fornial 
 lal 
 
 y
 
 THE LIBRARY 
 
 OF 
 THE UNIVERSITY 
 
 OF CALIFORNIA 
 LOS ANGELLS 
 

 
 ELEMENTS 
 
 OF THE 
 
 
 THEORY of CHYMISTRY
 
 EL EM 
 
 O F T H E 
 
 Theory and Pra&ice 
 
 O F 
 
 C H Y M I S T R Y. 
 
 TRANSLATED 
 
 From the French of M. MACQJJER, 
 
 Member of the Royal Academy of Sciences, and Pro- 
 feflbr of Medicine in the Univerfity of Paris. 
 
 IN TWO VOLUMES. 
 VOL. I. 
 
 THE THIRD EDITION. 
 
 LONDON, 
 
 Printed for J. N o u R s E, W. S T R A H A N, 
 
 J. and F. RIVINGTON, T. LONGMAN, 
 
 T. CAD ELL, and E. JOHNSTON. 
 
 MDCCLXXV.
 
 TO THE 
 
 i 7 7 
 RIGHT HONOURA BL E 
 
 THE 
 
 Earl of BUTE, 
 
 My LOR D, 
 
 THIS Tranflation of M. MACQUER'S 
 celebratedELEMENTsofCnYMisTRY 
 was undertaken with the fole View of ren- 
 dering fome fmall Service to my Country; 
 as I hoped it might contribute both to re- 
 commend and to facilitate the Study of a 
 SCIENCE, which, though more entertaining^ 
 inftructive, and extenfively ufeful than any 
 other, hath of late been too much neglected 
 in this Ifland. 
 
 A 3 I think 
 
 1. .
 
 DEDICATION. 
 
 I think myfelf very happy in feeing this 
 Defign approved of, and its Succefs in a 
 manner aflured, by the Honour which 
 YOUR LORDSHIP hath been pleafed to do me, 
 in condefcending to take it under your Pro- 
 tcdtion. 
 
 I am, with the utmoft Refpedl, 
 MY LORD, 
 
 YOUR LORDSHIP'S 
 
 moft Obedient 
 
 and moft Humble Servant 
 
 London, 
 March 251 1758. 
 
 ANDREW REID.
 
 THE 
 
 AUTHOR'S 
 
 PREFACE. 
 
 AN hundred and fifty years are fcarce elapfed 
 fince the clouds of prejudice, which had 
 long overfpread the world, began to clear up, 
 and men were convinced, by cultivating the Scien- 
 ces and attending to Nature, that no fanciful hy- 
 pothefes would ever le'ad them to the true caufes 
 of thofe various phenomena that incefiantly and 
 every where meet the obferver's eye ; but that the 
 narrow limits of the human understanding: confine 
 
 O 
 
 the courfe of our relearches to one fingie path; 
 namely, that of Experiment, or the Uie of our 
 Senfes. Yet, in this fhort period, Natural Philofo- 
 phy hathrifen to a high pitch of improvement, and 
 may with truth be faid to have made much greater 
 advances towards perfection, fince the experimental 
 method was introduced, than in the many ages 
 before. 
 
 This is true with regard to every branch of Na- 
 tural Philofophy ; but more particularly with re- 
 gard to Chymiftry. Though this Science cannot 
 be faid to have ever exifted without experiments, 
 yet it laboured under the ftme difadvantages with 
 the reft; becaufe thofe who lludied it made all 
 their experiments with a view to confirm their own 
 Hypothefes, and in conftquence of principles whicli 
 had no foundation whatever, but in their wild ima- 
 ginations. 
 
 A 4 Hence
 
 viii PREFACE. 
 
 Hence arofe that enormous heap, that inconp/n- 
 ous jumble of facts, which fome time ago a,- ..i- 
 tuted all the knowledge of Chymifts. Moft of 
 them, and efpeciaily thofe who afiumed the pom- 
 pous title of Alchymifts, were perfuaded that all 
 the Metals were no other than Nature's rude unfi- 
 nilhed efTays towards making Gold ; which, by 
 means of due ccclion in the bowels of the earth, 
 advanced gradually towards maturity, till at laft 
 they were perfectly converted into that beautiful 
 and precious Metal. 
 
 On this principle, which, if not demonftrably 
 fahc, is at leaft utterly dtftitute of proof, and un- 
 fupportcd by a fingle obicrvatton, they attempted 
 to fi .\ature had begun, by procuring to 
 
 the ..Is this much defired coction. 
 
 To attain it they mafic an infinite number of expe- 
 riments and tiialsj \vhichail confpired to detect 
 falfity of their fyftem, and to fatisfy men of 
 fenfe, that the methods they employed were very 
 far from anfwcring thepurpofe. 
 
 Hov.ever, as facts always promote the know- 
 
 ;j,e of Nature, it happened that thofe experi- 
 
 nts, though quite uieltls with regard to the end 
 for which they were originally made, proved the 
 
 afion of feveral curious dilcoveries. 
 
 Thefe lucky coniequences of their miftaken la- 
 bours raited the courage of the Chymifts, or ra- 
 ther Alchyrnifts, who looked upon every fuch in- 
 ftance of fuccei-> as a new ftcp towards the Grand 
 
 >j;k, and greatly increafed the fond opinion they 
 
 ined of themlelves, and of their Art, which 
 
 on that account they fet up very high above all 
 
 other Sciences. Nay, they carried this notion of 
 
 Superiority Ib far, as to hold the reit of mankind 
 
 unworthy, or incapable, of rifing to Juch fubiime 
 
 knowledge. In confequence thereof Chymiftry 
 
 became an occult and rr.yilcrious Science ; its ex- 
 
 g preflions
 
 PREFACE. is 
 
 preffions were all tropes and figures, its phrafes 
 metaphorical, and its axioms fo many enigmas : 
 in fhort, an obfcure unintelligible jargon is the 
 julttft character of the Alchymiftic language. 
 
 Thus, by endeavouring to conceal their fecrets., 
 thofe gentlemen rendered their art ufelefs to man- 
 kind, and brought it into deferved contempt. But 
 at length the genius of true Philofophy prevailed in 
 Chymiftry, as well as in the other fciences. Some 
 great men arofe, who had generofuy enough to 
 think their knowledge no otherways valuable than 
 as it proved of fervice to Society, They did their 
 iHmoil to introduce both the knowledge and the 
 practice of many important fecrers, till then of no 
 ufe-, they drew afide the veil which hid thechanm 
 of Chymiftry ; and that Science emerging from the 
 profound oblcurity, in which it had for many ages 
 lain concealed, gained the admiration of the world 
 as foon as it appeared in open day. Several focie- 
 ties of ingenious men were formed in the moft 
 learned countries of Europe, who vied with one 
 another in their labours to execute the noble 
 fcheme, and aOjfled each other by mutually com- 
 municating their discoveries. Chymiftry made the 
 mod rapid progrefs, enriching and perfecting the 
 Arts derived from, or depending on it. x In a 
 word, it put on a new face, and became truly wor- 
 thy of the title of .Science -, founding its principles 
 and its proceffes on folid experiments, and on juft 
 confequences deduced from them. 
 
 Since that time the Art is become fo exteniive, 
 by the numerous difcovtrics which Chymifts 
 have already made, and are daily making, thac 
 large volumes are required to contain a complete 
 Treatife on the fubjcct. In mort, Chymiftry may 
 now, in fome degree, be compared to Geometry r 
 each of thefe Sciences takes in a moft ample field 
 
 of
 
 x PREFACE. 
 
 of enquiry, which every day enlarges very confi- 
 derably ; from each are derived feveral Arts, not 
 only uieful but even neceflary to Society ; each 
 hath its Axioms and its undeniable principles, ei- 
 ther demonftrated from internal evidence, or 
 founded on conftant experience j fo that the one, 
 as well as the other, may be reduced to certain fun- 
 damental truths, on which all the reft are built. 
 Thefe fundamental truths connected together, and 
 laid down with order and precision, form whan we 
 call the Elements of a Science. It is well known 
 that there are many luch works relating to Geo- 
 metry, but it is not fo with regard to Chymiftry ; 
 there being very few books which treat of this 
 Science in an Elementary manner. 
 
 Yet it mult be owned that performances of this 
 kind are exceedingly ufcful. Many who have a 
 relifh for the Sciences, but have not leifure to read 
 elaborate Works which treat of them minutely, 
 are glad to meet with a book from which, without 
 facrin'cing too much of their tiir.e, or neglecting 
 their ordinary bufinefs, they may obtain a tafte or 
 juft notion of a Science that is not their principal 
 ftudy. Thole who incline to-go further, and learn 
 more, may, by reading an Elementary tract, be 
 enabled to underftand Authors who, as they com- 
 monly write only fcr proficients in the Art, are 
 oblcure and hardly intelligible to mere beginners. 
 Nay, I prclume to fay that an Elementary Treatife 
 of Chymiftry may prove a very ufeful book, even 
 to thofe who have made fome progrels in the Sci- 
 ence : for as it contains only the iundamental pro- 
 pofitions, and indeed is an abttradt of the whole 
 Art, it may help them to recollect the moft im- 
 portant parts of what they have read in many dif- 
 ferent works, and fix in their memories the moft 
 efiential truths, which might elfc be either con- 
 founded with others, orcn::rely forgot. And thefe 
 
 are
 
 XI 
 
 are the motives which determined me to compofe 
 the Work which I now offer to the Publick. 
 
 The general Plan on which I proceed is to fup- 
 pofe my Reader an abfolute Novice in Chymiftry ; 
 to lead him from the moft fimple truths, and fuch 
 as imply the loweft degree of knowledge, to fuch 
 as are more complex, and require a greater ac- 
 quaintance with Nature. This order, which I 
 have laid down for my rule, hath obliged me to 
 begin with examining the moft fimple iubftances 
 that we know, and which we confider as the ele- 
 ments whereof others are compoied ; as, by know- 
 ing the properties of thefe elementary parts, we are 
 naturally led to thofe of their feveral combinations ; 
 and on the other hand, in order to know the pro- 
 perties of compound bodies, it is neceffary we 
 mould be firft acquainted with the properties of 
 their principles. The fame reafon induced me, 
 when enquiring into the properties of one fubftance, 
 to take no notice of thofe which relate to any other 
 fubftance not treated of before. For example : as 
 I treat of Acids before Metals, I fay nothing un- 
 der the head of thofe Acids concerning their power 
 of diffolving Metals : that I defer till I come to 
 the fubjecl: of Metals : and thus I avoid fpeaking 
 prematurely of a fubftance with which I fuppofe 
 my Reader wholly unacquainted. And this me- 
 thod I was fo much the more eafily induced to fol- 
 low, that I know of no Chymical book written on 
 the fame Plan. 
 
 After difcourfing of Elements in general, I treat 
 next of fuch fubftances as ar immediately com- 
 pofed of them, and are, next to them, the moft 
 limple : fuch are all ialine fubftances. This head 
 comprehends mineral A-cids, fixed Alkalis, and 
 their feveral combinations : the volatile lulphureous 
 fpirit, fulphur, phofphorus, and the Neutral falts 
 which have an earth or fixed Alkali for their bafis : 
 6 thofe
 
 PREFACE. 
 
 thofe which have for their bafis cither a volatile 
 Alkali, or fome metallic fubftance, are referred, 
 according to my general Plan, to the heads under 
 which I treat or thofe lubftances. 
 
 Metallic fubftances are fcarcely more compound- 
 ed than the faline-, which induces me to confider 
 them next. I begin with thole which are the mod 
 fimple, or.at Itail feem to be fo , becaule their prin- 
 ciples, being very itrongly connected together, arc 
 feparated with the greatcft difficulty : fuch are the 
 Metals properly fo called ; namely Gold, Silver, 
 Copper, Iron, Tin, and Lead. After thele come 
 the Semi-metals in order ; to wit, Regulus of 
 Antimony, Zinc, Bifmuth, and Regulus of Ar- 
 fenic. Mercury being a doubtful fubftance, which 
 fome Chymifts rank with the Metals* and others 
 with the Scmi-mecals, becaufe it actually poffeflcs 
 certain properties in common with each, I have 
 treated of it in a feparate Chapter, which ftands 
 between the Metals and Semi-metals. 
 
 I next proceed to examine the fcveral forts of 
 Oils, whether Vegetable, which are divided into 
 fat, efiential, and cmpyreumatic j or Animal, and 
 Mineral Oils. 
 
 By examining thefc fubftances we obtain ideas of 
 all the principles which enter into the competition 
 of Vegetable and Animal bodies ; that is, of thofe 
 fubftances that are capable of fermentation : this 
 enables me to treat or fermentation in general; of 
 its three different degrees or kinds, the fpirituous, 
 acetous, and putrid ; and of the produces of thofe 
 fermentations, ardent fpirits, acids analogous to 
 thofe of vegetables and animals, and volatile alkalis. 
 
 The order in which I treat of all thofe fubftances 
 being different from that in which they are obtained 
 from compound bodies, I give, in a diftinct chap- 
 ter, a general Idea of Chymical Decompofition* 
 with a view to fiiew the order in which they arc 
 
 feparated
 
 feparated, from the feveral bodies in the compofi- 
 tion whereof they are found. This brings them 
 a fecond time under review, and gives me an op- 
 portunity of diftinguilhing thofe which exift natu- 
 rally in compound bodies, from thofe which are 
 only the refult of a new combination of fome of 
 their principles produced by the fire. 
 
 The fucceeding Chapter explains the late Mr. 
 Geoffroy's Table of Affinicies ; which I take to be 
 of great ufe at the end of an Elementary Tract like 
 this, as it collects into one point of view the molt 
 efiential and fundamental doctrines which are dil- 
 perfed through the work, 
 
 I conclude with an account of the Conftruction 
 of fuch Veflels and Furnaces as are ufually em- 
 ployed in Chymiftry. 
 
 In this Part I fay nothing of any manual opera- 
 tions, or the feveral ways of performing Chymicai 
 procefles j referving thefe particulars for my Trea- 
 tife of Practical Chymiftry, to which this muft be 
 confidered as an Introduction. 
 
 CON-
 
 C ON T EN T S 
 
 OF VOL. I. 
 
 Elements of the THEORY of Chymiftry. 
 
 CHAP. I. 
 
 OF the Principles of Bodies page I- 
 
 i. OfA,r 3. 
 
 2. Of Water 4. 
 
 3. Of Earth 5. 
 
 4 Of Fire 7. 
 
 5. Of the Phlogifton g. 
 
 CHAP. II. A general View of the Relations or Affinities 
 
 between Bcdies j i. 
 
 CHAP. III. Of Saline Sub/lances in general 14; 
 
 i. Of Acids 15. 
 
 2. Of Alkalis 18. 
 
 3. Of Neutral Salts j. 
 CHAP. IV. Of the feveral Sorts of Saline Sub/lances. 
 
 i. Of the Univerfal Acid 23. 
 
 2. Of the Nitrous Acid 28. 
 
 3. Of the Marine Acid 32. 
 
 CHAP. V. Of Lime 38. 
 
 c H A P . V I . Of Metallic Sub/lances in general 45. 
 
 CHAP. VII. Of Metals 49. 
 
 i. Of Gold it. 
 
 2. Of Silver 52. 
 
 3. Of Copper 59. 
 
 4. Of Iron 63. 
 
 5. Of Tin 69. 
 
 6. Of Lead 71. 
 
 CHAP. VIII. Of ^ui^-Silver 77. 
 CHAP. IX. Of the Semi-Metals. 
 
 i. Of Re^ulus of Antimony 83. 
 
 2. Of Bifmuth 92. 
 
 3. Of Zinc 93. 
 
 4. Of Regulus of Arfenic 96. 
 
 CHAP. X. Of Oil in general ioi. 
 
 i. Of Charcoal 102. 
 
 2. Of Soap 104. 
 
 CHAP.
 
 rvi CONTENT S, 
 
 ?. XI. Ofthtffveral Sorts of Oils. 
 
 I. Of Mineral Oils page 105. 
 
 2. Of Vegetable Oils 106. 
 
 3. Of Animal Oils 109. 
 
 CHAP. XII. Of Per me ntatlon in reneral Iio. 
 
 CHAP. XIII. Of t'. c Spirituous Fcrntentatitn III. 
 
 CHAP. XIV. Of the Attttui Fermentation 120. 
 
 <s i. Of Vinegar 121. 
 
 2. Of Tartar I2t. 
 
 p. XV Of the Putrid Fermentation, er Pt,tref t i,3ion 12*. 
 
 p. XVI. A general flew of Ckymkal Decotnpofi- 
 
 thn 135. 
 
 i. The Analyfis cf Vegetable Subflanccs 156. 
 
 Emulfions I^g. 
 
 2. The Analyfis of Animal Subftances 142. 
 
 ^ 3. The Analyfis of Mineral Subilances 144. 
 
 Of the Pyrites 147. 
 
 Of Ores 149. 
 
 CHAP. XV II. Explanation cf the Table of JJfinitits 159. 
 
 CHAP. XVIII. The Theory of Conjlr fitting the Vijjtli 
 
 :mly ttffd in Chymiflry 168. 
 
 IX. The Theory tf can/huffing the Farnates mojl 
 
 eommonly ufed in Cbjm'ijlrj. j - b' . 
 
 OfLu::s 197. 
 
 Elements of the PRACTICE of Ckymiftry. 
 
 Introdudion p. 2Di 
 
 PART I. OF MINERALS. 
 SECTION I. 
 
 Operations performed on Saline Mineral Subflance*. 
 CHAP. I. Of the Vitriolic Acid. 
 
 1. PROCESS. To extract Vitriol from the Pyrites aio. 
 
 2. To extract Sulphur from the Pyrites, and other ful- 
 phoreous Minerals 214. 
 
 3. To cxtraft Alum from a'uminous Minerals 2j8. 
 
 4. To extract the Vitriolic Acid from Copperas or 
 Green Vitriol 225. 
 
 5. To dcccmpofe Sulphur, and extraft its Acid, by 
 burning it 230. 
 
 6. To
 
 CONTENTS. xvii 
 
 6. To concentrate the Vitriolic Acid 233. 
 
 7. To decompound Vitriolated Tartar by means of the 
 Phlogifton ; or to compofe Sulphur by combining 
 the Vitriolic Acid with the Phlogifton 236. 
 
 CHAP. II. Of the Nitrous Acid. 
 
 1. PROCESS. To extract Nitre out of Nitrous Earths 
 and Stones. The Purification of Saltpetre. Mo- 
 ther of Nitre. Ma^nefia 239. 
 
 2. To decompofe Nitre by means of the Phlogifton. 
 Nitre fixed by. Charcoal. ClyJJus of Nitre. Sal 
 Polychre/lum 246. 
 
 3. To decompofe Nitre by means of the Vitriolic Acid. 
 The Smoking Spirit of Nitre. Sal de duobus. The 
 Purification of Spirit of Nitre 252. 
 
 CHAP. III. Of the Marine Add. 
 
 1. PROCESS. To extract Sea- fait from Sea-water, and 
 from Brine-fprings. Epfom-Salt 2 57* 
 
 2. Experiments concerning the Decompofition of Sea- 
 falt by means of the Phlogifton. Kunckel's Phof- 
 phorus 261* 
 
 3. To decompofe Sea-fak by means of the Vitriolic 
 Acid. Glauber's Salt. The Purification and Con* 
 centration of Spirit of Salt 279. 
 
 4. To decompofe Sea- fait by means of the Nitrous 
 Acid. Aqua regis. Quadrangular Nitre 286. 
 
 CHAP. IV. Of Borax. 28$. 
 
 SECTION II. 
 
 Of Operations on Minerals. 
 
 CHAP. I. Of Gold. 
 
 j. PROCESS. To feparate Gold, by Amalgamation 
 with Mercury, from the Earths and Stones with 
 which it is found mixed 2 95 
 
 2. To diflblve Gold in Aqua regis, and by that means 
 feparate it from Silver. Aumm Fulminant* Aurum 
 Fulminans reduced 300. 
 
 3. To diffolve Gold by Liver of Sulphur 37' 
 
 4. To feparate Gold from all other Metalline Jub- 
 ilances by means of Antimony 39 
 
 CHAP. II. Of Silver. 
 
 j. PROCESS. To feparate Silver from its Ore, by means 
 
 of Scorification with Lead 315. 
 
 VOL. I. a 2. The
 
 xviii CONTENTS. 
 
 2. The refining of Silver by the Cupel 322. 
 
 3. To purify Silver by Nitre 328. 
 
 4. To diflblve Silver in Aqua Fortis^znd thereby feparate 
 it from every other Metalline fubftance. The Pu- 
 i location of dqua Fortis. Silver precipitated by Cop- 
 per 331. 
 
 5. To feparate I Silver from the Nitrous Acid 
 by Diftilhtion. Cryftals of Silver. The Infernal 
 Stone 337. 
 
 6. To feparate Silver from the Nitrous Acid by Pre- 
 cipitation. Luna Cornea. Luna Cornea reduced 339. 
 
 7. To difiblvc Silver, and feparate it from Gold, by 
 Cementation 342. 
 
 CHAP. J1I. Of Copper. 
 
 1. PROCESS. '] o I eparate Copper from its Ore 347. 
 
 2. To purify Black Copper, and render it malle- 
 able 35 r. 
 
 3. To deprive Copper of its Phlogifton by Calcina- 
 tion 353. 
 
 4. To refufcitate the Calx of Copper end reduce it to 
 Metal, by reltoring its Phlogifton 355. 
 
 5. To ciiTolvc Copper in the Mineral Acids ibid. 
 CHAP. IV. Of Iron. 
 
 1. PROCESS. To fcparate Iron from its Ore 358. 
 
 2. To render Pig-iron and brittle Iron malle- 
 able 362. 
 
 ~. 'l*o convert Iron into Steel 364. 
 
 4. The Calcination of Iron. Sundry Saffrons of 
 Mars 367. 
 
 5. Iron difTolved by the Mineral Acids 368. 
 CHAP. V. Of Tin 
 
 j. PROCESS. To extract. Tin from its Ore 370. 
 
 2. The Calcination of Tin 37 2 - 
 
 3. The Difiolution of Tin by Acids 377. 
 CHAP. VI. OfLcaJ. 
 
 1. PROCESS. To extract Lead from its Ore 379. 
 
 2. To ffparzte L?ad from Copper 384 
 
 3. The Calcina'ion of Lead 388. 
 
 4. To prepare Glafs of Lead 389. 
 
 5. Lead difiblved bv the Nitrous Acid 391. 
 C ) I A P VII. Of Afermry. 
 
 j, PROCESS. To extract M.rcury from its Ore, cr to 
 revivify i: from CJinabar 395. 
 
 2. To
 
 CONTENTS. X ix 
 
 2. To give Mercury, by the a&ion of Fire, the ap- 
 pearance of a Metalline Calx 400. 
 
 3. To diflblve Mercury in the Vitriolic Acid. Turbith 
 Mineral 401. 
 
 4. To combine Mercury with Sulphur. ^Ethiops Mi- 
 neral 403. 
 
 5. To fublime the Combination of Mercury and Sul- 
 phur into Cinabar 405. 
 
 6. To diflblve Mercury in the Nitrous Acid. Sundry 
 Mercurial Precipitates 406. 
 
 7. To combine Mercury with the Acid of Sea-falt. 
 Corrofive Sublimate 408. 
 
 8. Sweet Sublimate 413. 
 
 9. The Panacea of Mercury 416. 
 
 *& ^Q* 
 
 MM 
 
 M
 
 ELEMENTS 
 
 O F T H E 
 
 
 
 THEORY of CHYMISTRY. 
 
 CHAP. I. 
 
 Of the PRINCIPLES of Bodies. 
 
 TH E Objeft and chief End of Chymi- 
 ftry is to feparate the different fubftances 
 that enter into the compofition of bodies , 
 to examine each of them apart ; to difcover their 
 properties and relations ; to decompofe thofe very 
 fubftances, if poffible i to compare them together, 
 and combine them with others ; to reunite them 
 again into one body, fo as to reproduce the ori- 
 ginal compound with all its properties , or even to 
 produce new compounds that never exifted among 
 the works of nature, from mixtures of o':her mat- 
 ters differently combined. 
 
 But this Analyfis, or Decompofition, of Bodies 
 is finite , for we are unable to carry it beyond a 
 certain limit. In whatever way we attempt to go 
 
 VQL. I. B further,-
 
 2 ELEMENTS o 
 
 further, we are always flopped by fubftances in 
 which we can produce no change, which are inca- 
 pable of being refolved into others, and which 
 ftand as fo many firm barriers obftru&ing our pro- 
 grefs. 
 
 To thefe fubftances we may, in my opinion, 
 give the title of Principles or Elements : at lead 
 they are really fuch with regard to us. Of this 
 kind the principal are Earth, Water, Air, and 
 Fire. For though there be realbn to think that thefe 
 are not the firft component parts, or the moft fimple 
 elements, of matter ; yet, as we know by ex- 
 perience, that our fenfes cannot poflibly difcover 
 the principles of which they are compofed, it feems 
 more reafonable to fix upon them, and confider 
 them as fimple homogeneous bodies, and the 
 principles of the reft, than to tire our minds with 
 vain conjectures about the parts or elements of 
 which they may confift - 9 feeing there is no criterion 
 by which we can know whether we have hit upon 
 the truth, or whether the notions we have formed 
 are mere fancies. We (hall therefore confider thefe 
 four fubftances as the principles or elements of all 
 the various compounds which natureprefents to our 
 enquiries : becaufe of all thofe we know they are in 
 fact the moft fimple ; and becaufe all our decom- 
 pofitions, all our experiments on other bodies, plain- 
 ly prove that they are at laft refolvable into thefe 
 primary parts. 
 
 Thefe principles do not enter in the fame propor- 
 tion into all bodies : there are even fome mixts in 
 the compolition of which this or that particular 
 principle is not to be found. Thus Air and Wa- 
 ter feem to be wholly excluded from the texture of 
 Metals : at leaft all the experiments hitherto made 
 on them feem to eftablifh this opinion. 
 
 The fubftances compofed immediately of thefe 
 Firft Elements we fhall call Secondary Principles ; 
 
 becaufe
 
 THEORY tf/*CHYMisTRY. 3 
 
 becaufe in reality their fcveral combinations with 
 each other, the interchangeable coalitions that take 
 place between them, confticute the different natures 
 of all other bodies ; which, as they refult from the 
 union both of primary and fecondary principles, 
 are properly entitled to the name of Compounds or 
 Mixts. 
 
 Before we enter upon the examination of Com- 
 pound Subftances, it is necefiary to conlider the 
 mod Simple ones, or our four Firll Principles, with 
 fome attention, in order to difcover their chief 
 properties. 
 
 . I. Of AIR. 
 
 AIR is that Fluid which we conftantly breathe, 
 and which encompafles the whole furface of the 
 terreftrial globe. Being heavy, like all other 
 bodies, it penetrates into all places that are not 
 either abfolutely inacceffible, or filled with fome 
 other body heavier than itfelf. Its principal property 
 is to be fufceptible of condenfation and rarefaction ; 
 fo that the very fame quantity of Air may occupy a 
 much greater, or a much fmaller fpace, according to 
 the different ftate it is in. Heat and cold, or, if you 
 will, the pretence and the abtence of the particles of 
 Fire, are the mod ufual caufes, and indeed the mea- 
 fures,of its condenfation and rarefaction : for if a cer- 
 tain quantity of Air be heated, its bu'k enlarges in 
 proportion to the degree of heat applied to it , the 
 coniequence whereof is, that the lame fpace now 
 contains' fewer particles of Air than it did before. 
 Cold again produces juft the contrary effect. 
 
 On this property which Air has, of being con- 
 denied and dilated by heat* its elafticity chiefly de- 
 pends. For if Air were forced by condenfation 
 into a lefs compais than it took up before, and 
 then expofed to a very confiderable degree of 
 cold, it would remain quite inactive, without exert- 
 
 B 2 ing
 
 4 ELEMENTS*/" the 
 
 ing fuch an effort as it iifiiaily makes againft the 
 comprefTing body. On the other hand, the elafticity 
 of heated Air arifes only from hence, that being 
 rareried by the a'^ion of tire, it requires much 
 more room than it occupied before. 
 
 Air enters into the compofuion of many fub- 
 flances, efpecially vegetable and animal bodies : for 
 by analyfing moftof them luch a confidcrable quan- 
 tity thereof is extricated, that fome naturalifts have 
 fufpe&ed it to be altogether deftitute of elafticity 
 when thus combined with the other principles in the 
 compofition of bodies. According to them the effi- 
 cacy of the elaftic power of the Air is fo prodigi- 
 ous, and its force when comprefTed fo excefiive, that 
 it is not poffible the other component parts of bo- 
 dies mould be able to confine fo much of it, in that 
 {late of comprefTion which it muft needs undergo, if 
 retaining its elafticity it were pent up among them. 
 
 However that be, this elaftic property of the Air 
 produces the molt fingular and important phe- 
 nomena, oblervable in the refolution and compofi- 
 tion of bodies. 
 
 . II. Of WATER. 
 
 WATER is a thing fo well known, that it i$ 
 almoft needlefs to attempt giving a general idea of 
 it here. Every one knows that it is a tranfparent, 
 infipid fubftance, and ufually fluid. I fay it is 
 ufually fo -, for being expofed to a certain degree of 
 cold it becomes lolid : folidity therefore feems to 
 be its moft natural ftate. 
 
 Water expofed to the fire grows hot ; but only 
 to a limited degree, beyond which its heat never 
 rifes, be the force of fire applied to it ever fo vio- 
 lent : it is known to have acquired this degree of 
 heat by its boiling up with great tumult. Water 
 cannot be made hotter, becaufe it is volatile, and 
 incapable of enduring the heat, without being eva- 
 porated and entirely diffipated.
 
 THEORY 0/"CHYMisTRY. 5 
 
 If fuch a violent and fudden heat be applied to 
 Water, as will not allow it time to exhale gently in 
 vapours, as when, for inftance, a fmall quantity 
 thereof is thrown upon a metal in fufion, it is difil- 
 pated at once with vaft impetuofity, producing a 
 moft terrible and dangerous explofion. This fur- 
 priiing effect may be deduced from the inftantane- 
 ous dilatation of the parts of the Water itfelf, or ra- 
 ther of the Air contained in it. Moreover, Water 
 enters into the texture of many bodies, both com- 
 pounds and fecondary principles ; but, like Air, it 
 feems to be excluded from the compofition of all 
 metals and moft minerals. For although an im- 
 menfe quantity of Water exifts in the bowels of the 
 Earth, moiftening all its contents, it does not there- 
 fore follow that it is one of the principles of mine- 
 rals. It is only interpofed between their parts ; for 
 they may be entirely robbed of it, without any fort 
 of decompofition : indeed it is not capable of an 
 intimate connection with them. 
 
 . III. Of EARTH. 
 
 WE obferved that the two principles above treat- 
 ed of are volatile; that is, the action of Fire fepa- 
 rates them from the bodies they help to compofe, 
 carrying them quite off, and difiipating them. 
 That of which we are now to fpeak, namely Earth, 
 is fixed, and, when it is abiblutely pure, refifts the 
 utmoft force of Fire. So that, whatever remains of 
 a body, after it hath been expofed to the power of 
 the fierceft Fire, muft be confidered as containing 
 nearly all its earthy principle, and confiding chiefly 
 thereof. I qualify my exprelTion thus for two rea- 
 fons : the firit is, becaufe it often happens, that this 
 remainder does not actually contain all the Earth 
 which exifted originally in the mixt body decom- 
 pofed by Fire ; fince it will afterwards appear that 
 Earth, though in its own nature fixed, may be ren- 
 
 B 3 dered
 
 6 ELEMENTSC/*^ 
 
 dered volatile by being intimately united with other 
 fubftances which are fo -, and that, in fad, it is 
 common enough for part of the Earth of a body to 
 be thus volatilized by its other principles : the fe- 
 cond is, that what remains after the calcination of 
 a body is not generally its Earth in perfect purity, 
 but combined with ibme of its other principles, 
 which, though volatile in their own natures, have 
 been fixed by the union contracted between it and 
 them. We {hall, in the fequel, produce fomc ex- 
 amples to illuftrate this theory. 
 
 Earth therefore, properly fo called, is a fixed 
 principle, which is permanent in the Fire. 1'here is 
 reafon to think it veiy difficult, if not impofiible, to 
 obtain the terrene principle wholly free from every 
 other fubftance : for after our utmoft endeavours to 
 purify them, the Earths we obtain from different 
 compounds are found to have different properties, 
 according to the different bodies from which they 
 are procured , or elie, if thole Earths be pure, wq 
 muft allow them to be effendally different, feeing 
 they have different properties. 
 
 Earth, in general, with regard to its properties, 
 may be distributed into fuftble, and unfufible -, that 
 is, into Earth that is capable of melting or be- 
 coming fluid in the Fire, and Earth that conftantly 
 remains in a folid form, never melting in the ftrong- 
 eft degree of heat to which we can expofe it. 
 
 The former is alfo called vitr$afrle, and the fe- 
 cond UBvitrifiable Earth ; becaule, when Earth is 
 melted by the force of fire, it becomes what we 
 call /**/}, which is nothing but the parts of Earth 
 brought into nearer contact, and more clofely united 
 by the means of fufion. Perhaps the Earth, which 
 we look upon as uncapable of vitrification, might 
 be fufed if we coulJ apply to it a fufficient degree 
 of heat. It is at lead certain that fome Earths, or 
 Hones, which feparately refift the force of Fire fo 
 
 that
 
 THEORY ^/'CHYMISTRY. 7 
 
 that they cannot be melted, become fufible when 
 mixed together. Experience convinced Mr. du Ha- 
 mel that lime-done and flate are of this kind. It is 
 however undoubtedly true that one Earth differs 
 from another in its degree of fufibility : and this 
 gives ground to believe, that there may be a fpe- 
 cies of Earth abfolutely unvitrifiable in its nature, 
 which, being mixed in different proportions with 
 fufible Earths, renders them difficult to melt. 
 
 Whatever may be in this, as there are Earths 
 which we are abfolutely unable to vitrify, that is a 
 fuffieient reafon for our divifion of them. Unvitri- 
 fiable Earths feem to be porous, for they imbibe 
 Water ; whence they have alfo got the name of 
 Abforbent Earths. 
 
 . IV. Of FIRE. 
 
 THE Matter of the Sun, or of Light, the Phlo- 
 gifton, Fire, the Sulphureous Principle, the Inflam- 
 mable Matter, are all of them names by which the 
 Element of Fire is ufually denoted. But it fhould 
 feem, that an accurate dillinflion hath not yet been 
 made between the different ftates in which it exifts ; 
 that is, between the phenomena of Fire actually 
 exifling as a principle in the compofition of bodies, 
 and thofe which it exhibits when exifting feparately 
 and in its natural flate : nor have proper diftincl: 
 appellations been affigned to it in thole different 
 circumflances. In the latter flate we may properly 
 give it the names of Fire, Matter of the Sun, of 
 Light, and of Heat ; and may confider it as a 
 fubflance compoied of infinitely fmall particles, con- 
 tinually agitated by a mod rapid motion, and of 
 confequence, effentially fluid. 
 
 This fubflance, of which the fun may be calle4 
 the general refervoir, feems to flow inceflantly from 
 that fource, diffufing itfelf over the world, and 
 through all the bodies we know j but not as a prin- 
 
 B 4 ciple,
 
 8 ELEMENTS 
 
 ciple, or efiential part of them, fince they may b 
 deprived thereof, at lead in a great meafure, with- 
 out fuffering any decompofition. The greateft 
 change produced on them, by its prefence or its ab- 
 fence, is the rendering them fluid or folid : fo tW| v 
 all otter bodies may be deemed naturally folid; Fire 
 alone efientially fluid, and the principle of fluidity 
 in others. This being prefuppoied, Air itfelf might 
 become folid, if it could be entirely deprived of the 
 Fire it contains -, as bodies of moft difficult fufion 
 become fluid, when penetrated by a fufficient quan- 
 tity of the particles of Fire. 
 
 One of the chief properties of this pure Fire is to 
 penetrate eafily into all bodies, and to diffufe itfelf 
 among them with a fort of uniformity and equality : 
 for if a heated body be contiguous to a cold one, the 
 former communicates to the latter all its excefs of 
 heat, cooling in exact proportion as the other warms, 
 till both come to have the very fame degree of 
 heat. Heat, however, is naturally communicable 
 fooneft to the upper parts of a body ; and confe- 
 quently, when a body cools, the under parts become 
 fooneft cold. It hath been obferved, for inftance, 
 that the lower extremity of a heated body, freely 
 fufpended in the air, grows cold fooner than the 
 upper ; and that when a bar of iron is red-hot at one 
 end, and cold at the other, the cold end is much 
 fooner heated by placing the bar fo that the hot 
 end may be undermoft, than when that end is 
 turned uppermoft. The levity of the matter of 
 Fire, and the vicinity of the Earth, may pofiibly be 
 the caufes of this phenomenon. 
 
 Another property of Fire is to dilate all bodies 
 into which it penetrates. This hath already been 
 fhewn with regard to Air and Water ; and it pro- 
 duces the fame effect on Earth. 
 
 Fire is the moft powerful agent we can employ 
 to decompofe bodies j and the greateft degree of 
 
 heat
 
 THEORYO/^CHYMISTRY. 9 
 
 heat producible by man, is that excited by the 
 rays of the fun collected in the focus of a large 
 burning-glafs. 
 
 . V, Of the PHLOGISTON, 
 
 FROM what hath been faid concerning the na^ 
 ture of Fire, it is evidently impoffible for us to fix 
 and confine it in any body. Yet the phenome- 
 na attending the combuftion of inflammable bodies 
 Ihew, that they really contain the matter of Fire as a 
 conftituent principle. By what mechanifm then is 
 this fluid, which is fo fubtle, fo active, fo difficult 
 to confine, fo capable of penetrating into every 
 other fubftance in nature ; how comes it, I fay, to be 
 fo fixed as to make a component part of the moft 
 folid bodies ? It is no eafy matter to give a fatisfac- 
 tory anfwer to this queftion. But, without pre- 
 tending to guefs the caufe of the phenomenon, let 
 us reft contented with the certainty of the fact, the 
 knowledge of which will undoubtedly procure us 
 considerable advantages. Let us therefore examine 
 the properties of Fire thus fixed and become a 
 principle of bodies. To this fubftance, in order to 
 diftinguifh it from pure and unfixed Fire, the Chy- 
 mifts have affigned the peculiar title of the Pblo- 
 gifton, which is indeed no other than a Greek word 
 for the Inflammable Matter-, by which latter name, 
 as well as by that of the Sulphureous Principle, it is 
 alfo fometimes called. It differs from elementary 
 Fire in the followjng particulars, i. When united 
 to a body, it communicates to it neither heat nor 
 light. 2. It produces no change in its ftate, whe- 
 ther of folidity or fluidity ; fo that a folid body does 
 not become fluid by. the accefiion of the Phlogifton, 
 and viceverfa -, the folid bodies to which it is joined 
 being only rendered thereby more apt to be fufed by 
 the force of the culinary fire. 3. We can convey it 
 from the body, with which it is joined, into another 
 
 body,
 
 10 E L E M E N T S of the 
 
 body, fo that it (hall enter into the compofition 
 thereof, and remain fixed in it. 
 
 On this occafiOH both thefe bodies, that which is 
 deprived of the Phlogifton and that which receives 
 it, undergo very confiderablc alterations ; and it is 
 this laft circumftance, in particular, that obliges us to 
 diftinguilh the Phlogifton from pure Fire, and to 
 confider it as the element of Fire combined with 
 fomc other fubftance, which ferves it as a baiis for 
 conftituting a kind of fecondary principle. For if 
 there were no difference between them, we mould 
 be able to introduce and fix pure Fire itfelf, where - 
 cver we can introduce and fix the Phlogifton : yet 
 this is what we can by no means do, as will appear 
 from experiments to be afterwards produced. 
 
 Hitherto Chymifts have never been able to obtain 
 the Phlogifton quite pure, and free from every other 
 fubftance : for there are but two ways of feparating 
 it from a body of which it makes a part ; to wit, 
 either by applying lome other body with which it 
 may unite the moment it quits the former ; or elfe 
 by calcining and burning the compound from which 
 you defire to fever it. In the former cafe it is evi- 
 dent that we do not get the Phlogifton by itfelf, 
 becaule it only pafles from one combination into 
 another ; and in the latter, it is entirely diflipated 
 in the decompofition, fo that no part of it can pof- 
 fibly be fecured. 
 
 The inflammability of a body is an infallible fign 
 that it contains a Phlogifton , but from a body's 
 not being inflammable, it cannot be inferred that 
 it contains none : for experiments have demonftra- 
 ted that certain metals abound with it, which yet 
 are by no means inflammable. 
 
 We have now delivered what is moft neceflary to 
 be known concerning the principles of bodies in 
 general. They have many other qualities befides 
 ihofe above-mentioned-, but we cannot properly 
 
 take
 
 THEORY of CHYMISTRY. 11 
 
 itake notice of them here, becaufe they prefuppofc 
 an acquaintance with fome other things relating to 
 bodies, of which we have hitherto faid nothing-, in- 
 tending to treat of them in the fequel as occafion 
 fhall offer. We fhall only obferve in this place, 
 that when animal and vegetable matters are burnt, 
 in fuch a manner as to hinder them from flaming, 
 fome part of the Phlogifton contained in them 
 unites intimately with their mod fixed earthy parts, 
 and with them forms a compound, that can be con- 
 fumed only by making it red-hot in the open air, 
 where it fparkles and waftes away, without emitting 
 any flame. This compound is called a Coal. We 
 lhall enquire into the properties of this Coal under 
 the head of Oils : at prelent it fuffices that we know 
 in general what it is, and that it readily communi- 
 cates to other bodies the Phlogifton it contains. 
 
 CHAP. II. 
 
 A general View of the Relations or 
 Affinities between Bodies. 
 
 EFORE we can reduce compound Bodies 
 
 to the fid! principles above pointed out, we 
 
 obtain, by analyfing them, certain fubftances which 
 are indeed more fimple than the bodies they helped 
 to compofe, yet are themfelves compofed of our pri- 
 mary principles. They are therefore at one and the 
 fame time both principles and compounds , for 
 which reafon we fhall, as was before faid, call them 
 by the name of Secondary Principles. Saline and 
 oily matters chiefly conftitute this clafs. But before 
 we enter upon an examination of their properties, 
 it is fit we lay before the Reader a general view of 
 what Chymifts underftand by the Relations or Affini- 
 ties
 
 If E L E M E N T S 0/* the 
 
 ties of Bodies ; becaufe it is neceffary to know thefe, 
 in order to a diftinct conception of the different 
 combinations we are to treat of. 
 
 Ail the experiments hitherto made concur with 
 daily obfcrvation to prove that different bodies, 
 whether principles or compounds, have luch a mu- 
 tual Conformity, Relation, Affinity, or Attraction, 
 if you will call it lo, as difpofes fome of them to 
 join and unite together, while they are incapable of 
 contracting any union with others. This effect, 
 whatever be its caufe, will enable us to account 
 for, and connect together, all the phenomena that 
 Chymiltry produces. The nature of this univerlal 
 affection of matter is diftinctly laid down in the fol- 
 lowing propofitions. 
 
 Firft, If one fubftance hath any Affinity or con- 
 formity with another, the two will unite together, 
 and form one compound. 
 
 Secondly, It may be laid down as a general rule, 
 that all fimilar fubftances have an Affinity with each 
 other, and are confequently difpofed to unite j as 
 water with water, earth with earth, &c. 
 
 Thirdly, Subftances that unite together lofe fome 
 of their feparate properties , and the compounds re- 
 fulting from their union partake of the properties 
 of thole fubftances which ferve as their principles. 
 
 Fourthly, The fimpler any fubftances are, the 
 more perceptible and confiderable are their Affini- 
 ties : whence it follows, that the lefs bodies are 
 compounded, the more difficult it is to analyfe 
 them , that is, to feparate from each other the 
 principles of which they confift. 
 
 Fifthly, If a body confift of two fubftances, and 
 to this compound be prelented a third fubftance 
 that has no Affinity at all with one of the two pri- 
 mary fubftances aforefaid, but has a greater Affinity 
 with the other than thofe two fubftances have with 
 each other, there will enfue a decompofition, and a 
 
 new
 
 THEORY O/'CHYMISTRY. 13 
 
 new union ; that is, the third fubftance will feparate 
 the two compounding fubftances from each other, 
 coalefce with that which has an Affinity with it, form 
 therewith a new combination, and difengage the 
 other, which will then be left at liberty, and fuch 
 as it was before it had contracted any union. 
 
 Sixthly, It happens fometimes that when a third 
 fubftance is preiented to a body confiding of two 
 fubftances, no decompofition follows ; but the two 
 compounding fubftances, without quitting each 
 other, unite with the fubftance prefented. to them, 
 and form a combination of three principles : and 
 this comes to pafs when that third fubftance has an 
 equal, or nearly equal, Affinity with each of the com- 
 pounding fubftances. The fame thing may alfo 
 happm even when the third fubftance hath no 
 Affinity but with one of the compounding fubftances 
 only. To produce fuch an effect, it is fufficient that 
 one of the two compounding fubftances have to the 
 third body a Relation equal, or nearly equal, to that 
 which it has to the other compounding fubftance 
 with which it is already combined. Thence it fol- 
 lows, that two fubftances, which, when apart from 
 all others, are incapable of contracting any union, 
 may be rendered capable of incorporating together 
 in fome meafure, and becoming parts of the fame 
 compound, by combining with a third fubftance 
 with which each of them has an equal Affinity. 
 
 Seventhly, A body, which of itfelf cannot de- 
 compofeacompoundconfiftingoftwofubftances,be- 
 caufe, as we juft now faid, they have a greater Affinity 
 with each other than it has with either of them, be- 
 comes neverthelefs capable of feparating the two by 
 uniting with one of them, when it is itfelf combined 
 with another body, having a degree of Affinity with 
 that one, fufficient to compenfate its own want thereof. 
 In that cafe there are two Affinities, and thence enfues 
 a double decompofition and a double combination. 
 
 Thefe
 
 14 ELEMENTS 0/* the 
 
 Thefe fundamental truths, from which we (halt 
 deduce an explanation of all the phenomena in 
 Chymiftry, will be confirmed and illuftrated by 
 applying them, a"s we mall do, to the fcveral cafes, 
 of which our defign in this Treatife obliges us to 
 give a circumftantial account. 
 
 CHAP. III. 
 
 Of Saline Subftances in general. 
 
 IF a particle of water be intimately united with 
 a particle of earth, the refult will be a new com- 
 pound, which, according to our third proportion 
 of Affinities, will partake of the properties of earth 
 and of water-, and this combination principally forms 
 what is called a Saline Sitbftance. Confequently 
 every faline Subflance muft have an affinity with 
 earth and with water, and be capable of uniting 
 with both or either of them, whether they befeparatc 
 or mixed together: and accordingly this property 
 charafterifes all Salts, or Saline Subftances, in general. 
 
 Water being volatile and Earth fixed, Salts in 
 general are lefs volatile than the former, and lefs 
 fixed than the latter; that is, fire, which cannot 
 volatilize and carry off pure earth, is capable of 
 rarefying and volatilizing a Saline Subftance-, but 
 then this requires a greater degree of heat than is 
 necefiary for producing the fame effects on pure 
 water. 
 
 There are feveral forts of Salts, differing from one 
 another, in reipect either of the quantity, or the qua- 
 lity of the earth in their compofition ; or laftly, they 
 differ on account of Ibme additional principles,which 
 not being combined with them in fufficient quantity 
 to hinder their Saline properties from appearing, 
 
 permit
 
 THEORY $/* CHYMISTRY. 15 
 
 permit them to retain the name of Salts, though 
 they render them very different from the fimpleft 
 Saline Subftances. 
 
 It is eafy to infer, from what has been faid of Salts 
 in general, that fome of them muft be more, fome 
 lefs, fixed or volatile than others, and fome more, 
 fome lefs, difpofed to unite with water, with earth, 
 or with particular forts of earth, according to the 
 nature or the proportion of their principles. 
 
 Before we proceed further, it is proper juft to 
 mention the principal reafons, which induce us to 
 think that every Saline Subftance is actually a com- 
 bination of earth and water, as we fuppofed at our 
 entering on this fubjeft. The firft is, the conformity 
 Salts have with earth and water, or the properties 
 they pofTefs in common with both. Of thele pro- 
 perties we (hall treat fully, as occafion offers to con- 
 iider them, in examining the feveral forts of Salts. 
 The fecond is, that all Salts may be aciually re- 
 folved into earth and water by fundry procefies; 
 particularly by repeated diflblution in water, eva- 
 poration, deficcation, and calcination. Indeed the 
 Chymifts have not yet been able to procure a Saline 
 Subftance, by combining earth and water together. 
 This favours a fufpicion, that, befides thefe two, 
 there is fome other principle in the competition of 
 Salts, which efcapes our refearches, becaufe we 
 cannot preferve it when we decompofe them : but 
 it is fufficient to our purpofe, that water and earth 
 are demonftrably amongft the real principles of Sa- 
 line Subftances, and that no experiment hath ever 
 Ihewn us any other. 
 
 . I. Of ACIDS. 
 
 OF all Saline Subftances, the fimpleft is that called 
 an Acid, on account of its tafte ; which is like that of 
 verjuice, forrel, vinegar, and other four things, which 
 for the fame reafon are aifo called Acids. By this 
 
 peculiar
 
 1 6 ELEMENTS^/" the 
 
 peculiar tafte arc Acids chiefly known. They have 
 moreover the property of turning alj the blue and 
 violet colours of vegetables red, which diftinguifhes 
 them from all other falts. 
 
 The form, under which Acids moil commonly 
 appear, is that of a tranfparent liquor ; though 
 folidky is rather their natural ftate. This is owing 
 to their affinity with water; which is fo great that, 
 when they contain but juft as much of it as is ne- 
 cefiary to constitute them Salts, and confequently 
 have a folid form, they rapidly unite therewith the 
 moment they come into contact with it : and as the 
 air is always loaded with moifture and aqueous va- 
 pours, its contact alone is fufficicnt to liquify them ; 
 becaufe they unite with its humidity, imbibe it 
 greedily, and by that means become fluid. We 
 therefore fay, they attract the moifture of the air. 
 This change of a fait from a folid to a fluid (late, 
 by the fole contact of the air, is allb called Deliquium-y 
 fo that when a fait changes in this manner from a 
 folid into a fluid form, it is faid to run -per deliquium. 
 Acids being the fimpleft fpecies of Saline bodies, 
 their affinities with different fubftances are ftronger 
 than thofe of any other fort of fait with the fame 
 fubftances ; which is agreeable to our fourth pro- 
 pofition concerning Affinities. 
 
 Acids in general have a great affinity with earths : 
 that with which they mod readily unite is the un- 
 vitrifiable earth to which we gave the name of 
 abforbent earth. They Icem not to act at all upon 
 verifiable earths, fuch as fand , nor yet upon fome 
 other kinds of earths, at leaft while they are in thtir 
 natural ftate. Yet the nature of thele earths may 
 be in fome meafure changed, by making them red 
 hot in the fire, and then quenching them fuddenly 
 in cold water : for by repeating this often they are 
 brought nearer to the nature of abforbent earths/ 
 and rendered capable of uniting with Acids, 
 
 When
 
 THEORY C/^CHYMISTRY. 17 
 
 When an acid liquor is mixed with an abforbent 
 earth, for inftance with chalk, thefe two fubftances 
 inftantly rufh into union, with fo much impetuofity, 
 eJpecially if the acid liquor be as much dephleg- 
 mated, or contain as little water, as may be, that a 
 great ebullition is immediately produced, attended 
 with confiderable hitting, heat, and vapours, which 
 rile the very inftant of their conjunction. 
 
 From the combination of an Acid with an ab- 
 forbent earth there arifes a new compound, which 
 fome Chymifts have called Sal Salfum , becaufe the 
 Acid by uniting with the earth lofes its four tafte, 
 and acquires another not unlike that of the common 
 fea fait ufed in our kitchens ; yet varying according 
 to the different forts of Acids and earths combined 
 together. The Acid^at the fame time lofes its pro- 
 perty of turning vegetable blues and violet colours 
 red. 
 
 If we enquire what is become of its propenfity to 
 unite with water, we (hall find that the earth, which 
 of itlelf is not foluble in water, hath by its union 
 with the Acid acquired a facility of diffolving there- 
 in ; fo that our Sal Salfum is foluble in water. But, 
 on the other hand, the Acid hath, by its union with 
 the ^arrh, loft part of the affinity ic had with water ; 
 fo that if a Sal Salfum be dried, and freed of all 
 fuperfluous humidity, it will remain in that dry folid 
 form, inftead of attracting the tnoifture of the air, 
 and running per deliquium, as the Acid would do 
 if it were pure and unmixed with earth. However, 
 this general rule admits of fome exceptions ; and 
 we (hall have occafion in another place to take no- 
 tice of certain Combinations of Acids with earths, 
 which ftill continue to attract the moifture of the 
 air, though not fo ftrongly as a pure Acid. 
 
 ACIDS have likewife a great affinity with the 
 Phlogifton. When we come to treat of each Acid 
 in particular, we Ihall examine the combinations of 
 
 VOL. I, C each
 
 i8 ELEMENTS cf the 
 
 each with the Phlogifton : they differ fo widely 
 from one another, nnd many of them are fo little- 
 known, that we cannot at prefcnt give any general 
 idea of them. 
 
 II. Of ALKALIS. 
 
 ALKAi.i 1 ? are Saline combinations in which there 
 is a greater proportion of earth than in Acids. The 
 principal arguments that may be adduced to prove 
 this fact are thefe : Firft , if they be treated in the 
 manner propofed above for analyzing Saline Sub- 
 ftances, we obtain from them a much greater 
 quantity of earth than we do from Acids. Se- 
 condly ; by combining certain Acids with certain 
 earths we can produce Alkalis ; or at lead fuch 
 faline compounds as greatly rekmble them. Our 
 third and lad argument is drawn from the pro- 
 perties of thofe Alkalis which, when pure and un- 
 adulterated with any other principle, have lefs affi- 
 nity with water than Acids have, and are alto more 
 fixed, refilling the mm oft force of fire. On this 
 account it is that they have obtained the title of 
 ,-11 as to dillinguifh them from another 
 (peci.es of Alkali, to be coniidered hereafter, which 
 is impure and vo'atile. 
 
 Though fixed Alkalis, when dry, fuilain the ut- 
 mou violence of fire without flying oiTin vapours, 
 it i c remarkable that, being boiled with water in an 
 open vefiel, confiderable quantities of them rile 
 with the {team : an effect which mud be attributed 
 to the great affinity between thefe two Jubilances, 
 by means whereof water communicates fome part 
 or its volatility to the fixed fait. 
 
 Alkalis freed of their fuperfluous humidity by 
 calcination attract the moiilure of the air, but not 
 fo llrongly as Acids : fo that it is eafier to procure 
 ai.d prcierve them in a folid form. 
 
 They
 
 THEORY of C H Y M i s T R Y. 19 
 
 They flow in the fire, and are then capable of 
 uniting with vitriliable earths, and of forming there- 
 with true glafs, which, however, will partake 
 of their properties, if they be ufed in fufficient 
 quantity. 
 
 As they melt more readily than vitrifiable earth, 
 they facilitate its fufion ; Ib that a weaker fire will 
 reduce it to glafs, when a fixed Alkali is joined with 
 it, than will melt it without that addition. 
 
 Alkalis are known by their tafte, which is acrid 
 and fiery -, and by the properties they pofiefs of 
 turning certain vegetable blues and violet colours 
 green ; particularly fyrop of violets. 
 
 Their affinity with Acids is greater than that of 
 abforbent earths ; and hence it comes to pafs that 
 if an Alkali be prefented to a combination of an 
 Acid with an abforbent earth, the earth will be 
 feparated from the Acid by the Alkali, and a new 
 union between the Acid and the Alkali will take 
 place. This is both an inftance and a proof of our 
 fifth propofition concerning Affinities. 
 
 If a pure Alkali be prefented to a pure Acid, 
 they rufh together with violence, and produce the 
 fame phenomena as were obferved in the union of 
 an abforbent earth with an Acid ; but in a, greater 
 and more remarkable degree. 
 
 Fixed Alkalis may in general be divided into two 
 forts : one of thefe hath all the above recited pro- 
 perties \ but the other poflefles fome that are pecu- 
 liar to itfelf. We mata> confider this latter fore 
 more particularly under the head of Sea-Salt. 
 
 111. Of NEUTRAL SALTS. 
 
 THE Acid and the Alkali thus uniting mutually 
 rob each other of their characleriilic properties ; 
 fo that the compound refulting from their union 
 produces no change in the blue colours of vege- 
 tables, and has a tafte which is neither four nor 
 
 C a acrid,
 
 2o ELEMENTS^/" the 
 
 acrid, but fahifh. A faline combination of this kind 
 is for that reafon named Sal Salfum, Sal Medium^ 
 or a Neutral Salt. Such combinations are alfo 
 called by the plain general name of Salts. 
 
 It mu ft be obferved that, in order to make thefe 
 Salts perfectly Neutral, it is necefiary that neither 
 of the two faline principles of which they are com- 
 pounded be predominant over the other ; for in that 
 cafe they will have the properties of the prevailing 
 principle. The reafon is this : neither of ihele la- 
 line lubftar.ces can unite with the other but in a li- 
 mited proportion, beyond which there can be no 
 further coalition between them. The action by 
 which this perfect union is accomplilhed is termed 
 Saturation , and the inftant when fuch proportions of 
 the two ialine fubftances are mixed together, that 
 the one is incorporated with as much of the other 
 as it can pofiibly take up, is called the Point of 
 Saturation. All this is equally applicable to the 
 combination of an Acid with an abforbent earth. 
 
 The con;bination is known to be perfect, that is, 
 the Point of Saturation is known to be obtained,, 
 when after repeated affufions of an Acid in fmall 
 quantities to an Alkali, or an abforbent earth, we 
 find thofe phenomena ceafe, which in fuch cafes 
 conftantly attend the conflict of union, as we faid 
 above, namely, ebullition, hilling, C5V. and we 
 may be allured the Saturation is complete when the 
 new .compound hath neither an acid nor an acrid 
 tafte, nor in the lead changes the blue colours of 
 vegetables. 
 
 Neutral Salts have not fo great an affinity with 
 water as either Acids or Alkalis have -, becaufe they 
 are more compounded : for we obierved before, 
 that the affinities of the moft compounded bodies 
 are generally weaker than thofe of the moft iimple. 
 In conlequence hereof few Neutral Salts, when dried, 
 attract the moifture of the air - t ani} thofe that do, 
 
 attract
 
 THEORY of CUY MI ST RY. 2-1 
 
 attract it more flowly, and in lefs quantity, than 
 either Acids or Alkalis do. 
 
 All Neutral Salts are foluble in water ; but more 
 or lefs readily, and in a greater or fmaller quantity, 
 according to the nature of their component prin- 
 ciples. 
 
 Water made boiling hot diffblves a greater quan- 
 tity of thofe falts which do not attract the moifture 
 of the air, than when it is cold ; and indeed it mud 
 be boiling hot to take tip as much of them as it is 
 capable of diflblving : but as for thofe which run 
 in the air, the difference, if there be any, is im- 
 perceptible. 
 
 Some Neutral Salts have the property of {hoot- 
 ing into Cryftals, and others have it not. 
 
 The nature of Cryftallization is this : Water can- 
 not diflolve, nor keep in folution, more than a de- 
 terminate quantity of any particular Salt : when, 
 therefore fuch a quantity of water is evaporated from 
 the folution of a Salt capable of cryftallization, that 
 the remainder contains juft as much Salt as it can 
 difiblve, then by continuing the evaporation the Salt 
 gradually recovers its folidform, and concretes into 
 feveral little tranfparent maffes called Cryftals. 
 Thefe cryftals have regular figures, all differing 
 from one another according to the fpecies of Salt of 
 which they are formed. Different methods of eva- 
 porating faline folutions have different effects on the 
 figure and regularity of the cryftals ; and each par- 
 ticular fort of Salt requires a peculiar method of eva- 
 poration to make its cryftals perfectly regular. 
 
 A folution of Salt defi&ried for crvftallization is 
 
 O 
 
 ufually evaporated by means of fire to a pellicle -, 
 that is, till the Salt begin to concrete , which is 
 perceived by a kind of thin dark (kin that gathers 
 on the furface of the liquor, and is formed of the 
 cryftallized particles of Salt. When this pellicle 
 gppears the folution is fuffered to cool, and the cry- 
 
 C 3
 
 22 E L E M E N T S of the 
 
 ftals form therein fafter or flower according to the 
 fore of Sal: in hand. If the evaporation be car- 
 ried on brifkly to perfect drynefs, no cryftals will 
 he formed, and only an irregular mats of Salt will 
 be obtained. 
 
 The reafons why no cryftals appear when the 
 evaporation is haftily performed, and carried on to 
 drynefs, are, firft, that the particles of Salt, being 
 always in motion while the folution is hot, have 
 not time to exert their mutual affinities, and to 
 unite together as cryftallization requires : fecondly, 
 .in quantity of water enters into the very 
 compofition of cryftals , which is therefore ablb- 
 ifary to their formation, and in a greater 
 or fmaller proportion according to the nature of 
 the Salt*. 
 
 If tliefe cryftallized Salts be expofed to the fire, 
 they firft part with that moifture which is not ne- 
 "uy to a faline concretion, and which they re- 
 tained only by means of their cryftallization : after- 
 wards they begin to flow, but with different de- 
 grees of firfibility. 
 
 It muft be obferved that certain Salts melt as 
 foon as they are expofed to the fire ; namely, thofe 
 which retain a great deal of water in cryftallizing. 
 But this fluor which they fo readily acquire muft be 
 carefully diftinguifhed from actual fufion : for it is 
 owing only to their fuperfluous humidity, which 
 heat renders capable of diflblving and liquifying 
 t .cm ; fo that when it is evaporated the Salt ceafes 
 to be fluid, and requires a much greater degree of 
 fire to bring it into real fufion. 
 
 The Neutral Salts that do not cryftallize may, 
 indeed, be dried by evaporating the water which 
 
 * Thofe who have the curiofity to fee a more particular ac- 
 count of the Cryftallization of Neutral Salts, may read Mr. 
 Rouelle'a excellent Memoir on that Subjeft, among thofe of trie 
 Academy of fcciences for j 744. 
 
 keeps
 
 T H E-o R Y of CHYMISTRY. 23 
 
 keeps them .fluid , but by becominp; foli'd they ac- 
 quire no regular form ; they again attract the 
 moifture of the air, and are thereby melted into a 
 liquor. Thefe may be called Liquefcent Sails, 
 
 Mod of the Neutral Salts, that confift of an Acid 
 joined wirh a fixed Alkali, or with an abforbent 
 earth, are themfclvcs fixed, and refill the force of 
 fire-, .yet feveral of them, if they be diiTolved in 
 water and the folution boiled and evaporated, fly 
 off along with the ileams. 
 
 CHAP. IV. 
 
 Of the fever al Sorts of Saline Subftances* 
 
 . I. Of the UNIVE RSAL ACID. 
 
 TH E Univerfal Acid is fo called, becaufe it is 
 in fact the Acid which is moll univerfally 
 diffufed through all nature, in waters, in the at- 
 mofphere, and in the bowels of the earth. But it 
 is feldom pure -, being almoft always combined with 
 fome other fubltance. That from which we obtain 
 it with moft eafe and in the greateft quantity is 
 Vitriol, a mineral which we fhall confider afterwards : 
 and this is the reafon why it is called the Vitriolic 
 Acid , the name by which it is beft known. 
 
 When theVitriolicAcid contains but littlephlegm, 
 yet enough to give it a fluid form, it is called Oil* 
 of Vitriol ; on account of a certain unctuofuy be- 
 longing to it. In truth this name is very improperly 
 beftowed on it ; for we fhall afterwards fee that, 
 bating this unctuoufnefs,it has none of the properties 
 of oils. But this is not the only impropriety in 
 names that we lhall have occafion to cenfure. 
 
 C 4 If
 
 24 E L E M E N T S of the 
 
 If the Vitriolic Acid contain much water it is 
 then called Spirit of Vitriol. When it does not con- 
 tain enough to render it fluid, and fo is in a folid 
 form, it is named the Icy Oil of Vitriol. 
 
 When Oil of Vitriol highly concentrated is 
 mixed with water, they rufh into union with fuch 
 impctuofity that, the moment they touch each 
 other, there arifes a hilling noife, like that of red- 
 hot iron plunged in cold water, together with a 
 very confiderable degree of heat, proportioned to 
 the degree to which the Acid was concentrated. 
 
 If inftead of mixing this concentrated Acid 
 with water, you only leave it expo fed to the air 
 for fome time, it attracts the moifture thereof, 
 and imbibes it moft greedily. Both its bulk and 
 its weight are increafed by this acceflion ; and if 
 it be under an icy form, that is, if it be con- 
 crcteJ, the phlegm thus acquired will foon refolve 
 it into a fluid. 
 
 The addition of water renders the Vitriolic Acid, 
 and indeed all other Acids, weaker in one fenfe ; 
 which is, that when they are very aqueous they 
 leave on the tongue a much fainter tafteof acidity, 
 and are lefs active in the folution of fome parti- 
 cular bodies : but that occafions no change in the 
 itrength of their affinities, but in fome cafes rather 
 enables them to dillblve feveral fubftances, which, 
 when well dephlcgmated, they are not capable of 
 attacking. 
 
 The Vitriolic Acid combined to the point of fa- 
 turation with a particular ablbrbent earth, the na- 
 ture of which is not yet well known, forms a Neu- 
 tral bait that cryftallizes. This Salt is called Alum, 
 and the figure of its cryftals is that of an octahe- 
 dron, or iolid of eight fides. Thefe odtahedra 
 are triangular pyramids, the angles of which are 
 fo cut off that four of the furfaccs are hexagons, 
 and the other four triangles. 
 
 There
 
 THEORY ^CHYMISTRY. 25 
 
 There are feveral forts of Alum, which differ ac- 
 cording to the earths combined with the Vitriolic 
 Acid. Alum difiblves eafily in water, and in cry^ 
 ftallization retains a confiderable quantity of it; 
 which is the reafon that being expofed to the fire it 
 readily melts, fwelling and puffing up as its fuper- 
 fluous moiilure exhales. When that is quite evapo- 
 rated, the remainder is called Burnt Alum, and is 
 very difficult to fufe. The Acid of the Alum is 
 partly diflipated by this calcination. Its tafte is 
 faltifh, with a degree of roughnefs and atfringency, 
 
 The Vitriolic Acid combined with certain earths 
 forms a kind of Neutral Salt called Selenites, which 
 cryftallizes in different forms according to the nature 
 of its earth. There are numberlefs fprings of wa- 
 ter infected with difiblved Selenites ; but when this 
 Salt is once cryftallized, it is exceeding difficult to 
 dhTolve it in water a fecond time. For that pur- 
 pole a very great quantity of water is necefTary, and 
 moreover it muft boil , for as it cools moft of the 
 diflblved Selenites takes a folid form, and falls in a 
 powder to the bottom of the veffel. 
 
 If an Alkali be prefented to the Selenites, or to 
 Alum, thefe Salts, according to the principles we 
 have laid down, will be thereby decompofed ; that 
 is, the Acid will quit the earths, and join the Alkali, 
 with which it hath a greater affinity. And from 
 this conjunction of the Vitriolic Acid with a fixed 
 Alkali there refults another fort of Neutral Salt, 
 which is called Arcanum duplicatum, Sal de duobus, 
 and Vitriolated Tartar, becaufe one of the fixed 
 Alkalis moft in ufe is called Salt of Tartar. 
 
 Vitriolated Tartar is almoft as hard to diflblve in 
 water as the Selenites. It (hoots into eight-fided 
 cryftals, having the apices of the pyramids pretty 
 obtufe. Its taite is faltifh, inclining to bitter j and 
 it decrepitates on burning coals. It requires a very 
 great degree of fire to make it flovy. 
 
 The
 
 26 ELEMENTS 
 
 The Vitriolic Acid is capable of uniting with trie 
 Phlogifton, or rather it has a greater affinity with it 
 than with any other body: whence it follows that 
 all compounds, of which it makes a part, may be 
 decompofed by means of the Phlogifton. 
 
 From the conjunction of the Vitriolic Acid with 
 the Phlogifton arifes a compound called Mineral 
 Sulphur, becaufe it is found perfectly formed in the 
 bowels of the earth. It is allo called Sulphur vivu;;t, 
 or fimply, Sulphur. 
 
 Sulphur is abfoluuly infoluble in water, and in- 
 capable of contracting any fort of union with it. 
 It melts wuh a v e decree c.r heat, and 
 
 lublimes ia line light downy tufts called I'imers rf 
 Sulpkur. By being thus fublimed it fuifers no de- 
 compofition, let the operation be repeated ever lo 
 often i fothat Sublimed Sulphur, or Flower of Sul- 
 phur, hath exactly the fame properties as Sulphur 
 that has never been fublimed. 
 
 If Sulphur be expofed to a brifk heat in the open 
 air, it takes fire, burns, and is wholly confumed. 
 This deflagration of Sulphur is the only means we 
 have of decompofing it, in order to obtain its Acid 
 in purity. The Phlogifton is deftroyed by the flame, 
 and the Acid exhales in vapours : thefe vapours col- 
 lected have all the properties of the Vitriolic Acid, 
 and differ from it only as they ftill retain fome por- 
 tion of the Phlogifton-, which, however, foon quits 
 them of its own accord, if the free accefs of the 
 common air be not precluded. 
 
 The portion of Phlogifton retained by the Acid 
 of Sulphur is much more confiderable when that 
 mineral is burnt gradually and (lowly : in that cafe 
 the vapours which rife from it have fuch a pene- 
 trating odour, that they inftantaneoufly iuffocate any 
 perfon who draws in a certain quantity of them with 
 his breath. Thefe vapours conftitiue what is called 
 the Volatile Spirit of Sulphur. There is reafon to 
 
 think
 
 THEORY ?/CHYMISTRY. 27 
 
 think this portion of Phlogifton which the Acid re- 
 tains is combined therewith in a manner different 
 from that in which thefe two are united in the Sul- 
 phur itfelf; for, ashasjuft been obferved, nothing 
 but actual burning is capable of feparating the Vi- 
 triolic Acid and the Phlogifton, which by their union 
 form Sulphur; whereas in the Volatile Spirit of 
 Sulphur they kparate fpontaneoufly when expofed 
 to the open air ; that is, the Phlogifton flies off and 
 leaves the Acid, which then becomes in every re- 
 fpect fimilar to the Vitriolic Acid. 
 
 That the Volatile Spirit of Sulphur is a com- 
 pound, as we have aiTerted it to be, appears evidently 
 from hence, that whenever the Vitriolic Acid touches 
 any fubftance containing the Phlogifton,. provided 
 that Phloo;ifton be difengased or opened to a cer- 
 
 O *^ ^J 
 
 tain degree, a Volatile Spirit of Sulphur is infalli- 
 bly and immediately generated. This Spirit hath 
 all the properties of Acids, bur confiderably weak- 
 ened, and of courfe lefs perceptible. It unices with 
 abforbent earths or fixed Alkalis-, and with them 
 forms Neutral Salts : but when combined therewith 
 it may be ieparated from them by the Vitriolic 
 Acid, and indeed by any of the mineral Acids, 
 becaufb its affinities are weaker. Sulphur hath the 
 property of uniting with abforbent earths, but not 
 near fo intimately as with fixed Alkalis. 
 
 If equal parts of Sulphur and an Alkali be melted 
 together, they incorporate with each other; and 
 from their conjunction proceeds a compound of a 
 moft unpleafant fmell, much like that of rotten 
 eggs, and of a red colour nearly refembling that of 
 an animal liver, which has occaiioned it to bear the 
 name of Hepar Sulpburis, or Liver of Sulphur. 
 
 In this compofition the fixed Alkali comm unicates 
 
 to the Sulphur the property of diffolving in water : 
 
 and hence it comes that Liver of Sulphur may be 
 
 made as well when the Alkali is diffolved by water 
 
 5 into
 
 2$ E L E M E N T S of the 
 
 into a fluid, as when it is fufed by the action of 
 fire. 
 
 Sulphur has lefs affinity than any Acid with the 
 fixed Alkalis: and therefore Liver of Sulphur may 
 be decompounded by any Acid whatever; which 
 will unite with the fixed Alkali, form therewith a 
 Neutral Salt, and feparate the Sulphur. 
 
 If Liver of Sulphur be diflblved in water, and 
 an Acid poured thereon, the liquor, which was 
 tranfparent before, inftantly turns to an opaque 
 white; bccaufe the Sulphur, being forced to quit 
 its union with the Alkali, lofes at the fame time the 
 property of difiblving in water, and appears again 
 in its own opaque form. The liquor thus made 
 white by the Sulphur is called Milk of Sulphur. 
 
 If this liquor be fu fife red to ftand ftill for fome 
 time, the particles of Sulphur, now moil minutely 
 divided, gradually approach each other, unite, and 
 fall infenfibly to the bottom of the veflel ; and 
 then the liquor recovers its tranfparency. The 
 Sulphur thus depofited on the bottom of the vefiel 
 is called the Mtgiftery or Precipitate cf Sulphur. 
 The names of Magiltery and Precipitate arc alfo 
 given to all iubftances whatever that are feparated 
 from another by this method; which is the realbn 
 that we ufe the cxprefTion of precipitating one fub- 
 fiance by another, to fignify the icparating one of 
 them by means of the other. 
 
 . II. Of the NITROUS ACID. 
 
 It is not certainly known what conftitutes the 
 difference between the Nitrous Acid and the Vitrio- 
 lic Acid, with regard to the conftituent principles of 
 each. The mod probable opinion is, that the 
 Nitrous Acid is no other than the Vitriolic Acid 
 combined with a certain quantity qf Phlogifton by 
 
 the
 
 THEORY of C H Y M i s T R Y. 29 
 
 the means of putrefaction. If it be fo, the Phlo- 
 gifton muft be united with the Univerfal Acid in 
 another manner than it is in fulphnr, and in its vo- 
 latile fpirit : for the Nitrous Acid differs from them 
 both in its properties. What gives ground for this 
 opinion is, that the Nitrous Acid is never found 
 but in earths and (tones which have been impreg- 
 nated with matters fubject to putrefaction, and 
 which therefore muft contain the Phlogifton, For 
 it is necefiary juft to obferve here, though it be 
 not yet proper to enter particularly into the fubjecl:, 
 that all iubftances fufceptible of putrefaction really 
 contain the Phlogifton. 
 
 The Nitrous Acid combined with certain abfor- 
 bent earths, fnch as chalk, marie, boles, forms 
 Neutral Saks which do not cryftallize ; and which* 
 after being dried, run in the a\r per deliquium. 
 
 All thole Neutral Salts which confift of the Ni- 
 trous Acid joined to an earth, may be decompo- 
 fed by a fixed Alkali, with which the Acid unites, 
 and deferts the .earth ; and from this union of the 
 Nitrous Acid 'with a fixed Alkali refults a new 
 Neutral Salt which is called Nitre, or Salt-petre. 
 This latter name fignifies the Salt of Stone; and in 
 fact Nitre is extracted from the (tones and plaifter, 
 in which it forms, by boiling them in water fatu- 
 rated with a fixed Alkali. 
 
 Nitre (hoots in long cryftals adhering fideways to 
 each other? it has a (altiih tafte, which produces a 
 fenfation of cold on the tongue. 
 
 This Salt eafily difiblves in water 5 which, when 
 boiling hot, takes up dill a greater quantity there- 
 of. 
 
 It flows with a pretty moderate degree of hear, 
 and continues fixed therein: but being urged by a 
 brifk fire, and in the open air, it lets go fome pait 
 o/ its Acid, and indeed flies off itfelf in part. 
 
 The
 
 30 E L E M E N T s of the 
 
 The moft remarkable property of Nitre, and that 
 which characterizes it, is its Fulmination or Explo- 
 fjr>n , the nature ot" which is as follows: 
 
 icn Nitre touches any fubftance containing a 
 Phlopillon, and actually ignited, that is, actually 
 on fire, it burfts out into a flame, burns, and is 
 decompounded with much noife. 
 
 In this deflagration the Acid is diffipated, and 
 totally feparated from the Alkali, which now re- 
 mains by itfelf. 
 
 Indeed the Acid, at lead the greateft part of it, 
 is by this means quite deftroyed. The Alkali 
 which is left when Nitre is decompounded by defla- 
 gration, is called in general Fixed Nitre, and, more 
 particularly, Nitre fixed by fuch and fuch a fub- 
 ilance as was ufed in the operation. But if Nitre 
 be deflagrated with an inflammable fubftance con- 
 taining the vitriolic Acid, as fulphur, for inftance, 
 the fixed Salt produced by the deflagration is not 
 a pure Alkali, but retains a good deal of the vi- 
 triolic Acid, and, by combining therewith, hath 
 now formed a neutral Salt. 
 
 Hitherto Chymills have been at a lofs for the 
 reafon why Nitre flames, anp! is decompounded in the 
 manner above mentioned, when it comes in contact 
 with a Phlogifton properly circumftanced. For my 
 I conjecture it to be for the fame reafon that 
 1 tartar is alfo decompounded by the addi- 
 tion of a Phlogifton -, viz. the Nitrous Acid, having 
 a greater affinity with the Phlogifton than with th,e 
 A! kali, naturally quits the latter to join with 
 the former, and fo produces a kind of fulphur, dif- 
 fering probably from the common fulphur, formed 
 by the vitriolic Acid, in that it is combuftible to fuch 
 a degree, as to take fire and be confumed in the very 
 moment ot its production; fo that it is impolfible to 
 prevent its being thus deilroyed, and confequently 
 impofiible to lave it. In lupport of this opinion 
 
 let
 
 THEORY of C HYMISTRY. 31 
 
 let it be confidered, that the concurrence of the 
 Phlogifton is abfohuely necefiary to produce this 
 deflagration, and that the matter of pure fire is 
 altogether incapable of effecting it : for though 
 Nitre be expofed to the mod violent degree of fire, 
 even that in the focus of the moft powerful burn- 
 ing-glafs, it will not flame -, nor will that effect ever 
 happen till the Nitre be brought into contact with 
 a Phlogifton properly fo called, that is, the matter 
 of fire exifting as a principle of fome body ; and 
 it is moreover necefiary that this Phlogifton be 
 actually on fire, and agitated with the igneous mo- 
 tion, or elfe that the Nitre itfelf be red-hot, and fo 
 penetrated with fire as to kindle any inflammable 
 matter that touches it. 
 
 This experiment, among others, helps to mew the 
 diftinction that ought to be made between pure ele- 
 mentary fire, and fire become a principle of bodies, 
 to which we have given the name of Phlogifton. 
 
 Before we leave this fubject, we mall obferve that 
 Nitre deflagrates only with fuch fubftances as con- 
 tain the Phlogifton in its fimpleft and pureft form ; 
 fuch as charcoal, fulphur, and the metalline fub- 
 ftances , and that, though it will not deflagrate 
 without the addition of fome combuftible matter, it 
 is neverthelefs the only known body that will burn, 
 and make other combuftibles burn with it, in clofe 
 veffels, without the admifiion of frelh air. 
 
 The Nitrous Acid hath not fo great an affinity 
 with earths and Alkalis as the vitriolic Acid hath 
 with the fame fubftances , whence it follows that the 
 vitriolic Acid decompofes all neutral faltsarifing from 
 a combination of the Nitrous Acid with an earth or 
 an Alkali. The vitriolic Acid expels the Nitrous 
 Acid, unites with the fubftance which ferved it for 
 a bafis, and therewith forms a neutral fait, which is 
 an Alum, a Selenites, or a vitriolated Tartar, ac- 
 cording to the nature of that bafis. 
 
 The
 
 32 E L E M E N T S of f/Jf 
 
 The Nitrous Acid, when thus feparated from its 
 bafis by the vitriolic Acid, is named Spirit of Nitre* 
 or Aqua Fortls. If it be dephlegmated, or contain 
 but little fuperfiuous water, it exhales in reddifh va- 
 pours-, thele vapours, being condenled and collected, 
 form a liquor of a brownim yellow, that incefiamly 
 emits vapours of the fame colour, and of a pungent 
 difagreeable fmell. Thefe characters have procu- 
 red it the names of Smoaking Spirit cf Nitre^ and 
 Tellow Aqua Fortis. This property in the Nitrous 
 Acid, of exhaling in vapours, (hews it to be leis 
 fixed than the vitriolic Acid; for the latter, though 
 ever fo thoroughly dephlcgmated, never yields any 
 vapours, nor has it any fmell. 
 
 . III. Of tbe ACID OF SEA-SALT. 
 
 THE Acid of Sea-Salt is fo called becaufe it is in 
 fact obtained from fuch Sea-Salt as is ufed in our 
 kitchens. It is not certainly known in what this 
 Acid differs from the vitriolic and the nitrous, with 
 regard to its constituent parts. Several of the ableft 
 Chymifts, fuch as Becher and Stahl, are of opinion 
 that the Marine Acid is no other than the Univer- 
 fal Acid united to a particular principle which 
 they call a Mercurial Earth. Concerning this earth 
 we fhall have occafion to fay more, when we come 
 to treat of metallic fubftances : But in the mean 
 time it muft be owned, that the truth of this opi- 
 nion is fo far from being proved by a fufficient 
 number of experiments, that the very exiftence of 
 iuch a mercurial earth is not yet well eftabliihed ; 
 and therefore, that we may not exceed the bounds 
 of our knowledge, we fhall content ourfelves with 
 delivering here the properties which characterize 
 the Acid in queftion, and by which it is diftinguimcd 
 from the two others confidered above. 
 
 When it is combined with abibrbcnt earths, fuch 
 
 as lime and chalk, it forms a neutral fuk that does 
 
 7 not
 
 THEORY of CHYMISTRY. 33 
 
 not cryftallize, and, when dried, attracts the moif- 
 ture of the air. If the abforbent earth be not fully 
 faturated with the Marine Acid, the fait thereby 
 formed has the properties of a fixed Alkali : and 
 this is what made us fay, when we were on the fub- 
 jeft of thole falts, that they might be imitated by 
 combining an earth with an Acid. The Marine 
 Acid, like the reft, hath -not fo great an affinity 
 with earths as with fixed Alkalis. 
 
 When it is combined with the latter, it forms a 
 neutral fait which (hoots into cubical cryftals. This 
 fait is inclined to grow moid in the air, and is con- 
 fequently one of thofc which water diffblves in 
 equal quantities, at leaft as to fenfe, whether it be 
 boiling hot or quite cold. 
 
 The affinity of this Acid with Alkalis and abfor- 
 bent Earths is not fo great as that of the vitriolic 
 and nitrous Acids with the fame fubftances : whence 
 it follows that, when combined therewith, jt may 
 be feparated from them by either of thofe Acids. 
 
 The Acid of Sea-Salt, thus difengaged from the 
 fubftance which ferved it for a bafis, is called Spirit 
 of Salt. When it contains but little phlegm it is 
 of a lemon colour, and continually emits many 
 white, very denfe, and very elaftic vapours ; on 
 which account it is named the Stnoaking Spirit of 
 Salt. Its fmell is not difagreeable, nor much un- 
 like that of faffron j but extremely quick and fuffb- 
 cating when it fmokes. 
 
 The Acid of Sea-Salt, like the other two, feems 
 to have a greater affinity with the Phlogifton, than 
 with fixed Alkalis. We are led to this opinion 
 by a very curious operation, which gives ground to 
 think that Sea-Salt may be decompofed by the pro- 
 per application of a fubftance containing the Phlo- 
 gifton. 
 
 VOL, I. D From
 
 34 ELEMENTS <?/" the 
 
 From the Marine Acid combined with a Phlo- 
 gifton refults a kind of Sulphur, differing from the 
 common fort in many refpefts ; but particularly in 
 this property, that it takes fire of itfelf upon being 
 expofed to the open air. This combination is 
 called Engliflj Pbofphorus y Pbcfpborus of Urine, be- 
 caufe it is generally prepared from urine-, or, only 
 Phofpborus. 
 
 This combination of the Marine Acid with a 
 Phlogifton is not eafily effected ; becaufe it requires 
 a difficult operation in appropriated veflels. For 
 thefe reafons it does not always fucceed ; and Phof- 
 phorus is fo fcarce and dear, that hitherto Chymirts 
 have not been able to make on it the experiments 
 neceiTary to difcover all its properties. If Phof- 
 phorus be fuffered to burn away in the air, a fmall 
 quantity of an acid liquor may be obtained from it, 
 which feems to be fpirit of fait, but either altered, 
 or combined with fome adventitious matter ; for it 
 has fcveral properties that are not to be found in 
 the pure Marine Acid-, fuch as, leaving a fixed 
 fufible fubftance behind it when expofed to a ftrong 
 fire, and being eafily combined with the Phlogifton 
 fo as to reproduce a Phcfphorus. 
 
 Phofphorus refembles fulphur in feveral of its 
 properties : it is foluble in oils ; it melrs with a 
 gentle' heat ; it is very combuftible i it burns with- 
 out producing foot; and its flame is vivid and 
 bhiiOi. 
 
 I'Yom what has been faid of the union of the 
 Acid 'of Sea-Salt with a fixed Alkali, and of the 
 neutral fait refultrng therefrom, it may be concluded 
 'that this neutral fait is no o:her than the common 
 kitchen-falt. Bur it muft be obferved that the fixed 
 'Alkali, which is the natural bafis of the common 
 fair, obtained from fea-water, is of a fort fomewhat 
 dificring from fixed Alkalis in general, and hath 
 certain properties peculiar to itfelf. For, 
 
 3 i. The
 
 T H E O R Y Of CH Y M I S T R Y. 35 
 
 t. The bafis of Sea-Salt differs from other fixed 
 Alkalis in this, that it cryftallizes like a neutral fait; 
 
 2. It does not grow moift in the air : on the con- 
 trary, when expofed to the air, it lofes part of the 
 water that united with it in cryftallization, by which 
 means its cryftals lofe their tranfparency, become* 
 as it were, mealy, and fall into a fine flour. 
 
 3. When combined with the vitriolic Acid to 
 the point of faturation, it forms a neutral fait, dif- 
 fering from vitriolated tartar, firft, in the figure of 
 its cryftals, which are oblong fix-fided folids ; fe- 
 condly, in its quantity of water, which in cryftalli- 
 zation unites therewith in a much greater propor- 
 tion than with vitriolated tartar ; whence it followsj 
 that this fait diflblves in water more readily than 
 vitriolated tartar ; thirdly, in that it flows with a 
 very moderate degree of heat, whereas vitriolated 
 tartar requires a very fierce one. 
 
 If the Acid of Sea-Salt be feparated from its 
 bafis by means of the vitriolic Acid, it is eafy to fee 
 that, when the operation is finifhed, the fait we 
 have been fpeaking of muft be the refult. A fa- 
 mous Chymift, named Glauber, was the firft who 
 extracted the Spirit of Salt in this manner, examined 
 the neutral fait refulting from his procefs, and, 
 finding it to have fome fingular properties, called 
 it his Sal mirabile^ or wonderful Salt: on this ac- 
 count it is ttill called Glauber's Sal miralile^ or 
 plainly Glauber's Salt. 
 
 4. When the bafis of Sea-Salt is combined with 
 the nitrous Acid to the point of faturation, there 
 refults a neutral fait, or a fort of nitre, differing from 
 the common nitre, firft, in that it attracts the moi- 
 fture of the air pretty itron^ly ; and this makes it 
 difficult to cryftaliize : fecund ly, in the figure of its 
 cryftals, which are parallelepipeds; and this has 
 procured it the name of Quadrangular Nitre. 
 
 D 2 Common
 
 36 E L E M E N T s of the 
 
 Common fait, or the neutral fait formed by com- 
 bining the Marine Acid with this particular fort of 
 fixed Alkali, has a tafte well known to every body. 
 The figure of its cryftals is exactly cubical. It 
 grows moift in the air, and, when expofed to the 
 Hre, it burlts, before it melts, into many little 
 fragments, with a crackling noife j which is called 
 the Decrepitation of Sea- Salt. 
 
 That neutral fair mentioned above, which is 
 formed b ; combining the Marine Acid with a com- 
 mon fixed Alkali, and called Sal febrifugum Syhii t 
 hath alfo this property. 
 
 India furnimes us with a faline fubftance, known 
 by the name of Bcrax, which flows very eafily, and 
 then takes the form of glafs. It is of great ufe in 
 facilitating the fufion of metallic fubftances. It 
 poflefies iome of the properties of fixed Alkalis, 
 which has induced certain Chymifts to reprelent it, 
 through miftake, as a pure fixed Alkali. 
 
 By mixing borax with the vitriolic Acid, Mr. 
 Homberg obtained from it a fait, which fublimes in 
 a certain degree of heat, whenever fuch a mixture is 
 made. This fait has very fingular properties ; but its 
 nature is not yet thoroughly underftood. It difTolves 
 in water with great difficulty ; it is not volatile, 
 though it riles by fublimation from the borax. Ac- 
 cording to Mr. Rouelle's obfervation, it rifes then 
 only by means of the water which carries it up : for, 
 when once made, it abides the fierceft fire, flows and 
 vitrifies juft as borax does , provided care be taken 
 to free it previously from moifture by drying it pro- 
 perly. Mr. Homberg called it Sedative Salt? on ac- 
 count of its medical effects. The fedative fait hath 
 the appearance, and fome of the properties, of a neu- 
 tral fait; for it moots into cryftals, and does not 
 change the colour of violets : but it acts the part 
 of an Acid with regard to Alkalis, uniting with 
 them to the point of faturation, and thereby form- 
 
 ing
 
 THEORY ^CHYMISTRY. 37 
 
 ing a true neutral fait. It alfo acts like the Acid 
 of vitriol on all neutral falts , that is, it discharges 
 the Acid of fuch as have not the vitriolic Acid in 
 their compofition. 
 
 Since Mr. Homberg's time it hath been difcover- 
 ed, that a fedative fait may be made either with the 
 nitrous or with the marine Acid ; and that fublima- 
 tion is not necefiary to extract it from the borax, 
 but that it may be obtained by cryftallization only. 
 For this latter difcovery we are indebted to Mr. 
 Geoffrey, as we are to Mr. Lemery for the former. 
 
 Since that time M. Baron d'Henouville, an able 
 Chymift, hath (hewn that a fedative fait may be 
 obtained by the means of vegetable Acids ; and 
 hath lately demonftrated, in fome excellent papers 
 publifhed in the collection of Memoirs written by 
 the correfpondents of the Academy of Sciences, 
 that the fedative fait exifts actually and perfectly in 
 the borax, and that it is not produced by mixing 
 Acids with that faline fubftance, as it feems all the 
 Chymifts before him imagined. This he proves 
 convincingly from his analyfis of borax, (which 
 thereby appears to be nothing elfe but the fedative 
 fait united with that fixed Alkali which is the bafis 
 of Sea-Salt) and from his regenerating the fame 
 borax by uniting together that Alkali and the feda- 
 tive fait : a proof the mod complete that can pofTi- 
 bly be produced in natural philofophy, and equi- 
 valent to demonftration itfelf. 
 
 In order to finifh what remains to be faid upon 
 the feveral forts of faline fubftances, we fhould now 
 fpeakof the Acids obtained from vegetables and ani- 
 mals, and alfo of the volatile Alkalis : but, feeing 
 thefe faline fubftances differ from thofe of which we 
 have already treated, only as they are varioufly alter- 
 ed by the unions they have contracted with certain 
 principles of vegetables and animals, of which no- 
 thing has been yet faid, it is proper to defer being 
 
 D 3 particular
 
 38 ELEMENTS o/" the 
 
 particular concerning them, till we have explained 
 thofe principles. 
 
 CHAP. V. 
 Of LIME. 
 
 AN Y fubftance whatever, that has been roaflcc] 
 a conlidrrable cirrr: in a (Irong fire without 
 melting, is commonly c;i, cl a Calx. Stones and 
 metals are the principal J objects that have the pro- 
 perty of being converted into Cakfs. We fhall 
 ireat of Metalline Calces in a fubfequent chapter, 
 and in this c^.,.ine ourfelves to the Calx of Stone^ 
 known by the name of Lime. 
 
 In treating of earths in general we obferved, 
 that they may be divided into two principal kinds j 
 one of which actually and properly flows when ex- 
 pofed to the action of fire, and turns to glafs , 
 whence it is called a fujiblt or verifiable earth ; the 
 other refifts the utrnoft force of fire, and is therefore 
 faid to be an uvfufible or unvitrifiable earth. The 
 latter is allb not uncommonly called calcinable earthj 
 though fundry forts of unfufible earths are inca- 
 pable of acquiring by the action of fire all the 
 qualities of 'calcined earth, or Lime properly fo called ; 
 fuch earths are particularly diftinguifhed by the 
 denomination of refractory earths. 
 
 As the different forts of (tones are nothing more 
 than compounds of different earths, they have the 
 fame properties with the earths of which they are 
 compofed, and may like them, be divided intofu- 
 fible or verifiable, and unfufible or calcinable. The 
 fufible ftones are generally denoted by the name of 
 Flints , the calcinable ftones, again, are the feveral 
 lores of marbles, cretaceous ftones, thofe commonly 
 
 calle4
 
 THEORY of C H Y M i s T R Y. 39 
 
 called free-ftones, &c. fome of which, as they, make 
 the beft Lime, are, by way of eminence, called 
 Lime-ftones. Sea-fhells alfo, and ftones that abound 
 with foflile fhells, are capable of being burnt to 
 Lime. 
 
 All thefe fubftances, being expofed, for a longer 
 or fhorter time, as the nature of each requires, to 
 the violent action of fire, are faid to be calcined. By 
 calcination they lofe a confiderable part of their 
 weight, acquire a white colour, and become friable 
 though ever fo folid before ; as, for rnftance, the 
 very hardeft marbles. Thefe fubftances, when 
 thus calcined, take the name of Quick Lime. 
 
 Water penetrates Quick Lime, and rufhes into it 
 with vaft activity. If a lump of newly calcined Lime 
 be thrown into water, it inftantly excites almoft as 
 great a noife, ebullition, and fmoke, as would be 
 produced by a piece of red-hot iron , with fuch a 
 degree of heat too, that, if the Lime be in due. pro- 
 portion to the water, it will fet fire to combuftible 
 bodies ; as hath unfortunately happened to veffels 
 laden with Quick Lime, on their ipringing a fmall 
 leak. 
 
 As foon as Quick Lime is put into water, it 
 fwells, and falls afunder into an infinite number of 
 minute particles : in a word, it is in a manner dii- 
 folved by the water, which forms therewith a fort 
 of white pafte called Slacked Lime. 
 
 If the quantity of water be confiderable enough 
 for the Lime to form with it a white liquor, this 
 liquor is called LacCakis\ which, being left fome 
 time to fettle, grows clear and tranfparent, the Lime 
 which was Impended therein, and occafioned its 
 opacity, fubfiding to the bottom of the veiTel. 
 Then there forms on the furface of the liquor a cry- 
 ftalline pellicle, fomewhat opaque and dark colour- 
 ed, which being fkimmed off is reproduced from 
 time to time. This matter is called Cremor Calcis. 
 
 D 4 Slacked
 
 40 E L E M E N T S of the 
 
 Slacked Lime gradually grows dry, and takes 
 the form of a folid body, but full of cracks and 
 dsftitute of firmneis. The event is different when 
 you mix it up, while yet a pafte, with a certain 
 Quantify of uncalcined flony matter, fuch as fand 
 for example : then it takes the name of Mortar, and 
 gradually acquires, as it grows drier and older, a 
 hardnefs equal to that of the bed (tones. This is 
 a very fingular property of Lime, nor is it eafy to 
 account for it : but it is a beneficial one -, for every 
 body knows the ufe of mortar in building. 
 
 Quick Lime attracts the moiflure of the air, in 
 the Lime manner as concentrated acids, and dry 
 fixed alkalis , but not in fuch quantities as to render 
 it fluid : it only falls into extremely fmall particles, 
 takes the form of a fine powder, and the title of 
 Lime flacked in tic air. 
 
 Lime once flacked, however dry it may after- 
 wards appear, always retains a large portion of the 
 water it had imbibed ; which cannot be feparated 
 from it again but by means of a violent calcination, 
 feeing fo recalcined it returns to be Quick Lime, 
 recovering all its properties. 
 
 Befides this great affinity of Quick Lime with 
 water, which difcovers a faline character, it has 
 feveral other faline properties, to be afterwards ex- 
 amined, much refembling thofe of fixed alkalis. In 
 Chymiftry it acts very nearly as thofe falts do, and 
 may be confidered as holding the middle rank be- 
 tween a pure abforbent earth and a fixed alkali : 
 and this hath induced many Chymifts to think that 
 Lime contains a true fait, to which all the proper- 
 ties it pofTefles in common with falts may be attri- 
 buted. 
 
 But as the chymical examination of this fubject: 
 hath long been neglected, the exiftence of a 
 faline fubftance in Lime hath been long doubt- 
 ful. Mr. du Fay, author of forrie excellent chy- 
 5 mical
 
 THEORY of CHYMISTRY. 41 
 
 mical experiments, was one of the firft who ob- 
 tained a Salt from Lime, by lixiviating it with a 
 great deal of water, which he afterwards evaporated. 
 But the quantity of fait he obtained by that means 
 was very fmall ; nor was it of an alkaline nature, 
 as one would think it fliould have been, confidering 
 the properties of Lime. Mr. du Fay did not carry 
 his experiments on this fubject any further, pro- 
 bably for want of time ; nor did he determine of 
 what nature the fait was. 
 
 Mr. Malouin had the curiofity to examine this 
 fait of Lime, and foon found that it was nothing elfc 
 but what was above called Cremor Calcis. He found 
 moreover, that, by mixing a fixed alkali with 
 Lime-water, a vitriolated tartar was formed ; that, 
 by mixing therewith an alkali like .the bafis of fea 
 fak, a Glauber's fait was produced ; and laftly, by 
 combining Lime with a fubftance abounding in 
 phlogifton he obtained a true fulphur. Thefe very 
 ingenious experiments prove to a demonftration 
 that the- vitriolic acid conftitutes the fait of Lime: 
 for, as hath been mewn, no other acid is capable of 
 forming fuch combinations. On the other hand, 
 Mr. Malouin, having forced the vitriolic acid of 
 this fait to combine with a phlogifton, found its 
 bafis to be earthy, and analogous to that of the 
 felenites : whence he concluded that the fait of 
 Lime is a true neutral fait, of the fame kind as the 
 felenites. Mr. Malouin tells us he found feveral 
 other falts in Lime. But as none of them was a 
 fixed alkali, and as all the faline properties of Lime 
 have an affinity with thole of that kind of fait, 
 there is great reafon to think that all thofe falts are 
 foreign to Lime, and that their union with it is 
 merely accidental. 
 
