^ £ £ * >: 4. a a J* '*.: ********>->^rY * .. ELEMENTS o F NATURAL HISTORY, AND OF CHEMISTRY: BEING THE SECOND EDITION OF THE ELEMENTARY LECTURES ON THOSE SCIENCES, FIRST PUBLISHED IN 1782, A N D N 0 W GREATLY ENLARGED AND IMPROVED, By the Author, M. DE FOURCROT, DOCTOR OF THE FACULTY OF MEDICINE AT PARIS, OF THE ROYAL ACADEMY OT SCIENCES, &C. &C. &C. TRANSLATED INTO ENGLISH. WITH OCCASIONAL NOTES, AND AN HISTORICAL PR%£&CE, BY THE TRANSLATOR.- '* **n* or •»■■ \ VOL. IV. a LONDON: //£ HINTED FOR G. G. J. AND J. ROBINSON, pater-noster.ro w. MDCCiXXXVIII. C-Ta-uj-Vo^eL CONTENTS to VOL. IV. PART III. The Vegetable Kingdom. CHAP. I. Concerning the Structure of Vegetables. - - Page i Chap. II. The Natural Philofophy of Vegetables. j Chap. III. Concerning Juices and Ex- tracts. - - 1 6 Chap. IV. Effential Salts. - 23 Chap. V. Concerning the Saccharine Matter. - - 31 Chap. VI. Concerning Gum and Mu- cilage. - - 43 Chap. VII. Of Fat Oils. - - 47 Chap. VIII. Concerning EfTential Oils. 58 Chap. IX. Concerning the Campho- rate Principle. - - - 61 Chap. X. Concerning the Spiritus Rec- tor. 66 Chap. XI. Of Inflammable Refinous Juices in general, and of Natural Balfams in particular. - ~ 73 Chap. XII. Concerning Refins. - 76 Chap. XIII. Gum Reiins. - 82 Chap. XIV. Of the pure Fecula of Vegetables. 92 Chap. XV. Concerning the Farina, and Starch of Corn. 97 a 2 Chap. ( iv ) Chap. XVI. Concerning Vegetable Co- louring Matters, and their Appli- cation to the Art of Dying. - 106 Chap. XVII. Concerning the Analyfis of Plants, by deftrudive Diftilla- tion, or a naked Fire. - 114 Chap. XVIII. Of Vegetable Coal, or Charcoal. - - - 122 Chap. XIX. Concerning the Fixed Salts, and Earths of Vegetables 130 Chap. XX. Concerning Fermentation in general, and the Spirituous Fer- mentation in particular. - 136 Chap. XXI. Of Ardent Spirit, or the Produd of the Spirituous Fernfen- tation. - - - - 148 Chap. XXII. Concerning Tartar. 178 Chap. XXIII. Of the Acid Fermen- tation, and of Vinegar. - 197 Chap. XXIV. Concerning the Putrid Fermentation of Vegetables. - 217 p A R. T IV. The Animal Kingdom. Chap. I. The General Charaders of Animals. - 222 Chap. II. Concerning Quadrupeds and Cetaceous Animals. - - 226 Chap. III. Concerning Birds. - 234 Chap. IV. Concerning Oviparous Qua- drupeds, and Serpents. - - 237 Chap. V, Of Fifties. - - 241 Chap, ( v ) Chap. VI. Concerning In feels. 246 Chap. VII. Of Worms. - - 255 Chap. VIII. The Functions of Ani- mals, from Man to the Polypus. 258 Chap. IX. Concerning the Chemical Analyfis of Animal Subflances in general. - - 279 Chap. X. Concerning the Blood. 288 Chap. XI. Concerning Milk. - 300 Chap. XII. Concerning F>it. 316 Chap. XIII. Concerning the Bile and Biliary Calculi. - 326 Chap. XIV. Concerning the Saliva, the Pancreatic Juice, and theGaf- tric Juice. - - - 333 Chap. XV. Concerning the Humours, or Animal Matters, which have not yet been examined ; fuch as Sweat, the Nafal Mucus, the Ce- rumen, Tears, the Gum of the Eyes, the Seminal Fluid, and the Excrements. - - 338 Chap. XVI. Concerning Urine. 342 Chap. XVII. Concerning Ammoniacal Phofphat, the Phofphat of Soda, and the Calculus in the Bladder. 353 Chap. XVIII. Of the Phofphorus of Kunckel. - 369 Chap. XIX. Concerning the Phofpho- ric Acid. - 383 Chap. XX. Concerning the Soft and White Parts of Animals, and their Mufcles. - - 391 Chap. ( vi ) Chap. XXI. Concerning the Bones of Animals. - - Page 400 Chap. XXII. Concerning different Subftances ufed in Medicine and the Arts, which are obtained from Quadrupeds, Cetaceous Animals, Birds, and Fifties. - - 407 Chap. XXfIL Concerning the Pro- duct of Oviparous Quadrupeds, Serpents, Infedts, Worms, which are ufed in Medicine and the Arts. 418 Chap. XXIV. Concerning the Putre- faction of Animal Subftances, 433 Elements T S NATURAL HISTORY, AND OF CHEMISTRY, dfc^cfrtifrtifrtifc<&tifctifrtifc&cfrc&<>& PART IIL The Vegetable Kingdom. CHAP, I. Concerning the Structure of Vegetables. EGETABLES are organized bodies, fixed at the furface of the earth, and pofleffing neither fen- Ability nor fpontaneous motion. They are diftinguifhed by their external ap- pearance and conftrudtion, and differ more particularly from minerals, in the circum- Vol. IV» A ftance 2 STRUCTURE OF ftance of their being nourished by introfuf- ception, and their elaborating the juices de- figned to increafe their bulk. They prefent phenomena, which depend on their organi- zation, and are called functions ; the prin- cipal of which is, their reproduction, by means of feed, or eggs, like animals. Vegetables differ from each other, i. By their magnitude : they are diftinguiihed into trees, fhrubs, herbs, moffes, &c. 2. By their places of growth : fome grow in dry, and others in moift grounds ; others in fand, clay, water, on the furface of ftones, or on other vegetables, &c. 3. By their fmell, . tafte, colour, &c. 4. By their duration : plants are perennial, annual, biennial, &c. 5. By their ufe, either as food, medicine, &c. A great number are ufed in the arts, fuch as dying, &c. others' are ufed merely for pleafure, ornament, &c. Vegetables, externally confidered, are formed of fix parts, or organs, deftined to perform peculiar functions. Thefe parts are the root, the ftem, the leaf, the flower, the fruit, and the feed. Thefe differ in form, texture, magnitude, number, colour, duration, tafte, &c. 1. The root is concealed in the earth, in water, or in the bark of other vegetables. It is either tuberous, or fibrous, or bulbous. Its direction is either perpendicular, or ho- rizontal 3 and its confiftence, as well as its form, VEGETABLES* 3 form, is fubjecl to great variations. Bo- tanifts diftinguifti them into feveral fpecies, and avail themfelves of thefe diftin&ions, as fpecific characters. 2. The Item grows out of the root, and fuftains the other parts. It is either folid, or hollow, ligneous or herbaceous, round, fquare, triangular, or having two acute angles, &c. The item comprehends the wood and the bark. The wood is diftinguifhed into wood, properly fo called, and fap. The bark coniifts of the epidermis, the pulp or veficular part, and the -cortical ftrata, or inner rind. The ftem is divided into branches, which have abfolutely the fame ftructure ; and the diverfity of this part very often ferves to eftabliih the diftincfive characters of the fpe- cies and varieties. 3. The leaves of vegetables are exceed- ingly varied. A By their form : they are oval, round, fagitated, haftate, oblong, elip- tic, cuneiform, &c. B By their polition on their ftem : they are either feffile, pe- tiolate, oppolite, alternate, ftellate, perfo- liate, vaginant, &c. C By their margin : they are either uniform, dentate, crenate, ferrate, repand, undulated, lacerated, trun- cated, &c. D By their fimplicity or com- pofition : compound leaves are formed, by the infertion of foliolas, or leffer leaves, and are then either digitate or conjugate, with either an odd or an even number of A a leaves. 4 STRUCTURE OF leaves. E By their pofition or place : they are radical, cauline, or floral. F By their colour, fmell, tafte, confidence, &c. Their ufe appears to confift in abforbing the elaftic fluids of the atmofphere, and exhaling dif- ferent kinds of air, according to circum- ftances. 4. The flowers are parts defigned to con- tain the organs of generation, and defend them till the fecundation is accomplifhed, at which time they fall. The flower is dis- tinguished into two parts : the external part ferves to inclofe and protect the internal part, whofe ufe confifts in reproducing the plant. The former comprehends the calyx, and the corolla. The calyx is external, and green. Linnsus diftinguifhes it into feven. fpecies -, namely, the perianthium ; the fpar- tha, or (heath ; the hufk ; the involucrum ; the amentum, or catkin ; the calyptra, or veil ; and the volva. The corolla is the coloured part commonly called the flower; it is either monopetalous, or confifting of one Angle piece; or polypetalous, confifting of feveral parts. The fyftem of Tournefort is founded on the corolla. The parts of the corolla are called petals. The organs in- cluded, and often concealed in plants, are the ftamina, and the piftils or fiyles. The ftamina are the male, or fecundating parts, and are almoft always more nunv -ous than the piftils. They confift of the filament, and VEGETABLES. 5 and the anthera. This laft, placed at the extremity of the filament, is a fmall bag, containing the fecundating powder. The piftil is in the midft of the ftamina : it is fometimes on another flower, or even on an- other plant; which circumftance occalions the diftin&ion of plants into male and fe- male. The piftil confifts of three parts ; the inferior part, which contains the embryo, and is called, in Latin, germen ; the fila- ment, which grows out of the inferior part, and is called the flyle; and its extremity, which is more or lefs dilated, is called ftigma. The fexual fyftem of Linnasus is founded on the number and pofition of the ftamina and piftils. Mr. De Juffieu has eftablifhed a* fyftem, founded on the infertion of the fta- mina above or below the germen, &c. 5. Flowers are fucceeded by fruits. Bo- tanifts diftinguilh {even fpecies ; the capfule, the iiliqua, the legumen, the conceptacu- lum, which becomes dry; fruits having ker- nels, fruits having pippins and berries, which remain fucculent. Thefe organs are defigncd to inclofe the feeds, and defend them from external agents. 6. The feed differs greatly in its form, magnitude, appendices, 6cc. It contains the plumula, or fmall plant ; the radicula, and the cotyledons. Thefe laft are two in number in moft vegetables ; but many fa- milies of plants have no more than one co- A 3 tyledon. 6 STRUCTURE OF tyledon. This part is to the grain, what the yellow and white of the egg is to the em- bryo bird ; it contains a proper nouriihment for the individual during the germination. Vegetables, confidered with refpedt to their internal parts, prefent five fpecies of veflels, or organs, which exift in all their parts; i, The common veflels, which con- duit the fap : they are placed in the central part of plants and trees, and rife perpendi- cularly, though with lateral bendings, fo as to form fmall vacancies between them. 2. The proper veflels, which convey the juices peculiar to each vegetable, fuch as the oils, gums, reiins, &c. They are placed beneath the bark, and appear in many places to be dilated into cavities, or refervoirs, which feem to be the excretory veflels. 3. The tracheae, or veflels through which air circu- lates : when a young green branch is torn afunder, they may be obferved of a fpiral form, refembling a cork-fcrew. They are often filled with fap. 4. The utricles, or fmall veflels, which contain a fecreted juice, and frequently colouring matter. They are placed in the middle of the ftem. 5. The veficular tiflue, which exhibits a feries of fmall cells, which leading horizontally from the pith, and crofling the fap veffels, and fill- ing the vacuities between them, are expanded beneath the epidermis, form a kind of foft covering, refembling the fkins of animals. The VEGETABLES, J The veficular tilTue of vegetables appears to anfwer to the cellular membrane of ani- mals. All the parts of vegetables confift of an aflemblage of thefe five kinds of veffels, each in particular being more or lefs numerous, dilated, contracted, &c. The differences in the form and texture of roots, items, leaves, &c. depend on this diverfity of number and difpofition. Malpighi, Grew, and Duhamel, have been the moft fuccefsful in their refearches into the natural hiflory of plants, and their works are the moft inftrudtive, with refped: to the internal formation of their feveral parts. CHAP. II. The Natural Philofophy of Vegetables. ^*pHE organs of vegetables, which we -* have concifely defcried in the forego- ing chapter, are defigned to perform feveral motions, which are called functions. Thefe functions are, i. The motion, or circulation of the fluids, 2. The alterations, or change of thefe fluids, by fecretion, A 4 3. The 3 STRUCTURE OF 3. The augmentation and developement of the vegetable by nutrition. 4. The exhalation of different fluids ela- borated in the organs of vegetables, and the inhaling of feveral principles con- tained in the atmofphere, by the fame organs. 5. The action of the air, and the ufe of this fluid in the veffels of vegetables. 6. The motion performed by fome of their parts. 7. The kind of fenfibility by which they endeavour to obtain the contact of fuch bodies as tend to promote the functions, fuch as light, &c. 8. And laftly, The various phenomena which ferve to reproduce the fpecies, and conftitute the generation of plants. We fhall confider each of thefe func- tions feparately. The principal fluid of vegetables, which is known by the name of fap, is contained in peculiar veffels, called the common veffels. Thefe veffels, which are placed in the middle of the ftem, and beneath the bark, are ex- tended from the root to the leaves and flow- ers. The fap which they conduct, is a co- lourlefs fluid, of an infipid tafte, and, like the blood in animals, becomes feparated into dif- ferent juices, for the nourifhment and fup- port of the feveral organs. It is very abun- dant VEGETABLES. 9 dant in the fpring, its prefence being then fhewn by the production of leaves and flowers. All the phenomena of vegetation, as well as experiments made by applying li- gatures about plants, mew, that it rifes from the root to the Hem and branches. But it is not fo well afcertained, that it de- fcends again towards the root, as fome phi- lofophers have affirmed. The valves ad- mitted to exift, by many botanifts, in the common veflels, have not been exhibited ; unlefs we may call by this name certain fibres, or hairs, with which their internal parts appeared to be lined, according toTour- nefort and Duhamel. Their regular mo- tion of this fluid is very far from refembling the circulation in animals. The fap, when conveyed into the utricles, and thence into the proper veflels, is elabo- rated in a peculiar manner : it produces dif- ferent faccharine, oily, mucilaginous fluids, which are emitted in confequence of an or- ganic procefs, and whofe evacuation feems to be an advantage to the vegetable, fince it does not receive any damage from a very confiderable occafional lofs of thofe matters. This alteration of the fluids, which is very obfervable in many organs, as in the necta- rium, at the extremity of the piftil, in the pulp of fruits, at the bafe of the calyces, and of many leaves, is produced intirely by that function, which in animals is called fecre- tion. 10 STRUCTURE OF tion. Guettard has carried this analogy {q far, as to defcribe glands of various forms at the bafes of the leaves of fruit trees, and towards the inner extremity of the petals of certain flowers. It is this fecretion which de- velopes the principle of fmell, the colouring matter, the combuftible fubftance, &c. But it differs very effentially from animal fecretion, which is intirely produced by the organiza- tion of the glands, which elaborate the ani- mal fluids ; whereas, in vegetables, the juices contained in the common veffels are more expofed to the contact of air, light, and the aftion of heat; and their fituation renders them capable of paffing through the proceffes of fermentation by means of thefe agents. The fap, while it remains in the cavities of the utricles, and of the veficular tunic, becomes thick, and more confident. This alteration renders it capable of adhering to the fides of the fibres, and of gradually aug- menting their dimenfions. Such is the me- chanifm of the nutrition of vegetables, their increafe of magnitude, and the developement of their parts. It greatly refembles the nu- trition of animals. The veficular tunic, and the utricles, have the fame conformation, and the fame ufe in both claries of organized beings. In both, they penetrate all their organs, eftabliihing an immediate commu- nication VEGETABLES. II nication between them, and in both they are the true feat of nutrition. Philofophical botanifts have long been convinced, that exhalations are emitted into the air from the furfaces of plants. The odo- riferous exhalation of leaves and flowers forms an atmofphere around vegetables, which ftrikes our fenfes, and which the contact of a body on fire is fometimes capable of in- flaming, as has been obferved with regard to the fraxinella. This exhalation appears to be a peculiar kind of inflammable gas. Experience has likewife fhewn, that many vegetables emit vapours which are mortal to fuch animals as remain long expofed to them. Such are the yew, and many trees, natives of hot countries. The experiments of Mr. Ingenhoufz have fhewn, that the leaves of all plants expofed to the light of the fun emit an invilible fluid, which con- fifis of true vital air, fimilar to that which is obtained from calces of mercury, &c. This property of leaves is intirely changed in the (hade, in which fituation they e- mit the cretaceous acid. This happy dif- covery, firft publilhed by Dr. Prieftley, fhews an unfufpedted property in plants, namely, that of purifying and renewing the air, by reftoring that portion of vivifying fluid which is continually deftroyed by corn- bullion, refpiration, &c. But at the fame time that vegetables continually emit vapo- rous 12 STRUCTURE OF rous fluids produced in the laft proceffes of vegetation, they likewife abforb many of the principles contained in the atmofphere. The lower furface of leaves abforbs the hu- midity of the dew, according to the expe- riments of Bonnet. Dr. Prieftley's experi- ments likewife prove, that vegetables abforb the gafes, which remain after combuftion and refpiration, and that vegetation is ftrongeF in air changed by thefe proceffes. The exhalation and inhalation at the furface of vegetables are confequently much more confiderable than was fuppofed before the time of the modern difcoveries. It even appears that the water abforbed by the in- ferior furface of leaves is decompoied ; that the bafe of inflammable air it contains is abforbed ; and that the pure air difengaged from the fuperior furface of the leaves is produced by the oxyginous principle con- tained in that fluid. The contact of the rays of the fun contributes greatly to this decompofition, as it does not take place in the fihade. Plants defended from the action of light, abforb water intirely without de- compofition, and become white, infipid, and foft; a much lefs quantity of coloured, com- buftible, or oily matter, being formed. The gafes abforbed by vegetables, are con- veyed into all their organs by the air veiTels, which in their ufe and ftru&ure refemble thofe of infe&s and worms. The air vef- fels VEGETABLES. I3 fels are not, however, appropriated folely to the circulation of elaftic fluids ; for they are obierved to be filled with fap, at thofe times of the year in which that fluid is moft abun- dant : a circumftance which conftitutes a great difference between them and the organs of refpiration, fo eftential to the exiftence of a great number of animals. From the theory of refpiration, which we have ex- plained in the hiftory of air, it is eafy to (hew why the temperature of vegetables does not exceed that of the air which furrounds them. It cannot be doubted, but that many parts of vegetables have an internal principle of motion ; in forne it is fo evident, as to be moft obvioufly diftinguifhed. Such is the motion of the feniitive plant, of the (la- mina of the Indian fig, of pellitory, &c. This motion feems to depend on the func- tion, which is known in animals by the name of irritability ; for it is excited by the action of a ftimulus, and has peculiar or- gans, which fome botanifts have compared to mufcular fibres. Ought we not to admit a fort of fenfibi- lity in plants, when we obferve them to turn their leaves and flowers towards the fun, and when we obferve that plants, in- clofed in wooden boxes, glazed on one fide, perforated, or merely thinner on one fide than the others, conftantly tend towards the tranf- 14 STRUCTURE OF tranfparent body, or the aperture through which the light pafles, or even towards the fide, which by its lefs thicknefs may admit a glimmering light ? Or may we not attri- bute this apparent fenfibility to the force of affinity, or tendency to combination, which exifts between vegetables with light ? It is well eftablifhed, that this fluid, either by percuffion or combination, affifts in produc- ing the colour, tafte, and combuftible property in plants; becaufe plants, which grow in the fhade, are white, infipid, aqueous, and con- tain no inflammable matter -, whereas vege- tables expofed, in the burning climates of the fouth, to the ftrong rays of the fun, be- come highly coloured, abound with bitter and refinous parts, and are eminently com- buftible. However ftrong we may fuppofe this affinity to be, we cannot conceive how it fhould be capable of exciting a motion fo confiderable in the branches and leaves of vegetables. We muft therefore neceftarily admit a peculiar kind of fenfation, or feel- ing, very different, it is true, from the fenfes of animals, by means of which vegetables give a preference to fuch fituations as are mod acteffible to light. The manner in which the fpecies are pro- duced, among vegetables, greatly refembles the generation of animals. The exiftence and union of fcxQS are neceffary in the great- eft number of plants. The labours of the celebrated VEGETABLES. 15 celebrated Linnaeus have difcovered a ftrong analogy between the organs deftined for this function in the two claffes of organic beings. The ftamina correfpond with thofe of the male fex, and the piftil is compofed of three parts, analagous to thofe of the genitals of female animals. The embryo is developed, by the a&ion of the fecundating powder, without which it is not capable of pro- ducing an individual, as is likewife daily obferved among birds. But befides this analogy, which need not be further purfued, vegetables are of a much Ampler ftrudture than animals ; and all their parts being com- pofed of the fame organs, each is capable of producing a new individual fimilar to itfelf. This is the reafon of the reproduction of plants, by means of fcions or flips, as well as the alteration of the fluids, by grafting, whether natural or artificial. There is like- wife another analogy, of modern difcovery, between vegetables and that clafs of animals which is reproduced, by diviflon into pieces, as the polypus, cruftaceous infedts, certain worms, &c. All the functions, which, taken together, conftitute the refemblance between vege- tables and animals, are fufceptible of alte- rations, which produce diforders. Thefe depend, moft commonly, , on the abundance or defed; of the fap, as well as its bad qua- lities, and are analogous to thofe which take . place % l6 JUICES AND EXTRACTS. place in animals. Their caufes, fymptoms, and cure, are alike referable to the general principles of medicine, and form a part of agriculture, which it muft be confeffed is not much advanced, but capable of great improvement, according to the plans of fe- veral celebrated authors. CHAP. I1L Concerning Juices and Extracts. 'T^HE fluids contained in vegetables, are ■* of two kinds ; the common, and the proper juices. The firft, confifts of the fap which is found in all plants. It is contain- ed in the common veffels, flows naturally out of their furface, but is more abundantly extracted by incifion. The fap is not merely an aqueous fluid, but contains falts, ex- tracts, and mucilages. When a certain quan- tity is defired, either for medical ufe, or philofophical inquiry, the plant is beat in a mortar, and prefled in a cloth, beneath a prefs, if neceflfary. Succulent vegetables give out their juice by fimple expreffion ; but thofe whole juices are vifcous, or in fmall quantity, require to be diluted with water, fucri as borage, and the PRINCIPLES OF VEGETABLES. 17 the dry aromatic plants. This fluid being ex- tracted, by ftrong prefTure, is found to contain a portion of the folids of the vegetables beaten fmall by the peflle, and confequently re- quires depuration ; which may be effected either, A By fubiidence, or filtration, when they are very fluid, as is the cafe with the juice of purflain, houfeleek, &c. B By white of egg, which collects the fecula, by coagulation, as is requifite with the juice of borage, nettle, &c. C By Ample heat, which coagulates and precipitates the pa- renchyma, as Mr. Baume advifes, with re- fpedl to juices that contain volatile prin- ciples, fuch as thofe of cochlearia, creffes, &c. The phial which contains the juice, being covered with a perforated paper, muft be plunged in boiling water, and taken out as foon as the juice is clarified. Immerfion in cold water brings it to a proper tempera- ture for filtration ; D By fpirit of wine, which coagulates the fecula; E By vegetable acids, as the London Pharmacopeia prefcribes for the juices of cruciform plants. The juices of plants hold in folution mat- ters which, when feparated from the aque- ous vehicle, form what, in pharmacy, are called extracts . Thefe are diftinguifhed into three kinds ; mucilaginous, faponaceous, and gum-refinous extracts. Mucilaginous extracts, are fuch as readily diffolve in water, fcarcely at all in fpirits of Vol, IVt B wine, l8 PRINCIPLES OF VEGETABLES. wine, and undergo fpirituous fermentation : fuch is the rob of goofeberries. prepared by evaporating the juice of that fruit. Saponaceous extracts are diftinguifhed by folubility in water, and partly in fpirit of wine ; they become mouldy, inftead of pafT- ing to the fpirituous fermentation. The juice of borage, when converted into an ex- tract, is of this nature; and thefe are ex- tracts properly lb called. Gum reiins diilblve in water, and in ar- dent fpirit ; they are inflammable, by virtue of the refinous principle they contain, and are not changed by expofure to air. The concentrated juice of wild cucumber, called elaterium is of this kind. Incifions are made in the fruit; and the expreffed juice being fuffered to clarify, by repofe, is eva- porated to drynefs on the water bath. Extracts of thefe three different fpecies are prepared, in the large way, by evaporat- ing the juices of feveral plants. Such, among others, are, i. The juice of acacia, imported from Egypt, where the fruit of this tree is mafh- ed, preffed, and the juice expofed to evapo- ration by the fun's heat. The infpiffated juice of floes is prepared, in Germany, by a fimilar procefs, and fold under the fame de- nomination. 2. Thatofhypociftis, which is made like the PRINCIPLES OF VEGETABLES. 19 the foregoing, with the fruits of this para- fitical plant. 3. Opium, an important medicine, whofe nature is not accurately known. It is ex- tracted from the white poppy, in Perlia, &c. where it flows through incifions made in the green capfules of the plant, in the form of a white juice, which dries into brown tears of the true opium. The opium of commerce is obtained, by preffure, from thefe capfules, moiftened with water, and comes to us in a dry form, in flat circular cakes, wrapped up in leaves, and mixed with many impurities. It is purified by folution in as fmall a quantity of water, as is fufficient to fufpend it -, which being filtered, or ftrained by ftrong preffure, is evaporated on the wa- ter bath. This is the extradt of opium, and contains a faponaceous extract, a folid effen- tial oil, an odorous, noxious, and narcotic principle, an efiential fait, and a glutinous matter. As the odorant, poifonous and nar- cotic principle, is often productive of bad effects, attempts have been made to obtain an extract of opium, deprived of this prin- ciple. Mr. Baume, who has made many experiments on opium, volatilized this prin- ciple, together with the efiential oil, and by that means feparated the refin, after a di- geftion of fix months. Bucquet has difco- vered, that the fame fedative extract, with- out the narcotic property, may be obtained B 2 by 20 PRINCIPLES OF VEGETABLES. by diftblving opium in cold water, and eva- porating the folution in a water bath. Lor- ry, who has made fuccefsful inquiries into this fubjedt, finds, that opium, after fer- mentation, affords a diftilled water, which has the fedative property, without produc- ing the bad effefts of the crude fubftance, and which he has ufed with great fuccefs. He obferves, that the odorous principle of this medicine cannot be deftroyed by any procefs. When the plants, from which it is pro- pofed to make extracts, are dry and ligneous, maceration, infufion, or decodlion in water, are employed, according to the ftate and na- ture of the materials : maceration is, in moft cafes, fufficient. Odoriferous plants muft be only infufed ; decoction extradls too much, and feparates the refinous parts, forming a thick fluid, which becomes tur- bid on cooling. Infufion may be ufed, in all cafes, according to the opinion of the moft celebrated phyficians and chemifts. Water extra&s various products from fe- veral plants. Thus the berries of juniper afford a mucilaginous extradl ; quinquina affords a faponaceous extradl, in fmall trans- parent fcales, refembling falts, if the eva- poration be made in very mallow veffels ; and rhubarb affords a gummy refinous fub- ftance. The faponaceous, or more properly the chemical PRINCIPLES OF VEGETABLES. 21 chemical extradt, appears to be a com- pound of oil and fixed vegetable alkali. The extracts, prepared in pharmacy, are very far from being all of the fame nature -, they are mixed with mucilage, effential fait, faccharine juice, refin, &c. From thefe confiderations, Rouelle, with the intention of illuftrating this part of medical chemiftry, diftinguifhed them into the three genera we have men- tioned : but the pure extract, reckoned a^ mong the immediate principles of vegetables, muft be confidered as a faponaceous com^ pound, pofTefiing peculiar properties, Extra&s are prepared in the large way, in commerce, by means of water. Such as, i. The yellow juice of liquorice, by the iirft infufion, or black, by ftrong deco&ion. This laft is burned, and contains a true char- coal. It is purified by folution in water, filtration, and evaporation, ufually with the addition of fome effential aromatic oil of annifeed, cinnamon, &c. 2. The cachou, or, as it is improperly called, Japan, earth, is prepared in the Eaft Indies, from the infufion of the feeds of a kind of palm, called areca, the infufion be- ing evaporated, and made into cakes. It is purified by folution in water, and evapora- tion, ufually with the addition of aromatics. Among the extracts prepared for medical ufea Rouelle particularly diftinguiflied thofe B 3 which 22 PRINCIPLES OF VEGETABLES. which are mixed with refin, by the names of gum refins, and refinous extracts. Gum refins do not burn without being firft dried, and appear to contain a larger quantity of extract, properly fo called, than of refin. The refinous extract burns much better, and appears to contain more refin, than extra&ive matter. This happy diftinc- tion mews, that the two fpecies confift fimply of mixtures of extract with different dofes of the refinous principle. They are not, therefore, with propriety called extracts, that name being applicable only to the fapo- naceous matter, whofe properties we mail proceed to enumerate. The pure extract differs from the forego- ing : it is a dry, folid, brownifh red, tranf- parent fubftance, which does not burn by itfelf, but emits plentiful fumes, and con- tains more or lefs efiential fait. Its tafte is almoft always bitter; by diftillation, it af- fords an infipid phlegm -, this phlegm, by a mild heat, becomes gradually of a deeper colour, and afiumes alkaline properties, as is obfervable with elaterium, extract of bo- rage, &c. The volatile alkali is formed by the heat; a fmall quantity of empyreumatic oil next comes over j and the coaly refidue, which is light and porous, contains alkali, and almoft always neutral fait. The extract, expofed to air, becomes mouldy, and attracts moifture 5 the fait it contains cryftallizing, and ESSENTIAL SALTS. 23 and feparating from the extractive part. They are often changed, and intirely decom^ pofed. It diflblves in water ; producing the appearance of a ftrong infufion. Acids de- compofe this folution, in the fame manner as they do foaps, and difengage a principle more or lefs oleaginous. Metallic folutions likewife feparate this principle, by double affinity. The chemical properties of extract have not been farther examined into j but thofe that are already known, evince, that it is with great propriety confidered. as a kind of foap. Extracts are ufed in medicine as aperitive, folvent, diuretic, ftomachic, remedies, and are daily adminiftered with great fuccefs. CHAP. IV. EfTential Salts, ^KE faline fubftances, held in folution A in the juices of plants or the water wherein they are infufed, are called effential falts of plants. They are obtained by cool- ing thofe fluids, which are iirft evaporated to the confiftence of fyrup. As thefe falts are impregnated with extractive, and flit matter, it is neqeflary to purify them with lime and B 4 whites 24 ESSENTIAL SALTS. whites of eggs. If thefe falts be of an acid nature, lime muft not be ufed, becaufe it would neutralize them, but pure white clay in powder. After the firft extraction, they are ftill very impure. Solution in diftilled water, and cryftallization, may be repeated till they become pure and white. The effential falts of plants are of a diffe- rent nature, and may be diftinguiihed into two claries. Class I. Of Effential Salts. The firft clafs includes thofe which re- femble mineral falts. The principal fpecies are, i. Cretaceous fixed alkalis, which are obtained from almoft all plants, by macerat- ing them with acids, as MargrafT and Rou- elle the younger have fhewn. The vege- table alkali is the moft common, but the mineral alkali exifts in marine plants. 2. Vitriolated tartar, or vitriol of pot-afh, in millefoil, in aftringent and aromatic plants, in fpurge flax, and in the mark of olives. 3. Glauber's fait, or vitriol of foda, from tama- rifk. 4. Nitre, from borage, turnfole, tobac- co, &c. 5. The febrifuge fait of Sylvius, or muriate of pot-afh ; and marine fait, or mu- riate of foda, in marine plants. 6. Selenite difcovered by Model in rhubarb. Many other falts will doubtlefs be found, refembling thofe of minerals, when a greater number ESSENTIAL SALTS. 25 number of plants {hall be accurately ana- lyzed. It has likewife been thought that volatile alkali; or rather ammoniacal chalk, exifts ready formed in cruciferous plants ; becaufe thefe plants, by diftillation, afford on the firft application of heat, a phlegm which holds a fmall quantity of that fait in folution. On this account the ancients called them animal plants; but Rouelle the younger has {hewn, that this fait does not exift ready formed in plants, but is produced by the re-adlion of the principles, which is promoted by heat. Mr. Baiime pretended that the volatile principle of cruciferous plants is nothing but fulphur. The vola- tile alkali obtained from thefe plants, arifes from the inflammable gas of the oil united to the mephitis contained in the vegetable, as Mr. Berthollet has {hewn. Various opinions have been held, refped:- ing the mineral falts found in plants. Some have thought, that thefe falts were conduct- ed from the earth by water, and pafled into the vegetables without alteration. Others have fuppofed, that the faline fubftances were formed by the procefs of vegetation. It is certain,- that two very different plants grow- ing in the fame foil, as for example, borage and millefoil, afford each the fait peculiar to itfelf , that is to fay, the borage affords nitre, and the millefoil vitriolated tartar. A fingle experiment, which has been much talked l6 ESSENTIAL SALTS. talked of, but never accurately made, would decide the queftion ; namely, to caufe fuch plants as afford a certain fait, for example, nitre, to grow in a quantity of earth, pre- vioufly lixiviated, and to water them with water containing marine or fome other fait. If the plants in thefe circumftances afford nitre, and not marine fait, it might be con- cluded that the fait does not pafs as fuch in- to the organs of plants, and that the proper fait is formed by the procefs of vegetation. Class II. Of Effential Salts. The fecond clafs contains fuch falts as are peculiar to vegetables. Thefe truly effen- tial falts always confift of an acid united vnith an alkali, or an oil. The acid is often in a difengaged ftate, though fometimes mafked by other fubftances. The effential acid falts of vegetables are found in a great number of plants, and arc afforded, in general, by all thofe which have a four tafte. Such are forrel, acid fruits, lemons, oranges, &c. The fait befl known of this kind in commerce, is called fait of forrel. It has been long fuppofed to have been obtained from the aleluia, or oxys, but it is now affirmed to be really extracted from a kind of forrel, in many parts of Switzerland, This fait has the form of white irregular cryflals^ ESSENTIAL SALTS. 2J cryftals, of a fharp tafte, and reddens blue vegetable colours, s It diifolves readily in water, and may be cryftallized without lofing its acid. By heat, in a crucible, it exhales a ftrong acid fmell, becomes carbonaceous, and takes fire. Its flame is blue, like that of fpirit of wine, and leaves, after its combuftion, a white fait, which with fpirit of fait forms marine fait. An ounce of this fait afforded Mr. Bau- me, by diflillation, three drachms and a half of an acid colourlefs liquor, with a flight fmell of marine acid. No oil paffed it over ; the refidue was coaly. This fait precipitates the nitrous folution of mercury, as does likewife the acid it affords by diftillation. The latter, mixed with the nitrous acid, did not diffolve. Bergman places the acid of forrel as a peculiar acid, in the thirteenth column of his table of affinities. He dif- fers from Baume in certain particulars, though he agrees with him in mod, as we (hall obferve ; but he has not faid whether his experiments were made with the fait of forrel in commerce, or the true eflential fait of forrel. The following is an extradt of his doctrine refpefting this fubftance. Salt of forrel confifts of the vegetable alkali, fuper- faturated with a peculiar acid. Scheele has contrived a very good method of obtaining this acid fait. He mixed the oxaline acid, faturated with volatile alkali, with a folution of «8 ESSENTIAL SALTS. of ponderous earth, in the nitrous acid : the principles of thefe two compounds were mutually changed by double affinity ; the ponderous earth uniting with the oxaline acid, forming the barytic oxate of Mr. De Morveau, and falling to the bottom, on account of its difficult foiubility. This pre- cipitated fait is decompofed by the vitriolic acid, which has a ftronger affinity with pon- derous earth than any fubftance hitherto known. The oxaline acid remains difen- gaged in the fupernatant liquor, which is decanted from the ponderous fpar, formed during the decompoiition. This fait feems to refemble the acid of fugar, rather than that of tartar, though it differs from both. For, when combined with a fmall quantity of vegetable alkali, it forms fait of forrel, fimilar to that of tartar ; but which decrepi- tates in the fire, melts, becomes almoft black, and capable of being totally decompofed by chalk : thefe properties are not found in tartar. A fmall proportion of vegetable alkali com- bined with acid of fugar, reiembles neither tartar nor fait of forrel. The oxaline acid prefers lime to alkalis; but it is yet uncertain whether ponderous earth and magnefia have likewife a ftronger affinity to this acid. It decompofes felenite j becaufe it has a ftronger affinity than the vitriolic acid with lime. If the oxaline acid be ftrongly heated, it is deftroyed j but it neither fwells, nor be- comes ESSENTIAL SALTS. 29 comes fo black, as the acid of tartar. By diftillation, it affords a phlegm, much more acid than that which is obtained from the latter by the fame procefs. From thefe cir- cumftances we may perceive, that the dif- ference between Bergman and Baume, con- fills in the former admitting the vegetable alkali as the bafe of this fait -, whereas the latter chemift found it to contain fait of foda. All the acid falts of plants have not yet been examined, though a great number is known. The acid of lemons may be fepa- rated from its mucilage by Handing, and concentrated by the a&ion of froft, as Mr. Georgius has ihewn ; or by evaporation, carefully conducted. It has been thought analogous to the acid of tartar, though its ftronger tafte feems to indicate a refem- blance with the oxaline acid. Stahl affirms this acid, faturated with crab's eyes, and digefted with a fmall quantity of fpirit of wine, gradually affumes the nature of vine- gar. Bergman obferves, that the acids of fpar, phofphorus, arfenic, borax, fugar, tartar, forrel, and lemons, refemble each other, in being fcarcely at all foluble when combined with earths ; and that they only become fo, by means of an excefs of acid ; a property which is not found in other falts. Yet felenite and ponderous fpar, two earthy falts, formed by the vitriolic acid, are fcarcely foluble in water. Fruits, 30 ESSENTIAL SALTS. Fruits, which are at firft four, and be- come fweet as they ripen, afford a fait, whofe acid is lefs developed than that con- tained in the foregoing fubftances. This fait feems to occupy the middle place between the very acid eifential falts, and the faccharine matter, and refembles the tartar of wine. It is obtained from apples, pears, quinces, tamarinds, &c. Rouelle the younger, has examined it carefully in many of thefe vege- tables. We mall fpeak more largely con- cerning it when we attend to the fpiritous fermentation. Modern chemifts feem inclined to think, that all the acids of four fruits differ from each other, and compofe particular fpecies. Bergman and Scheele are of this opinion. The latter fucceeded in cryftallizing the acid of lemons, by faturating the juice with chalk, and decompofing the fait by the ad- dition of vitriolic acid ; the acid of lemons is difengaged in the fupernatant liquor, and may be obtained in cryftals by evaporation and cooling. We mail hereafter fee, that this cryftallized acid differs from lemon juice, and does not afford the fame refult with the nitrous acid. CHAP, SUGAR. 31 CHAP. V. Concerning the Saccharine Matter. THE faccharine matter, which many chemifts coniider as a kind of eflential fait, is found in a great number of vegeta- bles, and may be properly ranged among their immediate principles. The maple, the birch, the red beet, the parfnip, the grape, wheat, &c. contain it. Margraff ex- traded it from moft vegetables. The petals of many flowers, and the nedtariums placed in thofe organs, elaborate a principle of this kind. The fugar cane, arundo faccharifera, con- tains it in larger quantities, and affords it more readily, than any other plant. The ripe canes are crufhed between two iron cylinders, placed perpendicularly. The ex- preffed juice falls on a plate beneath, and is called melaffes. It flows into a caldron, where it is boiled with wood-afhes and lime, and the fcum taken off. This boiling with afhes and lime is repeated in three other boilers, and converts it into fyrup. It is then ftrongly boiled with lime and alum ; and when it is fufficiently concentrated, it is poured into a veffel called the cooler. When 32 SUGAR* When it is cooled fo that the finger may be plunged into it without injury, it is poured into barrels placed over certain cifterns, and pierced at the bottom with many holes, flopped with canes. The fyrup becomes folid in the cafks, and part flows out through the holes into the cifterri beneath. The fugar in this concrete ftate is yellow and greafy ; it is called mufcovado. It is re- fined in the fugar iflands by boiling, and pouring into inverted earthen cones, called pans. That part of the fugar which is incapable of becoming concrete, runs through the aperture of the pan into a pot placed beneath. The bafe of the fugar loaves is taken away, and white fugar in powder is put in its place, and preiTed down ; the whole is then covered with moiftened clay. The water of the clay filtrates through the fugar, and carries with it a portion of the mother water, which runs out through the aperture at bottom, and is received in other pots. A fecond covering of clay is put on when the firft is dry, and the water is fuf- fered to filter through a fecond time ; after which, the loaves are carried to a flove to dry. At the end of eight or ten days thefe loaves are broken, and the powdered fugar is conveyed to Europe, where it is refined in- to fugar of different qualities. The procefs of refining confifts in boiling the fugar in lime-water, together with bul- locks SUGAR* 33 locks blood, taking off the fkim three or four times, and filtering the liquor, which is then poured into pans to make loaves. The loaves are covered with a ftratum of moiftened clay, and the water is thus filter- ed through the fugar, by the repeated ad- dition of a new ftratum of clay as the former becomes dry, until the fugar has acquired the requifite degree of whitenefs. The loaves of refined fugar are then conveyed into a ftove, and at the end of eight days are wrapped in paper, and tied up for fale. The remaining fyrup, which cannot be cryf- tallized, is fold under the name of melafTes. All chemifls formerly fuppofed, that thefe different operations feparate a fat matter from fugar, and by that means render it fufceptible of cryftallization. Bergman thinks, that lime ferves to deprive it of that excefs of acid> which prevents its taking the folid form* As it is quickly evaporated during the whole procefs, it takes the form of a granulated and irregular mafs, in the fame manner as we have before obferved with refpedt to the vitriol of zink. Sugar confifts of a peculiar acid united to a fmall quantity of alkali, and much fat mat- ter. It cryftallizes in hexahedral truncated prifms, and in this ftate is called fugar-candy. By diftillation, it affords an acid phlegm, and a few drops of empyreumatic oil. The refidue is a fpungy light coal, which con- Vol. IV. C tains 34 SUGAR* tains a fmall quantity of vegetable alkali. This fait is inflammable. On hot coals it melts, and fwells up very much, emits a penetrating vapour, and becomes con- verted into a brown yellow matter called caramel. It is very foluble in water, to which it gives much confiftence, and con- ftitutes a kind of mucilage, called fyrup. Syrup, diluted with water, is capable of fer- mentation, and affords ardent fpirit. Bergman has obtained, from all faccha- rine matters, efpecially fugar, an acid of a peculiar nature. For this purpofe, one part of fugar in powder is mixed in a retort with fix parts of aqua fortis, and a gentle heat is applied. The evaporation is continued for fome time after the red vapours have ceafed. The folution being fuffered to cool, affords white cryftals in the form of four-fided needles or prifms, terminated with dihe- dral fummits. The decanted liquor treated a fecond time with three or four parts of the fame nitrous acid, affords, by a new cryftal- lization, prifms of the fame form. The ope- ration is again repeated on the fecond mo- ther water. An ounce of white fugar, by this procefs, affords about three drachms of prifmatic fait; which is diffolved in hot water, and cryftallized by cooling, in order to obtain it in a ftate of purity. The acid of fugar has a very penetrating four tafte. Diluted with water, it forms aa SUGAR. 