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 bb% OH' 
 
 

 
 
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elements 
 
 O F 
 
 CHEMISTRY. 
 
 By M. I. A. CHAPTAL, 
 
 CHEVALIER OF THE ORDER OF THE KING, PROFESSOR OF CHEMISTRY 
 AT MONTPELLIER, HONORARY INSPECTOR OF THE MINES OF 
 FRANCE, AND MEMBER OF SEVERAL ACADEMIES OF 
 SCIENCES, MEDICINE, AGRICULTURE, IN- 
 SCRIPTIONS AND BELLES LETTRES. 
 
 TRANSLATED FROM THE FRENCH. 
 
 THE THIRD EDITION. 
 
 IN THREE VOLUMES. 
 
 VOL. I. 
 
 LONDON: 
 
 SsHoa 
 
 C4 (a 
 V.i' 
 
 PRINTED, FOR G. G. AND J, ROBINSON. 
 PATERNOSTER-ROW, 
 
 AY R. NOBLE, IN THE OLD BAILEY. 
 
Digitized by the Internet Archive 
 in 2015 
 
 https://archive.org/details/elementsofchemis01chap 
 
s' 
 
 THE great experience of M. Chaptal, his 
 unaffected candour, and the perfpicuity which 
 is feen in every part of the following treatife, 
 cannot but render it extenfively ufeful. I have 
 been particularly careful not to diminifh this 
 laff merit, by deviating in any refpeft from that 
 fcrupulous attention to accuracy which isindif- 
 penfably required to give authority to the tranf- 
 lation of a w ork of fcience. 
 
 « 
 
 W. NICHOLSON. 
 
 i 
 
CONTENTS 
 
 OF THE 
 
 FIRST VOLUME. 
 
 PART FIRST. 
 
 CONCERNING THE CHEMICAL PRINCIPLES. 
 
 INTRODUCTION. 
 
 Definition of chemifiry; its 
 
 Objed: and Means — Defcription of a 
 Laboratory, and the principal Inftru- 
 ments employed in chemical Opera- 
 tions, with a Definition of thofe Ope- 
 rations — - — 
 
 Page 
 
 s 
 
 I 
 
 SECTION I. 
 
 Concerning the General Law which tends 
 to bring the Particles of Bodies toge- 
 ther, and to maintain them in a State 
 of Mixture or Combination — 22 
 
 Of 
 
ti CONTENTS. 
 
 Of the Affinity of Aggregation 
 
 Of the Affinity of Compofition 
 
 SECTION IL 
 
 Concerning the various Means employed 
 by Chemifts to overcome the Adhefion 
 which exifts between the Particles of 
 Bodies — — — 
 
 SECTION III. 
 
 Concerning the Method of Proceeding 
 which the Chemift ought to follow in 
 the Study of the various Bodies pre- 
 fented to us by Nature — — 
 
 SECTION IV. 
 
 Concerning Simple or Elementary Sub- 
 ftances — — — 
 
 Chap. I. Concerning Fire * 
 
 Art. I. Concerning Caloric and Heat 
 
 Art. II. Concerning Light <-«*- — 
 
 Chap. II. Concerning Sulphur 
 
 Chap, III. Concerning Carbone — 
 
 SECTION V. 
 
 Concerning Gafes, or the Solution of cer- 
 tain Principles in Caloric, at the Tem- 
 perature of the Atmofphere — 
 
 Chap. I. Concerning Hydrogenous Gas, or In- 
 flammable Air - — - 
 
CONTENTS. vii 
 
 Chap.IL Concerning Oxigenous Gas, or Vital 
 
 Air 1 13 
 
 Chap. III. Concerning Nitrogene Gas, Azote, or 
 
 Atmofpherical Mephitis — 138 
 
 SECTION VI. 
 
 Concerning the Mixture of Nitrogene and 
 OxigeneGas; or of Atmofpheric Air 141 
 
 SECTION VIL 
 
 Concerning the Combination of Oxige- 
 nous Gas and Hydrogene, which forms 
 Water — — - 145 
 
 Art. I. Concerning Water in the State of Ice 148 
 
 Art. II. Concerning Water in the Liquid State 152 
 
 Art. III. Concerning Water in the State of Gas 156 
 
 SECTION VIII. 
 
 Concerning the Combinations of Nitro- 
 gene Gas. 1. With Hydrogene Gas. 
 
 2. With Earthy Principles forming 
 
 the Alkalis — — 165 
 
 Chap. I. Concerning Fixed Alkalis 166 
 
 Art. I. Concerning the Vegetable Alkali, or 
 
 Potaib 167 
 
 Art. II. Concerning the Mineral Alkali, or 
 
 Soda — — — 170 
 
 Chap. II. Concerning Ammoniac, or the Volatile 
 
 Alkali — » — - — 178 
 
 SEC- 
 
via 
 
 CONTENTS. 
 
 SECTION IX. 
 
 Concerning the Combination of Oxigene 
 • with certain Bafes forming Acids — 184 
 
 Chap. I. Concerning the Carbonic Acid — 
 
 Art. I. Carbonate of Potafh 
 
 Art. II. Carbonate of Soda . — 
 
 Art. III. Carbonate of Ammoniac 
 
 Chap. II. Concerning the Sulphuric Acid 
 
 Art. I. Sulphate of Potafh 
 
 Art. II. Sulphate of Soda — 
 
 Art. III. Sulphate of Ammoniac — 
 Chap. III. Concerning the Nitric Acid — 
 
 Art. I. Nitrate of Potafh 
 
 Art. II. Nitrate of Soda - — 
 
 Art. III. Nitrate of Ammoniac — 
 
 Chap. IV. Concerning the Muriatic Acid 
 
 Art. I. Muriate of Potafh — * 
 
 Art. II. Muriate of Soda 
 
 Art. III. Muriate o£ Ammoniac 
 
 Chap. V. Concerning the Nitro-muriatic Acid 
 Chap. VI. Concerning the Acid of Borax 
 
 Art. I- Borate of Potafh v — 
 
 Art. II. Borate of Soda ■ — 
 
 Art. III. Borate of Ammoniac 
 
 Concerning Mineral Waters — 
 
 190 
 
 201 
 
 202 
 
 203 
 
 20 £ 
 
 212 
 
 213 
 
 217 
 
 228 
 
 236 
 ib. 
 
 237 
 
 249 
 
 250 
 256 
 260 
 263 
 
 267 
 
 268 
 
 273 
 
 274 
 
 C 
 
ADVERTISEMENT 
 
 O F 
 
 THE AUTHOR, 
 
 GRICULTURE is no doubt the 
 
 bafis of public welfare, becaufe it 
 alone fupplies all the wants which nature 
 has conne6led with our exiftence. But the 
 arts and commerce form the glory, the or- 
 nament, and the riches of every polifhed 
 nation ; fince our refinement, and mutual 
 dependence on each other, have created a 
 new fet of wants which require to be fup- 
 plied. The cultivation of the arts is there- 
 fore become almoft as necelfary as that of 
 the ground ; and the true means of fecuring 
 Vol. I, a thefe 
 
 X A' 
 
ii Advertijement 
 
 thefe two foundations of the reputation and 
 profperity of a ftate, conlift in encouraging 
 the Science of Chemiftry, which difcovers 
 their principles. If this truth were not 
 univerfally acknowledged, I might on the 
 prefen t occafion give an account of thefuc- 
 cefs with which my labours have been at- 
 tended in this province*. I might even call 
 upon the public voice; and it would declare 
 that, fince the eftablifhment of leCtures on 
 chemiftry, between three and fourhundred 
 perfons have every year derived advantage 
 'from inftruflions in this fcience. It is well 
 known that our ancient fchools of medicine 
 and furgery, whofe fuccefs and fplendour 
 are connected with the general intereft of 
 this province, are more flourishing and 
 more numerous fince that period. And 
 with the fame confidence I might appeal 
 to the Public, that our manufactures are 
 daily increafing in perfection ; that feveral 
 new kinds of induftry have been introduced 
 into Languedoc ; that, in a regular fuccef- 
 fion, abufes have been reformed in the ma- 
 nufactories, while the proceffes of the arts 
 * Languedoc. 
 
 have 
 
of the Author . iii 
 
 have been Amplified; that the number of 
 coal-mines aCtually wrought is increafed ; 
 and that, upon my principles, and in con- 
 fequence of my care and attention, manu- 
 factories of alum, of oil of vitriol, of cop- 
 peras, ofbrownred, of artificial pozzolana, 
 of cerufe, of white lead, and others, have 
 been eftablifhed in feveral parts of the pro- 
 vince. 
 
 Chemiftry is therefore elfentially con- 
 nected with the reputation and profperity 
 of a ftate ; and at this peculiar inftant, 
 when the minds of men are univerfally 
 bufied in fecuring the publip welfare, every 
 citizen is accountable to his country for all 
 the good which his peculiar fituation per- 
 mits him to do. Every one ought to haften, 
 and prefent to fociety the tribute of thofe 
 talents which heaven has bellowed on him ; 
 and there is no one who is not able to 
 bring fome materials, and depofit them at 
 the foot of the fuperb edifice which the 
 virtuous adminiftrators are railing for the 
 welfare of the whole. It is with thefe views 
 that I have prefumed to offer to my coun- 
 trymen the work which I at prefent pub- 
 a 2 lifh i 
 
iv Advertiftment 
 
 lifh; and I entreat them to exercife their 
 feverity upon the intention of the author 
 only, but to referve all their indulgence 
 to the work. 
 
 I publifh thefe Elements of Chemiftry 
 with the greater confidence, becaufe I have 
 had opportunities myfelf of obferving the 
 numerous applications of the principles 
 which oonftitute its bafis to the phenome- 
 na of nature and art. The immenfe efta- 
 blilhment of chemical products which I 
 have formed at Montpellier has allowed 
 me to purfue the development of this doc- 
 trine, and to obferve its agreement with all 
 the fafls which the various operations pre- 
 fent to us. It is this doctrine alone which 
 has led me to Amplify raoft of the pro- 
 ceffes, to bring fome of them to perfection, 
 and to reftify all my ideas. It is therefore 
 with the moll intimate confidence that I 
 propofe it. I find no difficulty in making 
 a public acknowledgment that I have for 
 fome time taught a different doftrine from 
 that which I at prefent offer. I then be- 
 lieved it to be true and folid ; but I did 
 not on that account ceafe to confult 
 
 nature. 
 
V 
 
 cf the Author . 
 
 nature. I have coiiftantly entered into 
 this refearch with a mind eager for im- 
 provement. Natural truths were capable 
 of fixing themfelves with all their purity 
 in my mind, becaufe I had banifhed pre- 
 judice; and infenfibly I found myfelf drawn 
 by the force of facls to the dofirine I now 
 teach. Let other principles imprefs the 
 fame conviftion on my mind ; let the fame 
 number of phenomena and fafts exhibit 
 themfelves in their favour ; the fame num- 
 ber of happy applications to the opera- 
 tions of nature and of art; let them appear 
 to my mind with all the facred charaflers 
 of truth; and I will publifii them with the 
 fame zeal, and with the fame intereft. I 
 condemn equally the man who, attached 
 to the ancient notions, refpe£ts them fo 
 much as to rejeft without mature exami- 
 nation every thing which appears to op- 
 pofe them ; and him who embraces with 
 enthufiafm, and almoft without reflexion, 
 the principles of any new doftrine. Both 
 are worthy of compaffion if they grow 
 old in their prejudices ; and both are 
 worthy of blame if they perpetuate them. 
 
 I have 
 
vi Advertifemeni 
 
 I have been careful to banifh all difcuf- 
 fions from my work. That fpirit of party 
 which but too often caufes a divifion be- 
 tween perfons who are purfuing the fame 
 obje&s, that tone of bitternefs which pre- 
 dominates in certain difputes, that want of 
 candour which is infenfibly produced by 
 the movements of felf-love, have but too 
 long retarded the progrefs of our know- 
 ledge. The love of truth is the only paf- 
 fion which a philofopher ought to indulge. 
 The fame objeft, the fame intereft, tend to 
 unite chemifts. Let the fame fpirit infpire 
 them, and direft all their labours. Then 
 we (hall foon behold chemiftry advancing 
 in a rapid progrefs ; and its cultivators 
 will be honoured with the fuffrage and the 
 gratitude of their countrymen. 
 
 I have endeavoured in this work to ex- 
 plain my ideas with clearnefs, precifion, 
 and method. I know by experience that 
 the fuccefs of any work, and its various 
 degrees of utility, often depend on the 
 form under which the doftrine which it 
 contains is difplayed ; and it has accord- 
 ingly been my intention to fpare no pains 
 
 in 
 
of the Author. vix 
 
 in exhibiting the truths which form the 
 bans of this work in all the chara£ters 
 they are juftly entitled to* 
 
 In compofing thefe Elements of Che- 
 miftry, I have availed myfelf with advan- 
 tage of all the fa£is which I have found 
 in the works of the celebrated chemifts 
 who adorn this age. I have even made 
 no fcruple to follow their method in draw- 
 ing up certain articles ; and have transfer- 
 red into my own work, almoft without al- 
 teration, thofe fa£is which I have elfe- 
 where found defcri bed with a greater degree 
 of precifion and perfpicuity than I might 
 have been capable of beftowing on them. 
 This proceeding, in my opinion, renders 
 homage to authors, inftead of robbing 
 them. If fuch a proceeding might jufli- 
 fy reclamations, Meffrs. Lavoifier, De 
 Morveau, Berthollett, De Fourcroy, Sage, 
 Kirwan, & c. might eafily declare again!! 
 me. 
 
 I was well aware that the pretenfion of 
 knowing, difcufiing, and methodically dis- 
 tributing the whole of our prefent fcience 
 of chemiftry, was an enterprife beyond my 
 
 ability. 
 
viu Advertifemenl 
 
 ability. This fcience has made fo great <l 
 progrefs, and its applications are fo multi- 
 plied, that it is impoffible to attend to the 
 whole with the fame care: and it appears 
 to me that the writer of an elementary 
 work ought at prefent to attend princi- 
 pally to the development of general prin- 
 ciples, and content himfelfin pointing out 
 the confequences, and their applications. 
 In this way of proceeding we fhall follow 
 the method which has long been pra£tifed 
 in the ftudy of the mathematics ; the prin- 
 ciples of which, nearly infulated, and le- 
 parated from all application, form the firft 
 ftudy of him who means to acquire them. 
 
 To obtain a thorough acquaintance 
 with all the knowledge which has been ac- 
 quired in chemiftry until our time, the 
 chemical part of the Encyclopedic Me- 
 thodique may be confulted. In this work, 
 the celebrated author gives the moft in- 
 terefting account of the progrefs of the 
 fcience. Here it is that he difcuffes the 
 feveral opinions with that candour and 
 energy which become the man of letters 
 whole mind is directed' to truth only. 
 
 Here 
 
of the Author . ix 
 
 Here it is that he has made a precious de- 
 pofit of all the knowledge yet acquired, 
 in order to prefent to us in the fame point 
 of view all which has been done, and all 
 which remains to be done ; and here, in 
 a word, it is that Mr. De Morveau has 
 rendered the moll ftriking homage to the 
 truth of the doftrine we now teach ; be- 
 caufe, after having combated fome of its 
 principles in the firft volume, he has had 
 the courage to recant, the moment the fafts 
 feen in a better point of view, and re- 
 peated experiments, had fufficiently en- 
 lightened him. This great example of 
 courage and candour is doubtlefs honour- 
 able to the learned man who gives it ; but 
 it cannot fail to add Hill more to the con- 
 fidence which may be placed in the doc- 
 trine which is its objeft. 
 
 The development of the principles up- 
 on which the New Nomenclature is efta.- 
 blifhed, may be found in the Elementary 
 Treatife of Chemiftry of Mr. Lavoifier ; 
 and I refer likewife to this excellent work 
 for the figure and explanation of all the 
 apparatus I (hall have occafion to fpeak 
 
 of. 
 
X Advertifcment of the Author . 
 
 of. I take this ftep the more earneftly, 
 becaufe, by affociating my own produc- 
 tions to thofe of this celebrated chemift, 
 I entertain the hope of fecuring their fuc- 
 cefs, and can deliver them into the hands 
 of the public with greater confidence. 
 
 
 
 
 
 V, 
 
 
 
 PRE* 
 
PRELIMINARY DISCOURSE. 
 
 I T appears that the ancient nations pof- 
 felled fome notions of chemiltry. The 
 art of working metals, which dates from the 
 moll remote antiquity ; the luftre which 
 the Phoenicians gave to certain colours; 
 the luxury of Tyre ; the numerous manu- 
 factures which that opulent city included 
 within its walls — all announce a degree of 
 perfection in the arts, and fuppofe a conli- 
 derable extent and variety of chemical 
 knowledge. But the principles of this 
 fcience were not then united into a body 
 of doCtrine ; they were concentrated in the 
 worklhops of the manufacturers, where 
 they had their origin ; and obfervations 
 alone, tranfmitted from one operator to 
 
 another. 
 
xii Vrel'nninary Difcourfe . 
 
 another, enlightened and conducted the 
 fteps of the artift. Such, no doubt, has been 
 the origin of all the fciences. At firft they 
 prefented unconnefted fa£ls ; truths were 
 confounded with error; time and genius 
 alone could clear up theconfufion; and the 
 progrefs of information is always the fruit 
 of flow and painful experiment. It is dif- 
 ficult to point out the precife epochaof the 
 origin of chemical fcience; but we find 
 traces of its exiftence in the moft remote 
 ages. Agriculture, mineralogy, and all the 
 arts which are indebted to it for their prin- 
 ciples, were cultivated and enlightened. 
 We behold the original nations, immediate- 
 ly fueceeding the fabulous ages, furround- 
 ed by all the arts which fupplied their 
 wants ; and we may compare chemiftryto 
 that famous river whofe waters fertilize 
 the lands they inundate, but whofe fources 
 are ftill to us unknown. 
 
 Egypt, which appears to have been the 
 nurfe of chemiftry reduced to principles, 
 was not (low in turning the applications of 
 this fcience towards a chimerical end. The 
 firft feeds of chemiftry were foon changed 
 
 by 
 
Preliminary Difcourfe. xiil 
 
 by the paftion of making gold. In a mo- 
 ment all the labours of operators were di- 
 refted towards alchemy alone ; the great 
 objeft of ftudy became fixed on an endea- 
 vour to interpret fables, allufions, hierogly- 
 phics, &c. ; and the induftry of feveral 
 centuries was confecrated to the enquiry 
 after the philofopher’s ftone. But though 
 we admit that the alchemifts have retarded 
 the progrefs of chemiftry, we are very far 
 from being difpofed to any outrage on the 
 memory of thefe philofophers : we allow 
 them the tribute of efteem to which on fo 
 many accounts they are entitled. The pu- 
 rity of their fentiments, the fimplicity of 
 their manners, their fubmiffion to Provi- 
 dence, and their love for the Creator, pene- 
 trate with veneration ail thofe who read 
 their works. The profoundeft views of 
 genius are every where feen in their writ- 
 ings, allied with the moft extravagant ideas. 
 The moft fublime truths are degraded by 
 applications of the moft ridiculous nature; 
 and this aftoniftting contraft of fuperftition 
 and philofophy, of light and darknefs, com- 
 pels us to admire them, even at the inftant 
 
 that 
 
xiv Preliminary Difcourfe . 
 
 that we cannot withhold our cenfure. We 
 muft not confoundthe feci of alchemifts, of 
 whom we {hall proceed to fpeak, with that 
 crowd of impoftors, that fordid multitude 
 ofoperators at the furnace,whofe refearches 
 were directed to the difcovery of minds ca- 
 pable of being impofed on, who fed the 
 ambition of fuch weak minds by the de- 
 ceitful hope of increafmg their riches. This 
 laflclafs of vile and ignorantmen hasnever 
 been acknowledged by the true alchemifts; 
 and they are no more entitled to that name, 
 than the vender of fpecifics on the ftage to 
 the honourable name of Phyfician. 
 
 The hope of the alchemift may indeed be 
 founded on a (lender bafis ; but the great 
 man, the man of genius, even at the time 
 when he is purfuing an imaginary objefl, 
 knows how to profit by the phenomena 
 which may prefent themfelves, and derives 
 from his labours many ufeful truths which 
 would have efcaped the penetration of or- 
 dinary men. Thus it is that the alchemifts 
 have fuccefiively enriched pharmacy and 
 the arts with moft of their compofitions. 
 The Itrong defire of acquiring riches has in 
 
 all 
 
Preliminary Difcourje . X"V 
 
 all times been a paffion fo general, that this 
 lingle motive has been fufficient to lead 
 many perfons to the cultivation of a fcience 
 which has more relation than any other to 
 metals ; which ftudies their nature more 
 particularly, and appears to facilitate the 
 means of compofing them. It is known 
 that the Abdarites did not begin to confider 
 the fciences as an occupation worthy a rea- 
 fonable man, until they had feen a celebrated 
 philofopher enrich himfeif by fpeculations 
 of commerce ; and I do not doubt but that 
 the defire of making gold has decided the 
 vocation of feveral chemifts. We are there- 
 fore indebted to alchemy for feveral truths, 
 and for feveral chemical profelfors : but this 
 obligation is fmall, in comparifon to the 
 mafsof ufeful truth which might have been 
 afforded during the courfe of feveral centu- 
 ries; if, inftead of endeavouring to form 
 the metals, the operations of chemifts had 
 been confined to aijialyfing them, Amplify- 
 ing the means of extrafling them, com- 
 bining them together, working them, and 
 multiplying and reflifying their ufes. 
 
 The rage for makinggold was fucceeded 
 
 by 
 
xvi Preliminary Difcourfe. 
 
 by the fedu&ive hope of prolonging lifeby 
 means of chemiftry. The perfuafion was 
 eafily admitted, that a fcience which affords 
 remedies for all diforders, might without 
 effort fucceed in affording a univerfal medi- 
 cine. T he relations which have been hand- 
 ed down to us of the long life of the an- 
 cients^ ppeared to be a natural effect of their 
 knowledge in chemiftry. The numerous 
 fables of antiquity obtained the favour of 
 being admitted among eftablifhed fa£ls ; 
 and the alchemifts, after having exhaufted 
 themfelves in the fearch after the philofo- 
 pher s ftone, appeared to redouble their 
 efforts to arrive at an obje£t ftill more 
 chimerical. At this period the elixirs of 
 life, the arcana, the polychreft medicines, 
 had their origin ; together with all thofe 
 monftrous preparations, of which a few 
 have been handed down even to our days. 
 
 The chimera of the univerfal medicine 
 agitated the minds of moft men in the fix- 
 teenth century ; and immortality was then 
 promifed with the fa me effrontery as a Char- 
 latan now announces his remedy for every 
 difeafe. The people are eaftly feduced’by 
 
 thefe 
 
/ 
 
 Preliminary Difcourfe. xvii 
 
 thefe ridiculous promifes ; but the man of 
 knowledge can never be led to think that 
 chemiftry can fucceed in reverfing that 
 general law of nature which condemns all 
 living beings to renovation, and a continual 
 circulation of decompofitions and fuccef- 
 five generations. This fe6i gradually be- 
 came an obje£t of contempt. The enthu- 
 liaft Paracelfus, who, after having flattered 
 himfelf with immortality, died at the age of 
 forty-eight at an inn at Saltfburg, com- 
 pleted its difgrace. From that moment the 
 fcattered remains of this fe£t united them- 
 felves, never more to appear again in public. 
 The light which began to Ihine forth on all 
 fides, rendered it neceflary that they fhould 
 have recourfe to fecrecy and obfcurity ; and 
 thus at length chemiftry became purified. 
 
 James Earner, Bohnius, Tachenius, 
 Kunckel, Boyle, Crollius, Glafer, Glauber, 
 Schroder, &c. appeared on the ruins of 
 thefe two fefts, to examine this indigefted 
 aggregate, and feparate from the confufed 
 mafs of phenomena, of truth and of error, 
 everything which could tend to enlighten 
 thefcience. The fecloftheadepts,urgedon 
 Vol. I. b by 
 
xviii Preliminary Difcourfe. 
 
 by the madnefs of immortality, had difeo* 
 vered many remedies ; and pharmacy and 
 the arts then became enriched with for- 
 mulae and compofitions, whofe operations 
 required only to be rectified, and their ap- 
 plications better eftimated. 
 
 Nearly at the fame time appeared the 
 celebrated Becher. He withdrew chemif- 
 try from the too narrow limits of pharmacy* 
 He {hewed its connection with all the phe- 
 nomena of nature ; and the theory of the 
 formation of metals, the phenomena offer- 
 mentation, the laws of putrefaction, were 
 all comprehended and developed by this 
 fuperior genius. Chemiftry was then di- 
 rected to its true object : and Stahl, who fuc- 
 ceeded Becher, reduced to certain general 
 principles all the fads with which his prede- 
 cefTor had enriched the fcience. He fpoke a 
 language lefs enigmatical ; he clafledallthe 
 faCis with order and method ; and purged 
 the fcience of that alchemic infeCtion, to 
 which Becher himfelf was too much at- 
 tached. But if we confider how great are 
 the claims of Stahl, and how few the addi- 
 tions which have been made to his doc- 
 trine 
 
Preliminary Difcourfe . xix 
 
 trine until the middle of this century, we 
 cannot but be aftoniftied at the fmall pro- 
 grefs of the fcience. When we confult the 
 labours of the chemifts who have appeared 
 fince the time of Stahl, we fee mod of them 
 chained down to the fteps of this great man, 
 blindly fubfcribing to all his ideas; and the 
 labour of thinking appeared no longer to 
 exift among them. Whenever a well-made 
 experiment threw a gleam of light unfa- 
 vourable to his doftrine, we fee them tor- 
 ment themfelves in a ridiculous manner to 
 formadelufive interpretation. Thus it was 
 that the increafe of weight which metals ac- 
 quire by calcination, though little favoura- 
 ble to theideaofthefubtraftionof aprinci- 
 pie without any other addition, was never- 
 thelefs incapable of injuring this doCtrine* 
 The almoft religious opinion which 
 enflaved all the chemifts to Stahl, has no 
 doubt been pernicious to the progrefs of 
 chemiftry. But the ftrong defire of redu- 
 cing every thing to firft principles, and of 
 eftablifhing a theory upon incomplete ex- 
 periments, or fa£ts imperfectly feen, did not 
 admit of the fmalleft obftacles. From the 
 b 2 moment 
 
xx Preliminary Difcourfe . 
 
 moment that analyfis had {hewn fome of 
 the principles of bodies, the chemift thought 
 himfelf in poffeflion of the firft agents of 
 nature. He confidered himfelf as autho- 
 rized to regard thofe bodies as elements 
 which appeared no longer fufceptible of be- 
 ing decompofed. The acids and the alka- 
 lis performed the principal part in natural 
 operations : and it appeared to be a truth 
 buried in oblivion, that the term where the 
 artift flops is not the point at which the 
 Creator has limited his power ; and that the 
 laft refult of analyfis does indeed mark the 
 limits of art, but does not fix thofe of na- 
 ture. We might likewife reproach certain 
 chemifts for having too long negle£ied the 
 operations of the living fyftems. They 
 confined themlelves in their laboratories, 
 itudied no bodies but in their lifelefs ftate, 
 and were incapable of acquiring any know- 
 ledge but fuch as was very incomplete : for 
 he who, in his refearches, has no other ob- 
 jecl in view than that of afcertaining the 
 principles of a fubllance, a£ls like a phyfi- 
 cian who (hould fuppofe he had acquired 
 a complete notion of the human body by 
 
 confining 
 
Pelimina ry Difcourfe. xxi 
 
 confining his ftudies to the dead carcafe. 
 But we muftlikewife obferve that, in order 
 to form a proper notion of the phenomena 
 of living bodies, it is neceflary to pofiefs 
 the means of confining the gafeous prin- 
 ciples which efcape from bodies ; and of 
 analyfing thefe volatile and invifible fub- 
 fiances which combine together. Now 
 this work was impoffible at that time ; and 
 we ought to beware of imputing to men 
 thofe errors which arife from the ftate of 
 the times in which they lived. 
 
 It may perhaps be demanded, on this oc- 
 cafion, why chemiftry was fooner known, 
 and more generally cultivated, in Germany 
 and in the North than in our kingdom. I 
 think that many reafons may be given for 
 this. In the firft place, the fcholars of Stahl 
 and of Becher mult have beenmore nume- 
 rous, and confequently their inftru&ion far- 
 ther extended. Secondly, the working of 
 mines having become a refource neceftary 
 to the governments of the North, has been 
 Angularly encouraged ; and that chemiftry 
 which enlightens mineralogy mult necef- 
 
 farily 
 
xxii Preliminary Dtfcourfe . 
 
 farily have participated in its encourage', 
 ments *. 
 
 The ftudy of chemiftry did not begin to 
 be cultivated to advantage in France until 
 the end of the laft century. The firft wars 
 of Louis XIV. fo proper to develop the 
 talents of the artift, the hiftorian, and the 
 military man, appeared little favourable to 
 
 * Since the French government has facilitated the 
 ftudy of mineralogy by the mod fuperb eftablifhments, 
 we have beheld the tafte for chemiftry revive, the arts 
 which have the working of metals for their objeCl have 
 been rendered more perfeCt, and the mines which have 
 been wrought are more numerous. Mr. Sage has been 
 more particularly afiiduous and zealous to turn the fa- 
 vour of government towards this objeCt. I have been a 
 witnefs to the laborious attention of this chemift to ef- 
 fect this revolution. I have beheld the perfonal facri- 
 fices he made to bring it forward. 1 have applauded 
 his zeal, his motives, and his talents. The fame fen- 
 timents (till occupy my mind ; and though I teach a 
 do&rine at prefen: which is different from his, this 
 circumftanee arifes from the impoffibiliiy of command- 
 ing opinions. The philofopher who is truly worthy of 
 this name, is capable of difunguifliing the friend of his 
 art from the (lave of his fyftem : and, in a w 7 ord, every 
 one ought to write according to his conviction ; the 
 molt ('acred axiom of the fciences being, “Amicus Plato, 
 fed magis arnica veritas.” 
 
 the 
 
Preliminary Difcourfe. xxiii 
 
 the peaceable ftudyof nature. The natu- 
 ralifl who in his refearches fees union and 
 harmony around him, cannot be an indif- 
 ferent fpe&ator of the continual fcenes of 
 diforder and deflru&ion ; and his genius is 
 crufhed in the midft of troubles and agita- 
 tions. The mind of the great Colbert, deep- 
 ly penetrated with thefe truths, quickly en- 
 deavoured to temper the fire of difcord, by 
 turning the minds of men towards the only 
 obje&s which could fecure the peace and 
 profperity of the ftate. He exerted himfelf 
 to render trade flourifhing : he eftablifhed 
 manufactories : learned men were invited 
 from all parts,encouraged, and united toge- 
 ther, to promote his vali projects. Then it 
 was that the ardour of enquiry replaced for 
 a time the fury of conqueft ; and France very 
 foon flood in competition with all nations 
 for the rapid progrefs of the fcience§, and 
 the perfe£lion of the arts. Lemery, Hom- 
 berg, and Geoffroy arofe nearly at the fame 
 time ; and other nations were no longer en- 
 titled to reproach us for the want of che- 
 mifts. From that moment the exiflence of 
 the arts appeared to be well affured. AH 
 
 the 
 
xxiv Preliminary Difcourfe . 
 
 the fciences which afford their firft prin- 
 ciples, were cultivated with thegreateft fuc- 
 cefs: and it will lcarcely be credited that, 
 in the fpace of a few years, the arts were 
 drawn from a (late of non -entity; and car- 
 ried to fuch a degree of perfection, that 
 France, which had before received every 
 thing from foreign countries, became in pof- 
 feffion of the glory of fupplying its neigh- 
 bours with models and with merchandizes. 
 
 Chemiftry and natural hiftory, however, 
 at the beginning of this century, were culti- 
 vated only by a very fmall number of per- 
 fons ; and it was then thought that the 
 ftudy of thefe fciences ought to be confined 
 to the academies. But two men, whofe 
 names will be ever famous, have rendered 
 the tafte general under the reign of Louis 
 XV. The one poffeffed that noble Ipirit 
 which is a ftranger to the power of preju- 
 dice, that indefatigable ardour which foea- 
 fily overcomes every obfiacle, that opennefs 
 of character which infpires confidence, and 
 transfufed into the minds of his pupils that 
 enthufiafm of which he himfelf felt the force. 
 “While Rouelle enlightened the fcience of 
 
 chemiftry, 
 
XXV 
 
 Preliminary Difcourfe. 
 
 4 # 
 
 chemiftry, Buffon prepared a revolution 
 Hill more aftomfhing in natural hiftory. 
 The naturalifts of the North hadfucceeded 
 in caufing their productions to be read by 
 a fmall number of the learned; but the 
 works of the French naturalift were foon, 
 like thofe of nature, in the hands of the 
 whole world. He poflefled the art of dif- 
 fufing through his writings that lively in- 
 tereft, that enchanting colouring, and that 
 delicate and vigorous touch, which influ- 
 ence, attach, and fubdue the mind. The 
 profundity of his reafoning is every where 
 united to ail that agreeable illufion which 
 the moft brilliant imagination can furnifh. 
 The facred fire of genius animates all his 
 produ&ions ; his fyftems conftantly exhibit 
 the moft fublime profpeCts in their totality, 
 and the moft perfeCt correfpondence m their 
 minute parts ; and, even when he exhibits 
 mere hypothefes, we are inclined to per- 
 fuade ourfeives that they are eftablifhed 
 truths. We become like the artift who, 
 after having admired a beautiful ftatue, 
 ufed his efforts to perfuade himfelf that it 
 refpired, and removed every thing which 
 
 could 
 
xxvi Preliminary Difeourfe . 
 
 could difTipate his illufion. We take up 
 his work with a pleafure refembling that of 
 the man who turns again to deep, in hopes 
 of prolonging the deception of an agreea- 
 ble dream. 
 
 Thefe two celebrated men, by diffufmg 
 the tafte for chemiftry and natural hiftory, 
 by making their relations and ufes better 
 known, conciliated the favour of govern- 
 ment towards them; and from that mo- 
 ment every one interefted himfelf in the 
 progrefs of both fciences. Thofe perfons 
 who were bed qualified in the kingdom, 
 haftened to promote the revolution which 
 was preparing. The fciences foon inferibed 
 in their lift of cultivators the beloved and 
 refpefted names of La Rochefoucault, 
 A)en, Chaulnes, Lauraguais, Malefherve, 
 &c. ; and thefe men, diftinguifhed by their 
 birth, were honoured with a new fpecies of 
 glory, which is independent of chance or 
 prejudice. They enriched chemiftry with 
 their difeoveries, and aflbeiated their names 
 with all the other literati who purfued the 
 lame career. They revived in the mind of 
 the chemift that paftion for glory, and that 
 
 ardour 
 
Preliminary Difcourfe. xxvii 
 
 ardour for the public good, which conti- 
 nually excite new effort ; The man of am- 
 bition and intrigue no longer endeavoured 
 to deprefs the modeft and timid man of ge- 
 nius. The credit of men in place ferved as 
 a defence and fupport againft calumny and 
 perfecution. Recompenfes were affigned 
 to merit. Learned men were difpatched in- 
 to all parts of the world, to ftudy the arts, 
 and colleft their produftions. Men of the 
 firft merit were invited to infiru£l us with 
 regard to our own proper riches ; and efta- 
 blifhments of chemiftry which were made 
 in the principal towns of the kingdom, dif- 
 fufed the tafte for this fcience, and fixed 
 among us thofe arts which we might in vain 
 have attempted to naturalize, if a firm bafis 
 had not been firft laid. The profeffors 
 eflablifhed in the capital, and in the pro- 
 vinces, appeared to be placed between the 
 academies and the people, to prepare the 
 latter for thofe truths which flow from fuch 
 refpe&able aflociations. We may confider 
 them as a medium which refrafts and mo- 
 difies the rays of light that iffue from thofe 
 various luminous centres ; and directs them 
 
 towards 
 
xxviii 'Preliminary Difcourfe. 
 
 i 
 
 towards the manufa&ories, to enlighten 
 and improve their pra6tice. Without thefe 
 favours, without this confideration and 
 thefe recompenfes, could it have been ex- 
 petled that the moft unaftuming among 
 philofophers would have exerted himfelf 
 to promote the reputation of a people to 
 whom he was unknown ? Could a man fo 
 fituated reafonably hope to fucceed in car- 
 rying a difcovery into effeft ? Is it proba- 
 ble that he fhould have poffefled a fuffici- 
 ent fortune to work in the large way, and 
 by this means alone to overcome the num- 
 berlefs prejudices which banifh men of 
 fcience from manufaflories ? The contem- 
 plative fciences demand of the fovereign 
 repofe and liberty only; but experimental 
 fciences demand more, for they require af- 
 fiftance and encouragement. What indeed 
 could be hoped in thofe barbarous ages, 
 wherein the chemift fcarcely durft avow 
 the nature of the occupation which in fe- 
 cret conftituted his greatefl pleafure? The 
 title of Chemift was almoft a reproach : 
 and the prejudice which confounded the 
 profeffors of this fcience with fuch wretch- 
 
Preliminary Difcourfe . xxix 
 
 ed proje&ors as are entitled only to pity, 
 has probably kept back the revival of the 
 arts for feveral centuries; for chemiftry 
 alone can afford them a proper bafis. If the 
 princes of paft times had been friends of the 
 arts, and jealous to acquire a pure and du- 
 rable reputation; if they had been careful 
 to honour the learned, to colled their va- 
 luable labours, and to tranfmit to us with- 
 out alteration the precious annals of human 
 genius; we fhould have been difpenfed 
 from labouring among the rubbifh of early 
 times, to confult a few of thofe remains 
 which have efcaped the general wreck ; and 
 we fhould have been fpared the regret of 
 allowing, after many ufeful refearches, that 
 the mafter-pieces of antiquity which re- 
 main anfwer fcarcely any other purpofe 
 than to give us an idea of that fuperiority 
 to which the earlier nations had arrived. 
 Time, the fword, fire, and prejudice have 
 devoured all ; and our refearches ferve 
 only to add to our regret for the Ioffes 
 which the world has fuftained. 
 
 The fcience of chemiftry poffeffes the 
 glory,, in our days, not only of having ob- 
 tained 
 
xxx Preliminary Difeourfe. 
 
 tained the prote&ion of government, but it 
 may likewife boafl of another equally ele- 
 vated. This fcience has fixed the attention, 
 and formed the occupation, of various men 
 in whom the habit of a profound ftudy of 
 the accurate fciences had produced a ne- 
 ceflity of admitting nothing but what is 
 proved, and of attaching themfelves only 
 to fuch branches of knowledge as are fuf- 
 ceptible of ft rift proof. Meffrs. De la 
 Grange, Condorcet, Vander Monde, 
 Monge, De la Place, Meufnier, Coufin, 
 the mod celebrated mathematicians of 
 Europe, are all interefted in the progrefs 
 of this fcience, and molt of them daily add 
 to its progrefs by their difeoveries. 
 
 So great a mals of inftru£tioi>, and fuch 
 ample encouragement, could not but effedt 
 a revolution in the fcience itfelf ; and we 
 are indebted to the combined efforts of all 
 thefe learned men for the difeovery of fe- 
 veral metals, the creation of various ufe- 
 ful arts, the knowledge of a number of ad- 
 vantageous proceffes, the working of fe^ 
 veral mines, the analyfis of the gafes, the 
 decompofition of water, the theory of heat, 
 
 the 
 
Preliminary Difeourfe. xxxi 
 
 the do&rine of combuflion ; and a mafs of 
 knowledge fo abfolute and fo extended, re- 
 fpefting all the phenomena of art and of 
 nature, that in a very fhort time chemiftry 
 has become a fcience entirely new. We 
 might now fay with much more truth what 
 the celebrated. Bacon affirmed of the che- 
 miftry of his time: “ A new philofophy,” 
 fays he, “ has iffued from the furnaces of 
 “ the chemifts, which has confounded all 
 “ the reafonings of the ancients.” 
 
 But while difeoveries became infinitely 
 multiplied in chemiftry, the neceffity of re- 
 medying the confufion which had fo long 
 prevailed, was foon feen, and indicated the 
 want of a reform in the language of this 
 fcience. There is fo intimate a relation be- 
 tween words and fa£ls, that the revolution 
 which takes place in the principles of a 
 fcience ought to be attended with a fimilar 
 revolution in its language: and it is no 
 more poffible to preferve a vicious nomen- 
 clature with a fcience which becomes en- 
 lightened, extended, and Amplified, than 
 to polifh, civilize, and inftrufl uninformed 
 man without making any change in his na- 
 tural 
 
xxxii Preliminary Difcourfe. 
 
 tural language. Every chemid who wrote 
 on any fubje£t was (truck with the inaccu- 
 racy of the words in common ufe, and con- 
 fidered himfelf as authorized to introduce 
 fome change ; infomuch that the chemical 
 language became infenfibly longer, more 
 confufed, and more unpleafant. Thus the 
 carbonic acid has been known, during the 
 courfe of a few years, under the names of 
 Fixed Air, Aerial Acid, Mephitic Acid, 
 Cretaceous Acid, &c. ; and our poderity 
 may hereafter difpute whether thefe various 
 denominations were not applied to different 
 fubdances. The time was therefore come 
 in which it was neceffary to reform the 
 language of chemidry: the imperfeftions 
 of the ancient nomenclature, and the dif- 
 covery of many new fubdances, rendered 
 this revolution indifpenfable. But it was 
 neceffary to defend this revolution from the 
 caprice and fancy of a few individuals; it 
 was neceffary to edablifh this new lan- 
 guage upon invariable principles; and the 
 only means of infuring this purpofe was 
 doubtlefs that of erefting a tribunal in 
 which chemids of acknowledged merit 
 
 fhould 
 
Preliminary Difcourfe . xxxiii 
 
 fhould difcufs the words received without 
 prejudice and without intereft; in which 
 the principles of a new nomenclature might 
 be eftablilhed and purified by the fevered 
 logic; and in which the language fhould 
 be fc> well identified with the fcience, the 
 word fo well applied to the fadi, that the 
 knowledge of the one fhould lead to the 
 knowledge of the other. This was exe- 
 cuted in 1788 by Meffrs. De Morveau, 
 Lavoifier, Berthollet, and De Fourcroy. 
 
 In order to eftablifh a fyftem of nomen- 
 clature, bodies muff be confidered in two 
 different points of view, and diftributed in- 
 to two claffes; namely, the clafs of fimple 
 fubftances reputed to be elementary, and 
 the clafs of combined fubftances. 
 
 1. The moft natural and liiitable deno- 
 minations which can be affigned to fimple 
 fubftances, muft be deduced from a princi- 
 pal and charadteriftic property of the fub- 
 ftance intended to be expreffed. They may 
 likewife be diftinguiftred by words which 
 do not prefent any precife idea to the mind. 
 Moft of the received names are eftablifhed 
 on this laft principle, fuch as the names 
 
 Vol.L g Sulphur, 
 
xxxiv Preliminary Difcourfe • 
 
 Sulphur, Phofphorus,which do not convey 
 any fignification in our language, and pro- 
 duce in our minds determinate ideas only, 
 becaufe ufage has applied them to known 
 fubftances. Thefe words, rendered facred 
 by ufe, ought to be preferved in a new no- 
 menclature ; and no change ought to be 
 made, excepting when it is propofed to 
 reftify vicious denominations. In this cafe 
 the authors of the New Nomenclature have 
 thought it proper to deduce the denomina- 
 tion from the principal charafteriftic pro- 
 perty of the fubflance. Thus, pure air 
 might have been called Vital Air, Fire Air, 
 or Oxigenous Gas ; becaufe it is the bafis 
 of acids, and the aliment of refpiration and 
 combuft ion. But it appears to me that this 
 principle has been in a fmall degree depart- 
 ed from when the name of Azotic Gas was 
 given to the atmofpherical mephitis — l. 
 Becaufe, none of the known gafeous fub- 
 fiances excepting vital air being proper for 
 refpiration, the word Azote agrees with 
 every one of them except one; and confe- 
 quently this denomination is not founded 
 upon an exclufive property, diftin£tive and 
 
 cha- 
 
XXXV 
 
 Preliminary Pifcourfe, 
 
 charafteriftic of the gas itfelf. 2. This de- 
 nomination being once introduced, the ni- 
 tric acid ought to have been called Azotic 
 Acid, and its combinations Azotates ; be- 
 caufe the acids are propofed to be denoted 
 by the name which belongs to their radical. 
 3. If the denomination of Azotic Gas does 
 not agree with this aeriform fubftance, the 
 name of Azote agrees ftill lefs with the 
 concrete and fixed fubftance ; for in this 
 ftate all the gafes are effentially azotes. It 
 appears to me therefore that the denomina- 
 tion of Azotic Gas is not eftablifhed accord- 
 ing to the principles which have been 
 adopted; and that the names given to the 
 feveral fubftances of which this gas confti- 
 tutes one of the elements, are equally re- 
 movedfrom the principles of the Nomen- 
 clature. In order to corre£l the Nomen- 
 clature on this head, nothing more is ne- 
 ceflary than to fubftitute to this word a da- 
 nomination which is derived from the ge- 
 neral fyftem made ufe of; and I have pre- 
 fumed to propofe that of Nitrogene Gas. 
 In the firft place, it is deduced from the 
 chara£leriftic and exclufive property of 
 c 2 this 
 
xxxvi Preliminary Difcourfe. 
 
 this gas, which forms the radical of the ni- 
 tric acid. By this means we fhall preferve 
 to the combinations of this fubflance the 
 received denominations, fuch as thofe of 
 the Nitric Acid, Nitrates, Nitrites, &c. 
 In this manner the word which is afforded 
 by the principles adopted by the celebra- 
 ted authors of the Nomenclature, caufes 
 every thing to return into the order pro- 
 pofed to be eflablifhed. 
 
 2. The method made ufe of to afcertain 
 the denominations fuitable to compound 
 fubftances, appears to me to be fimple and 
 accurate. It has been thought that the lan- 
 guage of this part of fcience ought to pre- 
 fent the analyfes ; that the words fhould be 
 only the exprefnon of fafts; and that con- 
 fequently the denomination applied by a 
 chemift to any fubftance which has been 
 analyfed, ought to render him acquainted 
 with its conflituent parts. By following 
 this method, the Nomenclature is as it were 
 united, and identified with the fcience ; 
 and fatts and words agree together. Two 
 things are therefore united, which until 
 this time appeared to have no mutual re- 
 lation. 
 
Preliminary Difcourfe .. xxxvii 
 
 lation, the word, and the fubftance which 
 it reprefented ; and by this means the itudy 
 of chemiftry is hmplified. But when we 
 apply thefe inconteftable principles to the 
 various objefts of chemiftry, .we ought to 
 follow the analyfis ftep by ftep, and upon 
 this ground alone eftablifh general and in- 
 dividual denominations. We ought to ob- 
 ferve, that it is from this analytical method 
 that the various denominations have been 
 afligned, and that the methodical diftribu- 
 tibns of natural hiftory have been at all 
 times made. If man were to open his eyes 
 for the firft time upon the various beings 
 which people or compofe this globe, he 
 would eftablifh their relation upon the com- 
 parifon of their moll evident properties, and 
 no doubt would found his firft divifions 
 upon the moll fenfible differences. The 
 various modes of exiftence, or their feverai 
 degrees of confidence, would form his firft 
 divifion ; and he would arrange them under 
 the heads of folid, liquid, or aeriform bo- 
 dies. A more profound examination, and 
 a more connected analyfis of the individu- 
 als, would foon convince him that the fub- 
 
 ftances 
 
xxxviii Preliminary Difcourfe . 
 
 fiances which certain general relations had 
 induced him to unite in the fame clafs, un- 
 der a generic denomination, differed very 
 effentially among each other, and that the fe 
 differences neceffarily required fubdivi- 
 fions. Hence he would divide his folid bo- 
 dies into ftones, metals, vegetable fubftan- 
 ces, animal fuftances, &c. ; his liquids 
 would be divided into water, vital air, in- 
 flammable air, mephitic air, &c. When he 
 proceeded to carry his refearches on the na- 
 ture of thefe fubftances ftill farther, he 
 would perceive that moft of the individuals 
 were formed by the union of Ample princi- 
 ples ; and here it is that his applications of 
 the fy ftem to be followed, in affigning a fuit- 
 able denomination to eachfubftance, would 
 begin. To anfwer this purpofe, the authors 
 of the New Nomenclature have endeavour- 
 ed to exhibit denominations which may 
 point out the conftituent principles. This 
 admirable plan has been carried into exe- 
 cution as far as relates to fubftances which 
 are not very complicated, fuch as the com- 
 binations of the principles with each other; 
 the acids, earths, metals, alkalis, See . And 
 
 this 
 
Preliminary Difcoutfe. xx.ax 
 
 this part of the Nomenclature appear, to 
 me to leave nothing more to be defired. 
 The explanation may be feen in the work 
 publifhed on this fubjeft by the authors, 
 and in the Elementary Treatife of Che- 
 miftry of Mr. Lavoifier. I (hall therefore 
 do nothing more in this place than prefent 
 a fketch of the method I have followed ; 
 taking for example the combinations of 
 acids, which form the mod numerous clafs 
 of compounds. 
 
 The firft ftep confifted in comprehend- 
 ing under a general denomination the com- 
 bination of an acid with any given bafis ; 
 and in order to obferve a more exa6i ar- 
 rangement, and at the fame time to alhft 
 the memory, one common termination 
 has been given to all words which denote 
 the combination of an acid. Hence the 
 words Sulphates, Nitrates, Muriates, are 
 ufed to denote combinations of the ful- 
 phuric, nitric, and muriatic acids. The 
 kind of combination is denoted by adding 
 to the generic word the name of the body 
 which is combined with the acid; thus, 
 the fulphate of pot-alb expreffes the com- 
 bination 
 
xl * Preliminary Difcourfe. 
 
 bination of the fulphuric acid with pot- 
 
 afli. 
 
 The modifications of thefe fame acids, 
 dependent on the proportions of their 
 confiituent' principles; form 1 falts different 
 from thofe we have juft fpoken of ; and 
 the authors of the New Nomenclature 
 have exprefled the modifications of the 
 acids by the termination of the generic 
 word. The difference in the acids arifes 
 almoft always from the greater or lefs 
 abundance of oxigene. In the firft cafe, 
 the acid affumes the epithet of Oxigenated ; 
 hence the oxigenated muriatic acid, the 
 oxigenated fulphuric acid, &c. In the fe- 
 cond cafe, the termination of the word 
 which denotes the acid, ends in ous ; hence 
 the fulphureous acid, the nitrous acid, &c. 
 The combinations of thefe laft form ful- 
 phites, nitrites, &c. ; the combinations of 
 the former compofe oxigenated muriates, 
 oxigenated fulohates, &c. 
 
 The combinations of the various bodies 
 which compofe this globe are not all as fim- 
 pie as thofe here mentioned ; and it may 
 be immediately perceived how* long and 
 
 trouble- 
 
• Preliminary Difcourfe . xli 
 
 troublefome the denominations would be, 
 if attempts were made to beftow a Angle 
 denomination which fhould' denote the 
 conffituent principles of a body formed by 
 the union of five or fix principles. In this 
 cafe, the preference has been given to the 
 received appellation, and no other changes 
 have been admitted but fuch as were ne- 
 ceffary in order to fubftitute proper appel- 
 lations inftead of thofe which afforded no- 
 tions contrary to the nature of the objefts 
 they were applied to. 
 
 I have adopted this Nofrienclature in my 
 le&ures, and in my writings ; and I have 
 not failed to perceive how very advantage- 
 ous it is to the teacher, how much it re- 
 lieves the memory, how greatly it tends to 
 produce a tafte for chemiff ry, and with 
 -what facility and precifion the ideas and 
 principles concerning the nature of bodies 
 fix themfelves in the minds of the auditors. 
 But I have been careful to infert the tech- 
 nical terms ufed in the arts, or received in 
 fociety, together with thefe two denomina- 
 tions. I am of opinion that, as it is impof- 
 fible to change the language of the people, 
 
 it 
 
xlii Preliminary Difcourfe. 
 
 it is neceffary to defcend to them, and by 
 that means render them partakers of our 
 difeoveries. We fee, for example, that the 
 artift is acquainted with the fulphuric acid 
 by no other name than that of Oil of Vi- 
 triol, though the name of the Vitriolic Acid 
 has been the language of chemifts for a 
 . century paft. We cannot hope to be more 
 happy in thisrefpeft than our predeceflors; 
 and, fo far from feparating ourfelves from 
 the artift by a peculiar language, it is pro- 
 per that we fhould multiply the occafions 
 of bringing us together ; fo far from at- 
 tempting to enflave him by our language, 
 we ought rather to infpire his confidence 
 by learning his terms. Let us prove to the 
 artift that our relations with him are more 
 extended than he imagines ; and let us by 
 this intimacy eftablifh mutual correfpond- 
 ence, and a concurrence of information, 
 which cannot but redound to the advan- 
 tage of the arts and of chemiftry. 
 
 After having explained the principal ob- 
 j eft ions which have retarded the improve- 
 ment of chemiftry, and the caufes which 
 in our time have accelerated its progrefs, 
 
 we 
 
Preliminary Difcourfe. xliii 
 
 we (hall endeavour to point out the prin- 
 cipal applications of this fcience ; in which 
 attempt, we think, we (hah fucceed beft 
 by calling a general retrofpeti: over thofe 
 arts and fcences which receive certain 
 principles from it. 
 
 Mofl of the arts are indebted to accident 
 for their difcovery. They are in general 
 neither the fruit of refearch, nor the re- 
 fult of combination, but all of them have 
 a more orlefs evident relation tochemiftry. 
 This fcience therefore is capable of clear- 
 ing up their firft principles, reforming 
 their abufes, Amplifying their operations, 
 and accelerating their progrefs. 
 
 Chemiflry bears the fame relation to 
 moft of the arts, as the mathematics have 
 to the feveral parts of fcience which de- 
 pend on their principles. It is pofhble, no 
 doubt, that works of mechanifrn may be 
 executed by one who is no mathematician • 
 and fo likewife it is polfible to dye a beau- 
 tiful fcarlet without being a chemift : but 
 the operations of the mechanic, and of 
 the dyer, are not the lefs founded upon in- 
 variable 
 
xliv Preliminary Difcourfe . 
 
 variable principles, the knowledge of which 
 would be of infinite utility to the artift. 
 
 We continually hear in manufactories of 
 the caprices and uncertainty of operations ; 
 but it appears to me that this vague expref- 
 fion owes its birth to the ignorance of the 
 workmen with regard to thetrue principles 
 of their art. For nature itfelf does not aCl 
 with determination and difcernment, but 
 obeys invariable laws ; and the inanimate 
 fubftance which we make ufe of in our 
 manufactures, exhibits neceflary effeCts, in 
 which the will has no part, and confequent- 
 ly in which caprices cannot take place. 
 Render yourfelves better acquainted with 
 the materials you work upon, we might fay 
 to the artifis ; ftudy more intimately the 
 principles of your art; and you will be able 
 to forefee, to predict, and to calculate 
 every effeCt. It is your ignorance alone 
 which renders your operations a continual 
 feries of trials, and a difcouraging alterna- 
 tive of fuccefs and difappointment. 
 
 The public, which continually exclaims 
 that experience is better than fcience, en- 
 courages and fupports this ignorance on the 
 
 part 
 
Preliminary Difcourje . xlv 
 
 part of the artift; and it will not be remote 
 from our objeft to attempt to afcertain the 
 true value of thefe terms. It is very true, 
 for example, thataman whohashad avery 
 long experience may perform operations 
 with exaftnefs ; but he will always be con- 
 fined to the mere manipulation. I would 
 compare fuch a man to a blind perfon who 
 is acquainted with the road, and can pafs 
 along it with eafe, and perhaps even with 
 the confidence and affuranceof a man who 
 fees perfeftly well ; but is at the fame time 
 incapable of avoiding accidental obftacles, 
 incapable of (hortening his way or taking 
 the moll direft courfe,andincapabIeofiay- 
 ingdown any rules which he can communi- 
 cate to others. This is the ftate of the artift 
 of mere experience : however long the du- 
 ration of his practice may have been, as 
 the fimple performer of operations. 
 
 It may perhaps be repl ied, that artifts have 
 made very important difcoveries in confe- 
 quenceof afliduous labour. This is indeed 
 true, but the examples are very fcarce; and 
 we have no right to conclude, becaufe we 
 have feen men of genius without any ma- 
 thematical 
 
xlvi Preliminary Difoourfe . 
 
 thematical theory execute wonderful works 
 of mechanifm, that the mathematicsarenot 
 the bafis of mechanics, cr that any one has 
 a right to expeft to become a great mecha- 
 nic without a profound ftudy of mathe- 
 matical principles. 
 
 It appears to be generally admitted at pre- 
 fent, that chemiftry is the bafis of the arts : 
 but the artift will not derive from chemiftry 
 all the advantages he has a right to expeft, 
 until he has broken through that powerful 
 barrier which fufpicion, felf-love, and pre- 
 judice have raifed between the chemift 
 and himfelf. Such philofophers as have 
 attempted to pafs this line, have frequent- 
 ly been repelled as dangerous innovators; 
 and prejudice, which reigns defpotically 
 in manufa&ories, has not even permitted 
 it to be thought that the procefles were 
 capable of improvement. 
 
 It is eafy to fhew the advantages which 
 the arts might obtain from chemiftry, by 
 calling a retrofpefl over its applications 
 to each of them in particular. 
 
