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ELEMENTS 
 
 Of the Art of 
 
 A flaying Metals. 
 
 In TWO PARTS. 
 
 The Firft containing 
 
 THE THEORY, 
 
 The Second 
 
 THE PRACTICE 
 
 i 
 
 of the faid Art. 
 
 THE WHOLE 
 
 Deduced from the true Properties and Nature of 
 Fossils; confirmed by the moft accurate 
 and unqueftionable Experiments, explained in a 
 natural Order, and with the utmoft Clearnefs. 
 
 By JOHN ANDREW CRAMER , M. D. 
 
 Translated from the Latin. 
 
 Illuft rated with COPPEji PLATES. 
 
 To which are added, 
 
 Several Notes and Ohfervations not in the Original, 
 particularly Ufeful to the Engiijh Reader. 
 
 With an Appendix, containing a List of the 
 chief Authors that have been published in Engiijh 
 upon Minerals and Metals. 
 
 LONDON, 
 
 Printed for Tho. Woodward at the Half-Moon between 
 the Temple-Gates, and C. Davis in Pater-no fler Row, 
 Printers to the Royal Society. MDCC XLI, 
 
<»*■ 
 
To the Honourable 
 
 JOHN WIN'fHROP Efq; ' 
 
 Fellow of the Royal Society. 
 
 .9 I R, 
 
 I Beg Leave to make this Addrefs to 
 you in Coniideration of thofe ex-- 
 cellent Virtues and rare Accompliih- 
 ments, with which you are endowed 
 both as a Gentleman and a Scholar. 
 Your great Knowledge of the true and 
 moll fecret Branches of Philofophy, 
 which has been for many Generations 
 handed down in your honourable Fa- 
 mily ; your profound Skill in all mi- 
 neral Affairs, particularly in Metallurgy, 
 which you have likewife inherited from 
 your noble and truly learned Anceftors, 
 of which you have given ample Proofs 
 by thofe curious Collections of American 
 Minerals , wherewith you have enriched 
 the Mufeums both of the Royal Society , 
 of which you are an illuftrious Orna- 
 
 A ment 
 
DEDICATION. 
 
 <ment as well as worthy Member, and 
 of their learned and moft eminent Pre- 
 iident the Honourable Sir Ham Sloane 
 Baronet : Your perfonal Acquaintance 
 with our ingenious Latin Author Dr. 
 Cramer , who cannot but greatly ap- 
 prove of my dedicating to you a Tranf- 
 lation of his excellent Book on the doci- 
 maftic Art ; thefe, Sir, have been the 
 Motives, for which I could not more 
 juftiy, nor more judicioufly fhelter this 
 my new Performance under any other 
 Name, than yours. 
 
 However, Sir, I (hall always take it 
 as a lingular Favour done me, if you 
 v/ill be pleafed to accept this Tender of 
 my Refpedfc, as a Teftimony of the vaft 
 Eileem and lincere Friendfhip, where- 
 with I have the Honour to be, 
 
 SIR, 
 
 'Tour moji obedient. 
 
 And rnojl bumble Servant , 
 
 London, 
 
 May, 3, 1 / 41 * 
 
PREFACE. 
 
 J Shall in this compendious Work , give the 
 •* Reader the Elements of the Art of Affaying, 
 that is, that part of Che mi fry, which confifis in 
 a ftrifll Examination of Minerals , by Means of 
 a proper Apparatus. I have written this chiefly, 
 that it may be of ufe to fuch Lovers of Chemiftry 
 as apply themf elves to the Study of mineral 
 Matters . For this Reafon,fuppoJing that fome of 
 the fight eft and moft common chemical Preparati- 
 ons were in fome me afire known to the Reader , 
 I have been very Jhort about them , when 1 have 
 had Recourfe to them in the practical Part of 
 the docimaftical Art ; except perhaps in fome 
 Places, that required a more particular De-* 
 fcription, as being little taken notice of in the 
 common chemical procejfes . therefore, I thought 
 it proper, previoufly to give a Jhort and Jpecial 
 - Theory of this Art, that thofe who Jhould come 
 to the Procejfes, might already be acquainted 
 with certain f kings necejfary to be known ; that 
 by this Means the Mind might be more Qompleat - 
 ly inftrudled in the making of the Apparatus, 
 and the dift'erent Manners of proceeding be more 
 eajily underftood . I have begun this fheory by 
 an Explication of the lefts compound Objedls of 
 the Art, that theje being found pure, might be 
 diftinguifhed by their outward Form , or by the 
 
 A z jtightefi 
 
PREFACE. 
 
 flight eft Trial, efpecially in the Fire. The fimple 
 Stones have rendered this Matter the moji difficult : 
 For almoft all Authors have fettled the different 
 Claffes of them only from their Figure , Tranjpa- 
 rency , Colour , &c. which Method , however , 
 can be of little Service for our Purpofe , and 
 even in general. Thence it is, that there are 
 Exceptions in every one of thefe Claffes, on account 
 of fome ReJ'emblance with regard to the Particu- 
 lars jujl mentioned : So that Stones , which are 
 called by Jome general Name , do not always re ^ 
 femble each other as to the other Char aSeri flicks , 
 even the more effential, which for this Reafon 
 ought not to be negle&ed upon any Account. And 
 as it is no jmall Help towards a folid Knowledge 
 of compound Miner a Is , to know the AS ion of the 
 fimple Ones upon each other , provided one has a 
 Regard to the Conditions requifte in every Cafe, 
 and no unfeafonable FiBions are admitted ; I 
 have for this Reafon explained the Virtues of the 
 Menftn'a in the jecond Chapter . In the mean 
 
 Time, let none expect here to have this Matter 
 compleatly treated , I mean , as far as it is known 
 from the Experiments hitherto made 5 becaufe it 
 cannot he exaSly known other wife than from the 
 Proceffes themfelves . Therefore y I have inferted 
 here very few of thefe , and even none but fuch 
 as might be confirmed by the eafieft Trial. Had 
 1 done >otherwifie, I mu ft have fiuppofed that 
 many Things were already known to the Reader , 
 which are familiar only to experienced Artificers , 
 to whom it would have been a nfielejs Trouble to 
 propofe them. 1 have, for the fame Purpofe, given 
 a Defcription of the Infiruments , 
 
PREFACE. 
 
 It is eafy to conceive, that it has not fieri in 
 my Power to mention all compound Minerals , 
 on Account of the numberlefs Differences pro- 
 ceeding from their various ^ parities , Propor- 
 tions , , and Compo fit ions. Wherefore , I would 
 
 have the Phings which I have f aid on thefe Mat- 
 ters , confidered only as a Specimen , which , $ 03 $- 
 ever, may be very ifeful , even heceffary to 
 
 young Beginners . 
 
 I have added a floor f Defer iptvdh of the flfprks 
 which are chief y and firiBly docimaflical, to 
 which I have annexed Explanations erf the Perms. 
 P hen follows a Jhort Account of the EffeBs, and 
 of the. Utilities refulting from them in fever al 
 Arts and Sciences, as far as thefe P kings can be 
 under flood here. Phis is what I had to fay .con- 
 cerning the Order I have prepofed to tnyfelf In 
 treating this theoretical Part . 
 
 But , as I have, for floor tnefs Sakefeldom quoted 
 any Authors in this Work , I Jh all here .tent' n 
 in getter al thofe from whom I have borrowed . ; 
 though an indefatigable Labour, the clofefl In - 
 fpeBion, and Hands that were not afraid of the 
 Blacknefs of Charcoal, have indeed been my 
 chief Maflers in this Art. As to the Pheory of 
 it. Dr . Stahl, has in a clear Manner, given ns the 
 Principles thereof in many • of his Writings . 
 Dr. Henkel has given us InftruBicns about com- 
 pound Minerals, and chiefly about metallick 
 Ores, cfpeciaily in his Pyritology. Mr. Erker, 
 in his Preatife written in German, called 
 probtr415tftlj, and Agrieola in his P redtife De re 
 metallica. Lib. VII. have given us the Proceffes 
 themfelves, to which Modeftinus Pachfkis has 
 added fome few Phings of his own . As to the 
 ether Authors, they have borrowed all their Ma- 
 
 A 3 terials 
 
PREFACE. 
 
 ierials from thofe above-mentioned, or have not- 
 been made ufe of by nte, becaufe I knew them not . 
 
 If the Reader approves of this Work , he may 
 expedl fome others, that will perhaps be more 
 elaborate , 
 
 ADDENDA 
 
ADDENDA to the NOLES. 
 
 § 1 88. Note , '"”g r ~*Obacco-pipe Clay, p ii, Brick Du ft, p. i. Stur - 
 bridge Clay alone,* or Sturbridge Clay, p. ii, 
 Windfor Loam, p. i, will make very good Tefts to roaft Ores in. 
 
 §198 Note , Windfor Loam alone, or Sturbridge Clay alone, will 
 make very good Muffles : But the beft are made of Sturbridge Clay, 
 p. ii, and old Muffles, or Melting Pots, made of Sturbridge Clay, 
 which have been ufed in the Fire, beat to fine Powder, p. i, and 
 mixt. 
 
 § 209. Note , A clean "Florence Wine Flalk will ferve upon Occafion. 
 
 § 243. Add, at the End, this Note. Therefore the Iron Tower, 
 mentioned p, 88, is more fafe, becaufe the Groove at top may 
 be filled with Water, or Lute mixt very thin with Water, which 
 will effe&ually hinder any Air or Smoke from getting through. 
 
 Page 373, Line 14, add this Note. The Cauftick Alcaline Salt here 
 mentioned to be made of Soap Lees and Lime, is commonly 
 known by the Name of Lapis Infemalis, the Cauftick fo generally 
 ufed by Surgeons. 
 
 ADDENDA to the L I S T of 
 ENGLISH BOOKS. 
 
 Page 452, after Line 11, infert, 
 
 Pyrotechnical Difcourfes. 
 
 I. An experimental Confirmation of Chymical Philofophy, 
 by John Kunkel. 
 
 II. A fflort Difcourfe on the Original of Metallick Veins; by 
 Geo. Em. Stahl. 
 
 III. The Grounds of Pyrotechnical Metallurgy, and Metallick 
 Eftaying ; by John Chrifl. Fritfchius. 
 
 London 1705. in Odtavo. 
 
 Thefe Treatifes are faid to be tranflated from the Latin by Mr. John 
 Moult Chemift; but there being in the Original many Sentences of 
 German interfperfed, he hath left them untranflated, probably not 
 underftanding that Language. 
 
T H IE Reader is defired to make the following Corre&ions with a Pea 
 before he reads the Book over. 
 
 PARTI. 
 
 Page 7. line 26. for Nitrvm read Natrum. P. 2f, 1 . 15, for melting read 
 Solution. P. 26, 1. 17, for Of pure or oily Sulphurs, r. Of pure Sulphurs ous 
 or Oily Bodies- P.29, 1 . 25, fox already r. Alkali. P. 40, 1 . 4, after £>ldf 5 ' 
 <£>311 infert in Er.ghjb Sandiver. P.42, 1 .x 2, for Glafs-Gall • r. Sandi<ver ; 
 and wherever it occurs. P. 48, J. 24, for make r. examine. P. 52, 
 !. 20. for Cup r.Tefl. P. 59, 1 . ult. fox take the Apes out r. cuf the Apes cut 
 
 •with a Knife. P. 70, 1 . 27, for Plat XI. r. Plat. II. P. 75, 1 . 2q, for 
 
 by means of Precipitate of Sulphur r. precipitated by means of Sulphur. P. 82, 
 J. 36, for its lower Side — upper r. the bottom — top. P.85, 1 - 8 , for Depth r. 
 Width. P.88, in the Note 1 . uit. for (c) r. (e) for 2 r. 4. P. 92, 1 . 14, 
 for lower r. Tower] dele ’within. P. ioi, L ult. for ( d) r. (f). P. 102, 
 I. 3, for (f) r. (dj. P. 116, 1 . 22, dele mingled. P. 119, 1. penult, for 
 
 Load- r. Touch -Stone. P. 130, 1.23, for the Flower r. the Mineral. P. 134. 
 
 J. 19, for Mines r. Ores. P. 151, 1 . 4, for ’with r. upon. Ibid. 1 . 31, for 
 Vitrean r.’vitrefcent. Ibid. 1 . ult. in the Note for Ore r. or. P.154, 1*29, fot 
 Mines r. Ores. P. 162, 1-25, for Flower r. Powder. P. 164, 1 . 11, after 
 cleft infert that will bear a firong Fire. P.169, 1 . ult. del t tempered. P. 171, 
 J.' penult, fof Malenterue r. Melenteria. P. 176, 1 . 13, fur Suet r- Scot. 
 Jbid. 1 . 14, after yield infert this. P. 189, 1 . 10, for Aludulicr r. Aluduii, or. 
 P. 192,1. 18, for <§)d)la 5 Ibid. 1 . 27, for Fluidity r. Fufibility. 
 
 P. 199, !• 23, for Chemical r. Alchemical. 
 
 PART II. 
 
 P. 205, 1 . 6, for § 462 r. 4:25 1 . 7, dele and. P. 207, 1 . 2, for Funnel 
 y. Cone. P 215, 1 . 4, for as this DefeB is obfer’ved r. as feme Metal files 
 •when this DcfeSi is firji obferved, and before , &c. P. 2T7, 1 . 21 , for roafled r. 
 fmelttd P. 218, 1 . 16, infert add before a like Quantity. P. 226, 1 . 33, 
 for double and fey tuple r. Jixteen times the Weight. P, 227, 1 . 6, after Sur- 
 face) infest* rf the juft melted. Metal. Ibid. 1 . 7, dele like melted Metal. P.239. 
 I.3, for boiled r. refined. P. 242, I. 8, for Proc. IV. r. VI. P. 243, 1 . 7. 
 for of equal Value with r. taken for. P. 252, I. antepenult, for aggravate d with r. 
 aggregated to. P- 258, 1 . 15, for fixt r. firji. P. 263, 1 . 7, for put r into 
 r. put into it. P. 269, 1 . 2, for temper r. Allay. P. 280, 1 . 16, for Fire 
 j. Forge. P. 281, 1 . 7, for fluid r. fujibU. P. 288, 1 . 35, for alone r. along, 
 P.290, 1 . 9, for Capper r. Iron. P. 291, 1 . rg, fur Furnace r. Muffle 
 P.29&J. tilt.' fur larger r - layer P. 298, 1 . 17, for they lie hidden in this Manner 
 y. Bodies of this Nature he hid. P. 310, 1 . to, for they r. fucb j dele fucb 
 after fetched P.343, 1 . penult, for wears out r. cleaves. P. 352, 1 . antepenult* 
 
 forcharge r. change. P. 373, 1 . 13, f r Trition r. Trituration. P. 395, J. 14, 
 for Inflammation r- Deflagration. P. 406, I. §, for Arfenick r. Vitriol. P.42S, 
 J. 22, for Funnel r. Chimney. P. 429, 1 . 28 for terminated r. arched. Ibid. 
 1 . 29, dele by the Arch. 
 
 Additions to the INDEX. 
 
 Calx Caffii 445 Minerals, proper, 125 
 
 Ingot, an, 72 improper, ibid. 
 
 Iron melted with Pit-Coal, 347 ———accidental, ibid. 
 
 Lapis Lazuli 157 Sandiver, 4?. 
 
 Directions to the Bookbinder. 
 
 Place all the Plates in Order after Page 470. 
 
 TABLE 
 
TABLE 
 
 Of the Chapters and Ti'tles of the 
 theoretical Part of the Art of Affaying. 
 
 Chap. I. /'"'vF the Definition and Objedl of Affaying 
 Av page i 
 
 I. Of Metals. 2 
 
 II. Of Semi-metals* 
 
 III. Of Salts. 
 
 IV. Of Sulphur. 7 
 
 V. Of Stones and Earths. - 8 
 
 Chap. II. Of the docimaftical Menjlrua , and the Pre- 
 parations of them. 14 
 
 I. Of Metals and their Products , confidered 
 
 as Menftrua. * ibid. 
 
 II. Of Semi-metals , confidered as Menftrua*. 
 
 22 
 
 III. Of pure Sulphureous or oily Bodies , confi- 
 dered as Menftrua. 2 6 
 
 IV. Of Salts , confidered as Menftrua 28 
 
 V. Of Sulphur , confidered as a Menftruum. 
 
 4 *. 
 
 VI. Of Cements. 4 6 
 
 VII. Of the fimpler and reductive Fluxes, 48 
 
 Chap. III. Of docimaftical Utenfils. ^2 
 
 I. Of Veffels. ibid, 
 
 II . Of Furnaces , 
 
 III. Of the other Utenfils of J faying* 95 
 
 Chap, 
 
 
Table of the Chapters, &c. 
 
 Chap. IV. Of compound Minerals and of Ores. 123 
 I Of Sulphur and fulphureous Minerals . 1 2 6 
 II. Of Arfenkk and arfenical Minerals . 129 
 
 III. Of Ores in general . 132 
 
 IV. Of Iron , and its Ores. 136 
 
 1 V. Of Copper , audits Ores. 142 
 
 VI. Of Lead) and its Ores. 147 
 
 VII. Of Lin, and its Ores. 149 
 
 VIII. Of Silver, and its Ores. 1.52 
 
 IX. Of Gold , its Ores. 157 
 
 X. 0 / Mercury , f/j On?. 159 
 
 XI. Of the Regulus of Antimony, and its 
 
 Ore . 1 6 1 
 
 XII. Of Bifmuth, and its Ore. ibid. 
 
 XIII. Of and its Ore. 163 
 
 XIV. Of Vitriol , and vitriolick Minerals . 
 
 167 
 
 XV. 0/ Allom, and the Minerals out of 
 
 which it is extracted. 1 7 2 
 
 XVI. Of common Salt, and the Methods by 
 
 which it is obtained . 1 74 
 
 XVII. Of Borax, and its Origin. 176 
 
 XVIII. Of Nitre, and its Matrix and Gene- 
 ration. 177 
 
 Chap. V. Of docimaflical Operations. 182 
 
 Chap.VI. Of the Effects and Ufe of the Art of A flay- 
 ing. 198 
 
 DOC I- 
 
r 
 
 docimasia: 
 
 OR THE 
 
 ART of ASSAYING 
 
 METALS. 
 
 PART the First, 
 
 Being the Theory of ASSAYING. 
 
 CHAP. I. 
 
 Of the Definition and ObjeB of Assaying. 
 
 z. A S SAYING* is the Art of Separating 
 /% Metals , Semi-Metals , Sulphurs , and Aff- 
 
 j \ from each other, and from 
 
 other Bodies mix’d with them, fo that it 
 may appear, what Quantity there was originally of 
 each in the Body under Tryal, or what Benefit may 
 be reaped from the extracting of it. 
 
 2. All Minerals are the Objects of this Art: For 
 the Bodies aferefaid being feldom found naturally 
 pure, and under their true Form, but molt common- 
 ly mix’d and confounded with each other a thoufand 
 different Ways, and with many kinds of Earths and 
 Stones *, it is proper that the Workman Fnouid know 
 
 * A Corruption by the Workmen of the Word Ejfafing, derived 
 from the French EJfxyer, to try. 
 
 B 
 
 the 
 
2 The Art of 
 
 the Nature of all thefe Things, to be able to deter- 
 mine, what is requifite for the Separation of them. 
 
 3. I fhall, with the moft renowned Dr. Boer - 
 haave *, call Minerals and Foffils natural Bodies, 
 formed in the Bowels of the Earth, or in its Surface, 
 and whofe Frame is fo very fimple, that no Eye, tho* 
 ever fo fharp, has been able even with the beft Micro- 
 fcopes hitherto to difcover in them any Variety, be- 
 tween the Parts containing, and the Things therein 
 contained •, but a perfeCt Likenefs and Affinity of the 
 Parts with the Whole : Though it is known that in 
 moft of thefe a Concurrence of fluid and folid Parti- 
 cles hath been effected by certain Mixtures. 
 
 Corollary. He therefore that attempts to give a ra- 
 tional Account of the Art of Eflaying, ought previ- 
 oufly to give fuch a Defcription of the fimpler Species 
 of Minerals which enter into the Compofition of the 
 Concretes, as may be taken from their external Form, 
 from their being (imply put into the Fire, and from 
 other (lighter Experiments hereafter to be mentioned. 
 
 4. All Minerals hitherto known, may be referred 
 to five Gaffes, viz. Metals, Semi-Metals, Salts, Sul- 
 phurs, Stones and Earths. 
 
 I. 0/ Metals. 
 
 5. Metals , when pure, are Bodies extremely pon- 
 derous, fufible by feveral Degrees of Fire, folid in 
 the natural Heat of the Atmofphere, apt to be ex- 
 tended every way with the Hammer, and of the ut- 
 moft Opacity. They are fix in number, viz. Gold, 
 Silver, Copper, Lead, Tin, andiron. 
 
 6. Gold, Sol, whofe Mark is (Q) has all the Cha- 
 radterifticks (§5.) of Metals in their utmofl Perfe- 
 ction, It lofes between T C and of its Weight, in 
 pure diftilled Water. Though ever fo long kept in 
 a State of Fufion, and in the greateft Fire, it lofes 
 nothing of its Subflance *, as it is of a moft fix’d Na- 
 ture. It is infinitely malleable j it gives no Sound 
 
 * Eiem. Chem. Vol. I. p, 30, 
 
 X 
 
 when 
 
Assaying Metals. 5 
 
 when (truck ; in the Fire it no fooner whitens, but it 
 melts*, and then looks of a Sea-green at the Surface. 
 Aqua forth has no Power on it. Its diftinguifhing 
 Colour is yellow. 
 
 Sc hoi ion. 'The Operations hereafter to he made upon 
 Gold , and which I fuppofe are as yet unknown to the Rea- 
 der , will give him a more ex aft Idea of this Metal . I may 
 fay the fame of the other Metals . 
 
 7. Silver, Luna (])) lofes Tr or M of its weight in 
 Water: In Fire it is as fix’d as Gold, and melts in al- 
 molt the fame heat. Next to Gold it is infinitely mal- 
 leable, and eafy to be bent. It refills the belt Aqua 
 Regis , and is of the fineft fhining white. 
 
 8. Copper ($) Venus , lofes between 4 and ~ of its 
 weight in the fame Water, It is not very fix’d in 
 Fire, but lofes a great Part of its Subfiance, in Ex- 
 
 * halation and Drofs. It is likewife malleable, but 
 much lefs than the foregoing. It gives a loud Sound, 
 looks of a deep yellow, is not fufible but by a great 
 Heat, and no fooner begins to whiten, but tinges the 
 Fire with a moft beautiful blueifii green. All Salts, 
 and Things containing Salts, corrode it, when ap- 
 plied to it, in which cafe it aftumes a great Variety of 
 Colours, efpecialiy the fineft green or blue. 
 
 Sc hoi ion. Foftils are here faid by me to be turned into 
 Scoriae or Drofs , if when expofed to the Fire , they affuine 
 the Form of Glafs ; a brittle Body , fufble and fx'd in 
 Fire , and indijfoluble by Water . 
 
 9. Lead (b) Saturnus , lofes between t t _ and JLof 
 its weight in Water. It melts long before it reddens. 
 It is not fix’d, but lofes much of its Subftance by Eva- 
 poration in a great Fire, and according to the Degree 
 of Heat, turns entirely into a dufty or a vicrefcenc 
 Drofs, of a yellowifh Colour, called Litharge (Li- 
 thargyrium.) It is very tenacious, and the fofteft of 
 Metals. It gives hardly any Sound under the Ham- 
 mer, and is of a bluifh white Colour. 
 
 10. Tin, (2|_), Jupiter , is the lighted of all Metals. 
 It lofes y of its weight in Water. It is not of a 
 fix’d Nature, but melts in a mild Fire, long before 
 
 E 2 it 
 
4 The A r t of 
 
 it becomes red hot. It in a fhort Time, partly eva- 
 porates into Smoak, and partly becomes a Calx . ft 
 is lefs malleable than the foregoing, tho’ not very 
 hard : If bent, it makes a crackling Noife, its Colour 
 is much like that of Silver.- 
 
 11. Iron, (<?) Mars , lofes between J T and -J. of its 
 weight in Water. It is extremely fix’d in Fire, which 
 mult be in its higheft Degree to melt it : When in Fu- 
 fion, it lofes a confiderable Part of its Subftance it 
 fparkles, it diiTolves into a Glafs of a dark blue Co- 
 lour, and into fulphureous Vapours : It is the mod 
 rigid of Metals-, however, if it is not immediately 
 quenched upon being red hot, it is malleable enough, 
 it is of a watery Colour, and is attracted by the Load- 
 done. 
 