35 an agreeable acid liquor. It reddens all blue vegetable colours. Expofed to a mild heat, it becomes opake, and falls into a powder, refembling efflorefcence, and lofes three- tenths of its weight, by the evaporation of the water which enters into its cryftals. This water may be collected by the ufual apparatus for diftillation. A ftronger heat fufes the acid, and gives it a brown colour; an acid phlegm paffing at the fame time into the receiver, fimilar in all its properties to the fait itfelf. Part fublimes in the form of a white cruftj and the retort contains fcarcely any refidue. The refidue is grey or brown, and does not amount, according to Bergman, to more than the fiftieth part of the original matter. A very confiderable quantity of a gafeous fub- ftance is likewife afforded in this operation : half an ounce of the acid of fugar afforded Bergman ioo cubic inches of gas, half of which was cretaceous acid, and the other half inflammable gas, which burned with a blue flame. The Abbe Fontana, who repeated this experiment, obtained from an ounce of the cryftallized fait, 432 inches of gas, of which one third was cretaceous acid, and the reft inflammable gas, mixed with com- mon air. On repeating the fame experi- ment, I had a refult nearly agreeing with that of the latter chemift. The moft Angu- lar circumftance is, that the fublimed por- tion diftilled for two more fucceffive times C 2 affords 36 SUGAR. affords no coaly matter, but only a refidue of a whitifh grey colour. This fait heated in an open fire, emits a very penetrating vapour, and leaves a reiidue which is perfectly white. The acid of fugar expofed to the air, ef- florefces in procefs of time. Cold water diffolves half its weight of this fait ; but boiling water diffolves double the quantity. The fait cryftallizes as it cools. The acid of fugar diffolves the bafe of alum. The evaporated folution affords a yellowifh, tranfparent, fweet, aftringent, matter, which becomes moift in the air, and reddens turnfole. This fait boils up in the fire, lofes its acid, and leaves the clay of a brown colour. It is decompofable by mineral acids. The acid of fugar, combined with ponde- rous earth, forms a fait fcarcely foluble, which affords angular cryftals, when the acid is in excefs. Hot water, by carrying off this excefs, renders them opake, pul- verulent, and infoluble. When combined with magnefia, it affords a white fait in powder, decompofable by the fparry acid, and by ponderous earth. Saturated with lime, the acid of fugar af- fords a pulverulent (alt infoluble in water, and not decompofable but by fire ; becaufe the affinity of this acid with lime is fuch, that it takes it from every other. Bergman, confequently, SUGAR. 37 confequently, propofes the acid of fugar as a teft to difcover the prefence and quantity of lime contained in mineral waters, whe- ther difengaged, or in combination with any acid. This fait turns fyrup of violets to a green. The acid of fugar unites with the vege- table alkali, and may be cryftallized, pro- vided either of the principles be in excefs. This fait, which is very foluble in water, is decompofable by the action of fire, and by the mineral acids. Combined with two parts of foda, the acid of fugar forms a fait of difficult folubi- lity, which dilfolves more readily in hot than cold water, and turns fyrup of violets to a green. With the volatile alkali it affords an am- moniacal fait, which by flow evaporation, cryftallizes in quadrilateral prifms decom- pofable by fire, and convertible into creta- ceous ammoniacal fait, formed by the de- ftrudrion of the faccharine acid. f The acid of fugar is foluble in the mine- ral acids. It gives a brown colour to oil of vitriol, and js decompofed by fmoking fpirit of nitre. In general, it combines more readily with metallic calces than with metals. i. With white arfenic it forms very fufi- ble, volatile, prifmatic cryftals, decompof- able by heat. C 3 2. With 38 SUGAR. 2. With cobalt, a pulverulent fait of a light rofe colour, and difficultly foluble in water. 3. With calx of bifmuth, a white fait in powder, of difficult folubility. 4. With calx of antimony, a fait in cryf- talline grains. 5. With nickel, a white or greenifh yel- low fait, of difficult folubility. 6. With manganefe, a fait in a white powder, which becomes black by heat. 7. With zink, which it diffolves with ef- fervefcence, it forms a white pulverulent fait. 8. With calx of mercury, a white pulve- rulent fait, which becomes black by the contidt of light. This acid decompofes the vitriol and nitre of mercury. 9. It at firft blackens tin, which after- wards becomes covered w^ith a white pow- der. The fait it forms with this metal is of an acrid tafte, and by a wrell-condudted evaporation, cryftallizes in a prifmatic form. If quickly evaporated, it affords a tranfpa- jent mafs refembling horn. 10. It tarnifhes lead, but diffolves the calces much more readily than the metal it- felf. The faturated liquor depofits fmall cryftals, which may likewife be obtained by pouring the acid of fugar into a folution of the nitre, or the muriate of lead, as well as into the acetous folution of that metal. II. It 6UGAR. 39 ii. It attacks iron filings, and produces inflammable gas. This folution is ftyptic, and affords prifmatic cryftals, of a greenifh yellow, decompofable by heat. The faifron of Mars, united to this acid, prefents a yel- low powder, fimilar to that which is ob- tained by pouring the fluid acid cjf fugar into a folution of martial vitriol. 12. It acts on copper, and completely dilfolves the calces of that metal, forming a fait of a light blue colour, and of difficult folubility. This fait may likewife be ob- tained by precipitating the folutions of cop- per in the vitriolic, nitrous, muriatic, and acetous acids, by the addition of the acid of fugar. 13. The calx of filver, precipitated by vegetable alkali, is fparingly dirTolved in this acid. The beft manner of procuring this fait, which Bergman calls faccharated filver, is to precipitate the nitrous folution of this rnetal by the acid of fugar : a white preci- pitate is formed, fcarcely foluble in water, which becomes brown by the contact of light. 14. This acid has fcarcely any action, an the calx of gold. 15. Laftly, it diflblves the precipitate of platina, made by foda. This folution is yellowifh, and affords cryftals of the fame colour. Such are the phenomena defcribed C4 by 40 SUGAR, by Bergman, refpe&ing the combinations of the acid of fugar with metallic fubftances. It may be fuppofed, from the procefs of this celebrated chemift for obtaining the acid of fugar, that this fait is produced from the nitrous acid made ufe of. Bergman does not think that this opinion is admiffible, becaufe the acid of fugar has none of the properties of that of nitre, but on the con- trary, differs from it in all its combinations. The nitrous acid does not, in fail, appear to enter into the acid of fugar ; but the great quantity of nitrous gas emitted in this pro- cefs, fhews, that the fpirit of nitre is de- compofed. Now, fince the nitrous acid, according to the experiments of M. Lavoi- fier, does not afford nitrous gas, but in pro- portion as it lofes the bafe of pure air, it appears that a part of its oxyginous principle combines wTith the combuftible matter of the fugar, to form the acid obtained. We have (ttn already, that the production of the arfenical acid, and of the dephlogifticated muriatic acid, may be explained in this manner. Though, at the time of the firft difcovery of this acid, it was thought that the faccha-r rine principle was neceffary to its formation, it is at prefent known, that a great number of vegetables, which are not faccharine, afford it in greater or lefs abundance ; fuch are gums, ilarch, vegetable glutep, fait of forrel, le- mon SUGAR. 4X mon juice, fpirit of wine, and many animal matters, as Mr. Berthollet has difcovered. Among thefe fubftances, thofe which pro- duce the greateft quantity of this peculiar acid, by the a&ion of fpirit of nitre, are fuch as do not afford fugar. Pure fugar did not afford Bergman more than one-third of its weight of acid ; and Mr. Berthollet obtained more than half from wool. It feems, therefore, as M. De Morveau thinks, that this acid is formed by the union of a peculiar attenuated oil, which exifts in all organic fubftances, and is the fame through- out ; and that confequently the name of faccharine acid is improper. Mr. Scheele has obferved, that the acid of lemons, cryf- tallized by the procefs defcribed in the fore- going chapter, does not afford faccharine acid, by treatment with nitrous acid, though lemon juke itfelf affords it. The vitriolic acid, employed for the purification of this acid fugar, feems, therefore, to decompofe the oil which forms the bafe of the faccharine acid. Sugar is very extenfively ufeful. It is a food which, taken in too large a quantity, is capable of heating the animal fyftem. It is very much ufed in pharmacy, where it is the bafe of fyrups, lozenges, and other pre- parations. It is very ufeful, as a medium to favour the folution or fufpenfion of refins, oils, &c. in water. It preferves the juices of 42 SUGAR. of fruits, after they are reduced into a jelly. It may even be confidered as a medicine, fince it is incifive, aperient, flightly tonic, and ftimulant ; and there are, accordingly, inflances of diforders, arifing from obftruc- tions, which have been cured by the ha- bitual ufe of fugar. Certain juices, which flow out of plants, have a faccharine tafte. Manna and nedtar are of this kind. Manna is produced by the leaves of the pine, the oak, the juni- per, the willow, the fig-tree, the maplea &c. The afh, which is very abundant in Calabria, Sicily, &c. affords the man- T)a in commerce. It flows naturally from thefe trees, but is much more abundant- ly obtained by making incifions in their bark. That which is collected on chips of wood, or final 1 flicks, introduced into the artificial apertures, forms a kind of ftalactites, peiforated within, and called manna in the tear. Manna, in flakes, flows on the bark, and contains fome impurities. The inferior, unftuous fort, contains many foreign fub- ftances, and confifts of the refufe pieces of the two former kinds : it is always moift, and frequently adulterated. The tafte of manna is fweet, and flightly naufeous. The manna afforded by the larch tree, which abounds in Dauphiny ; and that of the alhagi, which grows in Perfia, (Hedyfarum Linn.) in the neighbourhood of Tauris, are not ufed : MUCILAGE* 43 ufed : the latter bears the name of tereniabin. Manna is foluble in water, and affords, by diftillation, the fame products as fugar. Treated with lime, and white of eggs, it affords a fubftance refembling fugar ; and by the procefs already defcribed with the ni- trous acid, it affords an acid of the fame nature as is obtained from fugar. It is ufed as a purgative, in the dofe of from one to two, or three ounces ; or in the dofe of a few drachms, diluted, as an al- terative. 3S£ CHAP. VI. Concerning Gum and Mucilage. ANOTHER kind among the proper juices of plants, is that called gum, or mucilage. This fubftance is very abundant in the vegetable kingdom. It is found in a great number of roots; the young fhoots, and new leaves, contain it in large quantities. This principle may be known by its vifcous and ad- hefive quality, when thefe parts are crufhed between the fingers. At the time of the year when the juices are moft abundant, it natu- rally exfudes through the bark of trees, and thickens at the furface into gum. Gum is foluble 44 MUCILAGE. foluble in water, to which it gives a thick and vifcous confiftence. This folution, known by the name of- mucilage, becomes dry, tranfparent, and brittle, by evapora- tion. Gum burns without any fenfible flame; it melts, and boils up on hot coals ; by dis- tillation, it affords much acid phlegm, a fmall quantity of thick and brown oil, and cretaceous acid, in the ftate of elaftic fluid. Its coal is very bulky, and contains a fmall quantity of the fixed vegetable alkali. Three kinds of gum are ufed in medicine, and in the arts. i . Gum, which flows from the apricot, pear, plumb trees, &c. It is white, yellow, or reddifh ; and when well felefted, may be applied to the fame ufes as other gums. A kind of gummy juice, of a beautiful yellow colour, flows from the elm, and is fome- times fnund in confiderable quantities on its bark. I find this gum to be infipid, foluble, vifcous, and to poffefs all the characters of juices of this nature. 2. Gum arabic, which flows from the acacia in Egypt and Arabia. Gum fenegal is of the fame nature : it is ufed in medicine as a foftening and relaxing remedy ; it gives confiftence to crayons, and is ufed in feveral arts. 3. The gum tragacanth, which flows from the adragant of Crete; tragacantha cretica. It MUCILAGE. 45 It is adminiftered in the fame cafes as th foregoing. Its folution is fomewhat thicker and it requires more water to diffolve it than the other gums. Vifcous flakes are depo- fited from its folution. Mucilages, of the fame nature as gums, are obtained from many plants. The roots of mallows, the greater comfrey, the bark of elm, linfeed, the feed of quinces, &c. afford vifcous fluids, by maceration in water, which, by evaporation, leave true gums. The deco&ion of thefe plants is fubftituted, in medicine, inftead of gums. All thefe fubftances, chemically confider- ed, feem, at firft fight, to be bodies not much compofed, fince chemical experiments often exhibit fubftances, which, by their gelati- nous form, feem to refemble gums and mu- cilages. Yet, from thefe vegetable products, which feem to conflitute an excrementitious humour, are obtained water, liquid acid, cretaceous acid, an oily principle, and fixed alkali, united to a coaly refidue. This re- fidue contains likewife a fixed earth, whofe nature is not yet known. When gums and mucilages are treated with the nitrous acid, they afford a cryftal- lized acid, of the fame nature as that which is improperly called acid of fugar. It ap- pears, therefore, that they contain the oily principle, whofe combination with the oxy- ginous 46 MUCILAGE. ginous principle conftitutes this fpecies of acid. The analogy between mucilage and faccha- rine matters, is likewife obfervable in the fumes of burned gum, which in fmell refem- ble that ofyalomel, as well as by the nature of the produces both afford by diftillation, and the poroiity and lightnefs of their refidual coal. Among fruits which become faccharine, there are fome, as for example, apricots, pears, &c. from which, before the time of their maturity, a true gum exfudes. The kind of dry mucilage, which we fhall hereafter defcribe, under the name of amylaceous fe- cula, is converted into faccharine matter by germination. Thefe fafts, and many others which might be urged, fhew, that there is a ftrong refemblance between fugar andgilm. The inlipid and gummy mucilage may per- haps pafs to the ftate of fugar, by a kind of fermentation. If the fad: were eftablifhed, it would be proper to place this fermentation before that which Boerhaave has diftin- guifhed by the name of fpirituous ; and it would always precede it, whether in the procefs of vegetation, or in thofe operations which are artificially made to produce the faccharine tafte in barley, &c. CHAP. oils. 47 CHAP. VII Of Fat Oils. O ILS are proper juices of a fat and unftuous nature, either folid or fluid, indiffoluble in water, combuftible with flame, and volatile in different degrees ; they are contained in the proper veflels, or in pecu- liar veficules. Thefe fubftances are found in two ftates in vegetables ; either combined with other principles, as in extracts, muci- lages, &c. or at liberty. Our attention mult at prefent be directed to the latter. Chemifts have fuppofed the exigence of a fimple oily principle, as well as of a pri- mitive fait. This oily principle, combined with different fubftances, and modified by thefe combinations, conftituted, according to them, the different fpecies of oils obtained in the analyfis of vegetables. The charac- ters attributed to this fimple and primitive oil, were great fluidity and volatility, neither colour nor fmell, combuftibility with flame and fmoke : it was faid to be incapable of uniting with water, and to confift of an acid combined with an earth and phlogifton. It 4S FAT OILS. It is certain that oil?, in their decompofi-* tion, always afford a fmall quantity of acid, and much inflammable gas ; the earth forms but a fmall part, as they leave but an incon- fiderable quantity of fixed and coaly refidue. This notion refpe&ing the oily principle, mull; be confidered as a mere hypothefis. Oils are never formed but by organic bodies, and all fubftances in the mine- ral kingdom, which prefent oily characters, have originated from the acftion of vegetable or animal life. It is even very probable, that they are only formed in vegetables, and that they pafs without alteration into animal fubftances. The oily juices of vegetables are diftin- guifhed into fat oils and effential oils. Fat oils are very undtuous ; their tafte is commonly mild and infipid, and they have no fmell ; they are not volatilized but by a heat fuperior to that of boiling water, and do not take fire till heated fufficiently to volatilize them. The wick which is ufed to burn fat oil in lumps, anfwers this purpofe ; it heats the oil to fuch a degree, as volatilizes it. Moft fat oils are fluid, and require a con- fiderable degree of cold to congeal them ; others become folid by a very flight degree of cold ; and others again are almoft always folid : thefe laft are called butters. Fat oils are not emitted from the furface of vegetables, but are contained in~the ker- nels, FAT OILS. 49 ncls, the pippins, and emulfive feeds* They are extracted by breaking the cellules by which they are enclofed $ that is to fay, by pounding and preffure. Fat oils expofed to air are changed, and become rancid ; their acid becomes develop- ed, and they lofe their properties, at the fame time acquiring others, by which they more nearly refemble effential oils. \ Water and fpirit of wine, by warning off this dif- engaged acid, deprive them of their ftrong talTe, but never reftore their original ftate. Mr. Berthollet has difcovered> that fat oils thinly fpread on the furface of water, and expofed to the air, become thick, and refemble wax. This appears to arife from the abforption of the bafe of vital air. By diftillation they afford an acid phlegm of a penetrating fmell, a light oil, adenferoil, and a large quantity of inflammable gas mixed with cretaceous acid. The quantity of refidual coal is not abundant. By rediftilling thefe, more phlegm, and an oil which becomes light- er each time, are obtained. This is known by the name of philofophical oil ; the alche- mifts prepared it by diftilling, for feveral fuc- ceflive times, an oil with which they had im- pregnated a brick. It is not exactly known how far this decompofition may be carried, though it is faid that fat oil may this way be reduced into the difengaged inflammable principle, acid, phlegm, air, and earth. Vol. IV. D Water Founded 1813 II So ^J/AT OILS. Water docs not produce any change in fat oils in the cold, but it purifies them, by carrying off part of their mucilage, which is likewife precipitated during their com- buftion, and is thecaufe of their property of fermenting and becoming rancid. It is well known, that water thrown on burning oils, caufes them to give a ftronger flame, inftead of extinguishing them. This depends on the vital air afforded by the decompofition of the water, which affords the bafe of vital air. When the vapour of the flame of burning fat oil is collected in a chimney, terminated by a worm pipe, a large quan- tity of water is obtained : whence it fol- lows, that this immediate principle of vege- tables contains an aqueous inflammable gas. Fat oils do not combine with filiceous earth : with clay they form a foft pafte ufed in chemiftry, by the name of fat lute. By particular procefTes they combine with magnefia, which reduces them to a faponace- ous ftate. Lime unites with oils, but not in a very evident manner when the fubftances are immediately applied to each other. Pure alkalies combine readily with fat oils, and produce a compound called foap. To prepare this compound, oil of olives, or of fweet almonds, is triturated with a concentrated lixivium of foda, rendered cauf- tic FAT OILS. 51 tic by lime, and known by the name of foap lye. The mixture becomes thick in a few* days, and is converted into the foap ufed in medicine. The foap of commerce is made by boiling the lixivium with rancid oil ; it is then white, but is marbled by martial vitriol. Green foap is made with the marc of olives and pot afh. Soap is foluble in pure water : heat de- compofes it, and difengages phlegm, oil* and volatile alkali produced from the fix- ed alkali and the oil ; the coal contains much fixed alkali. This artificial compofi- tion of volatile alkali feems to prove, that fixed alkalies contain mephitis, which re- acts on the inflammable gas of the oil. Lime-water decompofes foap, according to the obfervation of Mr. Thouvenel ; an infoluble calcareous foap is then formed, which is depofited in grains. Acids poured on foap difengage the oil, but fomewhat altered. The volatile alkali does not combine with fat oils without difficulty; yet, by long trituration the mixture becomes opake, and rather more conliftent. Fat oils unite with acids, and form pecu- liar foaps, when the acid made ufe of is weak. Meiirs. Achard, Cornette, and Mac- quer, have made experiments refpecting thefe compounds. Mr. Achard added concentrat- ed vitriolic acid, by fmall portions, to fat oil. D a This $2 FAT OILS. This mixture being continually triturated, becomes at length converted into a brown mafs, foluble in water and fpirit of wine. The oil obtained from this foap by alkalies, as well as by diftillation, is always more or lefs concrete. Mr. Macquer advifes, in making this foap, to pour the acid on the oil ; but he obferves, that an acid foap made in this manner, is fcarcely foluble in water. The foap which is prepared by triturating common alkaline foap with oil of vitriol, is more foluble. The concentrated vitriolic acid renders fat oils black, and caufes them to refemble bitumens. This phenomenon appears to arife from the re-aftion of the in- flammable gas of the oil on the oxyginous principle of the vitriolic acid. The fuming nitrous acid immediately changes fat oils to a black colour, and in- flames fuch as are of a drying nature. Thofe which do not dry cannot be inflamed, but by a mixture of fpirit of nitre and oil of vitriol, as P.ouelle the elder has fhewn in his Memoirs on the Inflammation of Oils, print- ed among thofe of the Academy for the year 1747. The muriatic and cretaceous acids, act but weakly on fat oils ; the former, however, in a concentrated (late, combines with them to a certain degree, according to Mr. Cor- net. The dephlogifticated muriatic acid thickens them much, and appears, by the abforption FAT OILS. 53 abforption of its oxyginous principle, to convert them into a fubftance nearly refem- bling wax. The action of the other acids on fat oils, is not known ; thefe oils do not appear to combine with neutral falts. Many of the latter, more efpecially the calcareous falts, decompofe alkaline foaps. In this decom- pofition, efpecially that effected by the vi- triols of lime and magneiia, which are fre- quently contained in water, the vitriolic acid unites with the fixed alkali of the foap, and forms vitriol of foda ; the lime or the magnefia combines with the oil, and forms a kind of foap fcarcely at all foluble, which floats in whitifh curd-like maffes on the fur- face of the water. This is the caufe of the common appearance produced by hard waters, when attempts are made to ufe them with foap. The action of inflammable gas on fat oils has not yet been examined. Fat oiis diffolve fulphur in a boiling heat, and this folution is of a deep brownifh red colour, of a very fetid fmell, and gradually depofits fulphur in the cryftalline form. When this combination is diftilled, the ful- phur is totally decompofed, and is no where found. This experiment well deferves.to be carefully repeated. Sulphureous gas is like- wife obtained in this decomposition. D 3 Fat 54 FAT OILS, Fat oils do not appear capable of uniting with pure metallic fubftances, excepting copper and iron, on which they have a coa- fiderable action. But they combine with metallic calces, and form thick, concrete combinations, of a foapy appearance, as may be obferved in the preparation of unguents and plafters. Thefe preparations have not yet been chemically examined'; it is only known, that certain metallic calces are re- duced in the formation of plafters ; as for example, the calces of copper and lead, &c. In docimaftic operations, fat oils are ufed to reduce metallic calces. Mr. Berthollet de- fcribes an ingenious and fimple procefs, for immediately combining a fat oil with any metallic calx, in the faponaceous form. It confi'fts in pouring a folution of foap into a metallic folution ; the acid of the latter feizes the fixed alkali of the foap, and the metallic calx is precipitated in combination with the oil, to which it communicates its colour. In this manner a beautiful green foap is formed with vitriol of copper, and a brown foap with vitriol of iron ; thefe compounds may perhaps be ufeful in paint- ing. M. Scheele has difcovered, that by combining oil of fweet almonds, of olives, of rape, or of linfeed, with the calces of lead, and adding a frnall quantity of water to the mixture, a fubftance is feparated, which he calls the fweet principle. By evaporating FAT OILS. $5 evaporating the water, this principle is ob- tained, of the confidence of fyrup ; by a ftrong heat it takes fire ; part is volatilized in the diftillation without burning; the refi- dual coal is very light. The fweet principle does not cryftallize, nor does it appear fufcep- tible of fermentation; nitrous acid diftilled four times from it, produces acid of fugar. This principle appears to be a kind of muci- Iase- Fat oils diflblve bitumens, and in particu- lar amber, but they require the afiiftance of heat. Thefe combinations are a kind of fat varnifh, which does not become dry with- out difficulty. Fat oils may be diflinguifhed into three genera. The firfl comprehends pure fat oils, which congeal by cold, thicken flowly, form foaps with acids, and do not take fire by the ni- trous acid, unlefs oil of vitriol be likewife ufed. t i. Such are oil of olives obtained from the pulp of that fruit, crufhed between two mill-ftones, and prefled in facks made of rufhes. The firfl produd: is called virgin oil ; that which is obtained from the marc, moiftened with water, is lefs pure, and ip fits a fediment. The oil of unripe olives is the oleum omphacine of the ancients. Oil of olives freezes at 10 degrees below zero, on Reaumur's thermometer, or ten de- D 4. grees 56 FAT OILS. grees and a half above zero, in the thermo- meter of Fahrenheit, and does not become rancid in lefs than about twelve years. 2. Oil of fweet almonds extracted with- out heat, becomes quickly rancid -, it does not freeze till its temperature is reduced to 6 degrees below o of Reaumur's fcale, or 17 and a half of Fahrenheit. 3. Oil of rape obtained from the feeds of a kind of cabbage called colfa. 4. Oil of ben, extracted from the ben nut, from Egypt and Arabia; it is very acrid, inodorous, and freezes very eafily. The fecond genus comprehends drying oils, which foon become thick, do not con- geal with cold, are inflamed by the nitrous acid alone, and form a kind of refin with vitriolic acid. 1. Such are linfeed oil, obtained by pref- fure from linfeed. It is ufed in oily var- nifhes, and in painting. 2. Nut oil applied to the fame ufe. 3. Oil of poppy feeds, which is not at all narcotic, as the Abbe»Rozier has clearly fhewn. 4. Oil of hemp feed, which is very drying. In the third genus we comprehend con- crete fat oils, or butters, among which we may diftinguifh the following. I. Butter of cocoa, obtained from the chocolate nut : four fpecies of cocoa are diftinguiflied 1 FAT OILS. 57 diftinguifhed ; the large and fmall caracca, the berbice, and that of the iflands. The butter is extracted by roafting and fubfequent ebullition in water, and is purified by melting with a gentle heat. 2. The cocoa nut affords a butter of the fame kind. 3. The wax of vegetables is of the fame kind, excepting that it is more folid ; it comes from China, where it is made into yellow, green, or white candles, according to the manner in which the wax is extracted. The catkins of birch and poplar, afford a fmall quantity of this kind of wax. That of Louifiana is more abundant ; M. Berthol- let quickly bleaches it with the dephlogifti- cated marine acid. The ufe of fat oils in the arts, and in me- dicine, is very extenfive. They are medi- cally prefcribed as relaxing, foftening, and laxative remedies ; fome are even purgative, as the oil of Ricinus, or PalmaChrifti, which has been likewiie difcovered to poffefs the property of deftroying and evacuating the folitary worm. They enter into many me- dical compounds, fuch as balfams, unguents, plafters, &c. they are often ufed as food, on account of the mucilage they contain. C H A P. 5S ESSENTIAL OILS* CHAP. VIII. Concerning Effential Oils. ESSENTIAL oils differ from fat oils, by the following characters : Their fmell is ftrong and aromatic : Their vo- latility is fuch, that they rife with the heat of boiling water : and their tafte is very acrid. They are likewife much more combuftible than the fat oils. Thefe oils exift in moft ftrong fmelling plants. They are either contained in the whole plant, as in the Bohemian angelica, or in the root only, as in ftarwort, the iris, the white dittany, and the kidney-wort, &c. ; or in the ftem, as in the woods of fandal, faffa- fras, pine, &c. or in the bark, as in cinna- mon. In fome, the leaves only contain it, as is obferved in balm, peppermint, worm- wood, &c. in other plants it is found in the calices of the flowers, as in the rofe, and lavender. The petals of camomile and orange flower abound with it. In others again, it is contained in the fruits, as in cubebs, pepper, juniper berries, &c. Laftly, many vegetables contain this oil in their feeds, as nutmeg, anife, fennel, and mofl umbelliferous plants. Eflential oils differ from ESSENTIAL OILS. 59 from each other, i. In the quantity, which greatly varies according to the ftate or age of the plant, 2. In confidence : fome are very fluid, fuch as thole of lavender, blue, &c. ; others congeal by cold, as the oils of anifeed, or fennel; others again are always concrete, as thofe of rofes, parfley, kidney- wort, and ftarwort. 3. With refpedt to co- lour : fome are colourlefs, others yellow, as that of lavender; others deep yellow, as that of cinnamon; others blue, as that of camomile ; others fea-green, as that of St. John's-wort; or green, as that of parfley. 4. By their weight : fome float on water, as mod of the oils extracted from plants growing in temperate countries ; others, as thole of faflafras and carraway feeds, and moft oils from hot countries, link to the bottom. This property is not, however, conftant with refpeft to climates, the eflen- tial oils of nutmeg, pepper, and mace, be- ing lighter than water. 5. With refpeci to fmell and tafle : this laft property is often very different in the eflential oil from that of the plant. . For example, pepper affords a mild oil, and the oil of wormwood is not bitter. Eflential oils are obtained, 1. By pref- fure, from the cedra, from bergamot, from lemons, oranges, &c. 2. By diftillation. For this purpofe, the plant is put into a copper alembic, together with water ; the water 60 ESSENTIAL OILS. water being made to boil, comes over toge- ther with the oil into the receiver, and is obtained feparate by decantation. Effential oils are adulterated either by the addition of fat oils, which may be known by the ftain fuch oils make on paper ; or by oil of turpentine, which may be diftinguifh- ed by its ftrong fmell, that remains after the effential oil is evaporated. The addition of fpirit of wine in moft cafes difcovers the adulterating fubftance which remains undif- folved, while the oil unites with the fpirit. Effential oils lofe their fmell by a gentle heat, as they are very volatile ; fire alone does not decompofe them. When heated with contaft of air, they quickly take fire, and emit a very thick fume, which becomes condenfed into a fine and light coaly mat-, ter : they leave very little fixed coal after their inflammation ; becaufe they are fo vo- latile, that the coaly matter is formed in the part which rifes. By eypofure to the air they become thick, and in procefs of time affume the character of refin. Needle-formed cryftals are depo- fited fimilar to thofe afforded by camphire when fublimed. Geoffroy the younger, ob- ferved them in the effential oils of mother- wort, marjoram, and of turpentine. The fame chemift obferves, that their fmell is fimilar to that of camphor.* They unite difficultly with lime and alka- lis5 « See the Memoirs of the Academy for the year 1721. CAMPHOR. 6l lis, and are changed by acids. The con- centrated vitriolic acid concerts them into bitumens ; but if it be weak, it forms a kind of foap. The nitrous acid caufes them to burn: into flame ; the muriatic acid renders them faponaceous ; and the dephlo- gifticated marine acid thickens them. They have no action on neutral falts. They combine very readily with fulphur, and form compounds, called balfams of ful- phur, in which the fulphur is fo far changed, that it cannot be again recovered. Mucilages and fugar render them foluble in water. They are ufed as cordial, ftimulant, anti- fpafmodic, &c. remedies. Externally ap- plied, they are powerfully antifeptic, and ftcp the progrefs of caries in the bones. CHAP. IX. Concerning the Camphorate Principle. /^Amphor is a white concrete cryftalline ^-* matter, of a ftrong fmell and tafte, which refembles effential oils in fome of its properties, and differs from them in others. From a number of obfervations, chemifts confider camphor as an immediate principle of vegetables, exifting in all very odorife- rous 6z CAMPHOR. rous plants, that contain effential oil. It has been obtained from the roots of zedoary, thyme, rofemary, fage, and other labiated plants, either by diftillation or decoction, as Cartheufer and Neumann have obferved; but this camphor is in final 1 quantities, and always has the fmell of the plant from which it is obtained. This lingular fubftance feems to be combined with the effential oils of vegetables, as we may conclude from the obfervation of Geoffroy, mentioned in the foregoing chapter. M. Joffe, apothe- cary at Paris, fhewed me a true camphor obtained from the roots of ftarwort. Lorry confidered camphor as a principle abound- ing in vegetables, and placed its fpiritus rector at the head of a clafs of very power- ful frnells, whofe effects on the animal eco- nomy deferve the attention of chemifts and phyficians. The camphor ufed in medicine, is obtained from a fpecies of laurel which grows in China, Japan, and in the iflands of Borneo, Suma- tra, Ceylon, &c. The tree which produces it, fometimes contains fo large a quantity that it need only be cleft, in order to obtain very pure tears of camphor, of confiderable fize. It is obtained by diftillation. The roots, or other parts of the tree, are put in- to an alembic with water, which is covered with a capital, containing ropes of rice ftraw. On the application of a fufficient heat, the camphor CAMPHOR. 63 camphor is fublimed in fmall greyifh grains, which are afterwards united into larger maf- fes. This crude camphor is impure ; the Dutch purity it by fublimation, after pre- viously adding an ounce of lime to each pound of the camphor. Camphor is much more volatile than ef- fential oils and fubftances : with the moft gentle heat, it crystallizes in hexagonal la- mina?, attached to a middle ftem. By a fudden heat it melts before it rifes. It does not feem decompofable by this means ; yet if it be repeatedly diftilled, it affords a red- diSh and manifestly acid phlegm, which feems to (hew that the whole might be de- compofed by repeating the operation a fuffi- cient number of times. The temperature of the air in fummer volatilizes it, fo that it is intirely diffipated. In a clofe veSTel it fublimes in hexagonal pyramids, or polygo- nal cryftals, which were obferved and de- fcribed in the year 1756, by Romieu. Its fmell is Strong and infupportable to fome perfons ; it takes fire readily, burns rapidly with much fmoke, and leaves no carbona- ceous relidue. It does not diffolve in water, to which, neverthelefs, it communicates its fmell : it burns on the furface of water. Romieu has obferved, that fmall pieces of camphor, of the third or fourth part of a line in diame- ter, on the furface of a glafs of pure water, have 64 CAMPHOR* have a rotatory motion, and are diflblved in the fpace of half an hour. He fufpects that this motion is produced by electricity, and obferves that it ceafes when the water is touched with a body that conducts electri- city, fuch as an iron wire ; and that on the contrary, it continues, though the wa- ter be touched with an infulating fubftance, fuch as glafs, refin, fulphur, &c. Earths, the falino-terreftrial fubftances, and alkalis, have no action on camphor. It muft, however, be obferved, that experi- ments have not yet been made with the cauftic alkalis. Concentrated acids diflblve camphor. Oil of vitriol, affifted by heat, difiblves it, and becomes red. The nitrous acid difiblves it without any inteftine motion, and forms a yellow liquid, which, becaufe it floats on the acid, has been called oil of camphor. Thfe muriatic acid, in the ftate of gas, dif- folves camphor j as do likewife the fulphu- reous and fparry gafes. If water be added to thefe folutions, they become turbid, and the camphor is feparated in flocks, which float on the fur face of the liquid, and does not appear to have fuftained any change in its properties. Alkalis, and alio the falino- terreftrial fubftances, and metallic matters, likewife feparate camphor from acids. Neutral falts have no action on camphor. The action of fulphur and bitumens on this fubftance CAMPHOR. 65 fubftance is not known, though it is pro- bable they would unite with it. Fat oils, and eflential oils, diflblve cam- phor by the affiflance of heat. Thefe fo- lutions, by cooling, gradually depofit cryf- tals in a vegetation fimilar to that which is formed in folutions offal ammoniac; namely, a middle ftem, in which very fine horizon- tal threads are inferted. This kind of feathers, examined by the magnifier, is very beautiful and regular. Romieu was the firfl who obferved this beautiful crys- tallization (Memoirs of the Academy for 1756, page 448}. We fhall hereafter fee that the folution of camphor in fpirit of wine, which is much better known and more ufed than the foregoing, prefent- ed this obferver with a cryftallization fome- what different, which he obtained by a peculiar procefs. Camphor is one of the moft powerful remedies the art of medicine pofiefles. It difiipates inflammatory tu- mours in a fhort time, by external applica- tion. It is ufed as an antifpafmodic, and as an antifeptic remedy in contagious diforders, putrid fevers, and in general, in- all difor- ders which are attended with nervous affec- tions, or putridity. It is not adminif- tered in France in larger dofes than a few grains ; in Germany, and in England, it is given in the quantity of feveral drachms per day. It is of importance to be known, that Vol. IV. E camphor 66 SPIRITUS RECTOR. camphor often mitigates heat and pain in the urinary paflages, as it were by inchant- ment. It is given, triturated with yolk of eggs, fugar, gums, or in the ftate of oil of camphor ; and is fometimes ufed in the compofition of diet drinks. Surgeons ufe camphorated fpirit of wine, whofe com- pofition we {hall hereafter defcribe, in exter- nal gangrenes, and often with good fuccefs. B CHAP. X. Concerning the Spiritus Reclor. Oerhaave gave the name of fpiritus rec- tor to the principle in which the fmell of plants refides. The properties of this fingular fubftance, fo interefting on account of its effects on the animal economy, are yet but little known. The fpiritus rector appears to be exceedingly volatile, fugacious, and attenuating. It is continually difengaged from plants, and forms an odoriferous atmofphere around them, to a greater or lefs diftance. All plants differ from each other in the quantity, efficacy, and nature of this principle. Some contain it in great abundance, and are only in part deprived of it by drying, fo that in thefe it appears to poffefs SPIRITUS RECTOR; 67 poflefs a certain degree of fixity. Such, in general^ are the odoriferous woods, and all the dry and ligneous parts of ftrong- fmell - ing vegetables. In others, this principle is fo volatile and tranfient, that though they have much fmell, the fpiritus redlor carl fcarcely be retained, even with the greateft difficulty. Laftly, there are plants, which have a fmell fcarcely fenfible ; thefe are call- ed inodorous, and their fpiritus redtor has been diftinguifhed by the appellation her^* baceous. The flighteft heat is fufficient to difengage the fpiritus re&or of plants. To obtain this principle, the plant muft be diftilled in a wa- ter-bath, and the vapours received in a head, which being kept cool, may condenfe them, and caufe them to pafs into the receiver in a liquid form. This produft is a limpid wa- ter, charged with the principle of fmell, and is called the effential, or diftilled water of the plant. The odorous principle is more volatile than the fluid which holds it in fo- lution. Heat drives off the fpiritus rector, and the liquid becomes, of courfe, deprived of its peculiar fmell; expofure to air pro- duces the fame effedt, very light mucilaginous flocks being depofited, and the fmell of the fluid being changed to that of mouldinefs. The principle of fmell unites with the oily juices, and even feems to be one of the com- ponent parts of effential oils j for, i . They E 2 always 68 SPIRITUS RECTOR. always abound with it. 2. Plants which have a permanent fmell, conftantly afford more effential oil than thofe whofe principle of fmell is very volatile, and which often afford no effential oil, as is the cafe with liliaceous plants. To retain the fpiritus rector of thefe laft, as the lilly, the jeffa- mine, the tuberofe, it is neceffary to com- bine them with fat oil. Thefe flowers are placed in a cucurbit of tin, together with cotton foaked in the oil of ben : the flowers and the cotton are difpofed flratum fuper ftratum ; and the cucurbit being clofed, a gentle heat is applied. The fpiritus rector is difengaged, and combining with the oil, becomes durably fixed. 3. Plants which have no fmell, do not afford the fmalleft quantity of effential oil. 4. Vegetables, whofe fpiritus rector has been extracted by diftillation in the water-bath, no longer afford effential oil, or at lead they do not, unlefs the diftillation has been fo managed, that they ftill retain part of their fmell ; in this cafe, they may afford a very fmall quantity. 5. An effential oil, which has loft its fmell, refumes it very readily, with all its properties, when re-diftilled from a frefh plant, of the fame kind as that from which it was originally extracted. The action of faline fubftances on the fpiritus rector has not yet been examined. The nature of this principle is not iden- tical, SPIRITUS RECTOR. 69 tical, but it feems to differ, according to the genera of the plants from which it is obtained. Macquer is of the fame opinion with Boer- haave, that it is in general compofed of an inflammable and a faline fubftance ; but he obferves, that it fometimes participates more of the faline nature, and in other plants is more oily. The fpiritus rector of cruci- ferous plants appeared to him to be faline ; and he gives it the character of being pene- trating, without affecting the nerves. That which, on the contrary, is iniipid or ftrong, without a keen and penetrating fmell, and affects the nerves in fuch a manner, as either to produce or mitigate thofe fymptoms which depend on their irritation, as is the cafe with aromatic and narcotic plants, participate more of the nature of oils, according to that celebrated chemift. Several facts may be brought in fupport of this affertion. The fraxinella emits an odour that forms an in- flammable atmofphere around the plant, which immediately takes fire on the approach of an ignited fubftance : the vapour then burns from the bottom to the top of the ftem which fupports the flowers. The fpi- ritus rector of fraxinella appears, there- fore, to be of an oily nature. Venel, a chemift at Montpellier, and difciple of Rou- elle, obtained an acid fpiritus rector from favory (marum) by a gentle heat ; and Roux, profeffor of chemiftry in the fchools E 3 of JO SPIRITUS RECTOR. of medicine, who examined this product, difcovered, that it does not redden blue ve- getable colours, but that it faturates alkalis. Chemifts are not agreed concerning the na- ture of the fpiritus re&or of cruciferous plants. Some think that it is acid, and others imagine it to be alkaline. From the experiments of Meffrs. Deyeux and Baume, it appears, that fulphur is found combined with the odorous principle of antifcorbutic plants \ and that this combuftible fubftance, in the ftate of an elaftic fluid, conftitutes the fpiritus redlor of cruciferous plants. Two important confiderations remain to be offered concerning the fpiritus redlor. The firft is, that this principle, according to the very probable conjecture of Macquer, is probably a gas of a peculiar nature. Its inviiibility and volatility, the manner in which it is expanded and difperfed in the atmofphere, together with certain experi- ments made by Dr. Ingen-houfz on the noxious gas afforded by flowers, render this opinion very probable. It only remains, therefore, to make the proper experimental inquiries on this fubjeft, which it muft be conferled require the greateft care and accu- racy, but at the fame time promife to re- ward the inquirer with difcoveries of the moft important kind. Boyle has already opened an immenfe field, and his labours have been continued with the greateft fuc- cefs SPIRITUS RECTOR. Jl cefs by Lorry. This philofopher has at- tended to the alterations which arife from the mixture of odours, and the changes they undergo by fermentation, by the adlion of fire, of air, or of different menftrua. We cannot, without departing too far from our original plan, enter into any detail of his experiments, and {hall therefore only ex- hibit his primitive divifion of odours. Lorry divides thefe bodies into five claffes, to which all other odours may be referred ; namely, camphorated, etherial, poifonous or nar- cotic, acid, and alkali. This phyfician, ex- plaining the bafis of his divifion, eftablifhed on the effects of odours on the fenfe of fmelling, and the nerves in general, affirms, that he does not propofe to inquire into their chemical nature; but it is moft probable, as he himfelf thinks, that the chemical pro- perties of each clafs refemble each other, as well as thofe properties they exhibit in rela- tion to the animal economy. The fecond confideration, with which we fhall terminate our hiftory of the principle of fmell, is, that though the plants called inodorous are confidered as not poiTeffing it, it is neverthelefs well afcertained, that by the loweft heat of a water-bath, thefe alfo afford a fluid, whofe fmell, though feeble, is fufficient to difcover the plant from which it was diftilled. I can affert, from many experiments, that plants, reckoned moft E 4 inodQrous4 72 SPIRITUS RECTOR. inodorous, afford, by the water-bath, a dif% tilled water, which emits their proper odour, in fuch a manner as to diftinguifti them per- fectly from each other. Thefe waters are quickly decompofed, lofing their faint cha- racterise fmells, and becoming changed by fermentation, which difcovers acid or alka- line characters, according to the nature of the fubftance. The art of the perfumer con lifts in ex- tracting the odorous principles of vegetables, and in preferving or fixing them in different fubftances. Moftof the proceffes of this art are intirely chemical. Diftilled waters are much ufed in the art of medicine; they po fiefs different virtues, according to their refpective nature. Thofe only are ufed which are diftilled by a naked fire, with the addition of water, as is done in the extraction of effential oils. We may obferve, that this manipulation is advifable in making aromatic effential waters, but is defective with refpect to fuch plants as are commonly called inodorous. We are of opinion, that it is indifpenfably neceffary to diftil them with the water-bath ; and as this precaution is not ufually taken, they have commonly an empyreumatic fmell, inftead of that of the plant. If the virtue of thefe waters refide only in their fpiritus rector, feeble as it may be, it is certain, that the ufual method of preparing them deprives them. RESINS. 