 1. It appears, from the writings of G> 
 lumella, that the ancients poffeffed a conft- 
 
 derable 
 
Preliminary Difcourfe. xlvii 
 
 derable extent of knowledge refpe&ing 
 agriculture, which was at that time con- 
 fidered as the firlt and nobleft occupation 
 of man. But when once the obje£ts of 
 luxury prevailed over thofe of neceffity, the 
 cultivation of the ground was left to the 
 mere fucceffion of praftice, and this firll of 
 the arts became degraded by prejudices. 
 
 Agriculture is more intimately connected 
 with chemiftry than isufuallyfuppofed. It 
 mull be admitted thatevery man is capable 
 of caufing ground to bear corn ; but what 
 a confi derable extent of knowledge is necef- 
 fary to caufe it to produce the greateft pof- 
 fible quantity ! It is not enough, for this 
 purpofe, to divide, to cultivate, and to ma- 
 nure any piece of ground: a mixture is like- 
 wife required of earthy principles fo well 
 afforted, that it may afford a proper nourifh- 
 ment ; permit the roots to extend themfel ves 
 to a diftance, in order to draw up the nutri- 
 tive juices; give the item a fixed bafe; re- 
 ceive, retain, and afford upon occafion, the 
 aqueous principle, withoutwhich no vege- 
 tation can be formed. It is therefore ef- 
 fential to afcertain the nature of the earth, 
 
 the 
 
xlviii Preliminary Difcourfe . 
 
 the avidity with which it feizes water, its 
 force of retaining it, &t\; and thefe requi- 
 res point to fludies which will afford prin- 
 ciples not to be obtained by mere practice 
 but flowly and imperfectly. 
 
 Every grain requires a peculiar earth. 
 Barley vegetates freely among the dry re- 
 mains of granite ; wheat grows in calca- 
 reous earth, &c. And how can it be pof- 
 lible to naturalize foreign products, with- 
 out a fufficient flock of knowledge to f up- 
 ply them with an earth fimilar to that 
 which is natural to them ? 
 
 The diforders of grain and forage, and 
 the deftruQion of the infefts which devour 
 them, are objefls of natural hiflory and 
 chemiflry : and we have feen in our own 
 times the effential art of drying and pre- 
 ferving grain, and all thofe details which 
 are interefling in the preparation of bread, 
 carried by the labours of a few chemifls 
 to a degree of perfe&ion which feemed 
 difficult to have been attained. 
 
 The art of difpofmg ftables in a proper 
 manner, that of choofing water adapted for 
 the drink of domeflic animals, the (economi- 
 cal 
 
Preliminary Difcourfe. xlix 
 
 cal proceffes for preparing and mixing their 
 food, the uncommon talent of fupplyinga 
 proper manure fuited to the nature of foils, 
 the knowledge neceflary to prevent or to 
 repair the effefts of blights — all come with- 
 in the province of Chemifiry ; and with- 
 out the afli fiance of this fcience our pro- 
 ceeding would be painful, flow, and un- 
 certain. 
 
 We may at prefent infift upon the ne- 
 ceflity of chemiftry in the various branches 
 of agriculture with fo much the more rea- 
 fon, as government does not ceafe to en- 
 courage this firft of arts by recompences, 
 diftinftions, and eftablifhments ; and the 
 views of the ftate are forwarded by the pro- 
 pofal of means to render this art flourith- 
 iftg. We fee, with the greateft fatisfaflion, 
 that by a happy return of reflection, we 
 begin to confider agriculture as the pureft, 
 the moll fruitful, and the mod natural 
 fource of our riches. Prejudices no lon- 
 ger tend to opprefs the hufbandman. Con- 
 tempt and fervitude are no longer the in- 
 heritance received for hisinceflant labours. 
 The mod ufeful and the mod virtuous 
 
 Vou I. d clafs 
 
1 Preliminary Difcourfe. 
 
 clafs of men is likewife that whofe date is 
 mod minutely corlfidered; and the culti- 
 vator of the ground in France is at lad 
 permitted to raife his hands in a date of 
 freedom to Heaven, in gratitude for this 
 happy revolution. 
 
 2. The working of mines is likewife 
 founded upon the principles of chemidry. 
 This fcience alone points out and direCts 
 the feries of operations to be made upon 
 a metal, from the moment of its extraction 
 from the earth until it comes to be ufed in 
 the arts. 
 
 * i ..... * r 
 
 Before the chemical analyfis was appli- 
 ed to the examination of (tones, thefe Tub- 
 dances were all denoted by fuperficial 
 characters, fuch as colour, hardnefs, vo- 
 lume, weight, form, and the property q£ 
 giving fire with the deel. All thefe cife 
 cumdances had given rife to methods of 
 divifion in which every other property 
 W-as confounded; but the fuccefTive la- 
 bours of Pott, r Margraaff, Bergmann, 
 Scheele, Bayen, Dietrich, Kirwan, Lavoi- 
 fier, De Morveau, Achard, Sage, Ber- 
 thollett, Gerhard, Erhmann, Fourcroy, 
 
 Mongez, 
 
Preliminary Difcourfe li 
 
 Mongez, Klaproth, Crell, Pelletier, De la 
 Metherie, &c. by inftrufting us concern- 
 ing the conftituent principles of every 
 known ftone, have placed thefe fubftances 
 in their proper lituations, and have carried 
 this part of chemiftry to the fame degree 
 of precifion as that which we before pof- 
 feffed relpefting the neutral falts. 
 
 The natural hiftory of the mineral king- 
 dom, unaffifted by chemiftry, is a language 
 compofed of a few words, the knowledge 
 of which has acquired the name of Mine- 
 ralogift to many perfons. The words Cal- 
 careous Stone, Granite, Spar, Schorle, 
 Feld Spar* Schiftus, Mica, &c. alone com- 
 pofe the diftionary of feveral amateurs>of 
 natural hiftory ; but thedifpofition of thefe 
 fubftances in the bowels of the earth, their 
 refpeftive pofition in the compofition of 
 the globe, their formation and fucceftive 
 decompofnions, their ufes in the arts, and 
 the knowledge of their conftituent princi- 
 ples,, form a fcience which can be well 
 known and inveftigated by the chemift 
 only. : 
 
 It is neceffary therefore that mineralogy 
 d 2 ftiould 
 
lii 'Preliminary Difcourfe . 
 
 fhould be enlightened by the ftudy of che- 
 miftry ; and we may obferve that, fince 
 thefe two fciences have been united, the 
 labour of working mines has been Ampli- 
 fied, metallic ores have been wrought with 
 more intelligence, feveral new metallic fub- 
 ftances have been difcovered, individuals 
 have opened mines in the provinces'; and 
 we have become familiar with a fpecies of 
 induftry which leemed foreign, and almoft 
 incompatible with, our foil and our habits. 
 Steel and the other metals have received in 
 ourmanufa£tories that degree of perfe£tiort 
 which had till lately excited our admira- 
 tion, and humiliated our felf-love. The 
 fuperb manufacture of Creufot has no 
 equal in Europe. Molt of our works are 
 fupported by pit-coal ; and this new com- 
 buftible fubftance is fo much the more va- 
 luable, as it affords us time to repair our 
 exhaufted woods, and as it is found almoft 
 every where in thole barren foils which 
 repel the ploughihare, and prohibit every 
 other kind of induftry. The eternal grati- 
 tude of this country is therefore due to 
 Meffrs. Jars, Dietrich, Duhamel, Monet, 
 
 Genfanne, 
 
Preliminary Difcourfe . liii 
 
 Genfanne, &c. who firft brought us ac- 
 quainted with thefe true riches. The tafte 
 for mineralogy, which has diffufed itfelf 
 within our remembrance, has not a little 
 contributed to produce this revolution; 
 and it is in a great meafure owing to thofe 
 collediions of natural hiftory, againft which 
 fome perfons have fo much exclaimed, 
 that we are indebted for this general tafte. 
 Our cohesions have the fame relation to 
 natural hiftory, as books bear to literature 
 and the fciences. The cohesion frequent- 
 ly is nothing more than an objeSi of lux- 
 ury to the proprietor; but in this very cafe 
 it is a refource always open to the man 
 who is defirous of beholding, and inftrudt- 
 ing himlelf. It is an exemplar of the works 
 of nature, which may be confulted every 
 moment; and the chemift who runs over 
 all thefe produftions, and fubjecis them to 
 analyfes to afcertain their conftituent prin- 
 ciples, forms the precious chain which 
 unites nature and art. 
 
 3. While the chemift attends to the na- 
 ture of bodies, and endeavours to afcertain 
 their conftituent principles, the natural 
 
 philofopher 
 
liv Preliminary Difcourfe. 
 
 philofopher ftudies their external charac- 
 ters, and as it were their phyfiognomy. 
 The obje£I of the chemift ought therefore 
 to be united to that of the philofopher, 
 in order to acquire a complete idea of a 
 body. What in fa£t (hall we call Air or 
 Fire, without the inftru&ion of the che- 
 mifl? Fluids more or lefs comprefhble, 
 ponderous, and elafiic. What are the parr 
 ticulars of information which natural phi- 
 lofophy affords us concerning the nature 
 of folids? It teaches us to diftinguifh them 
 from each other, to calculate their weight, 
 to determine their figure, to afcertain their 
 ufes, &c. 
 
 If we caff our attention upon the nume- 
 rous particulars which chemiftry has lately 
 taught us refpefling air, water, and fire, we 
 fhall perceive how much the connexion of 
 thefe two fciences has been ftrengthened. 
 Before this revolution, natural philofophy 
 was reduced tq the fimple difplay of ma- 
 chines; and this coquetry, by giving it a 
 tranfient glare, would have impeded its 
 progrefs, if chemiflry had not reftored it 
 to its true deflmation. The celebrated 
 
 chancellor 
 
Preliminary Difcourfe. * Iv 
 
 chancellor Bacon compared the natural 
 magic, or experimental philofophy, of his 
 time, to a magazine in which a few rich 
 and valuable moveables were found among 
 a heap of toys. The curious, fays he, is 
 exhibited inftead of the ufeful. What 
 more is required to draw the attention of 
 great men, and to form that tranfient fa- 
 fhion of the day which ends in contempt? 
 
 The natural philofophy of our days no 
 longer deferves the reproaches of this ce- 
 lebrated phiiofopher. It is a fcience 
 founded on two bafes equally foiid. On 
 the one part, it depends on mathematical 
 fcience for its principles ; and, on the other, 
 it refts upon chemiftry. The natural phi- 
 iofopher will attend equally to both fci- 
 ences. 
 
 The ftudy of chemiftry, in certain de- 
 partments, is fo intimately connected with 
 that of natural philofophy, that they are 
 infeparable; as, for example, in refearches 
 concerning air, water, fire, &c. Thefe 
 fciences very advantageoufly aftift each 
 other in other refpefts ; and while the 
 chemift clears minerals from the foreign 
 
 bodies 
 
lvi Preliminary Difcourfc. 
 
 bodies which are combined with them, the 
 philofopher fupplies the mechanical appa- 
 ratus neceffary for exploring them. Che- 
 miftry is inleparable from natural philo- 
 fophy, even in fuch parts as appear the 
 mod independent of it; fuch, for examr 
 pie, as optics, where the natural philofo^ 
 pher can make no progrefs but in propor- 
 tion as the chemift (hall bring his glafs to 
 perfeftion. 
 
 The connexion between thefe two fci- 
 ences is fo intimate, that it is difficult to 
 draw a line of diftinftion between them. 
 If we confine natural philofophy to enqui- 
 ries relative to the external properties of 
 bodies, we fhall afford no other objeft but 
 the mere outfide of things. If we reftrain 
 the chemift to the mere analvfis, he will at 
 mod arrive at the knowledge of the con- 
 ftituent principles of bodies, and will be 
 ignorant of their fun&ions. Thefe diftinc- 
 tions in a fcience which has but one com- 
 mon purpofe, namely the complete know- 
 ledge of bodies, cannot longer exift ; and 
 it appears to me that we ought abfolutely 
 to reject them in all obje£t$ which can only 
 
 be 
 
Preliminary Difcourfe . Ivii 
 
 be well examined by the union of natural 
 philofophy and cherniftry. 
 
 At the period of the revival of letters, it 
 was of advantage to feparate the learned, 
 as it were, upon the road to truth; and to 
 multiply the workfhops, if I may ufe the 
 expreflion, to haften the clearing away. 
 But at prefent, when the various points 
 are reunited, and the connection between 
 the whole is feen, thefe reparations, thefe 
 divifions, ought to be effaced; and we 
 may flatter ourfelves that, by uniting our 
 efforts, we may make a rapid progrefs in 
 the ftudyof nature. The meteors, and all 
 the phenomena of which the atmofphere 
 is the grand theatre, can be known only 
 by this re union. The decompofition of 
 water in the bowels of the earth, and its 
 formation in the fluid which furrounds us, 
 cannot but give rife to the moll happy and 
 the moll fublime applications. 
 
 4. The connexion between cherniftry 
 and pharmacy is fo intimate, that thefe two 
 fciences have long been confidered as one 
 and the fame; and cherniftry, fora long 
 time, was cultivated only by phyficians and 
 
 apothe- 
 
Iviii Preliminary Difcourfe . 
 
 apothecaries. It mud be allowed that, 
 though the chemiftry of the prefent day 
 is very different from pharmacy, which is 
 only an replication of the general princi- 
 ples of this fcience, thefe applications are 
 fo numerous, the clafs of perfons who cul- 
 tivate pharmacy is in general fo well in- 
 formed, that it is not at all to be wonder- 
 ed at, thatmoft apothecaries fhould endea- 
 vour to enlighten their proieffion by a fe- 
 rious ftudy of chemiftry, and by the hap- 
 pieft agreement unite the knowledge of 
 both parts of fcience. 
 
 The abufes which, at the beginning of 
 the prefent century, were made of the 
 applications of chemiftry to medicine, 
 have caufed the natural and intimate rela- 
 tions of this fcience with the art of heal- 
 ing to be miftaken. It would have been 
 more prudent, no doubt, to have reflified 
 its applications; but unfortunately we 
 have too much ground to reproach phy- 
 ficians for going to extremes. They have, 
 without reftrifition, banifhed that which 
 they before received without examination ; 
 and we have feen them fucceflively deprive 
 
 their 
 
Preliminary Difcourfe. lix 
 
 their art of all the a Alliance it might ob- 
 tain from the auxiliary fciences. 
 
 In order to direct with propriety the ap- 
 plications of cliemiltry to the human body, 
 proper views mult be adopted relating to 
 the animal economy, together with accu- 
 rate notions of chemillry itlelf. The re- 
 fu Its of the laboratory muft be confidered 
 as fubordmate to phyfiological obferva- 
 tions. We fhould endeavour to enlighten 
 the one by the other, and to admit no 
 truth as eftablifhcd which is contradifted 
 by any of thefe means of conviftion. It is 
 in confequence of a departure from thefe 
 principles that the human body has been 
 confidered as a lifelefs and paffive fub- 
 fiance ; and that the ftrift principles ob- 
 ferved in the operations of the laboratory 
 have been applied to this living fyftem. 
 
 In the mineral kingdom, every thing is 
 fubjected to the invariable laws of the affi- 
 nities. No interna! principle modifies the 
 aftion of natural agents ; and hence it 
 arifes that we are capable of foretelling, 
 producing, or modifying the effects. 
 
 In the vegetable kingdom, the aftion of 
 
 external 
 
lx Preliminary Difcourfe. 
 
 external agents is equally evident ; but 
 the internal organization modifies their ef- 
 fe&s, and the principal funClions of vege- 
 tables arile from the combined action of 
 external and internal caufes. It was no 
 doubt for this reafon that the Creator dif- 
 poled the principal organs of vegetation 
 upon the furface of the plant, in order 
 that the various funftions might at the 
 fame time receive the impreflions of ex* 
 ternal agents, and that of the internal 
 principle of the organization. 
 
 In animals, the functions are much lefs 
 dependant on external caufes ; and nature 
 has concealed the principal organs in the 
 internal part of their bodies, as if to with- 
 draw them from the influence of foreign 
 powers. But the more the fun&ions of an 
 individual are connefted with its organi- 
 zation, the lefs is the empire of chemiltry 
 over them ; and it becomes us to be cau- 
 tious in the application of this fcience to 
 all the phenomena which depend efienti- 
 ally upon the principles of life. 
 
 We muft not however confider chemif- 
 try as foreign to the ftudy and pra&iceof 
 
 medicine. 
 
Ixi 
 
 Preliminary Difcourje . 
 
 medicine. This fcience alone can teach 
 us the difficulty and art of combining re- 
 medies. This alone can teach us to apply 
 them with prudence and firmnefs. With- 
 out the affiftance of this fcience, the prac- 
 titioner would fcarcely venture to apply 
 thofe powerful remedies from which the 
 chemical phyfician knows the means of de- 
 riving fuch great advantage. Chemiftry 
 alone, in all probability, is capable of af- 
 fording means of combating epidemic dif- 
 orders, which in mpft cafes are caufed by an 
 alteration in the air, the water, or our food. 
 It will be only in confequence of analyfxs 
 that the true remedy can be found againft 
 thofe ftony concretions which form the 
 matter of the gout, the Hone, the rheuma- 
 tifm, &c. ; and the valuable particulars of 
 information which we now poflefs refpefcf- 
 ing refpiration, and the nature of the prin- 
 cipal humours of the human body, are like- 
 wife among the benefits arifing from this 
 fcience. 
 
 5. Chemiftry is not only of advantage to 
 agriculture, phyfic, mineralogy, and medi- 
 cine, but its phenomena are interefting to 
 
 all 
 
Ixii Preliminary Difcoiirfe. 
 
 all the orders of men: the applications of 
 this fcience are fo numerous, that. there are 
 few circumftances of life in which the che- 
 mift does not enjoy the pieafure of feeing 
 its principles exemplified. Molt of thofe 
 fatts which habit has led us to view with 
 indifference, are interefhng phenomena in 
 the eyes of the chernilt. Every thing in- 
 flrutts and amufes him ; nothing is indif- 
 ferent to him, becaufe nothing is foreign to 
 his purfuits ; and nature, no lefs beautiful 
 in her moft minute details than fublimein 
 the difpofition of her general laws, appears 
 to difplay the whole of her magnificence, 
 only to the eyes of the chemical philofo- 
 pher. 
 
 We might eafily form an idea of this 
 fcience, if it were polfibie to exhibit in this 
 place even a fketch of its principal appli- 
 cations* We fhould fee, for example, that 
 chemiftry affords us all the metals of which 
 the ufes are fo extenfive; that chemiftry af?/ 
 fords us the means of employing the parts 
 of animals and of plants for our ornament; 
 that our luxuries, and our fubfiftence, are 
 by this fcience eftablifhed as a tax upon all 
 
 created 
 
Preliminary Difcourfe .. Jxiii 
 
 created beings ; and ihat by this power we 
 are taught to fubject nature to our wants, 
 our talte, and even to our caprices. Fire, 
 that free independent element, has been 
 co!le£ted and governed by the indultry of 
 the chemift ; and this agent, deftined to 
 penetrate, to enliven, and to animate the 
 whole of nature, has in his hands become 
 the agent of death, and the prime minifter- 
 of deftruftion. The chemifts who in our 
 time have taught us to infulate that pure 
 air which alone is proper for combuftion, 
 have placed in our hands, as it were, the 
 very elfence of fire; and this element, 
 whofe effects were fo terrible, becomes the 
 agent of hill more terrible corifequences. 
 The atmofphere, which was formerly con- 
 fidered as a mafs of homogeneous fluid, is 
 now found to be a true chaos, from which 
 analyfis has obtained principles fo much 
 the more interefling to be known, as na- 
 ture has made them the principal agents of 
 her operations. We may confider this 
 mafs of fluid in which we live as a vaft la- 
 boratory, in which the meteors are pre- 
 pared, in which all the feeds of life and 
 
 of 
 
lxiv Preliminary Difcourjt . 
 
 of death are developed, from which nature 
 takes the elements of the compofition of 
 bodies, and to which their fubfequent de- 
 compofition returns the fame principles 
 which were before extracted. 
 
 Chemiftry, by informing us of the na- 
 ture and principles of bodies, inftructs us 
 perfe&ly concerning our relation to the ob- 
 jects around us. This fcience teaches us 5 
 as it were, to live with them ; and impreffes 
 a true life upon them, fince by this means 
 each body has its name, its charafter, its 
 ufes, and its influence, in the harmony 
 and arrangement of this univerfe. 
 
 The chemift, in the midft of thofe nu- 
 merous beings which the common race of 
 men accufe nature of having vainly placed 
 upon our globe, enjoys the profpeft as it 
 were in the centre of a fociety, all whofe 
 members are connefted together by in- 
 timate relations, and concur to promote 
 the general good. In his fight, every 
 thing is animated, every being performs a 
 part on this vaft theatre ; and the chemift 
 who participates in thefe intereftingfcenes, 
 is repaid with ufury for his firft exertions 
 
 to 
 
Preliminary Difcourfe. Jxv 
 
 to difcover the relations exifting between 
 them. 
 
 We may even confider this commerce, 
 or mutual relation between the chemift 
 and nature, as very proper to foften the 
 manners, and to imprefs on the charaXer 
 that freedom and firmnefs of principle fo 
 valuable in fociety. In the ftudy of na- 
 tural hiftory, no caufe ever prefents itfelf 
 to complain of inconftancy or treachery. 
 An attachment is eafily contracted for ob- 
 jects which afford enjoyment only ; and 
 thefe connexions are as pure as their ob- 
 jeX, as durable as nature, and ftronger in 
 proportion to the exertions which have 
 been required to eftablifh them. 
 
 From all thefe confiderations, there is no 
 fcience which more eminently deferves to 
 enter into the plan of a good education 
 than chemiftry. We may even affirm that 
 the ftudy of this fcience is aimoft indifpen- 
 fably neceffary to prevent us from being 
 flrangers in the midft of the beings arid 
 phenomena which furround us. It is true 
 indeed that the habit of beholding the ob- 
 jects of nature may produce a knowledge 
 
 Vol. I. e of 
 
 e 
 
Ixvi Preliminary Difcourfe. 
 
 of lome of their principal properties. We 
 may even in this way arrive at the theory 
 of fome of the phenomena. But nothing 
 is more proper to check the pretenfions of 
 young perfons who are elevated by fuch 
 imperfect acquifitions, than to (hew them 
 the vaft field of which they are ignorant. 
 The profound fentiment of their ignorance 
 will be feconded by the natural defire of 
 acquiring new knowledge. The wonder- 
 ful properties of the objects preferred to 
 them will en^a^e their attention. The in- 
 terefting nature of the phenomena will 
 tend to excite their curiofity. Accuracy 
 of experiment, and ftrifinefs of refult, 
 will form their reafoning powers, and ren- 
 der them fevere in their judgment. By 
 ftudying the properties of all the bodies 
 which furround him, the young fcholar 
 learns to know their relation with hirnlelf ; 
 and by fucceffively attending to all objects, 
 he extends the circle of his enjoyment by 
 new conquefts. He becomes a partaker in 
 the privileges of the Creator, by uniting 
 and difuniting, by compounding and de~ 
 ftroying. We might even affirm that the 
 
 Author 
 
Preliminary Difcourfe . Ixvii 
 
 Author of nature, referving to himfelf 
 alone the knowledge of his general laws, 
 has placed man between himfelf and mat- 
 ter, that it may receive thefe laws from his 
 hands, and that he may apply them with 
 proper modifications and reftriftions. In 
 this view, therefore, we may confider man 
 as greatly fuperior to the other beings which 
 compofe this living fyftem. They all fol- 
 low a monotonous and invariable procefs; 
 receive the laws, and fubmit to effebls 
 without modification. Man alone pof- 
 feffes the rare advantage of knowing a 
 part of thefe laws, of preparing events, of 
 predi£ling refults, of producing effefts at 
 pleafure, of removing whatever is noxious, 
 of appropriating whatever is beneficial, of 
 compofing fubftances which nature her- 
 felf never forms ; and, in this laft point of 
 view, himfelf a Creator, he appears to par- 
 take with the Supreme Being in the mod 
 eminent of his prerogatives. 
 
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 O F 
 
 CHEMISTRY. 
 
 PART THE FIRST. 
 
 • \ t , . . • r • • » 1 \ *1 r 
 
 CONCERNING THE CHEMICAL PRINCIPLES? 
 
 INTRODU CTION. 
 
 Definition of Chemiftry ; its Obje£l and 
 Means. — Defcription of a Laboratory, 
 and the principal Inftruments employ- 
 ed in chemical Operations, with a De- 
 finition of thole Operations. 
 
 X™™ \' r ' • r -* r 0 • • •’ 
 
 C HEMISTRY is a fcience, the objedt 
 of which is to afcertain the nature and 
 properties of bodies. 
 
 The methods ufed to obtain this knowledge 
 are reducible to two ; analyfis and fynthefis. 
 Vol. I. B The 
 
2 Laboratory . Furnaces . 
 
 The principal operations of chemiftry are 
 performed in a place called a Laboratory. 
 
 A laboratory ought to be extenfive and well 
 aired, in order to prevent dangerous vapours 
 from remaining, which are produced in fome 
 operations, or which may efcape by any un- 
 forefeen accident. It ought to be dry, becaufe 
 otherwife iron vefTels would ruft, and mod of 
 the chemical produces would be liable to 
 change. But the principal excellence of a la- 
 boratory confifts in its being furnifhed with ail 
 thofe inftruments which may be. employed in 
 the ftudy of the nature of bodies, and in en- 
 quiries refpe&ing their properties. 
 
 Among thefe inftruments there are fome 
 which are of general ufe, and applicable to 
 moft operations ; and there are others which 
 ferve only for peculiar ufes. This divifion im- 
 mediately points out that, at the prefent in- 
 ftant, we can only treat of the former, and that 
 we muft defcribe the others on fitch occafions 
 as will render it neceftary to treat of their ufes. 
 
 The chemical inftruments moft frequently 
 employed , are thofe which prefent themfelves 
 firft to view upon entering a laboratory ; 
 namely, the furnaces. 
 
 Thefe furnaces confift of earthen veflels ap- 
 propriated to the various operations performed 
 upon bodies by means of fire. 
 
 A proper 
 
The Evaporatory Furnace . 3 
 
 A proper mixture of fand and clay is com- 
 monly the material of which thefe veffels are 
 formed* It is difficult, and even impoffible, 
 to prefcribe and determine, according to any 
 invariable method, the proportions of thefe 
 conftituent parts ; becaufe they mu ft be varied 
 according to the nature of the earths made ufe 
 of. Habit and experience alone can furnifh 
 us with principles on this fubjedh 
 
 The feverai methods of applying fire to 
 fubftances under examination have occafioned 
 the conftruftion of furnaces in different forms, 
 which we fhall at prefent reduce to the three 
 following. 
 
 I. The evaporatory furnace. — This furnace 
 has received its name from its ufe. It is ufed 
 to reduce liquid fubftances into vapour by 
 means of heat, in order to feparate the more 
 fixed principles from thofe which are more 
 ponderous ; and were mixed, fufpended, com-* 
 pounded, or diffolved in the fluid. 
 
 The fire-place is covered by the evapora- 
 tory veffel. Two or three grooves, channels, 
 or depreffions are made in the fides of the 
 furnace, near its upper edge, to facilitate the 
 drawing of the fire. 
 
 The veffel which contains the fubftance to 
 be evaporated, is called the evaporatory veffel. 
 
 B 2 Thefe 
 
4 
 
 Chemical VeJJeh of Earth : 
 
 Thcfe veflels are formed of earth, glafs, or 
 metal. Veflels of unglazed earth are too po- 
 rous, infomuch that liquids filtrate through 
 their texture. Thofe of porcelain bifcuit are 
 likewife penetrable by liquids ftrongly heated, 
 and fuffer gafeous or aeriform fubftances to 
 efcape. The beautiful experiment of Mr. 
 D’Arcet upon the combuftion and deftrudlion 
 of the diamond, in balls of porcelain, are well 
 known, and tend to illuftrate this fubjedt. I 
 have confirmed thefe refults by experiments 
 in the large way, upon the diftillation of aqua* 
 fortis, which lofes as well in quality as quan- 
 tity when the procefs is carried on in veflels of 
 porcelain clay. 
 
 Glazed earthen veflels cannot be ufed when 
 the glafs confifts of the calces of lead or cop- 
 per ; becaufe thofe metallic matters are at- 
 tacked by acids, fats, oils, &c. Neither can 
 earthen veflels be ufed which are covered with 
 enamel, becaufe this kind of opake glafs is 
 almoft always full of fmall cracks through 
 which the liquid would introduce itfelf into 
 the body of the veflel. 
 
 Earthen veflels cannot therefore be ufed, 
 excepting in operations of little delicacy, in 
 which precifion and accuracy are not indif- 
 pcnfably required. 
 
 Evaporatory 
 
of Glafs , Copper , Lead, Tin , Cs?r. 5 
 Evaporatory veffels of glafs are in general 
 to be preferred, Thofe which refill the fire 
 better than any others, are prepared in the la- 
 boratory, by cutting a fphere of glafs or a 
 receiver into two equal parts with a red-hot 
 iron. The capfules which are made in the 
 glafs-houfe are thickeft at the bottom, and 
 confequently are more liable to break at that 
 part when expofed to the fire, 
 
 Evaporatory veflels of metal are ufedin ma. 
 nufadlories. Copper is moft commonly em- 
 ployed, becaufe it not only poflefles the pro-, 
 perty of refilling fire, but has a confiderable 
 degree of folidity, together with the facility of 
 being wrought. Alembics are made of this 
 metal, for the dillillation of vinous fpirits, and 
 aromatic fubllances ; as are alfo caldrons or 
 pots for cryllallization of certain falts, and 
 for feveral dyeing procelfes, &c. Lead is like- 
 wife of confiderable ufe, and is made choice of 
 whenever operations are to be performed upon 
 fubllances which contain the fulphuric acid, 
 fuch as the fulphates of alumine and of iron ; 
 and for the concentration and rectification of 
 the oils of vitriol. Tin veflels are alfo em- 
 ployed in fome operations : the fcarlet bath 
 affords a more beautiful colour in boilers of this 
 metal than in thofe of any other. Capitals of 
 
 tin 
 
6 
 
 Vtjfels for Evaporation . 
 
 tin have already begun to be fubftitoted in the 
 room of thofe of copper, in the con ftru (Sion of 
 alembics ; and by this means the feveral pro- 
 duces of diftillation are exempted from every 
 fufpicion of that dangerous metal. Boilers of 
 iron are likewife ufed for certain coarfe opera- 
 tions ; as for example, in the concentration of 
 the lixiviums of common fait, of nitre, &c. 
 
 Evaporatory veflels of gold, of ftlver, or of 
 platina, are to be preferred in fome delicate 
 operations ; but the price and fcarcity of thefe 
 veflels do not permit them to be ufed, efpe- 
 cially in the large way. 
 
 Moreover it is from the nature of the fub- 
 ftance to be evaporated, that we muft deter- 
 mine the choice of the veflel moft fuitable to 
 any operation. There is no particular kind of 
 veflels which can be adapted exclufively on all 
 occaflons. It may only be obferved, that glafs 
 prefents the greateft number of advantages, 
 becaufe it is compofed of a fubftance the leaft 
 attacked, the lead foluble, and the leaft de- 
 ftrudible by chemical agents. 
 
 Evaporatory veflels are known by the name 
 of capfules, cucurbits, &c. according to their 
 feveral forms. 
 
 Thefe veflels ought in general to be very 
 wide and ftiallow, in order that the diftil- 
 lation 
 
Application of Heat. Baths. 7 
 
 lation and evaporation may be fpeedy and 
 (economical. It is necelTary, 1. That the 
 evaporatory vefTel be not narrow at its upper 
 part. 2. That the heat be applied to the li- 
 quid in all parts, and equally. 3. That the 
 column or mafs of the liquid fhould have little 
 depth, and a large furface of evaporation. It 
 is upon thefe principles that I have conflrutft- 
 ed, in Languedoc, boilers proper for diflilling 
 brandy, which fave eleven-twelfths of the time, 
 and four-fifths of the combuftibles. 
 
 Evaporation may be performed in three- 
 manners. 1 . By a naked fire. 2. By the fand 
 bath. 3. By the water bath. 
 
 Evaporation is made by a naked fire, when 
 there is no fubflance interpofed between the 
 fire and the vefTel which contains the liquid 
 intended to be evaporated ; as, for example, 
 when water is boiled in a pot. 
 
 Evaporation is performed by the fand bath, 
 when a vefTel filled with fand is interpofed be- 
 tween the fire and the evaporatory vefTel. The 
 heat is in this cafe communicated more flowly 
 and gradually ; and the vefTels, which would 
 otherwife have been broken by the immediate 
 application of the heat, are enabled to refill 
 its force. The heat is at the fame time more 
 equally kept up; the refrigeration is moregra. 
 
 dual 1 
 
& The Water Bath . 
 
 dual ; and the operations are performed with a 
 greater degree of order, precilion, and facility. 
 
 If, inftead of employing a vefTel filled with 
 fand, we ufe a vefTel of water, and the evapo- 
 ratory vefTel be plunged in the liquid, the eva- 
 poration is faid to be made on the water bath : 
 in this cafe, the fubftance to be evaporated is 
 only heated by communication from the water. 
 This form or method of evaporation is em- 
 ployed when certain principles of great volati- 
 lity, fuch as alcohol, or the aromatic principles 
 of plants, are to be extracted or diftilled. It 
 pofTefTes the advantage of affording produces 
 which are not changed by the fire, becaufe the 
 heat is tranfmitted to them by the intervention 
 of a liquid : it is this circumftance which ren- 
 ders the procefs valuable for the extra&ion of 
 volatile oils, perfumes, ethereal liquids,&c. It 
 pofTelTes the advantage of affording a heat near- 
 ly equal, becaufe the degree of ebullition is a 
 term nearly conftant ; and this ftandard heat 
 may be graduated or varied at pleafure, by add- 
 ing falts to the liquid of the water bath, becaufe 
 this fingle circumflance renders the ebullition 
 more or lefs quick and eafy. The fame cffedl 
 may likewife be produced by reftraining the 
 evaporation; for in this cafe the liquid may af- 
 fume a degree of heat much more confiderablc. 
 
 as 
 
I 
 
 Sublimation. Reverberation . 9 
 
 as is feen in the digefler of Papin, fleam en- 
 gines, eolipiles, and the boilers for firiking 
 the red tinge in cotton. 
 
 Sublimation differs from evaporation, be- 
 caufe the fubflance to be raifed is folid. The 
 veffels ufed in this operation are known by the 
 name of fublimatory veffels. Thefe are com- 
 monly globes terminating in a long neck : they 
 are then called mattraffes. 
 
 In order to fublimeany fubflance, a part of 
 the ball of the mattrafs is furrounded with fand. 
 The matter which is volatilized by the heat, 
 rifes, and is condenfed againfl the coldeft part 
 of the veffel ; where it forms a flratum or cake, 
 that may be taken out by breaking the veffel 
 itfelf. In this manner it is that fal ammoniac, 
 corrofivefublimate, and other fimiiar produdls, 
 are formed for the purpofes of commerce. 
 
 Sublimation is ufually performed either for 
 the purpofe of purifying certain fubflances, 
 and difengaging them from extraneous matters; 
 or elfe to reduce into vapour, and combine 
 under that form, principles which would have 
 united with great difficulty if they had not been 
 brought to that flate of extreme divifion. 
 
 II. The reverberatory furnace. — The name 
 of the reverberatory furnace has been given to 
 
 that 
 
 1 
 
io The Reverberatory Furnace . 
 
 that conftrudtion which is appropriated to 
 diftillation. 
 
 This furnace is compofed of four parts, 
 i. The afh-hole, intended for the free paffage 
 of the air, and to receive the afhes or refidue of 
 the combuftion. 2. The fire-place, feparated 
 from the afh-hole by the grate, and in which 
 the combuftible matter is contained. 3. A 
 portion of a cylinder, which is called the la- 
 boratory, becaufe it is this part w r hich receives 
 the retorts employed in the operations or dis- 
 tillations. 4. Thefe three pieces are covered 
 with a dome, or portion of a fphere, pierced 
 near its upper part by an aperture, which af- 
 fords a free paffage to the current of air, and 
 forms a chimney. The molt ufuai form of the 
 reverberatory furnace is that of a cylinder ter- 
 minated by a hemifphere, out of which arifes a 
 chimney of a greater or lefs length, to produce 
 a fuitable degree of afpiration. 
 
 In order that a reverberatory furnace may 
 be well proportioned, it is neceffary, 1 . That 
 the afh-hole fhould be large, to admit the air 
 frefh and unaltered. 2. That the fire-place and 
 laboratory together fhould have the form of 
 a true ellipfis, whofe two foci fhould be occu- 
 pied by the fire and the retort. In this cafe all 
 
 the 
 
Diftillation . Retorts . 1 1 
 
 the heat, whether direft or refle&ed, will 
 ftrike the retort. 
 
 The reverberatory furnace is ufed for diftil- 
 lation. Diftillation is that procefs by which 
 the force of fire is applied to difunite and fe- 
 parate the feveral principles of bodies, accord- 
 ing to the laws of their volatility, and their 
 feveral affinities. 
 
 Diftilling veffels are known by the name of 
 retorts. 
 
 Retorts are formed of glafs, of ftone-ware, 
 of porcelain, or of metal; thefefubftances being 
 refpedlively ufed, according to the nature of 
 the bodies intended tobeexpofed to diftillation. 
 
 Whatever be the nature of the material, the 
 forms of retorts are the fame. This figure re- 
 fembles an egg, terminating in a beak or tube, 
 which diminifties infenfibly in diameter, and 
 is fiightly inclined or bended. 
 
 The oval portion of the retort, which is call- 
 ed its belly, is placed in the laboratory of the 
 furnace, and is fupported upon two bars of 
 iron, which feparate the laboratory from the 
 fire-place ; while the beak or neck of the re- 
 tort ifiues out of the furnace through a circular 
 aperture formed in the edges of the dome and 
 of the laboratory. 
 
 A velfel intended to receive the produdl of 
 
 the 
 
1 2 Receivers . Furnaces . 
 
 the diftillation is fitted to the neck of the re- 
 tort. This veffel is called the recipient, or 
 receiver. 
 
 The receiver is commonly a fphere with two 
 apertures ; the one of confiderable magnitude, 
 to receive the neck of the retort ; the other 
 fmaller, to afford vent for the vapours. This 
 part is called the tubulure of the receiver; 
 whence the terms tubulated receiver, or re- 
 ceiver not tubulated, &c. 
 
 Though the reverberatory furnace be parti- 
 cularly adapted to diftillation, this operation 
 may be performed on the fand-bath ; and here, 
 as in other cafes, it depends fingly on the 
 intelligence of the artift to vary his apparatus 
 according to the neceffity of circumftances, 
 and the nature of the fubftances upon which 
 he operates. 
 
 The conftrucftion of thefe furnaces may like- 
 wife be varied ; and the chemift will find it 
 neceffary to learn the art of availing himfelf of 
 every apparatus he poffeffes, to carry his opera- 
 tions into execution : for if he fhould perfuade 
 himfelf that it is impoffible to proceed in 
 chemical refearch, excepting in a laboratory 
 provided with all fuitable veffels, he may let 
 the moment pafs in which a difcovery might 
 be made, but which may not again return. 
 
 And 
 
Forge Furnace . Crucibles . 13 
 
 And it may be truly faid, that he who treads 
 fervilely in the paths of others who have gone 
 before him, will never attain to the difcovery 
 of new truths. 
 
 III. The forge furnace. — The forge furnace 
 is that in which the current of air is determine 
 cd by bellow*s. The afh-hole, the fire-place, 
 and the laboratory are here all united together; 
 and this affemblage forms only a portion of a 
 cylinder, pierced near the lower angle by a 
 fmall hole, into which the tube of the bellows 
 enters. This part is fometimes covered with a 
 hemifphere or dome, to concentrate the heat 
 with greater efficacy, and to refledt it upon 
 the bodies expofed to it. The forge furnace 
 is employed in the fufion and calcination of 
 metals, and generally for all the operations 
 which are performed in crucibles. 
 
 By crucibles we underftand veflels of earth 
 or metal, which are almoft always of the form 
 of an inverted cone. A crucible ought to 
 fupport the ftrongeft heat without melting ; 
 it ought to refill the attacks of all fuch agents 
 as are expofed to heat in veflels of this kind. 
 Thofe crucibles which poflefs the greatefi: 
 degree of perfection, are made in HefTe or in 
 Holland. I have made very good ones by a 
 
 mixture 
 
14 Crucibles . Various Fuels* 
 
 mixture of raw and unbaked clay from SaiavaS 
 in the Vivarais. 
 
 Our laboratories have been provided with 
 crucibles of platina, which unite the moft ex- 
 cellent properties. They are nearly infufible, 
 and at the fame time indeftrudlible by the fire* 
 
 The feveral earthen veffels concerning which 
 we have here treated, may be fabricated by 
 hand, or wrought in the lathe. The firft pro- 
 ceeding renders them more folid, the clay is 
 better united, and it is the only method ufed 
 in glafs manufactories ; but the fecond method 
 is more expeditious. 
 
 The agent of fuch decompofitions as are 
 effected by means of furnaces, is fire. It is af- 
 forded by the combuftion of wood, pit-coal, 
 or charcoal. 
 
 Wood is. only employed in certain large 
 works ; and we prefer charcoal in our labora- 
 tories, becaufe it does not fmoke, has no bad 
 fmell, and burns better in fmall malTes than 
 other, combuftibles. We choofe that which is 
 the moft fonorous, the drieft, and the leaft 
 porous. 
 
 But, in the feveral operations we are about 
 to defcribe, it is neceffary to defend the re- 
 torts from the immediate a&ion of the fire * 
 and alio to coerce and reftrain the expanfible 
 
 vapours. 
 
Lutes and Coatings for Retorts . 15 
 
 vapours, which are very elaftic, and frequent- 
 ly corrofive. It is to anfwer thefe purpofes 
 that various lutes are employed. 
 
 1. A giafs retort expofed to the action of 
 the fire would infallibly break, if the operator 
 were not to have recourfe to the prudent pre- 
 caution of coating it with earth. 
 
 1 have found it advantageous for the coat- 
 ing of retorts, to ufe a mixture of fat earth 
 and frefh horfe dung : for this purpofe, the fat 
 earth is fuffered to rot for fome hours in wa- 
 ter ; and when it is moiftened, and properly foft- 
 ened, it mu ft be kneaded with the horfe dung, 
 
 § 
 
 and formed into a foft pafte, which is to be ap- 
 plied and fpread with the hand upon every part 
 of the retort intended to be expofed to the 
 adtion of the fire. The horfe dung combines 
 feveral advantages. 1. It contains a ferous 
 fluid, which hardens by heat, and ftrongly con- 
 nedls all the parts together: when this juice 
 has been altered by fermentation or age, the 
 dung does not poffefs the fame virtue. 2. The 
 filaments or ftalks of hay, which are fo eafily 
 diftinguifhed in horfe dung, unite all the parts 
 of the lute together. 
 
 Retorts luted in this manner refift the im- 
 prefHon of the fire very well ; and the adhefion 
 of the lute to the retort is fuch, that even fhouid 
 
 the 
 
1 6 Lutes and Coatings for Retorts • 
 
 the retort fly during the operation, the diftil- 
 lation may be ftill carried on, as I have daily 
 experience in works in the large way. 
 
 2. When it is required to coerce or oppofe 
 the efcape of the vapours which are difengaged 
 during any operation, it is no doubt fufficient 
 if the joinings of the velTels be covered with 
 paper glued on, or with flips of bladder moift- 
 ened with the lute of lime and white of egg, 
 provided the vapours be neither dangerous nor 
 corrofive ; bur, when the vapours are corrofive, 
 it is neceflary to ufe the fat lut-e to retain them. 
 
 Fat lute is made with boiled linfeed oil mix- 
 ed and well incorporated with lifted clay. Nut 
 oil, kneaded with the fame clay, forms a lute 
 pofTefling the fame properties. It is eafily ex- 
 tended in the hand, and is ufed for defending 
 the joinings of veffels, upon which it is after- 
 wards fecured by ftrips of linen, dipped in the 
 Fate of lime and white of egg. Before the ap- 
 plication of heat in any diftihation, it isnecef- 
 fary firft to fuffer the lutes to dry. Without 
 this precaution, the vapours would rife and ef- 
 cape ; or ofherwife they would combine with 
 the water which moiftens the lutes, and would 
 corrode and deftroy the bladder, the fkin, the 
 paper, and in a word every fubflance ufed to fe- 
 cure them in their places. The lute of lime and 
 
 white 
 
Lutes . IVoulfe's Apparatus . 17 
 
 % 
 
 white of egg dries very fpeedily, and muft be 
 ufed the moment it is made. This lute, like- 
 wife, oppofes the greateft refinance to the ef- 
 cape of the vapours, and adheres the moft inti- 
 mately to the glafs. It is made by mixing a 
 fmall quantity of finely-powdered quick-lime 
 with white of egg, and afterwards beating up the 
 mixture to facilitate the combination. It muff 
 then be infiantly applied on pieces of old linen, 
 to be wrapped round the places of joining. 
 
 In the large works, where it is not polfible 
 to attend to all thefe minute details, the join- 
 ings of the retort and receiver are luted toge- 
 ther with the fame lute which is ufed to coat 
 the retorts. A covering of the thicknefs of a 
 few lines is fufficient to prevent the vapours of 
 the marine or nitrous acid from efcaping. 
 
 As in certain operations a difengagement 
 takes place of fo prodigious a quantity of va- 
 pours, that it is dangerous to confine them ; 
 and as, on the other hand, the fuffering them to 
 efcape would occafion a confiderable lofs in 
 the produdt ; an apparatus has been contrived 
 of great ingenuity and fimplicity to moderate 
 the iflue, and to retain without rifle fuch va- 
 pours as would otherwife efcape. This appa- 
 ratus is known by the name of its author, Mr. 
 Woulfe, a famous Englifh chemift. His moft 
 Voi. I. C excellent 
 
1 8 IVoulfe's Apparatus . 
 
 excellent procefs confifts in adapting the extre- 
 mity of a recurved tube to the tubulure of the 
 receiver ; the other end of which is plunged in- 
 to water, in a bottle half filled, and properly 
 placed for that purpofe. From the empty part 
 of this bottle iffues a lecond tube, which is in 
 like manner plunged in the water of a fecond 
 bottle. A number of other bottles may be 
 added, obferving the fame precautions ; with 
 the attention, neverthelefs, to leave the laft open, 
 to give a free efcape to the vapours which are 
 not coercible : and, when the apparatus is thus 
 difpofed, all the joinings are to be luted. It 
 will eafily be imagined that the vapours which 
 efcape from the retort are obliged to pafs 
 through the tube adapted to the tubulure of the 
 receiver, and confequently muff pafs through 
 the water of the firft bottle : they therefore 
 fuffera firft refiftance, w'hich partly condenfes 
 them. But as almoft all vapours are more or 
 lefs mifciblc and foluble in water, a calculation 
 is previoufly made of the quantity of water 
 necelfary to abforb the vapours which are dis- 
 engaged from the mixture in the retort; and 
 care is taken to diftribute this proper quantity 
 of water in the bottles of the apparatus. 
 
 By this means we obtain the pureft and raoft 
 concentrated produ&s; becaufe the water, 
 
 which 
 
IVoulfe's Apparatus . 1 9 
 
 which is always the receiver, and is the vehicle 
 of thefe fubftances ; becomes faturatedwith them. 
 There is, perhaps, no other method of obtain- 
 ing produds always of an equal energy, and 
 comparable in their effeds; a circumftance of 
 the greateft importance in the operations of the 
 arts, as well as in philofophical experiments. 
 
 I have applied this apparatus to works in the 
 large way ; and I ufe it to extrad the common 
 muriatic acid, the oxigenated muriatic acid, 
 ammoniac or volatile alkali, &c. 
 
 As it would very often happen, in this appa- 
 ratus, that the preffure of the external air would 
 caufe the water of the outer veffels to pafs into 
 the receiver, in confequence of the fimple re- 
 frigeration of the retort; this inconvenience has 
 been obviated, by inferting a ftraight tube into 
 the necks of the fir ft and the fecond bottles, to 
 fuch a depth, that its lower end is plunged into 
 the water, while its other end rifes feveral inches 
 above the neck of the bottle. It may ealily be 
 conceived, as a confequence of this difpofition, 
 that when the dilated vapours of the receiver 
 and retort are condenfed by cooling, the exter- 
 nal air will rufh through thefe tubes toeftablifh 
 the equilibrium ; and the water cannot pafs 
 from the one to the other. 
 
 Before the invention of this apparatus, it was 
 C 2 ufual 
 
20 
 
 JVoulfc's Apparatus 4 
 
 ufual to drill a hole in the receiver, which was 
 kept clofed, and only opened from time to time 
 for the efcape of the vapours. This method 
 was inconvenient in many refpedts. In the firft 
 place, and principally, becaufe, in fpite of all 
 precautions, it was attended with the rilk of 
 an explofion every moment, by the irregular 
 difengagement of the vapours, and the impoffi- 
 bility of calculating the quantity produced in a 
 given time. A fecond inconvenience was, that 
 the vapours which thus efcaped occafioned a 
 conliderable lofs in the product, and even weak- 
 ened the remainder ; becaufe this volatile prin- 
 ciple conhfted of the ftrongeft part. A third 
 inconvenience was, that the vapours which did 
 cfcape incommoded theartiftto fucha degree, 
 that it was impoflible to perform moft of the 
 operations of chemiftry in the courfe of a lec- 
 ture, where a corrfiderable number of auditors 
 were prefent. 
 
 ? Thus it is that the apparatus of Woulfe 
 unites a number of advantages : on the one hand, 
 economy in the procelTes, and fuperiority in 
 the produdt ; on the other hand, fafety for the 
 chemift and his afliftants : and, in every point 
 of view, the author is entitled to the belt ac- 
 knowledgments of chemifts, who were too of- 
 ten fo much affedted with thefe unwholefome 
 
 exhalations, 
 
Balances , &c. 
 
 21 
 
 exhalations, that their health was either totally 
 dedroyed, or they fell abfoiute vi&ims to their 
 zeal for the promotion of fcience. 
 
 It is necedary that a laboratory fhould be 
 provided with balances of the utmod accuracy ; 
 for the chemift, who very frequently operates 
 only upon fmall quantities, ought to be able, 
 by the ftridnefs of his operations, and the ac- 
 curacy of his apparatus, to produce refults com- 
 parable with thofe of works in the large way. 
 It frequently happens that the Ample elfay of 
 a fpecimen of an ore determines the opening 
 .of a mine: and it fcarcelyneed be pointed out, 
 of how great confequence it is to remove every 
 caufe of error from the operations of chemif- 
 try ; fince the flighted error in the works of 
 the laboratory may be attended with the mod 
 unhappy confequences, when the application 
 of the principles is made to works in the large 
 way. 
 
 We fhall treat of other veffels and chemical 
 apparatus, in proportion as we fhali have occa- 
 cafion to make ufe of them ; for it appears to us 
 that, by thus connetding the defeription with 
 their ufe, we fhall fucceed better in rendering 
 them intelligible to the reader, at the fame 
 time that his memory will be lefs fatigued. 
 
 SEC- 
 
22 
 
 Gravitation or Alt rati ion . 
 
 SECTION I. 
 
 Concerning the General Law which tends 
 to bring the Particles of Bodies toge- 
 ther, and to maintain them in a State 
 of Mixture or Combination. 
 
 T HE Supreme Being has given a force of 
 mutual attraction to the particles of mat- 
 ter; a principle which is alone fufficient to pro- 
 duce that arrangement which the bodies of this 
 univerfe prefent to our obfervation. As a very 
 natural confequence of this primordial law, it 
 follows that the elements of bodies mult have 
 been urged towards each other; that maffes 
 mull: have been formed by their re-union ; and 
 that folid and compact bodies muff have in- 
 fenlibly been conftituted; towards which, as 
 towards a centre, the lefs heavy and lefs corn- 
 pad bodies muff gravitate. 
 
 This law of attraction, which the chemifts 
 call Affinity, tends continually to bring prin- 
 ciples together which are difunited, and retains 
 with more or lefs energy thofe which are already 
 in combination ; fo that it is impoffible to pro- 
 duce any change in nature, without interrupting 
 or modifying this attractive power. 
 
 It 
 
Affinity of Aggregation. 23 
 
 It is natural, therefore, % nd even indifpenfa- 
 ble that we fhould fpeak of the law of the affi- 
 nities before we proceed to treat of the me- 
 thods of analyfis. 
 
 Affinity is exercifed either between princi- 
 ples of the fame nature, or between principles 
 pf a different nature. 
 
 We may, therefore, diftinguiffi two kinds of 
 affinity, w r ith refped to the nature of bodies. 
 1, The affinity of aggregation, or that which 
 lexifts between two principles of the fame na- 
 ture. 2. The affinity of compofition, or that 
 which retains two or more principles of diffe- 
 rent natures in a ftate of combination. 
 
 Of the Affinity of Aggregation. 
 
 Two drops of water which unite together in- 
 to one, form an aggregate, of which each drop 
 is known by the name of an integrant part. 
 
 An aggregate differs from a heap ; becaufe 
 the integrant parts of this laft have no percep- 
 tible adhelion to each other; as, for example, 
 a heap of barley, of fand, &c. 
 
 An aggregate, and a heap, differ from a 
 mixture; becaufe the conflituent parts of this 
 laft are of a different nature; as, for example, 
 in gun-powder. 
 
 The affinity of aggregation is ftronger, the 
 
 nearer 
 
24 Affinity sf Aggregation. 
 
 nearer the integrant parts approach to each 
 other ; fo that every thing which tends to fe- 
 parate or remove thefe integrant parts from 
 each other, diminifhes their affinity, and weak- 
 ens their force of cohefion. 
 
 Heat produces this, efted: upon mod known 
 bodies: hence it is that melted metals have 
 no confidence. The caloric, or matter of heat, 
 by combining with bodies, almod always pro- 
 duces an effedd oppofite to the force of attrac- 
 tion ; and wc might condder ourfelves as autho- 
 rifed to affirm that it is a principle of repulfion, 
 if found chemidry had not proved that it pro- 
 duces this effedl only by its endeavour to com- 
 bine with bodies, and thereby necefTarily dimi- 
 nifhing their force of aggregation, as all other 
 chemical agents do. Betides which, the ex- 
 treme levity of caloric produces the effedt that, 
 when it is combined with any given body, it 
 continually tends to elevate it, and to overcome 
 that force which retains it, and precipitates it 
 towards the earth. 
 
 The mechanical operations of pounding, of 
 hammering, or of cutting, likewifediminifh the 
 affinity of aggregation. They remove the in- 
 tegrant parts to a didance from each other; and 
 this new difpofition, by prefenting a lefs degree 
 of adhefion, and a larger furface, facilitates the 
 
 immediate 
 
Affinity of Compojition . 15 
 
 immediate action, and augments the energy* of 
 chemical agents. It is for this purpofe that bo- 
 dies are divided when they are to be analyfed* 
 and that the effect of re-agents is facilitated by 
 the adtion of heat. 
 
 The mechanical divificn of bodies is more 
 difficult, the ftronger their aggregation. 
 
 Aggregates exift under different ftates; they 
 arefolid, liquid, aeriform, &c. — SeeFourcroy’s 
 Chemiftry. 
 
 Of the Affinity of Compofition. 
 
 Bodies of different kinds exert a tendency or 
 attraction upon each other, which is more or lefs 
 ffrong; and it is by virtue of this force that all 
 the changes of compofition or decompofkion 
 obferved among them, are effected. 
 
 The affinity of compofition exhibits invari- 
 able laws in all the phenomena it caufes. We 
 may ftate thefe laws as general principles; to 
 which may be referred all the effects prefented 
 to our obfervation by the action of bodies up- 
 on each other. 
 
 I. The affinity of compofition acts only be- 
 tween the conftituent parts of bodies. 
 
 The general law T of attraction is exerted upon 
 the maffes; and in this refpedt it differs from 
 the law of the affinities* which does not percep- 
 tibly 
 
i6 
 
 Affinity of Compofition. 
 
 tibly a£t but on the elementary particles of bo- 
 dies. Two bodies placed near each other do 
 not unite; but, if they be divided and mixed, 
 a combination may arife. We have examples of 
 this when the muriate of foda, or common fait, 
 is triturated with litharge ; the muriate of am- 
 moniac, or common fal ammoniac, with lime, 
 &c. And it may be aflerted, that the energy of 
 the affinity of compofition is almoft alwayspro- 
 portioned to the degree of the divifion of bodies. 
 
 II. The affinity of compofition is in the in- 
 verfe ratio of the affinity of aggregation. 
 
 It is fo much the more difficult to decompofe 
 a body, as its conftituent principles are united 
 or retained by a greater force. Gafes, and ef- 
 pecially vapours, continually tend to combina- 
 tion, becaufe their aggregation is weak : and na- 
 ture, which is conftantly renewing the produc- 
 tions of this univerfe, never combines folid with 
 folid ; but, reducing every thing into the form 
 of gas, by this means breaks the impediments 
 of aggregation ; and thefe gafes uniting toge- 
 ther, form folids in their turn. 
 