 12. Quick-Silver, (j£) Mercurius , though it has no 
 other metallic!; Quality but its Ponderoufnefs, yet it 
 is almoit univerfally reckoned a leventh Metal. It 
 lofes -L Part of its weight in Water. When pure, it 
 is ever fluid, even in the coldefl: Weather, and of 
 courfe not malleable. It has the brightnefs of Silver, 
 and is of the utmofl: Opacity, being refolved into 
 Fumes- by a middling Fire, it evaporates entirely, a 
 very few reddifh Grains like Sand excepted. Thefe 
 Vapours, however, being collected, return into the 
 fame Mercury as before. 
 
 Scholion I. "Thefe are the Charadleriftkks of the pureft 
 Metals , when feparate from each other. They therefore 
 are not good, when two or more of them are mix’d toge- 
 ther \ For Inft an ce, Copter , Silver , and Gold , when 
 melted together with Tin , lofe their malleability , change 
 their Colour , &c. 
 
 Scholion II. The fpecifick Gravities of Metals, cannot 
 be very exadlly . determined for they vary a fmall Mat- 
 ter ; fi'r ft, according to the different Heat of the Atmoft 
 phere , which expands Water and other Fluids infinitely 
 mere than it does [olid Bodies 5 and by that unequal Dimi- 
 nution of the weight , makes it impcffible to affign them a 
 con ft ant Proportion , unlefs the Heat be determined with 
 the great eft Exadinefs. Secondly, according Jo the feve- 
 
 ral 
 
Assaying Metals. 5 
 
 ral Degrees of Purenefs in the Water \ which Difference 
 is fometimes found' not tnconfiderable. Thirdly, Accord - 
 
 ' ing to the different Purenefs of the Metals : For there is 
 hardly any Metal found fo very pure, but what may ea- 
 fily be demonftrated to be mix'd with fome ethers. Fourth- 
 ly, According to the fever al weight of the Atmofphere it - 
 felf : Though the Effeffi of its Variations be not very consi- 
 derable. This accounts why there are as many different 
 fpecifick Gravities affigned to Metals, as there are Au- 
 thors that have fearched this Matter by Experiments. 
 However, unlefs the Metals be of a very great Impurity, 
 the Sum of all the Differences refulting from the faid 
 Gaufes, is not fuff dent to hinder any particular Metal to 
 be diftinguifhed from any ‘other by its fpecifick Weight. 
 
 II. 0/ Semi-Metals. 
 
 13. Thefe agree with the foregoing, except that 
 they have not near the fame Malleability, if even they 
 have any. They are as follow. 
 
 14. Zink, is a Body of a blueifh white Colour; 
 brittle and fomewhat tenacious ; of confequence fome- 
 what malleable, though much lefs than Metals. It 
 melts in a gentle Fire, foon after it fmoaks, and then 
 flicks to the Furnace in the Form of exceeding light 
 white Flowers. lira greater Fire it burns with a 
 Flame of the mod beautiful green Colour, which evi- 
 dently betrays an Abundance of Sulphur. 
 
 15. Bifmuth, Tin-Glafs, ' when broken, appears to 
 confift of frnall cubic Particles, and thefe again con fill: 
 of minute Lamina's applied to each other. It is more 
 brittle than the foregoing, but differs little external- 
 ly, except that it does not affume the blue Colour, but 
 looks rather of a fhining and very light yellow. 
 
 1 6 . Regains of Antimony, is extremely brittle. V^hen 
 perfectly cleanfed from Sulphur, it furpaffes the fore- 
 going in whitenefs: It requires a greater Fire to be 
 melted ; which renders iteafy to be diftinguifhed from 
 the two former. 
 
 17. There is among the Minerals, another Body, 
 which deferves to be claffed among the 'Semi-Metals, 
 
 B 3 on 
 
6 The Art of 
 
 on account of its vaft Affinity to them, viz. Arfenich 
 (oo). This, if perfedHy pure, muft be white; it 
 grows foft in the Fire, and then evaporates entirely 
 into a thick white Smoke, that has the unpleafant 
 fmeU of Garlick ; but when grown cold, it gathers 
 intoafolid, half tranfparent, ponderous, white body. 
 It is not inflammable. When expofed to the Air, it 
 aiTumes a fmall milk white Skin ; it may be reduced 
 into a Regulus , very much like Antimony, and im> 
 flammable. 
 
 Corollar. Some refer Arfenick to the Clafs of Sul- 
 phurs ; but very improperly, as it plainly appears 
 from the Comparifon of its Charafterifticks juft men- 
 tioned, with thofe of Sulphurs. 
 
 III. Of Salts. 
 
 1 8. Salts are Bodies diffoluble in Water, melting 
 or volatile in the Fire, but not inflammable. 
 
 19. Firft of all, there are two kinds of pure and 
 natural Salts among Minerals*, one neutral, the other 
 
 acid. 
 
 20. The neutral is of two Sorts; the firft is com- 
 mon Salt (0), Muria , which, if pure, is always of 
 the whiteft Colour. It is femipellucid, diffoives in 
 pure Water, thickens in a gentle Fire, appears to 
 confift of feveral tefiellated, cubical and hexaedrai 
 Cryftals, joined together in truncated Pyramids ; it 
 crackles very loud, when thrown into the Fire. 
 
 21. The other is called Nitre (0), which whendif* 
 folved in pure Water, and cryftallized, according to 
 Art, affumes a prifmatical hexaedrai Figure, termi- 
 nated by fmall pyramidical Columns of the fame Num- 
 ber of Angles. It is white, and nearly tranfparent. 
 In a jxire Fire, fuch as the Rays of the Sun colledled, 
 or in Veftels defended from any Fuel falling into them, 
 it grows liquid by a gentle Heat: In a great Fire, it 
 partly perfpires through the Veftels, and partly refolves 
 into a Smoke, which is the Nitre itfelf; but any in- 
 flammable Body being added to it, it burns with a ve- 
 
Assaying Metals. 7 
 
 ty great Noife, and with the Matter added, changes 
 in part into an Alkali . 
 
 22. There is alfo an acid Salt, called Vagum FoJJile 
 found in Vitriol, Sulphur, Allom, nay, almoft every 
 where: It is feldom pure, if ever; but adheres either 
 to Metals (and chiefly to Copper and Iron) or to cal- 
 careous Earths, more commonly to thofe that turn in- 
 to Glafs, nay to the very Flints ; or is mix’d with 
 inflammable Foflils. But what diftinguifhes it from 
 all others is, its being more ponderous and more fix’d 
 than all the other Acids that are known, which it 
 drives out of its Matrices , mix’d with pure Water, 
 it grows very warm, it mixes with common Sulphur , 
 accompanied with fat Matters of any kind. What 
 its Power upon Metals is, will be fhewn hereafter, in 
 our Chapter of Menftrua. 
 
 23. To this Clafs might perhaps be referred the 
 Acids of common Salt and Nitre. However, as they 
 can be extradled by Chemifts from thefe Salts only, it 
 is not very fure that they are found naturally any 
 where. 
 
 Corollar . It is a queftion whether there maybe found 
 naturally, any true and perfect Alkaline Salt, whe- 
 ther fix’d or volatile in the mineral Kingdom? The 
 former feems to be confirm’d by the Salt of the Spa 
 Waters, and by the Nitrum of the Ancients : Marble, 
 and Stones either fetid or eafy to be cleft, poflibly 
 contain the latter. But both Points require a more 
 accurate Examination. See Fr. Hoffjnan * and Henc- 
 kel f 
 
 IV. Of Sulphur. 
 
 24. Whatever is inflammable, is called among the 
 Chemifts by the general Name of Sulphur . You find 
 it in the mineral Kingdom, always mix’d with Acid, 
 (§ 22.) otherwife the pure inflammable Mineral, feems 
 not to differ from the vegetable and animal ; nor does 
 
 * Differtat. Phyfico-Chem. Lib. II. Obf. I. 
 
 f Traftatu de Appropriatione, pag. 126. n. 4. 
 
 B 4 
 
 it 
 
8 The Art of 
 
 it feem that there are two kinds of it in nature : In this 
 Cafe the whole Difference between the feveral kinds 
 of Sulphur , would confift only in their various Mix- 
 ture with heterogeneous Matters. As therefore Nature 
 hardly affords any pure inflammable Matter, this is 
 not the Place to treat of the feveral kinds of Sulphurs , 
 which are never without Mixture : Our Defign re- 
 quires, that we ihould mention thofe only that are of 
 the fimpier kind. 
 
 i 
 
 V. Of S tones and Earths. 
 
 25. Stones are Bodies not diffolvable by Water, not 
 malleable, not inflammable, of the molt fix’d Nature, 
 and perfectly coherent. 
 
 26. When they confift of minute impalpable Par- 
 ticles, little or not at all coherent, they are called 
 Earths. . 
 
 27. But when being vifible, palpable, and extreme- 
 ly fmall, they neverthelefs appear ftill minute Stones 
 heaped together, they are called Sand Gravel, and 
 
 kjrit. 
 
 28. Our Defign chiefly requires, that we fhould 
 fhew the Differences of Stones, refulting from their 
 different Changes in the Fire : Nor will it be needlefs 
 to point out iuch of their other Charadterifticks, as 
 are eafily apprehended by the Senfes. 
 
 29. Some of them will melt in the greateft Heat 
 of a Wind Furnace, and are faid to be of the vitrifying 
 Kind : To which Clafs they are referred. 
 
 N 5 1 . Schiftus , or cleaving Stone , which is a Stone 
 confiding of a heap of Laminas that cleave eafily; it 
 is opaque, very loft, mod commonly black, in which 
 Cafe it is harder, and goes by the Name of Slate, other- 
 wife it looks of a dark blue, or afh-colour. Thefe Stones 
 put in Veffels clofely fhut, fudain a moderate melting 
 Fire, without any Alteration ; when the Heat is in- 
 creafed, they are put in Fufion ; and then the fir ft 
 black kind of them turns into a clear black Glafs. But 
 fome of the other Species, are by the ftrongeft Fire 
 railed up into a Scum, infomuch that a fmall Quantity 
 
Assaying Metals. 9 
 
 of them will fill a large Veffel, and then turn into a 
 very fpongy and light Mafs, that fwims upon Water. 
 
 N° 2. Common Potter's Clay is heavy, and oi$a 
 whitifh blue Colour; in Water it foftens into a tena- 
 cious Pafte ; a middling Fire hardens it firft, and a 
 ftronger Fire at laid runs it into a Glafs of a dark 
 green Colour. 
 
 N° 3. The Boles and Terr& Sigillatce or fealed Earths , 
 have an Affinity (N° 2.) with the foregoing, but are 
 of a fatter Nature, and of different Colours. They 
 harden to fuch a Degree in a moderate melting Fire, ' 
 that they mod commonly give Sparkles, when ftruck 
 with a Flint ; in a ftronger Fire, they turn into 
 Glafs, partly folid and green, and partly fpungy and 
 light, (as N°. 1.) To this Clafs belong a few Earths 
 of the Nature of Marie, though not quite fo fat. 
 
 N° 4. Flint, which is a vaftly ponderous Stone, 
 when ftruck with a Steel gives very bright Sparkles, 
 which being examined with the Microfcope, prove 
 to b Sconce of melted Iron and Stone. It is infinite- 
 ly hard, and of a ‘great many Colours. It affumes a 
 multitude of different Names, according to the Varie- 
 ty .of its Colour, for the Beauty of which it is very 
 much valued, though in confideration of its Size it is 
 fometimes of no Price at all. If this Stone, either 
 in its natural Surface, or when broken, is very cutting 
 and full of Angles, it is called by the Miners Quartz : 
 Some of them are eafily put in Ftifion in a Wind Fur- 
 nace ; others refift the greateft Fire without hardly 
 any Alteration, and might be thought not to belong 
 to this Clafs; but by means of a lmall Quantity of 
 Salt, or fome other Menftruum, nay by means of the 
 Jllkali in the Coals they will melt in a naked Fire. 
 When they are only minute Flints like Grains, heap- 
 ed together, but not adhering to each other, they are 
 called Sand or Gravel. But when they ftick together, 
 though diftin&ly colledted, they are called a fandy 
 or gravelly Stone, which is of the fame Nature as the 
 Flint, and affumes in the Fire a Variety of Colours, 
 Forms, and Delicacy. 
 
 30. Lime - 
 
IO 
 
 The Art of 
 
 30. Limefiones conftitute another kind, which when 
 burnt in the greateft Fire, are fo changed as either to 
 foften in the Fire immediately, or to cleave into Lime 
 by adding Water to them. Of this Clafs are, 
 
 N° 1. Spathum , or Spaad, which is a foft Stone, and 
 will be render’d fo very brittle by the mildeft Fire, 
 in which it makes a gentle Crackling, that you may 
 reduce it into Dull between your Fingers. It varies 
 its Gravity, as it is more or lefs compact. It moft com- 
 monly confifts of rhomboidal , often of prifmatical, pa- 
 rallel, and oblong Parts, varioufly tranfparent, and 
 generally of a watery or milky Colour. 
 
 N° 2. Marbles , which are of a great many Co- 
 lours, and often of various Colours at once. Marble 
 is a hard Stone, moft commonly opaque: If, after ha- 
 ving been burnt in a great Fire, it is expofed in the 
 Air, or wet with Water, it generally cleaves with 
 great Violence into a thin limy Powder: But this ftill 
 has an Exception ; for there are Marbles extremely 
 neat and fine, which, in a Fire not over-violent, turn 
 into an opaque kind of Glafs, but not at all into 
 Lime. 
 
 N° 3. Stalactites^ or Drop-Stones , which is a light foft 
 Stone commonly of a white or grey Colour, therefore 
 always calcareous, and will always burn into Lime. 
 It feldom proves of another Nature. 
 
 31. Finally, there are Stones which in the greateft 
 common Fire, either do not change at all, or at leaft 
 are never melted, nor reduced into Lime by being 
 wet : Whence they are very properly called Apyri , or 
 fuch whereon the Fire hath no Effetft. 
 
 N° i. Chalk deferves the firft Rank among thefe, 
 as it fuffers no Alteration, if pure, not even in the 
 the Focus of a Burning-glafs. It is light, white, foft, 
 and porous. It tranfmits Water through it, and fer- 
 ments with all Acids, in which it alfo diflolves. It is 
 not fiit, but rough to the Touch. 
 
 N° 2. The chalky and impure Maries come next : To 
 their Clafs muft be referred the Ferra Fripolitana , or 
 * Tripoly , which is like Chalk, but lighter, and feels fof- 
 
 ter* 
 
Assaying Metals, ii 
 
 ter. It is found yellow, white, red, and grey; and 
 hardens in the ftrongeft Fire to fuch a Degree, as to 
 give fparkles with a Steel. 
 
 N° 3. AJbeflus , a Stone confiding of rigid and 
 ftringy Fibres woven together, and cutting each other 
 acrofs. It varies very much as to its weight. It fcarce 
 changes in the greateft Fire, except that it commonly 
 turns white, and becomes harder than before. There 
 is a kind of very light AJbeftus, called Suber Mont a- 
 num , which melts into a black kind of Glafs *. 
 
 N°4. Amianthus , or Earth-Flax ^ which is little dif- 
 ferent from the foregoing, except that its Fibres are pli- 
 ant and parallel ; fo that the Virtuofi make Thread, 
 Cloth, and Paper, with a certain kind of it. Itfuftains 
 a moderate Fire without being altered : But when it is 
 expofed to the greateft Fire, it either partly or wholly 
 iofes its pliantnefs : This is chiefly true of that kind of 
 Amianthus , which is friable between the Fingers, and is 
 falfly called Alumen plumofum : ,For it hardens in Fire 
 to fuch a Degree, as to ftrike Light with a Steel *f\ 
 
 N° 5. Ollaris ] Lebetum Lapis, Pot-Stone a , which 
 feels exadtly like hard Soap: It is moft commonly 
 fomewhat tranfparent ; foft, ponderous enough, and 
 very eaftly carved with a Knife. In the Fire, it turns 
 white, and hardens to fuch a Degree as not to be fur- 
 pafled by Flints, and to ftrike a Light immediately. 
 But it cleaves in the greateft Fire. A few kinds of 
 Tobacco-pipe Clay belong to the fame Clafs. 
 
 N° 6 , Talck , it is a Stone confiding of fmall Scales, 
 lying one upon another: It has a foapy feel: It is 
 fometimes tenacious; refifts a great Fire, and fuffers 
 there no other Alteration, but its becoming more brittle, 
 N°7. Mica, Glimmer or Glift, it is of the fore- 
 going kind ; fhining, and brighter, black, gold or 
 filver colour’d ; nor can it be conquered by either Fire 
 or Water. 
 
 * A. Henckel. De Lapidum origine, p 58 , f Idem, ibid, 
 
 pag. 55* t Carol. Linnaei Syftema Naturae, Tab. I. 
 
 a It may be fo call-cd, becaufe in Switzerland they turn Tots and Ket- 
 tles out of it, that will bear the Tire to boil Meat in them. 
 
 Many 
 
1 2 The Art of 
 
 Many kinds of thefe Stones, which feel like Soap 
 before they are burnt, become fomewhat rough by the 
 Force of Fire. 
 
 32. There are Fill many other kinds of Stones, 
 whofe Differences are infinite as to their Figure, Co- 
 lour, Hardnefs, Tranfparency, and Weight. I fhall 
 forbear to enumerate them •, my chief Purpofe requi- 
 ring, that I fhould only defcribe here the mod com- 
 mon of them, and thofe in which the other Minerals 
 moft commonly lye hidden. Befides, there are many 
 Sorts of Stones that are Mixtures of feveral others, 
 which it is not cur Bufmefs here to mention, as we treat 
 only of thofe that are fimple. As for the red, what- 
 ever other Stones are found beddes thefe, may be re- 
 ferred to one of the hitherto mentioned Claffes ; though 
 they pofdbJy have other Charaderifticks belonging to 
 them in a more fpecifick Manner. 
 
 33. However, I by no means believe, that what I 
 have hitherto faid, is fufficient for a perfed Know- 
 ledge of all the Stones which Nature affords : For I 
 have done only what I could, not what I would; and 
 fhould any one fay fomething better on the Subjed, I 
 would gladly lay hold of it. There is certainly fuch 
 an infinite Combination of Forms and Proportions in 
 the Mixture of Stones among themfelves, that no Eye 
 is capable, ’even with the Help of Indruments, to di- 
 dinguifh them accurately. Their Figures, Colours, 
 and other the like outward Qualities, arc feldom Cen- 
 dant, as they depend upon a Multitude of Caufes, not 
 belonging to the Matter of the Stone itfelf : So that he 
 may eafily be deceived, who forms any Judgment or 
 Diftindion from them. That Method is better 
 grounded, which makes the Trials in feveral Degrees 
 of Fire, fird in clofe Veffels perfedly clean, and able 
 to re fid Fire, and then in open Veflels, and in a 
 Wind Furnace, or a Smith’s Forge. 
 
 34. Who can deny that there are many Genus's and 
 Species of fimple Minerals, befides thofe already 
 mentioned? It is not to be doubted, but that there 
 are in the Nature of Things, Salts, and perhaps Me- 
 tals, 
 
Assaying Metals, i j 
 
 fals, and Semi-Metals, different From thofe above- 
 mentioned, nay perhaps Minerals that could not be 
 referred to any of thefe Gaffes : Nor can we deny it, 
 wfien we confider. that Nitre, which, as far as we 
 know, was a Secret to the Ancients, has been found 
 out but a few Ages ago. 
 
 Coroll. As the Art of A flaying teaches the Nature 
 and Difference of fimple Minerals, and the Mixture 
 of thofe compounded, its ufefulnefs is evident for the 
 compleating natural Hiftory. Nor is it lefs ufeful 
 and neceffary in Metallurgy. For as no Man can, 
 pals any certain Judgment upon the Nature of Mine- 
 rals, from the bare Infpe&ion of them, he muft for 
 that purpofe have Recourfe to docimaftical Experi- 
 ments. Let us take, for an Example, fome Lead 
 Ore, of a yellowifh green Colour, and mix’d with 
 Cryftals refembling Spar, fhooting like Nitre, which, 
 as far as I know, is found in one Place only. Let us 
 liippofe a Man to have feen Lead Ore of all forts, 
 this very rare one excepted, the bare Infpedtion, the 
 Figure, Colour, and Weight of it, will never make 
 him find out, that this Ore is very rich in Lead*, 
 which any Man fkilled in thefe Things will confefs to 
 be true of many others. Ercker fpeaks of workers 
 of Mines, who had, with no final] Detriment, mi- 
 ftaken Ores of Tin for Ores of Iron *. 
 
 3 5. The Aim of docimaftical Operation is two- 
 fold •, viz. to know, firft y what kind and what quan- 
 tity of each Mineral is contained in the compounded 
 Subject *, fecondly , what kind and how much may be 
 extracted out of it, with fome Benefit. 
 
 Scholion. The Workers of Mines are often ??tifled by 
 the AJfayers , who make their Trials in fuch a Method , 
 and with fuch Additions , as can never be ufed in greater 
 Operations , on account of the vaft Expence and T rouble 
 which attend them. For when the Operation is under - 
 taken with that View , the Method of it ought to be fuch 
 as can be imitated and purfued in larger Works , or in the 
 
 * Vich Laz.. Erckers Brcblr, Buck, pa g. lao. 
 
 
 room 
 
14 7/fe A rt of 
 
 room thereof feme ether Method may be fubftituted equally 
 beneficial. 
 
 CHAP. II. 
 
 Of Docimajlical Menftrua, and the Preparation 
 of them. 
 
 3 6, BEFORE we treat of the Inftruments and 
 I# Veffds, and come to the Operations them- 
 felves, it is proper for us to fhew the Nature of thofe 
 Bodies, which are to be contained in thefe Veffels, 
 directed and applied by thefe Inftruments, and which 
 fhall act upon the Object of Allaying. 
 
 37. Thofe Bodies, which being applied to others 
 according to certain Rules, di Halve them fo as to ad- 
 here themfelves in a State of Divifion to the Particles 
 of the Body diffolved, and cannot feparate from them 
 again of their own accord, are called Menftrua . Thefe 
 are chiefly divided into dry, and moift *, which laft are 
 again fubdivided many ways : But this being mention- 
 ed in all the Writings of the Chemifts, we fhall pafs 
 it by in Silence, as we only treat of one Part of Che- 
 miftry : For we need only to explain in a fpecial Man- 
 ner, the Operations belonging to our prefent Pur- 
 pofe, and to acquaint the Reader with the Prepara- 
 tions of them. 
 
 Of Metals and their Produffs confidered as 
 Menftrua. 
 
 Of Lead. 
 
 38. See its Charadterifticks, Chap.l. §9. When 
 Lead is expofed to a moderate Fire in an earthen Vef- 
 fel, the Surface of it is immediately covered with a 
 thin tenacious Skin of Sconce , of different Colours: 
 When the Fire is increafed fo as to render the Vefiels 
 quite red hot, this Skin melts a little, and is thrown 
 
 to 
 
Assaying Metals. i y 
 
 to the Side of the Veffel, where it turns into Drofs cal- 
 led Litharge . Then the Lead feems to boil and 
 frnoak, and fmall Drops refembling the firft Sconce 
 are inceflantly produced, that fwim upon the Lead 
 like Oyl, and are continually thrown towards the 
 firft. If the Fire is kept at the fame Degree, the 
 whole Mafs of Lead at laft turns into Litharge. 
 
 39. If you put Copper into Lead thus fmoaking, 
 it caufes a much brifker Ebullition, and the Copper 
 as it were burfts, divides, and feems to become but 
 one homogeneous Mafs with the Lead, which Mafs is 
 brittle, and, when broken, its Surface, if there hath 
 been added about half as much Copper, will have 
 the Colour and Figure of a Piece of tempered Iron 
 or Steel. 
 
 40. Gold and Silver likewife melted with Lead, 
 become brittle, and Gold efpecially turns pale, by 
 the leaft Mixture of it. 
 