 I myfelf have made feveral experiments in order 
 to get fome infight into the faline nature of Lime, 
 
 and
 
 42 ELEMENTS 
 
 and fhall here produce the refult with all pofiiblc 
 concifenefs. 1 took feveral ftones of different 
 kinds, fome of which produced by calcination a 
 very ftrong Lime, and others but a very weak one. 
 Thefe I impregnated wjth different faline fubftances, 
 acids, alkalis, and neutrals, and then expofed them 
 all to the fame degree of fire, which was a pretty 
 ftrong one, and long enough continued to have 
 made very good Lime of ftones the moft difficult 
 to calcine. The confequence was, that, in the firft 
 place, thofe ftones which naturally- made but a weak 
 Lime were no; by this procefs 'converted into a 
 ftronger Lime-, and, moreover, that none of thefe 
 ftones, even fuch as would naturally have produced 
 the moft active Lime, had acquired the properties 
 of Lime. Thefe experiments I varied many ways, 
 employing different proportions of faline matters, 
 and almoil every pofjible degree of fire, and con- 
 ftantly o.bferved, after calcination, that all thofe 
 ftones were fo much the further from the nature of 
 Lime, as they had been combined with larger dofes 
 of falts. Among thofe which were impregnated with 
 the greateft proportion of falts, and had fuffered the 
 greateft violence of fire, I obferved fome that had 
 begun to flow, and were in a manner vitrified. 
 Now as the fame fubjecl: cannot be, at one and the 
 fame time, in the ftate of glafs and of Lime too ; 
 as a body cannot approach to one of thefe ftates but 
 in proportion as it recedes from the other , and as 
 falts in general difpofe thofe bodies to fufion and 
 vitrification which are in themfelves the moft averfe 
 to either, I concluded from my experiments, that 
 the faline fubftances J ufed had, by acting as fluxes 
 upon the ftones, prevented their calcination ; that 
 confequently we may fufpect there is no faline 
 matter in the compofition of Lime, as Lime ; and 
 that Lime does not owe its faline and alkaline pro- 
 perties
 
 THEORY C/CHYMISTRY. 43 
 
 perties to any fait , or at lead that if it does owe 
 ithofe properties to a fait, inch fait mud be na 
 rurally and originally combined with the matter of 
 the (lone in fo juft a proportion, that it is impofiible 
 to increafe the quantity thereof without prejudicing 
 the Lime, and depriving it in fome meafure of its 
 virtue. This theory agrees perfectly with the il*- 
 Juftrious Stahl's opinion ; for he thinks, as we ob- 
 ferved in difcourfing of Salts in general, that every 
 faline fubftance is but an earth combined in a cer- 
 tain manner with water. This notion he applies to 
 Lime, and fays that fire only fubtilizes and atte- 
 nuates the earthy matter, and thereby renders it 
 capable of uniting with water in fuch a manner, 
 that the refult of their combination mail be a fub- 
 ftance having faline properties ; and that Lime ac- 
 cordingly never acquires thefe properties till it be 
 combined with water. 
 
 I have dwelt longer on the Salt of Lime than I 
 (hall on any other particular ; becaufe the fubjed, 
 though in itfelf of great importance, has hitherto 
 been but little attended to, and becaufe the expe- 
 riments here recited are entirely new. 
 
 Lime unites with all acids, and in conjunction 
 with them exhibits various phenomena. 
 
 The vitriolic acid poured upon Lime difTolves it 
 with effervefcence and heat. From this mixture 
 there exhales a gre^t quantity of vapours, in Imell 
 and colour perfectly like thofe of fea-falt ; from 
 which however they are found to be very different 
 when collected into a liquor. From this combina- 
 tion of the vitriolic acid with Lime arifes a neutral 
 fait, which fhoats into cryftals, and is of the fame 
 kind with the felenitic fait obtained from Lime by 
 Mr. Malouin. 
 
 The nitrous acid poured upon Lime difTolves it 
 in like manner with effervefcence and heat : but the 
 folution is tranfparent, and therein differs from the 
 
 former,
 
 44 ELEMENTS 0/*//k? 
 
 former, which is opaque. From this mixture therfc 
 ariies a neutral laic, which does not cryftallize, and 
 has withal the very fingular property of being vola- 
 tile, and rifing wholly by diftillation in a liquid 
 form. This phenomenon is fo much the more re- 
 markable, as Lime, the bafts of this fait, is one of 
 the mod fixed bodies known in Chymiftry. 
 
 With the acid of fea-falt Lime forms alfo a 
 (Tngular fort of fait, which greedily imbibes the 
 moifture of the air. We mail have occafion to take 
 further notice of it in another place. 
 
 Thefe experiments made on Lime with acids 
 are likewife quite new. We are indebted for them 
 to Mr. Du Hamel of the Academy of Sciences, 
 whole admirable Memoirs on leveral fubjefts mew 
 his extenfive knowledge in all parts of Natural 
 Philofophy. 
 
 Lime applied to fixed alkalis adds confiderably 
 to their cauftic quality, and makes them more pene- 
 trating and active. An alkaline lixivium in which 
 Lime hath been boiled, being evaporated to dry- 
 nefs, forms a very cauftic fubftance, which flows in 
 the fire much more eafily, attracts and retains 
 moifture much more ftrongly, than fixed alkalis 
 that have not been fo treated. An alkali thus 
 acuated by Lime is called the Cauftic Stone, or Po- 
 tential Cautery ; becaufe it is employed by furgeons 
 to produce efchars on the fkin and cauterize it. 
 
 CHAP.
 
 THEORY cf CRY MIST KY. 45 
 
 CHAP. VI. 
 
 Of Metallic Subftances in general. 
 
 METALLIC Subftances are heavy, glit- 
 tering, opaque, fufible bodies. They cort- 
 lift chiefly of a verifiable earth united with the 
 phlogifton. 
 
 Several Chymifts infift on a third principle in 
 thefe bodies, and have given it the name of Mer- 
 curial earth -, which, according to Becher and Stahl, 
 is the very fame that being combined with the vi- 
 triolic acid forms and characterizes the acid of fea- 
 falt. The exiftence of this principle hath not yet 
 been demonilrated by any decifive experiment ; bur 
 we fhall mew that there are pretty itrong reafons 
 for admitting it. 
 
 We fhall begin with mentioning the experiments 
 which prove Metallic Subftances to confift of a 
 verifiable earth united with the phlogifton. The 
 firft is this : if they be calcined in fuch a manner as 
 to have no communication with any inflammable 
 matter, they will be fpoiled of all their properties, 
 and reduced to an earth or calx, that has neither 
 the fplendour nor the ductility of a metal, and in a 
 ftrong fire turns to an actual glafs, inftead of flow- 
 ing like a metal. 
 
 The fecond is, that the calx or the glafs refult- 
 ing from a metal thus decompofed, recovers all its 
 metalline properties by being fufed in immediate 
 contact with an inflammable fubftance, capable of 
 reftoring the phlogifton of which calcination had 
 deprived it. 
 
 On this occafion we muft obferve that Chymifts 
 have not yet been able, by adding the phlogifton, to 
 
 give.
 
 6 L E M E N T S of the 
 
 give the properties of metals to all forts of vitrifiabld 
 earths indifcriminately -, but to fuch only asoriginally- 
 made a part of fome metallic body. For example, 
 a compound cannot be made with the phlogiftori 
 and fand that fhall have the lead refemblance of a 
 metal : and this is what feems to point out the 
 reality of a third principle, as necefiary to form the 
 metalline combination. This principle may pro- 
 bably remain united with the vitrifiable earth of a 
 metallic fubftance,when reduced to a glals -, whence 
 it follows, that fuch vitrified metals require only 
 the addition of a phlogifton to enable them to ap- 
 pear again in their priftine form. 
 
 It may be inferred from another experiment* 
 that the calx and the glafs of a metal are not its 
 pure vitrifiable earth, properly fo called : for by 
 repeated or long continued calcinations, fuch a 
 calx or glafs may be rendered incapable of ever 
 refuming the metalline form, in whatever manner 
 the phlogifton be afterwards applied to it ; fo that 
 by this means it is brought into the condition of a 
 pure vitrifiable earth, abfolutely free from any 
 mixture. Thofe Chymifts who patronife the Mer- 
 curial earth, produce many other proofs of the 
 exiftence of that principle in metallic iubftances ', 
 but they would be mifplaced in an elementary 
 treatife like this. 
 
 When by adding the phlogifton to a metallic 
 glafs we reftore it to the form of a metal, we are 
 laid to reduce^ refufcitate, or revivify that metal. 
 
 Metallic fubftances are of different kinds, and 
 are divided into Metals and Senti- metals. 
 
 Thole are called Metals which, beftdes their 
 metalline fplendour and appearance, are alfo mal- 
 leable , that is, have the property of ftretching 
 under the hammer, and by that means of being 
 wrought into different forms without breaking. 
 
 Thofe
 
 of CHYMIST*RY. 47 
 
 Thofe which have only the metalline fplendour 
 and appearance, without malleability, are called 
 Semi-metals. 
 
 Metals are alfo- further fubdivided into two forts ; 
 viz. Perfeft and ImperfeR Metals. 
 
 The Perfect Metals are thofe which fuffer no 
 damage or change whatever by the moft violent 
 and moft lading action of fire. 
 
 The Imperfect Metals are thofe which by the 
 force of fire may be deprived of their phlogifton, 
 and confequently of their metalline form. 
 
 When but a moderate degree of fire is employed 
 to deprive a Metal of its phlogifton, the metal is 
 faid to be calcined and then it appears in the form 
 of a powdered earth, which is called a Calx : and 
 this metalline calx being expofed to a more violent 
 degree of fire melts and turns to glafs. 
 
 Metallic Subftances have an affinity with acids : 
 but not equally with all , that is, every Metallic 
 Subftance is not capable of uniting and joining with 
 every acid. 
 
 When an acid unites with a Metallic Subftance 
 there commonly arifes an ebullition, attended with 
 a kind of hiding noife and fuming exhalations. By 
 degrees, as the union becomes. more perfect, the 
 particles of the metal combining with the acid be- 
 come invifible : this is termed Dilution ; and when 
 a metalline mafs thus difappears in an acid, the 
 metal is faid to be diffbhed by that acid. It is pro- 
 per to obfcrve that acids acl: upon metalline lub- 
 ftances, in one refpeft, juft as they do upon al- 
 kalis and abforbent earths : for an acid cannot take 
 up above fuch a certain proportion thereof as is 
 fufHcient to faturate it, to deftroy feveral of its pro- 
 perties, and weaken others. For example, when 
 an acid is combined with a metal to the point of 
 faturation, it lofes its tafte, does not turn the blue 
 colour of a vegetable red, and its affinity with water 
 
 is
 
 48 E L E M E N T S ?/ the 
 
 is confiderably impaired. On the other hand, Me- 
 talline Subftances, which when pure are incapable 
 of uniting with water, by being joined with an 
 acid acquire the property of diflblving in water. 
 Thefe combinations of Metalline Subftances with 
 acids form different forts of neutral falts ; fome of 
 which have the property of fliooting into cryftals, 
 while others have it not : moft of them, whea 
 thoroughly dried, attract the moifture of the air. 
 
 The affinity which Metalline fubftances have with 
 acids is lefs than that which abforbent earths and 
 fixed alkalis have with the fame acids: fo that all 
 metalline falts may be decompounded by one of 
 thefe fubftances, which will unite with the acid, 
 and precipitate the metal. 
 
 Metalline Subftances thus feparated from an 
 acid folvent are called Magift&ries, and Precipitates, 
 of metals. None of thefe precipitates, except thofc 
 of the perfect metals, retain the metalline form : 
 moft of their phlogifton hath been deftroyed 
 by the folution and precipitation, and muft be re- 
 ftored before they can recover their properties. In 
 fhort, they are nearly in the fame ftate with metal- 
 line fubftances deprived of their phlogifton by cal- 
 cination , and accordingly fuch a precipitate is 
 called a Calx. 
 
 A metalline calx prepared in this manner lofes a 
 greater or a lefs portion cf its phlogifton, the 
 more or lefs effectually and thoroughly the metal- 
 line fubftance, of which it made a part, was dif- 
 folved by the acid. 
 
 Metallic Subftances have affinities with each other 
 which differ according to their different kinds : but 
 this is not univerfal , for fome of them are incapable 
 of any fort of union with fome others. 
 
 It muft be obicrvtd that Metallic Subftances will 
 not unite, except they be both in a fimilar ftate ; that 
 is, both in a Metalline form a or booh in the form 
 
 of
 
 THEORY C/*CHYMISTRY. 49 
 
 of a Glafs , for a metalline fubftance retaining its 
 phlogifton cannot contract an union with any me- 
 tallic glafs, even its own. 
 
 C II A P, VII. 
 Of METALS. 
 
 THERE are fix Metals, of which two nre 
 Perfect and four Imperfect. The perfect 
 Metals are Gold and Silver ; the others are Copper, 
 Tin, Lead, and Iron. Some Chymifts admit a 
 feventh Metal, to wit, Quick-filver : but as it is 
 not malleable, it has been generally confidered as 
 a metallic body of a particular kind. We mail foon 
 have occafion to examine it more minutely. 
 
 The ancient Chymifts, or rather the Alchymifts, 
 who fancied ar certain relation or analogy between 
 Metals and the Heavenly Bodies, beftowed on the 
 feven Metals, reckoning Quick- filver one of them, 
 the names of the feven Planets of the Ancients, ac- 
 cording to the affinity which they imagined they ob- 
 ferved between thofe feveral bodies. Thus Gold was 
 called Sol, Silver Luna, Copper Venus, Tin Jupiter, 
 Lead Saturn, Iron Mars, and Quick-filver Mercury. 
 Though thefe names were affigned for reafons merely 
 chimerical, yet they ftill keep their ground ; ib 
 that it is not uncommon to find the Metals called by 
 the names, and denoted by the characters, ot the 
 Planets, in the writings evtn of the bed Chymifts. 
 Metals are the heavieft bodies known in nature. < 
 
 . I. Of G O L D. 
 
 GOLD is the heavieft of all Metals. The arts 
 
 of wire-drawing and gold-beating fhew its won- 
 
 VOL, I. E dcrful
 
 ^O E L E M E N T S of the 
 
 derful ductility. The greateft violence of fire ig 
 not able to produce any alteration in it. Indeed Mr. 
 Homberg, a famous Chymift, pretended that he had 
 made this metal fume, and even vitrified it, by ex- 
 pofing it to the focus of one of the beft burning 
 glafTes, known by the name of the Lens of the 
 
 *" * 
 
 Palais Royal : but there are very good reafons for 
 calling in queftion the experiments he made on this 
 occafion, or rather for thinking that he was quite 
 miftaken. For, 
 
 1. No man hath fince been able to vitrify Gold, 
 though feveral good Experimenters have afliduoufly 
 tried to effect it, by cxpofing it to the focus of the 
 fame lens, and of other burning-glaffes ftill ftronger. 
 
 2. It hath been obferved that though Gold, when 
 expofed to the focus of thofe glafies, did indeed 
 emit fome vapours and decreafe in weight-, yet thole 
 vapours being carefully collected on a piece of pa- 
 per, proved to be true Gold, in no degree vitrified, 
 and which confequently had fuffered no change but 
 that of being carried away by the violence of the 
 heat, its nature not being in the lead altered. 
 
 3. The fmall portion of vitrified matter, which 
 was formed on the arm that fupported the Gold in 
 Mr. Homberg's experiment, may have come either 
 from the arm itfelf, or rather from fome heteroge- 
 neous particles contained in the Gold ; for it is al- 
 moft impofiible to have it perfectly pure. 
 
 4. Neither Mr. Homberg, nor any that have re- 
 peated his experiment, ever reduced this pretended 
 glafs of Gold by reftoring its phlogifton, as is done 
 with other metallic glafles. 
 
 5. To render the experiment decifive, the whole 
 mafs of Gold employed ought to have been vi- 
 trified i which was not the cafe. 
 
 Neverthelefs I do not pretend that this metal is 
 
 in its own nature abfolutely indeftruclible, and un- 
 
 7 verifiable t
 
 THEORY ^CHYMISTRY. 51 
 
 Vitrifiable : but there is reafon to think that nobody 
 hath hitherto found the means of producing thofe 
 effects on it, probably for want of a fufficient degree 
 of fire -, at lead the point is very doubtful. 
 
 Gold cannot be diffolved by any pure acid : but 
 if the acid of nitre be mixed with the acid of fea- 
 falt, there refults a compound acid liquor, with 
 which it has fo great an affinity that it is capable 
 of being perfectly difiblved thereby. The Chy- 
 mifts have called this folvent Aqita Regis, on ac- 
 count of its being the only acid that can diflblve 
 Gold, which they confider as the King of Metals. 
 The folution of Gold is of a beautiful orange 
 colour. 
 
 If Gold diflblved in aqua regis be precipitated 
 by an alkali or an abforbent earth, the precipitate 
 gently dried, and then expofed to a certain dtgree 
 of heat, is inftantly difperfed into the air, with 
 a moft violent explofion and noife : Gold thus 
 precipitated is therefore called Aurum Fulminans. 
 But ifjhe precipitated Gold be carefully wafhed in 
 plenty of water, fo as to clear it of all the adhe- 
 ring faline particles, it will not fulminate ; but may 
 be melted in a crucible without any additament, 
 and will then appear in its ufual form. The acid of 
 vitriol being poured on aurum fulminant 1 kewife 
 deprives it of its fulminating quality. 
 
 Gold does not begin to flow till it be red-hot like 
 a live coal. Though it be the moft malleable and 
 moft ductile of all metals, it has the fingular pro- 
 perty of lofing its ductility more eafily than any 
 of them : even the fumes of charcoal are fufficiertc 
 to deprive it thereof, if they come in contact with 
 it while it is in fufion. 
 
 The malleability of this metal, and indeed of all 
 the reft, is alfo confiderably diminiihed by expo- 
 fing it fuddenly to cold when it is red-hot ; for 
 
 E 2 example,
 
 2 E L E M E N T S of the 
 
 example, by quenching it in water, or even barely 
 expofing it to the cold air. 
 
 The way to reftore ductility to Gold, when bit 
 by its coming in contact with the vapour of coals, 
 and in general to any metal rendered leis malleable 
 by being fuddenly cooled, is to heat it again, to 
 keep it red-hot a confiderable time, and then to 
 let it cool very flowly and gradually , this opera- 
 tion frequently repeated will by degrees much in- 
 creafe the malleability of a metal. 
 
 Pure fulphur hath no effect on Gold ; but being 
 combined with an alkali into a hepar fulphuris, it 
 unites therewith very readily. Nay, ib intimate 13 
 their union, that the Gold by means thereof becomes 
 foluble in water ; and this new compound of Gold 
 and liver of fulphur, being difiblved in water, will 
 pals through the pores of brown paper without 
 fuffering any decompofition -, which does not hap- 
 pen, at leail in fuch a manifeft degree, to other 
 metallic fubftances diflblved by liver of fulphur. 
 
 Aurum fulminans mixed and melted with flower 
 of fulphur loles its fulminating quality : which 
 arifes from hence, that on this occalion the fulphur 
 burns, and its acid, which is the fame with the 
 vitriolic, being thereby fet at liberty becomes ca- 
 pable of acting upon the Gold as a vitriolic acid 
 would , which, as was faid above, deprives the 
 Gold of its fulminating quality. 
 
 . II. Of SlLVE R. 
 
 NEXT to Gold, Silver is the moft perfect metal. 
 Like Gold itrefifts the utmoft violence of fire, even 
 that in the focus of a burning-glafs. However it 
 holds only the fecond place among metals , becaufe 
 it is lighrer than Gold by almoft one half-, is alfo 
 fomewhat lefs ductile; and laftly, becaufc it i.s 
 acted upon by a greater number of folvents. 
 
 Yet
 
 THEORY of CHYMISTRY. 53 
 
 Yet Silver hath one advantage over Gold, namely 
 that of being a little harder ; which makes it allb 
 more fonorous. 
 
 This metal, like Gold, begins to flow when it 
 is fo thoroughly penetrated by the fire as to appear 
 ignited like a live coal. 
 
 While this metal is in fufion, the immediate 
 contadt of the vapour of burning coals deprives it 
 almoft entirely of its malleability, in the fame man- 
 ner as we obferved happens to Gold : but both thefe 
 metals eafily recover that property by being melted 
 with nitre. 
 
 The nitrons acid is the true folvent of Silver, 
 and being fomewhat dephlegmated will very readily 
 and eafily take up a quantity of Silver equal in 
 weight to itfelf. 
 
 Silver thus combined with the nitrous acid forms 
 a metallic fait which moots into cryftals, called by 
 the name of Lunar Cryftals, or Cryftals of Silver. 
 
 Thefe cryftals are moft violently cauftic : applied 
 to the-fkin the'y quickly affect it much as a live 
 coal would ; they produce a blackifh efchar, cor- 
 roding and entirely deftroying the parts they 
 touch. Surgeons ufe them to eat away the proud 
 fungous flefh of ulcers. As Silver united with the 
 nitrous acid hath the property of blackening all 
 animal fubftances, a folution of this metallic fait is 
 employed to dye hair, or other animal matters, of 
 a beautiful and durable black. 
 
 Thefe cryftals flow with a very moderate heat, 
 and even before they grow red. Being thus melted 
 they form a blackim mafs j and in this form they 
 are ufed by Surgeons, under the title of Lapis In- 
 fernalis, Infernal Stone, or Lunar Cauftic. 
 
 Silver is alfo diffolved by the vitriolic acid : but 
 then the acid muft be concentrated,- and in quantity 
 double the weight of the Silver , nor will the fohu 
 Uon fucceed without a considerable degree of heat. 
 
 E 3 Spirit
 
 J4- E L E M E N T S of the 
 
 Spirit of fait and aqua regis, as well as the other 
 acids, are incapable of difiblving this metal ; at 
 lead in the ordinary way. 
 
 Though Silver be not foluble in the acid of fea- 
 fait, nor'eafily in the acid of vitriol, as hath juft 
 been obiVrved, it doth not follow that it hath but a 
 weak affinity with the latter, and none at all with 
 the former : on the contrary it appears from ex- 
 periment that it hath with thcie two acids a much 
 greater affinity than with the acid of nitre : which 
 js fingular enough, confidering the facility with 
 which this laft acid diflblves it. 
 
 'i'iie experiment which proves the fact, is this. 
 To a folutnn of Silver in the nitrous acid, add the 
 acid either of vitriol or of lea- felt, and the Silver 
 will inttantly quit its nitrous folvent to join with the 
 fuperadded acid. 
 
 Silver thus united with the vitriolic or the marine 
 acid is lefs foluble in water than when combined 
 with the nitrous acid : and for this rcafon it is, that 
 when either of thefe two acids is added to a folution 
 of Silver, the liquor immediately becomes white, 
 and a precipitate is formed, which is no other than^ 
 the Silver united with the precipitating acid. It 
 the precipitation be effected by the vitriolic acid, 
 the precipitate will dilappear upon adding a fuffi- 
 cient quantity of water, becaufe there will then be 
 water enough to difiblve it. But the cafe is not 
 the fame when the precipitation is made by the 
 marine acid : for Silver combined therewith is 
 fearer foluble in water. 
 
 This Precipitate of Silver procured by means of 
 the marine acid is very eafily fufed, and when 
 fuled changes to a fubftance in fome meafure tran- 
 fparent and' flexible , which hath occafioned it to be 
 called by the name of Luna Cornea. If it be pro^ 
 pofed to decompound this luna cornea^ that is, to 
 feparate the marine acid from the Silver with which 
 
 it
 
 HYMISTRY. 55 
 
 it is united, the luna cornea muft be melted along 
 with fatty and abforbent matters, with which the 
 acid will unite, and leave the metal exceeding pure. 
 
 It muft be obferved that if, inftead of the marine 
 acid, fea-falt in fubftance be added to a folution 
 of Silver in the nitrous acid, a Precipitate is alfo 
 produced, which by fufion appears to be a true luna 
 cornea. The reafon is, that the fea-falt is decom- 
 pofed by the nitrous acid, which feizes its bafis, 
 as having a greater affinity therewith than its own 
 acid hathj and this acid being confequently dif- 
 cngaged and fet at liberty unites with the Silver, 
 which, as has been (hewn, has a greater affinity 
 with it than with the nitrous acid. This is an in- 
 ftance of decompofition effected by means of one 
 of thofe double affinities mentioned by us in our 
 feventh propofition concerning Affinities. 
 
 From what hath been already faid it is clear, 
 that all thefe combinations of Silver with acids may 
 be decompounded by abforbent earths and by fixed 
 alkalis ; it being a general law with regard to all 
 metallic fubftarices. We mall not therefore repeat 
 this obfervation when we come to treat of the other 
 metals , unlefs fome particular occafion require it. 
 
 With regard to Silver I muft take notice that, 
 when feparated by thefe means from the acids in 
 which it was diffolved, it requires nothing but 
 fimple fufion to reftore it to its ufual form ; becaufe 
 it does jiot, any more than Gold, lofe its phlogifton 
 by thofe folutions and precipitations. 
 
 Silver unites with fulphur in fufion. If this 
 metal be only made red-hot in a crucible, and 
 fulphur be then added, it immediately flows; 
 the fulphur acting as a flux to it. Silver thus* 
 united with fulphur forms a mafs that may be 
 cut, is half malleable, and hath nearly the colour 
 and confiftence of Lead. If this fulphurated Silver 
 be kept a long time in fufion, and in a great decree 
 
 E^J O 
 
 4 of
 
 56 E L E M E N T S of the 
 
 of heat, the fulphur flies off and leaves the Silver 
 pure. But if the fulphur be evaporated by a vio- 
 lent heat, it carries off with it part of the Silver. 
 
 Silver unites and mixes perfectly with Gold in 
 fufion. The two metals thus mixed form a com- 
 pound with properties partaking of both. 
 
 Metallurgists have hitherto fought in vain for a 
 perfectly good and eafy method of feparating thefe 
 two metals by the dry way only : (this term is ufed 
 to fignify all operations performed by fufion :) but 
 they are conveniently enough parted by the moijl 
 *'.iat is, by acid folvents. This method is 
 founded on thtr above-mentioned properties of Gold 
 and Silver with refpect to acids. It hath been 
 fhewn that aqua regis only will diflblve Gold ; 
 that Silver, on the contrary, is not foluble by aqua 
 regis t and that its proper folvent is the acid of 
 nitre : confequently, when Gold and Silver are 
 mixed together, if the compound mafs be put into 
 aqua fortis, this acid will take up all the Silver, 
 without diffolving a particle of the Gold, which 
 will therefore remain pure j and by this means the 
 defired feparation is effected. This method, which 
 is commonly made ufe of by Goldfmiths and in 
 Mints, is called the Parting JJJay. 
 
 It is plain that if aqua regis were employed in- 
 flead of aqua fortis, the feparation would be 
 equally effected , and that the only difference be- 
 tween this procefs and the former would confift 
 in this, that now the Gold would be diffolvcd, and 
 the Silver remain pure. But the operation by aqua 
 fortis is preferable ; becaufe aqua regis does take 
 up a little Silver, whereas aqua fortis hath not the 
 lead effect on Gold. 
 
 It muft be obferved that when Gold and Silver 
 are mixed together in equal parts they cannot be 
 parted by the means of aqua fortis. To enable 
 the aquafortis to act duly on the Silver, this metal 
 
 mud
 
 THEORY of CHYMISTRY. 57 
 
 muft be, at lead, in a triple proportion to the Gold, 
 If it be in a lefs proportion, you muft either employ^ 
 aqua regis to make the reparation, or, if you prefer 
 the ufe of aqua fortis, melt the metalline mafs, 
 and add as much Silver as is neceflary to make up 
 the proportion above-mentioned : and hence this 
 Procefs is called Quartatwn. 
 
 This effect, which is pretty fingular, probably 
 arifes from hence, that when the Gold exceeds or 
 even equals the Silver in quantity, the parts of both 
 being intimately united, the former are capable of 
 coating over the latter, and covering them ib as to 
 defend them from the aftion of the aqua fortis \ 
 which is not the cafe when there is thrice as much 
 Silver as Gold. 
 
 There is one thing more to be taken notice of 
 with regard to this procefs , which is, that per- 
 fectly pure aqua Jcrtis is rarely to be met with, 
 for two reafons ; firft, it is difficult in making it 
 wholly to prevent the riling of the medium em- 
 ployed to difengage the nitrous acid -, that is, a 
 little of the vitriolic acid will mix with the vapours 
 of the aqua fortis : fecondly, unleis the faltpetre 
 be very well purified it will always hold fomefmall 
 portion of fea-falt, the acid of which, we know, is 
 very readily fet loofe by the vitriolic acid, and con- 
 fequently rifes together with the vapours of the 
 aqua fortis. It is eafy to fee that aqua fortis 
 mixed either with the one or the other is not proper 
 for the Parting Procefs ; becaufe, as has jutt been 
 faid, the vitriolic and the marine acid equally pre- 
 cipitate Silver diffolved in the nitrous acid -, by 
 which means, when they are united with that acid 
 they weaken its aftion upon the Silver, and hinder 
 the diflblution. Add that aqua fortis adulterated 
 with a mixture of ipirit of fait becomes an aqua 
 regis, and confequently is rendered capable of 
 
 difiblving
 
 58 ELEMENTS o/" thf 
 
 diflblving Gold, in proportion as its action upon 
 Silver is diminifhed. 
 
 In order to remedy this inconvenience, and free 
 aqua fortis from the vitriolic or marine acid with 
 which it is tainted, Silver muft be diflblved there- 
 in : by degrees as the metal diflblves, thole hetero- 
 geneous acids lay hold of it, and precipitate with it 
 in the form of a white powder, as we obferved be- 
 fore. This precipitate being wholly fallen, the 
 liquor grows clear ; after which, if it be found 
 capable of difiblving more Silver, without turning 
 milky, it may be depended on as a perfectly pure 
 aqua fortis. Then filtre it, difTolve more Silver in 
 it, as long as it will take up any, and you will have 
 a folution of Silver in a very pure aqua fortis. By 
 means of this folution may other aquafortis be pu- 
 rified : for pour a few drops thereof into a very im- 
 pure aqua fortis, and Immediately the vitriolic or 
 marine acid, with which that aqua fortis is conta- 
 minated, will ]oin the Silver and fail therewith to 
 the bottom. When the folution of Silver prepared 
 as above does not in the lead affect the traniparency 
 of the aqua fcrtis, it is then very pure, and fit for 
 thz purpofes of Quartation. 
 
 This operation of purriyingaqiia fcrtis by a folu- 
 tion of Silver is called the Precipitation of aqua for- 
 tis i and aqua fortis thus purih'ed is called Precipi- 
 tated Aqua Fortis. 
 
 When Silver is diflblvcd in aqua- fortis it may 
 be ft parated therefrom, as hath been fhewn, by ab- 
 forbent earths and fixed alkalis. 
 
 We mail fee by and by that there arc other means 
 of effecting this : but whatever way it be feparated 
 from its loivent it recovers its metalline form, as 
 Gold does, by being fimply fufed without any 
 additamen;, 
 
 f . Hi. Qf
 
 THEORY of CHYMISTRY. 59 
 
 . III. Of COPPER. 
 
 OF all the imperfect metals Copper comes the 
 neareft to Gold and Silver. Its natural colour is 
 a deep-red yellow. It refifts a very violent degree 
 of fire for a confiderable time -, but lofing its phlo- 
 gifton at laft, it changes its metalline form for that 
 of a calx, or a pure reddifh earth. This calx is 
 hardly, if at all, reducible to glafs, without the ad- 
 dition of fomething to promote its fufion ; all that 
 the fierceft heat can do bein^ only to render it foft. 
 Copper, even while it retains its metalline form, 
 and is very pure, requires a confiderable degree of 
 fire to melt it, and does not begin to flow till long 
 after it is red-hot. When in fufion it communi- 
 cates a greenilh colour to the flame of the coals. 
 
 This metal is inferior to Silver in point of gra- 
 vity ; nor is its ductility fo great, though it be 
 pretty confiderable : bur, on the other hand, it 
 exceeds that met:\l in hardnefs. It unites readily 
 with Gold and Silver , nor does it greatly leflen 
 their beauty when added to them in a fmall quan- 
 tity : nay, it even procures them fome advantages; 
 fuch as making them harder, and lefs fubject to 
 lofe their ductility, of which thofe metals are often 
 liable to be deprived, by the mixture of the fmalleft 
 heterogeneous particle. This may probably arife 
 from hence, that the ductility of Copper has the 
 peculiarity of refitting moft of thofe caufes which 
 rob the perfect metals of theirs. 
 
 The property, which other metalline fubftances 
 have in common with Copper, of lofing the phlogif- 
 ton by calcining and then vitrifying, furnifhes us with 
 a method of feparating them from Gold and Silver, 
 when they are combined therewith. Nothing more 
 is required than to expofe the mafs compounded of 
 the perfect metals and other metalline fubftances tq
 
 60 E L E M E N T S of til 
 
 a degree of heat fufficient to calcine whatever is 
 not either Gold or Silver. It is evident that by this 
 means thefe two metals will be obtained as pure as 
 is pofiible ; for, as hath already been laid, no me- 
 talline calx or glafs is capable of uniting witli 
 metals pofifefTcd of their phlogifton. On this prin- 
 ciple is formed the whole bufmefs of refining Gold 
 and Silver. 
 
 When the perfect metals have no other alloy but 
 Copper, as this metal is not to be calcined or vitri- 
 fied without great difficulty, which is increafed by 
 its union with the unvitrifiable metals, it is eafy to 
 fee that it is almoft impofTible to feparate them 
 without adding fomething to facilitate the vitrifica- 
 tion of the Copper. Such metals as have the pro- 
 perty of turning eafily to glafs are very fit for this 
 purpofe ; and it is neceflary to add a certain quan- 
 tity thereof, when Gold or Silver is to be purified 
 from the alloy of Copper. We fhall have occafion 
 to be more particular on this fubject when we come 
 to treat of lead. 
 
 Copper is foluble in all the acids, to which it 
 communicates a green colour, and fometimes a 
 blue. Even the neutral lalts, and water itfelr, act 
 upon this metal. With regard to water indeed, as 
 the procuring it abfolutely pure and free from any 
 faline mixture is next to an impoflibility, it remains 
 a queftion whether the effect it produces on Copper 
 be not owing to certain faline particles contained 
 in it. It is this great facility of being diflblved 
 that renders Copper fo fubject to ruft ; which is 
 nothing elfe but ionic parts of its furface corroded 
 by faline particles contained in the furrounding air 
 and water. 
 
 The ruft of Copper is always green or blue, or 
 
 of a colour between thefe two. Internally ufed it is 
 
 very noxious, being a real poilbn, as arc all the fo- 
 
 lutions of this metal made by any acid whatever. 
 
 7 The
 
 TH E O R Y of CH Y M I S T R Y. 6l 
 
 The blue colour, which Copper conftantly aflfiimes 
 when corroded by any faline fubftance, is a fure 
 fjgn by which it may be difcovered wherever it 
 exifts, even in a very fmall quantity. 
 
 Copper difiblved in the vitriolic acid forms a kind 
 of metalline fait* which fhoots into rhomboidal 
 cryftals of a moft beautiful blue colour. Thefe 
 cryftals are called Blue Vitriol, or Vitriol of Copper. 
 They are fometimes found ready formed in the 
 bowels of the earth ; and may be artificially made 
 by difiblving Copper in the vitriolic acid ; but the 
 folution will not fucceed unlefs the acid be well 
 dephlegmated. The tafte of this vitriol is faltifti 
 and aftringent. It retains a confiderable quantity 
 of water in cryflallizing, on which account it is 
 eafily rendered fluid by fire. 
 
 It mud be obferved that, when it is expofed to a 
 certain degree of heat in order to free it of its hu- 
 midity, a great part of its acid flies off at the fame 
 time : and hence it is that, after calcination, there 
 remains only a kind of earth, or metalline calx, of 
 a red colour, which contains but very little acid. 
 This earth cannot be brought to flow but with the 
 greateft difficulty. 
 
 A folution of copper in the nitrous acid forms a 
 fait which does not cryftallize, but, when dried, 
 powerfully attracts the moifture of the air. The 
 lame thing happens when it is diflblved in fpirit of 
 fait, or in aqua regis. 
 
 If the Copper thus diflblved by any of thefe acids 
 be precipitated by an earth or an alkali, it retains 
 nearly the colour it had in the folution : but thefe 
 precipitates are fcarce any thing more than the earth 
 of Copper, or Copper deprived of moft of its 
 phlogifton; fo that if they were expofed to a vio- 
 lent fire, without any additament, a great part of 
 them would be converted into an earth that could 
 n^ver be reduced to a metalline form. Therefore, 
 
 when
 
 62 E L E M E N T 8 of tt>e 
 
 when we intend to reduce thefe precipitates to Cop- 
 per, it is neceflary to add a certain quantity of a 
 fubftance capable of reftoring to them the phlogif- 
 ton they have loft. 
 
 The fubftance which hath been found fitted for 
 fuch reductions is charcoal-duft ; becaufe charcoal 
 is nothing but a phlogifton clofely combined with 
 an earth, which renders it exceedingly fixed, and 
 capable of refifting a violent force of fire. But 
 as charcoal will not melt, and confcquently is capa- 
 ble of preventing rather than forwarding the flux 
 of a metalline calx or glafs, which neverthelefs is 
 efientially neceflary to complete the reduction, it 
 hath been contrived to mix it, or any other fub- 
 ftance containing the phlogifton, with fuch fixed 
 alkalis as eafily flow, and are fit to promote the 
 flux of other bodies. Thefe mixtures are called 
 Reducing Fluxes \ becaufe the general name of Fluxes 
 is given to all falts, or mixtures of falts, which fa- 
 cilitate fufion. 
 
 If Sulphur be applied to Copper made perfectly- 
 red-hot, the metal immediately runs , and thefe 
 two fubftances uniting form a new compound much 
 more fufible than pure Copper. 
 
 This compound is deftroyed by the fole force of 
 fire, for two reafons : the firft is, that, fulphur 
 being volatile, the fire is capable of fubliming a 
 great part of it, efpecially when it is in a great pro- 
 portion to the Copper with which it is joined , the 
 iecond is, that the portion of fulphur which re- 
 mains, being more intimately united with the Cop- 
 per, though it be rendered lefs combuftible by that 
 union, is neverthelefs burnt and confumed in time. 
 Copper being combined with lulphur, and together 
 with it expofed to the force of fire, is found to be 
 partly changed into a blue vitriol , becaufe the vitri- 
 olic acid, being difcngaged by burning the fulphur, 
 is by that means qualified to diffolve the Copper. 
 
 The
 
 THEORY of CnVMistRY. 63 
 
 The affinity of Copper with fulphur is greater than 
 that of Silver. 
 
 This metal, as well as the other imperfect metals 
 and the femi-metals, being mingled with nitre and 
 expoied to the fire, is decompofed and calcined 
 much fooner than by itfelf , becaufe the phlogif- 
 ton which it contains occafions the deflagration of 
 the nitre, and confequently the two fubftances mu- 
 tually decompofe each other. There are certain, 
 metalline fubftances whofe phlogifton is fo abun- 
 dant, and fo weakly connected with their earth, 
 that when they are thus treated with nitre, there 
 arifes immediately a detonation, accompanied with 
 flame, and as violent as if fulphur or charcoal-duft 
 had been employed ; fo that in a moment the me- 
 talline fubftance lofes its phlogifton, and is calcined. 
 The nitre, after thefe detonations, always afTum^ 
 an alkaline character. 
 
 . IV. O/IRON. 
 
 IRON is lighter and lefs ductile than Copper ; but 
 it is much harder, and of more difficult fufion. 
 
 It is the only body that has the property of be* 
 ing attracted by the magnet, which therefore fervcs 
 to difcover it wherever it is. But it mutt be ob- 
 ferved that it hath this property only when in its 
 metalline ftate, and lofes it when converted to an 
 earth or calx. Hence very few Iron-ores are at- 
 tracted by the load-ftone ; becaufe, for the molt 
 part, they are only forts of earths, which require a 
 phlogifton to be added before they can be brought 
 to the form of true Iron. 
 
 When Iron hath undergone no other preparation 
 but the fufion which is neceffary to fmelt it from its 
 ore, it is uiually quite brittle, and flies to pieces un- 
 der the hammer : which arifes in fome meafure from 
 its containing a certain portion of unmetallic earth 
 
 interpofed
 
 64 E L E M E N T S of the 
 
 interpofed between its parts. This we call Pig 
 Ircn. 
 
 By melting this a fecond time it is rendered 
 purer, and more free from heterogeneous matters : 
 but dill, as its proper parts are probably not 
 brought fufficiently near, or clofely enough united, 
 till the Iron hath undergone fome further prepara- 
 tion befides that of fufion, it ieldom hath any degree 
 of malleability. 
 
 The way to give it this property is to make it 
 juft red hot, and then hammer it for fome time in 
 all directions ; to the end that its parts may be pro- 
 perly united, incorporated, and welded together, 
 and that the heterogeneous matters which keep 
 them afunder may be ieparated. Iron made by 
 this means as malleable as poflible we call Ear Iron, 
 or Forged Iron. 
 
 Bar Iron is ft ill harder to fufe than Pig Iron : to 
 make it flow requires the utmoft force of fire. 
 
 Iron has the property of imbibing a greater 
 quantity of phlogifton than is neceflary to give it 
 the metalline form. It may be made to take in 
 this fuperabundant phlogifton two ways : the fnft 
 is by fufing it again with matters that contain the 
 phlogifton i the fecond is, by encompafilng it with 
 a quantity of fuch matters, charcoal-dud for in- 
 ftance, and then expofing it fo encompafled, for a 
 certain time, to a degree of fire barely fufficicnt to 
 keep it red-hot. This fecond method, whereby 
 one fubftance is incorporated with another by 
 means of fire, but without fufing either of them, 
 is in general called Cementation. 
 
 Iron thus impregnated with an additional quan- 
 tity of phlogifton is called Steel. The hardnels of 
 Steel may be confidcrably augmented by tempering 
 it ; that is, by making it red-hot, and fuddenly 
 quenching it in fome cold liquor. The hotter the 
 metal, and the colder the liquor in which it is 
 
 quenched j
 
 THEORY 0/*CHYMisTRY. 65 
 
 quenched, the harder will the Steel be. By this 
 means tools are made, flich as files and fheers 1 , 
 capable of cutting and dividing the hardeft bodies, 
 as glafs, pebbles, and Iron itfelf. The colour of 
 Steel is darker than that of Iron, and the facets 
 which appear on breaking it are fmaller. It is allb 
 lefs ductile and more brittle, efpecially when tem- 
 pered. 
 
 As Iron may be impregnated with an additional 
 quantity of phlogifton, and thereby converted into 
 Steel, fo may Steel be again deprived of that fuper- 
 abundant phlogifton, and brought back to the con- 
 dition of Iron. This is effected by cementing it 
 with poor earths, fnch as calcined bones and chalk. 
 By the fame operation Steel may be imtemperedi 
 nay, it will lofe the hardnefs it had acquired by 
 tempering, if it be but made red-hot, and left to 
 cool gradually. As Iron and Steel differ only in 
 the refpects we have here taken notice of, their 
 properties being in all other refpects the fame, 
 what follows is equally applicable to both. 
 
 Iron being expofed to the action of fire for fome 
 time, efpecially when divided into fmall particles, 
 fuch as filings, is calcined and lofes its phlogifton. 
 By this means it turns to a kind of reddilh yellow 
 earth, which on account of its colour is called Cro- 
 cus Martis, or Saffron of Mars. 
 
 This calx of Iron has the fingular property of 
 flowing in the fire with fomewhat iefs difficulty than 
 Iron itfelf; whereas every other metalline calx 
 flows with lefs eafe than the metal that produced it. 
 It has moreover the remarkable property of uniting 
 with the phlogifton, and of being reduced to Iron 
 without fufion ; requiring for that purpofe only to 
 be made red-hot. 
 
 Iron may be incorporated with Silver, and even 
 with Gold, by means of certain operations. Under 
 
 VOL. I. F the
 
 66 E L E M E N T S of the 
 
 the article of Lead we (hall fee how it may be fe- 
 parated from thefe metals. 
 
 The acids produce on it much the fame effects 
 as on Copper : every one of them acts upon it. 
 Certain neutral falts, alkalis, and even water itfelf, 
 are capable of diflblving it ; and hence it is alfo very 
 fubjedt to ruft. The vitriolic acid difiblves it with 
 the greateft eafe : but the circumftances which at- 
 tend the folution thereof are different from thofe 
 with which the fame acid diffblves Copper : for, 
 i. whereas the vitriolic acid muft be concentrated 
 to difiblve Copper, it muft on the contrary be di- 
 luted with water to diflblve Iron, which it will not 
 touch when well dephlegmated. 2. The vapours 
 which rife in this diflblution are inflammable , fo 
 that if it be made in a fmall-necked bottle, and the 
 flame of a candle be applied to the mouth thereof, 
 the vapours in the bottle take fire with fuch rapidity 
 as to produce a confidcrable explofion. 
 
 This folution is of a beautiful green colour ; and 
 from this union of the vitriolic acid with Iron there 
 refults a neutral metalline fait, which has the pro- 
 perty of (hooting into cryftals of a rhomboidal fi- 
 gure, and a green colour. Thefe cryftals are called 
 Green Vitriol^ Vitriol of Mars, and Copperas. 
 
 Green Vitriol hath a faltifti and aftringent tafte. 
 As it retains a great deal of water, in cryftalliz- 
 ing it quickly flows by the action of fire : but this 
 fluidity is owing to its water only, and is not a real 
 fufion ; for as foon as its moiilure is evaporated, it 
 refumes a folid form. Its green tranfparent colour 
 is now changed into an opaque white: and, if 
 the calcination be continued, its acid alfo exhales 
 and is diffipated in vapours , and as it lofes that, 
 it turns gradually to a yellow colour, which comes 
 fo much the nearer to a red the longer the calci- 
 nation is continued, or the higher the force of the 
 fire is raifed ; which being driven to the utmoft, 
 3 what
 
 THEORY C/'CHYMISTRY. 67 
 
 what remains is of a very deep red. This remain- 
 der is nothing but the body of the Iron, which hav- 
 ing loft its phlogifton is now no more than an earth, 
 nearly of the fame nature with that which is left 
 after calcining the metal itfelf. 
 
 Green Vitriol diffolved in water fpontaneoufly 
 lets fall a yellowifh earthy fediment. If this folution 
 be defecated by filtration, it (till continues to depo- 
 fite fome of the fame fubftance, till the vitriol be 
 wholly decompofed. This fediment is nothing but 
 the earth of Iron, wfrich is then called Ochre. 
 
 The nitrous acid diffolves Iron with great eafe.' 
 This folution is of a yellow colour, inclining more 
 or lefs to a rufTet, or dark-brown, as it is more or 
 lefs faturated with Iron. Iron diffolved by this acid 
 alfo, falls fpontaneoufly in a kind of calx, which is 
 incapable of being diffolved arfecond time ; for the 
 nitrous acid will not act upon Iron that has loft its 
 phlogifton. This folution does not cryftallize, and 
 if evaporated to drynefs attracts the moifture of the 
 air. 
 
 Spirit of fait likewife diffolves Iron, and this folu- 
 tion is green. The vapours which rife during the 
 diffolution are inflammable, like thofe which alcend 
 when this metal is attacked by the vitriolic acid. 
 Aqua regis makes a folution of Iron, which is of a 
 yellow colour. 
 
 Iron hath a greater affinity than either Silver or 
 Copper with the nitrous and vitriolic acids : fo that 
 if Iron be prefented to a folution of either in one of 
 thefe two acids, the diffolved metal will be precipi- 
 tated ; becaufe the acid quits it for the Iron, with 
 which it has a greater affinity. 
 
 On this occafion it muft be obferved that if a fo- 
 lution of Copper in the vitriolic acid be precipitated 
 by means of Iron, the precipitate has the form and 
 fplendour of a metal, and does not require the addi- 
 tion of a phlogifton to reduce if to true Copper; 
 
 F 2 which
 
 68 E L E M E N T S of tie 
 
 which is not the cafe, as has been (hewn, when the 
 precipitation is effected by earths or alkaline falts. 
 
 The colour of this metalline precipitate hath de- 
 ceived feveral peribns, who being unacquainted 
 with fuch phenomena, and with the nature of blue 
 vitriol, imagined that Iron was tranfmuted into Cop- 
 per, when they faw a bit of Iron laid in a folution 
 of that vitriol become, in form and external appear- 
 ance, exactly like Copper : whereas the lurface 
 only of the Iron was crufted over with the particles 
 of Copper contained in the vitriol, which had gra- 
 dually fallen upon and adhered to the Iron, as they 
 were precipitated out of the folution. 
 
 Among the folvents of Iron we mentioned fixed 
 alkalis ; and that they have fuch a power is proved 
 by the following phenomenon. If a large propor- 
 tion of alkaline falts be fuddenly mixed with a folu- 
 tion of Iron in an acid, no precipitation enfues, and 
 the liquor remains clear and pellucid 5 or if at firft 
 it look a little turbid, that appearance lads but a 
 moment, and the liquor prefcntly recovers its tranf- 
 parency. The reafon is, that the quantity of alkali 
 is more than fufficient to faturate all the acid of 
 the folution, and the fuperabundant portion there- 
 of, meeting with the Iron already finely divided by 
 the acid, difiblves it with cafe as faft as it falls, and 
 io prevents its muddying the liquor. To evince 
 that this is fo in faft, let the alkali be applied in a 
 quantity that is not fufficient, or but barely fuffi- 
 cient, to faturate the acid, and the Iron will then 
 precipitate like any other metal. 
 
 Water alfo afts upon Iron ; and therefore Iron 
 expofed to moifture grows rufty. If Iron-filings 
 be expofed to the dew, they turn wholly to a rult, 
 which is called Crocus Martis Aperiens. 
 
 Iron expofed to the fire together with nitre makes 
 it detonate pretty brifkly, fets it in a flame, and 
 decompofes it with rapidity. 
 
 TJiis
 
 THEORY of C H y M i s T R Y. 69 
 
 This metal hath a greater affinity than any other 
 metalline fubftance with fulphur; on which account 
 it is fuccefsfully ufed to precipitate and feparate all 
 metalline fubftances combined with fulphur. 
 
 Sulphur uniting with Iron communicates to it 
 fuch a degree of fufibility, that if a mais of this 
 metal heated red-hot be rubbed with a bit of ful- 
 phur, it incefTantly-runs into as perfect a fufion as a 
 metal expoled to the focus of a large burning-glafs. 
 
 . V. 0/TiN. 
 
 TIN is the lighted of all metals. Though it 
 yields eafily to the imprefiion of hard bodies, it has 
 but little ductility. Being bent backwards and 
 forwards it makes a fmall crackling noife. It flows 
 with a very moderate degree 6f fire, and long be- 
 fore it cornes to be red-hot. When it is in fufion, 
 its furface foon grows dufky, and there forms upon 
 it a thin dark-coloured dufty pellicle, which is no 
 other than a part of the Tin that has loft its phlo- 
 gifton, or a calx of Tin. The metal thus calcined 
 eafily recovers its metalline form on the addition of 
 a phlogifton. If the calx of Tin be urged by a 
 ftrong fire it grows white, but the greateft violence 
 of heat will not fufe it-, which makes ibme Chy- 
 milts confider it as a calcinable or abforbent earth, 
 rather than a verifiable one. Yet it turns to glafs, 
 in fome (ort, when mixed with any other fubftance 
 that vitrifies eafily. However, it always produces 
 an imperfect glafs only, which is nor at all tranlpa- 
 rent, but of an opaque white. The calx of Tin 
 thus vitrified is called Enamel. Enamels are made 
 of fevcral colours by the addition of this or that 
 metalline calx. 
 
 Tin unites eafily with all the metals ; but it de- 
 ftroys the ductility and malleability of every one of 
 them, Lead excepted. Nay, it pofieffes this property 
 of making metals brittle in fuch an eminent de- 
 
 F 3 grec,
 
 7O E L E M E N T S of 
 
 gree, that the very vapour of it, when in fufion, is 
 capable of producing this effect. Moreover, which 
 is very fingular, the moft ductile metals, even 
 Gold and Silver, are thofe on which it works this 
 change with the moft eafe, and in the greateft de- 
 gree. It has alfo the property of making Silver 
 mixed with it flow over a very fmall fire. 
 
 It adheres to, and in fome meafure incorporates 
 with, the furface of Copper and of Iron , whence 
 arole the practice of coating over thofe metals with 
 Tin. Tin-plates are no other than thin plates of 
 Iron tinned over. 
 
 If to twenty parts of Tin one part of Copper be 
 added, this alloy renders it -much more folid, and 
 the mixed mafs continues tolerably ductile. 
 
 If on the contrary to one part of Tin ten parts of 
 Copper be added, together with a little Zink, a 
 femi-metal to be confidered hereafter, from this 
 combination there refults a metalline compound 
 which is hard, brittle, and very fonorous ; fo that 
 it is ufed for cafting bells: this compofition is called 
 Bronze and Belt- met at. 
 
 Tin hath an affinity with the vitriolic, nitrous, and 
 marine acids. All of them attack and corrode it ; 
 yet none of them is able to diflblve it without great 
 difficulty: fo that if a clear folution thereof be de- 
 fired, particular methods muft be employed for that 
 purpofe , for the acids do but in a manner calcine it, 
 and convert it to a kind of white calx or precipitate. 
 The folvent which has the greateft power over it is 
 Aqua regis, which has even a greater affinity there- 
 with than with Gold itfelf ; whence it follows that 
 Gold diflblved in aqua regis may be precipitated by 
 means of Tin ; but then the aqua regis muft be 
 weakened. Gold thus precipitated by Tin is of a 
 moft beautiful colour, and is ufed for a red in en- 
 ameling and painting on porcelain, as alfo to give 
 A red colour to artificial gems. If the aqua regis 
 
 be
 
 THEOR Y of CH Y M i s T R Y. 71 
 
 be not lowered, the precipitate will not have the 
 purple colour. 
 
 Tin hath the property of giving a great luftre to 
 all red colours in general ; on which account it is 
 ufed by the dyers for ftriking a beautiful fcarlet, 
 and tin vefiels are employed in making fine fyrup 
 of violets. Water does not aft upon this metal, as 
 it does upon Iron and Copper ; for which reafon it 
 is not fubjec~t to ruft : neverthelefs when it is ex- 
 pofed to the air its furface foon lofes its polifh and 
 fplendour. 
 
 Tin mixed with nitre and expofed to the fire de- 
 flagrates with it, makes it detonate, and is immedi- 
 ately converted to a refractory calx : for fo all fub- 
 ftances are called which are incapable of fufion. 
 
 Tin readily unites with fulphur, and with it be- 
 comes a brittle and friable mafs. 
 
 . VI. O/LEAD. 
 
 NEXT to Gold and Mercury Lead is the heavieft 
 of all metalline fubftances, but in hardnefs is ex- 
 ceeded by every one of them. Of all metals alfo it 
 melts the eafieft except Tin. While it is in fufion 
 there gathers inceflantly on its furface, as on that 
 of Tin, a blackilh dufty pellicle, which is nothing 
 but a calx of Lead. 
 
 This calx further calcined by a moderate fire, 
 the flame being reverberated on it, foon grows white. 
 If the calcination be continued it becomes yellow, 
 and at laft of a beautiful red. In this ftate it is 
 called Minium, and is ufed as a pigment. Minium 
 is not eafily made, and the operation fucceeds well 
 in large manufactures only. 
 
 To convert Lead into Litharge, which is the 
 metal in a manner half vitrified, you need only keep 
 it melted by a pretty ftrong fire ; for then as its 
 furface gradually calcines, it tends more and more 
 to fufion and vitrification. 
 
 F 4 All
 
 72 E L E M E N T S of the 
 
 All thefe preparations of Lead are greatly difpo- 
 fed to perfect fufion and vitrification, and for that 
 purpofe require but a moderate degree of fire , the 
 calx or earth of Lead being of all metalline earths 
 that which vitrifies the moft eafily. 
 
 Lead hath not only the property of turning 
 into glais with the greateft facility, but it hath alfo 
 that of promoting greatly the vitrification of all the 
 other imperfect metals -, and, when it is actually 
 vitrified, procures the ready fufion of all earths and 
 ftones in general, even thofe which are refractory, 
 that is, which could not be fufed without its 
 help. 
 
 Glafs of Lead, befides its great fufibility, hath 
 alfo the fingular property of being fo fubtile and 
 aftive as to corrode and penetrate the crucibles in 
 which it is melted, unlels they be of an earth that 
 is exceeding hard, compact, and withal very refrac- 
 tory : for Glafs of Lead being one of the moft 
 powerful fluxes that we know, if the earth of the 
 crucible in which it is melted be in the fmalleft 
 degree fufible, it will be immediately vitrified ; 
 efpecially if there be any metallic matter in its com- 
 pofition. 
 
 The great activity of Glafs of Lead may be 
 xveakened by joining it with other verifiable mat- 
 ters : but unlefs thefe be added in a very great pro- 
 portion, it will ftill remain powerful enough to pe- 
 netrate common earths, and carry off the matters 
 combined with it. 
 
 On thefe properties of Lead, and of the Glafs of 
 Lead,depends the whole bu finds of refining Gold and 
 Silver. It hath been fhewn that as thefe two metals 
 are indeftructible by fire, and the only ones which 
 have that advantage, they may be Separated from 
 the imperfect metals, when mixed therewith, by ex- 
 pofing the compound to a degree of fire fufficiently 
 ftrong to vitrify the latter j which when once con- 
 3 verted
 
 THEORY 0/ % CnYMisTRY. 73 
 
 verted into glafs can no longer remain united with 
 any metal that has its metalline form. But ic is very 
 difficult to procure this vitrification of the imperfect 
 metals, when united with Gold and Silver -, nay, ic 
 is ?n a manner impoflible to vitrify them entirely, 
 for two reafons : firft, becaufe moft of them are natu- 
 rally very difficult to vitrify ; fecondly, becaufe the 
 union they have contracted with the perfect metals 
 defends them, in a manner, from the action of the 
 fire, and that fo much the more effectually as the 
 proportion of the perfect metals is greater ; which 
 being indeftructible, and in fome fort coating over 
 thofe with which they are alloyed, ferve them as a 
 prefervative and impenetrable fhield againfl the 
 utmoft violence of fire. 
 
 It is therefore clear that a great deal of labour 
 may be faved, and that Gold and Silver may be 
 refined to a much greater degree of purity than can 
 otherwife be obtained, if to a mixture of thefe metals 
 with Copper, for inftance, or any other imperfect me- 
 tal, be added a certain quantity of Lead. For the Lead, 
 by its known property, will infallibly produce the 
 defired vitrification ; and as it likewife increales the 
 proportion of the imperfect metals, and fo leflens 
 that of the perfect metals, in the mafs, it evidently 
 deprives the former of a part of their guard, and 
 fo effects a more complete vitrification. In conclu* 
 fion, as the Glafs of Lead hath the property of 
 running through the crucible, and carrying with it 
 the matters which it has vitrified, it follows that 
 when the vitrification of the imperfect metals is ef- 
 fected by its means, all thofe vitrified matters toge- 
 ther penetrate the velfel containing the fufed metal- 
 line mafs, difappear, and leave only the Gold and 
 Siver perfectly pure, and freed, as far as is pofiible, 
 from all admixture of heterogeneous parts. 
 
 The better to promote the feparation of fuch parts, 
 it is ufual to employ in this procefs a particular fort 
 
 of
 
 74 E L E M E N T s of the 
 
 of fmall crucibles, made of the afhes of calcined 
 bones, which are exceedingly porous and eafily per- 
 vaded. They are called cupels, on account of their 
 figure, which is that of a wide-mouthed cup : and 
 from hence the operation takes its name ; for when 
 we refine Gold and Silver in this manner we are 
 faid to cupel thofe metals. It is eafy to perceive that 
 the more Lead is added the more accurately will the 
 Gold and Silver be refined ; and that fo much the 
 more Lead ought to be added as the perfect metals 
 are alloyed with a greater proportion of the imper- 
 fect. This is the moft fevere trial to which a per- 
 fect metal can be put ; and confequendy any metal 
 that ftands it may be fairly confidered as fuch. 
 
 In order to denote the finenefs of Gold, it is fup- 
 pofed to be divided into twenty-four parts called 
 carats ; and Gold which is quite pure and free from 
 all alloy is faid to be twenty-four carats fine , that 
 which contains VT P art f alloy is called Gold of 
 twenty-three carats ; that which contains T a T of al- 
 loy is but twenty-two carats ; and fo on. Silver 
 again is fuppofed to be divided into twelve parts 
 only, which are called penny-weights : fo that when 
 abfolutely pure it is faid to be twelve penny -weights 
 fine , when it contains T 'T of alloy, it is then called 
 eleven penny-weights fine -, when it contains T a T of 
 alloy, it is called ten penny-weights fine, and fo on. 
 
 Jn treating of Copper we promifed to mew, under 
 the article of Lead, how to feparate it from Iron. 
 The procefs is founded on that property of Lead 
 which renders it incapable of mixing and uniting 
 with Iron, though it readily difiblves all other me- 
 talline fubftances. Therefore if you have a mafs 
 compounded of Copper and Iron, it muft be fufed 
 with a certain quantity of Lead, and then the Cop- 
 per, having a greater affinity with Lead than with 
 Iron, will defert the latter and join the former, 
 which being incapable of any union with Iron, as 
 
 was
 
 THEORY of CHYMISTRY. 75 
 
 was faid, will wholly exclude it from the new com- 
 pound. The next point is to feparate the Lead 
 from the Copper ; which is done by expofing the 
 mafs compounded of thefe two metals to a degree 
 of fire ftrong enough to deprive the Lead of its 
 metalline form, but too weak to have the fame ef- 
 fect on the Copper : and this may be done ; fince 
 of all the imperfect metals Lead is, next to Tin ? 
 the eafieft to be calcined, and Copper on the con- 
 trary refifts the greatcft force of fire longeft, with- 
 out lofing its metalline form. Now what we gain 
 by this exchange, viz. by feparating Copper from 
 Iron and uniting it with Lead, confifts in this, that 
 as Lead is calcined with tefs fire than Iron, the Cop- 
 per is lefs expofed to be deftroyed : For it muft be 
 obferved that, however moderate the fire be, it is 
 hardly poflible to prevent a certain quantity there- 
 of from being calcined in the operation. 
 
 Lead melted with a third part of Tin forms a 
 compound, which being expofed to a fire capable 
 of making it thoroughly red-hot, fwells, puffs up, 
 feems in fome fort to take fire, and is prefently cal- 
 cined. Thefe two metals mixed together are much 
 fooner calcined than either of them feparately. 
 
 Both Lead and Tin are in fome meafure affected 
 by water, and by a moid air ; but they are both 
 much lefs fubject than Iron or Copper to be corro- 
 ded by thefe folvents, and of courfe are much lefs 
 liable to ruft. 
 
 The vitriolic acid acts upon and clhTolves Lead, 
 much in the fame manner as it doth Silver. 
 
 The nitrous acid diffblves this metal with much 
 eafc, and in great quantities-, and from thisfolution 
 a fmall portion of mercury may be obtained. On 
 this fubject fee our Elements of the PraFtice of Chy- 
 miftry. 
 
 When this folution of Lead is diluted with a 
 good deal of water, the Lead precipitates in the 
 
 form
 
 76 E L E M E N T S of the 
 
 form of a white powder -, which happens becaufe 
 
 the acid is rendered too weak to keep the Lead 
 
 difiblved. 
 
 If this folution of Lead be evaporated to a cer- 
 tain degree, it fhoots into cryftals formed like regu- 
 lar pyramids with fquare bales. Thefe cryftals are 
 of a yellowiih colour, and of a faccharine tafte : 
 they do not eafily diflblve in water. This nitrous 
 metalline fait has the fingular property of detonat- 
 ing in a crucible, without any additament, or the 
 contact of any other inflammable fubitance. This 
 property it derives from the great quantity of 
 phlogifton contained in, and but loofely connected 
 with, the Lead which is one of its principles. 
 
 If fpirit of fait, or even fea-falt in fubftance, 
 be added to a folution of Lead in the nitrous acid, 
 a white precipitate immediately falls , which is no 
 other than the Lead united with the marine acid. 
 This precipitate is extremely like the precipitate of 
 Silver made in the fame manner, and that being 
 called Luna cornea hath occafioned this to be named 
 Plumbum corneum. Like the luna cornea it is very 
 fufible, and being melted hardens like it into a kind 
 of horny fubftance : it is volatile, and may be re- 
 duced by means of inflammable matters combined 
 with alkalis. But it differs from the luna cornea in 
 this chiefly, that it difiblves eafily in water , whereas 
 the luna cornea, on the contrary, diflblves therein 
 with great difficulty, and in a very fmall quantity. 
 
 As this precipitation of Lead from its folution 
 in fpirit of nitre is procured by the marine acid, 
 Lead is thereby proved to have a greater affinity 
 with the latter acid than with the former. Yet, if 
 you attempt to diflblve Lead directly by the acid of 
 fea-falt, the folution is not fo eafily effected as by the 
 fpirit of nitre, and it is always imperfect ; for it 
 wants one of the conditions eflential to every folu- 
 tion in a liquor, namely tranfparency. 
 
 If
 
 THEORY of CHYMISTRY. 77 
 
 If Lead be boiled for a long time in a lixivium of 
 fixed alkali, part of it will be difiblved. 
 
 Sulphur renders this metal refractory and fcarce 
 fufible ; and the mals they form when united 
 together is friable. Hence it appears that ful- 
 phur acts upon Lead much in the lame tnanner 
 as upon Tin ; that is, it renders both thefe metals 
 lefs fufible, which are naturally the mod fufible of 
 any, whi:e it exceedingly facilitates the fufion of 
 Silver, Copper, and Iron, metals which of them- 
 feives flow with the greateft difficulty. 
 
 CHAP. VIII. 
 
 Of QjJ I C K -S I L V E R. 
 
 WE treat of Quick-filver in a chapter apart, 
 becaufe this metallic fubftance cannot be 
 claflfed with the metals properly fo called, and yet 
 has fome properties which will not allow us to con- 
 found it with the femi- metals. The reafon why 
 Quick-filver, by the Chymifts commonly called 
 Mercury, is not reputed a metal is, that it wants 
 one of the effential properties thereof, to wit, mal- 
 leability. When it is pure and unadulterated with 
 any mixture, it is always fluid, and of courfe unmal- 
 leable. But as, on the other hand, it eminently 
 pofieflbs the opacity, the fplendour, and above all 
 the gravity of a metal, being next to Gold the hea- 
 vieft of all bodies, it may be coniidered as a true 
 metal, differing from the reft no otherwife than by 
 being conftantly in fufion ; which we may fuppofe 
 arifes from its aptnefs to flow with fuch a fmall degree 
 of heat, that be there ever fo little warmth on earth, 
 there is Hill more than enough to keep Mercury in 
 
 fufion i
 
 78 E L E M E N T S of the 
 
 fufion; which would become folid and malleable if it 
 were poffible to apply to it a degree of cold confi- 
 derable enough for that purpofe. Thefe properties 
 will not allow us to confound it with the femi-me- 
 tals. Add that we are not yet aflured by any un- 
 doubted experiment that it can be wholly deprived 
 of its phlogifton, as the imperfect metals may. 
 Indeed we cannot apply the force of fire to it as 
 could be wifhed : for it is fo volatile that it flies off 
 and exhales in vapours, with a much lefs degree of 
 fire than is neceflary to make it red-hot. The va- 
 pours of Mercury thus raifed by the action of fire, 
 being collected and united in a certain quantity, ap- 
 pear to be no other than true Mercury, retaining 
 every one of its properties , and no experiment hath 
 ever been able to (hew the Icaft change thus pro- 
 duced in its nature. 
 
 If Mercury be expofed to the greateft heat that it 
 can bear without fublimation, and continued in it 
 for feveral months, or even a whole year together, 
 it turns to a red powder, which the Chymifts call 
 Mercurius precipitates per fe. But to fucceed in this 
 operation it is abiblutely necefTary that the heat be 
 fuch as is above- fpecified ; for this metallic fubilance 
 may remain expofed to a weaker heat for a confi- 
 derable number of years, without undergoing any 
 fenfible alteration. 
 
 Some Chymifts fancied that by this opera- 
 tion they had fixed Mercury and changed its na- 
 ture ; but without any reafon : for if the Mercury 
 thus feemingly tranfmuted be expofed to a fome- 
 what ftronger degree of fire, it fublimes and exhales 
 in vapours as ufual ; and thofe vapours collected 
 are nothing elfe but running Mercury, which has 
 recovered all its properties without the help of any 
 additament. 
 
 Mercury has the property of difiblving all the 
 metals, Iron only excepted. But it is a condition 
 
 abfolutely
 
 THEORY ^fCHYMis TRY. 79 
 
 abfolutely necefiary to the fuccefs of fuch diflblu- 
 tion, that the metalline fubftances be poffefled of 
 their phlogifton ; for if they be calcined, Mercury 
 cannot touch them : and hence it follows that Mer- 
 cury doth not unite with fubftances that are purely 
 earthy. Such a combination of a metal with Mercury 
 is called an Amalgam. Trituration alone is fufficient 
 to efFecl: it j however, a proper degree of heat allb is 
 of ufe. 
 
 Mercury amalgamated with a metal gives it a 
 confiftence more or lefs foft, and even fluid, accord- 
 ing to the greater or fmaller proportion of Mercury 
 employed. All amalgams are foftened by heat, 
 and hardened by cold. 
 
 Mercury is very volatile ; vaftly more fo than the 
 moft unfixed metals : moreover the union it con- 
 tracts with any metal is not fufficiently intimate to 
 entitle the new compound refulting from that union 
 to all the properties of the two fubftances united ; 
 at leaft with regard to their degree of fixity and vo- 
 latility. From all which it follows that the bed 
 and fureft method of feparating it from metals dif- 
 folved by it, is to expoie the amalgam to a degree 
 of heat fufficient to make all the Quick-filver rife 
 and evaporate ; after which the metal remains in the 
 form of a powder, and being fufed recovers its 
 malleability. If it be thought proper to fave the 
 Quick-filver, the operation muft be performed in 
 elofe vefiels, which will confine and coliecl: the 
 mercurial vapours. This operation is moft fre- 
 quently employed to feparate Gold and Silver from 
 the feveral forts of earths and fands with which they 
 are mixed in the ore ; becaufe thefe two metals, 
 Gold efpecially, are of fufficient value to compen- 
 fate the lofs of Mercury, which is inevitable in this 
 procefs : befides, as they very readily amalgamate 
 with it, this way of feparating them from every 
 thing unmetallic is very facile and commodious. 
 
 Mercury
 
 8o ELEMENTS^/* the 
 
 Mercury is diflblved by acids ; but with circum- 
 flances peculiar to each parricular fort of acid. 
 
 The vitriolic acid, concentrated and made boiling 
 hot, feizes on it, and prefently reduces it to a kind 
 of white powder, which turns yellow by the affufion 
 of water, but does not difiblve in it : it is called 
 Turbith Mineral. However, the vitriolic acid on this 
 occafion unites with a great part of the Mercury, in 
 fuch a manner that the compound is foluble in wa- 
 ter. For if to the water which was ufed to wadi 
 the Turbith a fixed alkali be added, there falls in- 
 ftantly a ruflet-coloured precipitate, which is no 
 other than Mercury feparated from the vitriolic 
 acid by the intervention of the alkali. 
 
 This diflblution of Mercury by the vitriolic acid 
 is accompanied with a very remarkable phenome- 
 non -, which is, that the acid contracts a ftrongfmell 
 of volatile fpirit of fulphur : a notable proof that 
 part of the phlogifton of the Mercury hath united 
 therewith. And yet, if the Mercury be feparated 
 by means of a fixed alkali, it does not appear to 
 have fuftered any alteration. Turbith Mineral is 
 not fo volatile as pure Mercury. 
 
 The nitrous acid difiblves Mercury with eafe. 
 The folution is limpid and tranfparent, and as it 
 grows cold moots into cryftals, which are a nitrous 
 mercurialfalt. 
 
 If this folution be evaporated to drynefs, the 
 Mercury remains impregnated with a little of the 
 acid, under the form of a red powder, which hath 
 obtained the names of Red Precipitate, and Arcanum 
 Corallinum. This Precipitate, as well as Turbith, 
 is lefs volatile than pure Mercury. 
 
 If this folution of Mercury be mixed with a folu- 
 tion of Copper, made likewife in the nitrous acid, 
 and the mixture evaporated to drynefs, there will 
 remain a green powder called Green Precipitate. 
 
 Thefe
 
 THEORY C/CHYMISTRY. 81 
 
 Thele precipitates are cauftic and corrofive ; and 
 are ufed as fuch in furgery. 
 
 Though Mercury be diflblved more eafily and 
 completely by the nitrous acid than by the vitrio- 
 lic, yet it has a greater affinity with the latter than 
 with the former : for if a vitriolic acid be poured 
 into a folution of Mercury in fpirit of nitre, the 
 Mercury will quit the latter acid in which it was 
 diflblved, and join the other which was added. The 
 fame thing happens when the marine acid is em- 
 ployed inftead of the vitriolic. 
 
 Mercury combined with fpirit of fait forms a fin- 
 gular body , a metalline fait which moots into long 
 cryftals, pointed like daggers. This fait is volatile, 
 and fublimes eafily without decompofition. It is 
 moreover the moft violent of all the corrofives hi- 
 therto difcovered by Chymiftry. It is called Corro- 
 Jive Sublimate^ becaufe it muft absolutely be fublim- 
 ed to make the combination perfect. There are fe- 
 veral ways of doing this : but the operation will 
 never fail, if the Mercury be rarified into vapours, 
 and meet with the marine acid in a (imilar flare. 
 
 Corrofive Sublimate is diflblved by water, but 
 in very fmall quantities only. It is decompounded 
 by fixed alkalis, which precipitate the Mercury in 
 a reddifh yellow powder, called on account of its 
 colour Yellow Precipitate. 
 
 If Corrofive Sublimate be mixed with tin, and 
 the compound diftilled, a liquor comes over which 
 continually emits abundance of denfe fumes, and 
 from the name of its inventor is called the Smoking 
 Liquor of Libavius. This liquor is no other than 
 the tin combined with the marine acid of the Cor- 
 rofive Sublimate, which therefore it hath actually 
 decompounded : whence it follows that this acid 
 hath a greater affinity with tin than with Mercury. 
 
 The marine acid in Corrofive. Sublimate is not 
 quite faturated with Mercury j but is capable of 
 
 VOL, I. G taking
 
 82 E L E M E N T S of the 
 
 taking up a much greater quantity thereof. For if 
 Corrofive Sublimate be mixed with frefh Mercury, 
 and fublimed a fecond time, another compound 
 will be produced containing much more Mercury, 
 and lefs acrimonious ; for which reafon it is named 
 Sweet Sublimate of Mercury \ Mercurius dulcis, Aquila 
 alba. This compound may be taken internally, 
 and is purgative or emetic according to the dofe ad- 
 miniltered. It may be rendered (till more gentle 
 by repeated fublimations, and then it takes the title 
 of Panacea Mercurialis. No way hath hitherto been 
 found to diflblve Mercury in aqua regls without 
 great difficulty, and even then it is but imperfectly 
 aiflblved. 
 
 Mercury unites eafily and intimately with fulphur. 
 If thefe two fubttances be only rubbed together in 
 agentle heat, or even without any heat, they will con- 
 tract an union, tho' but an incomplete one. This 
 combination takes the form of a black powder, which 
 has procured it the name of sEthiops Mineral. 
 
 If a more intimate and perfect union be defired, 
 this compound muft be expofed to a ftronger heat ; 
 and then a red ponderous fubftance will be fublim- 
 ed, appearing like a mafs of mining needles -, this 
 is the combination defired, and is called Cinabar. 
 In this form chiefly is Mercury found in the bow- 
 els of the earth. Cinabar finely levigated acquires a 
 much brighter red colour, and is known to painters 
 by the name of Vermilion. 
 
 Cinabar rifes wholly by fublimation, without 
 fuffering any decomposition ; becaufe the .two fub- 
 ftances of which it confifts, viz. Mercury and Sul- 
 phur, are both volatile. 
 
 Though Mercury unites and combines very well 
 with fulphur, as hath beenfaid, yet it hath lefs affinity 
 with that mineral than any other metal ; Gold 
 only excepted : whence it follows that any of the 
 other metals will decompound Cinabar, by uniting 
 3 with
 
 THEORY of CHlrMistfc v. 
 
 with its fulphur j and fo fetting the Mercury at li- 
 berty to appear in its ufual form. Mercury thus 
 feparated from fulphur is efteemed the pureft, 
 and bears the name of Mercury revivified from Ci- 
 nabar. 
 
 Iron is generally ufed in this operation, prefera- 
 bly to the other metals, becaufe among them all ic 
 has the greateft affinity with fulphur, and is the only- 
 one that has none with Mercury. 
 
 Cinabar may alfo be decompounded by means of 
 fixed alkalis ; the affinity of thefe falts with fulphuf 
 being generally greater than that of any metalline 
 fubftance whatever. 
 
 CHAP. IX. 
 
 Of the SEMI-METALS. 
 
 . I. Of R fi G u L tr s OF ANTIMONY.' 
 
 RE G U LU S of Antimony is a metallic fubftance 
 of a pretty bright white colour. . It has the 
 fplendour, opacity, and gravity of a met?.t : but it 
 is quite unmalleable, and crumbles to dull, inftead 
 of yielding or ftretching, under the hammer ; on 
 which account it is claflfed with the Semi-metals. 
 
 It-begins to flow as foon as it is moderately red ; 
 but, like the other Semi-metals, it cannot ftand a 
 violent degree of fire ; being thereby diffipated into 
 fmoke and white vapours, which adhere to fuch cold 
 bodies as they meet with, and fo are collected into 
 9. kind of farina called Flowers of Antimony. 
 
 If Regulus of Antimony, inftead of being ex- 
 pofed to a ftrong fire, be only heated fo mode- 
 rately that it mail not even melt, it will calcine, 
 lofe its phlogifton, and take the form of a greyifti 
 
 G 2 powder
 
 84. E L E M E N T S of the 
 
 powder deftitute of all fplendour : this powder is- 
 called Calx of Antimony. 
 
 This calx is not volatile like the Regulus, but 
 will endure a very violent fire; and being, ex- 
 pofed thereto will flow, and turn to a glals of the 
 ytllowilli colour of a hyacinth. 
 
 It is to be obierved that the more the Regulus is 
 deprived of its phlogifton by continued calcination, 
 the more refractory is the calx obtained from it. 
 The glafs thereof has alfo fo much the lefs colour, 
 and comes the nearer to common glals. 
 
 The calx and the Glafs of Antimony will recover 
 their metalline form, like every other Calx and 
 Glafs of a metal, if reduced by reftoring to them 
 their loft phlogifton. Yet if the calcination be car- 
 ried too far, their reduction will become much more 
 difficult, and a much fmaller quantity of Regulus 
 will be refufcitated. 
 
 Regulus of Antimony is capable of diflblvingthe 
 metals , but its affinities with them are various, and 
 differ according to the following order. It affecls 
 Iron the moft powerfully, next Copper, then Tin, 
 Lead, and Silver. It promotes the fufion of metals, 
 but makes them all brittle and unmallcable. 
 
 It will not amalgamate with Mercury ; and 
 though by certain proccfles, particularly the addi- 
 tion of water and continued trituration, a fort of 
 union between thefe two fubftances may be pro- 
 duced, yet it is but apparent and momentary ; for 
 being left to themfelves and undifturbed they 
 quickly difunite and feparate *. 
 
 * M. Malouin, however, hath found a way to unite thefe two 
 metallic fubilances : but then he does it by the interpofuion of 
 fulphur ; that is, he combines crude Antimony with Mercury. 
 This combination is brought about in the fame way that yfcthi- 
 ops Mineral is made ; viz. either by fufion, or by trituraticn 
 only without fire. It refembles the common <thiops, and 
 M. Malouin calls it JEthiops of Antimony. He obferved that 
 Mercury unites with Antimony much more intimately, by 
 melting, than by rubbing them together. 
 
 * 3 The
 
 THEORY of CHYMISTRY. 85 
 
 The vitriolic acid, aflifted by heat, and even by 
 diftillation, diffblves Regulus of Antimony. The 
 nitrous acid likewife attacks it : but the folution can 
 by no art be made clear and limpid : fo that the Re- 
 gulus is only calcined, in a manner, by this acid. 
 
 The marine acid difiblves it well enough; but 
 then it muft be exceedingly concentrated, and appli- 
 ed in a peculiar manner, and efpecially by diftilla- 
 tion. One of the beft methods of procuring a per- 
 fect union between the acid of fea-falt and Regulus 
 of Antimony, is to pulverize the latter, mix it with 
 corrofive fublimate, and diftill the whole. There 
 rifes in the operation a white matter, thick and 
 fcarce fluid, which is no other than the Regulus of 
 Antimony united and combined with the acid of 
 fea-falt. This compound is extremely corrofive, 
 and is called Butter of Antimony. 
 
 It is plain that the corroiive fublimate is here de- 
 compounded that the Mercury is revivified, and 
 that the acid which was combined therewith hath 
 quitted it to join the Regulus of Antimony, with 
 which its affinity is greater. This Butter of Anti- 
 mony by repeated diftillations acquires a confider- 
 able degree of fluidity and limpidnefs. 
 
 If the acid of nitre be mixed with Butter of An- 
 timony, and the whole diftilled, there rifes an acid 
 liquor, or a fort of aqua regis, which ftill retain? 
 fome of the diflblved Regulus, and is called Bezo- 
 ardic Spirit of Nitre. After the diftillation there 
 remains a white matter, from which frefh fpirit of 
 nitre is again abftracled, and which being th?n 
 wafhed with water is called Bezoar Mineral. This 
 Bezoar Mineral is neither fo volatile, nor fo cauftic, 
 as Butter of Antimony ; becaufe the nitrous acid 
 hath not the property of volatilizing metallic fub- 
 ftances, as the marine acid does, and becaufe it re* 
 mains much more intimately combined with the 
 reeuline part. 
 
 G 3 If
 
 86 ELEMENT.SC/" the 
 
 If Butter of Antimony be mixed with water, the 
 liquor immediately becomes turbid and milky, and 
 3 precipitate falls, which is nothing but the metal- 
 lic matter partly feparated from its acid, which is 
 too much weakened by the addition of water to 
 keep it difiblved. Yet this precipitate ftili retains 
 a good deal of acid ; for which reaibn it continues 
 to be a violent emetic, and in fome degree corro- 
 five. It hath therefore been very improperly called 
 Mercurius Vit#. 
 
 The proper folvent of Regulus of Antimony is 
 pqua rcgis , by means whereof a clear and limpid 
 folution of this Semi-metal may be obtained. 
 
 Regulus of Antimony mixed with nitre, and pro- 
 jected into a red-hot crucible, lets the nitre in a 
 flame, and makes it detonate. As it produces this 
 effect by means of its phlogilton, it muft needs at 
 the fame time be calcined, and lofe its metallic pro- 
 perties, which accordingly happens, and when the 
 nitre is in a triple proportion to the Regulus, the 
 latter is fo perfectly calcined as to leave only a white 
 powder, which is fuied with great difficulty, and 
 then turns to a faintly coloured glafs, not very dif- 
 ferent from common glafs, and which is not redu- 
 cible to a Regulus by the addition of inflammable 
 matter; at lead it yields but a very fmall quantity 
 thereof. If lefs nitre be uied, the calx is not fo 
 white , the glafs it produces is more like a metal- 
 line glafs, and is more eafily reduced. The calx 
 of the Regulus thus prepared by nitre is called, on 
 Account of the medicinal virtue afcribed to it, Dia- 
 phoretic Antimony, or Diaphoretic Mineral 
 
 Nitre always becomes an alkali by deflagration, 
 and in the prefent cafe retains part of the calx, 
 \diich it even renders ibluble in water. This calx 
 may be feparated from the alkali, if an acid be em- 
 ployed to precipitate it ; and then it is called Mate- 
 fia Perlafp. This pearly matter is a calx of Anti- 
 mony
 
 THEORY C/^CHYMISTRY. 87 
 
 mony, fo completely deprived of its phlogifton as 
 to be altogether incapable of reduction to a Re- 
 gulus. 
 
 Regains of Antimony readily joins and unites 
 with fulphur, forming therewith a compound which 
 has a very faint metallic fplendour. This com- 
 pound appears like a mafs of long needles adhering 
 together laterally ; and under this form it is ufu- 
 ally found in the ore, or at leaft when only feparat- 
 ed by fufion from the ftones and earthy matters 
 with which the ore is mixed. It is called Crude 
 Antimony. 
 
 Antimony flows with a moderate heat, and be- 
 comes even more fluid than other metallic fub- 
 ftances. The action of fire diffipates or confumes 
 the fulphur it contains, and its phlogifton allb, fo 
 as to convert it into a calx and a glais, as it does 
 the Regulus. 
 
 Aquaregis, which we obferved to be the proper 
 folvent of the Regulus, being poured on Antimony, 
 attacks and diflblves the reguline parr, but touches 
 not the fulphur ; in conlequence whereof it decom- 
 pofes the Antimony, and feparates its fulphur from 
 its Regulus. 
 
 There are feveral other ways of effecting this de- 
 compofition, and obtaining the reguline part of An- 
 timony by itfelf : they confift either in deftroying 
 the fulphureous pare of the Antimony by combuf- 
 tion, or in melting the Antimony with fome fub- 
 ftance, which has a greater affinity than its reguline 
 part with fulphur. Moft metals are very fit for this 
 latter purpoie : for though the Regulus has a con- 
 fiderable affinity with fulphur, yet all the metals, 
 except Gold and Mercury, have a greater. 
 
 If therefore Iron, Copper, Lead, Silver, or Tin, 
 be melted with Antimony, the metal employed 
 will unite with the fulphur, and feparafe it from the 
 Regulus. 
 
 G 4 "It
 
 88 E L E M E N T s of the 
 
 It muft be obferved that, as thefe metals have 
 fome affinity with the Regulus of Antimony, the 
 Regulus will be joined in the operation by fome of 
 the metal employed as a Precipitant, (fo thofe lub- 
 ftances are called which ferve as the means of fepa- 
 rating two bodies from each other ; ) and therefore the 
 Regulus procured in this manner will not be abfo- 
 lutely pure : on this account care is taken to diitin- 
 guifh each by adding the name of the metal em- 
 ployed in its precipitation ; and thence come thefe 
 titles, Martial Regulus of Antimony, or only Martial 
 Regulus, Regulus Veneris ; and fo of the reft. 
 
 Antimony is employed with advantage to leparate 
 Gold from all the other metals with which it may 
 be alloyed. It has been (hewn that all the metals 
 have a greater affinity, than the rcguline part of 
 Antimony, with fulphur, Gold only excepted ; which 
 is incapable of contracting any union therewith: and 
 therefore, if a mafs compounded of Gold and fe- 
 veral other metals be melted with Antimony, every 
 thing in that mafs which is not Gold will unite with 
 the fulphur of the Antimony. This union occafions 
 two feparations, to wit, that of the fulphur of the 
 Antimony from its reguline part, and that of the 
 Gold from the metals with which it was adulterat- 
 ed ; and from the whole two new compounds arife j 
 namely, a combination of the metals wich the ful- 
 phur, which being lighted riles to the furface in 
 fufion ; and a metalline mafs formed of the Gold 
 and the reguline part of the Antimony united toge- 
 ther, which being much the heavieft finks to the 
 bottom. There is no difficulty in parting the Gold 
 from the Regulus of Antimony with which it is 
 alloyed : for the metalline mafs need only be expo- 
 fed to a degree of fire capable of diflipating into 
 vapours all the Semi-metal it contains ; which being 
 very volatile, the operation is much ealier, and more 
 expeuitioufly finilhed, than if the metals with which 
 
 the
 
 THEORY 0/*CHYMiSTRY. 80 
 
 I V^ 7 
 
 the Gold was debafed were to be vitrified on the 
 cupel , without taking into the account that if Sil- 
 ver were one of them, recourfe muft needs be had 
 to the procefs of quartation after that of the cupel. 
 
 If equal parts of nitre and Antimony be mixed 
 together, and the mixture expofed to the action of 
 fire, a violent detonation enfues , the nitre deflagra- 
 ting confumes the fulphur of the Antimony, and 
 even a part of its phlogifton. After the detonation 
 there remains a greyifh matter which contains fixed 
 nitre, vitriolated tartar, and the reguline part of 
 the Antimony in fome meafure deprived of its phlo- 
 gifton, and half vitrified by the action of the fire, 
 which is confiderably increafed by the deflagration. 
 This matter is called Liver of Antimony. 
 
 If inftead of equal parts of nitre and Antimony, 
 two parts of the former be ufed to one of the lat- 
 ter, then the reguline part lofes much more of its 
 phlogifton, and remains in the form of a yellowifli 
 powder. 
 
 Again, if three parts of nitre be taken to one of 
 Antimony, the Regulus is thereby entirely robbed 
 of its phlogifton, and converted to a white calx 
 which bears the name of Diaphoretic Antimony^ or 
 Diaphoretic Mineral. The pearly matter may be 
 precipitated by pouring an acid on the faline fub-.. 
 fiances which here remain after the detonation, in 
 the fame manner as we mewed above was to be 
 done with regard to the Regulus. 
 
 In the two laft operations, where the nitre is in a 
 double or triple proportion to the Antimony, the 
 reguiine part is found after the detonation to be con- 
 verted into a calx, and not into a half vitrified 
 matter, which we have feen is the effect when equal 
 parts only of nitre and Antimony are ufed. The 
 reafon of this difference is, that in thefe two cafes the 
 reguline part, being wholly, or almoft wholly, de- 
 prived of its phlogifton, becomes, as was obferved, 
 
 more
 
 go E L E M E N T S of the 
 
 more difficult to fufe, and confequently cannot be- 
 gin to vitrify in the fame degree of heat as that 
 which hath not loft fo much of its phlogifton. If 
 inftead of performing the operation with equal pares 
 of nitre and Antimony alone, a portion of ibme 
 fubftance which abounds with phlogifton be added, 
 in that cafe the fulphur only of the Antimony will 
 be confumed, and ihe Regulus will remain united 
 with its phlogifton and feparated from its fulphur. 
 
 The Regulus prepared in this manner is ablb- 
 lutely pure, becaufe no metalline fubftance taing 
 employed, none can mix with and adulterate it. 
 It is called Regulus of Antimony ptr ft, or only Rt- 
 %ulus of Antimony. 
 
 It is true indeed that in this operation much of 
 the reguline part unavoidably loles its phlogifton 
 and is calcined, and confequently a much fmaller 
 quantity of Regulus is obtained than when metal- 
 line precipitants are employed : but this lofs is eafily 
 repaired, if it be thought proper, by reftoring to 
 the calcined part its loft phlogifton. 
 
 Antimony melted with two parts of fixed alkali 
 yields no Regulus, but is entirely difiblved by the 
 fait, and forms with it a mafs of a reddilh yellow 
 colour. 
 
 The reafon why no precipitate is produced on 
 this occafion is, that the alkali uniting with the 
 fulphur of the Antimony forms therewith the com- 
 bination called Liver of Sulphur, which by its na- 
 ture is qualified to keep the reguline part diflblved. 
 This mafs formed by the union of the Antimony 
 with the alkali is foluble in water. If any acid 
 whatever be dropt into this folution, there falls a 
 precipitate of a reddifh yellow colour ; becaufe the 
 acid unites with the alkali, and forces it to quit the 
 matters with which it was combined. This preci- 
 pitate is called Golden Sutybur of Antimony. 
 
 As
 
 THEORY <?/* CHYMISTRY. 91 
 
 As in the operation for preparing Regulus of 
 Antimony per fe, fome of the nitre is, by the in- 
 flammable matters added thereto, turned to an al- 
 kali, this alkali leizes on part of the Antimony, 
 and therewith forms a compound like that juft de- 
 fcribed. Hence it comes that ir" the fcoria forme^ 
 in this proceis be djffolved in water, and an ad4 
 dropped into the folution, a true golden iulphurof 
 Antimony is thereby ieparated. 
 
 This union of Antimony with an alkali may alfo 
 be brought about by the humid way j that is, by 
 making ufe of an alkali rclolved into a liquor, a^ici 
 boiling the mineral in it. The alkaline liquor, in 
 proportion as it afts upon the Antimony, gradually 
 becomes reddifh and turbid. If left to fettle and 
 cool when well faturated therewith, it gradually de- 
 pofites the Antimony it had taken up, which preci- 
 pitates in the form of a red powder : and this preci 
 pitace is the celebrated remedy known by the name 
 of Kermes Mineral. It is plain that the kermes i$ 
 nearly the fame thing with the golden fulphur : ye; 
 it differs from it in fome refpedts , and efpecially in 
 this, that being taken inwardly it operates much 
 more gently than the golden fulphur, which is a 
 violent emetic. Nitre fixed by charcoal, and refoj- 
 ved into a liquor, is the only alkali employed IA. 
 preparing the kermes. 
 
 It was (hewn above that Regulus of Antimony 
 mixed and diftilled with corrolive fublimate decom- 
 pounds it, difengages the Mercury, and joining 
 itfelf to the marine acid forms therewith a new 
 combination, called Butter of Antimony. If the 
 fame operation be performed with crude Antimo- 
 ny inftead of its Regulus, the fame effefts are 
 produced : but then the Antimony itfelf is alfo de- 
 compofed-, that is, the reguline part is feparated 
 from the fulphur, which being fet free unites, with 
 the Mercury, now alfo at liberty, and thcfe two 
 
 together
 
 92 E L E M E M T s of the 
 
 together form a true cinabar called Cinalar of An- 
 timony. 
 
 . II. Of BISMUTH. 
 
 BISMUTH, known alfo by the name of Tin-glafs, 
 is a femi -metal, having almoft the fame appearance 
 as Regulus of Antimony , yet it has a more dufky 
 caft, inclining fomewhat to red, and even prefents 
 fome changeable ftreaks, efpecially after lying long 
 in the air. 
 
 When expofed to the fire it melts long before it 
 is red, and confequently with lefs heat than Regu- 
 lus of Antimony, which does not flow, as was 
 Ihewn above, till it begin to be red-hot. It be- 
 comes volatile, like all the other femi-metals, when 
 acted on by a violent fire : being kept in fufion by 
 a proper degree of heat it lofes its phlogifton with 
 its metallic form, and turns to a powder or a calx ; 
 and that again is converted into glafs by the conti- 
 nued action of fire. The calx and glafs of Bif- 
 muth may be reduced, like any other metallic 
 calx, by reftoring their phlogifton. 
 
 Bifmuth mixes with all the metals in fufion, and 
 even facilitates the fufion of fuch as do not other- 
 wife flow readily. It whitens them by its union, 
 and deftroys their malleability. 
 
 It amalgamates with Mercury, if they be rubbed 
 together with the addition of water : yet after 
 fome time thefe two metalline fubrtances defert 
 each other, and the Bifmuth appears again in the 
 form of a powder. Hence it is plain that the union 
 it contracts with Mercury is not perfect ; and yet it 
 has the fingular property of attenuating Lead, and 
 altering it in fuch a manner that it afterwards amal- 
 gamates with Mercury much more perfectly, fo as 
 even to pafs with it through fhamoy leather without 
 any feparation. The Bifmuth employed in making 
 this amalgama afterwards leparates from it fponta- 
 
 neoufly,
 
 THEORY 0/* CH YMI STRY. 93 
 
 neoufly, as ufual; but the Lead dill continues 
 united with the Mercury, and always retains the 
 property thus acquired. 
 
 The vitriolic acid does not difiblve Bifmuth : its 
 proper folvent is the nitrous acid, which diflblves 
 it with violence, and abundance of fumes. 
 
 Bifmuth diffblved in the nitrous acid is precipi- 
 tated not only by alkalis, but even by the bare ad- 
 dition of water. This precipitate is extremely white, 
 and known by the name of Magiftery of Bifmuth. 
 
 The acid of fea-falt and aqua regis iikewife act 
 upon Bifmuth, but with lefs violence. 
 
 This femi-metal does not fenfibly deflagrate with 
 nitre ; yet it is quickly deprived of its phlogifton, 
 and turned into a verifiable calx, when expofed 
 with it to the adion of fire. 
 
 It readily unites with fulphur in fufion, and forms 
 therewith a compound which appears to confift of 
 needles adhering laterally to each other. 
 
 It may be feparated from the fulphur with which 
 it is combined, by only expofing it to the fire, 
 v/ithout any additament , for the fulphur is either 
 confumed or fublimed, and leaves the Bifmuth be- 
 hind. 
 
 . III. Of Z i N c. 
 
 ZINC to appearance differs but little from Bif- 
 muth, and has even been confounded with it by 
 feveral authors. Neverthelefs, befides that it has 
 fomething of a blueifh caft, and is harder than Bif- 
 muth, it differs from it efTentially in its properties, 
 as will prefently be fhewn. Thefe two metallic, 
 fubftances fcarce refemble each other in any thing, 
 but'the qualities common to all femi- metals. 
 
 Zinc melts the moment it grows red in the fire, 
 and i hen alfo begins to turn to a calx, which, like 
 any other metallic calx, may be reduced by means 
 of the phlogifton : but if the fire be considerably 
 
 increafcd,
 
 <74 ELEMENTS^ tie- 
 
 increafed, it fublimes, flames, and burns like an oil}' 
 matter; which is a proof" of the great quantity of 
 phlogiiton in its compofition. At the fame time 
 abundance of flowers rile from it in the form of 
 white flakeSj flying about in the air like very light 
 bodies ; and into this form may the whole fubftance 
 of the Zinc be converted. Several names have 
 been given to thefe flowers, fuch as Pompholyx, 
 Philofophic Wool. They are fuppofed to be no 
 othtfr than the Zinc itfelf deprived of its phlogifton ; 
 yet nobody has hitherto been able to refufcitate 
 them in the form of Xinc, by reftoring their phlo- 
 gifton according to the methods ufed in the reduc- 
 tion of metals. Though they rife in the air with 
 very great eafe while the Zinc is calcining, yet 
 when once formed they are very fixed ; for they 
 withftand the utmoft violence of fire, and are ca- 
 pable of being vitrified, efpecially if joined with a 
 fixed alkali. They are foluble in acids. 
 
 Zinc unites with all metalline fubftances, except 
 Biimuth. It has this fingular property, that being 
 mixed with Copper, even in a confiderable quan- 
 tity, fuch as a fourth part, it does not greatly lefien 
 the ductility thereof, and at the fame time com- 
 municates to it a very beautiful colour not unlike 
 that of Gold : on which account the compofition is 
 frequently made, and produces what is called Brafs. 
 This metal melts much more eafily than Copper 
 alone, becaufe of the Zinc with which it is alloyed. 
 It it be expofed to a great degree of heat, the Zinc 
 which it contains takes fire, and fublimes in white 
 flowers, juft as when IE is pure. 
 
 It is to be obferved that Erafs is ductile only 
 while it is cold, and not then unlefs the Zinc ufed 
 in making it was very pure ; otherwife the compo- 
 fition will prove but a Tombac or Prince's Metal, 
 having very little malleability. 
 
 Zinc
 
 THEORY tf/'CHYMisTRY. 95 
 
 Zinc is very volatile, and carries off with it any 
 metallic fubftance with which it is fufed, making a 
 kind of fublimate thereof. In the furnaces where 
 they fmelt ores containing Zinc, the matter thus 
 fublimed is called Cadmia Fornacum^ to diftinguifh 
 it from the native Cadmia called alfo Calamine, or 
 Laps Calaminaris , which, properly fpeaking, is 
 an ore of Zinc, containing a great deal of that 
 femi-metal, together with fome Iron, and a ftony 
 fubftance. The name of Cadmia Fornacum is not 
 appropriated folely to the metallic fublimates pro- 
 cured by means of Zinc, but is given in general to 
 all the metallic fublimates found in fmelting houfes. 
 
 If a violent and fudden heat be applied to Zinc, 
 it fublimes in its metalline form ; there not being 
 time for it to burn and be refolved into flowers. 
 
 This femi-metal is foluble in all the acids, but 
 efpecially in fpirit of nitre, which attacks and dif- 
 folves it with very great violence. 
 
 Zinc has a greater affinity than iron or copper 
 with the vitriolic acid ; and therefore k decom- 
 pounds the green and blue vitriols, precipitating 
 thofe two metals by uniting with the vitriolic acid, 
 with which it forms a metallic fait, or vitriol, called 
 White Vitriol^ or Vitriol of Zinc. 
 
 Nitre mixed with Zinc, and projected into a red- 
 hot crucible, detonates with violence, add during 
 the detonation there rifes a great quantity of white 
 flowers, like thofe which appear when it is calcined 
 by itfelf. 
 
 Sulphur has no power over Zinc. Even liver 
 of fulphur, which diflblves all other metallic fub- 
 ftances, contracts no union with this femi-metal. 
 