 Hence, no doubt, it arifes, that the affinity 
 of compofition is fo much the more ftrong as 
 bodies approach nearer to the elementary ftate $ 
 and we fhall obferve, on this fubjedt, that this 
 law of nature is founded in wifdom : for if the 
 
 force 
 
Affinity of Competition. 27 
 
 force or affinity of compofition did not increafe 
 in proportion as bodies were brought to this de- 
 gree of fimplicity; if bodies did not afiume a 
 decided tendency to unite and combine, in pro- 
 portion as they approach to their primitive or 
 elementary ftate ; the mafs of elements would 
 continually increafe by thefe fucceffive and un- 
 interrupted decompofitions; and we fhould in- 
 feniibly return again to that chaos or confufion 
 of principles, which is fuppofed to have been 
 the original ftate of this globe. 
 
 The neceftity of this ftate of divifion, which 
 is fo proper to increafe the force of affinity, has 
 caufed it to be admitted as an inconteftable prin- 
 ciple, that the affinity of compofition does not 
 take place, unlefs one of the bodies be in the 
 fluid ftate : corpora non agunt niji fint fluida* But 
 it feems to me that extreme divifion might be 
 fubftituted inftead of diffolution ; for both 
 thefe operations tend only to attenuate bodies, 
 without altering their nature. It is by virtue of 
 this divifion, which is equivalent to di Ablution, 
 that the decompofition of muriate of foda is 
 effected by trituration with minium, as well as 
 the union of cold and dry alkali with antimony, 
 and the difengagement of volatile alkali by the 
 Ample mixture of fal ammoniac with lime. 
 
 III. When two or more bodies unite by 
 
 the 
 
28 Affinity of Compofition . 
 
 the affinity of compofition, their temperature 
 changes. 
 
 This phenomenon cannot be explained but 
 by confidering the fluid of heat as a conftitu- 
 ent principle of bodies, unequally diflributed 
 amongft them ; fo that, when any change is 
 produced in bodies, this fluid is difplaced in 
 its turn, which neceffarily produces a change 
 of temperature. We (hail return to thofe prin- 
 ciples when we fpeak of heat f 
 
 IV. The compound which refults from the 
 combination of two bodies, poffeffes proper- 
 ties totally different from thofe of its conftitu- 
 ent principles. 
 
 Some chemifts have affirmed, that the pro- 
 perties of compounds were intermediate be- 
 tween thofe of their conftituent parts. But 
 this term ct intermediate” has no meaning in 
 the prefent cafe ; for what intermediate qua- 
 lities can exift between four and fweet, or be- 
 tween water and fire? 
 
 If we attend ever fo little to the phenomena 
 which are exhibited to us by bodies in their 
 compofition, we fhall perceive that their form, 
 their tafte, and their confiftence, are changed 
 in combination ; and we cannot eftablifh any 
 rule to indicate, apriori> all the changes which 
 may arife, and the nature and properties of the 
 body which fhall be formed. 
 
 V. Every 
 
Jffinity of Cotnpofition. 29 
 
 V, Every individual fubftance has its pccu- 
 liar affinities with the various fubftances pre-* 
 fented to it. 
 
 If all bodies had the fame degree of affinity 
 with each other, no change could take place 
 amongft them : we fhould not be able to dis- 
 place any principle by prefenting one body to 
 another. Nature has therefore wifely varied 
 the affinities, and appointed to each body its re- 
 lation with all thofe that can be prefented to it. 
 
 It is in confequence of this difference in the 
 affinities that all chemical decompolitions are 
 effedted; all the operations of nature and art 
 are founded upon it. It is therefore of im- 
 portance to be well acquainted with all the 
 phenomena and circumffances which this law 
 of decomposition can prefent to us. 
 
 The affinity of compofition has received diffe- 
 rent names, according to its effedts. It is divided 
 into Simple affinity, double affinity, the affinity 
 of an intermedium, reciprocal affinity, &c. 
 
 1 . Two principles united together, and Sepa- 
 rated by means of a third, afford an example of 
 limple affinity : it confifts in the diplacing of 
 one principle by the addition of a third. Berg- 
 man has given it the name of Elective Attrac- 
 tion. 
 
 / 
 
 The body which is difengaged, or displaced, 
 
 is 
 
30 *The Laws of Lecompofition . 
 
 is known by the name of the Precipitate. An 
 alkali precipitates metals from their folutions; 
 the fulphuric acid precipitates the muriatic, the 
 nitric, &c. 
 
 The precipitate is not always formed by the 
 difengaged fubftance. Sometimes the new 
 compound itfelf is precipitated ; as, for exam- 
 ple, when I pour the fulphuric or vitriolic acid 
 on a folution of muriate of lime. Sometimes 
 the difengaged body and the new compound 
 are precipitated together; as, for example, 
 when the fulphate of magnefia or Epfom fait 
 isdiffolved in water, and precipitated by means 
 of lime-water. 
 
 2. It often happens that the compound of 
 two principles cannot be deftroyed either by a 
 third or a fourth body feparately applied; but 
 if thefe two bodies be united, and placed in con- 
 tact with the fame compound, adecompoiition 
 or change of principles will then take place. 
 This phenomenon conftitutes the double affini- 
 ty. An example will render this propofition 
 more clear and precife. The fulphate of pot-afh 
 or vitriolated tartar is not completely decom- 
 pofed by the nitric acid or by lime, when either 
 of thefe principles is feparately prefented ; but, 
 if the nitric acid be combined with lime, this 
 < nitrate of lime will decompofe the fulphate of 
 
 pot-afh. 
 
Qiiiefcent and Divelknt Affinities* 3 1 
 
 pot-afh. In this laft cafe the affinity of the 
 fulphuricacid with the alkali is weakened by its 
 affinity to the lime. This acid, therefore, is fub- 
 jeCt to two attractions; the one which retains 
 it to the alkali, and the other which attracts it 
 towards the lime: Mr. Kirwan has named the 
 firft the Quiefcent Affinity, the other the Di- 
 vellent Affinity. The fame may be faid refpeCt- 
 ing the affinities of the alkali; it is retained to 
 the fulphuric acid by a fuperior force, but ne- 
 verthelefs attracted by the nitric acid* Let us 
 fuppofe, now, that the fulphuric acid adheres 
 to the alkali with a force as 8, and to the lime 
 by a force expreffied by the number 6 ; that the 
 nitric acid adheres to the lime by a force as 4* 
 and tends to unite with the alkali by aforceas 7* 
 It may then be perceived that the nitric acid 
 and the lime, feparately applied to the fulphate 
 of pot-afh, would not produce any change: but 
 if they be prefented in a flate of combination, 
 then the fulphuric acid is attracted on the one 
 hand by 6, and retained by 8 ; it has therefore 
 an effective attraction to the alkali as 2. On 
 the other hand, the nitric acid is attracted by 
 a force as 7, and retained by a force as 4 5 it 
 therefore retains a tendency to unite with the 
 alkali, which is denoted by the number 3; 
 and confequently it ought to difplace the ful- 
 phuric 
 
J2 Various Cafes of Affinity. 
 
 phuric acid, which is retained only by a force 
 as 2. 
 
 3. There are cafes in which two bodies, hav- 
 ing no perceptible affinity to each other, obtain 
 a difpofition to unite by the intervention of a 
 third; and this is called the affinity of an in- 
 termediunm An alkali is the intermedium of 
 union between oil and water ; hence the theo- 
 ry of lixiviums, of wafhing, &c. &c. 
 
 If the affinities of bodies were well known, 
 we might foretel the refults of all operations: 
 but it is obvious how difficult it muft be to ac- 
 quire this extenfive knowledge of nature ; more 
 efpecially fince modern difeoveries have exhi- 
 bited to us an infinity of modifications in our 
 procefles, and have fhewn that refults may vary 
 with fuch facility, that even the abfence or pre- 
 fence of light will render them very different. 
 
 As long as chemiftry was confined to the 
 knowledge of a few fubftances, and was bulled 
 only in attending to a certain number of fads, 
 it was poffible to draw up tables of affinity, and 
 to exhibit the refult of our knowledge in one 
 and the fame table. But all the principles 
 upon which thefe tables have been conftruded, 
 have received modifications ; the number of 
 principles has increafed ; and we find ourfelves 
 under the neceflity of labouring upon new 
 
 ground. 
 
33 
 
 Various Cafes of Affinity. 
 
 ground. A fketch of this great work may be 
 feen in the Effay on Affinities of the celebrated 
 Bergman, and in the article Affinity in the En- 
 cyclopedic Metbodique. 
 
 VI. The particles which are brought toge- 
 ther and united by affinity, whether they be of 
 the fame nature or of different natures, continu- 
 ally tend to form bodies of a polyhedral, con- 
 ftant, and determinate form. 
 
 This beautiful law of nature, by which fhe 
 impreffes on all her productions a conftant and 
 regular form, appears to have been unknown 
 to the ancients : and when chemifts began to 
 difcover that almoft all bodies of the mineral 
 kingdom affected regular forms, they at firft 
 diftinguilhed them according to the inaccurate 
 refemblance fuppofed to exit between them 
 and other known bodies. Hence the denomi- 
 nation of cryftals in pyramids, needles, points 
 of diamonds, croffes, fword blades, &c. 
 
 We are more particularly indebted to the ce- 
 lebrated Linnaeus for the firft precife ideas of 
 thefe geometrical figures. He took notice of 
 theconftancy and uniformity of this character; 
 and this celebrated naturalift thought himfelf 
 authorifed to make it the balls of his method 
 of claffification of the mineral kingdom. 
 
 Mr. Rome de Lifle has proceeded ftill far- 
 Vol. I, I> ther: 
 
34 Regular Figures of Bodies 
 
 thcr: he has fubjedled all the forms to A flrift 
 examination ; he has, as it were, decompofed 
 them ; and is of opinion that he can diftinguifh 
 in the cryflals of all analogous or identical fub- 
 itances, the iimple modifications and fhades of 
 a primitive form. By this means he has re- 
 duced all the confufed and irregular forms to 
 certain primitive figures; and has attributed to 
 nature a plan or primitive defign, which {he va- 
 ries and modifies in a thoufand manners, accord- 
 ing to circumflances that influenceherproceed- 
 ings. This truly great and philofophical work 
 has rendered this part of mineralogy in the 
 highefl degree interefling; and if we fhould 
 admit that Mr. De Lifle has perhaps carried 
 thefe rcfembiances too far, we cannot but allow 
 that he deferves a diflinguifhed place amongfl 
 thofe authors who have contributed to the pro- 
 grefs of fcience. TheCry flail ographie of this 
 celebrated naturalifl may be perufed with ad- 
 vantage. 
 
 The abbe Hauy has fince applied calculation 
 to obfervation. He has undertaken to prove 
 that each cryflal has a nucleus or primitive form ; 
 and has fliewn the laws of diminution to which 
 the component laminae of the cryflals are fub- 
 jedl, in their tranfition from the primitive to 
 the fecondary forms. The development of 
 
 thefe 
 
produced by Cryftallization. 35 
 
 thefe fine principles, and their application to 
 cryftals the beft known, may be feen in his 
 theory of the ftrudture of cryftals, and in feve- 
 ral of his memoirs printed in the volumes of 
 the Academy of Sciences. 
 
 The united labours of thefe celebrated na- 
 turalifts have carried cryftallography to a de- 
 gree of perfection of which it did not appear 
 fufceptible. But we fhall, at this moment, at- 
 tend only to the principles according to which 
 cryftallization is effected. 
 
 To difpofe a fubftance to cryftallization, it 
 is neceffary in the firft place to reduce it to 
 the moft complete ftate of divifton. 
 
 This divifion may be effected by folution, or 
 by an operation purely mechanical. 
 
 Solution may be effected either by the means 
 of water or of fire. The folution of falts is in 
 general performed in the firft liquid, that of 
 metals is effected by means of the fecond; and 
 their folution is not complete until a degree of 
 heat is applied of fufficient intenfity to convert 
 them into the ftate of gas. 
 
 When the water which holds any fait in fo- 
 lution is evaporated, the principles of thedif- 
 folved body are infenfibly brought nearer to 
 each other, and it is^ obtained in a regular form. 
 The fame circumfhance nearly takes place in 
 D 2 the 
 
3 6 Various Appear ancts 
 
 the folution by fire. When a metal is impreg- 
 nated with this fluid, it does not cryftallize but 
 in proportion as this excefs of igneous fluid 
 is withdrawn. 
 
 In order that the form of a cryftal may be 
 regular, three circumftances are required; 
 time, a fufficient fpace, and repofe. Confult 
 Linnaeus, Daubenton, &c. 
 
 A. Time caufes the fuperabundant fluid to 
 be flowly dillipated, and brings the integral 
 parts nearer to each other by infenfible grada- 
 tion, and without any fudden fliock. Thefe 
 integrant parts therefore unite according to 
 their conffant laws, and form a regular cryftal. 
 For this reafon it is, that flow evaporation is 
 recommended by all good chemifts. Vide 
 Stahl’s Treatife on Salts, chap. 29. 
 
 In proportion as the evaporation of the fol- 
 vent is effected, the principles of the diiTolved 
 body approach each other, and their affinity is 
 continually augmented while that of the fol- 
 vent remains unaltered. Hence it arifes, no 
 doubt, that the laft portions of the folvent are 
 moft difficultly volatilized, and that falts retain 
 a greater or lefs quantity, which forms their 
 water of cryftallization. The proportion of 
 water of cryftallization not only varies greatly 
 in the different falts, but it adheres with greater 
 
 or 
 
attending CryftaUization , &c, 37 
 
 or lefs ftrength. There are feme which fuffer 
 this water to fly off when they are expofed to 
 the air ; fiich as foda or the mineral alkali, the 
 fulphate of foda or Glauber’s fait, &c. In this 
 fituation thefe falts lofe their tranfparency, 
 and fall into powder : they are then faid to have 
 efflorefeed. There are other falts which obfti*- 
 nately retain their water of cryftallization ; fuch 
 as the muriate of pot-afh, the nitrate of pot- 
 afh or common nitre, &c. 
 
 The phenomena prefented to us by the dif- 
 ferent falts, when forcibly deprived of their 
 water of cryftallization, exhibit other varieties. 
 Some crackle with the heat, and are thrown 
 about in fmall pieces when the water is difll- 
 pated: this appearance is called decrepitation. 
 Others emit the fame water in the form of fleam, 
 and are liquefied with a diminution of their 
 bulk. Others again fwell up, and become 
 converted into a biiftered or porous fubftance. 
 We are indebted to Mr. Kirwan for an ac- 
 curate table of the water of cryftallization con- 
 tained in each fait. This table may be feen 
 by confulting his Mineralogy. 
 
 The Ample cooling of the fluid which holds 
 the fait in folution may precipitate a confider- 
 able quantity. The caloric and the water dif- 
 folve a greater quantity of fait when their addon 
 
 is 
 
3 8 Various Appearances 
 
 is united; and it may eafily be imagined that 
 the fubtradiion of one of the folvents muft oc- 
 cafion the precipitation of that portion which 
 it held in folution. Thus it is that vrarm wa- 
 ter faturated with fait muft fuller a part to 
 precipitate by cooling; and for this reafon cry- 
 ftallization always begins at the furface of the 
 liquid, and on the fides of the containing vef- 
 fel ; namely, becaufe thefe parts are the firft 
 which fuffer refrigeration. 
 
 It is the alternation of heat and cold w T hich 
 caufes the atmofphere to diflolve fometimes a 
 greater, and fometimes a lefs quantity of water; 
 and conftitutes mifts, the evening dew, &c. 
 
 The mutual approach of the conftituent 
 parts of a body held in folution may be like- 
 wife accelerated by prefenting to the water 
 which fufpends them, another body which has 
 a ftrong affinity to it. It is upon this princi- 
 ple that alcohol precipitates feveral falts. 
 
 B. Space or fufficient room is likewife a con- 
 dition neceftary for obtaining regular cryftalli- 
 zation. If nature be reftrained in her opera- 
 tions, the product of her labour will exhibit 
 fymptoms of this fyate of conftraint. It may be 
 after ted that nature forms her productions ac- 
 cording to all the circumftances which may in- 
 fluence her operations. 
 
 Co A ftate 
 
39 
 
 attending CryftalUzaiion> &c. 
 
 C. A (fate of repofe in the fluid is likewife 
 neceffary to obtain very regular forms. Unin- 
 terrupted agitation oppofes all fymmetrical ar- 
 rangement $ and in this cafe the cryftallization 
 obtained will be eonfufed and indeterminate. 
 
 I am perfuaded that, in ordet to obtain bo- 
 dies under the form of cryftals, a previous folu- 
 tion is not neceifary, but that a (imple mecha- 
 nical divifion would be fufficient. To obtain a 
 conviction of this truth, it is only neceifary to 
 obferve that folution does not change the na* 
 ture of bodies, but (imply procures an extreme 
 (tate of divifion ; fo that the difunited princi- 
 ples approaching each other very gradually and 
 without (tarts, can adapt themfelves to each 
 other, by following the invariable laws of their 
 gravity and affinity. Now a divifion purely 
 mechanical produces the fame effeCt, and 
 places the principles in the fame difpofition. 
 We ought not therefore to be furprifed if molt 
 falts, fuch as gypfum, when difperfed in the 
 earth, (hould afiume regular forms without any 
 previous folution ; neither ought we to think 
 it (trange if the imperceptible fragments of 
 quartz, of fpar, &c. when carried along and 
 prodigioufly divided by the aftion of waters, 
 fhould be depofited in the form of regular 
 cryftals. 
 
 A very 
 
40 Cryfi alligation. Saline Vegetation . 
 
 A very fingular property may be obferved in 
 falts ; which may be referred to cryftallization, 
 but is likewife in fome meafure remote from it, 
 becaufe it does not depend upon the fame 
 caufes. This is the property of rifing along 
 the Tides of the veffels which contain the folu- 
 tion. It is known by the name of Saline Ve- 
 getation. 
 
 I have firft demonftrated that this phenome- 
 non depends on the concurrence of air and 
 light ; and that the effedt may be determined 
 at pleafure towards any part of the veffel, by 
 managing and directing the adtion of thefe 
 two agents. 
 
 I have fhewn the principal forms which this 
 fingular vegetation affedts. The detail of my 
 experiments may be feen in the third volume of 
 the Memoirs of the Academy of Touloufe. 
 
 Mr. Dorthes has confirmed my refults ; and 
 has moreover obferved that camphor, fpirits 
 of wine, water, &c. which rife by infenfible 
 evaporation in half-filled veffels, conflantly at- 
 tach themfelves to the moft enlightened parts 
 of the veffels. 
 
 Meffrs. Petit and Rouelle have treated on the 
 vegetation of falts ; but a feries of experiments 
 on the fubjedt was wanting. This is what we 
 have endeavoured to fupply. 
 
 SEC- 
 
Separation of component Tarts of Bodies* 41 
 
 SECTION II. 
 
 Concerning the various Means employed 
 by Chemifts to overcome the Adhefion 
 which exifts between the Particles of 
 Bodies, 
 
 HE law of affinities, towards which our 
 
 attention has been directed, tends conti- 
 nually to bring the particles of bodies into con- 
 tad:, and to maintain them in their (late of 
 union. The efforts of the chemift are almofl 
 all direded to overcome this attradive power, 
 and the means he employs are reducible to — 
 1, The divifion of bodies by mechanical opera- 
 tions. 2. The divifion or feparation of the 
 particles from each other by the affiftance of 
 fol vents. 3. The means of prefenting to the 
 feveral principles of the fame bodies, fubftances 
 which have a ftronger affinity to them than 
 thofe principles have to each other. 
 
 I. The different operations performed upon 
 bodies by the chemift, to determine their na- 
 ture, alter their form, their texture, and even in 
 
 fome 
 
42 Various Phenomena 
 
 fome inftances change their conftitution. All 
 thefe changes are either mechanical or che- 
 mical. 
 
 The mechanical operations we (hall at pre- 
 fent deferibe do not change the nature of fub- 
 ftances, but in general change only their form 
 and bulk. Thefe operations are performed by 
 the hammer, the knife, the peftle, &c. Whence 
 it follows, that the chemical laboratory ought 
 to be provided with all thefe inftruments. 
 
 Thefe divifions or triturations are perform- 
 ed in mortars of ftone, of glafs, or of metal. 
 It is the nature of the fubftance under exami- 
 nation which determines the ufe of one or the 
 other of thefe veflels. 
 
 The obje6t of thefe preliminary operations 
 is, to prepare and difpofe bodies for new ope- 
 rations which may difunite their principles 
 and change their nature ; thefe laft-mentioned 
 operations, which may be diftinguifhed by the 
 appellation Chemical, are what moft elfential- 
 ly conftitute the analyfis. 
 
 II. The folution to which we are at prefent 
 to attend, confifts in the divifion and difap- 
 pearance of a folid in a liquid, but without 
 any alteration in the nature of the body fo dif- 
 folved. 
 
 The 
 
attending Solution • 
 
 The liquid in which the folid difappears, is 
 called the folvent or menftruum. 
 
 The agent of folution appears to follow cer- 
 tain conftant laws, which we fhall here point 
 out. 
 
 A. The agent of folution does not appear to 
 differ from that of affinity ; and in all cafes the 
 folution is more or lefs abundant, the greater 
 the affinity of the integrant parts of the folvent 
 is to thofe of the body to be difiolved. 
 
 From this principle it follows, that, to faci- 
 litate folution, it is neceffary that bodies fhouid 
 be triturated and divided. By this means a 
 greater number of furfaces are prefented, and 
 the affinity of the integrant parts isdiminifhed. 
 
 It fometimes happens that the affinity be- 
 tween the folvent and the body prefented to it 
 has fo little energy, that it does not become 
 perceptible till after a considerable interval of 
 time. Thefe flow operations, of which we 
 have fome examples in our laboratories, are 
 common in the works of nature; and it is pro- 
 bably to fimilar caufes that we ought to refer 
 mod of thofe reful ts whole caufes or agents 
 efcape our perception or obfervation. 
 
 B. Solution is more fpeedy in proportion as 
 the body to be diffolved prefents a greater fur- 
 face : on this principle is founded the pradlice 
 
 of 
 
44 Various Phenomena 
 
 of pounding, triturating, and dividing bodies 
 intended to be diffolved. Bergman has even 
 obferved, that bodies which arc not attacked 
 in confiderable malTes, become foluble after 
 minute divifion. Letters on Iceland, p.421*. 
 
 C. The folution of a body conftantly pro- 
 duces cold. Advantage has even been taken 
 of this phenomenon to procure artificial cold, 
 much fuperior to the moft rigorous tempera- 
 ture ever obferved in our climates. We fhall 
 again advert to this principle when we come 
 to treat of the laws of heat. 
 
 The principal folvents employed in our 
 operations are water, alcohol, and fire. Bodies 
 fubmitted to one or the other of thefe folvents 
 prefent fimilar phenomena ; they are divided, 
 rarefied, and at laft difappear : the moft re- 
 fractory metal melts, is diflipated in vapour, 
 and paffes to the (late of gas, if a very ftrong 
 heat be applied to it. This laft ftate forms a 
 complete folution of the metallic fubftance in 
 the caloric. 
 
 The effeeft of caloric is often united with 
 one of the other folvents, to accomplifh a 
 more fpeedy and abundant folution. 
 
 The three folvents here mentioned do not 
 
 * Von Troil’s Letters, quoted by Bergman; T. 
 
 excrcife 
 
• attending Solution . 45 
 
 exercife an equal action on all bodies indifcri- 
 minately. Skilful chemifts have exhibited 
 tables of the diffolving power of thefe menftru- 
 ums. We may fee, in the Mineralogy of Kir- 
 wan, with what care that celebrated chemifl 
 has exhibited the degree of folubility of each 
 fait in water. The table of Mr. De Morveau 
 may likewife be confulted on the difTolving 
 power of alcohol. Journal de Phyfique, 1785. 
 
 Mofl authors who have treated of folution 
 have conlidered it in too mechanical a point 
 of view. Some have fuppofed {heaths in the 
 folvent, and points in the body difloived. This 
 abfurd and gratuitous fuppolition has appeared 
 fufficient toaccount for thea&ionof acids upon 
 bodies. Newton and GafTendi have admitted 
 pores in water, in which falts might iniinuate 
 themfelves ; and have by this means explained 
 why water does not augment in its bulk in 
 proportion to the quantity of fait it takes up. 
 Galfendi has even fuppofed pores of different 
 forms ; and has endeavoured to {hew by this 
 means how water faturated with one fait may 
 diffolve others of another kind. Dr. Watfon, 
 who has obferved the phenomena of folution 
 with the greateft care, has concluded from his 
 numerous experiments ; 1. That the water 
 
 rifes in the veflel at the moment of the immer- 
 
 iion 
 
46 Fffefts of Re- Agents. 
 
 fion of the fait. 2. That it falls during the 
 folution. 3. That it rifes after the folution. 
 above the original level. The two lad effects 
 feem to me to arife from the change of tempe- 
 rature which the liquor undergoes. The refri- 
 geration arifing from the folution mud dimi- 
 mfli the volume of the fol vent; but it ought 
 to return to its fird date as foon as the diffo- 
 lution is finifhed. The tables of Dr. Watfon 
 refpe&ing thefe phenomena, and the fpecific 
 gravity of water faturated with different falts, 
 may be confulted in the Journal de Phydque, 
 vol. xiii. p. 62*. 
 
 III. As the peculiar affinities of bodies to 
 each other are various, the condituent princi- 
 ples may be eafily difc-ngaged by other fub- 
 dances ; and it is upon this condderation that 
 the a<dion of all the re-agents employed by 
 chemidry in its analyfis is founded. Some- 
 times the chemid difplaces certain principles, 
 which he can in that date examine more accu- 
 rately, becaufe infuiated, and difengaged from 
 all their combinations. It frequently happens 
 that the re-agent made ufe of combines with 
 fome principle of the body analyfed ; and a 
 compound arifes, whofe characters indicate 
 
 # Or in the fifth vol. of his Chemical Effays. T; 
 
 to 
 
47 
 
 Effects of Re- Agents* 
 
 to us the nature of the principle which has 
 thus entered into combination, becaufe the 
 combinations of the principal re-agents with 
 various bafes are well known. It likewife fre- 
 quently happens that the re-agent made ufe of 
 is itfelf decompofed, which circumftance ren- 
 ders the phenomena and the products more 
 complicated ; but we are enabled from the na- 
 ture of thefe products to form a judgment of 
 the component parts of the body analyfed* 
 This iaft fadt was little attended to by the an- 
 cient chemifts ; and this is one of the princi- 
 pal defedts of the labours of Stahl, who has 
 referred moft of thole phenomena to the bodies 
 which he fubmitted to analylis, which in reali- 
 ty arofe only from the decompolition of the 
 re-agents employed in his operations* 
 
 SEC- 
 
43 
 
 Method offtudying 
 
 SECTION III. 
 
 Concerning the Method of Proceeding 
 which the Chemift ought to follow in 
 the Study of the various Bodies pre- 
 fented to us by Nature. 
 
 H E progrefs made in any fcience de- 
 
 pends upon the folidity of thofe princi- 
 ples which form its bails, and upon the method 
 of fludying them. It is not, therefore, to be 
 wondered at, that chemiftry made but little 
 progrefs in thofe times, when the language of 
 chemifls was enigmatical, and when the prin- 
 ciples of the fcience w r ere founded only on ana- 
 logies falfcly deduced, or on a few facts ill un- 
 derflood. In the times which have followed 
 this epocha, the fafls have indeed been more 
 attended to ; but, inflead of fullering them to 
 fpeak for themfelves, chemifls have been de- 
 firous of making applications, drawing con- 
 fequences, and eflablifhing theories. Thus it 
 was that Stahl, when he firft obferved that 
 oil of vitriol and charcoal produced fulphur. 
 
 if 
 
49 
 
 the Science of Chemijlry . 
 
 if he had then confined himfelf to the fimplc 
 relation of the fadt, would have announced a 
 valuable and eternal truth ; but when he con- 
 cluded that the fulphur was produced by the 
 combination of theinflammableprincipleof the 
 charcoal with the oil of vitriol, he afierted that 
 which the experiment does not point out : then 
 it was that he proceeded further than the fadts 
 warranted ; and this firft rafh ftep might be a 
 firft ftep towards error. All doctrine, in order 
 to be lafting, ought to confift of the pure and 
 fimple expreftion of fadls : but we are almoft 
 always governed by our imaginations ; we 
 adapt the fadls to our manner of feeing them, 
 and thus we are milled by ourfelves. The pre- 
 judice of felf-love afterwards furnifties us w T ith 
 various means to avoid recantation ; we exert 
 ourfelves to draw our fucceftors into the fame 
 paths of error ; and it is not till after much 
 time has been loft, after many vain conjedtures 
 have been exhibited, and after we have the 
 ftrongeft convidtions that it is impoftible to 
 bend the nature of things to our caprices and 
 unfounded ideas, that fome fuperior mind difen- 
 gages itfelf from the delufion ; and returning to 
 experiment, and the nature of things, fuffers 
 himfelf to be led no further than he is autho- 
 rized by thefe to proceed. 
 
 Vo l. I. E 
 
 We 
 
5 ° 
 
 Method of Jludying 
 
 We may affirm to the honour of fome of our 
 cotemporaries, that fads are at prefent difcufled 
 by a much feverer logic ; and it is to this vigo- 
 rous method of inveftigation and difcuffion that 
 we are indebted for the rapid progrefs of che- 
 miftry. It is in confequcnce of this dialectic 
 march that we have at length arrived to the 
 practice of attending to all the principles which 
 are combined or difengagedin the operations of 
 nature and art. We keep an account of all the 
 circumftances which have a more or lefs confl- 
 derable influence on the refults, and we deduce 
 Ample and natural confequences from the whole 
 of the fads ; by which means we create a fcience 
 as Arid: in its principles as fublime in its ap- 
 plications. 
 
 This then is the moment to draw out a faith-* 
 ful fketch of the adual ftate of chemiflry, and 
 to colled in the numerous writings of modem 
 chemifts every thing which may ferve to lay 
 the foundation of this beautiful fcience. 
 
 Not many years ago, it was poffible to pre- 
 fent, in a few wwds, the whole of our know- 
 ledge of chemiflry. It was fufficient, at that 
 time, to point out the methods of performing 
 pharmaceutical operations ; the procefles of the 
 arts were almoft all enveloped in darknefs, the 
 phenomena of nature were all enigmatical; 
 
 and 
 
the Science of Chemiftry. 51 
 
 and it is only fince this veil has begun to be 
 removed that vve have beheld the development 
 of a cotledlion of fads and refearches referable 
 to general principles, and forming a fcience 
 entirely new. Then it was that a number of 
 men of genius reviewed the whole, and attend- 
 ed to the improvement of chemical knowledge. 
 Every ftep in their progrefs brought them 
 nearer to the truth ; and in a few years we have 
 beheld a perfpicuous doctrine arife out of the 
 ancient chaos. Every event has appeared con- 
 formable to the. laws they-eftablifhed ; and the 
 phenomena of art and nature are now explain- 
 ed with equal facility. 
 
 But in order to advance with fpeed in the 
 career which has been thus opened, it is ne- 
 ceflary to explain certain principles, according 
 to which we may direct our fteps. 
 
 In the firft place, I think it proper to avoid 
 that tedious cuftom which fubje&s the beginner 
 in any fcience to the painful talk of collecting 
 all the opinions of various philofophers before 
 he decides for himfelf. In reality, facts belong 
 to all times, and are as unchangeable as nature 
 herfelf, whofe language they are. But the con- 
 fequences deduced from them muft vary ac- 
 cording to the ftate of our acquired knowledge. 
 It is eternally true, for example, that the com. 
 
 E 2 bullion 
 
5 2 Method of ftudying 
 
 bullion of fulphur affords the fulphuric acid. 
 It was believed, for a certain time, that this 
 acid was contained in the fulphur ; but our dif- 
 coveries on the combuflion of bodies ought to 
 have led us to the deduction of a very different 
 theory from that which prefented itfelf to the 
 earlier chemifts. We ought, therefore, to at- 
 tach ourfelves principally to fadts ; or rather 
 we ought to attach ourfelves to the facls only, 
 becaufe the explanation which is given of them 
 at remote times is very feldom fuited to the 
 prefent (late of our knowledge. 
 
 The numerous fadts with w’hich chemiflry 
 has been fucceflively enriched form the firfl 
 cmbarraffment of the fludent who is defirous of 
 acquiring the elements of this fcience. In fadt, 
 what are the elements of fcience P The clear, 
 fimple and accurate enunciation of thofe truths 
 which form its bails. It is neceifary, there- 
 fore, for the full accompliihment of this pur- 
 pofe, to analyfe all the fadts, and to exhibit a 
 faithful and clear abridgment : but this me- 
 thod is impracticable on account of the nume- 
 rous details, and the infinite numb^of difcuf- 
 dons, into which it would lead us. * The only 
 proceeding, therefore, which appears to me to 
 be practicable, is to exhibit the moil decifive 
 experiments, thofe which are the lead contefl- 
 
 ed. 
 
the Science of Chemijlry. 53 
 
 ed, and to neglect thofe which are doubtful or 
 inconclulive : for one experiment, well made, 
 eftablifhes a truth as inconteftably as a thou- 
 fand equally averred. 
 
 When apropofition is found to be fupported 
 by fufpicious or contefted fadts, when oppo- 
 fite theories are built upon contradictory expe- 
 riments, we muft have the courage to difcufs 
 them, to repeat them, and to acquire a certain- 
 ty of thetruth by our own endeavours. But 
 when this method of convidtion is out of our 
 power, we ought to weigh the degree of confix 
 dence which the defenders of the oppofite 
 facts are entitled to ; to examine whether ana- 
 logous facts do not lead us to adopt certain re- 
 fults ; after which it becomes us to give our 
 opinion with that modefty and circumfpection, 
 fuitable to the greater or lefs degree of proba- 
 bility annexed to each opinion. 
 
 But when any dodlrine appears to us to be 
 eftablifhed on experiments of fufficient validi- 
 ty, it then remains to be applied to the pheno- 
 mena of nature and art. This, in my opinion, 
 is the moft certain touchftone to diftinguifhtrue 
 principles from thofe which are without foun- 
 dation. And when I obferve that all the phe- 
 nomena of nature unite, and conform them- 
 felves, as it were, to any theory, I conclude that 
 
 this 
 
j4 Method of flu dying 
 
 this theory is the expreflion and the language 
 of truth. When, for example, I behold that 
 a plant can be fupported by pure water alone, 
 that metals are calcinable, that acids are formed 
 in the bowels of the earth, have I not a right to 
 conclude that the water is decompofed? and do 
 not the chemical fads which in our laboratories 
 afford ateflimony of its decompolition — do not 
 thefe acquire a new force by the obfervation of 
 the preceding phenomena ? I conclude, there- 
 fore, that we ought to make a point of uniting 
 thefe two kinds of proofs : and a principle de- 
 duced from experiment is not, in my opinion, 
 demonftrable, until I fee that it may with fa- 
 cility be applied to the phenomena of art and 
 nature. Hence, if I find myfelf in a ftate of 
 hefitation between oppofite fyftems, I will de- 
 cide in favour of that whofe principles and ex- 
 periments adapt themfelves naturally, and 
 without force, to the greateft number of phe- 
 nomena. I will always diftruft a fingle fad, 
 which is applicable to no conclufion ; and I 
 will confider it as falfe, if it be in oppofition 
 to the phenomena which nature prefents to us. 
 
 It appears to me likewife that he who pro- 
 fefles to ftudy, or even to teach chenriftry, 
 ought not to endeavour to arrive at or exhibit 
 the whole which has been done in each depart- 
 ment > 
 
the Science of Chemijlry. 55 
 
 ment, or to follow the tedious progrefs of the 
 human mind from the origin of a difcovery to 
 the prefent time. This faftidious erudition is 
 fatiguing to the learner ; and thefe digreffions 
 ought in no cafe to be admitted in the enun- 
 ciation of fcience, excepting when the hiftori- 
 cal details afford interefting fadls, or lead us by 
 uninterrupted degrees to the prefent ftate of 
 our knowledge, It rarely happens, however, 
 that this kind of refearches, this genealogy of 
 fcience, affords us fuch characters ; and it ought 
 no more to be admitted, in general, that an 
 elementary writer fhould bring together and 
 difcufs every thing which has been done in a 
 fcience, than that he who undertakes to direct 
 a traveller fhould previoufly enter into a long 
 differtation on all the roads which have been 
 fucceffivtly made, and on thofe which ftill 
 exift, before he fhould point out the belt and 
 fhorteft way to arrive at the end of his journey. 
 It may, perhaps, be faid of the hiftory of 
 fcience, and more efpecially that cf chemiftry, 
 that it refembles the hiflories of nations. It 
 feldom affords any light refpedting the prefent 
 fituation of affairs ; exhibits many fables con- 
 cerning paft times ; induces a necellity of en- 
 tering into difcuflions upon the circumftances 
 that pafs in review ,* and fuppofes a mafs of 
 
 extra., 
 
$6 \ Method of Jiltdying 
 
 extraneous knowledge acquired on the part of 
 the reader, which is independent of the pur- 
 pofe aimed at in the ftudy of the elements of 
 chemiftry. 
 
 When thefe general principles, refpeding 
 the ftudy of chemiftry, are once well eftablifti- 
 ed, we may afterwards proceed in the chemical 
 examination of bodies in two ways : we may 
 either proceed from the ftmple to the com- 
 pound, or we may defcend from the compound 
 to the ftmple. Both thefe methods have their 
 inconveniences; but the greateft, no doubt, 
 which is found in following the firft method 
 is, that, by beginning with the fimpleft bo- 
 dies, we prefent fubftances to the confideration 
 of the learner which nature very feldom exhi- 
 bits in fuch a ftate of nakednefs and ftmplicity ; 
 and we are forced to conceal the feries of ope- 
 rations which have been employed to diveft 
 thefe fubftances from their combinations, and 
 reduce them to the elementary ftate. On the 
 other hand, if we prefent bodies to the view of 
 the learner fuch as they are, it is difficult to 
 fucceed in an accurate knowledge of them ; 
 becaufe their mutual addon, and in general 
 moft of their phenomena, cannot be underftood 
 without the previous and accurate knowledge 
 
 of 
 
the Science of Che mi fry* £*7 
 
 r of their conftituent principles, fince it is upon 
 thefe alone that they depend. 
 
 After having maturely confidered the advaiw 
 tages and inconveniences of each method, we 
 give the preference to the firft. We fhall 
 therefore begin by giving an account of the 
 feveral bodies in their moft elementary Hate, or 
 reduced to that term beyond which analyfis can 
 effed nothing; and, when we fhall have ex- 
 plained their various properties, we will com- 
 bine thefe bodies with each other, which will 
 afford a clafs of fimple compounds : and hence 
 we fhall rife by degrees to the knowledge of 
 bodies, and the mofb complicated phenomena. 
 We fhall be careful, in any examination of the 
 feveral bodies to which we fhall dired our re- 
 fearches, to proceed from known to unknown; 
 and our firft attention fhall be direded to ele* 
 mentary fubftances. But as it is impoffible, 
 at one and the fame time, to treat of all thofe 
 fubftances which the prefent ftate of our know- 
 ledge obliges us to confider as elementary, we 
 fhall confine ourfelves to the exhibition of fuch 
 as are of the greateft importance in the pheno- 
 mena of the globe we inhabit, fuch as are al- 
 moft univerfally fpread over its furface, and 
 fuch as enter as principles into the compofition 
 of the re-agents molt frequently employed in 
 
 our 
 
5 8 Method ofjludying 
 
 our operations; fuch, in a word, as we conti- 
 nually find in the examination and analyfis of 
 the component parts of the globe. Light, 
 heat, fulphur, and carbone are of this number. 
 Light modifies all our operations, and moll 
 powerfully contributes to the production of all 
 the phenomena which appertain to bodies ei- 
 ther living or inanimate. Heat, diftributed af- 
 ter an unequal proportion among all the bodies 
 of this univerfe, eftablifhes their various de- 
 grees of confiftence and fixity $ and is one of 
 the great means which art and nature employ 
 to divide and volatilize bodies, to weaken their 
 force or adhelion, and by that means prepare 
 them for analyfis. Sulphur exifts in the pro- 
 ducts of the three kingdoms ; it forms the ra- 
 dical of one of the beft known, and mo ft ge- 
 nerally employed, acids ; it exhibits intereft- 
 ing combinations with moft fimple fubftances ; 
 and, under thefe feveral points of view, it is 
 one of the fubftances the moft necelfary to be 
 known in the firft fteps of chemical fcience. 
 The fame may be faid of carbone; it is the 
 moft abundant fixed product: found in vegeta- 
 bles and animals. Analyfis has difcovered it 
 in fome mineral fubftances. Its combination 
 with oxygene is fo common in bodies, and in 
 the operations of art and nature, that there are 
 
 fear c el y 
 
I ~ 
 
 the Science of Chemiji ry . 59 
 
 fcarcely any phenomena which do not prefect 
 it to our view, and which confequently require 
 the knowledge of its properties. From all 
 thefe reafons it appears to us, that for the ad- 
 vancement of chemiftry it is neceilary our firft 
 proceeding fhould be founded on the know- 
 ledge of thefe fubftances ; and that we fhould 
 not diredl our attention to other fimple or ele- 
 mentary fubftances, accordingly as they pre~ 
 fent themfelves. 
 
 SEC. 
 
6o 
 
 Simple or Elementary Bodies, 
 
 SECTION IV. 
 
 Concerning Simple or Elementary Sub- 
 ftances. 
 
 ' • ♦ .1 , . # \ ^ J i * 
 
 TF we cad an eye over the fyftems which 
 have been fucceflively formed by philofo- 
 phers relative to the number and nature of the 
 elements, we fhall be aftonilhed at the prodi- 
 gious variety which prevails in their manner of 
 thinking. In the earlier times, every one feems 
 to have taken his own imagination for his 
 guide; and we find no reafonable fyftem until 
 the time when Ariftole and Empedocles ac- 
 knowledged as elements, Air, Water, Earth, 
 and Fire. Their opinion has been well receiv- 
 ed for many ages; and it muft be confefled that 
 it is calculated to feduce the mind. There 
 are, in fadt, enormous mafles, and inexhaufiible 
 fiores, that prefent themfelves to our view, of 
 thefe four principles, to which the deltrudtion 
 or decompofition of bodies appeared to refer all 
 the feveral component parts which formation 
 or creation had taken from them. The authori- 
 ty of all thole great men who had adopted this 
 fyfiem, and the analyfis of bodies which pre- 
 
 fentecl 
 
Simple or Elementary Bodies . 6 1 
 
 Tented only thefe four principles, afforded fuff 
 ficient grounds for admitting this docftrine. 
 
 But as foon as chemiftry had advanced fo far 
 as to difcover the principles of bodies, the pro- 
 feffors of that fcience prefumed to mark the 
 number, nature, and chara&er of the elements; 
 and every fubftance that was unalterable by 
 the chemical methods of decompofition, was 
 conftdered by them as a Ample or elementary 
 principle. By thus taking the limits of ana- 
 lyfis as the term for indicating the elements, 
 the number and the nature of thefe muff vary 
 according to the revolutions and the progrefs 
 of chemiftry. This has accordingly happened, 
 as may be feen by confulting all the authors 
 who have written on this fubjeff, from the time 
 of Paracelfus to the prefent day. But it muff 
 be confeffed that it is no fmall degree of ra(h~ 
 nefs, to affume the extent of the power of the 
 artift as a limit for that of the Creator, and to 
 imagine that the ftate of our acquifitions is a 
 ftate of perfect knowledge. 
 
 The denomination of Elements ought there- 
 fore to be effaced from a chemical nomencla- 
 ture, or at leaft it ought not to be ufed but as 
 an expreftion denoting the laft term of our ana- 
 lytical refults ; and it is always in this fenfe that 
 we fhall ufe the word. 
 
 CHAR 
 
Fire, or Heal > 
 
 62 
 
 CHAP. L 
 
 Concerning Fire. 
 
 T HE principal agent employed by nature 
 to balance the power and natural effect 
 of attraction, is fire. By the natural effeCt of 
 attraction we fhould poffefs none but folid and 
 compaCt bodies ; but the caloric unequally dif- 
 perfed in bodies tends incefTantly to deftroy 
 this adhefion of the particles; and it is to this 
 principle that we are indebted for the varieties 
 of confidence under which bodies prefentthem- 
 felves to our obfervation. The various fub- 
 ftances that compofe this univerfe are there- 
 fore fubjeCted, on the one hand, to a general 
 law which tends to bring them together ; and, 
 on the other hand, to a powerful agent which 
 tends to remove them from each other: it is 
 upon the refpeClive energy of thefe two forces 
 that the confidence of all bodies depends. 
 When the affinity prevails, they are in the fo- 
 lid date; when the caloric is mod powerful, 
 they are in the date of gas ; and the liquid date 
 appears to be the point of the equilibrium be- 
 tween thefe two powers. 
 
 It is therefore efTentially ncceflary to treat of 
 fire> fince it aCts fo leading a part in this uni- 
 verfe ; 
 
Fire . Heat . Light. 63 
 
 verfe; and becaufe it is impoflible to treat of 
 any fubftance whatever without attending to 
 the influence of this agent. 
 
 There are two things to be conlidered in fire 
 — heat and light. 
 
 Thefe two principles, which have been very 
 often confounded, appear to be very diftindt in 
 their own nature; becaufe they are fcarcely 
 ever proportional to each other, and becaufe 
 each can exiit without the other. 
 
 The tnoft ufuai acceptation of the word Fir£ 
 comprehends heat and light 5 and its principal 
 phenomena muff have been known for a long 
 time. The difcovery of fire muft have been 
 nearly as ancient as the human fpecies upon 
 this globe. The fhock.of two flints, the addon 
 of meteors, or the effedt of volcanoes, muft have 
 afforded the eariieft idea of it; and it is very 
 aftonifhing that the inhabitants of the Marian 
 I (lands were not acquainted with its effedts 
 before the invafion of the Spaniards. Thefe 
 iilanders, who became acquainted with this ter- 
 rible element only in confequence of its ra- 
 vages, confidered it at firft as a malevolent 
 being which attached itfelf to all beings, and 
 devoured them.— See the Abbe Raynal’s Hif- 
 toire Philofophique, &c. 
 
 The effects of fire are perhaps the moft afto- 
 nifhing 
 
Caloric and Heat . 
 
 64 
 
 nilhing of any which nature exhibits ; and we 
 ought not to be furprifed that the ancients 
 conlidered it as an intermediate being between 
 fpirit and matter, and have built the beautiful 
 fable of Prometheus upon its origin. We have 
 had the happinefs, in our time, to acquire well- 
 founded and exteniive ideas refpeddng this 
 agent, which we fhall proceed to develop in 
 the two following articles. 
 
 ARTICLE I. 
 
 Concerning Caloric and Heat. 
 
 When a metal or a liquid is heated, thefe bo- 
 dies are dilated in cverv direction, are reduced 
 to vapour, and at lafb- become invilible when 
 the molt powerful heat is applied to them. 
 
 Bodies which poflefs the principle of heat, 
 part with it more or lefs readily. If we atten- 
 tively obferve a body during its cooling, a flight 
 movement of undulation will be perceived in 
 the furrounding air ; an effedl which may be 
 compared to the phenomenon exhibited upon 
 the mixture of two liquors of unequal denfity 
 and weight. 
 
 It is difficult to conceive this phenomenon 
 without admitting of a peculiar fluid, which 
 pafies firfl: from the body\vhich heats to that 
 
 which 
 
General Properties of Heat . 65 
 
 which is heated, combines with the latter, pro- 
 duces the effects we have fpoken of, and after- 
 wards efcapes to unite with other bodies, ac- 
 cording to its affinities, and the law of equili- 
 brium, to which all bodies tend. 
 
 This fluid of heat, which we call Caloric, is 
 contained in greater or lefs quantities in bodies, 
 according to the greater or lefs degrees of affi- 
 nity exilting between it and them. 
 
 Various means may be employed to difplace 
 or difengage the caloric. The firft is by the 
 method of affinities : for example, water pour- 
 ed upon the fulphuric acid expels the heat, and 
 takes its place ; and while there is a difengage- 
 ment of heat, the volume of the mixture does 
 not increafe in proportion to the bulk of the 
 two fubftances mixed. This fhews that pene- 
 tration takes place, which cannot be explained 
 but by admitting that the integrant parts of the 
 water take the place of the caloric, in propor- 
 tion as it is diffipated. — The fecond method of 
 precipitating caloric, is by friction and com- 
 preffion. In this cafe it is expreffed orfqueezed 
 out, in the fame manner as water from a fponge. 
 In reality, the whole of the heat whith may be 
 produced by fridiion, is not afforded by the 
 body itfelf ; becaufe, in proportion as the in- 
 terior heat is developed, the external air adts 
 Vol. I. F upon 
 
66 General Properties of Heat • 
 
 upon the body, calcines or inflames it, and itfelf 
 gives out heat during its fixation. Fermenta- 
 tion, and in general every operation which 
 changes the nature of bodies, may difengage 
 caloric, becaufe the new compound may de- 
 mand and receive a greater or lefs quantity. 
 Hence it is that chemical operations produce 
 fometimes cold, and fometimes heat. 
 
 Let us now examine the form under which 
 caloric prefents itfelf. 
 
 This fluid is difengaged either in a ftate of 
 liberty, or in a ftate of combination. 
 
 In the firft cafe, the caloric always endea- 
 vours to obtain an equilibrium ; not that it is 
 diftributed equally among all bodies, but it is 
 difperfed among them according to the degrees 
 of its affinity. Whence it follows, that the cir- 
 cumambient bodies receive and retain a quan- 
 tity more or lefs confiderable. Metals are eaft- 
 ly penetrated by this fluid, and tranfmit it with 
 equal facility; wood and animal fubftances re- 
 ceive it to the degree of combuftion ; liquids^ 
 until they are reduced to vapour. Ice alone 
 abforbs all the heat communicated to it, with- 
 out giving it out to other bodies until it has 
 acquired the fluid ftate*. 
 
 * The ingenious author has inadvertently been guilty of 
 an overfight. Not only ice, but all other bodies, abforb heat 
 during liquefaction, as he himfelf Ihews hereafter. T. 
 
 The 
 
Admeasurement of Heat . 67 
 
 The degree of heat can be appreciated only 
 by its effecfis : and the infiruments which have 
 been fucceflively invented to calculate it, and 
 are known by the names of thermometers, py- 
 rometers, &c. have been applied to the firidt 
 determination of the feveral phenomena exhi- 
 bited in confequence of the abforption of calo- 
 ric in various bodies. 
 
 The dilatation of fluids, or of metals in the 
 fluid flate, by the feveral degrees of heat, has 
 been long meafured by thermometers formed 
 of glafs; but this very fuflble fubflance can 
 only be ufed to afcertain degrees of heat infe- 
 rior to that which renders the glafs itfelf fluid. 
 
 Several means have been fucceflively pro- 
 pofed for calculating the higher degrees of heat. 
 Mr. Leidenfrofl: has proved that the hotter a 
 metal is, the more llowly will drops of water 
 evaporate from its furface; and he has propofed 
 this principle for the conftrudiion of pyrome- 
 ters. A drop of water in an iron fpoon, heated 
 to the degree of boiling water, evaporates in one 
 fecond ; a flmilar drop, poured on melted lead, 
 is diflipated in fix or feven feconds; and upon 
 red-hot iron in thirty. Mr. Ziegler, in his 
 Specimen de Digeflore Papini, has found that 
 89 feconds were required to evaporate a drop of 
 water at 520 degrees of Fahrenheit; and that 
 F 2 one 
 
68 
 
 Admeafunment of Heat „ 
 
 one fecond is fufficient at the 30odth degree. 
 This phenomenon, which is more interefting to 
 chemiftry than pyrometry, to which it will al- 
 ways afford refults little fufceptible of rigorous 
 calculation, appears to me to depend upon the 
 adhefion and decompofition of the water upon 
 the metal. 
 
 The moft accurate pyrometer we are ac- 
 quainted with, is that which was prefented to 
 the Royal Society of London by Mr. Wedg- 
 w'ood. It is conftru&ed upon the principle, 
 that the pureft clay fhrinks in the fire in pro- 
 portion to the heat applied to it. This pyro- 
 meter confifts of two parts; one called the 
 gauge, which ferves to meafure the degrees of 
 diminution or fhrinking; the other contains 
 the fimple pieces of pure clay, which are called 
 thermometer pieces. 
 
 The gauge is formed of a plate of baked earth, 
 upon which are applied two rulers or ftraight 
 pieces of the fame fubftance. Thefe rulers, 
 being perfectly ftraight and even, are placed at 
 the diftance of half an inch from each other at 
 one of their ends, and three-tenths of an inch 
 at the other. For greater convenience, the 
 gauge is divided into two parts, and the two 
 pieces are placed endways when required to be 
 ufed. The length of this rule is divided into 
 
 240 
 
 j 
 
Wedgwood' s Thermometer . 69 
 
 240 equal parts, of which each reprefents one- 
 tenth of an inch # . To form the thermometer 
 pieces, the earth is lifted with the greateft at- 
 tention, after which it i£ mixed with water, 
 and the pafte thruft through an iron tube, 
 ■which gives it a cylindrical form, to be cut 
 afterwards into pieces of a proper flze. When 
 the pieces are dry, they muft be prefented to 
 the gauge, where they ought to fit at the place 
 of o on the fcale. If by inadvertence of the 
 workmen any piece penetrates to one or two 
 degrees further, this degree is marked on its 
 flat furface, and requires to be deduced when 
 the piece is ufed in the admeafurement of heat. 
 The pieces thus adjufledare baked in a furnace 
 to a red heat, to give them the confluence ne- 
 ceflary for carriage. The heat employed in 
 this part of the procefs is ufually about flx de- 
 grees, and the pieces are diminifhed more or 
 lefs; but this is of no confequence when they 
 come to be fubmitted to a fuperior degree of 
 heat; and if it Ihould happen that an inferior 
 degree of heat is required to be meafured, un- 
 baked pieces are to be ufed, which are pre- 
 ferved in fheaths or cafes to avoid fri&ion. 
 
 When this pyrometer is to be ufed, one of 
 
 * This is, in fad, the twelve- hundredth of an inch in the 
 width, according to the dimenfions here given. T. 
 
 the 
 
7 ° 
 
 Wedgwood's Thermometer. 
 
 the pieces is expofed in the fire-place whofe 
 heat is required to be determined ; and when it 
 has acquired the whole intenfity, it is taken out, 
 and fuffered to cool, or for greater fpeed it is 
 plunged in water; after which it is prefented to 
 the gauge, and its degree of contraction eafily 
 determined. Mr.Wedgwood has given us the 
 refult of feveral experiments made with his 
 pyrometer, oppolite to which he has placed 
 the correfpondent degrees of Fahrenheit, 
 
 Pyrometer Thermometer 
 of Weogwood. ot Fahreuheit. 
 
 Red heat vifible by the light 
 Brafs melts at 
 Swedilh copper melts at 
 Tare filver melts at - - 
 
 Pure gold melts at 
 
 The heat of bars of iron raifed f fmall bar - 
 to welding - l large bar 
 
 The greateft heat producible in a fmith’s forge 1 25 
 Caft iron melts at - - 130 
 
 2 ! 
 
 2 7 
 
 28 
 
 3 2 
 90 
 9S 
 
 1077 
 
 i8 57 
 
 4557 
 
 47*7 
 
 5 2 37 
 
 12777 
 
 1 34-7 
 *7327 
 1 797 7 
 
 160 - 2i $n 
 
 The greateft heat of a wind furnace of 
 eight inches fquare 
 Thefe various thermometers are not appli- 
 cable to all cafes. We cannot, for example, 
 -calculate with ftri&nefs the heat which efcapes 
 from living bodies, or determine with precifion 
 the temperature of any fubftance, But MelTrs. 
 De la Place and Lavoilier (Acad, des Sciences, 
 1780) have invented an apparatus which ap- 
 pears to leave nothing further to bedefired. It 
 
 is 
 
The Calorimeter of Lavoifier , £s?r. 7 1 
 
 \ 
 
 is conftruded upon the principle that ice ab- 
 sorbs all the heat communicated to it, without 
 communicating it to other bodies until the 
 whole is melted j fo that from hence w'e may 
 calculate the degrees of heat communicated, by 
 the quantity of ice which is melted. It was ne- 
 ceflary, in order to afford fluid refults, to difco- 
 ver the means of caufing the ice to abforb all 
 the heat difengaged from the bodies under ex- 
 amination, and to cover it from the aclion of 
 every other fubflance which might facilitate its 
 fufion ; and, laftly, to colled: with great care 
 the water produced by the fufion. 
 
 The apparatus conftruded by thefe two ce- 
 lebrated academicians for this purpofe, coniifts 
 of three circular velfels nearly infcribed in each 
 other; fo that three capacities are produced. 
 The interior fpace or capacity is formed by an 
 iron grating, upon fupports of the fame metal. 
 Here it is that the bodies fubjeded to experi- 
 ment are placed. The upper part of this ca- 
 vity is clofed by means of a cover. The mid- 
 dle fpace, next to this, is defigned to contain 
 the ice which furrounds the interior compart- 
 ment. This ice is fupported and retained by a 
 grate, upon which a cloth is fpread. In propor- 
 tion as the ice melts, the water flows through 
 the grate and the cloth, and is colleded in a 
 
 veffel 
 
72 T'he Calorimeter of 
 
 veffel placed beneath. Laflly, the external 
 fpace or compartment of the apparatus contains 
 ice intended to prevent the effedt of the ex- 
 ternal heat of the atmofphere. 
 