73 them of all the properties they ought to have. We muft likevvife add, that the diftilled waters of plants, prepared in pharmacy, are not the pure fpiritus rector, in the fenfe Boerhaave ufes the word, but that the fpi- ritus rector is diluted with a large quan- tity of water, which comes over in the dif- tillation. CHAP. XI. Of Inflammable Reiinous Juices in general, and of Natural Balfams in particular. ^T^HE name of refinis given to a dry, in- ■* flammable fubftance, not mifcible with water, foluble in oils and fpirits of wine, and which flows in a liquid ftate from the trees that produce them. Thefe fubftances are oils, become concrete by being dried in the air. The difference between balfams and refins is not well fettled. Some give the name of balfam to fluid inflammable fubftances, though there are likewife dry balfams. Others call the moil odorous inflammable fubftances by this name. Bucquet has thrown con- fiderable light on this fubject, by confining the name of balfams to fuch combuftible matters 74 BALSAMS, matters as communicate a fweet tafte to wa- ter, and more efpecially contain odorant and concrete acids, which may be obtained by fublimation or deco&ion in water. The principal fpecies of balfams may be reduced to the three following : i. Benzoin; this is diftinguifhed into two fpecies, the benzoe amygdaloides, form- ed of white tears, refembling almonds, unit- ed by a brown matter : common benzoin is brown, and without tears -> it emits a very agreeable fmell, when fufed or touched with a hot needle. The tree which affords it is not known ; but we receive this halfam from the kingdom of Siam, and the ifland of Su- matra. It affords very little effential oil, or* account of its folidity. Boiling water ex- tracts an acid fait, in the form of needles, of a ftrong fmell, which cryftallizes by cool- ing. It is likewife obtained by fublimation, and is then called flowers of benzoin. This operation is made in two glazed earthen pots, placed one above the other, and clofed at the place of junction with paper. The fublimation muft be performed with a gentle heat, otherwife the fait will be brown. The paper cone, formerly ufed as a fublim- ing chimney, inftead of the upper pot, caufes the lofs of a great part of the flowers. The fmell of this fait is ftrong, and it produces a cough when inhaled. Its tafte is acid; it reddens fyrup of violets, and effervefces with the BALSAMS. 7| the cretaceous alkalis. Benzoin, diftilled in a retort, affords a very acid phlegm, a con- crete and brown fait of the fame nature, with a brown and thick oil. The refidual coal contains fixed alkali. Bergman and Scheele began the examina- tion of the properties and elective attractions of the acid of benzoin ; but their experi- ments are not fufficiently numerous to afford any very extended knowledge of this acid and its properties. Benzoin diflblves in fpirit of wine; and its tincture, precipitated by water, affords the lac virginale. The fait of Benjamin is ufed as a good incifive remedy in pituitous diforders of the lungs and veins. Its oil is difcuflive, and is externally applied in para- lytic diforders, tec. 2. Balfam of Tolu, Peru, or Carthagena. It is imported either in cocoa nut fhells, or in yellowifh tears, or in a fluid ftate. It flows from the Toluifera, placed by Linnaeus in the decandria monogynia. It may be extracted from the fhells, by fleeping them in boiling water, which renders it fluid. It comes from South America, in the tract between Carthagena and Honduras. It af- fords the fame products as benzoin, and more particularly the concrete acid. It is made into a fyrup, and is ufed in diforders of the lungs. The acid of balfam of Tolu has not been fuffi- j6 RESINS. fufficiently examined to determine whether it effentially differs from that of benzoin. 3. Storax calamita is in tears, either red and clean, or brown and unctuous. Its fmell is very ftrong. It flows from the oriental liquid amber, a plant very little known. Newman analyzed the ftorax calamita, and obtained a very fmall quantity of effential oil, a concrete acid fait, and a thick oil. This balfam is applied to the fame ufes as benzoin, and is more particularly confumed by perfumers. It was formerly imported inclofed in reeds, or canes ; we now receive it in the form of loaves, or irregular maffes, of a reddifh brown colour, mixed with fome tears of a lighter colour, and of a very agree- able fmell. CHAP. XII. Concerning Refins. RESINS differ from balfams in their fmell, which is lefs agreeable, and efpe- cially in their containing no concrete acid fait ; the principal fpecies are the follow- ing : 1. Balfam RESINS. 77 i. Balfam of Mecca, of Judea, of Egypt, of Grand Cairo. It is liquid, white, bitter, and of a very ftrong fmell, refembling that of lemons. It flows from a tree called amyris opobalfamum, placed by Linnaeus in the oclandria monogynia, and difcovered in Arabia Felix by Mr. Forfkahl, This liquid refin affords much effential oil, by diflillation ; it is incorporated with fugar, yolk of eggs, &c. and ufed as a vulnerary. 2. The balfam of copaiba, of a brown or yellow colour, which flows from the tree called copaiba, or copaifera, of Linnaeus, and placed by that botanift in the decandria monogynia. The common fort, as well as that of the balfam of Tolu, is a mixture of the true balfam of ^copaiba and turpentine, according to Cartheufer. It is ufed in ulcers of the lungs and bladder, like the foregoing. 3. Chio turpentine is afforded by the tur- pentine tree, which bears piftachio nuts. It is of a white, or blueifh yellow colour. By the water-bath, it affords a very fluid ef- fential oil ; but the oil obtained by a naked fire is lefs fluid. The turpentine, after this procefs, is yellower ; if the diflillation be made with water, it is white and fllky, and is called boiled turpentine. This is rarely met with, and is now no longer ufed. 4. Venice turpentine is commonly ufed in medicine, either in its natural ftate, or combined with fixed alkali. This combi- nation 78 RESINS. nation is called Starkey's foap. The difpen- fatory of Paris direcfts four ounces of effen- tial oil of turpentine to be poured on half a pound of nitre, fixed by tartar, before it is become cold. The mixture is to be agitated with a fpatula of ivory, and the veflel kept covered with a paper, more oil being from time to time added, till the whole forms a white mafs. As this procefs requires feve- ral months time to complete it, chemifts have endeavoured to difcover more expedi- tious methods of performing it. Rouelle, by triturating the alkali, drop by drop with the foap, and adding a fmall quantity of water towards the end, prepared a conside- rable mafs of this foap in the fpace of three hours. M. Baume diredts one part of al- kali of tartar, heated till it fufes, to be ground on a levigating ftone, three or four times its weight of effential oil of turpentine being gradually added. When the mixture has acquired the confiftence of a foft opiate, he expofes it in a moift place, in a glafs veflel covered with paper. In fifteen days, the deliquefcent alkali forms a ftratum of liquor at the bottom of a vefTel, the foap is in the middle, and a portion of the oil, of a red colour, floats above. M. Baume thinks, that the alkali unites only with that portion of the oil which is in the refinous ftate. M. Le Gendre carries this notion farther, and propofes to faturate a cold folution of fixed alkali RESINS. 79 alkali with oil of turpentine become thick, or turpentine itfelf. This foap has a certain degree of folidity, which gradually becomes more confiderable j it affords cryftals, which have been confidered as a combination of the acid of the oil with the vegetable fixed al- kali; but which, according to the acade- micians of Dijon, confift of the vegetable alkali, faturated with the cretaceous acid. As this foap is very difficult to make, and fubject to change, Macquer thinks, that when an union of the properties of effential oils with thofe of foap, is defired, it is more advifable to incorporate with the white me- dicinal foap, a few drops of that effential oil, whofe qualities may anfwer the intended pur- pofe. Pure volatile alkali, triturated with turpentine, forms a faponaceous folid com- pound, foluble in water, to which it gives a milky appearance. 5. The refin of fir is called Strafburg tur- pentine ; it is collected by piercing the ve- ficules of the bark of fir trees, which grow plentifully in the mountains of Switzerland. 6. Pitch is the juice of a kind of fir, called abies picea ; it is extracted by inci- fions made in the bark of the tree. It is melted by a gentle fire, and ftrained through facks j after which it is received in barrels. Burgundy pitch is white, but the mixture of coaly matter gives the black colour. When pitch is long kept in fufion with vi- negar, 8o RESINS. negar, it dries, becomes brown, and forms colophony. The dregs of pitch are burned in a fire-place, whofe chimney leads into a fmall chamber, terminated by a cone made of cloth : in this lafl, the fmoke condenfes, and forms the fine foot, called lamp-black. 7. Galipot, or refin of the pine. Holes are bored in the lower part of this tree, through which the refin flows into troughs. Other incifions are made higher up, when the former afford no more. When emitted in the fluid ftate, it is called galipot ; the portion which dries on the tree, in yellowiiTi mafles, is called barras. Thefe juices are melted, and when thickened by heat, are filtered through draw mats, and poured into moulds in fand. They then form maffes, call- ed arcancon, orbray-fec. If water be added, the matter becomes white, and forms refin, or pitch refin. Galipot is diftilled in the large way in the provinces of France, and affords an oil, called huile-de-raze, or caulking pitch. The tar, which is the empyreumatic oil of this fubftance, is prepared with the branches and roots of the pine. The wood of this tree is laid in heaps, covered with turf, and fet on fire. The oil, difengaged by heat., not being capable of efcaping through the turf, is precipitated into a fhallow tub, by means of a channel, and is collected for fale by the name of tar. 8. Tacamahaca, gum elemi, gum anima?, arc RESINSi 8l aire very little ufed : the tree that affords the fruit is not known. The gum elemi is ob- tained from a fpecies of amiris ; the oriental gum anime, or copal, whofe origin is un- known, and the oxidental gum anime, or courbaril, which flows from the hymenea, a tree growing in South America, are ufed to make varnifhes. 9. Maftic is in white farinaceous tears, of a weak fmell ; it flows from the turpentine tree, and the maflic tree. It is ufed as an aftringent and aromatic, and enters into the compofition of drying varnifhes, 10. Gum fandarac is in white tears, more tranfparent than maflic. It is obtained from the juniper, between the bark and the wood. It is ufed to prevent the finking of ink into paper, whofe external coating of fize has been fcraped off in making erafures. 1 1 . The refin of guaicum, which is green- ifh, is ufed as a remedy for the gout. It is obtained from the guaicum tree, by inci- fion. 12. The labdanum, or refin of a fpecies of ciftus in Candia, is blackifh. The coun- try people collect it by means of a ftarT, at the end of which are fattened many leather thongs, which they gently ftrike on the trees. They form it into cylindrical pieces, which are called labdanum in tortis. It is greatly adulterated by the addition of black fand, and is ufed as an aftringent. Vol. IV. F 13. Dragons 82 GUM RESINS 13. Dragons blood is a red juice, ob- tained from the draca?na draco, and feveral other trees of the fame kind. It comes to us in flat or round pieces, or in fmall balls, wrapped up in leaves. It is ufed in medi- cine as an aftringent. CHAP XIII, Gum Reims. /^UM refins are juices mixed with refin, ^* and an extractive matter, which has been taken for a gummy fubfcance. They never flow naturally from plants, but are extracted by incifion, in the form of emulfive white, yellow, or red fluids, which dry more or lefs quickly. Water, fpirit of wine, wine, or vinegar, diffolve them only in part. They differ in the proportion of reiin and extract, and their analyfis affords various refults : the fpecies moft neceffary to be known are the following. 1. Olibanum confifts of yellow tranfpa- rent tears, of a very difagreeable fmell. The tree which affords it is not known. By dif- tillation, a fmall quantity of effential oil, together with an acid fpirit, are obtained, and the coaly refidue, ariiing from the ex- tractive GUM RESINS; 83 tractive part, is very considerable. It is ufed in medicine for fumigations. 2. Galbanum is a fat juice, of a brown yellow colour, and naufeous fmell. In Sy- ria, Arabia, and at the Cape of Good Hope, it flows from incifions made in a ferulaceous plant, named bubon galbanum by Linnasus. Diftilled with a naked fire, it affords a blue effential oil, which afterwards becomes red; and alfo an acid fpirit, with a ponderous em- pyreumatic oil. It is a very good difcuffive remedy, and is powerfully antifpafmodic. 3. Scammony is of a blackifri grey colour, a ftrong and difagreeable fmell, a bitter and very acrid tafte. The Aleppo fcammony is diftinguifhed by its greater purity from that of Smyrna, which is ponderous, black, and mixed with foreign fub fiances. It is ex- tracted from the convolvulus fcammonia of Linnaeus. The root of this plant, cut in pieces and preffed, affords a white juice, which is black when dried. The different fpecimens of fcammony contain various pro- portions of extract and reiin, and its medical effects differ accordingly. It is prefcribed as a purge, in the dole of from 4 to 1 2 grains. Mixed with a fweet extract, fuch as that of liquorice, it forms the common diagredium; the juice of quinces is- likewife ufed for this purpofe. The common mode of admini- ftering it, is after previous trituration with fugar and fweet almonds. F 2 4. Gum 84 GUM RESINS. 4. Gum^guttae is yellow, reddifh, with- out fmell, and of a very acrid and corrofive tafte. It comes from Siam, China, and the ifland of Ceylon. It is extracted from a large tree, not much known, called by the natives, coddam pulli. It contains much refin, which renders it ftrongly purgative, in a dofe of from 4 to 6 grains. It ought not to be internally ufed, but with the great- eft caution. 5. Euphorbium is in yellow tears, which have the appearance of being worm-eaten ; it has no fmell. It flows from incilions made in the euphorbium, which grows in . Ethiopia, Lybia, and Mauritania. It contains a very acrid refin, and is fo ftrongly purga- tive, that it is reckoned among poifons. It is not ufed, unlefs externally, in caries. 6. AfTafcetida is fometimes in yellowifh tears, but moft commonly in loaves, formed of a number of pieces, agglutinated together. It has a very fetid fmell of garlic, with a bitter and naufeous tafte. It is extracted from the root of a fpecies of ferula, which grows in the province of Chorafan, and is called affafcetida by Linnaeus. The root of this plant is flefliy and fucculent. By expreffion, it affords a white juice, of an abominable fmell, which the Indians ufe as feafoning for food, under the name of food of the gods. It is internally ufed as a power- ful GUM RESINS. 85 ful antifpafmodic, and is applied externally as a difcutient remedy. 7. Aloes is a juice of a deep red, or brown, and very bitter. It is diitinguifhed into three fpecks ; fuccotrine aloes, hepatic aloes, and cabaline aloes : thefe differ only in their refpe&ive degrees of purity, the firit being the beft. A. De JurTieu faw the preparation of the different kinds of aloes, from the leaf of the common aloe plant. Deep incifions are made, from which the juice flows -, this is decanted from its fecula, and thickened by the fun's heat, in which ftate it is packed in leather bags, under the denomination of fuc- cotrine aloes. The juice obtained, by pref- fure, from the leaves, after it is purified by repofe, and dried, is the hepatic aloes. The fame leaves, by ftronger preffure, afford a portion of juice, which, mixed with the dregs of the two foregoing, constitutes the hepatic aloes. The firit fort contains a much lefs quantity of refin than the two laft, which are more ftrongly purgative. It is ufed in medicine as a draftic purge, and is acknow- ledged to poffefs the property of exciting the menftrual flux in women, or the hemorrhoids in men. It is much efteemed as a good hydragogue. 8. Myrrh is brought to us in the form of reddifh brilliant tears, of a Strong and rather agreeable fmeil, bitter tafte, and exhibiting white lines, of the form of a nail, in their F 3 fracture. 86 GUM RESINS, fracture. Some of thefe tears are intirely gummy, and infipid. Myrrh comes from Egypt, and efpecially from Arabia, in the country of the Troglodites. The plant from which it is extracted is not known. It con- tains much more extract than refin. It is ufed as an excellent ftomachic, antifpafmodic, and cordial remedy. Cartheufer advifes lite- rary men, whofe ftomachs are delicate, to chew this, and fwallovv it with the faliva. It is ufed in furgery, either in powder, or diffolved in fpirit of wine, to cleanfe foul ulcers, and to ftop the progrefs of caries. 9. Gum ammoniac fometimes has the form of tears, white within, and yellow without, and is fometimes in mafles refembling ben- zoin. They are eaiily diftinguifhed by their white colour and fetid fmell. It is fufpect- ed, from the admixture of feeds it contains, that this gum refin, which comes from Africa, is extracted from an umbelliferous plant. The folubility of this fubftance in water, and in fpirit of wine, and more par- ticularly its inflammability, are properties in which it refembles the refinous extractive matters of Rouelle. Gum ammoniac is medicinally ufed as a difcuffive remedy in obftinate obstructions ; it is given in dofes of a few grains, in pills or emulfions, and likewife enters into, the compofition of many difcuffive and refolvent platters. 10. The GUM RESINS. 87 10. The elaftic gum, or caout-chouc, is a vegetable fubftance, whofe nature cannot eafily be determined; for though, in its com- buftible property, which is applied to the pur- pofe of illumination in America, it feems to refemble refins, yet its elafticity, foftnefs, and infolubility in the menftrua which diffolve thefe laft, are characters which mew that it greatly differs from them. The tree which affords this fubftance grows in feveral parts of America. Hori- zontal inciiions are made quite through the bark; a white and fluid juice iffues forth, which is applied, in fucceffive coats, on clay moulds, and dried by the fan's heat. Various fketches of defigns are made on the furface with an iron tool. It is then ex- pofed to the fmoke ; and when perfectly dried, the clay is crufhed and taken out. The bottles, and various utenfils of elaftic gum, which are imported into Europe, are made in this manner. Veffels of elaftic gum may be ufed to con- tain water, and various fluids which do not corrode its fubftance. If it be cut into pieces, and the newly-cut edges applied to each other, they adhere together with con- fiderable force. Elaftic gum, fet on fire, foftens, fwells up, emits a fetid fmell, and fhrinks as it burns. It is not foluble in water;, and the action F 4 of 88 GUM RESIN*. of falinc matters on this fubftance is not known. Macquer, who attempted to dif- folve it in different menftrua, clearly afcer- tained, that it was not at all acted on by fpirit of wine, as Mefirs. De la Condaminc and Frefneau had before aflerted, in the Memoirs of the Academy for 1751, but that oils diflblve it, by the affiftance of heat. Neverthelefs, as his intention was to liquefy, or diflblve it in fuch a manner, as that it might be ufed, and refume all its properties, by the evaporation of the folvent, it became neceflary for him to ufe a more volatile menftruum than oils, which remain combined with the gum, and deprive it of its elafticity. Highly rectified ether, which readily diflblves this fubftance, and may be quickly evaporated, anfwers the purpofe per- fectly well. (See the Memoirs of the Aca- demy for the year 1768.) And though this fluid is very expenfive, he thinks it may be advantageoufly ufed in making certain uten- fils, fuch as catheters, by fucceflively ap- plying this folution on a mould of wax, till it is of the required thicknefs. When it is dry, the wax may be eafily feparated, by immerfion in boiling water. The foftnefs and elafticity of this inftrument, renders it extremely ufcful for fuch as are under the neceftity of continually ufing it. Such was the ftate of our knowledge, re- fpecting the elaftic gum, when, in the month of GUM RESINS, 89 of April, 178 1, Mr. Berniard, well known by the accuracy of his experiments, inferted, in the Journal de Phyfique, an excellent memoir concerning this Angular fubftance. This chemift concluded, from his experiments, that the elaflic gum is a peculiar kind of fat oil, coloured by matter which is foluble in fpirit of wine, and blackened by the fmoke, to which each coating is expofed to dry. Water does not at all change it; fpirit of wine deprives it of its colour, by boil- ing. The cauftic fixed alkali does not act upon it. Oil of vitriol reduces it to the ftate of coal, itfelf becoming black, and af- fuming the fmell and volatility of the ful- phureous acid. The common nitrous acid 2cts in the fame manner on this fubftance as on cork, changing its colour to a yellow* Spirit of nitre very quickly deftroys it, but the muriatic acid does not affect it in the leaf!:. Rectified vitriolic ether did not dif- folve it. This fact, as the author obferves, muft appear lingular, to all who are ac- quainted with the exact nefs and the veracity of Macquer. Nitrous ether diffolves it, and becomes yellow, affording, by evaporation, a tranfparent friable fubftance, which is fo- luble in fpirit of wine, and is in fact a true refin, formed, according to the author, by the action of the nitrous acid on the elaftic gum. The effential oil of lavender, and likewife thofe of afpic and of turnfole, dif- folved go GUM RESINS. folved it by the help of a flight heat ; but they formed gluey fluids, which daubed the hands, and confequently were not applicable to any ufe. Afolution of elaftic gum, mix- ed with fpirit of wine, depofited white flocks, infoluble in hot water, at the top of which they floated, and became white and folid, like wax, by cooling : it appeared to be a true concrefcibie fit oil. Oil of cam- phor diflblved elafiic gum, by Ample mace- ration. By evaporating this foiution, the camphor was driven oft, and an amber- coloured matter, of a firm confidence, fcarce- ly adheiive, remained in the capfule, and was found to be eafily foluble in fpirit of wine. Fat oils, bo i led on elaftic gum, dif- folve it, as does like wife wax. This Jub- ilance does not melt by the heat of boiling water; but when expofed to a greater heat, in a filver fpoon, it is converted into a black thick oil, emits white vapours, and remains fat and adheiive, though expofed to the air for feveral months, and does not recover the drynefs and elasticity in which its chief uti- lity confifts. Laftly, Mr. Berniard con- cluded his inquiries, by analyfing elaftic gum with a naked fire. One ounce afforded a very fmall quantity of phlegm ; an oil, at firft light and clear, but afterwards thick ; and coloured and volatile alkali, in a quan- tity which he has not afcertained. The coaly refidue was fimilar to that of refins* and GUM RESINS. 91 and weighed 12 grains. This chemift attri- butes the volatile alkali to the foot with which the elaftic gum is coloured. We muft obferve, that this analyfis does not accurately afcertain the nature of elaftic gum, becaufe the action of acids on this fubflance does not refemble that which they exhibit with fat oils, and which is much more rapid ; becaufe cauftic alkalis do not convert it into foap ; becaufe it does not melt, but by a degree of heat much greater than is neceffary to melt the moft folid fat oils ; becaufe no fat oil becomes dry and elaftic, &c. &c. The author, befides, in his fifteenth experiment, affirms, that this gum is compofed of two diftinct fubftances, which he does not exhibit; and he con- cludes, by confid;ring it as the product of art. From all thefe reflections, and many others which may be added, concerning the experiments of Mr. Berniard, valuable as they are, we think, with him, that much remains to be done, to afcertain the proper- ties of this fubftance, and to enable us to decide refpedting its nature. CHAP. gZ FECULA CHAP. XIV. Of the Pure Fecula of Vegetables. /HpHE juices of vegetables, elaborated iu ■* their veffels, become thick, and are gradually depoiited on the furface of the fibres, which are by that means fupported and augmented, or become accumulated, in a more or lefs folid form, in the organs of the plant. After having treated of the fluid parts of thefe organized fubftances, it is ne- ceflary to examine the fubftance of which their folids are compofed. We are far from pofTeffing an accurate knowledge of all the folid fubftances contained in vegetables; but it appears, that when treated by the pro- ceffes we are about to defcribe, they are re- ducible into a dry, pulverulent, inlipid, white, grey, or varioufly coloured fubftance, infoluble in cold water, and of an earthy appearance, called fecula. To obtain this fubftance, a root, item, leaf, or feed, is reduced to a pulp, by pound- ing. Succulent vegetables may be treated in this manner, without the addition of wa- ter ; but in general water is added, to faci- litate the feparation of the fibres, and to carry FECULA. 9J carry off the divided and pulverized parts. The pulpy matter, by ftrong preflure, af- fords a turbid, white, or coloured fluid, which after fome time depofits, by flanding, a fubilance partly fibrous, and fometimes pulverulent, which is the true fecula of ve- getables. Some parts of vegetables appear to be intirely compofed of this matter ; fuch as the feeds of gramineous and leguminous vegetables, tuberous roots, &c. Thefe parts in general afford the fineft and mofl abun- dant fecula. As to the tender items and leaves of vegetables, their more fibrous tex- ture affords only a coarfe-coloured filament- ous depofition, diftinguifhed by the name of coarfe fecula. If thefe be well dried, pul- verized and warned, the w7ater carries off a much finer fecula, perfectly fimilar to that of the tuberous roots and gramineous feeds. The chemift, therefore, makes no other dif- tinclion between thefe two kinds of fecula, than that the firft is obtained from a lefs fibrous part, confifting, as it were, of cells, in which nature has depofited dry or fari- naceous mucilage; while the fecond, being of a more fibrous texture, requires its or- ganization to be deftroyed by a more arti- ficial procefs. All the vegetable parts of folids, ftricUy fpeaking, afford a kind of fecula; but we fliall here more particularly fpeak of fuch as are prepared by art for food or medicine. The 94 FECULA. The fecula of bryony, potatoe, caflava, fagoj falop, and ftarch, are thofe we (hall par- ticularly attend to. i . To prepare the fecula of bryony, the firft roots are deprived of their bark, rafped in pieces, and fubmitted to the prefs. The juice is white, and depcfits a very fine fe- cula, from which, at the end of twenty- four hours, the liquid is decanted, and it is dried. As this fecula contains a certain quantity of extract, left by the juice, it is very acrid, and purges violently : by waffl- ing, it becomes finer, and whiter, but at the fame time lofes its purgative virtue. This method of preparing the fecula of bryony affords but a very fmail quantity, but a much greater may be obtained, by moiften- ing, with water, the mafs remaining in the prefs, (training this water through a hair lieve, to feparate the groffer fibres, and leaving it at reft, and to depoiit its fecula, at which time the water is to be decanted off, and the powder dried. This laft fecula is not pur- gative, like the former, becaufe it has been deprived of its extractive matter by the wa- ter. Mr. Baume has obferved, that the fe- cula of bryony is abiolutely the fame as ftarch, and may be made into hair powder, to the great faving of corn. The fecula of the roots of arum, and cornflag, are pre- pared in the fame way for medical ufes. 2. Potatoes are among the moil: ufeful alimentary FECULA. 95 alimentary fubftances, with refpect to their abundance and fertility. They afford a large quantity of very fine white fecula, which, when boiled, is an excellent food. It is ob- tained by fcraping the potatoes into a iieve, and pouring thereon a large quantity of wa- ter. The fluid carries off the fined: and mofl divided part of the fecula, which fubiides by Handing. The water is decanted off, and the fecula, dried by a gentle heat, has the form of a very fine white powder. Mill", confifting of a kind of rafps, turning on cy- linders, have besn contrived, and are ufed to great advantage in preparing this fecula. 3, The Americans extract, from the root of a very acrid plant, called manioc, a mild nou- rifhing fecula, which they call caffava. They ftrip the root, rafp it, and put it into a fack of rufhes, made in the form of a cone, and of a very open texture, which they fufpend to a ftaff, placed acrofs two upright pofts. At the lower extremity of this fack, they hang a heavy veffel, which by its weight preffes the root, and receives the juice which flows out, and is a moft acrid and dangerous poifon. When the fecula is well preffed, and deprived of all its juice, it is dried in the fmoke, fifted, and then forms caffava. This farina is fpread on a hot plate of iron, and turned till both its furfaces acquire a reddifh yellow colour, which denotes that it is fufficiently baked. In this ftate it is called 96 FECULA. called caflava bread. When the farina is heated in a veffel, and agitated from time to time, it takes the form of grains, called couac. A very fine and mild fecula, called mouffache, falls to the bottom of the ex- prefled juice, and is ufed for paftry. 4. Sago is a dry fecula, reduced into grains by the a&ion of fire, and comes to us from the iflands of Molucca, Java, and the Phillipines. It is obtained from a kind of palm, called landan, in the Moluccas. The trunk of this tree contains a fweetpith, which the inhabitants take out after having fplit the wood ; they then bruife it, and put it into a kind of cone, or funnel, made of bark, and pour on a large quantity of water. This fluid carries with it, through the fieve, the fineft and whiteft part of the pith, the fibrous part remaining behind. The water is received into pots, and gradually depofits the fecula. The clear water is then decant- ed, and the depofited matter is paffed through perforated plates, which give it the form of fmall grains. The red colour on their fur- face rifes from the action of fire, ufed in the drying. Thefe grains, or fago, become foft and tranfparent in boiling water, and form, with milk or foup, a light and agreeable li- quid, which is ftrongly recommended in phtjiifical diforders. 5. Salep, falop, falab, &c. is the root of a fpecies of orchis, prepared by the orien- tals. FARINA. 97 tats. They felecT: the fineft bulbs of this plant, which they peel, and boil, after pre- vioufly foaking them in cold water. They are then ftrung, and dried in the air. M. Jean Moult defcribes another procefs for prepar- ing falop, which may be ufed with every kind of orchis. The roots, either dry or under water, are rubbed with a brum, to take off the external pellicle; after which, by drying in an oven, they become very hard and tranfparent. Thefe are very eafily re- duced into powder, which, with hot water, forms a nourifhing jelly, much praifed by Geoffroy, in all diforders arifing from an ' acrid ftate of the lymph, and efpecially in. confumptions, and the bilious dyfentery. CHAP. XV. Concerning the Farina, and Starch of Corn. GTARCH, properly fpeaking, is a fecula ^ abfolutely fimilar to the foregoing ; but as the farina of corn, of which it is a con- ftituent part, is one of the mofl important fubltances that come under the examination of the chemift, we fhall treat more fully on this than on the other fecula. The fubftance called flour, is in general Vol, IV. G dry, 98 FARINA. dry, friable, infipid, capable of acquiring tafte and digeftibility, by the action of fire, and compofed of feveral fubftances eafily fe- parable from each other. It exifts in the feeds of gramineous plants, more efpecially wheat, rye, barley, oats, rice, buckwheat, &c. Leguminous plants likewife appear to contain a compound analogous to flour; but the flour of wheat only can be faid truly to poflefs the requilite properties, becaufe it is the only farina in which the different fub- ftances are duly proportioned to each other. Though the economical ufe of the flour of wheat, as the principal article of nourifhment, has been eitablimed from time immemorial, it is but lately that chemifts have began to ex- amine it. Meffrs. Beccarri, an Italian phy- lician, and Keffel Meyer, in Germany, are the firft chemifts who endeavoured to fepa- rate the different fubftances contained in flour, Meffrs. Rouelle, Spielman, Malouin, Parmentier, Poulletier de la Salle, and Mac- quer, continued and carried the experiments of thefe philofophers much farther. Mr. Parmentier, efpecially, has profecuted this inquiry with uncommon zeal and activity. His refearches into the nature of alimentary fubftances, the component parts of flour, the different fpecies of fecula, and on all nutrative vegetables in general, are, without doubt, the moft complete and exact of any that have been made in this way. Water VEGETABLE GLUTEN. 99 Water is an agent of the greateft utility, and leaft capable of altering the feveral mat- ters it takes up, or feparates, in the order of their folubility. This fluid is ufed, with the greateft fuccefs, to obtain the different fubftances of which wheat flour is compofed. To perform this true analyfis, a pafte is made with flour and water, and kneaded in a veflel of water, underneath a ftream from a cock ; the water carries off a very fine white pow- der, and the kneading muft be continued till this fluid paffes oft clear. The flour is then found to be feparated into three fubftances; a greyifh and elaftic matter remaining in the hand, which has been called the gluti- nous, or vegeto-animal part, on account of its properties ; a white powder, depofited by the water, which is the fecula, or ftarch ; and a fubftance, held in folution by the wa- ter, which appears to be a kind of mucila- ginous extract. We (hall examine the pro- perties of each of thefe three fubftances in order. § I. Concerning the Glutinous Part of Wheat. The glutinous part, is a tenacious, ductile, elaftic matter, of a whitifh grey colour. When drawn out, it extends about twenty times its length before it breaks, and appears as if compofed of fibres, or filaments, placed G 2 befide 813 IOO>-*^VEGETABLE GLUTEN. according to the direction 1 wmcn it has been drawn. If the force ceafes, it refumes its original form by its elafticity. By drawing it out, in different directions, it may be made fo thin, that its po- lifhed furface refembles the texture of animal membranes. In this ftate it adheres ftrongly to dry bodies, and forms a very tenacious glue, which was ufed by fome perfons to join broken china, long before chemifts found the means of obtaining it in large quantities. Mr.Beccari has obferved, that the proportion of glutinous matter is from a fifth, to a third, and more, in flour of the beft quality -y he has likewife. obferved, that this quantity va- ries in different feafons, and according to the nature of the corn. The fmell of the glutinous matter is faint, and refembles that of mucilage ; expofed to a fire capable of fuddenly drying it, it fwells up prodigioufly. In a dry air, or mild heat, it dries very well. It is then femi-tranfpa- rent, and hard, like glue, and fnaps fhort like that fubftance. If in this ftate it be placed on burning coals, or applied to the flame of a candle, it exhibits all the characters of an animal fub- ftance; it decrepitates, fwells, liquifies, curls up, and burns like a feather, or a piece of horn, emitting, at the fame time, a ftrong and fetid fmell. By diftillation, it affords, like animal fubftances, alkaline fpirit, con- crete VEGETABLE GLUTEN. 101 crete volatile alkali, or ammoniacal chalk, and an empyreumatic oil. Its coal is very difficultly incinerated, and does not contain fixed alkali. Frefh gluten, expofed to a hot and dry air, becomes changed, and putrifies abfo- lutely in the fame manner as animal fub- ftances. When it retains a fmall quantity of ftarch, this laft pairing to the acid fer- mentation retards and modifies the putrid fermentation, and converts the fubftance in- to a ftate nearly flmilar to that of cheefe. Rouelle the younger prepared a cheefe with the gluten, which Angularly refembled in its fmell and tafte, that of Gruyeres, or of Holland. Water does not at all diflblve this glutinous matter. By boiling in this fluid it becomes folid, lofes its extensibility and adhefive quali- ty, but does not acquire either tafte or folubi- lity in thefaliva. Neverthelefs, we rauft ob- ferve, that the gluten owes its elasticity and folidity to the water which formed the pafte. In fad:, this vegeto-animal portion, though capable of becoming folid and elaftic, is pulverulent, and without cohefion in the flour ; but as foon as water is added, its particles abforb the fluid, and adhere toge- ther, forming the elaftic fubftance called gluten. Water, therefore, contributes greatly to the formation of this fubftance, and it G 3 may 102 VEGETABLE GLUTEN. may perhaps be confidered as a compound, faturated with, and incapable of absorbing a larger quantity of water. This is fo true, that it abfolutely lofes its adhefion and elas- tic properties by drying. Moft faline fubftances act more or lefs efficacioufly on the gluten. The cauftic fixed alkalis in the fluid ftate diiTolve it by boiling. This folution is turbid, and de- pofits, by the addition of acids, a gluten which is not elaftic. The mineral acids diflblve the gluten. The nitrous acid diffolves it with great ac- tivity, and Mr. Berthollet has obferved, that this acid difengages mephitis, as it does from animal fubftances. When this elaftic fluid has been emitted, the folution affords a large quantity of nitrous gas, and becomes of a yellow colour. By evaporation it af- fords cryftals of the acid of fugar. The vi- triolic and marine acids form brown or vio- let folutions of this fubftance, from which a kind of oily matter feparates ; the gluten being truly decompofed. Mr. Poulletier, who has made many experiments on this fubftance, has difcovered, that ammoniacal falts may be obtained from thefe combina- tions, diftblved in water, or fpirit of wine, and evaporated in the open air. From thefe fadts, it follows, that this fubftance is totally different from all thofe hitherto known in vegetables, and that in many STARCH. °3 many of its characters it refembles the fi- brous part of the blood. It is to this gluten that wheat flour owes its property of form- ing a very adhefive parte with water, and the facility with which it rifes in leaven. The gluten does not appear to exift, at lead in any confiderable quantity, in other farina, fuch as that of rye, barley, buckwheat, rice, Sec. ; all which form folid, opake partes, fcarcely ductile, eafily broken, and which do not ferment when expofed to the temperature by which that procefs is ef- fected in wheat parte. The prefence of the gluten appears therefore to be neceflary for the produdion of good bread. Mr. Berthollet thinks that this glutinous fubftance contains phofphoric fait, like ani- mal matters, and that this is the caufe of the difficulty with which its charcoal is incinerated. Rouelle the younger found a glutinous fubftance analogous to that of wheat in the green fecula of plants, which afford volatile alkalis and empyreumatic oil, as does the vegeto-animal fubftance here treated of. § II, Concerning the Starch of Wheat. Starch, or the amylaceous fecula, com- pofes the greater part of flour ; it is the white fubftance which fubiides from the water ufed in obtaining the pure gluten. G 4 This 104 STARCH, This fubftance is very fine, and foft to the touch ; its tafte is fcarcely fenfible. Its colour is of a grey and dirty white, when extracted by the procefs we have defcribed; but the ftarch-makers render it extremely white by fuffering it to remain in the water for a time, after it has become acid. It appears from the experiment of Mr. Poulle- tier, that the fermentation which takes place in this fluid, whitens and purifies the ftarch by attenuating, and even deftroying the ex- tractive mucilaginous fubftance with which it is vitiated at firft. Starch, chemically confidered, is a mucilage of a peculiar na- ture. This mucilage, which has been im- properly confidered as an earth by fome chemifts, differs greatly from the glutinous part. It burns without emitting an empy- reumatic fmell. By diftillation with a naked fire, it affords an acid phlegm, of a brown colour, and a very thick empyreumatic oil towards the end. Its coal is eafily reduced to afhes, which contain fixed alkali. Starch is not foluble in cold water, but when boiled in water, it forms a kind of glue, that, when expofed to a moift air, gradually lofes its confiftence, ferments, be- comes four, and at laft mouldy. The nitrous acid produces the acid of fugar with this fecula, which is perfectly fimilar to thofe we have treated of in the foregoing chapter. A3 SACCHARINE MUCILAGE. 