 MefT. Hellot and Malouin have beftowed a great 
 deal of pains on this femi-metal. An account of 
 their experiments is to be found in the Memoirs of 
 the Academy of Sciences. 
 
 . IV. Of
 
 96 E L E M E N T S Of the 
 
 . IV. Of REGULUS OF ARSENIC. 
 
 REGULUS of Arfcnic is the moft volatile of 
 all the femi-metals. A very moderate heat makes 
 it wholly evaporate, and fly off in fumes , on which 
 account it cannot be brought to fufion, nor can any 
 confiderable mafies thereof be obtained. It has a 
 metallic colour, fomewhat refembling Lead $ but 
 it foon lofes its fplendour when expoled to the air. 
 
 It unites readily enough with metallic fubftances, 
 having the fame affinities with them as Regulus of 
 Antimony hath. It makes them brittle, and unmal- 
 leable. It hath alfo the property of rendering them 
 volatile, and greatly facilitates their fcorirkation. 
 
 It very eafily parts with its phlogifton and its me- 
 tallic form. When expoled to the fire it rifes in a 
 kind of mining cryftalline calx, which on that ac- 
 count looks more like a faline matter than a metal- 
 lic calx. To this calx or thefe flowers are given 
 the names of White Arfenic^ Cryjlalline Arfenic y and 
 moft commonly plain Arftnic. 
 
 The properties of this fubftance are very fingular, 
 and extremely different from thofe of any other 
 metallic calx. Hitherto it hath been but little ex- 
 amined ; and this led me to make fome attempts 
 towards difcovering its nature, which may be icen 
 in the Memoirs of the Academy of Sciences. 
 
 Arfenic differs from every other metalline calx, 
 firft, in being volatile ; whereas the calxes of all 
 other metallic fubftances, not excepting thofe of the 
 moft volatile femi-metals, Inch as Regulus of An- 
 timony and Zinc, are exceedingly fixed ; and le- 
 condly, in having a faline character, which is not 
 found in any other metalline calx. 
 
 The faline character of Arfenic appears, firft, from 
 its being foluble in water ; fecondly, from its corro- 
 live quality, which makes it one of the moft vio- 
 lent
 
 THEORY ^CHYMISTRY. 97 
 
 lent poifons : a quality from which the other metal- 
 lic fubftances are free, when they are riot combined 
 with fome feline matter. Regulus of Antimony 
 muft however be excepted. But then the beft Chy- 
 mifts agree that this femi-metal is either nearly of 
 the lame nature with Arfenic^ or contains a portion 
 thereof in its competition : befides^ its noxious 
 qualities never difcover themfelves fo plainly as 
 when it is combined with fome acid. Laftly, Arie- 
 nic afts juft like the vitriolic acid upon nitre ; that 
 is, it decompounds that neutral fait, by expelling 
 its acid from its alkaline bafis, of which it takes 
 poffefiion, and therewith forms a new faline com- 
 pound. 
 
 This combination is a fpecies of fait that is per- 
 fectly neutral. When the operation is performed 
 in a clofe veflfel, the fait moots into cryftals in the 
 form of right-angled quadrangular prifms, ter- 
 minated at each extremity by pyramids that are 
 alfo quadrangular and right-angled ; fome of which 
 however, inftead of ending in a point, are obtufe 
 as if truncated. The confequence is different 
 when the operation is performed in an open veffel^ 
 for then nothing is obtained but an alkaline fait 
 impregnated with Arfem'c, which cannot be cryf- 
 tallized. ' 
 
 The caufe of this different effecl: is that, when 
 the Arfenic is once eno-aaed in the alkaline bafis of 
 
 o c? 
 
 the nitre, it can never be feparated from it by the 
 utmoft force of fire, fo long as it is kept in a dole 
 veffel ; whereas, if you expofe it to the fire without 
 that precaution, it readily feparates from it. This 
 property of Arfenic was never before obferved by 
 any Chymift, and therefore this our new fpecies of 
 Neutral arfenical fait was abfolutely unknown til! 
 lately. 
 
 This new fait poffeffes many fingular properties, 
 the chief of which are thefe. Firft, it cannot be 
 
 VOL. I. H de-
 
 $8 ELEMENTS^ the 
 
 decompounded by the intervention of any acid, 
 even the ftrongeft acid of vitriol ; and this, joined 
 to its property of expelling the nitrous acid trom 
 its bafis, (hews that it has a very great affinity with 
 fixed alkalis. 
 
 Secondly, this very fait, on which pure acids 
 have no efFeft, is decompounded with the greatelt 
 eafe by acids united with metallic fubftances. The 
 reafon of this phenomenon is curious, and furnifhes 
 us with an inftance of what we advanced concern- 
 ing double affinities. 
 
 If to a folution of any metallic fubftance what- 
 ever, made by any acid whatever, (except that of 
 Mercury by the marine acid, and that of Gold by 
 aqua regis\ a certain quantity of our New Salt dif- 
 folved in water be added, the metallic fubftance is 
 inftantaneoufly feparated from the acid in which it 
 was diflblvcd, and falls to the bottom of the liquor. 
 
 All metallic precipitates obtained in this manner 
 are found to be a combination of the metal with 
 Arfenic , whence it necefiarily follows that the new 
 Neutral Salt is by this means decompounded, its 
 -arfenical part uniting with the metallic fubftance, 
 and its alkaline bafis with the acid in which that 
 fubftance was difiblved. 
 
 The affinities of thtfe feveral bodies muft be con- 
 fidered as operating on this occafion in the following 
 manner : The acids which tend to decompound the 
 Neutral Salt of Arfenic, by virtue of their affinity 
 with its alkaline bafis, are not able to accompliih it, 
 becanie this affinity is powerfully counteracted by 
 that which the Arfenic has with the fame alkaline 
 bafis, and which is equal or even fuperior to theirs. 
 But if thefe acids happen to be united with a fub- 
 itance which naturally has a very great affinity with 
 the arfenical part ot the Neutral Salt, then, the 
 two parts of which this Salt confifts being drawn 
 different ways by two feverai affinities tending to fe- 
 7 parate
 
 THEORY of C H Y M i s T R Y. 99 
 
 parate them from each other, the Salt will -undergo 
 a decompofition, which could not have been effected 
 without the help of this iecon-d affinity- Now as me- 
 tallic fubftances have a great affinity with Arfenic, it 
 is not furprifing that the Neutral Salt of Arfemc, 
 which cannot be decompounded by a pure acid, 
 fiiould neverthelefs yield to an acid combined with 
 a metal, The decompofition of this Salt, therefore^ 
 and the precipitation which of courle it produces in 
 metallic folutions, are brought about by the means 
 of a double affinity ; namely, that of the acid. with 
 the alkaline bafis of the Neutral Salt, and that of 
 the metal with the arfenical part of that fait. 
 
 Arfenic has not the fame effect on fea-falt as on 
 nitre, and cannot expel its acid : a very fmgular 
 phenomenon, for which it is hard to affign a reafon \ 
 for the nitrous acid is known to have a greater affi- 
 nity than the marine acid with alkalis, and even 
 with the bafis of fea-falt itfelf. 
 
 Yet Arfenic may be combined with the bafis of 
 fea-falt, and a Neutral fait thereby obtained, like 
 that which refults from the decompofition of nitre 
 by Arfenic : but for that purpofe a quadrangular 
 nitre muft be firft prepared, and Arfenic applied 
 thereto as to common nitre. 
 
 The Salt produced by uniting. Arfenic with the 
 bafis of fea-falt very much refembles the Neutral 
 fait of Arfenic above treated of, as well in the fi- 
 gure of its cryftals as in its feveral properties. 
 
 Arfenic prefents another fmgular phenomenon, 
 both with the alkali of nitre and with that of fea- 
 falt ; which is, that if it be combined with thefe 
 falts in a fluid ftate, it forms with them a faline 
 compound, quite different from the Neutral falts 
 of arfenic which refult from the decompofition of 
 nitrous falts. 
 
 This faline compound, which I call Liver ofArfe- 
 
 /V, takes up a much greater quantity of Arfenic 
 
 H 2 than
 
 ioo ELEMENTS of 
 
 than is necefTary for the perfect faturation of the al- 
 kali. It has the appearance of a glue, which is fo 
 much the thicker the more Arfenic it contains. Its 
 fmell is difagreeable ; it attracts the moifture of the 
 air, and does not cryftallizej it is eafily decom- 
 pounded by any acid whatever, which precipitates 
 the Arfenic and unites with the alkali. Laftly, the 
 effects it produces on metallic toluiions are different 
 from thofe of our neutral arienical falts. But the 
 bounds which I have fet myfelf in this treatife will 
 not allow me to be more particular. Such as have 
 the curiofity to enquire further into the fubject may 
 confult my Difiertations on Arfenic, publifhed 
 among the Memoirs of the Academy of Sciences. 
 
 Arlenic is eafily reduced to a Regulus, It need 
 only be mixed with any matter containing the phlo- 
 gifton, and by the help of a moderate heat a true 
 Regulus will fublime. This Regulus, as was laid, 
 is very volatile, and calcines with the grcateft eafe^ 
 which is the reafon why it cannot be obtained but 
 in fmall quantities, and alfo why, in order to ob- 
 tain maffes of it, fome have thought of adding 
 thereto fome metal with which it has a great affi- 
 nity, fuch as Copper or Iron ; becaufe by joining 
 with the metal it is partly fixed and restrained from 
 flying off. But it is plain the Regulus obtained by 
 this means is not pure, as it muft partake confi- 
 derably of the metal employed. 
 
 Arfenic readily unites with fulphur, and rifes 
 with it in a yellow compound called Orpiment. 
 
 Sulphur cannot be feparated from Arfenic but by 
 the intervention of two bodies only , to wit, a fixed 
 alkali and Mercury. 
 
 The property which Mercury poffeiTes of fepa- 
 rating fulphur from Arfenic is founded on this, that 
 thefe two metallic Jubilances are incapable of con- 
 trading any union ; whereas though mod of the 
 other metals and femi- metals have a greater affinity 
 5 with
 
 THEORY of CHY MIST* Y. 101 
 
 with fulphur than Mercury hath, as was fliewn in 
 treating of the decompofuion of Cinabar, never- 
 thelefs they are all unable to decompound Orpi- 
 ment-, becaufe Ibme of them have as great an affi- 
 nity with Arfenic as with fulphur 5 others have no 
 affinity with either; and laitly, fulphur hath as 
 great an affinity with Arfenic as with any of them. 
 
 It muft be oblerved that, if fixed alkalis be em- 
 ployed to purify Arlenic in this manner, no more 
 inuil be ufed than is neceffary to abforb the fulphur 
 or the phlogifton, of which alfo it is their nature to 
 deprive Arfenic ; for otherwife, as it has been fhewn, 
 that Arfenic readily unites with alkalis, they would 
 abforb a confiderable quantity thereof. 
 
 CHAP. X. 
 
 Of OIL in general. 
 
 OIL is an unctuous body, which burns and 
 confumes with flame and fmoke, and is not 
 foluble in water. It confifts of the phlogiilon 
 united with water by means of an acid. There is 
 moreover in its compofition a certain proportion of 
 earth, more or lets according to each feveral fort 
 of Oil. 
 
 The inflammability of Oil evidently proves that 
 it contains the phlogifton. That an acid is one of 
 its conftituent principles many experiments demon- 
 ftrate, of which thefe are the chief: If certain Oils 
 be long triturated with an alkaline fait, and the al- 
 kali afterwards difiblved in water, cryftals of a true 
 neutral fait will be produced : fome metals, and 
 particularly Copper, are corroded and rufted by 
 Oils, juft as they are by acids : again, acid cryftals 
 H 3 are
 
 102 ELEMENTS of tie 
 
 are found in fome Oils that have been long kept, 
 This acid in Oil ferves undoubtedly to unite its 
 phlogifton with its water , becaufe thele two fub- 
 flances having no affinity with each other cannot be 
 united without the intervention of fuch a medium 
 as an acid, which has an affinity with both. As to 
 the exiftence of water in Oils, it appears plainly 
 when they are decompofed by repeated diftillations, 
 efpecially after mixing them with abforbent earths. 
 Laftly, when an Oil is deftroyed by burning, a cer- 
 tain quantity of earth is conftantiy left behind. 
 
 We are very fure that the abovementioned prin- 
 ciples enter into the compofition of Oils i for they 
 may be obtained from every one of them : but it is 
 not abfolutely certain that they confift of thcfe only, 
 a.id that they do not contain fome other principle 
 which may elcape our notice in decompofing them ; 
 for hitherto it doth not appear, by any experiment 
 we can depend on, that Oil was ever produced by 
 combining together the principles here fpecified ; 
 yet fuch redintegrations are the only means we 
 have of fatisfying ourfelves that we know all the 
 principles which conftitute a body. 
 
 Oils expofcd to the fire in clofe vefiels pafs over 
 ^.Irnoft wholly from the containing vefTel into any 
 other applied to receive them. There remains, 
 however, a fmall quantity of black matter, which 
 is extremely fixed, and continues unalterable as long 
 as it hnth no communication with the external air, 
 be the force of the fire ever fo violent. This matter 
 is no other than part of the phlogifton of the Oil 
 united with its mod fixed and groffeft earth ; and 
 this is what we called Charcoal, or plainly a Coal. 
 
 . I. Of CHARCOAL. 
 
 /WHEN Oil happens to be united to much earth, 
 as it is in vegetable and animal bodies, it leaves a 
 confiderable quantity of Coal or Charred matter. 
 
 ' This
 
 THEORY of CH YMISTR Y. 103 
 
 This Coal, expofed to the fire in the open air, 
 burns and waltes, but without blazing like other 
 combuftible matters : there appears only a (mall 
 blueifh flame, but not the lead fmoke. Mod com- 
 monly it only glows and fparkles, and fo gradually 
 falls into allies, which are nothing but the earth of 
 the body, combined with an alkaline fait in burning. 
 This alkaline fait may be feparated from the earth, 
 by lixiviating the ames with water, which diflblves 
 all the fair, and leaves the earth quite pure. 
 
 Charcoal is unalterable and indeftrudible by any 
 other body but fire ; whence it follows, that when 
 it is not actually kindled and ignited, the moil 
 powerful agents, fuch as the acids, though ever fo 
 ftrong and concentrated, have not the leaft eftedb 
 on it. 
 
 The cafe is otherwife when it is lighted, that is, 
 when its phlogifton begins to feparate from its earth ; 
 for then the pure acid of vitriol being joined there- 
 with contracts an inftantaneous union with its- phlo- 
 gifton, and evaporates in a volatile fuiphureous 
 fpirit. If the vitriolic acid, inftead of being applied 
 quite pure, be firft clogged with fome balis, efpe~ 
 cially an alkaline one, it quits that bafis, enters into 
 a more intimate union with the phlogifton of the 
 burning Coal, and io forms an actual fulphur, with 
 which the alkali now unites and forms a hepar. 
 
 The pure acid of fea-lalt hath not been obierved 
 to act in the leaft upon Charcoal, efpecially when 
 it is not on fire. But when this acid is incorporated 
 with an alkaline or metallic bafis, and combined 
 according to a peculiar procefs with burning Char- 
 coal, it in like manner quits its bafis, unites with 
 the phlogifton, and therewith forms a Phofphorus, 
 of which we have already taken notice. 
 
 Nor has the pure nitrous acid any effect on a 
 charred Coal, even when ignited : and fo far is it 
 from, being able to kindle a cold one, that when 
 
 H 4 poured
 
 104 ELEMENTS of the 
 
 poured on a live one, it extinguifhes it like water, 
 But when this acid is united with a bafis, it quits it 
 rapidly as foon as it touches a burning coal, and 
 rufhes violently into an union with the phlogifton 
 thereof. From this union there probably ariles, as 
 we faid before, a kind of lulphur or phofphorus, 
 which is fo inflammable as to be deftroyed by the 
 fire the very moment it is generated. 
 
 The acids of nitre and vitriol act upon Oils ; but 
 -very differently, according to the quantity of phlegm 
 they contain. If they be weakened with much 
 water, they have no elfect at all upon Oils , if they 
 contain little water, or be dephlegmated to a cer- 
 tain degree, they diflblve them with heat, and with 
 them form compounds of a thick confidence. Acids 
 thus combined in a confiderable proportion with 
 Oils render them foluble in water. 
 
 . II. O/SOAP. 
 
 ALKALIS alfo have the fame property. When 
 an Oil is combined with an acid or an alkali in fucli 
 a manner that the compound refuking from their 
 union is foluble in water; fuch a compound may 
 in general be called a Soap. Soap itfelf hath the 
 property of rendering fat bodies in fome meafure 
 foluble in water ; on which account it is very ufeful 
 for fcouring or cleanfing any thing grealy. 
 
 Oily and ialinefubftances, combined together, ob- 
 ferve the fame general rules as all other combina- 
 tions ; that is, they mutually communicate the 
 properties belonging to each : thus Oils, which na- 
 turally are not foluble in water, acquire by their 
 union with ialine matters the property of diflblving 
 therein; and falts loie by their conjunction with 
 Oils part of their natural tendency to incorporate 
 with water; fo that while they ferve to constitute 
 Soap they do not, as before, attract the moifture 
 of the air, fcfr , and in like manner, as they are not 
 
 in-
 
 THEORY ^CHYMISTRY. 105 
 
 inflammable, they confiderably lefien the inflamrna* 
 bility of the Oils combined with them. 
 
 Acid Soaps are decompounded by alkalis, as al- 
 kaline Soaps are by acids, according to the general 
 rules of affinities. 
 
 The acids of nitre and vitriol, when highly con- 
 centrated, difiblve Oils with fuch violence as to heat 
 them, make them black, burn them, and even fet 
 them on fire. How fea-fak affects Oils is not yet 
 fufficiently afcertained. 
 
 All Oils have the property of difiblving fulphur; 
 which is not at all lurprifing, feeing each of its com- 
 ponent principles hath an affinity with Oil. 
 
 It is alib a property common to all Oils to become 
 more fluid, fubfile, light, and limpid the oftener 
 they are diftilled. On the contrary, by being in- 
 corporated with faline fubftances they acquire a 
 greater confidence, and fomeumes form compounds 
 that are aimoft folid. 
 
 CHAP. XI. 
 
 Of the feveral Sorts of OILS. 
 
 L S are diftinguifhed by the fubftances from 
 which they arc drawn : and as Oils are ex- 
 traded from minerals, from vegetables, and from 
 animals, there are of courfe Mineral, Vegetable, 
 Animal Oils. 
 
 . I. Of M I N E R A L O I L S. 
 
 IN the bowels of the earth we find but one fort 
 of Oil, called Petroleum : its fmell is ftrong and not 
 difagreeable, and its colour fomenmes more fome-
 
 j 06 E L E M E N'T S of the 
 
 times Ids yellow. There are certain mineral fub* 
 fiances which yield by diftiilation a great deal of 
 Oil very like Petroleum. This fort of lubftance 
 is called a Bitumen, and is, indeed, nothing but aa 
 Oil rendered confident and folid by being combined 
 with an acid , as appears from hence, that by unit- 
 ing Petroleum with the acid of vitriol we can pro- 
 duce an artificial Bitumen very like the native. 
 
 . II. Of VEGETABLE OILS. 
 
 VEGETABLE fubftances yield a very great quan- 
 tity and variety of Oils : for there is not a plant, 
 or part of a plant, that does not contain one or more 
 forts thereof, generally peculiar to itfelf, and diffe- 
 rent from all others. 
 
 By expreflion only, that is, by bruifing and 
 fqueezing vegetable fubftances, particularly certain 
 fruits and feeds, a fort of Oil is obtained which has 
 fcarce any fmell or tafle. Oils of this fort are very 
 mild and un6tuous , and, becauie in this refpedt 
 they referable animil fat more than the reft do, 
 they are called Fat Oils. 
 
 Thefe Oils, being expofed to the air for fome 
 time, looner or later grow thick, acquire an acrid 
 tafte, and a ftrong difagreeable fmell. Some of 
 them congeal with the fmalleft degree of cold." 
 This fort of Oil is well adapted to diffolvc thofe 
 preparations of Lead called Litharge and Minium, 
 with which they form a thick tenacious fubftance, 
 that is ufed for the bafis of almoft all plaifters. 
 They allo diflblve Lead in its metalline form ; but 
 pot fo eafily as the forts of calx abovementioned ; 
 probably becauie its body is not fo much opened, 
 nor its parts fo divided. 
 
 By exprciTion alone we alfo procure from certain 
 vegetable fubftances another fort of Oil, which is 
 thin, limpid, volatile, of a pungent tafte,. and re* 
 tains the 1'mell of the vegetable that yielded it -, on 
 
 which
 
 THEORY of CHYMISTRY. 107 
 
 which account it is called an EJJential Oil. Of this 
 there are feveral forts, differing from one another 
 like the Fat Oils, according to (he fubjecls from 
 which they are obtained. 
 
 We muft obferve that it is very difficult, or rather 
 in moft cafes irnpoffible, to force from the greateft 
 part of vegetables, by expreffion only, all the efien- 
 tial Oil they contain. For this purpofe therefore re- 
 coLirfe muft be had to fire : a gentle heat, not ex- 
 ceeding that of boiling water, will extract all the 
 effential Oils of vegetables , and .this is the moft 
 ufual and moft convenient way of procuring them. 
 
 The fat Oils cannot be obtained by the fame me- 
 thod : thefe being much lefs volatile than the efien- 
 tial Oils require a much greater degree of heat to 
 raife them ; which neverthelefs they cannot bear 
 without being much fpoiled and entirely changed in 
 their nature, as (hall prefently be fhewn. All Oils, 
 therefore, which rife with the heat of boiling water, 
 and fuch alone, mould be called Eflential Oils. 
 , Eflential Oils, in a longer or fliorter time, ac- 
 cording to the nature of each, lofe the fragrant 
 fmell they had when newly diftilled, and acquire 
 another, which is ftrong, rancid, and much lefs 
 agreeable : they alfo lofe their tenuity, becoming 
 thick and vifcid ; and in this ftate they greatly re- 
 femble thofe fubftances abounding in Oil which 
 flow from certain trees, and which are called Bal- 
 fams or re/ins, according as they are lefs or more 
 confident. 
 
 Balfams and Refins are not foluble in water. But 
 there are other Oily compounds which likewife run 
 from trees ; and, though not unlike Refins, are how- 
 ever foluble in water. Thefe are called Gums ; and 
 their property of diflblving in water ariles from their 
 containing more water and more fait than Refins 
 have , or at leaft their faline parts are lefs clogged 
 and more difengaged. 
 
 Balfams
 
 ELEMENTS of the 
 
 Balfams and Refins didilled with the heat of boil- 
 in" water yield great quantities of a limpid, fubtle, 
 odoriferous, and, in one word, efiential Oil. In the 
 ftill there remains a fubdance thicker and more con- 
 fident than the Balfam or Refin was before diftilJa- 
 tion. The fame thing happens to efiential Oils 
 which by length of time have acquired a confidence 
 and are grown refinous. If they be redidilled, they 
 recover their former tenuity, leaving behind them 
 a remainder thicker and more refinous than they 
 themfelves were. This fecond diftillation is called 
 the Rectification of an Oil. 
 
 It mutt be obferved that an effential Oil, com- 
 bined with an acid ftrong enough todiflblve it, im- 
 mediately becomes as thick and refinous, in confe- 
 quence of this union, as if it had been long expofed 
 to the air : which proves the confidence an Oil 
 acquires by long keeping to be owing to this, that 
 its lighted and lefs acid parts being evaporated, 
 the proportion of its acid to the remainder is fo in- 
 creafed, that it produces therein the fame change, 
 as an additional acid mixed with the Oil would have 
 wrought before the evaporation. 
 
 This alfo fhews us that Balfams and Refins are 
 only efiemial Oils combined with a great propor- 
 tion of acid, and thereby thickned. 
 
 If vegetable fubdances, from which no more ef- 
 fential Oil can be drawn by the heat of boiling 
 water, be expoftd to a dronger heat, they yield an 
 additional quantity of Oil ; but it is thicker and 
 heavier than the effentiai Oil. Thefe Oils are black, 
 and have a very difagreeable burnt fmell, which 
 hath made them be called Fetid, or Empyreumatic 
 Oils. They are moreover very acrid. 
 
 It mud be obferved that, if a vegetable fubdance 
 be expofed to a degree of heat greater than that 
 of boiling water, before the fat or the efiemial Oil 
 is extracted from it, an empyreumatic Oil only will 
 
 then
 
 THEORY of CHYMISTRY. 109 
 
 then be obtained , becaufe both the fat and efiential 
 Oils, when expofed to the force of fire, are thereby 
 burnt, rendered acrid, acquire a fmell of the fire, 
 and, in a word, become truly empyreumatic. There 
 is ground to think that an empyreumatic Oil is no- 
 thing elfe but an eflential or fat Oil burnt and 
 fpoiled by the fire, and that no other Oil befides 
 thefe two exifts naturally in vegetables. 
 
 Empyreumatic Oils, dilblled and rectified feveral 
 times by a gentle heat, acquire by every diftillation 
 a greater degree of tenuity, lightnefs,and limpidity. 
 By this means alfo they lofe fomething of their dif- 
 agreeable odour-, fo that they gradually come nearer 
 and nearer to the nature of effential Oils : and if 
 the rectifications be often enough repeated, ten or 
 twelve times for inftance, they become perfectly 
 like thole Oils - 3 except that their fmell will never 
 be fo agreeable, nor like that of the fubftances from 
 which they were obtained. 
 
 Fat Oils may alfo be brought by the fame means 
 to referable eflential Oils : but neither eflential nor 
 empyreumatic Oils are capable of acquiring the 
 properties of fat Oils. 
 
 . III. Of ANIMAL OILS. 
 
 DISTILLATION procures us confiderable quanti- 
 ties of Oil from all the parts of animal bodies, and 
 efpecially from their fat. This Oil at firft is not 
 very fluid, and is extremely fetid : but by many 
 rectifications it gradually acquires a great degree of 
 clearnefs and tenuity, and at the fame time lofes 
 much of its difagreeable odour. Animal Oils, thus 
 rendered thin and fluid by a great number of recti- 
 fications, have the reputation of being an excellent 
 medicine, and a fpecific in the epilepfy. 
 
 CHAP.
 
 IIO E L E M E N T S of the ' 
 
 CHAP, XII. 
 Of FERMENTATION in general. 
 
 BY Fermentation is meant an inteftine motion, 
 which, arifing fpontaneoufly among the in- 
 lenfible parts of a body, produces a new difpofitkm 
 and a different combination of thofe parts. 
 
 To excite a Fermentation in a mixt body it is 
 neceflary firft, that there be in the compofition of 
 that mixt a certain proportion of watery* ialine, oily 4 
 and earthy parts : but this proportion is not yet 
 lufficiently afcertained, Secondly, it is requisite 
 that the body to be fermented be placed in a cer- 
 tain degree of temperate heat : for much cold ob- 
 ftru&s fermentation ; and too much heat decom- 
 pofes bodies. Laftly, the concurrence of the air is 
 alfo neceflary to fermentation. 
 
 All vegetable and animal fubftances are fufcep- 
 tible of Fermentation, becaufe all of them contain 
 in a due proportion the principles above fpecified. 
 However, many of them want the proper quantity 
 of water, and cannot ferment while they remain in 
 fuch a ftate of drynefs. But it is eafy to fupply 
 that defedt, and ib render them very apt to fer- 
 ment. 
 
 With refpeft to minerals properly fo called, (that 
 is, excluding fuch vegetable and animal fubftances 
 as may have lain long buried in the earth,) they are 
 not fubject to any Fermentation ; at lead that our 
 fenfes can perceive. 
 
 Thereare three fortsof Fermentation, diftinguimed 
 from one another by their feveral productions. The 
 firft produces wines and fpirituous liquors , for 
 
 which
 
 THEORY of OHYMISTRY. in 
 
 which reaibn it is called the Vinous or Spirituous 
 Fermentation : the refult of the fecond is an acid li- 
 quor ; and therefore it is called the Acetous Fermen- 
 tation : and the third generates an alkaline fait ; 
 which, however, differs from the alkaline falts hi- 
 therto treated of, in this refpedt chiefly that, infiead 
 of being fixed, it is extremely volatile : this laft 
 fort takes the name of the Putrid or Putrefaffive 
 Fermentation. We fhall now .confider thele three 
 forts of Fermentation and their effects a little more 
 particularly. 
 
 Thefe three forts of Fermentation may take place 
 fucreffively in the fame fubject ; which proves them 
 to be only three different degrees of fermentation, 
 all proceeding from one and the fame caufe, rather 
 than three diftinct fermentations. Thefe degrees of 
 fermentation always follow the order in which we 
 have here placed them. 
 
 CHAP. XIII. 
 Of the SPIRITUOUS FERMENTATION. 
 
 TH E juices of almoft all fruits, all faccharine 
 vegetable matters, all farinaceous feeds and 
 grains of every kind, being diluted with a fufficient 
 quantity of water, are proper fubjects of Spirituous 
 Fermentation. If fuch liquors be expofed, in vef- 
 fels Qightly (lopped, to a moderate degree of hear, 
 they begin in fome time to grow turbid ; there 
 arifes inlenfibly a fmall commotion among their 
 parts, attended with a hiffing noife ; this by litdc 
 and little increaies, till the grofler parts appear, like 
 little feeds or grains, moving to and fro, agitated 
 among themfclves, and thrown up to the furface. 
 At the fame time fome air bubbles rife, and the 
 
 liquor
 
 lit E L E M E N T s 
 
 liquor acquires a pungent, penetrating fmell, occa- 
 fioned by the very Tubule vapours which exhale 
 from it. 
 
 Thefe vapours have never yet been collected, in 
 order to examine their nature , and they are known 
 only by their noxious effects. They are fo actively 
 pernicious, that if a man comes rafhly into a clofe 
 place, where large quantities of liquors are fer- 
 menting, he fuddenly drops down and expires, us 
 if he were knocked on the head. 
 
 When thefe fevcral phenomena begin to go off, 
 h is proper to ftop the fermentation, if a very fpi- 
 rituous liquor be required : for if it be fuffered to 
 continue longer, the liquor will become acid, and 
 from thence proceed to its laftitage, that is, to pu- 
 trefaction. This is done by flopping the containing 
 vefiels very dole, and removing them into a cooler 
 place. Then the impurities precipitate, and fet- 
 tling at the bottom leave the liquor clear and 
 tranfparent : and now the palate discovers that the 
 fweet faccharine. talte it had before fermentation is 
 changed to an agreeable pungency which is not 
 acid. 
 
 Liquors thus fermented are in general called 
 Wines : for though in common life that word pro- 
 perly fignifies the fermented juice of grapes only, 
 and particular names are given to the fermented 
 juices of ether vegetable lubltances \ as that ob- 
 tained from Apples is called Cyder ; that made from 
 malt is called Beer : yet in Chymiitry it is of ufe to 
 have one general term denoting every liquor that 
 has undergone this fir II degree of fermentation. 
 
 By diilillation we draw from Wine an inflam- 
 mable liquor, of a yellowilh white colour, light, 
 and of a penetrating, pleafant fmclL This liquor 
 is the truly fpirituous part of the wine, and the 
 product of fermentation. That which comes off in 
 the firft dilliiLuion is commonly loaded with much 
 
 phlegm
 
 THEORY of CH YMISTR v. 113 
 
 phlegm and fome oily parts, from which it may be 
 afterwards freed. In this ftate it goes by the name 
 of Brandy , but when freed from thefe heteroge- 
 neous matters by repeated diftillations, it becomes 
 flill clearer, lighter, more fragrant, and much more 
 inflammable, and then is called Spirit of Wine ^ and 
 Rettifud Spirit of Wine, or an Ardent Spirit > if con- 
 fidcrably purified. The properties which diftin- 
 guifh an Ardent Spirit from all other fubilances are 
 its being inflammable-, its burning and confuming 
 entirely, without the lead appearance of fmoke or 
 fuliginofity , its containing no particles reducible to 
 a coal ; and its being perfectly mifcible with water. 
 Ardent Spirits are lighter and more volatile than 
 any of the principles of the mixts from which they 
 were produced* and confequently more fo than the 
 phlegm, the acid, and the oil of which they thenv 
 ielves confift. This arifes from a particular difpo- 
 fition of thefe principles, which are in a finguiar 
 manner attenuated by fermentation, and thereby 
 rendered more fufceptible of expanfion and rarefac- 
 tion. 
 
 Ardent fpirits are fuppofed to be the natural fol- 
 vents of oils and oily matters. But it is very re- 
 markable that they diflblve eflential oils only, 
 without touching the fat of animals, or the fat oils 
 obtained from vegetables by exprefiion ; yet when 
 thefe oils have once undergone the action of fire, 
 they become foluble in fpirit of wine, and even ac- 
 quire a new degree of folubility every time they 
 are diftilled. It is not fo with eflential oils, which 
 can never be rendered more foluble in ardent fpirits 
 than they are at firft ; and are fo far from acquiring 
 a new degree of folubility every time they are di- 
 ftilled, that on the contrary they even in fome mea- 
 fure lofe that property by repeated rectifications. 
 
 I have taken fome pains to find out the 
 caufes of thefe finguiar effects, and the refult of 
 
 VOL. I. I my 

 
 H4 ELEMENTS 0/" tbe 
 
 my enquiries is published among the Memoirs of 
 the Academy of Sciences for the year 1745.^ I 
 therein confider ardent fpirits as confiding ot an 
 oH, or at lealt a phlogifton, mixed with a portion 
 of water, in which it is rendered foluble by means 
 of an acid. This being la-id down, I fhew that the 
 inability of fpirit of wine to difTolve fome oils muft 
 be imputed to its aqueous part, in which oils are not 
 naturally foluble without the intervention of a ialt : 
 and that the power which this fpirit exerts in dif- 
 folving other oils with cafe, fuch as effential oils, 
 mutl in all probability be owing to this, that in 
 thefe oils it meets with the neceflary faline me- 
 dium, that is, with an acid, which numberlets ex- 
 periments {hew they actually contain. 
 
 On the other hand, I there prove that the acid in 
 efifcntial oils is fuperabundant, and in fome fort fo- 
 reign to their nature, or that it is but (lightly con- 
 nected with them, and in part deferts them every 
 time they are diftilled ; which renders them Ids fo- 
 luble after every new rectification : whereas, on the 
 contrary, the fat exprefled oils in their natural date 
 give not the lead fign of acidity ; but the action of 
 fire upon them difcovers an acid which was not per- 
 ceivable before. Hence I conjecture that thefe oils 
 contain no more acid than is juft neceflary to con- 
 ftitute them oils , that this acid is intimately blend- 
 ed with their other component parts ; that it is fo 
 fheathed and entangled by thefc parts as to be in- 
 capable of exerting any of its properties -, and that 
 on this account thefe oils in their natural Hate are 
 not foluble in fpirit of wine : but that the difpofition 
 of their parts being gradually changed by the fire, 
 and their acid, being by that means fet more and 
 more at liberty, at length recovers its properties > 
 and particularly that of rendering the oily parts fo- 
 luble in an aqueous menftruurn : and hence it fol- 
 lows that the fat oils become fo much the more fo- 
 7 lublc
 
 TnEbR Y of CHYMISTR Y. 115 
 
 luble in fpirit of wine the ofcner they are expofed 
 to the action of fire. 
 
 Spirit of wine doth not difTolve fixed alkalis ; or 
 at leaft it takes up but a very fmall quantity thereof; 
 and hence ardent fpirits may be freed from much of 
 their phlegm by means of thefe falts thoroughly 
 dried : for as they llrongly imbibe moifture, and 
 have even a greater affinity than ardent fpirits with 
 water, if a fixed alkali, well exficcated, be mixed 
 with fpirit of wine that is not perfectly dephlegmat- 
 ed, the alkali immediately attracts its fuperfluous 
 moiftures, and is thereby refolved into a liquor, 
 which on account of its gravity defcends to the 
 bottom of the vefiel. The fpirit of wine, which 
 fwims at top, is by this means as much dephlegmat- 
 ed, and as dry, as if it had been rectified by feveral 
 diftillations. As it takes up fome alkaline particles 
 in this operation, it is thereby qualified to difiblve 
 oily matters with the greater facility. When rec- 
 tified in this manner it is called Alcoholized Spirit of 
 Wine. 
 
 Yet fpirit of wine, even when rectified to an al- 
 cohol, is not capable of diflblving all oily matters. 
 Thofe named Gums will by no means enter into 
 any fort of union therewith , but it readily diflblves 
 moft of thofe which are known by the appellation 
 of Refins. When it has diflblved a certain pro- 
 portion of refinous particles it acquires a greater 
 confidence, and forms what is called a Spirit-Var- 
 nifl}, or a Drying Varnlfo, becaufe it foon dries ; 
 This Varnifh is fubject-to be damaged by water. 
 Many forts thereof are prepared, differing from each 
 other according to the different refins employed, or 
 the proportions in which they are ufed. Moft of 
 thefe Varnifhes are tranfparent and colourlefs. 
 
 Such bitumens or refins, as fpirit of wine will not 
 touch, are diffolved in oils, by means of fire, and 
 then form another kind of Varnilh, which water does 
 
 I a not
 
 1 1 6 ELEMENTS^? 
 
 not hurt. Thele Varniflies are ufually coloured 
 and require much longer time to dry than the Spirit- 
 Varnifhes: they arc called Oil-Varnijhes. 
 
 Spirit of wine hath a much greater affinity with 
 water than with oily matters : and therefore if a fo- 
 lution of any oil or refin in fpirit of wine be 
 mixed with water, the liquor immediately grows 
 turbid, and acquires a whitifh milky colour, owing 
 entirely to the oily parts being feparated from the 
 fp.irituous menftruum by the accefiion of water, and 
 too finely divided to appear in their natural form. 
 But if the liquor (land fome time quiet, leveral of 
 theie particles unite together, and gradually acquire 
 a bulk furficient to render them very perceptible to 
 the eye. 
 
 Acids have an affinity with fpirit of wine, and 
 may be combined with ic. By this union they lole 
 mod of their acidity, and on that account are faid 
 to be Dulcified. But as thefe combinations of acids, 
 efyecially of the vitriolic acid, with fpirit of wine, 
 iurnifh fome new produclions of very fmguhr pro- 
 perties, and as an examination thereof may throw 
 much light on the nature of ardent fpirits, it will 
 not be amiis to take notice of them in this place, 
 and confider each of them particularly. 
 
 One part of highly concentrated oil of vitriol be- 
 ing mixed with four parts of well dephlegmated 
 fpirit of wine, there ariles immediately a confider- 
 able ebullition, and cfterveicence, attended with 
 great heat, and abundance of vapours, which fmell 
 pleafantly, but are hurtful to the lungs. At the 
 lame time is heard a hitting like that produced by a 
 piece of red-hot iron plunged into water. Indeed 
 it is proper to mix the liquors very gradually ; for 
 otherwife the veflHs in which the operation is per- 
 formed will be in great danger of breaking. 
 
 It the two liquors thus mixed be dtftilled with a 
 
 very gentle hear> there rifes firft a fpirit of wine of 
 
 7 3
 
 THEORY C/~CHYMISTRY. 117 
 
 a mo ft penetrating and grateful odour : when aboiit 
 half thereof is come over, what follows has a quicker 
 and more fuiphureous fmell, and is alfo more loaded 
 with phlegm. When the liquor begins to boil a 
 little, there comes off a phlegm which fmelis very 
 flrong of fulphur, and grows gradually more acid. 
 On this phlegm floats a fmall quantity of a very 
 light and very limped oil. In the ftill there remains 
 a thick, blackifh fubftance, fomewhat like a refui 
 or bitumen. From this fubftance may be feparated 
 a good deal of a vitriolic but fuiphureous acid. 
 When that is extracted, there remains a black mafs 
 like a charred coal, which being put into a crucible 
 and expofed to a violent heat leaves a fmall portion 
 of earth, very fixed, and even vitrifiable. 
 
 By rectifying the ardent fpirit, which came over 
 in diftilling the abovementioned mixture, a very 
 fingular liquor is obtained, which differs effentially 
 both from oils and from ardent fpirits, though in 
 certain refpects it refembles them both. This li- 
 quor is known in Chymiftry by the name of jEther, 
 and its chief properties are as follow. 
 
 /Ether is lighter, more volatile, and more in- 
 flammable, than the mod highly rectified fpirit of 
 wine. It quickly flies off when expofed to the 
 air, and fuddcnly catches fire when any flame ap- 
 proaches it. It burns like fpirit of wine without 
 the lead fmoke, and confumes entirely without 
 leaving the fmallefl appearance of a coal or of afhes. 
 Jt diflblves oils and oily matters with great eafe and 
 rapidity. Thefe properties it has in common with 
 an ardent fpirit. But it refembles an oil in that it is 
 not mifcible with water-, and this makes it effen- 
 tially different from fpirit of wine, the nature of 
 which is to be mifcible with all aqueous licjuors. 
 
 Another very fingular property of /Ether is its 
 great affinity with gold, exceeding even that of aqu<i 
 \\ does not indeed diffolve gold when in a 
 J 3 mafs,
 
 I 1 8 E L E M E N T S of the 
 
 mafs, and in its metalline form : but if a fmall 
 quantity of TEther be added to a folution of gold in 
 aqua regis, and the whole flhaken togeiher, the gold 
 feparatcs from the aqua rcgis, joins the ./Ether, and 
 remains diflblved therein. 
 
 The reafon of all the phenomena above-mention- 
 fd, refulting from the mixture of fpirit of wine 
 with oil of vitriol, is founded on the great affinity 
 between this acid and water. For if the vitriolic 
 acid be weak, and as it were over-dofed with watery 
 parts, neither oil nor ^ther can be obtained by 
 means thereof: but when highly concentrated, it 
 attracts the aqueous parts very powerfully ; and 
 therefore being mixed with fpirit of wine lays hold 
 of mod of the water contained in it, and even robs 
 it of fome portion of that which is eflential to its 
 nature, and neceflary to conftitute it fpirit of wine : 
 whence it comes to pafs that a certain quantity of 
 the oily particles in its compofition being leparated 
 from the watery particles, and fo brought nearer 
 jo each other, they unite and afTume their natural 
 form ; and thus the oil that fwims at top of the ful- 
 phureous phlegm is produced. 
 
 The vitriolic acid moreover thickens and even 
 burns fome of this oil ; and hence comes the bitu- 
 minous refiduum left at the bottom of the ft ill, 
 which looks like the refult of a vitriolic acid com- 
 bined with common oil. Laftly, the vitriolic acid 
 becomes fulphureous, as it always doth when united 
 with oily matters, and alfo very aqueous, on account 
 of the ouantity of phlegm which it nttracls from 
 the fpirit of wine. 
 
 TEther may be confidered as a fpirit of wine ex- 
 ceedingly dephlegmated, even to fuch a degree that 
 its nature is thereby changed -, fo that the few a- 
 flueous particles left in it are not fufficient to diflblvc 
 the oily particles and keep them' afundcr ; which 
 therefore being now much nearer to one another 
 
 than
 
 THEORY of CHYMIST^Y. 119 
 
 than in common fpirit of wine, the liquor hath loll 
 its property of being mifcible with water. 
 
 Spirit of nitre well dephlegmated, and combined 
 with fpirit of wine, preterits likewise ibme very 
 Singular appearances, 
 
 Firft, in the very inftant of ks mixture with fpi- 
 rit of wine, it produces a greater and more violent 
 cffervefcence than the vitriolic acid occafions. 
 
 Secondly, this mixture, without the help of dif- 
 tillation, and only by flopping the bottle in which 
 the liquors are contained, affords a fort of /Ether, 
 produced probably by the vapours which afcend 
 from, and fwim at top of the mixture. This is a 
 very fingular liquor. Dr. Navier was the firft that 
 took notice of it, and gave a defcription thereof, 
 which may be feen in the Memoirs of the Academy 
 of Sciences. 
 
 Thirdly, fbme authors pretend that, by diftilling 
 the mixture under confideration, an oil is obtained 
 greatly refembling that which, as we obferved 
 above, .rifes from fpirit of wine combined with the 
 vitriolic acid : others again deny this. For my parr, 
 I believe tlie thing depends on the different concen- 
 tration of the fpirit of nitre, as well as on the qua- 
 lity of the fpirit of wine, which is fometimes more 
 fometimes lefs oily. 
 
 Fourthly, the two liquors we are fpealdng of, 
 being intimately mixed by diftillation, form a li- 
 quor flightly acid, ufed in medicine, and known by 
 the name of -Sweet or Dulcified Spirit of Nitre : a 
 very proper name, feeing the nitrous acid, by uni- 
 ting with the fpirit of wine, actually lofes almoffc 
 all its acidity and corrofive quality. 
 
 Fifthly and laftly, when the diftillation is finimed, 
 there remains in the bottom of tlif \effcl a thick, 
 blackifh (ubftance, nearly refemblung that which is 
 found after diftilling oil of vitriol and fpirit of 
 
 I 4 Spirit
 
 1 20 ELEMENTS^/* tJ-e 
 
 Spirit of Salt hath likewile been combined with 
 fpirit of wine; but it does not unite therewith fo 
 eafily or fo intimately as the two acids abovemen- 
 tioned. To mix them thoroughly, the fpirit of 
 fait muft be highly concentrated, and fmoaking, 
 and moreover the affiftance of the {till muft be 
 called in. Some authors pretend that from this 
 mixture alfo a fmall quantity of oil may be obtained ; 
 which probably happens when the liquors have the 
 qualities above fpecified. The marine acid likewilc, 
 by uniting with fpirit of wine, lofes moil of its 
 acidity ; on which account it is in like manner called 
 Sweet or Dulcified Spirit of Salt. A thick reiiduum 
 is alfo found here after diftillation. 
 
 CHAP. XV. 
 
 Of the ACETOUS FERMENTATION. 
 
 BESIDES an ardent fpirit, wine affords a 
 great deal of water, oil, earth, and a fort of 
 acid which fhall be confidered prefently. When 
 the fpirituous part is feparated from thefe other 
 matters, they undergo no further change. But if 
 all the conftuuent parts of wine remain combined 
 together, then, after fome time, fhorter or longer 
 as the degree of heat in which the wine ftands is 
 greater or lefs, the fermentation begins afrefh, or 
 rather arrives at its fecond ftage. The liquor once 
 more grows turbid, a new inteftine motion arifes, 
 and after fome days it is found changed into an 
 acid; which, however, is very different from thofe 
 hitherto treated of. The liquor then takes the name 
 of Vinegar. The acetous iermentation differs from 
 the fpirituous, not only in its effect, but alfo in le- 
 Tcral of its concomitant circumftances. Moderate 
 
 monon
 
 THEORY of CHYMISTRY. .131 
 
 motion is of fervice to this, whereas it obftrufts 
 the fpirituous , and it is attended with much more 
 warmth than the fpirituous. The vapours it pro- 
 duces are not noxious, like thofe of fermenting wine. 
 Laftly, Vinegar depofits no tartar, even when the 
 wine employed in this operation is quite new, and 
 hath not had time to difcharge its tartar : inftead 
 of tartar Vinegar depofites a vifcid matter which is 
 very apt to putrify. 
 
 It muft be obferved that wine is not the only 
 fubftance that is fufceptible of the acetous fermen- 
 tation : for feveral vegetable and even animal 
 matters, which are not fubjecl: to the fpirituous fer- 
 mentation, turn four before they putrify. But as 
 vinous liquors poffefs in a very eminent degree the 
 property of being fufceptible of the acetous fermen- 
 tation, and likewife of producing the ftrongeft acids 
 that can refult from fuch fermentation, their acid 
 Jhall be more particularly confidered in this place. 
 
 . I. Of V I N E G A R. 
 
 I F wine, which has gone through this fecomj 
 ftage of fermentation, be diftilled, inftead of an ar- 
 dent fpirit, only an acid liquor is obtained, which 
 is called Diftilled Vinegar. 
 
 This acid has the fame properties as the mineral 
 acids of which we have already treated ; that is, it 
 unites with alkaline forts, abforbent earths, and me T 
 gallic fubftances, and therewith forms neutral faline 
 combinations. 
 
 Its affinity with thefe fubftances obferves the fame- 
 order as that obferved by the mineral acids with re- 
 gard to the fame fubftances , but in general it is 
 weaker ; that is, any mineral acid is capable of ex- 
 peiiing the acid of Vinegar out of all matters with 
 which it is united. 
 
 Vinegar hath likewife a greater affinity than ful- 
 chur with alkalis ; whence it follo.ws that it is ca- 
 pable
 
 122 E L E M E N T S of the 
 
 pable of decompounding that combination of ful- 
 phur with an alkali called Liver of Sulphur, and of 
 precipitating the fulphur it contains. 
 
 The acid of Vinegar is always clogged with a 
 certain proportion of oily parts, which greatly weaken 
 it, and deprive it of much of its activity , and for 
 this reafon it is not near fo ftrong as the mineral 
 acids, which are not entangled with any oil. By 
 diftillation, indeed, it may be freed from this oil, 
 and at the fame time from the great quantity of 
 water which in a manner fuffocates it, and by that 
 means it may be brought much nearer to the nature 
 of the mineral acids: but this attempt hath not 
 yet been proiecuted with the afliduity it deferves. 
 Befides diftillation, there is another way of freeing 
 Vinegar from a good deal of its phlegm , and that 
 is, by expofing it to a hard froft, which readily con- 
 geals the watery part into ice, while the acid re- 
 tains its fluidity. 
 
 Vinegar, faturated with a fixed alkali, forms a 
 neutral oily fait, of a dark colour, which is femi- 
 volatile, melts with a very gentle heat, flames when 
 thrown upon burning coals, and difiblves in fpirit 
 of wine, of which, however, it requires fix parts to 
 complete the folution. This folution being evapo- 
 rated to drynefs leaves a matter in the form of leaves 
 lying on each other ; on which account it hath ob- 
 tained the name of Terra Foliata. The fame foli- 
 ated matter will be obtained, though the fait be not 
 previoufly difiblved in fpirit of wine -, but not fo 
 readily. This fait is alfo called Regenerated Tartar. 
 Under the head of Tartar we mail fee the reafon of 
 thefe different appellations. Regenerated Tartar is 
 alfo in fome degree capable of cryftallizing : for 
 this purpoie a folution thereof in water mud be 
 (lowly evaporated to the confidence of a fyrup, and 
 then fuffered to ftand quiet in a cool place ; by 
 which means it will fhoot into dufters of cryftals, 
 
 tying
 
 THEORY ^CHYMISTRY. 123 
 
 lying one upon another, not unlike the feathers on 
 a quill. 
 
 With Vinegar and feveral abforbent earths, fuch 
 as calcined pearls, coral, {hells of fifli, &c. are alfo 
 formed neutral faline compounds, each of which 
 takes the name of the particular earth employed in 
 its competition. 
 
 Vinegar perfectly diffblves Lead, and converts it 
 to a neutral metallic fait, which moots into cryftals, 
 and has a 1'weet faccharine tafte. This compound 
 is called Sugar of Lead ', or Sal Saturni. 
 
 If Lead be expofed to the bare vapour of Vine- 
 gar, it will be thereby corroded, calcined, and con- 
 verted into a white matter much ufed in painting, 
 and known by the name of Cerufe j or, when it is 
 finer than ordinary, White Lead. 
 
 Vinegar corrodes Copper likewife, and converts 
 it into a beautiful green ruft, which alfo is ufed in 
 painting, and diftinguiihed by the name ofFerdegris. 
 However, Vinegar is not commonly employed to 
 make Verdegris : for this pnrpofe they ufe wine, or 
 the rape of wine, from which fire extricates an acid 
 analogous to that of Vinegar. 
 
 In treating of the feveral fubftances which con- 
 ftitute wine we mentioned an acid matter, but did 
 not then enter into a particular examination thereof; 
 becaufe as that matter greatly refembles the acid of 
 Vinegar, we thought it more proper to defer the 
 confideration of its properties till we had treated of 
 the acetous fermentation, and its effects. 
 
 . II. Of TARTAR. 
 
 THIS fubftance is a faline compound, confifting 
 of earthy, oily, and efpecially acid parts. It is found 
 in the form of crufts, adhering to the inner fides of 
 veffels in which wines have flood for fome time, 
 particularly acid wines, fuch as ihofe of Germany. 
 
 Tartar
 
 124- E L E M E N T s of the ' 
 
 Tartar derives its origin from the fuperabundant 
 quantity of acid contained in the juice or' the 
 grape. This fuperfluous acid, being more than 
 is requifite to ccnihiute the ardent {pint, unites 
 with fome of the oil and earth contained in the fer- 
 mented liquor, and forms a kind of fait \ which 
 for fome time continues fufpended in that liquor, 
 but, when the wine Hands undifturbed in a cool 
 place, is depcfued, as hath been laid, on the fides 
 of the cafk. 
 
 Tartar in this ftate contains many earthy parts, 
 which are fupcrfluous, and foreign to its nature. 
 From thefe it may be freed by boiling it repeatedly 
 with a fort of earth found in the neighbourhood of 
 Montpelier, as may be Iccn in the Memoirs of the 
 Academy of Sciences. 
 
 When it is purified, there appears on the furfacc 
 of the liquor a fort of white cryitalline pellicle, 
 which is flammed off as it forms. This matter is 
 called Cream of Tartar. The lame liquor which 
 produces this Cream, and ip which the purified 
 Tartar is ditto! ved, being fet to cool yields a great 
 number of white femi-tranfparent cryftals, which 
 are called Cryftals of Tartar. The Cream and the 
 Cryftals ot Tartar are therefore no other than pu- 
 rified Tartar, and differ frcm each other in their 
 form only. 
 
 -Though the Cryftals of Tartar have every ap- 
 pearance of a neutral fait, yet they are far Ircm 
 being fuch , for they have all the properties of a 
 true acid, which fcarce differs from that of vine- 
 gar, except that it contains lefs water, and more 
 earth and oil -, to which it owes its folid form, as 
 well as its property of not being foluble in water 
 without much difficulty : for a very great quan- 
 tity of water is requif:te to keep the Cryftals of 
 'Tartar in folution i and it mud moreover be boil- 
 ing iiot j othcrwife as foon as it cools moil of the 
 
 Tartar
 
 THEORY of CHYMISTRY. 
 
 Tartar diflblved in it feparates from the liquor* 
 and falls to the bottom in the form of a white 
 powder. 
 
 Tartar is decompofed by calcination in the open 
 fire. All its oily parts are confumed or diffipated 
 in fmoke, together with mod of its acid. The 
 other part of its acid, uniting intimately with its 
 earth, forms a very ftrong and very pure fixed al- 
 kali, called Salt of Tartar. 
 
 It will be (hewn in its proper place that almoft 
 every vegetable^ matter, as well as Tartar, leaves a 
 fixed alkali in its afhes : yet Tartar has thefe pe- 
 culiar properties , firft, it ailumes an alkaline cha- 
 racter even when burnt or calcined in clofe vef- 
 fels, whereas other fubllances acquire it only by 
 being burnt in. the ; open air-, fccondly, the alkali 
 of Tartar is ftronger and more faline than almoft 
 any that is obtained from other matters. 
 
 This alkali, when thoroughly calcined, power- 
 fully attracts the nioifture of the air, and melts 
 into an unctuous alkaline liquor, improperly called 
 Oil of 'Tartar per deliqiilum. This is the alkali 
 generally ufecl in making the Terra Foliata, men- 
 tioned under the head of Vinegar ; for which rea- 
 fon this combination is called Terra Foliata Tartan \ 
 a name fuitable enough. But the .'fame cannot be 
 faid of the other name, Regenerated. Tartar^ which 
 is alfo given it. 'Tis true that on this occafion 
 an- oily acid is reftored to the earth of the Tartar, 
 analogous to that of which the fire had deprived 
 it : but the compound thence refulting is a neu- 
 tral fak which very readily diffolves in water ; 
 whereas Tartar is manifeftly acid, and nut foluble, 
 or at leaft hardly foluble, in water. 
 
 Cryllals of Tartar combined with alkali of Tar- 
 tar produce a great eftervefcence while they are 
 mixing, as all acids ufually do , and if the combina- 
 tion be brought exactly up to the point of iaturation, 
 
 a per-
 
 iz6 ELEMENTS of the 
 
 a perfectly neutral fait is formed, which fiioots into 
 cryftals, and eafily difTolves in water ; and this 
 hath procured it the name of Soluble Tartar. It is 
 alfo called the Vegetable Salf, as being obtained 
 from vegetables only ; and again, Tartarifed Tar- 
 tar, becaufe it confifts of the acid and the alkali 
 of Tartar combined together. 
 
 Cryftals of Tartar combined with alkalis procur- 
 ed from the afhes of maritime plants, fuch as Soda, 
 which alkalis refemble the bafis of lea-fa) t, form 
 likewife a neutral fait, which cryftallizes well, and 
 diffolves eafily in water. This fait is another fort 
 of foluble Tartar. It is called Saignette's Salt, from 
 the inventor's name. 
 
 Both the Vegetable Salt and Saignette's Salt are 
 gently purgative foaps, and much ufed in Medi- 
 cine. 
 
 Tartar likewife diflblves the abforbent earths, as 
 lime, chalk, &c. and with them forms neutral 
 falts which are foluble in water *. It even attacks 
 metallic bodies, and when combined with them 
 becomes foluble. A foiuble Tartar for medical 
 ufe is prepared with Cryftals of Tartar and Iron : 
 the metallic fait thereby produced hath the name 
 of Cbalybeated Soluble Tartar. This fait attracts 
 the moifture of the air, and is one of thofe which 
 do not cryftallize. 
 
 Cryftallized Tartar acts alfo upon feveral other 
 metallic fubftances : for inftance, it diflblves the 
 Regulus, Liver, and G-afs of Antimony, and 
 thence acquires an emetic quality : it is then called 
 Stibiated or Emetic Tartar: It likewife difiblves 
 Lead, and therewith forms a fait which, in the 
 figure of its cryftals, refembles Tartarifed Tartar. 
 
 It is very extraordinary that Tartar, which of 
 itfelf is not foluble in water, ihould be foluble 
 
 * See Mr. Duhamel's Eflays on this fubjeft in the Memoirs 
 of the Academy of Sciences. 
 
 therein
 
 THEORY of CHYMISTRY. 127 
 
 therein when become a neutral fait by uniting either 
 with alkalis or with abforbent earths, or even with 
 metals. With refpeft to alkalis, indeed, it may be 
 urged that, having themfelves a great affinity with 
 water, they communicate to Tartar fome of that 
 facility' with which they naturally unite therewith : 
 but the fame cannot be alledged concerning abfor- 
 bent earths, and metallic fubftances, which water 
 diflblves not at all, or at lead with great difficulty, 
 and in fmall quantity. This effect, therefore, muft 
 be attributed wholly to fome change in the difpofi- 
 tion of its parts which is to us unknown. 
 
 All the Soluble Tartars are eafily decompounded 
 by expofing them to a certain degree of heat. In 
 diftillation they yield the fame principles which are 
 obtained from Tartar -, and what remains fixed in 
 the fire, after they are thoroughly burnt, is a com- 
 pound of the alkali which Tartar naturally pro- 
 duces, and of the alkaline or metallic fubftance 
 with which it was converted into a neutral fait. 
 
 As Cryftal of Tartar is the weakeft of all acids, 
 on account of the oily and earthy matters with 
 which it is combined, Soluble Tartars are decom- 
 pounded by all the acids j by any of which cryital 
 of Tartar may be feparated from the fubftance that 
 ferves it for a bafis and renders it a neutral fait. 
 
 The other acids which are procured from ve- 
 getables, and even thofe which are obtainable from 
 fome animal fubftances, may all be referred to and 
 compared with either Vinegar or Tartar, according 
 to the quantities of oil or earth with which they 
 are combined. 
 
 After all, thefe acids have not yet been tho- 
 roughly examined. There is great reafon to think 
 that they are no other than the mineral acids, which 
 in pafiing through the bodies of vegetables, and 
 even of animals, undergo a confiderable change, 
 efpecially by contracting an union with oily matters. 
 
 For,
 
 128 E L E MEN T S of the 
 
 For, as we faid before in treating of Vinegar, by 
 freeing them from their oil they are brought very 
 near to the nature of mineral acids : and fo likewife 
 the mineral acids acquire many of the properties of 
 vegetable acids by being combined with oils. 
 
 CHAP. XV. 
 
 Of the PUTRID FERMENTATION, or 
 PUTREFACTION. 
 
 EVERY body which hath gone through the 
 two ftages of fermentation above defcribed, 
 that is,' the fpirituous and the acetous fermenta- 
 tion, being left to itfelf in a due degree of warmth, 
 which varies according to the fubjecl, advances to 
 the laft ftage of fermentation , that is, to putre- 
 facYion. 
 
 It is proper to obferve, before we go any further, 
 that the converfeof this propofition is not true-, that 
 is, it is not necefiary that a body mould fuccefllvely 
 pafs through the fpirituous and the acetous fermen- 
 tation, before it can arrive at the putrid ; but char, 
 as certain fubftances fall into the acetous without 
 having gone* through the fpirituous fermentation, 
 fo others begin to putrify without having undergone 
 either the Ipirituous or the acetous fermentation ; 
 of which laft kind are, for inftance, moft animal 
 fubftances. When therefore we reprefented thefe 
 three forts of fermentation as three different de- 
 grees or ftages of one and the fame fermentation, 
 we fuppofed it to be excited in a body fufceptiblc 
 of fermentation in its full extent. 
 
 However, there is ftill room to think that every 
 fubftance which is capable of fermenting always 
 
 pafics
 
 THEORY of CHYMISTRY. 129 
 
 palTes neceffarily through thefe three different ftages; 
 but that the fubftances mod difpofed thereto pals 
 with fuch rapidity through the firft, and even the 
 fecond, that they arrive at the third before our 
 lenfes can perceive the leaft figns of either of the 
 two former. This opinion is not deftitute of pro- 
 bability ; yet it is not fupported by proofs fuffi- 
 ciently ftrong and numerous to compel our affent. 
 
 When a body is in a putrefying (late it is eafy to 
 difcover, (as in the two. forts of fermentation al- 
 ready treated of) by the vapours which rife from it, 
 by the opacity which invades it, if a pellucid liquor, 
 and frequently even by a greater degree of heat 
 than is found in the two other forts of fermentation^ 
 that an inteftine motion is begun among its con- 
 ftituent parts, which lafts till the whole be entirely 
 putrefied. 
 
 The effect of this inteftine motion is in this, as in 
 the two other forts of fermentation, to break the 
 union, and change the difpofition, of the particles 
 conftituting the body in which it is excited, and 
 to produce a new combination. This is brought 
 about by a mechanifm to which we are ftrangers, 
 and concerning which nothing beyond conjectures 
 can be advanced : but thefe we neglect, refolving 
 to keep wholly to facts, as the only things in Na- 
 tural Philofophy that are pofitively certain. 
 
 If, then, we examine a fubftance that has un- 
 dergone putrefaction, we mall foon perceive that 
 it contains a principle which did not exift in it be- 
 fore. If this fubftance be diftilled, there rifes firft, 
 by means of a very gentle heat, a faline matter 
 which is exceedingly volatile, and affects the organ 
 of fmelling briikly and difagreeably. Nor is the 
 aid of diftillation necefiary to difcover the prefence 
 of this product of putrefaction : it readily ma- 
 nifefts itfelf in moft fubftances where it exitts, as 
 any one may foon be convinced by obferving the 
 
 VOL. I. K different
 
 130 ELEMENTS of the 
 
 different fmell of frefh and of putrefied urine; for 
 the latter not only affects the nofe, but even makes 
 the eyes fmart, and irritates them fo as to draw tears 
 from them in abundance. 
 
 This faline principle which is the product of pu- 
 trefaction, when feparated from the other principles 
 of the body which affords it, and collected by it- 
 felf, appears either in the form of a liquor, or in- 
 that of a concrete fait, according to the different 
 methods ufed to obtain it. In the former ftate it is 
 called a Volatile Urinous Spirit ; and in the latter a 
 Volatile Urinous Salt. The qualification of urinous 
 is given it, becaufe, as was faid^ a great deal 
 thereof is generated in putrefied urine, to which it 
 communicates its fmell. It goes alfo by the general 
 name of a Volatile Alkali, whether in a concrete or 
 in a liquid form. The enumeration of its proper- 
 ties will (hew why it is called an Alkali. 
 
 Volatile Alkalis, from whatever fubftance ob- 
 tained, are all alike, and have all the fame proper- 
 ties , differing only according to their degrees of 
 purity. The Volatile Alkali, as well as the Fixed, 
 eonfifts of a certain quantity of acid combined with 
 and entangled by a portion of the earth of the mixt 
 body Irom wnich it was obtained ; and on that ac- 
 count it has many properties like thofe of a Fixed 
 Alkali. But there is moreover in its compofition a 
 confiderable quantity of fat or oily matter, of 
 which there is none in a Fixed Alkali ; and on this 
 account again there is a great difference between 
 them. Thus the Volatility of the Alkali produced 
 by putretaction. which is the principal difference 
 between it and the other kind of Alkali whofc na- 
 ture it is to be Fixed, muft be attributed to the 
 portion of oil which it contains : for there is a 
 certain method of volatilizing Fixed Alkalis by 
 means of a fatty lubftance. 
 
 \ Volatilo
 
 THEORY cfCnYMisfRY. 131 
 
 Volatile Alkalis have a great affinity with acids* 
 Unite therewith .rapidly and with ebullition, and 
 form with thetn neutral falts, which fhoot into 
 eryftals, but differ from one another according to 
 the kind of acid employed in the combination. 
 
 The neutral falts which have a Volatile Alkali for 
 their bafis are in general called Ammoniacal Salts. 
 That whofe acid is the acid of fea-falt is called Sal 
 Ammoniac. As this was the firft known, it gave 
 name to all the reft. Great quantities of this fait 
 are made in Egypt, and thence brought to us. 
 They fublime it from the foot of cow's-dung, which 
 is the fuel of that country, and contains fea-faltj 
 together with a Volatile Alkali, or at leaft the ma- 
 terials proper for forming it 5 and confequently all 
 the ingredients that enter into the compofuion of 
 Sal Ammoniac. See the Memoirs of the Academy 
 of Sciences. 
 
 The neutral falts formed by combining the acids 
 of nitre and of vitriol with a Volatile Alkali are 
 called, arter their acids, Nitrous Sal Ammoniac, and 
 Vitriolic Sal Ammoniac : the latter, from the name 
 of its inventor, is alfo called Glauber's Secret Sal 
 Ammoniac. 
 
 A Volatile Alkali, then, has the fame property 
 as a Fixed Alkali with regard to acids : yet they 
 differ in this, that the affinity of the former with 
 acids is weaker than that of the latter : and hence it 
 follows that any Sal Ammoniac may be decom- 
 pounded by a Fixed Alkali, which will lay hold of 
 the acid, and difcharge the Volatile Alkali. 
 
 A Volatile Alkali will decompound any neutral 
 fait which has not a Fixed Alkali for its bafis ; that 
 is, all fuch as confift of an acid combined with an 
 abforbent earth or a metallic fubftance. By joining 
 with the acids in which they are dififolved, it difen- 
 gages the earths or metallic fubftances, takes their 
 K 2 place*
 
 ELEMENTS of tbe 
 
 place, and in conjunction with their acids-, forms 
 Ammoniac Salts. 
 
 Hence it might be concluded that, of all fub- 
 ftances, next to the Phlogifton and the Fixed Alka- 
 lis, Volatile Alkalis have the greateft affinity with 
 acids in general. Yet there is feme difficulty in 
 this matter : for abforbent earths, and feveral me- 
 tallic fubftances, are alfo capable of decompound- 
 ing Ammoniacal Salts, difcharging their Volatile 
 Alkali, and forming new compounds by uniting 
 with their acids. This might induce us to think 
 that thefe fubftances have nearly the fame affinity 
 with acids. 
 
 But it is proper to obferve, that a Volatile Alkali 
 decompounds fuch neutral falts as have for their 
 balis either an abforbent earth or a metallic fub- 
 ftance, without the aid of fire; whereas abforbent 
 earths or metallic fubftances will not decompound 
 an Ammoniacal Salt, unlefs they be afiifted by a 
 certain degree of heat. 
 
 Now as all thefe matters are extremely fixed, afi 
 leaft in comparifon with a Volatile Alkali, they 
 have the advantage of being able to refift the force 
 of fire, and fo of acting in conjunction therewith -, 
 and fire greatly promotes the natural action of fub- 
 ftances upon one another : whereas the Volatile Al- 
 kali in the Ammoniacal Salt, being unable to abide 
 the force of fire, is compelled to defert its acid ; 
 and that fo much the more quickly, as its affinity 
 therewith is confiderably weakened by the prefence 
 of an earthy or metallic fubftance, both of which 
 have a great affinity with acids. 
 
 Thefe confiderations oblige us to conclude, that 
 Volatile Alkalis have a fomewhat greater affinity, 
 than abforbent earths and metallic fubftances, with 
 acids. 
 
 Ammoniacal Salts projected upon nitre in fufion 
 
 make it detonate : and the Nitrous Sal Ammoniac 
 
 J. detonates
 
 THEORY <*/ CHYMISTRY. 133 
 
 <ktonates by itfelf, without the addition of any in- 
 flammable matter. This fingular effect evidently 
 demonftrates the exiftence of an oily matter in Vo- 
 latile Alkalis ; for it is certain that nitre will never 
 deflagrate without the concurrence, and even the 
 immediate contact, of fome combuftible matter. 
 
 This oily fubftance is often found combined with 
 Volatile Alkalis in fuch a large proportion as to dif- 
 guife it, in fome meafure, and render it exceeding 
 foul. The fait may be freed from its fuperfluous 
 oil by repeated fublimations , and particularly by 
 fubliming it from abforbent earths, which readily 
 drink up oils. This is called the Rectification of a 
 Volatile Alkali. The fait, which before was of a 
 yellowifli or dirty colour, by being thus rectified 
 becomes very white, and acquires an odour more 
 pungent and lefs fetid than it had at firft, that is, 
 when obtained by one fingle dijftillation from a pu- 
 trid fubftance. 
 
 It is proper to obferve that the rectification of 
 a Volatile Alkali muft not be carried too far, or re- 
 peated too often -, for by that means it may be en- 
 tirely decompofed at length \ and particularly if an 
 abforbent earth, arid efpecially chalk, be employed 
 for that purpofe, the fait may be converted into an 
 oil, an earth, and water. 
 
 Volatile Alkalis aft upon feveral metallic fub- 
 ftances, and particularly on copper , of which they 
 make a moft beautiful blue folution. On this pro- 
 perty depends a pretty fingular effect, which happens 
 fbmetimes when we attempt, by means of a Volatile 
 Alkali, to feparate copper from any acid with which 
 it is combined, Inftead of feeing the liquor grow 
 turbid, and the metal fall, both which generally 
 happen when any Alkali whatever is mixed with a 
 metallic folution, we are furprifed to obferve the fo- 
 lution of copper, upon adding a Volatile Alkali, 
 retain its limpidity, and let fall no precipitate; or at 
 
 K 3 Jeatt
 
 134. E L E M E N T S of the 
 
 lead if the liquor docs grow turbid, it remains fa 
 but for a moment, and inftantly recovers its tranf- 
 parency. 
 
 This is occafioned by adding fuch a quantity of 
 Volatile Alkali as is more than fufficient fully to fa- 
 turate the acid of the folution, and confiderable 
 enough to difiblve all the copper as faft as it is fc- 
 parated from the acid. On tins occafion the liquor 
 acquires a deeper blue than it had before ; which 
 arile? from the property which Volatile Alkalis have 
 of giving this metal, when combined with them, a 
 fuller blue than any other folvent can : hence we 
 have a touchftone to difcover copper wherever 
 it is; for let the quantity of this metal combined 
 with other metals be ever fo fmall, a Volatile Alkali 
 never fails to difcover it, by making it appear of a 
 blue colour. 
 
 Though a Volatile Alkali be conftantly the re- 
 fult of putrefaction, yet it muft not therefore be 
 imagined that none can be produced by any other 
 means ; on the contrary, moft of thofe fubftances 
 which contain the ingredients neceflary to form it, 
 yield no inconfiderable quantity thereof in diftilla- 
 tion. Tartar, for example, which by being burnt 
 in an open fire is converted, as was (hewn, into a. 
 Fixed Alkali, yields a Volatile Alkali when it is 
 decompofed in dole veffels -, that is, when it is 
 diftilled : becaufe in this latter cafe the oily part is 
 not difllpated or burnt, as it is by calcination in a 
 naked fire, but has time to unite with fome of the 
 earth and acid of the mixt, in fuch a manner as to 
 form a true Volatile Alkali. 
 
 To prove that on this occafion, as well as on all 
 Others, where unputrefied bodies yield a Volatile Al- 
 kali, this fait is the product of the fire, we need 
 only obferve, that in thefe diftillations it never riles 
 till after fome part of the phlegm, of the acid, and 
 even of the thick oil of the mixt, is come over ; 
 
 whicfy
 
 THEORY of CHYMISTRY. 135 
 
 which never is the cafe when it is formed before- 
 hand in the body which is the fubject of the opera- 
 tion, as it is in thofe which have undergone pu- 
 trefaction : for this fait, being much lighter and 
 more volatile than thofe other fubftances, rifes of 
 courfe before them in diftillation. 
 
 CHAP. XVI. 
 
 A General fiew of CHYMICAL 
 DECOMPOSITION. 
 
 THOUGH we have confidered all the fub- 
 ftances which enter into the compofition of 
 Vegetables, Animals, and Minerals, whether as pri- 
 mary or as fecondary principles, it will not be im- 
 proper to mew in what order we obtain thefe prin- 
 ciples from the feveral mixts ; and efpecially from 
 Vegetables and Animals, becaufe they are much 
 more complicated than Minerals. This is called 
 Analyfmg a compound. 
 
 The method moft commonly taken to decompofe 
 bodies is by applying to them fucceflive degrees of 
 heat, from the gentleft to the moft violent, in ap- 
 propriated velTels, fo contrived as to collect what 
 exhales from them. By this means the principles 
 are gradually feparated from each other ; the moft 
 volatile rife firft, and the reft follow in order, as 
 they come to be acted on by the proper degree of 
 heat : and this is called Diftillation. 
 
 But it being obferved that fire, applied to the de- 
 compofition of bodies, moft commonly alters their 
 fecondary principles very fenfibly, by combining 
 them in a different manner with each other, or 
 even partly decompofing them, and reducing them 
 K 4 to
 
 I 36 E L E M E N T S of the 
 
 to their primitive principles ; other means have 
 been ufed to feparate thofe principles without the 
 help of fire. 
 
 With this view the mixts to be decompofed are 
 forcibly compreffed, in order to fqueeze out of them 
 all fuch parts of their fubftance as they will by this 
 means part with ; or elfe thole mixts are for a long 
 time triturated, either along with water, which 
 carries off all their faline and faponaceous contents ; 
 or with folvents, fuch as ardent fpirits, capable of 
 taking up every thing in them that is of an oily or 
 refinous nature. 
 
 We mall here give a fuccinct account of the ef- 
 fects of thefe different methods, as applied to the 
 principal fubftances among Vegetables and Ani- 
 mals, and likewife to fome Minerals. 
 
 . I. Vbe ANALYSIS of VEGETABLE SUBSTANCES. 
 
 A vaft many vegetable fubftances, fuch as ker- 
 nels and feeds, yield by ftrong compreflion great 
 quantities of mild, fat, unctuous Oils, which are not 
 foluble in ardent fpirits : thefe are what we called 
 ExpreJJed Oils. They are alfo fometimes called Fat 
 Oils, on account of their unctuoufnefs, in which 
 they exceed all other forts of Oil. As thefe Oils 
 are obtained without the aid of fire, it is certain that 
 they exifted in the mixt juft as we fee them, and 
 that they are not in the leaft altered j which could 
 not have been the cafe had they been obtained by 
 diftillation ; for that never produces any Oils but 
 fuch as are acrid and foluble in fpirit of wine. 
 
 Some vegetable matters, fuch as the rind of ci- 
 trons, lemons, oranges, &c. alfo yield, only by 
 being fqueezed between the fingers, a great deal 
 of. Oil. This fpirts out in fine fmall jets, which 
 being received upon any polifhed furface, fuch as 
 a looking-glafs, run together and form a liquor 
 that is a real Oil.
 
 THEORY of CHYMISTRY. 137 
 
 But it muft be carefully noted that this fort of 
 Oil, though obtained by expreffion only, is never- 
 thelefs very different from the Oils mentioned before, 
 to which the title of JLxpreffed Oils peculiarly be- 
 longs : for this is far lighter and thinner ; moreover, 
 it retains the perfect odour of the fruit which yields 
 it, and is foluble in fpirit of wine; in a word, it is 
 a true eflential Oil, but abounds fo in the fruits 
 which produce it, and is lodged therein in fuch a 
 manner, occupying a vaft number of little cells pro- 
 vided in the peel for its reception, that a very flight 
 pfefiure difcharges it ; which is not the cafe with, 
 many other vegetables that contain an eflential Oil. 
 
 Succulent and green plants yield by comprefiion 
 a great deal of liquor or juice, which confifts of 
 moft of the phlegm, of the falts, and a fmall por- 
 tion of the oil and earth of the plant. Thefe juices, 
 being fet in a cool place for fome time, depofite fa- 
 line cryftals, which are a combination of the acid of 
 the plant with part of its oil and earth, wherein the 
 acid is always predominant. Thefe falts, as is evi- 
 dent from the defcription here given, bear a great 
 refemblance to the tartar of wine treated of above. 
 They are called EffentialSalts\ fo that Tartar might 
 likewife be called the Effential Salt of Wine. 
 
 Dried plants, and fuch as are of a ligneous, or 
 acid nature, require to be long triturated with wa- 
 ter, before they will yield their eflential falts. Tritu- 
 ration with water is an excellent way to get out of 
 them all their faline and faponaceous contents. 
 
 A vegetable matter that is very oily yields its ef- 
 fential fait with much difficulty, if at all ; becaufe 
 the exceflive quantity of oil entangles the fait fa 
 that it cannot extricate itfelf or fhoot into cryftals. 
 Mr. Gerike, in his Principles of Cbymijlry^ fays, that 
 if part of the oil of a plant be extracted by fpirit 
 of wine, its eflential fait may be afterwards ob- 
 fained with mpre eafe and in greater quantity. This 
 
 muft
 
 138 ELEMENTS of the 
 
 muft be a very good method for fuch plants as have 
 an exceffive proportion of eflential oil -, but will 
 not fucceed if the eflential fait be hindered from 
 cryftallizing by a redundancy of fat oil, becaule 
 fat oils are not foluble in fpirit of wine. 
 
 Eflential Salts are among thofe fubftances which 
 cannot be extracted from mixts by diftillation : for 
 the firft imprefiion of fire de-compotes them. 
 
 Though the acid which predominates in the Ef- 
 fential Salts of plants, be moft commonly analogous 
 to the vegetable acid, properly fo called, that is, to 
 the acid of vinegar and tartar, which is probably no 
 other than the vitriolic acid difguifed , yet it fome- 
 times differs therefrom, and fomewhat rejembles the 
 nitrous or the marine acid. This depends on the 
 places where the plants grow which produce thefe 
 ialts : if they be maritime plants, their acid is akin 
 to the acid of fea-falt ; if on the contrary they grow 
 upon walls, or in nitrous grounds, their acid is like 
 that of nitre. Sometimes one and the fame plant 
 contains faks analogous to all the three mineral 
 acids , which (hews that the vegetable acids are no 
 other than the mineral acids varioufly changed by 
 circulating through plants. 
 
 Liquors containing the Eflential Salts of plants 
 being evaporated by a gentle heat to the confiftence 
 of honey, or even further, are called Extratts. 
 Hence it is plain, that an Extract is nothing but 
 the Eflemial Salt of a plant, combined with fome 
 particles of its oil and earth, that remained fuf- 
 pended in the liquor, and are now incorporated by 
 evaporation. 
 
 Extracts of plants are alfo prepared by boiling 
 them long in water, and then evaporating fome 
 part of it. But thefe Extracts are of inferior vir- 
 tue ; becaufe the fire diflipates many of the oily and 
 faline parts. 
 
 EMULSIONS
 
 THEORY C/^CHYMISTRY, 139 
 
 EMULSIONS, 
 
 Subftances which abound much in Oil, being 
 bruifed and triturated with water for fome time, 
 Afford a liquor of an opaque dead-white colour, 
 like milk. This liquor confilts of fuch juices as 
 the water is capable of diflblving, together with a 
 portion of the oil, which being naturally indifiblu- 
 ole in water, is only divided and difperled in the 
 liquor, the limpidity whereof is by that means de- 
 ftroyed. This fort of oily liquor, in which the oil 
 is only divided, not diflblved, is called an Emulfion. 
 The oily particles in Emulfions fpontaneoufly fepa" 
 rate from the v/ater, when left at reft, and uniting 
 jnto greater mafles rife, on account of their light- 
 nefs, to the furface of the liquor, which by that 
 means recovers a degree of tranfparency. 
 
 If vegetables abounding in eflential oils and re r 
 fins be digefted in fpirit of wine, the menftruum 
 takes up thefe oily matters, as being capable of 
 diflblving them , and they may afterwards be eafily 
 Separated from it by the affufion of water. The 
 water, with which fpirit of wine has a greater af. 
 fiflity than with oily matters, feparates them by this 
 means from their folvent, agreeably to the common 
 Jaws of affinities. 
 
 Without the help of fire fcarce any thing, 
 befides the fubftances already mentioned, can be 
 obtained from a plant : but by the means of diftilr 
 Jation we are enabled to analyle them more com- 
 pletely. In profecuting this method of extracting 
 from a plant the feveral principles of which it con- 
 fifts, the following order is to be obferved. 
 
 A plant being cxpofed to a very gentle heat, in 
 diftilling veflel fet in the balneum marla, yields a 
 water which retains the perfect fmell thereof. Some 
 Chymifts, and particularly the illuftrious Boerhaave, 
 Jiave called this liquor the Spiritus ReRor. The 
 
 nature
 
 140 ELEMENTS 0/* the 
 
 nature of this odoriferous part of plants is not yet 
 thoroughly known , becauie it is fo very volatile 
 that it is difficult to fubjeft it to the experiments 
 necefiary for difcovering all its properties. 
 
 If inflead of diftilling the plant in the balneum 
 maritc, it be diftilled over a naked fire, with the 
 precaution of putting a certain quantity of water 
 into the diftilling vefiel aloog with it, to prevent 
 its fuffering a greater heat than that of boiJing 
 water, all the efiential oil contained in that plant 
 will rife together wkh that water, and with the 
 fame degree of heat. 
 
 On this occafion it muft be obferved that no ef- 
 fential oil can be obtained from a plant after the 
 Spiritus Rcftor hath been drawn off; which gives 
 ground to think that the volatility of thefe oils is 
 owing to that fpirit, 
 
 The heat of boiling water is alfo fufficient to fe- 
 parate from vegetable matters the tat oils which 
 they contain. That, however, is to be done by the 
 way of decoftion only, and not by diftillation : be- 
 caufe though thefe oils will fwim on water, yet they 
 will not rife in vapours without a greater degree of 
 heat. 
 
 When the eflential oil is come over, if the plant 
 be expofed to a naked fire, without the addition of 
 water, and the heat be increafed a little, a phlegm 
 will rife that gradually grov/s acid ; after which, if 
 the heat be increafed as occafion requires, there 
 will come over a thicker and heavier oil , from 
 fome a volatile alkali \ and laft of all, a very thick, 
 black, empyreumatic oil. 
 
 When nothing more rifes with the ftrongeft de- 
 gree of heat, there remains of the plant a mere 
 coal only, called the Caput Mcrtuum, or Terra 
 Damnafa. This coal when burnt falls into afhes, 
 which being lixiviated with water, gives a fixed 
 alkali. 
 
 It
 
 THEORY of CHYMIS TRY. 
 
 It is obfervable that in the diftillation of plants 
 which yield an acid and a volatile alkali, thefe twor 
 falts are often found quite diftinct and feparate in 
 the fame receiver -, which feems very extraordinary, 
 confidering that they are naturally difpofed to unite, 
 and have a great affinity with one another. The 
 reafon of this phenomenon is that they are both 
 combined with much oil, which embarrafies them 
 fo that they cannot unite to form a neutral fait, as 
 they would not fail to do were it not for that im- 
 pediment. 
 
 All vegetables, except fuch as yield a great deal 
 of volatile alkali, being burnt in an open fire, and 
 fo as to flame, leave in their afhes a large quantity 
 of an acrid, cauftic, fixed alkali. But if care be 
 taken to fmother them, fo as to prevent their flaming 
 while they burn, by covering them with fomething 
 that may continually beat down again what exhales, 
 the fait obtained from their a(hes will be much 
 lefs acrid and cauftic , the caufe whereof is, that 
 fome part of the acid and oil of the plant being 
 detained in the burning, and flopped from being 
 diffipated by the fire, combines with its alkali. 
 Thefe falts cryftallize, and being much milder than 
 the common fixed alkalis, may be ufed in medicine, 
 and taken internally. They are called ^acbemufs 
 Salts, becaufe invented by that Chymift. 
 
 Marine plants yield a fixed alkali analogous to 
 that of fea-falt. As for all other plants or vegetable 
 fubftances, the fixed alkalis obtained from them, 
 if rightly prepared and thoroughly calcined, are all 
 perfectly alike, and of the very fame nature. 
 
 The lad obfervation I have to make on the pro- 
 duction of fixed alkalis is, that if the plant you in- 
 tend to work upon be fteeped or boiled in water 
 before you burn it, a much fmaller quantity of falc 
 will be obtained from it , nay, it will yield none at 
 all, if repeated boilings have robbed it entirely of 
 
 thofe
 
 1 42 E L E M E N T S of the 
 
 thofe falinc particles which muft necefifarily concur 
 with its earth to form a fixed Alkali. 
 
 $. II. 'Tbe ANALYSIS of ANIMAL SUBSTANCES. 
 
 SUCCULENT animal fubftances, fuch as new-killed 
 flefh, yield by expreffion a juice or liquid, which 
 is no other than the phlegm, replete with all the 
 principles of the animal body, except the earth, of 
 which it contains but little. The hard or dry parts, 
 fuch as the horns, bones, &V. yield a fimilar juice, 
 by boiling them in water. Thefe juices become 
 thick, like a glue or jelly, when their watery parts 
 are evaporated ; and in this ftate they are true ex- 
 tracts of animal matters. Thefe juices afford no 
 cryftals of efiential fait, like thofe obtained from 
 vegetables, and mew no fign either of an acid or 
 an alkali. 
 
 Great part of the oil which is in the flefh of ani- 
 mals may be eafily feparated without the help of 
 Jhre-, for it lies in a manner by itlelf: it is com- 
 monly in a concrete form, and is called Fat. This 
 oil fomewhat refembles the fat oils of vegetables ; 
 for like them it is mild, unctuous, indiflbluble in 
 fpirit of wine, and is fubtilized and attenuated by 
 the action of fire. But there is not in animals, as 
 in vegetables, any light efiential oil, which rifes 
 with the heat of boiling water ; fo that properly 
 ipeaking, animals contain but one fort of oil. 
 
 Few animal fubftances yield a perceptible acid. 
 Ants and bees are almoll the only ones from which 
 any can be obtained: and indeed the quantity 
 they yield is very fmall, as the acid i tie If is ex- 
 tremely weak. 
 
 The reafon thereof is, that as animals do not 
 draw their nourimmcnt immediately from the earth, 
 but feed wholly either on vegetables or on the flefh 
 of other animals, the mineral acids, which have 
 already undergone a great change by the union con- 
 tracted
 
 THEORY of CHVMISTRY. 143 
 
 traded between them and the oily matters of the 
 vegetable kingdom, enter into a clofer union and 
 combination with thefe oily parts while they are 
 pafllng through the organs and drainers of animals j 
 whereby their properties are deftroyed, or at leaft 
 fo impaired that they are no longer fenfible. 
 
 Animal matters yield in diftillation, firft, 4 
 phlegm, and then, on increafing the fire, a pretty 
 clear oil, which gradually becomes thicker, blacker, 
 more fetid, and empyreumatic. It is accompanied 
 with a great deal of volatile alkali , and if the firs, 
 be raifed and kept up till nothing more comes over, 
 there will remain in the diftilling vefiel a coal like 
 that of vegetables j except that when it is reduced 
 to afhes, no fixed alkali, or at lead very little, caii 
 be obtained from them, as from the alhes of ve- 
 getables* This arifes from hence that, as we faid 
 before, the faline principle in animals being more 
 intimately united with the oil than it is in plants^ 
 and being confequently more attenuated and fubti- 
 lized, is too volatile to enter into the combination 
 of a fixed alkali , on the contrary k is more di* 
 pofed to join in forming a volatile alkali, which oni 
 this occafion does not rife till after the oil, and 
 therefore muft certainly be the production of the 
 fire. It muft be obferved, that all we have hitherto* 
 faid concerning the analyfis of bodies rnuft be un- 
 derftood of fuch matters only as have not under- 
 gone any fort of Fermentation. 
 
 The chyle and the milk of animals which feed 
 on plants ttill retain fome likenefs to vegetables * 
 becaufe the principles of which thefe liquors are 
 eompofed have not gone through all the changes 
 which they muft fuffer before they enter into the 
 Animal combination. 
 
 Urine and fweat are excrementitious aqueous li- 
 quors, loaded chiefly with the faline particles which 
 are of no fervice towards the nourishment of the 
 
 animal,.
 
 144 ELEMENTS of tie 
 
 animal, but pafs through its drainers without re- 
 ceiving any alteration \ fuch as the neutral falts 
 which have a fixed alkali for their bafis, and par- 
 ticularly the fea-falt, which happens to be in the 
 food of animals, whether it exift therein naturally, 
 as it does in fome plants, or whether the animals 
 cat it to pleafe their palates. 
 
 The faliva, the pancreatic juice, and efpecially 
 the bile, are faponaceous liquors, that is, they con- 
 Cft of faline and oily particles combined together : 
 fo that being themfelves diflblved in an aqueous 
 liquor, they are capable of difiblving likewife the 
 oily parts, and of rendering them mifcible with 
 water. 
 
 Laftly, the blood being the receptacle of all 
 thefe liquors partakes of the nature of each, more 
 or lefs in proportion to the quantity thereof which 
 it contains. 
 
 . III. fbe ANALYSIS of MINERAL SUBSTANCES. 
 
 MINERALS differ greatly from vegetables, and 
 from animals; they are not near fo complex as 
 thofe organized bodies, and their principles are 
 much more fimple j whence it follows that thefe 
 principles are much more clofely connected, and 
 that they cannot be feparated without the help of 
 fire ; which not having on their parts the fame ac- 
 tion and the fame power as on organized bodies, 
 hath not the fame ill effect on them ; I mean the 
 effect of changing their principles, or even deftroy- 
 ing them entirely. 
 
 I do not here fpeak of pure, verifiable, or re- 
 fractory earths ; of mere metals and femi-metals ; 
 of pure acids j or even of their fimpleft combina- 
 tions, fuch as fulphur, vitriol, allum, fea-falt : of 
 all thefe we have faid enough. 
 
 We arc now to treat of bodies that are more com- 
 plex,and therefore more fufccptible of decompoficion. 
 
 Thcfc
 
 THEORY O/CHYMISTRY. 14? 
 
 Thefe bodies are compound malTes, .or combina- 
 tions of thofe above-mentioned ; that is, metallic 
 fubftances as they are found in the bowels of the 
 earth, united with feveral forts of fahd, ftones, 
 earths, femi-metals,' fulphur, &c. When the me- 
 tallic matter is combined with other matter?, in 
 fuch a proportion to the reft that it may be fepa- 
 rated from them with advantage and profit, thefe 
 compounds are called Ores : when the cafe is other- 
 wife, they are called Pyrites, and Marcafites\ efpe- 
 cially if fulphur or arfenic be predominant therein, 
 which often happens. 
 
 In order to analyfe an ore, and get out of it the 
 metal it contains, the firft ftep is to free it from a 
 great deal of earth and ftones, which commonly 
 adhere to it very (lightly and fuperficially. This is 
 effected by pounding the ore, and then warning it 
 in water , to the bottom of which the metalline 
 parts prefently fink, as being the heavieft, while 
 the fmall particles of earth and ftone remain fuf- 
 pended fome time longer. 
 
 Thus the metallic part is left combined with fuch 
 matters only as are moft intimately complicated with 
 it. Thefe fubftances are moft commonly fulphur 
 and arfenic. Now as they are much more volatile 
 than other mineral matters, they may be diffipated 
 in vapours, or the fulphur may be confumed, by 
 expofing the ore which contains them to a proper 
 degree of heat. If the fulphur and arfenic be de- 
 fired by themfelves, the fumes thereof may be 
 catched and collected in proper vefiels and places. 
 This operation is called Roafting an Ore. 
 
 The metal thus depurated is now fit to be expofed 
 to a greater force of fire, capable of melting it. 
 
 On this occafion the femi-metals and the im- 
 perfect metals require the addition of fome matter 
 abounding in phlogifton, particularly charcoal- 
 duft; becaufe thefe metallic fubftances lofe thc-ir 
 
 VOL. I. L phlo-
 
 1 46 E L E M E N T S of tht 
 
 phlogifton by the action of the fire, or of the fluxes 
 joined with them, and therefore without this pre- 
 caution would never acquire either the fplendour or 
 the duclility of a metal. By this means the metallic 
 fubftance is more accurately feparated from the 
 earthy and ftony parts,of which fome portion always 
 remains combined therewith till it is brought to 
 fufion. For, as we obferved before, a metallic glafs 
 or calx only will contract an union with fuch mat- 
 ters , a metal poflcfled of its phlogifton and metal- 
 line form being utterly incapable thereof. 
 
 We took notice of the caufe of this feparation 
 above, where we (hewed that a metal pcflcfled of its 
 phlogifton and metalline form will not remain inti- 
 mately united with any calcined or vitrified matter, 
 not even with its own calx or glafs. 
 
 The metal therefore on this occafion gathers into 
 a mafs, and lies at the bottom of the velFel, as be- 
 ing molt ponderous , while the heterogeneous mat- 
 ters float upon it in the form of a glafs, or a femi- 
 vitrification. Thefe floating matters take the name 
 of Scorify and the metalline fubftance at bottom is 
 called the Regulus. 
 
 It frequently happens that the metalline regulus- 
 thus precipitated is itfelf a compound of leveral me- 
 tals mixed together, which are afterwards to be fe- 
 parated. We cannot at prefent enter into a detail of 
 the operations neceflary for that purpofe : they will 
 appear in our Treatile of Practical Cbymiftry : but 
 the principles on which they are founded may be 
 deduced from what we have laid above, concerning 
 the properties of the feveral metals and of acids. 
 
 It is proper to obferve, before we quit this fub- 
 jedl, that the rules here laid down for analyfing 
 ores are not abfolutely general : for example, it is 
 often advifable to roaft the ore before you warn it ; 
 for by that means fome ores are opened, attenuated, 
 and made very friable, which would coft much trou- 
 5 b!c
 
 THEORY 0/*CHYMisTRY. 147 
 
 "ble and expence, on account of their exceffive hard- 
 nefs, if you fhould attempt to pound them without 
 a previgus torrefaction. 
 
 It is alfo frequently necefiary to feparate the ore 
 from part only of its ftone ; fometimes to leave the 
 whole ; and fometimes to add more to it, before 
 you fmelt it. This depends on the quality of the 
 flone, which always helps to promote fufion when 
 it is in its own nature fufible and verifiable. It is 
 then called the Fluor of the ore : but of this we muft 
 fay as we did of the preceding article ; it is fufficient 
 for our prefent purpofe to lay down the fundamental 
 principles on which the reafon of every procefs is 
 built i the defcription of the operations themielves 
 being refervcd for our fecond Part. 
 
 We mail now give a fuccinct account of the prin- 
 cipal ores and mineral bodies, contenting ourfelvcs 
 with juft pointing out the particulars of which they 
 feverally confift. 
 
 Of the PYRITES. 
 'The yellow Pyrites. 
 
 THE yellow Pyrites is a mineral confiding of 
 fulphur, iron, an unmetallic earth, and frequently a 
 little copper : the fulphur, which is the only one 
 of thefe principles that is volatile, may be feparated 
 from the reft by fublimation : it ufually makes a 
 fourth, and fometimes a third, of the whole weight 
 of thefe Pyrites. The other principles are fepa- 
 rated from one another by fufion and reduction 
 with the phlogifton, which, by metallizing the fer- 
 ruginous and cupreous earths, parts them from the 
 unmetallic earth : for this earth vitrifies, and can- 
 not afterwards continue united with metallic mat- 
 ters pofTerTed of their metalline form, as hath been 
 laid before. 
 
 L z There
 
 14.8 E L E M E N T S of the 
 
 T */ 
 
 There is yet another way of decomposing the 
 yellow Pyrhes, which is to let it lye till it efflorefces, 
 or begins to fhoct into flowers ; which is nothing 
 but a fort of flow accenlion of the fulphur it con- 
 tains. The fulphur being by this means decom- 
 pofed, its acid unites with the ferruginous and cu- 
 preous parts of the Pyrites, and therewith forms 
 green and blue vitriols ; which may be extracted 
 by fteeping in water the Pyrites which has efflo- 
 refccd or been burnt, and then evaporating the 
 lixivium to a pellicle \ for by this means the vitriol 
 will (hoot into cryftals. 
 
 Sometimes the Pyrites contains alfo an earth of 
 the fame nature with that of alum : a Pyrites of 
 this fort, after flowering, yields alum as well as 
 vitriol. 
 
 3 be White Pyrites. 
 
 THE white Pyrites contains much arfenic, a fer- 
 ruginous earth, and an unmetallic earth. The arfe- 
 nic being a volatile principle may be feparated by 
 fublimation or diftillation from the reft, which are 
 fixed : and thefe again may be disjoined from each 
 other by fufion and reduction, as was faid in rela- 
 tion to the yellow Pyrites. 
 
 The Copper Pyrites. 
 
 THE Copper Pyrites contains fulphur, copper, 
 and an unmetallic earth. A great deal thereof 
 likewife holds arfenic, and its colour approaches 
 more or lefs to Orange, yellow, or white, accord- 
 ing to the quantity of arlenic in it. It may be de- 
 compofed by the fame means as the yellow and 
 white Pyrites. 
 
 OF
 
 THEORY ^CHYMISTRY. 149 
 
 OF ORES. 
 
 Of Gold Ores. 
 
 GOLD being conftantly found in its metalline 
 form, and never combined with fulphur and arfe- 
 nicjts matrices are not, properly fpeaking, ores; be- 
 caufe the metal contained in them is not mineralized. 
 The gold is only lodged between particles of ftone, 
 earth, or land, from which it is eafily feparated by 
 lotion, and by amalgamation with quickfilver. 
 The gold thus found is feldom pure, but is fre- 
 quently alloyed with more or lefs filvcr, from which 
 it is to be feparated by quartation. 
 
 It is alfo very common to find gold in moil ores 
 of other metals or femi- metals, and even in the Py- 
 rites ; but the quantity contained therein is gene- 
 rally fo fmall, that it would not pay the coft of ex- 
 tracting it. Hov,ever, if any ihould incline to at- 
 tempt it, merely out of curiofity, it would be ne- 
 ceflary to begin with treating thefe ores in the 
 manner proper for feparating their metalline part j 
 then to cupel the metalline regulus fo obtained ; 
 and laftly to refine it by quartation. 
 
 Of Silver Ores. 
 
 IT is no rare thing to find filver, as well as gold, 
 in its metalline form, only lodged in fundry earths 
 and ftony matters, from which it may be feparated 
 in the fame manner as gold. But the greateft quan- 
 tities of this metal are ufually dug out of the bowels 
 of the earth in a truly mineral ftate ; that is, com- 
 bined with different fubftances, and particularly 
 with fulphur and arfenic. 
 