 To ufc this excellent machine, the middle or 
 fecond fpace is filled with pounded ice, as is like- 
 wife the cover of the internal fphere ; the fame 
 thing is done with regard to the external fpace, 
 as well as to the general covering of the whole 
 machine: the interior ice is fuffered to drain ; 
 and, when it ceafes to afford water, the cover- 
 ing of the internal fpace is raifed, to introduce 
 the body upon which the experiment is intended 
 to be made. Immediately after this introduc- 
 tion, the covering is put on, and the whole ap- 
 paratus remains untouched until the included 
 body has acquired the temperature of o, or the 
 freezing temperature of water, which is the 
 common temperature of the internal capacity. 
 The quantity of water afforded by the melting 
 of the ice is then weighed ; and this is an ac- 
 curate meafure of the heat difengaged from the 
 body, becaufe the fufion of the ice is theeffedt 
 of this heat only. Experiments of this kind 
 laft fifteen, eighteen, or twenty hours. 
 
 It is of great confequence, that in this ma- 
 chine there fhould be no communication be- 
 
 tween 
 
Lavcificr and Be la Place. 73 
 
 tween the middle, or fecond, and the external 
 fpace. 
 
 It is likewife neceflary that the air of the 
 apartment fhould not be lower than o, becaufe 
 the interior ice would then receive a degree of 
 coid lower than that temperature. 
 
 Specific heat is merely the proportional quan- 
 tity of heat neceflary to raife bodies of equal 
 mafs to the fame number of degrees of tem- 
 perature : fo that, when the fpecific heat of a 
 . folid body is required, its temperature mult be 
 elevated a certain number of degrees, at which 
 inftant it muft be placed in the internal fphere, 
 and there left until its temperature is reduced 
 to o. The water is then collected, and this 
 quantity divided by the product of the mafs of 
 the body ; and the number of degrees of its 
 original temperature above o, will be propor- 
 tional to its fpecific heat. 
 
 With regard to fluids, they are inclofed in 
 veffels whofe heat has been previoufly deter- 
 mined. The operation is then the fame as for 
 folids ; excepting that the quantity of water 
 afforded muft be diminifhed by a deduction of 
 that quantity which has been melted by the 
 heat of the veflel. 
 
 If it be required to determine the heat which 
 is difengaged during the combination of various 
 
 fubftances. 
 
74 The Calorimeter of Lavoifier y &c, 
 
 fubftances, they muft be all reduced, as well as 
 their containing veffels, to the temperature of 
 o. The mixture mull then be placed in the 
 internal fphere ; and the quantity of water col- 
 lected is the meafure of the difengaged heat. 
 
 In order to determine the heat of combuf* 
 tion and refpiration, as the renewal of air is in. 
 difpenfable in thefe two operations, it is necef- 
 fary to eftablifh a communication between the 
 internal part of the fphere and the furrounding 
 atmofphere ; and in order that the introduction, 
 of frefh air may not caufe any perceptible error, 
 thefe experiments ought to be made at a tercu 
 perauure little differing from o, or at leafi the 
 air which is introduced muff previoufly be 
 brought to this temperature. 
 
 To determine the fpecific heat of any gas, it 
 is neceffary to eftablifh a current through the 
 internal part of the fphere, and to place two 
 thermometers, one at the place of introduction, 
 and the other at the place of efcape. By com- 
 parifon of the temperatures exhibited by thefe 
 two inftruments, a judgment is formed of the 
 heat abforbed,and the melted ice is meafured. 
 
 An excellent memoir of Meffrs. De la Place 
 and Lavoifter may be confulted for the refults 
 of the experiments they have made. The pre. 
 fent extra& contains only a ihort account of 
 their valuable labours. 
 
 The 
 
General 'Properties of Heat. 75 
 
 The various means made ufe of for the ad^ 
 meafurement of heat, are founded on the ge^ 
 neral principle, that different bodies abforb 
 heat in greater or lefs quantities. If this fait 
 were not generally admitted, it might be efta- 
 blifhed on the three following fads. Dr. Frank- 
 lin having expofed two fmall pieces of cloth, 
 of the fame texture but of different colours, 
 upon the furfaee of fnow, perceived a few 
 hours afterwards, that the red cloth was bu- 
 ried in the fnow, while the other which was 
 white had not fuffered any depreflion*. M. de 
 Saulfure obferves, that the peafants of the 
 mountains of Switzerland are careful to fpread 
 a black earth over the furfaee of grounds co- 
 vered with fnow, when they are deflrous of 
 melting it to fow their feed. So likewife chil- 
 dren burn a black hat in the focus of a fmall 
 lens which would fcarcely heat a white one. 
 
 Such nearly are the phenomena of heat when 
 it is difengaged in a hate ot liberty. Let us 
 now contemplate thofe which it prefents when 
 it efcapes from a date of combination. 
 
 Heat is fometimes difengaged in a date of 
 Ample mixture, as in the phenomena of va- 
 pours, fublimations, &c. If heat be applied to 
 water, thefe two fluids will unite, and the mix- 
 
 * They were expofed to the rays of the fun. T. 
 
 ture 
 
76 General Properties of Heat. ) 
 
 turc will be diffipated in the atmofphere ; but 
 it would be an abufe of words to call fo weak 
 an union by the name of combination : for, as 
 foon as the heat becomes in a fituation to com- 
 bine with other bodies, it abandons the water* 
 which returns to a liquid ftate. This body, dur- 
 ing evaporation, continually carries with it a 
 portion of heat; and hence, perhaps, refult the 
 advantages of tranfpiration, perfpiration, &c. 
 
 But heat very frequently contracts a true 
 chemical union with the bodies which it vola- 
 tilizes : this combination is even fo perfed, 
 that the heat is not perceptible, but it is neu- 
 tralized by the body with which it is combined. 
 It is then called latent heat, calor latens . 
 
 The feveral cafes in which heat enters into 
 combination, and paftes to the ftate of latent 
 heat, may be reduced to the two following 
 principles ; 
 
 The firft principle. — Every body which paffes 
 from the folid to the liquid ftate, abforbs a por- 
 tion of heat, which is no longer fenfible to the 
 thermometer, but exifts in a true ftate of com- 
 bination. 
 
 The academicians of Florence filled a veftel 
 with pounded ice, and plunged a thermometer 
 in it, which defcended to o. The velfel was 
 then immerfed in boiling water, and the ther- 
 
 mometer 
 
General Properties of Heat. 77 
 
 i‘ mometerdid not rife during the whole time of 
 I the liquefa&ion of the ice. The fufion of ice 
 [ therefore abforbs heat. 
 
 Mr. Wilcke poured a pound of water, heated 
 to the 60th degree of Reaumur, upon a pound 
 of ice. The melted mixture poffefled the tem- 
 perature of o. Sixty degrees of heat had there- 
 fore entered into combination. 
 
 The chevalier Laudriani has fhewn that the 
 1 fufion of metals, of fulphur, of phofphorus, 
 of alum, of nitre > &c. abforbs heat. 
 
 Cold is produced in the difiolution of all the 
 (cryftallized) falts. 
 
 Reaumur made a feries of very interefting ex- 
 periments on this fubjedt, which confirm thofe 
 of Boyle. Fahrenheit caufed the thermometer 
 to defeend to forty degrees, by melting ice by 
 ftrong nitrous acid. But the moft afionifhing 
 experiments are thofe made by MefTrs. Thomas 
 Beddoes*, phyfician, and Walker, apothecary 
 at Oxford, and inferted in the Philofophical 
 Tranfadtions for the year 1 7 87 The mixtures 
 which produced the greateft degrees of cold are, 
 
 * It does not appear that Dr. Beddoes either had or pre- 
 tends to have any other {hare in the experiments of Mr. 
 Walker, than that of having tranfmitted them to the Royal 
 Society. T- 
 
 ' + Alfo in the fubfequent volumes. 
 
 1. Eleven 
 
7 8 General Properties of Heat; 
 
 1. Eleven parts of muriate of ammoniac, or 
 common fal ammoniac; ten parts of nitrate of 
 pot-alh, or common nitre j fixteen parts of ful- 
 phate of foda, or Glauber’s fait ; with thirty- 
 two parts by weight of water : the two firft 
 falts fhould be dry, and in powder. 2. The 
 nitric acid, muriate of ammoniac, and fulphate 
 of foda, lowered the thermometer to eight de- 
 grees under o. Mr. Walker has frozen mer- 
 'cury without uling either ice or lhow. 
 
 Jt is therefore an incontrovertible principle, 
 that all bodies w'hich pafs from the folid to the 
 liquid flate, abforb heat, and retain it in fo 
 accurate a combination as to afford no fign of 
 its prefencei The heat is therefore fixed, neu- 
 tralized, or latent. 
 
 The fecond principle. — All bodies, by pair- 
 ing from the folid or fluid (late to the aeri- 
 form ftate, abforb heat, which becomes latent; 
 and it is by virtue of this heat that fuch bodies 
 are placed and maintained in that Hate. 
 
 On this principle is founded the procefs 
 ufed in China, India, Perfia, and Egypt, to 
 cool liquors ufed for drink. 
 
 The water intended for this purpofe is put 
 into very porous velfels, and expofed to the fun, 
 or to a current of warm air, to cool the fluid 
 contained within them. 
 
 It 
 
General Properties of Heat. 79 
 
 It is by fimilar means that cool drink is 
 obtained in the long journeys of the caravans, 
 Interefling details on this fubjedl may be feen 
 in the Travels of Chardin, vol. iii. 1723 ; 
 Tavernier’s Voyages, vol. i. edit. 1738; Paul 
 Lucas’s Voyages, vol. ii. edit. 1724; and alfo 
 in the Mundus Subterraneus of P. Kircher, 
 lib. vi. fee. 2. cap. 2. 
 
 We may conclude from the experiments of 
 Mr. Richmann, made in 1747, and inferted in 
 the firft volume of the Imperial Academy of 
 Peterfburgh, 1 . That a thermometer taken out 
 of water, and expofed to the air, always de- 
 feends, even when its temperature is equal or 
 fuperior to that of the water. 2. That it after- 
 wards rifes, until that it has acquired the tem- 
 perature of the atmofphere. 3. That the time 
 of defeending is lefs than that which it em- 
 ploys to rife again. 4. That when the ther- 
 mometer, withdrawn from the water, has arifen 
 to the common temperature, its bulb is dry ; but 
 that it continues wet during the whole time of 
 its Handing beneath this common temperature. 
 
 To thefe confequences we will add others 
 deduced from feveral curious experiments by 
 the celebrated Cullen. 1. A thermometer fuf- 
 pended in the receiver of the air pump, de- 
 feends two or three degrees during the time of 
 
 exhatiftion. 
 
So General Properties of Heat . 
 
 exhauftion, and afterwards rifes to the tempera- 
 ture of the vacuum. 2. A thermometer plunged 
 in alcohol, in the receiver of the air pump, al- 
 ways defeends, and the lower in proportion as 
 the bubbles are flronger which ifTue from the 
 alcohol ; if it be withdrawn from this liquor, 
 and fufpended wet beneath the receiver, it falls 
 eight or ten degrees w’hile the air is pumping 
 out. 
 
 It is well known that if the ball of a ther- 
 mometer be wrapped in fine linen, and kept 
 moift by fprinkling with ether, and the evapo- 
 ration be facilitated by agitation in the air, the 
 thermometer will defeend to o. 
 
 The immortal Franklin has proved, in his 
 own perfon, that when the body perfpires ftrong- 
 ly, it is lefs heated than furrounding bodies, and 
 that perforation always produces a certain de- 
 gree of coldnefs. — See his Letter to Dr. Lind. 
 
 The great number of labourers in the burn- 
 ingheatsof our climate fupport themfelves only 
 by virtue of a copious perfpiration, the fluid for 
 which they replenish by drinking plentifully. 
 The workmen employed in glafs-houfes, foun- 
 deries, &c. often live in a medium hotter than 
 their bodies, the natural temperature of which 
 is equalized and moderated by perfpiration. 
 
 If evaporation be increafed by agitation of 
 
General Properties of Heat . 81 
 
 the air, the refrigeration is the greater. Hence 
 the ufeof fans, ventilators, &c. which, though 
 intended to give motion to warm air, afford 
 likewife the virtue of cooling by facilitating 
 and favouring evaporation. 
 
 Warm and dry air is beft fuited to form a 
 refrefhingcurrent, becaufeit is more calculated 
 to diffolve and abforb humidity ; moift air is 
 Jefs proper, becaufe it is already faturated. — 
 Hence the neceflity of frequently renewing the 
 air to preferve the coolnefs of our apartments. 
 
 Thefe principles have a nearer relation to 
 medicine than is generally fuppofed. We find 
 that almoft all fevers end in perforations, 
 which, befide the advantage of expelling the 
 morbific matter, poffefs likewife that of car- 
 rying off the matter of heat, and reftoring the 
 body to its common temperature. The phyfi- 
 cian who is defirous of moderating the excefs 
 of heat in the body of a patient, ought to 
 maintain the air in that difpofition which is 
 moft fui table to his views. 
 
 The ufe of volatile alkali is univerfally ac- 
 knowledged to be of advantage in burns, the 
 tooth-ach, &c. May not thefe effects be attri- 
 buted to the volatility of this fubftance, which 
 quickly combining with heat, carries it off, and 
 leaves an impreffion of cold ? — Ether is a fove- 
 Vol. I. G reign 
 
82 
 
 General Properties of Heat. 
 
 reign remedy for the colic. Does not its vir- 
 tue depend on the fame principles ? 
 
 The heat which has entered into combination 
 with bodies during their tranlition from the 
 folid to the liquid {fate, or from this laft to the 
 aeriform ftate, may be again exhibited by caus- 
 ing thefe fubftances to return again to the Hates 
 of liquefaction or folidity. In a word, every 
 fubftance which pafies from the liquid to the 
 folid ftate, fuffers its latent heat to efcape, 
 which at this inftant becomes free or thermo- 
 metrical heat. 
 
 The celebrated Fahrenheit, in the year 1724, 
 having left water expofed to a colder tempera- 
 ture than that of ice, the water remained fluid: 
 but it congealed by agitation ; and the thermo- 
 meter, which marked feveral degrees beneath 
 the freezing point, fuddenly rofe to that tem-^ 
 perature. Mr. Treiwald mentions a ftmilar 
 iadl in the TranfaClions ; and Mr. De Ratte 
 made the fame obfervation at Montpelier. 
 
 Mr. Baume has fhewn, in his enquiries and 
 experiments relating to feveral lingular pheno- 
 mena exhibited by water at the inftant of its 
 congelation, that feveral degrees of heat areal- 
 ways developed at that inftant. 
 
 Gafeous fubftances are maintained in the 
 aeriform ftate merely by the heat which is com- 
 bined 
 
Properties of Light. 83 
 
 bincd with them; and when to thefefubftances, 
 thus diflolved in caloric, another body is pre- 
 fented, to which they have a very ftrong affinity, 
 they abandon their heat to unite with this laft 
 fubftance; and the caloric, thus expelled ordif- 
 engaged, appears under the form of free or ther- 
 mometrical heat. This difengagement of heat, 
 by the concretion or fixation of gafeous fub- 
 ftances, was obferved by the celebrated Scheele, 
 as may be feen in the valuable experiments 
 which form the bafis of his Treatife on Air and 
 Fire. Since the time of this great man, rigo- 
 rous calculations have been made of the quan- 
 tity of latent heat exifting in each of thefe gafes : 
 we are indebted to Meflrs. Black, Crawford, 
 Wilcke, De la Place, La voifier, &c. for many 
 excellent refearches on this fubjedh. 
 
 ARTICLE IL 
 
 Concerning Light. 
 
 It appears that Light is tranfmitted to our 
 eyes by a peculiar fluid which occupies the in- 
 terval between us and vifible bodies. 
 
 Does this fluid arrive diredly from the Sun 
 by fuccefflve emiffions or eradiations ? or is it 
 G 2 a pecu- 
 
u 
 
 Properties of Light. 
 
 a peculiar fluid diftributed through fpace, and 
 put in adtion by the Sun’s rotary motion, or by 
 any other caufe ? I fhall not enter into any dif- 
 cutfion upon this fubjeCt, but fhall confine my- 
 felf to point out the phenomena. 
 
 A. The motion of light is fo rapid, that it 
 paffes through nearly eighty thoufand leagues 
 in a fee ond. 
 
 B. The elafticity of the rays of fight is fuch, 
 that the angle of reflection is equal to the angle 
 of incidence. 
 
 C. The fluid of light is ponderous ; for if a 
 ray of light be received through a hole in a win- 
 dow-fhutter, and the blade of a knife be pre- 
 fented to it, the ray is diverted from a right line, 
 and is infledted towards the body. This cir- 
 cumftance fhevvs that it obeys the law of at- 
 traction, and fufficiently authorifes us to clafs 
 it among other bodies of this nature. 
 
 D. The great Newton fucceeded in decom- 
 pofing the folar light into feven primitive rays, 
 which prefent themfel ves in the following order: 
 red, orange, yellow, green, blue, indigo, violet* 
 Dyes prefent us with only three colours, which 
 are red, blue, and yellow ; the combinations 
 and proportions of thefe three principles form 
 all the fhadesof colour with which the arts are 
 enriched. Philofophers have maintained that 
 
 among 
 
General Properties of Light . 85 
 
 among the folar rays there are three primitive 
 colours,— See Les Recherches de M. Marat. 
 
 All natural bodies may be confidered as 
 prifms which decompofe or rather divide the 
 light. Some refledt the rays without producing 
 any change, and thefe are white ; others abforb 
 them all, and caufe abfolute blacknels : the 
 greater or lefs affinity of the feveral rays with 
 various bodies, and perhaps likewife the difpo- 
 fition of the pores, is no doubt the caufe that, 
 when a pencil falls upon a body, fome rays en- 
 ter into combination, while others are refledl- 
 ed ; and it is this which affords the diversity of 
 colours, and the prodigious variety of {hades 
 under which bodies appear to our eyes r 
 
 We can no longer confine ourfelves to con- 
 fider light as a merely phyfical fubftance; the 
 chemift perceives its influence in moll of his 
 operations, and finds it neceflary to attend to 
 its affion, which modifies his refultsi and its 
 effedls are no lefs evident ih the various phe- 
 nomena of nature, than in the experiments per- 
 formed in our laboratories. 
 
 We fee that vegetation cannot take place 
 without light. Plants deprived of this fluid 
 become pale ; and when in hot-houfes the light 
 comes to them from one part only, the vege- 
 tables incline towards the aperture, as if to 
 fnew the neceffity of this beneficial fluid. 
 
 Without 
 
86 Properties and Effefts of Light. 
 
 Without the influence of light, vegetables 
 would exhibit but one lifelefs colour; they are 
 deprived of their beautiful (hades by the inter- 
 ception of this luminous fluid. On thefe prin- 
 ciples, celery, endive, and other plants, are 
 bleached. 
 
 Vegetables are not only indebted to the light 
 for their colour, but likewife for their fmell, 
 tafte, combuftibility, maturity, and the refinous 
 principle, which equally depend upon this fluid. 
 Hence it is, no doubt, that aromatic fubftances, 
 refins, and volatile oils, are the inheritance of 
 fouthern climates, where the light is more pure, 
 conftant, and intenfe. 
 
 We fee, likewife, that the influence of light 
 is evident in other beings : for, as Mr. Dorthes 
 has obferved, worms and grubs, which live in 
 the earth or in wood, are of a whitifh colour. 
 The birds and flying infers of the night are 
 likewife diftinguifhable from thofe of the day 
 by the want of brilliancy of colour ; and the 
 difference is equally marked between thofe of 
 the north and of the fouth. 
 
 A very aftonilhing property of light upon the 
 vegetable kingdom is, that when vegetables 
 are expofed to open day-light, or to the fun’s 
 rays, they emit vital air. We fhall again attend 
 to all thefe phenomena when we come to treat 
 of the analyfis of vegetables. 
 
 The 
 
87 
 
 Properties and Effefts of Light. 
 
 The fine experiments of Scheele and Ber- 
 thollet have fhewn that the abfence or prefence 
 of light has an aftonifhing effedt upon the re- 
 fult of chemical experiments. Light difen- 
 gages vital air from feveral fluids, fuch as the 
 nitric acid, the oxigenated marine acid, &c. 
 It reduces the oxides or calces of gold, filver, 
 &c. It changes the nature of oxigenated mu- 
 riates, according to the obfervations of Mr. 
 Berthollet. Light likewife determines the phe- 
 nomena of vegetation exhibited by faline fo- 
 lutions, as I have fhewn. From all which cir- 
 cumftances it is evident that we ought to at- 
 tend to the effedt of this agent in almofl: all 
 our operations. 
 
 tc Organization, fenfation, fpontaneous mo- 
 tion, and life, exifl: only at the furface of the 
 earth, and in places expofed to light : we might 
 affirm that the flame of Prometheus’s torch 
 was the expreflion of a philofophical truth 
 which did not efcape the ancients. Without 
 light, nature was lifelefs, inanimate, and dead : 
 a benevolent God, by. producing light, has 
 fpread organization, fenfation, and thought 
 over the furface of the earth.” — Elementary 
 Treatife of Chernifiry by Mr. Lavoifier. 
 
 We ought not to confound the folar light 
 with the light of our furnaces ; the light of 
 
 thefe 
 
8 $ 
 
 Sulphur . 
 
 thefe has, as I am convinced, very evident ef- 
 fects in certain phenomena; but thefe effects 
 are flow, and fcarcely comparable with thofe 
 of the folar light. 
 
 Although heat often accompanies light, the 
 phenomena we have mentioned cannot be at- 
 tributed to mere heat. Heat may indeed mo- 
 dify them where it exifts, but moft affuredly 
 it cannot produce them. 
 
 Concerning Sulphur . 
 
 E are obliged to place Sulphur among 
 
 the elements, though our predecefiors 
 pretended to have determined its conftituent 
 principles. This proceeding would appear to 
 be retrograde, if it were not evident that the 
 correction of miftakes is a real advancement 
 in fcience. 
 
 The ancients ufed the word fulphur to de- 
 note every combuftible and inflammable fub- 
 ftance. Accordingly we find, in all their writ, 
 ings, the expreffions of fulphur of metals, ful- 
 phur of animals, fulphur of vegetables, &c. 
 
 Stahl affigneth a determinate value to the de- 
 nomination of Sulphur ; and lince the time of 
 
 CHAP. II. 
 
 this 
 
Origin of Sulphur * 89 
 
 this celebrated chemift we have confined the 
 name to denote a body of an orange-yellow 
 colour, dry, brittle, capable of burning with a 
 blue flame, and exhaling a penetrating odour 
 during combuftion : when rubbed, it becomes 
 eledtric; and by a light prefllire in the hand it 
 cracks, and becomes reduced to powder. 
 
 It appears that fulphur is formed by the de-r 
 compofition of vegetables and animals. It has 
 been found on the walls of neceflary-houfes ; 
 and when the ditch of the Port St. Antoine, at 
 Paris, was cleared, a coniiderable quantity was 
 colle&ed, which was mixed with the decayed 
 remains of vegetable and animal fubftances, that 
 had filled the ancient ditches, and there putre- 
 fied. 
 
 Mr. Deyeux has likewife proved, that ful- 
 phur exifts naturally in certain plants, fuch as 
 patientia, cochlearia, &c. His procefies for 
 extra&ing it confifl in — 1. The wafhed root 
 muft be reduced by rafping into a fine pulp; 
 this muft be wafhed in cold water, and pafted 
 through a fieve or cloth of an open texture ; 
 the fluid paffes in a turbid ftate, and depofits a 
 precipitate, which when dried proves the exift- 
 ence of fulphur. 2. The pulp may be boiled, 
 and the feum afforded by the ebullition after- 
 wards dried : this feum contains fulphur. Se- 
 veral 
 
<90 Procejfes for extra Sting 
 
 vcral fpecies of rumex, confounded under the 
 name of Patience, do not contain fulphur. I 
 have obtained it from the rumex patientia L. 
 which grows on the mountains Ceverines, and 
 is the fame which is ufed at Paris. M. Le 
 Veillard obtained fulphur by fuffering vegetable 
 fubftances to putrefy in well-water. Sulphur is 
 abundantly contained in coal mines; it is found 
 in combination with certain metals; it appears 
 alrnoft always where vegetable decompofition 
 takes place ; it forms the greater part of thofe 
 pyritous and bituminous fchifti which occupy 
 the focus of volcanos ; it is fublimed in thofe 
 places w’here the pyrites are decompofed ; it is 
 thrown out by fubterraneous fires; and is found 
 in greater or lefs quantities in volcanic diftri&s. 
 Much has been faid concerning (bowers of ful- 
 phur; but it is at prefent w’ell known that this 
 error has chiefly arifen from the powder of the 
 (lamina of the pine, which is carried to great 
 diflances. Henckel faw the furface of a marfh 
 entirely covered with this pow r der. 
 
 The known proceffes for extracting fulphur 
 in the large way, and applying it to the pur- 
 pofes of commerce, confifl in difepgaging it 
 from the pyrites or fulphures of copper, or of 
 iron, by methods poffe fling various degrees of 
 (implicity and economy. On this fubject, the 
 
 Pyritology 
 
Sulphur in the large Way . 91 
 
 Pyritology of Henckel, Macquer’s Chemical 
 Dictionary, and the Metallurgical Tracts of 
 Mr. Jars, may be confuted. 
 
 In Saxony and Bohemia the ores of fulphur 
 are diddled in earthen tubes difpofed in a gal- 
 lery. The fulphur which is difengaged by the 
 heat paffes into receivers placed without, and 
 in which care is taken to keep a fufficient 
 quantity of water. 
 
 At Rammelfberg, at St. Bel, &c.. large heaps 
 of pyrites are made, which are decompofed by a 
 gentle heat, at firft applied to the .mafs from a 
 ftratum of combuftible matter upon which it is 
 placed. The heat is afterwards kept up by the 
 adlion of the pyrites among!! each other. The 
 fulphur which exhales cannot efcape laterally, 
 becaufe care is taken to cover the fides with 
 earth. It therefore rifes to the fummit of the 
 truncated pyramid, where it is collected into 
 fmall cavities made for that purpofe. The heat 
 of this part is fufficient to keep the fulphur in 
 a fluid flate; and it is taken out from time to 
 time with ladles. 
 
 Almofl all the fulphur ufed in France comes 
 from theSolfatara. This volcanic country every 
 where exhibits marks of th'e agency of fubter- 
 raneous lire. The enormous mafles of pyrites 
 which are decompofed in the bowels of the 
 earth produce heat, which fublimes part of the 
 
 fulphur 
 
92 Procejjes for extracting Sulphur . 
 
 fulphur through apertures which the fire, and 
 the effort of the vapours, have opened in all 
 parts. The earths and flones which contain 
 fulphur are diflilled ; and it i the refultof this 
 diflillation which is called Crude Sulphur. 
 
 The crude fulphur is tranfported into France 
 by the way of Marfeilles, where it receives the 
 neceffary preparations to fender it fuitable to 
 various purpofes. i. It is reduced into flicks 
 or rolls, by fuling it, and pouring it into 
 moulds: or, 2. It is formed into flowers of 
 brimflone by fubliming it with a gentle heat, 
 and collecting this fulphureous vapour in a 
 very clofe chamber of confiderable extent. 
 This very pure and finely divided fulphur is 
 diflinguifhed by the name of Flowers of Brim- 
 flone, or Sublimed Sulphur. 
 
 Sulphur enters into fufion by a moderate 
 heat ; and if the moment be feized in which 
 the furface congeals, and the liquid fulphur 
 contained beneath that furface be then poured 
 out, the internal cavity will exhibit long nee- 
 dle-formed cryflals of an octahedral figure. 
 This procefs, contrived by the famous Rouelle^ 
 has been applied to the cryflallization of almofl 
 all the metals. Sulphur is found naturally cryf- 
 tallized in Italy, at Conilla near Cadiz, &c. 
 Its ufual form is octahedral ; but I have feen 
 cryflals of fulphur in perfect rhomboids. 
 
 Stahl 
 
93 
 
 Properties of Sulphur . 
 
 Stahl thought that he had proved, by anaiyfis 
 and fynthefis, that fulphur is formed by the com- 
 bination of his phlogiflon with the fulphuric 
 acid* The happy feries of proofs which he has 
 left behind him for the eflablifhment of this 
 opinion, has appeared fo complete, that, fince 
 the time of this great man, his doctrine hascon- 
 flantly been admitted as founded on abfolute 
 proof. This example was even urged as an in- 
 fiance to fhew how high a degree of evidence 
 the chemical anaiyfis was capable of affording. 
 But our difcoveries reflecting gafeous fub- 
 ftances have fhewn us, that the ancients were 
 neceffarily led into error for want of that know- 
 ledge. The immenfe refearches of the moderns 
 into the compofition of acids, have fhewn that 
 thefe fubftances are decompofed in a variety of 
 operations; and this revolution in the flate of 
 our knowledge mull have produced a fimilar 
 change in our methods of explaining the phe- 
 nomena. An examination of the principal ex- 
 periments of Stahl, upon which his dodtrine 
 effentially depends, will fufficiently fhew the 
 truth of what we have afferted. 
 
 If one third part of charcoal, and two thirds of 
 fulphate of pot-afh, or vitriolated tartar, be 
 mixed and fufed in a crucible, theprodudlis (li- 
 ver of iulphur) fulphure of pot-afh. If this ful- 
 
 phure 
 
94 
 
 Analyfis of Sulphur. 
 
 pnure be diffolved in water, and the alkali be 
 engaged by addinga few drops of fulphuric acid, 
 a precipitate is afforded, which confifts of true 
 fulphur : cf whence,” fays Stahl, <c the fulphur 
 is a combination of phlogifton, or the inflam- 
 mable principle of the charcoal with the ful- 
 phuric acid.” The experiment was true, but 
 •the confequence is abfurd ; becaufe it would 
 follow that the fulphuric acid which w'as added, 
 muft have pofTeiFed the property of difplacing 
 fulphuric acid united to the alkali*. 
 
 If Stahl had more ftriftly analyfed the refult 
 or produft of this operation, he would have 
 been convinced that .it does not contain a par- 
 ticle of fulphuric acid. 
 
 If he had been poffeffed of the power of ope- 
 rating in clofed veffels, and of colle&ing the 
 gafeous fubftances which are difengaged, he 
 would have obtained a large quantity of carbo- 
 nic acid, which arifes from the combination of 
 theoxigeneof the fulphuric acid with charcoal. 
 
 * Without pretending, on the prefent occalion, todifpute 
 either for or againft phlogifton, I (hall obferve that this argu- 
 ment is one among the many paralogifms urged on both fides 
 in this controverfy. If there be any difficulty in conceiving 
 howdephlogifticated fulphur, or pure vitriolic acid, may dis- 
 place phlogifticated vitriolic acid, or lulphur, the fame will 
 apply to the oppofite theory, which afferts that aerated ful- 
 phur, or vitriolic acid, difplaces de-aerated vitriolic acid, or 
 pure fulphur. T. 
 
 if 
 
Pure Charcoal or Carl one. 
 
 95 
 
 If he had expofed his liver of fulphur to the 
 air in clofed veffels, he would have feen that the 
 vital air is abforbed, that the fulphure is de- 
 compofed, and that the fulphate of pot-afh, or 
 vitriolated tartar is formed ; which proves the 
 recompofition of the fulphuric acid. 
 
 If charcoal be moiftened with fulphuric acid 
 or oil of vitriol, and then expofed to diftiila- 
 tion, the produces are carbonic acid or fixed 
 air, fulphur, and much fulphureous or volatile 
 vitriolic acid. 
 
 The experiments of Stahi exhibit the mod; 
 perfedl demonftration of the decompofition of 
 the fulphuric acid into fulphur and oxigene; 
 and it is not neceffary, in the explanation of 
 them, either to fuppofe the exifience of an 
 imaginary being, or to fuppofe that fulphur is 
 a compounded body. 
 
 CHAP. III. 
 
 Concerning Carbone . 
 
 TJURE charcoal is called Carbone in the 
 new Nomenclature. This fubftance is 
 placed among fimple bodies, becaufe no ex- 
 periment has hitherto fhewn the polfibility of 
 decompofing it. 
 
 Carbone 
 
96 
 
 Pure Charcoal or Carbone . 
 
 Carbone exifts ready formed in vegetables- 
 It may be cleared of all the volatile and oily 
 principles by diftillation ; and, by fubfequent 
 wafhing in pure water, it tnay be deprived of 
 all the falts which are mixed and confounded 
 with it* 
 
 When it is required to procure carbone in a 
 flate of great purity, it muff be dried by ftrong 
 ignition in a clofed veffel : this precaution is 
 necelTary ; for the laft portions of water adhere 
 with fuch avidity, that they are decompofed, 
 and afford hydrogenous gas and carbonic acid. 
 
 Carbone exifts likewife in the animal king- 
 dom : it may be extracted by a procefs limilar 
 to that which we have defcribed; but its quan- 
 tity is fmall. It appears in the form of a light 
 fpongy mafs, difficultly confumed in the air, 
 and mixed with a great quantity of phofphates, 
 and even of fodar. 
 
 Carbone is likewife found in plumbago, of 
 which it is one of the principles* 
 
 We fnall treat more fully of this fubftance 
 in the analyfis of vegetables. But thefe con- 
 oife ideas are fufficient to enable us to proceed 
 in our account of its combinations, which is 
 indeed the only objeift of the prefent fhort 
 enumeration of its properties. 
 
 SEC- 
 
 ✓ 
 
Gafeous Subjlances ♦ 
 
 97 
 
 SECTION V. 
 
 Concerning Gafes, or the Solution of cer- 
 tain Principles in Caloric, at the Tem- 
 perature of the Atmofphere. 
 
 C ALORIC, in its combination with bo- 
 dies, volatilizes fome of them, and reduces 
 them to the aeriform ftate. The permanence 
 in this ftate in the temperature of the atmo- 
 fphere conftitutes the gafes ; Lo that, to reduce 
 a fubftance to the ftate of gas, conftfts in dif- 
 folving it in caloric. 
 
 Caloric combines with various bodies, with 
 greater or lefs facility ; and we are acquainted 
 with feveral that, at the temperature of the at- 
 mofphere, are conftantly in the ftate of gas : 
 there are others which pafs to this ftate at fome 
 degrees higher, and thefe are called Volatile or 
 Evaporable fubftances. They differ from fixed 
 fubftances, becaufe thefe laft are not volatilized 
 but by the application and combination of a 
 ftrong dofe of caloric. 
 
 It appears that all bodies do not indifcrimi- 
 nately require the fame quantity of caloric to 
 affume the gafeous ftate; and we fhall fee that 
 Vol.I. H this 
 
9 8 Converfion of Bodies 
 
 this proportion may be deduced from the fixa- 
 tion and concretion of thefe gafeous fubftances. 
 
 To reduce any fubftance to the ftate of gas, 
 the application of caloric may be made in va- 
 rious manners. 
 
 The moft fimple method confifts in placing 
 the body in contadt with another body which 
 is heated. In this fituation, the heat on one 
 hand diminifhes the affinity of aggregation or 
 compofition, by feparating the conftituent prin- 
 ciples to a greater diflance from each other; 
 on the other hand, the heat unites to the prin- 
 ciples with which it has the ftrongeft affinity* 
 and volatilizes them. This procefs is accord- 
 ing to the method of fimple affinities ; for it in 
 fadl confifls of the exhibition of a third body, 
 which, prefented to a compound of feveral 
 principles, combines with one of them, and 
 carries it off. 
 
 The method of double affinity may likewife 
 be ufed to convert any fubftance into the gaf- 
 eous form ; and this is what happens when we 
 caufe one body to adt upon another to produce 
 a combination, in which a difengagement of 
 feme gafeous principles takes place. If I pour, 
 for example, the fulphuric acid upon the oxide 
 of manganefc, the acid combines with the me- 
 tal, while its caloric feizes the oxigene, and 
 
 rifes- 
 
99 
 
 by Heat into Gafes . 
 
 rifes with it. This principle takes place not 
 only in this inffance, but on all other occa- 
 lions wherein, an operation being performed 
 Without the application of heat, there is a pro- 
 duction of vapour or gas. 
 
 The various Hates under which bodies pre- 
 fent themfelves to our eyes, depend almoft 
 entirely upon the different degrees of combina- 
 tion of caloric with thofe fame bodies. Fluids 
 do not differ from folids, but becaufe they con- 
 ffantly polfefs, at the temperature of the atmo- 
 fphere, the dofe of caloric which is requifite to 
 maintain them in that Hate ; they congeal and 
 pafs to the concrete Hate with greater or lefs 
 facility, according as the requifite quantity of 
 caloric is more or lefs confiderable. 
 
 All folid bodies are capable of palling to the 
 gafeous Hate ; and the only difference which 
 exiffs between them in this refpeCl is, that a 
 dofe of caloric is required for this purpofe, 
 which is governed — i. By the affinity of ag- 
 gregation, which conneCls their principles, re- 
 tains them, and oppofes itfelf to a new combi- 
 nation. 2. By the weight of the condiment 
 parts, which renders their volatilization more 
 or lefs difficult. 3. By the agreement and at- 
 traction between the caloric and the folid bo- 
 dy, which is more or lefs ffrong. 
 
 H 2 
 
 All 
 
ipo The Methods of making 
 
 All bodies, whether folid or liquid, when 
 they come to be volatilized by heat, appear in 
 two dates — that of vapour, or that of gas. 
 
 In the fird cafe, thefe fubdances lofe, in a 
 fhort time, the caloric which raifed them, and 
 again appear in their original form the moment 
 the caloric finds colder bodies to combine with ; 
 but it is rare that bodies thus divided refume 
 their original confidence. The fird date is 
 that of vapour. 
 
 In the fecond cafe, the combination of ca- 
 loric with the volatilized fubdance is fuch, 
 that the ordinary temperature of the atmofphere 
 is infufficient to overcome this union. This 
 date conditutes the gafes. 
 
 When the combination of caloric with any 
 fubdance is fuch that a gas is produced, thefe 
 invifible fubdances may be managed at plea- 
 fure, by the afiidance of apparatus appropriated 
 within our time to thefe ufes. Thefe appara- 
 tus are known by the name of Pneumato-che- 
 mic. Hydro-pneumatic apparatus, &c. 
 
 The pneumato-chemical apparatus, in ge- 
 neral, confids of a wooden veffel, ufually of a 
 fqu are form, and lined with lead or tin: two 
 or three inches beneath the upper edge there 
 is formed a groove, in which a wooden plank 
 Hides, having a hole in the middle, and a notch 
 
 in 
 
IOI 
 
 Experiments on Gafes . 
 
 in one of its fides ; the hole is made in the 
 centre of an excavation made in the fhelf, of 
 the figure of a funnel. 
 
 This velfel is filled with water or mercury, 
 according to the nature of the gafes operated 
 upon. There are fome which eafily combine 
 with water, and therefore require to be receiv- 
 ed over mercury. 
 
 The gafes may be extracted in various man- 
 ners. 
 
 When they are difengaged by fire, a recurv- 
 ed tube is adapted to the neck of the retort, 
 one extremity of which is plunged in the water 
 or the mercury of the pneumato-chemical 
 velfel, and opens beneath the aperture in the 
 fhelf, which is in the form of a funnel. The 
 jun&ion of the tube with the neck of the re- 
 tort is fecured with the ufual lute ; a velfel fill- 
 ed with the liquid of the ciftern is inverted upon 
 the fhelf over the aperture. When the gas is 
 difengaged from the materials in the retort, it 
 appears in the form of bubbles, which rife, and 
 gain the fuperior part of the inverted velfel. 
 When all the water is difplaced, and the bottle 
 is full of gas, it is withdrawn, by adapting a 
 glafs plate to its orifice to prevent its dillipa- 
 tion: it may then be poured from one velfel to 
 
 another, 
 
102 
 
 Hydrogenous Gas , 
 
 another, and fubjeded to a variety of experi- 
 ments to afeertain its nature. 
 
 When the gafes are difengaged by means of 
 acids, the mixture which is deigned to afford 
 them is put into a bottle with a recurved tube 
 fitted to its neck ; and this tube is plunged in 
 the ciftern in fuch a manner, that the bubbles 
 of gas may pafs, as in the former experiment, 
 through the aperture of the funnel in the fhelf. 
 
 The procefles at prefent ufed to extrad the 
 gafes, and to analyfe them, are fimple and com- 
 modious: and thefe procefles have Angularly 
 contributed to our acquifltion of the know- 
 ledge of thefe aeriform fubftances, whofe dis- 
 covery has produced a revolution in chemiftry. 
 
 CHAP. I. 
 
 Concerning Hydrogenous Gas y or inflammable Air* 
 
 I NFLAMMABLE Air is one of the 
 conftituent parts of water; a circumftance 
 which has entitled it to the denomination of 
 Hydrogenous Gas. Its property of burning 
 with vital air has caufed it to be diftinguifhed 
 by the name of Inflammable Air. 
 
 Hydro- 
 
or Inflammable Air . I 03 
 
 Hydrogenous gas has been procured long 
 fince. The famous philofophical candle attefts 
 the antiquity of this difcovery; and the cele- 
 brated Hales obtained from mod vegetables an 
 air which took fire. 
 
 Hydrogenous gas may be extracted from all 
 bodies in which it is a conftituent part ; but the 
 pureft is that afforded by the decompofition of 
 water, and it is this fluid which ufually affords 
 it in our laboratories. For this purpofe the ful- 
 phuric acid is poured upon iron, or zinc ; the 
 water which ferves as a vehicle for the acid, is 
 decompofed on the metal; its oxigene combines 
 with it, while the hydrogenous gas efcapes. 
 This explanation, however contrary to the an- 
 cient notion, is not the lefs a demonflrated 
 truth; in fad:, the metal exifts in the ffate of 
 an oxide in its folution by the fulphuric acid, 
 as may be proved by precipitating it with pure 
 vegetable alkali : on the other hand, the acid 
 itfelf is not at all decompofed ; fo that the ox- 
 ygenous gas Cannot have been afforded to the 
 ‘ iron but by the water. Water may be decom- 
 pofed like wife ffill more diredly by throwing 
 it upon iron ftrongly heated ; and hydrogenous 
 gas may be obtained by caufing water to pafs 
 through a tube of iron ignited to whitenefs. 
 
 The hydrogenous gas may be extracted by 
 
 the 
 
104 Hydrogenous Gas> 
 
 the fimple diftillation of vegetables. Vegetable 
 fermentation, and animal putrefaction, likewife 
 produce this gafeous fubftance. 
 
 The properties of this gas are as follow : 
 
 A. Hydrogenous gas has a difagreeable 
 ftinking odour. Mr. Kirwan has obferved, 
 that when it is extra<fled over mercury, it has 
 fcarcely any fmell. It contains half its weight 
 of water, and lofes its fmell the moment it is 
 deprived of this additional fubftance. 
 
 Kirwan has likewife obferved, that the vo,- 
 lume of hydrogenous gas is one-eighth larger 
 when received over water than when received 
 over mercury. 
 
 Thefe obfervations appear to prove, that the 
 offenfive fmell of this gas arifes only from the 
 water it holds in folution. 
 
 B. Hydrogenous gas is not proper for refpi- 
 
 ration. The abbe Fontana allures us that he 
 could not take more than three infpirations of 
 this air : the count Morrozo has proved that 
 animals perifh in it in a quarter of a minute. 
 On the other hand, feveral northern chemilfs 
 have affirmed, in confequence of experiments 
 made on themfelves, that hydrogenous gas 
 might be refpired without danger ; and it isfome 
 years fince the unfortunate Pilatre du Rozier 
 filled his lungs with it at Paris, and fet it on 
 - r * * fire 
 
or Inflammable Air . 
 
 105 
 
 fire during the expiration, which forms a very 
 curious jet of flame. It was remarked to him, 
 that the abbe Fontana had obje&ed againft 
 the accufacy of the Swedifh chemifls. This in- 
 trepid philofopher anfwered the objection, by 
 mixing one-ninth of atmofpherical air with 
 very pure hydrogenous gas. He refpired this 
 mixture, as ufual ; but when he attempted to 
 fet it on fire, the confequence was an explofion 
 fo dreadful, that he imagined all his teeth were 
 blown out. 
 
 This oppofition of opinions and contradic- 
 tion of experiments, refpecling a phenomenon 
 which feems capable of unanfwerable decifion 
 by one Angle experiment, induced me to have 
 recourfe to trial, to fix my own ideas on the 
 fubjedl. 
 
 Birds, fucceflively placed in a veflel of hy- 
 drogenous gas, died, without producing the 
 fmallefi: perceptible change in the gas itfelf. 
 
 Frogs placed in forty inches of hydrogenous 
 gas died in the fpace of three hours and a 
 half : while others lived fifty-five hours in oxi- 
 genous gas and atmofpheric air ; and when I 
 took them out (fill living, the air was neither 
 vitiated nor diminifhed. Numerous experi- 
 ments which I have made upon thefe animals, 
 have led me to obferve that they have the fa- 
 culty 
 
io6 Hydrogenous Gas, 
 
 eulty of (lopping their refpiration, when placed 
 in any noxious gas, to fuch a degree, that they 
 infpire only once or twice, and afterwards fuf- 
 pend every function on the part of the refpira-, 
 tory organ. 
 
 I have fince had occaiion to obferve that 
 thefe animals are not reduced into a putrid mafs 
 by remaining in hydrogenous gas, as was affirm- 
 ed fome time ago. The faCt which may have 
 impofed on chemifts who related this circum- 
 itance, is, that frogs are often enveloped in a 
 mucus or fanies, which appears to cover them ; 
 but they exhibit the fame phenomenon in all 
 the gafes. 
 
 After having tried the hydrogenous gas upon 
 animals, I determined to refpire it myfelf ; and 
 I found that the fame volume of this air might 
 be feveral times refpired without danger. But 
 I obferved that this gas was not changed by thefe 
 operations ; whence I concluded that it is no* 
 refpirable : for, if it were, it would fuffer a 
 change in the lungs, the objeCt of refpiration 
 not beingconfined to the reception and emiffion 
 of a fluid merely; it is a function much more 
 noble, more interefting, more intimately con- 
 nected with the animal ceconomy : and we ought 
 to confider the lungs as an organ which is 
 nourifhed by the air, digefts that which is pre- 
 
 fented 
 
or Inflammable Air ♦ 
 
 J07 
 
 fentedtoit, retains the beneficial, and rejedsthe 
 noxious part. Since therefore inflammable air 
 can be refpired feveral fucceffive times without 
 danger to the individual, and without any altera*, 
 tion or change in itfelf, we may conclude in- 
 deed that inflammable air is not a poifon, but 
 that it cannot be confldered as an air eflentially 
 proper to refpiration. It is with hydrogenous 
 gas in the lungs, as with thofe balls of mofs and 
 refln which certain animals fwallow during the 
 rigorous feafon of the winter, Thefe balls are 
 not digefted, lince the animals void them at 
 the return of fpring : but they delude hunger 5 
 and the membranes of the ftomach are exer- 
 cifed upon them without danger, in the fame 
 manner as the lungs exert themfelves upon the 
 hydrogenous gas prefented to them. 
 
 C. Hydrogenous gasis not cornbuftible alone; 
 it does not burn but by the concurrence of 
 oxigene. If a veflel filled with this gas be 
 reverfed, and a lighted taper be prefented to 
 it, the hydrogenous gas is found to burn at the 
 furface of the veflel; but the candle is extin- 
 guifhed the moment it is plunged lower. The 
 moft inflammable bodies, fuch as phofphorus, do 
 not burn in an atmofphere of hydrogenous gas. 
 
 D* Hydrogenous gas is lighter than common 
 
 air* 
 
i o 8 Hydrogenous Gas> 
 
 . . / 
 
 air. One cubic foot of atmofpheric air weighs 
 
 feven hundred and twenty grains ; a cubic, 
 foot of hydrogenous gas weighs feventy-two 
 grains. The barometer being at 29' 9, and 
 the thermometer 6o° Fahrenheit, Mr. Kirwan 
 found the weight of this air to that of common 
 air as eighty-four to one thoufand ; confe- 
 quently it was about twelve times as light. 
 
 Its fpecific gravity varies very much, be- 
 caufe it is difficult to obtain it conftantly of 
 the fame degree of purity. That which is ex- 
 tracted from vegetables contains the carbonic 
 acid and oil, which increafes its weight. 
 
 This levity of hydrogenous gas has caufed 
 certain philofophers to prefume that it ought to 
 arrive at and occupy the fuperior part of our at- 
 mofphere; and upon this fuppofirion the moft 
 brilliant conje&ures have been made refpedling 
 the influence which a flratum of this gas, predo- 
 minating over the reft of the atmofphere, ought 
 to produce in meteorology. They were not 
 aware that this continual lofs of matter is not 
 agreeable to the wife ceconomy of nature. They 
 did not obferve that this gas, during its afcent 
 in the air, combines with other bodies, more 
 efpecially the oxigene, and that water and other 
 produces are the refult ; the knowledge of which 
 ' ' ’ • muft 
 
or Inflammable Air. 109 
 
 mull neceffarily lead us to that of mod me- 
 teors. 
 
 The theory of balloons, or aeroflatic ma- 
 chines, is founded on this levity of the hy- 
 drogenous gas. 
 
 In order that a balloon may rife in the atmo- 
 fphere, it is fufficient that the weight of the 
 balloon itfelf, and the air it enclofes, fhould be 
 lefs confiderable than that of an equal bulk of 
 atmofpheric air ; and it muft rife till its weight 
 is in equilibrio with an equal volume of the 
 furrounding air. 
 
 The theory of the Mongolfiers is every differ- 
 ent from this. In this cafe a given volume of 
 atmofpheric air is rarefied by heat, and kept 
 feparated from the common mafs by a hollow 
 veifel of cloth. This rarefied fpace rnay there- 
 fore be confidered for a moment as confifting 
 of a mafs of air of greater levity, which muft 
 neceflarily make an effort to rife in the atmo- 
 fphere, and carry its covering along with it. 
 
 E. Hydrogenous gas exhibits various cha- 
 racters according to its degree of purity, and 
 the nature of the fubftances which are mixed 
 with it. 
 
 It feldom happens that this gas is pure. That 
 which is afforded by vegetables contains oil, 
 and the carbonic acid. The inflammable air 
 
 of 
 
lib Hydrogenous Gas. 
 
 of marfhes is mixed with a greater or lefs quarts 
 tity of carbonic acid ; and that which is afforded 
 by the decompofition of pyrites fometimes 
 holds fulphur in folution. 
 
 The colour of hydrogene, when fet on fire, 
 varies according to its mixtures. One-third of 
 the air of the lungs, mixed with the inflamma- 
 ble air of pit-coal, affords a flame of a blue co- 
 lour; inflammable air, mixed with nitrous air, 
 affords a green colour; the vapour of ether af- 
 fords a white flame. The various mixtures of 
 thefe gafes, and the degree of compreffion to 
 which they are fubjedled, when expreffed out 
 of an aperture in order to burn them, have, in 
 the hands of certain operators, afforded very 
 agreeable illuminations, well deferving the at- 
 tention of learned and curious obfervers. 
 
 F. Hydrogenous gas poffeffes the property 
 of diffolving fulphur. In this cafe it contracts 
 a ffinking fmell, and forms hepatic gas. 
 
 Mr. Gengembre put fulphur into inverted 
 veffels filled with hydrogenous gas, and dif- 
 folved it by means of the burning-glafs, The 
 hydrogenous gas, by this treatment, obtained 
 all the charaderiftic properties of hepatic gas. 
 
 The formation of this gas is almoft always 
 an effedl of the decompoiltion of water. In fa£t, 
 the alkaline fulphures, or livers of fulphur, do 
 
 not 
 
Ill 
 
 Hepatic Gas . 
 
 hot emit any difagreeable fmell while they are 
 dry; but the moment they are moiftened, an 
 abominable fmell is perceived, and the ful- 
 phate of pot-afh, or vitriolated tartar, begins to 
 be formed. Thefe phenomena prove that the 
 water is decompofed ; that one of its principles 
 unites to the fulphur, and volatilizes it ; while 
 the other combines with the alkali, and forms 
 a more fixed product. 
 
 Sulphurated hydrogenous gas may be obtain- 
 ed by dilfolving the fulphures or hepars by 
 acids. Thofe acids in which the oxigene is molt 
 adherent difengage the greatefl: quantity. The 
 muriatic acid produces twice as much as the 
 fulphuric. That which is produced by this laid, 
 burns with a blue flame ; but that which is dif- 
 engaged by the muriatic add, burns with a 
 yeilowifh white flame. 
 
 Scheele has taught us the means of obtain- 
 ing this gas in great abundance, by deeompo- 
 fing artificial pyrites, formed by three parts of 
 iron and one of fulphur, to which fpirit of vi- 
 triol is added. 
 
 The natural decompofition of pyrites in the 
 bowels of the earth produces this gas ; which 
 efcapes with certain waters, and communicates 
 peculiar virtues to them. 
 
 The 
 
1 12 Hepatic Gas. 
 
 The moft general properties of thefe gafes 
 are: 
 
 1. They render the white metals black. 
 
 2. They are improper for refpiration. 
 
 They impart a green colour to fyrup of 
 
 violets. 
 
 4. They burn with a light blue flame, and 
 depolit fulphur by this combuftion. 
 
 5. They mix with the oxigenous gas of the 
 atmofpheric air, and form water; at the fame 
 time that the fulphur, before held in folution, 
 falls down. Hence it happens that fulphur is 
 found in the channels of hepatic waters, though 
 their analyfis does not fhew the exiftence of an, 
 atom of that fubftance held in folution. 
 
 6. They impregnate water, and are fparing- 
 ly foluble in that fluid ; but heat or agitation 
 difflpates them again. 
 
 The air which burns at the furface of certain 
 fprings, and forms what is known by the name 
 of burning fprings, conlifts of hydrogenous gas 
 holding phofphorus in folution. It fmells 
 like putrid fifh. The Fere Lampi has difcover- 
 ed one of thefe fprings in the ifles of St. Colom- 
 bat. Dauphiny exhibits another fimilar fpring 
 at the diftance of four leagues from Grenoble. 
 The ignes fatui which glide along burying- 
 
 grounds. 
 
Vital Air ♦ 
 
 1 13 
 
 grounds, and which the fuperftitious people 
 fuppofe to conftft of the fpirits of the depart- 
 ed, are phenomena of this nature, which we fhall 
 fpeak of when we come to treat of phofphorus. 
 
 Concerning Oxigenous Gas, or Vital Air. 
 HIS gafeous fubftance was difcovered by 
 
 the celebrated Prieftley, on the 1ft of 
 Auguft 1774. Since that memorable day, 
 means have been devifed of obtaining it from 
 various fubftances; and its properties have 
 ftiewn that it is a production of the mofb in~» 
 terefting nature in the knowledge of chemiftry. 
 
 No part of the atmofphere exhibits vital air 
 in its greateft degree of purity. It is always 
 combined, mixed, or altered by other fub- 
 ftances. 
 
 But this air, which is the moft general agent 
 in the operations of nature, exifts in combina- 
 tion with various fubftances ; and it is by their 
 
 Vol. I. I deeonw 
 
 CHAP. II 
 
H4 Vital Air. 
 
 decompofition that it may be extra&ed and 
 procured. 
 
 A metal expofed to the air becomes changed ; 
 and thefe changes are produced only by the 
 combination of the pure air with the metal it- 
 felf. Simple dillillation of fome of thefe me- 
 tals thus changed, or oxides, is fufficient to 
 difengage this vital air ; and it is then obtained 
 in a very pure (late, by receiving it in the hy- 
 dro-pneumatic apparatus. One ounce of red 
 precipitate affords about a pint. 
 
 All acids have vital air for their bafe: there 
 are fome which yield it eafily. The diftillation 
 of nitre decompofes the nitric acid ; and about 
 twelve hundred cubic inches of oxigenous gas 
 are obtained from a pound of this fait. 
 
 The nitric acid, when diflilled from various 
 fubftances, is decompofed, and its conftituent 
 parts may be obtained feparately. 
 
 MefTrs. Prieftley, Ingenhoufz, andSennebier 
 difeovered nearly at the fame time that vege- 
 tables expofed to the light of the fun emit 
 vital air.- We fhall elfewhere fpeak of the cir- 
 tkimlfarices of thefe phenomena ; but fhall at 
 prefent confine ourfelves to the obfervation, 
 : that the emiflion of vital air is proportioned to 
 'the vigour of the plant, and the vivacity of the 
 light ; and that the direct emiflion of the rays 
 - of 
 
Vital Air . 
 
 of the fun is not neceflary to produce this gaf- 
 eous dew ; it is fufficient that the plant be well 
 enlightened, in order that it may tranfpire pure 
 air : fori have often colledled it in abundance 
 from a kind of mofs which covers the bottom 
 of a velTel filled with water, and fo well defend- 
 ed that the fun never {hone diredlly upon it. 
 
 In order to procure the vital air which is dif- 
 engaged from plants, it is fufficient to enclofe 
 them beneath a glafs velTel filled with water, and 
 inverted over a tub filled with the fame fluid. 
 The moment the plant is a&ed on by the fun, 
 fmall bubbles of air are formed on its leaves, 
 which detaching themfelves rife to the upper 
 part of the velTel, and difplace the liquid. 
 
 This dew of vital air is a beneficial gift of 
 nature to repair inceflantly the confumption 
 of vital air. The plant abforbs atmofpheri- 
 cal mephitis, and emits vital air. Man, on the 
 contrary, is kept alive by vital air, and emits 
 much mephitis. It appears therefore that the 
 animal and vegetable kingdoms labour for each 
 other ; and that by this admirable reciprocity 
 of fervices the atmofphere is continually re- 
 paired, and an equilibrium maintained between 
 its conftituent principles. 
 