 41. Tin is melted with Lead, by a Fire not much 
 greater than what would melt both feverally : But fo 
 loon as the Fire is increafed fo as to make the Veftels 
 turn red, the Tin immediately rifes above the Lead, 
 like little whitifh dufty Hillocks *, fo that one unfkil- 
 led in thefe Matters would be apt to think that Coals 
 had fallen into the Metal : If they have been taken 
 but a little while out of the Fire, they look like burn- 
 ing Coals. Tin thus calcined, when grown cold, has 
 its Colour variegated with white yellow and red. 
 
 42. Lead, fo long as it keeps its metallick Form, 
 can never join with Iron, though urged with ever fo 
 great a Fire. 
 
 43. Semi-Metals are eafily melted with Lead by 
 Fire, and a great Quantity ol them deprives it of its 
 Malleability. 
 
 44. This Metal muft oftentimes be made into 
 fmall Grains, that it may be mix’d with the others, 
 and its exadl Weight be more eafily determined. 
 
 But this Comminution is heft made the dry way, in 
 the following Manner, which is called Granulation. 
 Put Lead in an iron Ladle, melt it on a gentle Fire ; 
 
 fo 
 
i6 The Art of 
 
 fo foon as it is perfectly liquid, pour it at once into a 
 wooden Veffel having a wooden Cover, or fome other 
 Veffel in which a Fluid may be very ftrongly fhaken, 
 without however any danger of its running out. But 
 let the Sides of the Veffel be well rubbed with Chalk 
 or Wax; then let it be thoroughly fhaken, fo that 
 the Lead agitated within, may dafh ftrongly againft 
 the Sides of the Veffel ; nor do you ceafe this Motion, 
 till it becomes folid : You will find the greater Part 
 of the Lead, divided into very fmall porous Grains. 
 Let then the Chalk that flicks to it be wafhed off; 
 thenfift the Grains, to make them equal, dry them, 
 and keep them from the Duff in a clean Veffel, for 
 the Ufes hereafter to be explained. 
 
 Scholion I. The Reafon of doing thus is this. There 
 are among Metals fome , as Lead , Tin, and Brafs , which 
 when ready to melt , are extremely brittle , like wetted 
 gravel. The Chalk wherewith the Infide is rubbed over , 
 gives the Surface a vaft reftfting Force , and preferves it 
 from burning. Now , if the melted Lead be fhaken and 
 dafhed againft the Sides of the Veffel in the Manner afore- 
 faid , the Minute it begins to become folid , the Mafs at that 
 Moment being of the utmoft Brittlenefs , is fhivered into a 
 minute Duft, which can hardly Fe obtained any otherwife 
 than by this manual Operation. 
 
 Scholion II. There pre Cautions to be taken. Firft, 
 Let the Lead not be melted by too great a Fire ; for this 
 occafions a thin Skin on the Surface , which though taken 
 away is immediately fucceeded by another , which mixing 
 with the Lead during the fhaking , hinders very much the 
 Succefs of the Operation , it being too tenacious. Secondly, 
 Let the Lead be fufficiently fluid ; left the Mafs , fo foon as 
 poured in , fhould wax cold before it might be broken to 
 pieces . 
 
 Corollary. It is then plain, that this Granulation 
 cannot be made with fuch Metals, as are more tena- 
 cious in proportion as they are nearer being melted ; 
 fuch as Gold, Silver, &c. 
 
 45. Lead, and all its Produdb, turn into Glafs by 
 a great Fire (§9, and 38.) 
 
 46. This 
 
Assaying Metals. 17 
 
 46. This Glafs or Litharge pounded together, and 
 melted with vitriricable Stones, (§ 29), makes them 
 turn into Glafs with a much lefs Fire than they would 
 have done by themfelves. If you add a fufficient 
 Quantity of Litharge, thefe Stones melt into a kind 
 of Glafs fo very attenuated, that it infenfibly perfpires 
 through the Veffels ; nay, it melts the Veffe Is them- 
 felves, when they yield not a free Paffage to it. 
 
 47. All Lime-Stones (§ 30), if ufed in the fame 
 Manner (§ 46.) and mix’d with Litharge, have the 
 fame Fate, but they require a much greater Quantity 
 of Litharge, to acquire the fame Degree of Fluidi- 
 ty, when melted. 
 
 48. Stones that keep unburnt in the Fire (§ 31.) 
 are more difficult to be changed, and unlefs fome me- 
 chanical Mixture is ufed, and a moderate Fire pre- 
 ferved a long while, the Litharge vanishes through 
 the Veifels that contain it, before it has perfectly 
 melted thefe Stones. 
 
 49. Among Metals, Litharge likewife facilitates 
 the Fufion of Copper and Iron by Fire, but at the 
 fame Time it confumes a confiderable Quantity of 
 them, and runs itfelf with them into Glafs, as is plain 
 (§46.) from what has been faid. But the Glafs of 
 Lead does not mix as much with thefe Metals before 
 they are deftroyed, as it does with the aforefaid Stones ; 
 but fwims about and upon them. 
 
 50. Tin and its Calx (§ 10, 41.) is with great Diffi- 
 culty vitrified by a M ixture of Litharge, for i t always 
 feparating from it, fwims upon it. But if it turns in- 
 to Glafs at laft, it preferves a certain Clamminefs, 
 not to be taken away except by a confiderable Addi- 
 tion of Litharge. The Vitrification of its Calx, is 
 in fome Degree promoted by Copper: Which being 
 added to, and melted together with it, makes it more 
 eafy to be conquered. 
 
 51. The melting of Gold and Silver is likewife ha- 
 ftened by Glafs of Lead (as §49.) and they lofe no- 
 thing by it. However, if Gold and Silver are very 
 frequently melted with Litharge, they at length prove 
 
 C to 
 
1 8 The Art of 
 
 to have loft a Trifle of their weight: Nor are they, 
 for all that, deftroyed of that Quantity, for it may, 
 by a plain Separation, be extracted again out of the 
 Litharge, and will then be found of the fame Nature 
 as before: As the Operations in our fecond Part will 
 fhew. 
 
 52. The melting of Semi-metals is alfo promoted 
 by a Mixture of Litharge-, and then it happens with 
 them as with lefs perfect Metals : Which is facilitated 
 by an Addition of Iron. 
 
 53. Therefore it is felf- evident of what great ufe 
 this Litharge is in roafting refractory Ores of Gold, 
 Silver, and Copper. For it melts any Stones and 
 Earths whatfoever, with more fwiftnefs, than it turns 
 Metals into Glafs, provided every thing be equally 
 and minutely mix*d. Then the Metal which is hea- 
 vier goes down through the Glafs, which is in a thin 
 Fluxion, and gathers into a Regulus , upon which a 
 few fmall earthy Sconce are fwimming. But there is 
 always a Part of the Metal deftroyed at the fame 
 Time : Or if it is Gold or Silver, a fmall Quantity 
 of it is detained in the Sconce . 
 
 54. But as the Litharge penetrates through any 
 Veflels whatever, and, while melting, rifes into a 
 Scum, and thus eafily overflows -, Aflayers never ufe 
 it alone, but communicate a Clamminefs to it, and 
 flx it by adding a certain proportionable Quantity of 
 Flints, Sand, Clay, &c. for they take of Powder of 
 calcined Flints, or of Sand one Part, of Litharge two 
 Parts, which they mix very exactly by pounding 
 them together ; to this they add Nitre or common 
 Salt, that the whole may melt more eafily they fhut 
 the Veflels, which rnuft be thick and folid, with a 
 fmall Cover cut clofe, left the Coals which are to re- 
 duce the Litharge into Lead, lliould fall into it, they 
 leave it thus melted for above a Quarter of an Hour 
 and more ; during which Operation they muft be ever 
 looking into the Afh-Hole of the Wind-Furnace, to 
 examine whether the Crucible holds the Glafs or no. 
 For it moft frequently happens, that it perfpires 
 
 through 
 
Assaying Metals. ic> 
 
 through the Crucible like Water, and falls down in 
 Drops into the Afh-hole: When you fee this, you 
 mult immediately take the Vefiels out of the Fire, if 
 you are not willing to lofe all. Having broken the 
 Crucible, you moil commonly find a fmall Regulus 
 of Lead, reduced by the Fatnefs of the Salt, or of 
 the impure Nitre : In the Middle is the Glafs of Lead, 
 which is to be feparated and kept for ufe, the faline 
 Cake which is at top mud be thrown away. 
 
 55. If you ufe Clay or Potter’s Earth, or the Ca* 
 put Mortuum of Vitriol walk’d, you make likewife 
 excellent Glafs wi:h Litharge ; only you are to take 
 care not to add too great a Quantity of thefe Things, 
 for when Litharge is too much faturated, it cannot 
 confume the Bodies to be feparated from the Metals. 
 The Glafs likewife becomes ufelefs, when Part of the 
 Litharge runs through the Vefiels. This Damage 
 proceeds either from the Crucible’s not being folid e- 
 nough, or from the mechanical Mixture’s having been 
 negledted. 
 
 56. Moreover, it is to be noted concerning Lead, 
 that its Vapour, if it touches even the bed Gold, ren- 
 ders it brittle. 
 
 Of Tin. 
 
 57. See the Defcription of it (§ 10.) Tin eafily 
 melts with Silver, Gold, and Copper ; but when 
 they are melted with it in equal or lefs Quantity, it 
 renders them extremely brittle; efpecially Silver, 
 which becomes as brittle as Glafs by the lead Mix- 
 ture of Tin. But if a much greater Quantity of it 
 enters into metallick Makes, thefe dill preferve fome 
 Pliantnefs : For indance, ten Parts of Tin, and one 
 
 i Part of Copper melted together, make a Mafs more 
 rigid than pure Tin, but which is dill fomewhat 
 tradfable: By this Artifice, they make Utenfils of 
 Tin that are much more durable. If you add to 
 i Copper ten Parts of Tin , and a little Brafs or 
 Zink together , this will produce a brittle and very 
 | fonorous Metal, fit for making of Bells and Cannons. 
 
 C 2 58. Lead 
 
20 
 
 The Art of 
 
 58. Lead is of ail Metals that which acquires lefs 
 Brittlenefs by being mix’d with Tin: Though it be- 
 comes fomewhat more rigid. 
 
 59. Filings of Iron, or very thin Lamina of it, 
 being prefently made red in the Crucible, if you pour 
 upon them the double Quantity of Tin, on a great 
 Fire, they will turn into a brittle white Regains , 
 yielding quickly to the Attraction of the Load-Stone. 
 And here you mult have a very quick Fire, left too 
 great a Quantity of Tin fhould be confumed. In or- 
 der to which, and for the quicker melting of the Iron, 
 it will be proper to add a Quantity of Argol, that 
 is the crude Tartar of Wine, and Glafs. 
 
 60. The Vapours of 'Tin are infinitely noxious to 
 Silver , Gold, and Copper •, as they render them brit- 
 tle : Nay, if you fprinkle ever fo little Tin in the Fire 
 where thefe Metals are to be put, the moft ductile 
 of them, being made red on fuch a Fire, becomes 
 fo very untradlable, that the leaft Touch of a Hammer 
 will make it fplit like Glafs. Therefore, if the fmalleft 
 Quantity of Tin fhould happen to fall into the Fire ; 
 the whole muft be taken out of it with great Care, and 
 the Fire be made once or twice ftronger *, that whatever 
 Part of Tin remains, may be entirely difti pared. 
 
 Of C o P P E R . 
 
 6 1. Copper melts together with Silver and Gold, 
 witnefs all our Coins and Utenfils, and makes them 
 harder j whereas they could hardly otherwife be ap- 
 plied to any ufe in common Life, on account of their 
 great Softnefs. 
 
 62. Copper put on the Fire with Iron, promotes 
 the melting of the latter: However it becomes itfelf 
 more rigid and more pale by this Mixture. But it 
 will be proper, in order to make this melting more 
 fuccefsful, to throw upon it as much Tartar and com- 
 mon Glafs, as would be neceftary to cover the Surface 
 of the whole Mafs. 
 
 Of 
 
21 
 
 Assaying Metals. 
 
 0/Gold W Silver. 
 
 63. Gold and Silver mutually melt with one ano- 
 ther, and are befides eafily mix’d with Iron. As to 
 their other Properties, I fhall refer you back to what 
 has already been faid. 
 
 Of Iron. 
 
 ба. See what was faid before. However, it is ob~ 
 fervable that Iron mull be extremely pure in thefe 
 Mixtures; for if it contains too much Sulphur , the 
 melting does not fueceed fo well ; and the Iron ga- 
 thers into a Regulus feparated from the other Metals. 
 
 Of Mercury. 
 
 65. Mercury mixes with Gold, Silver, Lead, Tin, 
 Zink, and Bifmuth *, but not quite fo eafily with Cop- 
 per. This melting is called Amalgamation. But 
 all thefe Amalgama's become white, and when a great 
 Quantity of Metal is diffolved in Mercury , they 
 thicken into a kind of Pafte. But the following 
 Conditions are required, for the quick and good Suc- 
 cefs of thefe Mixtures. 
 
 Firft , That the Metal be comminuted, which may 
 be done any way, provided there is no Alcali in the 
 Operation ; becaufe this either retards, or totally hin- 
 ders the Adlion of the Mercury. 
 
 Secondly , That a mechanical Mixture be employed 
 by grinding in a Mortar. 
 
 Thirdly , That the Heat be as great as the Mercury 
 can bear without being diffipated. 
 
 Fourthly , That the Surface of the Metal be very 
 clean, and above all free from all greafinefs. 
 
 бб. But there is a greater or lefs Quantity of the 
 faid Metals diffolved, according as the Conditions al- 
 ready mentioned are not wanting, and the Purenefs of 
 the Mercury is greater or lefs. 
 
 67. However, you muff take care, that a Part of 
 the diffolved Metal be fo perfe&ly attenuated by the 
 Mercury , that it may infinuate through the Pores of 
 £ Filtre, as Salt diffolved in Water. However it is 
 
 C 3 but 
 
it The Art of 
 
 but a very fmall Quantity that can be thus difiblved, 
 a certain one cannot be univerfally determined, fince 
 it mufi be found out by a very gentle Diilillation, in 
 Experiments made on purpofe. The other Part of 
 the difiblved Metal runs freely with the Mercury : 
 But if the Amalgama is drained through a Glove- 
 leather Purfe, the Metal is retained in it, imperfectly 
 difiblved, together with about an equal Quantity 
 of Mercury adhering. 
 
 68. Mercury has no Power on Iron and Regulus 
 of Antimony; or if it has any, it muft be exerted by 
 an Artifice which has been hitherto a Secret to us. 
 
 II. Of Semi - Metals, confidered as Menftrua. 
 
 Of Arsenic k. 
 
 69. Arfenick, the Defcription whereof was given 
 (§ 17.) well pounded and mix’d together with feveral 
 Earths, efpecially with fuch as are calcareous and not 
 to be affected by the Fire, being expofed to the Fire, 
 proves much more fixt than it is of itfelf. 
 
 70. If to the Mixture (§69.) is added a little Tar- 
 tar, and it be then lightly moiftened with Water, and 
 prefied down with fmall Plates of Iron interpofed 
 every where, in aVeflel able to refill the greateft Fire ; 
 and if finally, the Vefiel being well clofed with only 
 a lmall Aperture left to it, is expofed for fix or eight 
 Hours, firfl to a moderate Fire encreafed at lafl to the 
 hig’hefl Degree, fo that the Mafs within may be melt- 
 ed; the whole proves a white brittle Regulus of Iron, 
 not to be reduced to its former State, except by an 
 open Fire, continued very long. 
 
 71. If Copper is managed in the fame manner with 
 Arfenick, it acquires the fame whitenefs, and retains 
 in good part its Malleability : Efpecially, if it is once 
 or twice melted with 'Tartar and Borax , that the fu- 
 perfiuous Arfenick Hill inherent may be difiipated. 
 
 7 2. Tin and Arfenick mixt over the Fire, turn im- 
 mediately to A files, the Part of the Arfenick adhering 
 flrongly enough to the Tin. 
 
 ? 2. Lead 
 
Assaying Metals. 23 
 
 73. Lead mix’d with Arfenick is immediately and 
 partly carried away, in the Form of a thick Smoak, 
 the reft being a thin Glafs of a Saffron colour. 
 
 74. Silver is penetrated by xlrfenick applied in the 
 fame (§ 70.) manner, and lofes its Malleability ; but 
 it vanifhes away by a great Fire, in the Form of 
 Smoak. 
 
 75. Gold penetrated by Arfenick, becomes infinite- 
 ly brittle, it lofes its Colour, and then being fuddenly 
 thrown in a great Fire, Part of it is fublimed. 
 
 Scholion. Arfenick , on account of this Property, is cal- 
 led Sulphur rapax: Becaufe , by its Action excited with 
 Fire and Air , there is often a greater Quantity of Metals 
 raifed and fublimed in form of Flowers up the Furnaces , 
 than is collected in the very melting Pots of the Furnaces 
 themf elves. However , the folid Matter thus fublimed is 
 called Cadmia fornacum. 
 
 76. Finally, Arfenick is attracted with a different 
 Force by different Metals, and attracts them recipro- 
 cally. Of all Metals it abforbs Iron moft greedily, 
 and fucceffively Copper , Fin, Lead , and Silver. 
 Therefore all Metals may be freed of the Foulnefs of 
 Arfenick by Iron , but not fo well by Sconce of Iron , 
 unlefs the Fufion be made in an open Fire : For then 
 Scoriae may be ufefully imployed, becaufe though they 
 do not of themfelves abforb the Arfenick , they never- 
 thelefs being reduced to Iron , a 61 in the fame Man- 
 ner as Iron itfelf. Now we fhallfoon fhew, that they 
 may be reduced to it, by the means already mention- 
 ed. 
 
 Of Antimony, 
 
 77. The Regulus (§ 16.) of Antimony, when melt- 
 ed by a great Fire, proves totally volatile. In the 
 
 | Fire, it bubbles a 1 moft like Lead, and diftolves into a 
 kind of Giafs not very fix’d, while the reft vanifhes 
 inta Smoak. 
 
 78. The fame renders all Bodies hitherto known 
 | volatile. Gold on certain Conditions excepted. 
 
 C d. 
 
 79. When 
 
24 - The Art of 
 
 79. When pulverized not very fine, it turns into a 
 Calx in a moderate me) ting Fire, which Calx being 
 melted by a great Fire, turns entirely into a kind of 
 Glafs, which is of a dark red Colour, half transpa- 
 rent, and fufficiently hard. This Glafs has a greater 
 Efficacy upon Bodies, than Litharge ltfelf (§ 46. — 52.) 
 for it attenuates Stones of ail kinds, diffolves them, 
 and with a very ftrong open Fire carries them away 
 with it in the Air. 
 
 80. If this Glafs does not equally change all Me- 
 tals, it turns them into Scoria , and makes them vo- 
 latile, Gold alone excepted : Becaufe it is thereby 
 freed of all heterogeneous Matters, except of Silver 
 and <Tin 9 whoie Separation is more difficult to be ob- 
 
 A 
 
 tained that way •, you may therefore with Reafon 
 call it the Wolf and Devcurer not only of Metals, 
 but of almoft all Bodies. 
 
 81. However, this Acftion (§80.) of the reguline 
 Part of Antimony is greatly augmented, ifyouufeat 
 nrft a ftrong Fire with Veflfels well ciofed, or throw 
 upon it any kind of Fat whatever: For by thefe 
 means you hinder the Regulus of Antimony from evapo- 
 rating immediately, and its Virtue to deftroy Bodies 
 is of longer Duration ; fo that at lafb every thing va- 
 nishes, and is confumed by a ftrong and open Fire. 
 
 However, the Regains of Antimony unites as vari- 
 oufiy with different Metals, as was faid (§ 76.) Arfe- 
 nick did ; for it greedily incorporates with Iron , and 
 next with Copper , &c. 
 
 Coroll. Hence appears how near of kind Regulus of 
 Antimony is to Arfenick : For the whole Difference fee ms 
 t:o be, that Arfenick is fix’d in Antimony by a vitrifying 
 Earth. Whence it happens that when Antimony is 
 mix’d with Metals, it can hardly be confumed from 
 thence by Uftuiation only : Nay, when being expofed 
 with them to the open Fire, it evaporates; it in the 
 mean while deftroys the metallick Particles, as foon 
 as it renders them volatile. 
 
 Of 
 
Assaying Metals. 
 
 Zf 
 
 Of Bismuth. 
 
 83. Bifmuth (§ 15.) caufes the lefs fufible Metals 
 ..to melt, by a much lefs Fire than they would, if they 
 were to be melted fingle: It mixes eafily with them 
 all, and according to the greater or lefs Quantity of 
 it added to them, it renders them more or lefs white, 
 brittle, and Semi-metal-like. 
 
 84. But Bifmuth being fo eafily deftroyed, it is pro- 
 per that the Mixture of it with Metals difficult to be 
 melted, be made in clofe VefTels, that the Fire be in- < 
 ceffantiy increafed, and the other Conditions fulfilled, 
 which are mentioned (§ 59.) 
 
 85. It is very obfervable, that Bifmuth melted with 
 Lead, Tin , or Silver , difpofes them fo, that being 
 afterwards amalgamated with Mercury , they are infi- 
 nitely more attenuated, and pafs through the Leather 
 together with the Mercury , in much greater Quantity 
 
 ‘ than they would, if there was no Bijmuth (§ 67.) 
 
 Of Z I N K. 
 
 86. Zink (§ 14.) mixes eafily with Lead and Tin, 
 and, according to its Quantity, renders them lefs mal- 
 leable. 
 
 87. He that is willing to melt Zink together with 
 Metals not very fufible, muff ufe the Methods pre- 
 fer i bed (§ 59.) 
 
 88. When it is by Fufion mix’d wit' four Times 
 the Quantity of Copper ; it becomes a brittle Metal, 
 of a fine Gold-Colour, called Prince Rupert’s Metal , 
 Prince’s Metal , or Bath Metal . 
 
 89. It is moreover obfervable, that Zink is very ra- 
 pacious: Which Quality of it is not fo eafily correct- 
 ed by an Addition of Iron , as is in the foregoing Semi- 
 Metals. For, by the Help of a greater Fire and of 
 Air, it fublimes all mix’d Metals; fo that they ad- 
 here to the Furnaces and Stoves in form of Flowers, 
 
 (which 
 
2 6 The Art trf 
 
 (which then are .called Nil album vel grifeum Pompho - 
 lyx.) Or go away together, in form of Sublimate, 
 called Putty or Cadmiee fornacum , in German ( Offen - 
 bruch) infinitely various in Colour, Weight, Figure, 
 and Confiftence. 
 
 Scholion. But the foregoing Semi- Met als produce like- 
 wife the fame Flowers and Sublimates , though without 
 ihe Affiftance of Zink : On which Account the faid Sub- 
 limate and Flowers are of various Kinds. However , 
 wherever thefe are produced , they are always Indications 
 of fome thing of the Arfenical or the Semi- met allick Spe- 
 cies. On the fame Account they differ ?nuch from each 
 other : For fome of them adhere to the very Sides of the 
 Furnaces , in fpite of a great Fire \ and fome others prove 
 incapable of refifting a lefs Degree of Fire , even in the 
 higheft Chimneys . 
 
 Of pure or oily Sulphurs, confidered as Menftrua* 
 
 90. Imperfect Metals, fuch as Iron, Copper , 
 Lead , and Pin , change their Form, lofe all their 
 Malleability, and part of their Fufibility, by a long 
 and ftrong Calcination, and of Confequence lofe their 
 metallick (§ 5.) Nature. Semi-Metals, Arfenick ex- 
 cepted, by a like Calcination, diflolve into Calxs , 
 which by a ftrong Fire (§8. Schol.) turn to Sconce, or 
 become volatile. 
 
 91. If you add to thefe Calxs (§ 90.) a fulphurous 
 (§ 24.) Body, without any vitriolick (§ 22.) Acid, and 
 fo fixt of its Nature as not to be diffolvable by any 
 but a great Fire ; the brittle Sco/ub , or the Calx is 
 reftored to its Priftine, either Metallick (§5.) or Semi- 
 metallick State (§ 13.) *, which Operation is called 
 Reduction. 
 
 92. This reduced Metal or Semi-metal, may, by 
 
 repeating the Calcination, again be deftroyed (§90.) 
 and in the fame Manner (§91.) be reduced to a like 
 Scoria,^ ora like Calx . 
 