 Several filver ores are diftinguifhed by peculiar 
 characterifticks, and are accordingly denoted by- 
 particular names. That which is called the T 7 /- 
 
 L 2 trews 
 
 f
 
 150 ELEMENTS <9 
 
 treous Silver Ore y is fcarce any thing elfe but a com- 
 bination of filver and fr.lphur. Another is known 
 by the name of the Horny Silver Ore, becaufe when 
 in thin plates it is femi-tranfparent : in this ore the 
 filver is mineralized by fulphur and a little arlenic. 
 The Red Silver Ore is of the colour which its name 
 imports, fometimes more, fometimes lefs vivid ; 
 and is chiefly compofed of filver, arfcnic, and ful- 
 phur : it alfo contains a little iron. 
 
 Thefe three ores are very rich in filver : the firft 
 contains nearly three fourths of its weight, and the 
 others about two thirds of theirs. 
 
 There is a fourth, called the While Silver Ore, 
 which though it be heavier, is not fo rich in filver, 
 becaufe it contains much copper. Many other 
 minerals contain filver, yet are not, properly fpeak- 
 ing, fiiver ores , becaufe a much greater quantity 
 of other metals than of filver is found in them. 
 
 When a filver ore is to be decompofed, in order 
 to have the filver pure, or when filver is to be ex- 
 traded out of any ore that contains it, the firft thing 
 to be done is to roaft the ore, in order to clear it of 
 the volatile minerals : and as filver cannot be had 
 pure without the operation of the cupel, which re- 
 quires more or lefs lead to be joined wich it, it is 
 ufual to mix with the terrified filver ore a quantity 
 of lead, proportioned to that of the heterogeneous 
 matters combined with the filver, and to melt the 
 whole together. Part of the added lead vitrifies 
 during the fufion, and at the fame time converts 
 fome of the heterogeneous matters alfo into glafs, 
 with which it forms a fcoria that rifes to the furface 
 of the matter. The other part of the lead, with 
 which the filver is mixed, falls to the bottom in the 
 form of a regulus, which mull be cupelled in order 
 to have the filver pure.
 
 THEORY of CH YMISTR Y. 
 
 Of Copper Ores. 
 
 COPPER is much feldomer found in a metalline 
 form, than gold or filver: it is commonly in a mi- 
 neral ftate : it is mineralized by fulphur and arfe- 
 nic : almoft all its ores contain alfo more or lefs 
 iron ; fometimes a little filver or even gold, to- 
 gether with un metallic earths and ftones, as all 
 ores do. 
 
 Moft copper ores are of a beautiful green or blue, 
 or elfe in (hades blended of thefe two colours. The 
 minerals called mount am green^ and mountain blue, are 
 true copper ores -, not in the form of hard ftones, 
 like other ores, but crumbly and friable like earth. 
 
 Neverthelefs there are feveral copper ores of dif- 
 ferent colours, as am-coloured, whitifh, and (haded 
 with yellow or orange ; which colours arife from 
 the different proportions of arfenic, fulphur, and 
 iron, which thefe ores contain. 
 
 In order to decompofe a copper ore, and to ex- 
 traft the copper it contains, it is firft of all to be 
 freed from as many of its earthy, ilony, fulphureous 
 and arfenical parts, as is poffible, by roafting and 
 wafhing ; then what remains is to be mixed with a 
 'flux compounded of a fixed alkali and fome inflam- 
 mable matter; a little fea-falt is to be put over all, 
 and the whole melted by a ftrong fire. The falts 
 facilitate the fufion and fcorification of the unme- 
 tallic matters, and therewith form a flag, which be- 
 ing the lighted rifes to the furface. The metalline 
 matters are collected below in the form of a (hining 
 regulus of copper , which, however, is not ufually 
 fine copper, but requires to be purified in the man- 
 ner to be (hewn in our fecond part. 
 
 In order to feparate the copper from the unmetal- 
 lic matters, it is abfolutely neceflfary to melt its ore 
 along with inflammable fubftances abounding in 
 
 L 4 phlogifton.
 
 152 E L E M E K T S of the 
 
 phlogifton. For, as this metal is not pofiefied of 
 its metalline form while it is in a mineral (late, as 
 it is deftitute of the true quantity of phlogiiton, 
 and, though it were not, would lofe it by the action 
 of the fire, it would come to pafs that if its ore 
 were melted without the addition ot any inflam- 
 mable matter, the cupreous earth or calx would be 
 fcorified and confounded with the un metallic mat- 
 ters , and as all metallic matters, except gold and 
 filver, are fubjcct to this inconvenience as well as 
 copper, the addition of an inflammable fubftancc, 
 in fluxing all ores that contain them, is a general 
 rule that ought conftantly to be obferved. 
 
 Of Iron Ores. 
 
 IRON is feldom found pure and malleable in the 
 earth-, yet it is much feldomer found in the mineral 
 ftate, properly fo called, than any of the other me- 
 tals : for molt iron ores arc fcarce any thing more 
 than a ferruginous earth mixed in different pro- 
 portions with unmetallic earths and (tones. Some 
 of them, however, contain alib volatile minerals, 
 fuch as fulphur and arfenic ; and therefore it is ne- 
 cefiary to roaft the iron ores, like all others, before 
 you attempt to extract the metal out'of them. That 
 being done, they are to be fmelted with a flux con- 
 fifting of fufible and inflammable matters, as the 
 general rule directs. 
 
 Iron is the commonefl of all metals-, nay, it is 
 fo univerfally diffufed through the earth, that it is 
 difficult to find any done, earth, or fand, that docs 
 not contain fome of it -, and therefore none of thefe 
 are ufually confidered and treated as iron ores, except 
 fuch as contain a great deal of that metal, and melt 
 eafily. The hematites, emery, yellow pyrites, ca- 
 lamine, all contain a pretty ccnfiderable quantity of 
 iron ; but nobody attempts to extract it from 
 them, bccaufe they are very hard to melt. 
 
 5 Ferru-
 
 THEORY of CH YMISTR Y. 
 
 Ferruginous earth being naturally of an orange 
 colour, a ftone or earth may bejuged to contain 
 iron, if either naturally, or after roafting, it appears 
 to have one (Lade of yellow or red. 
 
 The fingular property which iron has of beino- 
 attracted by the magnet, and of being the only 
 body, exclufive of all others, that is fo, likewife af- 
 fords us an eafy method of difcovering the prefence 
 of this metal among ether matters, where it often 
 cxifts in fuch a irnall quantity that it could notother- 
 wife be found out. For this purpofe the body in 
 which iron is fufpected to lurk, muft be pulverifed 
 and torrefied with fome inflammable matter; and 
 then the powder thus roafted being touched with 
 a magnet, or an animated bar, if it contains any 
 particles of iron they will infallibly adhere to the 
 magnet or bar. 
 
 Of 'Tin Ores. 
 
 TIN is never found in the earth pure and malle- 
 able, but always in a mineral (late, and always mi- 
 neralized by arfenic. Tin ores are not fulphureous ; 
 whence it comes that though tin be the lighteft of 
 all metals, its ores are n^yerthelefs heavier than 
 thole of other metals, as arfenic greatly exceeds 
 fulphur in gravity. Some tin ores contain alfo a 
 little iron. The ores of tin are to be warned, 
 roafted, and fmelted with a reducing flux, accord- 
 ing to the general rules. 
 
 ' t* WJ 
 
 Of Lead Ores. 
 
 LEAD, like tin, is never found but in a mineral 
 ftate. It is moft commonly mineralized by ful- 
 phur ; yet there are fome lead ores which alfo con- 
 tain arfenic. 
 
 Lead ores, as well as others, muft be roafted and 
 fmelted with a reducing flux : however, as it is dif- 
 ficult
 
 154 ELEMENTS 0/* the 
 
 jficult to free them from all their fulphur by torre- 
 faclion only, the reducing flux employed in their 
 fufion may be made up with a quantity of iron 
 filings, which being incapable of any union with 
 lead, and having a much greater affinity than that 
 metal with fulphur, will on this occafion be of great 
 fervice by interpofmg between them. 
 
 Of Quick /river Ores. 
 
 RUNNING Mercury is fometimes found in certain 
 earths, or grey, friable ftones ; but mod commonly 
 in a mineral ftate. It is always mineralized by ful- 
 phur, and by fulphur alone : fo that cinabar is the 
 only ore of quick-filver that we know of: and a 
 very rich one it is, feeing it contains fix or feven 
 times as much mercury as fulphur. 
 
 Roafting can be of no ufe towards decompofing 
 the ore of mercury, and feparating its fulphur ; be- 
 caufe mercury being itfelf very volatile would be 
 carried off by the fire together with the fulphur. In 
 order therefore to part the two fubftances of which 
 cinabar confifts, recourfe muft neceffarily be had 
 to fome third body, which will unite with one of 
 them, and by that means feparate it from the other. 
 Now all the metals, except Gold, having a greater 
 affinity than mercury with fulphur, fuc-li a body 
 is eafily found : any metal but Gold may be em- 
 ployed with fuccefs in this decompofition j but as 
 iron hath a greater affinity with fulphur than any 
 of the reft, and is moreover the only one that can- 
 not unite with mercury, it muft on account of 
 thefe two qualities be preferred to all the reft. 
 
 Fixed alkalis are alfo well qualified to abforb 
 the fulphur of cinabar. Cinabar muft be decom- 
 pofed in dole vefiels, and by the way of diftilla- 
 j otherwife the mercury, as foon as it feparates 
 
 from
 
 THEORY of CHYMISTR Y. icr 
 
 from the fulphur, will be diffipated in vapours and 
 entirely loft. 
 
 I N this operation it is needlefs to add either flux 
 or phlogifton -, becaufe the cinabar is decompofed 
 without melting, and the mercury, though in a mi- 
 neral ftate, contains, like gold and filver, all 
 the phlogifton requifite to fecure its metalline 
 properties. 
 
 Of the Ores of Regulus of Antimony. 
 
 REGULUS of Antimony is always found in a 
 mineral ftate : it is mineralized by fulphur ; but 
 fometimes, though rarely, it is alib combined with 
 a little arfenic. 
 
 W hen the ore of regulus of antimony is to be de- 
 compofed, the fir ft thing to be done is to expofe it 
 to a degree of heat too weak to melt its earthy and 
 ftony parts, but ftrong enough to fufe its reguline, 
 together with its fulphureous parts, which by this 
 means are feparated Irom the earth, and united into 
 one mafs, known by the name of Antimony. 
 
 It is plain that this firft operation, which is founded 
 on the great fufibility of antimony, produces, with 
 regard to the ore of regulus of antimony, the fame 
 effect that warning hath on other ores : ib that after 
 this firft fufion nothing more is requifite to the ob- 
 taining of a pure regulus of antimony, but to fepa- 
 rate it from its fulphur by roafting, and to melt it 
 with fome matter abounding in phlogifton, in the 
 fame manner as other metallic matters are treated. 
 The term Calcination is generally ufed to exprefs 
 this torrefaction of antimony, by means whereof the 
 metallic earth of the regulus of antimony is fepa- 
 rated from its fulphur. 
 
 As regulus of antimony hath, like mercury, 
 much lefs affinity with fulphur than the other me- 
 tals have, it follows that antimony may be decom- 
 pofed by the fame means as cinabar j but the regu-* 
 
 lus
 
 156 E L E M E N T S of the 
 
 lus fo obtained is adulterated with a portion of the 
 additament made ufe of, which combines there- 
 with. 
 
 There is ftill another procefs employed for ob- 
 taining the regulus of antimony : it confifts, as 
 was mentioned in its place, in detonating the mi- 
 neral with a mixture of nitre and tartar, applied in 
 fuch a proportion that, after the detonation has 
 confumcd the fulphur, there may remain fo much 
 inflammable matter as will be fufficient to furnifh 
 the metalline earth of the antimony with the phlo- 
 gifton neceflary to preferve its metallic properties. 
 But by this method Icfs regulus is produced, than 
 by calcining, or torrefying, and reducing as ufual. 
 
 Of the Ores of Bifmuth. 
 
 THE ore of Bifmuth confifts of the femi-metal 
 mineralized by arfrnic,'and of an unmetallic earth. 
 It is very eafy to decompoie this ore, and to extraft 
 the bifmuth it contains : for this purpofc it need 
 only be expofed to a moderate heat, whereby the 
 arienic will be difTipated in vapours, and the bif- 
 muth melted, which will then feparate from the 
 unmetallic earth. This earth, at lead, in feveral 
 ores of bifmuth, pofiefles the property of tinging 
 all verifiable matters, with which it is melted, of a 
 beautiful blue colour. 
 
 To decompofe the ore of bifmuth no flux or in- 
 flammable matter is ufed , becaufe this femi-metal 
 is poflciTed, even in its mineral (late, of all the 
 phlogifton requifite to maintain its metalline pro- 
 perties -, and its great fufibility makes it unneceflary 
 to melt the unmetallic earth contained in its ore. 
 
 Of tbe Ores of Zinc. 
 
 ZINC is not generally obtained from a particular 
 ore of its own , but fublimes during the fufion of 
 a mineral, or rather a confufcd mafs of minerals, 
 
 that
 
 THEORY O/'CHYMISTRY. 157 
 
 that contains this femi-metal together with iron, 
 copper, lead, fulphur, arfenic, and, like all other 
 ores, an unmetallic earth. 
 
 Neverthelefs there is a ftibftance which may be 
 confidered as the proper ore of zinc, becaufe it 
 contains a pretty large quantity of that femi-metal, 
 a little iron, and an unmetallic earth. It is called 
 Colamuei or Lapis Calamlnaris : but hitherto the 
 art of procuring zinc directly from this mineral 
 hath no where been practifed. Calamine is com- 
 monly employed only to convert copper into brafs, 
 or a yellow metal, by cementing it therewith. In- 
 deed till lately no eafy or practicable method of ob- 
 taining pure zinc from calamine was publickly 
 known ; for that femi-metal being volatile and very 
 inflammable, its ore cannot be fufed like others. 
 Mr. Margraaf was the firft who, by mixing pow- 
 dered charcoal with calamine in dole veflels, ob- 
 tained a perfect zinc from it, by the means of dif- 
 tillation or fublimation, as mall be fhewn in our 
 Practical Chymiftry. 
 
 Of Arfenical Minerals. 
 
 ARSENIC, as well as fulphur, is naturally com- 
 bined with almoft all ores, or minerals containing 
 metallic fubftances. As it is very volatile, while 
 the matters with which it is united are fixed, at 
 lead in companion therewith, it is eafily feparated 
 by fublimation. 
 
 The minerals that contain mod arfenic are the 
 white pyrites, orpiment, and cob-alt. We have al- 
 ready confidered the white pyrites : as toOrpiment, 
 it confifts of fulphur and arfenic. Both thefe fub- 
 ftances being very volatile, it is difficult to feparate 
 them by fublimation : yet, with proper manage- 
 ment, and a due regulation of the fire, this fepara- 
 tion may be effected ; becaufe fulphur fublim.es a lit- 
 tle more eafily than arfenic. But it is more conve- 
 nient
 
 153 E L E M E N T S of the 
 
 riient, as well as more expeditious, to make ufe of 
 fome additament that hath a greater affinity withone 
 of thofe Jubilances than with the other. Fixed al- 
 kalis and mercury, both of which have more affi- 
 nity with fulphur than with arfenic, may be very 
 properly employed on this occafion. 
 
 Cobalt is a mineral compofcd of arfenic, an 
 unmetallic earth, and frequently bifmuth : and as 
 none of theie are very volatile, except the arfenic, 
 this may be eafily feparated from the reft by fubli- 
 mation. The unmetallic earth which remains has, 
 like that of the ore of bifmuth, the property of 
 giving a blue colour to any verifiable matters 
 melted with it , whence it is conjectured that cobalt 
 and the ore of bifmuth have a great refemblance, 
 or are often blended with each other. Neverthelefs 
 Mr. Brant, an ingenious Swedim Chymift, infills 
 that they are very different : he pretends that the 
 metallic fubftance contained in the true cobalt is 
 a femi-metal of a peculiar nature, which hath been 
 erroneoully confounded with bifmuth : and indeed 
 he proves by a great number of curious experi- 
 ments, related in the Memoirs of the Academy of 
 Upfnl, that theie two metallic fubftances have pro- 
 perties that are efll'ntially different : to that which 
 is obtained from cobalt, he gives the name of Re>- 
 gn!us of Cobalt. 
 
 Befides the minerals already recited, there is found 
 in the bowels of the earth another fpecies of com- 
 pound body, of which we have already taken notice ; 
 but which is fuppofed, with fome degree of proba- 
 bility, to belong as much to the vegetable as to the 
 mineral kingdom : 1 mean the Bitumens , which the 
 beft obfervations oblige us to confider as vegetable 
 oils, that by lying long in the earth have contracted 
 an union with the mineral acids, and by that means 
 acquired the thicknefs, confidence, and other pro- 
 perties obfervable in them. 
 
 By
 
 THEO'RY of CHYJ* T ISTRY. 159 
 
 By diflillation they yield an oil, and an acid not 
 unlike a mineral acid. Mr. Bourdelin has even de- 
 monftrated, by a very artful and ingenious procels, 
 that amber contains a manifefh acid of fea-falt. See 
 the Memoirs of the Royal Academy of Sciences. 
 
 CHAP. XVII. 
 
 Explanation of the "Table of Affinities. 
 
 IT hath been fhewn in the courfe of this work 
 that the caufes of almoft all the phenomena, 
 which Chymiftry exhibits, are deducible from the 
 mutual affinities of different fubftances, efpecially 
 the fimpk'ft. We have already explained, (Chap. 
 II.) what is meant by affinities, and have laid down 
 the principal laws to which the relations of dif- 
 ferent bodies are fubject. The late Mr. Geoffroy, 
 one of the beft Chymifts'we have had, being con- 
 vinced of the advantages which all who cultivate 
 Chymiftry would receive from having conftantly be- 
 fore their eyes a ftate cf the beft afcertained relations 
 between the chief agents in Chymiftry, was the firft 
 who undertook to reduce them into order, and 
 unite them all in one point of view, by means of a 
 table. We are of opinion, with that great man, that 
 this Table will be of confiderable ule to luch as are 
 beginning to ftudy Chymiftry, in helping them to 
 form a juft idea of the relations which different 
 fubftances have with one another \ and that the prac- 
 tical Chymift will thereby be enabled to account for 
 what pafles in feveral of his operations, otherwife 
 difficult to be underftood, as well as tojudge whr.t 
 may be expected to refult from mixtures of different 
 compounds. Thele rcafons have induced us to 
 
 infert
 
 1 6o ELEMENTS c/* the 
 
 infert it at the end of this Elementary Treatife, and 
 to give a fhort explanation of it here ; efpecially 
 as it will ferve, at the fame time, for a recapitula- 
 tion of the whole work, in which the feveral axioms 
 of this Table are difperfed. 
 
 You have it here juft as it was drawn up by Mr. 
 Geoffroy, without any addition or alteration. I 
 own, however, that it might be improved both 
 ways: for fince the death of that great Chymift 
 many experiments have been made, Tome of which 
 have difcovered new affinities, and others have 
 raifcrd exceptions to fome of thofe laid down by 
 him. But feveral reafons diffuade me from publ'fh- 
 ing a new Table of Affinities, containing all the 
 emendations and innovations that might be made 
 in the old one. 
 
 The firft is, that many of the affinities lately dif- 
 covered are not yet fufficiently verified, but, on the 
 contrary, fubject to be contefted : in fhort, they 
 are perhaps liable to mere confiderable objections 
 a -.id exceptions than the other. 
 
 The fecond is, that as Mr. Geoffrey's Table 
 contains all the fundamental affinities, it is more 
 i'uitable to an Elementary Treatife than a much 
 fuller one would be ; feeing this would neccflarily 
 fuppofe the knowledge of many things not treated 
 of by us, and of which it was not proper to fay 
 any thing in fuch a book as this. 
 
 However, as it is effential to our purpofe that we 
 lead none into error, we mail take care in explain- 
 ing the affinities delivered by Mr. Geoffroy, to 
 mention the principal objections and exceptions to 
 which they are liable : we fhall moreover add a 
 very few new ones, confining ourfclves to fuch 
 only as are elementary and well afcertained. 
 
 The upper line of Mr. Geoffroy's Table, compre- 
 hends feveral fubftances ufed in Chymiilry. Under 
 each of thofe fubftances are ranged in diftinct co- 
 lumns
 
 THEORY of CHYMISTR Y. 16 1 
 
 lumris feveral matters compared with them, in the 
 order of their relation to that firft fubftance ; fo as 
 that which is the neareft to it is that which hath the 
 greateft affinity with it, or that which none of the 
 fubftances {landing below it can feparate therefrom ; 
 but which, on the contrary, feparates them all when 
 they are combined with it, and expels them in or- 
 der to join itfelf therewith. The fame is to be un- 
 derftood of that which occupies the fecond place of 
 affinity -, that is, it has the fame property with re- 
 gard to all below it, yielding only to that which is 
 above it : and fo of all the reft. 
 
 At the top of the firft column ftands the charac- 
 ter which denotes an Acid in general. Immediately 
 under this ftands the mark of a Fixed Alkali, being 
 placed there as the fubftance which has the greateft 
 affinity with an Acid. After the Fixed Alkali ap- 
 pears the Volatile Alkali, whofe affinity with Acids 
 yields only to the Fixed Alkali. Next come the Ab- 
 forbent Earths ; and laft of all Metallic Subftances. 
 Hence it follows that when a Fixed Alkali is united 
 with an Acid it cannot be feparated therefrom by 
 any other fubftance , that a Volatile Alkali united 
 with art Acid cannot be feparated from it by any 
 thing but a Fixed Alkali , that an Abforbent Earth 
 combined with an Acid may be feparated from ic 
 either by a Fixed or by a Volatile Alkali ; and 
 laftly, that any Metallic Subftance combined with 
 an Acid may be feparated from it by a Fixed Al- 
 kali, a Volatile Alkali, or an Abforbent Earth. 
 
 There are many important remarks to be made 
 on this firft column. Firft* it is making the rule 
 too general to fay that any Acid whatever has a 
 greater affinity with a Fixed Alkali, than with any 
 other fubftance. And indeed Mr. Geoffroy himfelf 
 hath made an exception with refpeft to the Vitriolic 
 Acid : for in the fourth column, at the head of 
 which ftands that Acid, we find the fign of the 
 
 VOL.. I. M Phlogifton.
 
 162 E L E M.E N T s of the 
 
 Phlogifton placed above that of the Fixed Alkali, 
 as having a greater affinity than the Fixed Alkali 
 with the Vitriolic Acid. This is founded on the 
 famous experiment, wherein Vitriolated Tartar and 
 Glauber's Salt are decompounded by means of the 
 Phlogifton, which feparates the Fixed Alkalis of 
 thefe Neutral Salts, and uniting with the Vitriolic 
 Acid contained in them forms therewith a Sul- 
 phur. 
 
 Secondly, Nitre deflagrates, and is decompofed, 
 by the contact of any inflammable matter whatever 
 that is actually ignited , and the operation which 
 produces Phoiphorus is no other than a decompofi- 
 tion of fea-falt, whole Acid quits its Alkaline bafis 
 to join with the Phlogifton : now thefe facts furnifh 
 very ftrong reafons for believing that both thefe 
 Acids, as well as the Vitriolic, have a ftronger affi- 
 nity with the Phlogifton than with a Fixed Alkali. 
 Laftly, as feveral experiments (hew the Vegetable 
 Acids to be only the Mineral Acids difgnifed and 
 mortified, there are fufficient grounds for fufpecting 
 that Acids in general have a greater affinity with the 
 Phlogifton than with Fixed Alkalis : fo that inftead 
 of making an exception with regard to the Vitriolic 
 Acid, it would perhaps be better to lay down this 
 greater affinity as common to all Acids whatever, 
 and to place the Phlogifton in the firft column, im- 
 mediately under the character which denotes an 
 Acid in general. This theory, however, ftands irt 
 need of confirmation from other experiments *. 
 
 * Mr. Margraaf, an able German Chymift, has made feveral 
 experiments, which induce him to think that the Acid of Phof- 
 phorus is of a particular kind, and different from that of fea- 
 ialt. May it not be the Marine Acid, but altered by the union, 
 it has contracted with the phlogifton ? Or may it not be, 
 with refpeft to Phofphorus, what the volatile fulphureous fpirit 
 is. with refpeft to Sulphur? See the Memoirs of the Royal 
 Academy of Sciences of Berlin, 
 
 Thirdly,
 
 THEORY of CHYMISTRY. 163 
 
 Thirdly, in this fame column the character of a 
 Volatile Alkali is fet above that of an Abforbent 
 Earth, as having a greater affinity with Acids ; 
 and yet thefe Abforbent Earths decompofe the 
 Ammoniacal falts, drive away the Volatile Alkali 
 from the Acids, and affume its place. This is one 
 of the firft objections made againft Mr. Geoffrey's 
 Table. His anfwer thereto is printed in the Me- 
 moirs of the Academy of Sciences for 1718, where 
 his Table alfo is to be found. We have already 
 declared our opinion about this matter in treating 
 of a Volatile Alkali. 
 
 Fourthly, in 1744, Mr. Geoffroy, brother to 
 jthe author of the Table, who hath done no lefs 
 honour to Chymiftry than that eminent phyfician, 
 gave in a Memoir containing an exception to the 
 Jaft affinity in the firft column ; namely, that whicfc 
 places Abforbent Earths above Metallic Subftances. 
 He therein fhews that Alum may be converted into 
 Copperas by boiling it in iron vqffels , that on this 
 pccafiori the iron precipitates the Earth of the 
 Alum, feparates it from its Acid, and aflfumes its 
 place ; fp that of courfe it muft have a greater affi- 
 nity, than the Abforbent Earth of Alum, with the 
 Vitriolic Acid. 
 
 At the head of the fecond column (lands the cha- 
 ra&er of the Marine Acid, which fignifies that the 
 affinities of this Acid are the fubject of the column. 
 Immediately below it is placed the mark of Tin, 
 As this is a metalline fubftance, and as the firft co- 
 lumn places metalline fubftances in the loweft degree 
 of affinity with all Acids, it is plain we muft fup- 
 pofe Fixed Alkalis, Volatile Alkalis, and Abforbent 
 Earths, to be placed here in order after the Marine 
 Acid, and before Tin. Tin, then, is of all Metal- 
 line fubftances that which has the greateft affinity 
 with the Marine Acid; and then follow Regains 
 of Antimony, Copper, Silver, Mercury. Gold 
 M 2 comes
 
 164 ELEMENTS^/" the 
 
 comes laft of all -, and there are no lefs than two 
 vacant places above it. By this means it is in fome 
 fort excluded from the rank of fubftances that have 
 an affinity with the Marine Acid. The reaibn 
 thereof is that this Acid alone is not capable of 
 difiblving Gold and combining therewith, necefia- 
 rily requiring for that purpole the aid of the Ni- 
 trous Acid, or at leall of the Phlogifton. 
 
 The third column exhibits the affinities of the 
 Nitrous Acid, the character whereof (lands at its 
 head. Immediately below it is the fign of Iron, as 
 the metal which has the greateft affinity with this 
 Acid ; and then follow other metals, each accord- 
 ing to the degree of its relation; to wit, Copper, 
 Lead, Mercury, and Silver. In this column, as 
 in the preceding one, we muft fuppofe the fub- 
 itances, which in the firft column fland above 
 Metallic Subftances, to be placed in their proper 
 order before Iron. 
 
 The fourth column is intended to reprefent the 
 Affinities of the Vitriolic Acid. Here Mr. Geoffroy 
 has placed the Phlogitton as the fubftance which 
 has the greateft affinity with this Acid, for the 
 reafon given in our explanation of the firft column. 
 Below it he has ranked Fixed Alkalis, Volatile 
 Alkalis, and Abforbent Earths, to fhew that this is 
 an exception to the firtfc column. As to Metalline 
 fubftances, he has fet down but three, being 
 thofe with which the Vitriolic Acid has the molt 
 perceptible affinity : thele metals, placed in the 
 order of their affinities, are Iron, Copper, and 
 Silver. 
 
 The fifth column (hews the affinities of Abforbent 
 Earths. As thcfe Earths have no lenfible affinity 
 but with Acids, this column contains only the cha- 
 racters of the Acids ranked according to the degree 
 of their ftrength, or affinity with the Earths -, to 
 wit, the Vitriolic, the Nitrous, and the Marine 
 
 Acids*
 
 THEORY of CHYMISTRY. 165 
 
 Acids. Underneath this lad might be placed the/ 
 Acid of Vinegar, or the Vegetable Acid. 
 
 The fixth column exprefTes the Affinities of Fixed 
 Alkalis with Acids, which are the lame with thofe 
 of Abforbent Earths. Moreover, we find Sulphur 
 placed here below all the Acids ; becaufe Liver of 
 Sulphur, which is a combination of Sulphur with 
 a Fixed Alkali, is actually decompounded by any 
 Acid : for any Acid precipitates the Sulphur and 
 unites with the Alkali. 
 
 Immediately over the Sulphur, or in the fame 
 fquare with it, might be fet a mark denoting the 
 Volatile Sulphureous Spirit; becaufe, like Sulphur, 
 it has lefs affinity than any other Acid with Fixed 
 Alkalis. Oils might alfo be ranked with Sulphur, 
 becaufe they unite with Fixed Alkalis, and there- 
 with form Soaps, which are decompounded by. any 
 Acid whatever. 
 
 The feventh column points out the affinities of 
 Volatile Alkalis, which are likewife the fame as 
 thofe of Abforbent Earths ; and the Vegetable Acid 
 might be placed here alfo under the Marine Acid. 
 
 The eighth column fpecifies the affinities of Me- 
 tallic fubllances with Acids. The affinities of the 
 Acids, which with refpect to Fixed Alkalis, Vola- 
 tile Alkalis, and Abforbent Earths, fucceeded each 
 other uniformly, do not appear in the fame order 
 here. The Marine Acid, inftead of being placed 
 below the Vitriolic and Nitrous Acids, Hands, on 
 the contrary, at their head ; becaufe, in fact, this 
 Acid feparates Metalline fubftances from all the 
 other Acids with which they happen to be united, 
 and, forcing thefe Acids to quit pofleffion, intrudes 
 into their place. Neverthelefs, this is not a general 
 rule , for feveral Metalline fubftances muft be ex- 
 cepted, particularly Iron and Copper. 
 
 The ninth column declares the affinities of Sul- 
 phur Fixed Alkalis, Iron, Copper, Lead, Silver,Re- 
 
 M 3 S ulus
 
 ELEMENTS of the 
 
 gulus of Antimony, Mercury, and Gold, (land be- 
 low it in the order of their affinities. With regard 
 to Gold it muft be obferved, that it will not unite 
 with pure Sulphur : it fuffers itfelf to be difiblved 
 only by the Liver of Sulphur, which is known to 
 be a competition of Sulphur and Fixed Alkali. 
 
 At the head of the tenth column appears Mer- 
 cury, and beneath it feveral Metalline fubftances, in 
 the order of their affinities with it. Thole Metalline 
 fubftances are Gold, Silver, Lead, Copper, Zinc, 
 and Regulus of Antimony. 
 
 It is proper 10 remark on this column that Re- 
 gulus of Antimony, which ftands the loweft, unites 
 but very imperfectly with Mercury ; and that 
 after a feeming union of thefe two Metallic fub- 
 ftances hath been obtained, by a tedious triture 
 with the addition of water, they do not continue 
 long united, but fpontaneoufly leparate from each 
 other in a fhort time. Iron and Tin are here ex- 
 cluded ; the former with great reafon, becaufe hi- 
 therto it hath not been clearly proved, by any 
 known experiment, that ever Mercury was united 
 yrith Iron : but the fame objection cannot be made 
 to Tin, which amalgamates very well with Mer- 
 cury, and might therefore be placed in this column 
 nearly between Lead and Copper. I ufe the word 
 nearly, becaufe the different degrees of affinity be- 
 tween Metalline fubftances and Mercury are not fo 
 exactly determined, as the other relations before 
 confidered ; feeing they generally unite with it, 
 without excluding one another. We can therefore 
 fcarce judge of the degree of affinity that belongs 
 to each, but by the greater or lefs readinefs of each 
 to amalgamate therewith. 
 
 The eleventh column (hews that Lead has a 
 greater affinity with Silver than with Copper, 
 
 The twelfth, that Copper has a greater affinity 
 ^yith Mercury than with Calamine, 
 
 The
 
 THEORY of CHYMISTRY. 167 
 
 The thirteenth, that Silver has a greater affinity 
 with Lead than with Copper. 
 
 The fourteenth contains the affinities of Iron, 
 Regulus of Antimony (lands immediately under- 
 neath it, as being the Metallic fubftance which has 
 the greateft affinity with it. Silver, Copper, and 
 Lead- are placed together in the next fquare below, 
 becaufe the degrees of affinity which thofe Metals 
 have with Iron are not exactly determined. 
 
 The fame is to be faid of the fifteenth column : 
 Regulus of Antimony (lands at its head j Iron is 
 immediately below it ; and below the Iron the fame 
 three Metals occupy one fquare as before. 
 
 Laftly, the fixteenth column indicates that Water 
 has a greater affinity with Spirit of Wine than with 
 Salts. By this general exprefiion mud not be under- 
 flood any Saline fubftance whatever , but only the 
 Neutral Salts, which Spirit of Wine frees from the 
 water that kept them in folution. Fixed Alkalis, 
 on the contrary, as well as the Mineral Acids, have 
 a greater affinity than Spirit of Wine with Water : 
 fo that thefe Saline fubftances, being well dephleg- 
 mated, and mixed with Spirit of Wine, imbibe the 
 water it contains and rectify it. 
 
 To thefe might be added another fhort column, 
 having Spirit of Wine at its head : immediately be- 
 low it mould be the character of Water, and below 
 that the mark of Oil. This column would (hew 
 that Spirit of Wine has a greater affinity with Wa- 
 ter than with Oils \ becaufe any Oily matter what- 
 ever, that is difiblved in Spirit of Wine, may be ac- 
 tually feparated from it by the affufion of Water. 
 This rule admits of no exception but in one cafe; 
 which is when the oily fubftance partakes of the 
 nature of foap, by having contracted an union with 
 fome faline matter, But as this mud be imputed 
 wholly to that adventitious faline matter being fuper- 
 to the oily fubftance, it is no juft foundation 
 M 4 for
 
 1 68 ELEMENTS of 
 
 for an exception, and the affinity in queftion is ne- 
 verthelefs general. 
 
 We have now delivered every thing material that 
 we had to fay concerning Mr. Geoffrey's Table of 
 Affinities. It is, as we obferved brfore, of ex- 
 ceeding great fervice, as it collects into one view the 
 principal truths laid down in this Treatife. Indeed 
 the moft advantageous way of ufing it is, not to 
 delay confulting it till you have read the book 
 through, but to turn to it while you are reading, as 
 oft as any affinity between bodies is treated of 
 Which it will imprint more ftronglyon your mind, 
 by reprefenting it in a manner before your eyes. 
 
 CHAP. XVIII. 
 
 'The THEORY o/* C o N s T RUCTING 
 the VE s s E L s mojl commonly ufed 
 in CH y M i s T R Y. 
 
 CHYMISTS cannot perform the operations 
 of their art without the help of a confiderable 
 number of vefiels, inftruments, and furnaces, 
 adapted to contain the bodies on which they intend 
 to work, and to apply to them the feveral degrees 
 of heat required by different procefies. It is there- 
 fore proper, before we advance to the operations 
 themfelves, to confider particularly and minutely 
 'what relates to the inftruments with which they are 
 to be performed. 
 
 Veflels intended forChymical Operations mould, 
 to be perfect, be able to bear, without breaking, 
 the fudden application of great heat and great cold ; 
 be impenetrable to every thing, and unalterable by 
 any folvent; unvitrifiable, and capable of enduring 
 
 the
 
 THEORY O/*CHYMISTRY. 169 
 
 the moft violent fire without melting : bat hitherto 
 no vefiels have been found with all thefe qualities 
 united. 
 
 They are made of fundry materials , namely, of 
 metal, of glafs, and of earth. Metalline veilels, 
 efpecially thofe made of Iron or Copper, are apt tQ 
 be corroded by almoft every faline, oily, or even 
 aqueous fubftance. For this reafon, in order to 
 render the ufe of them a little more extenfive, they 
 are tinned on the infide. But, notwithftandino- 
 
 O 
 
 this precaution, they are on many occafions not to 
 be trufted , and mould never be employed in any 
 nice operations which require great accuracy : 
 they are, moreover, incapable of refitting the force 
 of fire. 
 
 Earthen vefiels are of feveral forts. Some, that 
 are made of a refractory earth, are capable of being 
 fuddenly expofed to a ftrong fire without break- 
 ing, and even of fuftaining a great degree of heat 
 for a confiderable time : but they generally furrer 
 the vapours of the matters which they contain, as 
 well as vitrified metals, to pafs through them, eipe- 
 cially the glafs of lead, which eafily penetrates them 
 and runs through their pores as through a fieve. 
 There are others made of an earth that, when well 
 baked, looks as if it were half vitrified : thefe be- 
 ing much lefs porous, are capable of retaining the 
 vapours of the matters which they contain, and 
 even glafs of lead in fufion ; which is one of the 
 fevered trials a vefiel can be put to : but then they 
 are more brittle than the other fort. 
 
 Good glafs veffels mould conftantly be employed 
 in preference to all others, whenever they can pof- 
 fibly be ufed : and that not only becaufe they are 
 no way injured by the moft active folvents,norfuffer 
 any part of what they contain to pafs through, 
 frut alfo becaufe their tranfparency allows the Chy- 
 niift to obferve what pafles within them: which is 
 
 always.
 
 J 70 E L E M E N T S of the 
 
 always both curious and ufeful. But it is pity that 
 vefiels of this fort fhould not be able to endure a 
 fierce fire without melting. We fhall take care, 
 when we come to defcribe the feveral forts of chy- 
 mical inftruments, and the manner of ufing them, 
 to note what vefiels are to be preferred toothers on 
 different occafions. 
 
 Diftillation, as hath been already fud, is an ope- 
 ration by which we feparate from a body, by the 
 help of a gradual heat, the feveral principles of 
 which it confifts. 
 
 There are three methods of diftilling. The firft 
 is performed by applying the heat over the body 
 whofe principles are to be extracted. In this cafe, 
 as the liquors, when heated and converted into va- 
 pours, conftantly endeavour to fly from the center 
 of heat, they are forced to re-unite in the lower 
 j\irtof the vefTel, that contains the matter in diftil- 
 Jation, and fo patting through the pores or holes of 
 that veflel, they fall into another cold vefiel applied 
 underneath to receive them. This way of diftilling 
 is on this account called Diftilling per Defcenfum. 
 It requires no other apparatus than two veffels 
 figured like fegmeats of hollow fpheres, whereof 
 that which is pierced with little holes, and intended 
 to contain the matter to be diftilled, fhould be 
 much lefs than the other, which is to contain the 
 hre, and to fill its aperture exactly \ the whole to- 
 gether being fupported vertically upon a third vef- 
 k-1, v;hich is to ferve the purpole of a recipient, 
 admitting into its mouth the convex bottom of the 
 veflel containing the matter to be diftilled, which 
 muft accurately fill it. This method of diftilling 
 is but little ufed. 
 
 The fecond method of diftilling is performed by 
 applying the heat underneath the matter to be de- 
 compofed. On this occafion the liquors being 
 heated, rarefied, and converted into vapours, rife, 
 
 and
 
 THEORY 0/' CHYMISTRY. 171 
 
 and are condenfed in a veffel contrived for that 
 purpofe, which we fhall prefently defcribe. This 
 way of diflilling is called Diftilling per Afcenfum y 
 and is much ufed. 
 
 The veffel in which this diftillation $er Afcenfum 
 is performed we call an Alemlic. 
 
 There are feveral forts thereof differing from one 
 another both in the matter of which, and the man- 
 ner in which, they are made. 
 
 Thofe employed to draw the odoriferous waters 
 and efiential oils of plants are generally made of 
 copper, and confift of feveral pieces. The firft, 
 which is defigned to contain the plant, is formed 
 nearly like a hollow cone, the vertex whereof is 
 drawn out in the mape of a hollow cylinder or tube : 
 this part is named the Cucurbit, and its tube the 
 fleck of the Alembic. To the upper end of this 
 tube another veflel is foldered : this is called the 
 Head, and commonly has likewife the form of a 
 cone, joined to the neck of the alembic by its bafe, 
 round which, on the infide, is hollowed a fmall 
 groove, communicating with an orifice that opens at 
 its mod depending part. To this orifice is foldered a 
 fmall pipe in a direction floping downwards, which 
 is called the Nofe> Sptuf., or Beak of the alembic. 
 
 As loon as the matters contained in the alembic 
 grow hot, vapours begin to arife from them, and 
 alcending through the neck of the alembic into the 
 head, are by the fides thereof fcopped and condenfed : 
 from thence they trickle down in little dreams to 
 the groove, which conveys them to the fpout , and 
 by that they pafs out of the alembic into a glaf$ 
 veflel with a long neck, the end of the fpout being 
 introduced into that neck, and luted thereto. 
 
 TO facilitate the refrigeration and condenfation of 
 the vapours circulating in the head, all alembics of 
 metal are moreover provided with another piece, 
 which is a kind of lame pan of the fame metal, 
 
 i-> * ft 
 
 fitted
 
 172 ELEMENTS /" the 
 
 fitted and foldered round the head. This piece 
 ferves to keep cold water in, which incefiantly cools 
 the head, and therefore it is called the Refrigera- 
 tory. The water in the refrigeratory itielf grows 
 hot after fome time, and mult therefore be changed 
 occafionally , the heated water being firft drawn 
 off by means of a cock fixed near the bottom 
 of the refrigeratory. All copper alembics Ihould 
 be tinned on the infide for the reaions already 
 given. 
 
 When faline fpirits are to bediftilled, alembics of 
 metal muft not be uied ; becaufe the faline vapours 
 would corrode them. In this cafe recourfe muft be 
 had to alembics of glafs. Thefe confift of two 
 pieces only ; namely, a Cucurbit, whole fuperiour 
 orifice is admitted into and exactly luted with its 
 Jiead, which is the fecond pi<rce. 
 
 In general, as alembics require that the vapours 
 of the matter to be diftillcd mould rife to a confi- 
 derable height!),- they ought to be u!ed only when 
 the mod volatile principles are to be drawn from 
 bodies : and the lighter and more volatile the fub- 
 ftances to be feparated by diftillation are, rhe taller 
 muft the alembic be; becaufe the mod ponderous 
 parts, being unable to rife above a certain heighth, 
 fall back again into the cucurbit as foon as they 
 arrive there, leaving the lighter to mount alone, 
 whofe volatility qualifies them to afcend into the 
 head. 
 
 \Vhen a matter is to be diftilled, that requires 
 a very tall alembic, and yet does not admit of a 
 metalline veflel, the end will be beft anfwered by 
 a glais vefiel of a round or oval fhape, having 
 a very long neck, with a fmall head fitted to its 
 extremity. Such a veflel ferves many purpofes : 
 it is fometimes employed as a receiver, and at 
 other times as a digefting veflel ; on which laft 
 occafion it goes under the name of a Mafrafs. 
 i When
 
 ^THEORY c/* CHYMISTRY* 173 
 
 When one of thefe provided with a head is ap- 
 plied to the purpofe of diftilling, it forms a fort of 
 alembic. 
 
 There are fome alembics of glafs, blown in fuch 
 a manner by the workmen, that the body and head 
 form but one continued piece. As thefe alembics 
 do not ftand in need of having their feveral pieces 
 luted together, they are very ufeful on fome occa- 
 fions, when fuch exceeding fubtile vapours rife as 
 are capable of tranfpiring through lutes. The 
 head muft have an aperture at the top, provided 
 with a fhort tube, through which by means of a 
 funnel with a long pipe, the matter to be diftilled 
 may be introduced into the cucurbit. This is to 
 be exactly clofed with a glafs (topple, the furface 
 whereof muft be made to fit the infide of the tube 
 in every point, by rubbing thofe two pieces well 
 together with emery. 
 
 Another fort of alembic hath alfo been invented, 
 which may be ufed with advantage when Cohobation 
 is required ; that is, when the liquor obtained by 
 diftillation is to be returned upon the matter in the 
 cucurbit ; and efpecially when it is intended that 
 this cohobation mall be repeated a great number of 
 times. The vefftl we are fpeaking of is conftructed 
 exactly in the fame manner as that laft.defcribed ; 
 except that its beak, inltead of being in a ftraighc 
 line, as in the other alembics, forms a circular arch, 
 and re-enters the cavity of the cucurbit, in order 
 to convey back again the liquor collected in the 
 head. This inftrument hath commonly two beaks 
 oppofite to each other, both turned in this manner, 
 and is called a Pelican : it faves the artift the trouble 
 of frequently unluting and reluting his veffds, as 
 well as the lois of a great many vapours. 
 
 There are certain fubilances which in diftillation 
 afford matters in a concrete form, or rife wholly in 
 the form of a very light powder, called flowers. 
 
 "When
 
 174 ELEMENTS cf tht 
 
 When fuch fubftances are to be diftilled, the cu- 
 curbit which contains them is covered with a head 
 without a nofe, which is named a Blind-head. 
 
 When the flowers rife in great quantities and very 
 high, a number of heads is employed to collect 
 them ; or rather a number of a kind of pots, con- 
 fiding of a body only without any bottom, which 
 fitting one into the other form a canal, that may be 
 lengthened or fhortened at plealure, according as 
 the flowers to be lublimed are more or lefs volatile. 
 The laft of the heads, which terminates the canal, 
 is quite clofe at one end, and makes a true blind- 
 head. Thefe veflels are called Aludeh : they are 
 ufually of earthen or Hone ware. 
 
 All the vefiels above mentioned are fit only for 
 diftilling fuch light volatile matters as can be eafily 
 raifed and brought over; fuch as phlegm, eflential 
 oils, fragrant waters, acid oily Ipirits, volatile al- 
 kalis, &c. But when the point is to procure by 
 diiti'llation principles that are much lefs volatile, 
 and incapable of rifing high, fuch as the thick 
 fetid oils, the vitriolic, the nitrous, and the marine 
 acids, &c. we are under a neceflity of having 
 recourfe to other veflels, and another manner of 
 diftilling. 
 
 It is eafy to imagine that fuch a veflel muft be 
 rouch lower than the alembic. It is indeed no more 
 than a hollow globe, whofe upper part degenerates 
 into a neck or tube, that is tent into a horizontal 
 pofition ; for which reafon this inftrument is called 
 a Retort : it is always of one fingle piece. 
 
 The matter to be diftilled is introduced into the 
 body of the retort by means of a ladle with a long 
 tubular fhank. Then it is fet in a furnace built pur- 
 pofely for this ufe, and fo that the neck of the retort 
 coming out -of the furnace may, like the nofe of the 
 alembic, ftand in a doping pofition, to facilitate 
 the grefs of the liquors, which by its means are 
 
 conveyed
 
 THEORY 0f CHYMISTRY. 17$ 
 
 Conveyed to a receiver, into which it is introduced, 
 and with which it is luted. This way of diftilling, 
 in which the vapours feem rather to be driven out 
 of the veffel horizontally and laterally, than raifed 
 up and fublimed, is for that reafon called Diftilla- 
 tion per Latus. 
 
 Retorts are, of all the inftruments of diftillation, 
 thofe that muft fuftain the greateft heat, and refill 
 the ftrongeft folvents , and therefore they muft not 
 be made of metal. Some however, which are made 
 of iron may do well enough on certain occafions : 
 the reft are either of glafs or earth. Thofe of glafs, 
 for the reafons above given, are preferable to the 
 other fort, in all cafes where they are not to be 
 expofed to fuch a force of fire as may melt them. 
 The beft glafs, that which Hands both heat and 
 folvents beft, is that in which there are feweft al- 
 kaline falts. Of this fort is the green German glafs: 
 the beautiful white cryftal glafs is far from being 
 equally ferviceable. 
 
 Retorts, as well as alembics, may be of different 
 forms. For example, fome matters are apt to fwelf, 
 and rife over the neck of the retort in fubftance, 
 without fuffering any decompofition , when fuch 
 matters are to be diftilled in a retort, it is proper 
 that the body of the vefitl, inftead of being globu- 
 lar, be drawn out into the form of a pear, fo as 
 nearly to refemble that of a cucurbit. In a retort 
 of this kind, the diftance between the bottom and 
 the neck being much greater than in thofe whofe 
 bodies are fpherical, the matters contained have 
 much more room for expanfion , fo that the in- 
 convenience here mentioned is thereby prevented. 
 Retorts of this form are called Englifh retorts. As 
 they hold the middle place between alembics, and 
 common retorts, they may be ufed to diftill fuch 
 matters as have a mean degree of volatility be- 
 tween the greateft and the leaft. 
 
 It
 
 1 76 E L E M E N T S of tie 
 
 It is moreover proper to have, in a laboratory* 
 fundry retorts with necks of different diameters, 
 Wide necks will be found the fitted for conveying 
 thick matters, and fuch as readily become fixed ; 
 for inftance, fome very thick fetid oils, butter of 
 antimony, &c. : for as thefe matters acquire a con- 
 fidence as foon as they are out of the reach of a cer- 
 tain degree of heat, they would foon choak a nar- 
 row neck, and by (lopping the vapours, which rife 
 at the fame time from the retort, might occafton 
 the burfting of the vefiels. 
 
 Some retorts are alfo made with an opening on 
 their upper fide, like that of tubulated glafs alem- 
 bics, which is to be clofed in the fame manner with 
 a glafs ftopple. Thefe retorts are alfo called Tubu- 
 lated retorts, and ought always to be ufed whenever 
 it is neceffary to introduce freih matter into the re- 
 tort during the operation -, feeing it may be done 
 by means of this invention, without unluting and 
 icluting the veffels ; which ought always to be 
 avoided as much as poflible. 
 
 One of the things that mod perplexes the Chy- 
 mids, is the prodigious eladicity of many different 
 Vapours, which are frequently difcharged with im- 
 petuofity during the didillation, and are even capa- 
 ble of burding theveffels with explofion, and with 
 danger to the artid. On fuch occafions it is abfo- 
 lutely neceffary to give thefe vapours vent, as we 
 fhall direct in its proper place : but as that can ne- 
 ver be done without lofing a great many of them; 
 as fome of them in particular are fo elaftic that 
 fcarce any at all would remain in the veffel ; for 
 indance, thofe of the fpirit of nitre, and efpecially 
 thofe of the fmoking fpirit of fait-, the practice is to 
 make ufe of very large receivers, of about eighteen 
 or twenty inches diameter, that the vapours may 
 have fufficient room to circulate in, and by apply- 
 ing to the wide furface prefented them by the cxten- 
 
 five
 
 THEORY ^CHYMISTRY. 177 
 
 five infide of fuch a large veffel, may be condenfed 
 into drops. Thefe huge receivers are commonly in 
 the form of hollow globes, and are called Ballons. 
 
 To give thefe vapours (till more room, ballons 
 have been contrived with two open gullets in each, 
 diametrically oppofite to one another , whereof one 
 admits the neck of the retort, and the other is re- 
 ceived by one of the gullets of a fecond ballon of 
 the fame form, which is joined in like manner to 
 a third, and fo on. By this artifice the fpace may 
 be enlarged at pleafure. Thefe ballons with two 
 necks are called Adopters. 
 
 Operations on bodies that are abfolutely fixed, 
 as metals, Hones, land, &c. require only fuch 
 veflels as are capable of containing thofe bodies, 
 and refilling the force of fire. Thefe veflels are 
 little hollow pots, of different dimenfions, which, 
 are called Crucibles. Crucibles can hardly be made 
 of any thing but earth * they ought to have a cover 
 of the fame material fitted to (hut them clofe. The 
 beft earth we know is that whereof thofe pots are 
 made in which butter is brought from Bretagne : 
 thefe pots theinfelves are exceeding good crucibles; 
 and they are almoil the only ones that are capable of 
 holding glafs of lead in fufion, without being pe- 
 netrated by it. 
 
 For the roafting of ores, that is, freeing them, 
 by the help of fire, from their fulphureous and arfe- 
 nical parts, little cups made of the fame material 
 with crucibles are ufed , but they are made flat, 
 fhallow, and wider above than below, that thefe vo- 
 latile matters may the more freely exhale. Thefe 
 vefiels are called Tefts, or Scorifiers : they are 
 fcarce ever ufed but in the Docimaftic art, that is, 
 in making fmall Aflays of ores. 
 
 VOL. I. N CHAP.
 
 178 ELEMENTS^/" the 
 
 CHAP. XIX. 
 
 The THEORY of CONSTRUCTING the 
 FURNACES mojl commonly ufed in 
 CHYMISTRV. 
 
 SKILL in conducting and applying fire pro- 
 perly, and determining its different degrees, is 
 of very great conicquence to the fuccefs of Chymi- 
 cal operations. 
 
 As it is exceeding difficult to govern and mode- 
 rate the action of fire, when the vefiels in which any 
 operation is performed are immediately expoled to 
 it, Chymifts have contrived to convey heat to their 
 veflels, in nice operations, through different me- 
 diums, which they place occafionaliy between thole 
 vefiels and the fire. 
 
 Thofe intermediate fubftances in which they 
 plunge their vcffcls are called Baths. They are 
 cither fluid or folid : the fluid baths are water or its 
 vapours. When the diftilling veffel is let in water, 
 the bath is called Balneum Marine, or the Water- 
 Ee.tb-, and the greateft degree of heat of which it 
 is fulceptiblc is that of boiling water. When the 
 velfel is expoled only to the vapours which exhale 
 from water, this forms the Fapour-Eatb ; the heat 
 of which is nearly the fame with that of the Bal- 
 neum Marine. Thefe baths are ufeful for diftilling 
 cllential oils, ardent fpirits, fweet-fcented waters ; 
 "in a word, all fuch fubftances as cannot bear a 
 greater heat, without prejudice either to their 
 tdour, or 10 fome of their other qualities. 
 
 Baths
 
 THEORY of CHYMISTRY. 179 
 
 Baths may alfo be made of any other fluids, 
 fuch as oils, mercury, &c. which are capable of 
 receiving and communicating much more heat : 
 but they are very feldom ufed. When a more con- 
 fiderable degree of heat is required, a bath is pre- 
 pared of any folid matter reduced to a fine powder, 
 fuch as fand, afhes, filings of iron, &c. The he;ic 
 of thefe baths may be pufhed fo far as to make the 
 bottom of the veflel become faintly red. By plung- 
 ing; a thermometer into the bath, by the fide of the 
 vefltl, it is eafy to obferve the precife degree of 
 heat applied to the fubftance on which you are 
 working. It is neceffary that the thermometers 
 employed on this occafion be contlrudted on good 
 principles, and fo contrived as to be eafily compared 
 with thofe of the moft celebrated natural philofo- 
 phers. Thofe of the illuftrious Reaumur are moil 
 ufed and befc known, fo that it would not be amifs 
 to give them the preference. When a greater heat 
 is required than any of thofe baths can give, the 
 veffels muft be fet immediately on live coals, or in 
 a flaming fire : this is called working with a naked 
 fire ; and in this cafe it is much more difficult than 
 in the other to determine the degrees of heat. 
 
 There are feveral ways of applying a naked fire. 
 "When the heat or flame is reflected upon r -,t upper 
 part of a veflel which is expofed to the fire, this is 
 called a Reverberated heat. A Melting heat is that 
 which is ftrong enough to fufe moft bodies. A 
 Forging heat istbat of a fire which is forcibly excited 
 by The conftant blaft of a pair of bellows, or more. 
 
 There is alfo another fort of fire which fervcs 
 very commodioufly for many operation?, becaule it 
 does not requi/e to be fed or frequently mended : 
 this is afforded by a lamp with one or more 
 wicks, and may be called a Lamp-heat. It is 
 fcarce ever employed but to heat baths, in op rj ra- 
 tions which require a gentle and long continued 
 
 2 warmth :
 
 l8o E L E M E N T S of the 
 
 warmth : if it hath any fault, it is that of growing 
 gradually hotter. 
 
 All the different ways of applying fire require 
 Furnaces of different conftructions : we fhall there- 
 lore deicribe fuch as are of principal and nioft ne- 
 c diary ule. , 
 
 Furnaces muft be divided into different parts or 
 (lories, each of which has its particular ule and 
 name. 
 
 The lower part of the furnace defigned for re- 
 ceiving the allies, and giving paffage to the air, is 
 called the Afh-holc. 1 he alh-hole is terminated 
 above by a Grate, the ule of which is to fupport the 
 coals and wood, which are to be burnt thereon : 
 this part is culled the Fire-place. The fire-place is 
 in like manner terminated above by feveral iron 
 bars, which lie quite a-crofs it from right to left, in 
 
 s parallel to each other : the ule of thefe bars is 
 to luttain the vcffels in which the operations are to 
 be performed. The (pace above thefe bars to the 
 top of the furnace is the upper (lory, and may be 
 lulled the Laboratory of the furnace. Laftly, fome 
 furnaces are quite covered above by means of a kind 
 of vaulted roof called the dome. 
 
 Furnaces have moreover feveral apertures : one of 
 thefe is at the afh-hole, which gives paffage to the 
 air, and through which the afhes that fall through 
 the grate are raked out ; this aperture is called the 
 afh-hole door : another is at the fire-place, through 
 which the fire is fupplicd with fuel, as occafion 
 requires , this is called the mouth or door of the 
 fire-place, or the ftoke-hole : there is a third in the 
 upper ftory, through which the neck of the veffel 
 palfes ; and a fourth in the dome for carrying off 
 the fuliginofnies of combuftible matters, which is 
 called the chimney. 
 
 To conclude, there are feveral other openings 
 in the feveral pares of the furnace, the ufe whereof 
 
 is
 
 THEORY ?/ CHYMISTRY. 181 
 
 is to admit the air into thofe places, and alfo, as 
 they can be eafily fhut, to incite or flacken the 
 activity of the fire, and ib to regulate it; which has 
 procured them the title of regifters. All the other 
 openings of the furnace fhould be made to Ihut 
 very clofe, the better to affift in governing the fire ; 
 by which means they likewife do the office of 
 regifters. 
 
 In order to our forming ajuft and general idea of 
 the conftruction of furnaces, and of the difpofition 
 of the feveral apertures in them, with a view to in- 
 crcafe or diminifli the activity of the fire, it will 
 be proper to lay down, as our ground-work, cer- 
 tain principles of natural philofophy, the truth of 
 which is demonftrated by experience. 
 
 And firft, every body knows that combuftible 
 matters will not burn or confume unlefs they have a 
 free communication with the air; infomuch that if 
 they be deprived thereof, even when burning mod 
 rapidly, they will be extinguifhed at once : that 
 confequently combuftion is greatly promoted by the 
 frequent accefiion of frefh air, and that a ftream of 
 air, directed fo as to pals with impetuofity through 
 burning fuel, excites the fire to the greateft pofiible 
 activity. 
 
 Secondly, it is certain that the air which touches, 
 or comes near ignited bodies is heated, rarefied, and 
 rendered lighter than the air about it, that is, further 
 diftant from the center of heat ; and confequently 
 that this air, fo heated and become lighter, is ncceffa- 
 rily determined thereby to afcend and mount aloft, 
 in order to make room for that which is lefs heated 
 and not fo light, which by its weight and elafti- 
 city tends to occupy the place quitted by the other. 
 Another confequence hereof is, that if fire be kind- 
 led in a place inclofed every where but above and 
 below, a current of air will be formed in that place, 
 running in a direction from the bottom to the top ; 
 N 3 fo
 
 182 ELEMENTS^/* the 
 
 fo that if any light bodies be applied to the opening 
 below, they will be carried up towards ths fire ; 
 but, on the contrary, if they be held at the open- 
 ino; above, they will be impelled by a force which 
 will drive them up and carry them away from the 
 fire. 
 
 Thirdly and hftly, it is a truth demonftrated in 
 hydraulics that the velocity of a given quantity of 
 any fluid, determined to flow in any direction what- 
 ever, is fo much the greater the narrower the chan- 
 nel is to which that fluid is confined; and conse- 
 quently that the velocity of a fluid will be increaled 
 by making it run from a wider through a narrower 
 paflfage. 
 
 Thefe principles being eftabliftied, it is eafy to 
 apply them to the con ft ruction of furnaces. Firfl, 
 if a fire be kindled in the tiro-place of a furnace, 
 which is open on all fides, it burns nearly as if it 
 were in the open air. It has with the furroundini; 
 air a free communication , fo that frefh air is conti- 
 nually admitted to facilitate the entire combuilion 
 of the inflammable matters employed as fuel. But 
 there being nothing to determine that air to pals 
 with rapidity through the fire in this caie, it does 
 not at all augment the activity thereof, but fufTcrs 
 it to wafte away quietly. 
 
 Secondly, if the afh-hole or dome of a furnace, 
 in which a fire is burning, be fhut quite clofe, then 
 there is no longer any free communication between 
 the air and the fire : if the afh-hole be fhut, the air 
 is debarred from having free accefs to the fire -, if 
 the dome be ftopt, the egrets of the air rarefied by 
 the fire is prevented ; and coniequently the fire 
 muft in either cafe burn very faintly and flowiy, 
 gradually die away, and at laft go quite out. 
 
 Thirdly, if all the openings of the furnace be 
 wholly clofed, it is evident that the fire will be very 
 quickly cxtinguiihed. 
 
 Fourthly,
 
 THEORY of CIIYMIS TRV. 183 
 
 , Fourthly, if only the lateral openings of the fire- 
 place be fnut, leaving the afl>hoje and upper part 
 of the furnace open -, it is plain that the air 
 entering by the afb-hole will necefiarily be deter- 
 mined to go out at top, and .that confequently a 
 current of air will be formed, which will pafs 
 through the fire, and make it burn brifkly and vi^ 
 goroufly. 
 
 Fifthly, if both the afh-hole and the upper ftory 
 of the furnace be of fome length, and form canals 
 either cylindric or prifmatic, then the air being 
 kept in the fame direction through a longer fpace, 
 the courle of its ftream will be both flronn;er and 
 better determined, and confequently the fire will 
 be more animated by ir. 
 
 Sixthly and laftly, if the afh-hole and the upper 
 part of the furnace, inltead of being cylindric or prif- 
 matic canals, have the form of truncated cones or 
 pyramids, (landing on their bafes, and fo ordered 
 that the upper opening of the afh-hole, adjoining 
 to the fire place, may be wider than the bafe of the 
 fuperiour cone or pyramid, then the ftream of air, 
 being forced to pafs inceiTantly from a larger chan- 
 nel through a imallcr, mud be confickrably ac- 
 celerated, and procure to the fire the greateft ac- 
 tivity which it can receive from the make of a 
 furnace. 
 
 The materials fitteft for building furnaces are, 
 i. Bricks, joined together with potters clay mixed 
 with fand and moiftened with water. 2. Potters 
 clay mingled with potfherds, moiftened with wa- 
 ter, and baked in a violent fire. 3. Iron > of 
 which all furnaces may be made, with this precau- 
 tion, that the infidc be provided with a great many 
 prominent points, as faftenings for a coat ot earth, 
 with which the internal parts of the furnace mull 
 neceflarily be covered to defend it from the action 
 of the fire. 
 
 N 4 Th ~
 
 184 E L E M E N T s of the 
 
 The reverberatingfurnace is one of thofe that arc 
 moft employed in Chymiftry : it is proper for di- 
 flillations by the retort, and fhould be conftructed 
 in the following manner. 
 
 Firft, the ufe of the afh-hole being, as was faid, 
 to give pafTage to the air and to receive the afhes, no 
 bad confequence can attend its being made pretty 
 high: it may have from. twelve to twenty or twenty- 
 four inches in heighth. Its aperture fhould be wide 
 enough to admit billets of wood, when a great fire 
 is to be made. 
 
 Secondly, the afh-hole muft be terminated at 
 its upper part by an iron grate, the bars of which 
 fhould be very fubftantial, that they may rcfift the 
 a6tion of the tire : this grate is the bottom of the 
 fire-place, and deftined to fupport the coals. In the 
 lateral part of the fire-place, and nearly about the 
 fame heighth with the grate, there fhould be a hole 
 of fuch a fize that it mayeafily admitcharcoal,as well 
 as little tongs and fhovcls for managing the fire. 
 
 c? o \J 
 
 This aperture or mouth of the fire-place fhould be 
 perpendicularly over the mouth of the alh-hole. 
 
 Thirdly, from fix to eight or ten inches high 
 above the grate over the afh-hole, little apertures muft 
 be made in the walls of the furnace, of eight or ten 
 lines in diameter, an inch from one another, and 
 thofe in one fide muft be diametrically oppofitc to 
 thofe in the other. The ufe of thefe holes is to re- 
 ceive bars of iron for the retort to reft on , which 
 fhould be, as I faid, at different heights, in order to 
 accommodate retorts of different fizes. At the up- 
 per extremity of this part of the furnace, which 
 reaches from the iron bars to the top, the heighth 
 whereof mould be fomewhat lefs than the width of 
 the furnace, muft be cut a femi-circular aperture 
 for the neck of the retort to come through. This 
 hole muft by no means be over the doors of the fire- 
 place and afh-hole j for then, as itgivespafTagetothe 
 
 neck
 
 THEORY C/'CHYMISTRY. 185 
 
 neck of the retort, it muft of courfe be oppofite to 
 the receiver, and in that cafe the receiver itfelf 
 would (land over againft thofe two apertures; which 
 would be attended with this double inconvenience, 
 that the receiver would not only grow very hot, 
 but greatly embarrafs the operator, whofe free ac- 
 cefs to the fire-place and afh-hole would be thereby 
 obstructed. Itisproperthereforethatthefemi-circu- 
 Jar cut we are fpeaking of be fo placed that when 
 the greateft ballons are luted to the retort they may 
 leave an open pafiage to the fire-place and afh-hole. 
 
 Fourthly, in order to cover in the laboratory of 
 the reverberating furnace, there muft be a roof 
 made for it in the form of a cupola, or concave 
 hemifphere, having the fame diameter as the fur- 
 nace. This dome fhould have a femicircular cut 
 in its rim anfwering to that above-directed to be 
 made in the upper extremity of the furnace, fo that, 
 when adj uiled to each other, the two together may 
 form a circular hole for the neck of the retort to 
 pafs through. At the top of this dome there muft 
 alfo be a circular hole of three or four inches diame- 
 ter, carrying a mort tapering funnel of the fame 
 diameter, and three inches high, which will ferve 
 for a chimney to carry offall fuliginofities, and acce- 
 lerate the current of the air. This paffage may be 
 fhut at pleafure with a flat cover. Moreover, as it 
 is neceffary that the dome fhould be taken off and 
 put on with eafe, it fliould have two ears or handles 
 for that purpofe: a portative or moveable furnace 
 fhouid alfo have a pair of handles, fixed oppofite 
 to each other, between the afh-hole and the fire- 
 place. 
 
 Sixthly and laftly, a conical canal muft be pro- 
 vided of about three feet long, and fufficiently wide 
 at its lower end to admit the funnel of the aperture 
 at the top of the dome. This conical tube is to be 
 applied to the dome when the fire is required to be 
 
 extremely
 
 1 86 ELEMENTS*/" the 
 
 extremely active : it tapers gradually from its bafc 
 upwards, and breaks off as if truncated at top, 
 where it fhould be about two inches wide. 
 
 Befides the apertures already mentioned as necef- 
 fary to a reverberating furnace, there mud alfo be 
 many other (mailer holes made in its aili-hole, fire- 
 place, laboratory, and dome, which mull all be ib 
 contrived as to be eafily opened and fhut with itop- 
 ples of earth : theie holes are the rcgifters of the 
 furnace, and ferve to regulate the activity of the 
 fire, according to the principles before laid down. 
 
 When the action of the tire is required to be 
 exactly uniform and very brifk, it is necefTary to flop 
 carefully with moid earth all the little chinks in the 
 juncture of the dome with the furnace, between the 
 neck of the retort and the circular hole through 
 which it pafles, and which it never fills exactly; 
 and laftly, the holes which receive the iron bars 
 that fuftain the retort. 
 
 It is proper to have, in a laboratory, leveral rever- 
 berating furnaces of different magnitudes ; becauie 
 they muft be proportioned to the fize of the retorts 
 employed. The retort ought to fill the furnace, fo 
 as to leave only the diftancc of an inch between it 
 and the infide of the furnace. 
 
 Yet when the retort is to be expofed to a moil 
 violent fire, and efpecially when it is required that 
 the heat mall act with equal force on all parts of the 
 furnace, and as ftrongly on its vault as on its bot- 
 tom, a greater diltance muft be left between the re- 
 tort and the infide of the furnace ; for then the 
 furnace may be filled with coals, even to the upper 
 part of the dome. If moreover fomc pieces of wood 
 be .put into the afh-hole, the conical canal fitted on 
 to the funnel of the dome, and all the apertures of 
 the furnace exactly clofed, except the afh-hole and 
 the chimney, the greateft heat will then be excited 
 that this furnace can produce. 
 
 The
 
 THEORY C/CHYMISTRY. 187 
 
 The furnace now defcribed may alfo be employed 
 in many other chymical operations. If the dome 
 be laid afide, an alembic may very well be placed 
 therein : but then the ipace, which will be left be- 
 tween the body of, the alembic and the top of the 
 upper part of the furnace, mud be carefully filled 
 up with Windfor-loam moiftened; for without thac 
 precaution the heac would foon reach the very head, 
 which ought to be kept as cool as poflible, in order 
 to promote the comiehfation of the vapours. On 
 this occafion therefore it will be proper to leave no 
 holes open in the fire-place, but the lateral ones-, 
 of which alfo thoie over-againft the receiver muft 
 be flopped. 
 
 A pot, or broad-brimmed earthen pan, may be 
 placed over this furnace, and be ing fo fitted to ir 
 .as to cloie the upper part thereof accurately, and 
 filled with land, may ierve for a fand-heat to diftil 
 with. 
 
 The bars defigned to fupport diftilling vefiels 
 being taken out, a crucible may (land therein, and 
 many operations be performed that do not require 
 the utmoft violence of fire. In a word, this -fur- 
 nace is one of the moft commodious that can be, 
 and more extenfively ufeful than any other. 
 
 The Melting furnace is defigned for applying 
 the greateft force of heat to the moft fixed bodies, 
 fuch as metals and earths, It is never .employed in 
 diftilling: it is of no ufe but for calcination and 
 fufion ; and confequently need not admit any vef- 
 iels but crucibles. 
 
 The afh-hole of this furnace differs from that of 
 v the reverberating furnace only in this, that it muffc 
 be higher, in order to raife the fire-place to a level with 
 the artift's hand; becaufe in that all the operations 
 of this furnace are performed. The alb-hole there- 
 fore muft be about three feet high : and this heighth 
 procures it moreover the advantage of a good 
 
 draught
 
 1 S3 E L E M E N T S of the 
 
 draught of air. For the fame reafon, and in con- 
 fequenceof the principles we laid down, it fhould be 
 io built that its width leflening infenfibly from the 
 bottom to the top, it may be narrower where it 
 opens into the fire-place than any where below. 
 
 The afh-hole is terminated at its upper end, like 
 that of the reverberating furnace, by a grate, which 
 ferves for the bottom of the fire-place, and ought to 
 be very fubftantial that it may refift the violence of 
 the fire. The infide of this furnace is commonly an 
 elliptic curve; becaufe it is demonltrated by mathe- 
 maticians that furfaces having that curvature reflect 
 the rays of the fun, or of fire, in luch a manner 
 that meeting in a point, or a line, they produce there 
 a violent heat. But to anfwer this purpofe thofe 
 furfaces muft be finely polifhed ; an advantage 
 hardly procurable to the internal furfaceof this fur- 
 nace, which can be made of nothing but earth : 
 befides, if it were pofllble to give it a polifh, the 
 violent action of the fire that mull be employed 
 in this furnace would prefemly deftroy it. Yet 
 the elliptical figure muft not be entirely difre- 
 garded : for, if care be taken to keep the internal 
 iurface of the furnace as fmooth as poffible, it will 
 certainly reflect the heat pretty ftrongly, and col- 
 lect it about the center. 
 
 The fire-place of this furnace ought to have but 
 four apertures. 
 
 Firft, that of the lower grate, which communi- 
 cates with the afh-hole. 
 
 Secondly, a door in its fore-fide, through which 
 may be introduced coals, crucibles, and tongs for 
 managing them : this aperture mould be made to 
 fhut exactly with a plate of iron, having its infide 
 coated with earth, and turning on two hinges fixed 
 to the furnace. 
 
 Thirdly, over this door a hole flanting down- 
 wards, towards the place where the crucible is to 
 
 Hand.
 
 THEORY of CHVMISTRY. 189 
 
 (land. The ufe of this hole is to give the operator 
 an opportunity of examining the condition of the 
 matters contained in his crucible, without opening 
 the door of the fire-place : this hole fhould be made 
 to open and fhut eafily, by means of a ftopple of 
 earth. 
 
 Fourthly, a circular aperture of about three inches 
 wide in the upper part or vault of the furnace, 
 which mould gradually lefien and terminate, like 
 that of the dome of the reverberating furnace, in a 
 fhort conical funnel of about three inches long, and 
 fitted to enter the conical pipe before defcribed, 
 which is applied when the activity of the fire is to 
 be increafed. 
 
 When this furnace is to be ufed, and a crucible 
 to be placed in it, care mud be taken to fet on the 
 grate a cake of baked earth, fomewhat broader than 
 the foot of the crucible. The uie of this (land is 
 to fupport the crucible, and raife it above the 
 grate, for which purpofe it fhould be two inches 
 thick. Were it not for this precaution the bottom 
 of the crucible, which would (land immediately on 
 the grate, could never be thoroughly heated, be- 
 canfe it would be always expofed to the dream of 
 cold air which enters by the afh-hole. Care fhould 
 alfo be taken to heat this earthen bottom red-hot 
 before it be placed in the furnace, in order to free it 
 from any humidity, which might otherwife happen 
 to be driven againft the crucible during the opera- 
 tion, and occafion its breaking. 
 
 We omitted to take notice in fpeaking of the 
 am-hole that, befides its door, it mould have about 
 the middle of its heighth a fmall hole, capable of 
 receiving the nofel of a good perpetual bellows, 
 which is to be introduced into it and worked, after 
 the door is exactly (hut, when it is thought pro- 
 per to excite the activity of the fire to the utmoft 
 violence. 
 
 The
 
 I go ELEMENTS of the 
 
 The Forge is only a mafs of bricks of about three 
 feet high, alon^ whole upper furl ace is directed the 
 nofe or pipe of a pair of hrge perpetual bellows, fo 
 placed that the operator may eafily blow the fire 
 with one hand. The coals are laid on the hearth of 
 the forge, near the nofe of the bellows; they arc 
 confined, ir neceflary, to prevent their being car- 
 . the wind of the bellows, within a 
 Ipacc.inclolVd by bricks ; and then by pulling the 
 i .vs the fire is continually kept up in its greatell 
 activity. The forge is of uie v. hen there is occafion 
 to apply a great degree of heat fuddenly to any 
 jubilance, qr when it is nrefls.ry that the operator 
 be at liberty to handle frequently the matters which 
 lie propoles to fufe or calcine. 
 
 The Cupelling furnace is that in which gold and 
 filver are purified, by the means of lead, from all 
 alloy of other metallic Jubilances. This furnace 
 mult give a heat Urong enough to vitrify lead, and 
 therewith all the alloy which the perfect metals may 
 contain. This furnace is to be built in the follow- 
 ing manner. 
 
 I/'irft, of thick iron-plates, or of fome fuch 
 compofition of earth as we recommended for the 
 conltruciion of furnaces, mull be formed a hol- 
 low quadrangular priirn, whole fides may be 
 about a loot broad, and from ten to eleven inches 
 high ; and extending from thence upwards may 
 converge towards the top, fo as to form a pyra- 
 mid truncated at the heighth of feven or eight 
 inches, and terminated by an aperture of the width 
 of fevcn or eight inches every way. The lower 
 part of the prifm is terminated, and doled, by a 
 plate of die lame materials of which the furnace is 
 conltrucTted. 
 
 Secondly, in the fore- fide or front of this prifm 
 
 is an opening of three or four inches in heighth 
 
 5 by
 
 THEORYO/'CHYMISTRY. 191 
 
 by five or fix inches in breadth : this opening, 
 which mould be very near the bottom, is the door 
 of the ath-hole. Immediately over this opening is 
 placed an iron grate, the bars of which are qua- 
 drangular prifms of half an inch fquare, laid par- 
 rallel to each other, and about eight or nine inches 
 afunder, and fo difpofcd that two of their angles 
 are laterally oppofite, the two others looking one 
 directly upwards and the other downwards. As 
 in this fituation the bars of the grate prefent to the 
 fire-place very oblique furfaces, the ames and very 
 fmall coals do not accumulate between them, or 
 hinder the free entrance of the air from the afh- 
 hole. This grate terminates the afti-hole at its 
 upper part, and ferves for the bottom of the fire- 
 place. 
 
 Thirdly, three inches, or three and a half, above 
 the grate, there is in the fore-fide of the furn?ce 
 another opening terminated by an arch for its upper 
 part, which confequently has the figure of a fcmi- 
 circle : it ought to be four inches wide at bottom, 
 and three inches and an half high at its middle. 
 This opening is the door of the fire-place , yet it is 
 not intended for the fame uies as the door of the fire- 
 place in other furnaces : the purpofe for which it is 
 actually deftir.ed mall be explained when we come 
 to (hew how the furnace is to be ufed. An inch 
 above the door of the fire-place, ftill in the fore-fide 
 of the furnace, are two holes of about an inch dia- 
 meter, and at the diftance of three inches and a 
 half from each other, to which anfwer two other 
 holes of the fame fize, made in the hinder part, 
 directly oppofite to thefe. There is moreover a 
 fifth hole of the fame width about an inch above the 
 door of the fire-place. The defign of all thefe 
 holes mall be explained when we deicribe the man- 
 ner in which thefe furnaces are to be ufed. 
 
 Fourthly,
 
 Ip2 E L E M E N T S Of tie 
 
 Fourthly, the fore-part of the furnace is bound 
 by three iron braces, one of which is fixed juft be- 
 low the door of the alli-hole-, the fccond occupies 
 the whole fpace between the afli-hole door and the 
 door of the tire-place, and lias two holes in it, 
 anlwering to thole which \ve directed to be made in 
 the furnace itlelf about this place -, and the third is 
 placed immediately over the door of the fire-place. 
 Thefe braces mud extend from one corner of the 
 front of the furnace to the other, and be fattened 
 thereto with iron pins, in fuch a manner that their 
 flues next to the doors may not lie quite dole to the 
 body of the furnace, but form a kind of grooves 
 for the iron plates to flide in, that are defigned to 
 fiuit the two doors of the furnace when it is necef- 
 fary. Each of thefe iron plates fnould have a han- 
 dle, by which it may be conveniently moved , and 
 to each door there fnould be two plates, which 
 meeting each other, and joining exactly in the mid- 
 dle of the door-place, may ihut it very dole. Each 
 of the two plates belonging to the door of the fire- 
 place ought to have a hole in its upper part ; one 
 of thefe holes fhould be a (lit of about two lines 
 wide, and half an inch long ; the other may be a 
 lemi-tircular opening of one inch in height and two 
 in breadth. Thefe holes mould be placed fo that 
 neither of them may open into the fire-place when 
 the two plates are joined together in the middle of 
 the door to Ihut it clofe. 
 
 Fifthly, to terminate the furnace above, there 
 muft be a pyramid formed of the fame materials 
 with the furnace, hollow, quadrangular, three 
 inches high on a bafe of leven inches, which bale 
 mult exactly fit the upper opening of the furnace : 
 the top of this pyramidal cover muft end in a tube 
 of three inches in diameter and two in heighth, 
 which mult be almolt cylindrical, and yet a little 
 inclining to the conical form. This tube ferves, 
 
 as
 
 THEORY ^CHYMISTRY. 193 
 
 as in the furnaces already defcribed, to carry the. 
 conical funnel, which is fitted to the upper part 
 when a fire of extraordinary activity is wanted. 
 
 The furnace thus conftrudted is fit to ferve all the 
 purpofes for which it is defigned: yet before it can 
 be ufed another piece mult be provided, which, 
 though it does not properly belong to the furnace, 
 is neverthelefs neceffary in all the operations per- 
 formed by it ; and that is a piece contrived to con- 
 tain the cupels, or other vefiels which are to be ex- 
 pofed to the fire in this furnace. It is called a 
 Muffle, and is made in the following manner. 
 
 On an oblong fquare, of four inches in breadth, 
 and fix or feven in length, a concave femi-cylinder 
 is erected, in the form of a vault, which makes a 
 femi-circular canal, open at both ends. One of thefe 
 is almoft entirely clofed, except that near the bot- 
 tom two fmall femi-circular holes are left. In each 
 of its fides likewife two fuch holes are made, and 
 the other end is left quite open. 
 
 The Muffle is intended to bear and communicate 
 the fierceft heat j and therefore it muft be made 
 thin, and of an earth that will refift the violence of 
 fire, fuch as that of which crucibles are made. The 
 Muffle being thus conftrufted, and then well baked., 
 is fit for ufe, 
 
 When it is to be ufed it muft be put into the fur- 
 nace by the upper opening, and fet upon two iron 
 bars, introduced through the holes made for that , 
 purpofe below the door of the fire-place. The 
 Muffle mult be placed on thefe bars in the fire-place 
 in fuch a manner that its open end (hall ftand next to, 
 and directly againft, the door of the fire-place, and 
 may be joined to it with lute. Then the cupels are 
 ranged in it,and the furnace is filled up,to the hcighth 
 of two or three inches above the Muffle, with fmali 
 coals not bigger than a walnut, to the end that they 
 may lie dole round the Muffle, and procure it an 
 
 VOL. I. O equal
 
 194 E L E M E N T s 0/* the 
 
 equal heat on every fide. The chief ufe of the Muffle 
 is to prevent the coals and allies from falling into the 
 cupels, which would be very prejudicial to the ope- 
 rations carrying on in them : for the lead would not 
 vitrify as it ought, becaule the immediate contact 
 of the coals would continually reftore its phlogifton ; 
 or elfe the glafs of lead, which ought to penetrate 
 and pals through the cupels, would be rendered in- 
 capable of fcr doing-, becaufe the afhes mixing 
 therewith would give it fuch a confidence and te- 
 nacity as would deftroy that property, or at leaft 
 confiderably lefien it. The openings therefore, 
 wliich are left in the lower part of the Muffle, mould 
 not be fo high as to admit coals or afhes to get into 
 the cupels ; the ufe of them is to procure an eafier 
 pafifage for the heat and the air to thofe veflels. The 
 Muffle is left quite open in its fore-part, that the 
 operator may be at liberty to examine what pafies in 
 the cupels, to ftir their contents, to remove them 
 from one place to another, to convey new matters 
 into them, &c. and alfo to promore the free accefs 
 of the air, which mud concur with the fire towards 
 the evaporation neceflary to the vitrification of lead ; 
 which air, if frefh were not often enough admitted, 
 would be incapable of producing that effect ; be- 
 caufe it would foon be loaded with fuch a quantity 
 of vapours that it could not take up any more. 
 
 The government of the fire in this furnace is 
 founded on the general principles above laid down 
 for all furnaces. Yet as there are fome little dif- 
 ferences, and as it is very efiential to the fuccefs of 
 the operations for which this furnace is intended, 
 that the artift fhould be abfolutely mailer of his de- 
 gree of heat, we (hall in few words mew how that 
 may be raifed or lowered. 
 
 When the furnace is filled with coals and kindled, 
 jf the dcor of the alh-hole be fet wide open, and 
 of the fire-place fhut very clofe, the force of 
 \
 
 THEORY of CHYMISTRY. 
 
 the fire is increafed ; and if moreover the pyrami- 
 dal cover be put on the top, and the conical funnel 
 added to it, the fire will become ftill more fierce. 
 
 Seeing the matters contained in this furnace arc 
 encompaffed with fire on all fides, except in the 
 fore part oppofite to the door of the fire-place, and 
 as there are occafions which require that the force 
 of the fire fhould be applied to this part alfo, aa 
 iron box, of the fhape and fize of the door, hath 
 been contrived to anfwer that purpoie. This box 
 is filled with lighted coals, and applied immediately 
 to the door-place, by which means the heat there 
 is confiderably augmented. This help may be 
 made ufe of at the beginning of the operation, in 
 order to accelerate it, and bring the heat fooner to 
 the defired degree ; or in cafe a very fierce heat be 
 required ; or at a time when the air being hot and 
 moid will not make the fire burn with the neceflary 
 vigour. 
 
 The heat may be lefiened by removing the iron 
 box, and fhutting.the door of the fire-place quite 
 clofe. It may be ftill further and gradually dimi- 
 niftied, by taking off the conical funnel from the 
 top , by (hutting the door of the fire-place with one 
 of its plates only, that which has the kaft, or that 
 which has the greateft aperture in it j by taking off 
 the pyramidal cover j by fhutting the afh-hole door 
 wholly or in part i and laftly, by fetting the door of 
 the fire-place wide open : but, in this lad cafe, the 
 cold air penetrates into the cavity of the Muffle, and 
 refrigerates the cupels more than is almoft ever ne- 
 ceffary. If it be obferved, during the operation, 
 that the Muffle grows cold in any particular part, 
 it is a fign there is a vacuity left by the coals 
 in that place : in this cafe an iron wire muft be 
 thruft into the furnace, through the hole which is 
 over the door of the fire-place, and the coals ftirred 
 O 2 there-
 
 196 E L E M E N T S of the 
 
 therewith, fo as to make them fall into their pkces 
 and fill up the vacant interfaces. 
 
 It is proper to obferve that, befides what has been 
 faid concerning the ways of increafing the activity 
 cf the fire in the cupelling furnace, feveral other 
 catifes alfo may concur to procure to the matters 
 contained in the Muffle a greater degree of heat : 
 for example, the fmaller the Muffle is, the wider 
 and more numerous the holes in it are; the nearer 
 to its bottom, or further end, the cupels are placed; 
 the more will the matters therein contained be af- 
 fected with heat. 
 
 Befides the operations to be performed by the cu- 
 pel, this furnace is very ufeful and even necefiary,for 
 many chymical experiments-, fuch, for inftance, as 
 thofe relating to fundry vitrifications andenamelling. 
 As it is pretty low, the beft way is to place it, when 
 it is to be ufed, on a bafe of brick- work that may 
 raife it to a level with the operator's hand. 
 
 A Lamp-furnace is exceeding ufeful for all ope- 
 rations that require only a moderate, but long con- 
 tinued, degree of heat. The furnace for working 
 with a lamp-heat is very fimple : it confifts only of 
 a hollow cylinder, from fifteen to eighteen inches 
 high, and five or fix in diameter, having at its bot- 
 tom an aperture large enough for a lamp to be in- 
 troduced and withdrawn with eafe. The lamp 
 muft have three or four wicks, to the end that by 
 lighting more or fewer of them a greater or lefs de- 
 gree of heat may be produced. The body of the 
 furnace muft moreover have feveral fmall holes in 
 it, in order to fupply the flame of the lamp with 
 air enough to keep it alive. 
 
 On the top of this furnace ftands a bafon five 
 or fix inches deep, which ought to fill the cavity of 
 the cylinder exactly, and to be fupported at its cir- 
 cumference by a rim which may entirely cover and 
 clofe the furnace : the ufe of this bafon is to con- 
 i tain
 
 THEORY of CHYMISTRY. 197 
 
 tain the fand through which the lamp-heat is ufu* 
 ally conveyed. 
 
 Befides this there muft be a kind of cover or dome 
 made of the fame material with the furnace, and o 
 the fame diameter with the fand-bath, without any 
 other opening than a hole, nearly circular, cut in 
 its lower extremity. This dome is a fort of rever- 
 beratory, which ferves to confine the heat and di- 
 rect it towards the body of the retort ; for it is ufed 
 only when fomething is to be diftilled in a veflel of 
 this fafhion , and then the hole at its bottom ferves 
 for a paflage to the neck of the retort. This dome 
 fhould have an ear or handle, for the conveniency 
 of putting it on and taking it off with eafe. 
 
 Of Lutes. 
 
 CHYMICAL veflels, efpecially fuch as are made of 
 glafs, and the earthen veflels commonly called ftone- 
 ware, are very fubject to break when expofed to 
 fudden heat or cold , whence it comes that they 
 often crack when they begin to heat, and alfo when 
 being very hot they happen to be cooled, either by 
 frefh coals thrown into the furnace, or by the accefs 
 of cold air. There is no way to prevent the former 
 of thefe accidents, but by taking the pains to warm 
 your vefifel very flowly, and by almoft inienfible de- 
 grees. The fecond may be avoided by coating the 
 body of the veffel with a pafte or lute, which be- 
 ing dried will defend it againft the attacks of cold. 
 
 The fitteft duff for coating veflels is a compofi- 
 tion of fat earth, Windier-loam, fine land, filings of 
 iron, or powdered glafs, and chopped cow's hair, 
 mixed and made into a pafte with water. This lute 
 ferves alfo to defend glafs vefiels againft the vio- 
 lence of the fire, and to prevent their melting eafily. 
 
 In almoft all diftillationsitisof great confequence, 
 as hath been faid, that the neck of the diftilling vef- 
 fel be exactly joined with that of the receiver into 
 O 3 which
 
 ELEMENTS of the 
 
 which it is introduced, in order to prevent the va- 
 pours from efcaping into the air and fo being loft : 
 and this junction is effected by means of a lute. 
 
 A few flips of paper applied round the neck of 
 the veflels with common fize will be fufficient to 
 keep in fuch vapours as are aqueous, or not very 
 fpirituous. 
 
 If the vapours are more acrid, or more fpiri- 
 tuous, recourfe may be had to flips of bladder 
 long tteeped in water, which containing a fort of 
 natural glue clofe the junctures of the veflels very 
 well. 
 
 If it be required to confine vapours of a ftill more 
 penetrating nature, it will be proper toemploy a lute 
 that quickly grows very hard; particularly a pafte 
 made with quick-lime and any fort of gelly, whether 
 vegetable or animal ; fuch as the white of an egg, 
 ftiff fize, &c. This is an excellent Jute and not 
 cafily penetrated. It is alfo ufed to (top any cracks 
 or f raft u res that happen to glafs veflels. But it is 
 not capable of rcfifting the v?pours of mineral acid 
 fpirits, efpecially when they are ftrongand fmoking: 
 for that purpole it is neceflary to incorporate the 
 other ingredients thoroughly with fat earth foftened 
 with water; and even then it frequently happens 
 that this lute is penetrated by acid vapours, efpeci- 
 ally thofe of the fpirit of fait, which of all others 
 are confined with the greateft difficulty. 
 
 In fuch cafes its place may be fupplied with an- 
 other, which is called Fat Lute, becaufe it is actu- 
 ally worked up with fat liquors. This lute is com- 
 pofed of a very fine cretaceous earth, called tobacco- 
 pipe clay, moiftened with equal parts of the drying 
 oil of lint-feed, and a varnifh made of amber 
 and gum copal. It muft have the confidence of a 
 itiff pafte. \Vhen the joints of the veflels are clofed 
 up with this lute, they may, for greater fccurity, 
 
 M
 
 THEORY of CHYMISTRY. 
 
 be covered over with flips of linen fmeared with 
 the lute made of quick-lime and the white of an 
 
 egg- 
 
 Chymical veflels are liable to be broken in an 
 operation by other caufes befides the fudden appli- 
 cation of heat or cold. It frequently happens that 
 the vapours of the matters expofed to the action of 
 fire rum out with fuch impetuofity, and are fo 
 elaflic, that finding no pafiage through the lute 
 with which the joints of the veflels are clofed, they 
 burft the veflels themfelves, fometimes with explo- 
 fion and danger to the operator. 
 
 To prevent this inconvenience, it is necefTary 
 that in every receiver there be a fmall hole, which 
 being flopped only with a little lute may eafily be 
 opened and fhut again as occaflon requires. It 
 ferves for a vent-hole to let out the vapours, when 
 the receiver begins to be too much crowded with 
 them. Nothing but practice can teach the artift 
 when it is requifite to open this vent. If he hits 
 the proper time, the vapours commonly rum out 
 with rapidity, and a considerable hifling noife , and 
 the vent mould be (lopped again as foon as the 
 hitting begins to grow faint. The lute employed 
 to flop this fmall hole ought always to be kept fo 
 ductile, that by taking the figure of the hole exactly 
 it may entirely flop it. Befides, if it mould harden 
 upon the glafs, it would flick fo faft that it would 
 be very difficult to remove it without breaking the 
 vefiel. This danger is eafily avoided by making 
 ufe of the fat lute, which continues pliant for a 
 long time, when it is not expofed to an exceflive 
 heat. 
 
 This way of flopping the vent-hole of the re- 
 ceiver has yet another advantage : for if the hole 
 be of a proper width, as a line and half, or two 
 lines, in diameter, then when the vapours are ac- 
 cumulated in too great a quantity, and begin to 
 
 O 4
 
 2oo ELEMENTS, 
 
 make a great effort againft the fides of the receiver," 
 they pufh up the ftopple, force it out, and make 
 their way through the vent-hole : fo that by this 
 means the breaking of the vefiels may always be 
 certainly prevented. But great care mufl be taken 
 that the vapours be not fuffered to efcape in this 
 manner, except when abfolute necefiity requires it ; 
 for it is generally the very ftrongeft and moft fubtile 
 part of a liquor which is thus diflipated and loft. 
 
 Heat being the chief caufe that puts the elafticity 
 of the vapours in action, and prevents their con- 
 denfing into a liquor, it is of great confequence in 
 diftillation that the receiver be kept as cool as 
 poffible. With this view a thick plank mould be 
 placed between the receiver and the body of the 
 furnace, to intercept the heat of the latter, and 
 prevent its reaching the former. As the vapours 
 themfelves rile very hot from the diftilling veflel, 
 they foon communicate their heat to the receiver, 
 and efpecially to its upper part, againft which they 
 ftrike firft. For this reafon it is proper that linen 
 cloths dipt in very cold water be laid over the re- 
 ceiver, and frequently fhifted. By this means the 
 vapours will be confiderably cooled, their elafticity 
 Weakened, and their condenfation promoted. 
 
 By what hath been faid in this firft part, con- 
 cerning the properties of the principal agents in 
 Chymiftry, the conftruction of the moft neceflary 
 veflels and furnaces, and the manner of ufing them, 
 we are fufficiently prepared for proceeding directly 
 to the operations, without being obliged to make 
 frequent and long Hops, in order to give the ne- 
 ceflary explanations on thofe heads. 
 
 Neverthelefs we mall take every proper occafion 
 to extend the theory here laid down, and to im* 
 prove it by the addition of feveral particulars, 
 which will find their places in our Treatife of 
 Chymical Operations. 
 
 ELE-
 
 ELEMENTS 
 
 PRACTlCEofCHYMISTRYj 
 
 WHEREIN 
 
 The Fundamental Operations are de- 
 fcribed, and illuftrated by Obferva- 
 tions on each Procefs,
 
 ELEMENTS 
 
 O F T H E 
 
 PRACTICE of CHYMISTRY. 
 
 ^^^^^^^^^fa 
 
 INTRODUCTION. 
 
 AS the Elements of the Theory of Chymiftry, 
 delivered in the former part of this work* 
 were intended for the ufe of perfons fup- 
 pofed to be altogether unacquainted with the art, 
 they could not properly admit of any thing more 
 than fundamental principles, fo difpofed as conftantly 
 to lead from the fimple to the compound, from 
 things known to things unknown : for which reafon 
 I could not therein obferve the ufual order of Chy- 
 mical Decompofition, which is not fufceptible of 
 fuch a method. I therefore fuppofed all the analy- 
 fes made, and bodies reduced to their fimpleft prin- 
 ciples i to the end that, by obferving the chief pro- 
 perties of thofe primary elements, we might be en- 
 abled to trace them through their feveral combina- 
 tions, and to.form fome fort of judgment a priori 
 of the qualities of fuch compounds as may refult 
 from their junctions. 
 
 But this latter part is of a different nature. It is 
 a Practical Treatife, intended to contain the man- 
 ner of performing the principal Operations of Chy- 
 miftry ; the operations which ferve as ftandards for 
 regulating all the reft, and which confirm the fun- 
 damental truths laid down in the Theory. 
 
 As
 
 204 ELEMENTS of tie 
 
 As thefe operations confift almoft wholly of ana- 
 lyfes and decompofitions, there can be no doubt 
 concerning the order proper to be obferved in giv- 
 ing an account of them : it evidently coincides with 
 that of the analyfis itfelf. 
 
 But as all bodies, which are the fubjefts of Chy- 
 mical operations, are divided by nature into three 
 claffes or kingdoms, the mineral, the vegetable, 
 and the animal, the analyfis thereof may naturally 
 be divided into three branches : fome difference may 
 alio arife from the different order in which thefc 
 three may be treated of. 
 
 As the reafons afiigned for beginning with one 
 kingdom rather than with another have never been 
 thoroughly canvafied, and may perhaps fcem e- 
 qually good when viewed in a particular light, Chy- 
 mical writers differ in their opinions on this point. 
 For my part, without entering into a difcufiion of 
 the motives which have determined others to follow 
 a different order, I mail only produce the reafons 
 that led me to begin with the mineral kingdom, 
 to examine the vegetable in the fecond place, and 
 to conclude with the animal. 
 
 Firft then, feeing vegetables draw their nourim- 
 me nt from minerals, and animals derive theirs from 
 vegetables, the bodies which conftitute thefe three 
 kingdoms item to be generated the one by the other, 
 in a manner that determines their natural rank. 
 
 Secondly, this difpofition procures us the advan- 
 tage of tracing the principles, from their fource in 
 the mineral kingdom, down to the laft combinations 
 into which they are capable of entering, that is, in- 
 to animal matters -, and of obierving the fuccefiive 
 alterations they undergo in patting out of one king- 
 dom into another. 
 
 Thirdly and laftly, I look upon the analyfis of 
 minerals to be the eafieft of all ; not only becatife 
 they confift of fewer principles than vegetables and 
 animals, but alfobecaufealmoft all of them are capable 
 
 f
 
 PR ACTICE of CHYM ISTRY. 20$ 
 
 of enduring the moll violentaction of fire, when that 
 is neceffary to their decomposition, without any con- 
 fiderable change ordiminution of their principles, to 
 which thofe of other fubftances are frequently liable. 
 
 Befides, I am not fingular in this diftribution of 
 the three claflfes of bodies, which are the fubjeftsof 
 the chymical analyfis : as it is the moft natural, it 
 has been adopted by feveral authors, or rather by 
 moft who have publifhed Treatifes of Chymiftry. 
 But there is fomething peculiarly my own in the 
 manner wherein I have treated the analyfis of each 
 kingdom. In the mineral kingdom, for inftance, 
 will be found a confiderable number of operations 
 not to be met with in other Treatifes of Chymiftry; 
 the authors having probably confidered them as 
 ufelefs, or in fome meafure foreign, to the purpofe 
 of Elementary Books, and as conftituting together 
 a diftinft art. I mean the procefies for extracting 
 faline and metallic fubftances from the minerals 
 containing them. 
 
 Yet, if it be confidered that falts, metals, and 
 femi-metals are far from being produced by nature 
 in a ftate of perfection, or in that degree of purity, 
 which they are commonly fuppofed to have when 
 they are firft treated of in Books of Chymiftry; but 
 that, on the contrary, thefe fubftances are originally 
 blended with each other, and adulterated with mix- 
 tures of heterogeneous matters, wherewith they 
 form compound minerals ; I imagine it will be al- 
 lowed that the operations by which thefe minerals 
 are decompofed, in order to extract the metals, fe- 
 mi-metals, and other fimpler fubftances, efpecially 
 as they are founded on the moft curious properties of 
 thefe fubftances, are fo far from being ufelefs or fo- 
 reign to the purpofes of an Elementary Treatife, that 
 they are,on the contrary,abfolurely neceflary thereto. 
 