 The influence of folar light is not confined 
 to the produ&ion of vital air by itsadlion upon 
 I 2 vegetables 
 
1 1 6 Vital Air. 
 
 -vegetables alone; it: has likewife rhe Angular 
 property of decompofing certain fubftances, 
 and difengaging this gas. 
 
 A bottle of oxigenated muriatic acid, ex- 
 pofedto the fun, fuffers all the fuperabundant 
 oxigene which it contained to efcape, and paff- 
 es to the ftate of ordinary muriatic acid. The 
 fame acid, expofed to the fun in a bottle wrap- 
 ped in black paper, does not fuffer any change; 
 and, when heated in a dark place, is even re- 
 ducible into gas without decompofition. The 
 nitric acid likewife affords oxigenous gas* when 
 expofed to the fun ; w r hereas heat alone volati- 
 lizes it without decompofition. 
 
 The muriate, or marine fait of filver, placed 
 under water, and expofed to the fun, fuffers 
 oxigenous gas to efcape from it. I have 
 obferved that red precipitate likewife affords 
 oxigene in fimilar cafes, and that it becomes 
 black in no very long fpace of time. 
 
 We may likewife obtain oxigenous gas by 
 difengaging it from its bafes by means of the 
 fuiphuric acid. The procefs to which I give 
 the preference, on account of -its fimplicity, is 
 the following : — I take a fmall apothecary's 
 phial, into which I put one or two ounces of 
 manganefe, and pour thereon a fufficient quan- 
 tity of fuiphuric. acid to form a liquid paffe. I 
 * after- 
 
Vital Air • 
 
 117 
 
 afterwards fit a cork to the opening of the bot- 
 tle, with a hole through it, into which is infert- 
 ed a recurved tube ; one of whofe extremities 
 enters the bottle, while the other is placed un- 
 der the fhelf of the pneumato-chemical appara- 
 tus. When the apparatus is thus difpofed, I 
 prefent a fmall coal to the lower part of the bot- 
 tle, andoxigenous gas is immediatelydifengaged. 
 
 The manganefe I ufe was difcovered by me at 
 St. Jean de Gardonnenque. It affords its oxi- 
 gene with fuch facility, that nothing more is 
 neceftary for this purpofe than to incorporate it 
 with the lulphuric acid. This gas is not per-* 
 ceptibly mixed with nitrigenous gas (or phlo- 
 gifficated air) ; and the firft bubble is as pure 
 as the laft. 
 
 Oxigenous gas exhibits certain properties > 
 according to its degree of purity. Thefe depend 
 in general upon the fubftances which afford it. 
 That which is obtained from the mercurial 
 oxides almoft always holds a fmall quantity of 
 mercury in folution : I have been a witnefs to 
 its having produced a fpeedy falivation on two 
 perfons who ufed it for diforders of the lungs. 
 In confequence of thefe obfcrvations, I filled 
 bottles with this gas, expofed them toanintenfe 
 cold 3 and the lides became obfcured with a ftra- 
 
 tum 
 
1X8 
 
 Vital Air, 
 
 turn of mercurial oxide, in a (fate of extreme 
 divifion. I have feveral times heated the bath, 
 over which I caufed this gas to pafs ; and I ob- 
 tained, at two different times, a yellow preci- 
 pitate in the bottle in which I had received the 
 gas. 
 
 The oxigenous gas extra&ed from plants is 
 not equally pure with that afforded by the me- 
 tallic oxides : but from whatever fubftances it 
 is obtained, its general properties are the fol- 
 lowing: 
 
 A. It is more ponderous than the air of the 
 atmofphere ; the cubic foot of atmofpherical 
 air weighing feven hundred and twenty grains, 
 while the cubic foot of pure air weighs feven 
 hundred and fixty-five. According to Mr. 
 Kirwan, its weight is to that of common air as 
 eleven hundred and three to one thoufand. 
 One hundred and lixteen inches of this air 
 weighed 39,09 grains ; one hundred and lixteen 
 inches of common air weighed 35,38 grains at 
 the temperature of ten degrees of Reaumur, and 
 twenty-eight inches of preffure. One hundred 
 parts of common air weighed forty- fix, and 
 one hundred parts of vital air fifty. 
 
 B. Oxigenous gas is the only fluid proper 
 for combuflion* This acknowledged truth 
 
 caufed 
 
 / 
 
Vital Air. 
 
 ll 9 
 
 cauled the celebrated Scheele to give it the 
 name of Air of Fire. 
 
 To proceed with greater order in the exami- 
 nation of one of the mod important properties 
 of oxigenous gas, fince it belongs exclufively 
 to this fluid, we fhall lay down the four fol- 
 lowing principles, as inconteftable refults of 
 all the known facts. 
 
 The firft principle. — Combuflion never 
 takes place without vital air. 
 
 The fecond principle. — In every combuf- 
 tion there is an abforption of vital air. 
 
 The third principle. — There is an augmen- 
 tation of weight in the products of combuflion 
 equal to the weight of the vital airabforbed. 
 
 The fourth principle. — In all combuflion 
 there is a difengagement of heat and light. 
 
 I. The firft of thefe propofttions is a ftridt 
 truth. Hydrogenous gas does not burn alone, 
 without the affiftance of oxigene ; and all com- 
 buftion ceafes the moment that oxigenous gas 
 is wanting. 
 
 II. The fecond principle contains a truth 
 no lefs general. If certain bodies, fuch as phof- 
 phorus, fulphur, &c. be burned in very pure 
 oxigenous gas, this is abforbed to the laft par- 
 ade ; and when the combuflion is effected in a 
 
 mixture 
 
120 
 
 Vital Air, 
 
 mixture of feveral gafes, the oxigene alone is 
 abforbed, and the others remain unchanged. 
 
 In the flower combuftions, fuch as the ran- 
 cidity of oils, and the oxidation of metals, 
 there is equally an abforption of oxigene, as 
 may be fhewn by confining thefe bodies in a* 
 determinate mafs of air. 
 
 III. The third principle, though not lefis 
 true than the preceding, requires more expla- 
 nation ; and for this purpofe we fhalldiflin- 
 guifh thofe combuflions whofe refult, refidue, 
 and product are fixed, from thofe which afford 
 volatile and fugacious fubftanccs. In the firft 
 cafe the oxigenous gas quietly combines with* 
 the body ; and by weighing the fame body the 
 moment the combuflion has completely taken 
 place, it is eafily afcertained whether the in- 
 creafe in weight be proportioned to the oxi- 
 gene abforbed. This happens in all the cafes 
 wherein the metals are oxided, or oils rendered 
 rancid ; and in the produ<ffion of certain acids* 
 fuch as the phofphoric, the fulphurk, &c. In 
 the fecond cafe, it is more difficult to weigh 
 all the refults of the combuflion, and confc- 
 quently to afcertain whether the augmenta- 
 tion in weight be proportioned to the quan- 
 tity of the air abforbed. Neverthelefs, if the 
 combuflion be made in inverted veffels, and 
 
 the 
 
 / 
 
! 
 
 Vital Air. 1 2 1 
 
 the whole of the products be collected, it is 
 found that their augmentation in weight is 
 ftricdly equal to that of the airabforbed. 
 
 IV. The fourth principle is that whofe appli- 
 cations are the molt interefting to be known. 
 
 In mod combudions, the oxigenous gas be-^ 
 comes fixed and concrete. It therefore aban- 
 dons the caloric which maintained it in the 
 aeriform Hate ; and this; caloric being fet at li- 
 berty, produces heat, and endeavours to com- 
 bine itfelf with the fubftances neared at hand. 
 
 The difengagement of the hear is therefore a 
 conftant effed: in all the cafes wherein vital air 
 is fixed in bodies ; and it follows, from this 
 principle — i. That heat is mod eminently red- 
 dent in the oxigenous gas which maintains com- 
 budion. 2. That the more oxigene is abforbed 
 in a given time, the dronger will be the heat. 
 3. That the only method of producing a violent 
 heat condds in burning bodies in the pured 
 air. 4. That dreand heat mud be more intenfe 
 in proportion as the air is more condenfed. 
 5. That currents of air are neceffary to main- 
 tain and expedite combudion. It is upon this 
 principle that the theory of the effects of the 
 cylinder lamps is founded : the current of air, 
 which is renewed through the tube, fupplies 
 frefh air every indant ; and by continually ap- 
 
 plying 
 
122 
 
 Vital Air . 
 
 plying a new quantity of oxigenous gas to the 
 flame, a heat is produced fufficient to ignite 
 and deftroy the fmoke. 
 
 It is likewife on the fame principle that we 
 explain the great difference that exifts between 
 heat produced by a flow combuftion, and that 
 which is afforded by rapid combuftion. In 
 the latter cafe the fame quantity of heat and 
 light is produced in a fecond, which might 
 have been produced in the other cafe in a 
 much longer time. 
 
 The phenomena of combuftion, by means of 
 oxigenous gas, depend likewife upon the fame 
 laws. Profeffor Lichtenberger, of Gottingen, 
 foldered the blade of a knife to a watch fpring 
 by means of oxigenous gas ; Me firs. Lavoifier 
 and Erhmann have fubjefled almoft all the 
 known bodies to the adfion of fire maintained 
 by oxigenous gas alone ; and they produced 
 effedls which the burning-glafs could not have 
 operated. 
 
 Mr. Ingenhoufz has fhewn us, that if an iron 
 wire be bent into a fpiral form, and any com- 
 buftible fubftance whatever be fixed to one of 
 its ends, and fet on fire, the wire will itfelf be 
 fufed by plunging it into oxigenous gas. 
 
 Mr. Forfter, of Gottingen, found that the 
 light of glow-worms is fo beautiful and bright 
 
 in 
 
Vital Air . 
 
 123 
 
 in oxigenous gas, that one Angle in fed was fuf- 
 ficient to afford light to read the Annonces Sa- 
 vantes of Gottingen, printed in a very fmall 
 character. Nothing more is wanting therefore 
 than to apply this air to combuftion with facility 
 and oeconomy ; and Mr. Meufnier has fucceed- 
 ed in this, by conftruding a Ample and com- 
 modious apparatus. On this fubjed the treatife 
 of Mr. Erhmann upon fufion may be confulted. 
 
 The defcription of the gazometer may like- 
 wife be feen in the Elementary Treatife of Che- 
 miftry, by Mr. LavoiAer. 
 
 We fhail diftinguifti three ftates in the very 
 ad of combuftion — ignition, inflammation, 
 and detonation. 
 
 Ignition takes place when the combuftible 
 body is not in the aeriform ftate, nor fufcep- 
 tible of affuming that ftate by the Ample heat 
 of combuftion. This happens when well-made 
 charcoal is burned. 
 
 When the combuftible body is prefented to 
 oxigenous gas, in the form of vapour or gas, 
 the refult is flame ; and the flame is more con- 
 ftderable, in proportion as the combuftible 
 body is more volatile. The flame of a candle 
 is not kept up but by the volatilization of the 
 wax, which is continually effeded by the heat 
 of the combuftion. 
 
 Deto- 
 
1 2 
 
 Vita / Air . 
 
 Detonation is a fpeedy and rapid inflamma- 
 tion, which occafions a noife by the indanta- 
 neous formation of a vacuum. Mod detona- 
 tionsare produced by the mixture of hydroge- 
 nous and oxigenous gas, as I have fhewn in my 
 Memoir upon Detonations, in the year 1781 f 
 It has been fince proved, that the product of 
 the rapid combudion of thefe two gafes is wa- 
 ter. Very ftrong detonations may be produced 
 by burning a mixture of one part of oxigenous 
 gas with two of hydrogene. The effect may 
 be rendered dill more terrible, by caufing the 
 mixture to pafs through foap- water* and fetting 
 fire to the bubbles which are heaped on the 
 furface of the fluid. 
 
 Chemidry prefents feveral cafes in which the 
 detonation arifes from the fudden formation of 
 fome gafeous fubdances, fuch as that which is 
 produced by the inflammation of gunpowder ; 
 for in this cafe there is a fudden production of 
 carbonic acid, of nitrogene gas, &c. The pro- 
 duction or indantaneous creation of any gas 
 whatever, mud occaflon a fhock or agitation in 
 the atmofp’nere, which neceffariiy affords an ex- 
 plofion ; the effeCt of thefe explofions increafes, 
 and becomes dronger, from the oppofition of 
 any obdacles againd the efcape of the gas. 
 
 C. Oxigenous gas is the only gas proper for 
 
 refpira- 
 
Vital Air. 
 
 
 refpiration. It is this mo P l eminent property 
 which has entitled it to the name of Vital Air ; 
 and we fhall give the preference to this deno- 
 mination in the prefent article. 
 
 It has long fince been known that animals 
 cannot live without the affiftance of air. But 
 the phenomena of refpiration have been very 
 imperfe&ly known until lately. 
 
 Of all the authors who have written concern- 
 ing refpiration, the ancients are thofe who have 
 had the moll accurate ideas of it. They admit- 
 
 J 
 
 ted in the air a principle proper to nourifh and 
 fupport life, which they denoted by the name of 
 -pabulum vitee ; and Hippocrates exprefsly fays, 
 fpiritus etiam alimentum eft. This idea, which 
 was connected v 7 ith no hypothecs, has been 
 fucceffively replaced by fyflems void of all 
 foundation. Sometimes the air has been confi- 
 dered as a ftimulus in the lungs, which kept up 
 the circulation by its continual action. Vide 
 Haller. — Sometimes the lungs have been con- 
 lidered as bellows defigned to cool the body, 
 heated by a thou fa nd imaginary caufes: and 
 when it was proved that the volume of air was 
 diminifhed in the lungs, it was thought to be 
 an explanation of every difficulty, to fay that 
 the air was deprived of its fpring. 
 
 At this day, however, we are enabled to throw 
 
 forrie 
 
126 Vital Atr. 
 
 i , 
 
 Tome light on one of the mod important func- 
 tions of the human body. In order to proceed 
 with more perfpicuity, we (hall reduce our 
 notions to feveral principles. 
 
 1. No animal can live without the alfiftance 
 of air. This fa6t is univerfally admitted ; but 
 it has not been known until lately that the fa- 
 culty which the air pofTeffes of anfwering the 
 purpofe of refpiration, arifes only from one of 
 the principles of atmofpheric air, known by the 
 name of vital air. 
 
 2. All animals do not require the fame pu- 
 rity in the air. Birds, as well as men, and the 
 greated part of quadrupeds, require a very pure 
 air ; but thofe which live in the earth, or which 
 hide themfelves in a date of dupefa&ion dur- 
 ing the winter, can fubfid by means of a lefs 
 pure air. 
 
 3. The manner of refpiring the air is diffe- 
 rent in the feveral fubjedls. In general, nature 
 has given to animals an organ, which by its 
 involuntary dilatation and contra&ion receives 
 and expels the fluid in which the animal moves 
 and exids. This organ is more or lefs perfedf, 
 more or lefs concealed and defended from ex- 
 ternal injury, according to its importance, and 
 influence upon the life of the creature, as Mr. 
 Brouffonnet has obferved. 
 
 Amphi- 
 
Vital Air , 
 
 127 
 
 Amphibious animals refpire by means of 
 lungs : but they can fufpend their motion even 
 whilft they are in the air ; as I have obferved 
 with regard to frogs, which flop their refpira- 
 tion at pleafure. 
 
 The manner of refpiration infifhes is very dif- 
 ferent ; thefe animals come from time to time to 
 inhale the air at the furface of the water, where 
 they fill their veficle, and digeft it afterwards 
 at their eafe. I have for a long time obferved 
 the phenomena of fi fhes in the adt of refpiration ; 
 and am well allured that they are fenfible of 
 the action of all the gafes, like other animals* 
 Mr. De Fourcroyhas obferved that the air con* 
 tained in the veficle of the carp is nitrogene gas 
 (phlogifticated air). 
 
 Infedls with tracheae exhibit organs flill 
 more remote from ours in their conftru&ion. 
 In thefe animals, refpiration is effedled by the 
 trachese diftributed along the body. They 
 accompany all the velfels, and terminate by 
 lofing themfelves ininfenfible pores at the fur- 
 face of the fkin. 
 
 Thefe infe&s appear to me to exhibit feveral 
 very evident points of analogy with vegetables. 
 
 1. Their refpiratory organs are formed in 
 the fame manner, being difpofed through the 
 whole body of the vegetable and the animal. — 
 
 2. In- 
 
12 $ 
 
 Vital Air . 
 
 2. Infe&s do not require a great degree of pu- 
 rity in the air.; and plants are nourifhed with 
 atmofphericai mephitis. — 3. Both the one and 
 the other tranfpire vital air. The abbe Fontana 
 difeovered feveral infedts in ftagnant waters* 
 which* when expofed to the fun, afforded vital 
 air : and the green matter which is formed in 
 ffagnant waters, and is by Dr. Prieftley placed 
 among the confervas, in conformity with the 
 opinion of his friend Mr. Bewley — which Mr. 
 Senebier has fuppofed to be the conferva cefpi- 
 tofa fills refits undique divergent ibus Haileri y and 
 which has appeared to Dr. Ingenhoufz to be 
 nothing *fclfe but a mafs of animalcula — affords 
 a prodigious quantity of this air when expofed 
 to the fun. — 4. Infedts likewife afford, by che- 
 mical analyfis, principles fimilar to thofe of 
 plants, fuch as refins, volatile oils, &c. 
 
 Father Vaniere appears to have known, and 
 very elegantly expreffed, the property of vege- 
 tables to fupport themfelves by means of vital 
 air : 
 
 . . . Arbor enim (res non ignota), ferarurri 
 Inftat et halituum, pifcifque latentis in imo 
 Gurgite, vitaleset reddit et accipit auras. 
 
 Proedium Rus-r ictJM, 1. vi. 
 
 Animals with lungs refpire only by virtue of 
 'the vital air which furrounds them. Any gas 
 
 deprived 
 
Vital Air . 
 
 129 
 
 deprived of this mixture becomes immediately 
 improper for refpiration: and this function is 
 exercifed with fo much the greater liberty, as 
 vital air exifts in a greater proportion in the air 
 refpired. 
 
 Count Morozzo placed fucceflively feveral 
 full-grown fparrows under aglafs bell, inverted 
 over water. It was at fir ft filled with atmo,- 
 fpherical air, and afterwards with vital air. He 
 obferved— ■ 
 
 1. In atmofpherical air. 
 
 Hours. 
 
 Min. 
 
 The firft fparrow lived 
 
 3 
 
 O 
 
 The fecond 
 
 0 
 
 .3 
 
 The third 
 
 0 
 
 1 
 
 The water rofe in the vefTel eight lines during 
 
 the life of the firft; four durin 
 
 g the life of the 
 
 fecond ; and the third produced no abforption. 
 
 2. In vital air. 
 
 Hours. 
 
 Min. 
 
 The firft fparrow lived 
 
 5 
 
 23 
 
 The fecond 
 
 2 
 
 IQ 
 
 The third 
 
 1 
 
 30 
 
 The fourth 
 
 1 
 
 IQ 
 
 The fifth 
 
 0 
 
 30 
 
 The fixth 
 
 a 
 
 47 
 
 The feventh 
 
 Q 
 
 27 
 
 The eighth 
 
 0 
 
 3Q 
 
 The ninth 
 
 0 
 
 22 
 
 The tenth 
 
 O 
 
 21 
 
 Vol. I. K 
 
 From 
 
Vital Air . 
 
 *jo 
 
 From thefe experiments ir may be concluded, 
 I. That an animal lives longer in vital air than 
 in atmofpherical air. 2. That an animal can 
 live ill air in which another has died. 3. That, 
 independent of the nature of the air, refpedt 
 muff be had totheconflitution of the animals, as 
 
 •j 
 
 the (ixth lived forty-feven minutes, and the fifth 
 only thirty. 4. That there is either ah abforp- 
 tion of air, or the production of a new kind of 
 air, which is abforbed by the water as it rifes. 
 It remains,- at prefent, to examine what are 
 
 the changes produced by refpiration. 1 . In the 
 
 ■ 
 
 air. 2. In the blood. 
 
 The gas emitted by expiration is a mixture 
 of nitrogene gas, carbonic acid, and vital air. 
 If the air which iffues from the lungs be made 
 to pafs through lime-water, it renders it tur- 
 bid ; if it be received through tin&ure of turn- 
 fole, it reddens it j and if a pure alkali be fub- 
 ftituted indead erf the tin&ure of turnfole, it 
 
 1 # 
 
 becomes effervefeent. 
 
 When the carbonic acid has been abforbed 
 by the foregoing procefs, the remainder of this 
 air confids of nitrogene gas and vital air. The 
 vital air is fhewn to be prefent by mains of ni- 
 trous air. The air in which I had caufed five 
 fparrowstoperifn, afforded feventeen hundredth 
 parts of vital air. After having thus deprived 
 ttcV* the 
 
the expired air of all its vital air, and all its car- 
 bonic acid, the remainder is nitrogene gas. 
 
 It has been obferved that frugivorous ani- 
 mals vitiate the air lefs than Carnivorous ani- 
 mals. 
 
 A portion of the air is abforbed in refpiration. 
 Borelli formerly took notice of this ; and Dr. 
 Jurin had calculated that a man infpired forty 
 cubic inches of air in his ufual inhalations,- and 
 that in the greateft he could receive two hun- 
 dred and twenty inches ; but that a portion was 
 always abforbed. The celebrated Dr. Hales 
 endeavoured to determine this abforption more 
 ftridlly, and he eftimated it at a fixty-eighth 
 of the total of the refpired air ; but he did not 
 confider it as more than a hundred and thirty- 
 fixth, on account of errors which he fuppofed 
 to have taken place. Now a man refpires twenty 
 times in a minute, and inhales forty cubic 
 inches of air at each infpiration ; this makes 
 forty-eight thoufand per hour ; which, divided 
 by one hundred and thirty-fix, gives about 
 three hundred and fifty-three inches of air ab- 
 forbed and deftroyed in the hour. The procefs 
 of Hales is not exadt ; becaufe he palled the 
 air expired through water* which mu ft have 
 retained a fenfible proportion. 
 
 From more accurate experiments, Mr. De la 
 K 2 Metherie 
 
* 3 * 
 
 Vital Air . 
 
 Metherie has proved, that three hundred and 
 fixty cubic inches oi vital air are abforbed in 
 an hour. 
 
 My experiments have not (hewn near fo great 
 a lofs. 
 
 This fadt affords a proof of the facility with 
 which air is vitiated by refpiration when it is 
 not renewed, and fhews why the air of theatres 
 is in general fo unwholefome. 
 
 II. The firiteffedt which the air appears to 
 produce upon the blood is, that of giving it a 
 vermilion-colour. If the blackilh venous blood 
 be expofed in a pure atmofphere, it becomes of 
 a vermilion-colour at its furface: this fact is 
 daily obferved when blood is fuflfered to remain 
 expofed in a porringer to the air. Air which 
 has remained in contact with blood, extin- 
 guifhes candles, and precipitates lime-water. 
 Air injedted into a determinate portion of a 
 vein between two ligatures, renders the blood 
 of a higher colour, according tQ the fine ex- 
 periments of Dr. Hewfon. 
 
 The blood which returns from the lungs is of 
 a higher colour, according to the obfervations 
 of Melfrs. Cigna, Hewfon, &c. Hence arifes 
 the great intenfity of the colour of arterial 
 blood, compared with venous blood. 
 
 Mr. Thouvenel has proved, that by with- 
 drawing 
 
Vital Air « 
 
 *33 
 
 drawing the air which is in contact with the 
 blood, it may be again made to lofe its colour. 
 
 Mr. Beccaria expofed blood in a vacuum, 
 where it remained black, but affumed the moil 
 beautiful vermilion-colour as foon as it was 
 again expofed to the air. Mr. Cigna covered 
 blood with oil, and it preferved its black co- 
 lour. 
 
 Dr. Prieftley caufed the blood of a fheep to 
 pafs fucceffively into vital air, common air, me- 
 phitic air, &c. and he found that the blackeft 
 parts affumed a red colour in refpirable air, 
 and that the intenfity of this colour was in pro- 
 portion to the quantity of vital air prefent. The 
 fame philofopher filled a bladder with blood* 
 and expofed it to pure air. That portion of 
 blood which touched the furface of the blad- 
 der, became red, while the internal part re- 
 mained black ; an abforption of air therefore 
 took place through the bladder, in the fame 
 manner as when the contadt is immediate. 
 
 All thefe fadls inconteftably prove, that the 
 vermilion-colour affumed by the blood in the 
 lungs, is owing to the pure air which combines 
 with it. 
 
 The vermilion colour of blood is therefore 
 the firft effedt of the contadf, abforption, and 
 combination of pure air with the blood. 
 
 The 
 
Vital Air . 
 
 * 34 
 
 The fecond efte<5l of refpiration is to efta- 
 blifh a real focus of heat in the lungs; which 
 is a circumftance very oppofite to the preca- 
 rious and ridiculous notion of thofe who have 
 confidcred the lungs as a kind of bellows de- 
 figned to cool the human body. 
 
 Two celebrated phyficians, Hales and Boer- 
 haave, have obferved that the blood acquired 
 heat in palling through the lungs ; and mo- 
 dem phyfiologifts have eftimated this augmen- 
 tation of heat at eleven hundredths. 
 
 The heat in each clafs of individual animals 
 is proportioned to the magnitude of their 
 lungs, according to Meflrs. De Buffon and 
 Brou (Tonne t. 
 
 Animals with cold blood have only one au- 
 ricle and one ventricle, as Ariftotle obferved. 
 
 Perfons who have refpired vital air, agree in 
 affirming that they perceived a gentle heat vi- 
 vifying the lungs, and infenfibly extendingfrom 
 the brea(f into all other parts of the body. 
 
 Ancient and modem facts unite therefore to 
 prove, that a focus of heat really exifts in the 
 lungs! and that it is maintained and kept up by 
 the air of refpiration. We are able, at prefent, 
 to explain all thefe phenomena. In fadf, there 
 is an abforption of vital air in refpiration. Re- 
 fpiration then may be conhdered as an opera- 
 tion 
 
cion by means of which vital air paiTes conti- 
 nually from the gafeous to the concrete date ; 
 it mud therefore at each indant abandon the 
 heat which held it in folution, and in the date 
 of gas. This heat produced at every infpira- 
 tion mud be proportioned to the volume of 
 the lungs, to the activity of this organ, to the 
 purity of theair, therapidity of the infpirations, 
 &c. Hence it follows that during the winter, 
 the heat produced mud be more confiderable, 
 becaufe the air is more condenfed, and exhi- 
 bits more vital air under the fame volume. By 
 the fame reafon, refpiration ought to produce 
 more heat in the inhabitants of northern cli- 
 mates ; and this is one of the caufes prepared 
 by nature to temperate, and continually ba- 
 lance, the extreme cold of thefe climates. It 
 follows likewife that the lungs of adhmatic 
 perfons are lefs capable of digeding the air; 
 and I am affured that they emit the air without 
 vitiating it ; from which caufe their complexion 
 is cold, and their lungs continually languifhing ; 
 vital air is therefore wonderfully comfortable to 
 them. It may be eafily conceived from thefe 
 principles why the heat of animals is propor- 
 tioned to the volume of their lungs ; and why 
 thofe which have only one auricle, and one 
 ventricle, have cold blood, &c. 
 
 The 
 
Vital Air. 
 
 The phenomena of refpiration are therefore 
 the fame as thofe of combuftion. 
 
 Vital air,/ by combining with the blood, 
 forms the carbonic acid, which may be confi- 
 dered as antiputrefeent as long as it remains in 
 the circulation ; and that it is afterwards emit- 
 ted through the pores of the fkin, according 
 to the experiments of the count De Milly, 
 and the obfervations of Mr. Fouquet. 
 
 Vital air has been ufed with fuccefs in certain 
 diforders of the human body. The obferva- 
 tions of Mr. Caillens are well known. He 
 caufed perfons affe&ed with phthiftcal difor- 
 ders to refpire it with the greateft fuccefs. I 
 have myfelf been a witnefsto the moil wonder- 
 ful effects of this air in a fimilar cafe. Mr. 
 
 De B was in the laft ftage of a confirmed 
 
 phthifis. Extreme weaknefs, profufe fweats, a 
 flux of the belly, and in fhort every fymptom, 
 announced the approach of death. One of my 
 
 friends, Mr. DeP , put him uponacourfe 
 
 of vital air. The patient refpired it with de- 
 light, and afked for it with all the eagernefs of 
 an infant at the breaft. During the time that 
 lie refpired it he felt a comfortable heat, w j hich 
 diftributed itfelf through all his limbs. Hi* 
 ftrength increafed with the greateft rapidity; 
 and in fix weeks he was able to take long walks. 
 
 This 
 
Vital Air . 
 
 '*37 
 
 This flate of health laded for fix months : 
 but after this interval he relapfed ; and being 
 no longer able to have recourfe to the ufe of 
 
 vital air, becaufe Mr. De P had departed 
 
 for Paris, he died. — I am very far from being 
 of opinion that the refpiration of vital air ought 
 to be confidered as a fpecific, in cafes of this 
 nature. Iam even in doubt whether this pow- 
 erful air is perfectly adapted to fuch circum- 
 (lances ; but it infpires cheerfulnefs, renders 
 the patient happy, and in defperate cafes it is 
 moll certainly a precious reqpedy, which can 
 fpread flowers on the borders of the tomb, and 
 prepare us in the gentled manner for the lad 
 dreadful effort of nature. 
 
 The abfolute neceflity of vital air in refpira- 
 tion, enables us to lay down pofitive principles 
 for purifying the corrupted air of any given 
 place. This may be done in three ways. The 
 fir A conflfls in corredling the vitiated air by 
 means of fubflances which are capable of feiz- 
 ing the noxious principles. The fecond con- 
 fids in difplacing the corrupted air, and fubfli- 
 tuting frefh air in the room of it ; as is done by 
 means of ventilators, the agitation of doors, 
 &c. And the third conflds in pouring into 
 the mephitifed atmofphere a new quantity of 
 vital air. 
 
 The 
 
*3 8 Nitrogen? Gas, or 
 
 The proCefies employed in purifying cor- 
 rupted air, are not all certain in their effe&s. 
 The fires which are lighted for this purpofe 
 have no other advantage than to eftablilh af- 
 cending currents, and to burn unhealthy exha- 
 lations; and perfumes do nothing more than 
 difguife the bad fmell, without changing the 
 nature of the air, as the experiments of Mr. 
 Achard fiiew. 
 
 CHAP. III. 
 
 Concerning Nitrogene Gas , Azote , or Atmofphe - 
 rical Mephitis . 
 
 TT has been long fince afcertained, that air 
 -*■ which has ferved the purpofes of combuf- 
 tion and refpiration, is no longer proper for 
 thofe ufes ; the air thus corrupted has been 
 diftinguifhed by the names of Phlogifticated 
 Air, Mephitifed Air, Atmofpherical Mephitis, 
 &c. I call it Nitrogene Gas, for the reafons 
 explained in the Preliminary Difcourfe. 
 
 But this refidue of combuftion or refpiration 
 is always mixed with a fmall quantity of vital 
 air and carbonic acid, which muft be removed 
 in order to have the nitrogene gas in a ftate 
 of purity. There are feveral methods which 
 
 may 
 
Atfnofpherical Mephitis . 1 39 
 
 maybeufed to obtain nitrogene gas, in a very 
 pure ftate. 
 
 1. Scheele has taught us, that by expofing 
 fulphure of alkali, or liver of fulphur, in a vef- 
 fel filled with atmofpherical air, the vital air is 
 abforbed ; and, when the abforption is com- 
 plete, the nitrogene gas remains pure. 
 
 By expofing, inatmofphericairover mercury, 
 a mixture of iron and fulphur, kneaded toge- 
 ther with water, Mr. Kirwan obtained nitro- 
 gene gas fo pure, that it fuffered no diminution 
 by nitrous gas. He deprived it of all humidity, 
 by fucceflively introducing dried blotting-paper 
 into the veffel which contained it. Care muft 
 be taken to withdraw this air in time from the 
 pafte which affords it ; otherwife it will be mixed 
 with hydrogene or inflammable gas, which is 
 afterwards difengaged. 2. When by any means, 
 fuch as the oxidation of metals, the rancidity of 
 oils, the combuftion ofphofphorus, &c. the vital 
 air of the atmofphere is abforbed, the refidue is 
 nitrogene gas. All thefe procelfes afford me- 
 thods of greater or lefs accuracy to determine 
 the proportions of viral air and nitrogene gas 
 in the compofition of the atmofphere. 
 
 3. This mephitis may likewife be procured 
 by treating mufcular fiefh, or the well-wafhed 
 •fibrous part of blood, with nitric acid in the 
 
 hydro- 
 
140 
 
 Kitrogene Gas • 
 
 hydro-pneilmdtic apparatus. But it mud be 
 carefully obferved that thefe animal matters 
 ought to be frefh • for, if they have begun to 
 be changed by the putrid fermentation, they 
 afford carbonic acid mixed with hydrogenc 
 gas. 
 
 A. This gas is improper for refpiration and 
 combufhon. 
 
 B. Plants live in this air, and freely vege- 
 tate in it. 
 
 C. This gas mixes with the other airs, with- 
 out combining with them. 
 
 D. It is lighter than the atmofpheric air, the 
 barometer ftanding at 30.46, and Fahrenheit’s 
 thermometer at 60 : the weight of nitrogene 
 gas is to that of common air as nine hundred 
 and eighty-five to one thoufand. 
 
 E. Mixed with vital air, in the proportion 
 of 72 to 28, it conftitutes our atmofphere. 
 The other principles which analyfis exhibits in 
 the atmofphere, are only accidental, and by- 
 no means neceffary. 
 
Atmofpheric Air* 
 
 24 1 
 
 SECTION VI. 
 
 Concerning the Mixture of Nitrogene and 
 Oxigene Gas ; or of Atmofpheric Air. 
 
 T H E gafeous fubftances we have treated 
 of feldom exift alone and infulated ; na- 
 ture prefents them every where to our obferva- 
 tion in a ftate of mixture or of combination. 
 In the firft cafe thefe gafes preferve the aeri- 
 form ftate ; in the fecond they for the molt 
 part form fixed and folid bodies. Nature, in 
 its feveral decompofttions, reduces almolt all 
 the principles of bodies into gas. Thefe new 
 fubftances unite together, combine, and from 
 thence refult compounds of conftderable fim- 
 plicity in their principles, but which become 
 complicated by fubfequent mixture and com- 
 binations. We may follow the operations of 
 nature, ftep by ftep, without departing from 
 the plan we have adopted. 
 
 The mixture of about fevcnty-two parts of 
 nitrogene gas, and twenty- eight of oxigene, 
 forms this Huid mafs in which we live. Thefe 
 two principles are fo well mixed, and each of 
 them is fo neceflary to the fupport of the va- 
 rious functions of individuals w 7 hich live or 
 
 vegetate 
 
14 - Atmofpheric Air . 
 
 vegetate upon the globe, that they have not 
 yet been found feparate and alone. 
 
 The proportion of thefc two gafes is fub- 
 jc<fl to variation in the mixture which forms 
 the atmofphere : but this difference depends 
 only upon local caufes : and the moft ufual 
 proportion is that which we have here men- 
 tioned. 
 
 • * 4 ■ ? * r r* 
 
 The charaCteriftic properties of vital air are 
 modified by thofe of nitrogene gas, and thefe 
 modifications even feem to be neceffary; for if 
 we were to refpire vital air in its ftate of purity, 
 it would quickly confume our life ; and this 
 virgin air is no more fuitable to our exigence 
 than diftilled water. Nature does not appear 
 to have defigned us for the ufe of thefe prin- 
 ciples in their greatefl degree of perfection. 
 
 The atmofpheric air is elevated feveral 
 leagues above our heads, and fills the deepeft 
 fubterraneous cavities. It is invifible, infipid, 
 inodorous, ponderous, elaftic, &c. It was the 
 only gafeous fubftance known before the pre- 
 fent epocha of chemiflry ; and the infinite gra- 
 dations of all the invifible fluids which prefent- 
 ed themfeves fo frequently to the obfervation 
 of philofophers, were always attributed to mo- 
 difications of the air. Almoft the whole of 
 what has been written upon the air relates only 
 
 to 
 
Atmofpheric Air. 143 
 
 to its phyfical properties. We fhall confine 
 ourfelves to point out the chief of thefe. 
 
 A. Air is a fluid of extreme rarefadion, obe- 
 dient to the fmalleft motion : the flighted per- 
 cuflion deranges it ; and its equilibrium, which 
 is continually deftroyed, is continually endea- 
 vouring to reflore itfelf. 
 
 Though very fluid, it pafles with difficulty 
 through orifices by means of which groffer li- 
 quids can eafily penetrate. This has caufed 
 philofophers to fuppofe that its parts were of 
 a branched form *. 
 
 B. The atmofpheric air is invilible. It re- 
 fradls the rays of light without refleding them : 
 for it is without fufficient proofs that fome 
 philofophers have imagined that large mafles 
 of this fluid are of a blue colour. 
 
 It appears that the air is inodorous itfelf ; 
 though it is the vehicle of odorant particles. 
 
 It may be confidered as inflpid ; and when 
 its contad affeds us varioufly, We ought tc at- 
 tribute it to its phyfical qualities. 
 
 C. It was not until the middle of the lafi: 
 
 * This is a deception. It is true that the cohefive attrac- 
 tion renders it difficult to difplace any denfe fluid from a ca- 
 pillary tube by the intrufion of air; but every experiment of 
 the air-pump, the condenfor, and the barometer, (hews with 
 what facility the air pafles through the fmallefl orifices. T. 
 
 century 
 
*44 Atmofpberic Air . 
 
 century that its weight was afcertained by ac~ 
 curate experiments. The impoflibility of fup- 
 porting water in a tube open at the bottom, to a 
 greater height than thirty-two feet, caufed Tor- 
 ricellius to fufpedf that an external caufe fup- 
 ported the liquid at that height, and that it was 
 jiotthe horror of a vacuum which precipitated 
 the water in the barrels of pumps. This cele- 
 brated philofopher filled a tube clofed at one of 
 its extremities with mercury : he reverfed this 
 into a veffel filled with the fame metal ; and ob- 
 ferved that the mercury, after feveral ofcilla- 
 tions, conftantly fubfided to the height of twen- 
 ty-eight inches. He immediately faw that the 
 difference of elevations correfponded with the 
 relative weights of thefe two fluids, which are in 
 the proportion of fourteen to one. The immor- 
 tal Pafchal proved, fome time afterwards, that 
 liquids were fupported at this elevation by a 
 column of atmofpherical air ; and afcertained 
 that their height varies according to the length 
 of the column which prefies upon them, 
 
 D. The elafticity of the air is one .of the 
 properties upon which natural philofophers 
 have made the greateft number of experiments $ 
 and it has even been applied to confiderable 
 advantage in the arts. 
 
 SEC- 
 
The Component Parts of Wafer 
 
 * 4 $ 
 
 SECTION VIE 
 
 Concerning the Combination of Oxigenous 
 Gas and Hydrogene, which forms Water. 
 
 W ATER has been long confidered as 
 an elementary principle ; and when 
 accurate experiments had compelled chemifts 
 to clafs it among compound fubftances, a refin- 
 ance and oppofition were made to it, which were 
 not manifefted when the air, the earth, and the 
 other matters reputed to be elementary, were 
 fubjedted to fimilar revolutions. It feems to 
 me, however, that this analyfis is equally ftridt 
 with that of the air. Water is decompofed by 
 fevcral proceffes ; it is formed by the combi- 
 nation of oxigene and hydrogene : and we find 
 that all the phenomena of nature and art con- 
 fpire to prove the fame truth. What more 
 can be required to afford an abfolute certainty 
 refpeding any phyfical fadt ? 
 
 Water is contained in bodies in a greater or 
 lefs quantity, and may be confidered in two 
 Vol. I. L Hates : 
 
146 General Properties of Water. 
 
 dates : it is either in the date of fimple mix- 
 ture, or in a date of combination. In the firft 
 cafe, it renders bodies humid, is perceptible to 
 the eye, and may be difengaged with thegreated 
 facility. In the fecond, it exhibits no charac- 
 ter which fhews that it is in a date of mixture. 
 It exids in this form in crydals, falts, plants, 
 animals, &c. It is this water which the cele- 
 brated Bernard has called Generative Water ; 
 and of which he has made a fifth element, to 
 didinguifh it from exhalative water. 
 
 Water, exiding in a date of combination in 
 bodies, concurs in imparting to them hardnefs 
 and tranfparency. Salts, and mod dony crys- 
 tals, lofe their tranfparency when they are de- 
 prived of their water of crydallization. 
 
 Some bodies are indebted to water for their 
 fixity. The acids, for example, acquire fix- 
 ity only by combining with water. 
 
 Under thefe various points of view, water 
 may be confidered as the general cement of 
 nature. The dones and falts which are depriv- 
 ed of it, become pulverulent ; and water faci- 
 litates the coagulation, re-union, and confid- 
 ence of the particles of dones, falts,&c. as we 
 ihall fee in the operations performed with 
 pladers, lutes, mortar, &c. 
 
 Water, when difengaged from its combina- 
 tions. 
 
147 
 
 Properties of Water . 
 
 tions, and in a flare of abfolute liberty, is one 
 of the moft confiderable agents in the opera- 
 tions of this globe. It bears a part in the for- 
 mation and decompofition of all the bodies of 
 the mineral kingdom: it is neceifary to vegeta- 
 tion, and to the free exercife of mod of the 
 functions of animal bodies ; and it haftens and 
 facilitates the deflrudiion of thefe bodies, asfoon 
 as they are deprived of the principle of life. 
 
 For a certain time water was thought to be a 
 fluid earth. The diflillation, trituration, and 
 putrefaction of water, which always left an 
 earthy refidue, afforded credit to an opinion 
 that it was converted into earth. On this 
 fubject, the works of Wallerius and Margraff 
 may be confulted: but Mr. Lavoilier has 
 ihewn that this earth arifes from the. wear of 
 the veffels; and the celebrated Scheele has 
 proved the identity of the nature of this earth 
 with that of the glafs velTels in which the ope- 
 rations were made. So that the opinions of 
 the philofophical world are at prefent decided 
 in this refped:. 
 
 In order to obtain accurate ideas of a fub- 
 fiance fo neceffary to be knowm, we will conii- 
 der water under its three different Hates of fo- 
 lidity, fluidity, and gas. 
 
 L 2 
 
 ART I- 
 
Iqs 
 
 IVater in the Solid State • 
 
 ARTICLE I. 
 
 Concerning Water in the State of Ice. 
 
 Ice is the natural Rate of water, whenever it 
 is deprived of a portion of that caloric with 
 which it is combined when it appears in the 
 form of a liquid or gas. 
 
 Theconverfion into ice is attended with fe- 
 veral phenomena which feldom vary. 
 
 A. The firfl of all, and at the fame time the 
 mod extraordinary, is a fenfible production of 
 heat at the moment in which the water pafles 
 to the folid date. The experiments of Meflrs. 
 Fahrenheit, Treiwald, Baume, De Ratte, leave 
 no doubt on this fubjeCt; fo that the water is 
 colder at the indant of congelation than the 
 ice itfelf. 
 
 A flight agitation of the fluid facilitates its 
 converfion into ice, nearly in the fame manner 
 as the flighted motion very frequently deter- 
 mines the crydallization of certain falts. This 
 arifes, perhaps, from the circumftance, that by 
 this means the caloric, which is interpofed be- 
 tween the particles, and may oppofe itfelf to 
 the production of the phenomenon, may be 
 
 exprefled 
 
Water in the Solid State . 1 49 
 
 exprelfed or difengaged . In proof of this opini- 
 on, it is feen that the thermometer rifes at the 
 very fame inflant, according to Fahrenheit. 
 
 B. Frozen water occupies a larger fpace than 
 fluid water: we are indebted to the Academy 
 del Cimento for the proofs of this truth. In 
 their experiments, bomb fhells, and the flrong- 
 eft velfels, being filled with water, were burft 
 into pieces by the congelation of this fluid. 
 The trunks of trees are divided and fplit with 
 a loud noife, as foon as the fap freezes ; and fo 
 likewife Hones are broken in pieces the mo- 
 ment the water with which they are impreg- 
 nated paffes to the Hate of ice. 
 
 C. Ice appears to be nothing more than a 
 confufed cryflallization. Mr. De Mairan ob- 
 ferved that the needle-formed cryHals of ice 
 unite in an angle of either fixty or one hundred 
 and twenty degrees. 
 
 Mr. Pelletier obferved, in a piece of fiflulous 
 ice, cryHals in the form of flattened triangular 
 prifms, terminated by two dehedral fummits. 
 
 Mr. Sage obferves, that if a piece of ice, 
 which contains water in its internal parts, be 
 broken, the water runs out, and the internal 
 cavity is found to be lined with beautiful tetra- 
 hedral prifms, terminated in four-flded prifms. 
 Thefe prifms are often articulated and crofled. 
 
 Vide 
 
1 50 Water in the Solid State. 
 
 Vide M. Sage, Annales de Chimie, tom. i. 
 
 P- 77* 
 
 Mr. Macquart has obferved, that when it 
 fnows at Mofcow, and the atmofphere is not 
 too dry, the air is obferved to be loaded with 
 beautiful cry ftallizations regularly flattened, and 
 as thin as a leaf of paper. They conlift of an 
 union of fibres which (hoot from the fame cen. 
 tre to form fix principal rays, and thefe rays 
 divide themfelves into lmall blades extremely 
 brilliant : he obferved feveral of thefe flattened 
 radii which were ten lines in diameter. 
 
 D. When water pafles from the folid to the 
 liquid ftate, it produces cold by the abforption 
 of a portion of heat, as is confirmed by the fine 
 experiments of Wilcke. This production of 
 cold, by the fufion of ice, is likewife proved 
 by the practice of the confectioners, who fufe 
 certain falts with ice, in order to produce a 
 degree of cold below o. 
 
 Ice is found in many places in great maffes, 
 known by the name of Giacieres ; certain moun- 
 tains are confiantly covered with them, and the 
 fouthern ocean abounds with them. The ice 
 formed by fait v/atef affords frefh water when 
 melted ; and in feveral northern provinces water 
 is faid to be concentrated byfrofi, to colled: the 
 fall it holds in folution. I have likewife ob- 
 ferved. 
 
IVatev in the Solid State . 151 
 
 obferved, that feveral metallic falts are pre- 
 cipitated by expofing their folutions to a tem- 
 perature fufficient to freeze them. The ice 
 which was formed did not pofTefs the charac- 
 ters of the fait which had been diflolved. 
 
 Hail and fnoware nothing but modifications 
 of ice. We may confider hail as produced by 
 the fudden difengagement of the elaftic fluid, 
 which concurs in rendering water liquid : it is 
 almoft always accompanied with thunder. The 
 experiments of Mr. Quinquet have confirmed 
 this theory. — I will here relate a fad: to which 
 I myfelf was witnefs, at Montpelier, and of 
 which philofophers may advantageoufly avail 
 themfelves. On the 29th of Odober, 1786, 
 four inches of water fell at Montpelier; a vio- 
 lent explofion of thunder, which was heard about 
 four in the evening, and which appeared to be 
 very near, caufed a moft dreadful ihower of 
 hail. At this inftant adruggift, who was em- 
 ployed in his cellar in preventing the mifchief 
 occafioned by the filtration of water through the 
 wall, was highly aftonifhed to behold that the 
 water which came through the wall was inflantly 
 changed into ice. He called in feveral neigh- 
 bours to partake of his furprife. I vifited the 
 place a quarter of an hour afterwards, and found 
 jten pounds of ice at the foot of the wall ; I was 
 
 •well 
 
152 
 
 Water in the Liquid State . 
 
 well allured that it could not have palled through 
 the wall, which did not exhibit any crack, but 
 appeared to be in very good condition. Did 
 the fame caufe, which determined the forma- 
 tion of hail in the atmofphere, adt equally in 
 this cellar ? — I relate the fadt only, and forbear 
 to make any conjefture upon it. 
 
 ARTICLE II. 
 
 Concerning Water in the Liquid State. 
 
 The natural Hate of water appears to be that 
 of ice : but its moft ufiial ftate is that of fluidity ; 
 and under this form it polfelTes certain general 
 properties, which we fhall proceed to defcribe. 
 
 The experiments of the Academy del Ci- 
 mento have caufed the philofophical world to 
 deny the leaft elalticity to water, becaufe it 
 efcaped through the pores of balls of metal 
 flrongly comprelfed, rather than yield to pref- 
 fure. But Melfrs. Zimmerman, and the abbe 
 Mongez, have endeavoured to prove its elafti— 
 city from the very experiments upon which the 
 contrary opinion has been built*. 
 
 The 
 
 * The experiments of Canton, to prove the compreffibility 
 ©f water, are well known, and may be feen in the Philofo- 
 ' phical 
 
Water in the Liquid State . 153 
 
 The liquid date renders the force of aggre- 
 gation in water lefs powerful, and it enters 
 into combination more readily in this form. 
 Water which flows on the furface of our globe 
 is never pure. Rain-water is feldom exempt 
 from fome mixture, as appears from the fine fe- 
 ries of experiments of the celebrated MargrafF. 
 I have afcertained, at Montpelier, that the rain- 
 water in dorms is more impure than that of a 
 gentle fhower — that the water which falls fird 
 is lefs pure than that which falls after feveral 
 hours or feveral days rain — that the water 
 which falls when the wind blows from the fea 
 to the fouthward, contains fea-falt ; whereas 
 that which is produced by a northerly wind, 
 does not contain a particle. 
 
 Hippocrates has made feveral very important 
 obfervations refpedting the various qualities of 
 water, relative to the nature of the foil, the tem- 
 perature of the climate, &c. 
 
 As it is of importance to the chemid to have 
 very pure water for feveral delicate operations, 
 
 phical Tranfadlions. He enclofed water in fpherical glafs 
 veflels, from which a narrow neck proceeded, like that of a 
 thermometer : the water was found to occupy a larger fpace 
 when the preffure of the atmofphere was removed by the air- 
 pump, and a lefs fpace when a greater preffure was added by 
 the condenfor . T. 
 
 it 
 
1 5 4 'Dijlillation of Water. 
 
 it is neceflary to point out the means which 
 may be ufed to carry any water whatever to this 
 degree of purity. 
 
 Water is purified by didillation. This ope- 
 ration is performed inveffels called Alembics. 
 The alembic is compofed of two pieces ; a boiler 
 or cucurbit, and a covering called the capital 
 or head. 
 
 The water is put into the cucurbit, from 
 which it is raifed in vapours by means of fire, 
 and thefe vapours are condenfed by cooling 
 the head with cold water. The condenfed va- 
 pours flow into a veflel defigned to receive 
 them. This is called Diftilled Water; and is 
 pure, becaufe it has left behind it in the cucur- 
 bit the falts and other fixed principles which 
 altered its purity. 
 
 Diftillation is more fpeedy and quick, in pro- 
 portion as the p re flu re of the air is lefs upon 
 the furface of the ftagnant fluid. Mr. Lavoifier 
 diddled mercury in vacuo; and the abbe Rochon 
 has made a bappy application of thefe prin- 
 ciples to diflillation. It is to this fame prin- 
 ciple that we mud refer the obfervations of al- 
 mofl all naturalifls and philofophers, who have 
 remarked, that the ebullition in the liquid be- 
 comes more eafy, in proportion as we afeend a 
 mountain from any other elevation ; and it is 
 
 in 
 
Dijlillation of Water* jjj 
 
 in confequence of thefc principles, that Mr, 
 Achard conftrudled an inftrument to determine 
 the heights of mountains, by the degrees of tem- 
 perature of the ebullition of boiling water. 
 
 The abbe Mongez, and Mr. Lamanow, ob- 
 ferved that ether evaporates with prodigious fa- 
 cility upon the peak of Teneriffe; and Mr. De 
 SaufTure has confirmed thefe experiments on 
 the mountains of Switzerland. 
 
 A true diftillation is carried on every where 
 at the furface of our globe. The heat of the 
 fun raifes water in the form of vapours; thefe 
 remain a certain time in the atmofphere, and 
 afterwards fall in the form of dew, by fimple 
 refrigeration. This rife and fall of humidity, 
 which fucceed each other, wafh and purge the 
 atmofphere of all thofe particles, which by their 
 corruption or development might render it in- 
 fectious; and it is perhaps this combination of 
 variotilr miafmata with water which renders the 
 evening dew fo unwholefome. 
 
 It is to a fimilar natural diftillation that we 
 ought to refer the alternate tranlition of water 
 from the liquid ftate to that of vapour, which 
 forms clouds, and by this means conveys the 
 water from the fea to the fummits of mountains, 
 from which it is precipitated in torrents, to re- 
 turn again to the common receptacle. 
 
 We 
 
156 Water in the State of Gas • 
 
 We find traces of the diftillation of water in 
 the mod: remote ages. The firft navigators in 
 the illands of the Archipelago filled their pots 
 with falt-water, and received the vapour in 
 fponges placed over them. The procefs of dif- 
 tilling the water of the fea has been fucceflively 
 brought to perfection ; and Mr. PoifTonnier has 
 exhibited a very well conftructed apparatus to 
 procure frefh water at all times in abundance. 
 
 Pure water requires to be agitated, and com- 
 bined with the air of the atmofphere, to render 
 it wholefome. Hence, no doubt, it is, that 
 water immediately produced by melting fnow, 
 is unfit to drink. 
 
 The characters of potable water are the fol- 
 lowing : 
 
 1. A lively, frefh, and agreeable tafte. 
 
 2. The property of boiling readily, and alfo 
 that of boiling peafe and other pulfe. 
 
 3. The virtue of diflolving foap without 
 curdling. 
 
 ARTICLE III. 
 
 Concerning Water in the State of Gas. 
 
 Many fubdances are naturally in the ftate of 
 an aeriform fluid, at the degree of the tempera- 
 ture 
 
3 57 
 
 Water in the State of Gas . 
 
 ture of our atmofphere : fuch, for example, are 
 the carbonic acid ; and the oxigenous, the hy- 
 drogenous, and the nitrigenous gafes. 
 
 Other fubftances evaporate at a degree of 
 heat very near that in which we live. Ether 
 and alcohol are in this fituation. The fir ft of 
 thefe liquors pafles to the ftate of gas at the 
 temperature of 35 degrees; the fecond, at that 
 of 80 (of Reaumur). 
 
 Some fluids require a ftronger heat for this 
 purpofe ; fuch as water, the fulphuric and nitric 
 acids, oil, &c. 
 
 To convert water into an aeriform fluid, 
 Meflrs. De la Place and Lavoifler filled a glafs 
 veflel with mercury, and reverfed it over a difli 
 filled with the fame metal. Two ounces of wa- 
 ter were transferred beneath this veflel; and the 
 mercury was heated to the temperature of be- 
 tween ninety-five and a hundred of Reaumur, 
 by plunging it in a boiler filled with the mother 
 water of nitre. The included water became ra- 
 refied, and occupied the whole capacity. 
 
 Water, by pafling through earthen veflcls ig- 
 nited in the fire, becomes converted into gas, 
 according to Prieftley and Kir wan. The aeoli- 
 pile, the fleam-engine, the digefter of Papin, 
 and the procefs of the glafs-blowers, who blow 
 large globes by injecting a mouthful of water 
 
 through 
 
1 5 8 Water in the State of Gas • 
 
 through their iron tube, prove the converfion 
 of water into gas. 
 
 It follows from thefe principles, that the vo- 
 latilization of water being nothing more than a 
 diredl combination of caloric with this liquid, 
 the portions of water which arc the moft imme- 
 diately expofed to heat, muff be the firft vola- 
 tilized : and this is daily obferved ; for it is con- 
 tinually feen that ebullition begins at the part 
 moft heated. But when the heat is applied 
 equally at all parts, the ebullition is general. 
 
 Several phenomena have led us to believe that 
 water may be converted into air. The procefs 
 of the glafs-biowers to blow large fpheres ; the 
 hydraulic organ of father Kircher; the pheno- 
 mena of the asolipile ; the experiments of 
 Mefirs. Prieftley and Kirwan ; the manner of 
 affiftingcombuftion, by fprihklinga froall quan- 
 tity of water upon the coals — all thefe cir- 
 cumftances appeared to announce the conver- 
 fion of water into air. But it was far from be- 
 ing fuppofed that moft of thefe phenomena 
 were produced by the decompofition of this 
 fluid ; and the genius of Mr. Lavoifier was ne- 
 ceftary to carry this point of dodtrine to the 
 degree of certainty and precifion, which in my 
 opinion it now appears to poffefs. 
 
 Mefirs. Macquer and De la Metherie had 
 
 already 
 
*5 9 
 
 Compofition of Water . 
 
 already obferved, that the combuftion of in- 
 flammable air produced much water. Mr. Ca- 
 vendifh confirmed thefe experiments in Eng- 
 land, by the rapid combuftion of inflammable air 
 and vital air. ButMefTrs. Lavoifter, De la Place, 
 Monge, and Meufnier, have proved that the 
 whole mafs of the water might be converted into 
 hydrogene and oxigene ; and that the combuf- 
 t«on of thefe two gafes produced a volume of 
 water proportioned to the weight of the two 
 principles employed in this experiment. 
 
 i. If a fmall glafs veflel be inverted over 
 mercury, and a known quantity of diftilled wa- 
 ter and filings of iron be put into the upper 
 part of this yeflel, inflammable air will be gra- 
 dually difengaged, the iron will ruft, and the 
 water w r hich moiftens it will diminifh, and at 
 length difappear ; the weight of the inflamma- 
 ble air which is produced, and the augmenta- 
 tion in weight of the iron, will be equivalent to 
 the weight of the water made ufe of. It ap- 
 pears therefore to be proved, that the water is 
 reduced into two principles, the one of which is 
 inflammable air, and the other is the principle 
 which has entered into combination with the 
 metal. Now we know that the oxidation or 
 calcination of metals is otving to vital air ; and 
 confequently the two fubftances produced, 
 
 namely 
 
160 Compofition of Water, 
 
 namely the vital air and inflammable air, arife 
 from the decompofllion of water. 
 