 93. Hence it is plain that the Oleofum pur um Prin~ 
 cipium , or a pure oily Principle, enters into the Com- 
 
 pofition 
 
Assaying Metals. ly 
 
 pofition of Metals and Semi-Metals *, which may be 
 Fill more confirmed by an Addition of Nitre. For if 
 the Nitre, which detonates with every fulphurous Mat- 
 ter, is call upon Metals grown red hot in the Fire ; 
 thefe Metals, under a very evident Detonation, im- 
 mediately change into Calxs and Sconce * 5 becaufe 
 without Nitre they never undergo fo fudden a 
 Change, in the fame Time and Degree of Fire. 
 
 94. But the Chemical Analyfis ihews us, that there 
 is a fulphurous or oily Principle of this Kind (§ 24.) 
 contained in every part of Vegetables and Animals ; 
 fince a great Quantity of it may be extracted thence, 
 by a ftrong Diftillation. 
 
 95. However, it is obfervable, that Calxs and 
 Sconce (§90, 91, 92, 93.) are never fo far reduced by 
 fulphurousor oily Matters, as to be by them reftored 
 to their former Quantity : Nay, there is always a part 
 of them deftroyed : Which Lofs does like wife vary, 
 according to the Diverfity of the Metal or Semi-Metal 
 employed, or to the Duration and Violence of the 
 Fire, by which the Calcination has been mac^e ; ac- 
 cording to the quicker or flower Reduction of the 
 Calxs , and to the greater or lefs Purity and Fixednefs 
 of the oily Matter itfelf, wherewith the Reduction is 
 made. 
 
 Corollar . I. From thefe Things appears the Rea- 
 fon of the Extraction by Fire of the Metals, Iron, 
 Copper, &c. out of their Marcafite. For, if they 
 are laid in Strata together with Coals, and then urged 
 by a very ftrong Fire, excited with a Pair of Bel- 
 lows, their Sconce melting, running between the 
 burning Coals, and extremely attenuated by the Fire, 
 is impregnated with the oily Exhalation of the burn- 
 ing Coals, and thus reduced to a metallick Form. 
 
 Corollar. II. As the Calxs of Metals melt in the 
 Fire, with much greater Difficulty than the Metals 
 themfelves, whofe Deftrudlion gave them Birth *, 
 the Reafon is plain, why a much greater Fire is ne- 
 ceftary to reduce Metals and Semi-Metals from their 
 
 Calxs 
 
2§ The Art of 
 
 Calxs to their former State, than to melt the fame 
 after their Reduction. 
 
 Corollar « III. For the fame Reafon, the fatty 
 Matters added to Metals in order to melt them, put 
 them fooner in fufion, than the fame Degree of Fire 
 could have done, without the immediate Touch of 
 oily Bodies. 
 
 Corollar. IV. It is likewife evident, why Metals 
 and Semi-Metals, that are deftrudtible by a naked 
 Fire, are much lefs deftroyed, when they melt under 
 the Duft of Coals, or fome other phlogiftick Body, 
 than if they alone and naked fuftained the Strength 
 of the Fire. 
 
 Of Salts, confidered as Menstrua. 
 
 Of fixed Alcaly, confidered as a Menftruum. 
 
 9 6. See the Chara&eriflicks of this Salt. Boerk « 
 Elem. Chem . T t I. p. 764. 
 
 97 . qAlc aline Salt diflolves Stones and Earths of all 
 Kinds, in a great Fire, efpecially thofe that vitrify : 
 Which is the fooner effected, as the Mixture was more 
 exactly made before. Then a Glafs is produced, 
 which is extreaml'y various, according to the Diver- 
 fity, Tranfparency, Hardnefs, Weight, Colour, and 
 Fufibility in the Fire, of th zSalt an d Stones. 
 
 98. Gold and Silver, by the Flelp of this Salt, call 
 only upon them, are eafily melted, and lofe nothing, 
 provided both the Metals and Salt be perfectly pure. 
 But if the Calx, Filings, &c. of thefe Metals, mixt 
 with a greater Quantity of Alcaline Salt, melt in the 
 Fire *, the whole Metal does not fink to the Bottom, 
 but a part of it is detained in the Salt fwimming at 
 Top. But when the Earths and Salts are mixt with 
 them at the fame Time, the Lentor or Softnefs by the 
 Earth communicated to the Salt, and which no Fire 
 can perfectly attenuate, caufes the Quantity of Metal 
 in them remaining to be confiderable. 
 
 99. Iron, 
 
Assaying Metals. 29 
 
 99. Don, Copper, Tin, and Semi Metals, being 
 melted with this Salt of Oil made very fharp, are 
 more flowly confumed. Befides, Ale all promotes 
 very much the melting by Fire of Iron, Copper, and 
 the Regulus of Antimony : But not that of Tin, 
 
 Lead , Bifmuth , and Zink \ as thefe melt eafier than 
 Salt itfelf. 
 
 100. Mercury refills Alcaly altogether, nor can it 
 be mixt with it by any Method that is known. This 
 therefore is to be entirely avoided in the Preparation 
 of Metals for an Amalgama (§ 65). 
 
 101. What kind of fixt Alcali, whether mixt with 
 pure oily Matter, or with mineral Sulphur, is to be 
 preferred, we (hall point out hereafter, when we treat 
 of compound Menfirua , Flux's, Cements , &c *, 
 having hitherto explained only the fimpler Species 
 of them. 
 
 102. But the fixt Alcali, being, as it were, a dry 
 Menftruum , ferves chiefly to reduce the Calx of Me- 
 tals, that have been reduced by Acids. For Acids, 
 adhering to Metals, and being driven away violently 
 by a Fire carried to an exceflive Degree ; they hurry 
 a confiderable Quantity of them away with them- 
 felves : And if they are obliged, by adding more of 
 the fixt already, to pafs fir ft, whatever metallick 
 Matter they carry with them is abforbed and fixt : 
 that by this Means the Calx of Metals, made in- 
 tirely volatile by Acids , efpecially by that of Sea-Salt, 
 may be reduced without Lofs : Which cannot be con- 
 veniently effected by adding other Menftrua. 
 
 103. There is hardly any Neceflity, here to men- 
 tion the volatile Alcali *, it being very feldom, if 
 ever, neceflary in affaying. 
 
 Of Acids, confidered as Menftrua^ 
 
 104. Acids are employed by Afiayers, either the 
 mo ill or the dry Way, and according to the feveral 
 Methods ufed, produce different Effects. Among 
 thefe Acids occur, i ft , The vegetable Acids, of 
 
30 The Art of 
 
 which Wine -Vinegar is the only ufed. 2 diy , The 
 foflile Acids, among which the natural Acid of Vitriol 
 (§ 22.) has the firfb Rank ; the Spirits produced with 
 Nitre and Marine Salt by the Art of Chemiftry, 
 come next. 
 
 Of Vinegar of Wine . 
 
 105. Vinegar of Wine poured upon Earths and 
 Stones of all Kinds, whether calcareous, raw, or 
 burnt, difiolves them with a violent Ebullition, into a 
 Fluid to appearance homogeneous. Likewife, it totally 
 confurnes thofe that are chalky, and not to be affe&ed 
 by Fire. But among the vitrificable Stones, thofe 
 which are called Flint, and all the others belonging 
 to this Species, Sand, &c. do entirely refill Wine- 
 Vinegar : But the reft, at leaft as to their vitrificable 
 Parts, do not yield to its Power. 
 
 106. Among Metals, and Semi-Metals, Copper, 
 Lead, and Zink, difiolve molt readily with Vinegar. 
 This corrodes Iron. It has no manner of Power on 
 Silver, Gold, and Mercury. The others are more 
 properly leifurely extracted than dilfolved by Vinegar. 
 
 107. But thefe Diflolutions (§ 105 and § 106.) fuc- 
 ceed quicker with Heat than in the Cold. The 
 fame is to be faid of all the other following Menfirual 
 Acids. 
 
 Of the Acid of Vitriol. 
 
 108. Acid of Vitriol (§ 22.) has, with Earths and 
 Stones, the fame Virtue as Vinegar of Wine (§ 105.) 
 
 109. Among Metals and Semi-Metals it difiolves 
 readily Zink, Iron, and Copper ; and even Iron with 
 an Exhalation Fuelling very unpleafant, to which 
 Fire mull not be fullered to approach, if the Difio- 
 lution is made in a Veflel that has a narrow Neck : 
 
 , For it takes Fire, and burfts the Veffels with great 
 Violence. 
 
 no. Sil- 
 
Assaying Metals. 31 
 
 no. Silver , Mercury , Lead, , and TzVz, are, in 
 the Heat of the Ebullition, rather corroded than dif- 
 folved by this moft concenerated Acid. Though 
 fome of them be at the fame Time fo far dilfolved, 
 as to pafs through a Filtre, and may be wafhed with 
 Water. 
 
 hi. Gold is almoft quite free from the A&ion of 
 this Acid. 
 
 Of Aqua Fortis. 
 
 1 12. Aqua Fcrtis and Spirit of Nitre are the fame, 
 and differ only by the Manner in which they are 
 made. For the former is diftilled with Vitriol and 
 Colcothar, and the latter with Clay, Bole, Oil of 
 Vitriol, Brick-duft, GtV. But the generality of Af- 
 fayers ufe Aqua Fortis, as being more eafily pre- 
 pared ; becaufe a Quantity of Vitriol, much lefs than 
 the terreftrial Mixtures juft mentioned, with lefs Fire 
 alfo, expels the Spirit out of the fame Quantity of 
 Nitre. This Diftillation of Aqua Fortis is made as 
 follows. 
 
 1 13. You put Vitriol in an Earthen or Iron Pot : 
 If you make a Fire under it, the Vitriol begins to 
 melt and fmoke ; by increafing the Fire gradually, 
 it thickens and aflumes the Afh-colour. Let it be then 
 ftirred with a Twig juft before it becomes foiid, till it 
 be perfectly dry : But let it be taken as yet boiling out 
 of the Pot : For if it grows col!! therein, it will flick 
 to it fo faft, that you will hardly be able to get it 
 out. Pound in a moft fubtil Powder three Pounds 
 Weight of this calcined Vitriol, and mix them per- 
 fectly with four Pounds of Nitre well dried, and pul- 
 verized extremely fine. Put all thefe together in a 
 Cucurbite, a Retort, or an Iron Pot, and then put it 
 in a Furnace, that fhall be defcribed in our Chapter 
 of Utenfils, where the reft of the Apparatus hereto 
 belonging will likewife be explained. 
 
 Let then the Fire be made, at firft not much 
 greater than is neceffary to make Water boih When 
 
 the 
 
3^ The Art of 
 
 the Recipient begins to grow warm, then continue 
 the fame Degree of Fire, till all the Phlegm is ex- 
 pelled, which you will know from the Diminution 
 of the Heat of the Recipient *, then increafe the Fire 
 gradually, till you fee a few flight yellowifh Vapours 
 rife. Keep up the fame Fire for one or two Flours, 
 and finally make it fuch as may warm the Vefiels 
 moderately ; having continued it fo for fome Hours, 
 let the Vefiels wax cold, pour the Liquor, now emit- 
 ting reddifh Fumes, out of the Recipient into a Glafs 
 Veflel, having a Glafs Stopple, and this Liquor thus 
 prepared is your Aqua Fortis. 
 
 Scholion. I. In this Operation , you muft always pro- 
 portion the Duration of the fever al Degrees of your Fire , 
 to the Quantity of the Matter to be difiilled. 
 
 Scholion. II. Obferve befides , that , for Security’s 
 Sake , you are to leave in the Clofure of the Recipient and 
 Vejfel vjhich contains the Matter to be diftilled , a Hole 
 that may be ftopt and opened with a Wooden Peg : For 
 if you happen to exceed the juft Degree of the Fire , efpe- 
 cially when , in the beginning , the firft and more fubtile 
 Spirits , which are very elaftick , come forth *, the opening 
 of this Hole may give them a Pajfage , left the Vefjels 
 Jhould bur ft, which would be vaftly dangerous. 
 
 1 14. This Operation requires Nitre perfectly pure, 
 that you may have true Aqua Fortis. Above all 
 Things, you are to avoid the leaft Mixture of Marine 
 Salt, for the Reafon hereafter to be mentioned, when 
 we treat of Aqua Regia. Mean while, as this Ope- 
 ration is very toilfome, and takes a very long time ; 
 
 I fhall hereafter give a Method for making Aqua 
 Fortis of the requifite Purity, and diftilled out of a 
 Nitre not even perfeddy pure. 
 
 1 15. There are befides many other Ingredients, 
 commonly ufed in the diftilling of Aqua Fortis : viz. 
 burnt Alium, Sand, and the like ; which are here 
 added, to hinder the Species, which may happen not 
 to be fufnciendy calcined, from foaming, and from 
 breaking the Vefifel with great Violence. But when 
 thefe Species are fufficiently calcined, and dried up ; 
 
 then |] 
 
A ssaVing Metals. 33 
 
 then thefe Additions are perfectly needlefs, and by 
 over-fwelling the Mafs to be diHilled, requires 
 Veflels of a much larger Size* 
 
 11 6. Nay, there are befides many other, partly 
 needlefs and partly noxious Ingredients, ufed by Di- 
 Hillers of Aqua Forth. Such are Blood-Hones, un- 
 flacked Lime, Plumofe Allum, &c. all which it is 
 neverthelefs very proper not to ufe : For they are fo 
 far from having any good Effedb, that they on the 
 contrary yield a much worfe and more expensive Aqua 
 Fortis. This Water therefore muH never be ufed in 
 docimaflical Operations, before it has been accurately 
 tried. For indeed Aqua Fortis is but too often taint- 
 ed with thefe heterogeneous Matters, the major Part 
 of it confumes away, and it is frequently fo fixt, that 
 the flrongefl Fire is hardly able to take off the leaft 
 Part of it. I would then here have nothing ufed be- 
 fides calcined Vitriol, intimately mixt with Nitre , 
 there being no need of any other. 
 
 1 1 7. However, Bole, Clay, and Brick- Duft, do 
 likewife expel Aqua Fortis out of Nitre, which then 
 is called Spiritus Nitri. But you mufl add four 
 Times as much of thefe, in Proportion to the Nitre. 
 Confequently, this Method is not fo profitable as 
 the former (§ 113.) as it requires Veflels confiderably 
 larger. 
 
 1 1 8. As the extracted Spirits of Nitre are very 
 difficultly condenfated into Drops, efpecialiy in a ful~ 
 try Summer’s Heat, it will not be improper on ac- 
 count of the calcined Ingredients to pour into the Re- 
 cipient one quarter-part of pure Water, and, what 
 is Hill better, of Phlegm extracted out of Aqua Fortis % 
 By which Artifice the Spirits will be much eafier 
 received. 
 
 1 19. Aqua Fortis diffolves and corrodes all gritty 
 Stones , and the feveral Kinds of thofe that are vitri- 
 ficable and not confumed by Fire ^ but it has no 
 Power on Flints , nor of courle on Sandy as this con- 
 fiHs of minute Scones of the fame Kind, 
 
 D 
 
 120. It 
 
34 The Art of 
 
 1 20. It befides difTolves Iron, Copper, Lead , Sil- 
 ver, Mercury , Regains of Antimony , Bifmuth and 
 Zink •, tTz/z imperfectly *, Gold not at all. 
 
 12 1. Common Aqua Forth, when poured upon 
 
 Silver, moft generally grows troubled, in the begin- 
 ning of the DifTolution , and a little after it is per- 
 fect, a Precipitation of a whitifh Powder is made. 
 If this Powder, taken by itfelf, melts in the Fire 
 with Pot-afhes, you find at the Bottom of theVeffel 
 a Regulus of Silver collected. This fometimes melts 
 with Difficulty on the Fire, and has all the CharaCte- 
 rifticks of Calx of Silver precipitated from Aqua For- 
 th by Oil of Vitriol . This certainly happens, be- 
 
 caufe the Aqua Forth has been extracted by too great 
 and too long a Fire, or becaufe too great a Quantity 
 of calcined Vitriol has been ufed, or in ffiort becaufe 
 the mutual Mixture of the Vitriol and Nitre, has not 
 been rightly made : For in thefe Cafes, there appear, 
 when the Diftillation draws at an end, opaque, 
 milky, vitriolick Fumes in the Recipient : Which 
 Phenomenon fufficiently evidences the Caufe of the 
 aforefaid Precipitation. The abovemen tioned Calx 
 very feldom proves Fluid in the Fire ; it after- 
 wards turns into Horn-Silver, and fhews that the im- 
 pure Nitre bought for the Diftillation of the Aqua 
 Forth was intermixed with marine Salt. 
 
 122. But as the DifTolution of Silver, efpecially 
 that by which Gold is feparated from Silver with Aqua 
 Forth, is confiderably hindered and made uncertain 
 by this Kind of Precipitation (§ 121.J ; that Part of 
 Oil of Vitriol , and of Spirit of Salt which fpoils the 
 Aqua Forth, muft be feparated : Which is done in the 
 following Manner. They pour one 30 th or 40 th Part 
 of the Aqua Forth to be purified, into a fmall Cucur- 
 bite, and over a gentle Fire they diffolve in it Silver, 
 in fuch a Quantity as may fully faturate the Aqua 
 Forth. If in the beginning of the DifTolution the 
 troubled Aqua Forth looks milky, it is judged to 
 want to be purified : Then they pafs through a 
 Filtre the warm DifTolution, which being clear they 
 
 pour 
 
 
 1 
 
Assaying Metals. 35 
 
 pour drop bv drop into the reft of the Aqua Fortis 
 that is to be purified : This will become milky as 
 before *, they continue to inftil the Aqua Fortis , till 
 the dropping in of the ftnalleft Drop doth not at all 
 difturb it or render it milky : Then they let it reft 
 for fome Hours, that the precipitated Calx may fub- 
 fide, which done they again let a Drop fall, and re- 
 peat it conftantly, till at laft the milky Cloud is no 
 longer produced by the Falling of the Drop. Fi- 
 nally, they decant the pure and limpid Aqua Fortis , 
 from the Calx which fubfided at the Bottom •, or they 
 ftrain it gently through a fourfold filtring Paper, 
 which ought to be fmall, left it fhould break, by be- 
 ing overloaded with too much of the Aqua Fortis . 
 The remaining Calx is fuch as was mentioned (§ 121,) 
 but the Aqua Fortis is perfectly purified. 
 
 Scholion. Some are ufed to employ common Silver 
 mixed with Copper, nay Copper itfelf \ for the precipi- 
 tating of the Spirit of marine or vitri0lickS3.lt from Aqua 
 Fortis : But this does not at all fucceed , when Spirit of 
 marine Salt is to be precipitated, becaufe this being mixed 
 with Aqua Fortis dijfolves Copper perfectly. The Oil 
 of Vitriol is indeed driven out of Aqua Fortis, by means 
 of the Copper, inform of a whitifh Duft ; but not fo 
 perfectly as by Silver. Other wife, it appears in this 
 
 Operation that the precipitating Body adheres to that to be 
 precipitated, and finks to the Bottom together with it. 
 
 123. The beft Aqua Fortis is often tinged with a 
 greenifh Colour : Which happens, if Aqua Fortis 
 having been expofed for fome Days to the open Air, 
 and thus deprived of its fuming red Spirit, you pour 
 upon it fome frefh ftrong Aqua Fortis ftill emitting 
 its Fumes ; or if Aqua Fortis is diluted with Water. 
 But that you may be certain that this Colour does 
 not proceed from Copper , pour a little of the Liquor 
 into a fmall Cucurbite, and add to it as much of an 
 alcaline DifTolution or Spirit, as isfufficient to faturate 
 the Acid : Then, if there is ever fo little Copper , the 
 Colour becomes of a very dark Azure, with a cloudy 
 Precipitation •, becaufe the Nitre has been thereby 
 
 D 2 regenerated, 
 
3 6 The Art of 
 
 regenerated, which does not diflolve Copper fo much 
 as Aqua Fortis does : But if there is no Copper , the 
 Colour vaniffies entirely. 
 
 124. Aqua Forth thus prepared (§ 113. and 117,) 
 and corrected (§ 122.) muft be concentrated to a cer- 
 tain Degree : For if it is too weak, it either retards 
 the DiiTolution, or often does not even affect the 
 Silver . If on the contrary it is too ftrong, it va- 
 nifhes into Fumes, which rufh violently out of the 
 Veftels, though lufficiently deep, hurrying part of 
 the Silver along with them : But if there is any thing 
 of Gold in the Silver , it is corroded into a Duft , the 
 perfe6t Collection of which is afterwards very difficult. 
 The firft Fault is remedied, by pouring the Aqua 
 Forth into a deeper Cucurbite, and by abftrafting 
 Phlegm out of it, over a gentle Fire, till you fee 
 yellowifh Fumes appear. But, to find out whether it 
 is too ftrong, you are to ufe the following Method. 
 Melt together one Part of Gold and four Parts of 
 Silver ; of which make a Plate, which you are to cut 
 into three or more Parts *, roll up each Part, that it 
 may more conveniently be introduced into a fmall 
 Cucurbite : When roiled up, and (lightly heated at 
 the Fire, put this fmall Plate into the faid Cucur- 
 bite, pour upon it Aqua Forth , about the Triple of 
 the Weight of the Metal, and put it on a gentle Fire : 
 If then the Silver is eroded from the Gold , fo that the 
 Gold remaining retains the very fame Figure of the 
 Plate rolled up, and there appears no reddifh Duft at 
 the Bottom of theVeffel, then the Aqua Forth has 
 its proper Degree of Strength : But if the DiiTolution 
 has been made with fo much Violence, that the Pow- 
 der of the Gold was eroded, or the Plate almoft 
 broken, the Aqua Forth is too ftrong. You muft 
 then, in this Cafe, dilute it with one tenth or eightji 
 Part of pure Water, or rather of weaker Aqua Forth , 
 if you have it at hand, or of the Phlegm that was 
 drawn from it : Which done, you muft repeat the 
 Trial of the Diftolution of a like fmall Plate, feveral 
 Times over, till the Silver be diftolved without the 
 
 lead 
 
Assaying Metals'. 37 
 
 lead Diminution in the Gold , whereby you may be 
 fure of the requifite Degree of Strength in your Aqua 
 Fortis. 
 
 125. Aqua Fortis is excellent, when it comes again 
 after having been by Fire expelled out of diffolved 
 Metal ; becaufe it may be almoft entirely fetched out 
 of it byDiftillation. In order to this, you introduce into a 
 middle-fiz’d Glafs-cucurbite, adapted to an Alembeck, 
 with an Hole in it •, one Pound or one half Pound of 
 the fame Diffolution, and diftil it in the Manner here- 
 after defcribed in the Article of Utenfils, into a large 
 Recipient ; that the Drops may fall one after another 
 at the Interval of fome Seconds : When the Phlegm 
 of what remains fhall be drawn off to fome Ounces ; 
 let a like Quantity of a frefh Diffolution, gently 
 warmed, be put a- new into the Cucurbite, and be 
 drawn off again ; and let the pouring on of the frefh 
 Diffolution be reiterated in the fame Manner, till it 
 is all grown thick. This muff be done in a ffn all 
 Cucurbite, feveral Times over *, left a large Veffel, 
 being over-charged with too great a Quantity of the 
 Diffolution, fhould burft all of a fudden, and the 
 Aqua Fortis and Metal be loft at once. When, af- 
 ter the extra&ing of all the Phlegm, yellowifh Fumes 
 begin to appear by increafing the Fire a little, let 
 a Drachm or half a Drachm of Suet be added, left 
 the remaining Metal being dried up, fhould fo ftrong- 
 ly adhere to the Sides of the Veffel, as that it could 
 not be taken off : And when at laft the Mafs fhall 
 be quite dry, let it be put on the Fire, till it becomes 
 red hot. The Calx of Metal which remains at the 
 Bottom of the Cucurbite, muft be collected, and 
 melted with Pot-afhes. 
 
 Of Sprit of common Salt. 
 