10$ As ftarch forms the greateft part of flour, it cannot be doubted, but that it is the principal alimentary fubflance contained in flour, and in bread. § III. Concerning the Mucilaginous Ex- tractive Part of Flour. By evaporating the pure water with which the pafte was wailied, and from which ftarch had been depofited, Mr. Poulletier obtained a vifcous gluey fubftance of a brown yellow colour, and Jdightly faccharine tafte. This fubftance, denominated by its difcoverer the mucofo-faccharine matter, exhibited all the phenomena of fugar in its combuftion and diftillation. It is this which excites the acid fermentation in the water that floats above the ftarch ; for, as Macquer well ob- ferves, the latter is not at all foluble in cold water. The mucofo-faccharine matter exifts in a very fmall proportion in wheat corn, but may pethaps be more abundant in other kinds of flour. It cannot be doubted, notwithstanding the fmall quantity of this fubftance contained in wheat corn, but that it is principally concerned in the fermentation by which pafte is leavened. This inteftine motion, fo neceffary in the making of good bread, is not yet well underftood. It may perhaps con- fift 106 COLOURING MATTERS. lift in the commencement of fermentation, which is putrid in the gluten, acid in the ftarch, and perhaps fpiritous in the mucofo- faccharine matter; and rrom thefe three inci- pient fermentations mutually impeding each other, the lighter compound, which by bak- ing forms bread, may probably arife. At all events, it is certain, that the three fubftan- ces we fpeak of are fo combined and altered in bread, that they can no longer be fepa- rated. The adtion of heat is fufficient, without fermentation, to produce this inti- mate combination -y for unleavened bread, according to Malouin and Poulletier, does not afford the glutinous matter. From the foregoing fadts we fee, how greatly other kinds of flour differ from that of wheat, and ftill more thofe legumi- nous and farinaceous feeds, fuch as beans, peafe, chefnuts, &c. are far from poffeffing the qualities neceflary to make good bread. CHAP. XVI. Concerning Vegetable Colouring Matters, and their Application to the Art of Dying. T 7Egetables contain colouring matters in * all their organs. Thefe parts differ great- ly from each other; for a vegetable fubftance, which COLOURING MATTERS, IOJ which has no apparent colour, often affumes a very evident tinge, by peculiar menftruums. The art of dying, all the proceffes of which are abfolutely chemical, is founded on the folubility of colouring matters in different menflrua, the method of applying them to fubftances propofed to be dyed, and of ren- dering them fixed. In treating of the pro- perties of each colouring matter, we mail have occafion to fpeak of the principles of this important art, which is excellently treated of in the works of Hellot, Macquer, Le Pileur d'Apligny, Hecquet d'Orval, and the Abbe Mazeas. The colouring matter of vegetables pro- perly fo called, is not yet well known. Rou- ellefuppofed that the colouring matter, which is fo abundant in the vegetable kingdom, was analogous to the gluten of flour; but it is certain, that this matter prefents different chemical characters, according to the bafe with which it is united. When, therefore, it is faid, that a colour is extractive, refinous, &c. the terms apply rather to the bafe, than to the colouring matter. The true colour- ing matter of vegetables ufed in the arts, is doubtlefs of a very fubtle nature, and is perhaps as divifible as the principle of fmell. It may even be fuppofed, that it confifts only in a peculiar modification of the folid and liquid parts of vegetables. It is necef- fary to repeat in this place, that the colour of 108 COLOURING MATTERS. of vegetables is for the moft part produced by the contad: of light; but the manner in which light produces this efFed:, is a pro- blem not yet folved. However this may be, as it is impoffible to feparate the colour- ing m?tter intirely from the vegetable bafe it adheres to, thefe two fubftances are ufually taken together for the colouring matter. No chemift has more accurately diftin- guimed the vegetable colouring matters, considered with refpeft to the art of dying, than Macquer ; and his theory concerning the applying and fixing thefe colours to fubftances intended to be dyed, muft be ad- mitted as highly fatisfadory. As it is our intention to conned: this theory of dying with the hiftory of the chemical properties of vegetable colouring matters, we mall conlider them in the fame point of view. i. A great number of vegetable colouring matters, which are of an extractive or Sapo- naceous nature, are readily diifolved in wa- ter. Baftard rocket, madder, logwood, redwood, and Brafil wood, afford yellow or red colours of this kind. It may be eaiily conceived that fubftances tinged with thefe matters, readily give out their colour to water ; and it is therefore found neceftary, in order to render them durable, to make ufe of fome additional fubftance capable of de- compofing and fixing them ; as for example, crude tartar, alum, and other falts. Thefe falts COLOURING MATTERS, I09 falts are called corrofives. A difengaged acid would produce the fame effe&s, but it would alter the colouring matter. The portion of fupcrabundant acid of the alum unites with the alkali of the colouring fapo- naceous extract, and caufes the relinous part, which is then infoluble in water, to be pre- cipitated on the fubftance intended to be dyed. However, this colouring portion, ren- dered infoluble by the alum, or the corro- five, is of two kinds ; the firft is very folid, and refifts the air, foaps, and all the liquors which dyers call proofs. This kind of co- lour is called a good or ftrong dye. The other is changed by the air, and efpecially by the adtion of the proof liquors : It is called a falfe dye. To difcover the nature of thefe colours, and the duration of dyes in general, Mr. Berthollet propofes the ufe of the de- phlogifticated or aerated muriatic acid, which in a very fhort time, by its excefs of the oxyginous principle, produces the fame ef- fect as the pure air of the atmofphere would effed: in a much longer fpace of time. The quantity of acid required to difcolour and intirely bleach any dyed fluff, as well as the time required for this purpofe, may ferve to determine the folidity and duration of co- lours. It is obfervable that wool takes the dye better than any other fubftance; and that filk, cotton, and flax, in the order we have men- tioned 110 COLOURING MATTERS. tioned them, are dyed with more difficulty, and retain the colouring fubftance more weakly. Writers on the art of dying, hold differ- ent opinions refpedting the manner in which the colouring parts apply themfelves to the fubftances expofed to their contact. Many have fuppofed that this application takes place only in proportion to the number and magnitude of the pores in the various fub- ftances ; and that wool takes the dye better than filk or thread, becaufe its pores are more open and numerous. But Macquer thinks, that the greater or lefs facility with which the colour is applied, depends on the refpective nature of the colouring parts and the fubftance propofed to be dyed ; and that the art of dying is truly an external tinge or painting, which fucceeds and lafts by virtue of an affinity and intimate union between the colour and the dyed fubftance. This celebrated chemift adopted the opinion here recited, in confequence of the nume- rous experiments for which this art is greatly indebted to him. 2. Another kind of colouring matter feems to be compofed of faponaceous extract and refin. Macquer calls them refino-terreftrial matters. When thefe matters are boiled in water, the reiinous fubftance they contain melts, and is difperfed in the fluid by the af- fiftance of heat, and by virtue of the diffolved faponaceous portion ; but it precipitates in oro- COLOURING MATTERS. Ill proportion as the decoction or bath becomes cold. Confequently, when wool, or any- other fubftance is plunged in a decoction of this nature, the relin feparates by cooling, and applies itfelf without any other prepa- ration •, and as it is not foluble in water, it forms a lafting dye. Colouring matters of this clafs are obtained from almoft all aftrin- gent vegetables, fuch as the hufks of nuts, roots of walnut-tree ; or of dock, fumach, bark of alder, fandal-wood, &c. Thefe co- lours are all yellow, and are called root colours by the dyers. They generally ferve to form a very good ground, on which other more brilliant colours may be applied. It may be obferved, that colouring ingredients, which require no preparation either in the bath, or in the ftuff to be dyed, are more eafily applied to ufe than others. 3. The colouring principle of many other fubftances refides in a purely refinous mat- ter, infoluble in water, and fome not even in fpirit of wine ; but they all are foluble in alkalis, which convert them into a kind of foaps, foluble in water. The principal colours of this nature employed in dying are the following : A. The annatto, a kind of fecula, ob- tained by maceration of the feeds of the urucu putrefied in water. This fecula de- pofited during the putrefaction, is firft red, and in procefs of time becomes of a brick duft 112 COLOURING MATTERS. duft colour. The parte is mixed in water with the cendres gravelees, fliortly to be defcribed, and forms a bath, wherein the fluffs intended to be dyed are plunged. A gold, or orange yellow colour, of coniidera- ble beauty, is depoiited without the affifl- ance of a corrofive. B. The flower of carthamus, or baftard faffron, affords a very fine red colour, by "It contains two diftincl the one purely extractive the fame procefs, colouring parts and foluble in water, the other refinous. In order to obtain the latterL the foluble part of the carthamus muft firft be carefully warned away. The remainder is mixed with the cendres gravelees, or fait of foda; and the mixture being lixiviated, forms a bath. But as the alkali alters the colour, and renders it dull, the dyed fluff is plunged in water rendered acid by lemon juice : the acid feizes the alkali, and leaves the colouring matter, which it enlivens, and caufes to be- come red. A coloured fecula is obtained by a iimilar procefs, which, mixed with brianfon chalk in powder, compofes the rouge ufed by the ladies. C. Archil is a pafte prepared with moffes and lichen macerated in urine with lime : The latter dilengages the volatile alkali, which developes the red colcur. Archil mixed with water, affords a dye without any other preparation j with alkalis, it flrikes a violet COLOURING MATTERS. 1 13 a violet colour ; but this is a falfe dye, which changes in the air, and becomes yellow by the action of acids. D. Indigo, which is of a deep violet blue, of a coppery tinge, is a fecula prepared at St. Domingo, and in the Antilles, &c. by macerating the flalks of the anillo, or indigo plant, in ftone troughs, with water. The water becomes blue, and after flrong agi- tation the fecula precipitates. The indigo feparated from the water, is put into cloths to drain, and after being dried in fmall wooden boxes, it is broken into pieces. It is efteemed good when it floats on water, and burns intirely away on a red-hot fhovel. The colouring matter is extracted by alkalis, and applied, without any other preparation, to the .fluffs. It cannot be brightened by acids, becaufe they change its colour. 4. Certain colouring fubftances are foluble in oils. Alkanet, or the red- root of a kind of buglofs, communicates its colour to oil. Spirit of wine likewife diffolves feveral co- louring matters : green feculae diffolve in this menflruum, as well as in oil. It may eafily be conceived, that thefe colours, are not ufed in dying, becaufe the liquids ne- ceffary to extract them cannot be employed. Such are the principal circumftances in which our knowledge of vegetable colours confifts. Every immediate principle of ve- getables may constitute the bafe of thefe co- Vol> IV. H louring 114 DESTRUCTIVE DISTILLATION louring parts, fince they are found of fapo- naceous, reiinous, and extractive kinds. Some even appear to be of the nature of fat oils, being infoluble in water, or ardent fpirit, though they readily combine with al- kalis. Laftly, there are fome which are analagous to the glutinous part, according to Rouelle. There is every reafon to think, that fu- ture inquiries, if ikilfully made, will dis- cover many other properties of thefe fub- flances, which greatly abound in vegetables, and that they will contribute to the im- provement of the art of dying; an art to which chemiftry is well adapted to render the moft important fervices. CHAP. XVII. Concerning the Analyfis of Plants, by de- ftrudtive Diftillation, or a naked Fire. AFTER having examined all the fub- ftances which may be obtained from plants, by fimple methods, which are in- capable of changing them; and after having confidered thefe matters as the immediate principles of organized fubflances, it is ne- cefTary OF PLANTS. II5 ceflary to attend to the alterations they fuf- fer when expofed to heat. The ancient chemifts were acquainted with no other method of analyfing vege- tables, and all their refearches into the na- ture of thefe bodies, confifted in determin- ing how much fpirit, oil, and volatile fait they afforded by diftillation. This method is at prefent no longer efteemed, as it is known, that moft plants afford nearly the fame products; and the diftillation of a great number of different vegetables, made by che- mifts, in other refpects deferving the efteem of the public, has only ferved to undeceive us. In fact, how can it be imagined, that the action of fire, exerted on all the different principles in a vegetable fubftance, fuch as extract, mucilage, oil, refin, fait, gluten, &c. which decompofes each of thefe prin- ciples in a peculiar manner, can afford any knowledge refpecting their nature and quantity ; more efpecially when it is ob- ferved, that the products of thefe feveral decompofitions unite together, and produce new fubftances, fuch as did not exift in the vegetable under examination ? The analyfis of vegetables, by diffyllation, is therefore complex and fallacious. However, as none of the methods which art is in poffeflion of, ought to be neglected, in the chemical examination of any fubftance, we mav have occafional recourfe to this ana- H 1 lyfis, Il6 DESTRUCTIVE DISTILLATION lyfis, always carefully obferving, that it is not too much to be depended on. It ibmetimes happens, that when the effects of aqueous, fpiritous, and oily menftrua, on any fub- ftance, are compared with the alterations produced in it by fire, thefe laft confirm the deductions made from the action of the fol- vents, and by the products of the diftilla- tion, indicate the fubftances contained in greater or lefs quantities, the nature of its falts, &c. But to make valuable deductions from the analyfis by fire, it is neceffary, i . To be well acquainted with the action of fire, on each immediate or proximate prin- ciple, fuch as extract, mucilage, faline mat- ter, oily juices, the fluid, or folid part, &c. 2. To compare the products, afforded by diftillation, of the whole vegetable, with thofe ufually afforded by the proximate prin- ciples, treated in the fame manner. 3. To analyze the vegetable by menftruums, in order to obtain its proximate principles, and to make ufeful inductions from the al- terations it has fuftained by fire. The procefs of diftilling vegetables by a naked fire, is very eafy and fimple. A given quantity, of a dry vegetable, is put into a glafs, or earthen retort, fo as to fill it not more than half or two thirds ; the retort is then placed in a reverbaratory furnace, and a receiver of a proper fize adapted. It was formerly fuppofed nsceffary to ufe a receiver, perforated OF PLANTS. 117 perforated with a fmall hole, to give vent to the air faid to be difengaged from ve- getables, and tending to burft the veflels. But it is at prefent known, that the aeri- form fluid, which efcapes from thefe bodies during diftillation, is fcarcely ever air, but confifts of cretaceous acid and inflammable gas. Now, as thefe elaftic fluids are pro- ducts of the vegetable compound, by fire, as well as the phlegm, the oils, and the vola- tile falts, it is equally neceflary to collect them. For this purpofe, a perforated re- ceiver, communicating with an inverted glafs veflel, filled with water or mercury, may be ufed. By this means, the liquid products are collected in the receiver, and the aeri- form products under glafs veffels, placed on the fhelf of a pneumato-chemical apparatus. When the fubftance diftilled affords a con- crete fait, an adapter, or long glafs veifel, is fixed between the retort and the receiver, in order that the fublimation may be made on its internal furface. The operation is be- gun, by placing a few pieces of lighted char- coal beneath the retort, and the fire is gra- dually increafed till the veffel is red-hot, and nothing more comes over. After the whole has become cold, the apparatus is unluted, to examine each of the products obtained. Though the diftillation of vegetables never affords products which may be confidered as principles of the plant, yet thefe products H 3 differ 1 1 8 PRODUCTS FROM PLANTS differ confiderably from each other, and re* quire to be carefully diftinguifhed. The firft product which comes over, is an aqueous liquor, containing certain odorous and faline principles. As the diftillation ad^ vances, the colour and faline properties of this phlegm become ftronger. It is fuc- ceeded by an oil, whofe colour, confiftence, and weight, gradually increafe. From fome vegetables, a light and fluid oil is obtained ; but from others, a ponderous oil, capable of becoming concrete. The fmell of this oil is always ftrong, and empyreumatic. Dur- ing the time it comes over, a quantity of elaftic fluid is difengaged, which confifts ei- ther of the cretaceous acid, or inflammable gas, but mod commonly of a mixture of both. At this period it is that the volatile alkali fublimes, when the vegetable is of fuch a nature as to afford it. When all thefe fubftances are paft, the reiidue of the vege- table is of the nature of coal. We fhall now proceed to examine more particularly into the nature and origin of each of thefe produdts. The phlegm is produced from the water that enters into the compofition of the vege- table, and partly from the water of vege- tation, efpecially when the matter is not in^ tirely dry ; fo that its quantity is greater or lefs on this account. The phlegm is co- loured red, by a fmall quantity of oily matr ter BY DISTILLATION. 119 ter which rifes, and is ufually rendered fa- ponaceous, by the fait contained in the fluid. The faline matter is mod com- monly acid ; for which reafon the phlegm ufually reddens fyrup of violets, and caufes an effervefcence with cretaceous alkalis. This acid arifes from the mucilage, and the oil. But the phlegm is fometimes alkaline, as happens when nitrous or cruciferous plants, or emullive and farinaceous feeds, are dif- tilled; and it is often ammoniacal, becaufe the volatile alkali fucceeds the acid, and com- bines with it. This fad: may be afcertained by the addition of a fmall quantity of quick- lime, or alkali, by which a ftrong fmell of vo- tile alkali will be produced, when ammonia- cal fait is prefent. Though the acids of vege- tables do not appear to be all of the fame nature, thofe which are obtained, in their diffolution, exhibit the fame external cha- racters : but they have not yet been fuffi- ciently examined to afcertain their properties with any degree of accuracy. The oils ob- tained from vegetables in this method, are all ftrong- fmelling, highly-coloured, and poffefs nearly the fame properties. Thofe parts of vegetables which contain a large quantity of thefe inflammable fluids, fuch as the emulfive feeds, afford a large quantity of oil in their analyiis. Odoriferous plants afford an oil, which, at the beginning, flight- ]y partakes of their peculiar fmell, but quick- H4 \y 120 PRODUCTS FROM PLANTS ly aflumes the characters of other oils of this kind, namely, colour, weight, and an em- pyreumatic fmell. All thefe fluids are very inflammable ; the nitrous acid fets them on fire, and they are foluble in fpirit of wine. They may all, by rectification, be rendered very fluid, light, and colourlefs, and be con- verted into the ftate of etherial or eflential oils. The volatile fait, or ammoniacal chalk, is only obtained from certain vegetables ; but it is not true, as fome chemifts have affirm- ed, that it is afforded only by the cruciferous plants. All plants in general, which con- tain a certain quantity of glutinous or ve- geto-animal matter, afford more or lefs of volatile alkali, by virtue of the mephitis, fhewn by Mr. Berthollet to exift in this ve- getable principle. It is very feldom, how- ever, that any confiderable quantity is ob- tained in the concrete ftate, as it is ufually diflblved in the laft portions of the phlegm. This fait is produced by the union of the mephitis with the inflammable gas of the oil, and for this reafon it moft commonly paffes over towards the end of the diftilla- tion. It even feems, that the volatile alkali, which rifes with the phlegm in the analyfis of certain plants, fuch as the cruciferous plants, poppy, rue, &c. is always the pro- duel of a new combination ; fince Rouelle the younger has fhewn, that the plants them- BY DISTILLATION. J2J themfelves do not contain it in their natural ft ate. The elaftic fluids, difengaged during the diftillation of vegetables, appear to depend on the nature of the vegetable. A plant, which contains a large quantity of oily com- buftible fluid, affords inflammable gas. Mu- cilages, on the contrary, afford cretaceous acid. We have obferved, at the article of the acid of fugar, that Bergman and Fontana obtained a large quantity of cretaceous acid from that fubftance, and that the latter che- mift thinks, that vegetable acids are for the moft part compofed of it. It is not, there- fore, to be wondered, that mucilages, in which Bergman difcovered the fame acid as exifts in fugar, fhou Id afford cretaceous acid. Laftly, there are fome vegetable matters which afford atmofpheric mephitis. Thefe aeriform fluids are not extracted till near the end of the diftillation, when the vegetable becomes intirely decompofed. Hales, who was not acquainted with their nature, ob- ferved, that the quantity of air difengaged during the diftillation of vegetables is greater, the more folid they are ; whence he con- cluded, that this element was the cementing principle and caufe of folidity in bodies. It is eafy to form a proper opinion of this hy~ pothefis, from what has been already faid. CHAP. 122 CHARCOAJL CHAP. XVIIL Of Vegetable Coal, or Charcoal. pHARCOAL is the black refidueofve^ ^ getables, which have fuffered a complete decompofition of their volatile principles, in clofed veflels. The property of affording charcoal is only obferved in fuch organic fubftances as contain the combuftible matter called oil. The formation of coal was for- merly attributed, exclufively, to the decom- pofition of this lafl fuhftance ; but we begin to perceive, that the carbonaceous matter ex- ifts, ready formed, in vegetables, and that the action of fire merely feparates the volatile principles. Charcoal in general is black, brittle, fo- norous, and light ; it retains the form of the vegetable, provided its. texture has been con- fiftent, and the quantity of fluid not very great. If, on the contrary, a foft and fuc- culent plant be decompofed, the volatile matters, during their difengagement, deftroy the organic texture, and afford a friable coal, which does not poffefs the figure of the ve- getable. The quantities of coal vary ac- cording to the folidity and texture of the vegetable. CHARCOAL. 123 vegetable. Wood affords more than herbs $ gums more than refins ; and thefe laft, more than fluid oils. Each vegetable fubftance appears to contain it, in different quantities, if we confider charcoal as one of the imme- diate principles of this kingdom. Charcoal is a fubftance which poffeffes very fingular properties, for the moft part little known. Though it is of the greateft importance in chemiflry, and exhibits phe- nomena of the moft fingular kind, no che- mift has yet attempted to difcover its nature by a connected feries of inquiries. Stahl, who attended more particularly to this fub- ftance than any other chemift, confiders it as the principal repofitory of phlogifton. The knowledge we poffefs concerning the properties of charcoal, is almoft intirely con- fined to its economical ufes ; and the labours of philofophers exhibit nothing which can be called complete reflecting it. The phy- fical properties of charcoal differ according to the ftate and nature of the vegetable ufed in its formation -, it is fometimes hard, and, as we have obferved, retains part of the or- ganization of the vegetable : other fpecimcns are friable, and pulverulent. Pure oils af- ford a coal, in very fine particles, known by the name of lamp-black. Its weight va- ries according to circumftances. When well made, it has neither tafte nor fmell in any fenfible degree. Its colour is alfo fub- jed: 124 CHARCOAL. je<ft to variation, and is of a black more or lefs deep, either fhining or dull. But the moft important inquiry, refpe&ing this product of fire, relates to its chemical prin- ciples. Charcoal, expofed to the moft violent heat, in clofed veffels, is not in the leaft altered. Heated in the pneumato-chemical apparatus, it does not afford inflammable gas, unlefs water be prefent. A ftrong fire reduces it into vapour. When heated with contact of air, it burns, and is reduced to afhes, but with peculiar phenomena, which it is ef- fentially neceffary to diftinguifh carefully from thofe of other combuftible matters. When fet on fire, it becomes red, and burns with a white flame, which is more confider- able, the larger the mafs. It emits no kind of fmoke, but is converted into the elaftic fluid, cretaceous acid, which, according to M. Lavoilier, is a combination of the car- bonaceous and oxyginous principles, the latter forming three-fourths of the whole. In this manner the charcoal becomes gradu- ally confumed, and leaves only afhes, more or lefs white, partly faline, and partly earthy. The different charcoals vary in their inflam- mability; a diftinction which more parti- cularly afcertains their utility in the arts. Seme burn with flame, and are very quickly confumed ; others do not take fire but with difficulty, burn flowly, and are not reduced to CHARCOAL. I25 to afhes but after a long ignition. There are fome, as for example, the charcoal of oils, which do not burn but with the greateft difficulty. This character feems to depend on the adherence of the carbonaceous prin- ciple to the fixed falts of vegetables. Charcoal, expofed to the air, attracts humi- dity, probably becaufe it is very porous, and perhaps likewife by virtue of the falts it con- tains, though they be not in a difengaged ftate. When moiftened, it affords inflammable air, by heat, which arifes from the decompofition of the water; for when that fluid is paffed in vapour through an earthen tube, filled with red-hot charcoal, thefe two bodies are converted into inflammable gas, and aeriform cretaceous acid. The refidue is a fmall quantity of afhes. Rouelle has obferved, that fixed alkali diffolves a confiderable quan- tity of charcoal by fufion. The vitriolic acid, ftrongly heated with charcoal, in powder, is decompofed by that combuftible fubftance, which has a ftronger affinity than fulphur with the oxyginous principle. The nitrous acid is much more rapidly decompofed by charcoal. Dr. Prieftley ob- ferved, that much nitrous gas is produced in this mixture. Macquer found, that the nitrous acid very fenfibly eftervefces with this body, by the afliftance of heat. Mr, Prouft has fucceeded in fetting fire to char- coal, 126 CHARCOAL. coal, by the addition of a nitrous acid, weigh- ing one ounce four drachms and twenty- three grains, in a bottle which held an ounce of diftilled water. The novelty and im- portance of his experiments are fuch, that I fhall quote his own words, extracted from his observations on pyrophori made without alum, &c. inferted in the Journal de Medi- cine for July 1778. " Coal from the extract of carthamus, re- €C duced to powder, and recently calcined, €C detonated very ftrongly with the nitrous <c acid ; and the rapidity with which the " mixture took fire, threw up the powder " in the form of a very beautiful fire-work. ** I calcined very fine powder of common €C charcoal, and the detonation fucceeded tf very well. " I introduced about a drachm of the " powder of charcoal into a very dry glafs *' retort; I then poured in about a drachm " of nitrous acid, which had no fooner " reached the bottom of the retort, than " the detonation took place with the great- '* eft rapidity : a flame of more than four " inches in length iffued out of neck of the U retort while I held it in my hand, which " carried with it the powder, and very " deep-coloured vapours of nitrous acid. " Thefe vapours condenfed into 2 green li- " quor, fcarcely fuming : it confifted of 'f the nitrous acid, weakened by the water " which << CHARCOAL. 127 which entered into the combination of that which detonated firft. I poured new nitrous acid on the charcoal which re- mained in the retort, and continued the procefs till the whole was intirely de- ftroyed by fucceffive inflammation. " I repeated this experiment with cal- 94 cined lamp-black; the events were the u fame : the retort was found to contain " only a fmall portion of afhes, fometimes 94 femi-vitrified, and adhering to the bottom 44 of the retort. •f All charcoals in general attract a con- fi fiderable quantity of humidity. It ap- 44 peared to me, that charcoal calcined in " the evening, and kept till the next morn- 44 ing, was no longer proper for thefe ex- " periments, becaufe it became fenfibly " moiftened in that fpace of time. But the 44 moll Angular circumftance is, that thefe *' experiments are capricious, and do not i€ always fucceed, though with the fame " charcoal, the fame acid, and the fame *• proportions. The following manipula- tion appeared to me to infure fuccefs. If the acid be poured in the middle of the powder, it does not take fire : but if, on the contrary, it be fuffered to run down the fide of the capfule, or crucible, fo as to occupy the lower place, the de- tonation is made from that point; the powder rifes and takes fire, by the nitrous '• acid. <c tc c< <iC 128 CHARCOAL. " acid. When nitrous acid is wanting, the " detonation ceafes of itfelf, and the fur- " rounding charcoal remains black." The action of the other acids on charcoal is not known. This fubftance, afllfted by heat, decom- pofes all the vitriolic falts, and forms livers of fulphur. Itcaufes nitre to detonate, which burns it, by means of the pure air afforded from the fait by the adtion of the fire. A preparation is made for chemical and pharmaceutical purpofes, called nitre, fixed by charcoal. Two parts of nitre, and one of powdered charcoal, are mixed, and thrown into a red-hot crucible on the fire. A ftrong detonation enfues, after which a white mafs remains, confifting of the fixed alkali of the nitre and of the charcoal. By lixiviating this mixture, the water difiblves the fixed alkali, and leaves a fubftance fuppofed to be an earth. Liver of fulphur diffolves charcoal very rea- dily, both by the dry and moift way, and even combines with it more readily than any other fubftance. This difcovery is due to Rouelle. Metals do not unite with charcoal, but their calces recover the metallic ftate when heated with this fubftance. We have feen, at the article of metals, that this phenome- non may readily be accounted for, from the affinity of the oxyginous principle with the carbonaceous principle. The COLOURING MATTERS. 129 The action of vegetable fubftances on char- coal has not been much examined. It is only known, that a mixture of this fub- ftance with fat oils renders them inflam- mable by the nitrous acid; a circumftance which confirms the theory of Rouelle re- fpecting the inflammation of oils by this acid. All the fafts here related, concerning the known properties of charcoal, tend to prove, that this body is compofed of combuftible matter, falts, and earths. The peculiar combuftible matter which conftitutes more than three-fourths of char- coal, or the carbonaceous principle pro- perly fo called, is as yet fcarcely at all known. It appears, however, to have the ftrongeft affinity with the oxyginous prin- ciple, which it takes from almoft every other body, and that in many particulars it re- fembles plumbago. The various uies of charcoal in the arts, and in chemiftry, are w7ell known. Vol. IV. I CHAP, 13° FOT-ASHt. CHAP. XIX. Concerning the Fixed Salts and Earths of Vegetables. "II7HEN a vegetable coal has been burn- ^* ed, a grey, blackifh, or white matter remains, according to the nature of the charcoal. This fubftance, called afhes, is very compounded ; when well made, it con- tains only faline and earthy fubftances, mix- ed with iron, and a fmall quantity of man- ganefe. When the charcoal has been burn- ed with difficulty, the afhes ftill retain a fmall portion of inflammable matter. M. Lavoifier, on examining the wood afhes ufed by the faltpetre-makers, found them to con- tain extractive and refino-extradtive matters. The faline fubftances obtained, by lixivia- tion, from afhes, have been called the fixed falts of plants. The incineration of vege- tables is ufed for obtaining three kinds of falts, which we fhall here defcribe. 1. Pot-afh, from which the vegetable fixed alkali is obtained, is prepared in the north, by burning wood, with which thofe countries abound. This fait is very impure; it often contains combuftible matters, which diminish its whitenefs, and frequently neu- tral sbftA. 131 tral falts, fuch as the vitriols of pot-afh, of foda, and of lime, the muriates of pot-afh and of foda, a fmall quantity of cretaceous foda, with iron and earthy fubflances. To purify this fait, it is diffolved in the fmalleffc poffible quantity of cold water. The fluid becomes charged with the alkali, and fome of the neutral falts 3 and the earth, the char- coal, the iron, and the felenite, often con- tained in pot-afh, are feparated by the filter. This folution is then evaporated to a pellicle, and the feveral falts it contains are fuffered to cryflallize by cooling. After feveral filtra- tions, evaporations, and cryflallizations, when the lixivium no longer affords any neu- tral fait, it is evaporated to drynefs, and cal- cined. The fait is then cretaceous vege- table alkali, mixed with the fame alkali in a cauflic flate : it feems, however, always to contain fome neutral falts, and a fmall quantity of earthy fubflance, which is de- pofited by {landing, and may be feparated by the filter. After which, it may be ufed in the nicefl chemical experiments. 2. Soda, from which the mineral alkali is obtained, is the refidue of the combuflion of plants that grow on the fea coafls. It is prepared at Alicant in Spain, in Languedoc, at Cherbourg, &c. by burning various fpe- cies of plants. At Alicant, they ufe the kalis ; and at Cherbourg, the algas, and fucus, commonly known by the name of I 2 varech. 132 SODA varech. The firft plant contains a much greater quantity of mineral alkali than the fecond, which affords fcarcely any. Thefe different plants are burned in a trench. At Cherbourg, when the combuflion is ad- vanced, and the afhes are very hot, they are ftrongly agitated, and kneaded together with large poles. By this motion, the fub- ftance, which is fufficiently hot to undergo a kind of femi-vitrification, takes the form of hard and folid lumps, known in com- merce by the name of falicore, falicote, la- marie, and alun catin. The names, by which it is more particularly diftinguifhed, denote either the plant from which it was obtained, or the country where it was made. The foda of Alicant, likewife called barilla, is the beft for chemical purpofes, and thofe arts which require much mineral alkali. The foda of Cherbourg, or of varech, contains lefs alkali, and ought not to be ufed in che- mical experiments ; but it is advantage- oufly ufed in the manufacture of glafs, be- caufe the viti*eous frit it affords is found to be very ferviceable in that manufacture. The foda of commerce, chemically con- fidered, is a compound of cauftic foda, cre- taceous foda, cretaceous vegetable alkali in a fmall quantity, vitriols of pot- afh and of foda, marine fait, charcoal, iron in the ftate of Pruffian blue, according to the obfervation. of Henckel, and earth, partly difengaged, and partly FIXED SALTS. I33 partly combined with fixed alkali, as in that of Cherbourg. To feparate thefe fubftances, and obtain pure cretaGcous foda, it is dif- folved in cold diftilled water, and filtered, to feparate the earth, iron, and coaly matter; after which it is evaporated, as we have ob~ ferved concerning pot-afh. This alkali is purified more eafily than that of pot-afh, becaufe, as it cryftallizes more readily, it can be better feparated from the portion of cauftic foda; yet it contains fome of the neu- tral falts, and Pruffian blue, when firft cryf- tallized, which muft be feparated by repeated folutions and cryftallizations. 3. Fixed falts are prepared in pharmacy, which have been greatly recommended by Tachenius, and are ftill diftinguifhed by his name. The procefs of this chemift confifts in placing the plant, whole fait is propofed to be obtained, in an iron pot. This veffel is heated till its bottom is red hot; the plant, which is continually ftirred, emits much fmoke, and takes fire, at which time the pot is covered, (o that the fmoke may be diflipated, and the flame extinguifhed. By this means, the plant is gradually confumed. When reduced to a kind of blackifh afhes, it is lixiviated with boiling water, which af- fords a yellowiih, or brown fait, by evapo- ration to drynefs. This fait is often alka- line, but is very impure ; it is coloured by much extractive matter, which is mixed with I 3 all 134 RESIDUES OF all the neutral falts the plant contained. As it is a faponaceous compound, good effects often follow its ufe ; but it cannot be fup- pofed to poffefs the fame virtues as the plant from which it was extracted, becaufe its principles have neceffarily been altered by the combuftion. It would be of confiderable ufe to examine, analytically, the different fixed falts of plants, prepared after the man- ner of Tachenius, in order to difcover the faline and extractive matters they contain, and to determine their virtues, and the dofe in which each ought to be adminiftered. 4. When all the faline matter is warned off from the afhes of vegetables, the remain- der is a pulverulent fubftance, more or lefs white, or coloured, infipid, infoluble in wa- ter, and hitherto coniidered as an earthy fubftance. Iron may be extracted from this refiduum by the magnet. This metal, as well as the manganefe which vegetable afhes have lately been found to contain, exifted, ready formed, in the vegetable. Many philofophers have fuppofed, that the colours of plants are pro- duced by iron. Mr. Baume, who, in his memoir concerning clays, has mentioned the earthy refidue of vegetables, affirms, that it forms alum with the vitriolic acid, and like- wife felenite, flightly differing from that which is produced by pure calcareous earth. The other acids afford, with this refidue, fpathofe BURNED PL,ANTS. I35 fpathofe falts, and a fmall portion of martial falts. Hence Mr. Baume thinks that the earth of vegetables confifts of clay, and an earth refembling calcareous earth, though it feniibly differs from it, according to him, in not forming quick-lime by the action of fire. He thinks, that the clay is formed in thefe organized fubftances by the collifion to which vitrifiable earth is expofed, and the action of acids with which it combines ; that the clay, once formed, paffes to the ftate of cal- careous earth, by fucceffive elaborations in the tubes of vegetables. We may here obferve, that the difcoveries made in Sweden, on the faline nature of bones, which appear to be the fame with refpecl to animals as the fibrous parts are in vegetable fubftances, render it probable, that this refidue is far from being merely an earth. An accurate analyfis, fuch as has not hither- to been made, may {hew, that this fuppofed earthy fubftance is calcareous phofpate j at leaft we may fufpect this to be the cafe, fince the experiments of Margraaf and Berthollet, who have obtained phofphorus from muf- tard feed, from gluten, and from feveral Other vegetable fubftances. I 4 CHAP. I36 FERMENTATION* CHAP. XX. Concerning Fermentation in general, and the Spirituous Fermentation in particular. A FTER having confidered vegetables in ■*** the ftate in which they naturally exift, we mail proceed to defcribe the changes they experience in different circumftances. Thefe alterations, which intirely depend on their nature, are always the confequence of a phe- nomenon called fermentation. Fermentation is a fpontaneous commo- tion in a vegetable fubftance, by which its properties are totally changed. This commotion is peculiar to the fluids of or- ganic matters; no other fubftances, except thofe which have been elaborated by the principle of vegetable or animal life, being fufceptible of it. Chemifts have not fuffi- ciently attended to this important truth, whofe application to the phenomena which take place in organized bodies, cannot but be of the greateft ufe in medicine. There are feveral circumftances required in order that fermentation may proceed. Such are, 1. A FERMENTATION. I37 1. A certain degree of fluidity : dry fub- flances, in fad:, do not ferment at all. 2. A certain degree of heat. Each kind of fermentation requires a due degree of heat, but cold flops the progrefs of every ferment. 3. The contact of air. On this account it is, that organized fubftances are very well preferved, and are not altered in a vacuum. Chemifts, after Boerhaave, have diftin- guifhed three kinds of fermentation : the fpirituous, which affords ardent fpirit ; the acetous, which affords vinegar, or acid ; and the putrid fermentation, or putrefaction, which produces the volatile alkali. It muft be obferved, that there are many fermenta- tory proceffes which do not feem to belong to thefe three kinds ; fuch, perhaps, are the fermentations of bread, of mucilages, that which developes the colouring parts, &c. It has been thought, that the fermentations always follow each other in the order we have mentioned ; but there are bodies which become acid, without having previoufly un- dergone the fpirituous fermentation -y and there are others which putrify without paffing through the two firft ftages. We may like- wife obferve, that the inteftine motion of maturation appears to conftitute a kind of fermentation, by which faccharine matter is produced or difengaged. The fpirituous fermentation, or that which produces I38 SPIRITUOUS FERMENTATION. produces ardent fpirit, may be confidered with refpedt to, 1. The conditions neceffary to its production ; 2. The phenomena which accompany it; 3. The leveral fubftances fufceptible of this fermentation ; 4. Its caufe; and, 5. Its products. Experience has (hewn, that all vegetable matters are not capable of paffing to the fpi- rituous fermentation, but that the union of feveral peculiar circumftances is neceffary for this purpofe, Thefe conditions are, 1. A faccharine mucilage. This fubftance only is capable of paffing to the fpirituous fermentation. 2. A degree of fluidity, flightly vifcid. If the vegetable fluid be either too thick, or too thin, it will not ferment, 3. A degree of heat, from ten to fifteen degrees of Reaumur's thermometer, or be- tween fifty-five and fixty-five of Fahrenheit. 4. A large mafs, in which a rapid com- motion may be excited. When thefe four conditions are united, the fpirituous fermentation takes place, and is known by the following characteriftic phe- nomena. 1 . An inteftine motion is excited in the liquor, which increafes till the fermentation is well eftablifhed. 2. The bulk of the mixture is quickly augmented, and this augmentation follows the progrefs of the inteftine motion. 3. The SPIRITUOUS FERMENTATION, I39 3. The tranfparency of the fluid is dimi- nished by opake filaments, which are agitat- ed, and carried to every part of the fluid. 4. A degree of heat is produced, equal to eighteen degrees, (feventy-two and a half Fahrenheit) according to the Abbe Rozier. 5. The folid parts, mixed with the li- quor, rife and float, in confequence of the difengagement of elaftic fluid. 6. A large quantity of cretaceous acid gas is difengaged. This gas forms a ftratum in the upper part of the fermenting vats, which may be ealily diftinguifhed from air. In this ftratum it was, that Dr. Prieftley and Due de Chaulncs made their valuable ex- periments. Candles, plunged in this ftratum, are extinguished, and animals die therein ; lime-water is precipitated, and cauftic alkalis cryftallize perfectly. This acid, contained in the fermenting vats of brew-houfes, fre- quently produces the moil fatal effects on the workmen. 7. The difengagement of this gas is ac- companied with the formation of a great number of bubbles in the vifcid liquor, through which the cretaceous acid mull pafs. All thefe phenomena gradually ceafe, in proportion as the liquor lofes its fweet and mild tafte, and becomes brifk, penetrating, and capable of producing intoxication. Neceflity has induced mankind to prepare fermented 140 SPIRITUOUS FERMENTATION. fermented liquids with a great number of different vegetable fubftances ; but experi- ence has fhewn, that faccharine matters alone are capable of forming this kind of fluid. The following being moft commonly ufed, require to be enumerated. 1. The juice of grapes produces wine, properly fo called : it is the beft of all fer- mented liquors. The art of cultivating vines, which is of great importance, requires an attention to the following objects. 1. The nature of the foil. It is known, that a dry foil is in general well adapted to this plant, and that a ftrong foil does not agree with it. 2. The cultivation of this vege- table. It is pruned; its branches are bent, to impede the courfe of the fap ; care is taken that it be expofed to the heat of the fun, and more efpecially to the heat reflected from the earth, &c. It is not manured, &c. 3. The hiftory of its vegetation, its expofi- tion, its flowering, the formation and ripen- ing of the grape. 4. The accidents to which it is expofed, fuch as froft, heavy rain, moif- ture, &c. 5. The time of vintage, which fhouid be dry and hot. Thefe preliminary circumftances being known, the art of mak- ing wine is to be confidered, which coniifts in putting the ilalked grapes into a veffel, expofed to a heat of fifteen or fixteen de- grees, to break, agitate, and turn them over. When the fermentation is excited, and all its phenomena SPIRITUOUS FERMENTATION. 141 phenomena take place, the juice of grapes, or muft, mould be neither too fluid, nor too thick ; in the firft cafe, it requires to be thick- ened by boiling; in the latter, it is diluted with water. When the wine is made, it is drawn off into cafks, which are left open, where it experiences a fecond infenfible fer- mentation, by which its principles are more intimately combined ; a fine lye, and a fait, known by the name of tartar, being preci- pitated. To preferve the wine, rags, dipped in fulphur, are burned in the cafk which contains it. The knowledge of the different kinds of wine is an object of confiderable importance. France produces a great number of excellent wines. Thofe of Burgundy are preferable to any other for conftant ufe, becaufe their principles are perfectly combined, and no one predominates over the other. The wines of the province of Orleans refemble thofe of Burgundy, when they have been matured by keeping, which combines the excefs of ardent fpirit they contain with their other principles. The red wines of Cham- paigne are excellent, and of a delicate fla- vour. The white wine of this province, which does not fparkle, is to be preferred to the fparkling wine, whole penetrating and fubacid tafte, as well as its property of fparkling, depend on the cretaceous acid contained in it, when bottled before the fer- mentation 14^ SPIRITUOUS FERMENTATIONi mentation was finifhed. The wines of Lari-* guedoc and Guienne are of a deep colour* and are excellent bracers and ftomachics, efpecially when of a good old age. The wines of Anjou are white, very fpirituous, and intoxicate quickly. As to foreign wines, thofe of Germany, known by the name ofRhenifh and Mofelle, are white, and very fpirituous ; their tafte is keen and penetrating, and they quickly produce intoxication. Some wines of Italy, fuch as thofe of Orvieto, Vicenza, the Lachryma Chrifti, &c. are well fermented, and refemble the good wines of France. Thofe of Spain and of Greece are in general fweet, crude, imperfectly fermented, and very unwholfome. We muff, however, ex- cept thofe of Rota and Alicant, which are with juftice efteemed to be ftomachic and cordial. 2. Apples and pears afford cyder and perry. This fpecies of wine is very good, and affords good brandy, as M. d'Arcet has fhewn. 3. Cherries afford a tolerable good wine, from which a kind of brandy is diftilled, called Kirchenwaffer by the Germans. 4. Apricots, peaches, and plumbs, afford a wine of inferior quality. 5. Sugar, diffolved in water, ferments readily : from this kind of wine, a fpirit, called rum, taffia, guildive, &c. is made. 6. The SPIRITUOUS FERMENTATION. I43 6. The feeds of gramineous plants, and e- fpecially barley, afford a fpecies of wine, call- ed beer. The art of brewing confifts in the following proceffes. Barley is fteeped in water for thirty or forty hours, after which it is laid in a heap, to fprout or germinate ; it is then dried in a kiln, and the buds fe- parated by lifting ; after which it is coarfe- ly ground, and is diftinguifhed by the name of malt. A certain quantity of malt is put into a veffel, called the mafh-tun, on which water, nearly boiling-hot, is poured, which diffolves the mucilage. This being drawn off, a fecond quantity of heated water is poured on the malt, and in like manner drawn off. This fluid, called wort, is boiled up with hops, and is put, together with yeaft, into a veffel, called the cooler. When the fermentation begins to fubfide, the beer is ftirred up, and drawn off into calks ; the fecond fermentation throws up a fcum, called yeaft, which ferves to ex- cite fermentation in future brewings. The germination developes a faccharine matter in the barley, to which it owes its property of forming wine : the fame procefs fucceeds with moft other gramineous feeds. The whole of thefe facts prove, that the faccharine matter is the only principle of vegetables capable of pairing to the fpirituous fermentation, and that water is neceffary for the production of this inteftine motion. M. Lavoifier 144 SPIRITUOUS FERMENTATION. Lavoifier thinks, that this fluid is decom- pofed in the operation : the oxyginous prin- ciple feizes the carbonaceous matter of the fugar, and forms cretaceous or carbonaceous acid, which is difengaged during this fer- mentation ; while the bafe of the inflam- mable gas unites with the oil of the faccha- rine fubftance, and forms a very light com- buftible fubtle body, containing much lefs carbonaceous matter than the fugar, and much more inflammable : this is ardent fpirit. The product of all thefe fermenting fub- ftances, is a liquor more or lefs coloured, of an aromatic fmell, a penetrating and hot tafte, which, in fmall dofes, aflifts the action of weak fibres, but produces intoxication when taken too largely. It is univerfally known by the name of wine. The wine of grapes, for example, is com- pofed of a large quantity of water, ardent fpirit, an effential fait called tartar, and an extracto-refinous matter, which produces the colour in red wines. Before wx proceed to defcribe the methods of feparating thefe fubftances, it will be proper to defcribe the ufes and properties of the fluid itlelf. Wine diflblves many fub- ilances, by virtue of the water, the ardent fpirit, and the effential acid fait, of which it is formed. It unites with extracts, refins, certain metals, &c. On thefe properties depend WINE* J45 depend the preparations of medicinal wines, fuch as, 1 . Emetic wine, prepared by ma- cerating four ounces of crocus metallorum in two pounds of good white wine; the li- quid is filtered, or is ufed without filtration, in paralytic or apoplectic cafes. 