 2. When water is converted into the ftateof 
 vapour, in its paflage through an ignited iron 
 tube, the iron becomes oxided, and hydrogene 
 is obtained in the ftate of gas. The augmen- 
 tation of weight in the metal, and the weight 
 of the hydrogene obtained, form precifely a 
 fum equal to that of the water employed. 
 
 The experiment made at Paris, in the pre- 
 fence of a numerous commiflion of the Aca- 
 demy, appears to me to leave no further doubt 
 concerning the decompofltion of water. 
 
 A gun-barrel was taken, into which a quan- 
 tity of thick iron wire, flattened by hammering, 
 was introduced. The iron and the gun-barrel 
 were weighed : the gun-barrel was then covered 
 'with a lute proper to defend it from the contad: 
 of the air; it was afterwards placed in a furnace, 
 and inclined in luch a manner as that water 
 might run through it. At its mod elevated 
 extremity was fixed a funnel deflgned to con- 
 tain water, and to let it pafs drop by drop by 
 means of a cock : this funnel was clofed, to 
 avoid all evaporation of the water. At the 
 other extremity of the gun-barrel was placed a 
 tubulated receiver, intended to receive the wa- 
 ter which might pafs without decompofltion; 
 
 . - and 
 
Compofition of Water. 1 6 1 
 
 and to the tubulure of the receiver the pneu- 
 mato-chemical apparatus was adapted. For 
 greater precaution, a vacuum was made in the 
 whole apparatus before the operation began. 
 Laftly, as foon as the gun-barrel was red-hot, 
 the water was introduced drop by drop. Much 
 hydrogenous gas was obtained: and at the end 
 of the experiment the gun-barrel was found to 
 have acquired weight ; and the flat pieces of 
 iron included within were converted into a 
 flratum of black oxide of iron, or Ethiops 
 martial, cryftallized like the iron ore of the 
 ifland of Elba. It was afcertained that the iron 
 was in the fame ftate as that which is burned in 
 oxigenous gas ; and the increafed weight of the 
 iron, added to that of the hydrogene, was ac- 
 curately equal to that of the water employed. 
 
 The hydrogenous gas obtained was burned 
 with a quantity of vital air equal to that which 
 had been retained by the iron, and the fix 
 ounces of water were recompofed. 
 
 3^'Mcflrsj. Lavoifier and De la Place, by 
 burning in a proper apparatus a mixture of 
 fourteen parts of hydrogenous gas, and eighty- 
 fix of oxigene, obtained a proportionate quan- 
 tity of water. Mr. Monge obtained the fame 
 refult at Mezieres, at the fame time. 
 
 The moft conclufive and the moll authentic 
 Vol. L M experi- 
 
i 62 
 
 Compofition of Water . 
 
 experiment which was made upon the compo- 
 fition or fynthefis of water, is that which was 
 begun on the 23d of May, and ended on the 
 7th of June, 1788, at the Royal College, by 
 Mr. Lefevre de Gineau. 
 
 The volume of oxigenous gas confumed, 
 when reduced to the preffure of twenty-eight 
 inches of mercury, at the temperature of ten 
 degrees of the thermometer of Reaumur, was 
 35085 (French) cubic inches, and its weight 
 2 5bgros 10,5 grains. 
 
 The volume of hydrogenous gas was 74967,4 
 cubic inches, and the weight 66 gros 4,3 
 grains. 
 
 The nitrogenous gas and the carbonic acid 
 which were mixed with thefe gafes, and which 
 had been extracted out of the receiver at nine 
 feveral times, weighed 39,23 grains. 
 
 The oxigenous gas contained T V of its weight 
 of carbonic acid ; fo that the weight of the 
 gafes burned was 280 gros 63,8 grains, which 
 makes 2 pounds 3 ounces o gros 63,8 grains. 
 
 The veffels were opened in the prefence of 
 the gentlemen of the Academy of Sciences, and 
 feveral other learned men, and were found to 
 contain 2 pounds 3 ounces o gros 33 grains of 
 water : this weight anfwers to that of the gafes 
 made ufe of, wanting 3 1 grains ; this deficiency 
 
 may 
 
Compsfilion of Water. 163 
 
 may arifc from the caloric which held the gafes 
 in folution being diflipated when they became 
 fixed, which mud necedarily have occadoned 
 a lofs. 
 
 The water was fubacid to the tade, and af- 
 forded 27I grains of nitric acid, which acid is 
 produced by the combination of the nitrogene 
 and oxigene gafes. 
 
 From the experiment of the decompofition 
 of water, 100 parts of this fluid contained 
 Oxigene 84,2636 = 844. 
 
 Hydrogene 15,7364=151. 
 
 According to the experiment of its compofi- 
 tion, 100 parts of water contained 
 Oxigene 84,8 = 844.. 
 
 Hydrogene 15,2 == 15*. 
 
 Independent of thefe experiments of analyfis 
 and fynthefis, the phenomena exhibited by wa- 
 ter, in its feveral dates, confirm our ideas with 
 
 * ■ r* 
 
 regard to the condituent parts which we ac- 
 knowledge it to poflefs. The oxidation of 
 metals in the interior parts of the earth, at a 
 didance from the atmofpherical air, the efflo- 
 refcence of pyrites, and the formation of ochres, 
 are phenomena which cannot be explained 
 without the adidance of this theory. 
 
 Water, being compofed of tw T o known prin- 
 ciples, mud ad: like all other compound bodies 
 / M2 which 
 
164 Compofition of Water , 
 
 which we know ; that is, according to the 
 affinities of its conftituent parts. It muft there- 
 fore in fome inftances yield its hydrogene, and 
 in others its oxigene. 
 
 If it be placed in contadt with bodies which 
 have the ftrongeft affinity with oxigene, fuch as 
 the metals, oils, charcoal, &c. the oxigenous 
 principle will unite with thefe fubftances ; and 
 the hydrogene, being fet at liberty, will be dif- 
 fipated. This happens when hydrogene gas is 
 difengaged, by caufing the acids to adt upon 
 certain metals ; or when red-hot iron is plunged 
 in water, as Meflrs. Haflenfratz, Stoulfz, and 
 D’Hellancourt have obferved. 
 
 In vegetables, on the contrary, it feems that 
 the hydrogene is the principle which fixes it- 
 felf; while the oxigene is eafily difengaged, 
 and makes its efcape. 
 
Of Alkalis * 
 
 16s 
 
 SECTION VIII. 
 
 Concerning the Combinations of Nitrogene 
 Gas, 1. With Hydrogene Gas. 2. With 
 the Earthy Principles for ming the Alkalis. 
 
 I T appears to be proved, that the combina- 
 tion of nitrogene gas with hydrogene forms 
 one of the fubftances comprifed in the clafs of 
 alkalis. It is very probable that the others are 
 compofed of this fame gas and an earthy bans. 
 It is from thefe confederations that we have 
 thought proper to place thofe fubftances here: 
 and we have adopted that decifion with fo much 
 the more foundation, becaufe the knowledge of 
 alkalis is indifpenfably neceflary to enable us to 
 proceed with order in a courfe of chemiftry ; 
 and becaufe thefe re-agents are moft frequent- 
 ly employed, and their combinations a^d ufes 
 prefent themfelves at every ftep in the pheno- 
 mena of nature and art. 
 
 It is an eftablifhed convention to call every 
 fubftance an Alkali, which is chara&erifed by 
 the following properties: 
 
 A. An acrid, burning, urinous tafbe. 
 
 B. The property of converting fyrup of vio- 
 lets green ; but not the tin&ure of turnfole, as 
 certain authors announce. 
 
 C. The 
 
1 66 Char afters of Alkalis . 
 
 C. The virtue of forming glafs, when fufed 
 with quartzofe fubftances. 
 
 D. The faculty of rendering oils mifcible 
 with water; of effervefcing with certain acids; 
 and of forming neutral fairs with all of them. 
 
 I muft obferve that none of thefe characters 
 is rigorous and exciufive; and that confequent- 
 ly no one of them is fufficient to afford a cer- 
 tainty of the exigence of an alkali : but the re- 
 union of feveral forms, by their concurrence, 
 a mafs of proofs or indications, which lead us 
 to fufficient evidence. 
 
 The alkalis are divided into fixed alkalis and 
 volatile alkalis. This diftinCtion is eftablifhed 
 upon the fmell of thefe fubftances : the former 
 are not volatilized, even in the focus of the 
 burning mirror, and emit no charaCteriftic 
 fmell ; whereas the latter are eafily reduced in- 
 to vapour, and emit a very penetrating odour. 
 
 CHAP. I. 
 
 Concerning Fixed Alkalis . 
 
 N O more than two kinds of fixed alkalis 
 have hitherto been difcovered : the one 
 which is called Vegetable Alkali, or Pot-Afh; 
 the other Mineral Alkali, or Soda. 
 
 A RT|- 
 
Vegetable Fixed Alkali . 
 
 167 
 
 ARTICLE I. 
 
 Concerning the Vegetable Alkali, or Pot-Alh. 
 
 This alkali may be extracted from various 
 fubftances; and it is more or lefs pure, accord- 
 ingly as it is afforded by one fubflance or ano- 
 ther. Several varieties are made in commerce, 
 to which different names have been affixed, and 
 which are indifpenfably neceffary to be known. 
 The chemift may indeed confound all thefedif- 
 tinftions, in his writings, under one lingle de- 
 nomination : but the diffinftions eftablilhed by 
 the artifts are founded upon a feries of experi- 
 ments, which have proved that the virtues of 
 thefe feveral alkalis are very different ; and this 
 conftant variety in their effefts appears to me 
 to juffify the various denominations affigned 
 to them. 
 
 1. The alkali ext rafted from the lixivium of 
 wood-allies, is known by the name of Salin. 
 The falin calcined, and by this means difen- 
 gaged from all the blackening principles, forms 
 pot-alh. 
 
 The allies are more or lefs rich in alkali, ac- 
 cording to the nature of the wood which affords 
 them • in general, hard woods contain the mod. 
 The allies of beech afford from n to 131b. per 
 
 quintal. 
 
i68 
 
 Vegetable Fixed Alkali . 
 
 quintal, according to the experiments which 1 
 have made in the large way, at St. Sauveur ; 
 thofe of box afforded from 12 to 141b. The 
 tables drawn up by the feveral adminiflrators 
 of the gunpowder and faltpetre manufactories 
 may be confulted, refpeCting the quantity of 
 alkali afforded by the combuftion of feveral 
 plants: theyufed 40001b. of each in their va- 
 rious experiments. 
 
 To extract this alkali, nothing more is necef- 
 fary than to wafh the afhes, and to concentrate 
 the difiolution in boilers of caft iron. It is on 
 account of the alkali that wood afhes are em« 
 ployed in the lixiviums ufed by laundreffes or 
 bleachers. The ufe of alkali, in this cafe, is to 
 combine with the fat fubftances, and to render 
 them foluble in water. 
 
 Almoft all the pot-afh fold in commerce for 
 the ufe of our glafs-houfes, our foap-makers, 
 our bleaching-grounds, &c. is fabricated in the 
 north, where the abundance of wood admits of 
 its being applied to this (ingle purpofe. We 
 might eftablifh works of this kind to fufficient 
 advantage in the forefts of our kingdom. But 
 there is more to be done than is generally fup- 
 pofed, before the inhabitants of the mountains 
 can be turned towards this fpecies of induftry. 
 I have experienced this difficulty in the attempts 
 
 and 
 
Vegetable Fixed Alkali . 169 
 
 and very confiderable facrifices which I have 
 made to fecure this refource in the neighbour- 
 hood of Laigoual and Lefperou. The accurate 
 calculations which I have made, have neverthe- 
 lefs proved that the pot-afh would cod only 
 from 15 to 17 livres the quintal, whereas we 
 purchafe that from the north at 30 or 40 
 livres. 
 
 2. The lees of wine is almoft totally con- 
 verted into alkali by combuftion. This alkali 
 is called Cendres Gravelees : it' has almoft al- 
 ways a greenilh colour. This alkali is conft- 
 dered as very pure. 
 
 3. The combuftion of tartar of wine lijce- 
 wife affords an alkali of conftderable purity. 
 It is ufually burned wrapped up in paper, in 
 fmall packets, which are dipped in water, and 
 afterwards expofed upon burning coals. In 
 order to purify it, the refidue of the combuftion 
 is diffolved in water, the folution concentrated 
 by fire, the foreign falts feparated in proportion 
 as they precipitate; and a very pure alkali is 
 at laft obtained, which is known by the name 
 of Salt of Tartar. 
 
 To procure fait of tartar more fpeedily, as 
 well as more economically, I burn a mixture of 
 equal parts of nitrate of pot-afh, or common 
 
 nitre 
 
170 
 
 Mineral Fixed Alkali 
 
 nitre and tartar. The refidue, after lixiviation, 
 affords a beautiful fait of tartar. 
 
 Sait of tartar is the alkali moft commonly 
 employed in medical ules ; it is given in the 
 dofe of feveral grains. 
 
 4. If faltpetre be fufed upon charcoal, the 
 acid is decompofed and difhpated, while the 
 alkali remains alone and difengaged : this is 
 called Extemporaneous Alkali. 
 
 When the vegetable alkali has been brought 
 to the greateft ftate of purity, it attracts the hu- 
 midity of the air, and is refolved into a liquor. 
 In this ftate it is known by the very improper 
 name of Oil of Tartar per Deliquium. 
 
 ARTICLE II. 
 
 Concerning the Mineral Alkali, or Soda. 
 
 The Mineral Alkali has been fo called, be- 
 caufe it forms the balls of marine fait. 
 
 It is obtained from marine plants by com- 
 bultion: for this purpofe heaps of the faline 
 plants are formed ; and at the fide of thefe heaps 
 a round cavity is dug, which is enlarged towards 
 the bottom, and is three or four feet in depth : 
 this is the fire-place in which the vegetables are 
 burned. The combuftion is kept up without 
 
 interrupt 
 
Mineral "Fixed Alkali . 17 1 
 
 interruption for feveral days; and when all the 
 plants are confumed, a mafs of alkaline fait is 
 found remaining, which is cut into pieces, to 
 facilitate its carriage and fale. This is known 
 by the name of Rock Soda, or Soda. 
 
 All marine plants do not afford foda of the 
 fame quality. The barilla of Spain affords the 
 beautiful foda of Alicant. I am affured that we 
 might cultivate it upon our coafts in the Medi- 
 terranean, with the greateft fuccefs. This cul- 
 ture is highly interefting to the arts and com- 
 merce ; and government ought to encourage 
 this new fpecies of induftry. But an individual, 
 however inclined or devoted to the publicgood, 
 might make vain efforts to appropriate this com- 
 merce to our advantage, if he were not power- 
 fully affiffed by government ; becaufe the Spa- 
 nifh miniftry has prohibited the exportation of 
 the feed of barilla, under the ftrongeft penal- 
 ties. In Languedoc, and in Provence, we cul- 
 tivate on the banks of our ponds a plant known 
 by the name of Salicor, which affords foda of a 
 good quality ; but the plants which grow with- 
 out cultivation produce an inferior fort. I have 
 made an accurate analyfis of each fpecies, the 
 refults of which may be feen at the article 
 Yerrerie of the Ency elope die Metbcdique . 
 
 The mineral alkali is cleared of all hetero- 
 geneous 
 
172 Mineral Fixed Alkali* 
 
 geneous falts by diffolving it in water, and fe- 
 parating the feveral falts in proportion as they 
 fall down. The laft portion of the fluid being 
 concentrated affords thefoda, which cryftallizes 
 in rhomboidal o&ahedrons. 
 
 The mineral alkali is fometimes found in a 
 native flate: in Egypt it is known by the name 
 of Natron. The two lakes of Natron defcribed 
 by Sicard and Mr.Volney, are fltuated in the 
 defert of Chaiat, or St. Macaire, to the weft 
 of Delta. Their bed is a natural cavity of three 
 or four leagues in length, and a quarter of a 
 league in breadth ; the bottom is folid and ftony. 
 It is dry during nine months in the year; but 
 in winter a water of a violet-red colour oozes 
 out of the earth, w'hich fills the lake to five 
 or fix feet in depth : the return of the heat of 
 fummer evaporates this, and leaves a bed of 
 fait behind it of two feet in thicknefs, which 
 is dug out with bars of iron. The quantity 
 obtained annually amounts to 36,000 quin- 
 tals*. 
 
 Mr. Prouft found natron upon the fchifti 
 which form the foundation of the town of An- 
 gers; the fame chemift likewife found it upon 
 a ftone from the falpetriere of Paris. 
 
 The mineral alkali differs from the vege- 
 table, becaufe — 1. It is lefs cauftic. 2. It is fo 
 
 far 
 
Mineral Fixed Alkali . 
 
 *73 
 
 far from attracting humidity, that it effiorefces 
 in the air. 3. It cryftallizes in rhomboidal 
 octahedrons. 4. It forms different products 
 with the fame bafes. 3. It is more proper for 
 vitrification. 
 
 Do the alkalis exift ready formed in vegeta- 
 bles, or are they the product of the feveral 
 operations made ufe of in extracting them ? — • 
 This queftion has divided the opinions of che- 
 mifts. Du Hamel andGroffe proved, in 1732, 
 the exigence of alkali in cream of tartar, by 
 treating it with the fame nitric, fulphuric, and 
 other acids. Margraff has given additional 
 proofs of this, in a Memoir which forms the 
 twenty-fifth of his collection. Rouelle read a 
 Memoir to the Academy on the 14th of June, 
 1769, upon the fame fubjeCt: he even affirms 
 that he was acquainted with this truth before 
 the work of Margraff appeared. — See the Jour- 
 nal de Phyfique, vol. i. 
 
 Rouelle, and the marquis De Bullion, proved 
 that tartar exifts in muft. 
 
 It muft not be concluded from the exiftence 
 of an alkali in vegetables, that this fait is there 
 found in a difengaged ftate. On the contrary, 
 it is found combined with acids, oils, &:c. 
 
 The alkalis, fuch as we have defcribed them, 
 even after they have been difengaged from 
 
 every 
 
"i 74 Mineral Fixed Alkali . 
 
 every mixture, by folution, filtration, and eva- 
 poration, are not neverthelefs in that Rate of 
 purity and difengagement, which is necefiary to 
 be obtained in many cafes : they are nearly in 
 the Rate of neutral falts, by their combination 
 with the carbonic acid. When it is required to 
 difengage this acid, the alkali mull: be difiolved 
 in water, and quick-lime then flaked in the folu- 
 tion. This fubftance feizes the carbonic acid of 
 the alkali, and gives out its caloric in exchange. 
 We fhall fpeak of the circumflances of this 
 operation when we fhall have occafion to treat 
 of lime. The alkali being deprived of the car- 
 bonic acid, no longer effervefces with other 
 acids; it is more cauftic, and more violent in 
 its adlion; unites more eafily to oils; and is 
 then called Cauftic Alkali, Pure Pot-afh, or 
 Pure Soda. 
 
 When this alkali is evaporated, and brought 
 into the dry form, it is known by the name of 
 Lapis Caufticus. The corrofive virtue of this 
 fubftance depends principally upon the avidity 
 with which it feizes humidity, and falls into 
 deliquium. 
 
 The cauftic alkali, as it is ufually prepared, 
 always contains a fmall quantity of carbonic 
 acid, filiceous earth, iron, lime, &c. Mr. Ber- 
 thollet has propofed the following means of 
 
 purifying 
 
Mineral Fixed Alkali . 17 5 
 
 purifying it : — He concentrates the cauftic lix- 
 ivium until it has acquired a flight degree of 
 confidence ; at which period he mixes it with 
 alcohol, and draws off a portion by diftillation. 
 As foon as the retort is become cold, he finds 
 it to contain cryftals, mixed with a blackifh 
 earth, in a fmall quantity of liquor of a dark 
 colour, which is feparated from the folution of 
 alkali in the alcohol, which fwims above like an 
 oil. Thefe cryflals confift of the alkali fatu- 
 rated with the carbonic acid, and are infoluble 
 in fpirit of wine ; the depofition confifis of 
 filiceous earth, lime, iron, &;c. 
 
 The cauftic alkali in a ftate of great purity, 
 diffolved in the alcohol, fwims above the aque- 
 ous folution which contains the effervefcent 
 alkali. If the fpirituous folution of alkali be 
 concentrated on the fand-bath, tranfparent 
 cryftals are formed, which confift of the pure 
 alkali itfelf; thefe cryftals appear to be formed 
 by quadrangular pyramids inferted one in ano- 
 ther ; they are very deliquefcent, are foluble in 
 water and in alcohol, and produce cold by 
 their folution. — See the Journal de Phyfiquc, 
 1786, page 401. 
 
 The alkalis we have juft fpoken of, com- 
 bine eafily with fulphur. 
 
 This combination maybe effected — 1, By the 
 
 fufion 
 
i 7 6 
 
 Liver of Sulphur . 
 
 fufion of equal parts of alkali and fulphur. 
 2. By digefting the pure and liquid alkali upon 
 fulphur. — In thefe cafes the alkali becomes of 
 a reddifh-yellow colour. 
 
 The folutions of fulphur in alkali are known by 
 the name of Livers of Sulphur, Sulphures of Al- 
 kali, &c. They emit an oifenliYe fmeli, refem- 
 bling that of rotten eggs. This is occafioned 
 by the efcape of the (linking gas, called He- 
 patic Gas. 
 
 The fulphur may be precipitated by acids ; 
 and the refult of this precipitation is what the 
 ancient chemifls diftinguifhed by the name of 
 Milk of Sulphur, and Magiflery of Sulphur. 
 
 Thefe fulphures or hepars diffolve metals. 
 Gold itfelf may be fo divided by this means as 
 to pafs through filters. Stahl has fuppofed 
 that Mofes made ufe of this method to enable 
 the Ifraelites to drink the golden calf. 
 
 Though the analylis of the two alkalis has 
 not been made with flriQnefs, feveral experi- 
 ments lead us to believe that nitrogene is one of 
 their principles. Mr. Thouvenel, having ex- 
 pofed wafhed chalk to the exhalations of ani- 
 mal fubflances inputrefadlion, obtained nitrate 
 of pot-afh, or common nitre. I have repeated 
 this experiment in a clofed chamber of fix feet 
 fquare. Twenty-five pounds of chalk wafhed 
 in warm water, and expofed to the exhalation of 
 
 bullock’s 
 
Competition of Alkali. 177 
 
 bullock’s blood in putrefa&ion during eleven 
 months, afforded nine ounces of nitrate of lime, 
 in a dried ftate; and three ounces one gros of 
 cryflals of nitrate of pot-afh, or common nitre. 
 
 The repeated diftillation of foaps decom- 
 pofes them, and affords ammoniac. Now the 
 analyfis of this laft, by Mr. Berthollet, proves 
 the exigence of nitrogenous gas as one of its 
 conftituent parts. There is therefore room to 
 apprehend that nitrogene gas is one of the 
 principles of alkalis. 
 
 The experiments of Mr. Thouvenel, as well 
 as my own, lead me to believe that this gas > 
 when combined with lime, forms pot-afh, or 
 the vegetable alkali ; while its union with mag- 
 nefia forms foda. This laft opinion is fupport- 
 ed by the experiments — 1. Of Dehne, who ob- 
 tained magnefia from foda (fee Crell’s Chemi- 
 cal Annals, 1781, page 53). 2. Of Mr. Deyeux, 
 who obtained limilar refults even before Mr. 
 Dehne. 3. Of Mr. Lorgna, who obtained much 
 magnefia by diffolving, evaporating, and cal- 
 cining foda repeatedly (Journal de Phyfique, 
 1787). Mr. Ofburg confirmed thefe various 
 experiments in 1785. 
 
 Vox,. I. 
 
 .N 
 
 CHAP, 
 
Volatile Alkali 
 
 
 CHAP. II. 
 
 Concerning Ammoniac , Volatile Alkali . 
 
 O UR refearches have not hitherto exhibited 
 more than one fpecies of volatile alkali. 
 Its formation appears to be owing to putrefac- 
 tion; and though the diftillation of fome 
 fchifti affords it, yet this circumftance may be 
 attributed to their origin, which is pretty ge- 
 nerally afcribed to vegetable and animal de- 
 compofition. We find frequently enough, in 
 thefe fubftances, the print of fifhes, which is 
 in favour of this opinion. Some plants likewife 
 afford volatile alkali; for which reafon they 
 have been called Animal Plants. But the vo- 
 latile alkali is more efpecially afforded by ani- 
 mal fubflances : the diftillation of all their 
 parts affords it in conftderable abundance* 
 Horns are employed in preference, becaufe they 
 are refolved almoft entirely into oil and volatile 
 alkali. The putrefaction of all animal fub- 
 ftances produces volatile alkali ; and in this 
 cafe, as well as in diftillation, it is formed by the 
 combination of its two conftituent parts : for the 
 analylis very often fails in exhibiting any alkali 
 
 ready 
 
Volatile Alkali . 
 
 *79 
 
 ready formed, in fuch parts as diflillation or pu- 
 trefadlion would abundantly afford it from. 
 
 Almoft all the volatile alkali made ufe of in 
 commerce or medicine, is afforded by the de- 
 compofition of fal ammoniac. It is even on ac- 
 count of this circumflance that the chemiils 
 who have drawn up the New Nomenclature 
 have diflinguifhed the volatile alkali by the 
 name of Ammoniac. 
 
 To obtain ammoniac in a flate of confidera- 
 ble purity, equal parts of lifted quick-lime and 
 muriate of ammoniac, or common fal ammoni- 
 ac in powder, are mixed. This mixture is then 
 introduced into a retort, to which a receiver 
 and the apparatus of Woulfe have been adapted. 
 A quantity of pure w r ater is to be put into the 
 bottles, correfpondent to the weight of the fait 
 employed ; and the junctures of the veffels are 
 made good with the ufual lutes. The ammo- 
 niac is difengaged in the flate of gas, at the firfl 
 impreffion of the fire. It combines with the 
 water with heat ; and when the water of the firfl 
 bottle is faturated, the gas paffes to that of the 
 fecond, andfaturates it in its turn. 
 
 Volatile alkali is known by its very flrong 
 but not difagreeable fmell. It is eafily reduci- 
 ble into the flate of gas, and preferves this form 
 at the temperature of the atmofphere. This gas 
 N 2 may 
 
1 8 o Volatile Alkali • 
 
 may be obtained by decompofing the muriate 
 of ammoniac by quick-lime, and receiving the 
 product over mercury. 
 
 Alkaline gas kills animals, and corrodes the 
 fkin. The irritation is fuch, that I have feen 
 pimples arife all over the bodies of fome birds 
 expofed to its atmofphere. 
 
 This gas is improper for combuftion ; but if 
 a taper be gently immerfed in it, the flame is 
 enlarged before it goes out, and the gas fuffers 
 a dccompofltion. Alkaline gas is lighter than 
 atmofpheric air; and has even been mentioned, 
 on account of its lightnefs, as a proper fub- 
 fiance to fill balloons. The count De Milly 
 propofed to place a brazier, or veflel contain- 
 ing fire, under the balloon, to keep the gas in 
 its greatefl: ftate of expaniibility. 
 
 The experiments of Dr. Prieftley, who chang- 
 ed alkaline gas into hydrogene gas by means 
 of the eleflric fpark; thofe of the chevalier 
 Laudriani, who, by palling the fame gas through 
 ignited glafs tubes, obtained a large quantity 
 of hydrogenous gas — occafloned a fufpicion 
 of the exiflence of hydrogene among the prin- 
 ciples of alkaline gas. But the experiments 
 of Mr. Berthollet have removed all doubts on 
 this fubjedt; and all obfervations appear to 
 unite in authorifing us to conflder this alkali 
 
 as 
 
* Volatile Alkali . i$i 
 
 as a compound of the nitrogenous and hydro- 
 genous gafes. 
 
 1. If the oxigenated muriatic acid be mixed 
 with very pure ammoniac, an effervefcence 
 takes place, with a difengagement of nitroge- 
 nous gas, a produ&ion of water, and a conver- 
 lion of the oxigenated acid into the ordinary 
 muriatic acid. In this beautiful experiment, 
 the water which is produced is formed by the 
 combination of the hydrogene of the alkali and 
 the oxigene of the acid ; and the nitrogene gas 
 being fet at liberty, is diffipated. 
 
 2. When the nitrate of ammoniac is expofed 
 to diflillation, nitrogene gas is obtained, and a 
 greater quantity of water is found in the re- 
 ceiver than the fait itfelf contained. After the 
 operation, the ammoniac is found no longer to 
 exift. The water of the receiver is fiightly 
 charged with a fmall quantity of nitric acid, 
 which had paffed over. In this cafe, the hy- 
 dfogene of the alkali, and the oxigene of the 
 acid, form the water in the receiver, while the 
 nitrogenous gas efcapes. 
 
 If the oxides of copper or gold be heated 
 with ammoniacal gas, the product is water and 
 nitrogenous gas, and the metals are reduced. 
 
 I have obferved that the oxides of arfenic, 
 being digefted with ammoniac, are reduced, 
 
 and 
 
Volatile Alkali. 
 
 1S2 
 
 and often form o&ahedral cryflals of arfenic. 
 In this cafe there is a difengagement of nitro- 
 gene gas, and a formation of water. 
 
 It very often happens when metals, fuch as 
 copper or tin, are dilTolved by means of the 
 nitric acid, that anabforption of air takes place, 
 inflead of a difengagement of nitrous gas, as 
 might be expected : I have feen feveral perfons 
 very much embarraffed in fuch cafes, and I 
 have often been fo myfelf. This phenomenon 
 takes place more efpecially when a very con- 
 centrated acid is made ufe of, and the copper 
 is in fine filings: in this cafe ammoniac is pro- 
 duced. I have fhewn this fact to my auditors 
 long before I was acquainted with the theory 
 of its formation. That which led me to fufpedl 
 its exigence, was the blue colour which the 
 folution takes in this cafe. This ammoniac is 
 produced by the combination of the hydrogene 
 of the water with the nitrogene gas of the ni- 
 tric acid ; while the oxigene of the fame acid, 
 and that of the water, oxided the metal, and 
 prepared it for folution. It is to a fimilar eaufe 
 that we mult refer the experiment of Mr. John 
 Michael Hauffman of Colmar, who by palling 
 nitrous gas through a certain quantity of preci- 
 pitate of iron, in the mercurial apparatus, ob- 
 ferved that this gas was fpeedily abforbed, and 
 
 the 
 
Volatile Alkali . 
 
 183 
 
 the colour of the iron changed ; at the fame 
 time that valour of ammoniac was found in the 
 veflels. It is by a dmilar theory we may ac- 
 count for the formation of alkaline gas, by the 
 mixture of hepatic gas and nitrous gas over 
 mercury, as Mr. Kirwan obferves. 
 
 Mr. Auftin formed ammoniac ; but he ob- 
 ferved that the combination of nitrogenous gas 
 with the bafe of hydrogene does not take place, 
 unlefs this lad is in a date of great condenfa- 
 tion. 
 
 The formation of ammoniac by didillation 
 and putrefa&ion, appears to me likewife to in- 
 dicate its condiment parts. In fadl, there is in 
 both thefe operations a difengagement of hy- 
 drogene and nitrogene gas, and their combina- 
 tion produces ammoniac. 
 
 Mr. Berthollet has proved, by the way of de- 
 compofition, that one thoufand parts of ammo- 
 niac, by weight, are compofed of about eight 
 hundred and feven of nitrogene gas, and one 
 hundred and ninety-three of hydrogene gas. 
 — See the collection of the Royal Academy, 
 *7 8 4> P^e 316. 
 
 According to Dr. Audin, the nitrogene gas 
 is in proportion to the hydrogene, as one hun- 
 dred and twenty-one to thirty-two. 
 
 SEC 
 
184 General Properties of Acids . 
 
 SECTION IX; 
 
 Concerning the Combination of Oxigene 
 with certain Bafes forming Acids. 
 
 I T appears to be out of doubt, that the bodies 
 which we are agreed to call Acids, are com- 
 binations of vital air with a certain elementary 
 fubftance. The analyfis of almoft all the acids, 
 whofe component parts are known, eftablifties 
 this truth in a pofitive manner ; and it is on 
 account of this property that the denomination 
 of Oxigenous Gas has been given to vital air. 
 
 Every fubftance which poflefles the follow- 
 ing properties is called an Acid : 
 
 A. The word which is ufually employ- 
 ed to denote the impreftion or lively and ftiarp 
 fenfation produced on the tongue by certain 
 bodies, may be regarded as fynonymous to the 
 word acid . The only difference which may be 
 eftablifhed between them is, that the one de- 
 notes a weak fenfation, whereas the other com- 
 prehends all the degrees of force from the leaft 
 perceptible tafte to the greateft degree of cau- 
 fticity. We fay that verjuice, goofeberries, or 
 lemons, are Jour ; but we ufe the word acid to 
 exprefs the impreflion which the nitric, fulphu- 
 ric, or muriatic acids make upon the tongue. 
 
 The 
 
General Properties of Adds. 185 
 
 The caufticity of acids appears to arife from 
 their ftrong tendency to combination; and it 
 is from this property that the immortal New- 
 ton has defined them to be bodies which attradl 
 and are attra&ed. 
 
 It is alfo from this property that certain che- 
 mifts have fuppofed acids to be pointed bodies. 
 
 On account of this decided tendency to com- 
 bination which acids pollers, it feldom happens 
 that we find them in a difengaged Hate. 
 
 B. A fecond property of acids is that of 
 changing certain blue vegetable colours into 
 red, fuch as the colour of turnfole, fyrup of 
 violets, &c. Thefe two re-agents are common- 
 ly ufed to afcertain the prefence of acids. 
 
 The tindture of turnfole is prepared by light- 
 ly infilling in water that fubftance which is 
 known in common under the name of Turnfole 
 or Litmus. If the water be too lightly charged 
 with the colouring matter, the infufion has a 
 violet tinge, and muft in that cafe be diluted 
 with water until it becomes blue. The tinc- 
 ture of turnfole, when expofed to the fun, be- 
 comes red, even in clofed veflels ; and fome time 
 afterwards the colouring part is difengaged, and 
 falls down in the form of a mucilaginous difco- 
 loured fubftance. Alcohol may be ufed inftead 
 of w T ater in the preparation of this tindlure. 
 
 It 
 
1 86 General Properties of Acids. 
 
 It is generally fuppofed that the turnfole fa- 
 bricated in Holland is nothing more than the 
 colouring matter extracted from the rags or 
 cloths of turnfole of Grand-Galargues, and 
 precipitated upon a marly earth. Thefe rags 
 arc prepared by impregnating them with the 
 juice of nightfhade (morelle), and expofing 
 them to the vapour of urine, which develops 
 their blue colour. The rags are fent into Hol- 
 land, which has given rife to the opinion that 
 they are ufed in the fabrication of turnfole ; but 
 fubfequent enquiries have taught me that thefe 
 cloths are fent to the dealers in cheefe, who ex- 
 trad: a colour by infulion, and wafh their cheefes 
 with it, to give them a red colour. I am con- 
 vinced by the anaiyfis of turnfole, that the co- 
 louring matter is of the fame nature as that of 
 archil (orfeille) ; and that this principle is fix- 
 ed on a calcareous earth, and a fmall quantity 
 of pot-afh. In confequence of this anaiyfis, 
 I have endeavoured to caufe the liken parellus 
 of Auvergne to ferment with urine, lime, and 
 alkali ; and I obtained a pafle fimilar to that of 
 turnfole. The addition of alkali appears to me 
 to be neceffary to prevent the development of 
 the red colour, which, when combined with 
 the blue, forms the violet of the archil. 
 
 When any concentrated acid is to be tried 
 
 with 
 
General Properties of Acids. i8 y 
 
 with fyrup of violets, there are two particulars 
 to be attended to. i. The fyrup of violets is 
 often green, becaufe the petal of the violet con- 
 tains a yellow part at its bafe, which, when 
 combined with the blue, forms this green co- 
 lour : it is therefore effential to employ only 
 the blue of cne petal in order to have a beauti- 
 ful blue infufion. 2. Care muft be taken to 
 dilute the fyrup with a certain quantity of wa- 
 ter ; becaufe otherwife concentrated acids, fuch 
 as the fulphuric, would burn it, and form acoal. 
 
 The hmple infufion of violets may be ufed 
 inftead of the fyrup. 
 
 The colouring matter of indigo is not fen- 
 fible to the impreflion of acids. The fulphuric 
 acid diffolves it without altering the colour. 
 
 C. A third character of acids is, they effervefee 
 with alkalis; but this property is not general. 
 1. Becaufe the carbonic acid, and almoft all 
 weak acids, cannot be diftinguifhed by this pro- 
 perty. 2. Becaufe the pureft alkalis combine 
 with acids, without motion or effervefcence. 
 
 Is there not one fingle acid in nature, of 
 which the others may be only modifications ? 
 
 Paracelfus admitted an univerfal principle 
 of acidity, which communicated tafte and fo- 
 lubility to all its compounds. 
 
 Becher believed that this principle was com- 
 
 pofed 
 
1 88 General Properties of Acids. 
 
 pofed of water and verifiable earth. Stahl en- 
 deavoured to prove that rhe fulphuric acid was 
 the univerfal acid; and his opinion was adopted 
 by mod chemids for a long time. 
 
 Long after the time of Stahls Meyer main- 
 tained that the acid element was contained in 
 fire. This fydem, which is founded on cer- 
 tain known fadls, has had its fupporters. 
 
 The chevalier Landriani imagined he had 
 fucceeded in reducing all the acids to the car- 
 bonic acid ; becaufe, by treating them all with 
 different fubdances, he obtained this lad as the 
 condant refult of his analyfis. He was led into 
 an error, for want of having fufficiently attended 
 to the decompofitionof the acids he made ufe of, 
 and the combination of their oxigene with the 
 carbone of the bodies which entered into his ex- 
 periments, and produced the carbonic acid. 
 
 Ladly, the dried analyfis and fynthefis of mod . 
 of the known acids, have proved to Mr. La- 
 voifier that oxigene is the bafe of all of them ; 
 and that their differences and varieties arife 
 only from the fubdance with which this com- 
 mon principle is combined. 
 
 Oxigene united with metals forms oxides ; 
 and among thefe lad there arefome which pof- 
 fefs acid chara&ers, and are claffed amongd 
 acid fubdances. 
 
 Oxigene 
 
General Properties of Acids . 189 
 
 Oxigene combined with inflammable fub- 
 dances,fuchasfulphur,carbone, and oils, forms 
 other acids. 
 
 The adlion of acids upon bodies in general 
 cannot be underflood but by founding our ex- 
 planations upon the data which we have eda- 
 blifhedrefpedlingthe nature of their conflituent 
 
 parts. 
 
 The adhefion of oxigene to the bafe is more 
 
 or lefs flrong in the feveral acids, and confe- 
 
 quently their decompofi tion is more or lefs eafy ; 
 
 as, for example, in metallic folutions, which do 
 
 not take place excepting when the metal is in 
 
 the flate of an oxide. The acid which will yield 
 « * 
 
 Its oxigene with the greateft facility to oxide the 
 metal, will have the mod powerful adtion upon 
 it. Hence it happens, that the nitre and the 
 nitro-muriatic acids are thofe which diffolve 
 metals the mod readily; and hence likewife it 
 happens that the muriatic acid diflolves the 
 oxides more eafily than the metals, while the 
 nitric acid adls contrariwife : hence alfo itarifes 
 that this lada&s fo powerfully upon oils, &c. 
 
 It is impoflible to conceive and explain the 
 various phenomena prefented to us by acids in 
 their operations, if we have no idea of their 
 condituent principles. Stahl would not have 
 believed in the formation of fulphur, if he had 
 
 under- 
 
1 90 General Properties of Aeids, 
 
 underflood the decompofition of the fulphuric 
 acid upon charcoal; and if we except the com- 
 binations of acids with alkalis, and with cer- 
 tain earths, thefe fubflances are either totally or 
 partially decompofed in all the operations made 
 with them upon metals, vegetables, and ani- 
 mals, as we fhall find by obferving the pheno- 
 mena exhibited in thefe cafes refpedtively. 
 
 We fhall at prefent treat only of fomeof the 
 acids, and fhall direct our attention to the others 
 in proportion as we fhall have occafion to treat 
 of the various fubflances which afford them : we 
 fhall attend in preference to thofe which are the 
 befl known, and which have the greatefl influ- 
 ence in the operations of nature, as well as in 
 thofe of our laboratories. 
 
 CHAP. I. 
 
 Concerning the Carbonic Acid . 
 
 T HIS acid is almofl always obferved in the 
 flate of gas. We find that the ancients 
 were in fome meafure acquainted with it. Van 
 Helmont called it Gas Silveflre,thegasofmufl, 
 or of the vintage. Becher himfelf had a confi- 
 derably accurate notion of it, as appears by the 
 
 fol- 
 
Carbonic Acid , or Fixed Air . 19 1 
 
 following paffage : “ Diftinguitur autcm inter 
 fermentationem apertam et claufam ; in aperta 
 C£ potus fermentatus fanior elf, fed fortior in 
 < c claufa : caufa eft, quod evaporantia rarefadta 
 cf corpufcula, imprimis magna adhuc filveftri- 
 fc urn fpirituum copia, de quibus antea egimus, 
 “ retineatur, et in ipfum potum fe precipitet, 
 “ unde valde eum fortem reddit.” 
 
 Hoffmann attributed the virtue of molt mi- 
 neral waters to an elaftic fpirit contained in 
 them. 
 
 Mr. Venel, a celebrated profeffor in the 
 fchools at Montpellier, proved in 1750 that 
 the waters of Seltzer owed their virtue to a 
 fuperabundant portion of air. 
 
 In 1755, Dr. Black of Edinburgh advanced 
 that lime-ftone contains much air of a different 
 nature from common air. He affirmed that the 
 difengagement of this air converted it into lime, 
 and that by the reftoration of this air calcareous 
 ftone was regenerated. In the year 1746, Dr. 
 M'Bride fupported this dodtrine with new fadts. 
 Mr. Jacquin, profeffor of Vienna, refumed the 
 fame purfuit, multiplied experiments on the 
 manner of extradling this air, and added other 
 proofs in confirmation that the abfence of the 
 air rendered alkalis cauftic, and formed lime. 
 Dr. Prieftley exhibited all the perfpicuity and 
 
 pre- 
 
\<)2 General Properties and 
 
 precifion on this fubjeCl which might be ex- 
 pected from his abilities, and his fkill in making 
 experiments of this kind. This fubftance was 
 then known by the name of Fixed Air. In 
 1772, Bergmann proved that it is an acid, 
 which he called by the name of Aerial Acid. 
 Since the time of this celebrated chemift, it has 
 been diftinguifhed by the names of Mephitic 
 acid, Cretaceous acid, See.: and as foon as it 
 was proved to confift of a combination of oxu 
 gene and carbone, or pure charcoal, the name of 
 Carbonic acid was appropriated to it. 
 
 The carbonic acid is found in three differ- 
 ent ftates. 1. In that of gas. 2. In a Rate of 
 mixture. 3. In a ftate of combination. 
 
 It is found in the ftate of gas at the Grotto del 
 Cano, near Naples ; at the well of Perols, near 
 Montpellier; in that of Negrae in Vivarais ; 
 upon the furface of the'Lake~Averno in Italy, 
 and on thofe of feveral fprings ; in various fub- 
 terraneous places, fuch as tombs, cellars, necef- 
 faries, &c. It is difengaged in this form by the 
 decompofition of vegetables heaped together, 
 by the fermentation of wine or beer, by the pu- 
 trefaction of animal matters, &c. 
 
 It exifts in the ftate of ftmple mixture in 
 mineral waters, ftnee in thefe it pofiefTes all its 
 acid properties. 
 
 It 
 
Habitudes of Carbonic Acid . 193 
 
 It exifts in. a ftate of combination in lime- 
 ftone, common magnefla, alkalis, &c. 
 
 Various procefles are employed to colled: it, 
 according to the Hate in which it is found* 
 
 1. When the carbonic acid exifts in the ftate 
 of gas, it may be collected — 1 . By filling a bot- 
 tle with water, and emptying it into the atmo- 
 fphere of this gas ; the acid takes the place of 
 the water, and the bottle is afterwards corked 
 to retain it. 2. By expoling lime-water, cauftic 
 alkalis, or even pure water, in its atmofphere : 
 the gafeous acid mixes or combines with thefe 
 fubftances ; and may be afterwards extracted by 
 re-agents, which we fhall proceed to defcribe* 
 
 II. When the carbonic acid exifts in a ftate 
 of combination, it may be extra&ed— 1. By 
 diftillation with a ftrong heat. 2. By the re- 
 action of other acids, fuch as the fulphuric acid, 
 which has the advantage of not being volatile, 
 and confequently is not altered by its mixture 
 with the carbonic acid w hich is difengaged. 
 
 III. When the carbonic acid exifts in the ftate 
 of ftmple mixture, as in water, brifk wines, &c. 
 it may be obtained — 1. By agitation of the 
 liquid which contains it; as Mr. Venel prac- 
 tifed, by making ufe of a bottle to which he 
 adapted a moiftened bladder. 
 
 2. By diftillation of the fame fluid. — Thefe 
 two firft methods are not accurate. 
 
 Vol. I. O 
 
 3. The 
 
i$ 4 
 
 ' General Properties and 
 
 3. Theprocefs indicated by Mr. Gioanetti, 
 confifts’in precipitating the carbonic acid* by 
 means of lime-water, weighing the precipitate, 
 and deducting thirteen thirty-fecond parts for 
 the proportion of carbonic acid ; it having been 
 deduced from analyfis, by this celebrated phy- 
 fician, that thirty-two parts of carbonate of lime 
 contain feventeen lime, two water, and thir- 
 teen acid. 
 
 This fubflance is an acid, as is proved— 
 1. Becaufe tindfure of turnfole, agitated in a 
 bottle filled with this gas, becomes red. 2. Am- 
 moniac, or volatile alkali, poured into a velfel 
 filled with th6 gas, is neutralized. 3. Water 
 impregnated with this gas is ftrongly fub-acid. 
 4. It neutralizes alkali, and caufes them to 
 Cryftallize. 
 
 It remains at prefent to examine the proper- 
 ties of this acid gas. 
 
 A. It is unfit for refpiration. Hiftory in- 
 forms us that two flaves whom Tiberius caufed 
 to defcend into the Grotto del Cano, were im- 
 mediately ftifled ; and two criminals that Peter 
 de Toledo caufed to be fhut in there, fuffered 
 the fame fate. The abbe Nollet, who had the 
 courage to refpire the vapour, perceived a fuf- 
 focating fenfation, and a flight degree of acidity, 
 which produced coughing and fneezing. Pila- 
 
 tre 
 
Habitudes of Carbonic Acid . 195 
 
 ire de Roller, who prefents himfelf to our notice 
 on all occafions wherein danger was to be faced, 
 caufed himfelf to be fattened by cords fixed 
 under his arms, and defcended into the gafeous 
 atmofphere of a back of beer in fermentation. 
 He had fcarcely entered into the mephitis be- 
 fore flight prickings obliged him to ihut his 
 eyes; a violent fuffocation prevented him from 
 refpiring ; he felt a giddinefs, accompanied with 
 thofe noifes which characterize the apoplexy : 
 and when he was drawn up, his fight remained 
 dim for feveral minutes; the blood had filled 
 the jugulars;, his countenance had become 
 purple; and he neither heard nor fpoke but 
 with great difficulty : all thefe fymptoms how- 
 ever difappeared by degrees. 
 
 It is this gas which produces the many un- 
 happy accidents at the opening of cellars, in 
 places where wine, cyder, or beer are fuffered 
 to ferment. Birds plunged in the carbonic 
 acid gas, fuddenly perifh. The famous Lake 
 of Averno, where Virgil placed the entrance 
 of hell, exhales fo large a quantity of carbonic 
 acid, that birds cannot fly over it with impu- 
 nity. When the waters of Boulidou of Perols 
 are dry, fuch birds as attempt to quench their 
 thirft in the clefts, are enveloped in the mephi- 
 tic vapour, and die. 
 
 O 2 
 
 Frogs, 
 
ty6 General Properties and 
 
 Frogs, plunged in an atmofphere of carbo- 
 nic acid, live from forty to lixty minutes, by 
 fufpending their refpiration. 
 
 Infe&s are rendered torpid after a certain 
 time of remaining in this air; but they refume 
 their livelinefs the moment they are expofed to 
 the free air. 
 
 Bergmann pretended that this acid fuffocates 
 by extinguifhing irritability : he founds his opi- 
 nion upon the circumftance of his having taken 
 out the heart of an animal which had died in 
 the carbonic acid, before it was cold, and it 
 exhibited no fign of irritability. The cheva- 
 lier Landriani has proceeded ftill further ; for 
 he affirms that this gas extinguifhes irritability, 
 even wffien applied to the fkin ; and has averted 
 that, by tying a bladder full of this gas to the 
 neck of a fowl, in fuch a manner that the head 
 only of the animal was in the open air, and the 
 whole body enveloped in the bladder, the fowl 
 immediately perifhed. The abbe Fontana has 
 repeated and varied this experiment on feveral 
 animals, none of which died. 
 
 The count Morrozzo publifhed experi- 
 ments made in the prefence of Dr. Cigna ; 
 the refults of which appear to invalidate the 
 confequeoces of the celebrated Bergmann: 
 but it is to be obferved, that the chemift of 
 
 Turin 
 
Habitudes of Carbonic Acid . 197 
 
 Turin caufed his animals to die only in air 
 vitiated by the death of another animal ; and 
 that in this circumftance the nitrogene gas pre- 
 dominates. — See the Journal dePhyfique, tom. 
 xxv. p. 1 12. 
 
 B. The carbonic acid is improper for vege- 
 tation. Dr. Prieftley having kept the roots of 
 feveral plants in water impregnated with the 
 carbonic acid, obferved that they all perilhed; 
 and in tliofe inftances where plants are obferved 
 to vegetate in water or in air which contains 
 this gas, the quantity of gas is very fmall. 
 
 Mr. Senebier has even obferved, that plants 
 which are fuffered to grow in water (lightly aci- 
 dulated with this gas, emit a much larger quan- 
 tity of oxigenous gas ; becaufe, iji this cafe, the 
 acid is decompofed, the carbonaceous principle 
 combines and is fixed in the vegetable, while 
 the oxigene is thrown off. 
 
 I have obferved that thofe fungi which are 
 formed in fubterraneous places, are almoft to- 
 tally refolved into carbonic acid ; but if thefe 
 vegetables be gradually expofed to the adtion 
 of light, the proportion of acid diminifhes ; 
 while that of the coaly principle augments, and 
 the vegetable becomes coloured. I have pur- 
 fued thefe experiments with the grea^ft care in 
 a coal mine. 
 
 C. The 
 
1 9 S . General Properties and 
 
 C. The carbonic acid is cafily difTolved in 
 water. Water impregnated with this acid pof- 
 feffes very valuable medicinal qualities; and fe- 
 veral apparatus have been fuccelTively invent- 
 ed to facilitate this mixture. The apparatus 
 of Nooth, improved by Parker and Magellan, 
 is one of the mod ingenious. On this fubjed: 
 the' Encyclopedic Methodique may be confult- 
 ed, article Acide Mephitique. 
 
 The natural acidulous mineral waters do not 
 differ from thefe, excepting in confequence of 
 their holding other principles in folution ; and 
 they may be perfectly imitated when their ana- 
 lysis is well known. It is abfurd to think that 
 art is incapable of imitating nature in the com- 
 pofition of mineral w aters. It muft be admitted 
 that the proceffes of nature are abfolutely un- 
 known to us, in all the operations which relate 
 to life ; and we cannot flatter ourfelves with the 
 hope of imitating her in tfrefe circumdances. 
 But when the quedion relates to an operation 
 purely mechanical, or confiding of the folution 
 of certain known principles in w^ater, we can 
 and ought to perform it even frill better, as we 
 have the power of varying the dofes, and pro- 
 portioning the efficacy of any artificial mineral 
 water to the purpofes to which it is intended 
 to be applied. 
 
 D. The 
 
Habitudes of Carbonic Acid, 
 
 199 
 
 D. The carbonic acid gas is heavier than 
 common air. The proportion between thefe 
 two airs in weight, according to Mr. Kirwan, 
 is 45,69 to 68,74. The proportion, according 
 to the experiments of Mr. Lavoifier, is 48,81 
 to 69,50. 
 
 This confiderabie weight caufes it to occupy 
 the lowed: dtuations; and even gives it the 
 property of being poured out from one veffel 
 to another, fo as to difplace the atmofpheric 
 air. This truly curious phenomenon was ob- 
 ferved by Mr. De Sauvages, as may be feen in 
 his Differtation upon Air, which was crowned 
 in Marfeilles in 1750. 
 
 It appears to be proved, by fufhcient experi- 
 ments, that the carbonic acid is a combination 
 of carbone, or pure charcoal, and oxigene. 
 1. The oxides of mercury, when diddled, are 
 reducible without addition, and afford only ox- 
 igenous gas ; but if a fmall quantity of char- 
 coal be mixed with the oxide, the produd which 
 comes over conlifts of carbonic gas only, an4 
 the weight of the charcoal is diminiflied. 
 
 2. If well-made charcoal be ignited, and 
 plunged into a veffel filled with oxigenous gas, 
 and the veffel be inftantly clofed, the char- 
 coal burns rapidly, and at lad: goes out : the 
 produd in this experiment is carbonic acid, 
 
 which 
 
zoo Properties of Carbonic Acid . 
 
 which may be feparated by the known pro- 
 cefles ; the remainder is a fmall quantity of oxi- 
 genous gas, which may be converted into car- 
 bonic acid by the fame treatment. 
 
 In thefe experiments I fee nothing but char- 
 coal and oxigenous gas : and the confequence 
 deduced is fimple and natural. 
 
 The proportion of charcoal is to that of oxi- 
 geneas 12,028$* to 56,687. 
 
 When the carbonic acid, in fome cafes, is 
 obtained by burninghydrogenous gas, it arifes 
 from carbone held in folution in this gas. The 
 carbone may even be diffolved in hydrogenous 
 gas, by expofing it to the focus of tl\e burning 
 mirror in the mercurial apparatus, under a glafs 
 veffel filled with this gas. 
 
 The hydrogenous gas which is extracted from 
 a mixture of fulphuric acid and iron, holds 
 more or lefs of charcoal in folution ; becaufe 
 iron itfelf contains this fubftance in a greater 
 or lefs quantity, as is afcertained by the fine 
 experiments of MefTrs. Berthollet, Monge, 
 and Vander Monde. 
 
 The alkalis, fuch as we ufually meet with 
 them, contain carbonic acid; and it is this acid 
 which modifies them, and diminifhes their 
 energy, at the fame time that it communicates 
 to them the property of effervefcing. We may 
 
 therefore 
 
201 
 
 Carlonate of Pot-Ajh . 
 
 therefore confider alkalis as carbonates with 
 excefs of alkali; and it is eafy to faturate this 
 fuperabundant alkali, and to form true cryftal- 
 lizablc neutral fairs. 
 
 ARTICLE I. 
 
 Carbonate of Pot-afh. 
 
 The carbonate of pot.afh was formerly dif- 
 tinguifhed by the name of Cretaceous Tartar. 
 The method of caufing oil of tartar to cryftal- 
 lize, has long been known. Bonhius and Mon- 
 tet have fuccefTively fhewn thefe proceffes : but 
 the limpleft conlifts in expofing an alkaline 
 folution in an atmofphere of the acid gas which 
 is difengaged in the vinous fermentation ; the 
 alkali becomes faturated, and forms tetrahedral 
 prifmatic cryftals terminated by very fhort 
 four-fided pyramids. 
 
 I have feveral times obtained thofe cryftals 
 jm the form of quadrangular prifms, with their 
 extremities cut off flantwife. 
 
 This neutral fait no longer polfeffes the uri- 
 nous tafte of the alkali, but exhibits the pene- 
 trating tafte of neutral falts, and may be em- 
 ployed in medicine with the greateft fuccefs. 
 I have been d witnefs to its being taken in the 
 dofe of one dram (gros) without the leaft in- 
 convenience. 
 
 This 
 
202 Carbonate of Soda* 
 
 This fait poifefTes an. ad vantage beyond the 
 fait of tartar, in being lefs cauftic, and always 
 of the fame virtue. 
 
 It contains, according to the analyfis of 
 Bergmann, twenty parts acid, forty-eight al- 
 kali, and thirty-two water, in the quintal. 
 
 It does not attract the humidity of the air. I 
 have preferved fome of it for feveral years in a 
 capfule, without any appearance of alteration. 
 
 The carbonate of pot-afh is decompofed by 
 lilex in a fufftcient heat, which occafions a con- 
 fiderable boiling or ebullition. The refidue is 
 glafs, in which the alkali is in the cauftic ftate. 
 Lime decompofes the carbonate, by uniting to 
 the acid; and acids produce the fame effect, 
 by combining with the alkaline bafes. 
 