 After I had made thefe reflections, I could not 
 help thinking that an analyfis of minerals, which 
 ihould treat of faline and metallic fubftances, with- 
 out
 
 ao6 ELEMENTS of the 
 
 out taking any notice of the manner in which their 
 matrices muft be analyfed, in order to extract them, 
 would be no lefs defective, than a treatife of the ana- 
 lyfis of vegetables, in which Oils, eflential Salts, fixed 
 and volatile Alkalis, mould be amply treated of, 
 without faying one word of the manner of analyfing 
 the plants from which thefe feveral fubfiances are 
 obtained. I therefore thought myfelf indifpenfably 
 obliged to defcribc the manner of decompofing 
 every ore or mineral, before I attempted to treat of 
 the faline or metallic fubftance which it yields. 
 
 For example : as the Vitriolic Acid, with the con- 
 fideration of which I begin my Mineral Analyfis, is 
 originally contained in Vitriol, Sulphur, and Alum ; 
 and as thefe fubftances againderi ve their origin from 
 the fulphureous and ferruginous Pyrites, the firft 
 operations I defcribe under this head are the pro- 
 cefTes for decompofing the Pyrites in order toextradt 
 its Vitriol, Sulphur, and Alum. I then proceed to 
 the particular analyfis of each of thefe lubrtances, 
 with a view to extract their Vitriolic Acid , and af- 
 terwards deliver, in theirorder, the other operations 
 ufually performed on this Acid. Thus it appears 
 that this faline fubftance occafions my defcribing the 
 analyfes of the Pyrites, Vitriol, Sulphur, and Alum. 
 The whole of the Treatife on Minerals proceeds on 
 the fame plan. 
 
 The operations by which we decompofe ores and 
 minerals are of two forts: thofe employed in work- 
 ing by the great, and thofe for trying in fmall the 
 yield of any ore. Thefe two manners of operating 
 are fometimes a little different , yet in the main they 
 are the fame, becaufe they are founded on the fame 
 principles, and produce the fame effects. 
 
 As my chief defign was to defcribe the operations 
 that may be conveniently performed in a labora- 
 tory, I have preferred the procefies for fmall aflays; 
 cfpccially as they are ufually performed with more 
 
 care
 
 PRACTICE ^CHYMISTRY. 207 
 
 care and accuracy than the operations in great 
 works : and here I muft acknowledge that I am 
 obliged to M. Cramer's Docimqfia^ or Art of Afiay- 
 ing, for all the operations of this kind in my analyfis 
 of minerals. As M. Hellot's work on that fubject: 
 did not appear till after I had finifhed this, M. 
 Cramer's Docimajia^ in which found Theory is joined 
 with accurate practice, was the beft book of the 
 kind I could at that time confult. I therefore pre- 
 ferred it to all others ; and as I have not quoted it 
 in my analyfis of minerals, becaufe the quotations 
 would have been too frequent, let what I fay here 
 ferve for a general quotation. I have been careful 
 to name, as often as occafion required, the other 
 authors whofe proceffcs I have borrowed : it is a 
 tribute juftly due to thofe who have communicated 
 their difcoveries to the publick. 
 
 Though I have told the reader that in my analyfis 
 of minerals he will find the procefles for extracting 
 out of each the faline or metallic fubftances con- 
 tained in it, yet he muft not expect that this book 
 will inftruct him in all that it is neceflary he fhould 
 know to be able to determine, by an accurate aflay, 
 the contents of every mineral. My intention was 
 not to compofe aTreatife of AfTaying; and I have 
 taken in no more than was abfolutely neceflary to 
 make the analyfis of minerals perfectly underftood, 
 and to render it as complete as it ought to be in 
 an Elementary Treatife. I have therefore defcribed 
 only the principal operations relating thereto , the 
 operations which are fundamental, and which, as I 
 faid before, are to ferve as ftandards for the reft, 
 abftracted from fuch additional circumftances as are 
 of confequence only to the Art of Aflaying, pro- 
 perly fo called. 
 
 Such therefore as are defirous of being fully in- 
 ftructed in that Art, muft have recourfe to thofe 
 works which treat profefTedly of the fubject ; and 
 
 particu-
 
 08 ELEMENTS of the 
 
 particularly to that pubiifhed by M. Hellot: a per- 
 formance moft efteemed by fuch as are beft (killed 
 inChymiftry, and rendered fo complete by the nu- 
 merous and valuable obfervations and diicoveries 
 of the Author, that nothing better of the kind can 
 be wifhed for. I thought it proper to give thefe 
 notices in relation to my analyfis of minerals ; and 
 fhall now proceed to mew the plan of my analyfes 
 of vegetables and of animals. 
 
 Seeing all vegetable matters are fufceptible offer- 
 mentation, and when analyfed after fermentation, 
 yield principles different from thofe we obtain from 
 them before they are fermented, I have divided 
 them into two clafies , the former including vege- 
 tables in their natural ftate, before they have un- 
 dergone fewnentation ; and the tatter thofe only 
 \vhicn have been fermented. This analyfis opens 
 with the proceiks Dy which we extract from vege- 
 tables all the principles they will yield without the 
 help of fire : and then follow the operations for de- 
 compofing plants by degrees of heat, from the 
 gentleft to the moft violent, both in clofe veflels 
 and in the open air. 
 
 I have not made the fame divifion in the animal 
 kingdom, becaufe the fubftances that compole it 
 are fufceptible only of the laft degree of fermenta- 
 tion, or putrefaction i and moreover the principles 
 they yield, whether putrefied orunputrefied, are the 
 very fame, and differ only with regard to their pro- 
 portions, and the order in which they are extricated 
 during the analyfis. 
 
 I begin this analyfis with an examination of 
 the milk of animals that feed wholly on vegeta- 
 .bles , becaufe though this fubftance be elaborated 
 In the body of the animal, and by that means 
 brought nearer to the nature of animal matters, yet 
 it (till retains a great fimilitude to the vegetables 
 from which it derives its origin, and is a fort of 
 
 inter*
 
 PRACTICE of CHYMIST&Y. 269 
 
 intermediate fubftance between the vegetable and 
 animal. Then. I proceed to the analyfis of animal 
 matters properly fo called, thofe which actually make 
 a part of the animal body. I next examine the ex- 
 crementitious fubftances, that are thrown out of the 
 animal body as ftiperfluoUs and ufelefs. And theri 
 I conclude this latter part with operations on the 
 Volatile Alkali ; a faline fubftance of principal con- 
 fideration in the decompofition of animal matters. 
 Though, in the general view here given of the 
 order obferved in this Treatife of Practical Chymif- 
 try, I have mentioned only fuchprocefies as fervefor 
 analyfing, bodies, yet I have alfo inferted fome other 
 operations of different kinds. The book would be 
 very defective if it contained no more : for the de- 
 fign of Chymiftry is not only to analyfe the mixts 
 produced by nature, in order to obtain the fim- 
 pleft fubftances of which they are compofed, but 
 moreover to difcover by fundry experiments the 
 properties of thofe elementary principles, and to re- 
 combine them in various manners, either with each 
 other, or with different bodies, fo as to reproduce 
 the original mixts with all their properties, or even 
 form new compounds which never exifted in nature. 
 In this book therefore the reader will find procefles 
 for combining and recompounding, as well as for 
 refolving and decompofing bodies. I have placed 
 them next to the procefles for decompofition, tak- 
 ing all pofllble care not to interrupt their order, or 
 break the connection between them. 
 
 VOL, I,
 
 ELEMENTS 
 
 O F T H E 
 
 PRACTICE of CHYMISTR Y. 
 
 PART I. 
 OF MINERALS. 
 
 SECTION I. 
 
 Operations performed on Saline Mineral Subftances. 
 
 CHAP. I. 
 Of the VITRIOLIC ACID. 
 
 PROCES.S I. 
 
 To extraff Vitriol from tbe Pyrites. 
 
 TAKE any quantity you pleafe of Iron-Py- 
 rites ; leave them for fome time expofed to 
 the air , they will crack, fplit, lofe their 
 brightnefs, and fall into- powder. Put this powder in- 
 to a glafs cucurbit, and pour upon it twice its weight 
 of hot water; ftir the whole with a (lick, and the 
 liquor will grow turbid. PoUr it, while it is yet 
 warm, into a glafs funnel lined with brown filtering 
 paper-, and having placed your funnel over another 
 glafs cucurbit, let the liquor drain into it. Pour 
 
 more
 
 211 
 
 tnore hot water oh the powdered Pyrites, filter as 
 before, and fo go on, every time lefiening the quan- 
 tity of water, till that which comes off the Pyrites 
 appears to have no aftringent vitriolic tafte. 
 
 Put all thefe waters together into a glafs vefiel 
 that widens upwards , fet it on a fand bath, and 
 heat the liquor till a confiderable fmoke arifes; but 
 take care not to make it boil. Continue the fame 
 degree of fire till the furface of the liquor begins 
 to look dim, as if fome duft had fallen into it 5 
 then ceafe evaporating, and remove the veflel into 
 a cool place : in thefpace of four-and-twenty hours 
 will be formed therein a 'quantity of cryftals, of a 
 green colour and a rhomboidal figure : thefe are 
 Vitriol of Mars, or Copperas. Decant the remain- 
 ing liquor; add thereto twice its weight of water; 
 filter, evaporate, and cryftallize as before ; repeat 
 thefe operations till the liquor will yield no more 
 cryftals, and keep by themfelves the cryftals ob- 
 rained at each cryftallization. 
 
 O B S E R VA r 1 N S. 
 
 THE Pyrites are minerals which, by their weight 
 and mining colours, frequently impofe on fuch as 
 are not well acquainted with ores. At firft fight 
 they may be taken for very rich ones , and yet they 
 confiftenlyofafmallquaritityofmetal combined with 
 much fulphur or arfenic, and fometimes with both. 
 
 They ftrike fire with a fteel as flints do, and emit 
 a fulphureous fmell : fo that they may be known by 
 this extemporaneous proof. The metal moft com- 
 monly and moft abundantly found in the Pyrites is 
 iron ; the quantity whereof fometimes equals, or 
 even exceeds, that of the fulphur. Befides metal- 
 lic and fulphureous matters, the Pyrites contain alfo 
 fome unmetallic earth. 
 
 There are feveral forts of Pyrites : fome of them 
 contain only iron and arfenic, They have not all 
 the property of efflorefcing fpontaneoufly in the air 
 
 P a
 
 212 ELEMENTS 0/* the 
 
 and turning into vitriol: none do fo but fuch as 
 confift only of iron and fulphur, or at leaft contain 
 but a very fmall portion of copper, or of arfenic : 
 and even amongft thofe that are compofed of iron 
 and fulphur alone, there are fome that will continue 
 for years together expofed to the air without fhoot- 
 ing, and indeed without fufFering the leaft fenfible 
 alteration. 
 
 The efflorefcence of the Iron-Pyrites, and the 
 changes they undergo, are phenomena well worth 
 our notice. They depend on the fingular pro- 
 perty which iron pofiefles of decompofing fulphur 
 by the help of moifture. If very fine iron-filings 
 be accurately mingled with flowers of fulphur, this 
 mixture, being moiitened with water, grows very- 
 hot, fwells up, emits fulphureous vapours, and even 
 takes fire : what remains is found converted into 
 Vitriol of Mars. On this occafion, therefore, the 
 fulphur is decompofed ; its inflammable part is dif- 
 fipated or confumed; its acid combines with the 
 iron, and a Vitriol arifes from that conjunction. 
 
 This is the very cafe with the Pyrites that confift 
 only of iron and fulphur-, yet fome of them, as 
 we faid before, do not efflorefce fpontaneoufly and 
 turn to Vitriol. The reafon probably is that, in fuch 
 minerals, the particles of iron and fulphur are not 
 intimately mixed together, but feparated by fome 
 earthy particles. 
 
 In order to procure Vitriol from Pyrites of this 
 kind, they muft be for fome time expofed to the 
 action of fire, which by confuming part of their 
 fulphur, and rendering their texture lefs compact, 
 makes way for the air and moifture, to which they 
 muft be afterwards expofed, to penetrate their fub- 
 ftance, and produce in them the changes with 
 which thofe others are affected that germinate fpon- 
 taneoufly. 
 
 The Pyrites which contain copper and arfenic, 
 and for that reafon do not efflorefce, muft likewiie 
 
 under-
 
 PRACTICE ^CHYMISTRY. 213 
 
 undergo the action of fire ; which befides the ef- 
 fects it produces on Pyrites that confift of iron and 
 fulphur only, diflipates alfo the greateft part of the 
 arfenic. Thefe Pyrites being firft roafted, and then 
 expofed to the air for a year or two, do alto yield 
 Vitriol -, but then it is not a pure Vitriol of Iron, 
 but is combined with a portion of blue Vitriol, the 
 bafis of which is Copper. 
 
 Sometimes alfo there is Alum in the vitriolic wa- 
 ters drawn off the Pyrites. It was on account of 
 this mixture of different falts that we recommended 
 the keeping apart the cryftals obtained from each 
 different cryftallization: for by this means they may 
 be examined feparately, and the fpecies to which 
 they belong difcovered. 
 
 When Vitriol of iron is adulterated with a mix- 
 ture of the Vitriol of copper only, it is eafy to pu- 
 rify it and bring it to be entirely martial, by diffblv- 
 ing it in water, and fetting plates of iron in the fo- 
 lution : for iron having a greater affinity than cop- 
 per with the vitriolic acid, feparates the latter from 
 it, and afluming its place produces a pure Vitriol 
 of Mars. 
 
 Jn large works for extracting Vitriol from the 
 Pyrites they proceed thus. They collect a great 
 quantity of Pyrites on a piece of ground expofed to 
 the air, and pile them up in heaps of about three 
 feet high. There they leave them expofed to the 
 action of the air, fun, and rain, for three years 
 together; taking care to turn them every fix 
 months, in order to facilitate the efflorefcence of 
 thofe which at firft lay undermoft. The rain-water 
 which has walhed thofe Pyrites is conveyed by pro- 
 per channels into a ciftern ; and when a fufficient 
 quantity thereof is gathered, they evaporate it to a 
 pellicle in large leaden boilers, having firft put in- 
 to it a quantity of iron, fome part of which is dif- 
 folved by the liquor, becaufe it contains a vitriolic 
 acid that is not fully faturated therewith. When it 
 
 P 3 i*
 
 214 ELEMENTS 
 
 is fufficiently evaporated, they draw it off into large 
 leaden or wooden coolers, and there leave it to 
 fhoot into cryftals. In thefe laft vefiels feveral 
 fticks are placed, crofting each other in all manner 
 of directions, in order to multiply the furfaces on 
 which the cryftals may faften. 
 
 The Pyrites are not the only minerals from which 
 Vitriol may be procured. All the ores of iron and 
 copper that contain fulphur may allo be made to 
 yield green or blue Vitriol, according to the nature 
 of each, by torrefying them, and leaving them long 
 cxpofed to the air : but this ufe is feldom made ot 
 them, as there is more profit to be got by extract- 
 ing the metals they contain. Befides, it is eafier to 
 obtain Vitriol from the Pyrites, than from thole 
 other mineral Jubilances. 
 
 PROCESS II. 
 
 To extraft Sulphur from the Pyrites* and other ful- 
 fhureoits Minerals. 
 
 REDUCE to a coarfe powder any quantity of 
 yellow Pyrites, or other Mineral containing 
 Sulphur. Put this powder into an earthen or glais 
 retort, having a long wide neck, and fo large a 
 body that the matter may fill but two thirds of it. 
 Set the retort in a fand-bath fixed over a reverbe- 
 rating furnace : fit to it a receiver half full of water, 
 and fo placed that the nofe of the retort may be 
 about an inch under the water : give a gradual 
 fire, taking care you do not make it fo ftrong as 
 to melt the matter. Keep the retort moderately red 
 for one hour, or an hour and half, and then let the 
 veflels cool. 
 
 Almoft all the Sulphur feparated by this opera- 
 tion from its matrix will be found at the extremity 
 of the neck of the retort, being fixed there by 
 5 the
 
 PR ACTICE of CHYMISTRY. 
 
 the water. You may get it out either by melting 
 it with fueh a gentle heat as will not fet it on fire, 
 or by breaking the neck of the retort. 
 
 OBSERVATIONS. 
 
 OF all minerals the Pyrites contain the moft Sul- 
 phur; thofe efpecially which have the colour of fine 
 brafs, a regular form, fuch as round, cubical, hexa- 
 gonal, and being broken prefent a number of min- 
 ing needles, all radiating, as it wrre, from a center. 
 
 A very moderate heat is fufficient to feparate the 
 Sulphur they contain. We directed that the retort 
 employed mould have a long and wide neck, with 
 a view to procure a free paflage for the Sulphur : the 
 water fet in the receiver detains the Sulphur, fixes it, 
 and prevents it from flying off; fo that it is unnecef- 
 fary to clofe the joints of the vefTels. But it is pro- 
 per to take notice that when ever you ufe an appa- 
 ratus for diftilling, which requires the beak of the 
 retort to be under water, it is of very great confe- 
 quence that the fire be centtantly fo regulated that 
 the retort may not cool in the leaft ; for in that cafe, 
 as the rarefied air contained therein would be con- 
 denfed, the water in the receiver would rife into 
 the retort and break it. 
 
 If in diftilling Sulphur, according to the prefent 
 procefs, the matter contained in the retort mould 
 happen to melt, the operation would be thereby 
 considerably protracted, and it would require a 
 great deal more time to extract all the Sulphur ; 
 becaufe all evaporation is from the furface only, 
 and the matter, while it remains in a coarfe pow- 
 der, prefents a much more extenfive furface than 
 when it is melted. 
 
 This remark holds with regard to all other diftil- 
 lations. Any quantity of liquor, fet to diftil in its 
 fluid (late, will take much more time to rife in va- 
 pours, and pafs from the retort into the receiver, 
 P 4 than
 
 ai6 E L E M E M T s of the 
 
 *J 
 
 than if it be incorporated with fome folid body re- 
 duced to minute parts, fo that the whole mall make 
 a moift powder; and this though the very fame de- 
 gree of fire be applied in both cafes. 
 
 If the matter from which it is propofed to extract 
 Sulphur be fuch as will melt with the degree of fire 
 necefiary to this operation; that is, with a heat which 
 will make the retort but faintly red, it muft be mix- 
 ed with fome fubftance that is not fo fufible. Very 
 pure coarle land, or clean gravel, may be ufed with 
 fuccefs : but abforbent earths are altogether impro- 
 per for this purpofe, becaufe they will unite with 
 the Sulphur, 
 
 The fulphureous minerals which are mod apt to 
 fufe are the cupreous Pyrites, or yellow copper 
 ores: common lead ores are alfo very fufible. 
 
 The Pyrites are by this operation deprived of al- 
 moft all the Sulphur they contain ; and confequently 
 little is left behind, but the particles of iron and 
 copper, together with a portion of unmetallic earth, 
 which we fhall fhew how to feparate from thefe me- 
 tals, when we come to treat of them. I fay that by 
 this operation the Pyrites are deprived of almoft all, 
 and not entirely of all their Sulphur; becaufe, this 
 feparation being made in clofe veflels only, there 
 always remains a certain quantity of Sulphur, which 
 adheres fo obftinately to the metals, that it would 
 be almoft impoflible to get it all out, even though 
 a much ftronger fire than that directed in the pro- 
 cefs were applied for this purpofe, and though choice 
 had been, as it ought to be, made of fuch Pyrites, 
 or other fulphureous Minerals, as part moft eafily 
 with their Sulphur. Nothing but a very ftrong 
 fire in the open air is capable of carrying it wholly 
 off, or confuming it entirely. 
 
 In feveral places are found great quantities of na- 
 tive Sulphur. The Volcanos abound with it, and 
 people gather it at the foot pf thofe burning moun- 
 tains.
 
 PRACTICE of CHYMISTRY. 217 
 
 tains. Several fprings of mineral waters alfo yield 
 Sulphur, and it is fometimes found fublimed to 
 the vaulted roofs of certain wells, and among 
 others in one at Aix-la-Chapelle. 
 
 The Germans and Italians have large works, 
 for extracting Sulphur in quantities out of Py- 
 rites, and other minerals which abound therewith. 
 The procefs they work by is the fame with that 
 here delivered -, but with this difference only, that 
 Sulphur being but of fmall value they do not ufe 
 fo many precautions. They content themfelves 
 with putting the fulphureous minerals into large 
 crucibles, or rather earthen cucurbits, which they 
 place in the furnace in fuch a manner that, when 
 the fulphureous part melts, it runs into veflels fill- 
 ed with water, and is thereby fixed. 
 
 The Sulphur obtained, either by diftillation or 
 by fimple fufion, is not always pure. 
 
 When it is obtained by diftillation, if the matters 
 from which you extract it contain moreover fome 
 other minerals of nearly the fame volatility, fuch, 
 for inftance, as Arfenic, or Mercury, thefe mine- 
 rals will come over with it. This is eafily perceiv- 
 ed : for pure fublimed Sulphur is always of a beau- 
 tiful yellow, inclining to a lemon colour. If it 
 look red, or have a reddifh caft, it is a fign that 
 fome Arfenic hath rifen along with it. 
 
 Mercury fublimed with Sulphur likewife gives it 
 a red colour ; but Sulphur is very feldom adulte- 
 rated with this metallic fubftance : for Arfenic is 
 frequently found combined with the Pyrites, and 
 other fulphureous minerals , whereas on the contrary 
 we very rarely meet with any Mercury in them. 
 
 But if Mercury mould happen to rife with the 
 Sulphur in diftillation, it may be difcovered by ex- 
 amining the fublimate -, which, in that cafe, will 
 have the properties of Cinabar : on being broken its 
 infide will appear to confift of needles adhering la- 
 terally
 
 2 1 8 ELEMENTS of the 
 
 terally to each other ; its weight will be very con- 
 fiderable ; and laftly, the great heat of the place 
 where it is collected will furnifh another mark to 
 know it by ; for as Cinabar is lefs volatile than 
 Arfenic or Sulphur, it fattens on places too hot for 
 either Sulphur or Arfenic to bear. 
 
 Sulphur may alfo be adulterated with fuch fixed 
 matters, either metallic or earthy, as it may have 
 carried up along with it in the diftillation, or as may 
 have been fublimed by the Arfenic, which has a (till 
 greater power than Sulphurtovolatilize fixed bodies. 
 
 If you defire to free the Sulphur from mod ot 
 thefe heterogeneous matters, it muft be put into 
 an earthen cucurbit, and let in a fand bath. To 
 the cucurbit muft be fitted one or more aludeis, 
 and fuch a degree of heat applied as (hall but jutt 
 melt the Sulphur-, which is much lefs than that 
 necefiary to feparate the Sulphur from its matrix. 
 As loon as the Sulphur is melted it will fublime in 
 lemon-coloured flowers, that will (tick to the in- 
 fides of the aludeis. 
 
 When nothing more appears to rife with this de- 
 gree of heat, the vcfiels muft be fuffered to cool. 
 At the bottom of the cucurbit will be found a ful- 
 phureous mafs, containing the greateft part of the 
 adventitious matters that were mixed with the Sul- 
 phur, and more or lefs red or dark-coloured, ac- 
 cording to the nature of thofe matters. 
 
 When we come to treat of Arfenic and Mercury, 
 we mall give the methods of feparating Sulphur 
 entirely from thofe metallic fubftances. - 
 
 PROCESS III. 
 
 To extraft 4lum from aluminous Minerals. 
 
 TAKE fuch materials as are known or fufpe&ed 
 to contain Alum. Expofe them to the air, 
 that they may efflorefce. If they remain there a 
 
 year
 
 PRACTICE of CHYMISTRY. 219 
 
 year without any fenfible change, cakine them, and 
 then leave them expofed to the air, till a bit thereof 
 being put on the tongue imparts an aftringent alu- 
 minous tafte. 
 
 When your matters are thus prepared, put 
 them into a leaden or glafs veficl , pour upon them 
 thrice their weight of. hot water ; boil the liquor \ 
 filter it; and repeat thefe operations till the earth 
 be fo edulcorated that the water which comes off it 
 hath no tafte. Mix all thefe folutions together, 
 and let them (land four-and-twenty hours, that the 
 grofs and earthy parts may fettle to the bottom ; 
 or elfe filter the liquor: then evaporate till it will 
 bear a new-laid egg. Now let it cool, and fland 
 quiet foil r-and- twenty hours: in that time fome 
 cryftals will (hoot, which are moft commonly vitri- 
 olic ; for Alum is rarely obtained by the firft cry- 
 ftallization. Remove thefe vitriolic, cryftals: if 
 any cryftals of Alum be found amongft them, 
 thefe muft be diflblved anew,, and fet to cryftallize 
 a fecond time in order to their purification , becaufe. 
 they partake of the nature as well as of the colour 
 of vitriol. By this method extract all. the Alum 
 that the liquor will yield. 
 
 If you get no cryftals of Alum by this means, 
 boil your liquor again, and add to it a twentieth 
 part of its weight of a ftrong alkaline lixivium, or 
 a third part of its weight of putrefied urine, or a 
 fmall quantity of quick-lime. Experience and re- 
 peated trials muft teach you which of thefe. three 
 fubftances is to be preferred, according to the par- 
 ticular nature of the. mineral on which you are to 
 operate. Keep you,r liquor boiling, and if there be 
 any Alum in in, there will appear a white precipi- 
 tate : in that cafe let it cool and fettle. When the 
 white precipitate is entirely fallen, decant the clear, 
 and leave tne cryftals of Alum to fhoot at leifure, 
 
 till
 
 420 ELEMENTS of the 
 
 till the liquor will yield no more : it will then be 
 exceeding thick. 
 
 OBSERVAriONS. 
 
 ALUM is obtained from feveral forts of Minerals, 
 In fome parts of Italy, and in fundry other places, 
 it efflorelces naturally on the furface of the earth. 
 There it is fvvept together with brooms, and thrown 
 into pits full of water. This water is impregnated 
 therewith till it can difiblve no more. Then it is 
 filtered, and fet to evaporate in large leaden vefiels , 
 and when it is fufficiently evaporated, and ready to 
 fhoot into cryftals, it is drawn off into wooden cool- 
 ers, and there left for the fait to cryftallize. 
 
 In aluminous foils there are often found fprings 
 ftrongly impregnated with Alum , fo that to obtain 
 it the water need only be evaporated. 
 
 In the country about Rome there is a very hard 
 {tone, which is hewn out of the quarry juft like 
 other ftones for building : this ftone yields a great 
 deal of Alum. In order to extract it, the ftones 
 are calcined for twelve or fourteen hours ; after 
 which they are expofed to the air in heaps, and 
 carefully watered three or four times a day for forty 
 days together. In that time they begin to erHorefce, 
 and to throw out a reddifh matter on their furface. 
 Then they are boiled in water, which difiblves all 
 the Alum they contain, and being duly evaporated 
 gives it back in cryftals. This is the Alum called 
 Roman Alum. 
 
 Several forts of Pyrites alfo yield a great deal of 
 Alum. The Englilh have a ftone of this kind, 
 which in colour is very like a (late. This ftone 
 contains much Sulphur, which they get rid of by 
 roafting it. After this they fteep the calcined ftone 
 in water, which diflblves the Alum it contains, and 
 to this folution they add a certain quantity of a lye 
 made of the afhes of lea- weeds. 
 
 The
 
 PR ACTICE of CH YMI STR Y. 221 
 
 The Swedes have a Pyrites of a bright, golden 
 colour, variegated with filver fpots, from which 
 they procure Sulphur, Vitriol, and Alum. Thty 
 feparate from it the Sulphur and the Vitriol by the 
 methods above preicribed. When the liquor which 
 hath yielded Vitriol is become thick, and no more 
 vitriolic cryftals moot in it, they add an eighth part 
 of its weight of putrefied urine, mixed with a lye 
 made of the aflies of green wood. Upon this 
 there appears and falls to the bottom a copious red 
 fediment. They decant the liquor from this preci- 
 pitate, and when it is duly evaporated find it fhooc 
 into beautiful cryftals of Alum. 
 
 What hath been faid, concerning the feveral ma- 
 trices from which Alum is obtained, fufficiently 
 fhews that it is feldom folitary in the waters with 
 which aluminous fubjects have been lixiviated. It is 
 almoft always accompanied with a certain quantity 
 of Vitriol, or other faline mineral matters, which 
 obftrufb its cryftallization, and prevent its being 
 pure. 'Tis with a view to free it from thefe mat- 
 ters, that the waters impregnated with Alum are 
 mixed with a certain quantity of the lye of fome 
 fixed Alkali, or with putrefied urine, which con- 
 tains much volatile Alkali. Thefe Alkalis have the 
 property of decompounding all the Neutral falts 
 which have for their bafis either an abforbcnt earth 
 or a metallic fubftance ; and fuch as have a metallic 
 fubftance for their bafis more readily than thofe 
 whofe bafis is an earth. Confequently, if they are 
 mixed with a liquor in which both thefe forts of falts 
 are dhTolved,they muft decompound that fort whofe 
 bafis is metallic fooner than the other whofe bafis is 
 an earth. This is what comes to pafs in a folution 
 of Alum and Vitriol. The metallic part of the 
 latter is feparated from its acid by the Alkalis when 
 mixed with that folution ; and 'tis this metallic 
 part, which is generally iron, that appears in the 
 form of a reddilh precipitate, as above-mentioned. 
 
 But
 
 222 ELEMENTS of the 
 
 Butbecaufe Alkalis decompound alfo thofe Neu- 
 tral faks which have an earth for their bafts, care 
 muft be taken that too much thereof be not added ; 
 elfe what you put in, more than is neccfHiry to de- 
 compound the vitriolic faks in your liquor, will at- 
 tack the Alum, and decompound it like wife. 
 
 The Alkali made ufe of to promote the cryftalli- 
 zation of the Alum joins with the Vitriolic Acid, 
 which had diflblved the fubftances now precipitat- 
 ed, and therewith forms different Neutral fairs ac- 
 cording to its panicular nature. If the Alkali be a 
 lixivium of common wood-afhes, the Neutral falc 
 will be a vitriolated Tartar; if a lixivium of the 
 afhes of a maritime plant like Soda, the Neutral 
 fait will be a Glauber's fait ; if putrefied urine, the 
 Neutral Hilt will be a vitriolic Ammoniacal fait. 
 Some of thefe ialts incorporate with the Alum, 
 which in large works cryftallizes in vaft lumps : and 
 hence it comes that fome forts of Alum when mixed 
 with a fixed Alkali fmell like a volatile Alkali. 
 
 The cryftals of Alum are octaedral, that is, they 
 are folicls with eight fides. Thefe octaedral folids 
 are triangular pyramids, having their angles cut 
 away, fo that four of their furtaces are hexagons, 
 and the other four triangles. 
 
 Sulphur, Vitriol, and Alum are the three prin- 
 cipal iubje&s in which we certainly know that the 
 univerlal or Vitriolic Acid particularly refides, and 
 from which we extract it when we want to have it 
 pure. For this reaion we thought it proper, be- 
 fore we treated of the extraction of this Acid, to 
 fhew the method of feparating thofe matters them- 
 fclves from the other minerals out of which we ob- 
 tain them. 
 
 Moreover, all the other matrices, in which the 
 Vitriolic Acid is molt commonly lodged, may be 
 referred to one or other of the matters which ferver 
 as bales to thefe three minerals, 
 
 To
 
 PRACTICE O/'CHYMISTRY. 223 
 
 To Sulphur we may refer all combinations of 
 the Vitriolic Acid with an inflammable matter: 
 but we muft take care not to confound Sulphur 
 with thofe Bitumens in which the Vitriolic Acid 
 may be found : for the bafis of thofe bitumens is a 
 real Oil -, whereas the bafis of Sulphur is the pure 
 Phlogifton. Yet as Oils themfelves contain the 
 Phlogifton, which in union with the Vitriolic Acid 
 forms a true Sulphur, it follows that fuch bitumens 
 may in a certain refpect be clafied with Sulphur. 
 
 The fame is to be faid of Vitriol. The name is 
 ufually given to fuch combinations only as are form- 
 ed of the Vitriolic Acid with Iron or Copper, which 
 make the green and blue Vitriol; and to a third 
 fpecies of Vitriol, which is white, and has Zinc for 
 its bafis : but as the Vitriolic Acid may, by parti- 
 cular combinations, be united with many other 
 metallic fubftances, all fuch Metallic Salts muft be 
 referred to the clafs of Vitriols. 
 
 The fame may alfo be faid of Alum, which is 
 no other than a combination of the Vitriolic Acid 
 with a particular kind of abforbent earth ; fo that 
 all combinations of this Acid with any earth what- 
 ever may be placed in the fame clafs. 
 
 This laft clafs of mixts is the moft extenfive of 
 all that contain the Vitriolic Acid; becaufe there are 
 a vaft many earths, all differing from one another, 
 with which that Acid may be united. Alum pro- 
 perly fo called, the Gypfums, Talcs, Selenites, Boles, 
 and all the other compounds of this kind, differ 
 from each other only in their particular earths. 
 
 The different properties of thefe earthy falts de- 
 pend on the nature of their bafes. Thofe which 
 are of the aluminous kind retain much water in cryf- 
 tallizing, which makes them very foluble in water, 
 and gives them the property of acquiring readily 
 the aqueous fluor when expofed to the fire. Thofe 
 which are of the nature of the Selenites admit but 
 very little water in their cryftals, and confequently 
 
 arc
 
 224 ELEMENTS of tie 
 
 arc almoft infoluble in water ; nor does the fire give 
 them an aqueous fluor. Laftly, the Gypfums and 
 Talcs are ftill more deftitute of thefe properties. 
 The natures of the earths in thcfe feveral com- 
 pounds are hitherto but very imperfectly known, 
 and may give the Chymifts occafion for enquiries 
 equally curious and ufeful. 
 
 The Vitriolic Acid is fometimes found compli- 
 cated with a fixed alkaline bafis. This is almoft al- 
 ways the Alkali of Sea- fait; ib that the compound is 
 a Glauber's Salt. Some mineral waters are impreg- 
 nated therewith i which happens when thefe waters 
 contain Vitriol or Alum, together with Sea-falt. 
 
 From the principles laid down, in our Elements of 
 the Theory, it appears that the Vitriolic Acid hath 
 not fo great an affinity with earthy and metallic fub- 
 ftances as with fixed Alkalis ; and alfo that it is 
 ftronger than the Marine Acid, and hath a greater 
 affinity with fixed Alkalis. This being allowed, 
 the generation of native Glauber's Salts is eafily 
 accounted for. The Acid of aluminous or Vitriolic 
 falts quits the earth or the metal with which it was 
 combined, and expelling the Acid of fea-falt unites 
 with its bafis. Warmth greatly promotes thefe 
 decompofitions. 
 
 If the common foffil falt,ufually called Sal Gem, or 
 any other kind of Sea-fair, fhould happen to be near 
 a Vulcano, when it discharges flaming Sulphur, as 
 is frequently the cafe, and if this Sulphur mould 
 run among the Sea-falt, a Glauber's Salt would in- 
 ftantly be formed in that place -, becaufe when Sul- 
 phur burns, its Acid is feparated and fet at liberty. 
 
 Laftly, if aluminous or vitriolic matters, or burn- 
 ing Sulphur, fhould meet with the afhes of plants or 
 trees confumed by fire, a vitriolated Tartar would 
 be formed, becaufe thefe afhes contain a fixed Al- 
 kali of the fame nature with that of Tartar. 
 
 The Vitriolic Acid when combined with an earthy 
 
 bafis adheres ftrongly thereto j fo that the force of 
 
 f 
 fire
 
 PR ACTICE of CHYMISTR v. 225 
 
 fire is able to expel very little or none of it. There 
 is no way of feparating it from fuch a bafis, but by 
 prefenting to it an Alkaline Salt, with which it will 
 unite : nor is it ever extracted from fuch matters 
 when it is required pure. It does not adhere fo 
 firmly to metallic fubftances \ but is feparatecl from 
 them by the force of fire : fo that it may be obtained 
 from the feveral forts of Vitriol. It is ufually drawri 
 from Green Vitriol , that being the commoneft forti 
 As to Sulphur, the Phlogifton which is its bafis 
 being the fubftance wherewith the Vitriolic Acid 
 hath the greateft affinity, it would be altogether im- 
 poflible to decompofe it, and to feparate its Acid, 
 if it were not inflammable ; but by burning it the 
 Phlogifton is deftroyed, and leaves the Acid at li- 
 berty. By this means therefore it may be feparated. 
 We mall now give the procefTes for extracting the 
 Acid from Vitriol and Sulphur. 
 
 PROCESS IV. 
 
 extrafl the Vitriolic Add from Green Vitriol. 
 
 TAKE any quantity of Green Vitriol : put it 
 in an unglazed earthen veiTel, and heat ic 
 gradually. Vapours will foon begin to rife. Encreafe 
 the fire a little, and it will liquefy by means of the 
 water contained in it, and acquire what we called 
 an aqueous fluor. Continue the calcination, and it 
 will become lefs and lefs fluid, grow thick, and turn 
 of a greyifh colour. Now raife your fire, and keep 
 it up till the fait recover its iblidity, acquire an 
 orange colour, 'and begin to grow red where it im- 
 mediately touches the fides of the veffel. Then 
 take it out, and reduce it to powder. 
 
 Put the Vitriol thus calcined and pulverized into 
 a good earthern retort, of which one half at leaffc 
 
 VOL. I. C
 
 '226 ELEMENTS of the 
 
 muft remain empty. Set the retort in a reverbera- 
 tory furnace : fit thereto a large glafs receiver, and, 
 having lured the joint well, give fire by degrees. 
 You will foon fee white clouds rife into the receiver, 
 which will render it opaque, and heat it. Continue 
 the fame degree of fire till thefc clouds difappear : 
 they will be lucceeded by a liquor which will trickle 
 down the fides of the receiver in veins. Still keep 
 up the fire to the fame degree as long as thefe veins 
 Cc-r. When they begin to abate, encreafe the 
 fire, and pufh it to the utmoft extremity : upon thi.% 
 there will come over a black, thick liquor: it will 
 ;nd congealed, and prove the Icy Oil of 
 Vitriol, if care hath been taken to change the re- 
 ceiver, keep the veflels perfectly dole, and give a 
 fufficient degree of heat. Proceed thus till ndthing 
 more comes over, or at lead very little. Let the 
 veffrls cool, unl-jte them, pour the contents of the 
 receiver into a bottle, and leal it hermetically. 
 
 OBSERVATIONS. 
 
 GREEN Vitriol retains much water in cryftalliz- 
 ing; and in order to free it from that fuperfluous 
 phlegm, it muft be calcined before you diftill ir. 
 "Without this precaution the operation will be ex- 
 .iinoly protracted, and a great deal of time wafted 
 in diililling fuch a quantity of water; which will 
 moreover greatly weaken the Acid by commixing 
 wich it, unlefs care be taken to change the reci- 
 pient as ibon as the water is all come over. 
 
 But there is alfo another advantage in calcining 
 the Vitriol before you put it into the retort: for 
 otherwifc this fait would melt on the firft application 
 of heat, and run into a mafs -, which would prove 
 a great hindrance to its diftillation. This inconve- 
 nience is avoided by a previous calcination, in con- 
 
 jence whereof the Vitriol is eafily reduced to a 
 powder which never becomes fluid. 
 
 Vitriol
 
 PRACTICE o/' C H Y M i s T R Y* 
 
 Vitriol calcined as directed in the procefs grows 
 fo hard, and adheres fo firmly to the veffel in which 
 the calcination is performed, that it requires no 
 fmall pains to feparate and pulverize it. Care muft 
 be taken to put it into the retort as foon as it is 
 pulverized, and to flop that veffel very clofe if you 
 do not begin the diftillation immediately : for 
 otherwife it will naturally attract from the air almoft 
 all the moifture it hath loft. 
 
 The Acid which Vitriol yields by diftillation is 
 fulphureous ; probably becauie it ftill retains Ibme of 
 the Phlogifton, with which it was united when under 
 the form of fulphur in the Pyrites , or elfe hath 
 laid hold on a portion of that belonging to the iron 
 which ferved for its bafis in Vitriol. But this ful- 
 phureous part is volatile, and flies off in time. 
 
 This decompofition of Vitriol in clofe veffels is a 
 difficult and laborious procefs. To carry the opera- 
 tion to its utmoft perfection requires a fire of ex* 
 treme violence, kept up without intermiffion during 
 four or five days -, fuch in (hort as few veffels are 
 able to bear. Of courfe this operation is feldom 
 performed in laboratories. The French Chymifts 
 fetch their Oil of Vitriol from Holland, where it is 
 extracted from Vitriol in large quantities, by means 
 of furnaces erected for the purpofe, in which many 
 retorts are employed at once. 
 
 In the Memoirs of the Academy of Sciences M. 
 Hellot hath given us the moft material circumftances 
 of a very fine experiment of this kind, in which he 
 pufhed the diftillation of Green Vitriol to the utmoft. 
 Into a German retort * he put fix pounds of Green 
 Englifli Vitriol calcined to rednefs, which he ex- 
 pofed to a fire of the extremeft violence, conftantly 
 kept up during four days and four nights. At the 
 expiration of that time he found in the veffels em- 
 
 * They are much the beft, and bear a very fierce heat. 
 
 ployed
 
 228- E L E M E N T S of the 
 
 ployed as receivers art Icy Oil of Vitriol, which 
 was altogether in a cryftalline form and black. The 
 precautions neceliary to make this experiment luc- 
 ceed he reprefents in the following terms. 
 
 " The fuccefs of this operation, which produces 
 " an Oil of Vitriol ptncjiiy Icy and without any 
 " liquor, depends on the care taken to prevent the 
 " acid vapours, driven by the fire out of Vitriol 
 " calcined to rednefs, from having any communi- 
 " cation with the external air while they are diftil- 
 " ling : for otherwiie they will attract from it a 
 " moirture which will keep them fluid in the re- 
 " ceiver. The receiver inn (I be at fuch a diftance 
 *' from the furnace that it may remain cool enough 
 " for the vapours to condenfe in it. There muft 
 *' alfo be fufficient room for thole vapours to circu- 
 " hue in, and to prevent the fulphureous explotions, 
 .ich are every now and then difcharged out of 
 " the retort, from burfting the vefiels : for though 
 *' the previous calcination of the Vitriol hath car- 
 *' ried off the moft volatile, yet there Hill remains 
 " enough of the inflammable principle, even in the 
 *' ir.;n itkrlf, to form a Sulphur with the Acid as 
 " it is extricated, or at leait a mrxt that would be 
 " as apt to take fire as common Sulphur, if it were 
 *' not over-doled with the Acid. 
 
 " As the bed means of gaining thefe ends M. 
 ** Hellot contrived to adapt to the neck of his re- 
 " tort a receiver with two necks, the lowermoit of 
 " which was inferted into a large ballon. Receivers 
 " arnlk-d to each other in this manner are called 
 " Adopters. 
 
 ' it is no eafy matter to get this Icy Oil out of 
 *' the ballon : for as foon as the air touches it fuch 
 " a thick cloud of fulphureous fumes ariies, that 
 *' it is abfolutely ncccffary to place the veffel on 
 " fome fhelf over head, becaufe a man cannot (land 
 - 5 " expofed
 
 PRACTICE of CH YMISTR Y. 229 
 
 " expofed thereto for a fingle minute without be- 
 " ing fuftbcated." 
 
 This Icy Acid muft be fliut up with all poffible 
 expedition in a cryftal bottle accurately clofed with 
 a glais iiopple, which mould be ground with emery 
 in its neck fo as to fit it exactly : for it attracts 
 moifture fo powerfully, that, unlefs exceeding great 
 care be taken to prevent all communication with 
 the external air, it will foon difiblve into a fluid. 
 
 " The Icy Oil is black ; becaufe the acid vapours 
 " carry over with them fomething of a greafy mat- 
 "*' ter, from which Vitriol is feldom live, and 
 " which always appears, after repeated iblutions 
 " and crystallizations of this Salt, in the mojher- 
 " water which will moot no more. Now the 
 " fmalleft portion of inflammable matter prefently 
 " blackens the moft highly rectified Oil of VirrLl, 
 " which is perfectly clear. 
 
 " The Vitriolic Acid, when forced over by a 
 " violent heat, carries along with it forne ferrugi- 
 " nous particles alib, that want nothing but to be 
 " united with a Phlogifton to become true iron. 
 " They are eafily difcovered, either in the common 
 " black Oil of Vitriol, or in the blackifli cryftals 
 " of the Icy Oil, by only diflblving them in a large 
 " quantity of diiiilled v;a:er : for after feven or 
 " eight days digefiion a light powder or downy 
 " fediment precipitates, which being calcined in a 
 " violent fire is partly attracted by the magnet ; 
 " and being again calcined with bees-wax becomes 
 " almoft entirely iron." 
 
 The Caput mortuum of this diftillation of Vitriol 
 is the ferruginoxis earth of this Salt, and is called 
 Colcothar. "When this Colcothar hath undergone a 
 violent fire, as in the experiment now related, force 
 any Acid remains therein. Out of fix pounds ot 
 Vitriol that M. Hellot uled, he could recover no 
 more, by lixiviating what was left in the retort, 
 
 than
 
 230 ELEMENTS^/" tbs 
 
 than two ounces of a Vitriolic Salt j and even that 
 was very earthy. 
 
 If" Vitriol be expofed to a fire neither fo violent 
 nor fo long continued, its Colcothar will yield a 
 greater quantity of Vitriol that hath not been de- 
 compofed. A white crystalline fait is alib obtained 
 from it, and called Salt cf Cokotbar \ which is no 
 other than the fmall portion of Alum ufually con- 
 tained in Vitriol, and not fo eafily decomposed by 
 the aftion of fire. 
 
 PROCESS V. 
 
 fo decompcfe Sulphur, and extratt its Acid, by 
 burning it. 
 
 TAKE any quantity of the pureft Sulphur : fill 
 therewith a crucible or other earthen difh : 
 heat it till it melts : then fet it on fire ; and when its 
 whole' furface is lighted place it under a large glafs 
 head, taking care that the flame of the Sulphur do 
 not touch either its fides or bottom , that the air 
 have free accels, in order to make the Sulphur 
 burn clear-, and that the head incline a little to- 
 ward the fide on which its beak is, that as the va- 
 pours condenfe therein the liquor may run off with 
 cafe. To the beak of this veflel fit a receiver : the 
 fumes of the lighted Sulphur will be condenfed, 
 and gather into drops in the head, out of which 
 they will run into the receiver. There, when the 
 Sulphur has done burning, you will find an Acid 
 liquor, which is the Spirit of Sulphur. 
 
 OB S ERVAT 10 N S. 
 
 IN the burning of Sulphur, the Phlogifton which 
 
 ferves for its bafis is difiipated, and feparated from 
 
 the Acid which is left at liberty. The acid fumes 
 
 which rife from the lighted fulphur ftrike againll the 
 
 5 infido
 
 PR AC TICE of CH YMISTR Y. 23 I 
 
 infide.of the head placed over ir, are there comienfed, 
 and appear in the form of a liquor. But as Sulphur, 
 like all other inflammable bodies, Nitre excepted, 
 will not burn in clofe veflels, it is neceffary that the 
 air be freely admitted here; which occafions the lofs 
 of a great deal of the Acid of the Sulphur, as is 
 evident from the pungent fuffocating fmell per- 
 ceived in the laboratory during the operation. 
 
 This Acid, while combined with the Phlogifton, 
 is incapable of contracting any union with water -, 
 but when alone is very apt to mix therewith : it is 
 even proper to put fome in its way, that it may in- 
 corporate therewith as foon as it is difcharged from 
 the Sulphur ; for it is tiien very free from phlegm, 
 very volatile, and confequently very little difpofed. 
 to condenfe into a liquor, but on the contrary very 
 apt to fly off in vapours. The water, which it im- 
 bibes with a kind of avidity, fixes and detains it ; fo 
 that by this means a much greater quantity there- 
 of is obtained from Sulphur, than if it were diftilled 
 without this precaution. 
 
 It is proper therefore now and then to introduce a 
 difh full of hot water under the head which receives 
 the fumes of the Sulphur. The vapours that ex- 
 hale from the water bedew the infide of the head, 
 and procure the advantage we are fpeaking of. 
 
 The fame thing may be effected fcveral other 
 ways : thus, the crucible containing the Sulphur 
 may be fet on a foot placed in an earthen difh with 
 fome water in it ; which however muft not rife above 
 the foot-, for if it mould reach the crucible, it might 
 cool and fix the fulphur. The dim thus prepared 
 muft be placed on a fand-bath hot enough to make 
 the water fmoke continually ; a,nd over all is to be 
 placed the head as directed in the procefs. 
 
 The fize and form of the veffel which immediate- 
 ly receives the fulphureous fumes may aifo contri- 
 
 bute
 
 232 E L E M E N T s of the 
 
 bute to increafe the quantity of the Acid Spirit. A 
 very large vefiel, with a hole at bottom no wider 
 than is jufl fufficient to admit the vapours, is the 
 properett for this operation. 
 
 After the Sulphur has burnt for fome time, it 
 often happens that a fort of fkin or cruft forms on 
 its furface, which is not inflammable, but gradually 
 lefiens the quantity and vigour of the flame as it in- 
 creafes in thicknefs, and at lail puts it quite out. 
 This cruft proceeds from the impurities, and hete- 
 rogeneous uninflammable particles contained in the 
 fulphur. Care muft be taken to remove it with an 
 iron wire as faft as it forms. 
 
 Two quantities of Sulphur may allb be kept in 
 two crucibles, and heated alternately. That in 
 which the Sulphur is hot and melted may be lub- 
 flituted for the other in which the Sulphur is grown 
 cold and fixed j bccaufe cold Sulphur does not 
 burn well. 
 
 The Spirit of Sulphur is at firft pungent and vo- 
 latile, becaufe it ftili retains a fmall portion of the 
 Phlogifton : but that fulphureous part flies off, 
 efpecially if the bottle in which the Spirit is kept 
 be left for fome time unftopped. 
 
 The Acid obtained from Sulphur appears by all 
 chymical proofs perfectly like that obtained from 
 Vitriol: they differ in this only that the former is 
 the pureit \ for the Acid obtained from Vitriol car- 
 ries over with it fome metallic parts, as we ob- 
 ferved before, which can never happen to that ob- 
 tained from Sulphur. 
 
 Tf linen rags dipped in a folution of Fixed Al- 
 kali be expofed to the fumes of burning brim'lone, 
 the Spirit of Sulphur joins with the Alkali, and 
 therewith forms a Vitriolated Tartar. This Salt is 
 "known to be formed when the rags grow ftifF, and 
 appear fpangled with a vail many glittering points, 
 
 which
 
 PRACTICE of CHYM ISTR Y. 233 
 
 which are nothing but little cryftals of the Salt we 
 are fpeaking of. 
 
 When the Sulphur burns very gently and flowly 
 the Spirit that exhales from it is fo much the more 
 fulphureous and volatile : and hence the Salt formed 
 by the combination of this Spirit with the Alkali 
 expofed to it in linen rags, as in the above-menti- 
 oned experiment, is not at firfta Vitriolated Tartar- 
 but a Neutral Salt of a particular kind, which is 
 capable of being decomposed by any other Mineral 
 Acid, thefulphureous Acid having lefs affinity than 
 any of the reft with Alkalis. Neverthelefs this Salt 
 becomes in time a true Vitriolated Tartar, becaufe 
 the fulphureous part which weakened its Acid 
 eafily quits it and flies off. 
 
 PROCESS VI. 
 
 T0 concentrate the vitriolic Acid. 
 
 TAKE the Vitriolic Acid you intend to concen- 
 trate, that is, 'to dephlegmate and make 
 ilronger : pour it into a good glafs retort, of fuch a 
 fize that your quantity of Acid may but half fill it: 
 fet this retort in the fond-bath of a reverberating 
 furnace : fit to it a receiver; lute it on, and give a 
 gradual fire. There will come over into the recei- 
 ver a clear liquor, the firil drops of which will be 
 but faintly Acid : this is the moft aqueous part. 
 
 When the drops begin to follow one another 
 much more flowly, raife your fire, till the liquor be- 
 gin to bubble a little in the middle. Keep it thus 
 gently boiling, till one half or two thirds thereof 
 be come over into the receiver. Then let your 
 Veflels cool ; unlu'te'them ; what remains in the re- 
 tort pour into a cryftal bottle, and flop it exacftly 
 \vith a clafs flopple rubbed with emery. 
 
 B S E R-
 
 234 ELEMENTS of the 
 
 OBSERVATIONS. 
 
 THE Acid obtained from Sulphur is generally 
 very aqueous , either becaufe in preparing it water 
 mull neceflarily be adminiftcred, that it may unite 
 therewith as it feparates from the Sulphur ; or be- 
 caufe it is fo greedy of moifture as to attract a great 
 deal from the air, which muft needs be admitted to 
 make the Sulphur burn. 
 
 The Acid obtained from Vitriol, excepting that 
 which rifes laft, is alfo mixed with a pretty confide- 
 rable quantity of phlegm , becaufe the Vitriol, 
 though calcined, ftill retains a great deal thereof, 
 which riles with the Acid in diflillation. Now, as 
 there are many chymical experiments that will not 
 fucceed without Acids exceedingly dephlegmatcd, 
 it is proper to have in a laboratory all the Acids 
 thus conditioned : becaufe if they happen to be 
 too ftrong for particular operations, as is ibmetimes 
 the cafe, it is very eafy to lower them to the defired 
 degree, by adding a fufficient quantity of water. 
 
 The Vitriolic Acid is much heavier and much 
 lefs volatile than water. If therefore a mixture of 
 thefe two liquors be expofed to the fire, the aqueous 
 part will rife with a degree of heat which is not able 
 to carry up the Acid : by this means they may be 
 feparated from each other j and thus is the Vitriolic 
 Acid concentrated. 
 
 Neverthelefs, as this Acid combines mod clofcly 
 with water, and is in a manner flrongly connected 
 with it, the water carries up fome portion thereof 
 along with it ; and hence it comes that the liquor 
 which rifes into the receiver is Acid : it is called 
 Spirit of Vitriol. 
 
 As the fire carries off the moft aqueous part, 
 the other which remains in the retort increaics in 
 fpecific gravity. The Acid particles are brought 
 nearer together, retain the aqueous particles more 
 
 obfti-
 
 PRACTICE?/" CHYMISTRY. 235 
 
 obftinately , and therefore to feparate them the de- 
 gree of heat muft be increafed. 
 
 It is ufual to draw off one half or two thirds of 
 the liquor that was put into the retort: but this 
 depends on the degree of ftrength the Acid was of 
 before concentration, and the degree of concentra- 
 tion intended to be given it. 
 
 If the Acid to be concentrated be Oil of Vitriol, 
 from being brown or black it grows clearer as the 
 operation advances, and at latt becomes perfectly 
 colourlefs and tranfparent-, becaule the fat matter, 
 which tinged it black, is difllpated during thepro- 
 cefs. Some of it depofites a white cryftalline earth. 
 
 A fulphureous fmell is generally perceived about 
 the veffels in this operation. This arifes from a 
 fmall portion of the Phlogifton from which the 
 Acid is not free; and 'tis this inflammable matter 
 which gives the Oil of Vitriol its black colour : for 
 the cleared and bed reclined Oil of Vitriol will be- 
 come brown, and even black, in a fhort time, if any 
 inflammable matter, though in a very fmall quanti- 
 ty, bediffolved therein. 
 
 The veflels are luted in this operation, to prevent 
 any lofs of the Spirit of Vitriol, which being very 
 acid is of ufe in many chymical experiments, and 
 may itfelf alfo be again concentrated, 
 
 We obferved that in this operation it is neceflary 
 the retort fhould be of very good glafs. Indeed 
 the Acid is fo adtive and fo ftrong, that if the glafs 
 be tender and have a little too much fak in its com- 
 pofuion, it will be fo corroded thereby that it will 
 fall to pieces. 
 
 Though we directed the retort to be fet in a fand- 
 bath for this operation, it does not follow that it 
 may not alfo be placed in a naked fire : on the con- 
 trary, when the heat is not conveyed through a bath 
 the operation advances fafter, and is much lets te- 
 dious. But then great caution muft be ufed, and 
 
 the
 
 236 ELEMENTS of the 
 
 
 
 the clofeft attention given to the management of 
 the fire, which muft be raifed by almoft impercep- 
 tible degrees, efpecially at the beginning of the 
 operation ; otherwiie it is next to a certainty that 
 the vefiels will break. In general, a naked fire 
 may be employed in almoll ail dilhllarions which 
 require a greater degree of heat than that of boil- 
 ing water, or the balneum mart a : the operation will 
 be fooner finifhed -, but it requires an experienced 
 hand, that has by practice acquired a habit of go- 
 verning the fire with judgment. 
 
 There is moreover another advantage in not 
 ufing the land-bath -, which is, that if in the time 
 of the operation you perceive the fire too fierce, 
 you can quickly check it, either by (lopping clofe 
 all the apertures of the furnace, or by drawing out 
 all or part of the lighted coals. This inconvenience 
 is not near fo eaiily remedied when you ufe the 
 fand-bath ; becaufe when once heated it retains its 
 heat very long after the fire is quite extinguiihed. 
 
 PROCESS VII. 
 
 T0 decompofe Vitriolated Tartar by means of the Phlo- 
 gifton , or to compofe Sulphur by combining the Vi- 
 triolic Acid with the Pblogifton. 
 
 TAKE equal parts of Vitriolated Tartar, and 
 very dry Salt of Tartar, feparately reduced 
 to powder ; add an eighth part of their weight of 
 charcoal-dud ; and mix the whole together very 
 accurately. Throw this mixture into a red hot 
 crucible, placed in a furnace filled with burning 
 coals. Cover it very dole, and keep it very hot, 
 till the mixture melt, which may be known by un- 
 covering the crucible from time to time. There 
 
 will
 
 PRACTICE ^CHYMISTRY. 237 
 
 then appear a bluilh flame, accompanied with, 
 a pungent fmell of Sulphur. 
 
 Take the crucible out of the fire : difiblve its 
 contents in hot water : filter the folution through 
 brown paper fupported by a glafs funnel : drop in- 
 to the filtered liquor by little and little any Acid 
 whatever. As you add the Acid the liquor will grow 
 more and more turbid, and let fall a grey precipi- 
 tate. Continue dropping in more Acid till the li- 
 quor will yield no more precipitate. Filter it a fe- 
 cond time, to feparate it from the precipitate : what 
 remains on the filter is a true inflammable Sulphur, 
 which you may either melt or fublime into flowers. 
 
 OB S ERV AT 10 N S. 
 
 ALL bodies that contain the Vitriolic Acid may 
 contribute, as well as Vitriolated Tartar, to the ge- 
 neration of Sulphur : fo that all the neutral Saks 
 in which this Acid is a principle, the Alums, Sele- 
 nites, Gypfums, Vitriols, may be lubftituted for it 
 in this experiment. All theie matters, with the ad- 
 dition of charcoal-dud only, being fufed in a cruci- 
 ble, conitantly produce Sulphur ; becaufe the Vi- 
 triolic Acid having a greater affinity with the Phlo- 
 gifton than with any thing elfe, will quit its bafis, 
 whatever it be, to join with the Phlogifton of the 
 charcoal, and therewith form a Sulphur. 
 
 The fixed Alkali added thereto helps to promote 
 the fufion of the ingredients, which is neceiTary for 
 effecting the defired combination. It alib ferves to 
 unite with the Sulphur, when formed -, and thus 
 makes the combination called Liver of Sulphur, 
 which prevents the Sulphur from being coniumed 
 as loon as formed : for the fixed Alkalis, which are 
 incombuftible, hinder Sulphur from burning lo 
 eafily as it would do if they were not joined with it. 
 They may afterwards be feparated from each other, 
 by the means of any Acid whatever. 
 
 This
 
 ELEMENTS of the 
 
 This procefs, in which Sulphur is regenerated, by 
 re-combining together the principles of which it 
 was originally competed, is one of the mod beauti- 
 ful experiments that modern Chymiftry hath pro- 
 duced. We are indebted for it to M. Stahl , and 
 Dr. GeoflVoy hath given a particular account of it 
 in the Memoirs of the Academy of Sciences. 
 
 Before thele gentlemen Glauber and Boyle had 
 indeed publifhed methods of producing Sulphur, 
 Glauber made ule of his Sal mirabile and powdered 
 charcoal : Boyle employed the Vitriolic Acid and 
 Oil of Turpentine. But neither of thofe Chymifts 
 underflood rhe true theory of their operations : they 
 did not thoroughly know the principles of Sulphur : 
 they did not imagine they had compofed Sulphur-, 
 they thought they only extracted what they fup- 
 pofed to exift previoufly in the matters they em- 
 ployed in their experiments. 
 
 M. Stahl was the firft who difcovered and explain- 
 ed the nature of Sulphur, and proved that in Glau* 
 ber's and Boyle's experiments Sulphur was actually 
 produced, by uniting together the principles of 
 which it is conftituted. This beautiful experiment 
 pives the flrongeft luftre of evidence to the theory 
 of the compofuion of that mixt, which acts fuch a 
 capital part in Chymiftry , and it can no longer be 
 doubted that Sulphur is actually a combination ot 
 the Vitriolic Acid with the Phlogifton. 
 
 Befides this important truth, our procefs for com- 
 pofing Sulphur by art proves feveral others that are 
 equally efiemial and fundamental. 
 
 The firft is that the Vitriolic Acid hath a greater 
 affinity with the Phlogifton than with any other thing, 
 feeing it quits metallic and earthy fubftances, as well 
 as Alkaline falts, in order to combine therewith. 
 
 The fecond is that Sulphur combines with fixed 
 Alkalis without fufreringany decompofmonj feeing 
 
 1C
 
 PRACTICE of CHVMISTRY. 239 
 
 it may be feparated from them* entire and unaltered; 
 and feeing that very Sulphur, which is naturally in- 
 diffoluble in water, is rendered foluble therein by 
 the union it hath contracted with the fixed Alkali. 
 
 The third is that the Vitriolic Acid, which when 
 it is pure hath the greateft affinity with Alkalis of 
 any Acid whatever, lofes a great deal of that affinity 
 by contracting an union with the Phlogifton , fee- 
 ing the weakeft Acids are capable of decompofing 
 the Liver of Sulphur, and feparating the Sulphur 
 from the Alkali. And this alfo confirms one of the 
 general propofitions concerning affinities advanced in 
 our theory , to wit, that the affinities of compound 
 or mixed fubftances are weaker than thofe of the 
 fame fubftances in a purer or more fimple ftate. 
 
 CHAP. II. 
 
 Of the NITROUS ACID. 
 
 PROCESS I. 
 
 'To extra ft Nitre out of nitrous Earths and Stones. 
 'The Purification of Salt Petre. Mother of Nitre. 
 Magnefia. 
 
 TAKE any quantity of nitrous earths or ftones ; 
 reduce them to powder -, and therewith mix 
 a third part of the afhes of green-wood and quick- 
 lime. Put this mixture into a barrel or vat, and 
 pour on it hot water to about twice the weight of 
 the whole mafs. Let it ftand thus for twenty-four 
 hours, ftirring it from time to time with a (tick. 
 Then filter the liquor through brown paper, or pals 
 it through a flannel bag, till it come clear : it will 
 then have a yellowifli colour. Boil this liquor, and 
 evaporate till you perceive that a drop of it let fall 
 
 on
 
 240 ELEMENTS of the 
 
 on any cold body coagulates. Then (lop the eva- 
 poration, and let your liquor in a cool place. In 
 the fpacc of rour-and-tvventy hours cryilals will be 
 formed in it, the figure of which is that of an hex- 
 agonal prifir, having its oppofite planes generally 
 equal, and terminated at each extremity by a py- 
 ramid of the lame number of fides. Thcfe cryilals 
 will be of a brownilh colour, and deflagrate on a 
 live coal. 
 
 Decant the liquor from thefe cryilals -, mix it with 
 twice its weight of hot water; evaporate and cryf- 
 talhze as before. Repeat the fame operation till the 
 liquor will yield no more cryilals: it will then be 
 very i i goes by the name of Mother of Nitre. 
 
 OBSERVATIONS. 
 
 EARTHS and ilones that have been impregnated 
 with animal or vegetable juices fulceptible of pu- 
 trefadlion, and have been long expoled to the air, 
 but flickered from the fun and rain, are thofe which 
 yield the greateft quantity of Nitre. But all forts 
 of earths and ilones are not equally fit to produce 
 it. None is ever found in flints or fands of a cryf- 
 talline nature. 
 
 Some earths and Hones abound fo with Nitre, 
 that it efflorefces fpontaneouily on their furface, in 
 the form of a cryilalline down. This Nitre may be 
 collected with brooms, and accordingly has the 
 name of Salt- Petre Sweepivgs. Some of this fort is 
 brought from India. 
 
 Hitherto we are much in the dark as to the ori- 
 gin and generation of Nitre. Some Chymifcs pre- 
 tend that the Nitrous Acid is diifufed through the 
 air, and gradually depofited in fuch earths and 
 lilies as are qualified to receive it. 
 
 Others, confidering that none of it is ever ob- 
 tained but from earths that have been impregnated 
 ve^e'.iblc or animal juices, have from thence 
 
 concluded
 
 PRACTICE 
 
 Concluded thofe two kingdoms to be the general 
 repofitories of the Nitrous Acid ; that if we do not 
 perceive it to exift in fuch matters at all, or at leaft 
 in any great quantity, till they have undergone pu- 
 trefaction, and are in ibme meafure incorporated 
 with fuitable earths and (tones, 'tis becaufe the Acid 
 is fo entangled with heterogeneous particles that it 
 requires the affiftance of putrefaction, and much 
 more of filtration through an earth, to difengage it, 
 and enable it to appear in its proper nature. 
 
 Laftly, others are of opinion that this Acid is no 
 other than the univerfal or Vitriolic Acid ; difguifed 
 indeed by a portion of the Phlogifton, which is com- 
 bined with it in a peculiar manner by the means of 
 putrefaction. They ground this opinion chiefly 
 on the analogy or rcfemblance which they find be- 
 tween the Nitrous Acid and the Volatile Sulphure- 
 ous Spirit. Its volatility, its pungent fmell, its 
 properties of taking fire, and of deftroying the blue 
 and violet colours of vegetables, ferve them as fo 
 many proofs. 
 
 Their opinion is the more probable on this ac- 
 count,- that even though the Nitrous Acid mould 
 actually be produced by vegetable and animal fub- 
 ftances, yet as thefe fubftances themfelves draw all 
 their component principles from the earth, and as 
 the Vitriolic Acid is diffufed through all the foils 
 which afford them nourilhment, there is great rea- 
 fon to think that the Nitrous Acid is no other than 
 the Vitriolic Acid altered by the changes and com- 
 binations it hath undergone in its paffage into and 
 through thofe fubftances. In 1 750 the Royal Aca- 
 demy of Sciences at Berlin propofed an account of 
 the generation of Nitre as the fubject for their 
 prize, which was conferred on a Memoir wherein 
 this lad opinion was fupported by fome new and 
 Very judicious experiments. 
 
 VOL. I. R The
 
 24* t B M E N T S </ the 
 
 The proccfs by which our Salt-petre makers ex 
 tract Nitre in quantities, out of rubbifh and nitrous 
 earths* is very nearly the fame with that here ftt 
 down : fo that I fhall not enter into a particular 
 account of it. I IhaU only take notice of one thing, 
 which it is of fome confluence to know -, namely, 
 that there is no nitrous earth which does not con- 
 tain fea-fak alfo. The greateft quantifies of this 
 fait are to be found in thole earths which have 
 been drenched with urine, or other animal excre- 
 ments. Now as the rubbifli of old houies in great 
 cities is in this clafs, it comes to pals that when the 
 Salt-petre workers evaporate a nitrous lixivium 
 drawn from that rubbifh, as foon as the evapora- 
 tion is brought to a certain pitch, a great many 
 little cryftals of fea-fak form in the liquor, and fall 
 to the bottom of the veficl. 
 
 The Salt-petre workers in France call thefe faline 
 particles the Grain, and take great care to feparate 
 them from the liquor, (which as long as it continues 
 hot keeps the falt-petre diflblved) before they fet it 
 to cryftallize. This fact leems a little fmgular, con- 
 fidering that fea-falt diffolvcs in water more eafily 
 than falt-petre, and cryftallizes with more difficulty. 
 
 In order to dilcover the caufe of this phenomenon, 
 we mull recollect fome truths delivered in our theo- 
 retical Elements. The firtt is, that water can keep 
 but a determinate quantity of any fait in folution* 
 and that if wa-tcr fuJly fatura-ted with a fait be evapo- 
 rated, a quantity of fait will cryftallize in proportion 
 to the quantity of water evaporated. The fecond is, 
 that thole falts which are the moft foluble in water, 
 particularly thole which run in the air, will difiblve 
 
 colvi and in boiling water equally ; whereas much 
 greater quantities of the other falts will difiblve in 
 hot and boiling water than in cold water. Thefe 
 things being admitted, when we know that fea-fak 
 is one of the firft fort, and falt-petre of the fecond, 
 i the
 
 PRACTICE of CHYMISTRY. 243 
 
 the reafon why fea-falt precipitates in the prepara- 
 tion of falt-petre appears at once. For 
 
 When the iblution of falt-petre and fea-fak comes 
 to be evaporated to fuch a degree that it contains as 
 much fea-falt as it pofiibly can, this fait muft begin 
 to cryftallize, and continue to do fo gradually as 
 the evaporation advances. But becaufe at the fame 
 time it does not contain as much falt-petre as it can 
 hold, feeing it is capable of diffbl ving a much greater 
 quantity thereof when it is boiling hot than- whep 
 it is cold, this laft named fait will not cryftallize Ib 
 foon. If the evaporation were continued till the 
 cafe of the falt-petre came to be the fame with that 
 of the fea-falt, then the falt-petre alfo would begin 
 to cryftallize gradually in proportion to the water 
 evaporated, and the two falts would continue cryl- 
 tallizing promifcuoufly together: but it is never 
 carried fo far ; nor is it ever neceflary -, for as the 
 water cools it becomes more and more incapable 
 of holding in folution the fame quantity of falt- 
 petre as when it was boiling hot. 
 
 And then comes the very reverfe, with regard to 
 the cryftallizing of the two falts , for then the Salt- 
 petre (hoots, and not the Sea-falt. The reafon of 
 this fact alfo is founded on what has juft been faid. 
 The Sea-falt, of which cold water will difiblve as 
 much as boiling water, and which owed its cryftal- 
 lizing before only to the evaporation, now ceafes to 
 cryftallize as foon as the evaporation ceafes -, whilq 
 the Salt-petre, which the water kept difiblved only 
 becaufe it was boiling hot, is forced to cryftallize 
 merely by the cooling of the water. 
 
 When the folution of Salt-petre has yielded as 
 many cryftals of that Salt as it can yield by cooling, 
 it is again evaporated, and being then fuffered to 
 cool yields more cryftals. And thus they continue 
 evaporating and cryftallizing, till the liquor will 
 afford no more cryftals. It is plain that as the Salt- 
 R 2
 
 244 ELEMENTS of the 
 
 pctre cryftallizes, the proportion of Sea-falt td 
 the dilfolving liquor increales , and as a certairi 
 quantity of water evaporates alfo during the time 
 employed in cryftallizing the Salt-petre, a quantity 
 of Sea-falt, proportioned to the water Ib evaporat- 
 ing, muft cryftallize in that time : and this is the 
 reaibn why Salt-petre is adulterated with a mixture 
 of Sea-falt. It likewife follows that the lall cryftals 
 of Nitre, obtained from a folution of Salt-petre 
 and Sea-falt, contain much more Sea-falt than the 
 firft. 
 
 From all that has been faid concerning the cryf- 
 tallization of Salt-petre and Sea-falt, it is eafy to 
 deduce the proper way of purifying the former of 
 the!e two Salts from a mixture of the latter. For 
 this purpofe the Salt-petre to be refined need only 
 be difiblved in fair water. The proportion between 
 the two falts in this fecond folution is very different 
 from what it v/as in the former; for it contains no 
 more Sea-falt than what had cryftallized along with 
 the Salt-petre under favour of the evaporation, the 
 reft having been left difiblved in the liquor that re- 
 fuled to yield any more nitrous cryftals. 
 
 As there is therefore a much greater quantity of 
 Salt-petre than of Sea-falt in this fecond folution, ic 
 is eafy to evaporate it to fuch a degree that a great 
 1 of Salt-petre fhall cryftallize, while much more 
 of the water muft necefiarily be evaporated before 
 any of the Sea-falt will cryftallize. 
 
 However, the Salt-petre is not yet entirely freed 
 from all mixture of Sea-falt by this firft purification ; 
 for the cryftals obtained from this liquor, in which 
 Sea-falt is diflblved, are ftill encrufted, and, as it 
 were, infected therewith : hence it comes, that, tof 
 refine the Salt-petre thoroughly, thefe cryftalliza- 
 tions muft be repeated four or five times. 
 
 The Salt-petre men commonly content themfelves 
 with cryftallizing it thrice, and call the produce Sah- 
 
 pctrc
 
 PRACTICE of CHYMISTRY. 245 
 
 petre of the fir ft, fecond, or third (hoot, according 
 to the number of cryftallizations it has undergone. 
 But their beft refined Salt-petre, even that or" the 
 third (hooting, is not yctfufficiently pure for Chy- 
 mical experiments that require much accuracy : 
 fo that it muft be further purified , but ftill by the 
 fame method. 
 
 . The Nitrous Acid is not pure in the earths and 
 flones from which it is extracted. It is combined 
 partly with the very earth in which it is formed, and 
 partly with the Volatile Alkali produced by the pu- 
 trefaction of the vegetable or animal matters that 
 concurred to its generation. A Fixed Alkali and 
 Quick-lime are added to the lixivium of a nitrous 
 earth, in order to decompofe the nitrous Salt form- 
 ed in that earth, and to feparate the Acid from the 
 Volatile Alkali and the abforbent earth with which 
 it is united : thence comes that copious fedimcnt 
 which appears in the lye at the beginning of the 
 evaporation. Thefe matters form with that Acid 
 a true Nitre, much more capable than the original 
 Nitrous Salts of cryftallization, detonation, and the 
 other properties which are efiential thereto. The 
 bafis of Nitre is therefore a Fixed Alkali mixed 
 with a little lime. 
 
 The Mother of Nitre, which will yield no more 
 cryftals, is brown and thick : by evaporation over 
 a fire it is further infpiffated, and becomes a dry, 
 folid body ; which however being left to itlelf foon 
 gives, and runs into a liquor. This water ilill con- 
 tains a good deal of Nitre, Sea-falt, and the Acids 
 of thele Salts united with an abforbent earth. It 
 contains moreover a great deal of a fat, vifcid mat- 
 ter, which prevents its cryftallizing. 
 
 All faline folutions in general, after having yield- 
 ed a certain quantity of cryftals, grow thick, and 
 refufe to part with any more, though they ftill con- 
 tain much Salt. They are all called Mother-water;, as 
 R 3 well
 
 246 ELEMENTS of t1:c 
 
 well as that which hath yielded Nitre. The Mo- 
 ther-waters of different Salts may prove the fubjefts 
 of curious and ufcful enquiries. 
 
 If a Fixed Alkali be mixed with the Mother of 
 Nitre, a copious white precipitate immediately falls, 
 which being collected and dried is called Magnefia. 
 This precipitate is nothing but the abforbent earth 
 that was united with the Nitrous Acid, together 
 with a good deal of the lime that was added, and 
 was alfo united with that Acid, from which they 
 are now feparated by the Fixed Alkali, according 
 to the ufual laws of affinities. 
 
 The Vitriolic Acid poured upon Mother of Ni- 
 tre caufes many Acid vapours to rife, which are 
 a compound of the nitrous and marine Acids, that 
 js, an Aqtta rtgia. On this occafion alfo there falls 
 a large quantity of a white powder, which is ftill 
 called Magnefia ; yet it differs from the former in 
 that it is not, like it, a pure abforbent earth, bat 
 combined with the Vitriolic Acid. 
 
 An Aqua regis may alfo be drawn from nitrous 
 earths by the force of fire only, without the help 
 of any additament. 
 
 PROCESS II. 
 
 decompofe Nitre by means of the Pklogifton. Ni- 
 tre fixed by Charcoal. Clyfius of Nitre. Sal Po- 
 ly chreftum. 
 
 TAKE the pureft Salt-petre in powder j put it 
 into a large crucible, which it may but half 
 fill -, fet the crucible in a common furnace, and fur- 
 round it with coals. When it is red-hot the Nitre 
 will melt, and become as fluid as water. Then 
 throw into the crucible a fmall quantity of charcoal- 
 duft : the Nitreand the charcoal will immediately de- 
 flagrate with violence i and a great commotion will be 
 
 raifed,
 
 PR ACTICE of CHYMISTRY. 247 
 
 raifed, accompanied with a confiderable hiffing, and 
 abundance of black fmoke. As the charcoal waftes, 
 the detonation will abate, and ceafe entirely as foon 
 as the coal is quite confumed. 
 
 Then throw into the crucible the fame quantity 
 of charcoal-duft as before, and the fame phenome- 
 na will be repeated. Let this coal alfo be confum- 
 ed : then add more, and go on in the fame manner 
 till you can excite no further deflagration ; always 
 obferving to let the burning coal be entirely con- 
 fumed before you add any frefh. When no defla- 
 gration enfues, the matter contained in the crucible 
 will have loft much of its fluidity, 
 
 OB S ERV A? 10 N S. 
 
 NITRE will not take fire, unlefs the inflammable 
 matter added to it be actually burning, or the Nitre 
 itfelf red-hot, and fo thoroughly ignited as imme- 
 diately to kindle it. Therefore, if you would pro- 
 cure the detonation of Nitre with charcoal, and 
 make ufe of cold charcoal, as in the procefs, tlie 
 Nitre in the crucible muft be red-hot, and in per- 
 fect fufion : but you may alfo ufe live coals, and 
 then the Nitre need not be red-hot. 
 
 It is proper that the crucible ufed in this experi- 
 ment mould be only half full ; for during the deto- 
 nation its contents fwell, and might run over with- 
 out this precaution. For the fame reaibn the char- 
 coal-duft is to be thrown in by little and little ; and 
 that firft put in muft be entirely confumed before 
 any frefh be added. 
 
 The matter remaining in the crucible after the 
 operation is a very ftrong Fixed Alkali. Being ex* 
 pofed to the air it quickly attracts the moifture there- 
 of, and runs into a liquor. It is called Alkalizated 
 Nitre, or to diftmguifh it from Nitre alkalizated by 
 pther inflammable matters, Nitre fixed by charcoal. 
 R 4 However }
 
 24-S ELEMENTS of the 
 
 i */ 
 
 However, this Alkali is not abfolutely pure. It 
 flill contains a portion of the Nitre that hath not 
 been decomposed : for when there remains but a 
 little of this Salt mixed with a great quantity of Al- 
 kali, which is not inflammable, the Alkali in fome 
 meafure (belters it, coats it over, and obftrufts that 
 immediate contact with the inflammable matters 
 applied, which is neccOary to make it deflagrate. 
 
 If the Fixed Alkali be defired perfectly free from 
 any mixture of undecompofed Nitre, the fire abouc 
 the crucible muft be confiderably increafed as foon 
 as the detonation is entirely over i the matter muft 
 be made to flow, which requires a much ftronger 
 heat than would melt Nitre, and kept thus in fu- 
 lion for about an hour. -After this no perfect Nitre 
 \vill be found therein : for the little that was left, 
 being unable to abide the force of the fire, as not 
 being extremely fixed, either is entirely diflipated, 
 or lofes its Acid, which is carried off by the violence, 
 of the heat. 
 
 Fixed Nitre contains alfo a portion of the earth 
 that constituted the bafis of the Nitre, which is no 
 other than the lime employed in its cryftallization^ 
 or elfe fome of the earth with which its Acid was ori- 
 ginally combined, and which it retained in cryftalliz- 
 ing. When Nitre is deflagrated with fuch matters as 
 produce aflies, thefe afhes likewile furnifh a certain 
 quantity of earth, which mixes with the Fixed Al- 
 kali. To ieparate thefe feveral earths from the 
 Alkali, nothing more is requifite than to let it run 
 fer defiquittm, or todiflblve it in water, and filter the 
 folution through brown paper. Whatever is faline 
 will pafs through the filtre with the water, and the 
 earthy part will be left upon it. 
 
 The Nitrous Acid is not only diflipated during 
 the deflagration of the Nitre, but is even deftroy- 
 cd, and perfectly decompofed. The fmoke that; 
 riles during the operation has not the leaft odour of
 
 PRACTICE of CKYMISTRY. 249 
 
 an Acid. Its nature may be accurately examined 
 by catching it in proper vefiels, and condenfmg it 
 into a liquor. 
 
 Nitre differs from Sulphur, and from all other in- 
 flammable bodies whatever, in this, that the free ac- 
 cefs of the air is indifpenfably necefiary to make any 
 of the others burn; whereas Nitre, and Nitre only, 
 is capable of burning in clofe vefiels : and this pro 
 perty furnifhes us with the means of collecting the 
 vapours which it difcharges in deflagration. 
 . For this purpofe to a tubulated earthen retort you 
 muft fit two or three large adopters : fet the retort 
 in a furnace; and under it make a fire iufficientto 
 keep its bottom moderately red. Then take a fmall 
 quantity, two or three pinches for example, of a 
 mixture of three parts of Nitre with one of char- 
 coal-duft, and drop it into the retort through its 
 tube, which muft be uppermoft, and immediately 
 flopped clofe. A detonation inftantly enfues, and 
 the vapours that rife from the inflamed mixture of 
 Nitre and charcoal, patting out through the neck of 
 the retort into the adopters, circulate therein for a 
 while, and at lad condenie into a liquor. 
 
 When the detonation is over, and the vapours 
 condenfed, or nearly fo, drop into the retort ano- 
 ther equal quantity of the mixture ; and repeat this 
 till you find there is liquor enough in the recipients 
 to be examined wi.th eafe and accuracy. This liquor 
 is almoft infipid, and fhews no tokens of acidity; 
 or at moil but very flight ones. It is called Clyffus 
 of Nitre. 
 
 It is eafy to perceive why feveral adopters are re- 
 quired in this experiment, and why a very fmall 
 quantity of the mixture muft be introduced into the 
 retort at once. The explofion, and the quantity of 
 air and vapours difchargcd on this occafion, would 
 quickly burft the veflels, if all thefe precautions 
 not attended to. This plainly appears from 
 
 the
 
 250 E L E M E N T s of the 
 
 the terrible effects of gun-powder, which is nothing 
 but acompofition of Nitre, Sulphur, and Charcoal. 
 
 Nitre is alib decompofed and takes fire by the 
 means of Sulphur; but the circumftances and the 
 rcfuh differ widely from thole produced therewith 
 by charcoal, or any other inflammable body. 
 
 Nitre deflagrates with Sulphur on account of the 
 Phlogifton which the latter contains. If one part 
 of Sulphur be mixed with two or three parts of Ni- 
 tre, and the mixture thrown by little and little into 
 a red-hot crucible, upon every projection there ariies 
 a detonation accompanied -with a vivid flame. 
 
 The vapours discharged on this occafion have 
 the mingled fmell of a Sulphureous Spirit and Spi- 
 rit of Nitre ; and if they be collected by means of 
 i tubulated retort, and fuch an apparatus of veflcls 
 as was uled in the preceding experiment, the liquor 
 contained in the recipients is found to be an actual 
 mixture of the Acid of Sulphur, the Sulphureous 
 Spirit, and the Acid of Nitre ; the firft being in 
 greater quantity than the other two, and the fecond 
 greater than the lad. 
 
 Nor is the remainder after detonation a Fixed Al- 
 kali, as in the former experiments ; but a Neutral 
 Salt, confifting of the Acid of Sulphur combined 
 with the Alkali of Nitre ; a fort of Vitriolated Tar- 
 tar known in medicine by the name of Sal Poly- 
 fbrejlum. 
 
 There are evidently two effential differences be- 
 tween this laft experiment and the preceding one. 
 What remains after the deflagration of Nitre with 
 Sulphur is not a Fixed Alkali : and moreover, the 
 vapours emitted in the operation are impregnated 
 withaquantityoftheNitrous Acid; which is notthe 
 tafe when Nitre is decompofed by any other inflam- 
 mable matter which contains no Vitriolic Acid. 
 
 The reaibn of thefe differences is naturally deduce- 
 om v/hat hath been already faid concerning the 
 
 properties
 
 PR ACTICE of CH YMISTR Y. 251 
 
 properties of the Vitriolic and Nitrous Acids. We 
 have feen that by burning Sulphur its Acid is not 
 decompofed, but only feparatcd from its Phlogiftoh. 
 We alfo know that its Acid has a great affinity with 
 Fixed Alkalis. Thefe things being granted, it fol- 
 lows that, as foon as the Nitrous Acid quits its Alka- 
 line bafis, by deflagrating with the Phlogifton of the 
 Sulphur, the Acid of this very Sulphur, being fee 
 at liberty by that deflagration, muft unite with the 
 Alkaline bafis deferted by the Acid of Nitre, and 
 therewith form a Neutral Salt. Hence, ihftead of 
 a Fixed Alkali, we find at the end of the operation 
 a fort of Vitriolated Tartar ; the Acids of Sulphur 
 and of Vitriol being the fame, as is evident from 
 what hath been above faid concerning them. 
 
 In order to difcover the caufe of the other pheno- 
 menon, we muft recollect two things advanced in 
 pur Elements of the Theory ; to wit, that the af- 
 finity of the Vitriolic Acid with Fixed Alkalis is 
 greater than that of the Nitrous Acid ; and again, 
 that the Nitrous Acid isnotcapableofcombiningand 
 taking fire with the Phlogifton, but when it is in the 
 form of a Neutral Salt, that is, when it is united 
 \vith fome alkaline, earthy, or metallic bafis. If 
 thofe two principles be applied to the effect in quef- 
 tion, the iblution is ea'fy and natural. For, in the 
 deflagration of Nitre with Sulphur, the Phlogifton 
 is not the only fubftance capable of feparating the 
 Nitrous Acid from its bafis : the Acid of the Sulphur, 
 more and more of which is fet at liberty as the Phlo- 
 gifton is confurned, is alfo capable of producing 
 the fame effect ; but with this difference, that the 
 portion of the Nitrous Acid which is detached from 
 Jts Alkali by the Phlogifton is at the fame inftant 
 fet on fire and decompofed by that union j where- 
 as trie portion thereof which is feparated by the 
 Vitriolic Acid, being when fo feparated incapable 
 pf uniting with the Phlogifton, and of cohfiiming 
 
 there-
 
 252 ELEMENTS of the 
 
 therewith, is preferved entire, and rifcs in vapours, 
 together with that portion of the Vitriolic Acid 
 which could not unite with the bafis of the Nitre. 
 
 PROCESS III. 
 
 To decompofe Nitre by means of the Vitriolic Acid. 
 The Smoking Spirit of Nitre. Sal de duobus. 
 The Purification of Spirit of Nitre. 
 
 TAKE equal parts of well purified Nitre and 
 Green Vitriol : dry the Nitre thoroughly, and 
 bruife it to a fine powder. Calcine the Vitriol to 
 rednefs : reduce it likewife to a very fine powder ; 
 and mingk thele two fubftances well together. Put 
 the mixture into an earthen long-neck, or a good 
 
 flafs retort coated, of fuch a fize that it may be but 
 alffull. 
 
 Set this vefiel in a reverberating furnace covered 
 with its dome ; apply a large glafs receiver, hav- 
 ing a fmall hole in its body, flopped with a little 
 lute. Let this receiver be accurately luted to the 
 retort with the fat lute, and the joint covered with a 
 flip of canvas fmeared with lute made of quicklime 
 and the white of an egg. Heat the veflels very gra- 
 dually. The receiver will foon be filled with very 
 denfe red vapours, and drops will begin to diftiU 
 from the nofc of the retort. 
 
 Continue the dtftillation, encreafing the fire a lit- 
 tle when you obferve the drops to follow each other 
 but flowly, fo that above two thirds of a minute 
 pafles between them ; and, in order to let out the re- 
 dundant vapours, open the fmall hole in the re- 
 ceiver from time to time. Towards the end of the 
 operation raife the fire fo as to make the retort 
 red. When you find that, even when the retort is 
 red-hot, nothing more comes over, unlute the re- 
 ceiver, and without delay pour the liquor it con- 
 tains
 
 PRACTICE of CHYMISTRY. 2$% 
 
 tains into a cryftal bottle, and clofe it with a cryftal 
 flopple ground in its neck with emery. This liquor 
 will be of a reddifh yellow colour, fmaking exceed- 
 ingly, and the bottle containing it will be conftant- 
 ly rilled with red fumes like thofe obferved in the 
 receiver. 
 
 BSE RVA? IONS. 
 
 THE Vitriolic Acid having a greater affinity with 
 Fixed Alkalis than with any other fubftance, the 
 Phlogifton excepted, and being in the Vitriol united 
 with a ferruginous bafis, will naturally quit that ba- 
 fia to join with the Fixed Alkali of the Nitre ; the 
 Acid whereof being weaker than the Vitriolic, as 
 we have already obferved on feveral occafions, muft 
 needs be thereby expelled from its bafis. The Ni- 
 tre therefore is decompofed by the Vitriol, and its 
 Acid being fet at liberty, is carried up by the force 
 of the fire. 
 
 Indeed the Nitrous Acid, being thus feparated 
 from its alkaline bafis, might be expected to com- 
 bine with the ferruginous bafis of the Vitriol : but 
 as it has, like all other Acids, much lefs affinity 
 with Metallic fubftances than with Alkalis, even a 
 moderate degree of fire is fufficient to feparate ic 
 from them. Moreover, this Acid hath either no 
 effect, or very little, upon iron that has loft much 
 of its Phlogifton by contracting an union with any 
 Acid i which is the cafe of the ferruginous bafis of 
 Vitriol. 
 
 By the procefs here delivered a very ftrong, per- 
 fectly dephlegmated, and vaftly fmoking Spirit of 
 Nitre is obtained. If the precautions of drying the 
 Nitre and calcining the Vitriol be neglected, the 
 Acid that comes over, greedily attracting the water 
 contained in thefe falts, will be very aqueous, will 
 not fmoke, and will be almoft colourlefs, with a 
 very flight tinge of lemon.
 
 254 - ELEMENTS g 
 
 The fumes of highly concentrated Spirit of Ni- 
 tre, fuch as that obtained by the above procefs, arc 
 light, corrofive, and very dangerous to the lungs 
 being no other than the moft dephlegmated part of 
 the Nitrous Acid. The perfon therefore who un- 
 lutes the veflels, or pours the liquor out of the re- 
 ceiver into the bottle, ought with the greateft cau- 
 tion to avoid drawing them in with his breath j and 
 for that reafon ought to place himfelf fo that a cur- 
 rent of air, either natural or artificial, may carry 
 them off another way. It is alib necdlary that 
 care be taken, during the operation, to give the 
 vapours a little vent every now and then, by open- 
 ing the fmall hole in the recipient ; for they are fo 
 elartic, that, if too clofely confined, they will burft 
 the veffels. 
 
 When the operation is over, you will find a red 
 mafs at the bottom of the retort, caft as it were in 
 a mould. This is a Neutral Salt of the nature of 
 Vitriolated Tartar, refuhing from the union or' the 
 Acid of the Vitriol with the Alkaline bafis of the 
 Nitre. 
 
 The ferruginous bafis of the Vitriol,which is mix- 
 ed with this hilt, gives it the red colour. To fepa- 
 rate it therefrom, you mud pulveriie it, difiblve it 
 in boiling water, and filter the folution feveral times 
 through brown paper , becaufe the ferruginous 
 earth of the vitriol is fo fine, that fome of it will 
 pals through the firft lime. When the folution is 
 very clear, and depofites no fediment, let it be 
 fee to flioot, and it will yield cryftals of Vitriolated 
 Tartar ; to which Chymilb have given the peculiar 
 title of Sal de dttobus* 
 
 In this Captitmortuum we frequently find, befide* 
 the ferruginous earth of Vitriol, a portion of Nitre 
 and Vitriol not decompofed i either becaufe the two 
 falts were not thoroughly mingled, or becaufe tha 
 
 fire
 
 PR ACTIC E of CH YMISTRY. 255 
 
 fire was not railed high enough towards the end of 
 the operation. 
 
 Nitre may alfo be decompofed, and its Acid ob- 
 tained, by the interpofition of any of the other Vi- 
 triols, Alums, Gypfums, Boles, Clays -, in fhorr, 
 by means of any compound in which the Vitriolic 
 Acid is found, provided it have not a Fixed Alkali 
 for its bafis. 
 
 The diftillers of Aqua fortis^ who make large 
 quantities at a time, and who uie the leaft charge- 
 able methods, do their bufinefs by the means of earths 
 impregnated with the Vitriolic Acid ; fuch as Ckrys 
 and Boles. With thefe earths they accurately mix 
 the Nitre from which they intend to draw their Spi- 
 rit : this mixture they put into large oblong earthen 
 pots, having a very [hort curved neck, which en- 
 ters a recipient of the fame matter and form. Thefe 
 veflels they place in two rows oppofite to each other 
 in long furnaces, and cover them over with bricks 
 cemented with Windibr-loarn, which ferves for a 
 reverberatory : then they light the fire in the fur-' 
 nace, making it at nrft very fmall, only to warm 
 the veflels ; after which they throw in wood, and 
 raife the fire till the pots grow quite red-hot, irt 
 which degree they keep it up till the diftillation is 
 entirely finiihed. 
 
 The Acid of Nitre may alfo be Separated from 
 its bafis by means of the pure Vitriolic Acid. For 
 this purpofe the Nitre from which you mea-n to ex- 
 tract the Acid mult be finely pulverized, put into a, 
 glafs retort, and a third of its weight of concen- 
 trated Oil of Vitriol poured on it : the retort miift 
 be placed in a reverberating furnace, and a receiver, 
 like that ufed in the preceding operation, expedi- 
 'tioufiy applied. 
 
 As loon as the Oil of Vitriol touches the Nitre 
 the mixture grows hot, and copious red fumes 
 
 begin
 
 56 ELEMENTS of the 
 
 begin to appear : fome drops of the Acid come over 
 even before the fire is kindled in the furnace. 
 
 On this occafion the fire muft be moderate ; be- 
 caufc the Vitriolic Acid, being clogged by no bafis^ 
 acts upon the Nitre much more brifldy, and with 
 much greater effect, than when it is not pure. 
 
 This operation may be performed by a land heat; 
 which is a fpeedy and commodious way of obtaining 
 the Nitrous Acid. In other reipeets the precautions 
 recommended in the preceding experiment muft be 
 carefully obferved here, both in diftilling the Acid 
 and in taking it out of the receiver. 
 
 The Spirit of Nitre extracted by this method is 
 as ftrong, and fmokes as much, as that obtained by 
 calcined Vitriol, provided the oil of Vitriol made 
 ufe of be well concentrated , but it is generally 
 tainted by the admixture of a fmall portion of the 
 Vitriolic Acid, which, having no bafis of its own 
 to reftrain it, is carried up by the heat before it can 
 lay hold of the bafis of the Nitre. 
 
 There are feveral experiments in Chymiftry that 
 fucceed equally well whether the Nitrous Acid be or 
 be not thus adulterated with a mixture of the Vitri- 
 olic Acid j but there are fome, as we (hall fee, that 
 will not fucceed without a Spirit of Nitre fo mixed. 
 If the Acid be diftilled with a view to fuch expe- 
 riments, it muit be kept as it is. But moft expe- 
 riments require the Spirit of Nitre to be abfoluteljr 
 pure ; and if it be intended for luch, it muft be 
 perfectly cleanfed from the Vitriolic taint. 
 
 This is eafily effected by mixing your Spirit 
 with very pure Nitre, and diftilling it a fecond 
 time. The Vitriolic Acid, with which this Spirit of 
 Nitre is adulterated, coming in contact with a great 
 quantity of undecompofed Nitre, unites with its 
 Alkaline bafis, and cxpells a proportionablequantity 
 of the Nitrous Acid. 
 
 In
 
 PR ACTICE of CH YMISTR Y. 257 
 
 In the retort made ufe of to diftill the Nitrous 
 Acid, by means of the pure Vitriolic Acid, is found 
 a Caput mortuum differing from that left af$er the 
 diftillation of the fame Acid by the interpofition of 
 Vitriol, in as much as it contains no red ferruginous 
 earth. This is a very white faline mafs, moulded 
 in the bottom of the retort : if you pound it, diffolve 
 it in boiling water, and evaporate the folution, it 
 will (hoot into cryftals of Vitriolated Tartar : fome- 
 times alfo it contains a portion of undecompofed 
 Nitre, which moots after the Vitriolated Tartar, 
 becaufe it is much more foluble in water. 
 
 CHAP. III. 
 
 Of the MARINE ACID. 
 
 PROCESS I. 
 
 To extraft Sea-Salt from Sea-Water, and frctii Brine-* 
 Springs. Epfan Salt. 
 
 FILTER the fait water from which you intend 
 to extract the Salt : evaporate it by boiling till 
 you fee on its furface a dark pellicle: this confifts 
 wholly of little cryftals of fait juft beginning to 
 moot : now flacken the fire, that the brine may 
 evaporate more (lowly, and without any agitation. 
 The cryftals, which at firft were very fmall, will 
 become larger, and form hollow truncated pyra- 
 mids, the apices whereof will point downwards, and 
 their bafes be even with the furface of the liquor. 
 
 Thefe pyramidal cryftals are only collections of 
 fmall cubical cryftals concreted into this form. 
 
 VOL. I. 3 When
 
 258 ELEMENTS of the 
 
 When they have acquired a certain magnitude 
 they fall to the bottom of the liquor. When they 
 come to be in fuch heaps as almoft to reach the fur- 
 face of the liquor, decant it from them, and con- 
 tinue the evaporation till no more cryftals of Sea- 
 falt will ihoot. 
 
 OBSERVATIONS. . 
 
 THE Acid of Sea-falt is fcarce ever found, either 
 in Sea-water or in the earth, otherwife than united 
 with a fixed Alkali of a particular kind, which is 
 its natural bafis ; and consequently it is in the form 
 of a Neutral Salt. This Salt is plentifully difiblved 
 in the waters of the ocean, and when obtained 
 therefrom bears the name of Sea-Salt. It is alfo 
 found in the earth in vaft cryftalline maflcs, and is 
 then called Sal-Gem : fo that Sea-falt and Sal-Gem 
 are but one and the fame fort of Salt, differing 
 very little from each other, except as to the places 
 where they are found. 
 
 In tl^e earth are alfo found fprings and foun- 
 tains, whofe waters are ftrong brines, a great deal 
 of Sea-Salt being difiblved in them. Thele fprings 
 either rife directly from the Sea, or run through 
 fome mines of Sal-Gem, of which they take up a 
 quantity in their pafTage. 
 
 As the fame, or at lead nearly the fame, quantity 
 of Sea-falt will continue diffolved in cold water as 
 boiling water will take up, it cannot (hoot, as Nitre 
 does, by the mere cooling of the water in which it 
 is diflblved: it cryitallizes only by the means of 
 evaporation, which continually lefiens the propor- 
 tion of the water to the Salt ; fo that it is always 
 capable of containing juft fo much the lefs Sea-fak 
 the more there is cryftallized. 
 
 The brine mould not boil after yon perceive the 
 pellicle of little cryftals beginning to form on its fur- 
 face j for the calmnefs of the liquor allows them to 
 
 form
 
 PRACTICE of CHYMIS TRY. 
 
 Form more regularly, and become larger. Nor 
 after this mould the evaporation be hurried on too 
 faft , for a faline cruft would form on the liquor, 
 which, by preventing the vapours from being car- 
 ried off, would obftruct the cryftallization. 
 