2. Chaly- beat wine, made by digefting one ounce of Heel filings with two pounds of white wine : it is an excellent tonic and aperitive medicine. 3. The wines of vegetables, pre- pared (a) either with red wine, in which aftringent or aromatic plants are macerated ; (b) or with white wine, which is ufually em- ployed with antifcorbutic plants ; (c) or with Spanith wine : the wine of Squills, and alfo the liquid laudanum of Sydenham, are pre- pared with this wine. The latter is made by digefting two ounces of fliced opium, one ounce of faffron, a drachm of powdered cinnamon and cloves, in a pound of Spanifh wine. This medicine is a very good feda- tive, taken in the dole of a few drops, efpe- cially in cafes in which it is feared that opium may weaken the patient, or flop fome ufeful evacuation. The a&ion of fire is commonly ufed to decompofe wine, and feparate it into its feve- ral principles. The diftillation is performed in an alembic of tinned copper, to which a receiver is adapted : as foon as the wine boils, a colourlefs fluid, flightly opake, and milky, of a hot and penetrating tafte, and a Vol. IV, K ftrong I46 WINE. ftrong agreeable fmell, comes over. This fluid is received, till the vapours no longer take fire by a candle. It is called brandy, and confifls of water, ardent fpirit, and a fmall portion of oil, which renders it milky at firft, and after a certain time colours it yellow. The colour of old brandy, in com- merce, does not, however, arife from the oil alone, which comes over in the diftilla- tion, but likewife from the extra&ive mat- ter it takes from the cafk in which it is con- tained. Brandy is the fluid from which ar- dent fpirit is extracted, as we fhall hereafter fee. The refidual liquor, after it has afforded fpirit of wine, is of an acid aufiere tafte, turbid, and depofits a large quantity of fa- line cryftals, which appear to be tartar. The wine is therefore intirely decompofed, and cannot be reftored to its former proper- ties by combining the fpirituous produd: with the refidue. Hence the analyfis ap- pears to be complicated. If the refidue of wine which has afforded brandy be evapo- rated, it takes the form and confiftence of an extradl. The colouring part may be fe- parated by the addition of fpirit of wine, which does not adt on the tartar. Water does not precipitate this tindlure. By evaporation of the tindture to drynefs, a refidue is obtain- ed, which quickly takes fire, and is foluble in water; it is a true refino- ex tractive fub- ftance, which the ardent fpirit, formed by fermen- WINE. 147 Fermentation, has extracted from the fkins of the grapes. From this analyfis it appears, that wine confifls of water, ardent fpirit, tartar, and colouring matter; we have al- ready explained the nature and properties of two of thefe fubftances, namely, water, and the colouring extract ; ardent fpirit and tartar remain, therefore, to be treated of. Before we proceed to fpeak of thefe, we (hall take notice of a fubflance that precipi- tates from wine during its fermentation, and is called lees. It confifls of the feeds and fkins of grapes, impure tartar, and vitrio- lated tartar. By diftillation with a naked fire, it affords brandy : treated in a retort, it affords acid phlegm, oil, volatile alkali, and its coal contains cretaceous vegetable alkali and vitriolated tartar. The incinera- tion of the lees of wine, in the open air, affords a cauftic fixed vegetable alkali, mix- ed with vitriolated tartar, and known in commerce by the name of cendres gravelees. The account we fhall proceed to give of fpirit of wine, and of tartar, will complete what remains to be faid concerning the lees of wine. K 2 CHAP* ARDENT SPIRIT. C PI A P. XXI. Of Ardent Spirit, or the Product of the Spirituous Fermentation. WE have feen that brandy, obtained by diftilling wine with a naked fire, is a compound of ardent fpirit, water, and a fmall portion of oil. Diftillation is ufed to feparate thefe fubftances, and to obtain ar- dent fpirit in a ftate of purity. There are feveral methods of diftilling fpirits of wine. M. Baume advifes to diftill brandy a con- fiderable number of times, by a water-bath, to obtain 'all its fpirit. He recommends the feparation of the firft fourth part of the pro- duct of the firft diftillation, and likewife of the firft half of the product of the following diftillation s; to mix all thefe together, and to rectify by a gentle heat. The firft half of the fluid, which paffes in this rectification, is the pureft ardent fpirit, called alkohol; the remainder is lefs ftrong, but very good for ordinary purpofes. Rouelle directs, that half the brandy made ufe of, be drawn off by diftillation on the water-bath ; this firft product is common fpirit of wine, which, being rectified twice, and reduced to about two- ARDENT SPIRIT, 149 two-thirds, becomes a flronger fpirit. This is to be again diftilled with water, according to the procefs of Kunckel, which feparates the oil > the diftilled fpirit, being again rec- tified, may be depended on as perfectly pure. The refidue of brandy, after diftillation, is water, containing colouring matter, on the top of which a peculiar oil floats. Hence it may be obferved, that the pu- rity and ftrength of ardent fpirit muft differ according to the proceffes ufed in obtaining it. A method of difcovering its purity has long been fought after. It was formerly fuppofed, that fpirit of wine, which readily catches fire, and leaves no refidue, is very pure; but it is at prefent well known, that the heat excited by its combuftion is fuffi- ciently ftrong to diiiipate all the phlegm it might contain. Another proof has been propofed, by means of gunpowder : when fpirit of wine, let on fire in a fpoon upon gunpowder, does not inflame it, it is con- iidered as bad ; if, on the contrary, it fets it on fire, it is judged to be excellent. But this proof is very fallacious ; for when a large quantity of the beft fpirit of wine is burned on a fmall quantity of gunpowder, the water it affords during its combuftion moiftens the powder, and prevents its taking fire; whereas it may be inflamed by burn- ing a very fmall quantity of phlegmatic fpirit of wine on its furface. This method is K 3 therefore 150 ARDENT SPIRIT. therefore no more to be depended on than tho former. Boerhaave has defcribed a very good procefs for afcertaining the purity of this fluid : it confirts in throwing the very dry powder of fixed fait of tartar into fpirit of wine ; this unites with the fuperfluous water of the fpirit, and forms a more pon- derous and coloured fluid than the ardent fpirit, with which it does not mix, but falls to the bottom. Laftly, M. Baume, on the confideration that fpirit of wine is lighter the purer it is, has contrived an areometer, by which the degree of purity of this fluid may be accurately afcertained. When the inftrument is plunged in fpirit of wine, it links deeper, in proportion as the fluid is purer. By experiments carefully made, he has determined, that the pureft and moft highly rectified fpirit of wine gives thirty- eight degrees of his areometer. The me- thod of constructing this inftrument, as well as the refults afforded by different quantities of fpirit of wine, may be {ten in his ele- ments of pharmacy, and may be applied to determine the ftrength of fpirit of wine by the hydrometer.* Pure * Notwithstanding the labours of many ingenious che- mifts, and particularly thofe of Mr. Bories, related in his Memoir, which obtained the prize propofed by the ftates of Languedoc, in 1772, and publifhed at Montpelier in the year 1774, much remains to be done before the ftrength ARDENT SPIRIT. 151 Pure ardent fpirit, obtained by the procefs we have defcribed, is tranfparent, exceedingly fluid, and fo light, that it weighs four hundred and eighty grains, in a bottle which contains five hundred and feventy fix grains of diftilled water. Its fmell is penetrating, and agreeable ; its tafte is hot, and ftrong. It is extremely volatile, rifing and paffingover in clofe veiTels, by a very gentle heat, and is by this means K 4 feparated ftrength of fpirits can be determined, with fufficient accu- ra :y e\en fcr commercial purpofes. If ardent fpirit, which is fo highly dephlegmated as not to liquefy hot pulverized all: di, be confidered as pure fpirit, or the ftandard extreme, diftilled wacer forming the other extreme, it will then be necelTar^ to afcertain, by experiment, \. The fpeciflc graviry of 1 certain number of mixtures of water and this f, irit, taken fo near each other, as that the intermediate fpecmc gravities may not fenfibly differ from thofe deduced mathematically in the ufual manner. 2. The expanfions, or variations of fpeciflc gravity of thefe mixtures, at the different temperatures of the atmofphere. 3. The change of fpeciflc gravity, produced by the folution of faccharine or oleaginous fubltances in thefe fpirits. 4. Eafy methods muft be devifed to mew the prefence and quantity of the laft mentioned fubftances ; and alfo, 5. To deter- mine the fpeciflc gravity of the fluid. Thefe requifites demand a great number of accurate experiments to be made. Rectified ardent fpirit, re- peatedly affufed on dry alkali, till it would no longer diffolve or liquefy it, was found, by Mr, Bories, by many experiments, to have the following fpeciflc gravity. Reaumur's Therm. 4- ro°==82o|||| * i5°=8i75i!s 4* 20°=8i3|48 05s Th( 152 ARDENT SPIRIT. feparated from the fmall quantity of water it might contain. The firft portions are the moft volatile, and pure. It was formerly thought, that a large quantity of air was always difengaged during the diftillation of fpirit of wine. This fuppofed air is now. known to be the fpirit itfelf, in the form of gas. When ardent fpirit is heated with the contact of air, it foon takes fire, and exhi- bits a light flame, white in the middle, and blue at the fides ; it completely burns away, when pure. Many chemifts have at- The fpecific gravities of mixtures, by meafure, of the foregoing fpirit with diftilled water, were as under. Temperature »J- 150 Reaumur. Spirit 10 Water o Specific gravity 8i7sI!t 9 - - - 1 844!ot! 8 - - - 2 869SII 7 - - - 3 893HH 6 4 91STW? 5 - - " "5 934T-J35f 4 - - - 6 I ----- . 95"i?!l 3 7 9<>S\V& 2 - - 9 976^|| 1 - - - 9 - 987t7oYt O - - - IO ----- 1. 000 I find, by diftilling 20 meafures of the beft fpirit of wine of the ftiops, (Sp. Gr. = 836) in glafs veffels, by a lamp, that the firft meafure which came over had a fpecific gravity of 820, at a temperature of 710 of Fahrenheit, or about »J- 1 7 1 of Reaumur. This, which is the ftrongeft fpirit mere diftillation can afford, contains about one part in the hundred of water, of which it may be deprived by alkali. Note of the Tranflator. tempted ARDENT SPIRIT. 1 53 tempted to difcover the product afforded by fpirit of wine in burning. They found that its flame is accompanied with neither foot nor fmoke ; and that the volatilized matters when condenfed, are pure water, without tafte or fmell, abfolutely in the ftate of dif- tilled water. Boerhaave, from this pheno- menon, fuppofed, that the flame is pro- duced by the water ; and this opinion is confirmed by the knowledge we at prefent poflefs, refpecting the inflammable air ob- tained by the decompoiition of water, and the water obtained by burning inflammable gas. Mr. Lavoifier difcovered, that when fpirit of wine is burned in a chimney a- dapted to receive the vapours, a larger quan- tity of water is obtained than the whole of the fpirit made ufe of amounts to; whence it follows, that this liquor contains a large quantity of inflammable gas. On the other hand, Mr. Berthollet has remarked, that when a mixture of this fpirit and wrater is burned, the refidual fluid precipitates lime- water. This experiment fhews, that ardent fpirit contains a fmall quantity of carbona- ceous matter, which, by its combuftion or combination with the oxyginous principle, forms the cretaceous acid. Chemifts have adopted different opinions reflecting ardent fpirit ; Stahl, Boerhaave, and fome others, have coniidered this fluid as a compound of a very attenuated oil, a fubtle acid, and water. 154 ARDENT SPIRIT. water. Others, at the head of whom may- be placed Cartheufer and Macquer, think that fpirit of wine is formed by the union of phlogifion and water. The nature of this fluid is not yet well known. Spirit of wine, expo fed to the air, evaporates at a temperature of 550, and leaves no refidue, except a ftnall quantity of water, when it has not been well dephlegmated. This eva- poration in the air is more rapid, the hotter the atmofphere ; and produces a degree of cold, which is ftronger in proportion to its rapidity. Spirit of wine has the form of an elaftic fluid at 185 degrees of Fahrenheit's thermometer. Spirit of wine unites with water in all proportions, and is perfectly foluble in that fluid. This folution is attended with heat, and produces mixtures, whofe ftrengths are greater in proportion as the quantity of ar- dent fpirit is greater. The affinity of com- bination between thefe two fluids is fo ftrong, that water is capable of feparating fpirit of wine from many bodies with which it may be combined -y and on the contrary, fpirit of wine decompofes moft faline folu- tions, and precipitates the falts. From the confideration of this laft property, it is, that Boulduc propofes the ufe of fpirit of wine to precipitate the falts contained in mineral waters, and to obtain them unaltered. Spirit of wine has no aftion on pure earths. ARDENT SPIRIT. 155 earths. It is not known whether it is al- tered by ponderous earth and magnefia. Lime appears capable of producing fome change in this fluid, fince it acquires a degree of fmell when diftilled from that earthy fub- ftance. But this alteration has not been properly inquired into. Fixed alkalis appear really to decompofe fpirit of wine, as is known by the medical preparation called the acrid tincture of tar- tar. To prepare this, pot-aih is melted in a crucible, pulverized while hot, and put into a matrafs ; highly dephlegmated fpi- rit of wine is poured on, to three or four fingers depth ; the matrafs is clofed with another of a fmaller iize, luted together, and the whole is digefted on a fand bath, till the fpirit has acquired a reddifli colour. A great or lefs quantity of alkali remains at the bottom of the veflel. This acrid tinc- ture of tartar affords, by diftillation, a fpirit of wine of a fweet fmell, fcarcely altered ; and a fubftance remains in the retort re fern - bling a faponaceous ex t raft, which diftilled with a naked fire, affords fpirit of wine, volatile alkaline fpirit, and a light empyreu- matic oil. In this operation, a fmall quan- tity of charcoal is formed, which is found to contain the vegetable alkali. The ex- periment feems to (hew, that fpirit of wine contains an oil which is feized by the fixed alkali, and forms a true foap kept in fo- lution I56 ARDENT SPIRIT. lution in the portion of ardent fpirit which is not decompofed. The lilium of Para- celfus does not differ from the acrid tincture of tartar, excepting that the fixed alkali employed in its preparation appears to be rendered cauftic by the metallic calces with which it was heated. The martial, jovial, and cupreous reguli of antimony, each in the quantity of four ounces, are fufed toge- ther, then reduced into powder, and detonated with eighteen ounces of tartar, and as many of nitre; the whole being melted, pulverized, and put into a matrafs, highly rectified fpi- rit of wine is poured on, to the height of three or four inches above the mixture. By digeflion on a fand bath, the fpirit aiTumes a beautiful red colour, deeper than that of the preceding tincture, but prefenting the fame phenomena. The former tindture may be made intirelv fimilar to the lilium of Paracelfus, by digefting fpirit of wine in the cauftic fixed alkali, inftead of ufing fait of tartar, which is not deprived of its cretaceous acid, unlefs it has been kept red hot a long time. Mr. Berthollet afcertained that thefe tinctures are merely folutions of cauftic vegetable alkali in fpirit of wine, and that they afford an ufeful method of ob- taining the alkali very pure, by evaporation of the fpirit. Spirit of wine has the fame action on pure foda. The acrid tinctures of tartar are excellent bracers, and powerful deobflruents. ARDENT SPIRIT. I57 deobflruents. They are ufed in thofe cafes where the natural forces of the patient are infufficient to favour the crifis, as in the malignant fever, the worft kind of fmall pox, &c. The action of the cauftic volatile alkali on fpirit of wine has not yet been exa- mined. All the acids prefent very important pheno- mena with this fpirituous fluid. When con- centrated oil of vitriol is poured on an equal quantity of rectified fpirit of wine, a ftrong heat, with a remarkable hilling noife, is produced ; the two fubftances become co- loured, and emit a fweet fmell, refembling that of lemon-s, or the apple called golden rennet. If the retort, in which this mix- ture is ufually made, be placed on a fand bath with large receivers adapted, the firft being plunged in a vefiel of cold water, the products are, 1 . A fpirit of wine of a fweet fmell. 2. A fluid called ether, of a very agreeable fmell, extremely volatile, whofe prefence is afcertained by the ebullition of the liquor contained in the retort, and by the large ltrias which run down the fides of the vefiel. The receiver muft now be kept cool by wet cloths. 3. After the ether, a fulphureous fpirit paffes, whofe white colour and fmell indicate the proper time for chang- ing the receiver, in order to have the ether feparate, 4. At the fame time a light yel- lowifh 158 Ether. lowifh oil is volatilized, which is called fweet oil of wine. The fire muft be greatly lowered after the ether is paffed, becaufe the matter contained in the retort is black, thick, and fwells up confiderably. 5. When the fweet oil is all diftilled, fulphureous acid next comes over, which becomes thicker and thicker ; and towards the end dirty and black oil of vitriol. 6. The operation be- ing continued by a gentle heat, the refidue becomes perfectly dry, and has the form and confidence of a bitumen. By expofure to a flrong heat, an acid liquor and a dry and yel- lowifh fubflance refembling fulphur, is ob- tained. M. Baume, who has made a great number of experiments on vitriolic ether, has very carefully examined this refidue, and found it to contain martial vitriol, Pruf- lian blue, a faline fubflance, and a peculiar earth, whofe nature he has not afcertained. He even affirms, that the yellowifh fubli- mate it affords, is not fulphur, but that it remains white and pulverulent, without taking fire on the coals. To thefe details we fhall add, that the refidue of ether af- fords new ether, by the addition of one- third of fpirit of wine dephlegmated by fait of tartar, and diflilling the mixture, as Mr. Cadet has fhewn. Thefe diilillations may be repeated feveral times, and from a mix- ture of fix pounds of oil of vitriol and fpirit of wine, to which fifteen pounds of the lat- ter ETHER. I59 ter fluid are fucceflively added, more than ten pounds of good ether may be obtained. The operation we have described, is one of the moft fingular in chemiftry for the phenomena it exhibits ; and at the fame time one of the moft important, with refpedt to the explanation it affords concerning the compofition of fpirit of wine. There are two opinions refpe<5ting the formation of ether, which it is neceffary to explain. Macquer, who, as we have obferved, con- fiders fpirit of wine as a compound of water and phlogifton, thinks that the oil of vitriol takes the water from this fubftance, and caufes it to approach gradually to the cha- racters of oil. According to this opinion, therefore, fpirit of wine firft paffes over icarcely altered ; next a fluid, which occu- pies the middle place between water and oil ; and laftly, a true oil, becaufe the vitriolic acid a<5ts fo much the ftronger on the principles of the fpirit of wine, as the heat is more confiderable. Bucquet made a ftrong objection to this theory ; namely, that it is difficult to conceive, how the oil of vitriol, charged from the firft with a certain quantity of water it had taken from the fpirit of wine, could ftill, not- withstanding this dilution, re-adt fo ftrong- ly on a portion of the fame fpirit, as to put it into the oily ftate. He therefore propofed another opinion refpeCting the pro- duction l6o ETHER, dudiion of ether. He confidered fpirit of wine as a fluid compofed of oil, acid, and water ; and imagined, that when the acid of vitriol is mixed with the fpirit, a kind of bituminous fluid is produced, which af- fords by heat the fame principles as all bitu- mens ; namely, a light, odorous, very com- buftible oil, or a fpecies of naptha, which is the ether, and afterwards a lefs volatile and more coloured oil, which is the fweet oil of wine. We mall, in fact, perceive by the properties of ether, which we are about to explain, that this fluid has all the cha- racters of a highly attenuated oil, fuch as naptha. This theory does not explain, with fufficient perfpicuity, what happens during the preparation of ether. The oxy- ginous principle appears to be taken from the vitriolic acid by the fpirit of wine, and to be one of the principles of the ether. Ether obtained by the procefs we have defcribed, is not in a Hate of purity, but contains fpirit of wine and fulphureous acid. It muft be rectified by diftillation in a retort, on a fand bath, with the addition of fixed al- kali. The fait combines with the fulphu- reous acid, and the ether palfes over in a ftate of great purity, by the gentleft heat. The firft part of this product being received feparate, is the pureft and mod highly rec- tified ether. Ether is a fluid much lighter than fpirit of ETHER. l6l of wine, of a ftrong, fweet, and very ex- panfible fmell, of a hot and penetrating tafte. It is fo volatile, that it is inftantly diffipated by agitation, or pouring out. During its evaporation, it produces a de- gree of cold fufficient to freeze water, as M. Baume has (hewn in his experiments. It takes the form of gas, which burns with great rapidity. Air, which holds ether in folution, may be paffed through water with- out lofing its fmell and inflammability. Ether takes fire very readily when heated in the open air, or brought into contact with an in- flamed fubftance. The electric fpark likewife fets it on fire. Its flame is very luminous, and leaves a black coaly mark on fubflances expofed to it. M. Lavoifier has proved, that cretaceous acid is formed during the combuftion of this liquor ; and Mr. Scheele found that the refidue of ether burned on a fmall quantity of water, contains vitriolic acid. Ether difTolves in ten parts of water, ac- cording to the Count de Lauraguais. The phenomena produced by adding to ether all the faline fubflances, have not yet been exa- mined ; little more being known, than that the action of fome acids, lime, and fixed alkalis, do not appear capable of changing it. The cauflic volatile alkali mixes with it in all proportions, and forms a fluid, whofe odour may be very ufeful in fpafmodic diforders. Vol. IV. L * Oil l62 ETHER. Oil of vitriol becomes much heated by mix- ture with ether, and converts a considerable part of it into fweet oil of wine by diftilla- tion. The fuming nitrous acid excites a con- fiderable effervefcence ; the ether appearing to become more confiftent, oily, and of a deeper colour in this experiment. Ether has not been combined with the other faline fub- ftances, nor even with the inflammable mi- neral fubftances. It is afcertained, that ether diffolves eflential oils and refins, like fpirit of wine ; and etherial tinftures are ac- cordingly ufed in medicine. Ether is confidered as a powerful tonic, and anti-fpafmodic remedy. It is ufed in hyfteric diforders, and fpafmodic cholics, and is of excellent fervice in cafes where digeftion is ill performed on account of weaknefs of the ftomach. It muft be ad- miniftered, however, with prudence, be- caufe its exceflive ufe is dangerous. It is likewife fuccefsfully applied externally in head-achs, burns, &c. Hoffman, who made many experiments with the vitriolic acid, and fpirit of wine, ufed a medicine com- pofed of fweet oil of wine diffolved in ar- dent fpirit, which he called his mineral anodyne liquor. The Faculty of Medicine at Paris have added ether to this liquor, and pre- fcribe it to be prepared by mixing two ounces of the fpirit of wine which paffes in diftilla- tion before the ether, two ounces of ether, and ETHER* l6j and twelve drops of fweet oil of wine. This medicine is employed for the fame purpofes as ether, but is far from having the fame efficacy. The nitrous acid acts very ftrongly on fpirit of wine. M. Navier is the firft who de^ lcribed an eafy and cheap method of prepar- ing nitrous ether. He directs twelve ounces of very pure and well reclined fpirit of wine to be poured into a very ftrong glafs bottle, and plunged in cold water, or which is ftill better, in pounded ice : to this is to be added, in feveral portions, the liquor being agitated each time, eight ounces of fpirit of nitre ; after which the bottle muft be clofed with a good cork, covered with leather, and well fecured. This mixture is then to be left in a remote or private place, to prevent accidents that might arife from the burfting of the bot- tle, which fometimes happens. After fome hours, bubbles arife from the bottom of the veifel, and are gradually collected at the top, forming a ftratum of true ether. This difengagement continues from four to fix days. As foon as the liquor appears to be at reft, the cork muft be pierced with an in- ftrument, that a certain quantity of air may efcape, which, without this precaution* would rufh out on opening the bottle, and carry the ether with it. As foon as the air is diffipated, the bottle is to be uncorked, and the fluid it contains poured into a funnel, L 2 whofe 164 ETHER. whofe lower aperture being flopped with the finger, the reiidue may be feparated from the ether which floats above, and mud be kept in a feparate veffel. Mr. Woulfe defcribes another procefs for preparing nitrous ether. It confifts in uf- ing very large veffels, that the difengaged air may have a confiderable fpace to expand itfelf in. A matrafs of white glafs, con- taining eight or ten pints, and terminated by a neck of feven or eight feet long, is placed on a tripod fufRciently high to admit of a chafing-difh being put underneath. To the neck of this matrafs, a tubulated head is adjufted, with a tube of feven or eight feet long adapted to its beak. The lower extremity of the tube is received in a veffel with two necks, whofe lower part is drawn out into a tube, which is inferted in a bottle. To the other neck of this receiver is adapt- ed the apparatus of bottles, which we have frequently mentioned as the invention of Mr. Woulfe. Thefe veffels being well luted together, one pound of rectified fpirit of wine, with an equal quantity of fuming fpirit of nitre are poured into the matrafs, through the perforation in the head ; this perforation is then clofed with a ground ftopper wrapped round with a piece of lea- ther. As foon as the mixture is made, it becomes ftrongly heated, vapours are difen- gaged, which pafs rapidly along the neck of the ETHER. 165 the matrafs, and by applying a fufficient degree of heat to make the mixture boil, nitrous ether paffes into the receiver. This procefs, though very ingenious, has its in- conveniencies. The adjuftment of the ap- paratus is difficult, and the veffels are very expenfive; beiides which, the method is dangerous ; becaufe, notwithflanding the fpace afforded to the vapours, they are dif- engaged with ib much rapidity, that the veffels frequently fly in pieces. Mr. Bogues, in the year 1773, publifhed another procefs for making nitrous ether. He directs one pound of fpirit of wine to be mixed with one pound of nitrous acid, weakened fo as to exhibit only twenty-four de- grees ofBeaume's hydrometer, in a glafs retort, containing eight pints ; to this a receiver of twelve pints is to be adapted, the air is fuffered to efcape by adjufling the barrels of two quills at the juncture of the lute, and the diftillation muff be performed by a very gentle heat. By this means he obtained fix ounces of nitrous ether, of confiderable pu- rity. It appears, from the account of the Abbe Rozier, that Mr. Mitouard, as early as the year 1770, ufed a procefs nearly fimi- lar to that of Mr. Bogues. This chemift expofed four ounces of fuming fpirit of nitre with twelve ounces of fpirit of wine to diftillation in a retort, which he placed L 3 lightly l66 ETHER. lightly on the fand, and by this method, which appears the moil fimple of any, he obtained nitrous ether. Laftly, Mr. De la Planche, apothecary at Paris, has invented two methods of preparing nitrous ether very conveniently. The firft confifts in putting nitre into a tubulated (tone-ware retort, to which a large receiver, with an adopter, is fitted ; oil of vitriol is firft poured to the nitre through the tube, and afterwards fpirit of wine. The vitriolic acid difengages the fpirit of nitre, which re-acts on the fpirit of wine, and forms nitrous ether, almoft immediately. As it might be fufpedted that the ether prepared in this way was partly vitriolic, he has fubftituted inftead of this method, another, which is very ingenious. An adopter, and a receiver, which communicates, by a recurved tube, with an empty bottle, are affixed to a tubu- lated glafs retort, containing fix pounds of very dry nitre. The laft veffel, namely the bot- tle, communicates by means of a fyphon, with another bottle, containing three pounds of the pureft fpirit of wine. The whole being well luted, and the retort placed on a bath of afhes, three pounds of very pure oil of vitriol is poured on the nitre through the tube, which is immediately clofed with a ground /topper. The mixture is then heated to ebullition, and kept in that ftate till no more vapours pafs over. In this experiment, the ETHER. 167 the vitriolic acid difengages the acid of nitre, which pafles partly into the receiver, and partly into the fecond bottle. When the operation is ended, the receiver contains fuming fpirit of nitre, the retort vitriolated tartar, and the fecond bottle an etherial liquor. This laft is diftilled in a retort with a receiver, in the ufual method, no more than two-thirds of the liquid being brought over. The product is again diftilled with a fifth part of fuming fpirit of nitre, poured in by a little at a time, through a glafs funnel with a long neck; two-thirds of this liquid being likewife diftilled over. Laftly, the fecond product is rectified by diftillation from fait of tartar > the firft four ounces being kept apart, and three-fourths of the remainder fuffered to come over. The four ounces are very pure nitrous ether ; the three- fourths of the remainder are a nitrous mineral anodyne liquor. The reiidues of the two rectifications are dulcified fpirit of nitre. Nitrous ether obtained by thefe procef- fes, is a yellowifh fluid, as volatile and eva- porable as vitriolic ether, whofe fmell it refembles, though it is .ftronger, and not fo agreeable ; its tafte likewife is hotter, and more pungent than that of vitriolic ether. It contains a fmall portion of fuperabundant acid. A large quantity of air is continually difengaged from it, which caufes the ftoppers L 4 of l68 ETHER. of the bottles containing it to fly out fre- quently. Its flame is brighter, and the fmoke it emits when burned, is denfer than that of the vitriolic ether; it leaves a larger coaly refidue; and laftly, like the vitriolic ether, it takes gold from its folutions, and fufpends a certain quantity. The refidue of nitrous ether is of a lemon yellow colour, its fmell is acid and aromatic, and its tafte is penetrating, and refcmbles that of diftilled vinegar. It affords, by diftillation, according to Baume, a clear liquor of a milder tafte than that of nitrous ether, being an agreeable acid, which red- dens fyrop of violets, unites with water in all proportions, and effervefces with cretaceous vegetable alkali. The retort contains a yellow friable matter, of the appearance of amber, which attracts the humidity of the air, becomes of a pitchy confiftence, and is foluble in water without rendering it mucilaginous. This, which Mr. Baume calls a gummy faponaceous fub- ftance, if the diftillation be continued, affords a few drops of a very clear acidulous fluid, of an oily confiftence, and flightly empyreuma- tic fmell. A fpungy, brilliant, taftelefs, very fixed coal remains. Bucquet affirms, that if the liquor which remains after the formation of nitrous ether be evaporated, it aflumes the confiftence of a mucilage, and at the end of a certain time, affords faline cryftals refembling ETHER. 169 refembling hairy caterpillars, which have been called cryftals of Hiaerne, from the name of the chemift who firit defcribed them. It has fince been difcovered, that this relidue is the acid of fugar, which proves that the combuftible bafe of that acid is contained in fpirit of wine. The muriatic acid does not fenfibly act on fpirit of wine; this acid being only dulci- fied by fimple mixture with the fpirit, as are likewife the two others when mixed with a large proportion of fpirit. Mr. Baume, in his diflertation on ether, aflerts, that he obtained a fmall quantity of marine ether, by caufing fpirit of fait and fpirit of wine to meet in the form of vapour. Ludolf and Pott ufed butter of antimony with the fame inten- tion. Baron Born directs the folution- of flowers of zink in the marine acid, and diftillation of this fait concentrated by eva- poration in clofe veflels, with fpirit of wine. This procefs affords marine ether, with coniiderable facility. But no one has pur- fued this inquiry with fo much diligence and fuccefs as the Marquis de Courtanvaux. According to the procefs of this chemift, a pint of fpirit of wine is to be mixed in a retort with two pounds and a half of the fmoking li- quor of Libavius; a ftrong heat is excited, and a white fuffocating vapour arifes, which dis- appears when the mixture is agitated ; an agree- able fmell is then perceived, and the mixture affumes 170 ETHER aflumes a lemon colour. The retort is to be placed on a hot fand bath, two receivers being luted on, the outer of which is plunged in cold water. A dephlegmated fpirit of wine firft paifes over, and afterwards the ether rifes, which may be perceived by its fmell, and the ftriae it forms in the neck of the retort. As foon as the fmell changes, and becomes ftrong and fuffocating, the receiver muft be changed ; a clear acid liquor then comes over, on the top of which float a few drops of fweet oil. This is fucceeded by a yellow butyraceous matter, or true butter of tin ; and laftly, a brown ponderous liquor, which emits abundance of white vapours. A grey pulverulent matter, or calx of tin, remains in the retort. The etherial product being poured on oil of tartar in a retort, a ftrong effervefcence takes place, and an abundant precipitate is thrown down, which is produced by the tin that came over in the diftillation. A fmall quantity of water is then added, and a fecond diftillation is per- formed by a gentle heat ; the firft half of the product being etherial. All the fluids, which pafs after the muriatic ether, are loaded with tin ; they attract the humidity of the air, and unite with water, without affording any preci- pitate. It was formerly very difficult to deter- mine thecaufeof the ftrong action of themuri- atic acid contained in the fuming liquor on fpi- rit of wine, fince the pure acid does not at all ad; ETHER, I7I act on that inflammable fluid. But, fince the difcovery of Mr. Scheele, it appears to be owing to the dephlogifticated or aerated ftate of the acid ; and that its property of converting fpirit of wine into ether mufr. be attributed to the excefs of the bale of air it contains. This theory was firft explained by me in the year 1 78 1 , and is now confirmed by the experiments of Me firs. Berthollet and Pelletier. M. de la Planche, the apothecary, has pro- pofed to make muriatic ether, by pouring oil of vitriol and fpirit of wine on decrepitated marine fait, in a tubulated retort. The muriatic acid gas difengaged by the vitriolic acid, meets the vapour of fpirit of wine in the receiver, and combines with it. An etherial acid is produced, which may be purified by a fecond diftillation from fixed alkali. In this procefs, the muriatic acid appears to take a portion of the oxyginous principle from the vitriolic acid. Muriatic ether is very tranfparent ; its fmell is nearly the fame as that of vitriolic ether; it likewife burns in the fame manner, and affords a fimilar fmoke. But it differs in two properties ; the one, that when burning it exhales an odour as penetrating as the fulphureous acid ; the other, that its tafte is ftyptic like that of alum. Thefe two phenomena fhew, that this ether is different, and perhaps lefs perfect than the two 172 ARDENT SPIRIT. two foregoing ; and there is no doubt but when its other properties fhall be examined, other differences, equally remarkable, will be obferved. After having thus treated of the action of three mineral acids on fpirit of wine, we fhall refume the hiftory of this fluid. The action of other acids on ardent fpirit has been little examined. It is only known, that it readily unites with the acid of borax, or fedative fait, which communicates a green colour to its flame ; and that it abforbs more than its bulk of cretaceous acid. As to the neutral falts, Macquer has determined, that vitriolic falts are notdiflblved in thismen- ftruum but with difficulty; that the nitrous and the muriatic falts unite with it much more readily ; and that in general it diffolves faline fubftances with more facility in pro- portion as their acid is lefs adherent. Spirit of wine boiled on the vitriols of pot-am and of foda, diffblved no part. Cretaceous vegetable alkali and foda do not unite with it, but moft ammoniacal falts do. Deli- quefcent earthy falts, fuch as the combina- tions of lime and magnefia, either with the nitrous or marine acid, are perfectly diffolved. Some metallic falts are likewife very foluble, fuch as martial vitriol in the ftate of mother water, cupreous nitre, the muriates of iron and of copper, and corrofive fublimate; all the ARDENT SPIRIT. I73 the cupreous falts communicate a beautiful green colour to its flame. Mr. De Morveau has, fince the time of Macquer, given a very accurate table of the degrees of folubility of falts by ardent fpirit. This table is inferted in the Journal de Phyfique. Spirit of wine does not diffolve fulphur either when in mafles, or in powder; but thefe two bodies unite v/hen they meet in the vaporous form, as the Count de Laura- guais has difcovered. His procefs conlifts in putting flowers of fulphur into a glafs cucurbit, upon which flowers he places a fmaller veflel, filled with fpirit of wine. A head and receiver being adapted, and the ap- paratus being heated by a fand bath, both fubftances rifing together, combine and form a fluid, which pafies into the receiver rather in a turbid ftate, and emits a fetid fmell. It contains about one grain of fulphur in the drachm of fpirit of wine. I have difcovered that the fame combination may be obtained by diftilling hepatic waters, fuch as thofe of Enghien, with fpirit of wine. Ardent fpirit has no a&ion either on metallic fubftances, or their calces. It partly diflblves certain bitumens, fuch as amber and ambergris. It does not ad: on thofe which are black and coaly. It has been obferved, that fpirit of wine diftilled from fixed alkalis, a£ts more ftrongly on thefe bitumens, and that a mixture of alkali with thefe 174 ARDENT SPIRIT* thefe renders them more foluble ; doubtlefs, by converting them into a kind of foap. There are few vegetable matters on which fpirit of wine does not act more or lefs. Extracts lofe their colouring part, and when they are of the refino-extractive, or extracto- refinous kind, great part is diffolved. Sac- charine and faponaceous juices alfo unite with this fluid. Margraaf, by means of ardent fpirit, obtained a faccharine effential fait from beet root, fkirwort, parfnips, &c. But the matters with which it combines the moil: readily, are the effential oils, fpiritus rector, camphor, balfams, and refios. The name of fpirituous diftilled waters is given to fpirit of wine impregnated with the fpiritus rector of plants. Thefe fluids are obtained by diftillation from odoriferous plants v/ith fpirit of wine. The fpirit feizes the principle of fmell, and rifes with it, carrying up at the fame time a certain quantity of effential oil, which caufes it to become white by the addition of diftilled water ; but this principle may be feparated by rectification on a water-bath, with a very gentle heat, care being taken to draw off no more than three-fourths of the fpirit, in order to be certain of having only the fpiritus rector. Thefe fpirituous diftilled waters acquire a more agreeable fmell by keeping; the odorous principle appearing to combine more inti- mately with the fpirit. The ARDENT SPIRIT. I75 TheYpiritus rector has fo ftrong an affinity with fpirits of wine, that this fluid takes it from effential oils and water. In fact, when fpirit of wine is diftilled from effential oils, or from water charged with the fmell of a plant, it takes the odorous principle, and leaves the oil or water without fmell. It is obferved, that fpirit of wine diffolves the ponderous and thick effential oils more perfectly than thofe which are fluid and light. Water feparates this compound by precipitating the oil in the form of white opake globules ; but the fpiritus rector remains united to the fpirit of wine. Spirit of wine readily diflblves camphor in the cold, but it diffolves a larger quantity by the affiftance of heat. This folution, when well faturated, as for example, two drachms of camphor to one ounce of fpirit of wine, being diluted with water, added drop by drop, affords a cryftalline vegetation obferved by Mr. Romieu. It confiils of a perpendi- cular Item, into which fibres are inferted, forming an angle of 60 degrees with the perpendicular ftem. This experiment fel- dom fucceeds, and requires many trials to afcertain the quantity of water, the degree of cooling, &c. The names of tinctures, elixirs, balfams, quintefcences, &c. are given to compounds of oily or relinous juices in fpirit of wine, which is fufficiently charged to have a high colour, I76 ARDENT SPIRIT. colour, and to afford an abundant precipitate by water. Like diftilled water, they are diftinguifhed by the denomination of fimple, when they contain but one fubftance in folution ; or compound, when they contain many. Thefe medicines are, in general, prepared by expofing the dry vegetable itfelf, whofe eflential oil or refin is required to be extracted, or the pulverized extract of the plant, to the action of fpirit of wine, which is aflifted either by agitation, or the heat of the fun, or a fand bath. When the refins of a number of plants, or vegetable fub- ftances, are required to be diffolved in the fame fpirit, care mull be taken to digeft that fubftance firft, which is the moft difficultly acted on by the fpirit ; and to add the other fubftances in the order of their folubility. When the menftruum has exhaufted its ac- tion, and is faturated, it is to be ftrained off. A compound tincture is fometimes extem- poraneoufly made, by mixing feveral fimple tinctures. Thus the elixir proprietatis is made, by mixing the tinctures of myrrh, faffron, and aloes. Refins and balfams may be feparated from fpirit of wine by the affufion of water, or by diftillation ; but in either cafe, the fpirit retains the odorous principle. Water is not capable of decompofing tin&ures formed with the extracto-refmous, or refmo-extractive fubftances, fuch as the tincture ARDENT SPIRIT. » ■ I77 tin&ure of rhubarb, faffron, opium, gum ammoniac, &c. ; becaufe thefe fubftances are equally foluble in both menftrua. Spirit of wine and brandy are of the mofl exteniive afe : the latter is drank with the intention of recruiting the animal' forces ; but it is dangerous if exceffively ufed, becaufe it dries the fibres, and produces tremblings, palfies, obftructions, dropfies, and other diforders. Spirit of wine, either pure, or with the addition of camphor, is ufed to ftop the progrefs of gangrenes. Spirituous diftilled waters are adminiftered in medicine, as tonic, cordial, antifpifmodic, ftomachic, 6cc. They are given either diluted in water, or foftened by the addition of fyrup. The drinks called ratafias, or cordials, are made with thefe diftilled waters and fugar. When they are well prepared, and taken in fmall quantities, they may be ufeful ; but in general, they can be of fervice only to few, and may produce bad confequences to moft who take them. The exceflive ufe of this kind of liquors is truly dangerous, for inftead of ftrengthening the ftomach, they in general produce the contrary effect. Thofe which are the leaft pernicious, when occafionally taken with moderation, may be prepared without heat, by infufing the aromatic fubftance in one part of rectified Vol. IV. M fpirit 178 TARTAR. fpirit of wine, with two parts water, and one of fine fugar. Tinctures have nearly the fame virtues as the fpirituousdiftilled waters, but their action is much ftronger ; for which reafon they are ufed in fmall doles in pills, or with wine, or water. The precipitates they form in this laft cafe, are fufpended for a fufficient time in the mixture, and the odorous part remains diffolved in the fpirit of the tincture. Laflly, fpirit of wine united to copal, oil of afpic, or of the greater lavender, or to oil of turpentine, forms varnifhes which are called drying ; becaufe, when applied on any fubftance, the fpirit of wine evaporates, and leaves a tranfparent refinous coating. A mixture of effential oil prevents thefe varnifhes from drying too quickly, and communicates a degree of uncluoiity, which renders them lefs brittle. CHAP. XXIL Concerning Tartar. ARTAR is an effential fait, united to a portion of vegetable fixed alkali and oil. It is depofited on the fides of cafks during the infennble fermentation of wine. It T TARTAR. I79 It is not produced by the fpirituous fermen- tation, as fome chemifts have fuppofed ; for Roueile the younger difcovered it ready formed in unfermented wine, or muft, and in verjuice. It has the form of irregular plates, difpofed in ftrata, often full of brilliant cryftals, and of a vinous acid tafte. It is diftinguifhed into white tartar, and red tartar, the latter differing from the former only in a greater abundance of colouring matter. " Crude tartar expofed to heat in clofe veffels, affords a reddifh acid phlegm, an oil at firft light, and afterwards ponderous, coloured, andempyreumatic j a fmall quantity of vola- tile alkali, and much cretaceous acid, which Hales, Boerhaave, and many other che- mifts fuppofed to be air. A coal remains, which contains a large quantity of creta- ceous vegetable alkali, and is ealily burned. Vegetable alkali, of confiderable purity, is obtained by the combuftion and incineration of tartar. With this intention, pulverized tartar is wrapped up in papers, which are afterwards dipped in water ; thefe are ranged in a fur- nace, between two ftrata of charcoal, which being fet on fire, the tartar burns, and is calcined ; when the fire is burnt out, the papers of tartar are found in their original form ; theie are lixiviated with cold diftilled water, which after filtration is evaporated M 2 to l8o TARTAR. to a pellicle, and fuffercd to cool, in order to feparate the vitriolated tartar, which cryf- tallizes by repofe. The fluid folution be- ing decanted off, is evaporated and cryftal- lized a fecond time ; and this procefs is re- peated as long as any cryftals are afforded : after which it is evaporated to drynefs, and affords vegetable alkali, partly cauftic, and partly combined with cretaceous acid. Tartar is but fparingly foluble in water : one ounce of that fluid, at the temperature of 55 degrees of Fahrenheit, diffolved no more than four grains. As it contains a large quan- tity of oleaginous colouring matter, it is pu- rified by folution and cryftallization, at Ani- ane and CalviiTon, in the neighbourhood of Montpellier. Dr. Fizes has given a full de- fcription of this purification, in a memoir printed among thofe of the Academy in 1725. The tartar is boiled in water, and filtered while hot ; the folution becomes turbid on cooling, and depofits irregular cryftals, which form a parte ; the pafte is boiled in copper veffels, together with water, mixed with an argillaceous earth, brought from Merviel, two leagues from Montpellier. A ,fcum rifes to the top, which is carefully taken off, and is at length fucceeded by a faline pellicle. The fire is then put out ; and the pellicle being broken, falls to the bottom, among the cryf- tak which precipitated from the folution. The earth, which fouls thefe cryftals, is wafhed TARTAR. l8l wafhed off with cold water, and they are then fold, under the name of cream of tar- tar, or cryftals of tartar ; which differ only ID the circumftance, that the cream is formed at the furface, while the cryftals are depofited at the bottom of the liquor. The white clay appears to deprive the tartar of its fuper- abundant oily and extractive matter. Tartar according to M. Defmaretz, is, purified in a fomewhat different manner at Venice. The pulverized fait, being diffolved in boiling water, depoiits its impurities, from which it is carefully feparated, and the liquor affords cryftals by cooling. Thefe cryftals are re-diffolved in water, gradually heated ; and as foon as it boils, beaten whites of eggs, with fifted wood afhes, are thrown, in. This mixture of allies is made fourteen or fifteen times ; the fcum is taken off, and the liquor left to cool. A pellicle of very white faline cryftals is foon formed, which after the water is decanted, are fuffered to dry. This method changes the nature of the cream of tartar, by converting a part into tartarized vegetable alkali. We fhall proceed to examine the chemical properties of cream of tartar, or tartar purified in the neighbourhood of Montpellier. Very pure cream of tartar is. cryftallized, though irregularly; it has an acid tafte, lefs vi- nous than that of crude tartar. On hot coals, it emits much fmoke, of a penetrating empy- M 7 reumatic j82 TARTAR. reumatic fmell, and itfelf becomes black and carbonaceous. If cream of tartar be diftilled in an earthen retort, with a receiver, connected with an inverted veffel of water, by means of a tube, and the fire be gradually raifed, a phlegm, almoft colourlefs, and fcarcely acid, firft comes over ; next a ftronger acid, of a deeper colour; and afterwards an oil, which becomes more and more coloured, confiftent, and empyreumatic ; and laft of all, the concrete volatile alkali, and a large quantity of cretaceous acid. A very abundant coal remains in the retort, which, lixiviated with- out incineration, affords a large quantity of fixed alkali. The diftilled products may be rectified by a gentle heat. In this rectifica- tion, the phlegm partes over nearly colour- lefs, the oil becomes very white and volatile, the volatile alkali partly combines with the acid, and is not obtained feparate and pure, but by diftilling the laft portions of phlegm with the addition of fixed alkali. The ve- getable fixed alkali, contained in the coal, is not produced in the operation, as many che- mifts have thought, but is all contained ori- ginally in the tartar. The re-action of the fixed alkali on the oil produces the volatile alkali; and the quantity of volatile fait may be increafed, by diftilling the oil obtained from the cream of tartar a fecond time, with the coal it leaves in the retort. Cream TARTAR. 