 ARTICLE II. 
 
 Carbonate of Soda. 
 
 The denominations of Aerated Mineral ali 
 kali, Cretaceous Soda, &c. have been fuccef- 
 fively given to this kind of carbonate. 
 
 The mineral alkali, in its natural ftate, con- 
 tains a greater quantity of carbonic acid than 
 the vegetable ; and nothing more is. neceffary 
 than to diflolve it, and duly evaporate the wa- 
 ter, in order to obtain it in cryftals. 
 
 Thefe 
 
203 
 
 Carbonate of Ammoniac, 
 
 Thefe cryftals are ufually rhomboidal odta- 
 hedrons ; and fometimes have the form of 
 rhomboidal laminae, applied obliquely one 
 upon the other, fo that they refemble tiles. 
 
 This carbonate efflorefces in the air. 
 
 One hundred parts contain fixteen parts acid, 
 twenty alkali, and fixty-four water. 
 
 The affinity of its balls with filex is ftronger 
 than that of the carbonate of pot-afh ; in con- 
 fequence of which, the vitrification it produces 
 is more quick and eafy. 
 
 Lime and the acids decompofe it, with the 
 fame phenomena which we have obferved at the 
 article Carbonate of Pot-afh. 
 
 ARTICLE III. 
 
 Carbonate of Ammoniac. 
 
 This fait has been generally known by the 
 name of Concrete Volatile Alkali. It has like- 
 wife been diftinguifhed by that of Cretaceous 
 Volatile Alkali, &c. 
 
 It may be obtained by diftillation from many 
 animal fubflances. Tobacco affords, likewife, 
 a large proportion; but almoft the whole of 
 that which is employed in the arts, and in me- 
 dicine, is formed by the direft combination of 
 the carbonic acid and ammoniac, or volatile al~ 
 
 kali. 
 
204 Carbonate of Ammoniac. 
 
 kali. This combination may be effected — 1. By 
 pafling the carbonic acid through ammoniac, 
 or the pure volatile alkali in folution. 2. By 
 expofing ammoniac in an atmofphere of car- 
 bonic acid gas. 3. By decompofing the mu- 
 riate of ammoniac by the neutral falts which 
 contain this acid, fuch as the carbonate of lime 
 or common chalk. For this purpofe, white 
 chalk is taken, and very accurately dried ; and 
 then mixed with equal parts of muriate of am- 
 moniac, or common fal ammoniac in fine pow- 
 der. This mixture is put into a retort, and 
 diftilled; the ammoniac and the carbonic acid 
 being difengaged from their bafes, and reduced 
 into vapours, combine together, and are depo- 
 fited on the fides of the receiver, where they 
 form a ftratum more or lefs thick. 
 
 The cryftallization of this carbonate ap- 
 peared to me to be that of a four-fided prifm, 
 terminated by a dihedral fummit. 
 
 The carbonate has lefs fmell than the ammo- 
 niac ; it is very foluble in water. Cold water 
 dirtolves its own weight of this fait, at the tem- 
 perature pf fixty degrees of Fahrenheit. 
 
 One hundred grains of this fait contain forty- 
 five parts acid, forty-three alkali, and twelve 
 water, according to Bergmann. 
 
 Mod acids decompofe it, and difplace the 
 carbonic acid. 
 
 C H A P. 
 
Production of the Sulphuric Acid. 20$ 
 
 CHAP. II. 
 
 Concerning the Sulphuric Acid. 
 
 S ULPHUR, like every other combuffible 
 fubffance, cannot be burnt but by virtue 
 of the oxigenous gas which combines with it. 
 
 The moft ufual phenomena which accom- 
 pany this combuffion, are, a blue flame, a 
 whitiffi and fuffocating vapour, and a ftrong, 
 penetrating, and difagreeable fmell. 
 
 The refults of this combination vary accord- 
 ing to the proportion in which thefe two prin- 
 ciples enter into this fame combination. 
 
 The fulphureous or the fulphuric acid may 
 be atpleafure obtained from fublimed fulphur, 
 or from crude fulphur, accordingly as a greater 
 or lefs quantity of oxigene is combined with the 
 fulphur, by means of combuffion. 
 
 When the current of air which maintains the 
 combuffion is rapid, the fulphur is carried, and 
 depofited without any apparent alteration, into 
 the internal part of the leaden chambers in 
 which the oil of vitriol is made. If the current 
 of air be rendered more moderate, the combi- 
 nation is fomewhat more accurate ; the fulphur 
 
 is 
 
jo6 Production of the Sulphuric Acid 
 
 is partly changed, and is depofited in a pellicle 
 upon the furface of the water. This pellicle is 
 flexible like a fkin, and may be handled and 
 turned over in the fame manner. If the current 
 be ftill lefs rapid, and the air be fuffered to have 
 a fufficient time to form an accurate combina- 
 tion with the fulphur, the refult is fulphureous 
 acid ; which acid preferves its gafeous form at 
 the temperature of the atmofphere, and may 
 become liquid like water by the application of 
 cold, according to the line experiments of Mr. 
 Monge. If the combuftion be ftill flower, and 
 the air be fuffered to digeft upon the fulphur a 
 longer time, and with greater accuracy, the re- 
 fult is fulphuric acid : this laft combination 
 may be facilitated by the mixture of faltpetre, 
 becaufe this fubftance furnifhes oxigene very 
 abundantly. 
 
 Numerous experiments which I have made 
 in my manufactory, to economize the faltpetre 
 employed in the fabrication of oil of vitriol, 
 have feveral times exhibited the refults here 
 mentioned. 
 
 All the proceffes which are capable of being 
 adapted for extracting the fulphuric acid, are 
 reducible to — i . The extraction of it from fub- 
 ftances which contain it. 2 . Its direCt forma- 
 tion by combination of fulphur and oxigene. 
 
 In 
 
207 
 
 by Combujlion 
 
 In the firft cafe, the fulphures, or vitriolic 
 falts of iron, copper, or zinc, and even thofe 
 whofe bafes are clay and lime, according to 
 Netimann and Margraff, may be expofed to dis- 
 tillation. Butthefe expenfive procelfes are not 
 very eafy to be carried into execution ; and ac- 
 cordingly they have been abandoned, to make 
 room for others of greater fimplicity. 
 
 In the fecond cafe, the oxigene may be pre- 
 fented to the fulphur in two forms: either ill 
 the (late of gas, or in the concrete ftate. 
 
 i. The combuftion of fulphur by oxigenous 
 gas, is performed in large chambers lined with 
 lead. The combuftion is facilitated by mixing 
 about one-erghth of a nitrate of pot-afh with 
 the fulphur. The acid vapours which fill the 
 chamber are precipitated againft its fides, and 
 the condenfation is facilitated by a ftratum of 
 water difpofed on the bottom of the chamber. 
 In fbme manufactories in Holland, this com- 
 buftion is performed in large glafs balloons with 
 large mouths, and the vapours are precipitated 
 upon water placed at the bottom. 
 
 In both cafes, when the water is fufhciently 
 impregnated with acid, it is concentrated in 
 leaden boilers, and rectified in glafs retorts, to 
 render it white, and to concentrate it fufhciently 
 for the purpofes of trade. The acid, when of a 
 
 due 
 
20 8 Production of the Sulphuric Acid i &c, 
 
 due flrength, indicates fixty-fix degrees, accord- 
 ing to'the aerometer of Mr. Baume; and when 
 it has not been carried to this degree, it is unfit 
 for moft of the ufes for which it is intended. It 
 cannot, for example, be employed in diffolving 
 indigo ; for the fmall quantity of nitric acid 
 which it contains, unites with the blue of the 
 indigo, and forms a green colour. I have as- 
 certained this phenomenon by very accurate 
 experiments ; and I have been a witnefs to the 
 failing of colours, and the lofs of fluffs, in con- 
 fequence of the imperfection of the acid. 
 
 2. When the oxigene in the concrete flate is 
 prefented to the fulphur, it is then in combina- 
 tion with other bodies, which it abandons to 
 unite with this la ft. This happens when the 
 nitric acid is diflilled from fulphur. Forty- 
 eight ounces of this acid, at thirty-fix degrees, 
 diflilled from two ounces of fulphur, afforded 
 near four ounces of good fulphuric acid. This 
 faCl was known to Matte Lafaveur: but I 
 pointed out all the phenomena and circum- 
 ftances of the operation in 1781. 
 
 Sulphur may likewife be converted into ful- 
 phuric acid by means of the oxigenated muria- 
 tic acid. — Encyclopedic Methodique, tom. i. 
 P- 370. 
 
 The fulphuric acid which is found difengaged 
 
 in 
 
Native Sulphuric Acid. 209 
 
 in fame places in Italy, appear likewife to arife 
 from the combuftion of fulphur.. Baldaffiari has 
 obferved it in this ftate in a hollow grotto, in 
 the midft of a mafs of incruft^tions depolited 
 by the baths of Saint Philip, in Tufcany. He 
 afferts that the fulphureous vapour continually 
 arifes in this grotto. He likewife found ful- 
 phureous and vitriolic effervefcences at Saint 
 Albino, near mount Pulciano; and at the lakes 
 of Travale, where he obferved the branches of a 
 tree covered with concretions of fulphur and 
 the oil of vitriol. — Journal de Phylique, t. vii. 
 
 P- 395- : 
 
 O. Vandelli relates that, in the environs of 
 Sienna and Viterbo, fulphuric acid is fome- 
 times found dilTolved in water. Mr. (the com- 
 mander) De Dolomieu affirms that he found it 
 pure and cryftallized inagrotto of mount Etna, 
 from which fulphur was formerly obtained. 
 
 According to a firft experiment of Mr. Ber- 
 thoil'et, fixty-nine parts of fulphur w ith thirty- 
 one parts of oxigene formed one hundred parts 
 of fulphuric acid ; and, according to a fecond 
 experiment, feventy-tvvoof fulphur and twenty- 
 eight of oxigene formed one hundred parts of 
 dry acid. 
 
 The various degrees of concentration of the 
 fulphuric acid have caufed it to be diftinguifh- 
 
 Vol. I. P ed 
 
' 2 io Congelation of Sulphuric Acid . 
 
 ed by different names, under which it is known 
 in commerce. Hence the denominations of 
 Spirit of Vitriol, Oil of Vitriol, and Glacial 
 Oil of Vitriol, to exprefs its degrees of con- 
 centration. 
 
 The fulphuric acid is capable of pafling to 
 the concrete ftate by the imprelfion of intenfe 
 cold. This congelation is a phenomenon long 
 lince known. Kunckel and Bohn have fpoken 
 of it: and Boerhaave fays exprefsly, “ Oleum 
 vitrioli, fumma arte puriffimum, fummo fri- 
 gore hiberno in glebas folidefcit perfpicuas : 
 fed, ffatim ac acuties frigoris retunditur, li- 
 quefcit et diffluit. 5 ’ — We are indebted to the 
 Duke D’Ayen for fome very valuable experi- 
 ments. upon the congelation of this acid ; and 
 Mr.DeMorveau repeated them with equal fuc- 
 cefs in 1782, and proved that this congelation 
 may be affedted at a degree of cold confldera- 
 bly ’lefs than what had been mentioned*. 
 
 I have already feveral times obtained beau- 
 tiful cryilals of fulphuric acid in flattened hex- 
 ahedral prifms, terminated by an hexahedral 
 pyramid; and my experiments have enabled 
 me to conclude — 1. That the very concen- 
 
 * See alfo the experiments of Mr. Keir, and the late 
 experiments of Mr. Cavendifli, on the congelation of acids, 
 in the Philofophical Tranfaftions, 
 
 trated 
 
Character's of Sulphuric A cid. 2 1 1 
 
 trated acid cry ftallizes more difficultly than that 
 whofe denfity lies between lixty-three and fixty- 
 five. 2. That the proper degree of cold is 
 from 1 to 3 degrees below o of Reaumur. The 
 detail of my experiments may be feen in the 
 volume of the Academy of Sciences of Paris 
 for the year 1784. 
 
 The characters of the fulphuric acid are the 
 following. 
 
 1 . It is undtuous and fat to the touch, which 
 has occafioned it to obtain the very improper 
 name of Oil of Vitriol. 
 
 2. It weighs one ounce and feven gros in a 
 bottle containing one ounce of diftilled water. 
 
 3. It produces heat, when mixed with water, 
 to fuch a degree as to exceed that of boiling wa- 
 ter. If one end of a tube of glafs be clofed, 
 and water poured into it, and the clofed end 
 of this tube be plunged into water, the water 
 in the tube may be made to boil by pouring 
 fulphuric acid into the external water which 
 furrounds the tube. 
 
 4. It feizes with great avidity ail inflamma- 
 ble fubftances; and it is blackened and decom- 
 pofed by this combination, 
 
 Stahl fuppofed the fulphuric acid to be the 
 univerfal acid. He founded this opinion more 
 efpeeially upon the circumftance, that cloths 
 
 P 2 foaked 
 
212 Sulphate of Pot-aJIj . 
 
 foakcd in a folution of alkali, and expofed to 
 the air, attra&ed an acid which combined with 
 the alkali ; and formed a neutral fait, by him 
 fuppofed to be of the nature of fulphate of pot- 
 afh, or vitriolated tartar. Subfequent and more 
 accurate experiments have fhewn that this 
 aerial acid was the carbonic; and the prefent 
 Rate of our knowledge is fuch as permits us 
 flill lefs than ever to believe in the exiftence 
 of an univerfal acid. 
 
 ARTICLE I. 
 
 Sulphate of Pot-afh. 
 
 \ 
 
 The fulphate of pot-afh is defcribed indif- 
 ferently under the names of Arcanum Dupli- 
 catum, Sal de Duobus, Vitriolated Tartar, Vi- 
 triol of Pot-afh, &c. 
 
 This fait cryftallizes in hexahedral prifms > 
 terminating in hexahedral pyramids, with tri- 
 angular faces. 
 
 It has a lively and penetrating tafte, and 
 melts difficultly in the mouth. 
 
 It decrepitates on hot coals, becomes red- 
 hot before it fufes, and is volatilized without 
 decompofition. 
 
 It is foluble in fixteen parts of cold water, at 
 the temperature of 60 deg. of Fahrenheit ; and 
 boiling water diflolves one-fifth of its weight. 
 
 100 grains 
 
213 
 
 Sulphate of Soda . 
 
 ioo grains contain 30.21 acid, 64.61 alkali, 
 and 5.18 water. 
 
 Moft of the fulphate of pot-afh ufed in me- 
 dicine is formed by the diredt combination of 
 the fulphuric acid and pot-afh, or the vegeta- 
 ble alkali ; but that which is met with in com- 
 merce is produced in the diflillation of aqua 
 fortis, by the fulphuric acid : this has the form 
 of beautiful cryflals, and is fold in the Comtat 
 Venaifin at forty or fifty livres the quintal. 
 The analyfis of tobacco has likewife afforded 
 me this fulphate. 
 
 Mr. Baume proved to the Academy, in 1760, 
 that the nitric acid, affifted by heat, is capable 
 of decompofing the fulphate of pot-afh. Mr. 
 Cornette afterwards fhewed that the muriatic 
 acid pofTeffes the fame virtue; and I fhewed, 
 in 1780, that this acid may be difplaced by 
 the nitric acid, without the afli fiance of heat; 
 though the fulphuric acid refumes its place 
 when the folution is concentrated by heat. 
 
 ARTICLE II. 
 
 Sulphate of Soda. 
 
 This combination of the fulphuric acid and 
 foda is flill known under the names of Glauber’s 
 
 Salt, 
 
214 Sulphate of Soda . 
 
 Salt, Sal Admirabile,Vitriol of Soda, &c. This 
 fait cryfiallizes in rectangular oCtahedrons, of 
 a prifrtiatic or cuneiform figure, of which the 
 two pyramids are truncated near their bails. 
 
 It has a very bitter tafte, and eafily diiTolves 
 in the mouth. 
 
 It fwells up upon heated coals, and boils, in 
 confequence of the diifipation of its water of 
 cryftallization. After this water has been dif- 
 perfed, there remains only a white powder, dif- 
 ficult of fufion, which is volatilized without 
 decompofition by a itrong heat. 
 
 By expofure to the air, it effervefces, lofes its 
 tranfparency, and is reduced to a fine powder. 
 
 Three parts of water, at 60 deg. of Fahren- 
 heit’s thermometer, diiTolved one part of this 
 fait ; but boiling water difiblves its own weight. 
 
 100 grains of fulphate of foda contain 14 
 acid, 22 alkali, and 64 water. 
 
 It is formed by the direct combination of the 
 two principles which contain it ; but the tamarix 
 gallica, which grows on the fea-coafts, contains 
 fo large a quantity, that it may be extracted to 
 advantage. Nothing more is n'ecefiary for this 
 purpofe, than to burn the plant, and lixiviate 
 the afhes. That fait which is fold in the fouth 
 of France, in fine cryflals, is prepared in this 
 manner. It is very pure, and the price does 
 
 not 
 
Sulphate of Animoniac. 2 1 £ 
 
 not exceed thirty or thirty-five livres the quin- 
 tal. This fulphate is likewife formed in our la- 
 boratories when we decompofe the muriate of 
 loda, or common fait, by fulphuric acid. 
 
 Pot-afh difiolved by heat in a folution of 
 fulphate of foda, precipitates the foda, and 
 takes its place. See my Chemical Memoirs. 
 
 1. . 1*. Jl ; . • ' . . . j* l : # i > v - * „ . . . 
 
 ARTICLE III. 
 
 Sulphate of Ammoniac. 
 
 The fulphate of ammoniac, commonly known 
 by the name of Glauber’s Secret Ammoniacal 
 Salt, is very bitter. 
 
 It cryftallizes in long flattened prifms with 
 fix fldes, terminated by flx-flded pyramids. 
 
 It cannot be obtained in well-formed cryftals 
 but by infenflble evaporation. 
 
 It (lightly attracts the humidity of the air. 
 
 It liquefies by a gentle heat, and rifes over a 
 moderate fire. 
 
 Two parts of cold water diflolve one of this 
 fait ; and boiling water its own weight, accord- 
 ing to Fourcroy. The fixed alkalis barytes, 
 and lime, difengage the ammoniac from it. 
 
 The nitric and muriatic acids difengage the 
 fulphuric acid. 
 
 The 
 
2 1 6 Sulphate of Ammoniac > 
 
 The different fubffancts of which we have 
 treated are of coniiderable ufe in the arts and 
 medicine. 
 
 The fiilphureous acid is employed in whiten- 
 ing ff Ik, and giving it a degree of luftre. Stahl 
 had even combined it with alkali, and formed 
 the fait fo welt known under the name of Stahl’s 
 Sulphureous Salt. This combination paffes 
 quickly to the ftate of fulphate, if it be left ex- 
 pofed to the air ; as it fpeedily abforbs the ox- 
 igene which is wanting for that purpofe. 
 
 The principal ufe of the fulphuric acid is in 
 dyeing, in which art it ferves to diffolve indigo, 
 and carry it in a ffate of extreme divifion upon 
 the fluffs to be dyed; it is likewife ufed by 
 the manufacturers of Indiens, or iilk and fluff 
 mixtures, to carry off the preparation of thefe 
 goods, wherein lime is ufed. The chemiff: 
 makes great ufe of this acid in his analyfes ; 
 and to feparate other acids from their combi- 
 nation, fuch as the carbonic, the nitric, and 
 the muriatic acids. 
 
 The fulphate of pot-afh is known in medicine 
 as an alterative, and is ufed in cafes of ladteous 
 coagulations. It is given in the dofe of a few 
 grains^ and is even purgative in a greater dofe. 
 
 The fulphate of foda is an effectual purga- 
 tive in the dofe of from four to eight gros, or 
 
 drams. 
 
Acid of Nitre , or Nitric Acid. 217 
 
 drams. For this purpofe it is diflolved in a 
 pint of water. 
 
 
 CHAP. III. 
 
 Concerning the Nitric Acid. 
 
 T HE nitric acid, called Aqua Fortis in 
 commerce, is lighter than the fulphuric. 
 It ufually has a yellow colour, a ftrong'and 
 difagreeable fmell, and emits red vapours. It 
 gives a yellow colour to the Ikin, to filk, and 
 to almoft all animal fubftances with which it 
 may come in contadh It dilTolves and fpeed- 
 ily corrodes iron, copper, zinc, &c. with the 
 efcape of a cloud of red vapours during the 
 whole time its adlion lafts. It entirely deftroys 
 the colour of violets, which it reddens. It 
 unites to water with facility; and the mixture 
 affumes a green colour, which difappears when 
 ftill further diluted. 
 
 This acid has been no where found in a dif- 
 engaged ftate. It always exifts in a ,f:ate of 
 combination; and it is from thefe combinations 
 that the art of chemiftry extra&s it, to apply it 
 to our ufes. The nitrate of pot-afh, or com- 
 mon nitre, is the combination which is belt 
 
 known. 
 
2 1 8 Acid of Nitre , or Nitric Acid . 
 
 known, and is likewife that from which we 
 ufually extrad the nitric acid. 
 
 The procefs ufed in commerce to make aqua 
 fortis, confifts in mixing one part of faltpetre 
 with two or three parts of red bolar earth. 
 This mixture is put into coated retorts, dif- 
 pofed in a gallery or long furnace, to each of 
 which is adapted a receiver. The firft vapour 
 which arifes in the diftillation is nothing but 
 water, which is fuffered to efcape at the place 
 of jundture, before the luting: and when, the 
 red vapours begin to appear, the phlegm which 
 is condenfed in the receiver is poured out; and 
 the receiver, being replaced, is carefully luted 
 to the neck of the retort. The vapours which 
 are condenfed, form at firft a greenifh liquor: 
 this colour difappearsinfenfibly, and.is replaced 
 by another which is more or lefs yellow. Some 
 chemifts, more efpecially Mr. Baume, were of 
 opinion that the earth adted upon the faltpetre 
 by virtue of the fulphuric acid it contains. But 
 not to mention that this principle does not 
 exift in all the earths made ufe of, as Meflrs. 
 Macquer, De Morveau, , and Scheele have 
 proved, we know that pulverized flints equally 
 produce the decompofition of faltpetre. I am 
 therefore of opinion that the effedt of thefe 
 earths upon the fait ought to be referred to the 
 
 very 
 
219 
 
 Acid of Nitre, or Nitric Acid . 
 
 very evident affinity of the alkali to the filex, 
 which is a principal component part ; and 
 more efpecially to the flight degree of adhefion 
 which exifts between the conftituent princi- 
 ples of nitrate of pot-afh. 
 
 We decompofe faltpetre in our laboratories 
 by means of the fulphuric acid. Very pure ni- 
 trate of pot-afh is taken, and introduced into a 
 tubulated retort, placed in a fand bath, with a 
 receiver adapted. All the places of jun&ion 
 are carefully luted j and as much fulphuric acid 
 as amounts to half the weight of the fait is pour- 
 ed through the tubulure; and the diftillation is 
 proceeded upon* Care is taken to fit a tube 
 into the tubulure of the receiver ; the other end 
 of which is plunged into water, to condenfethe 
 vapours, and to remove all fear of anexplofion. 
 
 Inftead of employing the fulphuric acid, we 
 may fubftitute the fulphate of iron, and mix it 
 with faltpetre in equal parts. In this cafe the 
 refidue of the diftillation, when well wafhed, 
 forms the mild earth of vitriol made ufe of to 
 polifh glafs. 
 
 Stahl and Kunckel have fpokcn of a very 
 penetrating aqua fortis, of a blue colour, ob- 
 tained by the diftillation of nitre with arfenic. 
 
 Whatever precaution is taken in th purifi- 
 cation of the faltpetre, and however great the 
 
 attention 
 
220 
 
 Acid of Nitre . 
 
 attention may be which is bellowed upon its dif- 
 tillation, the nitric acid is always impregnated 
 with fome foreign acid, either the fulphuric or 
 muriatic, from which it requires to be purified. 
 It is cleared of the firft by re-diftilling it up- 
 on very pure faltpetre, which retains the fmall 
 quantity of fulphuric acid that may exift in the 
 mixture.. It is deprived of the fecond by pour- 
 ing into it a few drops of a folution of nitrate 
 of filver. The muriatic acid combines with the 
 filver, and is precipitated with it in the form of 
 an infoluble fait. The fluid is then fullered to 
 remain at reft, and is afterwards decanted from 
 the precipitate or depofition. This acid, fo 
 purified, is known under the name of Aqua 
 Fortis for Parting, Precipitated Nitrous Acid, 
 Pure Nitric Acid, &c. 
 
 Stahl had confidered the nitric acid as a mo- 
 dification of the fulphuric, produced by its 
 combination with an inflammable principle. 
 This opinion has been fupported by feveral new' 
 fadts, in a diflertation of Mr. Pietfh, crowned 
 by the Academy of Berlin in 1749. 
 
 The experiments of the celebrated Hales led 
 him ftill nearer to this conclufion, as his ma- 
 nipulations w r ere fucceflively employed upon 
 the two conftituent principles of the nitric 
 acid. This celebrated philofopher had obtained 
 
 ninety 
 
221 
 
 Properties of Nitrous Acid . 
 
 ninety cubic inches of air from half a cubic inch 
 of nitre ; and he proceeded no further in his 
 conclufions, than to aflert that this air is the 
 principal caufe of the explofions of nitre. 
 
 The fame philofopher relates that the pyrites 
 of Walton, treated with equal quantities of fpi- 
 rit of nitre and water, produce an air which has 
 the property of abforbing the frefh air, which 
 may be made to enter the veffel. This great 
 man, therefore, extradled fuccehively the two 
 principles of the nitric acid ; and thefe capital 
 experiments put Dr. Prieftley in the road to 
 the difcoveries he has fince made. 
 
 It was not however until the year 1776 that 
 the analylis of the nitric acid was w ell known. 
 Mr. Lavoifier, by diftilling this acid from 
 mercury, and receiving the feveral products in 
 
 the pneumato-chemical apparatus, has proved • 
 
 that the nitric acid. 
 
 whofe fpecific 
 
 gravity is 
 
 to that of diffilled water as 
 contains — 
 
 131607 to IOOOOO, 
 
 Nitrous gas 
 
 02. 
 
 g “OS. 
 
 grains. 
 
 1 
 
 7 
 
 5 1 ? 
 
 Oxigenous gas 
 
 1 
 
 7 
 
 7 a 
 
 Water 
 
 *3 
 
 — 
 
 — ' 
 
 By combining thefe three principles toge- 
 ther the decompofed acid was regenerated. 
 The adlion of the nitric acid on moft inflam- 
 mable 
 
222 Properties and Component Paris 
 
 triable matters, confifts in nothing more than 
 a continual decompofition of this acid. 
 
 If the nitric acid be poured upon iron, cop- 
 per, or zinc, thefe metals are inftantly attack- 
 ed with a ftrong effervefcence ; and a confider- 
 able difengagement of vapours takes place, 
 which become of a red colour by their combi- 
 nation with the atmofpheric air, but which may 
 be retained and collected in the ftate of gas in 
 the hydro-pneumatic apparatus. In all thefe 
 cafes the metals are ftrongly oxided. 
 
 The nitric acid, when mixed with oils, ren- 
 ders them thick and black, converts them into 
 charcoal, or inflames them, accordingly as the 
 acid is more or lefs concentrated, or in a great- 
 er or lefs quantity. 
 
 If very concentrated nitric acid be put into 
 an apothecary’s phial, and be poured upon 
 charcoal in an impalpable powder, and very 
 dry, it fets it on fire inftantly, at the fame 
 time that carbonic acid and nitrogene gas are 
 difengaged. 
 
 The various acids which are obtained by 
 the digeftion of the nitric acid on certain fub- 
 llances, fuch as the oxalic acid, or acid of fugar, 
 the arfenical acid. &c. owe their exiftence 
 merely to the decompofition of the nitric acid, 
 the oxigene of which is fix'ed in combination 
 
 with 
 
of Nil roils Acid. 223 
 
 with the bodies upon which this acid is de- 
 compofed, renders it one of the moft aCtive ; 
 becaufe the aCtion of acids upon moft bodies 
 is a confequence of their own proper decom- 
 pofition. 
 
 The characters of nitrous gas, which is ex- 
 tracted by the decompolition of the acid, are — 
 1. It is invifible, or perfectly tranfparent. 2. 
 Its fpecific gravity is rather lefs than that of 
 ^tmofpherical air. 3. It is unfit for refpiration, 
 though, the abbe Fontana pretends that he re- 
 fpired it without danger. 4. It does not main- 
 tain combuftion. 5. It is not acid, according 
 to the experiments of the Duke de Chaulnes. 
 6. It combines with oxigene, and reproduces 
 the nitric acid. 
 
 But what is the nature of this nitrous gas ? 
 It was at firft pretended that it confifts of the 
 nitric acid faturated with phlogifton. This 
 fyftem ought to have been abandoned as foon 
 as it was proved that the nitric acid depo- 
 fited its oxigene upon the bodies on which it 
 aCted ; and that the nitrous gas was ‘lefs in 
 weight than the acid made ufe of. A capital 
 experiment of Mr. Cavendifh has thrown the 
 greateft light on the fubjeCt. This chemift 
 having introduced into a tube of glafs feven 
 
 parts 
 
224 Properties and Component Parts 
 
 parts of oxigenous gas obtained without nitrous 
 acid, and three parts of nitrogene gas ; or, by 
 eftimating thefe quantities in weight, ten parts 
 of nitrogene to tw^enty-lixof oxigene — and hav- 
 ing caufed the eledtric fpark to pafs through 
 this mixture, perceived that its volume or bulk 
 was greatly diminifhed, and fuccceded in con- 
 verting it into nitric acid. It may be prefumed, 
 from his experiment, that the acid is a combi- 
 nation of feyen parts of oxigene, and three of 
 nitrogene. Thefe proportions conftitute the 
 ordinary nitric acid ; but when a portion of 
 its oxigene is taken away, it paffes to the (late 
 of nitrous gas ; fo that nitrous gas is a combi- 
 nation of nitrogene gas, with a fmall quantity 
 of oxigene. 
 
 Nitrous gas may bedecompofed byexpofing 
 it to a folution of the fulphure of pot-afh, or 
 hepar of fulphur : the oxigene gas unites to 
 the fulphur, and forms fulphuric acid ; while 
 the nitrogene gas remains behind in a ftate of 
 purity. 
 
 Nitrous gas may like wife be decompofed by 
 means of pyrophorus, which burns in this air, 
 and abforbs the oxigenous gas. 
 
 The ele&ric fpark has likewife the property 
 of decompofing nitrous gas. Mr. Van Marum 
 has obferved that three cubic inches of the ni- 
 
 trous 
 
of Nitrous Acid. 22$ 
 
 trous gas are reduced by electricity to one cu- 
 bic inch and three quarters ; and that this refi- 
 due no longer polfeffed any property of nitrous 
 gas. Laftly, according to the experiments of 
 Mr. Lavoifier, one hundred grains of nitrous gas 
 contain thirty-two parts nitrogene, and fixty- 
 eight parts oxigene : according to the fame 
 chemift, one hundred grains of nitric acid con- 
 tain feventy-nine and a half oxigene and twenty 
 and a half nitrogene ; and this is the reafon why 
 nitrous gas fhould be employed in a lefs portion 
 than nitrogene gas, to combine with the oxigene 
 gas, and form the nitric acid. 
 
 Thefe ideas upon the compofition of the ni- 
 trous acid, appear to be confirmed by the re- 
 peated proofs we now have of the neceflity of 
 caufing fubftances, which afford much nitro- 
 gene gas, to be prefented to the oxigene gas, in 
 order to obtain nitric acid. 
 
 The feveral flates of the nitric acid may be 
 clearly explained according to this theory : — 
 1. The fuming nitrous acid is that in which the 
 oxigene does not exift in a fufficient propor- 
 tion ; and we may render the whiteft and the 
 moft faturated nitric acid fuming and ruddy* 
 by depriving it of a part of its oxigene by 
 means of metals, oils, inflammable fubftances* 
 See . or even by difengaging the oxigene by 
 Vol. I. the 
 
226 Properties and Component Parts . 
 
 the fimple expofition of the acid to the light of 
 the fan, according to the valuable experiments 
 of Mr. Berthollet. 
 
 The property which nitrous gas poflelTes, of 
 abforbing oxigene to form the nitric acid, has 
 caufed it to be employed to determine the pro- 
 portion of oxigene in the compofition which 
 forms our atmofphere. The abbe Fontana has 
 conftrudted, on thefe principles, an ingenious 
 eudiometer, the defcription and manner of uling 
 which may be feen in the firft volume of Dr. 
 Ingenhoufz’s Experiments upon Vegetables. 
 
 Mr. Berthollet has veryjuftly obferved, that 
 this eudiometer is inaccurate, or productive of 
 deception — i. Becaufe it is difficult to obtain 
 nitrous gas constantly formed of the fame pro- 
 portions of nitrogene gas and oxigene ; for 
 they vary, not only according to the nature of 
 the fubftancesupon which the nitric acid is de- 
 compofed, but likewife accordingly as the fo- 
 lution of any given fubftance by the acid is 
 made with greater or lefs rapidity. If the acid 
 be decompofed upon a volatile oil, nothing but 
 nitrogene gas can be obtained ; if the acid adt 
 upon iron, and it be much concentrated, nitro- 
 gene gas only will be obtained, as I have ob- 
 ferved, &c. 2. The nitric acid which is formed 
 by the union of nitrous gas and oxigene, dif- 
 
 folves 
 
027 
 
 of AJihfaus Acid . 
 
 iolves a greater or lefs quantity of nitrous gas 
 according to the temperature, the quality of 
 the air which is tried, the iize of the eudiome- 
 ter, &c. fo that the diminution varies in pro- 
 portion to the greater or lefs quantity of nitrous 
 gas obtained by the nitric acid which is formed : 
 confequently the diminution ought to be great- 
 er in winter than in fummer, &c* 
 
 According to the experiments of Mr. La- 
 voifier, four parts of oxigenous gas are fuffici- 
 ent to faturate feven parts and one-third of ni- 
 trous gas ; whereas it is found that nearly fix- 
 teen parts of atmofpheric air are required to 
 produce the fame effect : whence this cele- 
 brated chemiflhas concluded, that the air of the 
 atmofphere does not in general contain more 
 than one-fourth of oxigenous or refpirable gas. 
 Repeated experiments at Montpellier, upon 
 the fame principle, have convinced me that 
 twelve or thirteen parts of atmofpheric air are 
 conftantly fufficient to faturate feven parts and 
 one-third of nitrous gas. 
 
 Thefe experiments fhew, to a certain degree 
 of accuracy, the proportion in which vital air 
 exifts in the air which we refpire ; but they do 
 not give us any information refpedting the nox- 
 ious gafes which, when mixed with the atmo^ 
 fpheric air, alter it, and render it unwholfome* 
 Q 2 This 
 
2 28 Nitrate of Pof-a/l, or Nitre . 
 
 This obfervation very much curtails the ufc 
 of this inftrument. 
 
 The combination of the oxigenous and ni- 
 trous gafes always leaves an aeriform relidue, 
 which Mr. Lavoifier eftimated at about one 
 thirty-fourth of the whole volume : it arifes 
 from the mixture of the foreign gafeous fub- 
 ftances, which more or lefs affedt the purity 
 of the gafes made ufe of. 
 
 ARTICLE I. 
 
 Nitrate of Pot-afh. 
 
 The nitric add, combined with pot-afh, 
 forms the fait fo well known under the names 
 of Nitre, Saltpetre, Nitre of Pot-afh, &c. 
 
 This neutral fait is rarely the produdt of any 
 diredl combination of its two conflituent parts. 
 It is found ready formed in certain places ; 
 and in this manner it is that the whole of the 
 nitre employed in the arts is obtained. 
 
 In the Indies, it efflorefees on the furface of 
 uncultivated grounds. The inhabitants lixi- 
 viate thefe earths with water, which they after- 
 wards boil and cryftallize in earthen pots. Mr. 
 Dombey has obferved a great quantity of falt- 
 petre near Lima, upon earths which ferve for 
 
 pafture. 
 
Production of Nitre . 229 
 
 pafture, and which produce only gramineous 
 plants. Mr. Talbot Dillon, in his travels into 
 Spain, relates that one-third of all the grounds, 
 and in the fouthern parts of that kingdom even 
 the dull of the roads, contain faltpetre. 
 
 Saltpetre is extracted in France from the 
 ruins and plafter of old houfes. 
 
 This fait exifts ready formed in vegetables, 
 fuch as parietaria and buglofs, &c. And one 
 of my pupils, Mr. Virenque, has proved that 
 it is produced in all extracts which are capable 
 of fermenting. 
 
 The fermentation of faltpetre may be fa- 
 voured, by cauling certain circumftances to 
 concur which are of advantage to its formation. 
 
 In the north of Europe, the faltpetre-beds are 
 formed with lime, afhes, earth of uncultivated 
 grounds, and ftraw, which are Gratified, and 
 watered with urine, dunghill-water, and mo- 
 ther waters. Thefe beds are defended by a 
 covering of heath or broom. In the year 1775, 
 the King caufed a prize to be propofed by the 
 Royal Academy of Sciences at Paris, to difcover 
 a method of increafing the produd: of faltpetre 
 in France, and to relieve the people from the 
 obligation of permitting the faltpetre makers 
 to examine their cellars, in order to difcover 
 and carry away faltpetre earths. Several Me- 
 moir 
 
 1 
 
230 Production of Nitre. 
 
 moirs were offered on the fubjedt, which the; 
 Academy united into a fingle volume ; and 
 thefe have added to our knowledge, by inftrueft- 
 ing us more efpecially concerning the nature 
 of the matters which favour the formation of 
 nitre. It was known, for example, longfince, 
 that nitre is formed in preference near habita- 
 tions, or in earths, impregnated wdth animal 
 products : it was likewife known that, in gene- 
 ral, the alkaline bails was afforded by the con- 
 currence of a vegetable fermentation. Mr. 
 Thouvenel, whofe Memoir was crowned, has 
 proved that the gas which is difengaged by pu- 
 trefaction, is neceffary for the formation of 
 nitre ; that blood, and, next to it, urine, were 
 the animal parts which were the moft favoura- 
 ble to its formation ; that the moff minutely 
 divided and the lighted: earths were the moft 
 proper for nitrification ; that the current of air 
 muft be properly managed, to fix upon thefe 
 earths the nitric acid which is formed, &c. 
 
 It feems to me that Becher poffeffed a con- 
 fiderably accurate knowledge of the formation 
 of nitre, as appears from the followingpaffages : 
 
 " Haec enim ('vermes, mufeae, ferpentes) pu- 
 <K trefaefta in terram abeunt prorfus nitrofam ; 
 * f ex qua etiam communi modo nitrum copio- 
 %< fum parari poteft, fola elixatione cum aqua 
 c< communi. ,, — Phyf, Subt, lib, i, S. V. t. i. 
 
 p. ?86» 
 
 (< Sed 
 
Production of Nitre . 231 
 
 " Sed et ipfum nitrum necdum finis ultimus 
 < f putrefaCtionis eft ; narn cum ejufdem partes 
 <c igneae feparantur, reliquae in terram abeunt 
 fC prorfum puram et infipidam, fed ftngulari 
 u magnetifmo praeditam novum fpiritum aere- 
 Cf um attrahendi, rurfufque nitrum fiendi. ,, — 
 Phyf. Subt. S. V. t. i. p. 292, 
 
 From all the difcoveries and obfervations 
 which have been hitherto made, it follows that, 
 in order to eftablifh artificial nitre beds, it is 
 neceffary that animal putrefaction and vegeta- 
 ble fermentation fhould concur. The nitro- 
 gene gas, in its difengagement from the animal 
 fubftances, combines with the oxigene, and 
 forms the acid, which again unites with the 
 alkali, whofe formation is favoured by the ve- 
 getable decompofition. 
 
 When the manufacturer is in pofteflion of 
 falt-petre grounds, whether by the fimple ope- 
 rations of nature or by the affiftance of art, the 
 faltpetre is extracted by the lixiviation of thefe 
 earths ; which lixivium is afterwards concen- 
 trated, and made to cryftallize. In proportion 
 as the evaporation goes forward, the marine 
 fait, which almoft always accompanies the for- 
 mation of nitre, is precipitated. This is taken 
 out with ladles, and fet to drain in bafkets 
 placed over the boilers. 
 
 As 
 
-3 2 Production of Nitre • 
 
 As a great part of the nitre has an /earthy 
 bafis, and requires to be furniflied with an al- 
 kaline bails to caufe it to cryftallize, this pur- 
 pofe is accomplifhed either by mixing allies 
 with the faltpetre earths, or by adding an alkali 
 ready formed to the lixivium itfelf. 
 
 Nitre obtained by this firft operation is ne- 
 ver pure, but contains fea-falt, and an extract- 
 ive and colouring principle, from which it mud 
 be cleared. For this purpofe it is diffolved in 
 frefh water, which is evaporated ; and to which 
 bullocks blood may be added, to clarify the 
 folution. The nitre obtained by the fecond 
 manipulation is known by the name of Nitre of 
 the Second Boiling* If recourfe be had to a 
 third operation to purify it, it is then called 
 Nitre of the Third Boiling* 
 
 The purified nitrate of pot-afh is employed 
 in delicate operations, fuch as the manufacture 
 of gunpowder, the preparation of aqua fortis 
 for parting, and the folution of mercury, &c. 
 The faltpetre of the firft boiling is ufed in thofe 
 works where aqua fortis is made for the dyers. 
 It affords a nitro-muriatic acid, which is ca- 
 paple of diffolving tin by itfelf. 
 
 The nitrate of pot-afh cryftallizes in prif- 
 matic octahedrons, which almoft always repre- 
 fent fix-fided flattened priftps, terminated by 
 dihedral fummits* 
 
 It 
 
Production of Nil re . 233 
 
 It has a penetrating tafte, followed by a fen- 
 fation of coldnefs. 
 
 It is fufible upon ignited coals ; and in this 
 cafe its acid is decompofed. The oxigene 
 unites with the carbone, and forms the carbo- 
 nic acid ,* the nitrogene gas and the water are 
 diflipated ; and it is this mixture of principles 
 which has been known under the name of 
 Clyhus of Nitre. 
 
 The diftillation of the nitrate of pot-afh af- 
 fords twelve thoufand cubic inches of oxigen- 
 ous gas for each pound of the fait. 
 
 Seven parts of water diffolve one of nitre, at 
 lixty degrees of Fahrenheit ; and boiling water 
 diflolves its own weight of this fait. 
 
 One hundred grains of the cryftals of nitre 
 contain thirty acid, fixty-three alkali, and 
 feven water. 
 
 When a mixture of equal parts of nitre and 
 fulphur is thrown into a red-hot crucible, a 
 faline fubftance is obtained, which was for- 
 merly called Sal Polychreft of Glafer, and 
 which has lince been confidered as Sulphate of 
 Pot-afh. If nitre be fufed, and a few pinches 
 of fulphur be thrown upon this fait in fufion, 
 and the whole be afterwards poured out or caft 
 into plates, it forms a fait known by the name 
 of Crystal Mineral. 
 
 A mixture 
 
*34 
 
 Gunpowder, 
 
 A mixture of feventy-five parts of nitre, 
 nine and a half of fulphur, and fifteen and a 
 half of charcoal, forms gunpowder. This mix- 
 ture is triturated from ten to fifteen hours, care 
 being taken to moiften it from time to time. 
 This trituration is ufually performed bypound- 
 ing mills, whofe peftles and mortars are of 
 wood. In order to give the powder the form 
 proper to granulate it, it is paiTed through 
 lieves of fkin, whofe perforations are of various 
 fizes. Thegrained powder is then lifted, to fepa- 
 rate the duft, and it is afterwards carried to the 
 drying-houfe. Gunpowder for artillery, or 
 cannon-powder, receives no other preparation ; 
 but it is neceffary to glaze the powder which is 
 intended for fowling. This laft preparation is 
 effected by putting it into a kind of cafk which 
 turns on an axis, and by whofe movement the 
 angles of the grains are broken, and their fur- 
 faces polifhed. We are indebted to Mr. Baume 
 and the chevalier Darcy for a feries of experi- 
 ments, in which they have proved — 
 
 1. That good gunpowder cannot be made 
 without fulphur. 
 
 2. That charcoal is likewife indifpenfably 
 neceffary. 
 
 3. That the quality of gunpowder depends, 
 ceteris paribus, upon the accuracy with which 
 the mixture is made. 
 
 4. That 
 
Fulminating Powder • 235 
 
 4. That the effedt of powder is greater when 
 limply dried than when it is granulated. 
 
 The effedl of gunpowder depends upon the 
 rapid decompofition which is made in an in- 
 ftant of a confiderable mafs of nitre, and the 
 fudden formation of thofe gafes which are 
 the immediate produdl. Bernoulli, in the la^t 
 century, afcertained the development of air by 
 the deflagration of gunpowder : he placed four 
 grains of powder in a recurved tube of glafs, 
 plunged the tube in w 7 ater, and fet fire to the 
 gunpowder by means of theburning-glafs ; after 
 the combuftion the interior air occupied a larg- 
 er fpace, fo that the fpace abandoned by the 
 water was fuch as would have contained two 
 hundredgrains of gunpowder. — Hift.de 1’ Aca- 
 demiedesScieneesde Paris, 1696, t.ii. Memoire 
 de M. Varignon fur le Feu et la Flamme. 
 
 The fulminating powder, which is made by 
 the mixture and trituration of three parts of nU 
 tre, two of fait of tartar, and one of fulphur, 
 produces effedls ftill more terrible. In order to 
 obtain the full effedf, it is expofed in a ladle to 
 a gentle heat; the mixture melts, a fulphureous 
 blue flame appears, and the explofion takes 
 place. Care muft be taken to give neither too 
 ftrong nor too flight a degree of heat. In either 
 cafe, the combuftion of the principles takes 
 place feparately, and without explofion. 
 
 A RTF, 
 
236 Nitrate of Soda and Ammoniac, 
 
 ARTICLE IL 
 Nitrate of Soda. 
 
 This fait has received the name of Cubic 
 Nitre, on account of its form; but this deno- 
 mination is not exadt, becaufe it affedtsa figure 
 conflantly rhomboidal. 
 
 It has a cool, bitter tafte. 
 
 It (lightly attradls the humidity of the air. 
 
 Cold water, at fixty degrees of Fahrenheit’s 
 thermometer, difTolves one-third of its weight; 
 and hot water fcarcely difTolves more. 
 
 It fufes upon burning coals with a yellow co- 
 lour; whereas common nitre affords a white 
 flame, according to Margraff — 24 Differt. fur 
 le Sel Commun, t. ii. p. 343. 
 
 100 grains of this fait contain 28.80 acid, 
 50.09 alkali, and 21.11 water. 
 
 It is almoft always the product of art. 
 
 ARTICLE III. 
 
 Nitrate of Ammoniac. 
 
 The vapours of ammoniac, or volatile alkali, 
 being brought into contadi with thofe of the 
 
 nitrous 
 
'The Muriatic Acid • 
 
 237 
 
 nitrous acid, combine with them, and form a 
 white and thick cloud, which (lowly fublides. 
 
 But when the acid is dire&ly united to the 
 alkali, the refult is a fait, which has a cool, bit- 
 ter, and urinous tafte. 
 
 Mr. De Lifle pretends that it cryflallizes in 
 beautiful needles, limilar to thofe of fulphate 
 of pot-alh. 
 
 Thefe cryftals cannot be obtained but by a 
 very flow evaporation. 
 
 When this fait is expofed to the fire, it 
 liquefies, emits aqueous vapours, dries, and 
 detonates. 
 
 Mr. Berthollet hasanalyfed all therefultsof 
 this operation, and has drawn from them a new 
 proof of the truth of the principles which he 
 has eftablilhed with regard to ammoniac. 
 
 CHAP. IV. 
 
 Concerning the Muriatic Acid . 
 
 5 *Tp HIS acid is generally known by the 
 name of Marine Acid, and it is ftill dif- 
 tinguifhed among artifans by the name of Spirit 
 of Salt. 
 
 It is lighter than the two preceding acids ; it 
 
 has 
 
238 Diji illation of Muriatic Acid . 
 
 has a ftrong penetrating fmell, refembling that 
 of faffron, but infinitely more pungent ; it 
 emits white vapours when it is concentrated ; 
 it precipitates filver from its folution in the 
 form of an infoluble fait, &c. This acid has 
 no where been found difengaged ; and, to ob- 
 tain it in this ftate, it is necelfary to difengage it 
 from its combinations. Common fait is ufually 
 employed for this purpofe. 
 
 The fpirit of fait of commerce is obtained by 
 a procefs little differing from that which is ufed 
 in the extraction of aqua fortis. But as this 
 acid adheres more ftrongly to its balls, the pro- 
 duct is very weak, and only part of the marine 
 fait is decompofed. 
 
 Flints pulverized, and mixed with this fait, 
 do not feparate the acid. Ten pounds of flints 
 in powder, treated by a violent fire with two 
 pounds of the fait, did not afford me any other 
 product than a mafs of the colour of litharge. 
 The fumes were not perceptibly acid. If clay, 
 which has once ferved to decompofe marine 
 fait, be mixed with a new quantity of the fame 
 fait, it will not decompofe an atom of it, even 
 though the mixture be moiflencd and formed 
 into a pafle, Thefe experiments have been 
 feveral times repeated in my manufactory, and 
 have conftantly exhibited the fame refults. 
 
 The 
 
Dift illation of Muriatic Acid . 239 
 
 The fulphate of iron, or martial vitriol, which 
 fo eafily difengages the nitric acid, decompofes 
 marine fait; but very imperfe&ly. 
 
 The impure foda known in France by the 
 name of Blanquette, and in which my analyfis 
 Fas exhibited twenty-one pounds of common 
 fait out of twenty-five, fcarcely affords any mu- 
 riatic acid when it is diftilled with the fulphuric 
 acid ; but it affords abundance of fulphureous 
 acid. Mr. Berard, director of my manufac- 
 tory, attributed thefe refults to the coal con- 
 tained in this foda, which decompofed the ful- 
 phuric acid. He therefore calcined the blan- 
 quette to deftroy the charcoal; and then he 
 found he could treat it in the fame manner as 
 common fait, and with the fame fuccefs. 
 
 The fulphuric acid is ufually employed to 
 decompofe marine fait. My method of pro- 
 ceeding confiffs in drying the marine fait, 
 pounding it, and putting* it into a tubulated 
 retort placed upon a fand bath. A receiver is 
 adapted to the retort, and afterwards two bot- 
 tles, after the manner of Woulfe, in w'hich I 
 diftribute a weight of diffilled water equal to 
 that of the marine fait made ufe of. The join- 
 ings of the veffels are then luted, but with the 
 greateff caution ; and when the apparatus is 
 thus fitted up, a quantity of fulphuric acid is 
 
 poured 
 
240 t) filiation of Muriatic Acid . 
 
 poured through the tubulure equal to half the 
 weight of the fait. A confiderable ebullition is 
 immediately excited ; and when this effervef- 
 cence is darkened, the retort is gradually heat- 
 ed, and the mixture made to boil. 
 
 The acid is difengaged in the ftate of gas; 
 and mixes rapidly with the water, in which it 
 produces a confiderable degree of heat. 
 
 The water of the firft bottle is ufually fatu- 
 rated with the acid gas, and forms a very con- 
 centrated and fuming acid ; and though the 
 fecond is weaker, it may be carried to any de- 
 lired degree of concentration, by impregnating 
 it with a new quantity of the gas. 
 
 The ancient chemifls were divided refpefting 
 the nature of the muriatic acid. Becher fup- 
 pofed it to be the fulphuric acid modified by 
 his mercurial earth. 
 
 This acid is fufceptible of combining with 
 an additional dofe of oxigene; and, what is 
 very extraordinary, it becomes more volatile in 
 confequenceof this additional quantity ; where- 
 as the other acids appear to acquire a greater 
 degree of fixity in the lame circumflances. It 
 may even be faid, that its acid virtues become 
 weaker in this cafe, fince its affinities with alka- 
 lis diminifh ; and it is fo far from reddening 
 blue vegetable colours, that it deftroys them. 
 
 Another 
 
Oxigenated Muriatic Acid . 241 
 
 Another phenomenon not lefs interefling, 
 which is prefented to us by this new combina- 
 tion, is, that though the muriatic acid feizes 
 the oxigene with avidity, yet it contracts fo 
 weak a union with it, that it yields it to almoft 
 all bodies, and the mere action of light alone 
 is fufficient to difengage it. 
 
 It is to Scheele that we are indebted for the 
 difcovery of the oxigenated muriatic acid. He 
 formed it in the year 1774, by employing the 
 muriatic acid as a folvent for manganefe. He 
 perceived that a gas was difengaged, which pof- 
 feffed the diftindtive fmell of aqua regia ; and 
 he was of opinion that in this cafe the muriaric 
 acid abandoned its phlogifton to the manga- 
 nefe; in confequence of which notion he called 
 it the Dephlogifticated Marine Acid. He took 
 notice of the principal and truly aftonifhing 
 properties of this new fubflance; and all che- 
 mifts fince his time have thought their atten- 
 tion well employed in examining a fubftance 
 which exhibits fuch lingular properties. 
 
 To extra# this acid, I place a large glafs 
 alembic of one lingle piece upon a fand bath. 
 To the alembic I adapt a fmall receiver ; and 
 to the receiver three or four fmall bottles near- 
 ly filled with diddled water, and arranged ac- 
 cording to the method of Woulfe. I difpofe the 
 Vol. I. R 
 
 receiver 
 
242 Oxigenated Muriatic Acid « 
 
 receiver and the bottles in a ciftern, the places 
 of junction being luted with fat lute, and fe- 
 cured with rags foaked in the lute of lime and 
 white of egg. Laftly, I furround the bottles 
 with pounded ice. When the apparatus is thus 
 difpofed, I introduce into the alembic half a 
 pound of manganefe of Cevennes, and pour up- 
 on it, at feveral repetitions, three pounds of 
 fuming muriatic acid. The quantity of acid 
 which I pour at once is three ounces ; and at 
 each time of pouring a confiderable efferve- 
 fcence is excited. I do not pour a new quantity 
 until nothing more comes over into the receiv- 
 ers. This method of proceeding is indifpenf- 
 ably neceffary, when the operator is defirous of 
 making his procefs with a definite quantity of 
 the materials. For if too large a quantity of 
 acid be poured at once, it is impoflible to re- 
 train the vapours ; and the effervefcence will 
 throw a portion of the manganefe into the re- 
 ceiver. The vapours which are developed by 
 the affufion of muriatic acid are of agreeniih 
 yellow colour; and they communicate this co- 
 lour to the water when they combine with it. 
 When this vapour is concentrated by means of 
 the ice, and the water is faturated with it, it forms 
 a fcum at the furface, which is precipitated 
 through the liquid, and refembles a congealed 
 
 oil. 
 
243 
 
 Oxigenated Muriatic Acid . 
 
 oil. It is neceffary to a (Tift the adtion of the 
 muriatic acid by means of a moderate heat ap- 
 plied to the fand bath. The fecure luting of 
 the velfels is alfo an elTential circumftance ; for 
 the vapour which might efcape is fuffocating, 
 and would not permit the chemift to infpedt his 
 operation clofely. It iseafy to difcover the place 
 where it efcapes through the lutes, by running a 
 feather dipped in volatile alkali over them : the 
 combination of thefe vapours inftantly forms a 
 white cloud, which renders the place vifible 
 where the vapour efcapes. An excellent Me- 
 moir of Mr. Berthollet, publifhed in the An- 
 nales Chimiques, may be confulted upon the 
 oxigenated muriatic acid. 
 
 The fame oxigenated muriatic acid may be 
 obtained by diddling, in a fimilar apparatus, 
 ten pounds of marine fait, three or four pounds 
 of manganefe, and ten pounds of fulphuric acid. 
 
 Mr. Reboul has obferved that the concrete 
 Rate of this acid is a cryRallization of the acid, 
 which takes place at three degrees of tempera- 
 ture below the freezing point of Reaumur. 
 The forms which have'been obferved are thofe 
 of a quadrangular prifm, truncated very ob- 
 liquely, and terminated by a lozenge. He has. 
 likewife obferved hollow hexahedral pyramids 
 on the furface of the liquor. 
 
 R 2 
 
 To 
 
244 Oxigenated Muriatic Acid . 
 
 To make ufe of the oxigenated acid in the 
 arts, and in order to concentrate a greater quan- 
 tity in a given volume of water, the vapour is 
 made to pafs through a folution of alkali. A 
 white precipitate is at firft formed in the li- 
 quor ; but a fhort time afterwards the depolition 
 diminifhes, and bubbles are difengaged, which 
 are nothing but the carbonic acid. In this cafe 
 two falts are formed, the oxigenated muriate, 
 and the ordinary muriate. The mere impref- 
 iion of light is fufficient to decompofe the for- 
 mer, and convert it into common fait. This 
 lixivium contains, indeed, the oxigenated acid 
 in a ftronger proportion. The execrable fmell 
 of the acid is much weakened. It may be em- 
 ployed for various ufes with the fame fuccefs, 
 and with great facility; but the effed is very 
 far from correfponding with the quantity of 
 oxigenated acid which enters into this combi- 
 nation, becaule the virtue of a great part is de- 
 stroyed by its union with the alkaline balls. 
 
 The oxigenated muriatic acid has an excef- 
 lively ftrong fmell. ltadsdiredly on the la- 
 rynx, which it Simulates, excites coughing, 
 and produces violent head-aches. 
 