 If the evaporation be continued after the liquor 
 ceafes to yield any cryftals of Sea- fait, other cryftals 
 will be obtained of an oblong four-fided form, 
 which have a bitter tafte, and are almoft always 
 moift. This fort of Salt is known by the name of 
 Epfom Salt, which it owes to a fait fpring in Eng- 
 land, from the water of which it was firft extract- 
 ed. This Salt, or rather faline compound, is a con- 
 geries of Glauber's Salt and Sea-falt, in a manner 
 confounded together, and mixed with fome of the 
 Mother of Sea-falt, in which is contained a kind of 
 bituminous matter. Thefe two Neutral Salts, 
 which conftitute the Epfom Salt, may be eafily fe- 
 parated from each other, by means of cryftalliza- 
 tion only. Epfom Salt is purgative and bitter; 
 and therefore named Sal Catbarticum Amarum^ or 
 bitter purging Salts. 
 
 There are different methods ufed in great works 
 for obtaining Sea-falt out of water in which it is 
 difiblved. The fimpleft and eafieft is that praclifed 
 in France, and in all thofe countries which are not 
 colder. On the fea fliore they lay out a fort of broacj 
 lhallow pits, pans, or rather ponds, which the fea 
 fills with the tide of flood. When the ponds are 
 thus filled, they (lop their communication with the 
 fea, and leave the water to evaporate by the heat 
 of the fun ; by which means all the Salt contained in 
 it neceffarily cryftallizes. Thefe pits are called 
 BnU Ponds. Salt can be made in this way in the 
 fummer-time only ; at leaft in France, and other 
 countries of the fame temperature : for during the 
 winter, when the fun has lets power and rains are 
 frequent, this method is not practicable. 
 
 S 2
 
 26o ELEMENTS of the 
 
 For this reafon, as it often rains in the province 
 of Normandy, the inhabitants take another way to 
 extract Salt from fea-watcr. The labourers em- 
 ployed for this purpofe raiie heaps of fand on the 
 Ihore, fo that the tide waters and drenches them 
 when it flows, and leaves the land dry when it ebbs. 
 During the interval between two tides of flood the 
 fun and the air eafily carry off the moifture that 
 was left, and fo the land remains impregnated with 
 all the Salt that was contained in the evaporated 
 water. 1'hus they let it acquire as much lalt as it 
 can by feveral returns of flood, and then warn it 
 out with frefh water, which they evaporate over a 
 fire in leaden boilers. 
 
 To obtain the bait from brine- fprings, the water 
 need only be evaporated : but as feveral of thcie 
 fprings contain too little Salt to pay the charges 
 that would be incurred, if the evaporation were 
 effected by the force of fire only, the manufacturers 
 have fallen upon a lefs expenfive method of getting 
 rid of the greateft part of the water, and preparing 
 the brine for cryftallization, in much lefs time, 
 and with much lei's fire, than would otherwife have 
 been necefiary. 
 
 The method confifts in making the water fall 
 from a certain heighth on a great many fmall fpars 
 of wood, which divide it into particles like rain. 
 This is performed under fheds open to all the winds, 
 which pafs freely through this artificial fhower. By 
 this means the water prefents to the air a great ex- 
 tent of furface, being indeed reduced almoft entirely 
 to furface, and the evaporation is carried on with 
 great eafe and expedition. The water is raifed by 
 pumps to the heighth from which it is intended to 
 tall *. 
 
 PRO- 
 
 * The Marquis de Montalembert, in a Memoir read before 
 the Academy of Sciences, propoies a new method of effecting, 
 thefe evaporations, together with fomc confiderable improve- 
 ment*
 
 PR ACTICE of CHYMISTRY. 261 
 
 PROCESS II. 
 
 Experiments concerning the decompofttion of Sea-falt, 
 by means of the Phlogifton. Kunckel's Pbofyhorus. 
 
 pure urine that has fermented five or fix 
 days take a quantity in proportion to 
 " the quantity of Phofphorus you intend to make : 
 " it requires about one third part of a hogmead to 
 " make a dram of Phofphorus. Evaporate it in 
 " iron pans, till it become clotted, hard, black, 
 " and nearly like chimney-foot -, at which time it 
 " will be reduced to about a fixtieth part of its 
 " original weight before evaporation. 
 
 " When the urine is brought to this condition 
 " put it in feveral portions into fo many iron pots, 
 " under which you mud keep a pretty brifk fire 
 " fo as to make their bottoms red, and ftir it in- 
 " ceffantly till the volatile fait and the fetid oil be 
 *' almoft wholly difilpated, till the matter ceafe to 
 " emit any fmoke, and till it fmell like peach-blof- 
 " foms. Then put out the fire, and pour on the 
 " matter, v/hich will now be reduced to a powder, 
 " fomewhat more than twice its weight of warm wa- 
 " ter. Stir it about in this water, and leave it to 
 " foak therein for twenty-four hours. Pour off the 
 " water by inclination ; dry the drenched matter, 
 " and pulverize it. The previous calcination carries 
 " off from the matter about a third of its weight, 
 " and the lixiviation wathes out half the remainder. 
 
 " With what remains thus calcined, warned, 
 " and dried, mix half its weight of gravel, or yel r 
 
 mcnts in the firuflure and difpofition of the buildings necefiary 
 for that purpoie. They are called by the French Bailments de 
 Graduation-^ which may properly enough be rendered Brine- 
 koufei. 
 
 S' a " low
 
 ::62 ELEMENTS?/ the 
 
 " low freeftone rafped, having fiftcd out and 
 " thrown away all the fineft particles. River fund 
 " is not proper on this occafion, becaufe it flies in 
 " a hot fire. Then add to this mixture a fixteenth 
 <c part of its weight of charcoal, made of beech, or 
 " of any other wood except oak, becaufe that alfo 
 " flies. Moiften the whole with as much water as 
 " will bring it to a ftiff pafte, by working and 
 ** kneading it with your hands : now introduce it 
 " into your retort, taking care not to daub its 
 ; neck. The retort muft be of the beft earth, 
 * c and of fuch a fi'ze, that when your matter is in 
 " it, a full third thereof fhall ftill be empty. 
 
 " Place your retort, thus charged, in a reverbe- 
 " rating furnace, fo proportioned, that there may 
 " be an interval of two inches all round between the 
 " fides of the furnace and the bowl of the retort, 
 < even where it contracts to form the neck, which 
 <e mould ftand inclined at an angle of fixty degrees. 
 " Stop all the apertures of the furnace, except the 
 " doors of the fire-place and afh-hole. 
 
 " Fit on to the retort a large glafs ballon two 
 " thirds full of water, and lute them together, as 
 " in diftilling the Smoaking Spirit of Nitre. In 
 ^ the hinder part of this ballon, a little above the 
 * c furface of the water, a fmall hole muft be bored, 
 " This hole is to be flopped with a fmall peg of 
 *' birch-wood, which rnurt flip in and out very ea- 
 ^ fily, and have a fmall knob to prevent its falling 
 " into the ballon. This peg is to be pulled out 
 <c from time to time, that by applying the hand 
 * c to the hole it may be known whether the air, 
 " rarefied by the heat of the retort, iffucs out with 
 " too much or too little force. 
 
 " If the air rufhes out with too much rapidity, 
 ^ c and with a hitting noife, the door of the am-hole 
 " muft be entirely fhut, in order to flacken the fin . 
 " If it do not ftrike pretty frnartly againft the hand, 
 
 *' that
 
 P R A c T i c E ^f C H Y M i s T R Y. 26* 
 
 that door mud be opened wider, and large coals 
 thrown into the fire-place to quicken the fire irn-f 
 mediately. 
 
 " The operation ufually lafts four and twenty 
 hours ; and the following figns fhew that it will 
 fucceed, provided the retort refift the fire. 
 " You muft begin the operation with putting 
 fome unlighted charcoal in the afh-hole, and a 
 little lighted charcoal at the door thereof, in or- 
 tier to warm the retort very flowly. When the 
 whole is kindled, pufh it into the afh-hole, and 
 dole the door thereof with a tile. This moderate 
 heat brings over the phlegm of the mixture. 
 The fame degree of fire muft be kept up four 
 hours, after which fome coals may be laid on 
 the grate of the fire-place, which the fire under- 
 neath will kindle by degrees. With this lecond 
 heat brought nearer the retort, the ballon grows 
 warm, and is filled with white vapours, which 
 have the fmell of fetid oil. In four hours after, 
 this veflel will grow cool and clear-, and then 
 you muft open the door of the afh-hole one inch, 
 throw frefh coals into the fire-place every three 
 minutes, and every time fhut the door of it, left 
 the cold air from without fliould ftrike againft 
 the bottom of the retort and crack it. 
 " When the fire has been kept up to this degree 
 for about two hours, the infide of the ballon be* 
 gins to be netted over with a volatile fait of a 
 fingular nature, which cannot be driven up but 
 by a very violent fire, and which fmells pretty 
 itrong of peach-kernels. Care muft be takea 
 that this concrete fait do not ftop the little hole in 
 the ballon : for in that cafe it would burfc, the 
 retort being then red-hot, and the air exceedingly 
 ..rarefied. The water in the ballon, being heated 
 by the vicinity of the furnace, exhales vapours 
 84 " which
 
 264 ELEMENTS of the 
 
 44 which difiblve this fprigp;ed fait, and the ballon 
 44 clears up in half an hour after ir has ceafccl rifine;. 
 
 41 In about three hours from the firft appearance 
 " of this ialt, the ballon is again filled with new v.i- 
 44 pours, which fmtll like Sal Ammoniac thrown 
 44 upon burning coals. They condenie on the fides 
 44 of the receiver into a 1'alt which is not branched 
 <{ like the former, but appears in long perpendi- 
 44 cular ftreaks, which the vapours of the water do 
 44 not difiblve. Thefe white vapours are the fore- 
 " runners of the Phofphorus, and a little before 
 ct they ceafe to rife they lofe their firft fmell of Sal 
 " Ammoniac, and acquire the odour of garlick. 
 
 44 As they afcend with great rapidity, the little 
 44 hole muft be frequently opened, to obferve whe- 
 44 ther the hiding be not too ftrong ; for in that 
 44 cafe it would be neceffary to (hut the door of the 
 " afh-hole quite clofe. Thefe white vapours con- 
 4C tinue two hours. When you find they ceafe 
 41 rifing, make a fmall paflage through the dome, 
 44 by opening fome of its regifters, that the flame 
 44 may juft begin to draw. Keep up the fire in 
 44 this mean Hate till the firft volatile Phofphorus 
 4C begins to appear. 
 
 44 This appears in about three hours after the 
 4t white vapours firft begin to rife. In order to dif- 
 44 cover ir, pull out the little birchen peg once 
 * 4 every minute, and rub it againft fome hot pare 
 44 of the furnace, where it will leave a trail of 
 4 ' light, if there be any Phofphorus upon it. 
 
 44 Soon after you obferve this fign, there will 
 44 ifiue out through the little hole of the ballon a 
 44 ftream of bluilh light, which continues of a 
 * 4 greater or fhorter extent to the end of the opera- 
 44 tion. This ftream or fpout of light does not burn. 
 44 If you hold your finger againft it for twenty or 
 4 ' thirty feconds, the light will adhere to it ; and if 
 
 4C you
 
 PR ACTICE 0/*CHYMisTRY. 265 
 
 c * you rub that finger over your hand, the light 
 " will befmear it, and render it luminous. 
 
 " But from time to time this ftreamer darts out 
 " to the length of feven or eight inches, fnapping 
 " and emitting fparks of lire -, and then it burns 
 " all combuftible bodies that come in its way. 
 " When you obferve this, you mult manage the 
 " fire very warily, and iliut the door of the afh- 
 " hole quite clofe, yet without ceaiing to throw 
 " coals into the fire-place every two minutes. 
 
 " The Volatile Phoiphorus continues two hours ; 
 " after which the little fpout of light contracts to 
 " the length of a line or two : and now is the time 
 ft for pulhing your fire to the utmoft : immediately 
 " fet the door of the afh-hole wide open, throw bil- 
 " lets of wood into it, unftop all the regifters of the 
 " reverberatory, iupply the fire-place with large 
 " coals every minute : in fhort, for fix or feven 
 * c hours all the infide of the furnace muft be kept 
 " of a white heat, fo that the retort (hall not be 
 " diftinguifhable. 
 
 " In this fierce extremity of heat the true Phof- 
 " phorus diftills like an oil, or like melted wax : 
 " one part thereof floats on the water in the reci- 
 " pient, the other falls to the bottom. At laft, 
 41 the operation is known to be quite over when the 
 *' upper part of the ballon, in which the volatile 
 " Phofphorus appears condenfcd in a blackifh film, 
 * e begins to grow red : for this fhews that the 
 " Phofphorus is burnt where the red fpot appears. 
 " You muft now flop all the regifters, and fruit all 
 " the doors of the furnace, in rrder to fmother the 
 ' fire ; and then clofe up the little hole in the bal- 
 " Ion with fat lute or bees-wax. In this condition 
 ^ c the whole muft be left for two days , becaufe 
 " the veflels muft not be feparated till they are 
 " perfedlly cold, left the Phofphorus fhould take 
 f 4 fire. 
 
 " As
 
 266 ELEMENTS of the 
 
 " As foon as the fire is out, the ballon, which 
 " is then in the dark, prefent* a mod agreeable 
 " object : all the empty part thereof above the wa- 
 " tcr feems filled with a beautiful blue ]"; 
 " which continues for feven or eight hours, or as 
 " long as the ballon keeps warm, never difappear- 
 " ing till it is cooled. 
 
 " When the furnace is quite cold take out the 
 * vefiVls, and fepurate them from each other as 
 " neatly as poflible. With a linen cloth wipe away 
 " all the black (luff you find in the mouth of the 
 ' ballon , for if that filth mould mix with the Phof- 
 " phorns, it would hinder it from being tranfpa- 
 " rent when moulded. This mufl be done with 
 " great expe<.i;iio;i : after which pour into the bal- 
 " Ion two or three quarts of cold water, to acce]e- 
 ' rate the precipitation of the Phol phorus that 
 *' fwims at top. Then agitate the water in the bal- 
 " Ion, to rinte out all the Phofphorus that may 
 " flick to the fides j pour out all the water thus 
 " fliaken and turbid, into a very clean earthen pan, 
 ct and kt it (land till it grows clear. Then decant 
 " this firft ufelefs water, and on the blackifh iedi- 
 " ment, left at the bottom of the pan, pour fome 
 " boiling water to melt the Phofphorus \ which 
 " thereupon unites with the fuliginous matter, or 
 volatile Pholphorus, that precipitated with it, both 
 " together forming a mafs of the colour of flate. 
 * When this v/ater, in which you have melted the 
 " Phofphorus, is cool enough, take out the Phof- 
 ** phoru?, throw it into cold water, and therein 
 tl break it into little bits in order to mould it. 
 
 *' Then take a mar,ras, having a long neck 
 ' fjmewhat wider next the body than at its 
 " mouth : cut off half the body, fo as to make a 
 " funnel of the neck-part, the fmaller end of which 
 " inuft be (lopped with a cork. The firft mould 
 " being thus prepared, plunge it endwife, with its 
 
 *' mouth
 
 PRACTICE ?/' CHYMISTRY. 267 
 
 ** mouth uppermoft, in a vefiel full of boiling wa- 
 " ter, and fill it with that water. Into this funnel 
 " throw the little bits of your flate-like mafs, 
 " which will rnelt again in this hot water, and fall 
 " fo melted to the bottom of the tube. Stir this 
 " melted matter with an iron wire, to promote the 
 " feparation of the Phofphorus from the fuliginous 
 " matter with which it is fouled, and which, being 
 ' lefs ponderous than the Phofphoru?, will gra- 
 " dually rife above it towards the upper part of 
 " the cylinder. 
 
 " Keep the water in the veflel as hot as at firft, 
 " till on taking out the tube you fee the Phofpho- 
 " rus clean and tranfparent. Let the clear tube 
 ft cool a little, and then let it in cold water, where 
 " the Phofphorus will congeal as it cools. When 
 * it is perfectly congealed, pull out the cork, and 
 " with a fmall rod, near as big as the tube, pufh 
 " the cylinder of Phofphorus towards the mouth 
 * f of the funnel, where the feculency lies. Cut 
 " off the black part of the cylinder, and keep it 
 " apart : for when you have got a quantity thereof, 
 " you may melt it over again in the fame manner, 
 " and feparate the clean Phofphorus which it ftill 
 *' contains. As to the reft of the cylinder which 
 tc is clean and tranfparent, if you intend to mould 
 " it into fmaller cylinders, you may cut it in 
 " flices, and rnelt it again by the help of boiling 
 " water in glafs tubes of fmaller dimenfions." 
 
 OB SERFA? ION S. 
 
 THIS procefs for making Phofphorus is copied 
 from the Memoirs of the Academy of Sciences for 
 the Year 1737 , where it is defcribed by M. Hellot, 
 with fo much accuracy, clearnefs, and precifion x 
 that I thought I could not do better than tranfcribe 
 it, without departing from the author's own expref- 
 for the fake of fuch as may not have tbofe 
 
 Memoirs.
 
 s68 ELEMENTS of the 
 
 Memoirs. We fhall take occafion, in thefe obferva* 
 tions, to point out fomeefTentialcircumftances which 
 I have omitted in thedefcription of theProcefs, that 
 I might not break the connection between the phe- 
 nomena that happen in the courfe of this experiment. 
 
 It is proper to obferve, in the firft place, that one 
 of the moft ufual caufes of mifcarriage in this ope- 
 ration is a defedl of the requifite qualities in the re- 
 tort employed. It is abfolutely neceffary to have 
 that vefTel made of the bed earth, and fo well made 
 that it fhall be capable of redding the utmoft vio- 
 lence of fire, continued for a very long time ; as 
 appears by the defcription of the procefs. The 
 retorts commonly fold by potters, and other earthen 
 ware-men ; are not fit for this operation ; and Mr. 
 Hello: was obliged to fend to Hefle-Caflel for fuch 
 as he wanted. 
 
 \Ve mall, in the fecond place, obferve with 
 M. Hellot that, " before you let your retort in 
 " the furnace, it is proper to make an eflay of your 
 " matter, to lee if there be reafon to hope for fuc- 
 " cefs. For this purpofe put about an ounce there- 
 " of into a fmali crucible, and heat it till the veflel 
 " be red. The mixture, after having fmoked, 
 *' ought to chop or crack without puffing up, or 
 *' even rifing in the leaft. From thefc cracks will 
 " iflue undulating flames, white and bluifh, dart- 
 " ing upwards with rapidity. This is the firft vo- 
 " latile Phofphorus, which occafions all the dan- 
 *' ger of the operation. When thefe firft flafhes 
 " are over, increale the heat of your matter by 
 " laying a large live coal upon the crucible. You 
 " will then fee the fecond Phofphorus, like a lu- 
 " minous, fteady vapour, of a colour inclining to 
 " violet, covering the whole furface of the matter : 
 " it continues for a very long time, and diftufes a 
 *' fmell of garlick, which is the diftinguiihing 
 " odour of the Phofphorus you are lecking. 
 
 44 When
 
 PRACTICE O/*CHYMISTRY. 269 
 
 " When this luminous vapour is entirely gone, 
 " pour the red hot matter out of the crucible upon 
 " an iron plate. If you do not find one drop of fait 
 " in fufion, but that, on the contrary, the whole 
 " falls readily into powder, 'tis a proof that your 
 ** matter was fufficiently lixiviated, and that ic 
 " contains no more fixed Salt, or Sea-falt, if you 
 " will, than is requifite. If you find on the plate 
 " a drop of fait coagulated, it mews that there is 
 " too much left in, and that there is danger of 
 " your mifcarrying in the operation ; becaufe the 
 " redundant fait would corrode, and eat through 
 " the retort. In this cafe your matter muft be 
 " warned again, and then fufficiently dried." 
 
 Our third obfervation mall be concerning the 
 furnace proper to be employed in this operation. 
 This furnace muft be fo conftrufted, that within 
 a narrow compafs it may give a heat at leaft equal 
 to that of a glafs-houfe furnace, or rather greater, 
 efpecially during the laft feven or eight hours of the 
 operation. M. Hellot in his Memoir gives an ex- 
 acl: defcription of fuch a furnace. 
 
 " As certain accidents may happen in the courfe 
 *' of the operation, fome precautions are to be taken 
 " againft them. For inftance, if the ballon mould 
 " break while thePhofphorus is diftilling, and any 
 " of it fhould fall on combuftible bodies, it would 
 " let them on fire, and probably burn the laborato- 
 " ry, becaufe it is not to be extinguimed without the 
 " greateft difficulty. The furnace muft therefore be 
 " erected under fome vault, or upon a bed of brick- 
 " work raifed under fome chimney that draws well : 
 " nor muft any furniture or utenfil of wood be left 
 " near it. If a little flaming Phofphorus mould fall 
 " on a man's legs or hands, in lefs than three mi- 
 " nines it would burn its way to the very bone. In 
 *' fuch a cafe nothing but urine will ftop its progrefs.
 
 70 ELEMENTS of the 
 
 " If the retort crack while the Phofphorus is 
 " diftilling, there is an unfuccefsful end of your 
 ** operation. It is eafy to perceive this by the (link 
 " of garlick which you will fmell about the fur- 
 " nace ; and moreover, the flame that ifiues thro' 
 " the apertures of the reverberatory will be of a 
 " beautiful violet colour. The Acid of Sea-falt 
 " always gives this colour to the flame of fuch 
 " matters as are burnt along with it. But if the 
 " retort break before the Phofphorus hath made 
 " its appearance, its contents may be faved by 
 u throwing a number of cold bricks into the fire- 
 ' place, and upon them a little water to quench 
 " the fire at once." All thefe ulcful oblervaiions 
 we owe alfo to M. Hellot. 
 
 The Phofphorus here defcribed was firft difcover- 
 td by a citizen of Hamburgh named Brandt, who 
 worked upon urine in fearch of the Philofopher's 
 ftone. Afterwards two other fkilful Chymifts, who 
 knew nothing more of the procefs than that Phof- 
 phorus was obtained from urine, or in general from 
 the human body, likewife endeavoured to difcover 
 it i and each of them fcparately did actually make 
 the difcovery. Thefe two Chymifts were Kunckel 
 and Boyle. 
 
 The former perfected the difcovery, and found 
 out a method of making it in confiderablequantitiesr 
 at a time ; which occafioned it to be called Ktincfars 
 Pbcfpbcrus. The other, who was an Engliih gen- 
 tleman, had not time to bring his difcovery to per- 
 fection, and contented himfelf with lodging a vou- 
 cher of his having diicovered it in the hands of the 
 Secretary of the Royal Society of London, who 
 gave him a certificate thereof. 
 
 " Though Brandt, fays M. Hellot, ^Yho had be- 
 
 " forethisfold his fecret to a Chymift named Krafir, 
 
 " fold it afterwards to icveral other perfons, and 
 
 " even at a very low rate ; and though Mr. Boyle 
 
 i publiih-
 
 PR ACTICE of CHYMISTRY. 271 
 
 * : publifhed the procefs for making it; yet it is ex- 
 *' tremely probable that both of them kept in their 
 " own hands the mafter-key; I mean, tbeparticu- 
 " lar management neceffary to make the operation fuc- 
 " ceed '. for till Kunckel found it out, no other 
 <c Chymift ever made any confiderable quantity 
 *' thereof, except Mr. Godfrey Hankwitz, an 
 <c Englifti Chymift, to whom Mr. Boyle revealed 
 " the whole myftery. 
 
 " Neverthelefs, continues he, we are very far 
 " from alledging that all thole who have defcribed 
 " this operation meaned to impofe upon the world : 
 " but we conceive that moft of them having ob- 
 " fervcd luminous vapours in the ballon, and fome 
 " fparks about the juncture of the vefTels, were 
 " contented with thole appearances. And thus it 
 " came to pafs, that, after Kunckel and Boyle 
 " died, Mr. Godfrey Hankwitz was the only Chy- 
 " mift that could fupply Europe therewith ; on 
 " which account it is likewife very well known by 
 " the name of Engli/b Phofphorus" 
 
 Almoft all theChymiftsconfider Phofphorus as a 
 fubftance confifting of the Acid of Sea-falt com- 
 bined with the Phlogifton, in the fame manner as 
 Sulphur confifts of the Vitriolic Acid combined 
 with the Phlogifton. This opinion is founded oi> 
 the following principles. 
 
 Firft, Urine abounds with Sea-falt, and contains 
 alfo a great deal of Phlogifton : now thefe are the 
 ingredients of which they conjecture Phofphorus to 
 be competed. 
 
 Secondly, Phofphorus has many of the properties 
 of Sulphur; fuch as being foluble in oils , melting 
 with a gentle heat ; being very combuftible; barn- 
 ing without any foot ; giving a vivid and bluifh 
 flame; and laftly, leaving an acid liquor when 
 burnt: lenfible proofs that it differs from Sulphur 
 in nothing but the nature of its Acid. 
 
 Thirdly,
 
 272 ELEMENTS of the 
 
 Thirdly, this Acid of Phofphorus, being mixed 
 with a folution of filver in Spirit of Nitre, precipi* 
 tates the filver, and this precipitate is a true Lunct 
 cornea, which appears to be more volatile even than 
 the common fort ; as M. Hellot tells us, who made 
 the experiment. This fact proves inconteftably 
 that the Acid of Phofphorus is of the lame nature 
 with that of Sea- fait : for all Chymifts know that 
 the property of precipitating filver in a Luna cornea 
 belongs to the Marine Acid only. 
 
 Fourthly, M. Stahl obierves that, ifSea-fakbe 
 cad on live coals, they inftantly burn with great acti- 
 vity ; then they emit a very vivid flame, and are 
 much foonerconlumed than if none of this Salt had 
 touched them ; that Sea-falt in fubftance, which 
 will bear the violence of fire a confiderable time 
 when fufed in a crucible, without fultaining any fen- 
 fible diminution, yet evaporates very quickly, and 
 is reduced to white flowers, by the immediate con- 
 tact of burning coals : and laftly, that the flame 
 which rifes on this occafion is of a blue colour in- 
 clining to violet, efpecially if it be not thrown di- 
 rectly on the coals thcmfelves, but kept in fufion 
 amid (I burning coals, in a crucible fo placed that 
 the vapour of the Salt may join with the enflamed 
 Phlogifton as it riles from the coals. 
 
 Thefe experiments of Mr. Stahl's prove that the 
 Phlogifton acts upon the Acid of Sea-falt, even 
 while it is combined with its alkaline bafis. The 
 flame that appears on this occafion may be confi- 
 dered as an imperfect Phofphorus : and indeed its 
 colour is exactly like that of Phofphorus. 
 
 All the facts above related evince that the Acid 
 of Phofphorus is akin to that of Sea-falt , or rather 
 that it is the very fame. But there are other facts 
 which prove that this Acid undergoes fomc change 
 at lead, fome peculiar preparation, before it enters 
 into the cornpoimon of a true Phofphorus, and that, 
 
 when
 
 PRACTICE ^GHYMISTRY. 27 j 
 
 tohen extricated therefrom by burning, it is not a 
 pure Acid of Sea-falt, but is ftill adulterated with 
 a mixture of fome other fubftance, which makes it 
 considerably different from that Acid. For thefe 
 obfervations we are obliged to M. Marggraff, of 
 the Academy of Sciences at Berlin, a celebrated 
 Ghymift. I mail prefcntly give an account of his 
 principal experiments as fucciriclly as poflible. 
 
 M. Marggraff hath allb publifhed a procefs for 
 making Phofphorus, and allures us that by means 
 thereof we may obtain in lefs time, with lefs heat, 
 Jefs trouble, and lefs expence, a greater quantity 
 of Phofphorns than by any other method. His 
 operation is this : 
 
 He takes two pounds of Sal Ammoniac in pow- 
 der, which he mixes accurately with four pounds of 
 Minium. This mixture he puts into a glafs retort, 
 and with a graduated fire draws off" a very (harp* 
 volatile, urinous fpirit. 
 
 We obierved in our theoretical Elements that fome 
 metallic iubftances have the property of decompo- 
 fing Sal Ammoniac, and feparating its volatile Al- 
 kali-, concerning which phenomenon we there gave 
 our opinion. Minium, which is a calx of lead, is one 
 of thofe metallic fubftances. In this experiment it 
 decompofes the Sal Ammoniac, and ieparates its vo- 
 latile Alkali; what remains in the retort is a com- 
 bination of the Minium with the Acid of the Sal 
 Ammoniac, which is well known to be the fame 
 with the Marine Acid ; and confequently the refi- 
 due of this operation is a fort of Plumbum corneum. 
 
 The quantity thereof is four pounds eight ounces, 
 Of this he mixes three pounds with nine or ten 
 pounds of urine, that has ftood putrefying for two 
 months, evaporated to the confidence of honey. 
 Thefe he mixes by little and little in an iron pan 
 over the fire, ftirring the mixture from time to time. 
 Then he adds half a pound of charcoal duft, and 
 
 VOL. I, T evapo-
 
 174 E L EM E N T s of the 
 
 evaporates the matter, kept continually ftirring, till 
 the whole be brought to a black powder. He nexc 
 dittills the mixture in a glafs retort with degrees of 
 tire, which he raiies towards the end lo as to make 
 the retort red-hot, in order to expel all the urinous 
 fpirit, fuperfluous oil, and ammoniacal fait. The 
 diftillation being finiihed, there remains nothing in 
 the retort but a very friable caput wortxum. 
 
 This remainder he pulverifes a ( (r ain, and throws a 
 pinch thereof on live coals, thereby to dilcover 
 whether or no the matter be rightly prepared, and 
 in order, tor yielding Phofphorus. If it be fo, it 
 prefently emits an arienical odour, and a blue un- 
 dulating flame, which pafiTes over the furface of the 
 coals like a wave. 
 
 Being thus a flu red of the fuccefs of his operation, 
 he puts one hah of his matter, in three equal parts, in- 
 to three fmall earthen German retorts, capable of 
 holding about eighteen ounces 01 water a-piece, 
 Thele three retorts, none of which is above three 
 quarters full, he places together in one reverberator/ 
 furnace, built much like thofewe havedefcribed,' 
 < ept that it is fo conftructed as *o hold the three re- 
 's ciiipoied in one line. To each retort he lutes a 
 recipient fomething more than half full of water, or- 
 dering the whole in luch a manner, that the notes 
 of his retorts almoft touch the furface of the water. 
 He begins the dillillation with warming the retorts 
 flowly, for about an hour, by a gentle heat. When 
 At time is clapled he raiies tire fire gradually, lo 
 that in half an hour more the coals begin to touch 
 the bottoms of the retorts. He continues throwing 
 coals into the furnace by little and little, till they rife 
 half way the heighth of the retorts -, and in this he 
 employs another half hour. I .aftly, in the next half 
 hour he raifes the coals above the bowls of the retorts. 
 Then the Phofphorus begins to afcend in clouds ; 
 on this he in-ftantly increafcs the heat of the fire as 
 
 much
 
 PRACTICE cf CHYMISTRY. 275 
 
 much as poffibJe,, filling the furnace quite up with 
 coals, and making the retorts very red. This de- 
 gree of fire caufes the Phofphorus to diftill in drops 
 which fall to the bottom of the water. He keeps 
 up this intenfe heat for an hour and half, at the 
 end of which the operation is finifhed , fo that it 
 lafts but four hours and a half in all : nay, he fur- 
 ther afiures us that an artift, well verfed in managing 
 the fire, may perform it in four hours only. In 
 the fame manner he di dills the fecond moiety of 
 his mixture in three other fuch retorts. 
 
 The advantage he finds in making ule of feveral 
 fmall retorts,, inftead of a fingle large one, is that 
 the heat penetrates them with more eafe, and the 
 operation is performed with lefs fire, and in Ids 
 time. He purifies and moulds his Phofphorus much 
 in the fame manner as M. Hellot does. From the 
 quantity of ingredients above-mentioned, he obtains 
 two ounces and a half of fine cryftalline moulded 
 Phofphorus, 
 
 M. Marggraff confidering, as a confequence of 
 the experiments above related, that a highly con- 
 centrated Acid of Sea-lalt contributes greatly to- 
 wards the formation of Phofphorus, proceeded to 
 try feveral other experiments, in which he employed 
 that Acid in a ftate of combination with other 
 bafes. He mixed, for inftance, an ounce of Luna 
 cornea with an ounce and half of putrefied and in- 
 ipiflated urine, and from the mixture obtained a 
 very beautiful Phofphorus. 
 
 In more, the feveral experiments mentioned hav- 
 ing thoroughly perfuaded him that the Acid of Sea- 
 falt, provided it were highly concentrated, would 
 combine with the Phlogiiton as readily as the Vitri- 
 olic Acid does, he refolved to try whether he could 
 not make Phofphorus with matters containing that 
 Acid and the Phlogifton, without making ufe of 
 any urine. 
 
 T 2 With
 
 276 ELEMENTS of the 
 
 With this view he made a great number of dif- 
 ferent trials, wherein he employed Sea-falt in fub- 
 (lance, Sal Ammoniac, Plumbum corneum, Luna 
 cornea, fixed Sal Ammoniac, otherwile called Oil of 
 Lime. Thefe feveral fubftances, all of which con- 
 tain the Acid of Sca-falt, he mixed with lundry 
 matters abounding in Phlogifton, different vegetable 
 coals, and even animal matters, fuch as the oil of 
 hartfhorn, human blood, &c. varying the propor- 
 tions of thele Jubilances many different ways, with- 
 out ever being able to produce a finale atom of 
 Phofphorus : which gave this able Chymift juft 
 caufe to fufpect that the Marine Acid, while pure 
 and crude, is not capable of combining with the 
 Phlogifton in the manner requifite to form a Phof- 
 phorus ; that for this purpofe it is neceffary the Acid 
 fhould have contracted a previous union with fome 
 other matter -, and that the Acid found in urine 
 hath probably undergone the neceffary change. 
 M. Marggraff is of opinion that the matter, which 
 by its union renders the Marine Acid capable of 
 entering into the competition of Phofphorus, is a 
 fort of exceedingly fubtile verifiable earth. The 
 experiments he made upon the Acid of Phofphorus 
 will fhew that his notion is not altogether ground- 
 lefs. M. Marggraff having let fotne urine, evapo- 
 rated to the conliilence of honey, (land quiet in a 
 cool place, obtained from it, by cryftallization, a 
 Salt of a fingular nature. By diflilling this urine 
 afterwards, he fatisfied himfelf that it yielded him 
 much lefs Phofphorus than urine from which no 
 Salt had been extracted ; and as it cannot be entirely 
 deprived of this Salt, he thinks that the Imall quan- 
 tity of Phofphorus, which this urine yielded him, 
 came from the Salt that was Hill left in it. 
 
 Further, he diftilled this Salt feparatcly with lamp- 
 black, and obtained from it a confiderable quantity 
 of very fine Phofphorus. He even mixed Luna cor- 
 nea
 
 PRACTICE of CFIYMISTRY. 277 
 
 with this Salt, in order to fee whether it would 
 not increafe the quantity of his Phofphcrus; but 
 without fuccefs : whence he concluded that in this 
 Saline matter refides the true Acid that is fit to en- 
 ter into the compofition of Phofphorus. This opi- 
 nion is confirmed by feveral experiments on the 
 Acid of Phofphorus, which he found to have fome 
 properties refembling thofe of this Salt. 
 
 The Acid of Phofphorus feems to be more fixed 
 than any other : and therefore if you would lepa- 
 rate it, by burning, from the Phlogilton with which 
 it is united, there is no occafion for fuch an appa- 
 ratus of vefiels as is employed for obtaining the Spi- 
 rit of Sulphur. For this Acid will remain at the 
 bottom of the veflel in which you burn your Phof- 
 phorus : iadeed, if it be urged by the force of fire, 
 us moft fubtile part evaporates, and the remainder 
 appears in the form of a vitrified matter. 
 
 This Acid effervefces with fixed and volatile Alka- 
 lis, and therewith forms Neutral Salts ; but very dif- 
 ferent from Sea-fak, and from Sal- Ammoniac. That 
 which has a fixed Alkali for its bafis does not 
 crackle when thrown on burning coals ; but fwells 
 and vitrifies like Borax. That which has a volatile 
 Alkali for its bafis (hoots into long pointed cryftals -, 
 and, being urged by fire in a retort, lets go its 
 volatile alkali, a vitrified matter remaining behind. 
 This Salt is like that abovementioned, as obtained 
 from urine and yielding Phofphorus. 
 
 It appears from the experiments adduced, that 
 the Acid of Phofphorus tends always to vitrifica- 
 tion , which proves that it is not pure, and gave 
 M. Marggraff caufe to think that it is altered by 
 the admixture of a very fubtile verifiable earth, 
 v M. Marggraff alfo obtained Phoiphorus from fe- 
 veral vegetable fubftances which we ufe every day 
 for food. This gives him occafion to conjecture that 
 T 3 the
 
 278 ELEMENTS of the 
 
 the Salt requifite to the formation of Phofphorus 
 Is in vegetables, and pafles from thence Into the 
 animals that feed upon them. 
 
 Laftly, he concludes his dificrtation by informing 
 us of a very important truth, viz. That the Acid 
 obtained from Phofphorus, by burning it, will ferve 
 to form Pholphorus anew ; for which purpofe it 
 need only be combined with fome charred coal, 
 fuch as lamp-black, and diftilled. 
 
 From what hath been faid on this fubjeft it is 
 plain the Chymifh have a great many curious and 
 interefting enquiries to make concerning Phofpho- 
 rus, and particul.tt ly concerning its Acid. 
 
 I (hall conclude this article with an account of 
 certain properties of Pholphorus which I have not 
 yet mentioned. 
 
 Phofphorus diflblves by lying expofed to the air, 
 "What water cannot effect, fays M. Hellot, or at 
 leatl requires eight or ten years to bring about, the 
 moifture of the air accomplices in ten or twelve 
 clays -, whether it be that the Phoiphorus takes fire- 
 in the air, and the inflammable part evaporating, 
 almoit entirely, leaves the Acid of the Pholphorus 
 naked, which like all other Acids, when exceedingly 
 concentrated, is very greedy of moitture ; or elfe 
 that the moifture of the air, being water divided 
 into infinitely fine particles, is fo fubtile as to 
 find its way through the pores of the Phofphorus, 
 into which the groifer particles of common water 
 can by no means infmuate themfelves. 
 
 Phofphorus heated by the vicinity of fire, or by 
 being any way rubbed, foon takes lire and burns 
 ixcly. It is foluble in all Oils and in Ether, giv- 
 ing to thpfe liquors the property of appearing lumi- 
 nous when the bottle containing the lolution is open - 
 ed. Being boiled in water, it likewife communicate 
 thereto this luminous quality. M. Morin, Profel- 
 ior at Chaftres, is the author of this obfervation. 
 
 The
 
 PRACTICE of CH YMIS TR Y. 279 
 
 The Lite Mr. Grofle, a celebrated Chymift, of 
 the Academy of Sciences, obfervcd that Phofplu- 
 rus being diiTolvedine-flential oils cry fballizes therein. 
 Thefecryftals take fire in the air, either when thrown 
 into a dry veflel, or wrapt up in a piece of paper. 
 If they be dipped in Spirit of Wine, and taken out 
 immediately, they do not afterwards take fire in the 
 nir : they fmoke a little, and for a very fhort time, 
 but hardly wafte at all. 'Though fome of them 
 were left in a fpoon for a fortnight, they did not 
 feem to have loft any thing of their bulk : but when 
 the fpoon was warmed a little they took fire, juft 
 like common Phofphorus that had never been dif- 
 iblved and cryftallize.d in an effential oil. 
 
 M. Marggraff, having put a dram of Phofphorus. 
 with an ounce of highly concentrated Spirit of Nitre 
 into a glafs retort, obierved that, without the help 
 of fire, the Ac'ud difiblvecl the Phofphorus ; that 
 part of the Acid came over into the recipient which 
 was luted to the retort ; th^t at the fame time the 
 Phofphorus took fire, burnt furioufly, and burft the 
 velTels withexplofion. Nothing of this kind happens 
 When any of the other Acids, though concentrated, 
 are applied to Phofphorus. 
 
 PROCESS III. 
 
 To decompofe Sea-Salt ly means of the Vitriolic Acid. 
 Glauber's Salt. The Pttrifii'ftion and Concentration 
 of Spirit of Salt. 
 
 PUT the Sea-falt from which you mean to ex- 
 trad the Acid into an unglazed earthen pipkin, 
 and let it amidft live coals. The Salt will decrepi- 
 tate, grow dry, and fall into a powder. Put this 
 decrepitated Salt into a tubulated glafs retort, leav- 
 ing two thirds thereof empty. Scr the retort in a 
 reverberating furnace , apply a receiver like that 
 
 T 4 Vfcd
 
 ELEMENTS of the 
 
 ufed in diftilling the fmoking Spirit of Nitre, an4 
 lute it on in the fame manner, or rather more ex- 
 actly if poflible. Then through the hole, in the up- 
 per convexity of the retort, pour a quantity of 
 highly concentrated Oil of Vitriol, equal in weight 
 to about a third part of your Salt, and immediately 
 fhut the hole very dole with a glafs ftopple, firil 
 ground therein with emery fo as to fit it exactly. 
 
 As foon as the Oil of Vitriol touches the Salt, the 
 retort and receiver will be filled with abundance of 
 white vapours ; and foon after, without lighting 
 any fire in the furnace, drops of a yellow liquor will 
 diilill from the nofe of the retort. Let the diftilla- 
 tion proceed in this manner without fire, as long as 
 you perceive any drops come : afterwards kindle a 
 very fmall fire under the retort, and continue diftil- 
 Jing and raifing the fire by very flow degrees, and 
 with great caution, to the end of the diftillation -, 
 which will be finiihed before you have occafion to 
 make the retort red-hot. Unlute the vefiels, and 
 without delay pour the liquor, which is a very fmok- 
 ing Spirit of Salt, out of the receiver into a cryftal 
 bottle, like that directed for the fmoking Spirit of 
 Nitre. 
 
 OBSERVATIONS. 
 
 SEA-SALT, as hath been already faid, is a Neutral 
 Salt compofed of an Acid, which differs from thofc 
 of Vitriol and Nitre, combined with a Fixed Alkali 
 that has fome peculiar properties ; but does not vary 
 from the others in its affinities. This Salt therefore, 
 as well as Nitre, muft be decompofed by the Vitri- 
 olic Acid , which accordingly is the cafe in the pro- 
 cefs here defcribed. The Vitriolic Acid unites with 
 the Alkaline bafis of the Sea-falt, and feparates its 
 Acid ; and that with much greater facility than itex- 
 the Nitrous Acid from its Alkalin,e bafis, be- 
 
 caufe
 
 PRACTICE ^CHYMISTRY. 281 
 
 caufe the Acid of Sea-falt has not ib great an affrnity 
 as the Nitrous Acid with Fixed Alkalis. 
 
 As a highly concentrated Oil of Vitriol is ufed 
 on this occafton, and as the Sea-falt is previoufly 
 dried and decrepitated, the Acid obtained from it 
 by distillation is very free from phlegm, and always 
 fmokes, even more violently than the ftrongeft 
 Acid of Nitre. The vapours of this Acid are alfo 
 much more elaftic and more penetrating than thofe 
 of the Nitrous Acid : on which account this diftil- 
 lation of the fmoking Spirit of Salt is one of the 
 moft difficult, mod laborious, and mod dangerous 
 operations in Chymiftry. 
 
 This procefs requires a tubulated retort, that the 
 Oil of Vitriol may be mixed with the Sea-falt after 
 the receiver is well luted to the retort, and not be- 
 fore : for, as foon as thefe two matters come toge- 
 ther, the Spirit of Salt rufhes out with fo much itn- 
 petuofity, that, if the veffels were not luted at the 
 time, the copious vapours that would ifiue through 
 the neck of the ballon would fo moiflen it, as well 
 s the neck of the retort, that it would be impracti- 
 cable to apply the lute and fecure the joint as the 
 operation requires. Moreover, the operator would 
 be expofed to thofe dangerous fumes, which, on this 
 occafion, rufh out, and enter the lungs, with fuch in- 
 credible activity as to threaten inftant fuffbcatiom 
 
 Having faid fo much of the elafticity and activity 
 of the fumes of Spirit of Salt, it is needlels to in- 
 fift upon the necefficy of giving vent to the veflels 
 from time to time, by opening the little hole of the 
 ballon : indeed the bed way to prevent the lofs of a 
 great many vapours, on this occafion, is to employ 
 Adopters, and cover them with wet canvas, which 
 will cool and condenfe the vapours they contain. 
 
 When the operation is finimed, we find a white, 
 faline mafs at the bottom of the retort as in a mould. 
 j|" |his mafs be diflblved in water, and the folution 
 
 cry ft a^
 
 E I. F. M E N T S of the 
 
 cryftallized, it yields a confidtrable quantity of Sea- 
 fait that hath not been d< j compofed, and a Neutral 
 Salt confining of the Vitriuiic Acid united wuh the 
 Alkaline bafis of that part which hath been de 
 pofed. This Neutral Salt, which bears the name 
 viGlGnl)*r its inventor, differs from Vitriolated Tar- 
 tar, or the Sal dt tiucbus, which remains after diftil- 
 linu; the Nitrous Acid, efpecially in that it is more 
 fufible, more folublc in water, and hath its cryftals 
 differently figured. But as in thefe two Salts the 
 Acid is the fame, the differences that appear be- 
 tween them muft be attributed to the peculiar na- 
 ture of the bafis of Sea-fair. 
 
 Spirit of Salt drawn by the procefs above dc- 
 fcribed is tainted with afmall mixture of the Vitri 
 plic Acid, carried up by the force of fire before it 
 had time to combine with the Alkali of the Sea- 
 falt , which happens likewife to the Nitrous Acid 
 procured in the fame manner. If you defire to have 
 it pure, and abfolutely free from the Acid of Vitriol, 
 it mud be diltillecl a leccnd time from Sea-lalt, as, 
 the Acid of Nitre was before directed to be di (tilled 
 again from frefh Nitre, in order to purify it from 
 any Vitriolic tai 
 
 . Sea-falt,-as well as Nitre, may be decompofed by 
 any combination of the Vitriolic Acid with a metal- 
 lic or earthy fubltance : but it is proper to obferve, 
 that if you diftill Spirit of Salt by means of Green 
 Vitriol, the operation will not fucceed fo well as 
 when Spirit of Nitre is diftilhd in the fame manner : 
 lefs .Spirit is obtained, and a much fiercer fire is re- 
 quired. 
 
 The csnft of this lies in the property which the 
 Acid of Sea-falt pofTeffes of ditfblving Iron, even 
 when deprived of a part of its Phlogifton by hav- 
 ing conirac'ted an union with another Acid , fo that 
 it is no fooner diflodced from its own bafis by the 
 Vi:rioiic Acid, than it unites with the ferruginous 
 
 bafis
 
 PRACTICE ^CHYMISTRY. 283 
 
 bafis of the Vitriol, from which it cannot be fepa- 
 rated but by a mod violent fire. This is the confe- 
 quence moFeefpeciallywhen calcined Vitriol is made 
 nfe of: for moilKire;, as we fhall preiently fee, greatly 
 facilitates the iepararion of the Marine Acid from 
 thole fubftances with which it is united. 
 
 When you do not defire a highly dephlegmated 
 and fmoking Spirit of Salt, you may diilill with the 
 additament of any earth containing the Vitriolic 
 Acid -, as Clay, for inftance, or Bole. To this end 
 one part of Sea-falt, (lightly dried and reduced to a 
 fine powder, mud be accurately mingled with two 
 parts of the earth you intend to employ likewife 
 pulverized , of this mixture make a ftiff pafte with 
 a proper quantity of rain water, and having formed 
 littk balls thereof about the iize of a hazel nut, let 
 them dry in the fun ; when dry put them into a 
 ftone or coated glafs retort, leaving a third part 
 thereof empty; let this vefTel in a reverberating 
 furnace, covered with its dome ; apply a receiver, 
 which need not be luted on for fome time ; and 
 heat the veffds very flowly. At firft an infipid wa- 
 ter will rife-, which muft be thrown away: after- 
 wards the Spirit of Salt will appear in white clouds. 
 Now lute your veflels, and raife the fire by degrees ; 
 which towards the end muft be pufhed to the ut- 
 moft extremity. The operation is known to be h> 
 nifhed when no drops fall from the nofe of the re- 
 tort, the receiver copls, and the white vapours that 
 filled it are feen no more. 
 
 The Spirit of Salt obtained by the procefs here 
 delivered does not fmoke, and contains much more 
 phlegm than that which is diftilled by means of the 
 concentrated Oil of Vitriol ; becaufe the earth, 
 though dried in the fun, {till retains a great deal of 
 moilture, which commixes w'nh the Acid of theSea- 
 falt. Confequently it is much eafier to collect its 
 vapours ; fo that this operation is attended with 
 
 i much
 
 ELEMENTS of tie 
 
 much lefs trouble than the other. Nevertheless it is 
 advifeableto proceed gently i to apply but little heat 
 at firft, and to unftop every now and then the fmall 
 hole of the receiver : for a quantity of the vapours 
 of Spirit of Salt, even when weakened by the ad- 
 mixture of water, is very apt to burlt the vefiels. 
 
 A much greater degree of fire is necefiary to 
 raile the Spirit of Salt by this latter procefs, than 
 by that in which the pure Vitriolic Acid is em- 
 ployed : for, as fad as the Spirit of Salt is diflodged 
 from its own baiis, by the Vitriolic Acid contained 
 in the earth made ufe of, part of it joins that earth, 
 and cannot be Jeparafed from it without the moft 
 violent heat, 
 
 A Spirit of Salt that mall not fmoke may alfo be 
 obtained by means of the pure Vitriolic Acid. Spi- 
 rit of Vitriol, or Oil of Vitriol, lowered with a good 
 deal of water, will do the bufmefs. 
 
 Some Chymifts direct a little water to be placed in 
 the receiver, when Spirit of Salt is to be diftillexl by 
 the intermedium of concentrated Oilof Vitriol, in or- 
 der to make the acid vapours condenle more readily. 
 By this means indeed tome of the inconveniencies 
 attending the diftillation of fmoking Spirit of Sale 
 may be avoided : but on the other hand, the acid 
 vapours being abfolutely fuffbcated by the water as 
 fad as they come over, the Spirit of Salt obtained 
 by this method will be no Icls aqueous than that 
 procured by the interpofition of earths : fo that here 
 is an expence to no manner of purpofe. Therefore, 
 when a Spirit of Salt is defired that fhall not Imoke, 
 it is bed to employ an additament of earth-, and 
 that fp much the rather as the Marine Acid ob- 
 tained by this means is purer and freer from any 
 Vitriolic taint, for the reafons already afligned. 
 
 Part of the Acid of Sea-falt may be feparated 
 from its Alkaline bafts by the force of fire alone, 
 without the intervention of any other body. With 
 
 this
 
 PRACTICE O/CHYMISTRY. 
 
 this view the Salt muft be put into the retort without 
 being dried. At firft an infipid water rifes ; but it 
 gradually becomes acid, and hath all the properties 
 of Spirit of Salt. When the Salt in the retort is 
 grown perfectly dry, nothing more can be forced 
 over by any degree of heat whatever. If you would 
 obtain more Acid from the fame Salt, you muft take 
 it out of the retort, where you will find it in a lump, 
 reduce it to powder, and expofe it to the air for 
 fome time, that it may attract the moifture thereof; 
 or elle wet it at once with lome rain water, and dif- 
 till as before. You will again have "an infipid water, 
 and a little Spirit of Salt ; which will in like manner 
 ceafe to rife when the Salt in the retort becomes dry. 
 This operation may be repeated as often as mail be 
 thought proper : and perhaps it may be poffible to 
 decompofe Sea-falt entirely by means thereof, with*- 
 out the interpofition of any other body. The Spirit 
 of Salt thus obtained is exceeding weak, in fmall 
 quantity, and loaded with much water. 
 
 This experiment proves that moifture greatly fa- 
 cilitates the feparation of the Acid of Sea-falt from 
 the matters with which it is united : and this is the 
 reafon that, in diftilling Spirit of Salt with the ad- 
 ditament of an earth, the operation requires much 
 lefs fire at the beginning, while the earth and fait 
 retain a great deal of humidity, than towards the 
 end, when they begin to grow dry. 
 
 After the operation there remains in the retort a 
 faline and earthy mafs, which contains, i. Some 
 entire Sea-falt that has fuffered no decompofition -, 
 2. A Glauber's Salt which is, as we laid before, a 
 Neutral Salt confifting of the Vitriolic Acid united 
 with the Alkaline bafis of the Sea-falt, from which 
 it hath expelled its proper Acid-, 3. Part of the 
 earth ufed as an intermedium, ftill retaining a por- 
 tion of its original Vitriolic Acid, which, happening 
 not to lie near enough to any particles of Sea-falt, 
 
 could
 
 286 ELEMENTS of .the 
 
 could not exert its power in decoonpofing them, and 
 fo remains united with its earth^ribafis , 4. Another 
 part of the fame earth, impregnated v/ith fome of 
 the Marine Acid, which combined therewith upon 
 being-expelled from its Alkaline balls by the Vitriolic 
 Acid,and which the" force of fire was unable to fcparatc 
 from it when the matters were gro.wn perfectly .dry. In 
 confeqnenceof what remains in this caputmorti'.um^ if 
 the whole maf<rbc triturated, moillened with a little 
 water, and diftilled a fecond time, confiderably more 
 Spirit of Salt will be obtained from it : and the fame 
 is to be faid of all d filiations of this fort. 
 
 Spirit of Salt obtained by the means of any other 
 additamcnt than concentrated Oil of Vitriol is gene- 
 rally very weak : but it may be dephlegmated and 
 concentrated, if required, much in the fame man- 
 er as Oil of Vitriol. For this purpofe you mufl 
 put it into a glals cucurbit, fet it in a balneum mart*, 
 lit thereto a head and a receiver, and with a mode- 
 rate degree of heat draw off one third or one half of 
 the liquor. What comes over into the receiver will 
 be the mod aqueous part, which being the lightdt 
 will rile firft, impregnated however with a little 
 acid : in the cucurbit will be lefr a concentrated Spi- 
 rit of Salt, or the moft acid part, which being the 
 heavieft will not rile with the degree of heat that is 
 capable of carrying up the. phlegm. Spirit of Salt 
 thus concentrated, called alfo Oil of Salt^ does noc 
 ihioke : it is of a yellow colour inclining to green, 
 and an agreeable fmell, not unlike that oT faffron. 
 
 PROCESS IV. 
 
 To decompofe Sea- fait ly means of the Nitrous Acid. 
 Aqua .regis. Quadrangular Nitre. 
 
 TAKE dried Sea-falt : bruiie it to powder : put 
 it into a glafs-retort, leaving one half of the 
 vefil-1 empty. Pour upon it a third of its weight 
 
 ot
 
 PRACTICE C/'CHYMISTRY. 287 
 
 bf good Spirit of Nitre. Place your retort in the 
 fand-bath of a reverberating furnace , put on the 
 dome-, lute to the retort a receiver having a final 1 
 hole in it, and heat the vefiels very flowly. There 
 will come over into the receiver fome vapours, and 
 an acid liquor. Increafe the fire gradually till no- 
 thing more rifes. Then unlute the veflels, and pour 
 the liquor out of the receiver into a cryltal bottle, 
 flopped like others containing Acid Spirits. 
 
 OBSERVATIONS. 
 
 THI: Nitrous Acid hath a greater affinity than the 
 Marine Acid with Fixed Alkalis. When therefore 
 Spirit of Nitre and Sea-falt are mixed together, the 
 fame confequences, in fome meafure, will follow, as 
 when the Vitriolic Acid is mixed with that Salt 
 that is, the Nitrous .Acid will, like the Vitriolic, 
 decompofe it, by difiodging its Acid from its AW 
 kaline bafis, and afiuming its place. But as tlit 
 Nitrous Acid is confiderably weaker, and much 
 lighter, than the Vitriolic Acid , a good deal of it 
 rifes along; with the Acid of Sea-folt during the 
 
 o \ t/ 
 
 operation. The liquor found in the receiver is 
 therefore a true Acpia regis. 
 
 If decrepitated Salt, and a right fmoking Spirit of 
 Nitre, be employed in this procefs, the Aq*& regis 
 obtained will be very ftrong; and during the ope- 
 ration very elaftic vapours will rufh our and burft 
 the vefifels, if thofe precautions be not taken winch 
 we pointed out as neceflary in diftilling the Spirit of 
 Nitre, and the fmoking Spirit of Salt. 
 
 The operation being finifhed, there is left in the 
 retort a ialine mafs, containing Sea-ialt not decom- 
 pofed, and a new fpecies of Nitre, which having 
 for its bafis the Alkali of Sea-falt, that is, as we 
 havefeveral times obferved, an Alkali of a peculiar 
 nature, differs from the common Nitre, i. In the 
 ' figure of its cryftalsj which are folids of four fides^ 
 
 formed
 
 288 ELEMENTS of tie 
 
 formed like lozenges : 2. In that it cryftallizes with 
 more difficulty, retains more warer in its cryftals, 
 attracts the moifture of the air, and diflblves in wa- 
 ter with the lame drcumftances as Sea-falt. 
 
 CHAP. IV. 
 Of BORAX, 
 
 PROCESS. 
 
 To decompofe Borax by tie means of Adds^ and to fe- 
 parate from it the Sedative Salt by fublimation and 
 by cryftallization. 
 
 REDUCE to a fine powder the Borax from 
 which you intend to extraft the Sedative Salt. 
 Put this powder into a wide-necked glafs retort. 
 Pour upon it an eighth part of its weight of com- 
 mon water, to moiften the powder ; and then add 
 concentrated Oil of Vitriol, to the weight of fome- 
 what more than a fourth part of the weight of the 
 Borax. Set the retort in a reverberatory, make a 
 moderate fire at firft, and augment it gradually till 
 the retort become red-hot. 
 
 A little phlegm will firft come over, and then 
 with the lait moifture that the heat expels the Se- 
 dative Salt will rile j by which means fome of it wil! 
 be diflblved in this laft phlegm, and pafs therewith 
 into the receiver ; but moft of it will adhere in the form 
 of faline flowers to the fore-part of the neck of the re- 
 tort, jurt where it is clear of the groove of the furnace. 
 There they collect into a heap, which the fucceeding 
 flowers pulh infenfibly forward till they flightly ftop 
 the paflfage. Thofe which rile after the neck is thus 
 flopped Itick to the after- part of it which is hot. v>- 
 
 trifv
 
 PRACTICE O/'CHYMISTRY. 289 
 
 trify in fome meafure, and form a circle of fuied 
 Salt. In this ftate the flowers of the Sedative Salt 
 feem to iflfue out of the circle, as from their bafis : 
 they appear like very thin, light, mining fcales, 
 and muft be brumed off with a feather. 
 
 At the bottom of the retort will be left a falinc 
 mafs: diflblve this in a fufficient quantity of hot 
 water -, filter the folution in order to free it from a 
 brown earth which it depofites; fet the liquor to 
 evaporate, and cryftals of Sedative Salt will form 
 in it. 
 
 OBSERVATIONS. 
 
 THOUGH Borax is of great ufe in many chymical 
 operations, efpecially in the fufion of metals, as we 
 mall haveoccafion to fee, yet till of late years Chy- 
 mifts were quite ignorant of its nature, as they ftill 
 are of its origin -, concerning which we know no- 
 thing with certainty, but that it comes rough from 
 the Eaft Indies, and is purified by the Dutch. 
 
 M. Homberg was one of the firft that attempted 
 to analyfe this Salt. He fhewed that on mixing it 
 with the Vitriolic Acid, and diftilling the mixture, a 
 fait fublimes in little fine needles. This product of 
 Borax he called by the name of Sedative Salt^ be- 
 caufe he found it had the property of moderating 
 the great tumult and heat of the blood in fevers. 
 
 After M. Homberg Other Chymifts alfo exer- 
 cifed themfelves on Borax. M. Lemery difcover- 
 ed that the Vitriolic is not the only Acid by means 
 of which the Sedative Salt may be obtained from 
 Borax ; but that either of the other two Mineral 
 Acids, the Nitrous or the Marine, may be ufed in 
 its ftead. 
 
 M. Geoffroy hath greatly facilitated the means of 
 obtaining the Sedative Salt from Borax , having 
 Ihewn that it may be extracted by cryftallization as 
 >vell as by fublimation -, and that the Sedative Salt 
 
 VOL, I, U fo
 
 290 ELEMENTS of tbe 
 
 fo obtained is in no refpect inferiour to that which 
 was procured before by fublimation only. To 
 him alfo we are indebted for the difcovery that in 
 the compofition of Borax there is an Alkaline Salt 
 of the fame nature as the bafisof Sea-falt. This he 
 found by obferving that he got a Glauber's Salt 
 from a folution of Borax into which he had poured 
 fome Vitriolic Acid with a view to obtain its Seda- 
 tive Salt. 
 
 Laftly, M. Baron, whom we mentioned before 
 on occafion of this Salt, hath proved, by a great num- 
 ber of experiments, that a Sedative Salt may be pro- 
 cured from Borax by the help of Vegetable Acids, 
 which was never done by any body before him ; that 
 the Sedative Salt is not a combination of an Alka- 
 line matter with the Acid made ufe of in extracting 
 it, as fome of its properties feemed to indicate; but 
 that it exifts previoufly and completely formed in the 
 Borax-, that the Acid employed to extract: it only 
 helps to diiengage it from the Alkali with which it 
 is united ; that this Alkali is actually of the fame 
 nature as the bafis of Sea-falt, becaufe that after ex- 
 tracting the fedative Salt, which.by its union there- 
 with forms the Borax, a Neutral Salt is found, of 
 the fame fort with that which would be produced by 
 combining the bafis of Sea-falt with the particular 
 Acid made ufe of; that is, if with the Vitriolic 
 Acid, a Glauber's fait ; if with the Nitrous Acid, a 
 quadrangular Nitre ; and if with the Marine Acid, 
 a true Sea-falt; and laftly, that the Sedative Salt may 
 be re-united to its Alkali, and re-produce a Borax. 
 
 Nothing therefore now remains, to give us all the 
 infight we can defire into the nature of Borax, but 
 to know what the Sedative Salt is. M. Baron hath 
 already given us certain negative notices concerning 
 it, by (hewing what it is not; that is, that the Acid 
 employed in its extraction doth not enter into its 
 compofition. We have great reafon to hope that he 
 
 will
 
 PR ACTICE of CHYMIST RY. 291 
 
 carry his enquiries ftill further, and clear up all 
 our doubts on this fubject. 
 
 The Sedative Salt may be extracted from Borax, 
 not only by the means of pure and fimple Acids, but 
 alfo by the fame Acids combined with a metallic ba- 
 fis. Thus Vitriols, for inftance, may be employed 
 for this purpofe with good fuccefs. It is eafy to fee 
 that the Vitriol muft be decompofed on this occafi- 
 on, and that its Acid cannot unite with the Alkali 
 in which theSedative Salt is lodged, withoutquitting 
 its metallic bafis, which muft of courle precipitate. 
 
 The Sedative Salt actually fublimes, when a li- 
 quid containing it is diftilled ; but it does not there- 
 fore follow that it is naturally volatile. It rifes on- 
 ly by the aid of the water with which it is mixed. 
 The proof of this affertion is, that, when all the 
 humidity of the mixture containing this Salt is dif- 
 fipated, no more Salt will rife, be the fire ever fo 
 violent , and that by adding more water to moiften 
 the dried mafs containing it, more Salt will every 
 time be obtained, through many repeated diftilla- 
 tions. In the fame manner, if ibme Sedative Salt 
 be moiftened, and expofed to a proper degree of 
 heat, a fmall quantity thereof will rife at firft by 
 the help of the water ; but as foon as it grows dry 
 it remains exceedingly fixed. This obfervation we 
 owe to M. Rouelle. 
 
 The Sedative Salt hath the appearance and the 
 tafte of a Neutral Salt : it does not change the co- 
 lour of the juice of violets , nor does it eafily diftblve 
 in water-, for it requires a quart of boiling wat?r to 
 difTolve two ounces of it : yet, with regard to Alka- 
 lis, it has the properties of an Acid , it unites with 
 thofe falts, forms therewith afaline compound which 
 cryftallizes, and even expells the Acids that happen 
 to be combined with them ; fo that it dtcompofes 
 the fame Neutral Salts that are decompofed by the 
 Vitriolic Acid. 
 
 U 2 The
 
 292 ELEMENTS of the 
 
 The Sedative Salt, when fuddenly expofed to the 
 violent heat of a naked fire, lofes near half its weight, 
 melts, puts on and retains the appearance of glals > 
 but its nature tlill remains unchanged. This glafs 
 diliblves in water, and fhcots anew into cryftals of 
 Sedative Salt. This Salt communicates to the Al- 
 kaline fait with which it is united, when in the form 
 of Borax, the property of melting with a moderate 
 heat, and forming; a kind of glals ; and 'tis this 
 great fufibility that recommends the frequent uie of 
 Borax as a flux for aflaying ores. It is allb employ- 
 ed fometimes as an ingredient in the composition of 
 glafs , but, in time, it always communicates thereto 
 the fault which its own glafs hath, namely that of 
 tarnifhing with the air. The Sedative Salt hath 
 moreover the fingular property of difiblving in 
 Spirit of Wine, and of giving to its flame, when 
 fet on fire, a beautiful green colour. All thefe ob- 
 fervations we owe to Mefif. Geoffrey and Baron. 
 
 M.GeofFroy prepares the Sedative Salt by cryilal- 
 lization only in the following manner. 4t Me dif- 
 44 folvcs four ounces of refined Borax in a fufrkient 
 44 quantity of warm water, and then pours into the 
 " iolution one ounce and two drams of highly con- 
 44 centrated Oil of Vitriol, which makes a crackling 
 " noife as it falls in. When this mixture has Mood 
 " evaporating for fome time, the Sedative Salt be- 
 44 gins to make its appearance in little, fine, mining 
 44 plates, floating on the furface of the liquor. The 
 44 evaporation is then to be flopped, and the plates 
 44 will by little and little encreafe in thicknefs and 
 " breadth. They unite together into little tufts, 
 <4 forming with each other fundry different groups. 
 44 If the veffel be ever fo little fcirred, the regularity 
 " of the cryftals will be difturbed , fo that it mull 
 44 not be touched till the cryftallization appears to be 
 44 finifhed. The cryftalline clufters, being grown 
 44 too bulky and too heavy, will then fall of them- 
 
 44 felves
 
 PRACTICE C/CHYMISTRY. 293 
 
 " felves to the bottom of the veflel. This being ob- 
 " ferved, the faline liquor muft be gently decanted 
 
 ' from thofe little cryftals, which, as they are not ea- 
 
 c fily diffolved, muft be wafhed clean, by pouring 
 *' cold water (lowly on the fides of the pan, three or 
 
 ' four times fucceffively, in order torinfe out all re- 
 " mainsof the faline liquor,and thenfecfirfttodrain, 
 " and afterwards to dry in the fun. This Salt, in the 
 " form of light flakes of (how, is now foft to the 
 
 ' touch, cool in the mouth, (lightly bitter, crackling 
 " a little between the teeth, and leaving a fmall im- 
 " preflion of acidity on the tongue. It will keep 
 *' long without giving or calcining, if managed 
 ** according to the preceding directions j that is, 
 " if it be exactly freed from its faline liquor. 
 
 " It differs from the Sedative Salt obtained by 
 " fublimation in this refpecl: only, that notwith- 
 " {landing its feeming lightnefs it is a little heavier 
 cc nLhan the other. M. Georfroy luppofcs the caufc 
 ct of this weight to be, that, as feveral of the thin 
 " plates adhere together in cryftallizing, they re- 
 " tain between them fome fmall matter of humidity; 
 " or, if you will, that, as they form larger cryftals, 
 " they prefent lefs furface to the air which elevates 
 " light bodies: whereas, on the contrary, the other 
 " Sedative Salt, being driven up by the force of 
 " fire, rifes into the head of the cucurbit in a more 
 " fubtile form, having its particles much more ex- 
 " panded and divided. 
 
 " M. Georfroy, having put his Sedative Salt made 
 " by cryftallization to all the fame trials with that 
 " made by fublimation, fatisfied himfelf that there 
 *' is no other difference between the two. If the 
 44 Sedative Salt made by cryftallization happens to 
 " calcine in the fun ; that is, if its luftre tarnimes, 
 " and its furface grows mealy, 'tis a fign that it (till 
 11 contains either a little Borax or fome Glauber's 
 " Salt: for thefe two Salts are apt to calcine in this 
 U 3 " man-
 
 294 ELEMENTS of the 
 
 " manner, and pure Sedative Salt mould not be 
 " fubjeft to this inconvenience. In order to pu- 
 *' rify it, and free it entirely from thofe Salts, it 
 " muft be diflblved once more in boiling water. 
 " As foon as the water cools, the Sedative Salt re- 
 " appears in light, mining, cryftalline plates, 
 " fwimming in the liquor. After Handing four- 
 " and-twenty hours, the liquor mull be decanted, 
 " and the fait wafhed with irefh water; by which 
 " means it will be very pure and beautiful." 
 
 Glauber's Salt and Borax diflblve in water with 
 vaftly more eafe than the Sedative Salt, and confe- 
 quently do not cryftallize Ib readily by much : fo 
 that the fmall portion of thofe fairs, which may have 
 been left on the furrace of the Sedative Salt, be- 
 ing diffufed through a large quantity of water, con- 
 tinues in a ftate of folution, while the Sedative Salt 
 cryftallizes -, which being alfo wafhed afterwards 
 with fair water, it is impoflible that the fmalleft 
 particle of thofe other Salts fhould remain adhering 
 to it , and confequently this muft be deemed an, 
 excellent way of purifying it. 
 
 SEC-
 
 PR ACTICE of CHYMISTRY. 295 
 
 SECTION II. 
 
 Of Operations on METALS. 
 
 CHAP. I. 
 
 Of GOLD. 
 
 PROCESS I. 
 
 210 feparate Gold, by Amalgamation with Mercury? 
 from the Earths and Stones with which it is found 
 mixed. 
 
 PULVERIZE the earths and ftones contain- 
 ing Gold. Put the powder into a little wooden 
 tray ; dip this tray in water, gently ihaking it and 
 its contents. The water will grow muddy, by taking 
 up the earthy parts of the ore. Continue wafhing it 
 in this manner till the water ceafe to appear turbid. 
 Upon the ore thus warned pour Itrong vinegar, hav- 
 ing firft diflblved therein, by the help of heat, about 
 a tenth part of its weight of alum. The powder muft 
 be quite drenched and covered with this Jiquor, and 
 fo left to ftand for twice twenty-four hours. 
 
 Decant the vinegar, and warn your powder with 
 warm water, till the lad that comes off hath no tafte : 
 then dry it, and put it into an iron mortar, with, 
 four times its weight of Quick- filver : triturate the 
 whole with a heavy wooden peftle, till all the pow- 
 der be of a blackifh colour: then pour in a Hale 
 water, and continue rubbing for fonje time longer. 
 More earthy and heterogeneous particles will be fe- 
 parated from the metalline parts by means of this 
 
 U 4 water.
 
 ELEMENTS of the 
 
 water, which will look dirty : it muft then be decant- 
 ed, and more fair water added. Repeat this feveral 
 times , then dry what remains in the mortar with a 
 fponge, and by the help of a gentle heat : you will 
 find it an Amalgam of the Mercury with the Gold. 
 
 Put this Amalgam into a chamoy bag : tie a knot 
 on its neck, and fqueeze it hard between your 
 fingers, over fome wide- mouthed veflel ; there will 
 ifiue through the pores of the leather numberlefs 
 little jets of Mercury, forming a fort of mower, that 
 will collect into large globules in the veflel placed 
 underneath. When you can fgrce out no more Mer- 
 cury by this means, open the bag, and in it you 
 will find the Amalgam freed from the fuperfluous 
 Mercury j the Gold retaining only about as much 
 thereof as nearly equals itfelf in weight. 
 
 Put this Amalgam into a glafs retort ; fet this re- 
 tort in the fand-bath of a reverberating furnace \ co- 
 ver it quite over with land ; apply a glafs receiver 
 half full of water, fo that the note of the retort may 
 be under the water. The receiver need not be luted 
 to the retort. Give a gradual heat, and raife the 
 fire till drops of the fublimed Mercury appear in 
 the neck of the retort, and fall into the water with 
 a hi/Ting noife. If you hear any noife in the retort, 
 flacken your fire a little. Laftly, when you obferve 
 that, though you raife the fire ftill higher than be- 
 fore, nothing more will come over, take out your 
 retort, break it, and there you will find the Gold, 
 which muft be melted in a crucible with Borax. 
 
 O B S ERVA? 10 N S. 
 
 Gold is a perfect metal, -which can by no means 
 be deprived of its Phlogifton, and on which few, 
 even of the moft powerful chymical iolvents, have 
 any effect : and therefore it almcft always hath its 
 metalline form when found in the earth , from which 
 k may femetimes be feparated by fimple lotion. 
 3' The
 
 PR ACTICE of CHYMISTRY. 297 
 
 The Gold duft found in the fands of certain rivers 
 is of this kind. When it refides in ftones, or tena- 
 cious earths, it may be extracted by the procefs here 
 delivered , to wit, by Amalgamation, or combina- 
 tion of Mercury with the Gold. Mercury is inca- 
 pable of uniting with any earthy fubftances, not 
 even with the metallic earths, when they are de- 
 prived of their Phlogifton, and confequently have 
 not the metalline form. 
 
 Hence it follows that when Mercury is triturated 
 with particles of Gold, of earth, and of ftone, min- 
 gled together, it unites with the Gold, and feparates 
 it from thofe heterogeneous matters. Yet, if there 
 be along with the Gold any other metal, in its me- 
 talline form, except Iron, the Mercury will amalga- 
 mate with that alfo. This often happens to Silver, 
 which being a perfect metal as well as Gold, is for 
 that reafon Ibmetimes dug up in its metalline form, 
 and even incorporated with Gold. When this is 
 the cafe, the mafs that remains in the retort, after 
 abftracting the Mercury of the Amalgama, is a com- 
 pound of Gold and Silver, which are to be feparated 
 from each other by the methods we (hall give for 
 that purpofe. The prefent procefs is therefore ap- 
 plicable to Silver as well as Gold. 
 
 Sometimes Gold is intimately combined with fuch 
 mineral matters as hinder the Mercury from acting 
 upon it. In that cafe the mixed mafs muft be roaft- 
 ed before you proceed to Amalgamation : for if the 
 matters be volatile, fuch, for inftance, as antimony 
 or arfenic, the fire will carry them off -, fo that after 
 roafting the Amalgamation will fucceed. But fome- 
 times thefe matters are fixed, and require fufion , if 
 fo, recourfe muft be had to fome particular me- 
 thods, which we mall defcribe when we come to 
 treat of Silver, as thefe two perfect metals are to be 
 
 treated in the fame manner, 
 
 Ores
 
 298 ELEMENTS of the 
 
 Ores containing Gold muft be vvafhed before an 
 Amalgam is attempted; that the metalline parts, be- 
 ing freed from the numerous particles of earth with 
 which they are encompafled, may the more readily 
 incorporate with the Mercury. Befides, it is the 
 property of Mercury to take the form of a dark 
 unmctallic powder, after being long rubbed with 
 other matters, fo that it cannot be eafily diftin- 
 guifhed from the particles of earth. And hence, if 
 you ftill continue to grind the matters together, 
 after the Amalgamation is completed, and wafh 
 them again and again, the water that comes off will 
 always look turbid, being impregnated with fome 
 particles of the Amalgam. This is eafily proved : 
 for if you let the turbid water fettle, and diftill the 
 fediment, you will obtain Quick-filver from it. 
 
 The ore is to be fleeped in vinegar charged with 
 alum, in order to cleanfe the furface of the Gold, 
 which is often covered with a thin coat of earth 
 that obftructs the Amalgamation. 
 
 Great care muft be taken that the Mercury em- 
 ployed in this operation be very pure. If it be 
 adulterated with any metallic fubftance, it muft be 
 freed therefrom by the methods which we mall 
 propofe in their proper place. 
 
 The way of feparating Mercury from Gold is 
 founded on the different properties of thefe two me-, 
 tallic fubftances ; the one being exceedingly fixed, 
 and the other very volatile. The union which Mer- 
 cury contracts with the metalsisnotintimateenough, 
 to give the new compound which refults therefrom 
 all the properties of either of the two united fub- 
 ftances ; at lead fo far as concerns their degrees of 
 iixity and volatility. Hence it comes that, in our 
 Amalgam, the Gold communicates but very little 
 of its fixity to the Mercury, and the Mercury com- 
 municates to the Gold but very little of its volati- 
 lity. Yet if the Mercury be diftilled off with a 
 3 much
 
 PRACTICE ^CHYMISTRY. 299 
 
 much greater degree of heat than is neceffary to 
 elevate it, a pretty confiderable quantity of Gold 
 will moft certainly be carried up along with it. 
 
 It is alfo of confequence, on another account, 
 that the fire be duly governed on this occafion. For 
 if too great a degree of heat be applied, and the 
 fire afterwards lowered, the water in the receiver, 
 which covers the nofe of the retort, will rife into its 
 body, break it to pieces, and fpoil the operation. 
 
 The caufe of this phenomenon depends on the 
 property which air poflefles of rarefying with heat 
 and condenfmg with cold, joined to its weight. As 
 foon as the retort is acted on by a lefs degree of heat 
 than acted on it the inftant before, the air contained 
 therein is condenfed, and leaves a vacuum^ which 
 the external air, by virtue of its weight, tends to 
 occupy , but, the orifice of the retort being under 
 water, the external air can no way gain admittance, 
 but by pufhing in before it the water which inter- 
 cepts its paffage. This caution, as we obferved 
 above, muft be applied to all diftillations, where 
 the veflels are difpofed as they are in this. 
 
 Care muft alfo be taken that the nofe of the retort 
 be not placed too deep under water : for as the 
 neck grows very warm during the operation, be- 
 caufe the degree of heat required to raife mercury 
 is about three times greater than that which raifes 
 water, it may eafily be broken by the contact ot 
 the cold water in the receiver. 
 
 This method of extracting Gold and Silver from 
 their ores, by Amalgamation with Mercury, is not 
 to be abfolutely depended on as a fure proof of the 
 quantity of thofe metals that may be contained in 
 the earth allayed by this means : for fome fmall part 
 of the Amalgam is always loft in warning iti anJ 
 moreover, the Mercury, when fqueezed through 
 chamoy, always carries with it a frnall portion of 
 Gold. So that if you defire to know more ex- 
 actly
 
 300 ELEMENTS of the 
 
 aftly, by this method, the quantity of Gold or Sil- 
 ver contained in any earth, the Amalgam muft not 
 be fqueezed through chamoy, but diftilled alto- 
 gether. Much the fureil method of making an ac- 
 curate aflay is that by fufion and fcorification, which 
 we (hall deicribe under the head of Silver. 
 
 In fome countries, and eipecially in America, 
 the method of Amalgamation is ufed, for extracting 
 Gold and Silver in large quantities, from the ma- 
 trices which contain them in their metalline form. 
 Agricola and other metallurgifts have defcribed 
 the machines by means whereof fuch Amalgama- 
 tions are managed. 
 
 PROCESS II. 
 
 To diffche Gold in Aqua regis, and by that means to 
 feparate it from Siher. Aurum Fulminans. Au- 
 rum Fulminans reduced. 
 
 TAKE Gold that is perfectly pure, or alloyed 
 with Silver only. Reduce it to little thin 
 plates, by hammering it on an anvil. If it be not 
 fufficiently tough, neal it till it be red in a moderate, 
 clear fire, quite free from I'moking coals, and then 
 let it cool gradually, which will reftore its ductility. 
 
 When the plates are thin enough, make them red 
 hot once more, and cut them into fmall bits with a 
 pair of fheers. Put thefe bits into a tall, narrow- 
 mouthed cucurbit, and pour on them twice their 
 weight of good Aqua regis, made of one part Sal 
 Ammoniac, or Spirit of Salt, and four parts Spirit of 
 Nitre. Set the cucurbit in a land-bath moderately 
 heated, flopping its orifice (lightly with a paper 
 coffin, to prevent any dirt from falling in. The 
 Aqua regis will prefently begin to fmoke. Round 
 the little bits of Gold will be formed an infinite 
 number of fmall bubbles, which will rife to the 
 
 furface
 
 PRACTICE O/'CHYMISTRY. 301 
 
 furface of the liquor. The Gold will totally dif- 
 folve, if it be pure, and the folution will be of a 
 beautiful yellow colour: if the Gold be alloyed 
 with a fmall quantity of Silver, the latter will re- 
 main at the bottom of the veffel in the form of a 
 white powder. If the Gold be alloyed with much 
 Silver, when the Gold is diffolved the Silver will re- 
 tain the form of the little metalline plates put into 
 the veffel. 
 
 When the diffolution is completed, gently pour 
 off the liquor into another low, wide-mouthed, 
 glafs cucurbit, taking care that none of the Silver, 
 which lies at the bottom in the form of a powder, 
 cfcape with the liquor. On this powder of Silver 
 pour as much freih Aqua regis as will cover it en- 
 tirely; and repeat this till you are fure that nothing 
 more can be taken up by it. Laftly, having de- 
 canted the Aqua regis from the Silver, warn the Sil- 
 ver with a little Spirit of Salt weakened with water, 
 and add this Spirit of Salt to the Aqua regis in which 
 your Gold is diffolved. Then to 'the body con- 
 taining thefe liquors fit a head and a receiver, and 
 diftil with a gentle heat, till the matter contained 
 in the cucurbit become dry. 
 
 OBSERVATIONS. 
 
 IT is certain that Aqua regis is the true folvent of 
 Gold, and that it does not touch Silver : fo that if 
 the Gold diffolved in it were alloyed with Silver, 
 which is often the cafe, the two metals would by 
 this means be pretty accurately feparated from each 
 other. But if you defire to obtain from this folution 
 a Gold abfolutely pure, you muft free it, before you 
 diffolve it, from'every other metallic fubftance but 
 Silver ; becaufe Aqua regis a&s upon moft of the 
 other metals and the femi-metals. We mail mew 
 under the head of Silver, as we promifed before, 
 how to. purify a mafs of Gold and Silver from every 
 
 other
 
 302 ELEMENTS of lie 
 
 other metallic alJoy. Thither alfo we refer the com- 
 mon Parting AlTay performed by means of Aqua 
 fortis : becaufe in that operation the Silver is dif- 
 lolved, and not the Gold. 
 
 If the Gold put to difiblve in Aqua regis be pure* 
 the diilblution is eafily and readily effected. But 
 if, on the contrary, it be alloyed with Silver, the 
 Aqua regis finds more difficulty in difTolving it. 
 
 v, if the Silver exceed the Gold in quantity, the 
 difiblution will not take place at all, for the rca- 
 fons adduced in our Theoretical Elements j of 
 which we mail fpeak more fully when we come to 
 treat of the Parting Aflay. 
 
 In the procefs we directed the Gold to be difiblv- 
 ed in a tall body. This precaution is necelTary to 
 prevent the lois of fome part thereof : for it is the 
 property of Aqua regis to carry off along with it 
 lome of the Gold, efpecially when there is any Sal 
 Ammoniac in its compoficion, if the vef&l be heated 
 while the diflblution is going on, or if the Aqua 
 regis be very ftrong. Yet it is proper to make ufe 
 of Aqua regis that is too rtrong rather than too 
 weak : for if it prove too ftrong, and be oblerved 
 not to act upon the metal for that reafon, it is craiy 
 to weaken it, by gradually adding fmall quantities 
 of pure water, till you perceive it begin to act with 
 vigour. This is a general rule regarding all ir,c- 
 tallic difiblutions in Acids. 
 
 When the folution of Gold is evaporated to dry- 
 nefs, if you defire to reduce into a mafs the Gold 
 dull left at the bottom of the cucurbit, you mult 
 put it into a crucible, and cover it with pulverized 
 borax, mixed with a little nitre and calcined wine- 
 lees , then cover the crucible clofe, heat it with a 
 moderate fire, which muft be afterwards increafed 
 fo as to melt the contents. At the bottom of the 
 crucible you will find a lump of Gold, over which 
 the lalts you added will be as it were vitrified. Thefe 
 
 falts
 
 PRACTICE ofCuv MIS TRY. 
 
 ialts are added chiefly to promote the fufion of the 
 metal. 
 
 The Gold may, if you will, be feparated from 
 its folvent without evaporating the folution as 
 above directed. You need only mix with the folution 
 a fixed or volatile Alkali by little and little, till you 
 lee no more precipitate fall, and then let the liquor 
 ftand to fettle, at the bottom of which you will find 
 a fediment : filter the whole, and dry what is left 
 on the filter. 
 
 Both fixed and volatile Alkalis pofleffing, as hath 
 been frequently repeated, a greater affinity with 
 Acids than metallic fubftances have, they precipi- 
 tate the Gold, and feparate it from the Acids in 
 which it is difiblved : but it is of great confequence 
 to take notice that, if you attempt to melt this pre- 
 cipitated Gold in a crucible, it will fulminate as foon 
 as it feels the heat, with fuch a terrible explofion, 
 that, if the quantity be at all confiderable, it may 
 prove fatal to the operator : even rubbing it a little 
 hard will make it blow up. This preparation is 
 therefore called Aurum fulminans^ 
 
 Hitherto no fatisfactory explanation hath been 
 given of this phenomenon. Some Chymifts confi- 
 dering that, in the precipitation of the Gold, a Nitre 
 is regenerated by the union of the Alkali with the Nit 
 trous Acid which enters into the compofition of the A- 
 qua regis^ imagine that fome of this regenerated Nitre, 
 combining with the precipitated Gold, takes fire and 
 detonates, either by means of fome fmall portion of 
 Phlogifton that may be contained in the Alkali, or 
 by means of that which conftitutes the Gold itlelf. 
 But, in the firft place, 'tis well known that Fixed 
 Alkalis do not contain Phlogifton enough to make 
 Nitre detonate. Indeed, if a Volatile Alkali be 
 employed in the precipitation, a Nitrous Ammonia- 
 cal Salt will be formed,containing Phlogifton enough 
 
 to
 
 304 ELEMENTS of the 
 
 to be capable of detonating without the concourfc 
 of any additional Phlogifton : but this detonation 
 of the Nitrous Ammoniacal Salt is not to be com- 
 pared, as to the violence of its effects, with the ful- 
 mination of Gold. Betides, we do not find that 
 Gold precipitated by a Volatile Alkali explodes with 
 greater force than that precipitated by a Fixed Al- ' 
 kali. As for the Gold, 'tis certain that it fuffers no 
 decompofition at all by fulminating. When fulmi- 
 nated under a glafs bell, in fuch fniall quantities as 
 not to endanger the operator, the Gold is found 
 Scattered about under the bell in very fine particles, 
 without having undergone any alteration. 
 
 Others have fancied this fulmination of the Gold 
 to be nothing but the decrepitation of the Sea-ialt 
 that is regenerated, in the precipitation of the metal, 
 by the Fixed Alkali uniting with the Acid of Sea- 
 ialt which makes part of the Aqua regis. But to 
 this it may be faid, that Gold precipitated by a Vo- 
 latile Alkali fulminates as violently as that precipi- 
 tated by a Fixed Alkali; and yet no Sea-ialt can be 
 formed in the liquor by the addition of a Volatile 
 Alkali, but only a Sal Ammoniac which has not the 
 property of decrepitating. Moreover, there is no 
 comparifon, as to the effects, between the decrepi- 
 tation of Sea-ialt and the fulmination of Gold. 
 
 Nor, laltly, can this fulmination be attributed, 
 as it is by fome, to the effort made by the Salts to 
 efcapefrom amidft the particles of Gold, in which: 
 they are fuppofed by them to be imprifoned : for then 
 we might deprive this Gold entirely of its fulminat- 
 ing quality by only boiling it in water, and fo 
 warning offall the faline particles, which probably 
 adhere to its furface only. It is plain there is great 
 room for very beautiful difcoveries on this fubject. 
 In Walerius's Mineralogy we find fome obfervations 
 that may throw a little light on the point before us. 
 
 " The
 
 PR ACTICE of CHYMISTRY. 305 
 
 " The quantity, fays he, of fulminating Gold 
 " precipitated exceeds that of the Gold diffblved : 
 " if the Aqua regis be made with Sal Ammoniac the 
 " explofion will be ilronger ; it will alfo be more 
 " violent if the folution be precipitated with a Vo- 
 " latile Alkali, than if a Fixed Alkali be ufed for 
 " that purpofe." 
 
 One of the fpeedieft and eafieft methods to deprive 
 this Gold of its fulminating quality, is to grind in a 
 mortar twi'ceas much flowers of Sulphur as you have 
 Gold to reduce, mixing your fulminating Gold 
 therewith by little and little as you grind them 
 together ; then to put the mixture into a crucible, 
 and heat it juft enough to melt the Sulphur. Pare 
 of the Sulphur will be diflipated in vapours, and the 
 reft will burn away. When it is quite confumed, 
 encreaie the fire fo as to make the crucible red-hot. 
 When you perceive no more fmell of Sulphur, pour 
 on the Gold a little Borax, previoufly melted in an- 
 other crucible with a Fixed Alkali, as calcined 
 Wine-lees, or Nitre fixed with Tartar ; and then 
 raife the fire fufficiently to make the whole flow. Af- 
 ter the fufion is completed you will find a button 
 of Gold at the bottom of the crucible under the falts. 
 
 Fulminating Gold may alfo be reduced by pour- 
 ing on it a fufficient quantity of Fixed Alkali re- 
 duced to a liquor, or of oil of Vitriol, evaporating 
 all the moifture, and gradually throwing what re- 
 mains, mixed up with fome pinguious matter, into 
 a crucible kept red-hot in a furnace. The reafon 
 why thefe fubftances deprive the Gold of its fulmi- 
 nating quality depends on the caufes that produce 
 the fulmination. 
 
 Gold may alfo be frparated from Aqua regis, and 
 precipitated by the means of feveral metallic fub- 
 itances that have a greater affinity, either with 
 Aqua regis, or with one of the two Acids that com- 
 pote it. Mercury is. one of the fitteft for this pur- 
 
 VOL. I. X
 
 306 ELEMENTS of tie 
 
 pofe. On dropping a folution of Mercury in the 
 Nitrous Acid by little and little into a folution of 
 Gold, the mixture becomes turbid, and a precipi- 
 tate is formed. Continue dropping in more of the 
 fqlution of Mercury till no more precipitate falls ; 
 then let the liquor ftand to fettle, and at the bot- 
 tom of it you will find a fediment, which is the 
 precipitated Gold : pour off the liquor by inclina- 
 tion, and warn the precipitate with fair water. 
 
 Mercury hath a greater affinity with the Marine 
 than with the Nitrous Acid. The affinity which 
 Mercury hath with the Marine Acid is alfo greater 
 than that of Gold with the Marine Acid ; for un- 
 lefs this Acid be alfociated either with the Nitrous 
 Acid, or at lead with a certain proportion of Phlo- 
 gifton, it will not difiblve Gold. Hence it comes 
 that when a folution of Mercury in the Nitrous 
 Acid is dropped into a folution of Gold in Aqua re- 
 gtSy the Mercury unites with the Acid of Sea-falt, 
 which is an ingredient in \\izAqua regis : but the 
 Marine Acid cannot on this occafion join the Mer- 
 cury, without deferring the Gold and the Nitrous 
 Acid with which it was united ; and then the Gold, 
 which cannot be kept in folution by the Nitrous 
 Acid alone, is forced to quit its folvent and preci- 
 pitate. The liquor therefore, that now floats over 
 the Gold thus precipitated, mull contain Mercury 
 united with the Acid of Sea-falt : and in fac"t it 
 yields a true Corrofive Sublimate, which is known 
 to be a combination of Mercury with the Marine 
 Acid. 
 
 Mercury diflfolved in Spirit of Nitre- is employed 
 to procure the precipitation we are fpeakingof; 
 becaufe metallic fubflances, when fo comminuted 
 by an Acid, are much fitter for fuch experiments 
 than when they are in a concrete form. 
 
 Gold precipitated in this manner by a metallic 
 iubftance doth not fulminate. 
 
 P R O-
 
 PR ACTICE of CHYMISTRY, 307 
 
 PROCESS III. 
 
 To diffol've Gold by Liver of Sulphur. 
 I X together equal parts of common Brim- 
 Hone, and a very flrong Fixed Alkali ; for 
 instance, Nitre fixed by charcoal. Puttheminacruci- 
 ble, and melt the mixture, ftirringitfrom time to time 
 with a fmall rod. There is no occafion to make the 
 fire very brifk; becaufe the Sulphur facilitates the 
 fufion of the Fixed Alkali. Some fulphureous va- 
 pours will rife from the crucible j the two fubftances 
 will mix intimately together, and form a reddifli 
 compound. Then throw into the crucible fome 
 little pieces of Gold beat into thin plates, fo that the 
 whole do not exceed in weight one third part of the 
 Liver of Sulphur : raife the fire a little. As foon 
 as the Liver of Sulphur is perfectly melted, it will 
 begin to diflblve the Gold with ebullition -, and will 
 even emit fome flames of fire. In the fpace of a few 
 minutes the Gold will be entirely diflblved, efpeci- 
 ally if it was cut and flatted into fmall thin leaves. 
 
 OBSERVATIONS. 
 
 The procefs here delivered is taken from M. 
 Stahl. The defign of that ingenious Chymift's en- 
 quiry was to difcover how Mofes could burn the 
 golden calf, which the Ifraelites had fet up and wor- 
 Ihipped v/hile he was on the mount-, how he could 
 afterwards reduce that calf to powder, throw it 
 into the water which the people ufed, and make all 
 who had apoftatized drink thereof, as related in 
 the Book of Exodus. 
 
 M. Stahl, having firft obferved that Gold is ab- 
 foluteiy inalterable and indeftruftible by the force of 
 fire alone, be it ever fo violent, concludes, that 
 without a miracle Mofes could not poffibly perform 
 
 X 2 the
 
 308 ELEMENTS of the 
 
 the above-mentioned operations on the golden calf, 
 any way but by mixing with the Gold fome matter 
 qualified to alter and diflblve it. He then takes no- 
 tice that pure Sulphur does not aft upon Gold at 
 all, and that many other fubftances, which are 
 thought capable of dividing and diflblving it, can- 
 not however do it fo completely as is necefiary to 
 render that metal fufceptible of the effects related. 
 He then gives the method of diflblving it by Liver 
 of Sulphur defcribed in the proccfs. 
 
 Liver of Sulphur diflblves likewife all the other 
 tnttals : but M. Stahl obferves that it attenuates 
 Gold more than any other metallic fubiiance, and 
 unites with it much more intimately than with the 
 reft. This appears from what happens, on at- 
 tempting to diflblve in water any of the mixts re- 
 fulting from the union of another metal with Liver 
 of Sulphur : for then the metal feparates, and ap- 
 pears in the form of a powder or fine calx ; 
 whereas, when Gold is united with Liver of Sul- 
 phur, the whole compound difiblves in water fo 
 perfectly, that the Gold even pafles with the Liver 
 of Sulphur through the pores of filtering paper. 
 
 If an Acid be poured into a folution of* this com- 
 bination of Gold with Liver of Sulphur, the Acid 
 unites with the Alkali of the Hepar, and the Gold 
 falls to the bottom of the liquor along with the 
 Sulphur, which doth not quit it. The Sulphur thus 
 precipitated with the Gold is eafily carried off by a 
 flight torrefadtion, after which the Gold remains ex- 
 ceedingly comminuted. The Sulphur of this com- 
 pound may alfo be deftroyed by torrefaction, with- 
 out the trouble of a previous folution and precipi- 
 tation, and then alfo the GoU remains fo attenuated 
 as to be mifcible with liquors, and floats on them, 
 or fwimg in them, in iuch a manner that it may 
 eafily b fwallowed with them in drinking. From 
 all this M. Stahl concludes there is greas rcafon to 
 
 believe
 
 PRACTICE of CHYMISTRY. 309 
 
 believe it was by means of the Liver of Sulphur 
 that Mofes divided, and in a manner calcined, the 
 golden calf, fo that he could mingle it with water, 
 and make the Ifraelites drink it. 
 
 PROCESS IV. 
 
 ^Co fe-parate Gold from all other metallic Subftances ly 
 means of Antimony. 
 
 HAVING put the Gold you intend to purify 
 into a crucible, fet it in a melting furnace, 
 cover it, and make the Gold flow. When the me- 
 tal is in fufion caft upon it, by a little at a time, 
 twice its weight of pure crude Antimony in pow- 
 der, and after each projection cover the crucible 
 again immediately: this done keep the matter in 
 fufion for a few minutes. When you perceive that 
 the metallic mixture is perfectly melted, and that its 
 furface begins to fparkle, pour it out into a hollow 
 iron cone, previoufly heated, and fmeared on the 
 infide with tallow. Immediately ftrike with a 
 hammer the floor on which the cone ftands ; and 
 when all is cold, or at leaft fufficiently fixed, invert 
 the cone and ftrike it : the whole metallic mafs 
 will fall out, and the under part thereof, which was 
 at the point of the cone, will be a Regulus more or 
 lefs yellow as the Gold was more or lefs pure. On 
 ftriking the metallic mafs the Regulus will freely 
 part from the fulphureous cruft at top. 
 
 Return this Regulus into the crucible, and melt 
 it. Lefs fire will do now than was required be/ore. 
 Add the fame quantity of Antimony, and proceed 
 as at firft. Repeat the fame operation a third time, 
 if your Gold be very impure. 
 
 Then put your regulus into a good crucible 
 much larger than is neceflary to hold it. Set your 
 crucible in a melting furnace, and heat the matter 
 
 X 3 but
 
 310 lEMEKTSo 
 
 but juft enough to make it flow, with a fmooth, bril- 
 liant furface. When you find it thus conditioned, 
 point towards it the nofe of a long-fnouted pair of 
 bellows, and therewith keep gently and conftantly 
 blowing. There will arife from the crucible a con- 
 fiderable fmoke, which will abate greatly when you 
 ceafe to blow, and increafe as foon as you begin 
 again. You mud raife the fire gradually as you 
 approach towards the end of the operation. If 
 the furface of the metal lofc its brilliant polifh, and 
 fcem covered with a hard cruft, 'tis a fign the 
 fire is too weak; in which cafe it mil ft be increafed, 
 till the furface recover its mining appearance. At 
 laft, when no more fmoke rites, and the furface of 
 the Gold looks neat and greenifh, cafb on it, by 
 little and little, fome pulverized Nitre, or a mix- 
 ture of Nitre and Borax. The matter will fwell 
 up. Continue thus adding more Nitre gradually, 
 till no commotion is thereby produced in the cru- 
 cible , and then let the whole cool. If you find, 
 when the Gold is cold, that it is not tough enough, 
 melt it over again ; when it begins to mek c.ift in 
 the fame Salts as before ; and repeat this till it be 
 perfectly ductile. 
 
 OBSERVATIONS. 
 
 ANTIMONY is a compound, confiding of a femi- 
 metallic part united with about a fourth part of 
 its weight of common Sulphur. It appears, in the 
 ninth column of the Table of Affinities, that all 
 the metals, Mercury and Gold excepted, have a 
 greater affinity than the reguline part of Antimony 
 with Sulphur. If therefore Gold, adulterated with 
 a mixture of Copper, Silver, or any other metal, 
 be melted with Antimony, thole metals will unite 
 with the Sulphur of the Antimony, and feparate it 
 from the reguline part, which being thus let free 
 will combine and be blended with the Gold. Thele 
 
 two
 
 PRACTICE G/'CHYMISTRY. 311 
 
 two metallic fubftances, forming a mafs far heavier 
 than the other metals mixed with the fulphur, fall 
 together to the bottom of the crucible in the form 
 of a Regulus, while the others float over them like 
 a fort of fcoria or flag : and thus the Gold is freed 
 from all alloy but the reguline part of the Antimony. 
 
 As all the other metals have a great affinity with 
 Sulphur, and Gold is the only one that is capable 
 of refifting its action, one would think Sulphur 
 alone might be fufficient to free it from the metals 
 combined with it, and that it would therefore be 
 better to employ pure Sulphur, in this operation, 
 than to make uie of Antimony -, the reguline part 
 of which remaining united with the Gold requires 
 another long and laborious operation to get rid of 
 it. 
 