183 Cream of tartar is not altered by expofure to air. It diffblves in twenty-eight parts of boil- ing water, and cryftallizes confufedly by cooling, as we have obferved. A certain quantity of earth feparates from the folutioa of this fait, which is doubtlefs that which was ufed in its purification : the folution reddens tincture of turnfole, and has an acid tafte. The action of quartzofe earth, clay, and ponderous earth, or barytes, on cream of tartar, is not known. The chemifts of the academy of Dijon have obferved, that mag- neiia forms, with cream of tartar, a foluble fait, decompofable by fixed alkali, and af- fording, by evaporation in the open air, fmall prifmatic cryftals in radii. This tartar of magnefia boils up, and becomes converted into a light coal, by expofure to the action of fire. M. Poulletier de la Salle obtained from this combination a gelatinous mafs, perfectly refembling mucilage. The action of lime, and of chalk, on cream of tartar, has been well defcribed by feveral chemifts. When chalk is thrown into a fo- lution of cream of tartar, an effervefcence is produced, occafioned by the difengagement of cretaceous acid ; and a very abundant pre- cipitate, conlifting of a combination of the tartareous acid and lime, is formed. The fupernatant liquor contains a neutral fait, M 4 which 184 TARTAR. which exifted, ready formed, in the cream of tartar, and confifts of the acid of tartar, united to vegetable alkali: it is known, as we fh'all prefently fee, by the name of fo- luble tartar. We are indebted to Rouelle the younger for this valuable analyfis of cream of tartar -y which proves, 1 . That this fubftance is compofed of a fuperabun- dant oily acid, and a certain quantity of this acid, united to vegetable fixed alkali, in the ftate of a neutral fait. 2. That the combi- nation of the tartareous acid with lime, forms a neutral fait of very difficult folubility. Mr. Prouft has difcovered, that calcareous tartar, diftilled in a retort, leaves a refidue, which takes fire by expofure to air, like pyropho- rus. Bergman, in his difTertation on the elective affinities, gives a procefs for fepa- rating the the tartareous acid. He directs the precipitate formed by chalk thrown into a folution of cream of tartar, to be warned with diftilled water j this tartarized lime being then put into a phial, eight times its weight of vitriolic acid, confiding of one part of oil of vitriol, and eight water, muft be poured thereon. After digefting for twelve hours, and being frequently ftirred with a fpatula of wood, the clear liquor muft be decanted off from the mixture ; the de- poiition at the bottom muft likewife be wafhed with water, till it no longer com- municates any tafte ; and the water ufed in wafhing TARTAR, 185 wafliing is to be added to the former liquid. This is the tartareous acid. It is evident, in this experiment, that the vitriolic acid decompofes the calcareous tartar, and forms felenite, at the fame time that it diiengages the tartareous acid, which remains diiTolved in the water. The acid thus obtained al- moft always contains a fmall quantity of vi- triolic acid, which may be precipitated by the addition of a fmall quantity of calcareous tartar, the earth falling. down with the vi- triolic acid, in the form of felenite, while the tartareous acid is difengaged. Bergman adds, that the folution of this acid, evapo- rated to the confidence of fyrup, affords cryftals, in plates or fcales ; that thefe cryf- tals become black by heat, and afford, by diftillation, an acidulous phlegm, with a fmall quantity of oil ; leaving a reiidual coal, which is neither acid nor alkaline. Hence it appears, that the tartareous acid contains oil, like all the other acids of vegetables. Cream of tartar unites very well with the different alkalis. If it be added to a 'folu- tion of cretaceous vegetable alkali, a ftrong effervefcence is immediately produced, by the difengagement of the cretaceous acid. The cream of tartar rnuft be added to fatu- ration, and the liquor filtered, after hav- ing boiled for half an hour ; after which, the evaporation being continued till a pellicle is formed, the folution, by flowly cooling, affords l86 TARTAR. affords long quadrangular prifms, terminated by two facets, placed flantwife. This fait is known by the names of vegetable fait, foluble tartar, tartarized tartar, and ought to be called tartar of pot-afh. It has a bitter tafte ; is converted into a coal by a ftrong heat ; and is decompofed by diftillation, af- fording an acid phlegm, oil, and a large quan- tity of cretaceous acid. It flightly attracts the humidity of the air, and is completely diffolved in four parts of water, at the heat of 120 degrees. The mineral acids decom- pofe it, and precipitate cream of tartar ; it is alfo decompofed by mod metallic folu- tions. Cream of tartar, combined with foda, forms fait of Seignette, fo called from the name of an apothecary of Rochelle, who flrfl compofed it. It is prepared, by diffolving twenty ounces of cream of tartar in four pounds of water, and gradually adding very pure cryftallized vegetable alkali tofaturation, which point is known by an effervefcence not being excited by the addition of more alkali. In this combination the cream of tartar is rendered more foluble. The fluid being evaporated, till it has nearly the confidence of fyrup, affords, by cooling, very beauti- ful regular cryftals, often of a confiderable magnitude. They are prifms of fix, eight, or ten unequal faces, truncated at right angles at their extremities. Thefe prifms are moft commonly bifedted length wife j and the 'tartar. 187 the large face, or bafe, on which they reft, is marked by two diagonal lines, interfer- ing each other, and dividing the bafe into four triangles. The fait of Seignette, which ought to be called tartar of foda, was at firft fold as a fecret, but was difcovered, at the fame time, by Boulduc and Geoffroy, in 1731. It has a bitter tafte ; is decompofed by the fire, like the tartar of pot-afh ; efflo- refces in the air, becaufe it contains much water of cryftallization, and is nearly as foluble as tartar of pot-afh, and, like that fait, is decompofed by mineral acids and metallic folutions. The mother water of this fait, contains the portion of tartar of pot-afh, which compofes part of the cream of tartar. The volatile alkali forms, with cream of tartar, an ammoniacal tartareous fait, which crystallizes very well by evaporation and cooling. Bucquet affirms, that its cryftals are rhomboidal pyramids. Macquer obferved fome, in thick prifms, of four, five, or fix fides ; others thickeft in the middle, and terminated by very acute points. The aca- demicians of Dijon obtained them in ob- lique angled parallelopipedons. Ammoni- acal tartar has a cool tafte, and is decom- pofed by heat : in the air it efHorefces : hot water diffolves it more readily than cold ; and \t cryftallizes by cooling. Lime and fixed alkalis 1 88 TARTAR. alkalis difengage the volatile alkali ; mineral acids and metallic folutions decompofe it. Pott and Margraaf treated cream of tartar with the mineral acids, and the latter ob- tained neutral falts, fimilar to thofe afforded by each of thefe acids with vegetable alkali ; whence he concluded, that this alkali exifts, ready formed, in cream of tartar. Rouelle the younger made a number of accurate ex- periments, which afforded the fame refults. A pound of cream of tartar, in very fine powder, was added to a pound of oil of vi- triol ; the mixture became hot, and the mutual adtion of the two fubftances on each other was affifted by the heat of a water- bath, and by frequent ftirring with a glafs inftrument. This heat being continued ten or twelve hours, the mixture became of the thicknefs of cream, at which period two or three ounces of boiling diftilled water were added, which rendered the whole fluid. Two hours after, the mixture was taken from the fire, and three pints of boiling dif- tilled water were added. This folution was coloured, and opake, and contained difen- gaged vitriolic acid, a portion of cream of tartar not decompofed, and vitriol of pot-afh. The excefs of vitriolic acid was then fatu- rated with chalk $ and felenite, with a fmall quantity of cream of tartar, were precipitated. The mixture was then filtered and evaporated, till it became reduced to eighteen or twenty ounces $ TARTAR. 189 ounces ; during which, a fmall quantity of cream of tartar and of felenite, fell down. The fluid was decanted off, evaporated a fecond time, and by ftanding afforded vitriolated tar- tar; more of which was obtained in the like manner by fucceffive evaporations. This fait is always mixed with a fmall quantity of cream of tartar, and burns on a hot iron. But if a due quantity of diftilled water be added, the vitriolated tartar will be taken up, and the cream of tartar will remain un- diiTolved. The foregoing procefs is defcribed by Berniard, who repeated it with fuccefs after Rouelle. The nitrous and muriatic acids, treated in the fame manner with cream of tartar, afford nitre and febrifuge fait ; which incontro- vertibly proves the exiftence of vegetable al- kali in this fubftance. Cream of tartar acquires folubility, by uniting with borax and fedative fait. Ac- cording to the experiments of M. De Laf- fone, one part of the latter fait may render about four parts of cream of tartar foluble. This mixed folution affords a greenifh, very acid gummy fait, by evaporation. Cream of tartar appears capable of uniting with moft metallic fubftances, as Meffrs. Monnet and the chemifts of the academy of Dijon have fhewn. But as thefe combina- tions have been little examined, we fhall only fpeak, in this place, of thofe of anti- mony, I90 TARTAR. mony, mercury, lead, and iron; becaufe they are better known, and are moil of them ufed in medicine. The combination of cream of tartar and antimony, is called ftibiated, or antimoniated tartar, or more commonly emetic tartar. As it is one of the moft important remedies afforded by chemiftry, it is neceffary to examine its properties with the greateft care. Since the time of Adrian de Mynficht, who firft de- fcribed this compofition, in the year 1631, the procefs for making it has been greatly varied. The Pharmacopeia, and the writings of chemifts, all differ, either in the antimo- nial fubftances directed to be employed, as well as in the cream of tartar and water, either with refped: to quantity, or the me- thod of applying them to each other. Berg- man, in his differtation on this medicine,* has given an excellent fedtion on the diffe- rent proceffes heretofore ufed in preparing antimoniated tartar. The crocus metallo- rum, the liver, the glafs, and the flowers of antimony, have been fucceffively prefcribed : fome diredt thefe fubrtances to be boiled with cream of tartar, and a greater or lefs quantity of water, for ten or twelve hours ; others direct the ebullition to be continued no longer than half an hour; others again require the filtrated lixivium to be evaporated * E%s, Vol. I. to TARTAR. I9I to drynefs ; and laftly, there are others who direct it to be cryftallized, and the cryftals only to be ufed in medicine. Hence it hap- pens, that antimoniated tartar is never the fame fubftance, but pofieffes various de- grees of force, fo that its effects cannot be clearly afcertained. And accordingly Geof- froy, who examined many fpecimens of an- timoniated tartar, of different degrees of force, found, by the analyfis, that the weak- eft contained from thirty to ninety grains of regulus, in the French ounce of 576 grains. Thofe of a middle degree of emetic power, 1 08 grains, and the ftrongeft 1 54 grains. Glafs antimony has been chofen in preference to other antimonial fubftances, becaufe it is one of the moft foluble by cream of tartar ; but this glafs may be more or lefs calcined, and the different degrees of calcination muft affect its emetic power. However, if very tranfparent glafs of antimony, previoufly well levigated, be boiled in water, with an equal weight of cream of tartar, till the latter is fa- turated, and this folution be filtered and evaporated by a gentle heat, cryftals of an- timoniated tartar are obtained, by Hand- ing, whole emetic power appears to be fufficiently conftant. The liquor being decanted and evaporated, affords new cryf- tals for feveral fucceflive times. The mother water contains fulphur, tartar of pot-am, and a certain quantity of liver of fulphur. When the mixture of cream of tartar, glafs of I92 TARTAR. of antimony, and water, which has been boiled for the preparation of antimoniated tartar, is paffed through the filtre, a yellow or brown gelatinous fubflance remains be- hind, which Rouelle has examined, and finds to afford, by diftillation, a very inflammable pyrophorus. Macquer propofes to fubftitute the powder of algaroth, inftead of glafs of antimony, in the preparation of emetic tartar ; becaufe this powder is itfelf a violent emetic, and when precipitated from the butter of antimony is always the fame. Bergman has adopted the opinion of Macquer; and fince that time, emetic tartar has been prepared in the labo- ratory of the academy of Dijon according to the method of Bergman and M. De Laffone. This medicine has been ufed with the greateft fuccefs : it operates, in a dofe of three grains, without fatiguing the ftomach or interlines. Antimoniated tartar cryftallizes in very tranfparent trihedral pyramids, decompof- able by heat, which converts them to a coaly fubflance. It efHorefces in the air, and becomes a white farinaceous powder ; it is foluble in fixty parts of cold water, or in a much lefs quantity of hot wa- ter. It cryftallizes by cooling ; and is de- compofed by lime and alkalis. Calcareous earth, and pure water, in, a large dofe, are capable of decompofing it ; whence it fol- lows, that it ought to be adminiftered only in diftilled water. Liver of fulphur, and hepatic TARTAR. I93 hepatic gas, precipitate from it a red pow- der, or kind of golden fulphur, which may ferve as a tefl for the prefence of this fait in all liquors containing it. Iron feizes the acid of tartar, and feparates the calx of anti- mony ; antimoniated tartar ought not, there- fore, to be prepared in verTels of this metal, Mr. Durande, phyficianand profeffor at Dijon, propofes that this medicine be made publick- ly, and by one uniform procefs, eflablifhed by law, as the theriaca is made ; and we are convinced, that the greateft advantages would arife to the pra&ice of phyfick from fuch a regulation being adopted. The tartareous acid may be combined with mercury by two methods. The one mention- ed by Mr. Monnet, confifls in diffolving fix parts of cream of tartar in boiling water, with one part of mercury, precipitated from the nitrous acid by cretaceous vegetable alkali. This liquor, filtered and evaporated, affords cryftals, that are decompofable by pure wa- ter. The fecond method of uniting mer- cury with the tartareous acid, conlifts in pouring a nitrous folution of this metal into a folution of tartar of pot-afh, or tartar of foda : a precipitate of mercurial tartar is af- forded, and the nitre of pot-afh, or foda, re- mains diffolved in the liquor. Cream of tartar has a fenfible action oh the calces of lead. Rouelle the younger has afcertained, that the faturnine tartar, pro- Vol. IV. N duced 194 TARTAR, duced in this operation, does not remain dlffolved, but that the liquor, by evapora- tion, affords pure vegetable alkali, which was ready formed in the cream of tartar. This is one of the proceffes he has made ufe of to prove that fixed alkali exifts in tartar. Copper, and its calces, are readily attacked by the tartareous acid : the refult is a fait, of a beautiful green, capable of cryftallization, but hitherto little examined. Iron is very ftrongly acted on by cream of tartar. A medicine, called chalybeated tar- tar, is prepared, by boiling eleven ounces of levigated iron filings with one pound of white tartar, in twelve pounds of water. When the tartar is diflblved, the liquor is filtered, and depofits cryftals, more of which may be obtained by fubfequent evaporation. To prepare the tartarized tincture of Mars, a pafte is made, with fix ounces of iron fil- ings, one pound of white tartar in powder, and a fufficient quantity of water. This mixture is left at reft for twenty-four hours ; after which twelve pounds of water are add- ed, and the whole boiled for two hours; frefh water being added in proportion as the evaporation goes forward. The liquor is then decanted, filtered, and thickened, by boiling to the coniiftence of fyrup ; after which one ounce of fpirit of wine is added. Rouelle afcertained, that the fixed vegetable alkali exifts at liberty in this tincture, and that by heating TARTAR. I95 heating it with acids, neutral falts, with bafe of this alkali, are obtained. There are likewife two other medical preparations, formed by the combination of the tartareous acid and iron. The one is foluble martial tartar, confifting of one pound of the tarta- rized tincture of Mars, and four ounces of tartar of pot-a(h, evaporated to drynefs. The other is known by the name of martial balls. They are made by mixing, in a glafs veifel, one part of fteel filings, and two parts of white tartar in powder, with a certain quan- tity of brandy ; when the brandy is evapo- rated, the mafs is pulverized, and more brandy added, which is fuffered to evaporate as before. This procefs is repeated till the mafs becomes tenacious, when it is formed into balls. Crude tartar is very ufeful in the art of dy- ing, and it is likewife made ufe of by hat- makers. The different preparations of cream of tartar which we have enumerated, are moftly ufed in medicine ; pure cream of tartar is confidered as cooling and antifeptic. In the dofe of half an ounce, or an ounce, it purges gently, and without exciting naufea. The tartars of pot-afh and of foda are often ufed, in conjunction with other purgative medicines, in the dofe of a few drachms : antimoniated tartar is one of the moft ufeful and effica- cious medicines afforded by chemiftry. Th;. fait is emetic, purgative, diuretic, diapho- N 2 retic I96 TARTAR. retic, or deobftruent, according to the dofes and proceffes ufed in adminiftering it. It often produces all thefe effects at one time. It may alfo beconfidered as a powerful alter- ative, of excellent ufe in removing obftruc- tions of the vifcera, when given in fmall dofes often repeated. It is adminiftered as an emetic, in the dofe of from one to four grains, diffolved in water. It is mixed, in the dofe of a grain, with other purgatives, whofe action it affifts : and laftly, when given in the quantity of half a grain, greatly diluted with water, it acts as an alterative. M. De LafTone has difcovered, that antimo- niated tartar is rendered very foluble in wa- ter by the mixture of fal ammoniac ; and that a mixed fait, fimilar to fal alemrSroth, is produced. It may be concluded, that this new compound is capable of producing confiderable effects on the animal economy. Chalybeated tartar, foluble martial tartar, and the tartarized tincture of Mars, are ufed as tonic and aperient medicines. CHAP. ACID FERMENTATION. I97 CHAP. XXIII. Of the Acid Fermentation, and of Vinegar, M ANY vegetable fubftances, fuch as gums and amylaceous fecula, diffolved in boiling water, are capable of undergoing the acid fermentation ; but this property is more efpecially remarkable in fermented and fpirituous liquors. All thefe fluids, when ex- pofed to heat in contact with air, undergo the. acid fermentation, and afford the liquor called vinegar. The wine of grapes is more efpe- cially ufed in preparing this liquor, though it is poffible to make very good vinegar with cyder, perry, &c* There are three conditions neceffary to the acetous fermentation: 1. A degree of heat from 750 to 900 of Fahrenheit. 2. A fubftance at the fame time vifcous and acid, fuch as muci- lage and tartar. 3. The con tad: of air. The change which wine undergoes, when it be- comes converted into vinegar, muft be attri- buted to an inteftine motion, excited in the fluids by the prefence of a certain quantity of * Vinegar is made in Britain from wort, which is the infufion of malt, made in the fame way as in the procefs of brewing. T. N 3 mucilage I98 ACID FERMENTATION. mucilage, which is not changed, and is capa- ble of paffing through a new fermentation. The prefence of an acid fubftance, fuch as tartar, is neceffary to determine the acid fer- mentation. Laftly, the contadt of air is in- difputably neceffary, and it appears that a certain portion is abforbed during this fer- mentation, as the Abbe Rozier has proved. All wines are capable of forming vine- gar. The bad wines are employed in pre- ference, lor the fake of cheapnefs ; but the experiments of Beccher and Cartheufer, prove, that generous wines, abounding with ardent fpirit, afford in general the beft vine- gar. Boerhaave, in his Elements of Chemiftry, has defcribed a very good procefs for making vinegar. Two large cafks are provided, and a falfe bottom of wicker is fixed, at fome diftance from the bottom, within each, on which vine branches and grape ftalks are fpread : wine is then poured in; fo that one of the veffels is filled, and the other only half full. The fermentation commences in the latter : when it is well eftablifhed, it i3 fill- ed up with wine added from the other tun. By this means, the fermentation is retarded in the full veffel, and accelerated in the other. When it has arrived at a confiderable degree in this laft, it is again filled up, by transferring part of the fluid from the other; the fermentation confequently recommences ia ACID FERMENTATION, I99 in the veflel from which the liquor was lafl taken, and becomes flower in that which is filled up. The alternate rilling and empty- ing of the veflels is continued till the vine- gar is perfectly formed, which ufually hap- pens in twelve or fifteen days. When the effects of this fermentation are attend to, much ebullition and hifling is per- ceived ; the liquor becomes hot and turbid, exhibits a great quantity of filaments and bubbles, agitated in every direction ; a ftrong acid fmell, not at all dangerous, is emitted, and a large quantity of air is abforbed. It is neceffary to impede the fermentation every twelve hours. Thefe phenomena gradu- ally become lefs, the heat decreafes, the motion decays, and the fluid recovers its tranfparency : a fediment is depofited, in reddifh flocks, which adhere to the fides of the veflels. Numerous experiments have fhewn, that the fmaller the quan- tity of wine, and the more perfed: the ac- cefs of air, fo much the more readily does it pafs to the flate of vinegar. The vinegar muft be carefully drawn off, in order to feparate it from its lees, which, without this precau- tion, would quickly caufe it to undergo the putrid fermentation. Vinegar does not de- pofit tartar by flanding, like wine ; this fait is diflblved, and combined with the ardent fpirit and water during the fermentation. It is N 4 even 200 ACETOUS ACID. even probable, that the prefence of this fait contributes to the tafte and other acid pro- perties of vinegar. This fluid has more or lefs of colour, according to that of the wine ufed in its preparation ; but in general, vi- negars, which have the leaft colour, are far from being of as light a colour as the white wines, becaufe they hold in folution the colouring matter of the tartar, which has likewife been developed by the production of the acid. Vinegar, prepared in the method here de- fcribed, is very fluid -y of an acid and fpiri- tuous fmell ; and of a four tafte, of different degrees offtrength: it reddens blue vegetable colours. When expofed to a warm tempe- rature, in imperfectly clofed veffels, it be- comes changed, lofing its fpirituous part, and depofiting a great quantity of mucilagi- nous flocks and filaments, at the fame time that it affumes a putrid fmell and tafte. In order to preferve it, it is neceflary to boil it for a fhort tim£, as Scheele has obferved.* When vinegar is diftilled by a naked fire, in an earthen alembic, or in a glafs retort, on a fand-bath, a phlegm, of a lively and agreeable fmell, but fcarcely acid, firft paffes over -, this is fucceeded by a very white and odorous liquor, called diftilled vinegar. The following products have lefs fmell, and more acidity, as the diftillation advances. If thefe * This difcovery, announced in Scheele's EfTays, p. 315, Englifti tranilation3 did not fucceed with me upon trial. T. pro* ACETOUS ACID. 201 products be taken feparately, diftilled vine- gars, differing from each other in acidity and fmell, may be obtained; but it is ufual, in this procefs, to draw off about two-thirds of the liquor, which conftitutes the pureft vi- negar. The portion which comes over af- terwards is more acid, but it has an empy- reumatic fmell, which may be diffipated by expofure to air ; it is likewife flightly co- loured. This operation {hews, that the acetous acid is lefs volatile than water. The remaining vinegar is thick, of a deep and dirty colour, depofits a certain quantity of tartar, and is considerably acid. If it be evaporated in open veffels, it takes the form of an extraft; and if, when dried, it be dif- tilled in a retort, it affords a reddifh phlegm, acid, an oil at firft light coloured and after- wards heavy, with a fmall quantity of vola- tile alkali. The remaining coal contains much fixed alkali. Vinegar may be concentrated by expoling it to froft. The frozen part con lifts almoft intirely of water; the part which remains fluid, being decanted off, is found to be much more acid : the quantity of vinegar thtfs obtained is fmall. The acid of vinegar, feparated from tartar and the colouring matter, by diftillation, is capable of uniting with a great number of bodies. It does not readily combine with argilla- ceous earth, with which it forms cryftals, in 202 ACETOUS ACID. in fmall needles, whofe properties are little known. It is the acetous fait of clay. This acid unites readily with magnefia, and affords a fait, which is very foluble in water, and does not afford cryftals, but is converted into a vifcous deliquefcent mafs, by evaporation. The acetous fait of mag- nefia is decompoied by fire, by the mineral acids, by ponderous earth, by lime, and by the alkalis. It is very foluble in fpirit of wine. The acid of vinegar combines with lime, and decompofes chalk, whofe acid it difen- gages, in the form of an elaftic fluid. The fait it forms with lime, cryftallizes in very fmall prifms, of a fattin appearance. The calcareous acetous fait is bitter, and four, and effiorefces in the air. Fire decompofes It j its earth is feparated by fixed alkalis; and the mineral acids difengage its acid. The combination of the acid of vinegar with vegetable alkali, is called terra foliata tartari, and ought to be called, the acetous fait of pot-afh. This fait is prepared, by pour- ing very pure diftilled vinegar on white fait of tartar •> the mixture is agitated, and the vi- negar added, till the faturation is perfecl, and the fait well diffolved. It is proper to add an excefs of acid. The liquor, being firft filtered, is evaporated, by a gentle heat, in a veiTel of porcelain, or pure filver j and when it becomes thick, the evaporation is conti- nued ACETOUS ACID. 203 nued to drynefs, on a water-bath. By this means, a very white terra foliata is obtained. If too ftrong a degree of heat be ufed, it becomes grey, or brown, by the burning of a portion of the vinegar. Some chemiiis affirm, that this fait may be obtained in a regular form, by cooling the folution prcvioufly eva- porated to a thick pellicle. The acetous fait of pot-afh has a penetrating, acid, and uri- nous tafte. It is decompofed by the action of fire; and affords, by diftillation in a re- tort, an acid phlegm, empyreumatic oil, volatile alkali, and a large quantity of ftrong- fmelling gas, conlifting of a mixture of cre- taceous and inflammable gas. The refidua! charcoal contains much difengaged fixed al- kali. This fait ftrongly attracts the humi- dity of the air, and is very foluble in water. The vitriolic acid decompofes it. For this purpofe, one part of oil of vitriol is poured on two parts of the acetous fait of pot-am, introduced into a tubulated retort, to which a receiver is adapted : a vaporous fluid, of a penetrating fmell, is immediately difengaged, with a ftrong effervefcence, which condenfes in the receiver, into a liquor called radical vinegar. This vinegar is very concentrated, and ftrongly acid j but it is not pure, as it always contains a certain quantity of ful- phureous acid, diftinguilhable by its fmell. Cream of tartar likewife decompofes the ace- tous fait of pot-afh, becaufe it has a ftronger affinity 204 ACETOUS ACID. affinity than the acetous acid with the alka- line bafe of this fait. Vinegar unites perfectly with foda, and forms a fait, improperly called cryftallizable terra foliata. This does not differ from the acetous fait of pot-afh, but in its cryftalliz- ing in ftriated prifms, refembling thofe of the vitriol of foda, and in its not attracting the humidity of the air. To obtain perfect cryftals, the folution muft be evaporated to a pellicle, and fet in a cool place. The acetous fait of foda is decompofed by fire, and the mineral acids -, and we may obferve, that if the calcareous, or alkaline acetous falts, be diftilled by a ftrong heat, the re- lidues are pyrophori, which take fire when expofed to the air. Mr. Prouft, the dif- coverer of thefe facts, is of opinion, that a pyrophorus is produced in all cafes, where a carbonaceous refidue is divided by an earth or a metallic calx. The acid of vinegar, with the volatile al- kali, forms a liquor, known by the name of fpirit of Mindererus. This fait is fo vola- tile, that it cannot be evaporated without lofing the greateft part of it. Neverthelefs, cryftals, in the form of needles, and of a hot and penetrating tafte, may be obtained by flow evaporation. The ammoniacal acetous fait is decompofed by the action of fire, by lime and fixed alkalis, which difengage the volatile ACETOUS ACID. 205 volatile alkali, and by the mineral acids, feparate the vinegar. Vinegar ads on almoft all metallic fub~ jftances, and its combinations are attended with a variety of important phenomena. It does not appear to diflblve the calx of arfenic ; but this laft fubftance diftilled with an equal part of the acetous fait of pot-afh, afforded Meffrs. Cadet, and the chemifls of the Academy of Dijon, a red fuming liquor of a naufeous fmell, very tenacious, and of a Angular nature. Mr. Cadet had before obferved, that this liquor inflames fat lute. The academicians of Dijon being defirous of examining a yellowifh matter of an oily confidence, collected at the bottom of the veffel, which contained the arfenico-acetous, fuming liquor, decanted a portion of this fuperfluent liquor, and poured the reft on a filter of paper. A few drops had fcarcely parTed, when immediately an offenfive and very thick fume arofe, which formed a column from the veffel to the cieling ; a kind of ebullition was excited on the borders of the matter, and a beautiful rofe-coloured flame iflued forth ; all which lafted a few feconds. A full account of the experiments of thefe learned Academicians, may be feen in the third volume of the Elements of Chemiftry of Dijon. They compared the liquor we have fpoken of to a liquid phof- phorus; we think it is a pyrophorus of the 206 ACETOUS ACID. the fame kind as thofe we (hall prefer* tly mention. The refidue of the diflillation of the acetous fait of pot-afh with calx of arfenic, confills for the moft part of vegetable fixed alkali. Vinegar dhTolves the calx of cobalt, and forms a folution of a pale rofe colour. t It has no aclion on bifmuth, or its calces. It diflblves nickel direclly, according to Mr. Arvidfon ; this folution affords green cryftals, of the form of a fpatula. The acetous acid does not appear to ad: on the regulus of antimony, but it appears to diffolve the glafs of this femi-metal; iince Angelus Sala made an emetic preparation with thefe two fubftances. Zink, and alfo its calces, are readily diifolved by vinegar. Mr. Monnet obtained cryftals from this folution in the form of flat plates. The acetous fait of zink fulmi- nates on hot coals with a blueifh flame. By diflillation it affords an inflammable liquor, a yellowifh oily fluid, which foon becomes of a deep green ; and a white fublimate, which when fet on fire by a candle, burns with a beautiful blue flame -, the refidue is in the ftate of a pyrophorus, not very com- buftible. The acid of vinegar does not diffolve mercury in its metallic ftate ; but this combination may be made by dividing the mercury into very fmall particles, as was done ACETOUS ACID. 207 done by Keyfer. Mercury, in the ftate of calx, readily unites with vinegar. The acid may be boiled either on precipitate per fe, on turbith mineral, or mercury precipitated from its nitrous folution by the vegetable alkali. The fluid becomes white, but recovers its tranfparency when boiling hot; it is then to be filtered, and filver-coloured cryflals fall down, in fcales refembling fedative fait. This has been called mercurial foliated earth, or mercurial acetous fait. It may be immedi- ately prepared by pouring a nitrous folution of mercury into an acetous folution of vege- table alkali ; the nitrous acid unites with the fixed alkali of this laft fait, and forms nitre, which remains diffolved ; while the calx of mercury, combining with the acid of the vinegar, is precipitated in the form of brilliant fcales. The mixture being then filtered, the mercurial acetous fait will re- main on the filter. This fait is decompofed by the action of fire, and its refidue affords a kind of pyrophorus. It is quickly altered by combuftible vapours. Tin is not much altered by vinegar. This acid diffolves only a fmall quantity of that metal, which by folution afforded Mr. Mon- net a yellowifh fubftance refembling gum, and of a fetid fmell. The acid of vinegar acts more ftrongly on lead than on moft other metals, and diffolves it with the utmoft facility. When thin plates of this metal are expofed to the 208 ACETOUS ACID. the vapour of heated vinegar, they become covered with a white powder called cerufe, which is a calx of lead. Cerufe ground with one third part of chalk, forms the white lead ufed as a paint. In order to faturate vinegar with lead, the acid is poured on cerufe in a matrafs ; the mixture is fet to digeft on a fand bath, and after feveral hours is evaporated to a pellicle ; by cooling it affords white cryftals, forming either irre- gular needles, if the fluid has been too much concentrated ; or flat parallelipipedons, ter- minated by two flant fe&ions, when the evaporation has been well made. This is called fait or fugar of Saturn, on account of its fweet tafte, which is at the fame time very ftyptic. A fait of the fame nature is made, by boiling equal parts of litharge and of vinegar, and evaporating it to the con- fiftence of fyrup. This is the extradt of Saturn of Mr. Goulard, which long before his time was known by the name of vinegar of Saturn. Salt of Saturn, or the acetous fait of lead, is decompofed by heat ; it affords an acid, ruddy, and very fetid liquor, different from radical vinegar. The reiidue is a very good pyrophorus. This fait * is decompofed by diftilled water, by lime, by alkalis, and by the mineral acids. The extract of Saturn, diluted with water, and mixed with a fmall quantity of brandy, forms the vegeto-mineral water. Vinegar ACETOUS ACID. 209 Vinegar quickly diffolves iron ; the effer- vefcence which takes place in this folution arifes from the difengagement of inflammable gas afforded by the water, which feems to be decompofed. The liquor has a red or brown colour ; and by evaporation affords only a gelatinous magma, together with fome long brown cryftals. The Martial acetous fait has a ftypric and fweetifh tafte ; is decompofed by fire, which drives off its acid ; attracts the moifture of the air, and is decompofed in diftilled water. When heated till it no longer emits a fmell of vinegar, it leaves a yellowifh calx attracted by the load-ftone. The acetous folution of iron affords a very black ink with nut-galls, and may be fuccefsfully ufed in dying. The phlogifticated alkali precipitates a very bright Pruffian blue. Martial cethiops, the pre- cipitates of iron, the faffrons of Mars, the fparry iron ore, afford folutions with vine- gar of a very fine red colour. Diftilled vinegar diffolves copper with very great facility, and by the affiftance of heat it gradually affumes a green colour. But the acid acts more readily on this metal when already calcined by vinegar, and con- verted into the fubftance called verdigris. Verdigris is prepared in the neighbourhood of Montpellier, by plates of copper in earthen veffels, covered in layers with the hufks of grapes, which have been previoufly fprinkled Vol. IV. O and 210 ACETOUS ACID. and fermented with weak vinegar. The furface of theie plates foon become covered with a green ruft, which is increafed by piling them together, and fprinkling them with weak vinegar. The copper is then fcraped, and the verdigris is packed in facks of leather for fale. M. Monnet, apothecary at Montpellier, has very well defcribed this procefs, in two Memoirs printed among thofe of the Academy of Sciences, for the years 1750, and 1753. Verdigris readily diffolves in vinegar, and the folution, which is of a beautiful green colour, affords by evaporation and cooling, green cryftals, in truncated quadrangular pyramids, called cryftals of Venus. The cryftals prepared for commerce, which are called diftilled verdigris, becaufe diftilled vinegar is ufed in preparing them, have the figure of a pyramid ; its cryftals affume this form, becauie they are depofited on a ftick cleft into four branches, which are kept afunder by a piece of cork. The acetous fait of copper has a ftrong tafte, and is a violent poiibn. It is decom- pofed by the action of fire, efflorefces in the air, and becomes covered with a powder, whole green colour is much paler than that of the fait itfelf. It is completely diflblved in water without decompolition. Lime- water and alkalis precipitate the calx of copper. When ACETOUS ACID. 211 When this fait is pulverized and diftilled in an earthen or glafs retort, a fluid is ob- tained at firft pale and fcarcely acid ; but affords afterwards one fo ftrong, as to refemble the mineral acids. The receiver muft be changed during the operation, in order that the phlegm and the acid may be had feparate ; the latter is called radical vinegar. It has a green colour, arifing from a certain quan- tity of the calx of copper which comes over. When the diftillation ceafes, and the bot- tom of the retort is red hot, the refidue is a brown copper coloured powder, which often communicates a metallic tinge to the fides of the veffel. This refidue is ftrongly pyrophoric, as the Due D'Ayen and Prouft have obferved. Radical vinegar is rectified by diftillation with a gentle heat ; it is then perfectly colourlefs, provided the heat has not been urged too ftrongly, fo as to dry the remaining calx of copper. The reduc- tion of the copper referved in this experi- ment explains the nature of radical vinegar. This acid appears to have the fame relation to common vinegar, as the aerated or oxy- ginated muriatic acid has to the pure muri- atic acid. In this operation the acetous acid unites with the oxyginous principle of the calx of copper, which at the fame time refumes the metallic ftate. The rery dif- ferent effe&s produced by radical vinegar, compared with thofe of the common acetous O 2 acid, 212 ACETOUS ACID. acid, appear therefore to arife from its excels of the oxyginous principle. Radical vinegar, thus rectified, has fo ftrong and penetrating a fmell, that it is impoifible to fupport it for any length of time ; its caufticity is fuch, that it corrodes and burns the fkin, and it is extremely volatile and inflammable. When heated with contact of air, the rapidity with which it burns is the greater, the more highly it is rectified. This experiment has induced chemifts to believe, that vinegar is an acid combined with an ardent fpirit ; it may, perhaps, be confidered as a kind of natural ether. This notion is rendered probable, by the penetrating and agreeable fmell emit- ted by the firft portions of this acid in diftillation. Radical vinegar evaporates in- tirely, when expofed to the air ; it unites to water, with much heat ; with earths, alkalis, and metals, it forms the fame falts as common vinegar ; but its action on com- buftible bodies is in general much more rapid. The Marquis de Courtanvaux has fhewn, that it is only the laft portion of the acetous fluid obtained by diitillation from cryftals of verdigris which is inflam- mable 5 and that it likewife has the property of being congealed by cold. This lait por- tion when rectified, ciyftallized in the re- ceiver in large plates and needles, and did not become fluid, at a leis heat than about 62 degrees ACETOUS ACID. 213 degrees of Fahrenheit. In this property like- wife it refembles the aerated muriatic acid. The acid of vinegar, affifted by heat, diflblves the precipitate of gold made from aqua regia by adding a fixed alkali. This fo- lution, precipitated by volatile alkali, affords fulminating gold, as Bergman has (hewn. Vinegar does not aft on platina or filver, while they are in the metallic ftate, but it dif- folves their calces. This acid combines with many of the immediate principles of vegetables. It dif- folves extracts, mucilages, and effential falts ; unites with the fpiritus reftor, and is con- iidered as the proper folvent of gum refins. It has even after a certain length of time in. the way of diftillation, a confiderable action on fat oils, which it converts into a fapo- naceous ftate. But the combination of vi- negar with vegetable fubftances, has been by no means accurately examined. This acid is ufed to extrad: fame of the vegetable principles, more eipecially that of fmell; and vinegars of different nature, either fimple or compound, are prepared for medical ufe. The vinegars of fquills, colchicum, &c. afford an example of the firft ; the the- riacal vinegar, and the vinegar of the four thieves, are of the fecond kind, Thefe me- dicines are prepared by maceration and di- geftion continued for feveral days. As the ^cid is volatile, it is diftiUed from aromatic O 3 plants, 214 ACETOUS ACID. plants, whofe odorant principle it takes up j the diftilled vinegar of lavender ufed as a perfume is of this kind -, thefe liquors are in general lefs agreeable than fpirituous dif- tilled waters. Radical vinegar decompofes fpirit of wine, and forms ether with the fame facility as the mineral acids, as the Count de Laura- guais has difcovered. For this purpofe, ra-* dical vinegar is poured on an equal quantity of fpirits of wine in a retort. A confiderable degree of heat is excited. The retort is then placed in a fand bath, with two receivers fitted on, the outer being plunged in cold water or pounded ice. The mixture being quickly brought to ebullition, adephlegmat- ed fpirit of wine paries firft, afterwards the ether, and laftly an acid which is ftronger as the diftillation advances : a brown mafs, confiderably refembling a refin remains in the retort. Care muft be taken to change the receiver as foon as the etherial fmell becomes fharp and penetrating, that the acid may be collected apart from the ether. The ether muft be rectified by a gentle heat with alkali. A large proportion is loft in this ope- ration. The formation of the acetous ether is owing to theexcefs of the oxyginous principle in radical vinegar. Mr. Scheele affirms, that he did not fucceed in preparing acetous ether, by adding radical vinegar to fpirit of wine, and that he did not obtain it, but by the addition of a mineral acid, Mr. Pcer- ner ACETOUS ACID. 215 ncr had before made the fame remark con- cerning the difficulty of obtaining acetous ether by the procefs of Mr. de Lauraguais. However, many French chemifts have exe- cuted that procefs ; and I can myfelf affirm, that I have repeated it with fuccefs. M. de la Planche, the apothecary, prepares acetous ether, by pouring oil of vitriol and fpirit of wine on fait of Saturn, introduced into a retort. The theory and practice of this operation, are abfolutely the fame as thofe of the nitrous and muriatic ethers, prepared by a like procefs. The acetous ether has an agreeable fmell like other ethers, but it always partakes of the fmell of vinegar, though it is not acid. It is very volatile and inflammable, burns with a bright flame, and leaves a coaly mark after its combuftion. Vinegar is much ufed as to feafon food. It is likewife of excellent ufe in medicine, as a refrefhing and antifeptic fluid. A fyrup is made with fugar, which is given with great fuccefs in burning or putrid fev:rs, &c. ; this acid, externally applied, is aftrin- gent and bracing. All its combinations are likewife applied to medical ufes. The acetous falts of vegetable and mineral alkali, which are known by the names of terra foliata tartari, and mineral acetous fait, are powerful deobftruent and aperient re- O 4 medies ; 2l6 ACETOUS ACID. medies ; they are adminiftered in the dofc of from half a drachm to a drachm. The fpirit of Mindererus, or folution of ammoniacal acetous fait, taken in the dofe of a few drops in a proper liquid, is aperient, dieuretic, cordial, antifeptic, &c. It often fucceeds in the leucophlegmatia, or fvvelling of the external parts of the body. The Mercurial acetous fait, or Mercurial terra foliata, is an excellent anti-venereal; it is the principal ingredient in Keyfer's pills. The extract of Saturn, vinegar of Saturn, and the vegeto-mineral water are applied externally as deficcatives. Thefe medicines, being ftrongly repellent, ought to be admi- niftered with great caution, efpecially when applied to parts which are ulcerated or with- out fldn. Boerhaave mentions feveral young women attacked with confumptions, in con- fequence of the external ufe of preparations of lead. Cerufe enters into the compofition of drying unguents and plafters, and verdi- gris is a component part of feveral collyria and unguents. Radical vinegar is ufed as a very powerful ftimulant to be refpired by fuch as fall into fainting fits. For the convenient ufe of this remedy, a certain quantity is poured on vi- triolated tartar grofsly powdered, which is kept in a well clofed bottle j this medicine k PUTRID FERMENTATION. 