 Its tafte is fharp and bitter. It fpeedily de- 
 liroys the colour of tindure of turnfole. But it 
 appears that the property which moft oxige- 
 nated 
 
Oxigenated Muriatic Acid. 245 
 
 nated fubflances pofTefs, of reddening blue co- 
 lours, arifes only from the combination of oxi- 
 gene with the colouring principles ; and that, 
 when this combination is very flrong and ra- 
 pid, the colour is delfroyed. 
 
 The oxigenated muriatic acid with which a 
 folution of cauftic alkali is faturated, affords, 
 by evaporation in veffels fecluded from the light, 
 common muriate and oxigenated muriate. 
 This laft detonates upon charcoal ; is more fo- 
 luble in hot than in cold water; cryftallizes, 
 fometimes in hexahedral laminae, and oftener 
 in rhomboidal plates. Thefe cryftals have an 
 argentine brilliancy, like mica. Its tafte is 
 faint; and its cryftals, when they are dilfolved 
 in the mouth, produce a fenfation of coolnefs 
 refembling that of nitre. 
 
 Mr. Berthollet has afcertained, by delicate 
 experiments, that the oxigenated muriatic acid 
 which exifls in the oxigenated muriate of pot- 
 afh, contains more oxigene than an equal weight 
 of oxigenated muriatic acid dilfolved in water ; 
 and this has led him to confider the oxigenated 
 acid combined in the muriate as being fuper- 
 oxigenated. He conliders the common muri- 
 atic gas with relation to the oxigenated muria- 
 tic gas, the fame as the nitrous gas or fulphure- 
 ous gas with refpeft to the nitric and fulphuric 
 
 acids, 
 
246 Gunpowder with Muriatic Salt . 
 
 acids. He pretends that the produ&ion of the 
 Ample muriate and the oxigenated muriate in 
 the fame operation, may be compared to the 
 action of the nitric acid, which in many cafes 
 produces nitrate and nitrous gas. Hence he 
 has coniidered the muriatic acid as a pure radi- 
 cal, which combined with a greater or lefs quan- 
 tity of oxigene, forms either Ample muriatic 
 acid gas, or the oxigenated muriatic acid gas. 
 
 The oxigenated muriates of foda do not dif- 
 fer from thofe of pot-afh, but in being more 
 deliquefcent and foluble in alcohol, lijce all 
 the falts of this nature. 
 
 The oxigenated muriate of pot-afh gives 
 out its oxigene in the light, and by diftillation 
 as foonas the veffel is heated torednefs. One 
 hundred grains of this fait afford feventy-five 
 cubic inches of oxigenous gas reduced to the 
 temperature of twelve degrees of Reaumur. 
 This air is purer than the others, and may be 
 employed for delicate experiments. The oxi- 
 genated muriate of pot-afh, when cryftallized, 
 does not trouble the folutions of nitrate of 
 lead, of filver, or of mercury. 
 
 . Mr. Berthollet has fabricated gunpowder, 
 by fubftituting the oxigenated muriate inflead 
 of faltpetre. The effects it produced were 
 quadruple. The experiment in the large way, 
 
 which 
 
Bleaching by Oxigenated M. Acid . 247 
 
 which was made at Eflone, is but too well 
 known, by the death of Mr. Le Tors and Ma. 
 demoifelle Chevraud. This powder exploded 
 the moment the mixture was triturated. 
 
 The oxigenated muriatic acid whitens thread 
 and cotton. For this purpofe the cotton is 
 boiled in a weak alkaline lixivium ; after which 
 the (tuff is wrung out, and fteeped in the oxi- 
 genated acid. Care is taken to move the cloth 
 occafionally in the fluid, and to wring it out. 
 It is then wafhed in a large quantity of water, 
 to deprive it of the fmell with which it is im- 
 pregnated. 
 
 I have applied this known property to the 
 whitening of paper and old prints : by this 
 means they obtained a whitenefs which they 
 never before poflefled. Common ink difap- 
 pears by this acid ; but printers ink is not at- 
 tacked by it. 
 
 Linen and cotton cloths, and paper, may be 
 bleached by the vapour of the oxigenated ma- 
 rine acid. I have made fome experiments in 
 the large way, which have convinced me of the 
 poffibility of applying this method to the arts. 
 The Memoir in which I have given an account 
 of my experiments, will be printed in the vo- 
 lume of the Academy of Paris for the year 1787* 
 
 The oxigenated muriatic acid thickens oils ; 
 
 and 
 
248 
 
 Oxigenated Muriatic Acid . 
 
 and oxides metals to fuch a degree, that this 
 procefs may be advantageoufly ufed to form 
 verditer. 
 
 The oxigenated muriatic acid diffolves me- 
 tals without effervefcence; becaufe its oxigene 
 is fufficient to oxide them without the neceffity 
 of the decompofition of water, and confequent- 
 ]y without the difengagement of gas. 
 
 This acid precipitates mercury from its fo- 
 lution, and converts it into the ftate of corro- 
 five fublimate. 
 
 It converts fulphur into fulphuric acid, and 
 infiantly deprives the very black fulphuric acid 
 of its colour. 
 
 When mixed with nitrous gas, it pafTes to 
 the ftate of muriatic acid, and converts part of 
 the gas into nitric acid. 
 
 When expofed to light, it affords oxigen- 
 ousgas, and the muriatic acid is regenerated. 
 
 The muriatic acid acts very efficacioufly up r 
 on metallic oxides, merely in confequence of 
 its becoming oxigenated ; and in this Cafe it 
 forms with them falts, which are likewife more 
 or lefs oxigenated. 
 
 ARTI- 
 
Muriate of Pot -a fJj. 249 
 
 ARTICLE I. 
 
 \ 
 
 Muriate of Pot-afh. 
 
 This fait is ftill diftinguilhed by the name 
 of Febrifuge Salt of Sylvius. 
 
 It has a difagreeable ftrong bitter tafte. 
 
 It cryftallizes in cubes, or in tetrahedral 
 prifms. 
 
 It decrepitates upon coals ; and when urged 
 by a violent heat it fufes, and is volatilized 
 without decompolition. 
 
 It requires three times its weight of water, 
 at the temperature of fixty degrees of Fahren- 
 heit, for its folution. 
 
 It is fubjedt to little alteration in the air. 
 
 One hundred grains of this fait contain 29. 68 
 acid, 63.47 alkali, and 6.85 water. It is fre- 
 quently met with, but in fmall quantities, in 
 the water of the fea, in plafter, in the afhes of 
 tobacco, &c. The exigence of this fait in the 
 afhes of tobacco might with juftice have fur- 
 prifed me, as I had reafon to expedt the muriate 
 of foda which is employed in the operation 
 called watering. Was the foda metamorphofed 
 into pot-alh by the vegetable fermentation ? 
 This may be determined by direct experiments. 
 
 ARTI- 
 
2$Q 
 
 Muriate of Soda , 
 
 ARTICLE IL 
 Muriate of Soda. 
 
 The received names of Marine Salt, Com- 
 mon Salt, and Culinary Salt, denote the com- 
 bination of muriatic acid with foda. 
 
 This fait has a penetrating but not bitter 
 tafle. It decrepitates on coals, fufes, and is 
 volatilized by the heat of a glafs-maker’s fur- 
 nace, without decompofition. 
 
 It is foluble in 2.5 times its weight of water, 
 at fixty degrees of Fahrenheit’s thermometer. 
 
 One hundred grains of this fait contain 33.3 
 acid, 50 of alkali, and 16.7 of water. 
 
 It cryftallizes in cubes. Mr. Gmelin has in- 
 formed us that the fait of the fait lakes in the 
 environs ofSellian on the banks of the Cafpian 
 fea A forms cubical and rhomboidal cryflals. 
 
 Mr. De Lifle obferves, that a folution of ma- 
 rine fait, left to infenfible evaporation during 
 five years by Mr. Rouelle, had formed regular 
 octahedral cryflals refembling thofe of alum. 
 
 Marine fait may be obtained in octahedrons, 
 by pouring frefh urine into a very pure folution 
 of frefh filt. Mr. Rerniard is convinced that 
 this addition changed only the form of the fait, 
 without altering its nature. 
 
 Common 
 
 y 
 
or Common Salt. 
 
 251 
 
 Common fait is found native in many places. 
 Catalonia, Calabria, Switzerland, Hungary, and 
 Tyrol poffefs mines, which are more or lefs 
 abundant. The richeft fait mines are thofe of 
 Wieliczka in Poland. Mr. Berniard has given 
 us a defcriptionof them in the Journal de Phy- 
 fique; and Mr. Macquart, in his Effays on 
 Mineralogy, has added interefting details con- 
 cerning the working of thefe mines. 
 
 Our fait fprings in Lorraine and Franche- 
 comte, and fome indications afforded by Ble- 
 ton, have appeared fufficient motives to Mr. 
 Thouvenel to prefume that fait mines exift in 
 our kingdom. This chemift expreffes himfelf 
 in the following manner : 
 
 f€ At the diftance of tw 7 o leagues from Sa- 
 verne, between the village of Hudtenhaufen 
 and that of Garbourg, in a lofty mountain called 
 Penfenperch, there are two great refervoirs of 
 fait water; the one to the eaft, at the head of 
 a large deep and narrow 7 valley, which is called 
 the great Limerthaal ; the other to the wefi, 
 upon the oppofite flope, towards Garbourg. 
 They communicate together by five fmall 
 ftreams, which are detached from the upper re- 
 fervoir, and unite in the lower one. From thefe 
 two fait refervoirs flow tw 7 o large llreams ; the 
 upper runs into Franche-comte, and the lower 
 
 into 
 
2 5 2 Salt Springs and Mines , 
 
 into Lorraine, where they fupply the well- 
 known fait works.” 
 
 The waters therefore flow to the diftance of 
 feventy leagues from the refervoir. 
 
 Salt mines appear to owe their origin to the 
 drying up of vafl: lakes. The fhells and madre- 
 pores found in the immenfe mines of Poland 
 are proofs of marine depofitions. There are 
 likewife fome feas in which the fait is fo abun- 
 dant, that it is depofited at the bottom of the 
 water; as appears from the analyfls of the wa- 
 ter of the lake Afphaltites, made by MefTrs. 
 ,Macquer and Sage. 
 
 This native fait is often coloured; and as 
 in this ftate it poffeffes conflderable brilliancy, 
 it is called Sal-gem. It almoft always contains 
 an oxide of iron, which colours it. 
 
 As thefe fait mines are neither fufficiently 
 abundant to fupply the wants of the inhabitants 
 of the globe, nor diftributed with that unifor- 
 mity as to permit all nations to have ready re- 
 courfe to them, it has been found neceflary to 
 extradl the fait from the water of the fea. The 
 fea does not contain an equal quantity in all 
 climates; Ingenhoufz has fhewn us that the 
 northern feas contain lefs than the fouthern. 
 Marine fait is fo abundant in Egypt, that, ac- 
 cording to Halfelquifl:, a frelh-water fpring is 
 
 • a treafure 
 
Extraction of Salt from Waters* 253 
 
 a treafure which is fecretly tranfmitted from 
 father to fon. 
 
 The method of extrading the water of the 
 fea varies according to the climates. 
 
 1. In the northern provinces, the fait fands 
 of the fea coafts are wafhed with the lead: pof- 
 fible quantity of water, and the fait is obtained 
 by evaporation. — See the defcription of this 
 procefs by Mr. Guettard. 
 
 2. In very cold countries, fait water is con- 
 centrated by freezing, and the refidue is evapo- 
 rated by fire. — See Wallcrius. 
 
 3. At the fait fprings of Lorraine and Fran- 
 checomte, the water is pumped up, and differ- 
 ed to fall upon heaps of thorns, which divide 
 it, and caufe a part to evaporate. The farther 
 concentration is effeded in boilers. 
 
 4. In the fouthern provinces, at Feccais, at 
 Peyrat, at Cette, and elfewhere, the extradion 
 is begun by feparating a certain quantity of 
 water from the general mafs of the fea, w # hich 
 is differed to remain in fquare fpaces, called 
 Partenemens. For this purpofe it is neceffary 
 to have fluices which may be opened and fhut 
 at pleafure, and to form furrounding walls 
 w ? hich prevent all communication with the fea, 
 except by means of thefe gates. It is in the 
 partenemens that the water goes through the 
 
 firft 
 
2 3 4 Decompofliion of Sea Salt . 
 
 firft ftage of evaporation; and when it begins 
 to depofit its fait, it is raifed by bucket wheels 
 to other fquare compartments, called Tables, 
 where the evaporation finifhes. 
 
 The fait is heaped together, to form the 
 cdmmelles ; in which ftate it is left for three 
 years, in order that the deliquefcent falts may 
 flow out of it s and, after this interval of time, 
 it is carried to market. 
 
 Exertions and enquiries have long fince been 
 made to difcover a cheap method of decom- 
 posing marine fait, to obtain the mineral alka- 
 li at a low price, which is of fuch extenlive 
 life in the manufactures of foap, glafs, bleach- 
 ing, &c. The procefles hitherto difcovered 
 are the following: 
 
 1. The nitric acid difengages the muriatic 
 acid, and forms the nitrate of foda, which may 
 be eafily decompofed by detonation. 
 
 2. Pot-afh difplaces the foda, even in the 
 cold, as I found by experiment. 
 
 3. The fulphuric acid forms fulphate of foda 
 by decompofing the marine fait ; the new fait, 
 when heated with charcoal, is deftroyed ; but a 
 fulphure of foda, or liver of fulphur, is formed, 
 which is difficult to be entirely feparated; and 
 this procefs does not appear to me to be econo- 
 mical. The fulphate may likcwife be decom- 
 pofed 
 
^55 
 
 Decomposition of Sea Salt . 
 
 pofed by the acetite of barytes, and the foda 
 afterwards obtained by calcination of the acetite 
 of foda. 
 
 4. Margraff tried in vain to accomplifh this 
 purpofe, by means of lime, ferpentine, iron, 
 clay. Sec. He adds that if common fak be 
 thrown upon lead heated to rednefs, the fait is 
 decompofed, and muriate of lead is formed. 
 
 5. Scheele has pointed out the oxides of lead 
 for the decompofition of common fait. If com- 
 mon fait be mixed with litharge, and made in- 
 to a pafte, thclitharge gradually lofes its colour, 
 and becomes converted into a white matter, 
 from which the foda may be extracted by walk- 
 ing. It is by precedes of this kind that Tur- 
 ner extradls it in England; but this decompo- 
 fition never appeared to me to be complete, 
 unlefs the litharge was employed in a propor- 
 tion quadruple to that of the fait. I have ob- 
 fer.ved that almoft all the bodies are capable of 
 alkalizing marine fak, but that the abfolute 
 decorhpofition is very difficult. 
 
 6. Barytes decompofes it likewife, according 
 to the experimei}ts of Bergmann. 
 
 7. The vegetable acids, combined w ith lead, 
 may likewife be ufed to decompofe common 
 fak. When thefe falts are mixed, a decom- 
 polition takes place: the muriate of lead falls 
 
 dow n ; 
 
256 Muriate of Ammoniac*. 
 
 down ; and the vegetable acid, united to the 
 foda, remains in folution. The vegetable acid 
 may be difTipated by evaporation and calcina- 
 tion; and the alkali remains difengaged. 
 
 Marine fait is more efpecially employed at 
 our tables, and in culinary purpofes. It re- 
 moves and corrects the infipidy of our food, 
 and at the fame time facilitates digeftion. It is 
 ufed in a large proportion to preferve flefh 
 from putrefaction ; but in a fmall dofe it haftens 
 that procefs, according to the experiments of 
 Pringle, Macbride, Gardane, &c. 
 
 ARTICLE III. 
 
 Muriate of Ammoniac. 
 
 Of all the combinations of ammoniac this is 
 the molt intereftirig, and the moft generally ufed . 
 It is known by the name of Sal Ammoniac. 
 
 This fait may bediredtly formed by decom- 
 pofing the muriate of lime by the means of 
 ammoniac, as Mr. Baume has praCtifed at Paris. 
 But almoft all rhe fal ammoniac which circu- 
 lates in commerce is brought to us from Egypt, 
 where it is extracted by diftillation from foot, 
 by the combuftion of the excrements of fuch 
 animals as feed on faline plants. 
 
 The 
 
or Common Sal Ammoniac . 257 
 
 The details of the procefs which is lifed have 
 not been very long known. One of the firft 
 writers who gave adefcription of this operation 
 is father Sicard. He informed us, in 1716, 
 that diftillirtg veffels were charged with the foot 
 of the excrements of oxen, to which fea fait 
 and camels urine were added. 
 
 Mr. Lemaire, conful at Cairo, in a letter 
 written to the Academy of Sciences in 1720, 
 affirms that neither urine nor fea fait is 
 added. 
 
 Mr. HafTelquift has communicated to the 
 Academy of Stockholm a confiderably extent 
 live defcription of the procefs* by which we 
 karri, that the dung of all animals which feed 
 onfaline plants is indifcriminately ufed, and that 
 the foot is diftilled, to obtain fal ammoniac. 
 
 The dung is dried by applying it againfi: the 
 walk ; and it; is burned inhead of wood, in fuch 
 countries as do not poffefs that fuel. Thefub- 
 limation is performed in large round bottles of 
 one foot and a half diameter, terminating in a 
 neck of two inches in height ; and they are 
 filled to within four inches of the neck. The 
 fire is kept up during three times twenty-four 
 hours.; the fait is fublimed to the upper part 
 of thefe velfels, where it forms a mafs of the 
 fame figure as the veiTels themfelves. Twenty 
 
 Vo l. I, S pounds 
 
258 Extraction of Sal Ammoniac • 
 
 pounds of foot afford fix pounds of fal ammo- 
 niac, according to Rudenfkield. 
 
 I was always of opinion that fal ammoniac 
 might be extracted by treating the dung of the 
 numerous animals which feed on faline plants 
 in the plains of La Camargue and La Crau> in 
 the fame manner ; and after having procured, 
 with the greateft difficulty, two pounds of the 
 foot, I extracted from it four ounces of fal am. 
 moniac. I muft obferve, to fave much trouble 
 to thofe who may wiffi to follow this branch of 
 commerce, that the dung produced during the 
 fummer, the fpring, or the autumn, does not 
 afford this fait* I did not know to what cir- 
 cumftance to attribute the verfatility of my 
 refults, until I found that thefe animals do not 
 eat faline vegetables, excepting at the time when 
 frefh plants cannot be had ; and that they are 
 reduced to the neceffity of having recourfe to 
 faline plants only during the three winter 
 months. This obfervation appears to me to 
 be a proof, that marine fait is decompofed in 
 the firft paffages ; and that the foda is modifi- 
 ed to the ftate of ammoniac. 
 
 Sal ammoniac is continually fublimed through 
 the apertures of volcanic mountains. Mr. Fer- 
 ber found it ; and Mr. Sage admitted its exifl- 
 ence among voj panic products. It is found in 
 
Sal Ammoniac . 2^9 
 
 the grottos of Puzzolo, according to Meffrs. 
 Swab, Scheffer, &c. 
 
 It is found in the country of the Calmucs. 
 Model analyfed it. 
 
 It is alfo produced in the human body, and 
 exhales by perforation in malignant fevers. Mr* 
 Model has proved this facft in his own perfon : 
 feral the time of a. violent Tweat which termi- 
 nated a malignant fever, he wafhed his hands 
 in a lolution of pot-afh, and obferved that a pro- 
 digious quantity of alkaline gas was difengaged. 
 
 Sal *ammoniae cryftallizes by evaporation in 
 quadrangular prifrns, terminated by ftiort qua- 
 drangular pyramids. It is often obtained in 
 rhombic cryftals by fublimation. The concave 
 face of the loaves of fal ammoniac in commerce 
 
 7 f 
 
 is fometimes covered with thefe cryftals* 
 
 This fait has a penetrating, acid, urinous tafte* 
 It pofTefies a degree of dudtility which renders 
 it ’flexible, and caufes it to yield to a blow of 
 theihammer. It does not change in the air ; 
 which circumftance renders it probable that 
 our fal ammoniac is different from that men- 
 tioned by Pliny and Agricola, as that attracted 
 humidity. Three parts and a half of water dif- 
 folve one part of fal ammoniac, at ftxty degrees 
 of Fahrenheit’s thermometer; a conftderable 
 degree of cold is produced by its folution. 
 
 ■One hundred parts of fal ammoniac contain 
 S 2 fifty- 
 
260 Nitro-muriatic Acid , 
 
 fifty-two parts acid, forty ammoniac, and eight 
 water. 
 
 This fait is not at all decompofed by clay ; 
 nor by magnefia except with difficulty, and in 
 part only ; but it is completely decompofed 
 by lime and fixed alkalis. The fulphuric and 
 .nitric acids difengage its acid. 
 
 This fait is ufed in dyeing, to bring out cer- 
 tain colours. It is mixed with aqua fortis, to 
 increafe its folvent power. 
 
 It is ufed in foldering ; in which operation it 
 pofTeffes the double advantage of clearing the 
 metallic furface^and preventing its oxidation# 
 rvv:o ' ’ j .'-T •?,.! » * b 
 
 } - ( . ■ - juiwta*— — 
 
 • < **’) ; • - 1 • 4 r ■ • » «0 -/ i 
 
 CHAP. V. 
 
 Concerning the Nitro-muriatic Acid, 
 
 _ 
 
 rnHE acid which we call Nitro-muriatic, 
 A is a combination of the nitric and mu- 
 riatic acids. 
 
 x 
 
 r Our predeceffors diftinguifhed it by the name 
 of Aqua Regia, on account of its property of 
 diffolving gold. 
 
 this mixed acid. 
 
 If two ounces of common fait be diftilled 
 with four of nitric acid, the acid which comes 
 
 over 
 
Nitro-muriatic Acid . 26 1 
 
 over into the receiver will be good nitro-mu- 
 riatic acid. 
 
 This is the procefs of Mr. Baume. 
 
 The nitrate of pot-afh may be decompofed 
 by diddling two parts of muriatic acid from one 
 of this fait : good aqua regia is the produdt of 
 this operation ; and the reiidue is a muriate 
 of pot-afh, according to Mr. Cornette. 
 
 Boerhaave affirms that he obtained a good 
 aqua regia, by diftiiling a mixture of two parts 
 of nitre, three of fulphate of iron or martial 
 vitriol, and five of common fait. 
 
 The Ample diftillation of nitre of the firft 
 boiling affords aqua regia ; which is employed 
 by the dyers in the folution of tin, for the com- 
 pofition of the fcarlet dye. This aqua fortis is 
 a true aqua regia : and it is by virtue of the 
 mixture of acids that it diflolves tin ; for if it 
 confided of the nitric acid in a date of too great 
 purity, it would corrode and oxide the metal 
 without diffolving it. The dyers then fay that 
 the aqua fortis precipitates the tin ; and they 
 corredt the acid by diffolving fal ammoniac or 
 common fait in it. 
 
 Four ounces of fal ammoniac in powder, 
 diffolved gradually, and in the cold, in one 
 pound of nitric acid, form an excellent aqua 
 regia. An oxigenated muriatic acid gas is di.f- 
 
 engaged 
 
Nit ro - muriatic Acid. 
 
 26 2 
 
 engaged for a long time ; which it is impru- 
 dent to attempt to coerce, and which ought to 
 be Buffered to efcape by convenient apertures. 
 
 Aqua regia is likewife formed by mixing 
 together two parts of pure nitric acid and one 
 of muriatic acid. 1 
 
 The very evident fmell of oxigenated muri- 
 atic acid, which is difengaged in every procefs 
 which can be adopted to form the acid at pre- 
 fent in queftion ; and the property which it 
 pofTeffes, equally with the oxigenated muriatic 
 acid, of diffolving gold, have led certain che- 
 mifts to infer that, in the mixture of thefe two 
 acids, the muriatic acid feized the oxigene of the 
 nitric, and affumed the charaderof oxigenated 
 muriatic acid : fo that the nitric acid was con- 
 fidered as anfwcring no other purpofe than that 
 of oxigenating the muriatic. But this fyftem is 
 inconfiftent ; and though the virtues of the 
 muriatic acid are modified by this mixture, and 
 it is oxided by the decompofition of a portion 
 of the nitric acid, neverthelefs the two acids 
 Bill exift in the aqua regia: and I am convinc- 
 ed that the beft made aqua regia, fatu rated with 
 pot-afh, will afford the ordinary muriate, the 
 oxigenated muriate, and the nitrate. It appears 
 to me that the powerful addon of aqua regia 
 depends fimply on the union of the two acids ; 
 
 one 
 
Acid of Borax 
 
 263 
 
 one of which is exceedingly well calculated to 
 oxide the metals, and the other diflblves the 
 oxides or calces with the greateft avidity. 
 
 Concerning the Acid of Borax. 
 
 HE acid of borax, more generally known 
 
 by the name of Homberg’s Sedative Salt, 
 is almoft always afforded by the decompofition 
 of the borate of foda, or borax. But it has 
 been found perfectly formed in certain places ; 
 and we have reafon to hope that we fhall fpeed- 
 ily acquire more accurate information refpecft- 
 ing its nature. 
 
 Mr. Hoefer, director of the Pharmacies of 
 Tufcany, was the firft who detected this acid 
 fait in the waters of the lake Cherchiajo, near 
 Monte-rotondo, in the inferior province of Si- 
 enna : thefe waters are very hot, and they afford- 
 ed him three ounces of the pure acid in one 
 hundred and twenty pounds of the water. This 
 fame chemifl: having evaporated twelve thou- 
 fand two hundred and eighty grains of the water 
 of the lake of Caftelnuovo,obtained one hundred 
 
 CHAP. VI 
 
 and 
 
2 b 4 Acid of Borax. 
 
 and twenty grains. He prefumes, moreover, 
 that it might be found in the water of feveral 
 other lakes, fuch as thofe o,f Laffo, Monte- 
 cerbeloni, &c. 
 
 Mr. Sage has depoRted in the hands of the 
 Royal Academy of Sciences fome acid of borax, 
 brought from the mines of Tufcany by Mr. 
 Beffon, who colleded it himfelf. 
 
 Mr. WeRrumb found fedative fait in the 
 Rone called Cubic Quartz of Lunebtirg. He 
 obtained it by decompoRng this Rone by the 
 acids of fulphur, nitre, &c. The refult of his 
 analyfis is the following : 
 
 Sedative fait 
 
 tV 
 
 Calcareous earth 
 
 T* To 
 
 Magefia — 
 
 
 Clay and filex 
 
 2 
 
 Iron — 
 
 to 2 
 
 ToS L y To7 
 
 This Rone, according to the obfervations of 
 LaRius, has the form of fmall cubical cryRals, 
 fomerimes tranfparent, in other fpecimens 
 milky, and affords fparks with the Reel. 
 
 The acid of borax is generally found com- 
 bined with foda. It is from this xombination 
 that it is difengaged, and obtained either by 
 fubiimation or cryRallization. 
 
 When it is propofed to obtain it by fubii- 
 mation, three pounds of calcined fulphate of 
 
 iron* 
 
Acid of Borax • 265 
 
 iron, and two ounces of borate of foda > are dif- 
 folved in three pounds of water. The folution 
 is then filtered, and evaporated to a pellicle ; 
 after which the fublimation is performed in a 
 cucurbit of glafs with its head. The acid of bo- 
 rax attaches itfelf to the internal furface of the 
 head, from which it may be fwept by a feather. 
 
 Homberg obtained it by decompoling of 
 borax with the fulphuric acid. This procefs 
 fucceeded with me wonderfully well. For this 
 purpofe I make ufe of a glafs cucurbit with its 
 head, which I place on a fand bath. I then 
 pour upon the borax half its weight of ful- 
 phuric acid, and proceed to fublimation. The 
 fublimed acid is of the moft beautiful white- 
 nefs. 
 
 Stahl, and Lemery the younger, obtained 
 the fame acid by making ufe of the nitric and 
 muriatic acids. . 
 
 To extract the acid of borax by cryftalliza- 
 tion, the borax is diffolved in hot water, and 
 an excefs of fulphuric acid is poured in. A 
 fait is depofited during the cooling on the fide 
 of the veffel, in the form of thin round plates, 
 applied one upon the other. This fait, when 
 dry, is very white, very light, and of a filvery 
 appearance. It is the acid of borax. 
 
 We are indebted to Geoffroy for this procefs, 
 
 Baron 
 
266 
 
 Acid of Borax . 
 
 Baron has added two fadts: the fir ft, that the 
 vegetable acids are equally capable of decom- 
 pofing borax ; and the fecond, that borax may 
 be regenerated by combining the acid of borax 
 with foda. 
 
 This acid may be purified by folution, filtra- 
 tion, and evaporation ; but it muft be obferved, 
 that a confiderable part is volatilized with the 
 water which flies off in the evaporation. 
 
 The acid of borax has a faline cool tafte. It 
 colours the tindlure of turnfole, fyrup of vio- 
 lets, &c.red. 
 
 One pound of boiling water diffolved no 
 more than one hundred and eighty-three grains, 
 according to Mr. De Morveau. 
 
 Alcohol diffolves it more eafily ; and the 
 flame which this folution affords is of a beauti- 
 ful green. This acid, when expofed to the 
 fire, is -reduced to a vitriform and tranfparent 
 fubftance, inftead of rifing; which proves, as 
 Rouelle has obferved, that it is only fublimed 
 by favour of the water, with which it forms a 
 very volatile compound. 
 
 As moft of the known acids decompofe this 
 acid, and exhibit it in the fame form, it has 
 been thought a juftifiable conclufion that it ex- 
 ifts ready formed in the borax. Mr. Baume has 
 even affirmed that he compofed this acid by 
 
 leaving 
 
Borate of Pot -ajh. 267 
 
 leaving a mixture of grey clay, greafe, and 
 cows dung expofed to the air in a cellar. But 
 Mr. Wiegleb, after an unfuccefsful labour of 
 three years and a half, thinks himfelf autho- 
 rifed to give a formal negative to the French 
 chemift. 
 
 Mr. Cadet has endeavoured to prove 
 
 1. That the acid of borax always retains a por- 
 tion of the acid employed in the operation. 
 
 2. That this fame acid has ftill the mineral al- 
 kali for its bafis. — Mr. De Morveau has, with 
 his ufual fagacity, difculfed all the proofs 
 brought forward by Mr. Cadet ; he has {hewn 
 that none of them are conclufive, and that the 
 acid of borax is entitled to retain its place 
 among the chemical elements. 
 
 ARTICLE I. 
 
 Borate of Pot-afh. 
 
 The acid of borax combined with pot-afh 
 forms this fait. It may be obtained either by 
 the diredt combination of thefe two feparate 
 principles, or by decompofing borax by the 
 addition of pot-afh. 
 
 This fait, which is yet little known, afforded 
 Mr. Baume fmall cryftals. 
 
 The acids difengage it by feizing its alka- 
 line bafe. 
 
 ARTI- 
 
a 6 8 Borate of Soda , or Common Borax . 
 
 ARTICLE II. 
 
 Borate of Soda. 
 
 This combination forms Borax, properly fo 
 called. 
 
 It is brought to us from the Indies ; and its 
 origin is ftill unknown*. 
 
 The article Borax may be confulted in Bo- 
 mare’s Dictionary of Natural Hiftory. 
 
 It does not appear that borax was known to 
 the ancients. The chryfocolla, of which Diof- 
 corides fpeaks, was nothing but an artificial 
 folder compofed, by the goldfmiths themfelves, 
 with the urine of children and ruft of copper, 
 which were beaten together in a mortar of the 
 fame metal. 
 
 The word Borax is found for the firfl time in 
 the works of Geber. Every thing which has 
 been written fince that time concerning borax, 
 
 * The origin of borax is very well afcertained in two Pa- 
 pers, in the feventy feventh volume of the Philofophical 
 Tranfaftions, Numbers xxviii. and xxix. It is dug up in 
 a cryftallized ftate from the bottom of certain fait lakes in a 
 mountainous, barren, volcanic diftrift, about twenty-five 
 days journey to the eaftward of Lafla, the capital of the king- 
 dom of Thibet. T. 
 
 is 
 
i The Hifiory and Purification of Borax. 2 6$ 
 
 is applicable to the Fubftance which is at pre- 
 fent known to us by that name. 
 
 Borax is found in commerce in three different 
 Bates. — The firft is brute borax, tincall, or 
 chryfocolla. It comes to us from Perfia, and 
 is enveloped and foiled by a greafy covering. 
 The pieces of brute borax have almoft all of 
 them the form of a (ix-ftded prifm, (lightly 
 flattened, and terminated by a dihedral pyra- 
 mid. The fradhireof thefe cryftals is brilliant, 
 with a greeni(h caft. This kind of borax is 
 very impure. It is pretended that borax is 
 extracted from the lake of Necbal, in the king- 
 dom of Grand Thibet. This lake is filled with 
 water during the winter, which exhales in the 
 fummer ; and when the waters are low, work- 
 men enter, who detach the cryftals from the 
 muddy bottom, and put them into bafkets. 
 
 The Weft Indies contain borax. It is to 
 Mr. Anthony Carera, a phyftcian eftabliftied 
 at Potoft, that we are indebted for this difco- 
 very* The mines of Riquintipa, and thofe in 
 the neighbourhood of Efcapa, afford this fait 
 in abundance. The natives ufe it in the fufton 
 of copper ores. 
 
 The fecond kind of borax known in com- 
 merce comes from China. It is purer than the 
 
 preced- 
 
2*7 o The Hi ft ary and Purification of Borax** 
 
 preceding, and has the form of frnall plates 
 cryftallized upon oneof their furfaces, on which 
 the rudiments of pnfms may be perceived. 
 This borax is mixed with a white powder, 
 which appears to be of an argillaceous nature. 
 
 Thefe feveral kinds of borax have been puri- 
 fied at Venice for a long time, and afterwards in 
 Holland; but MefTrs. Laguiller refine itatpre- 
 fent in Paris : and this purified borax forms the 
 third kind which is met with in commerce. 
 
 In order to purify borax, nothing more is 
 neceffary than to clear it of the imdhious fub- 
 ifance which foils it, and impedes its folution. 
 
 Crude borax added to a folution' of mineral 
 alkali, is more completely diflblved,and may 
 be obtained of confiderable beauty by a firfl 
 cryftallization ; but it retains the alkali made 
 ufe of ; and borax, purified in this manner, 
 poiTeffes a greater proportion of alkali than in 
 its crude ftate. 
 
 The oily part of borax may be deftroyed by 
 calcination. By this treatment it becomes 
 more foluble, and may in fadl be purified in 
 this way/ But the method is attended with a 
 confiderable lofs, and is not fo advantageous as 
 might be imagined. - ' ' : 
 
 The mofb fimple method of purifying borax-,- 
 eonfifis in boiling it ftrongly, and for a long 
 
 time. 
 
271 
 
 The Properties of Borax, 
 
 time. This folution being filtrated, affords by 
 evaporation cryftals rather foul, which may be 
 purified by a fecond operation fimilar to the 
 foregoing. I have tried all thefe proceffes in 
 the large way ; and the latter appeared to me 
 to be the mod fimple. 
 
 Purified borax is white, tranfparent, and has 
 a Somewhat greafy appearance in its fracture. 
 
 It cryftallizes in hexahedral prifms, termi- 
 nated by trihedral and fometimes hexahedral 
 pyramids. 
 
 It has a ftyptic tafte. 
 
 It converts fyrup of violets to a green. 
 
 When borax is expofed to the fire, it Swells 
 up, the water of cry Utilization is difli pared in 
 the form of vapour; and the fait then becomes 
 converted into a porous, light, white, and opake 
 mafs, commonly called Calcined Borax. If the 
 fire be more ftrongly urged, it affumes a pafty 
 appearance, and is at length fufed into a trans- 
 parent glafs of agreenifh yellow colour. Solu- 
 ble in water ; and which lofes its transparency 
 by expofure to the air, in confequence of a white 
 effloreScence that forms upon its Surface. 
 
 ~ This fait requires eighteen times its weight of 
 water, at the temperature of fixty degrees of 
 Fahrenheit’s thermometer, to diffolve it. Boil- 
 ing water difTolves one-fixth of its weight. 
 
 • il- Barytes 
 
272 Habitudes of Borax . 
 
 Barytes and magnefia decompofe borax* 
 Lime-water precipitates the folution of this 
 fait; and if quick-lime be boiled with borax, 
 a fait of fparing folubility is formed, which is 
 the borate of lime. 
 
 Borax is ufed as an excellent flux in docimafi. 
 tic operations. It enters into the compofitionof 
 reducing fluxes, and is of the greatefl ule in 
 analyfes by the blow-pipe. It may be applied 
 with advantage in glafs manufactories ; for 
 when the fufion turns out bad, a fmall quan- 
 tity of borax re-eflablifhes it. It is more ef- 
 pecially ufed in foidering. It aflifts the fufion 
 of the folder, caufes it to flow, and keeps the 
 furface of the metals in a foft or clean flate, 
 which facilitates the operation. It is fcarcely 
 of any ufe in medicine. Sedative fait alone is 
 ufed by fome phyficians; afid its name fuffici- 
 ently indicates its application. 
 
 Borax has the inconvenience of fwelling up, 
 and requires the greatefl: attention on the part 
 of the artift who ufes it in delicate works, more 
 efpecially when defigns are formed with gold 
 of different colours. It has been long a defi- 
 deratum to fubftitute fome compofition in the 
 room of borax, which might poffefs its advan- 
 tages without its defeefls. 
 
 Mr. Georgi has publifhed the following pro- 
 
 3 cefs : •' 
 
/ 
 
 Bo rate of Ammoniac . 273 
 
 cefs : — cf Natron, mixed with marine fait and 
 Glauber’s fait, is to be dilfolved in lime-water; 
 and the cryftals which feparate by the cooling 
 of the fluid may be fet apart. The lixivium 
 of natron is then to be evaporated ; and this 
 fait afterwards dilfolved in milk. ' The evapo- 
 ration affords fcarcely one-eighth of the natron 
 employed, and the relidue may be applied to 
 the fame ufes as borax.” 
 
 Melfrs. Struve and Exchaquet have proved 
 that the phofphate of pot-alh, fufed with a cer- 
 tain quantity of fulphate of lime, forms an ex- 
 cellent glafs for foldering metals. — See the 
 Journal dePhylique, t. xxix. p. 78, 79. 
 
 * ARTICLE III. 
 
 Borate of Ammoniac. 
 
 This fait is ftill little known. We are indebt- 
 ed to Mr. De Fourcroy for the following indi- 
 cations: — He dilfolved the acid of borax in 
 ammoniac, and obtained by evaporation a bed 
 or plate of cryftals conne&ed together, whofe 
 furface exhibited polyhedral pyramids. This 
 fait has a penetrating and urinous tafte ; it 
 renders the fyrup of violets green ; gradually 
 lofes its cryftalline form, and becomes of a 
 Vol. I. T brown 
 
2 74 Examination of 
 
 brown colour, by the contad of air. It ap- 
 pears to be of confiderable folubility in water* 
 Lime difengages the volatile alkali. 
 
 no;: - .... v • ,[ n* 
 
 Concerning Mineral Waters*. 
 
 T HE name of Mineral Water is given to 
 any water whatever which is fufficiently 
 loaded with foreign principles to produce an 
 effed upon the human body, different from 
 that which is produced by the waters com- 
 monly ufed for drink. 
 
 Men, doubtlefs, were not long in attending 
 to the differences of waters. Our anceftors ap- 
 pear even to have been more ftridly attentive 
 than ourfelves to procure wholefome drink. It 
 w as almoft always the nature of the water which 
 
 . * As mineral waters bear relation to every part of chemif- 
 
 r Y •) * * r 
 
 try, their analvfes may be indifferently placed at the end cf 
 any one of the parts. But as the nature of the principles they 
 contain fuppofe an . acquaintance with the produds of the 
 three kingdoms, it is more natural to referve the ar tide of 
 jhe mineral waters for the conclufion of a courfe of chemif- 
 try. I have thought proper to change this order for no other 
 'reafon, than becaufe I forefaw that the third volume of this 
 •work would be of too large a fize even without it. 
 r* . t deter- 
 
Mineral- Waters . 
 
 *7S 
 
 determined their, preference in the frtuatior* of 
 towns,' the chpice-of habitations, aodr confer 
 qutntly the union of; citizens. The fo>eU, the 
 tafte^and more efpecially the effeiks of waters 
 upon the animal economy, have^been ; thought 
 fufficient, during a long time, ;tq djetermine 
 their nature. VVe may fee, in thefwrkings of 
 HippojCfatqs, how much obfervation and genius 
 are capable of performing in fubjedh of this 
 nature. This great man, of whom it would^af- 
 ford but a very imperfedl -idea to confiderhim 
 merely as the Father of Medicine, was fo well 
 acquainted with the influence of water upon 
 the human body, -that he affirms that the mere 
 quality of their ufual drink is capable of mo- 
 difying and producing, a difference between 
 men ; and he recommends to young phyiicians 
 to attend more particularly to the nature of the 
 waters their patients ought to ufe. We fee that 
 the Romans, who were frequently under the 
 nec^flity of fettling in parched climates, fpared 
 no exertions to procure wholefome water to 
 their colonies. The famous aquedudf which 
 carried the water of Uzes to Nifmes, is an un- 
 equivocal proof of this; and we flill poffes fe- 
 veral mineral fprings at which they formed cq- 
 lonies, for the advantage of the baths.. 
 
 It was not till near the feventeenth century 
 T 2 that 
 
27 6 Examination of 
 
 that the application of chemical methods to 
 the examination of waters was firft made. We 
 are indebted to the prefent revolution of che- 
 miftry for the degree of perfection to which 
 this analyfis has been carried. 
 
 The analyfis of waters appears to me to be 
 neceffary, in order — 
 
 1. That we may not make ufe of any water 
 for drink but fuch as is wholefome. 
 
 2. That we may become acquainted with 
 thofe which poffefs medicinal virtues, and ap r 
 ply them to the ufes to which they are fuited. 
 
 3. To appropriate to the different works or 
 manufactories that kind of water which is the 
 belt calculated for their refpeCtive purpofes. 
 
 4. To correCt impure waters, or fuch as are 
 either impregnated with any noxious princi- 
 ple, or charged with any fait. 
 
 5. To imitate the known mineral waters, in 
 all places and at all times. 
 
 The analyfis of mineral waters is one of the 
 moft difficult problems of chemiftry. In order 
 to make a perfect analyfis, it is neceffary to be 
 aware of all the difiinCtive characters of the fub- 
 ftances which may be held in folution in any 
 water. The operator mufi be acquainted with 
 the means of feparating from an almoft infenfi- 
 
 ble 
 
Mineral Waters • 277 
 
 ble refidue the different fubftances which com- 
 pofe it. He muft be able to appreciate the na- 
 ture and quantity of the produdts which arc 
 carried off by evaporation ; and likewife to 
 afcertain whether certain compounds are not 
 formed by the operations of his analyfis, while# 
 others may be decompofed. 
 
 The fubftances contained in waters are held 
 either in fufpenfton or in folution. 
 
 1. Thofe fubftances which are capable of 
 being fufpended in waters are, clay, ftlex in 
 a ftate of divifion, calcareous earth, magne- 
 fia, &c. 
 
 Thofe which are foluble are, pure air, the 
 carbonic acid, pure or compound alkalis, lime, 
 magnefia, the fulphates, the muriates, the ex- 
 tradive matter of plants, hepatic gas, &c. The 
 moft ancient, the moft general, and the mod 
 ftmple divifion of mineral waters, is that which 
 diftinguifhes them into cold waters and hot or 
 thermal waters, accordingly as their temperature 
 is the fame, or exceeds that of common water. 
 
 A divifion founded on the feveral qualities of 
 thefe waters, will arrange them in four claffes. 
 
 I. Acidulous or Gafeous Waters. — Thefe are 
 known by their penetrating tafte ; the facility 
 with which they boil ; the difengagement of 
 
 bubbles 
 
278 Examination of 
 
 bubbles by fimple agitation, or even by mere 
 ftajiding; the property of reddening the tindlure 
 fcf turnfole; the precipitating lime-water, &c. 
 
 They are either cold or h6t. The fir fb are 
 thofe bf Selfz, of Chateldon, of Vais, of Perols, 
 •&c. The fiecond are thofe of Vichi, of Mont- 
 d’or, of Chatelguyon, &c. 
 
 II. Saline waters, properly fo called.— Thefe 
 are charadterifed by their faline taffe, which is 
 modified according to the nature of the falts 
 they contain. The falts moft generally found 
 in waters tire, the muriate of magnefia, the ful- 
 phates of foda, of lime, &c. Our waters of 
 Balaruc, of Yeufet, &c: are of this nature. 
 
 III. Sulphureous Waters. — Thefe waters 
 have long "been confidered as holding fulphur 
 in folution. Meffrs. Vend and Monnet oppo- 
 fed this affertion. Bergmann has proved that 
 moft of thefe waters are merely impregnated 
 with hepatic gas. It appears, however, that 
 there are fame which' hold true liver of ful- 
 phur in folution, fuch as thofe of Bareges and 
 of Cotteret ; whereas the waters of Aix laCha- 
 pelle, Montmorency, &c. are of the nature of 
 thofe mentioned by Bergmann. We may, with 
 Mr. De Fourcroy, call the firft by the name of 
 Hepatic Waters, and the latter by ‘the name of 
 Ilepat'ized Waters. 
 
 This 
 
Mineral Waters . 279 
 
 This clafs is known by the fmell of rotten 
 eggs which they emit. 
 
 IV. Martial Waters. — Thefe have the pro- 
 perty of exhibiting a blue colour by the folu- 
 tion of pruffiate of lime they have befides a 
 very evident aftringent tafte. The iron is held 
 in folution either by the carbonic or the ful- 
 phuric acid . In the firfl cafe the acid is either 
 in excefs, and the water has a penetrating fiib- 
 acid. taite, as the waters of Buifang, Spa, Pyr- 
 mont, Pougue,&c. : or the acid is not in excefs, 
 and confequently the waters are not acidulous; 
 fuch are the waters of Forges, Conde, Aumale, 
 &c. Sometimes the iron is combined with the 
 fulphuric acid, and the water holds in folution 
 a true fulphate of iron. Mr. Opoix admits 
 this fait in the waters of Provins ; and thofe of 
 Rouo;ne near Alais are almoft faturated with 
 it. Mineral waters of this quality are fre- 
 quently found in the vicinity of ftrata of py- 
 rites. There are feveral near Amalou, and in 
 the diocefe of Uzes. 
 
 There are fome waters which may be placed 
 indiferiminately in feveral of the claffes. Thus, 
 for example, there are faline waters which may 
 be confounded with gafeous waters, becaufe 
 air is con ftantly defengaged from them. The 
 waters of Balaruc are of this kind. 
 
 We do not comprehend among mineral 
 
 . waters 
 
Examination of 
 
 waters thofe which fuffer gas to efcape through 
 them, without communicating any charadter- 
 iftic property ; fuch as the burning fpring of 
 Dauphiny, &c. 
 
 When the nature of any water is afcertained, 
 its analyfis may be proceeded upon by the 
 union of chemical and phyfical means. I call 
 thofe methods phyfical, which are ufed to af- 
 certain certain properties of water without de- 
 eompofing them. Thefe methods are, for the 
 moft part, fuch as may be carried into effect at 
 the fpring itfelf. The appearance, the fmell, 
 and the tafte afford indications by no means to 
 be negledled. 
 
 The limpidity of any water indicates its pu- 
 rity, or at lead the accurate folution of the fo- 
 reign principles it may contain ; an imperfedt 
 tranfparency denotes that foreign fubftances 
 are fufpended. Good water has no fmell: the 
 fmell of rotten eggs denotes liver of fulphur, 
 or hepatic gas; a fubtle and penetrating fmell 
 is proper to acidulous waters ; and a fetid fmell 
 charadterizes fagnant waters. 
 
 The bitternefs of waters in general depends 
 on neutral fairs. Lime, and the fulphates, 
 give them an auffere tafte. 
 
 It is like wife of importance to afcertain the 
 fpecific gravity of the water, which may be 
 done either by means of the areometer, or by 
 
 the 
 
Mineral Waters. 281 
 
 the companion of its weight with that of an 
 equal volume of diftilled water. 
 
 The degree of heat mu ft likewife be taken 
 by means of a good mercurial thermometer. 
 Thermometers made with fpirits of wine ought 
 to be rejected ; becaufe the dilatation after the 
 thirty-fecond degree of Reaumur, is extreme, 
 and no longer correfponds with the tempera- 
 ture of the water. It is interefting to calculate 
 the time which the water requires to become 
 cool, in comparifon with diftilled water raifed 
 to the fame degree of temperature. Notice 
 muft likewife be taken whether any fubftance 
 exhales, or is precipitated by the cooling. 
 
 The obferver ought likewife to enquire whe- 
 ther rains, dry feafons, or other variations of the 
 atmofphere, have any influence on the tempera- 
 ture or quantity of water of the fpring. If thefe 
 caufesa£t upon the fpring, its virtue cannot but 
 vary exceedingly. This is the caufe why cer- 
 tain mineral waters are more highly charged with 
 their principles in one year than in another 5 and 
 hence alfo it arifes that certain waters produce 
 wonderful effects in fome years, though in other 
 feafons their effedls are trifling. The celebrate 
 ed De Haen, who analyfed for fcveral fucceftive 
 years all the waters in the neighbourhood of 
 Vienna, never found them to contain the fame 
 
 principles 
 
282 
 
 Examination of 
 
 principles in the fame proportion. It would 
 therefore be an intereifing Circ urn fiance, if, at 
 the time of taking up or bottling of thefe wa- 
 ters, a fkilful phyiician were to analyfe them, 
 and publilh the refult. 
 
 After thefe preliminary examinations have 
 been made at the fpring, further experiments 
 muff be made according to the methods of che.- 
 miftry. Thefe experiments ought to be pc 
 formed at the fpring itfelf: but if this cannot be 
 done, new bottles maybe filled with the water ; 
 and, after, doling them very accurately, they 
 may be carried to the laboratory of the chemift, 
 who muff proceed to examine them by re- 
 agents, and by the method of analyfis. 
 
 1. The fubftances contained in water are de- 
 compofed by means of re-agents ; and the new 
 combinations or precipitates which are formed, 
 immediately point out the nature of the prin- 
 ciples contained in the waters. The mo ft effi- 
 cacious and the only necelfary re-agents are the 
 following : 
 
 3. Tin 8: ur.e of turnfole becomes red by its 
 mixture with acidulous waters. 
 
 2. Pruffiate of lime, and that of ferruginous 
 pot-afh not faturated, precipitate the iron con- 
 tained in a mineral water of a blue colour. 
 
 3. The very concentrated fulphuric acid de- 
 
 3 compofes 
 
. 'Mineral Waters . 
 
 2§3 
 
 eompofes moft neutral fairs ; and forms with 
 their bafes falts very well known, and eafily 
 diftinguifhed. 
 
 4. The oxalic acid, or acid of fugar, difen-. 
 gages lime from all its combinations, and forms 
 with it an infoluble fait. 
 
 The oxalate of ammoniac produces a more 
 fpeedy effect ; for, by adding a few cryftals of 
 this fait to water charged with any calcareous 
 fait, an infoluble precipitate is inftantly formed. 
 
 5. Ammoniac or volatile alkali affords a 
 beautiful blue colour with thefolutions of cop- 
 per. When this alkali is very pure, it does not 
 precipitate the calcareous fait, but decompofes 
 the magnefian only. In order to have it in a 
 highly cauftic Itate, a fyphon may be plunged 
 in the mineral water, and ammoniacal gas or 
 alkaline air paffed through it. The water ought 
 to be kept from the contact of the atmofphere, 
 which otherwife might occafion a precipitation 
 by virtue of its carbonic acid. 
 
 6. Lime water precipitates magnefia ; and 
 it likewife precipitates the iron from a folution 
 of fulphate of iron. 
 
 7. The muriate of barytes detedls the fmall- 
 eft particle of fulphuric falts, by the regene- 
 ration of ponderous fpar, which is infoluble, 
 and falls down. 
 
 8. Alco- 
 
284 
 
 Examination of 
 
 8. Alcohol is a good re-agent, on account 
 of its affinity with water. 
 
 The nitrates of filver and of mercury may 
 likewife be employed to decompofe fulphuric 
 or muriatic fal.ts. 
 
 II. Thefe re-agents, indeed, point out the 
 nature of the fubftances contained in any water; 
 but they do not exhibit their accurate propor- 
 tions. For this purpofe we are obliged to have 
 recourfeto other means. 
 
 There are two things to be conlidered in the 
 analyfis of any water — i. The volatile princi- 
 ples. 2 . The fixed principles. 
 
 i. The volatile principles are carbonic acid 
 gas and hepatic gas. The proportion of car- 
 bonic acid may be afcertained by various pro- 
 cefTes. The firft, which has been ufed by Mr. 
 Venel, confifts in half filling a bottle with the 
 gafeous water intended to be analyfed. A 
 bladder is then to be tied upon the neck of the 
 bottle, and the water agitated. The air w hich 
 isdifengaged inflates the bladder; and by that 
 indication an eftimate may be made of its quan- 
 tity. This procefs is not accurate; becaufe agi- 
 tation is not fufficient to difengage the whole 
 of the carbonic acid. Neither is the evapora- 
 tion of the w^ater in the pneumato-chemical 
 apparatus much more exact; becaufe the wa- 
 ter 
 
Mineral Waters • 
 
 285 
 
 ter which rifes with the air combines again with 
 it, and the gafeous product conlifts only of a 
 part of the gas contained in the water. The 
 precipitation by lime-water appears to me to 
 be the moft accurate procefs. Lime-water is 
 poured into a determinate quantity of the wa- 
 ter, until it ceafes to caufe any precipitate,, 
 This precipitate being very accurately weighed, 
 •H parts of the whole muft be deducted for the 
 proportion in which water and earth enter in- 
 to it; and the remainder is the acid contained 
 in this carbonate of lime. 
 
 Hepatic gas may be precipitated by the very 
 concentrated nitric acid, according to the ex- 
 periments of Bergmann. 
 
 The oxigenated muriatic acid has been pro- 
 pofed by Scheele; and Mr. De Fourcroy has 
 pointed out the fulphureous acid, the oxides of 
 lead, and other re-agents, to precipitate the 
 fmall quantity of fulphur held in folution in 
 hepatic gas. 
 
 2. Evaporation is commonly ufed to afeer- 
 tain the nature of the fixed principles contained 
 in any mineral water. VefTels of earth or porce- 
 lain are the only kind fuitable to this purpofe. 
 
 The evaporation muft be moderate ; for 
 ftrong ebullition volatilizes fome fubftances, 
 and decompofes others. In proportion as the 
 
 evaporation 
 
2S6 
 
 Examination of 
 
 evaporation proceeds, precipitates are afforded; 
 which Mr. Boulduc propofes to take out as 
 they are formed. The celebrated Bergmann 
 advifes evaporation to drynefs, and to analyfe 
 the refidue in the following manner: . v 
 
 1. This refidue mull be put into a fmall 
 phial, and flrongly agitated with alcohol; af- 
 ter which the fluid mull be filtrated. 
 
 2. Upon the refidue pour eight times its 
 weight of cold diddled water; agitate this, and 
 filter the fluid, after (landing fey era! hours. 
 
 3. Laftly, the refidue mult be boiled for a 
 
 quarter of an hour in five or fix hundred parts 
 of diftilled water, which fluid mull be feparated 
 by filtration. j 
 
 4. The refidue, which is neither foluble in 
 water nor in alcohol, mull then be moiftened, 
 and expofed for feveral days to the fun,: by this 
 treatment, the iron which it may contain, rufts. 
 It mult then be digelled in diftilled vinegar, 
 which diflolves lime and magnefia; and this fo- 
 lution, evaporated to drynefs, affords either an 
 ^arthy fait in filaments which are notdeliquef- 
 cent, ora deliquefcent fait; which laft has mag- 
 nefia for its bafe. The infoluble refidue con- 
 tains iron and clay, which are to be diffolved 
 in the muriatic acid. The iron is firll to be 
 
 precipi- 
 
Mineral Waters. 287 
 
 precipitated by the pruffiate of lime; and af- 
 terwards the clay by another alkali. 
 
 • The falts which the alcohol has diffolved, are 
 the Muriates of magnefia and of lime. They 
 are eafdy known by decompofing them by the 
 fulphuric acid. 
 
 With refped to the falts diffolved in the cold 
 w r ater, they maft be (lowly cryflallized ; and 
 their form, and other obvious qualities, will 
 fhevv what they are. 
 
 The folution by boiling water contains no- 
 thing but fulphate of lime. 
 
 When the analyfis of.any water has been well 
 made, the fy nthefis becomes eafy; and the 
 compofition or perfed imitation of mineral 
 waters is no longer a problem infoluble to che- 
 mifts. What, in fad, is a mineral water? It is 
 rain water, which, filtering through the moun- 
 tains, becomes impregnated w r ith the various 
 foluble principles it meets with. Why, there- 
 fore, when once we know the nature of thefe 
 principles, can it not be pofiible to dilTolve them 
 in common water, and to do that which nature 
 itfelf does ? Nature is inimitable only in its 
 vital operations; we may imitate its effeds 
 perfedlyin all other proceffes: we may even 
 do better; for we can at pleafure vary the tem- 
 perature and the proportions of the conftitu- 
 
288 Examination of Mineral Waters. 
 
 ent parts. The machine of Nooth, improved 
 by Parker, may be made ufe of to compofe 
 any gafeous mineral water, whether acidulous 
 or hepatic,* and nothing is more eafy than to 
 imitate fuch waters as contain only fixed prin- 
 ciples. 
 
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