 126. Spirit may be extracted out of common Salt 
 (§ 20.) after the fame Manner (§113. and 1 1 7.), as it 
 is out of Nitre : However, the Diftillation of it re- 
 quires a Fire much ftronger, and much longer conti- 
 
 D 3 nued, 
 
38 The Art of 
 
 nued, than that of Spirit of Nitre, It comes out in 
 the Form of fmall whitifh light Clouds, which coagu- 
 late into a yellowifh green Liquor. But this Spirit 
 may be much more conveniently produced with Oil 
 of Vitriol ; by pouring one part of this 0 / 7 , diluted 
 with an equal Quantity of Water, upon two Parts of 
 common Salt \ and then you make the Diftillation out 
 of Glafs-VeiTels, in a Sand-Bath. Spirit thus drawn, 
 more diluted, and then diftilled by a gentle Fire in a 
 Cucurbite, from a Quantity of the pureft Sea Salt, in 
 order to abforb the Portion of Oil of Vitriol , which 
 may happen to adhere, and then dephlegmated and 
 rectified ; I fay, fuch Spirit mull be looked upon as 
 the belt Spirit of Salt, 
 
 127. Spirit of Salt diffolves Iron into a yellowifli 
 green Liquor, and Copper into one of a deep yellow 
 Colour. H In diffolves in this Spirit with Violence and 
 much Noife, in great Plenty, and becomes a thick, 
 tranfparent Fluid. Lead diffolves in it likewife ; 
 but after it has refted a while, there is always fome- 
 thing of a white Duff that finks to the Bottom. Sil- 
 ver, provided it be very pure, does not diffolve in 
 Spirit of Salt ; but if it contains ever fo little Copper , 
 for it feldom is altogether free from it, its Surface is 
 in a Manner corroded by the Acid o I Salt, and its 
 Colour lullyed. The belt Spirit of Salt prepared 
 with Oil of Vitriol 1 and re&ified (§ 126.), being pour- 
 ed upon Gold does not influence it in the leaft. It dif- 
 folves Mercury into a limpid Liquor. When more 
 diluted with Water, it does not diffolve Regulus of 
 Antimony : But this being diffolved in the moff con- 
 centrated Spirit of Salt , if you add Water to it, or 
 only expofe it to the moift Air, you reduce it again 
 
 . to a white Duff. Zink diffolves immediately in Spirit 
 of Salt, 
 
 Of Aqjj a Regis. 
 
 128. When the Spirits of Nitre (§ 113.) and of 
 Salt (§ 126.) are mix’d together, this Mixture is cal- 
 led 
 
Assaying Metals. 39 
 
 led Aqua Regis. To have it excellent, put in a Glafs- 
 Retort Aqua Fortisof the belt kind, well proved, and 
 of therequifite Strength (§ 122, 124.) add to it half 
 the Quantity of common Salt, perfectly dry, and pul- 
 verized *, and in a Sand-Bath force up the Spirits, firft 
 by a flow, and finally by a ftrong Diftillation. Or 
 if you put into Aqua Forth one quarter Part of Salt 
 Ammoniac , or of Spirit of Salt (§ 126); it immediate- 
 ly aftumes a yellow Colour, and emits abundantly the 
 white Vapours of the Spirits of Salt , which foon pro- 
 duces true Aqua Regis. However, you are to take - 
 Care, in this fecond Method, that the VefiTel contain- 
 ing the Mixture be not prefently fhut up clofe: For 
 in that cafe it would burft. Befides, this Mixture 
 muft be made under the Chimney, left the fuffocating 
 Spirits fhould lpread all over, and fill the Labora- 
 tory. 
 
 129. Aqua Regis , diftolves perfectly Iron , Copper , 
 Tin, Gold , Mercury , Regulus of Antimony , Bifmuthy 
 and Zink. It even diftolves Lead more than Spirit of 
 Salt does *, however, it becomes fomewhat troubled in 
 the Operation. If it has its requifite Degree of 
 Strength, it does not diflolve Silver : But if you have 
 put in the Mixture a Quantity of Salt Ammoniac , 
 or of Marine Salty or of Spirit of common Salt, not 
 fufficient, it then corrodes Silvery nay, it even diftolves 
 it in part, this Aqua Regis being imperfe<ft. 
 
 Coroll. The Reafon is then felf-evident, why in the 
 Separation of Silver and Gold by Aqua Regis , it is bet- 
 ter to ufe a Quantity of Spirit of Salty or of Marine 
 Salty or of Salt AmmoniaCy exceeding, than one fhort 
 of the right Meafure. Nor is it lefs evident thence, 
 why an exadl Separation of Silver and Gold is better 
 effected with Aqua Forth than with Aqua Regis ; as 
 the former never corrodes Gold % whereas the latter 
 corrodes Silver frequently. 
 
 D 4 
 
 Of 
 
40 The Art of 
 
 0 Neutral Salts, confidered ds Menftrua. 
 
 130. The Neutral Salts here chiefly ufed, are Borax, 
 fel Vitri , that is, the Scum of Glafs called by the 
 Germans Glafs -gall. Nitre , common Salt , and Salt Am - 
 moniack . 
 
 0 / B O R A X. 
 
 13 1. Borax , or Chryfocolla, (Gold-Sodder) is a Salt 
 very difficult to be difiolved in Water. It is white, 
 fbmewhat tranfparent, confiding of odloedral Cry- 
 flals; having a fweetifh Flavour at firft, and in the 
 End an alkaline urinous After-tafte. Borax expofed 
 to the Fire, is raifed into Spume with a hiffing 
 Noife, when at laft the Veflfel grows red hot, it be- 
 comes a thin Fluid, and then growing cold it looks 
 like very fine Glafs : However it is at any time diflfo- 
 luble in Water, though with great Difficulty. 
 
 Scholion. Borax being fo apt to foam and fwell on the 
 Tire, it is very proper to melt it before it is ufed , left it 
 Jhould rife over the Vejfels. 
 
 132. All Earths and Stones, well mix’d and 
 pounded together with Borax , dififolve into Glafs of 
 different Species. 
 
 133. Borax forwards very much the melting of 
 Metals difficult to be put in Fufion*, as are Gold , Sil- 
 ver, Copper , Iron , Regains of Antmony, and dimi- 
 niffies them very little. When, therefore, Metals are 
 difperfed, or divided into very minute Parts, retain- 
 ing however their metallick Form, and are then to be 
 again reduced into one Angle Mafs by Fire, Borax is 
 of very great Ufe. Dirt and Affies, though in ever fo 
 fmall a Quantity, will certainly hinder fmall Particles 
 of Gold and Silver from melting eafily into one fingle 
 Mafs. But if they are fo difpofed by a very ftrong 
 Fire, as to melt into Regulus , a great Part of the Me- 
 tal will always adhere to the flighteft Filthinefs that is 
 {lung away. But the viler kinds of Metals not only 
 
 undergo 
 
Assaying Metals. 41 
 
 undergo the above-mentioned Accidents ; but their 
 Surfaces being fo far encreafed. Copper and Iron turn 
 entirely into Sconce and are deftroyed, and Tin and 
 Lead are fo in great Part. It is therefore very detri- 
 mental when thefe viler Metals are mix’d in ever fo 
 fmall a Quantity with Gold and Silver. For in the 
 melting there come upon the Surfaces light Sconce, in 
 which the Gold and Siver is retained as in Spunges, 
 and is hindered from running into the Regains. To re- 
 move thefe Inconveniences, Borax is added, becaufe 
 as it helps the melting of Metals, and of all Bodies by 
 Fire, its bringing the whole Mafs to a quick Fufion, 
 caufes the Metals to fink to the Bottom without Lofs, 
 and vitrifies the lighted Sconce, throwing them on the 
 Surface. Which is true of both the nobler and the 
 viler Metals, but of Copper and Iron efpecially. Be- 
 fides, Borax , by covering the Surface of Metal tor- 
 tured in the Fire, as if it were with a kind of very 
 thin Glafs , defends it againft the combined Force of 
 the Fire and Air, which is very deftruCtive of imper- 
 fect Metals efpecially *, befides, that it alfo caufes 
 Metals to melt in a much lels Fire. 
 
 134. It is likewife expedient to rub with Borax the 
 Infide of the Crucibles in which the. more precious 
 Metals are to be melted : For they, by that Means, 
 are totally covered with a thin vitreous Cruft, when 
 in Fufion, and the fmall Cavities which never fail to 
 render the Infide of even the beft Crucibles, uneven, 
 are filled up : So that the Metal may be poured out 
 all very neatly. Therefore, it is a chief Point never 
 to negleCl this particular, when any little Mafs of 
 Gold or Silver is to be melted a fecond Time. 
 
 135. Obferve however, that, if you melt Gold 
 with Borax, you muft add to it a little Nitre, or Salt 
 Ammoniac, but not both together •, becaufe they 
 would make a Detonation. For Borax alone makes 
 Gold pale ; but it recovers its Colour again, by means 
 of Nitre, or of Salt Ammoniac . 
 
 136. Borax, on account of the above-mentioned 
 Quality (§ 133.) is clafled, though improperly, a- 
 
 mong 
 
42 The Art of 
 
 mong reducing Bodies, that is, among thofe which 
 reftore Metals, howfoever deftroyed, to their metal- 
 lick Form : For it reduces into one Mafs of Re- 
 gulus , not the deftroyed Metals, but only the fcat- 
 tered Particles of them. 
 
 137. There are other neutral Salts, ufed for the 
 promoting the Fufion of Metals : But they are feldom 
 alone, and almoft always mixed with Bodies of the 
 reducing Kind only, of which we fball fpeak foon. 
 For thefe alone almoft always diminifh fomething 
 from the grofier Metals in Fire, or even change them 
 altogether. Of this Kind are common Salt, Glafs-Gall 
 and Nitre . However, of thefe Nitre is moft to be 
 avoided : It is true, it promotes very well the melt- 
 ing of Gold and Silver *, but as it, on the contrary, 
 caufes a Detonation with the fulphurous Part of the 
 coarfe Metals, which is not fo intimately mixed, it 
 changes them into Calxs, moft commonly very diffi- 
 cult to be melted ^ which may be eafily experienced 
 in Copper , Iron , Lead, and Tin , mixed with an equal 
 Quantity of Nitre , and thrown into a red hot Cru- 
 cible. Salt A?nmoniack is alfo now and then ufed by 
 Aftayers: Though its Defedt may be eafily fupplied, 
 fometimes with common Salt , fometimes with Nitre . 
 For it feldom is ufed, except in the two Cafes above- 
 mentioned (§ 128. and 135.) viz. For the making of 
 Aqua Regis, or for the colouring of Gold: And the 
 former may be very well obtained with common Salt , 
 and the latter with Nitre . For which fame Reafon, 
 we have not mentioned Salt Ammoniac in our firft 
 Chapter. 
 
 0 / Sulphur, confidered as a Menftruum. 
 
 138. Here we do not underftand by Sulphur any 
 inflammable Matter whatever (§ 24) ; but that Mat- 
 ter only which is mixed with the Acid of Vitriol. Such 
 is common fcffile Rrimftone , which, in regard to the 
 Acid mixed with it, has quite other Qualities, than 
 an unmixed oily Principle. 
 
 139. The 
 
Assaying Metals. 43 
 
 139. The pured Gold , when melted with Brimftone , 
 remains perfectly the fame as before ; it lets the Sul- 
 phur burn very freely, remaining itfelf at the fame 
 Time entire, provided it was very well cleanfed 
 before. 
 
 140. Silver , when it begins to grow red hot in the 
 Crucible, melts immediately by adding Brimftone , 
 which of courfe renders it more fpeedily fluid. 
 When poured out, it proves a Mafs that cuts very 
 eafily, very malleable, of the Colour and Confi (fence 
 of Lead . However, this Mafs being a fecond Time- 
 expofed to a very great and long lading Fire, is again 
 freed from the Sulphur , which is then diflipated ; 
 and then it germinates into a kind of woolly Sub- 
 dance, in cafe the Fire be dackened towards the 
 End. 
 
 14 1. Tin granulated, and dratified with an equal 
 or a double Quantity of Brimftone , deflagrates in the 
 Fire as if Nitre had been added, and leaves the fluid 
 Mafs, which becomes folid and confident, while it is 
 yet red in the Fire : Whence it is plain, that the Fu- 
 fion of Tin is retarded by Sulphur. The remaining 
 Regulus , under the Hammer, is very brittle, much 
 like a Semi-Metal, and of the Colour of Lead. But 
 the Part of the Tin thus turned into Sconce^ looks 
 like Afhesand Dud at Top, but darker coloured and 
 cleaner within. The whole Mafs of the Tin will turn 
 into the like Sconce , by continuing to burn it with 
 frelli Additions of Brimftone. 
 
 142. Lead melted with Brimftone , after the Defla- 
 gration turns into a Mafs hardly fufible by a great 
 Fire, friable, confiding of very bright Particles, and 
 with which the Crucible is lcen to be wholly in- 
 crudated. 
 
 143. Copper made into Strata with an equal Quan- 
 tity of Brimftone , melts immediately in the Fire, and 
 turns into a black brittle Mafs. The dime thing 
 happens, when you pour Brimftone upon Copper tho- 
 roughly red hot. 
 
 144. The 
 
44 The Art of 
 
 144. The very fame Thing happens to Iron , which 
 being taken red hot out of the Fire, and rubbed with 
 Sulphur , melts immediately into a fpongy Drofs. It 
 quits this Sulphur with great difficulty, but melts very 
 eafily with it : So. that there is no Metal or Semi- 
 Metal that is fo friendly to Sulphur as Iron. 
 
 145. Regulus of Antimony being well pulverifed, 
 mixed with Sulphur , melted, and ftirred with a Hook, 
 turns into crude Antimony , the Fufion of which is like- 
 wife promoted by Brimftone. However, it is more 
 difficult than any of the foregoing to mix with Brim- 
 fione. 
 
 146. The fame happens to Bifmuth melted with 
 Brimftone over the Fire, as doth Regulus of Antimony 
 (§ 145): Which however is a little flower. Thence 
 a Mafs is produced, like Antimony, of a faint grey 
 Colour, confiding of minute and very bright Needles 
 [ Spiculi ] cutting each other acrofs,and extremely brittle. 
 
 147. Zink melted with Brimftone , mixes with it not 
 very eafily ; but if remaining long in a moderate 
 Fire, it is covered over with Sulphur poured at feve- 
 ral Times upon it, and continually ftirred with a 
 Poker, this at laft produces a very brittle, dark- 
 coloured, fhining Subftance. 
 
 Coroll . 1. Therefore, Iron being very greedy of 
 Sulphur , all the other Metals and Semi-Metals may 
 be freed of Sulphur by it. 
 
 Coroll. 2. A very fmall Quantity of Iron , a greater 
 Quantity of Copper, and a confiderable deal of Lead 
 and Tin, are neceflary to abforbe the fame Quantity 
 
 of Sulphur. 
 
 Cci'oll. 3. The reguline Part of Antimony is precipi- 
 tated from Sulphur, by Iron, Copper , Lead , Tin, and 
 Silver. 
 
 Coroll. 4. The Sconce fwimming upon the Regulus 
 of Antimony made by the abovefaid five Metals 
 {Coroll. 3.) are more or lefs fufible, according as thefe 
 Metals melt more or lefs eafily with Sulphur in the 
 Fire : For the Sconce of Regulus of Antimony are nothing 
 but Sulphur of Antimony mixed with precipitating Me- 
 
Assaying Metals. 45 
 
 tals. Therefore, the Drofs of Silver is very eafy, 
 that of Tin, Copper , and Iron more difficult, and 
 that of Lead the mod difficult of all, to be melted, 
 
 148. If you throw into a Crucible, red hot on the 
 Fire, white artificial Arfenick , mixed with one tenth 
 Part of Brimftone , and cover it immediately with a 
 Tile ; and then pour it out after it has been one or 
 two Minutes in Fufion, it becomes a folid brittle Bo- 
 dy, of a Citron Colour *, but if you melt it in the 
 fame Manner with a fifth Part of Brimftone, the 
 Mafs, when grown cold, aflumes the red Colour ; if 
 at lad you melt or fublimate Arfenick and Sulphur 
 together, in an equal Quantity, it produces a fine red 
 tranfparent Mafs, which is called Rubinus Arfenicalis , 
 Sulphur Auratum , the Arfenical Ruby, Sulphur of 
 Gold. 
 
 149. Brimftone , melted with half the Quantity of 
 fixed Alcali (§ 9 6), turns into Hepar Sulphur is. Liver 
 of Sulphur, fo called from its being of a Liver Co- 
 lour ; which, on account of the alcaline Salt it con- 
 tains, makes all Earths and Stones melt foon in the 
 Fire. When melted with any Metal whatever, it 
 prefently makes it run, and renders it brittle, no 
 longer like a Metal or Semi-Metal, and makes it dif- 
 folvable by Water : This is fo general, that even 
 Gold and Silver are not excepted. Therefore, there 
 are many Cautions to be ufed in the roading of Oars 
 by different Fufions. 
 
 150. A like Hepar (§ 149.) will be produced with 
 vitriolate Tartar with Glafs-Gall and other neutral 
 fixed Salts, -containing the vitriol ick Acid, if, when 
 they are red or in Fufion in the Fire, you add to them 
 Coal-dud, or any other more fixt Phlogid. 
 
 15 1. The Hepar Sulphuris a is not fo drong, 
 when made with fixed Nitre made with Coals, or 
 with Alcali compofed of Tartar and Nitre , nor with 
 neutral Salts with an addition of Sulphur , already con- 
 taining the vitriolick Acid. 
 
 Frid. Hoffmann;, Obferv. Phyfko-Chemi. 
 
 of 
 
4 6 The Art of 
 
 Of Cements. 
 
 152. We have already declared 104, and 129J 
 what were the Effects upon Metals and Semi-Metals 
 of acid Menftrua , condenfed in a fluid Form, by a 
 Heat not greater than that of the Fire which makes 
 them ebulliate. It now remains, that we fhould exa- 
 mine what are the Effects of the felf-fame Menftrua , 
 urged with the Degree of Fire which makes them 
 red hot, upon the Bodies aforefaid. 
 
 153. But, as the acid Salts condenfed into Liquors 
 (§105, 108, 113, 126, 128.) cannot bear to be 
 made red hot, and are refolved by a much lefs Fire, 
 into Vapours which cannot be reftrained ; this re- 
 quires another manual Operation : For the Acid of 
 Vinegar cannot be extracted out of the Cryftals of 
 Verdigreafe , nor the Spirits of Nitre and Salts be ex- 
 tracted out of them, by terreftrial Additions, or by 
 Vitriol (§113, 126) *, nor in fhort the Acid of Vitriol 
 itfelf be fetched out of its metallick or terreftrial Ma- 
 trix, without the ACtion of a very ftrong Fire. 
 Therefore, you are to proceed in fuch a Manner, that 
 the Bodies to be changed by thefe acid Spirits, be in 
 the fame Veflfel wherein the faid Spirits are pro- 
 duced, and, when made red hot therein, be furround- 
 ed on every Side with the agitated Vapours of the 
 fame Spirits. This is eafily obtained, if you put the 
 faid Bodies among the Matter itfelf which is to emit 
 the acid Spirits, after having moiftened it lightly, 
 and preffed it ; and then expofe them together to the 
 Fife. This Operation is then called Cementation ; and 
 the dry Species , which melt the acid Menftrua , and 
 are commonly ufea for this Operation, are called 
 Cemeyits . 
 
 154. The Proportion of the Additions ufed in 
 making the Cements , is the fame as in the Diftillation 
 of acid Spirits (§ 113, and 126). But connnonSalt 
 and Nitre being the melting Menftrua of Metals 
 (§ 137)*, and Vitriol becoming extremely hard, by the 
 
 fame 
 
Assaying Metals. 47 
 
 fame Fire which is proper to be ufed in Cementations, 
 that is, not a very ftrongone •, on this Account, they 
 ufe a Quantity of Brick-duft , Colcothar , &c. three or 
 four times greater *, left the Salts happening to melt, 
 by employing a Fire a little ftronger, they Ihould at 
 the fameTime put the Metals in Fufion, and above ail 
 Gold and Silver : For this is the Method of prevent- 
 ing the melting o f Salts ; or if they melt, you at leaft 
 hinder them by that Means from running together, 
 and from hardening to fuch a Degree, as that the 
 Mafs may not be pulled afunder, and the interpofed < 
 Metal be feparated, but with difficulty. For the 
 fame Reafon, it is not proper here to ufe Bole alone, 
 as an additional Help, becaufe it hardens like a Stone 
 in the Fire. 
 
 155. But, that the Spirits which are driven out 
 (§ 153, 154.) of the Matter of the Cement , may a< 5 l 
 the longer and with greater Force the Veftels in 
 which the Cementation is made, muft be clofed, the 
 Clofures being flopped with Clay, though not alto- 
 gether without vent. By this Means the Spirits are 
 beaten back, and yet not fo abfolutely confined, as 
 not to be able, when the Fire is increafed, to make 
 their way through the Clofures of the Veftels *, which 
 vent being not given them, the Veftels would infalli- 
 bly burft. 
 
 156. Among Metals, Copper , Iron , Lead , Tin, 
 and all Semi-Metals, being committed to any of the 
 above-mentioned (§ 153, 154.) Cements , are totally 
 corroded in a few Hours : Which will be the fooner 
 done, if they are intermixed with the Cement , in form 
 of Lamina’s , or of Granulation. 
 
 157. Thus it is that Silver is immediately con- 
 fumed by the feveral Species of Spirit of Nitre : Nay, 
 Spirit of Salt confumes Silver , when ufed in this Man- 
 ner, which otherwife does not corrode it, when it has 
 the Form of a fluid Body. Nor does Silver refift the 
 Vapours of Vitriol in a Cementation. Nay, the Vine- 
 gar of Vegetables itfelf, concentrated in the Cryftals 
 of Verdigrcafe , and mixed with terreftrial Bodies, 
 
 when 
 
4 8 The Art of 
 
 when ufed as a Cement , takes likewife fomething from 
 Silver . But Gold remains untouched, in all the afore- 
 faid Cements . The other Metals, and all the Semi- 
 Metals, whenever they are intermixed with Gold (if 
 this be granulated, or reduced into Lamina's) are 
 eroded from it by Cementation j this however is fome- 
 what more difficult for Silver *, but Copper , when 
 mixed with Gold in greater Quantity, is confumed 
 pretty foon : Neverthelefs, a fmall Part of it remain- 
 ing in the Gold, is fo ftrcngly defended by the latter, 
 that it is a difficult Matter to feparate them perfedly 
 by Cementation. 
 
 158. The feveral Compofitions and Effecls of Ce- 
 ments ffiall be defcribed in the following Part, when 
 we come to the Operations to be made with Gold. 
 
 Of the simpler and reductive Fluxes. 
 
 159. Whatever caufes a Body, hardly or not at all 
 fufible by Fire, to melt, is called a Flux. 
 
 1 60. But, what Species of Bodies have that (§ 1 59.J 
 Faculty which caufes them to be called Fluxes , you 
 are to fee (§ 46, and follow, 97, &c. 130, &c.) 
 where we treated of the Glafs of Lead, and of fixed 
 and neutral alcaline Salts. Aflayers ufe them, when 
 they want to make Minerals in a fmall Quantity : 
 This caufes them to be called Sales Fuforii . But when 
 a greater Quantity of Minerals is to be worked upon, 
 it is feldom poffible to ufe Fluxes of this Kind with 
 Benefit, becaufe they are very expenfive. Then, in- 
 ftead of the above-mentioned Salts, they ufe fuch 
 Stones as are vitrificable by a gentle Fire or the Sco- 
 ria made of the fame Stones when melted, which 
 ferves this Purpofe frill better : For the more often 
 thefe Stones have been expofed to. the Fire, the more 
 eafily they are put in Fufion : The Reafon of which 
 feems to be the alcaline Salt, proceeding from the 
 Fewel of the Fire, and adherent to the faid Scoria: 
 (§ 97). Therefore, thefe Things being in large 
 Quantities added to Ores, in great Operations, they 
 
 caufe 
 
Assaying M E T A L S. 4£) 
 
 caufe the faid Ores to melt, which are other wife ren- 
 dered refradtory by the calcareous and incombuftible 
 Stones and Earths mixed with them : Which, how- 
 ever, is not fo eafily obtained with the faid Sconce , as 
 by Means of the above-mentioned Glafs of Lead and 
 Salt. But the great Price of thefe hinders their being 
 frequently ufed. 
 