217 is univerfally known by the name of fait of vinegar. Acetous ether has not yet been applied to any ufe; neither is it known whether it has any peculiar virtues, differing from thofe of the other ethers. CHAP. XXIV. Concerning the Putrid Fermentation of Vegetables. ALL the vegetable fubftances, which **** have paiTed the fpirituous and acid fer- mentation, are fufceptible of a third intef- tine commotion, by which they are changed; this is called the putrid fermentation. Stahl, and feveral other chemifts, have thought, that this kind of fermentation is merely a confequence of the two preceding, or rather that thefe three phenomena depend on a fingle procefs, or motion, which tends to deftroy the texture of folid fubftances, and to change the properties of fluids. It is true, in fact, that if certain vegetable fubftances be left to themfelves, they pafs through the three fermentations fucceffively, and without interruption. For example; all faccharine matters, diffolved in a certain quantity of water, 2l8 PUTRID water, and expofed to a degree of heat of about 60 or 80 degrees, afford, firft wine, afterwards vinegar, and at laft the acid cha- racter is deftroyed ; they patrify, lofe all their volatile principles, and become dry, infipid, and earthy. But it mult be ob- ferved, that a great number of vegetable fub- ftances do not pafs through thefe three kinds of fermentation, at leaft as far as fenfe can diftinguifh. Infipid mucilages, and folu- tions of gum in water, become four, with- out exhibiting any appearance of fpirit ; and the glutinous matter appears to pafs imme- diately to putrefa&ion, without previoufljr becoming acid. It therefore appears, that though thefe three fermentations fucceed each other in many of the vegetable prin- ciples, there are neverthelefs many others which are capable of the two laft, without the foregoing, or even of putrefying, with- out exhibiting previous figns of acidity. Thefe laft participate of the nature of animal fubftances, and afford volatile alkali by the adtion of heat, and mephitis by the nitrous acid. It appears to 6e from this character, that the vegeto-animal fubftances putrefy fo readily. The inteftine motion which changes the nature of vegetable matters, and reduces them to their elements, requires the follow- ing conditions. Humidity, or the prefence of water, is one of the mod neceffary ; dry and FERMENTATION. 219 and folid vegetables, fuch as wood, are not at all changed, while they remain in that ftate; but if they be moiftened, and their fibres feparated, the inteftine motion foon commences : water, therefore, appears to be one of the caufes of putrefaction -3 and we fhall fee, in the animal kingdom, . that the decompofition of this liquid appears to pro- duce fermentation. Heat is not lefs necef- fary. Cold, or the temperature of ice, not only oppofes this fpontaneous deftruction, but retards its progrefs, and in fome mea- fure reftores the former flate of fubftances which have began to change. The degree of heat, neceffary to putrefaction, is much lefs than that which maintains the fpirituous and acid fermentation, fince it requires no more than about 45 degrees of temperature ; but a ftronger degree of heat is more favour- able to this procefs, provided it be not fo ftrong as to volatilize all the humidity, and intirely to dry the fubftance which putrefies. Accefs of air is a circumftance which Angular- ly promotes putrefaction, fince vegetable fub- ftances are very well preferved in a vacuum. This prefervation, however, has its limits ; and the contact of air does not appear to be indifpenfable for carrying on putrefaction, like the two conditions before-mentioned. The putrefaction of vegetables has its pecu- liar phenomena. Vegetable fluids, which pu- trefy, become turbid, lofe their colour, and depofit 220 PUTRID depofit different fediments ; bubbles rife fco the furface, and mouldinefs appears at the beginning. Vegetable matters, fimply moif- tened, and foft, exhibit the fame pheno- mena; the commotion is never fo great as in the fpirituous and acetous fermentations. The bulk of the matter which putrefies does not appear to increafe, neither does its tem- perature rife ; but the moft important phe- nomenon is the change of fmell, and the vo- latilization of an acrid penetrating urinous principle, fimilar to the volatile alkali, and which, on examination, is found to be that fubflance. Hence the putrefactive fermenta- tion has been diftinguifhed by the name of the alkaline fermentation, and the volatile alkali has been coniidered as its product. The. penetrating fmell flies off by degrees, and is fucceeded by a naufeous, faint fmell, not ealily defcribed. The decompofition is then at its height; the putrefying vegetable matter is then very foft, or fluid, like a fy- rup -, it experiences a great number of fuc- ceflive modifications in the odorant prin- ciple which exhales. Laftly, it dries, its difagreeable fmell is diflipated by degrees, and nothing remains but a blackiih, and as it were, coaly refidue, known by the name of earth, humus vegetabilis, in which no- thing is found but certain faline and earthy fubftances. Such is the order of the phe- nomena obferved in the fpontaneous decom- pofition FERMENTATION* 221 pofition of vegetables which putrefy : but this decompofition, carried to that point in which bodies are reduced to their faline or earthy fkeleton, requires a very long time; and it may even be added, that it has not yet been properly obferved by any perfon. This reproach which is call on chemifts and philo- fophers for their inattention to animal matters, is much more deferved with regard to vegeta- ble fubftances. No philofopher has yet under- taken to obferve the complete putrefaction of thefe laft, though many have begun todefcribe the phenomena which take place in that of animal matters. We may therefore conclude the hiftory of the fpontaneous and natural analyfis of vegetables, by adding, fimply, i. That the fhort account we have given fhews, that vegetable putrefaction attenuates, volatilizes, and deftroys their humours, and reduces them to the earthy ftate. 2. That nothing is yet certainly known concern- ing the phenomena and limits of this kind of putrefaction, which requires to be proper- ly diftinguiihed from that of animal matters. 3. Laftly, as this fermentation is much more evident, and has been better obferved in the fluids and folids of animal fubftances, the larger detail we mall enter into, refpecting thefe laft, will complete our hiftorical iketch of the known fafts relating to putrefaction. PART ( 222 ) PART IV. ■—— —————— ■ i ■ The ANIMAL KINGDOM, CHAP. I. The General Chara&ers of Animals.* NIMALS are in general diftinguifhed from vegetables, by locomobility, and more perfed: organization. Yet, there are intire claffes of thefe which are fixed to a place ; fuch as the lithophytes, and zoo- phytes, which are produced and die on the fame fpot. And, on the other hand, certain vegetables have as much motion in their leaves and flowers, as certain animals ; for example, fhell-worms. The organization * We do not here prcpofe to exhibit more than a fketch of the methods of naturalifts, to facilitate the progrek of beginners in the ftudy of natural hiflory, as treated by the beft writers : but our plan does not permit us to enter fiilly into general confiderations on the nature of animals, which have been treated in fo elegant and philofophical a manner by the Count De BufTon and Mr. Bonnet. F. even ANIMALS. 223 even appears lefs perfect in polypi than in moft plants. Hence it is very difficult to draw a true line of difcrimination between thefe two kingdoms ; and modern naturalifts have therefore been under the neceffity of confounding them in one fingle arrange- ment, called the organic kingdom. Neverthelefs, when we coniider perfect animals, we find great differences between them and vegetables. Numerous and dif- tinct organs, a more complicated ftructure, and a greater variety of functions, are the characters in which thefe differences confift; but it does not appear the lefs difficult to give a good definition of thefe fubflances. By attending to the moll: general charac- ters, v/e may define animals to be bodies endued with fenfation and motion, neceffary to preferve their life. They are all capable of re-producing their like : fome, by the union of the two fexes, produce fmall living creatures; others lay eggs, which require nothing more than a due temperature, in order to produce young. There are fome which multiply without conjunction of fexes ; and others which are re-produced when cut in pieces, like the roots of plants. The true character, or fpecific diftinction of ani- mals, is not eafily affigned. The mixture of races produces numberlefs varieties ; and tranfportation into different climates occa- fions numerous changes in the form, mag- nitude, 224 CLASSIFICATION OF nitude, colours, &c. of. animals. We cart only, therefore, confider thofe as diftindt fpecies, which have conftantly the fame form, and are perpetuated by the re-production of individuals ; and the alterations produced by the intermixture of fpecies, climate, $o- meftication, &c. conftitute the varieties. The number of animals which cover the furface of our globe being very confiderable, it would be impoffible to diftinguifh them from each other, if nature had not prefented remarkable differences in their external fi- gure, on which distinctions are eafily efta^ blifhed. Naturalifts have at all times been fenfible of the utility of thefe differences, which they have advantageoufly applied in claffing animals into methodical diviiions. Although it is certain, that thefe claffifica- tions do not exift in nature, but that the whole chain of created beings is uninter- rupted, yet it is certain, that thefe methods affift the memory, and are of great ufe in the fludy of natural hiftory. We may there- fore confider thefe methods, as instruments appropriated to our limited powers, by the help of which we may fuccefsfully attend to the riches of nature. Ariftotle eftablifhed only general and fimple diviiions -, but his mafterly confiderations, refpefting the inte- rior and exterior organs of animals, have formed a bale, on which the divifions of the firft naturalifts, iuch as Gefner, Aldrovandus, Jonfton, ANIMALS. 225 Jonfton, Charleton, Ray, &c. are in great part founded. Thefe early naturalifts have been fucceeded by a great number of others, who have rendered the methods more per- fect, and have added to the knowledge we poifefs ; but among thefe laft, thofe whofe works more particularly require to be known, and from whom we mall borrow, are Meffrs. Klein, Artedi, Linnaeus, Briffon, Dauben- ton, Geoffroy. After man, whofe organization and intel- ligence place him at the head of animated bodies in a feparate clafs, all ether animals may be divided into eight claffes ; namely, quadrupeds, cetacea, birds, viviparous quad- rupeds, ferpents, fillies, infects and worms, and polypi. Thefe claffes might be more multiplied, but the difficulties would in- creafe in the fame proportion, and defeat the purpofe of artificial claffification, whofe fole merit confifts in limplicity and perfpicuity. Mr. Daubenton, who has paid great atten- tion to the claffification of animals, has ar- ranged them in the fame manner, and has confidered the ftructure of the principal con- ftituent parts of each, to (hew that the claffes are gradually degraded, from quad- rupeds, which neareft refemble man, to worms, which are the mofl remote. See Table I. Vol. IV. P CHAP. 226 QUADRUPEDS CHAP. II. Concerning Quadrupeds and Cetaceous Animals. Zoology. QUADRUPEDS are animals having ^^^four feet, whofe body is moft com- monly covered with hair. They refpire by lungs fimilar to thofe of man; and like him they have a heart, confifting of two ventri- cles : they are viviparous. Thefe animals referable man the neareft in their flru&ure ; there are even fome, as for example, the ape and a few others, which Linnaeus has thought proper to include in the fame order as man. This naturalift gives the name of mammalia to this clafs, in which he comprehends ce- taceous fiih, becaufe they have teats, and give milk to their young. Though this clafs of animals appears to refemble man in fome refped:s, yet they differ greatly from him in feveral important particulars. Such are the horizontal fituation of their bodies, the form of their extremities, the thicknefs and hard- nefs of their fkin, which is hairy, or covered with a hard and as it were corneous fub- ftance, QUADRUPEDS. 12J ftance, the prolongation of the vertebras of the back into a tail, the anterior part of the cranium flat and horizontal, the ears large and long, the bones of the nofe and upper jaw very long, and placed obliquely. When we compare this ilru&ure to that of the human fpecies, whofe body is perpendicular, the bone called radius moveable, the fingers perfectly feparate, the thumbs oppofed to the four other fingers, and the fkin fmooth and thin, we mail be fenlible how much this conformation exalts its fenfibility, and renders it fuperior to the mod perfedt of other animals. The anatomy of its internal parts, and the hiftory of its functions, add iiill more force to thofe important conclu- iions. The ancient naturalifts, at whofe head Ariftotle and Pliny may be placed, havS diftinguimed quadrupeds only by the place of their habitation. For which reafon, and the want of accurate defcriptions, it is often impofiible to afcertain the animals they fpeak of. Later naturalifts, perceiving the difadvantages of this method, adopted an- other, which is very different; they have availed themfelves of the moft obvious dif- ferences on the external parts of animals, to eflablifli charadters readily known, by the afiiftance of which they may with certainty be diftinguiflied from each other. We fhall in this place explain three artificial methods Pa of 228 QUADRUPEDS. of claffing quadrupeds; namely, thofe of Linnaeus, Vogel, and BrifTon. The Method of Linnaeus. Linnsus has divided animals with teats, or the mammalia, in feven orders. The firft, comprehending thofe which he calls primates, has for its characters incifive teeth in both jaws ; conftantly four in number in the upper jaw ; two teats on the breads, and the arms feparated by claviculae : this order contains four genera -, man, homo ; the ape, jimia-y the lemur, or profimia; and the bat, vefpertillio. It cannot but be admitted that this method is very remote from na- ture, fince it arranges in the fame order, creatures fo diffimilar as man and the bat. Animals of the fecond order are diftin- guifhed by the name of bruta : their cha- racters are the want of incifive teeth, their feet armed with ftrong hoofs, and their pace flow. This order includes fix genera, which •are the elephant, elephas ; the fea-cow, /r/- checus ; the (loth, bradypus •> the ant-eater, myrmecophaga ; the mam's ; the tato w, da/ypus. The two firft genera are very re- mote from the four others. In the third order, the Swedifh naturalift diftinguiihes favage beafts by the name of ferae. In this he comprehends all animals with teats, whofe incifive teeth are conical, and QUADRUPEDS. 229 and ufually fix in number in each jaw, whofe canine teeth are very long grinders, not flatted, feet armed with fharp nails, and which tear their prey, and live by deftroy- ing other creatures. There are ten genera of this order ; the feal, phoca ; the dog, cam's; the cat, fe/is ; the ferret, viverra; the weazel, mujlela; the bear, urjhs; the opofium, didelphis ; the mole, ta/pa ; the fhrew-moufe, for ex ; and the hedge -hog, erinaceus. The fourth order, intitled glires, or rats, is diftinguifhed by the following characters : the animals which compofe it have two in- cifive teeth in each jaw, and no canine teeth; their feet are armed with claws proper for leaping ; they live on barks, roots, &c. This order comprehends fix genera ; namely, the porcupine, hijirix ; the hare, lepus ; the caftor, cajior ; the rat, mus ; the fquirrel, fciurus -, and the American bat, to which Linnasus has given the name of nodtilio. In the fifth order, he includes, under the name of pecora, fuch quadrupeds as have incifive teeth in the lower jaw, and none in the upper ; whofe feet are cloven, and which ruminate. The camel, camelus -> the muik animal, mofchus-y the flag, cervus; the goat, capra ; the fheep, ovis ; the ox, bos ; are the fix genera which compofe this order. The fixth order includes, under the deno- mination of belluae, fuch quadrupeds as have the incifive teeth obtufe, and their feet P 3 hoofed. 23O QUADRUPEDS. hoofed. The four genera of this order, namely, the horfe, equus; the hippopotamus, hippopotamus ; the hog, Jus ; and the rhino- ceros, rhinoceros, are very well diftinguifhed from each other by the number of then- teeth, and the form of their feet. Laftly, in the feventh order, which comprehends the cetaceous animals, is diftinguifhed from all others by the form of the feet, which refemble fins : but as we think proper, with many modern naturalifts, to make a peculiar clafs of cetaceous animals, we ihall fpeak of them after quadrupeds. The method of Linnaeus appears to be de- fective in many refpects ; not only in its ar- ranging together animals fo diffimilar as man and the bat, &c. and feparating animals fo fimilar as the rat and the moufe, &c. but likewife becaufe the divifions are not fuffi- ciently numerous, and do not readily enable us to diftinguifh each quadruped; which laft requifite is indilpenfably neceffary, arid is in fad: the only advantage a method is re~ quired to poffefs. The Method of Klein. Klein divides quadrupeds into two prin- cipal orders : in the firft, he arranges thofe whofe feet are ungulated, pedes ungulati Jive cheliferi ; in the fecond, thofe whofe feet are digitated, pedes digit at i. The QJJADRUPEDS. 23! The firft order is divided into five fami- lies, whole characters are founded on the diviiion of their ungulated feet in feveral pieces. The firft family, called monQchela9 comprehends the genus of the horfe : the fecond, whofe individuals are diftinguifh- ed by the name dicbela, includes all thofe whofe feet are cloven into two parts, bijulci. Some have horns, as the bull, the ram,, the goat, the flag, &c. others are not horn- ed, as the hog, the boar, the babyroufTa. The trichela, or animals, whofe ungulated feet are divided into three parts, compofe the third family, of which the rhinoceros is the only variety. The fourth family, whofe character confifts in the feet being di- vided into four pieces, tetrachela> contains only the hippopotamus. The fifth, which is diftinguifhed by the feet being divided into five parts, pentachela, includes only the elephant. The fecond order of quadrupeds, whofe feet are digitated, is likewife divided into five families ; the firft comprehending animals with two digits, didadlyla, confifts of the camel and the filenus, or floth of Ceylon. The fecond family, or animals of three di- gits on their feet, trida&yla, includes the floth and the ant-eater. The third, or te- tradaBila, or animals of four digits, contains tatous, or armadillos, and Guinea pigs, which feem to be a fpecies of rabbits. The fourth P 4 family, 232 QUADRUPEDS. family, characterized by five digits on the feet, pentadatlila, is the moft numerous of all; it contains the rabbit, the fquirrel, the dormoufe, the rat and the moufe, the opof- fum, the mole, the bat, the weazel, the porcupine, the dog, the wolf, the fox, the coati, the cat, the tyger, the lion, the bear, the ape : the number of fpecies compre- hended under thefe genera is very confide- rable. It muft be obferved, that in all thefe characters, taken from the form of the feet, Klein confiders only the fore* feet in his diftindtion of families. Laftly, the fifth family confifts of animals whofe feet are irregular, anomalopedia ; fuch are the otter, the caftor, the fea-cow, and the feal. The fame objection may be made to the fyftem of Klein, as to that of Linnaeus, Though his firft divifions are fufficiently dis- tinctive of the families, the genera are not fo eafily afcertained according to his method, more efpecially thofe of the fourth family. The Method of M. Briffon. M. Briflbn has avoided moft of thefe in- conveniences, by combining together all the characters of the naturalifts who have pre- ceded him. He has availed himfelf of the number of teeth, or their abfence, the form of the extremities, that of the tail, the na- ture CETACEOUS ANIMALS. 233 ture of the appendices, fuch as the horns, the fcales, the prickly fpines or quills. His com- bined method is doubtlefs the moft complete, and beft adapted to diftinguifh any quadru- ped, and refer it to its proper genus. We here prefent his divilions in the form of a table; it exhibits the characters of thefe animals to their refpective genera, and has the advan- tage of being very fimple, and eafily under- ftood. See Table II. Concerning Cetaceous Animals. Cetaceous animals are of a large fize, in- habit the ocean, and by the ftructure of their lungs and blood-velfels, are capable of liv- ing'in water, as we fhall more fully explain in the hiftory of refpiration. They referable quadrupeds in the ftructure of their .breafts, and in general of all their internal organs, as well as in their bringing forth living young. But they differ from them in the form of their extremities, which terminate in fins, and in two large apertures, at the upper part of their heads, through which they can: up the water to various heights. Naturalifts call thefe pafTages fpiracula. The number of genera of thefe animals is much lefs conliderable than that of quad- rupeds. M. BrifTon has diftinguifhed them, 1. Into fuch as have no teeth, as the whale, balcena* 2"34 BIRDS. balcena. 2. Into fuch as have teeth only in the upper jaw, as the narwal, or unicorn fifh, monodon, vel monoceros. 3. Such as have teeth only in the lower jaw, as the phyfeter. 4, and laftly, Such as have teeth in both jaws, as the dolphin, delphinus. CHAP. HI. Concerning Birds. Ornithology. T>IRDS are biped animals, which move ■*-* through the air by means of wings, are covered with feathers, and have a beak of a horny fubftance. A great number of inte- refting fads are obfervable with regard to thefe animals, relative to the various form of their beak, the ftrufture of their feathers, the motions they perform, and their man- ners or habits. The moll important of thefe will be exhibited in the abridgment of phy- fiology, which we fhall give in the fol- lowing pages ; but at prefent we fhall only attend to the external characters which na- turalifts have taken to diflinguifh birds, and clafs them methodically. The earlier writers on this part of natural hiftory have efta- blifhed BIRDS. 235 blifhed no other differences between birds than fuch as relate to the places they inha- bit. Hence they have diftinguifhed them into birds inhabiting woods, plains, feas, rivers, lakes, &c. Others have diftinguiihed them from their food, into birds of prey, granivorous birds, &c. &c. But the methodical writers have diflin- guilhed birds in another way. Linnaeus has divided them after the form of their beak into fix orders, like the quadrupeds with which he has compared them. But thefe divifions do not appear fufficiently exteniive, efpecially when we confider that the number of fpecies in birds is much more confidera- ble than in quadrupeds, fince M. de Buf- fon reckons the quadrupeds at two hundred, and the birds at fifteen hundred, or two thoufand. We fhall therefore only mention in this place the methods of Klein and of Briffon. Klein divides birds into eight families, after the form of their feet; the firft under the name of didaffiles, comprehends fuch as have two digits on their feet ; the oftrich is the only fpecies in this divifion. The fe- cond contains the tridaffyles, fuch as the cafuary, the buflard, the lapwing, and the plover. The third contains the tetrada&yles, which have two digits behind and two be- fore ; fuch as the parokeet, the wood-pecker, the cuckcow, and the king-fiiher. The fourth 236 BIRDS. fourth contains the tetrada5iylesy three of whofe digits are before, and one behind. This family is the moft numerous of any, as it comprehends the birds which prey by day and by night, fuch as the raven, the magpye, the ftarling, the thrufh, the black- bird, the lark, the red-breaft, the fwallow, the titmoufe, the woodcock, &c. The fifth family contains the tetraftyks, whofe three anterior digits are united by a membrane, and the pofterior at liberty. Thefe birds are called palmipedes ; the goofe, the duck, the fea-maw, and the diver, com- pofe this family. The fixth includes the tetradaftyles, whofe four digits are united by a membrane. Thefe in latin are called planet. The pelican, the cormorant, the booby, and the anhinga , are arranged by Klein in this family. The feventh is com- pofed of fuch as have only three digits, and thefe united by a membrane ; they are called the tridaByles palmipedes. The guil- lemot, the penguin, and the albatros, belong to this family. Laftly, the eighth clafs in- cludes the tetradaffyles, whofe digits have membranes fringed, or as it were torn ; thefe are alfo called da&ylobes. Coots, and fome of the fpecies of divers, compofe this laft family. The method of Klein, though more comprehenfive than that of Linnaeus, is not- withstanding attended with many difficulties in afcertaining the genera, efpecially that of OVIPAROUS QUADRUPEDS. 237 of the fourth family ; for which reafon we think the method of M. Briilon is to be pre- ferred. It muft be confeffed, however, that this laft, in which the author has ufed all the characters together, as he has done with re- fpect to the quadrupeds, appears very com- plicated at firft fight ; but when it is re- duced into a table, as we have done, all its divifions may be readily diftinguifhed ; and any bird may be eafily known by attending to the characters according to their arrange- ment. See table the third at the end of this volume. CHAP. IV. Concerning Oviparous Quadrupeds, and < Serpents. T INN^EUS claffed together, in his fyf- ■*-' tern, under the denomination of am- phibia, the oviparous quadrupeds, ferpents, and cartilaginous fifhes : but JVL Dauben- ton obferves, that the word amphibious cannot be applied to any peculiar ciafs of animals ; becaufe, if the expreffion be ap- plied to animals who live as long as they pleafe either in the air or in the water, there are none which poffefs that advantage ; and if 238 OVIPAROUS QUADRUPEDS. if it be applied to terreftrial animals, which are able to remain a certain time in the wa- ter, or to aquatic animals, which are capa- ble of living a certain time in the air, all animals would be amphibious. He there- fore makes two orders of oviparous quadru- peds and ferpents, and arranges the amphi- bia nantes of Linnaeus among the fifties. The oviparous quadrupeds form the fourth order of animals in the divifion of M. Dau- benton. Their organization is confiderably perfect, fince like the quadrupeds, cetaceous animals, and birds, which precede them, they have a head, noftrils, and internal ears. But they differ in the following characters : 1. They have but one ventricle m the heart. 2. Their blood is almoft cold. 3. They infpire and expire the air at long inter- vals. 4. They are oviparous, and confe- quently without breads ; this laft character is common to them with the. four orders of animals which follow them. Laftly, the exiflence of four feet without hair, is pecu- liar to this order. M. Daubenton remarks, that the feveral genera of this order of animals differ too much from each other, to admit of any ge- neral defcription applicable to the whole. He therefore applies the general characters in the hiftory of each genus ; as for example, at the words tortoife, lizard, toad, frog, &c. in the fecond volume of the Natural Hiftory SERPENTS. 239 Hiftory of Animals, which compotes part of the Encyclopedic Methodique. As the methodical difpofition, and the cha- racters of the orders of oviparous quadru- peds, as laid down by this celebrated natu- ralift, are the moft accurate and complete of any which have yet come under my obfer- vation, I have united all the divifions of M. Daubenton from the claffes to the fpecies ; becaufe thefe laft are no more than a hundred in number. See the fourth table. Serpents form the fifth order of animals in the divifion of M. Daubenton. The fcales with which they are covered, and the abfence of feet and fins characterize them very well. They have a head, noftrils, internal ears, a lingle ventricle in the heart, the blood almoft cold, their refpiration is made at long intervals, and they lay eggs like the oviparous quadrupeds. Serpents have nei- ther neck nor moulders, and the fcales which cover them are of three kinds. They are either rhomboidal, and cover each other in the manner of tiles, which Linnaeus calls fquammae ; or they are of a long fquare form, touching without covering each other; Lin- naeus calls thefe fcuta : they are only obferv^ able on ferpents j when they are very lmall and of the fame form they are called fcut- tella ; or laftly, they confift of rings encirc- ling the bodies of ferpents, as is feen in the amphyfbena. , Serpents, 24° SERPENTS. Serpents, though without feet, fometimes move with confiderable fwiftnefs, by leaning firft on their anterior part, railing up the middle, and bringing forward the pofterior part of their body j by which means they raife themfelves on their tail, and fpring to fome diftance, in order to feize their prey. They caft their fkin once or twice in the year. Some ferpents are venomous ; out of 131 fpecies noted by Linnseus, 23 are dan- gerous, according to that naturalift. All thefe animals, whofe bite is venomous, have on each fide of the upper jaw, a tooth much larger than the others, together with a refer- voir filled with a peculiar liquor, which paffes into the wound through a perforation in the tooth. It is eftablifhed, by the moft authentic teftimony, that fome ferpents are of a pro- digious fize. Mr. Adamfon, from very exacT: data, fixes the magnitude of the largeft fer- pents at 40 or 50 feet in length, and a foot, or a foot and a half in thicknefs. M. Lau- renti has paid greater attention than any other naturalift to the claffification of fer- pents. He diftributes them into feventeen genera ; but the difficulty of obferving the diftin&ive characters, has prevented M. Dau- benton from adopting his method; this laft naturalift has therefore followed Linnaeus in the fifth table. I have inferted the divifions and characters of ferpents from the genera to 127 FISHES. 241 127 fpecies, noted by M. Daubenton. Sec table the fifth. CHAP. V. Of Fifhes. Ichthyology. FISHES are animals very different from the foregoing : their interior organs are of a peculiar ftrudture, as we fliall obferve in our abridgment of phyfiology. They are diftinguifhed from other animals by their having no feet, but fins, by which they move in the water, and by their refpiring water inftead of air. It is much more diffi- cult to make obfervations on fifhes than on other animals, and for that reafon their na- tural hiftory is in a much lefs advanced ftate. In order to underftand the methodical di- vifion which we propofe after Artedi, Lin- naeus, and Gouan, it will be necefTary to take a curfory view of the anatomy of their external parts. The bodies of fifties may be divided into three parts ; namely, the head, the trunk, and the fins. The head of thefe animals is differently formed. It is either flattened horizontally, or laterally, or elfe round; naked, or co- Vol. IV. Q_ vered 242 FISHES. vered with fcales ; fmooth, or covered with afperites, tubercules, & c. Their mouths are obferved to have lips either of fie 111 or of bone, with appendages, or foft and very moveable barbulaa ; the teeth fixed either to the jaws, the palate, the tongue, or the throat ; the eyes two in number, motionlefs, and without eyelids ; the perforations of the noftrils double on each fide the opening of the gills or branchiae -, the opercula, or round triangular or fquare bones defigned to clofe the aperture of the branchiae ; the branchial membrane placed beneath the opercula, fuf- tained by feveral bones in the form of an arch, whole number varies from two to ten. This membrane is folded up beneath the opercula, and muft be well examined with refpect to its ftructure and varieties, becauie the characters of the genera are moil com- monly taken from the number or form of its radii. The trunk is of various forms as well as the head j it is either round, globular, long, fiat, or angular. The obferver mull take notice of the lateral line, which feems to divide each fide of the body into two parts ; the thorax placed beneath the gills at the commencement of the trunk, and contain- ing the heart and the branchiae ; the belly, whole ribs form the principal fupports of the fins continued from the head to the tail, and which contains the ftomach, the inteftines, FISHES, 243 inteftines, the liver, the air bladder, the parts of generation ; the opening of the anus, which is common to the inteftines, the bladder, and the generative parts ; laftly, the tail, which terminates the trunk, and is of various forms and magnitudes. The fins, pinnce natatorice, are formed of membranes fupported on fmall radii, fome of which are hard, bony, and: terminate in a fharp point, which characterizes the fifties called acanthopterygiani, fo denominated by Artedi ; others are flexible, foft, obtufe, and as it were cartilaginous, which charac- terizes the fifhes called malacopterygianu Five forts of fins are diftinguifhed with re- flect to their fituation ; the dorfal, the pec- toral, the abdominal, together with thofe of the anus, and of the tail. The dorfal fin is impair j it maintains the fifh in equilibrium, and varies in fituation, number, figure, proportion, &c. The pectoral fins are fituated at the aper- ture of the gills ; they are two in number, and perform the office of arms, and fometimes of wings. They differ as to the place of their infertion, extent, figure, &c. The abdominal fins are of the greateft importance to be known, becaufe their fitua- tion has been affumed by the celebrated Lin- naeus, as a diftinctive character in the clafiifica- tion of fifhes. Thefefins are placed at the infe- rior part of the body, under the belly, before Q^2 the 244 FISHES. the anus, always lower and nearer to each other than the perioral fins. They are fome- times wanting; and as Linnasus has com- pared them to feet, he calls thofe fifhes which are without them apodes ; but they exift in the greateft number of fifhes. Their infertion varies ; when they are placed for- ward or beneath the aperture of the gills, and the pedtoral fins, they are called jugu- lar ; and the fame name is likewife applied to the fifhes in which it occupies this place. If they be attached to the thorax behind the opening of the gills, they are then called thoracic ; and the fifhes which poflefs this ftrudture are diftinguifhed by the fame name in the method of Linnaeus. Laftly, when they are placed beneath the belly, nearer the anus than the pedtoral fins, they are denoted by the name of abdominal, which term is likewife applied to the fifhes diftinguifhed by this ftrudture. The fin of the anus is impair. It occu- pies either wholly, or in part, the region fituated between the anus and the tail ; it differs in form, extent, and number, though it has not been obferved double, excepting in the gold fifh of China. The tail fin is placed vertically at the extremity of the body, and terminates the tail. It is the rudder of the fifh, or inftru- ment by the various motions of which it changes its direction at pleafure. It like- wife FISHES. 245 wife exhibits many varieties in its form, adherence, connection, extent, &c. After theie details refpecting the external anatomy of fifties, we (hall proceed to men- tion the methodical divifions of naturalifts. Before the time of Artedi, no naturalift had attempted to arrange fifties in a methodical manner; though feveral methods were be- fore ufed for the clarification of other ani- mals. This philofopher propofed a fyftem of Ichthyology, founded on the nature of the bones of the fins, whether hard or foft, pointed or obtufe, and on the form of the gills. He afterwards attempted to multi- ply the divifions by attending to the other parts ; but a premature death terminated his labours. Linnaeus attempted to eftablifh an Ichthyologic method, from the various fitu- ations of the belly fins ; and Mr. Gouan, a celebrated profefibr at Montpelier, has very fkilfully combined the two fyftems of Ar- tedi and Linnasus. This naturalift firft di- vides fifties into fuch as have their gills com- plete ; that is to fay, confiding of an aper- ture and a complete branchial membrane, and thofe which have their gills imperfect ; that is to fay, wanting either the opercula, or the branchial membrane, or both. The firft are afterwards diftinguifhed from each other by the form of their fins. Thefe parts are in fact compofed either of hard and ftiarp bones, or foft, and as it were cartilaginous 0^3 radii, 246 INSECTS. radii. Thefe differences constitute three claf- fes of fifties, namely, 1. The acanthoptery- giani. 2. The malacopterygiani. 3. The branchioftegi. In each of thefe claffes of fifhes, the belly fins are either wanting, or placed at the neck, thorax, or belly. Mr. Gouan has divided each clafs into four or- ders ; that is to fay, apodes, jugular, tho- racic, and abdominal. The diftinttive characters of the genera, which immediately follow thefe divifions, are founded on the form of the head, of the mouth, of the branchial membrane, and more particularly on the number of radii which fupport this membrane. See Table VI. CHAP. VI. Concerning Infects. Entomology. TNSECTS are animals which are known ■*■ by the form of their body, which is di- vided as it were into rings, and by two moveable horns which they have on their head, and are diftinguifhed by the name of antennae. Infects compofe one of the moft numerous claffes of animals, doubt- lefs, on account of their minutenefs ; for it INSECTS. 247 it has been obferved, the fmaller thefe creatures are, the more numerous is their production. The hiftory of thefe animals is highly agreeable and amufing, and per- haps not the lead in point of utility ; fince difcoveries refpefting their properties may pro^ exceeding ufeful in the arts, and in medicine. The claries of infefts exhibit refemblances with almolt every other animal, with re- fpeft to their manners, form, habitations, &c. Some walk like quadrupeds ; others fly like birds ; others again fwim, and live in the water like fi flies ; and laftly, there are others which leap, or crawl along, like certain reptiles. This analogy may even be carried much farther, by a full examination of the ftrufture of their extremities, their mouth, their internal organs, &c. In lefts externally confidered, are com- pofed of three parts ; namely, the head, the thorax, and the abdomen. The head differs in its form, fize, and pofi- tion. It is fometimes very large, and fome- times very fmall,% with refpeft to the bulk of the infeft. It is either round, fquare, or long; fmooth, rough, tuberculated, or- tufted with hair. We may obferve the an- tennae placed near the eyes, confifling. of different articulated and moveable pieces, refembling a thread terminated either by Q^4 a point 24^ INSECTS. a point or a knob. The form of thcfe organs muft be carefully diftinguifhed, becaufe this character is almoft always ufed to diftinguifh the genera. 2. The eyes -y which are of two forts, either in facets, or refembling net-work, fmooth and fmall. Thefe organs are very large in fomc infers, and in others very fmall. Their number is various ; there are infedls which have only one eye, as the monoculus ; others have two, five, or even eight, as for exam- ple the fpider, &c 3. The mouth; which is formed either of ftrong and corneous jaws, moveable laterally, or confifts of a trunk of various lengths dilated, fpiral, &c. ; or a Am- ple, cleft, &c. This part is frequently or- namented with fmall moveable appendices, called antennulae, to the number of two or four. The thorax is the ftomach of infedls. It is placed between the head and the belly, and is either round, triangular, cylindric, thick, flender, &c. It may be confidered as compofed of fix faces, like a cube, which form it fometimes has. The face, or ante- rior extremity, is hollowed to receive the head. This articulation is fometimes made only by a part as fmall as a thread, as in flies. The pofterior extremity is ufually rounded and articulated with the firft ring of the abdo- men, and is fometimes joined with this part only by a thread. The fuperior furface is ei- ther INSECTS. 249 ther flat and fmooth, rounded, prominent, with appendices, or tubercles, or terminated by a kind of border, turned up, which confti- tutes the thorax marginatus. The wings arc attached at the pofterior part of this furface. Moil infects are provided with thefe organs ; but as they differ Angularly from each other, and the principal diviiions of claffes adopted by methodical writers are founded on thefe differences, it will be neceffary to attend more particularly to them. The wings are either two or four in num- ber ; among thofe which have two tranfpa- rent wings, as the fly, the gnat, &c. thefe wings always have beneath the place of their infertion a flender thread terminated by a round button, called balancers, haheres, which is covered by a concave membra- nous fubftance. In a great number of in- fects thefe two wings are very ftrong, and folded up under hard, horny, moveable co- verings, called fheaths, or elytra. Thefe differ in form ; fome cover the whole ab- domen j others are, as it were, cut tranf- verfely, and cover only a part ; fome are hard, and others foft, and moft of them towards the top of the future, or line, at which they are applied to each other, have a fmall triangular piece affixed to the tho- rax, which is called fcutellum ; but this piece is wanting in fome. Laftly, in many infects the elytra are fattened together, and are 2$0 INSECTS. are formed of one motionlefs piece. The wings are often four in number, and are thin membranes, and tranfparent, as in the li- bella, the wafp, &c. or they are covered on each furface with a coloured powder, which, under the microfcope, appears to confift of fcales, placed over each other like tiles, im- bricatim. . The inferior part of the thorax is irre- gular, confifting of feveral pieces fattened to each other ; and fome of the legs are fixed to it. The number of legs varies in infects ; fome have fi#, and others eight, like fpiders : others have ten, as the hornet. Laftly, there are infects which have a much larger number; the wood-lice have fixteen ; and fome of fcolopendra, and centipedes, have as many as feventy, and one hundred and twen- ty, on each fide. Among thofe which have no more than fix, eight, or ten, they are all attached to the thorax, according to Geof- froy -, among thofe which have a larger num- ber, fome are inferted in the rings of the belly. The leg of an infect is always compofed of three parts ; the thigh, which joins to the body, the leg, and the tarfus. There is often an intermediate piece between the body and the thigh. The tarfus is formed of many pieces, or rings, articulated toge- ther, whofe number varies from two to five. In fome infects, the tarfus is more confider- able INSECTS. 