 Indeed, ftrictly fpeaking, Sulphur alone would 
 be fufficient to produce the defired feparation : but 
 it is proper to obferve that, as Sulphur alone is very' 
 combuftible, mod of it would be confumed in the 
 operation before it could have an opportunity to 
 unite with the metallic fubftances , whereas when 
 it is combined with the Regulus of Antimony, it is 
 thereby enabled to bear the action of the fire much 
 longer without burning, and confequently is much 
 fitter for the purpofe in queftion. Befides, if we 
 were to make ufe of pure Sulphur, a great part of 
 the Gold, which is kept in perfect fufion, and its 
 precipitation facilitated, by the Regulus of Anti- 
 mony, would remain confounded with the lulphu- 
 reous fcoria. 
 
 Neverthelefs, feeing the metals with which Gold 
 is alloyed cannot be feparatedfrom it by Antimony, 
 but that a quantity of Regulu? proportioned to the 
 quantity of the metals fo feparated will unite with 
 the Gold, and that the more Regulus combines with 
 the Gold, the more tedious, chargeable, and labo- 
 rious will the operation prove, this confideration, 
 X 4 ought
 
 312 ELEMENTS o/* the 
 
 ought to have fome influence in directing our pro- 
 eels. Therefore, if the Gold be very impure, and 
 worfe than fixteen carats, we muft not mix it with 
 crude Antimony alone, but add two drams of pure 
 Sulphur for every carat the Gold wants of fixteen, 
 and lefTen the quantity of Antimony in proportion 
 to that of the real Gold. 
 
 It is neceflary to keep the crucible clofe covered, 
 after mixing the Antimony with the Geld, to pre- 
 vent any coals from falling into it: for, if that 
 fhould happen, the melted mafs would puff up 
 confiderably, and might perhaps run over. 
 
 The infide of the cone, into which you pour the 
 melted metallic mafs, muft be greafed with tallow, 
 to prevent its (licking thereto, and that it may 
 come eafily out. Striking the floor, on which the 
 cone with the melted metal (lands, helps the preci- 
 pitation and delcent of the Regulus of Gold and 
 Antimony to the bottom of the cone. 
 
 Lefs fire is requifite to melt this compound Re- 
 gulus, in order to add frefli Antimony, than was 
 neceflary before the Gold was mixed with the regu- 
 line part of the Antimony ; becaufe this metallic 
 fubflance, being much more fufible than Gold, pro- 
 motes its melting. The Antimony is mixed with 
 the Gold by repeated projections, that the feparation 
 of the metals may be accomplished with the greater 
 cafe and accuracy. Yet the operation might be 
 fuccefsfully* performed, by putting in all the Anti- 
 mony at once, and with one melting only. 
 
 The metalline mafs found at the bottom of the 
 cone after all thefe operations, is a mixture of Gold 
 with the reguline part of the Antimony. All the reft 
 of the procefs confifts only in feparating this reguline 
 part from the Gold. As Gold is the mod fixed of 
 all metals, and as the Regulus of Antimony cannot 
 bear the violence of fire without flying off in va- 
 pours, nothing more is neceflary for this purpofe 
 
 but
 
 PRACTICE of CHYMISTRY. 313 
 
 but to expofe the compound, as diredled in the pro- 
 cefs, to a heat ftrong enough, and long enough 
 continued, to diflipate all the Regulus of Antimo- 
 ny. This femi-metal exhales in the form of a very 
 thick white fmoke. It is proper to blow gently 
 into the crucible during the whole operation ; be- 
 caufe the immediate contact of the frefti air incef- 
 fantly thrown in promotes and confiderably en- 
 creaks the evaporation : and this is a general rule 
 applicable to all evaporations. 
 
 The fire muft be gradually raifed as the Regulus 
 of Antimony is diffipated, and the operation draws 
 toward an end ; becaufe the mixed mafs of Regu- 
 lus of Antimony and Gold becomes fo much the 
 lels fufible as the proportion of the Regulus is lef- 
 fened. Though the Regulus of Antimony be fe- 
 parated from the Gold in this operation, becaufe 
 the latter is of fuch a fixed nature that it cannot be 
 volatilized by the degree of fire which diflipates 
 the Regulus , yet, as the Regulus is very volatile, 
 it will undoubtedly carry up fome of the Gold along 
 with it, efpecially if you hurry on the evaporation, 
 too faft, by applying too great a degree of fire, by 
 blowing too brifkly into the crucible, and ftill 
 more if you evaporate your mixture in a broad flat 
 veffel inftead of a crucible. All thefe things muft 
 therefore be avoided, if you would lofe no more 
 Gold than you needs muft. 
 
 However, unlefs the evaporation be carried to 
 the utmoft, by the means above pointed out, a fmall 
 portion of the Regulus of Antimony will always 
 remain combined with the Gold, which defends it 
 from the aflion of the fire. This fmall portion of 
 Regulus hinders the Gold from being perfectly 
 pure and dudile. In order therefore to confume 
 and fcorify it, we caft Nitre into the crucible when 
 we perceive it to emit no more white vapours. 
 
 We
 
 314 ELEMENTS 0/" the 
 
 We know that Nitre has the property of reduc- 
 ing all metallic fubftances to a calx, Gold and Sil- 
 ver excepted , becaufe it deflagrates with the phlo- 
 gifton to which their metalline form is owing : but 
 as this accenfion of the Nitre occafions a tumid effer- 
 vefcence, care muft be taken to throw it in but by 
 little and little at a time; for if too much be pro- 
 jected at once the melted matter will run over. 
 
 This operation might be confiderably abridged 
 by taking advantage of the property which Nitre 
 pofieffes of thus confuming the phlogifton of me- 
 tallic fubftances , as by means thereof we might 
 deftroy all the Regulus of Antimony incorporated 
 with the Gol-."!, without having recourie to a long 
 and tedious evaporation. But then we fi.ould at 
 the fame time lofe a much greater quantity of 
 Gold, by reafon of the tumujt and ebullition which 
 are inseparable from the detonation of Nitre. On 
 the whole therefore, if Nitre be made ufe of to pu- 
 rify Gold, great care muft be taken to apply but 
 very little of it at a time. 
 
 All the Silver that was mixed with the Gold, and 
 indeed a little of the Gold itfelf, remains con- 
 founded with the fulphureous fcoria, which floats 
 upon the Golden Regulus after the addition of the 
 Antimony : we {hall fhew in the Chapter on Sil- 
 ver how thefe two metals are to be feparated from 
 the Sulphur. 
 
 CHAP.
 
 PRACTICE O/^CHYMISTRY. 31$ 
 
 " i =a 
 
 CHAP. II. 
 
 Of SILVER. 
 
 PROCESS I. 
 
 To feparate Silver from its Ore, ly means of Scorifi~ 
 cation with Lead. 
 
 BEAT to powder in an iron mortar the ore from 
 which you mean to feparate the Silver, having 
 rirtl roafted it well in order to free it from all the 
 Sulphur and Arfenic that it may contain. Weigh 
 it exactly : then weigh out by itfc-lf eight times as 
 much granulated Lead. Put one half of this Lead 
 into a tefc, and fpread it equally thereon : upon this 
 Lead lay your ore, and cover it quite over with 
 the remaining half of the Lead. 
 
 Place the teft thus loaded under the further end 
 of the Muffle in a cupelling furnace. Light your 
 fire, and increafe it by degrees. If you look through- 
 one of the apertures in the door of the furnace you 
 will perceive the ore, covered with calcined Lead, 
 fwim upon the melted Lead. Prefently afterward^ 
 it will grow foft, melt, and be thrown towards the 
 fides of the veflel, the furface of the Lead appear- 
 ing in the midft thereof bright and mining like a 
 luminous difc : the Lead will then begin to boil, 
 and emit fumes. As foon as this happens, the fire 
 muft be a little checked, fo that the ebullition of 
 the Lead may almoft entirely ceafe, for about a quar- 
 ter of an hour. After this it muft be excited to the 
 degree it was at before, fo that the Lead may begin 
 again to boil and fmoke. Its fbining furface will 
 gradually leflen, and be covered \v\th fcori*. Stir 
 the whole with an iron, hook, and draw io towards 
 
 the
 
 3 I 6 E L E M E N T S 
 
 the middle what you obferve towards the fides of 
 the vefiel ; to the end that, if any part of the ore 
 Jhould flill remain undifiblved by the Lead, it may 
 be mixed therewith. 
 
 When you perceive that the matter is in perfect 
 fufion, that the greateft part of what flicks to the 
 iron hook, when you dip it in the melted matter, 
 ieparates from it again, and drops back into the vef- 
 iel ; and that the extremity of this inftrument when 
 grown cold, appears varniflied over with a thin, 
 fmooth, fhining cruft-, you may look on theie as 
 marks that the bufinefs is done, and the more uni- 
 form and evenly the colour of the cruft is, the more 
 perfect may you judge the fcorification to be. 
 
 Matters being brought to this pafs, take the tefk 
 with a pair of tongs from under the muffle, and 
 pour its whole contents into an iron cone, firfl 
 heated and greafed with tallow. This whole ope- 
 ration lafts about three quarters of an hour. When 
 all is cold, the blow of a hammer will part the 
 Regulus from the fcoria-, and as it is not poflible, 
 how perfect foever the fcorification be, to avoid 
 leaving a little Lead containing Silver in the fcoria, 
 it is proper to pulverife this fcoria, and feparate 
 therefrom whatever extends under the hammer, in 
 order to add it to the Regulus. 
 
 OB S E 
 
 Silver, as well as Gold, is often found quite pure, 
 and under its metalline form, in the bowels of the 
 earth -, and in that cafe it may be feparated from 
 the ftones 01 land, in which it is lodged, by fimple 
 warning, or by Amalgamation with Mercury, in 
 the fame manner as before directed for Gold. But 
 it alfo happens frequently that Silver is combined in 
 the ore with other metallic fubftances and minerals, 
 which will not admit of this procefs, but force us to 
 employ other methods of feparating it from them. 
 
 Sulphur
 
 PRACTICE of CH YM i STR Y. 317 
 
 Sulphur and Arfenic are the fubftances to which 
 Silver and the other metals ufually owe their mineral 
 ftate. Thefe two matters are never very clofely 
 united with Silver; but may be pretty eafily fe pa- 
 rated from it by the action of fire, and the addition 
 of Lead. If Arfenic be predominant in a Silver 
 ore, it will unite with the Lead by the help of a 
 pretty moderate heat, and quickly convert a confi- 
 derable quantity thereof into a penetrating fufiblc 
 glafs, which has the property of fcorifying with cafe 
 all fubftances that are capable of fcorification. 
 
 When Sulphur predominates, the fcorification 
 proceeds more (lowly, and doth not always fucceed ; 
 becaufe that mineral combined with Lead leflens ics 
 fufibility, and retards its vitrification. In this cafe 
 part of the Sulphur muft be diffipated by reading : 
 the other part unites with the Lead \ and that, be- 
 ing rendered lighter by this union, floats on the reft 
 of the mixture, which chiefly contains the Silver. 
 At laft the joint action of the air and of the fire, 
 diffipar.es the portion of Sulphur that had united 
 with the Lead : the Lead vitrifies and reduces to a 
 fcoria whatever is not either Silver or Gold : and 
 thus the Silver beino- difentanejled from the hetero- 
 
 
 
 geneous matters with which it was united, one part 
 thereof being diffipated and the other vitrified, 
 combines with the portion of Lead which is not vi- 
 trified, and falls through the fcoria, which to favour 
 its defcent muft be in perfect fufion. 
 
 The whole procefs therefore confifts of three dif- 
 tinct operations. The firft is Roafting, which difii- 
 patesfome of the volatile fubftances found united with 
 the Silver : the fecond is Scorilication, or the Vitri- 
 fication of the fixed matters alfo united with the Sil- 
 ver, fuch as fand, ftones, metals, &c. and the third 
 is Precipitation, or the feparation of the Silver from 
 the fcoria. The two fir it are, as hath been (hewn, 
 preparatives for the laft, and indeed produce it. 
 
 As
 
 3 1 8 E L E M E N T s 
 
 As every thing we faid concerning Gold, when 
 we treated of the procefs of Amalgamation, is to be 
 applied to Silver, which may be extracted by the 
 fame method, when it is in its metalline form - y in 
 the fame manner all we now advance touching the 
 method of extracting Silver by Scorification, when 
 it is depraved with a mixture of heterogeneous 
 matters, is equally applicable to Gold in the fame 
 circumftances : and indeed Silver almoft always 
 contains more or lefs Gold naturally. 
 
 In the procefs we directed that the ore fhould be 
 pulverized before it be expofed to the tire, with a 
 view to enlarge its furface, and by that means faci- 
 litate the action of the Lead upon it, as well as the 
 evaporation of its volatile parts. 
 
 We recommended the precaution of flackening 
 the fire a little at the beginning of the operation, 
 only to prevent the Lead from being too haftily 
 converted into litharge, left it (hould penetrate and 
 corrode the teft before it had wholly diflblved the 
 ore : but if we were perfectly certain of the veHd's 
 being fo good as to be in no danger of penetration 
 by the Lead, this precaution would be needlefs. 
 
 It is proper to add eight parts of Lead tor one of 
 ore ; though fo much is not always abfolutely ne- 
 ceflary, elpecially when the ore is very fufible. 
 The fuccefs of this operation depends chiefly on 
 the completenefs of the Scorification-, and therefore 
 the addition of more Lead than enough is attended 
 with no inconvenience : for, as it always promotes 
 the fcorification, it can never do any harm. 
 
 If the ore be mixed with fuch earthy and ftony 
 parts as cannot be feparated from it by wartiing, it 
 is the more difficult of fufion,even though the ftones 
 fhould be fuch as are moft difpofed to vitrify ; bc- 
 cauie the moft fufible earths and ftones are always 
 lefs fo than moft metallic fubftances. In that cafe 
 it will be necefiary, for effecting the Scorificution, 
 
 to
 
 PRACTICE of C H YMISTRY. 319 
 
 to mix thoroughly with the pulverized ore an equal 
 Quantity of Glafs of Lead, to add twelve times as 
 much granulated Lead, and then to proceed as di- 
 rected for a fufible ore -, expcfing the mixture to a 
 degree of fire ftrong enough, and long enough kept 
 np, to give the fcoria all the properties above re- 
 quired as figns of a perfect icorification. 
 
 Silver ore is fometimes mixed with pyrites, and 
 the ore of Arfenic, or cobalt, which alfo make it 
 refractory. As the pyrites contain a large quantity 
 of Sulphur, which is very volatile as well as Arfe- 
 nic ; in this cafe it is proper to begin with freeing 
 the ore from thefe two extraneous fubftances. This 
 is eafily done by roafting : only be fure, when you 
 firft expofe the ore to the heat, to cover the vefiel in 
 which you roaft it, for fome minutes, with an in- 
 verted vefiel of the fame width ; becaule fuch forts of 
 ore are very apt to fly when they firft feel the heat. 
 
 After this uncover it, and leave it expofed to the 
 fire till no more fnlphureous or arfenical matters 
 rife. Then mix it with the fame quantity of Glafs 
 of Lead as we ordered for ores rendered refractory 
 by the admixture of earths or (tones, and proceed 
 in the fame manner. 
 
 It is the more necefiary to roaft Silver ore infected 
 with Sulphur and Arfenic, becaufe, as Sulphur ob- 
 ftructs the fufion of Lead, if cannot but do hurr, 
 and protract the operation ; and Arfenic does mif- 
 chief, on the other hand, by fcorifying a very great 
 quantity of Lead too haftily. 
 
 When the Sulphur and Arfenic are diflipated by 
 roafting, the ore muft be treated like that which is 
 rendered refractory by (tony and earthy matters > 
 for as the pyrites contain much iron, there remains, 
 after the Sulphur is evaporated, a conliderable quan- 
 tity of martial earth, which is difficult to fcorify. 
 The pyrites as well as the cobalts, contain more- 
 over an unmetallic earth, which is hard to fufe. 
 
 The
 
 320 ELEMENTS of the 
 
 The general rule therefore is, when the ore is 
 rendered refractory by any caufe whatever, to mix 
 it with Glafs of Lead, and to add a larger quantity 
 of granulated Lead. Yet fome ores are fo refravftory 
 that Lead alone will not do the bufinefs, and re- 
 courle muft be had to fome other flux. That which 
 is fitted for the prefent purpofe is the Black Flux, 
 compofed of one part of Nitre and two parts of Tar- 
 tar deflagrated together. The Phlogifton contained 
 in this quantity of Tartar is more than fufficient to 
 alkalizate the Nitre. This Flux therefore is nothing 
 more than Nitre alkalizated by Tartar, mixed with 
 fome of the fame Tartar that hath not loft its Phlo- 
 gifton, and is only reduced to a fort of coal. 
 
 The White Flux is alfo very fit to promote fufion ; 
 but on this occafion the Black Flux is preferable, 
 becaufe the Phlogifton of the Black Flux prevents 
 the Lead from being too foon converted to litharge, 
 and fo gives it time to difiblve the metallic matters. 
 The White Flux, which is the relult of equal parts 
 of Tartar and Nitre alkalizated together, being no 
 more than an Alkali deftitutc of Phlogifton, or con- 
 taining but very little, doth not pofTefs this advan- 
 tage. 
 
 if Silver mould be combined in the ore with 
 Iron in its metalline ftate, which however does not 
 commonly happen, then, in order to feparate them, 
 the Iron muft be deprived of its Phlogifton, and con- 
 verted to a crocus before the mixed mafs be melted 
 with Lead , which may be done by difiblving it in 
 the Vitriolic Acid, and then evaporating the Acid. 
 
 We are neceflitated to make ufe of this contri- 
 vance, becaufe Iron in its metalline form cannot be 
 diffolved either by Lead or by the Glafs of Lead ; 
 but when it is reduced to a calx, litharge unites wkh 
 it, and fcorifies it. 
 
 If you have not at hand the utenfils neceflary for 
 performing the operation we have been defcribing in 
 
 a tcft,
 
 PRACTICE c/* C H Y M i s f R Y. 321 
 a teft, and under the muffle -, or if you have a mm4 
 to work on a greater quantity of ore at a time* 
 you may make ufe of a crucible for the purpofe, 
 and perform the operation in a melting furnace. 
 
 In this cafe the ore muft be prepared, as above 
 direded, according to its nature, and mixed with 
 a proper quantity of Lead and Gla'fs of Lead j the 
 whole put into a good crucible, leaving two thirds 
 thereof empty, and covered with a mixture of Sea- 
 falt and a little Borax, both very dry, to the thick- 
 nefs of a full half inch. 
 
 This being done, fet the crucible in the midft of 
 a melting furnace, raife the coals quite to the lip of 
 the crucible ; light the fire ; cover the furnace with 
 its dome ; brut do not urge the fire more than is 
 necefiary to bring the mixture to perfeft fufion : 
 leave it thus in fufion for a good quarter of an 
 hour ; ftir the whole with a bit of ftrong iron wire ; 
 then let it cool ; break the crucible, and feparate 
 the Regulus from the fcoria. 
 
 The Salts added on this occafion are fluxes* 
 and their ufe is to procure a perfefl fufion of the 
 fcoria. 
 
 If the melted matters be left expofed to the" 
 fire, either in a teft, or in a crucible, longer than 
 is above prefcribed, the portion of Lead, that hath 
 united and precipitated with the Silver, will at lad 
 vitrify, and at the fame time fcorify all the alloy 
 with which that metal may be mixed. But as there 
 are no veflels that can long endure the aftion of 
 litharge, without being pierced like a fieve, fome 
 of the filver may efcape through the holes or fif- 
 fures of the veflel, and fo be loft. It is better 
 therefore to complete the purification of your Sil- 
 ver by the operation of the Cupel, the deicription 
 of which follows. 
 
 Vofc.L
 
 322 ELEMENTS of the 
 
 PROCESS II. 
 
 refining of Silver by the Cupel. 
 
 TAKE a cupel capable of containing one third 
 more matter than you have to put into it : 
 fet it under the muffle of a furnace, like that de- 
 fcribed in our Theoretical Elements, as peculiarly 
 appropriated to this fort of operation. Fill the fur- 
 nace with charcoal , light it ; make the cupel red- 
 hor, and keep it fo till all its moifture be evapo- 
 rated ; that is, for about a good quarter of an hour, 
 if the cupel be made wholly of the afhes of burnt 
 bones; and for a whole hour, if there be any 
 warned wood-am in its compofition. <> 
 
 Reduce the Regulus which remained after the pre- 
 ceding operation to little thin plates, flatting them 
 with a fmall hammer, and feparating them carefully 
 from all the adherent fcoria. Wrap thefe in a bit of 
 paper, and with a fmall pair of tongs put them gent- 
 ly into the cupel. When the paper is confumed, the 
 Regulus will foon melt, and the fcoria, which will 
 be gradually produced by the Lead as it turns to li- 
 tharge, will be driven to the fides of the cupel, and 
 immediately abforbed thereby. At the fame time 
 the cupel will aflume a yellow, brown, or blackim 
 colour, according to the quantity and nature of 
 the fcoria imbibed by it. 
 
 When you fee the matter in the cupel in a vio- 
 lent ebullition, and emitting much fmoke, lower 
 the fire by the methods formerly prefcribed. Keep 
 up fuch a degree of heat only that the fmoke which 
 afcends from the matter may not rife very high, and 
 that you may be able to diflinguifii the colour which 
 the cupel acquires from the fcoria. 
 
 Increafe the fire by degrees, as more and more 
 litharge is formed and abforbed. If the Regu- 
 lus
 
 PRACTICE of CHYMIS TRY. 323 
 
 Jus examined by this affay contain no Silver, you 
 will fee it turn wholly into fcoria, and at laft dif- 
 appear. When it contains Silver, and the quan- 
 tity of Lead is mucli diminimed, you wUl perceive 
 little vivid irifes, or beautiful rain-bow colours, 
 fhooting fwiftly along its furface, and crofting each 
 other in many different directions. At laft, when 
 all the Lead is deftroyed, the thin dark fkin, that is 
 continually protruded by the Lead while it is turn- 
 ing into litharge, and wiiich hitherto covered the 
 Silver, fuddcnly difappears ; and, if at this moment 
 the fire happen not to be.ilrong enough to keep the 
 Silver in fufion, the furface of that metal will at 
 once dare out a dazzling fplendour : but, if the fire 
 be ftrong enough to keep the Silver in fufion, 
 though freed from all mixture of Lead, this change 
 of colour, which is called its fulguration, will not 
 be fo perceptible, and the Silver will appear like 
 a bead of fire. 
 
 Thefe phenomena mew that the operation is fi- 
 nifhed. But the cupel muft ftill be left a minute or 
 two under the muffle, and then drawn (lowly out 
 with the iron hook towards the door of the furnace. 
 When the Silver is fo cooled as to be but moderately 
 red, you may take the cupel from under the muffle 
 with your little tongs, and in the middle of its ca- 
 vity you will find an exceeding white bead of Sil- 
 ver, the lower part whereof will be unequal, and 
 full of little pits. 
 
 O B S ERVATIONS. 
 
 THE Regulus obtained by the former procefs con- 
 fifts altogether of the Silver contained in the ore, 
 alloyed with the other metals that happened to be 
 mixed therewith in its mineral flate, and a good 
 deal of the Lead that was added to precipitate the 
 Silver. The operation of the cupel may be confi-^ 
 dered as the fequel of that procefs, being intended 
 cnlv to reduce into a fcoria whatever is not Gold or 
 Y 2 Silver.
 
 324 ELEMENTS 
 
 Silver. Lead being of all metals that which vitri- 
 fies the mod eafily, which moft promotes the vitri- 
 fication of the reft, and the only one which, when 
 vitrified, penetrates the cupel, and carries along 
 with it the other metals which it hath vitrified, is 
 confequently the fitted for that purpofe. We fhall 
 fee in its place that Bifmuth hath the lame proper- 
 ties with Lead, and may be fubltituted for it in 
 this operation. 
 
 Care muft be taken to choofe a cupel of a proper 
 capacity. Indeed it fhould rather be too big than 
 too little: becaufe the operation is no way prejudiced 
 by an excefs in its fize-, whereas, if it be too fmall, 
 it will be over-doled with Lead, and at laft the li- 
 tharge, which deftroys every thing, will corrode its 
 cavity, and eat holes through the very body of the 
 vefiel. Add that the afhes, of which the cupel is 
 made, being once glutted with litharge, ablbrb it 
 afterwards but flowly, and that the quantity of this 
 vitrified litharge, becoming too great to be contained 
 in the fubftance of the vefiel, exfudes through it, 
 and drops on the floor of the muffle, which it cor- 
 rodes and renders unequal , and moreover folders 
 to it the vefiels fet thereon. It may be laid down 
 as a general rule for determining the fize of a cu- 
 pel, that it weigh, at lead, half as much as the 
 metallic mafs to be refined in it. 
 
 It is alfo of the utmod confequence that the cupel 
 be well dried before the metal be put into it. In 
 order to make fure of this point it mud be kept 
 red-hot for a certain time, as is above directed : for 
 tho' to the fight and to the touch it may appear very 
 dry, it neverthelefs obdinately retains a fmall mat- 
 ter of moidure, fufficient to occafion the lofs of fome 
 of the metal-, which, when it comes to melt, will be 
 thereby fpirited up, in the form of little globules, to 
 the very roof of the muffle. The cupels, that dand 
 mod in need of an intenfe heat to dry them, are thofe 
 
 chiefly 
 
 5
 
 PRACTICE ^CHYMISTRY. 325 
 
 chiefly in whofe compofition wood afhes are employ- 
 ed : for whatever care be taken to lixiviate thofe 
 afhes before they are ufed, they will ftill retain a 
 little alkaline fait , and that, we know, is very 
 greedy of moifture, will not part entirely with it, 
 but by the means of a violent calcination, and pre- 
 fently re-imbibes it when expofed to the air. 
 
 A little Phlogifton alfo may ftill be left in the afhes 
 of which the cupels are made ; and that is another 
 reafon for calcining them before they are ufed. By 
 this means the remaining Phlogifton is diflipated, 
 which might otherwife combine with the litharge 
 during the operation, reduce it, and occafion fuch 
 a ferment in the matter as to make fome of it run 
 over : to thefe inconveniencies, which any remain- 
 der of moifture or Phlogifton may produce, we mutt 
 add the cracks and flaws, which are very incident to 
 cupels not perfectly freed from both thofe matters. 
 It is of no lefs importance to the fuccefs of this 
 operation, that a due degree of heat be kept up. In 
 the procefs we have defcribed the marks which 
 Ihew the heat to be neither too ftrong nor too 
 weak , when it exceeds in either of thele refpe&s 
 may be known by the following figns. 
 
 If the fume emitted by the Lead rife like a fpout 
 to the roof of the muffle-, if the furface of the melt- 
 ed metal be extremely convex, confidering thequan- 
 tity of the mafs: if trie cupel appear of iuch a white 
 heat, that the colour communicated thereto by the 
 imbibed fcoriacannotbediftiricmilhed: ailthefefhew 
 
 **j 
 
 that the heat is too great, and that it ought to be 
 di mini fried. If, on the contrary, the vapours only ho- 
 ver, as it were, over the furface of the metal : if the 
 melted mafs be very flat, confidering its quantity; 
 if its ebullition appear but faint , if the fcorite, that 
 appear like little fiery drops of rain, have but a lan- 
 guid motion ; if the fcoria gather in heaps, and do 
 not penetrate the cupel ; if the metal be covered with 
 
 y it
 
 326 ELEMENTS of tie 
 
 it as with a glafiy coat; and laftly, if the cupel 
 look dull-, thefe are proofs that the heat is too 
 weak, and ought to be increaied. 
 
 The defign of this operation being to convert the 
 Lead into litharge, and to give it fufficient time 
 and opportunity to Icorify and carry off with it 
 whatever is not Gold or Silver ; the fire muft be 
 kept up to fuch a degree that the Lead may eafily 
 be turned into litharge, and yet that litharge not 
 be abforbed too haftily by the cupel, but that a 
 fmall quantity thereof may all along remain, like 
 a ring, round the melted metal. 
 
 The fire is to be gradually increafed as the ope- 
 ration draws nearer to its end : for, as the propor- 
 tion of the Lead to the Silver is continually leffen- 
 ing, the metallic mafs gradually becomes lefs fufi- 
 ble ; while the Silver defends the Lead mixed with 
 it from the aftion of the fire, and prevents its be- 
 ing eafily converted into litharge. 
 
 When the operation is finished, the cupel muft 
 ftill be left under the muffle, till it has imbibed all 
 the litharge, to the end that the bead of Silver may 
 be eafily taken out : for, without this precaution, it 
 would ftick fo fafb as not to be removed, but by 
 breaking off part of the cupel along with it. Care 
 muft alfo be taken to let this bead of Silver cool gra- 
 dually, and be perfectly fixed, before you draw it 
 from under the muffle : for if you expofe it at once 
 to the cold air, before .it be fixed, it will fweil, 
 fhoot into fprigs, and even dart out feveral little 
 grains to a confiderable diftance, which will be loft. 
 
 If the bead appear to have a yellowifh tinge, 'tis 
 a fign that it contains a great deal of Gold, which 
 muft be feparated from -it by the methods to be 
 hereafter (hewn. 
 
 It is proper to obferve that there is fcarce any 
 Lead that does not contain fome Silver ; too little 
 perhaps to defray the charges neceflary to feparate it, 
 
 vet
 
 PRACTICE 0/*CHYMisTRY. 327 
 
 yet confiderable enough to lead us into an error, by 
 mixing with the Silver obtained from an ore, and 
 increafmg its weight. And therefore, when the ope- 
 rations above defcribed are applied to the affaying of 
 an ore, in order to know how much Silver it yields, 
 it is previously neceflary to examine the Lead to 
 be ufed, and to afcertain the quantity of Silver it 
 contains, which mud be deducted from the total 
 weight of the bead of Silver obtained by purify- 
 ing it in this manner. 
 
 Silver may be feparated from its ore, and at the 
 fame time refined, by the fingle operation of the 
 cupel, without any previous fc&rification with Lead. 
 In order to do this, you muft pound the ore ; roaft 
 it, to diffipate all its volatile parts ; mix it with an 
 equal quantity of litharge, if it be refractory , divide 
 it into five or fix parcels, wrapping each in a bit of 
 paper; weigh out eight parts of granulated Lead for 
 one of ore, if it be fufible, and from twelve to fix- 
 teen, if it be refractory ; put one half of the Lead into 
 a very large cupel under the muffle, add thereto one 
 of the little parcels of ore, when the Lead begins to 
 fmoke and boil ; immediately flacken the fire a lit- 
 tle ; continue the fame degree of heat till you per- 
 ceive that the litharge formed round the metal, and 
 on its furface, begins to look bright ; then raife the 
 fire-, add a frefh parcel of ore^ continue proceeding 
 in the fame manner till you have put in all the ore ; 
 then add the remaining half of the granulated Lead, 
 and conduct the fucceeding part of the operation 
 in the fame manner as that of cupelling. 
 
 In this operation it is necefiary that the fire be not 
 too ftrongly urged, and that it be diminifhed every 
 time you add a frefh parcel of ore , that fo the Lead 
 and the litharge may have time to diffolve, fcorify, 
 and carry off in to the pores of the cupel, all the ad- 
 ventitious matters with which your Silver may be 
 mixed. Notwithftanding this precaution, when the 
 Y 4 ore
 
 328 ELEMENTS of the 
 
 pre is refractory, there often gathers in the cupel a 
 great quantity of fcoria, together alfo with fome of 
 the ore that could not be difiblved and fcorified. 
 It is with a view to remedy this inconvenience that 
 the fecond moiety of the Lead is added towards 
 the end, which completes the difiblution and fco- 
 rification of the whole , fo that by means thereof 
 no fcoria, or very little, is left in the cupel at the 
 end of the operation. 
 
 The operation of the cupel is chiefly ufed to pu- 
 rify Silver from the alloy of Copper ; becaufe this 
 metal, being more fixed and harder to calcine than 
 other metallic fubftances, is the only one that re- 
 mains united with Silver and Lead, after roaftingand 
 fcorification with Lead. It requires no lefs than fix- 
 teen parts of Lead to dcftroy it in the cupel, and le- 
 parate it from Silver. It melts into one mafs with 
 the Lead ; and the glafs produced by thefe two 
 metals, deprived of their phlogiflon, inclines to a 
 brown or a black colour j by which appearance ch icfly 
 we know that our Silver was alloyed with Copper. 
 
 PROCESS III. 
 
 To purify Silver by Nifre. 
 
 GRANULATE the Silver you intend to pu- 
 rify, or reduce it to thin plates-, put it into 
 a good crucible -, add thereto a fourth part in weight 
 of very dry pulverized Nitre, mixed with half the 
 weight of the Nitre of calcined Wine-lees, and 
 about a fixth part of the fame weight of common 
 glafs in powder. Cover this crucible with another 
 crucible inverted ; which mult be of fuch a fize that 
 its mouth may enter a little way into that of the 
 lower one, and have its bottom pierced with a hole 
 of about two lines in diameter. Lute the two cru- 
 cibles together with clay and Wiadibr-loam. Wher}
 
 PRACTICE C/'CHYMISTRY. 329 
 
 the lute is dry, place the crucibles in a melting fur- 
 nace. Fill the furnace with Charcoal, taking care 
 however that 'the fuel do not rife above the upper 
 crucible. 
 
 Kindle the fire, and make your vefiels of a mid- 
 dling-red heat. When they are fo, take up with 
 the tongs a live coal, and hold it over the hole of 
 the upper crucible. If you immediately perceive 
 a vivid ipjendour round the coal, and at the fame 
 time hear a gentle hiding noife, it is a fign that the 
 fire is of a proper ftrength , and it muft be kept up 
 at the fame degree till this phenomenon ceafe. 
 
 Then increafe the fire to the degree requifite to keep 
 pure Silver in fufion-, and immediately after take your 
 vefiels out of the furnace. You will find the Silver 
 at the bottom of the lower crucible, covered with 
 a mafs of -Alkaline fcoria of a greenifli colour. If the 
 metal be not rendered perfectly pure and ductile by 
 this operation, it muft be repeated a fecond time. 
 
 OB S ERRATIC N S. 
 
 THE purification of Silver by Nitre, as well as 
 the procefs for refining it on the cupel, is founded 
 on the property which this metal pofleflfes of refifting 
 the force of the ftrongeft fire, and the power of the 
 moft active iblvents, without lofing its phlogifton. 
 The difference between thefe two operations confifts 
 wholly in the fubftances made ufe of to procure the 
 fcorification of the imperfect metals, or femi-metals, 
 that may be combined with the Silver. In the for- 
 mer this was obtained by Lead, and here it is effected 
 by Nitre. This Salt, as we have fhewn, hath the pro- 
 perty of calcining and quickly deftroying all me- 
 tallic fubftances, by confuming their phlogifton, ex- 
 cept the perfect metals, Gold and Silver, which alone 
 are able to refift its force. This method may there- 
 fore be employed to purify Gold as well as Sil- 
 yer, or indeed both the two mixed together. 
 
 In
 
 33 E L E M E N T s of the 
 
 In this operation the Nitre is gradually atkali- 
 zated, as its Acid is confumed with the phlogifton of 
 the metallic fubftances. The Alkaline Salt and 
 pounded glafs are added, with a view to promote 
 the fufion of the metalline calxes, as faft as they 
 are formed, and to fix and retain the Nitre, which, 
 as we (hall prefently fee, is apt to fly off in a cer- 
 tain degree of heat. 
 
 The precaution of covering the crucible with ano- 
 ther crucible inverted, which hath only a fmall hole 
 in its bottom, is defigned to prevent any of the Silver 
 from being loft in the operation : for when the Ni- 
 tre comes to be adted on by a certain degree of heat, 
 and efpecially when it deflagrates with any inflam- 
 mable matter, part of it flies off, and fo rapidly 
 too as to be capable of carrying off with it a good 
 deal of the Silver. The little hole left in the co- 
 vering crucible is necefiary for giving vent to the 
 vapours, which rife during the deflagration of the 
 Nitre, as they would otherwife open themfelves a 
 pafiage by burfting the veffels. After the opera- 
 tion this vent-hole is found befet with many little 
 particles of Silver, which would have been loft if 
 the crucible had not been covered. 
 
 If you fhould obferve, during the detonation of 
 the Nitre, that a great many vapours iffue through 
 the vent-hole with a confiderable hiffing noife, even 
 without applying the coal, you muft take it for a 
 fign that the fire is too brifk, and accordingly check 
 it; elfe a great deal of the Nitre will be diflipated, 
 and with it much Silver. 
 
 You murt obferve to take the Silver out of the 
 fire as foon as it is in fufion : for if you neglect this, 
 the Nitre being entirely diflipated or alkalizated, 
 the calxes of the metals deftroyed by it may pofiibly 
 recover a little phlogifton, communicated either by 
 the vapours of the charcoal, or by little bits of coal 
 accidentally falling into the crucible j by which 
 5 means
 
 PRACTICE of CHYMISTRY. 331 
 
 means fome portion of thofe metals being reduced 
 will mix again with the Silver, prevent its having 
 the defined degree of purity and ductility, and 
 oblige you to begin the operation afrefh. 
 
 PROCESS IV. 
 
 To dijjolve Silver in Aqua Fortis, and thereby fepa- 
 rate it from every other metalline Subftance. The 
 Purification of Aqua Fords. Silver precipitated 
 by Copper. 
 
 THE Silver you intend to difiblve being beaten 
 into thin plates, put it into a glafs cucurbit ; 
 pour on it twice its weight of good precipitated Aqua 
 Fortis , cover the cucurbit with a piece of paper, and 
 fet it on a fand-bath moderately heated. The Aqua, 
 Fortis will begin to diffolve the Silver as foon as it 
 comes to be a little warm. Red vapours will rife ; 
 and from the upper furfaces of the Silver there will 
 feem to iffue dreams of little bubbles, alcending to 
 the top of the liquor, between which and the Silver 
 they will form, as it were, a number of fine chains : 
 this is a fign that the dififolution proceeds duly, and 
 that the degree of heat is fuch as it ouscht to be. If 
 
 O O 
 
 the liquor appear to boil and be agitated, a great 
 many red vapours rifing at the fame time, it is a fign 
 that the heat is too great, and mould be lelTened till 
 it be reduced to the proper degree indicated above: 
 having obtained that, keep it equally up till no more 
 bubbles or red vapours appear. 
 
 If your Silver be alloyed with Gold, the Gold 
 will be found, when the diflblution is finimed, at 
 the bottom of the veflel in the form of a powder. 
 The folution muft now be decanted while it is yet 
 warm : on the powder pour half as much frem Aqua 
 Fortis as before, and make it boil-, again decant this 
 fecond Aqua Fortis^ and repeat the fame a third 
 
 time;
 
 332 ELEMENTS of the 
 
 time; then with fair water wafh the remaining pow- 
 der well : it will be of a brown colour inclining to 
 red. In the obfervations we fhall fhew how the 
 Silver is to be feparated from the Aqua Fortis. 
 
 OBSERVATIONS. 
 
 ALL the precedes on Silver already delivered, 
 whether for extracting it from its ores, or for refin- 
 ing it, either by the Cupel or by Nitre, are appli- 
 cable to Gold alfo. And if Silver be alloyed with 
 Gold before it undergo thofe feveral operations, 
 it will ftill remain alloyed therewith after them, in 
 the fame manner, and in the fame quantity , becaufe 
 both metals bear them equally. All therefore, that 
 can be expected from thole feveral afiays, is the fe- 
 paration of every thing that is neither Silver nor 
 Gold from thefe two metals. But in order to fe- 
 parate thefe two from each other, recourfe muft be 
 Lad either to the procefs laid down under the head 
 of Gold, or to that here defcribed, which is the 
 mod commodious, the molt ufual, and known by 
 the names of Quartation and the Parting Affay. 
 
 Aqua Fortis is the true Solvent of Silver, and is 
 utterly incapable of diflblving the lead atom of 
 Gold. If therefore a mafs confiding of Gold and 
 Silver be expc fed to the action of Aqua Fortis, that 
 Acid will ciiflblve the Silver contained in the com- 
 pound, without touching the gold, and the two 
 metals will be fcparated from each other. This me- 
 thod of parting them is juft the reverfe of that de- 
 fcribed before under the head of Gold, which is 
 effected by the means of Aqua Regis. 
 
 To the fuccefs of this feparation, by means of A- 
 quaFortis,fcvera\ conditions are effentially neceflary. 
 The firft is, that the Gold and Silver be in due pro- 
 portion to each other ; that is, there muft be at lead 
 twice as much Silver as Gold in the metalline mafs, 
 ocherwife the Aqua Fortis will not be able to diffblve
 
 PRACTICE OMISTRY. 333 
 
 it, for the reafon formerly given. If therefore 
 the mafs contain too little Silver, it mud either be 
 melted down again, and a proper quantity of Silver 
 added ; or elfe, if the Gold be in a fufficient pro- 
 portion to the Silver, they may be parted by means 
 of Aqua Regis. 
 
 Secondly, it is neceffary that the dqua Forth em- 
 ployed in this operation be abfolutely pure, and free 
 from any taint of the Vitriolic or Marine Acid : for, 
 if it be adulterated with the Vitriolic Acid, the Sil- 
 ver will precipitate as faft as it diffolves, and fo the 
 precipitated Silver will again mix with the Gold. If 
 the Aqua Forth contain any of the Marine Acid, 
 the Silver will be precipitated in that cafe alfo; and 
 this inconvenience will be attended with another, 
 namely, that the menftruum, being partly an Aqua. 
 RegiS) will difiblve fome of the Gold. You muft 
 therefore be very lure that your Aqua Forth is pure,, 
 before you fet about the operation. In order to dif- 
 cover its quality, you muft try it by diflfolving, in a 
 fmall portion thereof, as much Silver as it will take 
 up : if the Aqua Forth grow opaque and milky as 
 it diffolves the Silver, 'tis a a fign ic contains fome 
 foreign Acid, from which it muft be purified. 
 
 In order to effecl: this, let the portion of Aqua 
 Forth ufed for the above trial ftand to fettle : the 
 white milky part will gradually fall to the bottom 
 of the vefTel. When it is all fallen, gently decant 
 the clear liquor, and pour a fevv drops of this de- 
 canted folution of Silver into the Aqua Forth which 
 you want to purify. It will inftantly become milky. 
 Let the white particles precipitate as before, and 
 then add a few more drops of your folution of Silver, 
 If the Aqua Forth ftill become milky, let it preci- 
 pitate again, and repeat this till you find that a drop 
 of your Solution of Silver, let fall into this Aqua 
 ) does not make it in the leaft turbid. Then 
 
 filter
 
 334 ELEMENTS of the 
 
 filter it through brown paper, and you will have an 
 Aqua For t is perfectly fit for the Parting Afiay. 
 
 The white particles that appear and fettle to the 
 bottom, on diflblving Silver in an Aqua Fortis adul- 
 terated with a mixture of fome foreign Acid, are 
 no other than that very Silver, which is no fooner 
 diflblved by the Nitrous Acid than it deferts that 
 iblvent to unite with the Vitriolic or Marine Acid, 
 wherewith it has a greater affinity, and falls to the 
 bottom with them. And this happens as long as 
 there remains in the Aqua Fcrtis a fingle atom of 
 either of thofe two Acids. 
 
 When therefore your Aqua Fcrtis hath diflblved 
 as much Silver as it is capable of taking up, and 
 when all the white particles formed during the dif- 
 folution are fettled to the bottom, you may be af- 
 fured that the portion which remains clear and lim- 
 pid is a folution of Silver in an exceeding pure Aqua 
 Fortis. But if the folution of Silver thus depurat- 
 ed be mixed with an Aqua Fortis adulterated with 
 the Vitriolic or Marine Acid, a like precipitation 
 will immediately enfue, for the reafons above given, 
 till the very laft particle of the heterogeneous Acid 
 contained in \\itAqua Fortis be precipitated. . 
 
 Aqua Fortis purified by this method contains no 
 extraneous fubftance whatever, except a fmall por- 
 tion of Silver , fo that it is very fit for the parting 
 procefs. But if it be intended for other chymical 
 purpofes, it muft be rectified in a glafs retort with 
 a moderate heat, in order to feparate it from the 
 fmall portion of Silver it contains, which will re- 
 main at the bottom of the retort. 
 
 The third condition necefiary to the fuccefs of this 
 operation is, that your Aqua Fortis be neither too 
 aqueous, nor too highly concentrated. If too weak, 
 it will not aft upon the Silver: and the confequence 
 will be the fame if it be too ftrong. Both thefe in- 
 conYeniencies arc eafily remedied : for in the former 
 
 cafe
 
 PRACTICE of CHYMISTRY. 335 
 
 cafe part of the fuperfluous phlegm may be drawn 
 off by diftillation -, or a fufficient quantity of much 
 ftronger Aqua Fortis may be mixed with that which 
 is too weak : and in the latter cafe, very pure rain 
 water, or a weaker Aqua Fortis^ may be mixed 
 with that which is too ftrong. 
 
 You may fatisfy yourftlf whether or no your Aqua 
 Fortis hath the requifite degree of ftrengch, by dil- 
 folving therein a thin plate confiding of one part 
 Gold and two or three parts Silver , which plate 
 mud be rolled up in form of a paper coffin. If, 
 when all the Silver contained in the plate is difiblv- 
 ed, the Gold remains in the form of the coffin, it is a 
 fign that your Solvent has a due degree of ftrength. 
 If, on the contrary, the Gold be reduced to a pow- 
 der, it is a proof that your Aqua Forth is too ftrong, 
 and ought to be weakened. 
 
 The Gold remaining after the diflblution of the 
 Silver muft be melted in a crucible with Nitre and 
 Borax, as hath already been laid under the procefs 
 for parting Gold and Silver by means of Aqua Re- 
 gis. As to tKe Silver which remains diffblved in the 
 Aqua Fortis, there are feveral ways to recover it. 
 
 The moft ufual is to precipitate it by the interpo- 
 lation of Copper, which hath a greater affinity than 
 Silver with the Nitrous Acid*. For this purpofe 
 the folution is weakened by adding twice or thrice 
 as much very- pure rain water. The cucurbit con- 
 taining the folution is let on a fahd-bath gently 
 heated, and very clean plates of copper put into it. 
 The furfaces of thefe phtes are loon covered with 
 little white fcales, which gradually fall to the bot- 
 tom of the vefiel, as they come to be collected in 
 quantities. It is even proper to ftrike the cucurbit 
 gently now and then, in order to make the fcales 
 of Silver from the copper plates, and fo make 
 room for a new crop. 
 
 * See the Table <?f Affinities, Column IV. 
 
 The
 
 336 ELEMENTS of f&e 
 
 The Aqiia Fortis parts with the Silver by degrees 
 only, as it diflblves the Copper ; and therefore the 
 liquor gradually acquires a bluifh green colour as 
 the precipitation advances. This precipitation of 
 the Silver is to be continued as long as any remains 
 diflblved in the A^ua Fortis : you may be fare that 
 your liquor contains no more Silver, if the furface 
 of a frdh plate of Copper laid therein remain clean 
 and free from afh-coloured or greyifh particles ; 
 or if one drop of a folution of Sea-falt let fall into, 
 it produce no white or milky cloud. 
 
 The precipitation being finifhed, the liquor is to 
 be gently poured off from the precipitated Silver, 
 which muft be rinfed in feveral waters, and even 
 made to boil therewith, in order to free it wholly 
 from the diflblved Copper. The Silver thus well 
 warned muft be thoroughly dried, mixed with a 
 fourth of its weight of a flux compounded of equal 
 parts of Nitre and calcined Borax, and then melted 
 in a crucible. On this occafion care muft be taken 
 to raife the fire gently and gradually, till the Sil- 
 ver be brought to fufion. 
 
 With what accuracy Ibever the precipitated Silver 
 be wafhed, in order to free it from the folution of 
 Copper, yet the Silver will always be found alloyed 
 with a fmall portion of the Copper : but then this 
 Copper is eafily deftroyed by the Nitre, with which 
 the Silver is afterwards melted ; Ib that the latter 
 metal remains perfectly pure after the operation. 
 
 Though the Silver be not previoufly cupelled, but 
 be alloyed with other metallic fubftances at the time 
 it is thus diflblved, yet the difiblving, precipitating, 
 and fufing it with Nitre would befufficienttofeparate 
 it accurately from them all, and refine it to a degree 
 of purity equal to that obtained by the cupel. 
 
 The Copper that remains diflblved in the Aqua 
 Fortis, after the precipitation of the Silver, may in 
 like manner be precipitated by Iron, and, as it re- 
 tains
 
 PRACTICE ^CHYMISTRY. 337 
 
 tains a fmall portion of Silver, ought not to be neg- 
 lected when thefe operations are performed on con- 
 fiderable quantities. 
 
 In the two next proceffes we (hall mew two other 
 methods of feparating Silver from Aqua Fortis. 
 
 PROCESS V. 
 
 To feparate Silver from the Nitrous Acid fa T)iftilla- 
 tion. Cryftals of Silver. The Infernal Stone. 
 
 INTO a large, low, glafs body put the folution 
 of Silver, from which you intend to feparate the 
 Silver by diftillation. To this body fit a tubulated 
 head provided with its ftopple. Set this alembic 
 10 a fand-bath, fo that the body may be almoft 
 covered with fand : apply a receiver, and diftill with 
 a moderate heat, fo that, the drops may fucceed 
 each other at the diftance of fome feconds. If the 
 receiver grow very hot, check the fire. When red 
 vapours begin to appear, pour irito the alembic, 
 through the hole in its head* a frefh quantity of 
 your folution of Silver, firft made very hot. Con- 
 tinue diftilling in this manner, and repeating the 
 addition of frefh liquor, till all your folution be put 
 into the alembic. When you have no more frefh 
 folution to put in, and when, the phlegm being all 
 come over, red vapours begin again to appear, con- 
 vey into the alembic half a dram or a dram of tal- 
 low, and diftill to drynefs ; which being done, in- 
 creafe your fire fo as to make the vefifel containing 
 the fand-bath red-hot. In the alembic you will 
 find a calx of Silver, which muft be melted in a 
 crucible with fome foap and calcined wine-lees. 
 
 VOL. I. Z O&SER-
 
 ELEMENTS of the 
 
 OBSERVATIONS. 
 
 A low cucurbit is recommended for this opera- 
 tion, to the intent that the particles of the Nitrous 
 Acid, which are ponderous, may the more eafily 
 be carried up. and pals over into the receiver. For 
 the fame reafon the cucurbit is directed to be al- 
 moft wholly covered with fand ; left otherwiie the 
 acid vapours fhould be condenfed about that part 
 of the cucurbit, which, being out of the fand, 
 would be much cooler than that which is encom- 
 pafTed therewith, and from thence fhould fall baek 
 again to the bottom , by which means the diftilla- 
 tion would certainly be retarded, and the veflel pro- 
 bably be broken. 
 
 Notwithftanding thefe precautions the veflels 
 are liable to break in fuch diltillations -, efpecially 
 when they contain a great deal of liquor. With 
 a view therefore to prevent this accident, we or- 
 dered that the whole quantity of the folution of 
 Silver to be diftilled fhould not be put at once into 
 the alembic. The little bit of tallow, added to- 
 wards the end of the operation, is intended to hin- 
 der the metal from adhering clofely to the veflel, 
 as it would otherwiie do, when all the moifture is 
 dilTipated. 
 
 The Sodp and Fixed Alkali mixed with the Sil- 
 ver to flux it, after its feparation from the Aqua 
 Fortis in this way, ferve to abforb luch of the mod 
 fixed particles of the Acid as may (till remain 
 united with the metal. 
 
 If the diftillation be flopped when part of the 
 phlegm is drawn olf, and the liquor be then fuftcrtd 
 to cool, many cryftals will fhoot therein, which are 
 a Neutral Salt conftituted of the Nitrous Acid and 
 Silver. If the dillillation be carried further, and 
 itonped \vhen near its conclufion, the liquor being 
 
 then
 
 PR AC t ICE of CH YMIST R v. 
 
 then fuffcred to cool will wholly coagulate into a 
 blackilh mafs called the Infernal Stone. 
 
 This way of feparating Silver from its folvent is 
 attended with, the advantage of faving all the Aqua 
 Fortis, which is excellent, and fit to be employed 
 in other operations. 
 
 PROCESS VI. 
 
 To feparate Silver from the Nitrous Acid Z>y Precipi- 
 tation. Luna Cornea. Luna Cornea reduced. 
 
 INTO your folution of Silver pour about a 
 fourth part in weight of Spirit of Salt, folution 
 of Sea-falt, or folution of Sal Ammoniac. The li- 
 quor will inftantly become turbid and milky. Add 
 twice or thrice its weight of fair water, and let it 
 ftand fome hours to fettle. It will depofite a white 
 powder. Decant the clear liquor, and on. the pre- 
 cipitate pour frefh Aqua Fortis^ or Spirit of Salt, 
 and warm the whole on a fand-bath with a gentle 
 heat for fome time. Pour off this fecond liquor, 
 and boil your precipitate in pure water, fhifting it 
 feveral times > till the precipitate and the water be 
 both quite infipid. Filter the whole, and dry the 
 precipitate, which will be a Luna Cornea^ and muft 
 be reduced in the following manner. 
 
 Smear the infide of a good crucible well with 
 foap. Put your Luna Cornea into it 5 cover it with 
 half its weight of Salt of Tartar, thoroughly dried 
 and pulveriled , prefs the whole hard down ; pour 
 thereon as much oil, or melted tallow, as the pow- 
 der is capable of imbibing , fet the crucible thus 
 charged, and clofe covered, .in a melting furnace, 
 and, for the firft quarter .of an hour, make no more 
 fire than is necenary to make the crucible mode- 
 rately red : after that raife it fo as to melt the Sil- 
 
 Z 2 ver
 
 340 ELEMENTS of tie 
 
 ver and the Salt, throwing into the crucible from 
 time to time little bits of tallow. When it ceafeg 
 to fmoke, let the whole cool j or pour it into a hol- 
 low iron cone, warmed and tallowed. 
 
 BS ERVAT JO N S. 
 
 THE procefs here delivered furnifhes us with the 
 means of procuring Silver in a degree of purity 
 which is not to be obtained by any other method 
 of treating it whatever. That which is refined on 
 the cupel always retains a fmall portion of copper, 
 from which it cannot poflibly be feparated in that 
 way : but if it be diflblved in Aqua Fortis, and 
 precipitated thence in a Luna Cornea by the Marine 
 Acid, the precipitate will be an abfolutely pure 
 Silver, unalloyed with that fmall portion of Copper 
 which it retained on the cupel. The reafon of this 
 effect is, that the Copper remains as perfectly dif- 
 folved in Spirit of Salt and in /tqua Regia as in Aqua 
 Fcrtis : fo that when the Silver, and the Copper 
 with which it is alloyed, are diflblved together in 
 the Nitrous Acid, if the Acid of Sea-lak be mixed 
 with the fohuion, part of this latter Acid unites 
 with the Silver, and therewith forms a new com- 
 pound, which not being foluble in the liquor, falls 
 to the bottom. The other part of the Acid mix- 
 ing with the Nitrous, forms an Aqua Regis, in 
 which the Copper remains diflblved, without lepa- 
 rating from it. 
 
 Frefh Acid is poured on the precipitated calx of 
 Silver, in order to complete the folution of the 
 fmall portion of Copper that may have efcaped the 
 aflion of the firft folvent. It is indifferent whether 
 the Spirit of Salt or the Spirit of Nitre be employed 
 for this pnrpofe, becaufe they both diffolve Copper 
 alike, and becaufe Silver precipitated by Spirit of 
 Salt is, noc foluble in either. 
 
 After
 
 PRACTICE of CHYMISTRY. 341 
 
 After this it is neceflary to wafh the precipitate 
 well with pure water, in order to free it entirely 
 from the particles of Aqua Fortls adhering to the 
 Silver : becaufe they may poflibly contain fome*- 
 thing of Copper, which would mix with the Silver 
 in melting, and taint its purity. 
 
 If this precipitate of Silver be expofed to the 
 fire, unmixed with any other fubftance, it melts as 
 foon as it begins to be red , and if the fire be in- 
 creafed, part thereof will be diffipated in vapours, 
 and the reft will make its way through the crucible. 
 But being poured out as foon as melted, it coagu- 
 lates into a cake of a purplifh red colour, femi- 
 tranfparent, ponderous, and in fome degree pliable, 
 efpecially if it be very thin. It bears fome refern- 
 blance to horn, which hath occafioned it to be called 
 Luna Cornea. 
 
 As Luna Cornea is not foluble in water, recourfe 
 muft be had to fufion, in order to reduce it, by fe- 
 parating from the Silver thofe acids which give it 
 the abovementioned properties. Fixed Alkalis and 
 fatty matters are very fit to produce that fepara^ 
 tion. 
 
 We directed that the infide of the crucible, in 
 which the reduction is to be made, mould be care- 
 fully fmeared with foap, and that the Luna Cornea, 
 fhould be quite covered with a Fixed Alkali and 
 fat, to the end that when the heat is ftrong enough 
 to diflipate it in vapours, or to attenuate it fo as to 
 render it capable of penetrating the crucible, it may 
 be forced to pafs through matters qualified to ab- 
 forb its Acid, and reduce it. 
 
 Luna Cornea may alfo be reduced by being 
 melted with fuch metalline fubftances as have a 
 greater affinity than Silver with the Acids where- 
 with it is impregnated. Of this kind are Tin, 
 Lead, Regulus of Antimony : but the Luna Cornea 
 rufhes fo impetuoufiy into conjunction with thofe 
 
 Z 3 ' metal-
 
 342 ELEMENTS of tie 
 
 metalline fubftances, that a vaft many vapoafs ariie, 
 and carry off with them part of the Silver : if 
 therefore you c:iufe to effeft the reduction by the 
 interpofition of luch metalline fubftances, you muft 
 employ a retort inftead of a crucible. 
 
 But this method is attended with another incon- 
 venience -, which is, that fome part of thofe metal- 
 line fubftances may unite with the Silver, and adul- 
 terate it; for which reafon it is bed to keep to the 
 method firft propofed. 
 
 PROCESS VH. 
 
 Vo dij/ohe Silver, and feparate it from Gold, by 
 
 Cementation. 
 
 MI X thoroughly together fine brick-duft four 
 parts, Vitriol calcined to rednefs one part, 
 and bea-falt or Nitre one part. Moiften this pow* 
 der with a little water. With this cement cover the 
 bottom of a crucible half an inch thick ; on this firft 
 bed lay a thin plate of the mafsof Gold and Silver 
 you intend to cement, and which you muft previ- 
 oufly take care to beat into fuch thin plates. Cover 
 this plate with a fecond layer of cement, of the 
 fame thickncfs as the former , on this fecond bed 
 lay another plate of your metal ; cover it in like 
 manner with cement \ and fo proceed till the cru- 
 cible be filled to within half an inch of its brim. 
 Fill up the remaining fpace with cement, and clofe 
 the crucible with a cover, luted with a pafte made 
 of Wind for- loam and water : fet your crucible 
 thus charged in a furnace, whofe fire-place is deep 
 enough to let it be entirely furrounded with coals, 
 quite up to 4ts mouth. Light fome coals in the 
 furnace, taking care not to make the fire very brifk 
 at firft ; encreafe it by degrees, but only fo far as 
 i tq
 
 PRACTICE ^CHYMISTRY. 343 
 
 to make the crucible moderately red -, keep up the 
 .fire in this degree for eighteen or twenty hours : 
 then let the fire go out , open the crucible when it 
 is cold, and feparate the cement from your plates 
 of Gold. Boil the Gold repeatedly in fair water, 
 till the water come off quite infipid. 
 
 OBSERVATIONS. 
 
 IT cannot but feem ftrange that, after having fo 
 often declared the Acid of Sea-falt to be incapable 
 of diflblving Silver, we (hould direct eirher Nitre 
 or Sea-falt indifferently to be employed in com- 
 pofmg a cement, which is to produce an Acid ca- 
 pable of eating out all the Silver mixed with Gold. 
 It is eafy to conceive how the Nitrous Acid extri- 
 cated from-its bafis by means of the Vitriolic Acid 
 may produce this effect : but if Sea-falt inftead of 
 Nitre be made an ingredient in the cement, its 
 Acid, though fet at liberty in the fame manner by 
 the Vitriolic Acid, muft at firft fight appear unable 
 to anfwer the end. 
 
 In order to remove this difficulty we muft here 
 obferve that there are two very effential differences 
 between the Marine Acid collected in a liquor, as 
 it is when diftilled in the ufual manner, and the 
 fame Acid feparated from its bafis in a crucible, as 
 jt is in cementation. 
 
 The firft of thefe two differences is, that the Acid 
 being reduced into vapours when it acts on the Sil- 
 ver in cementation, its activity is thereby greatly 
 encreafed : the fecond is, that in the crucible it 
 fuftains a vaftly greater degree of heat than it can 
 ever bear when it is in the form of a liquor. For, 
 after it is once diftilled and feparated from its bafis, 
 it cannot fuftain any extraordinary degree of heat 
 without being volatilized and entirely diflipated : 
 whereas while it continues united with its bafis it is 
 much more fixed, and cannot be feparated but by a 
 Z 4 very
 
 344 ELEMENTS of the 
 
 very intenfe heat. Confequently, if it meet with 
 any body to diffolve, at the very inftant of its fepa- 
 ration from its bafts, while it is actuated by a much 
 fiercer heat than can ever be applied to it on any 
 Other occafion, it rnuft operate upon that body 
 with fo much the more efficacy : and thus it comes 
 to pafs that in cementation it has the power of dif- 
 folving Silver, which it would be incapable of 
 touching if it were not fo circumftanced. 
 
 But herein Gold differs from Silver : for, what- 
 ever force the Nitrous or the Marine Acid may 
 exert, when extricated from their bales in the ce- 
 menting crucible, this metal obftinately rcfufes to 
 yield to either of thole Acids ieparately, and can 
 never be diffolved by them, unltfs both be united 
 together. 
 
 Our cementation therefore is actually a parting 
 procefs in the dry way. The Silver is dilfolved, 
 and the Gold remains unaltered. Nay, as the 
 action of the Acids is much ftronger when they are 
 applied this way, than when they are ufcd for dif- 
 folution in the moill way, the Nitrous Acid, which 
 in the common parting procefs will not diffolve 
 Silver unlefs its weight be double that of the Gold, 
 is able in cementation to diflblve a very fmall quan- 
 tity of Silver diffufed through a large quantity of 
 Gold. 
 
 It fometimes happens that after the operation the 
 cement proves extremely hard, fo that it is very 
 troublefome to fcparate it entirely from the Gold, 
 In this cafe it mult be foftened by moiftening it with 
 hot water. This hardnefs which the cement ac- 
 quires isoccafioned by the fufion of the Salts, which 
 is the effect of too ftronga heat. It was in order to 
 prevent this, and that a due degree of heat might 
 be applied, without the danger of melting the falts, 
 that we directed the cement to be mixed with 
 $ confiderable quantity of earthy matter incapable
 
 PRACTICE 0/"CHYMisTRY. 345 
 
 of fufion, fuch as brick-duft. A greater inconve- 
 nience Hill will enfue, if the fire be made fo ftrong 
 as to melt the Gold: for then it will partly com- 
 mix again with the other metalline fubftances dif- 
 
 C3 
 
 folved by the cement, and confequendy will not 
 be purified. 
 
 The crucible is covered, and its cover luted on, 
 to prevent the acid vapours from being too foon 
 diffipated, and to force them to circulate the longer 
 in the crucible. However, it is neceflary that thofe 
 vapours mould find a vent at laft, otherwife they 
 would burft the veffel : and for this reafon we di- 
 rected the crucible to be luted only with Windfor- 
 loam, which does not grow very hard by the action 
 of fire, and fo is capable of yielding and giving 
 pafiage to the vapours, when a certain quantity of 
 them is collected in the crucible, and they begin 
 to ftruggle for an efcape on every fide. 
 
 When the operation is finiQied, the Silver dif- 
 folved by the Acid of the cement is partly diftri- 
 buted through the cement, and partly in the Gold 
 itfelf, which is impregnated therewith. For this 
 reafon the Gold muft be warned feveral times in 
 boiling water, till the water become abfolutely in- 
 fipid : for, if the Gold be melted without this pre- 
 caution, it will mix again with the Silver : the ce- 
 ment alfo may be wafhed in the fame manner to re- 
 cover the Silver it contains. 
 
 Though this cementation be, properly fpeaking, 
 a purification of Gold, yet we have placed it among 
 the procefles on Silver, becaufe it is the Silver that 
 is difiblved on this occafion, and becaufe this is a 
 particular way of difiblving that metal. Moreover, 
 moft of the procefles hitherto delivered, either on 
 Gold or Silver, are equally applicable to both thefe 
 metals. 
 
 If the Gold do not appear quite pure after the 
 cementation, the procefs muft be repeated. 
 
 There
 
 346 ELEMENTS cf the 
 
 There are feveral ways to know the finenefs of 
 Gold, the quantity of Silver with which it is alloy- 
 ed, and the proportion in which thefe two metals 
 are mixed in a mafs purified by the cupel. 
 
 One of the fimpleft is the trial by the Touch- 
 ilone -, which indeed is hardly any more than judg- 
 ing by the eye only, from the colour of the com- 
 pound metal, what proportion of Gold and Silver 
 it contains. 
 
 The Touch-done is a fort of black marble, whole 
 furface ought to be half policed. If the metalline 
 mafs which you want to try be rubbed on this done, 
 it leaves thereon a thin coat of metal, the colour of 
 which may be eaftly obferved. Such as are ac- 
 cuftomed to fee and handle Gold and Silver can at 
 once judge very nearly from this fample in what 
 proportion the two metals are combined: but, for 
 greater accuracy, thofe who are in the way or hav- 
 ing frequent occafion for this trial are provided 
 with a fufficient number of fmall bars or needles, 
 of which one is pure Gold, another pure Silver, and 
 all the reft confid of thefe two metals mixed toge- 
 ther in different proportions, varied by carats, or 
 even by fractions of carats, if greater exa&nefs be 
 required. 
 
 The finenefs of each needle being marked on it, 
 that needle, whole colour feems to come neared the 
 colour of the metalline dreak on the Touch-done, is 
 rubbed on the done by the fide of that ftreak. This 
 needle likewife leaves a mark ; and if there appear 
 to be no difference between the two metalline dreaks, 
 the metalline mafs is judged to be of the fame fine- 
 nefs as the needle thus compared with it. If the' 
 eye difcovers a fen fible difference, another needle is 
 fought for whofe colour may come nearer to that of 
 the metal to be tried. But though a man be ever 
 fo well verfed in judging thus of the finenefs of Gold 
 by the eye only, he can never be perfectly and ac- 
 curately
 
 PRACTICE ^f CHYMISTRY. 347 
 
 curately fare of it by this means alon?. If fuch 
 certainty be required, recourfe muft be had to the 
 parting aflay ; and yet when you have gone through 
 it, there always remains a fmall quantity of the 
 metal, which fhould have been diffolved, and yet 
 efcaped the action of the folvent. For example, if 
 you make ufe of Aqua Regis, the Silver that re- 
 mains after the operation ftill contains a little Gold ; 
 and, if you make ufe of Aqua Fortis, the Gold that 
 remains after the operation ftill contains a little 
 Silver. And therefore if you refolve to carry the 
 reparation of thefe two metals ftill further by fol- 
 vents, it will be neceffary, after you have gone 
 through one parting procefs, to perform a fecond 
 the contrary way. For example, if you begin with 
 Aqua Fortis, then, after it has diffolved all the Silver 
 in the metalline mafs that it is capable of taking up, 
 diffolve the remaining Gold in Aqua Regis; by which 
 means you will fepar-ate the fmall portion of Silver 
 left in it by the Aqua Fortis. The contrary is to 
 be done if you made ufe of Aqua Regis firft. 
 
 CHAP. III. 
 
 Of COPPER. 
 
 PROCESS I. 
 
 'To feparate Copper from its Ore. 
 
 i EAT your Copper ore to a fine powder, hav- 
 ing firft freed it as accurately as poffible, by 
 warning and roafting, from all ftony, earthy, ful- 
 phureous, and arfenical parts. Mix your ore thus 
 pulverized with thrice its weight of the black flux ; 
 put the mixture into a crucible , cover it with com- 
 mon fait to the thicknefs of half an inch, and prefs 
 
 the
 
 348 ELEMENTS of the 
 
 the whole down with your finger. With all this 
 the crucible rrm ft be but half lull. Set it in a melt- 
 ing furnace -, kindle the fire by degrees, and raife it 
 infenfibly till you hear the Sea-falt crackle. When 
 the decrepitation is over, make the crucible mode- 
 rately red-hot for half a quarter of an hour. Then 
 give a confiderable degree of heat, exciting the fire 
 with a pair of good perpetual bdiows, io that the 
 crucible may become very red-hot, and be perfectly 
 ignited. Keep the fire up to this degree for about 
 a quarter of an hour-, then take out the crucible, 
 and with a hammer (Irike a few blows on the floor 
 whereon you fct it. Break it when cold. If the 
 operation hath been rightly and fuccefsfully perform- 
 ed, you will find at the bottom of the vefiel a hard 
 Regulus, of a bright yellow colour, and femi-mal- 
 leable ; and over it a fcoria of a yellowifh brown 
 colour, hard and mining, from which you may fc- 
 parate the Regulus with a hammer. 
 
 OBSERVATIONS. 
 
 COPPER in the ore is often blended with feveral 
 other metallic fubftances, and with volatile miner 
 rals, fuch as Sulphur and Arfenic. Copper ores 
 alfo frequently participate of the nature of the py- 
 rjtes, containing a martial and an unmetallic earth, 
 both of which are entirely refractory, and hinder 
 the ore from melting. In this cafe you muft add 
 equal parts of a very fufile glafs, a little borax, 
 and four parts of the black flux, to facilitate the 
 fufion, The black flux is moreover necefTary to 
 furnifh the Copper with the Phlogifton it wants, or 
 reftore fo much thereof as it may lofe in melting. 
 For the fame reafon, when any ore, but that of 
 Gold or Silver, is to be fmelted, it is a general rule 
 to add fome black flux, or other matter abounding 
 with Phlogifton. 
 
 The
 
 PRACTICEC/'CHYMIsfRY. 349 
 
 The Regulus produced by this operation is not 
 malleable, becaufe it is not pure Copper, but a mix- 
 ture of Copper with all the other metallic fnbftances 
 that were in the ore ; except fuch as were feparated 
 from it by roafting, of which it contains but little. 
 
 According to the nature of the metallic matters 
 that remain combined with the Copper after this 
 fufion, the colour of the Regulus is either like that 
 of pure Copper, or a little more whitifh : it is alfo 
 frequently blackifh, which has procured it the name 
 of Black Copper. In this fhate, and even in general, 
 it is ufual enough to call this Regulus by the name 
 of Black Copper, when alloyed with other metallic 
 fubftances that render it unmalleable, whatever its 
 colour be. 
 
 Hence it appears that there may be feveral diffe- 
 rent forts of Black Copper. Iron, Lead, Tin, 
 Bifmuth, and the reguline part of Antimony, are 
 almoft always combined with the ores of Copper, 
 in a multitude of different proportions -, and all thefe 
 fubftances, being reduced by the black flux in the 
 operation, mix and precipitate with the Copper. If 
 the ore contain any Gold or Silver, as is pretty often 
 the cafe, thefe two metals alfo are confounded with 
 the reft in the precipitation, and become part of 
 the Black Copper, 
 
 Pyritofe, fulphureous, and arfenical Copper ores 
 may be fufed, in order to get rid of the groffer he- 
 terogeneous parts, without p re viou fly roafting them; 
 but in this cafe no alkaline flux muft be mixed 
 with the ore; becaufe the Alkali in combination 
 with the Sulphur would produce a Liver of Sul- 
 phur, and fo diffolve the metalline part ; by which 
 means all would be confounded together, and na 
 Regulus, or very little, be precipitated. On this 
 occafion therefore nothing muft be added to pro- 
 mote the fufion, but fome tender fufile glafs, toge- 
 ther with a fmall quantity of borax. 
 
 This
 
 350 ELEMENTS of the 
 
 This firft fufion may alfo be performed amidd 
 the coals, by cafting the ore upon them in the fur- 
 nace, without ufmg a crucible ; and then an earthen 
 velTel, thoroughly heated, or even made red-hot* 
 muft be placed under the grate of the fire-place* 
 to receive the metal as it runs from the ore. 
 
 The Regulus obtained by this means is much 
 more impure and brittle than Black Copper, becauie 
 k contains moreover a large quantity of Sulphur 
 and Arfenic , as thefe volatile fubilances have not 
 time to evaporate during the Ihort fpace requifite 
 to melt the ore, and as they cannot be carried oft" 
 by the aftion of the fire after the ore is once melt- 
 ed, whatever time be allowed for that purpofe. 
 However, fome part thereof is diflipated ; and the 
 Iron which is in pyritofe ores, having; a much 
 greater affinity than Copper, and indeed than any 
 other metallic fubftance, with Sulphur and Arfenic, 
 abibrbs another part thereof, and feparates it from 
 the Regulus. 
 
 This Regulus, it is plain, ftill contains all the 
 fame parts that were in the ore, but in different 
 proportions , there being more Copper, combined 
 with Ids Sulphur, Arfenic, and unmetallic earth, 
 v. hich have been either diffipated or turned to flag. 
 Therefore if you would make it like Black Copper, 
 you muft pound it, roaft it over and over, to free 
 it from its Sulphur and Arfenic, and then melt it 
 tvith the black flux. 
 
 If th'is Regulus contain much Iron, it will be 
 advifeable to melt it once or twice more, before all 
 the Sulphur and Arfenic are feparated from it by 
 roafting; for as the Iron, by uniting with thefe 
 volatile fbftanc'es, feparates th'-m from the Copper, 
 with which they have not fo great an affinity; fo 
 alfo the Sulphur and Arfenic, by uniting with the 
 Iron, help in their turn to feparate it from the 
 Copper. 
 
 PRO-
 
 PR ACTICE of CHVMISTRY. 351 
 
 PROCESS II. 
 
 70 purify Black Copper, and render it malleable. 
 
 BREAK into fmall bits the Black Copper you 
 intend to purify ; mix therewith a third part 
 in weight of granulated Lead, and put the whole 
 into a cupel fet under the muffle in a cupelling fur- 
 nace, and previoufly heated quite red. As foon as 
 the metals are in the cupel raife the fire confidera- 
 bly, making ufe, if it be needful, of a pair of per- 
 petual bellows, to melt the Copper fpeedily. When 
 it is thoroughly melted, lower the fire a little, and 
 continue it juft high enough to keep the metalline 
 mafs in perfect fufion. The melted matter will 
 then boil, and throw up fome/a>n>, which will 
 be abforbed by the cupel. 
 
 When moft of the Lead is confumed, raife the 
 fire again till the face of the Copper become bright 
 and mining, thereby {hewing that all its alloy is 
 feparated. As foon as your Copper comes to this 
 ftate, cover it with charcoal duft conveyed into- 
 the cupel with an iron ladle : then take the cupel 
 out of the furnace and let it cool. 
 
 OBSERVATIONS. 
 
 OF all the metals, next to Gold and Silver, Cop- 
 per bears fufion the longeft without lofmg its phlo- 
 gifton , and on this property is founded the procefs- 
 here delivered for purifying it. 
 . It is neceffary the Copper Ihould melt as foon as 
 it is in the cupel, becauie its nature is to calcine 
 much more eafily and much fooner, when it is only 
 fed-hot, than when it is in fufion. For this reafon 
 the fire is to be confiderably raifed,. immediately on 
 putting the Copper under the muffle, that it may melt 
 
 as
 
 352 ELEMENTS of tie 
 
 as foon as pofiible. Yet too violent a degree of fire 
 muft not be applied to it : for when it is expofed K* 
 fuch a degree of heat only as is but juft nccefiary to 
 keep it in fufion, it is then in the moft favourable 
 condition for lofing as little as may be of its phlo- 
 gifton j and if the heat be ftronger, a greater quan- 
 tity thereof will be calcined. As loon therefore as 
 it flows it is proper to weaken the fire, and reduce it 
 to the degree juft requifite to keep up the fufion. 
 
 The Lead added on this occafion is intended to 
 facilitate and expedite the fcorification of the metal- 
 lic fubftances combined with the Copper. So that 
 the event is here nearly the fame as when Gold or 
 Silver is refined on the cupel. The only difference 
 between this refining of Copper, and that of the 
 perfect metals, is that the latter, as hath been (hewn, 
 ablblutely refift the force of fire and the action of 
 Lead, without fuftering the lead alteration , where- 
 as a good deal of Copper is calcined and deftroyed, 
 when it is purified in this manner on the cupel. 
 Indeed it would be wholly deftroyed, if a greater 
 quantity of Lead were added, or if it were left too 
 long in the furnace. It is with a view to fave as 
 much of it as poflible that we order it to be covered 
 with charcoal-duft as foon as the fcorification is 
 finifhed. 
 
 The Lead ferves moreover to free the Copper ex- 
 peditioufly from the Iron with which it may be al- 
 loyed. Iron and Lead are incapable of contracting 
 any union together : fo that as fail as the Lead unites 
 with the Copper, itfcparates the Iron, and excludes 
 it out of the mixture. For the fame reafon if Iron 
 were combined in a large proportion with Copper, 
 it would prevent the Lead from entering into the 
 compofition. Now, as it is neceflary to give the 
 more heat, and to keep the Copper to be incorpo- 
 rated with Lead the longer in fuiion, as that Cop- 
 per is alloyed with a greater proportion of Iron, 
 
 fome
 
 PRACTICE ^CHYMISTRY. 353 
 
 fome black flux mull be added on this occafion, to 
 prevenc the Copper and the Lead from being cal- 
 cined before their afibciarion can be effected. 
 
 Copper purified in the manner here directed is 
 beautiful and malleable. It is now alloyed with no 
 other metalline fubftance but Gold or Silver, if 
 there were any in the mixed mafs. If you defire 
 to extract this Gold or Silver, recourfe mud be 
 had to the operation of the cupel. The procefs 
 here given for purifying Copper is not ufed in large 
 works, becaufe it would be much too chargeable. 
 In order to purify their Black Copper, and render 
 it malleable, the fmelters content thetnfelves with 
 roafting it, and melting it repeatedly, that the me- 
 tallic fubftances, which are not fo fixed as copper, 
 may be diflipated by fublimation, and the reft fco- 
 rified by fufion. 
 
 PROCESS III. 
 
 'To deprive Copper of its Phlogifton by calcination. 
 
 PUT your Copper in filings into a teft, and 
 fet it under the muffle of a cupelling furnace; 
 light the fire, and keep up fuch a degree of heat as 
 may make the whole quire red, but not enough to 
 melt the Copper. The furface of the Copper will 
 gradually lole its metalline fplendour, and put on 
 the appearance of a reddifh earth. From time to 
 time tiir the filings with a little rod of copper or 
 iron, and leave your metal expofed to the fame de- 
 gree of fire till it be entirely calcined. 
 
 OBSERVATIONS. 
 
 IN our obfervations on the preceding procefs we 
 took notice that Copper, in fufion, calcines more 
 (lowly, and lefs eafily, than when it is expofed to 
 a degree of fire barely fuffident to keep it red-hot, 
 
 VOL. I. A a without
 
 354 E L E M E N T s 0/* the 
 
 without melting it ; and therefore, the defign here 
 being to calcine it, we have directed that degree of 
 heat only to be applied. 
 
 The cupelling furnace is the fitted for this ope- 
 ration, bccaule the muffle is capable of receiving 
 fuch a flat vclTel as ought to be ufed on this occa- 
 fion, and comrmimcafimj to it a great deal of heat ; 
 while, at the lame time, it prevents the falling in 
 of any coals, which, by furnifhing the Copper 
 with frefh phlogifton, would greatly prejudice and 
 protract the operation. 
 
 As Copper calcines with great difficulty, this 
 operation is extremely tedious : nay, though Cop- 
 per hath flood thus expoied to the fire for ieveral 
 days and nights, and feems perfectly calcined, yet 
 it frequently haj pens that, when you try afterwards 
 to melt it, forr.c of it relumes the form of Copper : 
 a proof that all the Copper had not loft its phlo- 
 gifton. Copper is much more expeditioufly de- 
 prived of its phlo^itfon by calcining it in a crucible 
 with Nitre. 
 
 The calx of Copper perfectly calcined is with 
 great difficulty brought to fufion : yet, in the focus 
 of a large burning-glais, it melts and turns to a red- 
 dim and almoft opaque glafs. 
 
 By the procefs here delivered, you may likcwife 
 calcine all orlur metalline fubftartces, which do not 
 melt till they be thoroughly red-hot. As to thofe 
 which melt before they grow red, they are eafily 
 enough calcined^ even while they r.re in fufion. 
 
 PRO-
 
 PRACTICE of CHYMISTRY. 355 
 
 PROCESS IV. 
 
 . / > 
 
 To refufciate the Calx of Copper, mid reduce it te 
 Copper^ by reftoring its Phlogifton. 
 
 MIX the Calx of Copper with thrice as much 
 of the black flux ; put the mixture into a 
 good crucible, fo as to fill two thirds thereof, and 
 over it put a layer of Sea-falt a finger thick. Cover 
 the crucible, and fet it in a melting furnace; heat 
 it gradually, and keep it moderately red till the 
 decrepitation of the Sea-falt be over. Then raife 
 the fire confiderably by means of a good pair of per- 
 petual bellows , fatisfy yourfelf that the matter is in 
 perfect fufion, by dipping into the crucible an iron 
 wire ; continue the fire in this degree for half a quar- 
 terofanhour. When thecrucibleiscold, you will find 
 at its bottom a button of very fine Copper, which 
 will eafily feparate from the faline fcoria at top. 
 
 OBSERVATIONS. 
 
 WHAT hath been faid before on the fmelting of 
 Copper ores may be applied to this procefs, as being 
 the very fame. The observations there added mould 
 therefore be confuited on this occafion. 
 
 PROCESS V. 
 
 To di/ofae Copper in the Mineral Acids. 
 
 ON a fand-bath, in a' very gentle heat, fet a 
 a matra Is containing fome Copper filings; pour 
 on them twice their weight of Oil of Vitriol. That 
 Acid will preiently attack the Copper. Vapours 
 will rife, and iflue out of the neck of the matrafs* 
 A vaft number of bubbles will afcend from the fur- 
 A a a face
 
 356 ELEMENTS of the 
 
 face of the metal to the top of the liquor, and the 
 liquor will acquire a beautiful blue colour. When 
 the Copper is difiblved, put in a little and a little 
 more, till you .perceive the Acid no longer acts 
 upon ir. Then decant the liquor, and let it ttand 
 quiet in a cool place. In a fhort time great num- 
 bers of beautiful blue cryftals will moot in it. 
 Thefe cryftals are called Vitriol of Copper^ or Blue 
 Vitriol. They diflblve eafily in Water. 
 
 OBSERVAT 10 NS. 
 
 THE Vitrioliq Acid perfectly diflblves Copper,, 
 which is allb foluble in all the Acids, and even in 
 many other menftruums. 
 
 This Acid may be feparated from the Copper 
 which it hath difiblved by cliftillation only : but the 
 operation requires a fire of the utmoit violence. 
 The Copper remaining after it mutt be filled with 
 the black flux, to make it appear in its natural 
 form ; not only becaufe it ttill retains a portion of 
 the Acid, but alfo becaufe it hath loft part of its 
 phlogifton by being difiblved therein. The black 
 flux is very well adapted both to abforb the Acid 
 that remains united with the Copper, and to reftore 
 the phlogifton which the metal hath loft. 
 
 The mod ufual method of feparating Copper 
 from the Vitriolic Acid is by prefenting to that 
 Acid a metal with which it hath a greater affinity 
 than with Copper. Iron being fo qualified is con- 
 ffquently very fit to bring about this fcparation. 
 When therefore plates of Iron well cleaned are laid 
 in a folution of Blue Vitriol, the Acid foon begins 
 to act upon them, and by degrees, as it diffblves 
 them, depofites on their furfaces a quantity of Cop- 
 per in proportion to the quantity of Iron it takes 
 up. The Copper thus precipitated hath the appear- 
 ance of fmall leaves or fcales, exceeding thin, and 
 of a beautiful copper-colour. Care mutt be taken 
 5 to
 
 PR ACTICE of CHYMISTRY. 357 
 
 to fhake the Iron-plates now and then, to make the 
 Icales of Copper fall off, which will otherwiie cover 
 them entirely, hinder the Vitriolic Acid from at- 
 tacking the Iron, and fo put a (top to the precipi- 
 tation of the remaining Copper. 
 
 When thefe fcales of Copper ceafe to fettle on 
 the clean Iron-plates, you may be fure all the Cop- 
 per that was in the liquor is precipitated, and that 
 this liquor, which was a folution of Copper before 
 the precipitation, is a folution of Iron after it. So 
 that here two operations are performed at one and 
 the fame time ; to wit, the precipitation of the 
 Copper, and the diffolution of the Iron. 
 
 The Copper thus precipitated requires only to be 
 feparated from the liquor by filtration, and melted 
 with a little black flux, to become very fine mal- 
 leable Copper. 
 
 The Copper may alfo be precipitated out of a fo- 
 lution of Blue Vitriol by the interpofition of a Fixed 
 Alkali. This precipitate is of a greenifli blue co- 
 lour, and requires a much greater quantity of the 
 black flux to reduce it. 
 
 Copper diflblves in the Nitrous Acid, in the Ma- 
 rine Acid, and in Aqua Regis \ from all of which it 
 may be feparated by the lame methods as are here 
 ordered with regard to the Vitriolic Acid. 
 
 A a 3 CHAP.
 
 358 
 
 CHAP. IV. 
 
 Of IRON. 
 
 PROCESS I, 
 ?o feparate Iron from its Ore. 
 
 POUND into a coarle powder the martial 
 ftones or earths out of which you defign to ex- 
 tra/51 tKe Iron : roaft this powder in a teft under the 
 muffle for fome minutes, and let your fire be brifk. 
 Then let it cool, beat it very fine, and roaft it a 
 fecond time, keeping it under the muffle till k emit 
 no more fmell. 
 
 Then mix with this powder a flux compofed 
 of three parts of Nitre fixed with Tartar, one part 
 of fufile glafs, and half a part of Borax and char- 
 coal-duft. The dofe of this reducing flux muft be 
 thrice the weight of the ore. 
 
 Put this mixture into a good crucible , cover it 
 with about half a finger thick of Sea-falt ; over the 
 crucible put its cover, and lute it on with Windfor- 
 loam made into a pafte with water. Having thus 
 prepared your crucible, fet it in a melting furnace, 
 which you muft fill up with charcoal. Light the 
 fire, and let it kindle by gentle degrees, till the 
 crucible become red-hot. When the decrepitation 
 of the Sea-falt is over, raife your fire to the higheft 
 by the blaft of a pair of perpetual bellows, or rather 
 feveral. Keep up this imenfe degree of heat for 
 three quarters of an hour, or an whole hour, tak- 
 ing care that during all thjs time the furnace be 
 
 kept
 
 PRACTICE O/'CHYMISTRY. 
 
 keptconftantly filling up with frefh coals as the for- 
 mer confume. Then take your crucible out of 
 the furnace; ftrike the pavement on which you fet 
 it feveral times with a hammer, and let it ftand to 
 cool : break it, and you will find therein a Regulus 
 of Iron covered with (lag. 
 
 OBSERVATIONS. 
 
 IRON ore, like all others, requires roafting, to 
 feparate from it, as much as pofilble, the volatile 
 minerals, Sulphur and Arfcnic, which being mixed 
 with the Iron would render it unmalleable. Indeed 
 it is fo much the more neceflary to roaft thefe 
 ores, as Iron is, of all metallic fubflances, that which 
 has the greateft affinity with thofe volatile minerals; 
 on which account no metallic fubliance whatever 
 is capable of feparating it from them by fu-fkm and 
 precipitation. 
 
 Fixed Alkalis, it is true, have a greater affinity 
 than Iron with Sulphur ; but thrn the compolinon 
 which a Fixed Alkali forms with Sulphur is capable 
 of difiblving all metals. Coniequently, if you do 
 not diffipate the Sulphur by roaiting, but attempt 
 to feparate it from the Iron by melting the ore with 
 a Fixed Alkali, the Liver of Sulphur formed in the 
 operation will diflblve the martial part; fo that af- 
 ter the fufion you will find little or no Regulus. 
 
 All Iron ores in general are rcfradory, andlefs fu- 
 fible than any other; for which reafon a much 
 greater proportion of flux, and a much more violent 
 degree of fire, is required to fmelt them. One prin- 
 cipal caufe why thefe ores are fo refractory is the 
 property which Iron itfelf has of being extremely 
 difficult to fule, and of refilling the aftion of the 
 fire fo much the more as it is purer, and further 
 removed from its mineral ftate. Among all the 
 metallic fubftances it is the only one that is 
 leis fufible when combined with that portion qf 
 
 A a 4 phlo-
 
 360 ELEMENTS of tie 
 
 phlogifton which gives it the metalline form, than 
 when it is deprived thereof, and in the form of a 
 calx. 
 
 In fmeltin^-houfes Iron ore is fufed amidft char- 
 coal, the phlogitton of which combines with the 
 martial earth, and pives it the metalline form. 
 The Iron thus melted runs down to the bottom of 
 the furnace, from whence it is let out into large 
 moulds, in which it takes the fhape of oblong 
 blocks, called Pigs of Iron. This Iron is ftill v.ry 
 impure, and quite unmalleablc. Its want of ducti- 
 lity after the firft melting arifes partly from hence, 
 that, notwithstanding the previous roafting which 
 the ore underwent, there (till remains, after this 
 Jirit fufion, a confiderable quantity of Sulphur or 
 Arfenic combined with the metal. 
 
 A certain quantity of quick-lime, or of ftones 
 that will burn to lime, is frequently mix- J 
 Iron ore on putting it into the fmeiting furnace. 
 The lime being an abibrbent earth, very apt ro 
 unite with Sulphur and Arfenic, is of uic to le- 
 parate thole minerals from the Iron. 
 
 It is alfo of ufe to mix fome iVh matters with 
 the ore, when the ftones or eartii^ which naturally 
 accompany it are very fuiible ; for, as the Iron is 
 of difficult fufion, it may happen that the earthy 
 matters mixed with the Iron mall melt as eafily as 
 the metal, or perhaps more eafily. In fuch a cafe 
 there is no feparation of the earthy from the metal- 
 line part, both of which melt and precipitate toge- 
 ther promifcuoufly : now quick-lime, being ex- 
 tremely refractory, ferves on this occafion to check 
 the melting of thofe matters which are too fufible. 
 
 Yet quick-lime, notwithftanding its refractory 
 quality, may fometimes be of uie as a flux forlron. 
 This is the cafe when the ore happens to be combined 
 with fubftances which, being united with lime, ren- 
 der it fufible : fuch are all arfenical matters, and even 
 
 fome
 
 PR ACTIC E of CH YMISTR Y. 361 
 
 ibme earthy matters, which being combined with 
 quick-lime make a fufible compound. 
 
 When the ore of an Iron Mine is found difficult 
 to reduce, it is ufually neglected even though it be 
 rich -, becaufe Iron being very common, people 
 chufe to work thofe mines only whofe ores arc 
 fmelted with the mod eafe, and require the leaft 
 confumption of wood. 
 
 Yet refractory ores are not to be altogether re- 
 jected, when another Iron ore of a different quality 
 is found near them. For it often happens that two 
 feveral Iron ores, which being worked feparately 
 are very difficult to manage, and yield at lafb but 
 bad metal, become very tractable, and yield ex- 
 cellent Iron, when fmelted together : and accord- 
 ingly fuch mixtures are often made at Iron-works. 
 
 The Iron obtained from ores by the firft fufion 
 may be divided into two forts. The one, when 
 cold, refilts the hammer, doth not eafily break, 
 and is in fome meafure extenlible on the anvil; but 
 if ft ruck with a hammer when red-hot flies into 
 many pieces : this fort of Iron hath always a mix- 
 ture of Sulphur in it. The other fort on the con- 
 trary, is brittle when cold, but fomewhat ductile 
 when red-hot. This iron is not fulphurated, is na- 
 turally of a good quality, and its brittlenefs arifes 
 from its metalline parts not being fufficiently com- 
 pacted together. 
 
 Iron abounds fo much, and is founiverfally dif- 
 fufed through the earth, that it is difficult to find 
 a body in which there is none at all : and this hath 
 led feveral Chymifts, even men of great fame, 
 into the error of thinking that they had tranfmitted 
 into Iron feveral forts of earths in which they fuf- 
 pected no Iron, by combining them with an inflam- 
 mable matter-, whereas, in fact, all they did was to 
 give the metalline form to a true martial earth which 
 happened to be mixed with other earths. 
 
 PRO-
 
 362 ELEMENTS 
 
 PROCESS II. 
 
 To render Pig-iron and brittle Iron malleable. 
 
 INTO an earthen veffel widening upwards put 
 fome charcoal-duft, and thereon lay the Pig- 
 iron which you propofe to render duftile; cover it 
 all over with a quantity of charcoal-, excite the fire 
 violently with a pair, or more, of perpetual bellows 
 till the Iron melt. If it do not readily flow and 
 form a great deal of flag on its furface, add fome 
 tiux, fuch as a very fufible fand. 
 
 \Yhen the matter is in fufion keep (lirring it from 
 time to time, that all the parts thereof may be 
 equally acted on by the air and the fire. On the 
 furface of the melted Iron fccri<e will be formed, 
 which muft be taken off as they appear. At the 
 fame time you will iec a great many fparkles darted 
 up from the furface of the metal, which will form 
 a fort of fiery fhower. By degrees, as the Iron 
 grows purer, the number of thefe fparkles dimi- 
 nifhes, though they never vanifh entirely. When 
 but few fparkles appear, remove the coals which 
 cover the Iron, and let the flag run out of the vef- 
 Jel ; whereupon the metal will grow folid in a mo- 
 ment. Take it out while it is ftill red-hot, and 
 give it a few ftrokes with a hammer, to try if it be 
 ductile. If it be not yet malleable, repeat the ope- 
 ration a fecond time, in the fame manner as before. 
 Laftly,whenit is thus fufficiently purified by the fire, 
 work it for a long time on the anvil, extending ic 
 different ways, and making it red-hot as often as 
 there is occafion. Iron thus brought to the necef- 
 fary degree of ductility, fo as to yield to the ham- 
 mer, and fuffer itfelf to be extended every way, 
 either hot or cold, without breaking to bits, or 
 even cracking in the lead,. is very good and very 
 
 pure.
 
 PRACTICE of CH YMISTR Y. 363 
 
 pure. If it cannot be brought to this degree by 
 the method here prefcribed, ic is a proof that the 
 ore from which this Iron was extracted ought to be 
 mixed with other ores-, but it frequently requires 
 a great number of trials to obtain an exact know- 
 ledge of the quality and proportion of thofe other 
 ores with which it is to be mixed. 
 
 OBSERVATIONS. 
 
 THE brittlenefs and mortnefo of Pig-iron arifes 
 from the heterogeneous parts which it contains, and 
 which could not be feparated frtfm it by the firft fu- 
 fion. Thefe extraneous matters are ufually Sul- 
 phur, Arfenic, and unmetallic earth, and alfo a 
 ferruginous earth ; but fuch as could not be com- 
 bined with the phlogifton as it ought to be, in or- 
 der to have the properties of a metal, and muft 
 therefore be confidered as heterogeneous, with re- 
 fpecl to the other well-conditioned martial particles. 
 
 The Pig-iron, by undergoing repeated fufions, is 
 freed from thefe heterogeneous matters ; thole 
 which are volatile, fuch as Sulphur and Arfenic, 
 being diffipated, and the unmetallic matters being 
 fcorified. As to the ferruginous earth, which did 
 not at firft acquire the metalline form, it becomes 
 true Iron at laft j becaufe, among the coals with 
 which it is encompaffed, it meets with a fufficient 
 quantity of phlogifton to reduce it to metal. 
 Charcoal is alfo necefiary on this occafion, that it 
 may continually furnifli phlogifton to the Iron, 
 which would otherways be converted into a calx. 
 
 Hammering tine red-hot Iron, after each fufion, 
 ferves.to force out from amongft the martial parts 
 fuch earthy matters as may happen to remain there, 
 and fo to bring into cloier contact the metalline 
 parts which were feparated before by the interpo- 
 . fition of thofe heterogeneous matters. 
 
 PRO-
 
 364 ELEMENTS of tie 
 
 PROCESS III. 
 
 To convert Iron into Steel. 
 
 TAKE finall bars of the bed Iron-, that is, 
 of fuch as is malleable both hot and cold ; 
 fet them on their ends in a cylindrical earthen vef- 
 fel, whole depth is equal to the length of the bars, 
 and in fuch a manner that they may be an inch di- 
 ftant from each other, and from the fides of the cru- 
 cible. Fill the veflel with a cement compounded 
 of two parts of charcoal, one part of bones burnt 
 in a clofe veflel till they become very black, and 
 one half part of the afhes of green wood ; having 
 firft pulverifed and thoroughly mixed the whole 
 together. Take care to lift up the Iron bars a lit- 
 tle, to the end that the cement may cover the bot- 
 tom of the veflel, and lo that there be about the 
 depth of half an inch thereof under every bar : co- 
 ver the crucible and lute on the cover. 
 
 Set the crucible thus prepared in a furnace, fo 
 contrived that the crucible may be furrounded with 
 coals from top to bottom : for eight or ten hours 
 keep up Inch a degree of fire that the veflel may be 
 moderately red ; after this take it out of the fur- 
 nace , plunge your little Iron bars into cold water, 
 and you will find them converted into Steel. 
 
 OBSERVATIONS. 
 
 The principal difference between Iron and Steel 
 confifts in this, that the latter is combined with a 
 greater quantity of phlogiflon than the former. 
 
 It appears by this experiment that, to make 
 Iron unite with an inflammable matter, it is not ne- 
 
 cefiary
 
 PR ACTICE ^CHYMISTR Y. 365 
 
 cefTary it fhould be in fufion , it is fufficient that 
 it be fo red-hot as to be opened and foftened by 
 the fire. 
 
 Every kind of charcoal is fit to be an ingredient 
 in the compofition of the cement employed to make 
 Steel, provided it contain no vitriolic Acid. How- 
 ever, it hath been obferved that animal coals pro- 
 duce a fpeedier effect than others : for which rea- 
 fon it is proper to mix fomething of that kind with 
 charcoal-duft, as above directed. 
 
 The following figns fhew that the operation 
 hath fucceeded, and that the Iron is changed into 
 good Steel. 
 
 This metal being quenched in cold water, as pro^- 
 pofed above, acquires fuch an extraordinary degree 
 of hardnefs, that it will by no means yield to any 
 impreflion of the file or hammer, and will fooner 
 break in pieces than ilretch upon the anvil. And 
 here it is proper to obferve, that the hardnefs of 
 Steel varies with the manner in which it is quenched. 
 The general rule is, chat the hotter the Steel is 
 when quenched, and the colder the water is in 
 which you quench it, the harder it becomes. It 
 may be deprived of the temper thus acquired, by 
 making it red-hot, and letting it cool (lowly ; for 
 it is thereby Ibftened, rendered malleable, and the 
 file will bite upon it. For this reafon the artifans 
 who work in Steel begin with unternpering it, that 
 .they may with more eafe fhape it into the tool they 
 intend to make. They afterwards new-temper the 
 tool when finiflied, and by this fecond temper the 
 Steel recovers the fame degree of hardnefs it had 
 acquired by the firft temper. 
 
 The colour of Steel is not fo white as that of 
 Iron, but darker, and the grains, facets, or fibres, 
 which appear on breaking it, are finer than thofe 
 obferved in Iron. 
 