 1 61. We have already faid (§51, 98, 133, and 
 137.) how ufeful thefe S'alts (§ *59, 160.) were, for 
 the melting of Gold and Silver , and of their Calxs. 
 But when, in the Fufion itfelf. Gold and Silver art to 
 be purged of other Metals and Semi-Metals, then it 
 is proper to ufe Nitre only, or at moft Nitre together 
 with other Salts. For Semi-Metals, and the four lefs 
 perfect Metals, are deftroyed (§ 137.) by Nitre ; in 
 which Cafe Nitre , by its Detonation with their Sul- 
 phurs, is in part alkalized, and, by help of a gentle 
 Fire, turns the Calxs proceeding from thefe Metals, 
 into a vitrious and much attenuated Scoria . 
 
 Coroll. Thence the Reafon is plain, why Gold and 
 Silver made brittle, are readily reftored to their Mal- 
 leability by Nitre : For Semi-Metals, and among 
 Metals Lead and Lin m'oft of all, communicate this 
 Fault to Gold and Silver : But being changed by Nitre 
 in the Manner aforefaid (§ 161.) they are in a firnple 
 Fufion again rejected by Geld and Silver: So that 
 they can no longer mix with thefe Metals, unlefs 
 fome Reduction is made. However, there is no ether 
 Body that can, by mixing with Silver and Gold, render 
 them brittle, unlefs crude Charcoals happening to fall 
 into the Vefifel wherein Gold and Silver are melted, 
 fhould impregnate it with fomething arfenical ; there 
 being fome Arfenick contained in Coals of this Kind, 
 2is is demonftrated by Stahl and Hoffman. 
 
 162. The moft imperfedt Metals, and the Semi- 
 Metals melt more eafily, by adding Salts. (§ 159, 160.) 
 to them, than they do of themfelves. However, 
 they always lofe a great deal of their Subftance by 
 this means, which happens efpecially with regard to 
 Copper and Iron . To mend this, it is neceffary to 
 
 E add 
 
yo The Art of 
 
 add fome kind of fat Body, that prevents the De- 
 ftrudlion, and reduces Metals already deftroyed : 
 And this is the more neceffary, when Calxs prepared 
 either by burning, or by a Detonation with Nitre y 
 are to be reduced. The Flux proper for this Opera- 
 tion, is very well prepared in the Manner following : 
 Take one Part of common Nitre \ of crude Tartar, tho- 
 roughly dried, two or three Parts; pound them fepa- 
 rately into a very fine Powder; then grind them well 
 together ; put them into an Earthen Pot, narrow at 
 the Orifice, not glazed within, and of a Capacity 
 three Times larger than the Powder requires : Which 
 done, put them on a gentle Fire. So foon as the 
 Mafs begins to be inflamed with a Noife, fhut the 
 Orifice with a File. After the Detonation, this will 
 produce a black, oily, alkaline Salt , eafily fufible in 
 the Fire, called Fluxus Niger , or Hack Flux ; put it 
 into a Pot clofely fhut, and in a dry warm Place, to 
 prevent its growing moift. 
 
 Coroll. Tartar being burnt alone in Vefiels clofely 
 fhut, or detonated with Nitre, is molt quickly al- 
 kalized, and thus retains a confiderable Part of the 
 Oil which it contains abundantly, and which is fixed 
 enough. For thisReafon, it very eafily turns into a re- 
 ducing Flux. This Flux, therefore, on account of its 
 alkaline Salts , diffolves Earths and Stones , and changes 
 them into an imperfed kind of Glafs (§ 97.) by a 
 moderate melting Fire. But the Oil being of a more 
 fixed Nature, flill remains concealed therein, and is 
 requifite both to preferve Metals from being deftroy- 
 ed, and to reduce fuch as are deftroyed already 
 
 (§ 91)- . 
 
 Scholion. I. If the Pot is glazed within , and part 
 of the glazing comes off , and mixes and melts with the 
 Flux, it is again reduced to Lead, and thus may difap - 
 point the Artificer : Becaufe , this Cruft of Glafs is ap- 
 plied to Pots with Litharge or with Lead. 
 
 Scholion. II. All Fluxes muft he kept and ufed very 
 dry ; for moift Salts foam very much ; and when the 
 Operations are done in clofe Veffels , if the Fire is quickly 
 
 increafed , 
 
Assaying Metals* yi 
 
 increafed , not being able to get rid of the Moifture , it 
 /plits the Vejfels. 
 
 1 63. If equal Parts of the fame Ingredients (§162.) 
 are detonated in the fame Manner, the Oil is aimoft 
 entirely confumed by the abundance of Nitre , and the 
 reft looks like an afh or white colour’d &?//, more al- 
 kaline and (harp than the foregoing ; wherefore it is 
 called Fluxus albus , or white Flux . 
 
 164. The Fluxus albus (§ 1 63.) is very efficacious 
 to diffolve Stones and Earths ; but of a lefs reducive 
 Virtue ; and deftroys the Metal, when the Fire is 
 continued a little longer than is required. 
 
 165. Thefe Fluxes are likewife of very great Ser- 
 vice, to reduce Metals from their refpe&ive Calxs y 
 and to free them from the Stones , in which they are 
 inherent. But when the refra&ory Calx of Iron is to 
 be reduced by a great and long lafting Fire ; thefe 
 Fluxes being infinitely attenuated, though confined in 
 clofe Vefiels, 1. part from their oily Principle : 
 2. then their alkaline Salt remaining ftill, they be- 
 gin to confume the Vefiels, of what Matter foever 
 they may be made (§ 97), and flip away, making 
 their way through them. The firft Fault is mended, 
 by adding Coal-duft , becaufe this lofes not its fixed 
 Oily without the Help of a free Air : The other Fault 
 is remedied with common Glafs made of a due Mixture 
 of Flints and fixed Alkali : For this is fufible enough, 
 it melts with Fluxes added to it, and by its Vifcofity 
 in a Manner coagulates and faturates the Salty and 
 thus hinders it from eafily corroding the Vefiels. 
 
 1 66. Artificers compofe a great many Fluxes with 
 the above-mentioned Salts (§ 97, 130.) and with the 
 reductive ones ; nay, fome ufe as many different 
 Fluxes as there are different Oars and Metals all 
 which, however, we think altogether needlefs to de- 
 feribe. It is better to have explained a few of the 
 limpler ones, which ferve for all the others, and are 
 very eafily prepared, than to tire the Reader with 
 confufed Compofitions : And this chiefly, becaufe 
 unfkilled Artificers fometimes attempt to obtain 
 
 with 
 
5 % The Art of 
 
 with many Ingredients of the fame Nature heaped up 
 beyond Meafure, and with much Labour, though 
 not more properly and more fecurely, what might 
 have been eafily effected, with one only and the fame 
 Ingredient, thus increafing the Number, not at all 
 the Virtue of the Things employed. Neverthelefs, 
 if any one loves Variety, he may, according to the 
 Proportions and Cautions above prefcribed, at his 
 Will chufe among the fimpler Kinds fuch as will beft 
 fuit his Purpofe, and compofe a Variety of Fluxes 
 with them. 
 
 CHAP. III. 
 
 Of Docimajlical Utenfih. 
 
 1 67. 'j Comprehend under this Title the Vefiels, 
 A Furnaces, and other pafiive Inftruments, ne- 
 ceflary for the conveniently and accurately perfecting 
 of docimaftical Operations. 
 
 I. O/Wessels. 
 
 168. The firft among docimaftick Vefiels, is the 
 Coppel , or lefier Cup made of Bone-ajhes , which is aVef- 
 fel made of fuch Matter, that it indeed contains melted 
 Metals, fo long as they are in their true metallick 
 State, but abforbs them, as well as all the other Bo- 
 dies, when they are vitrified. 
 
 169. The Matter of Coppels (§ 168.) therefore, 
 muft be chofen fuch as can refill the ftrongeft Fire, 
 not running eafily into Glafs with vitrificable Bodies, 
 as for Inftance with Glafs of Lead , and fit to be re- 
 duced into a well coherent, though porous Mafs. 
 The beft Earth for this Purpofe was found, that 
 which is made of calcined Bones of all Animals, a 
 very few excepted, efpecially Swine-bones : For 
 when it is made of the latter it receives fomething 
 metallick in it, at the fame Time that it abforbs 
 
Assaying Metals. 
 
 Glafs. But the beft Bones are thofe of Calyes, Oxen, 
 Sheep and Horfes, efpecially the fmalleft, which are 
 the more eafily calcined, the longer they have been 
 expofed to the Injuries of the Air. 
 
 170. The Calcination of thefe Bones (§ 169.) mud 
 be made for a few Hours, or more, according to their 
 Bignefs, in a great open Fire : Therefore, you muft 
 pick up the fmaller ones, and thofe which are lefs 
 covered with fat. You will have a fure Sign of the 
 Calcination’s being perfect, if you fee not one black 
 Spot without the Bones, nor any within when you 
 break them. 
 
 1 71. When thefe Bones are perfe&ly white (§170), 
 pound them in a Mortar, fift them through a very 
 fine Sieve *, or if you have none of this Kind at hand, 
 grind the coarfer Powder upon a very hard Stone into 
 a very fine Flour, and then wafh it with warm frefh 
 Water : For during the Calcination, the Bones are 
 almoft always impregnated with the Salt of the Allies 
 of the Fewel of the Fire. Then this will be an ex- 
 cellent Earth for the making of Coppels *. 
 
 172. Fifii-bones, when very fmall, are more eafily 
 calcined than thofe of other Animals : Whjch may 
 be eafily done in a large open Earthen Vefiel. Thefe 
 Bones being then pulverized are kill better than the 
 foregoing (§171). 
 
 173. Parget or Plafter made of fome kinds of 
 Spaad, is almoft preferable to the aforefaid Earths 
 (§ 171, 172). But it is not every Spaad will ferve 
 this Purpofe. You muft then, before you prepare' a 
 Quantity of this Parget, previoufiy try whether it 
 will fucceed, or not. The Calcination of this Kind of 
 Spaad is made in an earthen Vefiel, clofed with a 
 Tile upon a gentle Fire : This occafions a little 
 crackling, which being over, the Calcination is per- 
 feft. 
 
 174. But, as the Preparation of the Afhes of Bones 
 is toillome enough (§ 17 i, 172) ; and the faid Kinds 
 of Spaad not to be found every where j on this Ac- 
 
 * It is called bv fome Clar , 
 
 E 3 
 
 count, 
 
54 ^ A RT 0^ 
 
 count, when you have a great many Coppels to 
 make, you may fupply this Want with Alhes of Ve- 
 getables. But left the Coppels fhould vitrify, be^ 
 caufe of the alkaline Salt adhering to thefe Alhes, 
 you muft previoufly ufe the following Preparation. 
 Let hot, white, and very light Embers made of 
 foft Wood, be {trained through a Sieve by pouring 
 pure Water upon them ; that all the Coals that 
 happen to adhere to them, may be feparated, and 
 the beft and ftneft Afhes may not fly away. Pour 
 upon this {trained Duft pure and boiling Water ; ftir 
 it with a Wooden Stick ; then let the Alhes fubfide 
 quietly, and the Water which fwims a Top, and which 
 at firft remains always troubled, be decanted : Pour 
 new Water on the remaining Afhes, and after they 
 have fubfided a fecond Time, decant it again : 
 Repeat this over and over, till the Water fwimming 
 a Top proves altogether infipid : Then pour frefli 
 Water again, ftir it with the Wooden Stick, and af- 
 ter eight or twelve Seconds, pour it out as yet trou- 
 bled, into a clean Veflel : Part of the Afhes will re- 
 main in the foregoing Veflel, in which the faid wafh- 
 ing has been made : Pour Water upon this Remaind- 
 er, ftir it and wafti it likewife, and then, after a 
 fhort Reft, pour it into the fecond Veflel : Repeat 
 this in the fame Manner, till there remains at the 
 Bottom of the firft Veflel nothing but a little Sandy 
 or fome other coarfer Corpufcules. Let the walhed 
 Afhes reft till they fubfide, and the Water fwimming 
 at Top be decanted foftly. Thus you will have good 
 Earthy free from redundant Salt and Oily and immu- 
 table by Fire; which, however, being reduced into 
 fmall Balls, burnt again in a Potter’s Oven, and 
 then wafhed anew, will prove better ftill. 
 
 175. Finally, put a fmall Quantity of Alhes of 
 the Bones of Beafts or of Fifties (§ 171, 172.) into a 
 very clean Earthen Veflel, and a fecond Time calcine 
 them during a few Hours, in the ftrongeft Fire, 
 wafh them next with Water, then grind them upon a 
 Porphyry into a moft fubtil Powder, to be kept fe- 
 
 parately. 
 
Assaying Metals. y y 
 
 rately, for the Ufes foon to be mentioned. It is 
 called in German Clacr* 
 
 176. The hollow of the Coppels, which receives 
 and contains the Metal, mud beafpherical Segment, 
 not very deep *, firft, that the Surface of the melted 
 Mafs, let this be ever fo much diminifhed, be fuffi- 
 ciently vifible to the Eye of the Artificer ; fecondiy, 
 that the Metal left in that Cavity, may melt together 
 in one Globule. But the outfides of the Coppels muft 
 be only a fmall Matter convergent towards the Bafis, 
 like a truncated Cone ; that it may Hand firm upon, 
 its Bafis. 
 
 177. But that this Figure (§ 176.) may eafily be 
 given the Coppels, you are to have Copper or Brafs 
 Moulds, the Figure of which is defcribed ( Plat . I. 
 Fig. I. and II.) where we have added an' exa< 5 t Ex- 
 planation. You likewife find their various Sizes, ac- 
 cording to the Quantity of the Metal to be worked 
 in the Coppels. 
 
 178. With all thefe Preparations (§ 168 — 177.) 
 you will make the docimaftical Coppels. 1. Take 
 Allies of Bones, of Beads, or of Fifties alone, or two 
 Parts of Wood Allies (§ 174.) and one Part of dry 
 Allies of Bones (§ 1 7 1 .) mix them well in a Mortar, 
 or upon Porphyry ; then add to them by Drops juft 
 .as much Water, or of white of Eggs diluted with 
 Water, as will be neceftary to make the Matter ftick 
 together, when ftrongly prefted between the Fingers, 
 and not more or lefs : Or if you ufe Spaad (§ 173.) 
 let it be fprinkled in the fame Manner with a Solution 
 of Vitriol. Put a large Quantity of the wetted Dull 
 into a fmall Mortar {Plat. I. Fig. II.) fupported up- 
 on a firm Prop ; prefs down with your Fingers the 
 Mafs poured loofely in *, that the Capacity of the 
 Mortar may be quite full of it ; and lay the Remainder 
 afide. 2. Put the Peftle perpendicular {Plat. I. Fig. I.) 
 into the Mortar, and then with a Mallet drive it with 
 three or four Blows, according to the different Diame- 
 ter of the Velfel that is to be made, and make 
 
 E 4 the 
 
$6 The Art of 
 
 the Mafs pretty compact, taking care left the Peftle 
 fhould rub againft the Sides of the Mortar. 3. Hav- 
 ing then removed the Peftle, ftrew the upper Part of 
 the Cavity of the fmall Vefiel, with Afhes of dry 
 Bones ground extremely fine (§ [75), which is done 
 with the Sieve {Plat. I. Fig. IV): Again, put the 
 Peftle into the Mortar, after having firft wiped it 
 with a clean Rag, and drive it pretty ftrongly with 
 one or two Blows more. 4. Then have at hand a 
 fmall wooden Plank, ftrewed a Quarter of an Inch 
 thick with dry Afhes, put upon it the Mortar con- 
 taining the Coppel already prepared, fo that the lef- 
 fer Bafis of it be underneath ; prefs it againft the 
 fmall Board : the Coppel will then eafily quit its 
 Mould : Let next the prominent Inequalities at the 
 upper Edge and Bottom of the Coppel, be cut off 
 with a iiiarp Knife: Finally, let the Coppel inverted 
 be laid afide in a dry Place. 
 
 179. Therefore, the dry Afhes called Clcer , muft 
 be applied to the Infide of the Coppel, that the little 
 Inequalities molt commonly remaining there, may be 
 filled, and make a Sort of very fine Sieve, admitting 
 through it vitrified Bodies, and retaining Gold and 
 Silver : Thus, when the Cavity of the Coppel is 
 carefully done over with thefe Allies, it will be no 
 great Harm, if the Mafs (§ 178.) ufed for the mak- 
 ing of Coppels, happens to be defiled with a fmall 
 Mixture of Sand or of any other Powder more eafy 
 to be vitrified. And indeed it is hardly poftible to 
 avoid this Fault entirely, efpecially when you ufe 
 Wood- Allies. Thence the Reafon is plain, why 
 this Dull (§ 175.) muft be prepared with fo much 
 care. Therefore great Cautions are to be taken, 
 that the levigation of this Dull be not made upon a 
 foft Stone : becaufe Particles of it being by Chance 
 rubbed off might fpoil the Powder. 
 
 180. The Coppels ought to be rather more than 
 
 lefs compadt : the latter being always hurtful ; 
 
 whereas the former, by abforbing the Glafs more (low- 
 ly, does but retard the Operation a little. 
 
 1 8 1. There- 
 
Assaying Metals. 57 
 
 1 8 1. Therefore, Coppels made of Afhes of Bones 
 oFBeafts, of Fifh-bones, and of Spaad, are excel- 
 lent, as they need not be made very hot at firft, and 
 require not the Regimen of the Fire to be fo ftridtlv 
 obferved. But if you add to them Wood-afhes, it 
 will be neceftary to make the Coppels pretty hot, 
 before you put the Metal into them : Which being 
 negledted, the aqueous Vapours forcing their Way 
 out, will caufe the Metal to be thrown out in Drops ; 
 for Coppels of this Kind can never be perfectly dri- 
 ed by the Air alone *, there being always fomething ■ 
 of an Alcaline Salt adherent to Wood-afhes, which 
 attra&s the Water out of the Air: As the dark Co- 
 lour of thefe Afhes, and the Solution of Ammoni- 
 ack Salt poured upon them evidently fhew. For 
 which very reafon, thefe Allies are more difpofed 
 to Vitrification, than Afhes of Bones ; for the latter 
 are nearer the nature of incombuftible Stones. 
 
 Coroll. Hence like wife it is plain, why the dry 
 Powder (§ 175.) wherewith the Cavity of the Coppel 
 is done over, feparates more eafily in the Operation 
 of the Coppelling, when Wood-allies have entered 
 into the Matter of the Coppels: Which is vaftly 
 prejudicial *, becaufe when thefe things adhere, they 
 either increafe the Weight, or cannot be got out of 
 the Bed of Metal, without fomething of it being 
 loft. 
 
 182. As to the moiftening of the Matter of Cop- 
 pels (§ 178.) you are to take care, (i v .) Not to ufe a 
 Fluid too mucilaginous and fat: For this make3 
 Coppels fo compact, that they not only rejedt vitri- 
 fied Bodies, and yield them a very flow PafTage, but 
 alfo fplit when made very hot, lofing firft their oily 
 Part. (2.) Not to ufe fuch mucilaginous Fluids, as 
 may produce a great deal of fixt Alkaline Salt in the 
 heating of the Coppel *, as the tartareous Dregs of 
 fermented Bodies do. (3.) Not to moiften the 
 Allies too much : for then the Surface of the Cop- 
 pels is never perfectly neat. (4.) Some mix about 
 *Mie tenth Part of decanted Clay to the laid (§ 178.) 
 
 Afhes 
 
58 7 £i? Art of 
 
 Allies: And when this is done, the Matter muft be 
 moiftened with Water only ; becaufe the Clay 
 makes the Afhes flick fufEciently together. How- 
 ever, take care that too much of Clay be not added ; 
 And you muft always regard the feveral Degrees of 
 Fatnefs of this Earth . (5) If the Afhes of Bones 
 
 are not ground too coarfe, their being fprinkled with 
 pure Water, makes them fo coherent, that there is 
 no need of adding any Clay, or mucilaginous Fluid, 
 to increafe the Cohefion ; for Coppels of this kind, 
 as well as thofe made with Spaad (§ 173.J need 
 hardly be made hot before the Metal is put into 
 them. 
 
 Coroll. It is then plain, why the Operation done 
 in a Coppel made with Afhes of the Bones of Beafts, 
 of Fifh Bones, or with Parget of Spaad, lafts a lit- 
 tle longer-, but is more fecurely performed, than if 
 Wood-Afhes had been mixt to it. For as it re- 
 ceives more flowly a vitrified Metal, on account of 
 its own compadl Subftance ; fo it is lefs to be feared, 
 that any thing of a perfect Metal fhould be abforb- 
 ed ; though the Management of the Fire be not fo 
 fcrupuloufly minded. 
 
 183. Thefe fmall Veffels made of Afhes (§ 168.) 
 ferve for docimaftick Operations not very exten- 
 five : But if a larger Quantity of Metals is to be 
 work’d upon, we accordingly ufe greater Coppels, 
 one Foot and a half broad, commonly called Feft. 
 But thefe are made with Wood-afhes ; but not pre- 
 pared with fo much Care as (§ 174.) They add 
 to them Brick-duft beaten very fine. In this 
 cafe, they ufe for Moulds, either the earthen Pot, 
 or the Iron-ring reprefented (Plat. I. Fig. VIII. 
 and XI.) 
 
 184. The manner of making them is as follows: 
 (1) In an earthen Ve fife 1 not glazed within, and by 
 its Depth and Largenefs proportioned to the diffe- 
 rent Quantity of Metal to be put in it. Let the 
 infide of it be well moiftened with Water that the 
 Afhes to be put into it may adhere the better. (2) 
 
Assaying Metals. jp 
 
 Put the Alhes juft mentioned, and moiftened in the 
 lame Manner (§ 178.) as was faid about Coppels, 
 into this vefiel •, fo that it may be half full of them : 
 Then prefs them with a wooden indented Peftle, 
 ( Plat. I. Fig. XII.) or (if* you are making but a 
 fmall Teft) with only a wooden Cylinder an inch 
 thick. When preflfed, add upon them fome other 
 Afhes, to be prefled in the fame manner ; till the 
 earthen Vefiel be almoft quite full : Remove the fu- 
 perfluous Afhes with an Iron Rule. (3.) Let the In- 
 equalities remaining at the Border be fmoothed with' 
 a wooden-Ball rolled about: This done, cut the Ca- 
 vity with a bowed Iron (Plat. I. Fig. IX.) that you 
 may have a broad fpherical Segment, not very deep. 
 (4.) With a Sieve, ftrew this Cavity with dry Afhes 
 of Bones of Animals, ground extremely fine (§ 175.) 
 and to be fqueezed hard by the rotation of the 
 wooden-Ball. Thus you will have a Teft, which, to- 
 gether with its earthen Pot, muft be put in a dry 
 warm Place. 
 
 Another Manner . 
 
 185. Let an iron-Ring (Plat. I. Fig. VIII.) be 
 filled with Afhes like thofe already mentioned 
 (§ 183.) in fuch manner, that they may rife confide- 
 rably above the faid Ring*, then prefs them ftrong- 
 ly with your Hands, or with an indented Peftle 
 (Plat. I. Fig. XII.) (2.) Then, with gentle Blows 
 of a Hammer, prefs the Afhes from the Circumfe- 
 rence towards the Center in a fpiral Line, and in 
 fuch manner that, after having been fufliciently 
 prefled, they may be a fmall matter higher than the 
 Brink of the Ring: Or, if there areVacancies, empty 
 the Ring, and fill it again with more Allies: For if 
 you add ever fo little of Afhes, the fecond put in 
 do not cohere fo ftrongly with the firft, but they 
 may feparate in the Operation. (3.) This done, 
 turn the Ring upfide down, and on the other fide 
 the Afhes out, to the Quantity of one third 
 
 Part 
 
60 The Art of 
 
 part of the Depth of the Ring, and again fill the 
 Vacuity with the fame Allies (§ 185. N°i, 2), in fuch 
 a Manner, that there may remain no fenfible Cavi- 
 ty. 4. Finally, cut out a Cavity in the larger Sur- 
 face of the Ring, and in the fame Manner mentioned 
 (§ i 8 4-) 
 
 186. The Tells, called in German 3 ^r 0 tbfcfj 0 tb 0 lT, 
 are Veffels refilling the ftrongell Fire, and fo vallly 
 compaft, that fometimes they not only retain melted 
 Meltals, but alfo the very Glafs of Lead itfelf. 
 