25I able in the fore than in the hind feet; a circumftance which eftablifhed an analogy between thefe creatures and many quadru^ peds, whofe fore-feet have a greater number of digits than the hinder. M. Geoffroy has availed himfelf of this character, in his di- viiion, as we mall hereafter fee. The tarfus is terminated by two, four, or fix, fmall ' claws, or hooks, and is often furnimed with brufhes, or fpungy balls, on its lower part, by means of which the infect is capable of walking on the moft polifhed fubftances, fuch as glafs, &c. in any pofition. On each fide of the thorax, one or two oblong, oval apertures are obferved, which are called ftigmata, through which the in- feci: refpires. The third part of infects is the abdomen. It is moft commonly compofed of corneous rings, or half rings, which flip over one an- other; in fome the rings are not obferved, and the abdomen appears to be formed of a fingle piece : it is ufually larger in males than fe- males. The parts of generation are placed at its extremity ; a ftigma is obfervable on the fide of each ring, except the two lafh Many infects have flings at the pofterior part of their abdomen, fome of which are fharp and piercing, others in the form of a fiw, and fome of that of a gimblet. They ferve ei- ther as inftruments of defence, or to pene- trate 252 INSECTS. trate fubftances in which the infetts depofit their eggs. The moft Angular phenomenon, in which infects differ intirely from moft other ani- mals, confifts in the changes of ftate through which they pafs, or the metamorphofes they are fubjedted to, before they become per- fect infects. There are fome infects, and almoft all the clafs of aptera, wfych do not undergo thefe changes, but the great- er number are fubject to them ; the in- fect does not come out of the egg with the form of the mother, but in that of a worm, with or without feet, the ftrudturc of its head and the rings being exceedingly various. This firft ftate is the caterpillar ; under this kind of mafk, the infect eats, grows, moves, and changes its fkin feveral times. When it has grown to its full fize, it changes its fkin for the laft time, and no longer appears under the form of a worm, but under a different form, called nympha chryfaltSj aurelia. M. Geoffroy diftinguifhes four kinds of nymphae : the firft is that which does not refemble an animal; a few rings only are obferved at the lower part, and the upper part exhibits indiftindt impreffions of an- tennas, legs and wings. The fkin of this kind is hard, cartilaginous, and it has only a flight motion in its rings. The butterfly, phalaena, &c. are of this kind. The INSECTS. 253 The fecond kind of chryfalis admits of the parts of the perfedt animal being dif- tinguifhed beneath a thin and very foft fkin. It is motionlefs, like the forego- ing. Infedts with hard coverings to their wings, thofe with four naked wings, and thofe with two wings, afford examples of this kind. The third fpecies, is that whofe parts are perfectly developed, and which move ; fuch are thofe of the gnats and infedts which pafs the two firft ftages of their life in the water. Laftly, the fourth fpecies comprehends thofe which refemble the perfedt infedts in the form of their body, their antennae, and paws : thefe nymphae move, and eat ; they differ from perfedt infedts only in the want of wings, and in their being incapable of procreating. The nymphs of the libella, of the bug, of grafshoppers, and of crickets, &c. are of this kind. Infedts, like other animals, were only dif- tinguifhed by the ancient naturalifts from the places of their habitation. No one be- fore the time of Linnaeus attempted to dif- pofe them methodically, according to diftin- guifhing charadters. After Linnaeus, to whom we are indebted for the firft fyftematic divi- fion of thefe animals, M. GeofFroy attempt- ed to clafs them in a more accurate manner; his divifion of fedtions in genera is a mafter- piece of the kind, for precifion, accuracy, and 254 INSECTS. and perfpicuity : we fhall therefore follow his fyftem. M. Fabricius has fince availed himfelf of the form of the jaws to divide infers. M. Geoffroy divides infects into fix fec- tions, according to the abfence, the number, and the ftru&ure of the wings : the firft fection includes the coleoptera, or infects whofe wings are covered with cafes. Their mouth, which is armed with two lateral and corneous mandibles, forms likewife a general character of this fection. The May- bug exhibits both thefe characters. The fecond fection comprehends the he~ tniptera, whofe fnperior wings are either in a fmall degree thick and coloured, or rather hard and opake ; but as the character of the wings is i.ot flrongly marked in this fection, it is replaced by that of the mouth, which is conftant. This mouth is a long and flender trunk, turned inwards between the feet : the wood-bug and the cicada are of this fection. The third fedtion is compofed of tetrap- tera, with farinaceous wings, the four wings being coloured by a fcaly powder. Thefe have a trunk more or lefs long, and often of a fpiral form, as in the butterfly : Lin- naeus calls thefe lepidoptera. In the fourth fection are placed the te- trapteray with bare wings. Their four wings are membranous, and their mandibles are INSECTS. 255 are hard : the wafp is of this kind. Linnaeus has made two orders of thefe infe&s ; name- ly, the neuroptera, whofe anus has no fling, and whofe wings have nervous marks ; and the hymenoptera, which have the anus armed with a fting, and the wings membranous, without any very apparent nerves. The fifth fe&ion contains the diptera, or infedts with two wings ; their mouth is moft commonly in the form of a trunk, and they have ballancers under the infertion of their wings. Laftly, in the fixth and laft fe&ion are clafTed, the aptera, or infefts without wings, fuch as the fpider, the loufe, &c. Befides thefe primary divifions, M. Geof- froy has eftablifhed others, to facilitate the diftindion of infefts. See Table VII. CHAP. 256 WORMS. CHAP. VII. Of Worms. TyORMS are foft animals, of a very *^ different form from infe&s, with which they have been confounded by feve- ral naturalifts, their organization being lefs perfedt than that of thofe animals. They have no bones, properly fpeaking ; and their members are not conftrudted like thofe of infefts, neither are they, like them, fubject to pais through different ftates. Their or- gans, deftined for the purpofe of generation, are not known ; many worms have no head perfectly formed ; and laftly, the abfence of feet and fcales diftinguifh them from all other creatures. The clafs of worms is the mod numerous, and the lead known, of all animals. There are few organic fubftances, either living or dead, in which certain worms are not found, that fubfift and are nourifhed within them. Moft naturalifts have placed worms and polypi in the fame clafs ; but it would perhaps be better to feparate them, fince their internal ftru&ure and fun&ions perfectly diftinguifh them from each other. We know that moft worms contain a heart, and WORMS. 257 and veflels, but nothing fimilar has been dif- covered in polypi. The worms we now fpeak of mi] ft not be confounded with the larvcz of infecfts or caterpillars, which have likewife been called worms, merely on account of their form. Their head, furnifhed with mandi- bles, and their legs, which are more or lefs numerous, confifting commonly of fix, af- ford characters by which they may be eafily diftinguifhed. Worms have a considerable degree of ac- tivity, and in general love moifture. Some have not a head which can be eafily diftin- guifhed •, moft of them are hermaphrodites. Such as have a head, have two moveable horns, which they can retraft, and are called tentacula. All the worms, of which we are now giving an abridged account, have the property of being re-produced, when cut through ; a circumftance which {hews, that their organization is fimple, and refembles that of polypi. This clafs of animals may be divided into four feftions : the firft contains the naked, or bare worms, whofe organization is belt known, and which in their leading character refemble other animals ; in the fecond, we lhall place worms which have a teftaceous covering, or fhell-worms ; their organs are lefs known than thofe of the former fe<ftion ; the valuable refearches of Mr. Adanfon Vol. IV. R , prove, 258 ANIMAL FUNCTPONS. prove, however, that their ftructure refem- bles that of naked worms. The third fection will contain worms with a cruftaceous co- vering ; their organization is not fo well known as that of the foregoing, their ex- ternal form and the ftructure of their mouth only having been examined. And laftly, the fourth fection will include the polypi. The methodical divifions of thefe different fections have already afforded employment to many naturalifts ; Lifter, Linnasus, Klein, Ellis, Pallas, D'Argenville, are thofe of whofe affiftance we have availed ourfeives, in the imperfect divifion exhibited in our eighth table. See Table VIII. CHAP. VIII. The Functions of Animals confidered, from Man to the Polypus. 'THE characters peculiar to living and -^ organized bodies, confift, as we have already obferved, in the different functions executed by means of their organs. We have confidered thofe of vegetables ; the or- der we have adopted now leads us to the functions of animals. That part of the art of medicine, in which the Animal functions. 259 the functions of animals are examined, is called phyfiology. This ufeful and valuable fcience ought not to be confined to the fingle confiderationof the human fpecies, but mould be extended to all animals : in this point of view, we fhall curforily pals over the animal kingdom. The' functions of animals are reducible td the following : I. Circulation. II. Secretion. III. Refpiratiofl. IV. Digeftion. V. Nutrition. VI. Generation. VII. Irritability. VIII. Senfation. Thefe different functions are obferved iri man, quadrupeds, cetaceous animals, birds, fifhes, oviparous quadrupeds, ferpents, and infe&s. Worms and polypi do not poffefs them all, neither do ferpents nor infedts poffefs them in the fime degree. I. The circulation is one of the moil im- portant functions. It is indifpenfably ne- ceffary to maintain life. The organs by which it is performed, are the heart, the ar- teries, and the veins. The heart is a conical mufcle, towards the apex of which are two cavities, called ventricles ; and at its bafe, two other veffels, called auricles. A large artery, named the R 2 aorta, 260 ANIMAL FUNCTIONS. aorta, ilTues from the left ventricle, and distributes the blood to the various parts of the body ; another artery, of equal magni- tude, iffues from the right ventricle, which is called the pulmonary artery, becaufe it is fpread into ramifications in the lungs. The right auricle receives the blood which re- turns from every part of the body, by the two venae-cavae $ whence the fluid pafles into the right ventricle : from this laft it is trans- mitted to the lungs, by the pulmonary arte- ry, and is returned, by the pulmonary veins, into the left auricle, and thence to the left ventricle, from which it is propelled to all the parts of the body through the aorta. This motion, as it takes place in man, conftitutes two kinds of circulation ; that of the whole body, and the pulmonary circulation. The latter was known before the former. Har- vey, an Englifli phyfician, difcovered the general circulation. This fun&ion is performed in quadrupeds, cetaceous animals, and birds, abfolutely in the fame manner as in the human fpecies. In fifties, the heart has but one ventricle, and the lungs, or gills, do not receive blood, by means of a peculiar cavity of the heart. Rep- tiles refemble fifties in this refpedt. The heart of infedts and worms confifts of a feries of nodules, which contract one after the other ; their veflels are very fmall, and their blood cold and colourlefs. Polypi have neither heart ANIMAL FUNCTIONS. 26l heart nor veflels ; and are inferior to vege- tables, with refpedt to this fun&ion. II. Secretion is a fun&ion, by which dif- ferent organs feparate, from the blood, juices deftined to particular ufes, as the bile in the liver, &c. This function is one of the moil general in animals, and is found in all the clafles y but it is not poflible to attend to it in each, without entering into too long a detail. It will therefore be fufficient to obferve, that in all animals, which have a true circulation, the fecretions follow the fame laws as in man; and that it even appears to take place in moft animals which have not a heart. Befides the analogy that neceflarily fubfifts between man and animals which have the fame organs, with refpedt to the fundions we are treating of, certain clafles of animals exhibit peculiar fe- cretions, which are not performed in the hu- man fpecies ; fuch are the mufk and civet in quadrupeds, fpermaceti among cetaceous ani- mals, the oily fluid, with which birds fmear their wings, the virulent fluid of the viper, the adhefive fluid of the fcales of fifhes, the acrid and acid juices of the bupreftis, ftaphy- lini, ants, and wafps, among infe&s ; the vif- cous mucilage of fnails, the colouring juices of the purple fifh or murex, and a great many others, which the natural hiftory of each ani- mal difplays. III. Refpiration, confidered in all animals, is a function intended to bring the blood into contad; with the fluid they inhabit : men and R 3 quadru- 262 ANIMAL FUNCTIONS. quadrupeds, for this purpofe, have an orgai^ called the lungs. This vifcus confifts of a collection of hollow veficles, which are form- ed by the expanfion of a membranous and cartilaginous tube, called the arteria trachea, and of blood-veffels, which form a great number of areola? at the furface of the bron- chial veffels : thefe veficles and veffels are fuftained by a cellular, loofe, and fpungy fub- flance, which forms the parenchyma of the lungs. The air diftends the veffels by infpi- ration ; the bafe of the vital air of the atmo- fphere appears to combine with a principle difengaged from the blood, and forms the cretaceous acid, which is expired, together with the mephitis. The matter of heat, fe- parated from the vital air, unites with the blood, and reftores thofe properties which it had loft in paffing through the body. This function is performed in the fame manner in cetaceous animals ; excepting, however, that as there is an immediate com- munication between the auricles, thefe ani- mals are capable of remaining a confiderable time without refpiring. Though the refpiration in birds be ana- lagous to that of the animals laft treated of, yet it appears to be much more extenfive. Anatomifts have difcovered, in the abdomen of birds, fpungy veficular organs, which communicate with their lungs ; and thefe laft extend even into the bones of the wings, which ANIMAL FUNCTIONS. 263 which are hollow, and without marrow, by a channel placed at the upper parts of the breafts, and which opens in the fuperior part of the os humeri. This happy dif- covery of Mr. Camper teaches us, that the air paffes from the lungs of birds into the bones of their wings -, and that this fluid, rarefied by the heat of their bodies, renders them very light, and Angularly affifts their flight.* Fifhes have gills, or branchiae, inftead of lungs ; thefe organs are formed of membra- nous fringes, difpofed on a bony arch, and charged with a very great quantity of blood- veflels. The water enters by the opening of the mouth of fillies ; paffes through the fringes, which are by that means feparated from each other ; preffes and agitates the blood, and paffes out through apertures fi- tuated at the two lateral and pofterior parts of the head, on which two moveable bony valves, called opercula, are placed, and fuf- tained by the branchial membrane. Du- verney fuppofed that the brachiae feparate the air contained in water. M. Vicq d'Azir, who has paid great attention to the anatomy of fimes, thinks that the water performs the office of air in the branchiae of thefe ani- * This is doubtful. See Mr. John Hunter's account of certain receptacles of air in birds, which communicate with the lungs. Philof. Tranfa&ions, vol. 74, for the year 1774. T. R 4 mals, 264 ANIMAL FUNCTIONS. mals. It is certain, that as fifhes do not refpire air, and convert it into cretaceous acid, their blood does not poifefs the degree of heat, which the air gives to iuch animals as refpire it. Infedls have no lungs ; they have two tubes, or tracheae, placed along the back, from which, on each fide, other fmaller tubes iffue forth, and terminate at the lateral part of each wing, by a fmall cleft, called ftigma-: Thefe ftigmata appear rather to be defigned to emit fome elaftic fluid, fince in- fefts do not quickly die in a vacuum; though they have convullions, and expire in a few inftants, if the ftigmata be covered with oil or varnifh. Worms have an organization, flill lefs perfect. No kind of refpiration has been obferved in polypi, which, with refpedt to this function, are lefs perfect than vege- tables, in which we have obferved the tra- cheae. IV. Digeftion confifts in the feparation of the nutritive matter contained in food, and its abforption, by peculiar veffels, called chyliferous. It is performed in a channel, which is continued from the mouth to the anus, and which, in man, in enlarged to- wards the upper part of the abdomen. This enlargement is called the ftomach. The alimentary canal afterwards becomes narrower, is turned in different direc- tions, and is diftinguifhed by the name of ANIMAL FUNCTIONS. 265 pf the inteftines. This#long tube, which is formed of mufcles and membranes, retains the aliments, fo as to extract all the nutri- tive matter they contain. There are like- wife other glandulous organs, near the fto- mach, whofe office is to prepare the fluids requifite to ftimulate the ftomach and intef- tines, and to extract the nutritive part of the food : thefe organs are the liver, the fpleen, and the pancreas. The bile and pancreatic juice flow into the firft infeftine, called the duodenum, and mix with the food. Before this mixture is performed, the aliments are diifolved in the ftomach, by the gaftric juice. The whole courfe of the inteftines is co- vered with vafcular apertures, deftined to ex- tract the chyle. Thefe veflels convey it into the receptaculum lumbare, in the thoracic duct, and the chyle is poured into the left fubclavial vein, in which it mixes with the blood. Such, in a few words, are the me- chanifm and phenomena of digeftion in man. Quadrupeds differ greatly in the form of their teeth, ftomach, and inteftines : fome of thefe animals, as the ant-eater, and the fcaly lizard, which live on foft food, have no teeth; others, fuch as the floth and the armadillo, have only grinders ; others, as the elephant, and fea-cow, have molar and canine teeth ; laftly, the greater number have the three kinds of teeth, mojar, canine, and incifivej but their number, 266 ANIMAL FUNCTIONS. number, pofition, and ftrength, are fubjecfl to great variations. The moil finking circum- fiance in this various ftru&ure of the teeth, is, that, according to the remark made by Ariflotle, Galen, &c. there is a conftant re- lation between the number and pofition of thefe bones, and the form of the flomach. In fa6t, all quadrupeds, which have incifive teeth in both jaws, as the horfe, the ape, the fquirrel, the dog, the cat, have no more than one membranous ventricle, as in man; the anatomifts call thefe animals monogaf- trica: and in thefe the digeflion is perform- ed ahfolutely in the fame manner as in the human fpecies. Quadrupeds, which have incifive teeth only in the inferior jaw, zvzpoly- gajirica, and ruminating j fuch are the camel, the goat, the ram, the ox, the flag, &c. Thefe quadrupeds, which are ufually bifulc, and armed with horns, have four flomachs ; the fir ft, called in oxen the paunch, is the largeft, and is divided into four other cavities ; it receives the aliments at the fame time with the fecond, which opens into the paunch by a large orifice. The herbaceous aliments, contained in thefe organs, dilate, and the air becomes rarefied ; the nerves of thefe vifcera are flimulated, and an anti-periftaltic motion is excited, which returns them, through the oefophagus, into the mouth; where they are again mafticated by the molar teeth, and re- duced ANIMAL FUNCTIONS. 267 Juced into a kind of foft pafte. In this ftate, together with the drink, they are conducted, by a new deglutition, into the third fto- mach, called the omafus, by means of a dud paffing from the oefophagus to this laft ventricle. Laftly, they pais from the omafus into the fourth ftomach, where they are truly digefted. The intefrines of ruminating ani- mals, are likewife much more extended than thofe of monogaftric quadrupeds. Cetaceous animals perfectly refemble thefe laft, in the mechanifm of the now treated of function. Birds differ from each other in the ftructure of their ftomach -y in fome it is membranous, and in others flefhy, or mufcular. The firft fort, which may be called hymenogajlrica, are carnivorous -, all birds of prey are of this fpecies. Their ftomach contains a very ac- tive juice, capable of foftening bones, ac- cording to the experiments of Reaumur : their bile is likewife very acrid. The fe- cond, which may be called miogajirzca, fub- fift only on grain ; their ftomach is formed of a quadrigaftric mufcle, armed with a hard and thick membrane, proper for trituration : thefe birds have likewife a double ccecum. Fifhes have a membranous long ftomach, with many appendices ; their inteftines are in general fhort. Reptiles exhibit the fame ftrudture ; their ftomachs are capable of an aftonifhing degree of diftenlion. Serpents are often feen to fwallow intire animals, much larger than themfelves. Infects 268 ANIMAL FUNCTIONS, Infers have a ftomach, and inteftines, which are well organized. Swammerdam and Perrault affirm, that the mole cricket has four ftomachs. Their ftomachs are divided into four cavities, as may be eafily {ecn by differing this infect, which is very common, and much feared by gardeners. Worms have a very irregular ftomach, and likewife fmall inteftines. The polypus feems to be merely a ftomach, for it digefts very quickly : the fame aperture ferves this creature both as mouth and anus. V. Nutrition is a confequence of digeftion and circulation. As the folids always lofe, or become diminifhed, by the motions they perform, and require to be repaired, this is performed by nutrition. In the early part of life, they increafe in bulk, and the ani- mal grows. The cellular membrane is ufu- ally confidered as the organ of this function, and the lymph as the fluid proper to reftore the folids. It appears, neverthelefs, that each organ is nourifhed by a peculiar and proper matter, which it feparates, either from the blood, the lymph, or fome other fluid which paifes through it. For example $ the mufcles are maintained by the fibrous matter, which they feparate from the blood; the bones extract calcareous phofphoric fait, and lymphatic matter •> the pure lymph dries in laminae on the cellular texture; the con- creflible ANIMAL FUNCTIONS, 269 creffible oil being at th6 fame time depofited. Each organ, therefore, is nourimed in a peculiar manner, and in each, nutrition is a true fecretion. Quadrupeds and cetaceous animals perfectly refemble man, with regard to this function. The fame remark applies alfo to birds : but it is performed much lefs quickly with fifties ; for which reafon thefe animals live a very long time : the age of fome of them is not known ; but in general, the flower the nutrition and the growth, the longer the life. Infe&s exhibit nothing remarkable with regard to this function. It mufl only be obferved, that they grow only in the form of larvae, and not in that of the chryfalis, or of the perfed: infed:. Swammerdam and Malpighi have proved, that the larva contains a perfed infed:, ready formed be- neath a number of fkins. The caterpillar likewife contains the butterfly, whofe wings and feet are doubled up. In worms and polypi, nutrition is per- formed in the cellular membrane, and is likewife performed in vegetables, by means of the reticular and veficular membranes, VI. Generation, considered in all animals, is performed in many different manners ; moft of them have different (cxts, and re- quire conjunction. Such are the human fpecies, quadrupeds, and cetaceous animals. The females of quadrupeds have a matrix, feparated 2JO ANIMAL FUNCTIONS* feparated into two cavities, uterus hicornis^ and a confidefable number of teats ; they have not the menftrual flux; moft of them bear feveral young at a time ; the time of their geftation is fhorter ; feveral have a peculiar membrane to receive the urine of the foetus; this membrane is called allantoides. The generation of birds is very different. The males have a very ftrong and imperfo- rated genital organ, which is often double. The vulva, in females, is placed behind the anus $ the ovaria have no matrices ; and there is a duel, for the purpofe of convey- ing the egg from the ovarium into the in- terlines ; this paflage has been called oviduc- tus. The egg of pullets has exhibited un- expected facts to phyfiologifls, who have ex- amined the phenomena of incubation. The moft important difcoveries are thofe of Mal- pighi and Haller. The latter found the chicken, perfectly formed, in eggs which were not fecundated. There is no determinate conjunction among fillies ; the female depofits its eggs on the fand, over which the. male paries, and emits its feminal fluid, doubtlefs for the purpofe of fecundating them -, thefe eggs are hatch- ed after a certain time. The males of feveral oviparous quadru- peds have a double, or forked organ. A- mong ferpents, the viper is not viviparous. Infedls alone, exhibit -all the varieties which ANIMAL FUNBTIONS. 27I which are obferved in other animals. There are fome, and indeed the greater number, which have the fexes in two feparate in- dividuals ; among others, the re-production is made either with or without conjunction, as in the vine-fretter, Puceron ; one of thefe infects, confined alone beneath a glafs, pro- duces a great number of others. Mr. Bon- net has eftablifhed this fact, by experiments very carefully repeated. The organ of the male is inclofed in the abdomen, and may be caufed to appear, by lightly preffing the extremity of this part. It is ufually armed with two hooks, to feize the female. The place of thefe organs is greatly varied ; with fome it is at the upper part of the belly, near the breaft-plate, as in the female of the dragon-fly; in others, it is at the extremity of the antenna, as in the male fpider. In- fects multiply prodigioufly, and are almoft oviparous, except the wood-loufe. Worms are hermaphrodites ; each indi- vidual has two fexes, and the conjunction is double, as is obferved in the earth-worm and the fnail. Mr. Adanfon adds, that bivalves, fhell animals, or concha, have no organs of ge- neration, and reproduce their young without conjunction ; thefe worms are viviparous. Univalves, or fnails, are oviparous ; the fmall animals, whether they iffue from the belly of 272 ANIMAL FUNCTIONS. of the mother, or from eggs, have their fhell ready formed. Polypi are the fingular animals, with refpeft to generation ; they are reproduced by buds, or offsets : a bud is feparated from each vigorous polypus, which is fixed to fome neighbouring body, and grows : po- lypi are likewife found on their furface, in the fame manner as branches iffue from the trunks of trees. The mere phenomenaof generation compofe the whole of our knowledge of the fubjedt; and all the fyftems invented to explain this myftery are attended with infurmountable difficulties : they may be feen collected in the Phyfiology of Haller, the Venus Phyfi- que of Maupertuis, and the Natural Hiftory of BufFon. Mr. Bonnet has treated largely on this fubjedt, in his confiderations on or- ganized bodies. M. De BufFon has given an ingenious fyflem, which may be feen in his work. VI T. Irritability is the property which certain organs, called mufcles, poffefs of con- tracting or fhortening, by the aftion of any ftimulus which touches them. Mr. Haller has proved this valuable dodtrine inthemoft perfpicuous manner. The mufcles of man, of quadrupeds, of cetaceous animals, and of birds, refemble each other ; they are all alike red, compofed of fibres, united in bundles of different forms, covered with iilver-^o- luured ANIMAL FUNCTIONS, 2J 3 loured membranes, called aponeurofes, and terminated by flat, or round cords, named tendons. The mufcles of fimes are white, and much more irritable than thofe which are red. The irritability in oviparous quadrupeds and ferpents is ftill ftronger, and lafts a long time after the death of the animal. This ap- pears to be a common property in all animals whole blood is cold ; whereas, in animals which have warm blood, it difappears in proportion as that fluid cools. Infedts have their mufcles placed within their bones, which are hollow, and of the nature of horn. This ftrudture may be well obferved in the hollow thigh of the large green grafshopper, and may likewife be eafi- ly obferved in the lobfler. The mufcles of worms are very pale, and irritable ; they are likewife very ftrong in covered worms, which have a heavy fhell to carry. Polypi are very irritable ; they contract into a tingle point, and move their arms with Angular agility -, yet their ftructure does not appear to be mufcular. It is from the property of irritability that animals polfefs the power of tranfporting themfelves from place to place, and of per- forming a great number of motions, to re- move noxious things, and to obtain thofe which are ufeful. The hiftory of this func- Vol. IV. S tion 274 ANIMAL FUNCTIONS. tion ought, therefore, to include that of animal motions. Standing, walking, leap- ing, flying, creeping, or fwimming, are combined adlions, or the refults of mufcular contractions, in each clafs of animals. An explanation of thefe, would require a de- fcription of the extenfor mufcles of the thigh of man, for ftanding ; that of the ex- tremities of the figure of the body; the long and acute face, and the thorax, laterally comprefied, in quadrupeds, for leaping ; of the ftrudture of the feathers, the fternum, the pe&oral mufcles, the beak, the tail, and the interior texture of the bones, of birds, for flying. In this hiftory, likewife, it would be neceffary to confider at large, the mufcular annuli, the fcales, or the tuber- cules, which anfwer the purpofe of feet in reptiles; the form of the body, the ftrudure of the fins, of the air-bladder, and its com- munication with the ftomach, in fimes ; and in infedis, the ftrufture, number, and pofi- tion of the feet, the appendices of the tarfus, the form, pofition, and nature of the wings, the ballancers, Sec. But it is fufiicient, in this place, to have mewn the importance of thefe confiderations, and fuch as peculiarly deferve the attention of the phyfiologift. Laftly, there is another cenfideration, which does not appear to have been fufli- ciently attended to; namely, that a mufcle may be regarded as a fecretory organ, appro- priated ANIMAL FUNCTIONS. 275 priated to the feparation of the fibrous and irritable matter, of which we mall elfewhere fpeak ; and that the imperfections of this kind of fecretion ought to be very carefully obferved by phyficians. We fhall refume this fubject in our examination of the blood. VIII. Senfibility is a function, by means of which animals experience the fenfations of pleafure and pain, according to the nature of the bodies which are in contact with their organs. The fenfes depend on the brain, the medulla allongata, the fpinal marrow, and the pairs of nerves, which ifTue in great numbers from thefe three foci; without thefe organs, feniibility could not exift. In order to understand the mechanifm of this func- tion more readily, we may divide into three regions, thofe organs which are continued, and feem to form but one, which phyfio- logifts have called the fenfible man : thefe three regions conhTt of the brain, the ce- rebellum, and the medulla allongata; the middle or part of communication confifts of the nervous fibres, and the fenfitive expan- fion, or dilated extremity, of the nerves. This extremity exhibits various forms in different organs ; in fome it is membranous and re- ticular, as in the ftomach and inteftines; in others, it is foft and pulpy, as at the bottom of the eye, and in the labyrinth of the in- ternal ear : in fome fituations, it has the form of papillae, as beneath the fkin, on the S 2 tongue, 2^6 ANIMAL FUNCTIONS. tongue, and on the glands, &c. and in others it is fpread into long, foft, and flat fibres, as in the nafal membrane of Schneider. The brain in man is larger and better or- ganized than in other animals, and is the caufe of his underflanding. In quadrupeds it is much fmaller -, but on the other hand, their nerves are more fenfible, and their fenfes more acute, efpecially that of fmell, the organ of which is much dilated, and as it were multi- plied, by the number of ethmoidal lamina. Their thick hairy fkin deprives them, in a great meafure, of the fenfe of touch ; but their tafte is very acute. The ear has the fame apparatus, as in man. Cetaceous fifh have fcarcely any brain, in proportion to the mafs of their bodies ; this organ is furrounded with an oily and thick fluid; their fenfes are obtufe. The brain of birds has neither the fame ftructure nor the fame apparatus of folds, eminences, and concavities, as that of man and quadrupeds. The beautiful ftructure of the eyes of thefe animals, their magnitude, the thick and cartilaginous fclerotica, the internal eye- lid, or membrana niffiitans, mov- ed by peculiar mufcles, the mafs of the cryf- talline and vitreous humours, the veflel of black matter contained at the extremity of the optic nerve, the brilliant colour of the choroides, all denote a complicated organi- zation, and a peculiar care taken by nature to ANIMAL FUNCTIONS. 277 to render the fight of birds penetrating; that they may fee their prey at a great diftance, and avoid the dangers which the rapidity of their flight would otherwife have continu- ally led them into; and, in a word, to pro- mote that agility and quicknefs of motion, which appear to be the lot of thefe animals. Their fmell is lefs perfed: than their fight; they do not appear to be very fenfible of the fmell and tafte of food ; the fituation of the apertures of the noftrils, and the hard mem- brane which covers the beak, ferve to ex- plain thefe phenomena with fufficient faci- lity. Among reptiles the fenfibility is not very confiderable. The brain is very fmall, and the nerves have no ganglions ; the fenfes, in general, do not appear to be aftive, though the eye, and internal ear, prefented a very beautiful organization to Meffrs. Klein, Geoffroy, and Vicq d'Azyr. Fifties have a very fmall brain, and their cranium is filled with an oily matter. Their fenfes, more efpecially their fight and hear- ing, are of confiderable delicacy. The or- gan for the latter of thefe fenfes is very well formed, as Meffrs. Klein, Geoffroy, Cam- per, and Vicq d'Azyr have obferved. Such naturalifts as have fuppofed fifties to be deaf, appear therefore to be miftaken. Infefts have no brain, but a lengthened medullary fubftance, of a cylindric form, S 3 full 278 ANIMAL FUNCTIONS. full of nodules, which occupies the whole length of their body. From this fubftance iflue nervous fibres, which accompany the divifion of the trachea. The eyes of in-. fects are known. Swammerdam has de- fcribed an optic nerve, which is divided in fuch eyes as have the appearance of net- work, into as many fibres as there are facets in that membrane. It is not known whether they have an organ of hearing. Few or no traces of the fenfible organ are perceived in worms. Swammerdam found in the fnail a brain moveable and with two lobes, eyes placed either on the bafe or at the point of the tentacula, and an optic nerve, contraftable like thofe kind of horns. Mr. Adanfon affirms, that eyes are fome- times either wanting in worms, or that they are covered with an opake fkin. As to polypi, they have no organ of fenfe, though they appear to feek the light. Senfibility is therefore a funftion enjoyed by man in a much ftronger degree than by other animals. It is this which diftinguifhes him, and places him at the head of the ani- mated creation ; and this fundion requires to be carefully and minutely inquired into, by the legiflator, the philofopher, and the phyfician. CHAP. ANALYSIS. 279 CHAP. IX. Concerning the Chemical Analyfis of Ani- mal Subitances in general. /TpHE analyfis of animal fubftances is a ■** part of chemiftry, which is the moft difficult, and leaft advanced of any. The ancient chemifts contented themfelves with diftilling thefe fubftances by a naked fire; an operation which is now known to alter, and intirely change bodies of fo compounded a nature as the folids and fluids of animals. Some of the fluids of the human frame, and of certain quadrupeds, only have been fub- jedled to this analyfis. Many caufes oppofe the advancement of this branch of chemiftry; the difliculty and unpleafantnefs of thefe experiments, the fmall number of expedients for the treat- ment of animal matters, without changing them very much, the impofiibility of finding the moft remote fynthetical method of re- producing thefe matters, and more particu- larly the uninterefting nature of thefe re- fearches to chemifts who are not phyiicians, are the principal motives which have hither- to impeded the progrefs of fcience refpe&zng S 4 them. 28o ANALYSIS OF them. Neverthelefs, the refearches of cer- tain modern philofophers, efpecially Meffrs. Rouelle, Macquer, Bucquet, Poulletier de la Salle, Berthollet, Prouft, Scheele, and Bergman, have opened a new path, and fhew that the art of healing may receive the great- eft advantages from inquiries of this nature. The bodies of the principal animals, fuch as man and quadrupeds, to which cur at- tention is particularly directed, are formed of fluids and folids. The fluids of animals are diftinguifhed into three clalTes, relative to their ufes. The firit clafs contains the recrementitial humours, defigned to nourifh and fupport certain organs. The fecond com- prehends the excrementitial humours which are excluded out of the body, by certain emunctories, as ufelefs, and capable of pro- ducing noxious effects, if retained too long. In the third are ranked, fuch as are of the nature of the two preceding, being partly recrementitial, and partly excrementitial : the former are the blood, the lymph, the jelly, the fibrous or glutinous part, the fat, the marrow, the matter of internal perfo- ration, and the offeous juice; the latter comprehends the fluid of infenfible tranfpi- ration, the fweat, the mucus of the noftrils, the cerumen of the ears, the gummy mat- ter of the eyes, the urine, and the feces. Thefe laft are the faliva, the tears, the bile, the pancreatic juice, the gaflric and intef- tinaj ANIMAL SUBSTANCES- 281 tinal juices, milk, and the feminal liquor. We cannot examine all thefe fluids in the order we have enumerated them ; 1 . Becaufe they are very little known; 2. Becaufe it is indifpenfably neceffary to treat of thofe, in the firft place, whole analyfis is the moft advanced. The folids of animals, which form the parenchyma of their different organs, may be divided into three claffes ; the firft con- taining foft and white parts, as the laminae of the cellular tiffue, the membranes, the membranous vifcera, the aponeurofes, the ligaments, the tendons, and the fkin. The foft and red parts form a fecond clafs, very diftincT: from the firft -y fuch, in particular, are the mufcles, and a part of thofe organs which contain mufcular fibres, fuch as the ftomach, the inteftines, the bladder, the ma- trix, &c. Laftly, the third clafs compre- hends the bony folids. The animal analyfis is at prefent very dif- ferent from that formerly ufed. The decom- pofition by fire is now no longer praclifed, and animal matters are treated with re-agents, more efpecially acids, alkalis, fpirits of wine, &c. The different fluids, mixed with each other, or contained in the veficles of the different parts, are feparated by repofe, by decantation, by filtration, or by expref- fion. The action of thefe fubftances on co- louring matters is examined, as well as the feveral 1?2 ASALYS1S OF feveral changes they undergo at different ten ires. By careful evaporation of I liquors, the different (alts they con- tai: panted without alteration. By theft methods c Gs, modern che- at diicoveries. ; difee rat Is different from all thole b known. M. Berthol- let taincd the exigence of difen- gage /phoric acid in urine, and in iweat; he has likewift found a very ccnliderahle quantity of mephitis in This I im- port is j the pre; fefubft. and . explains the dch e\ em and To cnlat flefli treated with quantity is >ut the : of before , and the : loft be than jc ins to ; . M. Berthollet explai: the formation erf bdi, afforded by :~:ra tc :!on o{ fire. ::ion and i gc- ment of :'/-■ (alt ther :ion or re] mce of th< ccs with ' . tters, which putrefy, ANIMAL SUBSTANCES. 283 putrefy, and afford volatile alkali by diflil- lation. It appears, in fact, that this alkali is formed, in both cafes, by the combina- tion of inflammable gas with mephitis. I cannot do better than quote, in this place, the words of M. Berthollet on the general nature of animal fub fiances, in a memoir read at a public meeting of the Faculty of Medicine, and inferted in the Journal de . Phyfique, Vol. XXVIII. Page 272. " Organized bodies are principally com- " pofed of two fubflances, which have very " evident diilin&ive charajfters : the one " affords acid, when decompofed by the " a&ion of fire, and the other volatile al- " kali -, the one forms ardent fpirit, by fer- " mentation, the other putrefies immedi- " ately, and affords volatile alkali; the one, " by calcination, affords a coal, which burns <c readily, the other is reduced into a coal t( of difficult combuflion : laftly, the for- <c mer compofe the greatefl part of vege- " table, and the latter of animal, fubflances; " whence they are diflinguifhed by the two " denominations. " M. Bergman formed, by means of fugar m and the nitrous acid, an acid which he " called the faccharine acid, and which " poffeffes remarkable properties. I applied " this kind of analyfis by the nitrous acid " to animal fubflances, and I found that I* they all afforded a greater or lefs quantity " of 284 ANALYSIS OF " of faccharine acid, but always accompa- " nied with a peculiar oil. I obferved that " no ammoniacal fait was obtained, but •' that a refidue was afforded, which is not €e found in vegetables. From thefe firfl " experiments I concluded (Memoires de " l'Academie, 1780) that animal fubflances «* contained a fubftance analogous to fugar, *' united to an oil, which I confidered as '* peculiar to animal fubftances. My ex- " periments likewife informed me, that the *c volatile alkali did not exifl in animal fub- €t fiances, but that it arofe from a combi- ** nation formed either by the action of heat, <c or the influence of putrefaction ; and €C lailly, the refidue concerning which I " did not explain myfelf in that memoir, <c contains phofphoric acid in excefs, com- " bined with calcareous earth. " I afterwards examined the action of V lime and metallic falts on animal fub- €C fiances, and proved, that this action in €€ which their cauflicity confifls, is a con- " fequence of the chemical affinities of the •* metallic calces, which tend with various " degrees of force to become revived ; fo *' that thofe which are very eafily revived, tc fuch as the calces of filver and of mer- " cury, have a flrong degree of cauflicity, *' and form very cauflic falts. Hence " it follows, by applying the modern dif- " coveries of philofophers to the theory I " have ANIMAL SUBSTANCES. 285 have given, that it is the air combined in metallic calces, and deprived of the prin- ciple of elafticity, which tends to unite with a principle of animal fubftances, and this principle appears to me to be the oil they contain ; but the caufticity of alkalis cannot be attributed to the fame caufe, but muft be the effedt of another affinity. I have proved in the Memoirs of the Academy for the year 1782, that the cauftic alkali diffolved animal fub- ftances without difuniting their princi- ples. I have fhewn the properties of this combination, and have availed myfelf of it to unite the animal fubftances with different metallic calces ; feveral combi- nations were produced, which were be- fore unknown to chemifts ; but the cauf- tic alkali treated in the fame manner with vegetable fubftances formed no combina- tion. " " By purfuing my inquiries, I have fuc- ceeded in determining the principles of the volatile alkali. I have fhewn, that the volatile alkali is a combination of detonating inflammable gas, or, to fpeak more accurately, of the inflammable gas of water and phlogifticated air, or me- phitis : fo that the inflammable gas forms nearly the fixth part of the weight, or two-thirds of the volume of the volatile alkali. I have fince determined how the " volatile 286 ANALYSIS OF " volatile alkali is produceable by putrcfao " tion, or by the action of fire. All mat-, " ters which have the character of animal f< fubftances contain mephitis, which may " be abundantly feparated by means of the V nitrous acid. It mult neceffarily happen, " therefore, when thefe fubftances are dif- " tilled, that their mephitis mull pafs into " fome combination, or that it will be found " among the aeriform products -y but it is " not found in thefe laft, as I have afcer- ic tained, by detonating the inflammable gas " obtained by this method in the eudiometer " ofM. Volta, and comparing it with the " inflammable gas obtained by the diftilla- " tion of charcoal, and that of vegetable " fubftances ; and there is nothing among " the other products of the diftillation but *? the volatile alkali, which can have re- " ceived it into its compofition. Confe- " quently, whenever v.olatile alkali is form- " ed, the mephitis of the animal fubftances " combines with the inflammable gas, which " is feparated from the oil, or moft proba- " bly with that which arifes from the de- " compofition of the water, whofe vital air " at the fame time combines with thechar- " coal to form fixed air. In putrefaction, M the inflammable gas combines with the " mephitis; whereas in the fpirituous fer- " mentation, the fame gas combines with u a vegetable oil and fugar, to form fpirit " of ANIMAL SUBSTANCES. 287 * of wine, in which I have found and fepa- ? rated thefe fubftances, by means of the f dephlogifticated marine acid. " From thefe feveral obfervations it fol- € lows, that animal fubftances are much * more compounded than fubftances which ' are purely vegetable. They contain a f matter analogous to fugar, a peculiar oil, f phofphoric acid combined with a fmall ' quantity of calcareous earth, mephitis, 1 and very probably fixed air. It is the * phofphoric acid which exifts in the coal 1 of animal fubftances, combined with a ' portion of the true charcoal, of the oil, * and with earth, that appears to