 If
 
 366 E L E M E N T S of 
 
 If the bars of Iron thus cemented in order to 
 convert them into Steel be too thick, or nor kept 
 Jong enough in cementation, they will not be turned 
 into Steel throughout their whole thicknefs : their 
 Surfaces only will be Steel to a certain depth, and 
 the center will be mere iron-, becaufe the Phlo- 
 oifton will not have thoroughly penetrated them. 
 On breaking a bar of this fort, the difference in co- 
 lour and grain between die Steel and the Iron is 
 very vifible. 
 
 It is eafy to deprive Sted of the fuperabundant 
 quantity of Phlogillon which conftttutes it Steel, and 
 thereby reduce it to Iron. For this purpofe it need 
 only be kept red-hot fome time, obierving that no 
 matter approach it all the while that is capable of 
 refunding to it the Phlogifton which the fire carries 
 off. The lame end is ttill fooner obtained by ce- 
 menting it with meagre hungry matters, capable of 
 abibrbing the Phlogifton ; luch as bones calcined 
 to whitenels, and cretaceous earths. 
 
 Steel may allb be made by fufion ; or Pig iron 
 may be converted into Steel. For this purpofe the 
 lame method muft be employ ed as was above directed 
 for reducing Pig-iron into maJleable Iron-, with this 
 difference, that, as Steel requires more Phlogifton 
 than is neceffary to Iron, all the means muft be made 
 ufeof that arc capable of introducing into the Iron a 
 great deal of Phlogifton ; fuch as melting but a fmall 
 quantity of Iron at a time, and keeping it conftantly 
 cncompaffed with abundance of charcoal , re-iterat- 
 ing the fufions; taking care that the blaft of the 1 
 bellows directed along the furface of the metal do 
 not remove the coals that cover it, &c. And here 
 it muft be obfcrved, that there are fome forts of 
 Pig-iron which it is very difficult to convert into 
 Steel by this method, and that there are others 
 which fucceed very readily, and with fcarce any 
 trouble at all. The ores which yield the laft men- 
 
 tioned
 
 PRACTICE ^ CHYMISTR Y. 367 
 
 tioned fort of Pig-iron are called Steel Ores. Steel 
 made by this means miift be tempered in the fame 
 manner as that made by cementation *. 
 
 PROCESS IV. 
 
 *The Calcination of Iron. Sundry Saffrons of Mars. 
 
 TAKE filings of Iron, in what quantity you 
 pleafe; put them into a broad unglazed 
 earthen veiTel ; fet it under the muffle of a cupell- 
 ing furnace ; make it red-hot ; ftir the filings fre- 
 quently ; and keep up the fame degree of fire till 
 the Iron be wholly turned into a red powder. 
 
 OBSERVATIONS. 
 
 IRON eafily lofes its phlogifton by the action of 
 fire. The calx that remains after its calcination is 
 exceeding red ; which makes this be thought the 
 natural colour of the earth of that metal. It hath 
 accordingly been obferved that all the earths and 
 ftones, which either are naturally red, or acquire 
 that colour by calcination, are ferruginous. 
 
 The yellowifh red colour which every calx of 
 Iron hath, in whatever manner it be prepared, hath 
 procured the name of Crocus or Saffron to every 
 preparation of this kind. That made in the man- 
 ner above directed is called in Medicine Crecus 
 Martis aftringens. 
 
 The ruft produced on- the fnrface of Iron is a 
 fort of calx of Iron made by the way, of diJTolution. 
 
 * Mr. Reaumur hath obliged the publick with a treatife on 
 the means of converting Iron into Steel, in which he hath ex- 
 haufted the fubjeft. Such as defire the ampleft and mo ft ufefol 
 inflrudions, on that part of metal! urgy, would do well to con - 
 iult his Work. 
 
 The
 
 368 ELEMENTS of tbe 
 
 The moifture of the air adls upon the metal, dif- 
 folves it, and robs it of ibme of its Phlogifton. This 
 ruft is called in Medicine Crocus Martis dperitns ; 
 becaufe it is thought that the (aline parts, by means 
 whereof the humidity difiblves the Iron, remain 
 united with the metal after its diflblution, and give 
 it an aperitive virtue. The Apothecaries prepare 
 this fort of Saffron of Mars by expofing Iron filings 
 ro the dew, till they be turned entirely to riili. -, 
 which is then called Saffron of Mars by dew. 
 
 Another Saffron of Mars is allo prepared in a 
 much fhorter manner, by mixing filings of Iron 
 with pulverized Sulphur, and moiftening the mix- 
 ture, which after iome time ferments and grows 
 hot. It is then let on the fire-, the Sulphur burns 
 away, and the mafs is kept ilirring till it become a 
 red matter. This Saffron is nothing but Iron dif- 
 iolved by the Acid of Sulphur, which is known to 
 be of the fame nature with that of Vitriol \ and 
 confequently this Saffron of Mars is no way diffe- 
 rent from Vitriol calcined to rednefs. 
 
 PROCESS V. 
 
 Iron drffbhed by tbe mineral Acids. 
 
 PUT any mineral Acid whatever into a matrafs 
 with fome water; fet the matrafs on a fand- 
 bath gently heated j drop into the veflel fome filings 
 of Iron: the phenomena which ufually accompany 
 metalline diiTolutions will immediately appear. 
 Add more filings, till you obferve the Acid hath 
 loft all fenfjble action upon them : then remove 
 your matrafs from the fand-batli j you will find in 
 it a folution of Iron. 
 
 B S E R-
 
 PRACTICE of CHYMISTRV. 
 
 O E SERVANT ION S. 
 
 IRON is very eafily diflblved by all the Acids. If 
 iyou make life of the Vitriolic Acid, care muft be 
 taken to weaken it with water, in cafe it be concen- 
 trated ; becaufe the difiblution will fucceed the bet- 
 ter. The vapours that rife on this occafion are in- 
 Bammable ; and if a lighted paper be held to the 
 mouth of the matrafs, efpecially after keeping it 
 ftopt for fome time and making the whole gently * 
 the fulphureous vapours take fire with fuch rapidity 
 as to produce a confiderable explofion ; which is 
 fometimcs ftrong enough to burft the veffel into a 
 thoufand pieces. This folution hath a green colour, 
 and is in fact a fluid Green Vitriol, which wants 
 nothing but reft to make it {hoot into cryftals. 
 
 If you make ufe of the Nitrous Acid, yoli muft 
 ceafe adding more filings when the liquor, after 
 Handing ftill fome moments, becomes turbid ; for, 
 when this Acid is impregnated with iron to a cer- 
 tain degree, it lets fall fome of that which it had 
 diffolved, and becomes capable of taking up frefli 
 filings. Thus by conftantly adding new iupplies of 
 Iron, this Acid may be made to diffolve a mucfi 
 greater quantity thereof than is ncceffary to faturate 
 it entirely. This folution is of a ruffct colour, and 
 doth not cryftallize. 
 
 If the weather be not extremely cold, and the 
 Acids have a proper degree of ftrength, the fand- 
 bath is unnecefiary, as the diflblution will fucceed 
 very well without it. 
 
 Iron diflblved by Acids may be feparated there- 
 from, like all other metallic fubftances in the lame 
 circumftances, either by the action of fire, which car- 
 ries off the Acid and leaves the Martial earth, or by 
 the interpofuion of fubftances which have a greater 
 affinity than metallic fubftances have with Acids ; 
 that is, by Abforbent Earths and Alkaline Sales. By 
 
 VOL. I. B b what-
 
 3 70 ELEMENTS of the 
 
 whatever means you leparate Iron from an Acid fof- 
 venr, it conftantly appears, after the feparation, m 
 the form of a yellowifh red powder-, becaule it is 
 then deprived of moft of the phlogifton to which it 
 owed its metalline form : whence it is reafonable to 
 think that this is the proper colour of Martial Earth. 
 All thcfe precipitates of Iron are true Saffrons of 
 Mars, which, as well as thofc prepared by calcina- 
 tion, are fo much the further removed from the 
 nature of a metal, the more they are deprived of 
 their phlogiiton. Thence it comes that they are 
 more or lets foluble by Acrds, and more or lefs at- 
 tracted by the macnet : as no ferruginous earth, per- 
 fectly deprived of all inflammable matter, is at all 
 attracted by the magnet, or loluble by Acids. 
 
 CHAP. V. 
 
 0/TiM. 
 
 P R O C E S S I. 
 
 o extra ft 1'ln from its Ore. 
 
 BREAK your Tin ore into a coarfe powder, 
 and by wafhing carefully feparate from it all 
 the heterogeneous matters, and ores of a different 
 kind, that may be mixed therewith. Then dry ii, 
 and roall it in a itrong degree of fire, till no more 
 Arlenical vapour rile from it. When the ore is 
 roaftcd, reduce it to a fine powder, and mix it tho- 
 roughly with *wice its weight of the black flux well 
 dried, a fourth part of its weight of clean iron filings, 
 together with as much borax and pitch : put the 
 mixture into a crucible ; over all put Sea-falt to the 
 j thick-
 
 PR ACTICE of CHYMISTRY. 371 
 
 thicknefs of four fingers, and cover the crucible 
 clofe. 
 
 Set the crucible thus prepared in a melting fur- 
 nace : apply at firft a moderate and flow degree of 
 fire, till the flame of the pitch, which wilV efcape 
 through the joint of the cover, difappear entirely. 
 Then fuddenly raife your fire, and urge it wirh ra- 
 pidity to the degree neceflary for melting the whole 
 mixture. As foon as the whole is in fufiori take 
 the crucible out of the furnace, and feparate the 
 Regulus from the fcbria. 
 
 OBSERVATIONS. 
 
 ALL Tin ores contain a confiderable quantity of 
 Arfenic, and no Sulphur at all, or at mod very' 
 little Hence it comes that, though Tin be the 
 lighted of all metals, its ore is nevertheleis much 
 heavier than any other ; Arfenic being much heavier 
 than Sulphur, of which the ores of every other kind 
 always contain a pretty large proportion. This 
 ore is moreover very hard, and is not brought to a 
 fine powder with To much eafe as the reft. 
 
 Thefe properties of Tin ore furnifh us with the 
 means of feparating it ealily by lotion, not only 
 from earthy and ftony parts, but even from the other 
 ores which may be mixed with it. And this is of 
 the greater ad vantage on two accounts, viz. becaule 
 Tin cannot endure, without the deftruction of a 
 great part thereof, the degree of fire rreceffary to 
 icorify the refractory matters which accompany its 
 ore/, and again becaufe this metal unites fo eafily 
 with Iron and Copper, the ores of which are pretty 
 commonly blended with Tin ore, that, after the 
 reduction, it would be found adulterated with a 
 mixture of thefe two metals, if they were not fe- 
 parated from it before the fufion. 
 
 But fometimes the Iron- ore confounded with that 
 
 of Tin is very heavy, ami is not eafily pulverized ; 
 
 B b ? whence
 
 372 ELEMENTS of the 
 
 whence it comes to pafs that it cannot be icparated 
 therefrom by warning only. In that cafe the mag- 
 net muft be employed to feparate it, after the ore 
 hath been roafted. 
 
 Roafting is moreover necefiary for Tin ore, in 
 order to diflipate the Arlenic which volatilizes, cal- 
 cines, or deftroys one part of the Tin, and reduces 
 the reft to a mort, brittle fubftance, like a Semi- 
 metal. The ore is known to be fufficiently roafted 
 when no more fumes rife from it , when it has loft 
 the fmell of garlic -, and when it does not whiten a 
 clean plate of Iron held over it. 
 
 Tin being one of thofe metals which are moft 
 cafily calcined, it is neceflary in reducing its ore to 
 employ fuch matters as may furnifh it with phlo- 
 gifton. In order to defend it from the contact of 
 the air, which always accelerates the calcination of 
 metallic fubftances, the mixture is to be covered 
 with Sea-falt; and the addition of pitch helps to 
 increafe the quantity of phlogifton. 
 
 PROCESS II. 
 
 Tbs Calcination of Tin. 
 
 INTO an unglazed earthen dim put the quan- 
 tity of Tin you intend to calcine ; melt it, and 
 keep ftirring it from time to time. Its furface will 
 be covered with a greyifh white powder: continue 
 the calcination till all your Tin be converted into 
 fuch a powder, which is the Calx of Tin. 
 
 QESERVA* 10 NS. 
 
 THOUGH the calcination of metalline fubftances 
 is promoted by expofing them, in powder, or in file- 
 ings, to the action of fire, and by ordering it fo that 
 they may not melt, becaufe they prefent a much 
 fmaller furface when melted than when unmelted 5 
 i yet
 
 PRACTICE ^CHYMISTRY. 373 
 
 yet we have not directed this precaution to be ufed 
 in calcining Tin. The reafon is, this metal is fo 
 fufible that it cannot endure the degree of fire re- 
 quifite to deftroy its phlogifton without melting, 
 and of courfe, though Tin calcines eafilv, the ope- 
 ration is nevertheless tedious, becaufe the melted 
 metal prefents but a fmall furface to be acted on by 
 the fire and the air. This inconvenience may be 
 partly remedied, and the operation greatly expedit- 
 ed, by dividing the quantity of Tin to be calcined 
 into feveral fmall parcels, and expofing them to the 
 fire in feparate vellels, fo that they may not re-unite 
 when melted, and form one fingle mafs. 
 
 Leaf Tin caft on Nitre in actual fufion caufes it 
 to deflagrate and fulminate j and from this mixture 
 there riles a white vapour, which is converted into 
 flowers when it meets with any obftacle to impede 
 its flying off entirely. 
 
 Mr. Geoffrey, who went through a courfe of ex- 
 periments on Tin, an account whereof may be feen 
 in the Memoirs of the Academy of Sciences, found 
 that from the colour of the calx of that metal a 
 judgment may be formed of its degree of purity, 
 and nearly of the quantity and quality of the me- 
 tallic fubftances with which it is alloyed. The ex- 
 periments tried on this fubject by that eminent 
 Chymift are very curious. 
 
 He performed the calcination in a crucible, which 
 he heated to a cherry-red, and kept up the fame 
 degree of fire from the beginning to the end of the 
 operation. The calx which formed upon his metal, 
 in that degree of heat, appeared like fmall white 
 fcales, a little reddi(h on the under fide. He puflied 
 it to one fide as it formed, to the end that it might 
 not cover the furface of the metal, which, like all 
 others, requires the contact of the air to turn it in- 
 to a calx. 
 
 B b 3 " While
 
 374 ELEMENTS of the 
 
 44 \Vhile he was making thefe calcinations, he had 
 " an opportunity of oblerving a. curious fact, of 
 * 4 which nobody before him had ever taken notice; 
 " probably becaufe nobody had ever calcined Tin 
 " by the fame method. The fact is, that during 
 " the calcination of the Tin, whether you break the 
 44 pellicle which forms on the furface of the metal 
 " while in red-hot fulion, or whether you let it re- 
 " main without touching it, you perceive in feveral 
 44 places a fmallfwell of a certain matter,whichburfts 
 4 - and makes its way through the pellicle. This 
 41 matter puffs up, grows red, at the ia;r.e inftant 
 44 takes fire, and darts out a fmail whitifh flame, 
 44 as vivid and as brilliant as that of Zinc, when 
 44 urged by a fire ftrong enough to fublime it into 
 41 flowers. The vivednefs of this flame may be fur- 
 " ther compared to that of feveral fmall grains of 
 " phofphorus of urine fired and gently dropped on 
 44 boiling water. From this bright flame a white 
 44 vapour exhales-, after which the fwelled mafs 
 " partly crumbles down, and turns to a light white 
 44 powder, fomctimes ipottcd with red, according 
 44 to the force of the fire. After this momentary 
 44 ignition, there arife ftionger, more numerous, or 
 44 more frequent heavings of matter, out of which 
 4C iffues a good deal of white fume, that may be in- 
 44 tercepted by a cover of tin-plate or copper fitted 
 4i to the crucible, and appears to be the flowers of 
 44 Tin, which in fome meafure corrode thefe metals. 
 44 Hence Mr. Gcofifroy conjecl:ures,with a great deal 
 44 of probability, that their lublimation is promoted 
 14 by a portion of Arfenic. When the cruil formed 
 14 by this calx comes to be too thick, or in too great 
 14 a quantity, to be puflied on one fide, fo as to leave 
 44 part of the metal uncovered, Mr. GeofFroy puts 
 44 out the fire, becaufe no more calx would be fornv 
 " ed; the communication of the external air with 
 " the Tin in fufion being abfolutely neceflary there- 
 
 44 to.
 
 PR AC TIC E of CH YMISTR Y. 375 
 
 4t to, as hath been already faid. In this operation 
 " it is to be obferved that, if the fire be too flow, 
 " neither the inflammation of the fulphureons par- 
 " tides, nor the white fumes that rile, will be fo 
 " diftinftly perceived, as when the fire is of the 
 " degree requifite to keep the crucible juft of a 
 " cherry-red heat. 
 
 " Mr. Geoffroy having taken off this firft calx 
 " began the calcination anew. In this fecond hear 
 *' the buddings or heavings were more confiderable, 
 ** and (hot up in the form of cauli-flowers; but were 
 " dill compofed of little icales. The thoroughly cal- 
 -" cined portion of this vegetation waslikewiie white 
 " and red ; and the inferiour furfaces of fome little 
 fi bits thereof were wholly red. When thefe calci- 
 " nations are continued, fulphureous vapours rile 
 " feemingly of another kind than thofe which ap- 
 " peared in the beginning , for all the calx made 
 " by the firft heat was perfectly white ; whereas in 
 " the lecond it begins to be fpotted here and there 
 ^ with a tinge of black. Mr. Geoffroy was obliged 
 " to go through a courfe of twelve feveral calcina- 
 *' tions before he could convert two ounces of Tin 
 *' into a calx. He had the opportunity, during 
 " thefe feveral calcinations, to obierve that after 
 P the fourth, and ibmetimes after the third, the 
 u red fpots of the calx decreafe, and the black in- 
 ?* creafe-, that the germinations ceafe-, that the crult 
 * c of the calx remains flat ; that in the twelfth fire 
 " the Tin yields no more of this fcaly cruft -, that 
 " towards the end the undulations of the fufed 
 *' metal appear no longer -, and that the fmall re- 
 ?' mainder of calx is mixed with feveral very minute 
 " grains of metal, which feem much harder than 
 *' Tin. Mr. Geoffroy could not collect a fufficient 
 " quantity thereof to cupel them, and fatisfy him- 
 " fclf whether or no they were Silver." 
 
 B b 4 Though
 
 376 ELEMENTS of the 
 
 Though Tin, and all the imperfect metals in ge- 
 neral, feem converted to a calx, and lofe the me- 
 talline form, by one (ingle calcination, and that a 
 flight one , yet they are not wholly deprived of their 
 phlogiilon : for if the calx of Tin, for inftance, pre- 
 pared according to the procefs above delivered, be 
 caft upon Nitre in fufi^n, it will make that fart 
 deflragrare very perceptibly-, a convincing proof 
 that it ftiil contains much inflammable matter. If 
 therefore a calx be required abfolutely free from 
 phlogifton, this firft calx muff be rc-calcincd by a 
 more violent fire, and the calcination continued till 
 all the phlogifton be diifipated. 
 
 " Mr. GeofFroy, being defirous of having his calx 
 " of Tin very pure and perfectly calcined, expofed 
 " once more to the action of lire the twelve portions 
 " of calx obtained by his former calcinations. But, 
 " as it would have been too tedious to re-calcine 
 " them all leparately, he made four parcels of the 
 " whole, each confuting of three taken according to 
 " the order in which they were firlt calcined ; and 
 " gave to each a fire fufficiently ftrong, and long 
 " enough continued, to calcine them as thoroughly 
 '' as was pofiible. After this fecond calcination he 
 *' found them all of a mod beautiful white, except 
 * c the firft parcel : as that confifted of the portions 
 " obtained by the three firft heats, in all of which 
 " there were fcales tinged with red, it ftill retained 
 *' a ftain of carnation, though hardly perceptible. 
 " Agreeably to the general rule, the two ounces of 
 " Tin gained in weight by being thus calcined , and 
 *' the increafe was two drams and fifty-feven grains^ 
 " Mr. GeorTroy obferves that no Tin, but what 
 " is abiulutely pure, will yield a ptrfedtly white 
 " calx. He calcined in this manner feveral other 
 " parcels of Tin that were impure and varioufly al- 
 " loyed ; each of which produced a calx differently 
 *' coloured, according to the nature and quantity of 
 
 " its
 
 PRACTICE C/CHYMISTRY. 
 
 ?c its alloy : whence he julily concludes that calci-r 
 ** nation is a very good method of trying the fine- 
 *' nefs of Tin, or its degree of purity. " The par- 
 ticulars of Mr. Geoffrey's experiments on this fub- 
 jecl, which are very curious, may be ieen in the 
 Memoirs of the Academy for 1738. 
 
 It is proper to take notice that a man mould be 
 very cautious how he expofes himfelf to the vapours 
 of Tin, becaule they are dangerous -, this metal be- 
 ing very juftly fufpected by Chymifts of containing 
 fomething Arfenical. 
 
 PROCESS III. 
 
 diffblution of 'Tin ly Adds. 'The Smoking liquor 
 of Libavius. 
 
 PU T into a glafs veflel what quantity you pleafe 
 of fine Tin cut into little bits. Pour on it 
 thrice as much Aqua Regis, compounded of two 
 parts Aqua Fortis weakened with an equal quantity 
 of very pure water, and one part Spirit of Salt. A n 
 ebullition will arife, and the Tin will be very rapidly 
 difiblved ; efpecially if the quantities of metal and 
 of Aqua Regis be confiderable. 
 
 OBSERVATIONS. 
 
 TIN is foluble by all the Acids-, but Aqua Regis <\\t- 
 folves it beft of any. Yet in this diflblution it comts 
 .to pafs that part of the diflblved Tin precipitates of 
 its own accord to the bottom of the veflel, in the form 
 of a white powder. This folution of Tin is very 
 fit for preparing the purple-coloured precipitate of 
 Gold. For this purpofe the folution of Tin muft 
 be let fall, drop by drop, into a folution of Gold. 
 Spirit of Nitre difiblves Tin nearly as Aqua Regis 
 does 5 but it occafions a greater quantity of calx. 
 
 If
 
 378 ELEMENTS of the 
 
 If two or three- parts of Oil of Vitriol be poured 
 on one p.ut of Tin, and if the veflel in which the 
 mixture is made be expofed to fuch a degree of 
 heat as to evaporate all the moiilure, there will re- 
 main a tenacious matter (ticking to the fides of the 
 
 \^> 
 
 veffel. If water be poured on this matter, and it 
 be then expofcd a fecond time to the lire, it will 
 difiblve entirely, excepting a Imall portion of a 
 glutinous fubflance, which alib may be diiiblved 
 in frelh Oil of Vitriol. 
 
 The Acid of Sea- fait may be combined with Tin 
 by the following procefs. Mix perfectly, by tntu- 
 ration in a marble mortar, an amalgam of two 
 ounces of fine Tin, and two ounces and a half of 
 Quick-filver, with as much Corrofive Sublimate. 
 As foon as the mixture is completed, put it into a 
 glafs retort, and diftill with the fame precautions 
 as we directed to be ufed in preparing concentr.it- 
 rd and fmoking Acids. There will firft conic over 
 into the receiver fomc drops of a limpid liquor, 
 which will be foon followed by an elatlic fpirii 
 will iffue out with impetuolity. At lati fome Mow- 
 ers, and a falinc tenacious matter, will rite into the 
 neck of the retort. Then (lop your diitillation, and 
 pour into a glals bottle the liquor you will find in the 
 receiver. This liquor continually exhales aconfider- 
 able quantity of denle, white fumes, as long as it is 
 allowed to have a free communication with the air. 
 
 The product; of this diilillation is a combination of 
 the Acid of Sea-falt with Tin. As the affinity of 
 Tin with this Acid is greater than that of Mercury, 
 the Acid contained in the Corrofive Sublimate quits 
 the Mercury, wherewith it was united, to join the 
 Tin -, which it volatilizes fo as to make it rife with it- 
 lelf in a liquid form. We make ufe of the amal- 
 gam of Tin with Quick-filver, becaufe we are there- 
 by enabled to mix the Corrofive Sublimate perfectly 
 
 there-
 
 PR ACTICE of CHYMISTRY. 379 
 
 therewith, as the fuccefs -of the operation requires 
 it mould be. 
 
 In this experiment the Tin is volatilized, and the 
 Acid of Sea-falt, which is exceedingly concentrated, 
 flies off inceffantly in the form of white vapours. 
 This compound is known in Chymiftry by the name 
 of the Smoking Liquor of Libavius ; a name derived 
 from its quality, and from its Inventor. Tin dif- 
 folved by Acids is eafily leparated from them by 
 Alkalis. It always precipitates in the form of 
 a white calx. 
 
 CHAP. VI. 
 
 Of LEAD. 
 
 PROCESS I. 
 
 To extraft Lead from its Ore. 
 
 HAVING roafted your Lead ore reduce it to 
 a fine powder ; mix it with twice its weight 
 of the black flux, and one fourth of its weight of 
 clean iron filings and borax ; put the whole into a 
 crucible capable of containing at lead thrice as 
 much ; over all put Sea-falt four fingers thick , 
 cover the crucible ; lute the juncture : dry the whole 
 with a gentle heat, and fet it in a melting furnace. 
 
 Make the crucible moderately red : you will hear 
 the Sea-falt decrepitate, and after the decrepitation 
 a fmall hiding in the crucible. Keep up the fame 
 degree of fire till that be over. 
 
 Then throw in as many coals as are neceiTary tq 
 complete the operation entirely, and raife the fire 
 fuddenly, fo as to bring the whole mixture into per- 
 fect fufion. Keep up this degree of fire for a quar- 
 ter
 
 380 ELEMENTS of the 
 
 t-rr of -an hour, which is time lufficient for the 
 precipitation of the Regulus. 
 
 When the operation is finifhed, which may be 
 known by the quietneis of the matter in the cruci- 
 ble, and by a bright vivid flame that will rife from 
 ir, take the crucible out of the furnace, and iepa- 
 ratc the Regulus from the fcoria, 
 
 OBSERVATIONS. 
 
 ALL Lead ore contains a good deal of Sulphur, 
 which muft be firft feparated from it by roafting : 
 and as this kind of ore is apt to fly when firft expof- 
 ed to the fire, it is proper to keep it covered till it be 
 thoroughly heated. Another precaution to be 
 ufed, in roafting this ore, is not to give it too 
 great a heat, but to keep the vefTel which contains 
 it juft moderately red ; becaufe it eafily turns 
 tlammy, which cccafions it to (lick to the veflel. 
 
 The Iron that is added, and mixed with the flux, 
 abforbs the Sulphur which may happen to remain, 
 even after reading : it helps alfo to fcparate from the 
 Lead fome portions of lemi-metal, dpecially of An- 
 timony, which are frequently mixed with this ore. 
 
 There is no fear left the Iron mix with the Lead 
 in fufion, and adulterate it ; for thefe two metals are 
 incapable cf contracting any union together, when 
 each has its metalline form. 
 
 Nor is there any realbn to apprehend left the 
 Iron mould, by its refractory quality, obftruct the 
 fufion of the mixture ; for though this metal be 
 nc^t fufible when alone, yet, by the union it con- 
 tracts with the matters it is defigned to ablorb, it 
 becomes fo to fuch a degree as in fome meafure to 
 perform, on this occafion, the office of a flux. 
 
 The government of the fire is a point of great 
 confequence in this operation. It is neceflary to ap- 
 ply but a moderate degree of heat at firft : for, when 
 The metallic earth of the Lead, combining with the 
 
 phlogifton,
 
 PR ACT ICE of CHYMIStRY. 
 
 phlogifton, acquires the metalline form, it fwells up 
 in fuch an extraordinary manner, that there is great 
 danger left the matter mould overflow, and run all 
 out of the containing veflel. With a view there- 
 fore to avoid this inconvenience, we direct a very 
 large crucible t be ufed. This heaving of the 
 Lead, at the inftant of its reduction, is attended 
 with a noife like the whittling of wind. 
 
 Notwithftanding all the precautions that can bt 
 ufed to prevent the reduction from taking place too 
 haftily, and fo occafioning the effufion of the mat- 
 ter, it often happens that, on raifing the fire in 
 order to bring the mixture into.fufion, the hiding 
 fuddenly begins again, and is very loud. In thai 
 cafe all the apertures of the furnace muft immedi- 1 
 ately be {hut clofe, in order to choak and fuffocate 
 the fire : for, if this be neglected, the matter iri 
 the crucible will fwell up, make its way through 
 the luting of the juncture, nay, pum up the 
 cover, and run over. This accident is to be appre- 
 hended during the firft five or fix minutes after you 
 raife the fire in order to melt the mixture. This ef- 
 fufion of the matter is accompanied with a dull 
 flame, a thick, grey and yellow ftnoke, and a noife 
 like that of fome boiling liquor. When you obferve 
 thefe feveral phenomena you may be fure the mat- 
 ter is run out of the crucible, either in the manner 
 above defcribed, or by making its way through 
 fome cracks in the vefTel, and confequently that the 
 operation is fpoiled. 
 
 Moreover* this event infallibly follows whenever 
 a bit of coal happens to fall into, the crucible , and 
 this is one reafon why it is neceffary to cover it. 
 
 You may be certain that the operation hath fuc- 
 ceeded if the fcoria be fmooth when cold, and have 
 not in part efcaped throueh the lute-, if the Lead be 
 notdifperfed in globules through the whole mafs of 
 the matter contained in the crucible, but is, on the 
 
 contrary,
 
 382 ELEMENTS of tbe 
 
 contrary, collected at the bottom, in the form of 3 
 folid Regulus, not very ihining, but of a bluifh 
 caft, and ductile. Moreover the fcoria ought, in 
 the prelent caie, to be hard and black, and fhould 
 not appear full of holes like a fieve, except only in 
 that part which was contiguous to the Salt. 
 
 Here it is proper to oblerve that the Sea-fah 
 doth not mix with the fcoria, but floats upon it. 
 After the operation it is black ; which colour it 
 gets, no doubt, from the charred parts of the flux. 
 The ablence of thefe figns mews the operation to 
 have mifcarried. 
 
 "When the ore to be fmelted is pyritofr and refrac- 
 tory, it may be roafted at firft with a much (Ironger 
 degree of fire than is uied for ores that are fufible j 
 becaufe the martial earth, and the unmetallic earth, 
 which are always mixed in- pyritofe matters, hinder 
 it from growing readily foft in the fire. Befides, 
 fuch an ore requires a greater quantity of the black 
 flux and of borax to be mixed with it, and a higher 
 degree of fire to fufe it. 
 
 It is generally needlefs to mix iron filings with 
 this fort of ore ; becaufe the martial earth, with 
 which pyritofe matters are ahvays accompanied, is 
 reduced during the operation by the help of the 
 black flux, which for that purpofc is mixed with 
 it in a large proportion, and furnimes a quantity 
 of iron iufficient to ablbrb the heterogeneous mine- 
 rals mixed with the Lead. 
 
 Yet, if it fliould be obferved that the pyrites 
 which accompany the Lead ore are arfenical, then, 
 as fuch pyrites contain but a frnall quantity of fer- 
 ruginous earth, iron filings muft be added ; which 
 are, on this occafion, fo much the more neceflfary 
 for ablbrbing the Arfenic, as this mineral remains in 
 part confounded with the ore, is reduced to a Regu- 
 lus during the operation, unites with the Lead, and 
 
 deftroys
 
 PRACTICE O/CHYMISTRY. 383- 
 
 deftroys a great deal of it by procuring its vitrifi- 
 cation. 
 
 , The Lead obtained from fuch pyritofe ores is 
 commonly not very pure ; it is blackifh and fcarce 
 ductile ; qualities communicated to it by a fmall 
 mixture ot Copper in the pyrites, which always con- 
 tain more or lels thereof. We fhall prefently (hew 
 the method of feparating Lead from Copper. 
 
 Lead ore mayalfo be reduced by melting kamtdft 
 coals. For that purpole firft kindle a fire in the 
 furnace in which you intend to melt your ore ; then 
 put a layer of your ore immediately upon the lighted 
 coals, and cover it with another layer of coals. 
 
 Though the melting furnace ufed for this, opera- 
 tion be capable of giving a confiderable heat, yet it 
 is necefTary further to increafe the force of the fire 
 by the means of a good pair of perpetual bellows* 
 which will produce aneffecl: like that of a forge. The 
 ore melts, the earth of the Lead unites with the phlo- 
 gifton of the coals, and fois reduced to metal, which* 
 runs through the coals, and falls into an earthen vef-? 
 lei placed at the bottom of the furnace to receive it. 
 Care muft be taken to keep this veiTel well filled 
 with charcoal-duft, to the end that the Lead may be 
 in HO danger of calcination while it continues there; 
 the charcoal-duft conftantiy furnifhing it with phlo* 
 gifton to preferve its metalline form. 
 
 The earthy and ftony matters that accoYnpany the 
 ore are fcorified by this fufion, juft as they are by the 
 other which is performed in a clofe veflfel. With re- 
 gard to the Sulphur and Arfcnic, they are fuppofed 
 to have been firft accurately feparatcd from the ore 
 by roafting. This is the method commonly eta- 
 ployed for fmelting Lead ore at the works. 
 
 PRO-
 
 384 
 
 ELEMENTS 0" the 
 
 PROCESS II. 
 
 . To feparate Lead from Cvp-per. 
 
 WITH luting earth arid charcoal-duft make 
 a flat veflel, widening upwards, dnd large 
 enough to contain your metalline mafs. Set it (hel- 
 ving downwards from the back towards the fore- 
 part ; and in the fore-part, at the bottom, make a 
 little gutter communicating with another vefiel of 
 the fame nature, placed near the former and a little 
 lower. Let the mouth of the gutter within fide the 
 tipper veflel be narrowed, by means of a fmall iron 
 plate fixed acrofs it, while the loam is yet foft ; fo as 
 to leave a very fmall aperture, in thelowerpartofthis 
 canal, fufficient to difcharge the Lead as It melts. 
 Dry the whole by placing lighted coals around it. 
 
 When this apparatus is dry, put your mixed mafs 
 of Copper and Lead into the upper veflel : both in 
 that, and in the other vefiel, light a very gentle fire 
 of wood or charcoal, fo as not to exceed the degree 
 of heat necefiary to melt Lead. In fuch a degree of 
 heat the lead contained in the mixed mafs will melr, 
 and you will fee it run out of the upper veflel into 
 the lower-, at the bottom of which it will unite into 
 a Regulus. When in this degree of heat no more 
 Lead flows, increafe the fife a little, fo as to make 
 the veflel moderately red. 
 
 When no more will run, collccl the Lead con- 
 tained in the lower veflel. Melt it over again in an 
 iron ladle, with a degree of fire fuffitient to make 
 the ladle red -, throw into it a little tallow or pitch, 
 and while it burns keep ftirring the metal, in order 
 to reduce any part of it that may be calcined. Re- 
 move the pellicle or thin cruft which will form on the 
 furface-, iqueeze out all the Lead it contains, and 
 then put it to the mafs of Copper left in the upper 
 
 veflel.
 
 PRACTICE of CH YM i STR v. 385. 
 
 vefiel. Check the fire, and in the fame manner take 
 off a iecond fkin that will form on the furface of the 
 Lead. Laftly, when the metal is ready to fix, take 
 off" the fkin that will then- appear on it. The Lead 
 remaining after this will be very pure, and free 
 from all alloy of Copper. 
 
 With regard to the Copper itfelf, you will find it 
 in the upper vefTel covered with a thin coat of 
 Lead : and if the Lead mixed with it was in the 
 proportion of a fourth or a fifth part only, and the 
 fire applied was gentle and flow, it will retain 
 nearly the fame form after the operation that the 
 mixed ma Is had before. 
 
 OB S ERVAT ION S. 
 
 LEAD frequently remains mixed with Copper 
 after the reduction of its ore, efpecially if the ore was 
 pyritofe. Tho' Copper be a much more beautiful 
 and more duclile metal than Lead, yet the latter by 
 being alloyed with the former is rendered eager and 
 brittle. This bad quality is eafily difcovered by the 
 eye on breaking it : for the furface of the broken 
 part appears all granulated ; whereas when it is pure 
 it is more evenly, and refembles a congeries of Iblid 
 angles. If the Lead be alloyed with a confiderable 
 quantity of Copper, its colour hath a yellowifh caft. 
 
 Confidering the bad qualities which Copper com- 
 municates to Lead, it is neceflary to leparate thele 
 two metals from each other. The method above 
 laid down is the fimpleft and the bed. It is found- 
 ed on two properties belonging to Lead : the firft is 
 that of being much more fufible than Copper-, fo 
 that it will melt and run in a degree of heat that is 
 not capable of making the Copper even red-hot, 
 which yet is very far from being able to melt it: 
 the fecond is, that Lead, though it hath an affinity 
 with Copper, and unites very perfectly therewith, 
 yet is not able to diflblve it without a greater heat 
 
 VOL, I, C c than
 
 ELEMENTS of tie 
 
 than the degree barely necefiary tofufc Lead. Hence: 
 it comes that Lead may be melted in a Copper vcf- 
 fcl, provided no greater degree of heat be applied 
 than that purpofe requires. But when the Lead be- 
 comes ib hot as to be red, fume and boil, it in- 
 itantly begins to diffolve the Copper. For this rea- 
 ibn, it is eficntia! to the fuccefs of our operation that 
 a moderate degree of heat only be applied, and no 
 greater than is requifite to keep the Lead in fufion. 
 
 Charcoal-dull is made an ingredient in the com- 
 pofition of the veficls ufed on this occafion, in order 
 to prevent the calcination of the Lea 
 
 The iron plate, with which the entrance of the 
 gutter within the upper vefTel is narrowed, iervcs to 
 prevent the larger pieces of Copper, which the Lead 
 may carry along with it, from paffing through : it 
 ilops them, and allows the Lead to run off alone. 
 
 But as thele parcels of Copper may entirely choak 
 the pafiage, care muft be taken, when any happen 
 to be ilopt, to remove them from the entrance of the 
 gutter, and pufh them back into the middle of the 
 veflcl. It is allo ncceflary to obferve whether or no 
 the Lead fixes any where in the paffage , and, if it 
 does, the heat of that part muft be increaled, in or- 
 der to melt it and make it run off. 
 
 Notwithftanding all the precautions that can be 
 taken, to hinder the melted Lead from carrying off 
 any Copper with it, it is impofiible to prevent this 
 inconvenience entirely : and therefore the Lead is 
 melted over again, in order to ieparate the Imall por- 
 tion of Copper with which it is ftill adulterated. 
 
 As Copper is much lighter than Lead, if thefe 
 two metals happen to be ib blended together that 
 theCopper, without being in fufion and diflblved by 
 the Lead, is only interpoied between the parts of the 
 melted Lead, fo as to fwim therein, it is then pre- 
 cifely in the cafe of a folid body plunged into a 
 fluid heavier than itfelf, and muft rife to the furir.ce, 
 
 like
 
 P R A C T I C E of C H Y M I S t R Y. 387 
 
 like wood thrown into water. It is proper to burn 
 fbme inflammable matter on this melted Lead, in 
 order to reduce fuch parts thereof as are constantly 
 calcining on -its furface while it is in fufion ; for 
 without this precaution they would be taken off 
 together with the -Copper. 
 
 The Copper remaining after this feparation is, as 
 we took notice before, (till mixed with a little Lead. 
 If you defire to feparate it entirely therefrom, you 
 muft put it into a cupel, and expofe it under the 
 muffle to fuch a degree of fire as may convert all the 
 Lead into litharge. This cannot be ib done but that 
 iboieof the Copper alfo will be fcorified by the heat 
 of the fire, and by the action of the Lead : but as 
 there is a very great difference between the facility 
 and readinefs with which thefe two metals calcine^ 
 the portion of Copper that is calcined, while the 
 whole Lead is turning into litharge, is icarce worth 
 confidering. 
 
 The Lead, though carefully feparated from the 
 Copper by the procefs here delivered, is not yet ab- 
 iulutely pure : ibmetimes it is alloyed with Gold$ 
 and almoft always contains fome Silver. If you 
 would free the Lead as much as poflible from any 
 mixture of thefe two metals, you muft convert it 
 into glafs, feparate the remaining bead, and after- 
 wards reduce this glafs of Lead. But, as thefe two 
 perfect metals are of no prejudice to the Lead, it 
 is not ufual to leparate them from it, unlefs they be 
 in a fufficient proportion to defray the charge, and 
 produce fome profit beftdes. 
 
 When we examine by the cupel the juft propor- 
 tion of Gold and Silver that an ore or a mixed me- 
 talline mats will yield, we make a previous affayof 
 the Lead to be employed in the operation, and af- 
 terwards, in our elt innate, deduct a proper allow- 
 ance for the quantity of fine metal due to the Lead 
 made ufe of. 
 
 C c * PRO-
 
 ELEMENTS of tie 
 
 PROCESS III. 
 
 The Calcination of Lead. 
 
 TAKE what quantity of Lead you plcafe . 
 melt it in one or more unglazed earthen pans ; 
 a dark grey powder will be found on its furface. 
 Keep ftirring the metal incefTantly till it be wholly 
 converted into fuch a powder, which is the Calx cf 
 Lead. 
 
 OBSERVATIONS. 
 
 As Lead is a very fufible metal, and in that re- 
 fpeft greatly relembles Tin, mod of the oblerva- 
 tions we made on the calcination of Tin may be 
 applied here. 
 
 In the calcination of all metals, and particularly 
 in this of Lead, there appears a Angular phenome- 
 non which is not eafily accounted for. It is this : 
 though thefe matters lofe a great deal of their fiib- 
 ftance, either by the difiipation of their phlogifton, 
 or becaufe fbme of the metal, perhaps, exhales ir> 
 vapours, yet when the calcination is overtheir calxes 
 ire found to be increafed in Weight, and this increafe 
 is very confiderable. An hundred pounds of Lead, 
 for example, converted into Minium, which is no- 
 thing bilt a calk of Lead brought to a red colour 
 by continuing the calcination, are found to gain ten 
 pounds weight ; fo that for an hundred pounds of 
 Lead we have one hundred and ten pounds of Mi- 
 nium: a prodigious and almoft incredible augmen- 
 tation, if it be confldered that, far from adding any 
 thing to the Lead, we have on the contrary difll- 
 pated part of it. 
 
 To account for this phenomenon Natural Philofo- 
 phers and Chymifts have invented feveral ingenious 
 hypothefes, but none of them entirely fatisfaftory. 
 
 As
 
 PRACTICE O/^CHYMISTRY. 389 
 
 As we have no eftablifhed theory to proceed upon, 
 we mall not undertake to explain this extraordina- 
 ry fa<fc. 
 
 PROCESS IV. 
 
 fT0 prepare Glafs of Lead. 
 
 TAKE two parts of Litharge, and one part of 
 pure crystalline Sand ; mingle them together 
 as exactly as potlible, adding a little Nitre and Sea- 
 falt : put this mixture into a crucible of the mod 
 folid and moft compact earth. Shut the crucible 
 with a cover that may perfectly clofe it. 
 
 Set the crucible thus prepared in a melting fur- 
 nace-, fill the furnace with coals-, light the fire 
 gradually, ib that the whole may be flowly heated : 
 then raiie the fire ib as to make the crucible very 
 red, and bring the matter it contains into fufion ; 
 keep it thus melted for a quarter of an hour. 
 
 Then take the crucible out of the furnace, and 
 break it : in the bottom thereof you will moft com- 
 monly find a fmall button of Lead, and over it a 
 tranfparent Glafs, of a yellow colour nearly refem- 
 bling that of amber. Separate this Glafs from the 
 little button of metal, and from the faline matters 
 which you will find above it. 
 
 OBSERVATIONS. 
 
 PURE Lead, being expofed to a ftrong fire with- 
 out any additament, turns to Litharge ; which is a 
 icaly fort of fubitance, more or lets yellowilh, fhin- 
 Ing, and foft to the touch. This is the firft advance 
 -to the Vitrification of Lead. The large refineries 
 of Gold and Silver by the means of Lead furnifh a 
 great quantity of this material. It is fometimes 
 whittfh, and is then called Litharge of Silver 5 fome- 
 C c 3 times
 
 ELEMENTS of the 
 
 times yellow, and then bears the name of Litharge 
 i/f Gold. The difference of its colour depends on 
 the degree of fire it hath undergone, and on the 
 metalline fubftances vitrified with it. 
 
 Litharge alone is very fufible, and being expofed 
 to the fire is eafily converted into Glafs : but this 
 Glafs of Lead, made without additament, is fo 
 active, Ib penetrating, and ickapt to fwell, that it 
 can fcarcely be made ufe of when pure. We are 
 obliged in lome fort to clog it, by uniting it with 
 lome vitrifiablc matter that is not fo fubtile, fuch 
 as Sand , and it is for this reafon, not to render 
 the mixture more fufible, that we have directed 
 the addition of one third part of Sand to two thirds 
 of Litharge. 
 
 The Nitre and Sea-ialt, prefcribed as ingredients 
 .in the mixture, are defigned to procure an equal fu- 
 fion of the whole. For, as the Sand is lighter and 
 Ids fufible than the Litharge, it will partly rile to- 
 wards the upper part of the crucible when that 
 matter firft begins to flow ; in conlequence whereof 
 the contents of the upper part will be much more 
 ^difficult to melt, and form a Glais much more com- 
 pact than that below: but the Nitre and Sea-lalt 
 poflTefling the upper part of the crucible, becaufc 
 they are itill lighter than the Sand, and being in 
 their own nature very efficacious fluxes, on account 
 of their great fufibility, they quickly bring about 
 the fuflon of thole particles of Sand, which, having 
 efcaped the action of the Litharge, may have rifen 
 unverified to its furface. 
 
 The mod difficult thing to procure, and yet the 
 moft neceflary to the fuccefs of this operation, is a 
 crucible of earth fo firm and compact as not to be 
 penetrated by the Glafs of Lead, which corrodes 
 and makes its way through every thing. 
 
 The precaution of chufing a crucible, that (hall 
 contain a good deal more than the matter to be vi- 
 trified,
 
 PR AC TIC E 'of Ctl YMISTR Y. 391 
 
 trified, is a necefiary one, becaufe Litharge andGlafs 
 of Lead are very apt to fwell. 
 
 The rule to keep the crucible clofe fliut is alfo 
 indifpenfably necefTary, to prevent any bit of char- 
 coal, or other inflammable matter, from falling into 
 it : for when this happens it occafions a reduction of 
 the Lead, which is always attended with a fort of 
 efferveicence, and fuch a confiderable heaving, that 
 commonly moft of the mixture runs over the cruci- 
 ble. For the fame reafon it is very proper, before 
 you expofe the mixture to the fire, to examine whe- 
 ther or no it contains any matter capable of furnifh- 
 ing a phlogifton during the operation ; and if it 
 does, to remove that matter with great care. 
 
 The little button of Lead, found at the bottom 
 of the crucible after the operation, comes from a 
 imall portion of Lead that is commonly left in Li- 
 tharge, unlefs you prepare it carefully yourfelf, and 
 do not take it from the fire till you are fure of hav- 
 ing deftroyed all the Lead. Befides, this frnail por- 
 tion of Lead can be of no prejudice to the opera- 
 tion, becaufe it cannot communicate its phlogifton 
 to the reir of the matter. 
 
 The revivifying of Litharge, of the Calx, and of 
 the Glafs of Lead, may be obtained by the fame 
 precedes as the reduction ot its ore. 
 
 PROCESS V. 
 
 Lead diffihed by the Nitrous Acid. 
 
 U T into a matrafs fome Aqua Fortis precipi- 
 tated like that uled to diffolve Silver; weaken 
 it by mixing therewith an equal quantity of common 
 water-, fet the matrafs in a hot fand-bath -, throw in- 
 to it, little by little, fmall bits of Lead, till you fee 
 that no mere will diffolve. Aqua Fortis thus lowered 
 will diilolve about a fourth of its weight of Lead. 
 C c 4 There
 
 392 ELEMENTS of the 
 
 There is gradually formed upon the Lead, as it 
 cfiiTolves, firft a grey powder, and afterwards a 
 white cruft, which at lad hinder the folvcnt from 
 afting on the remaining part of the metal -, and 
 therefore the liquor fhould be made to boil, and 
 the vefTel mould be fhaken to remove thole impe- 
 diments, by which means all the Lead will be dil- 
 lolved. 
 
 B S E R VA r I N S. 
 
 LEAD very much refembles Silver, with refpect 
 to the phenomena which attend its diflbkition in 
 Acids. For example, the Nitrous Acid mult be 
 very pure and uncontaminated with the Vitriolic or 
 Marine Acid, to qualify it for keeping the Lead in 
 folution : for, if it be mixed with either the one or 
 the other of thefe Acids, the Lead will precipitate 
 in the form of a white powder as fad as it difiblves ; 
 which is juft the cafe with Silver. 
 
 If the Vitriolic Acid be mixed with the Nitrous, 
 the precipitate will be a combination of the Vitriolic 
 Acid with Lead , that is, a Neutral Metallic Salt, 
 or Vitriol of Lead. If the Acid of Sea-falt be mixed 
 therewith, the precipitate will be a Plumbum cor- 
 neum ; that is, a Metallic Salt refembling the 
 Luna Cornea. 
 
 When all the Lead is diflblved as above described, 
 the liquor appears milky. If it be kept warm over 
 the fire till little cryftals begin to appear on its fur- 
 face, and afterwards left to (land quiet, in a certain 
 time there will be found at the bottom a greyifh 
 powder, which being tried on Gold is Mercurial 
 enough to whiten it. Little globules of Quick- 
 filver are even difcernibie in it. 
 
 "We owe this obfervation, together with this man- 
 lier of proving the exigence of Mercury in Lead, 
 and of procuring it from thence, to M. Groflc, who 
 hath given an account of his procefs in the Memoirs 
 
 of
 
 PRACTICE of CHYMISTRY. 39? 
 
 of the Academy of Sciences, from whence we have 
 copied the defcription of the operation in hand. 
 
 The iblution being quickly poured off by incli- 
 nation from the grey mercurial precipitate is ftili 
 milky, and depofites another white fediment. When 
 this iecond precipitate falls the liquor becomes clear 
 and limped, and is then of a fine yellow colour, like 
 a folution of Gold. On this gold-coloured iblu- 
 tion, and on the two precipitates above-mentioned, 
 M. Grofie made feveral obfervations, the chief of 
 which we fhall here infert. 
 
 The yellow liquor affects the tongue at firft with 
 a tafte of fweetnels -, but afterwards vellicates it very 
 fmartly, and leaves on it a ftrong feniation of acri- 
 mony, which continues for a long time. 
 
 Alkalis precipitate the Lead fuipended in this li- 
 quor, juft as they do all other metals diffolved by 
 Acids ; and this precipitate of Lead is white. 
 
 Sea-falt, or Spirit of Salt, feparates the Lead from 
 its folvent, and precipitates it, as we obferved be- 
 fore, into a Plumbum ccrneum : but this precipi- 
 tate differs from the Luna cornea, as being very Ib- 
 luble in water j whereas the Luna cornea will not 
 difiblve in it at all , or at leaft diffolves therein with 
 great difficulty, and in a very fmall quantity. This 
 Plumbum corneum diffolved in water is again precipi- 
 tated by the Vitriolic Acid. M. Groffe obferves 
 that this forms an exception to the eighth column of 
 Mr. Geoffrey's Table of affinities , in which the 
 Acid of Sea-falt is marked as having a greater affi- 
 nity than any other Acid with Metallic fubltances. 
 
 Our folution of Lead is allb precipitated in a 
 white powder by feveral Neutral Saks-, fuch as 
 Virriolated Tartar, Alum, and common Vitriol. It 
 is by the means of double affinities that thefe Neu- 
 tral Saks effect this precipitation. 
 
 Even pure water alone is.capable of precipitating 
 the Lead of our folution, by weakening the Acid, 
 
 and
 
 394 ELEMENTS of the 
 
 and thereby difabling it from keeping the metal 
 lulpended. 
 
 Laftly, as all the folutions of metals in Acids are 
 nothing but Neutral metallic Salts in a fiuid form, 
 io if the folution of Lead be evaporated over the 
 fire, it will (hoot into very beautiful cryftals, about 
 the bigneis cf hemp-iced, fhaped like regular pyra- 
 mids having fquare bales. Thefc cryftals are yel- 
 lowifh, and have a Iweec laccharine tafte : but what 
 is moil.fmgular in them is, that, as they confift of 
 the Nitrous Acid combined with Lead, which ma- 
 nifcllly contains a great deal of phlrgifton, they 
 conftitute a Nitrous Metallic Salt, which has the 
 property of deflagrating in a crucible, without the 
 addition of any other inflammable matter. It is 
 extremely hard to diflblve this Salt in water. 
 
 ,lhe grey mercurial precipitate which whitens 
 Gold, and in which little globules of running Mer- 
 cury are perceivable, is far from beir.p; pure Mer- 
 cury. This metallic fubtrance makes but a fmall 
 part thereof: for it is an aflemblage i . of little cryf- 
 rals of the fame nature wirh thole afforded by the 
 evaporated folution , 2. of a portion of the white 
 matter, or powder, which renders the folution milky -, 
 3. of a grey powder which M. Grofle confiders as 
 the only mercurial part-, 4. and laftly, of little 
 particles of Lead that have efcaped the action of 
 the folvent-, efpecially if a little more Lead than 
 the Acid is capable of dilTolving were added with a 
 view to laturate it entirely, as in the prefent procefs. 
 
 By means of motion and heat the fmall parcels of 
 Mercury may be amalgamated with the Lead. 
 . That Mercury mould be found intire and in glo- 
 bules in the Spirit of Nitre, which very eafily dif- 
 iblves that metallic fubftance, will not be furprizing 
 to thofe who reflect that, in the prefent cafe, the 
 Acid is faturated with Lead, with which it has a 
 greater affinity than with Mercury \ as appears by 
 
 M.
 
 PR ACTICE of CHYMISTR Y. 395 
 
 M. Geoffrey's Table of Affinities, where, in the 
 column that hath the Nitrous Acid at top, Lead is 
 placed above Mercury. Agreeably to this, if Lead 
 be prefented to a folution of Mercury in Spirit of 
 Nitre, the Lead will be diffolved, and as the diflblu- 
 tion thereof advances the Mercury will precipitate. 
 
 Hence it appears that, in order to find any Mer- 
 cury in the fpontaneous precipitate of Lead diflblved 
 by the Nitrous Acid, it is neceffary that the Acid 
 be entirely faturated with Lead ; or elie that por- 
 tion of the Acid which remains unfaturated will 
 diflblve the Mercury. 
 
 With regard to the white powder that renders the 
 folution milky, and afterwards precipitates, it is no- 
 thing but a portion of the Lead, which, not being 
 intimately united with the Acid, falls in part of its 
 own accord. It is a fort of calx of Lead, which 
 being expofed to the fire becomes partly glafs, and 
 partly Lead, becaufe it ftill retains fome of its phlo- 
 gifton. 
 
 CHAP. VII. 
 
 Of MERCURY. 
 
 PROCESS I. 
 
 To exiraff Mercury from its Ore, cr to revivify if 
 from Cinabar. 
 
 PULVERIZE the Cinabar from which you 
 would extrad the Mercury -, with this powder 
 mix an equal part of clean iron filings ; put the mix- 
 ture into a retort of glafs or iron, leaving at leaft 
 one third part thereof empty. Set the retort thus 
 
 prepared
 
 396 ELEMENTS of the 
 
 prepared in a find-bath, fo that its body may be 
 quite buried in the land, and its neck decline confi- 
 derably downwards : fit on a receiver half filled with 
 water, and let the nofe of the retort enter about 
 half an inch into the water. 
 
 Heat the veflels fo as to make the retort mode- 
 rately red. The Mercury will rife in vapours, which 
 will condenic into little drops, and fall inco the wa- 
 ter in the receiver. "When you fee that nothing 
 more comes over with this degree of hear, increafe 
 it, in order to raife what Mercury may ftill be left. 
 "When all the Mercury is thus brought over, take 
 off the receiver, pour out the water contained in 
 jr., and collect the Mercury. 
 
 OB S E R V A<T 10 NS. 
 
 MERCURY is never mineralized in the bowels of 
 the earth by any thing but Sulphur j with which it 
 forms a compound of a brownilh red colour, known 
 by the name of Cinalnr. 
 
 Sometimes it is only mixed with earthy and ftony 
 matters that contain no Sulphur-, but as this me- 
 tallic fubftance is never deftitute of its phlogifton, 
 it then has its metalline form and properties. When 
 it is found in rhis condition, nothing is more eafy 
 than to feparate it from thole heterogeneous matters. 
 For that ptirpofe no more is requifite than to diftill 
 the whole with a fire ftrong enough to raife the 
 Mercury in vapours^ This mineral is volatile -, the 
 earthy and ftony matters are fixed \ and a certain 
 degree of heat will effect a complete feparation of 
 what is volatile from what is Jixed. 
 
 This is not the cafe when Mercury is combined 
 with Sulphur : for this latter mineral is volatile as 
 well as Mercury ; and the compound refulting from 
 the union of them both is alfo volatile : fo that 
 if Cinabar were expofed to the fire in dole vefiels, 
 
 as
 
 PRACTICE of C H Y M i s T R Y. 397 
 
 as it muft be to lave the Mercury* it would be 
 fublimed in fubftance, without being decompoied 
 at ail. 
 
 In order therefore to feparate thefe two Jubilances 
 from each other, we mult have recourle to the in- 
 terpofition of fome third, which hath a greater af- 
 finity with one of them than the other hath, and no 
 affinity with that other. 
 
 Iron hath all the conditions requifite for this pur- 
 pofe; feeing it hath, as may be feen in the Table, 
 a much greater affinity with Sulphur than Mercury 
 hath, and is incapable of contracting any union 
 with Mercury. 
 
 Iron, however, is not the only fubftance that may 
 be employed on this occafion : Fixed Alkalis, Ab- 
 ibrbent earths, Copper, Lead, Silver, Regulus of 
 Antimony, have all, as well as Iron, a greater affi- 
 nity than Mercury with Sulphur. Nay, feveral of 
 thefe fubftanccs, namely, the faline and earthy Al- 
 kalis, as well as Regulus of Antimony, cannot con- 
 tract any union with Mercury : the reft, to wit, Cop- 
 per, Lead, and Silver, are indeed capable of amal- 
 gamating with Mercury; but then the union which 
 thefe metals contract with the Sulphur prevents it \. 
 and even tho' they fhould unite with this metallic fub- 
 ftance, the degree of heat to which the whole mixture 
 is expofed would loon carry up the Mercury, and 
 feparate it with eafe from thofe fixed fubftances. 
 
 In this diftillation the fame cautions muft be ob- 
 ferved as in all others : that is, the veflels muft be 
 flowly heated, efpecially if a glafs retort be ufed ; 
 the fire muft be raifed by degrees, and a much 
 ftronger one applied at laft than at firft. This 
 operation particularly requires a very ftrong de- 
 gree of fire, when there is but a fmall quantity of 
 Mercury left. 
 
 After the operation there remains in the retort a, 
 compound of Iron and Sulphur, which may eafily 
 
 be
 
 398 ELEMENTS of the 
 
 be converted into a crocus^ by calcining it and 
 burning away the Sulphur. 
 
 If a Fixed Alkali be employed, a Liver of Sulphur 
 will be found in the retort after the diftillation. 
 
 If the Cinabar from which you extract the Mer- 
 cury be good, you will generally obtain fevcn 
 eighths ot its weight in Quick-filver. 
 
 In the prefent operation it is not necefiary to lute 
 on the receiver, becaufe the water, in which the nofe 
 of the retort is plunged, is fufficient to fix the Mer- 
 curial vapours. In cafe the Cinabar, from which 
 you intend to leparate the Mercury, be mixed with 
 a great quantity of heterogeneous, but fixed, mat- 
 ters, fuch as earths, (tones, &c. it may be fepa- 
 rated from them by fubliming it with a proper de- 
 gree of heat, becaufe it is volatile. 
 
 The vapours of Mercury are prejudicial, and 
 may excite a falivation, tremors, and palfies \ they 
 fhould therefore be always avoided by fuch as 
 work on this mineral. 
 
 The oldeir. and richeft mine of Mercury is that of 
 Almaden in Spain. It is a fingular property of that 
 mine that, though the Mercury found in it is com- 
 bined with Sulphur, and in the form of Cinabar, 
 yet no additament is required to procure the fepara- 
 tion of thefe two-, the earthy and itony matter, with 
 which the particles of the ore are incorporated, be- 
 ing itfelf an excellent abforbent of Sulphur. 
 
 In the Qu'ck-iilver works carried on at this mine 
 they make no uie of retorts. They place lumps of 
 the ore on an iron grate, which ttands immediately 
 over the furnace. The furnaces which ferve for this 
 operation are clofed at the top by a fort of dome, 
 behind which Rands the fliaftofa chimney that com- 
 municates with the fire-place, and gives vent to the 
 fmoke. Thcfe furnaces have in their fore-fide fix- 
 teen apertures, to each of which is luted an aludel 
 in a horizontal pofition, communicating with a 
 
 long
 
 PR ACT I CE of CH Y MI STR Y. 399 
 
 long row of other aludels placed iikewife in an ho- 
 rizontal direction; which aludels fo connected to- 
 gether form one long pipe or canal, the farther 
 end whereof opens into a chamber clelVmed to re- 
 ceive and condenfe all the mercurial vapours. 
 Thefe rows of aludels are fupported from end to 
 end by a terrafs, which runs from the body of the 
 building, wherein the furnaces are erected, to that 
 where the chambers are built that perform the of- 
 fice of receivers. 
 
 This is a very ingenious contrivance, and faves 
 much labour, expence, and trouble, that would be 
 unavoidable if retorts were employed. 
 
 That part of the furnace which contains the 
 lumps of ore, ferves for the body of the retort ; 
 the row of aludels for its neck , and the little 
 chambers in which thefe canals terminate are ac- 
 tual receivers. The terrafs of communication, 
 which reaches from the one building to the other, 
 is formed of two inclined planes, the lower edges 
 of which, meeting in the middle of the terrafs, rife 
 from thence infenfibly -, the one quite to the build- 
 ing where the furnaces are, and the other to that 
 which forms the recipient chambers. By this 
 means, when any Mercury efcapes through the 
 joints of the aludels, it naturally runs down along 
 thefe inclined planes, and fo is collected in the 
 middle of the terrafs, where the inferiour fides of 
 the planes meeting together form a fort of canal, 
 out of which it is eafily taken up. 
 
 The celebrated M. de Juflieu having viewed the 
 whole himfelf, in a journey he made to this mine, 
 furnilhed us with this defcription of the work. 
 
 PRO-
 
 400 ELEMENTS of the 
 
 PROCESS II. 
 
 To give Mercury, by the attion of Fire, tie app; tr- 
 ance of a Metalline Calx. 
 
 PUT Mercury into feveral little glafs matrafles 
 with long and narrow necks. Stop the ma- 
 tralles with a little paper, to prevent any dirt from 
 lalling into them. Set them all in one land-bath, 
 io that they may be lurrounded with land as high as 
 two thirds of their length. Apply the ftron^tit de- 
 gree ol heat that Mercury can bear without iublim- 
 ing : continue this heat without interruption, till all 
 the Mercury be turned to a red powder. The ope- 
 ration latls about three months. 
 
 OBSERVATIONS. 
 
 MERCURY treated according to the procefs here 
 delivered hath all the appearance of a metalline calx, 
 but it hath no more : for, if it be expofed to a pretty 
 ftrong degree of fire, it fublimes, and is wholly re- 
 duced to running Mercury, without the addition of 
 any other inflammable matter ; which proves that 
 during this long calcination it loft none of its phlo- 
 gifton. 
 
 The volatile nature of Mercury, which permits it 
 not to bear a heat of any ftrength without fublim- 
 ing, prevents our examining all the effects that fire 
 is capable of producing on it. Yet there is reafon 
 to believe that, as this metallic fubftance refcmbles 
 the perfect metals in its weight, its fplendour, and 
 a brilliancy whch refifts all the impreflions of the 
 air without alteration, it would like them be un- 
 changeable by the Created force of fire, if it were 
 fixed enough to bear it. 
 
 In order to give Mercury the form of a metalline 
 
 calx, it mutl necefiarily be expofed for about three 
 
 5 months
 
 PRACTICE ^CHYMISTRY. 401 
 
 months together, to the utmoft heat it can bear 
 without fubliming, as is above directed. Boerhaave 
 kept it digefting in a lefs heat for fifteen years fuc- 
 ceffively, both in open and in clofe veffels, without 
 bbferving it to fuffer the leaft change ; except that 
 there was formed upon its furface a fmall quantity 
 of a black powder, which was reduced to running 
 Mercury by trituradon alone. 
 
 Mercury thus converted to a red powder is known 
 in chymiftry and medicine by the name of Mercury 
 precipitated per fe : a title proper enough, as it is 
 actually reduced to the form of a precipitate, and 
 that without any additament > but very improper ori 
 the other hand, confidering that in reality this Mer- 
 cury is not a precipitate, as not having been feparat- 
 ed from any menftruum in which it was difTolved. 
 
 P R O C E-S S III. 
 
 To diffohe Mercury in the Vitriolic Acid, Turbitk 
 
 f Mineral. 
 
 PUT Mercury into a glafs retort, and pour on 
 it thrice its weight of good Oil of Vitriol, 
 bet the retort in a fand-bath ; fit on a recipient ; 
 warm the bath by degrees till the liquor jufl fim- 
 mer. With this heat the Mercury will begin to 
 diflblvc. Continue the fire in this degree till all 
 the Mercury be difTolved. 
 
 OBSERVATIONS. 
 
 THE Vitriolic Acid difiblves Mercury pretty well : 
 but for this purpofe the Acid muft be very hot, or 
 even boil ; and then too it is a very long time before 
 the difTolution is completed. We have directed the 
 operation to be performed in a retort , becaule this 
 folution is ufually employed to make another prepa- 
 ration called Turbitb Mineral^ which requires that as 
 much as poflible of the Acid folvent be abitrafled by 
 
 VOL. I. D d diftil-
 
 402 E L E M E N T S of fkt 
 
 diftillation. Having therefore diffolved your Mer- 
 cury in the Vitriolic Acid, if you will now prepare 
 the Turbith, you mutt, by continuing to heat the 
 retort, drive over all the liquor into the receiver, 
 and diflill till nothing remains but a white pow- 
 dery matter : then break the retort: pulverize its 
 contents in a glafs mortar, and thereon- pour com- 
 mon water, which will immediately turn the white 
 matter of a lemon colour ; wafh this yellow matter 
 in five or fix warm waters, and it will be what is 
 called in medicine Turlith Mineral^ that is, a com- 
 bination of the Vitriolic Acid with Mercury, five 
 or fix grains whereof is a violent purgative, and 
 alfo an emetick ; qualities which rt pofTefTes in 
 common with the Vegetable Turbith, whofe name 
 it hath therefore taken. 
 
 There rifes out of the retort, both while the 
 Mercury is diflblving, and while the folvent is ab- 
 ftrafling, a weak Spirit of Vitriol ; becaufe a great 
 part of the Acid remains united with the Quick- 
 filver, which at laft appears in the form of a white 
 powder: fo thru, if you do not incline to fave the 
 Acid which rifcs on r his occafion, you may, inftread 
 of drawing off the liquor in a retort, evaporate it 
 in a glafs bafon it-t on a fand-bath, which will be 
 much fooner done. 
 
 It is very remarkable that, on this occafion, the 
 Mercury may be expofed, without any danger of 
 fubliining, to a much greater heat than it is capable 
 of bearing when not combined with the Vitriolic 
 Acid ; which fhcw's that this Acrd hath the pro- 
 perty of fixing Mercury to a certain degree. 
 
 The white matter, that remains after the evapo- 
 ration of the fluid, is one of the mod violent cor- 
 vofu'ts, and would prove an actual poifon- if taken 
 internally. By wallving it feveral times in warm 
 water it is frcc-d from a great deal of its Acid, and 
 fo confiderably fweetened. The proof is this ; if 
 the water ufed in wafhing the Turbith be evapo- 
 \ fated,
 
 PRACTICE ^CHYMISTRY. 40; 
 
 fated, there remains after the evaporation a matter 
 in form of a Salt, that being fet in a cellar runs 
 into a liquor called Oil of Mercury , which is a pow- 
 erful corrofive. Several authors further direct Spi- 
 rit of Wine to be burnt on the Turbith, to fweeten 
 it Hill more. 
 
 If inftead of warning the white matter that re- 
 mains after the moifture is drawn off, frefh Oil of 
 Vitriol be poured on it, and then abftrafted as be- 
 fore ; this treatment being repeated two or three 
 times, there will at laft remain in the retort a mat- 
 ter having the appearance of an oil, which refifls 
 the action of the fire, and cannot be deficcated : 
 qualities which are owing to the great quantity of 
 Acid particles thus united with the Mercury. This 
 Oil of Mercury is one of the moft violent corro- 
 lives. The Mercury may be feparated therefrom, 
 by precipitating it with an Alkali, or a metallic fub- 
 llance that hath more affinity than Mercury with 
 the Vitriolic Acid : Iron, for inftance, may be em-- 
 ployed in this precipitation. Mercury thus fepa- 
 rated from the Vitriolic Acid need only be diftilled 
 to recover the form of Quick-filver. 
 
 PROCESS IV. 
 
 To combine Mercury with Sttlpkur. ALthiops Mineral. 
 
 MI X a dram of Sulphur with three drams of 
 Quick-filver, by triturating the whole in a 
 glafs mortar with a glafs peftle. By degrees, as you 
 triturate* the Mercury will difappear, and the matter 
 will acquire a black colour. Continue the triture 
 till you cannot perceive the lead particle of running 
 Mercury. The black matter you will then have in 
 the mortar is known in medicine by the name of 
 Ethiops Mineral. An JEchiops may alfo be made 
 by fire in the following; manner. 
 
 TO d 2 In
 
 404 ELEMENTS of tit 
 
 In a {hallow unglazed earthen pan melt one part 
 of Mowers of Sulphur : add three parts of running 
 Mercury, making it fall into the pan in the form of 
 Imall rain, by fqueezing it through chamoy leather. 
 Keep (lirring the mixture with the ihank of a to- 
 bacco-pipe all the while the Mercury is falling : 
 you will fee the matter grow thick and acquire a 
 black colour. When the whole is thoroughly 
 mixed, let lire to it with a match, and let as much 
 of the Sulphur burn away as will flame. 
 
 OBSERVATIONS. 
 
 MERCURY and Sulphur unite together with great 
 cafe; cold triture alone is fufficient to join them. 
 By this means the Mercury is reduced into exceed- 
 ing fmall atoms, and combines lo perfectly with the 
 Sulphur that the leafi: veftige thereof is not to be 
 feen. 
 
 Sulphur is not the only matter which being rub- 
 bed with Mercury will deftroy its form and fluidity: 
 all fatfubftances that have any degree of confidence, 
 fuch as the fat of animals, balfams, and refins, are 
 capable of producing the fame effect. This metal- 
 lic Jubilance, being triturated for tome time in a 
 mortar with theie matters, becomes at laft invifible, 
 and communicates to them a black colour. \Vhni 
 thus divided by the interpofition of heterogeneous 
 particles, it is laid to be Killed. But Mercury doth 
 not contract fuch an intimate union with thefc 
 other matters as it doth with Sulphur. 
 
 The /Ethiops prepared by fufion is a more pel- 
 feet and accurate combination of Mercury and Sul- 
 phur than the other : for, the quantity of Sulphur 
 directed to be ufed in making it being much creator 
 
 o o o 
 
 than is ablolutely neceffary to fix the Mercury, the 
 redundant Sulphur is deftroyed by burning, and 
 hone left but what is mod intimately united with 
 the Mercury, and hindered by the union it 'mh 
 i con-
 
 PRACTICE O/*CHYMISTRY. 405 
 
 contracted with that metallic fubftance from bein^ 
 fo eafily confumed. The ./Ethibps therefore, which 
 is prepared by fufion and burning the Sulphur, 
 contains a much greater proportion of Mercury 
 than that which is made by fimple triture; fo that 
 in Medicine it ought to be prelcribed in different 
 cafes, and in fmaller dofes. 
 
 If no more Sulphur than is juft necefiary to kill 
 the Mercury be added to it at firft, it will be dif- 
 ficult to obtain a perfect mixture ; becaufe that 
 quantity is very fmall : it is better therefore to em- 
 ploy at once the quantity above directed. 
 
 PROCESS V. 
 
 ST0 fublime the combination of Mercury and Sulphur 
 into Cinabar. 
 
 GRIND to powder JEthiops mineral prepared 
 by fire. Put it into a cucurbit , fit thereto a 
 head ; place it in a fand-bath, and begin with apply- 
 ing fuch a degree of heat as is requilite to fublime 
 Sulphur. A black matter will rife, and adhere to 
 the fides of the veflel. When nothing more will 
 rife with this degree of heat, raifc the fire fo as to 
 make the fand and the bottom of the cucurbit red ; 
 and then the remaining matter will fublime in the 
 fprm of a brownilh red mafs, which is true Cinabar, 
 
 B S E R V A? IONS. 
 
 ./ETHIOPS Mineral requires nothing but fublima- 
 tion to become true Cinabar, like that found in 
 Quick-filver mines : but our JEthiops contains ftill 
 more Sulphur than ought to be in the compofition 
 of Cinabar ; for which reafon we have directed the 
 degree of fire applied at firft to be no greater than 
 that which is capable of fubliming Sulphur. As 
 Cinabar, though confifting of Mercury and Sul- 
 D d 3 P hur >
 
 406 ELEMENTS of tie 
 
 phur, is yet much leis volatile than either of thefe 
 Jubilances alone ; which probably arifes from the 
 Vitriolic Acid contained in the Sulphur-, there- 
 fore, if there be any redundant Sulphur in the 
 
 hiops, which hath not contracted an intimate 
 union with the Mercury, it will fublime by itfelf 
 in this firft degree of heat. Some mercurial parti- 
 cles alib will rile with it, and give it a black colour. 
 
 Cinabar contains no more Sulphur than about a 
 fixth or leventh part <.Yi:s \\< .vju : fo that, inftead 
 of employing the common ^fcthiops to make it, it 
 would be better to prepare one on purpofe that 
 fiiould contain much lefs Sulphur , becaule toq 
 much Sulphur prevents the fuccefs of the operation 
 by blackening the Sublimate. Indeed in whatever 
 manner you go about it, the Cinabar always ap^ 
 pears black at firft : but when it is well prepared, 
 and contains no more than its due proportion of 
 Sulphur, the blacknels is only external. This black 
 coat therefore may be taken off: and then the in- 
 ternal part will appear of a fine red, and, if fub- 
 limed a fccond time, will be very beautiful. 
 
 As artificial Cinabar hath the fame properties 
 xvith the native, it may be decompofed by the 
 fame means : fo that, if you want to extra/t the 
 Mercury out of it, recourfe muft be had to the pro- 
 eels above delivered for working on Cinabar ores. 
 
 PROCESS VI. 
 
 diffclve Mercury in tbe "Nitrcus Acid. Sundry 
 Mercurial Precipitates. 
 
 PU T into a matrafs the quantity of Mercury 
 you intend to diflblve : pour on it an equal 
 quantity of good Spirit of Nitre, and fet the matrafs, 
 in a fand-bath moderately heated. The Mercury 
 v/illdifiblve with the phenomena that ufually attend 
 
 the;
 
 ICE of C H Y M i s T R Y. 407 
 
 the diflblutions of metals in this Acid. When the 
 diHblution is completed let the liquor cool. You 
 will know that the Acid is perfectly faturated, if 
 there remain at the bottom of the veflel, notwitli- 
 flanding the heat, a little globule of Mercury that 
 will not difiblve. 
 
 OBSERVATIONS. 
 
 MERCURY diflblves in the Nitrous Acid with 
 much more facility, and in much greater quantity, 
 than in the Vitriolic ; fo that it is notneceHary, on 
 this occafion, to make the liquor boil. This folu- 
 tion when cold yields cryftals, which are a Nitrous 
 Mercurial Salt. If you defire to have a clear lim- 
 pid folution of Mercury, you muft employ an Aqiia 
 portis that is not tainted with the Vitriolic or Marine 
 Acid : for, the affinity of thefe two Acids with 
 Mercury being greater than that of the Nitrons 
 Acid, they precipitate it in the form of a white 
 powder, when .they are mixed with the folvent. 
 
 Mercury thus precipitated in a white powder, out 
 .of a folution thereof in the Spirit of Nitre, is ufed 
 in Medicine. To obtain this precipitate, which is 
 known by the name of the White Precipitate^ Sea- 
 falt difTolved in water together with a little Sal Am- 
 moniac is ufed ; and the precipitate is warned feveral 
 jtimes in pure water, without which precaution it 
 would be corrofive, on account of the great quan- 
 tity of the Marine Acid which it would contain. 
 
 The preparation known by the name of Red Pre- 
 cipitate is alfo obtained from our folution of Mer- 
 cury in Spirit of Nitre. It is made by abftracling 
 all the moifture of the folution, either by diftillation 
 in a retort, or by evaporation in a glafs bafon fet on 
 a fand-bath. When it begins to grow dry it appears 
 like a white ponderous mafs. Then the fire is made 
 ftrong enough to drive off aJmolt all the Nitrous 
 ? A,cid, which, being now concentrated, riles in the 
 D d 4 form,
 
 E L E M E N T S of tbf 
 
 form of red vapours. If thefe vapours be catched 
 in a receiver, they condenfe into a liquor, which is 
 a very ftrcng and vaftly fmoking Spirit or" Nitre. 
 
 By degrees, as the Nitrous Acid is forced up by 
 the fire, the mercurial mafs lofes its white colour, 
 and becomes fir ft yellow, and at lad very red. 
 When it is become entirely or" this lad colour thfj 
 operation is finifhed. The red mafs remaining is a 
 Mercury that contains but very little Acid, in com- 
 panion of what k did while it was white : and in- 
 deed the firil white mafs is fuch a violent corrofive, 
 that it cannot be ufed in Medicine ; whereas, when it 
 is become red, it makes an excellentelcharotic, which 
 thofe who know how to ufe it properly apply with 
 very great fuccefs, particularly to venereal ulcers. 
 
 This preparation is very improperly called a Pre- 
 tipitate : for the Mercury is not leparated from the 
 Spirit of Nitre by the interpofition of any other 
 Jubilance, but only by evaporating the Acid. It 
 is a lib called Arcanum Corattinum. 
 
 It muft be obferved that Mercury, by its union 
 with the Nitrous Acid, acquires a certain degree of 
 fixity : for the red precipitate is capable of fuflain- 
 inp, without being volatilized, a ftronger degree 
 of heat than pure Mercury can ; which, as we ob- 
 ferved before, is the property of Turbith mineral 
 alfo. 
 
 PROCESS VII. 
 
 *T0 combine Mercury with tke Acid of Sea-falt. 
 Corrcfae Sublimate. 
 
 EVAPORATE a folution of Mercury in the 
 Nitrous Acid till there remain only 'a white 
 powder, as mentioned in our obfervations on the 
 preceding procefs. With this powder mix as much 
 Green Vitriol calcined to whitenefs, and as much 
 decrepitated Sea-falt, as there was Mercury in the 
 
 iolution.
 
 PRACTICE of CH YMISTR Y. 409 
 
 folution. Triturate the whole carefully in a glafs 
 mortar. Put this mixture into a matrafs, fo that 
 two thirds thereof may remain empty, having firft 
 cut off the neck to half its length : or inftead thereof 
 you may ufe an apothecary's phial. Set your vef- 
 iel in a fand-bath, and put fand round it as high as 
 the contents reach. Apply a moderate fire at firft, 
 and raife it by flow degrees. Vapours will begin 
 to afcend. Continue the fire in the fame degree 
 
 O 
 
 till they ceafe. Then flop the mouth of the vefiel 
 with paper, and increafe the fire till the bottom of 
 the land-bath be red-hot. With this degree of 
 heat a Sublimate will rife, and adhere to the infide 
 and upper part of the vefiel, in the form of white, 
 femi-tranfparent cryflals. Keep up the fire to the 
 fame degree till nothing more will fublime. Then 
 
 c> \j 
 
 Jet the veffel cool , break it, and take out what is 
 fublimed, which is Ccrrojive Sublimate. 
 
 Q BSE RVATION S. 
 
 IN this operation the mineral Acids act, and are 
 acted upon, in a remarkable manner. Every one of 
 the three is at firft neutralized, or united with a dif- 
 ferent bafis ; the Vitriolic beingcombined with Iron; 
 the Nitrous with Mercury, forming therewith a Ni- 
 trous Mercurial Salt-, and the Marine with its natural 
 Alkaline bafis, The Vitriolic and Nitrous Acids, 
 which are united with metalline fubftances, being; 
 
 O 
 
 both ftronger than the Acid of Sea-falt, ftrive to 
 expel it from its bafis, in order to combine with it 
 themfelves ; but the Vitriolic Acid, being the 
 ftrongeft of the two, would take ible pofleffion of 
 this bafis exclufive of the Nitrous, which would 
 continue united with the Mercury, if the Marine 
 Acid had not a greater affinity than the Nitrous 
 with this metallic fubftance. This Acid therefore 
 being expelled from its bafis by the Vitriolic Acid, 
 and To fet at liberty, muft unite with the Mercury, 
 and feparate the Nitrous Acid from it j which now 
 hath no refource but to unite with the Iron deferted 
 
 by
 
 410 E L E M E N T s 
 
 by the Vitriolic Acid. But as all thefe changes 
 are brought about by the means of a confiderable 
 hear, and as the Nitrous Acid hath not a very firm 
 connection with the Iron, it is driven off by the 
 force of the fire; and this it is which we fee rife in 
 vapours during the operation. It alfo carries off 
 with it fomc parts of the other two Acids, but in a 
 very imaii quantity. After the operation therefore 
 there remains, i. A combination of the Vitriolic 
 Acid with the bails of Sea-falt , that is a Glauber's 
 Salt : 2. A red martial earth, being that which was 
 the bafis of the Vitriol : thele two fubftances are 
 hl;-nded together, and remain at the bottom of the 
 vefTel becaufe of their fixity: 3. A combination of 
 the Marine Acid with Mercury j both of which be- 
 ing volatile, theyafcend together into the upper part 
 of the vefiel, and there form a Corrofive Sublimate. 
 
 If we reflec~l on this procefs with attention, and 
 recollect diftinctly the affinities of the different fub- 
 itances employed in it, we lhall perceive that it is 
 not neceffary to make ufe of ail thole matters, and- 
 that the operation would lucceed though icveral of 
 them were left out. 
 
 Firft, the Nitrous Acid may be omitted , fince, 
 as hath been (hewn, it is not an ingredient in the 
 Sublimate, but is difiipated in vapours during the 
 operation. From an accurate mixture therefore of 
 Vitriol, Sea-falt, and Mercury, a Corrofive Subli- 
 mate muil be obtained : for as the Acid of the Vi- 
 triol will difengage the Acid of Sea-falt, the latter 
 will be at liberty to combine with the Mercury, and 
 ib form the compound we are in quell of. 
 
 Secondly, if we make ufe of Mercury diflblved 
 by the Nitrous Acid, we may omit the Vitriol i be- 
 caufe the Nitrous Acid having a greater affinity than 
 the Marine Acid itfelf with the bafis of Sea-falt, and 
 the Acid of Sea-falt having a greater affinity than 
 the Nitrous Acid with Mercury, thefe two Acids 
 \vili naturally make an exchange of the bales with 
 
 which
 
 PR ACTICE of CHYMISTRY. 41; 
 
 which they are united : the Nitrous will lay hold 
 on the bafis of Sea-falt, and form a quadrangular 
 Nitre, while the Marine Acid will join the Mer- 
 cury, and with it form a Corrofive Sublimate. 
 
 Thirdly, inftead of Sea- fait its Acid only may be 
 employed; which being mixed with the folution of 
 Mercury in the Spirit of Nitre, will, by virtue of its 
 greater affinity with that metallic fubftance, feparate 
 it from the Nitrous Acid, unite with it, and form a 
 white mercurial precipitate, which need only be 
 fublimed to become the combination required. 
 
 Fourthly, infteacj. of Mercury diffolved in the 
 Nitrous Acid, Mercury diffolved by the Vitriolic 
 Acid, or Turbith, may be ufed ; only mixing Sea- 
 falt therewith : for thefe two faline fubftances will 
 mutually decompound each other, by virtue of the 
 affinities of their Acids, and for the fame reafons 
 that Sea- fair and the Mercurial Nitrous Salt de- 
 compound each other. The Vitriolic Acid quits 
 the Mercury with which it is combined, to unite 
 with the bafis of the Sea-falt ; and the Acid of this 
 Salt being expelled by the Vitriolic, combines 
 with the Mercury, and confequently forms our 
 Corrofjve Sublimate. In this cafe a Glauber's Sale 
 remains after the fublimation. 
 
 Thefe feveral methods of preparing Corrofive 
 Sublimate are never ufed, becauie each of them is 
 attended with fome inconvenience; fuch as re- 
 quiring too long triture, yielding a Sublimate lefs 
 corrofive than it mould be, or a fmaller quantity 
 of it. We muft, however, except the laft ; whicl^ 
 was invented by the late Mr. Boulduc, of the Aca- 
 demy of Sciences, who found none of thefe incon-r 
 veniencies attending it *. 
 
 Corrofive Sublimate may alfo be made only by 
 mixing Mercury with Sea-falt, without any addita- 
 ment. This may appear furprizing when we confi- 
 fkr that, as Acids have a greater affinity with Alka- 
 
 * See the Memoirs of the Academy for 1730. 
 
 US
 
 412 ELEMENTS?/ tie 
 
 His than with metallic fubftances, the Acid of Sea- 
 fait ought not to quit 'its bafis, which is Alkaline, 
 to unite with Mercury. 
 
 In order to explain this phenomenon it mud be 
 remembered that Sea-falt, when expofed to the fire 
 without additamcnt, fuffers a little of its Acid to 
 efcape. Now this portion of the Marine Acid unites 
 with the Mercury, and forms a Corrofive Sublimate. 
 Moreover, as there is a pretty ftrong affinity between 
 the Marine Acid and Mercury, this may help to de- 
 tach from the Sea-falt a greater quantity of Acid 
 than it would otherwiie part with. Neverthelefs 
 the quantity of Sublimate obtained by this means 
 js not confiderable, nor is it very corrofivc. 
 
 On this occafion we muft alfo mention another 
 combination of the Marine Acid with Mercury ; 
 which is made by mixing that metallic fubftance 
 perfectly with Sal Ammoniac, by the means of 
 triture. Mercury, like all other metals except 
 Gold, pofiefTes the property of decompounding 
 Sal Ammoniac, feparating the volatile Alkali which 
 ierves it for a bafis, and combining, by the help of 
 a very gentle heat, with its Acid, which is well 
 known to be the fame with that of Sea-falt. This 
 decompofition of Sal Ammoniac, by the metalline 
 inbftances, is a full exception to the firft column 
 of Mr. Geoffroy's Table of Affinities, and is the 
 bafis of feveral new medicines invented by the hue 
 Comte de la Garaye *. 
 
 Corrofive Sublimate is the moft violent and the 
 jjncft active of all corrofive poifons. It is never ufed 
 An medicine, but in external applications. It is a 
 powerful efcharotic ; it deftroys proud flefh, and 
 cleans old ulcers : but it mnft be ufed by thofe only 
 who know how to apply it properly, and requires an 
 able hand to manage it. It is not commonly applied 
 by itfelf, but mixed in the proportion of half a dram 
 
 * See the Memoir given in by me on this fubjedl to the Aca- 
 demy of Sciences in the Memoir -es fAcadamie 1754. 
 
 to
 
 PRACTICE of CHYMISTRY. 413 
 
 to a pound of lime-water. This mixture is yel- 
 lowifb, arid bears the name of Aqua Phagadtnica. 
 
 \Vater diffblves Corrofive Sublimate, but in a 
 fmall quantity. If a Fixed Alkali be mixed with 
 this folntion, the Mercury precipitates in the form 
 of a red powder., If the precipitate be procured by 
 a VoJatile Alkali, it is white , if by Lime-water, it 
 is yellow. This Mercurial Salt difiolves pretty ea- 
 fily in boiling Spirit of Wine. 
 
 PROCESS VIII. 
 
 Sweet Sublimate. 
 
 TAKE four parts of Corrofive Sublimate; pul- 
 verife it in a glafs or marble mortar ; add by 
 little and little three parts of Mercury revivified from 
 Cinabar , triturate the whole carefully, till the Mer- 
 cury be perfectly killed, fo that no globule thereof 
 can be perceived. The matter will then be grey. 
 Put this powder into an apothecary's phial, or into 
 a matrafs, whofe neck is not above four or five 
 inches long, leaving two-thirds thereof empty. 
 Set the veffel in a fand-bath, and put fand round 
 it to one third of its heighth. Apply a moderate 
 fire at firft ; and afterwards raife it gradually till 
 you perceive that the mixture iublimes. Keep it 
 up to this degree till nothing more will rife, and 
 then break the veifel. RejecT:, as ufelefs, a fmall 
 "quantity of earth which you will find at the bot- 
 tom -, feparate alfo what adheres to the neck of the 
 verTel, and carefully collect the matter in the mid- 
 dle, which will be white. Pulverize it ; fublime it 
 a fecond time,, in the fame manner as before; and 
 in the fame manner feparate trJfc earthy matter left 
 at the bottom of the veffd, and what you find fub- 
 limed into the neck. Pulverize, and fublime a third 
 lime, the white matter you laft found in the mid- 
 dle.
 
 414 El E ME NTS cf the 
 
 die. The white matter of this third fublimation is 
 the Sweet Sublimate, called alfo dquila Alba. 
 
 OBSERVATIONS. 
 
 THE Acid of Sea-falt in the Corrofive Sublimate 
 is very far from being perfectly faturatcd with Mer- 
 cury , and thence comes the corrofive quality of 
 this faline compound. But though Mercury, as 
 appears by this combination, is capable of imbibing 
 a much greater quantity of Acid than is necefiary 
 to diflblve it , nay, though it naturally takes up 
 this fuperabundant quantity of Acid, yet it doth 
 not follow from thence that this redundant Acid 
 may not combine with Mercury to the point of 
 perfect laturation, fo as to loie its corrofive acidity. 
 
 This is the cafe in the operation here defcribed. 
 A frefh quantity of running Mercury is mixed with 
 Corrofive Sublimate ; and the frefh Mercury* com- 
 bining with the fuper-abounding Acid, deprives 
 the Sublimate of its acrimony, and forms a com- 
 pound which comes much nearer the nature of a 
 Neutral Metallic Salt. 
 
 Trituration alone is not fufficier.t to produce an 
 union between the newly added Mercury and the 
 Acid of the Corrofive Sublimate; bec.vjfe, gene- 
 rally fpeaking, the Acid of Sea-falt cannr: diflblve 
 Mercury without the help of a certain degree of 
 heat, and unlcfs ir be reduced into vapours. 
 
 Thus, though the newly added Mercury become? 
 invifible by trkuration,and fcems actually combined 
 \v;th the Corrofive Sublimate, yet the union is not 
 intimate. There i^ only an interpofition of parts, 
 but no trr>e diflblution of the newly added Mercury 
 by the luper-abundant Acid of the Corrofive Subli- 
 mate. For this reafon the mixture mult be Ju- 
 blimed; and by this fublimation only is the true 
 union effected. Nor is one finale fublimation fuf- 
 ficient : no lefs than three arc necelfary to deprive 
 the Sublimate of the corrofive quality which ren- 
 ders
 
 PRACTICE C/CHYMISTRY. 415 
 
 ders it poifonous. After the third fublimation, the 
 Sublimate being put upon the tongue gives no 
 confiderable fenfation of acrimony ; nor doth it re- 
 tain any more of its former activity than is requifite 
 to make it a gentle purgative, when adminiftered 
 from fix to thirty grains for a dofe. 
 
 If a lefs quantity of Mercury than that above di- 
 redled be mixed with the Corrofive Sublimate, the 
 fuper-abundant Acid will not be fufficiently fatu- 
 rated , and the lefs Mercury is added, the more of 
 its corrofive virtue will the Sublimate retain. 
 
 If, on the contrary, a greater quantity of Mer- 
 cury be added, there will be more than the Acid 
 can poffibly dififolve, and the fuperfluous quantity 
 will remain in its natural form of Quick-filver. It 
 is better therefore to err in the excefs than in the 
 defect of the proportion of Mercury to be added , 
 becaufe the Corrofive Sublimate will take up no 
 more than is necefiary to dulcify it. 
 
 Part of the Acid of the Corrofive Sublimate is 
 alfo difiipated in vapours during the operation ; and 
 it is neceflary to allow room for thefe vapours to 
 circulate, and a vent to give them paiTage, or elfe 
 they will burfl the veffds. Thefe are our reafons 
 for leaving an empty fpace in the lubliming veflels, 
 and for having their necks no more than five or fix 
 
 Q 
 
 inches long. 
 
 The matter which fublimes into the neck of the 
 veflel is always very acrid-, for which reafon it 
 mtift be feparated from the Sweet Sublimate. 
 There remains alfo at the bottom of the matrafs an 
 earthy, reddifh matter; which probably comes from 
 the Vitriol employed in making the Corroiive Su- 
 blimate. This matter muft likewife be rejected as 
 yields after every fublimation.
 
 41 6 [ E L E M E ff T S ofj &C. 
 
 PROCESS IX. 
 
 The Panacea of Mercury. 
 
 PULVERISE ibme Sweet Sublimate, and 
 fublime it in the lame manner as you did 
 thrice before. Repeat this nine times. After 
 thefe fublimations it will make no imprefiion on the 
 tongue. Then pour on it aromatic Spirit of Wine, 
 and fet the whole in digeftion for eight days. Af- 
 ter that decant the Spirit of Wine, and dry what 
 remains, which is the Panacea of Mercury. 
 
 OBSERVATIONS. 
 
 THE great number of lublimations, which the; 
 Sweet Sublimate is made to undergo, fweeten it dill 
 more, and to fuch a degree that it leaves no fenfa- 
 tion on the tongue, nor hath any purgative virtue. 
 
 The Spirit of Wine, in which it is digefted after 
 all the fublimations, is defignedto blunt {till more 
 the (harpnefs of any acid particles that may not 
 have been fufficiently dulcified by the preceding 
 fublimations. 
 
 As Mercury is the fpecific remedy for venereal 
 diforders, fundry preparations thereof have been at- 
 tempted with a view to produce different effeftsv 
 Sweet Sublimate is purgative ; arid for that rcalbn 
 is not quite proper tor procuring a falivation, be- 
 caufe it carries off the humours by (tool. The Pa- 
 nacea of Mercury, which, on the contrary, is not 
 purgative, may railc a falivation when taken in- 
 wardly. 
 
 End cf lit F.rji 1'olime.

 
 Pl.n.
 
 PI .
 
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 GXOFFRO Y \V TABJ.i: ,/'//, 
 
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 Explanation of 
 
 ^r^Aad Spirits V ^ bfcrfrrn t F.tirr/.< s 
 *0 MaiinfAcid MS Metallic Jn/> flu nets 
 -0 JfitrousActd Mfrairif 
 * VilriclitAcid & Jtfqulus of_A ntimony 
 QvFlavdAlkA/i /^/// 
 e A Volatile Aituli 3 JV/w
 
 Pl.VE. 
 
 COMPARATIVE AFFINITIES 
 
 frnif/jy ifi/b/hittces . 
 
 n. i. XL ffl. m. m iv: m 
 
 
 
 $ 
 
 k 
 
 9 
 
 p 
 
 c/ 
 
 er 
 
 V 
 
 % 
 
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 k 
 
 ^ 
 
 c/ 
 
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 3" 
 
 9 
 
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 the Characters . 
 
 9 Coppfr Q Sulphur 
 O Ircn J^ Fhfayifton, 
 K ^^d^ ^ S/.nrif- 0f Vinegar 
 If Tin, V &*/ 
 2e 2"wr 8 Neuh-al Ja/ts 
 LC Calamine V Ardent Spirits .
 
 EXPLANATION 
 
 O F T H E 
 
 P L AT E S. 
 
 \ 
 
 PLATE FIRST. 
 F I G. I. A Copper Alembic. 
 
 A. The Cucurbite or Body. 
 
 B. The Neck. 
 
 C. The Head 
 
 D. The Beak, Nofe, or Spout. 
 
 E. The Refrigeratory, or Cooler. 
 
 F. Its Cock. 
 
 G. The Receiver. 
 
 F I G. . II, A Glafs Alembic. 
 
 A. The Cucurbite. 
 
 B. The Head. 
 
 C. The Gutter within the Head. 
 
 D. The Beak. 
 
 FIG. III. Along-necked Glafs Alembic. 
 
 A. The Body of the Matrafs. 
 
 B. The Neck. 
 
 C. The Head. 
 
 PLATE SECOND. 
 
 FIG. I. A Glafs Alembic of one Piece. 
 
 A. The Cucurbite 
 
 B. The Head. 
 
 C. The Aperture in the Head. 
 
 D. Its Stopple. 
 
 . The Mouth of the Cucurbite. 
 
 VOL. I. EC
 
 4 i8 EXPLANATION. 
 
 F I G. JI. A PtUcan. 
 
 A. The Cucurbitc. 
 
 B. The Head. 
 
 C. 7"he Aperture in the Head, with its Stopple, 
 
 D. D. The two curved Spoutr. 
 
 FIG. III. A Row of Aludeli* 
 
 F I G. IV. A Rttart. 
 
 A. Its Bowl. 
 
 B. Its Neck. 
 
 FIG. V. An Englljk Retort. 
 
 PLATE THIRD. 
 
 FIG. I. A Reverberating Furnace. 
 
 A. The Afh-hole Door. 
 
 B. The Fire-place D< or. 
 
 C. C. C. C. Regifters. 
 
 D. The Dome, or Reverberator)'. 
 
 E. The Conical Funnel. 
 
 F. The Retort in the Furnace. 
 
 G. The Receiver. 
 
 H. H. Iron Bars to fuftain the Retort. 
 
 FIG. II. The Conical Funnel by itfelf. 
 
 F I G. III. Back View of a Muffle. 
 
 A. The bottom of the Muffle. 
 
 B. Its Arch. 
 
 C. C. C. Lateral apertures. 
 
 FIG. IV. Fore View of a Muffle. 
 F I G. V. A Melting Furnace. 
 
 A. A. The Bafe of the Furnace. 
 
 B. The Afli-hole. 
 
 C. D. The Grate for the Fire. 
 K. The Fire-place. 
 
 F,
 
 OF THE PLATES. 419 
 
 F. G. H. Curvature of the infide of the upper part of the 
 
 Fire-place. 
 I. The Shaft or Chimney. 
 
 PLATE FOURTH. 
 
 A Cupelling Furnace. 
 
 A. The Afti-hole. 
 
 B. B. Its Hiding Doors. 
 
 C. The Fire-place. 
 
 D. D. Its Hiding Doors. 
 
 E. F. Small apertures in the Sliders. 
 
 G. G. Holes for Bars to bear the Muffles. 
 
 H. H. H. Iron braces in the forepart of the Furnace, which 
 
 form grooves for the Doors of the Fire-place and Afh- 
 
 hole to flide in. 
 
 I. The upper pyramidal part of the Furnace. 
 K. An aperture therein for managing the Coals. 
 L. The opening at top. 
 M. The Pyramidal Cover. 
 N. The Chimney or End of the Shaft, on which the 
 
 conical Funnel may be fitted. 
 
 O. O. O. O. Handles for moving the fliding Doors. 
 P. P. Ears of the Pyramidal Cover. 
 
 ft. B. The Furnaces, as reprefented in the two laft 
 Plates, are not in due proportion to each other. The 
 Cupelling Furnace is much larger than it fhou!d be, with 
 refpeft to the Melting Furnace. Thefe dimensions arc 
 here given ir, only that all its parts might be more dif- 
 tinclly exprefted, than could have been done if we had 
 it lefs.
 
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