 187. Their Figure and Size may be the fame as 
 that of the Coppels: However they commonly are 
 made larger. To form them, they ufe a wooden 
 cr hrafs- Mould, reprefented (Plat. I. Fig. V. and VI.) 
 Nor is there any Difference between a Coppel and a 
 Tell, except that the Matter of the latter mull be 
 more compact and coherent. 
 
 188. The Matter fit for the making of Tells is 
 prepared thus : (1.) Make into Balls, Clay of the 
 bell kind, and pure ; and dry them in the Air, or 
 in the Fire: When dried, pound them in a Mortar: 
 Pour upon this Earth abundance of warm Water ; 
 let this Mixture reft a while *, and when the Clay has 
 fubfided, pour out the Water which fwims at top. 
 The fame Walking may be repeated, that all the 
 minute Lumps of the Clay may be well foaked with 
 Water, and any thing of Salt contained in them be 
 walked off (2.) Then add of the purell Sand, of 
 Powder of calcined Flints ground, and well wafhed, 
 of faulty but clean HeJJiah Crucibles, or of any in- 
 combullible Stones ground very fine, fuch Quantity 
 as will render the Mafs thick, hardly adhering to 
 the Hand of him that kneeds it, and hardly pliant 
 when reduced into a fmall Lamina. This Mals will 
 be fit for the making of Tells. 
 
 189. But, before you make a great Quantity of 
 Tefts with this Earth (§ 188.) it will be proper firft 
 to put into a lingle one made with it, a Quantity of 
 Glafs of Lead , and to expofe it for an Hour or 
 more to the ftrongell Fire. Thus you will be fure. 
 
Assaying Metals. 6 1 
 
 whether it can refid Fire, and th zGlafs of Lead: For 
 you cannot determine the exa<d Proportion of the 
 Ingredients, on Account of the Variety of Clays. 
 Nature now and then affords in fome Places Clay fo 
 well tempered, that it is extremely proper for the 
 making of Teds, without any Preparation, or with- 
 out a Mixture of another Matter: Sometimes it on- 
 ly wants to be wafhed : But mod commonly it mud 
 be frrd prepared in the abovementioned (§ 188.) 
 Manner. 
 
 190. If then the Mafs under Trial (§ 189.) turns 
 into Glafs ; you mud add to it fome of the aforefaid 
 Duds of Stones, efpecially of incombudible Stones. 
 However, take care not to add too much of pulver- 
 ized Chalk ; for if the Matter is tempered with 
 that alone, the Teds made with it, will indeed re- 
 fid Fire the more ; but being too porous by this 
 means, they yield a Pafiage to Litharge; which 
 being abforbed, they foften to fuch a Degree, that 
 they fall afunder of themfelves, or are totally 
 crufhed when you take hold of them with Tongs. 
 
 19 1. Teds are made in Moulds (Plat. I. Fig. V. 
 and VI.) after the following Manner. Rub a little 
 Mortar and the Pedle lightly with Bacon or Oil ; 
 then fill fird the two thirds of it with prepared Clay 
 (§ 188.) and then with your Thumb make a fmall 
 Pit in the middle of the Clay; put the Pedle upon 
 it, and prefs the Matter with Blows of a Hammer, 
 the dronger the better; and finally take the Ted 
 out of the Ring, in the Manner mentioned (§ 178. 
 N. 4.) as was faid of Coppels. 
 
 192. The clayy Matter here to be ufed, mud be 
 fo diff and dry, that it may break the Moment you 
 bend it with your Hands: For if it is too foft, it 
 will hardly be poffible to have any intire Teds, or 
 at lead they are mifhapen. Nor yet mud the Clay 
 be over dry ; otherwife it would be difficult to 
 fafhion. 
 
 193. Teds thus made (§ 191.J and dried in a dry 
 and moderately warm Place, may ferve immediately, 
 
 without 
 
6t The Art of 
 
 without being previoufly made hot ; unlefs Salts or 
 Litharge are to be managed therein : For thefe 
 
 Things being melted in Velfels not baked before, 
 foon perfpire through them. 
 
 194. The allaying Oven (Fornix docimafticus ) or 
 as others call it Tegula , Lejludo ; in German , and 
 Englilh Muffely is an arched Covering, refilling the 
 ltrongell Fire, which, in the Operation preferves 
 the Coppels and Tells (§ 178, 19 1.) from the falling 
 of Allies and Coals into them, and at the fame 
 time of fuch a Form, as is no hindrance to the Adi- 
 on of the Air and Fire, nor to the Infpeclion of 
 the Alfayer. 
 
 Coroll . You may then make your Muffels of what 
 Form you pleafe, provided they have the faid (§ 194.) 
 Conditions requilite. 
 
 195. But thofe which ferve for ElTays made in 
 Coppels, are moll commonly made femi-cylindrical ; 
 but like a hollow Hemifphere, when greater Alh- 
 YelTels (§ 184, 185.) are imployed. 
 
 196. The Muffel mull have Holes in it; (1.) That 
 
 the Alfayer may ealily look into it : For which Pur- 
 pofe the forepart of it mull be quite open (Plat. IL 
 Fig. I.) (2.) That the Air may the better ad in 
 
 Conjundion with the Fire, and be incelfantly re- 
 newed: For there is hardly any Fumes produced 
 without the Adion of it ; which however is of an 
 abfolute Necelfity in the Vitrification of Lead: For 
 when the Air is once filled with a certain Quanti- 
 ty of Vapours, it hardly admits any more after that; 
 for which Reafon a conllant Renewal of Air is necef- 
 fary. (3.) Befides, thefe Holes ferve for the Regi- 
 men of the Fire : For the cold Air rufhing through 
 the large Hole before, cools the Bodies put in the 
 Muffel ; or if, after having put fome Coals in it, 
 you Ihut this Aperture in part, or even intirely with 
 a Door added to it, the Fire increafes to the highell 
 Degree ; which can hardly be done fo quickly by 
 the breathing Holes of the Furnace. (4.) That the 
 arfenical Vapours of Lead and Antimony , which pafs 
 
 through 
 
Assaying Metals. 
 
 through the Holes made in the Bafis of the Muffel, 
 may not be offenfive to the Afiayer Handing 
 by it. 
 
 Coroll, Therefore, when you are to fix the Height, 
 Length, and Depth of Muffels, you muff confider, 
 how many Vefiels, and of what Size, are to be intro- 
 duced at once into it, and that the whole Infide of 
 the Vefiels, both foremoft and hindmoft, may be 
 within the Reach of the Afiayer’s Eye : To which 
 laft Point you mutt have a fpecial regard. But mofl 
 commonly they are of the requifite Dimenfion, when , 
 four Inches high, fix or eight Inches long, and four 
 or fix Inches broad. The Segments cut off at the 
 Bafis for the lefifer Holes, muft be fo high as that at 
 lead the fmall Vefiels put under them, may not be 
 tainted by Coals and Allies falling into them : For 
 thefe hinder the Vitrification of Lead , and the De- 
 ftru&ion of the other Metals and the Semi-metals, 
 and reduce them entirely when already deftroyed : 
 But the Scoria fpoiled by Afhes, foften and retard the 
 Operation. 
 
 197. You muft have wooden Moulds, for the 
 forming of thefe Muffels, [Plat, I. Fig, 13J. 
 
 198. The Matter which they are made of, is the 
 fame as that of Teffs (§ 188) *, provided it be a little 
 more moiftened and pliant. 
 
 199. To form your Muffels, gather in one Mafsa 
 fufficient Quantity of Clay prepared (§ 198.) and 
 moiftened, fo as to be fomewhat pliant *, kneed it 
 well with your Hands, put it upon a Plane of Stone y 
 or any other that may be not much changed by the 
 Moifture •, extend the Mafs evenly into a Cake a lit- 
 tle longer than the Muffel to be made, fo broad as 
 to exceed a fmall Matter the Border of the faid Muf- 
 fel, and fo thick as that two or more thin Lamina s 9 
 about two geometrical Lines thick, may be cut off 
 from it : Which is eafily done, by rolling upon the 
 Mafs of Clay a wooden Rolling-pin, ftrewed firft 
 lightly with Afhes or Chalk. 2. With a thin brals 
 Wire well ftretch^d out, cut off from the Cake 
 
 (N° 1.) 
 
6 4 The Art of 
 
 (N° i.J a thin Plate, with great Caution, left it 
 Ihould break ; take it away, and having firft fmeerecl 
 it over with Bacon or Oil, clap it upon the convex 
 Part of the Mould {Plat, I. Fig. XIII.) 3. Then iri 
 the fame Manner fhut the hinder-Part of the faid 
 Mould, with a like Lamina made Semi-circular, fo 
 that the Border of this Lamina may be joined toge- 
 ther with the hinder-Border of the Lamina upon the 
 convex Part of (N° 2.) the Mould •, which is ef- 
 fected with Water, without which the hinder -Lamina 
 would not flick to the fore one. 4. By the fame 
 Method, you may, if you think it proper, annex 
 the Bottom to the inferior Edges of the above-men- 
 tioned two Lamina's . Otherwife, you may leave 
 the Bottom moveable, making it of a fmall Lamina 
 cut off from the Cake : In which Cafe, however, it 
 mufl by its Breadth exceed by half an Inch the Sides 
 and hinder-Part of the Muffel (N° 2. and 3), that 
 the latter may with the greater Security Hand upon 
 it as a Bafis. 5. Then with your Hand wet, rub the 
 Muffel thus made all over *, that the fmall Chinks 
 perhaps not feen, may by this Means be clofed up 
 on every Side, and the Clay clofely joined to the 
 Mould. 6 . When the Muffel applied to the Mould 
 has been for fome Hours in the dry Air, and it is 
 become hard, cut off from it fome Pieces, in the 
 Manner aforefaid (§ 196. Cor oil.) and {Plat. II. Fig. 
 I. and II.) which done, take the Mould foftlyaway : 
 For if the Muffel fhould dry perfectly upon it, it 
 w 7 ould certainly crack. When afterwards the Muffel 
 expofed to the Air for fome Days, is quite dried, 
 it is at laft baked in a Potter’s Oven, or even in the 
 affay-Oven hereafter to be defcribed *, in fuch 
 Manner, neverthelefs, that in the latter Cafe, the 
 Coals being lighted above firft, may communicate 
 the Fire flowly down to thofe underneath : Ocher- 
 wife, indeed the exceffive Force of the Fire would 
 certainly occafion Cracks in the Muffel. For which 
 Reafon, it is much fecurer, to bake it in the firft 
 Manner mentioned. 
 
 2CO. If 
 
Assaying Metals. *5 
 
 200. If you adapt to the Convex Mould {Plat. I. 
 Fig . XIII.) another Concave one {Plat. I. Fig . XIV.9 
 in the Manner defcribed in the Explication of the 
 Figure juft cited, fo that the Clay between them may 
 be formed by a ftrong Preffure ; this will make 
 Muffels much more folid with lefs Trouble, lefs apt 
 to crack, and more capable to refill' the Fire. Now 
 this is done in the following Manner. Put Clay a 
 little drier than the foregoing, or that kind of Clay 
 which is improperly called French Clay *, into the hol- 
 low Mould, rubbed firft with Bacon *f*, and with your 
 Hands extend it on the Semi-cylindrical Cavity of the 
 Mould, and againft the Board at the hinder Part 
 {Plat. I. Fig. XIV. I m) then put upon the extended 
 Clay the Convex Mould, rendered fmooth with Ba- 
 con ; fo that the Sides of it may be equally diftant 
 from the upper Border of the concave Mould : Then 
 put upon it the upper Board {Plat. I. Fig. XIV. n.o.) 
 with Screws belonging to it {g) 9 and by means of 
 them prefs it fo, as that the Board put upon it may 
 touch the Body of the concave Mould : Which done, 
 prefs finally the convex Mould as much as pofiible 
 againft the other, by means of the hinder Screws 
 {Plat. I. Fig. XIV. i. k ) *, then loofe the Screws, 
 and after having taken away the hinder and upper 
 Boards, take out the Convex Mould : Which is done 
 by means of a Screw {Plat. I. Fig. XIV. lit. p) that 
 ferves as a Handle. Thus you will have a Muffel 
 formed, which is eafily taken out of the cylindrical 
 Cavity, and from the Balls of which Segments may 
 immediately be cut off: Finally, dry it well, and 
 bake it as the foregoing ones (§ 199). 
 
 20 1. When larger Afh-Vefiels or Fefts^ 183.) are to 
 be covered, they ufe large fpheroidal Muffels {Plat. II. 
 Fig. III.) made of call lron 9 or they make Muffels of 
 the fame Kind with Clay , and upon Moulds of the 
 fame Figure {Plat. II. Fig. IV). Then the Mafs of 
 Clay is extended with wet Hands only from the Top 
 
 * Windfor-luO&m is as good as any. 
 
 f Black-Lead powder’d is better. 
 
 cf 
 
 F 
 
66 ' The Art of 
 
 of the fpheroidal Mould towards the Borders ; and 
 thus a MufFel is made with no great Trouble. 
 
 202. You fee the Figure of the melting Pots and 
 Crucibles [Plat. II. Fig.Y. and VI). Thefe Veftels, 
 when fmall, are made with a Bafts a little wider ; 
 both that they may not be thrown down, upon what 
 they are fet on, by the Coals put upon them, and left 
 they fhould fall, when taken out of the Fire, and 
 put upon a Pavement not exactly horizontal. 
 
 203. Thefe Vefiels (§ 202.) are formed in wooden 
 or brafs Moulds divided into two Parts, from Top 
 to Bottom, that they may be disjoined and put toge- 
 ther again. For this Reafon, they adapt a broad 
 iron-Ring, to the outfide of the Mould in fuch a 
 Manner, that the two Parts of the Mould may be 
 joined clofe together, by applying the Ring to them, 
 and feparated, by taking it away : Which appears 
 better from ( Plat . II. Fig . VII. and IX.) than from 
 the Defcription. However, this concave Model pro- 
 cures you only the external Form of the Vefiel, but 
 the inward Cavity is made with a Peftle ( Plat . II. 
 Fig. VIII). 
 
 204. The Matter thefe Veftels (§ 202.) are made 
 of, may be the fame as that of the Tefts and Muffels 
 (§ 188 to 190). Obferve only, that it is proper to 
 make ufe of the like Veftels, which have already fuf- 
 tained a great Fire, and are very clean, reduced into 
 Powder, to correft the Stiffnefs of the Clay . 
 
 205. To make Vefiels (§202.) with this Appara- 
 tus (§ 203), put your hollow Mould within the Iron 
 Ring {Fig. VII. and IX), and lay it upon a firm 
 Support : Then fill the Cavity of the Mould, with a 
 fufficient Quantity of Matter (§ 204.) very ftiff ; 
 which Quantity can hardly be determined, otherwife 
 than by Experience : Then prefs it down with your 
 Fingers, or with a wooden-Stick, leaving an hollow 
 in the Middle ; fo that the Matter may rife a little 
 beyond the Sides of the hollow Mould : Finally, 
 put into it the Peftle {Fig. VIII.) rubbed over with 
 Bacon, and drive it down with feveral ftrong Strokes 
 
Assaying Me t a l s’. 67 
 
 (Df a Mallet : Then take away the Peftle gently; and 
 if the Matter is hard enough, and the hollow Mould 
 fufficiently poliffied, the Veffels may be immediately 
 taken out of the hollow Mould, by removing the 
 Ring : But if the Matter is too ftifF, or too moift, 
 and the hollow Mould not fufficiently fmooth, take 
 away the Peftle and put the Mould in a dry warm 
 Place ; and by this Means, the Mould may be 
 opened, and the fmall Veffiel be taken out in a few 
 Minutes. When thefe Veffels (§ 204.) are fufficient- 
 ly dried ; they muft be baked in a Potter’s Oven. 
 
 206. The larger Crucibles and melting Pots arc 
 made in the fame Manner. Only inftead of a Mal- 
 let we ufe a Prefs, to force the Peftle into the con- 
 cave Mould. 
 
 207. There are Cautions to be ufed in the making 
 of thefe Veffels. (1.) A fufficient Quantity of Mat- 
 ter muft be put all at once into the Mould : For if 
 you add to the Matter once compreffed a new Lump 
 of the fame, it does not cohere with the firft : Which 
 happens likewife, when a Quantity of fmall folid, 
 or at leaft compafr Maffes are put into it, without 
 having firft been well united by handling. Hence 
 come many Chinks, and Pores, in the drying and 
 baking, which often cannot be difcovered by the 
 Eye, nor by the Sound when the Veffels are ftruck, 
 and mean while yield a quick Paffage through them 
 to the Salts. (2.) If thefe Veffels are not made with 
 a large Bottom, the concave Mould muft not be be- 
 fmeered with Bacon : Otherwife, when you take out 
 the Peftle, the Veffel flicking to it, commonly 
 comes out of the concave Mould along with it ; nor 
 can it afterwards be taken off from the Peftle, unlefs 
 you break it. 
 
 208. In Fufions, it is often necefiary to cover 
 
 the Veffels with Tiles : Wherefore I give a Pic- 
 
 ture of them ( Plat . II. Fig. X). Thefe are made of 
 the fame Matter as the melting Pots and Crucibles * : 
 
 * A Piece of common plain Tile may ferve as well, if made to 
 fit the VeiTeL 
 
 t 1 £ For j 
 
6% The Art of 
 
 For your common Earthen-ware, which is generally 
 glazed with Litharge, grows clammy in the ftrongeft 
 Fire, and flicks to the VefTels *, fo that they are ta- 
 ken off with difficulty, or even melt entirely. It is 
 then better to cut off Pieces like Tiles with a Knife, 
 from a Cake of Clay (§ 188.) extended upon a flat 
 Table, of the Bignefs requifite, according to the dif- 
 ferent Diameters of the Veffels to be doled. Then 
 pare away the Borders of the inferior Surface of the 
 Plate fo cut off, which is to touch immediately the 
 Veffel to be clofed, leaving a Shoulder all round, by 
 means of which the Tile is faftened in fuch a Manner, 
 that it is not eafily removed by the Poker, or when 
 frefh Coals are put on the Fire. Finally, you put 
 in the Middle of the outlide a fmall Bit of the fame 
 Clay ; that it may be eafily taken away or put on the 
 Veffel again with Tongs, by means of this Kind of 
 Handle. 
 
 209. The fmall feparatory Cucurbites or Matraffes 
 (Plat. II. Fig . XI.) muft be made of very tranfpa- 
 rent Glafs, and yet capable of refilling the moll 
 corrofive Menfirua , left they fhould be corroded. 
 Nor muft they be two thick, efpecially at the Bot- 
 tom ; for when they are very thick they eafily burft 
 in the Fire. Let them be eight or ten Inches high, 
 with a very narrow Orifice, hardly half an Inch 
 wide ; left the Matter therein contained, being in a 
 violent Ebullition, fhould rife over the Mouth of the 
 Veffel, or at leaft Part of it be thrown out in fmall 
 Drops, like a thin Rain, to which there is always a 
 little of the Metal adhering *, that in fhort a greater 
 Repercuffion of the Fumes may be made. The bot- 
 tom has a fufficient Capacity, when it contains one or 
 two Ounces of Aqua Forth . It is befides proper, 
 that their Orifice be turned backwards into a broad 
 Margin or Lip, left the Solutions, when poured 
 out, fhould run down along the Sides of the Veffel. 
 
 210. To fupport fuch a fmall Cucurbite, (§ 209.) 
 we ufe a Trivet (Plat. II. Fig. XII.) fo made, that 
 fmall Cucurbites of this Kind, and fome of a Size a 
 
 little 
 
Assaying Metals. 69 
 
 little larger, may be put upon it with equal Security. 
 Therefore, let the Feet of it be fpread wide afunder, 
 that fome lighted Coals may eafily be put under or 
 taken away, and all the Appearances of the Solution 
 be carefully examined. 
 
 21 1. Next to this, we ufe a Copper Skellet or 
 Glafs Bowl ( Plat . II. Fig. XIII.) furnifhed with an 
 Handle and a Nib, for the wafhing clean of the 
 Calx of Silver precipitated by Copper out of Aqua 
 Forth. It is the better when made of Copper , becaufe 
 it then can expel whatever Quantity of Silver remains 
 in the Solution after the Precipitation. For there 
 remains almoft always fomething of it. The Diame- 
 ter of this Veflel muft be fix Inches or more, its 
 Depth about four Inches. 
 
 212. You muft furthermore have at hand a fmall 
 golden Difh, one Inch broad, and half an Inch deep, 
 {Plat. II. Fig. XIV.) which ferves to heat the Geld 
 in red hot, from which another Metal has been eroded 
 in a docimaftical Operation ; that any remains of 
 the Menftruum ftill adhering to it may be diftipated. 
 It muft be made of the pureft Gold : For in an 
 Earthen Difh, grown porous and brittle by the Sepa- 
 ration, part of the Gold might be feraped off : And 
 if it were made of another Metal, it would either 
 melt, not being able to refill fo great a Fire, or call 
 fcaly Scorias , or even be corroded by the Menftruum 
 remaining in the Gold ; and thus would both waysdi- 
 minifh the weight of the Gold , and deceive theAffayer. 
 
 213. You muft likewife have a particular Iron 
 Trivet {Plat. II. Fig. XV.) adapted to this Difh 
 (§ 212), to fupport it. 
 
 214. The wafhing Trough or Tray {Situla lava - 
 toria. Plat. II. Fig. XVI.) is an oblong Veflel,. in 
 which the lighter and unprofitable Parts of the Ores,, 
 are wafhed off, by pouring Water upon them and 
 ftirring it. It muft be made of Earth or of Stone, 
 not glazed, though of a clean fmooth Surface. How- 
 ever, any other Veffel of a middling Capacity, and 
 pretty wide, may ferve for the fame Ufe. 
 
 F 3 215. Finally, 
 
yo The Art of 
 
 215. Finally, you muft have for the Granulation 
 of Lead and tin above defcribed (§ 44,) a granulat- 
 ing wooden Box, with its Cover, and fo large as 
 that fome Pounds of Metal may be contained and 
 well fhaken in it. You have the Figure of it (Plat. 
 II. Fig . XVII). 
 
 216. But to granulate Metals the wet Way, you 
 may ufe any Veffel, if it be but wide, filled with cold 
 Water, which mufl be ftirred about with a Broom. 
 For Inftance, the Metal, when a good Quantity of 
 it is to be reduced into Grains at once, is firft melted ; 
 then with a very fmall red hot Crucible, 'held with 
 a Pair of Tongs, it is laded up out of the larger 
 Veffel wherein is the whole melted Mafs, and while 
 another Man ftirs the Water about with the Broom, 
 which he then raifes one half above the Water, you 
 pour it all at once upon the faid Broom, that it may fall 
 through it into the Water. But the Sprigs of the 
 Broom muft not be too clofe, left the Metal being 
 (topped by fo many Obftacles, fhould wax cold too 
 foon, and by being detained between their Interfaces, 
 adhere to them, and not reach the Water. When 
 all the Metal has been thus injected, and the Water 
 decanted, you will find it divided into fmall Par- 
 ticles. 
 
 217. Some ufe a particular Machine, made on pur- 
 pofe for this Work, and reprefented {Plat. XI. Fig. 
 XVIII). They take a wooden Cylinder, fix Inches 
 long, and ten in Diameter, and adapt to it an Axis 
 and Handle, like a Grindftone. Then cut all round 
 longitudinally fix or eight Channels about three In- 
 ches deep. Then put the Cylinder thus prepared 
 upon aTub or wideVeffel, like that defcribed (§216); 
 fo that the Axis of it being received by Semi-circular 
 Cavities cut in the Border of the Veffel, may be kept 
 fteddy, left it fhould fly out of its Place in the Ro- 
 tation. Then the Veffel is filled with Water to fuch 
 an Height, as that one third Part of the Cylinder 
 may be immerfed in the Water ; then throw the 
 melted Metal, laded up after the Manner mentioned 
 
 (§216.) 
 
Assaying Metals. 71 
 
 (§216.) upon the Cylinder juft defcribed, which 
 muft be turned all the while upon its .Axis with the 
 Handle. By this Means, your Metal made thinner, 
 than after the foregoing Manner (§ 216.) will be 
 comminuted into thin Plates rolled together. 
 
 Scholion. By both thefe Methods (§ 216, and 217.) 
 combined , you may very well and with Security granu- 
 late Gold, Silver, and the fever al metallick Mixtures : 
 But there is always fome Rijk in the granulating of Cop- 
 per : To avoid which , you ?nufl 'pour it only in a fmall 
 Quantity, and with a fmall Stream ; (Vhich is more 
 fecurely done , if the Transfufion is made through a red 
 hot Crucible , having a few fmall Holes at bottom ; that 
 the Copper being as it were previoufy divided by this 
 framing , may thus fall upon the Broom (§ 216.) or upon 
 the Cylinder (§ 217). 
 
 2 1 8. The Cement- Pots are cylindrical Vefiels, made 
 of Potter’s Clay, with Tiles adapted to them, and 
 turned by Potters. The Size of thefe Velfels muft be 
 proportioned to the Quantity of Cement to be put 
 (§ 153.) into them. However, it is not proper to 
 make them above eight or ten Inches broad : For 
 when larger, the Fire acts with Difficulty and In- 
 equality, efpecially in the Middle of them. 
 
 219. You are to obferve, that in the making of 
 thefe Earthen Vefiels (§ 218.) and of their Covers, 
 all kinds of Clay contract and take up a lefier Space 
 in the drying and baking : Infomuch however, that 
 the purer Clay contracts one tenth Part of its Dia- 
 meter : But the more it is mixt with Sand, or fome 
 other Dull of Stones and Vefiels already baked, the 
 lefs it dirpiniffies *, this Diminution being fometimes 
 hardly perceptible. Therefore, if a Vefiel, or a Co- 
 ver, of a determined Size is to be made of Clay ; it 
 muft be made greater than the required Bulk, in 
 proportion to the Diminution, which Experience 
 teaches you, Clay, either crude or prepared, under- 
 goes in the drying up of it. 
 
 220. The melting-Cone {Plat. II. Fig. XIX.) 
 ferves for the Precipitation of melted Metals, which 
 
 F 4 is 
 
7% The Art of 
 
 is made when two Bodies, melted together, and yet 
 not mixing perfectly with one another in the Fufion, 
 feparate of their own Accord into two Strata, on 
 account of their different fpecifick Gravity. This 
 Precipitation might indeed be made in the fame Vef- 
 fel wherein the Fufion is made : But, in this Cafe, 
 you would be always under the Neceffity of breaking 
 the melting Pot every Time ; becaufe the Part pre- 
 cipitated cannot be got out of it, when this Veffel is 
 intire. Therefore we ufe for this Work the above- 
 mentioned kind of Cone, into which the melted Mafs 
 is poured, and out of which it may be eafily taken, 
 when the Precipitation is perfect. But as the Quan- 
 tity of the Matter to be precipitated is often but 
 fmall, the conical Figure has, on this account, been 
 affigned to the melting- Cones, doubtlefs, that the 
 heavy Matter fubfiding to the Point of it, may be 
 colle&ed into one folid Regulus . 
 
 221. The melting-Cone is made of Copper or of 
 Brafs, that the Infide of it may be fufficiently po- 
 lifhed. When it is made of Brafs, you muft take 
 care that it be not made too hot : For then, when 
 you ftrike it with any force, it eafily fplits, on ac- 
 count of the brittlenefs of this Metal in a great 
 Fire. 
 
 222. When the Quantity of the melted Matter to 
 be precipitated is confiderable ; you may ufe, inftead 
 of melting Cone (§ 221), a large brafs or iron-Mor- 
 tar, or any large iron -Veffel whatever. 
 
 223. Finally, when melted Metals or Semi-Metals 
 are poured out, in order to be examined clofely, or 
 afterwards affayed in part ; it is proper in the pouring 
 out, to give them an oblong Form not over-big : Be- 
 caufe they, by this Means, are more eafily divided, 
 and cut into fmall Bits. In order to this, they ufe a 
 Set of Moulds {Plat. II. Fig. XX.) called an Ingot, 
 having one or many prifmatical or femi-cylindrical 
 Furrows, of different Sizes, and well polifhed, with 
 a very long Handle, and made of Iron, thepropereft 
 Matter for this Inftrument. 
 
 224. But 
 
Assaying Metals. 
 
 224. But when a fmall Mafs of precipitated Metal 
 is forthwith and entirely to be put into a Coppel 5 
 they chufe to ufe a Mould, having the Form of a Seg- 
 ment of a little Sphere, and made likewife of Iron ; 
 fuch as is commonly employed in pouring out fuch 
 Ores as have been extra&ed and fcorificated by Lead. 
 By this Means you are fure to hinder the fmall me- 
 tallick Mafs, from fcraping with its angulous Sur- 
 face any Particle of the tender Bottom of the Cop- 
 pel, while it is put into it, and, by this Means, 
 from making it rough. 
 
 225. All thefe Moulds (§221, and 224.) muft be 
 well heated, before the Metal is poured into them ; 
 left they fhould happen to be a little wet, or con- 
 trail a Moifture, efpeciaily in cold Weather, by the 
 fudden Heat of the melted Mafs being poured into 
 them : In which Cafe, the Matter poured in is often- 
 times difploded with very great Danger. 
 
 226. Moreover, they muft be previoufly fmeered 
 over with Tallow, that the Regulus’s may be more 
 eafily taken out of them, and that the Cavity of the 
 Moulds may not be corroded, by the Mafs poured into 
 them. But if a very great Quantity of Metal is to 
 be poured out, efpeciaily of a very fulphureous Me- 
 tal, or by means of precipitate of Sulphur ; the 
 fmeering of the Cone or of the Mortar with Tallow, 
 is hardly fufHcient, to prevent the Corrofion juft men- 
 tioned : Becaufe the large Mafs of the Matter pour- 
 ed in, remains hot for a confiderable while. There- 
 fore, in this Cafe they ufe a Lute, reduced to a thin 
 Pap, with Water, which being applied very thin to 
 the Infide of the Cone, or of the Mortar, is after- 
 wards dried up. Thus, by means of this Cruft, the 
 Action of the Sulphur upon the Metal of the Cone 
 is certainly prevented. Nay, pure Copper itfelf, 
 though it be melted with no Sulphur, operates fome- 
 thing like this : Wherefore, it is necefiary in this 
 Cafe to ufe the faid Precaution. 
 
 227. Finally, 
 
74 The Art of 
 
 227. Finally, aftaying requires that you fhould 
 have two Mortars ; one of Iron and deep, to beat 
 Bodies fmall ; the other lefs deep, of Iron or Wood y 
 and wide *, this muft have a wooden-Peftle. The 
 latter, moft commonly of Iron , ferves for Amalga- 
 mations : For iron-Mortars are moft fit for thisWork \ 
 becaufe, though fomething of the iron be eroded by 
 the Trituration, it neverthelefs mixes not with the 
 Amalgama : So that Iron is to be preferred to all 
 other Metals, in Operations of this Kind. Befides, 
 Mercury may be moderately heated therein, whereby 
 the Amalgamation is very much accelerated : Which 
 cannot be fo eaftly effected in a wooden-Mortar. 
 
 228. Beftdes, for fome Operations not directly be- 
 longing to the Art of Allaying, though it is proper 
 that the Aflayer fhould be able to make them, by 
 help of his own Skill, you muft have diftillatory Vef- 
 fels, fuch as earthen and glafs- Cucurbites and Re- 
 torts : But thefe being fufficiently known, and de- 
 fcribed every where in chemical Books, I need not 
 here be very particular in defcribing of them. I 
 fhall only obferve, that the glafs -Veftels which are 
 to fuftain a great Fire, are the better as they are 
 thinner : For, when thick, they foon fplit. But it is 
 the contrary for the Recipient, which muft be 
 thicker. 
 
 229. When the Veftels (§ 228.) are expofed naked 
 to the greateft Fire ; it eaftly happens, that they 
 burft, by throwing frefh cold Fuel into the Fire : For 
 the preventing of which, you muft have Recourfe to 
 Lorication or Coating. This is performed in the 
 following Manner : Take fome of the fame Matter, 
 of which theMuffels and Crucibles are made (§ 188), 
 and, inftead of Water, moiften it with frefh Blood, 
 not yet coagulated, and diluted with twice or thrice 
 the fame Quantity of Water, to make a thin Pafte 
 of it : Then add to this Pafte Cow-hairs, or others 
 not very long nor ftiff : And if you have at Hand 
 Glafs pulverized, and fifted, it may alfo be of Service, 
 to mix fome of it with the reft. Then with this Mafs 
 
 befmear 
 
Assaying Metals. 7jr 
 
 befmear your Veffel with a Pencil, and dry it : When 
 dried, befmear it a fecond Time, and dry it again : 
 Repeat this a third and fourth Time, till the Veffel 
 be covered over with a Cruft or Coat, one third or 
 fourth Part of an Inch thick. 
 
 Scholion. Jo hinder the Blood from coagulating ; you 
 mufty when it is juft let out of the Animal , ftir it with 
 your Hand or with a Stick , till it is quite cold : Being 
 thus attenuated , it will remain for fame Hays without 
 coagulating . 
 
 230. When you are to diftil ftrong corrofive Spi- ' 
 rits, it is proper, for the fhutting of the Veffels 
 (§ 2 2 8.) clofe, to mix with the abovefaid Pafte, 
 
 (§ 229.) Bole, worked with Whites of Eggs diluted 
 with Water, in a Quantity not to be determined other- 
 wife than by Experience : This will give you a Lute, 
 which will confine ftrong Vapours. 
 
 II. O/Furnaces, 
 
 231. As the Practice of Affaying confifts chiefly 
 in the refining of Foffils by Fire ; you are to have 
 Inftruments, in which the Fire may be contained, ap- 
 plied to the Subject, and augmented or diminifhed to 
 any Degree, at your Pleafure. 
 
 232. The firft Furnace peculiarly called the Aflay- 
 
 Oven {Plat. III. Fig. I.) is made in the following 
 Manner. 1. Make with Iron Plates, a hollow qua- 
 drangular Prifm, eleven Inches broad, and nine In- 
 ches high, (a a, b b), ending at Top in a hollow 
 quadrangular Pyramid fb b, c c) feven Inches high, 
 terminating in an Aperture at Top feven Inches 
 fquare. But this Prifm muft be clofed at Bottom 
 with fuch another Iron Plate, which ferves as a Bafis 
 or Bottom to it (a a). 2. Near the Bottom make a 
 
 Door (e) three Inches high, and five Inches broad, 
 that leads to the Afh-hole. 3. Above this Door, and 
 at the Height of fix Inches from the Bafis, make 
 another Door (f), of the Figure of a Segment of a 
 Circle, four Inches broad at its Bafis, and three In- 
 ches 
 
The Art of 
 
 ches and a half high in the Middle. 4. Then fatten 
 three Iron Plates on the fore- Part of this Furnace : 
 Let the firft of them (g g) eleven Inches long, and 
 half an Inch high, be clapped, its lower Edge, a- 
 gainft the Bottom of the Furnace, with three or four 
 Rivets, in fuch a Manner, that there may be, between 
 the upper Edge of the faid Plate and the Side of the 
 Furnace, a Groove fo wide, as that the Sliders of the 
 lower Door (k k) may be put into it, and freely 
 move backwards and forwards therein : Thefe mutt 
 be made of a thicker iron-Plate. The fecond iron- 
 Plate (h h), eleven Inches long, three Inches high, 
 and perfe&ly parallel to the foregoing Plate, mutt 
 be clapt in the Space between the two Doors, in fuch 
 Manner, that both the upper and the lower Edge of 
 it, may form a hollow Groove with the Side of the 
 Furnace. One of thefe Grooves, which looks down- 
 wards, ferves to receive the upper Edges of the Sli- 
 ders, that (hut the lower Door (N° 2). The other 
 that locks upwards, is to receive the inferior Edges 
 of the Sliders of the fmall Door above (N° 3). The 
 third Plate (i i) which is like the firft, muft be rivetted 
 clofe above the upper Door, in fuch Manner, that it 
 may form a Groove looking downwards, and con- 
 tiguous to the upper Edge of the upper Door (N° 3.) 
 5. In order to fhut both Doors (N° 2. and 3) you 
 muft adapt to each of them two Sliders made of Iron 
 Plates, that may move within the above-mentioned 
 Grooves (k k 1 1 .) But the tv/o Sliders belonging 
 to the upper Door (N° 3.) muft have each a Hole 
 near the Top ; that is, one a fmall Hole 7 Part of 
 an Inch broad, and one Inch and a half long (m) ; 
 and the other a Semi-circular Aperture, one Inch 
 high and two Inches broad (n). Let befides each 
 Slider have a Handle, that they may be laid hold of, 
 when they are to be moved. 6. Moreover, let five 
 round Holes, one Inch broad, be bored in the Furnace : 
 Two of which muft be made in the fore- Part of the 
 Furnace (o o), two others in the back Part, all at the 
 Height of five Inches from the Bottom, but three 
 
 Inches 
 
Assaying Metals. 77 
 
 Inches and a half diftant from each Side of the Fur- 
 nace ; and finally, a fifth Hole (pj,at the Height of 
 one Inch above the upper Edge of the upper Door (T ). 
 7. In ftiort, let the Infide of the Furnace be armed 
 with iron-Hooks, jetting out half an Inch, and 
 about three Inches diftant from each other, to faften 
 the Lute with which the Furnace is to be covered 
 over within. 8. Let then an iron, moveable, hollow, 
 quadrangular Pyramid (q) three Inches high, be ad- 
 apted to the upper Aperture (d) of the Furnace at 
 the Bafis feven Inches broad, ending upwards in a ' 
 hollow Tube (r) three Inches in Diameter, two In- 
 ches high, almoft cylindrical, though fomewhat con- 
 vergent at Top. This prominent Tube ferves to 
 fupport a Funnel or Flue, which is almoft cylindrical, 
 hollow, made of Iron Plates, and two Foot high (t), 
 and which, when a very ftrong Fire is required, is put 
 perpendicularly upon the fhor ter Tube, in fuch Man- 
 ner, that it enters clofe into it one Inch and a half or 
 two Inches deep, and may again be taken off at Plea- 
 fure, when there is no need of fo ftrong a Fire. But 
 this pyramidalCover (q)muft befides have two Handles 
 (s s) adapted to it, that it may be laid hold of, and thus 
 be taken away or put on again. And, that this be- 
 ing put on the Aperture (d) of the Furnace, may not 
 be eafily thrown down, let an Iron Plate be rivetted 
 to the right and left upper Edge of the Furnace (c c), 
 and be turned down towards the Infide, fo as to 
 make a Furrow open before and behind, into which 
 the lateral Edges of the Cover may enter and be faft- 
 ened, and at Pleafure be moved backwards and for- 
 wards, whenever it muft be put on, or removed. 9. 
 Let a fquare Ledge, made of a thick iron-Plate 
 (Fig. II.) be fattened at top of the upper Edge of the 
 lower Door (e) *, this is defigned to fupport the Grate 
 and the Lute. But it muft be made of two Pieces, 
 that it may be eafily introduced into the Cavity of the 
 Furnace. Thus you will have an aflay Oven, which 
 muft afterwards be covered over inwardly on the In- 
 fide with Lute : This you are to do as follows : 
 
 233. That 
 
*8 The Art of 
 
 233. That the Fire may be the better confined* 
 and the Iron not be deftroyed by growing red hot* 
 the whole Infideof the Furnace (§ 232.) muft be co- 
 vered over (See Plat. III. Fig. III. and IV.) with 
 Lute, one Finger, or one Finger and a half thick. 
 The Lute fit for this, is made with a Mafs of Clay 
 (§ 188, 190), or with French Clay , moiftened with 
 three or four Times as much of Ox-Blood diluted 
 with Water *. But before you cover the Infides of 
 your Furnace with this Lute, you muft firft put 
 within the Furnace fmall iron-Bars, equal in length 
 to the Diameter of the Oven, quadrangular, prif- 
 matical, half an Inch thick, having their Extremities 
 fupported by the Ledge (§ 232. N° 9), and ~ of an 
 Inch diftant from each other ; and you muft fallen 
 them fo, that their flat Sides may be oblique with re- 
 gard to the tranfverfe Se&ion of the Furnace, and 
 that the two oppofite Angles may look one upwards 
 and the other downwards, the Bars muft not be laid 
 flat but edge-ways, by which Situation, you hinder 
 the Allies of the Fuel of the Fire from being detained 
 too long, between the Interftices of the faid iron-Bars, 
 and from making an Obftruflion, that would oppofe 
 the free Draught of the Air (See Plat. III. Fig. IV). 
 The Furnace being then covered over with Lute, 
 and dried up by a gentle Heat, is at laft fit for do- 
 cimaftical Operations, and efpecially for fuch as muft 
 be performed in the Afiay-oven (§ 194.) 
 
 * The belt Lute, and eafteft to be had at London, is a Sort of 
 Clay called Wzndfor- Loam, which muft be mixt pretty ftiff, and 
 prefled into the Infldeof the Furnace, firft wetted with Water, and 
 when the Clay begins to dry, it muft be beat down clofe to the Sides, 
 with a wooden Mallet, then the Unevennefies and Cracks filled up 
 wich frefh Clay fomewhat moifter, fo as to be made fmooth and 
 even with a Trowel, and then left to dry gently, and if any Cracks 
 happen they muft again be filled up. If any Pieces of this Lute are 
 broken off by the Fire ; let it be quite cold and wet, the Edges of 
 the old Lute and frefh Clay will unite to it, and fill up the Holes ; 
 if the Crack is but fmall, you may ufe the Furnace again iromedU 
 ately, even before the frefh Clay is dry. 
 
 23 4. if 
 
Assaying Metals. 79 
 
 234. If then an Operation is to be made in the 
 Furnace hitherto defcribed (§ 232, 233), you muft 
 let through the four lower Holes above defcribed, 
 of the Furnace (See Plat. III. Fig.l. o o) placed 
 before and behind, and direcftly oppofite to each other, 
 two iron-Bars one Inch thick, and long enough that 
 their Extremities on every Side may jut out of the 
 Holes a fmall Matter. Thefe ferve to fupport the 
 Muftel, and its Bottom (See Plat . III. Fig. III. and 
 IV). You theh introduce the Muffel through the 
 upper Aperture of the Furnace {Fig. I. d.) and place . 
 them upon the above defcribed iron-Bars, in fuch 
 Manner that the open fore- fide of it be contiguous to 
 the inward Border of the upper Door f. (See Fig , 
 III. and IV). The Fuel of the Fire is introduced 
 through the Top of the Furnace (d) ; the Cover of 
 which, on this Account, muft be moveable, and not 
 very heavy (q). The beft Fuel for the Fire is Char- 
 coal made of the hardeft Wood, efpecially of Beech, 
 broken into fmall Pieces of the Bignefs of an Inch, 
 wherewith the Muffel muft be covered over fome In- 
 ches high *. We then reject larger bits of Coals, 
 becaufe they cannot fall through the narrow Interftices, 
 between the Sides of the Muffel and thofe of the Fur- 
 nace, and cannot of courfe fufficiently furround the 
 Circumference of the Muffel : Whence it happens, 
 that there are on every Side places void of Fuel, and 
 the Fire is either not ftrong enough, or unequal. 
 But, if on the contrary, you ufe Coals too fmall ; 
 then a great Part fall immediately through the Inter- 
 ftices of the Grate into the Afh-hole ; and the ten- 
 dered Particles of them turn too loon into Afhes y and 
 by increafing the Heap of AJhes , obftrudl the free 
 Draught of the Air, which is here greatly requi- 
 lite. 
 
 * Scotch Coal or Kennel-Coal (but not New-Cajlle or Sea-Coal) bro- 
 ken into fmall Pieces, may be mixed with an equal Quantity of 
 Charcoal ; or if any Ores require long roafting, the Fire may be firft 
 kindled with Scotch Coal } but the Operation is beft finifhed with 
 only Char coal. 
 
 235. A 
 
 3 
 
80 'The Art of 
 
 235. A perfedt Management of the Fire is moft 
 commonly neceftary, in the performing of Operations 
 in this Furnace (§ 232, 233) : Therefore, the Reader 
 muft give Attention to what follows. If the Door of 
 the Afh-hole {Plat. III. Fig. I. e) is quite open ; 
 and the Sliders of the upper Door (f ) drawn towards 
 each other, fo as to touch one another in the Middle 
 of the Door •, and if befides the Cover (q) and the 
 Funnel (t) adapted to its Tube (r) is upon the Top 
 (d) of the Furnace, the Fire will then be in the high- 
 eft Degree poflible : Though in the mean Time it 
 is hardly ever neceftary to put the Funnel on, except 
 in a very cold Seafon. But if, after having difpofed 
 the Furnace in the Manner juft defcribed, you put 
 red burning Coals into the open upper Door (f) of it, 
 the Fire is ft ill more increafed thereby : However, 
 this Artifice is never, or very feldom, neceftary. When 
 you fhut the upper Door, with only that Slider, that 
 has a narrow oblong Hole in it {Plat. III. Fig . I. m) 
 then the Heat becomes a little lefs : But it diminifhes 
 ftill more, when you fhut the Door with the other 
 Slider, that has in it the Semi-circular Hole (n), which 
 is larger than that of the firft Slider : Nay, the Heat 
 again is lefs, when you take away the Funnel put at 
 top of the Cover : Finally, the Door of the Afh-hole 
 being either in part or totally fhut, the Heat is ftill 
 diminifhed, becaufe the Draught of Air, fo neceftary 
 to excite the Fire, is thereby hindered. But if, be- 
 fides all thefe, you likewife open the upper Door 
 quite ; then the cold Air rufhing into the Muffel, 
 cools the Bodies put under it, that are to be changed, 
 to a Degree never required in any Operation, and 
 fuch as will entirely hinder the boiling of Lead . If 
 during the Operation, the Fire begins to decay, or to 
 grow unequal, it is a Sign, that there are Places void 
 of Coals, between the Sides of the Furnace and thofe 
 of the Muffel : Therefore, in this Cafe, you muft ftir 
 your Coals on every Side, with an Iron Rod, which 
 is to be introduced through the upper Hole (p) of 
 
Assaying Me ta i, s. 8 r 
 
 the' Furnace; that they may fall together, and thus 
 act in a proper Manner, and equally. 
 
 236. However, you are to obferve, concerning 
 the Regimen of the Fire juft defcribed (§ 235) that 
 though the Apparatus is made with all the Exadtnefs 
 mentioned, neverthelefs the Effect does not always 
 anfwer it : The Caufc of which Difference has moft 
 commonly its Origin in the various Difpofnions of 
 the Air. For as every Fire is more excited by Coals 
 in proportion, as the Air more condenfed, and more 
 quickly agitated, {trikes them more violently (which 
 the Effect of Bellows plainly fhews) it thence .ap- 
 pears, that in warm and wet Weathers, when the 
 Atmofphere is light, the Fire muff be lefs efficacious 
 in Furnaces ; that likewife, when feveral Furnaces 
 fituated near each other, are burning at the fame 
 Time, the Fire is in part fuffoca ted * becaufe the am- 
 bient Air is thereby rendered more rare and lighter. 
 The fame Effedt is produced by the Sun, efpecially 
 in Summer-time, when it ffiines upon the Place where 
 the Furnace is fituated. The Atmofphere, on the 
 contrary, being heavier in cold dry Weather, excites 
 a very great Fire. 
 
 .237. The Heat of the Fire a<ffs the ftronger upon 
 the Bodies to be changed, as the Muffel put in the 
 Furnace is lefs ; as the faid Muffel has more and 
 larger Segments cut out of it ; as the Sides of this 
 Muffel are thinner •, in fhort, as there are more Vef- 
 fels placed in the hinder Part of the Muffel and on 
 the contrary. 
 
 238. In this Cafe, when many of the Conditions 
 requifite for the exciting of Fire are wanting, then 
 indeed the Artificer, with all his Skill, will hardly 
 be able to excite the Fire to a fufficient Degree, in 
 order to perform Operations well, in common Affay- 
 ovens, even though he ufes Bellows, and puts Coals 
 into the upper Door of the Furnace. For this Rea- 
 fon, I have put the Grate almoft three Inches below 
 the Muffel, left the Air rufhing through the Afh- 
 hole, ffiould cool the Bottom of the Muffel, which 
 
 G happens 
 
8z The Art of 
 
 happens in common Aflay-ovens ; and again, thar 
 the fmaller Coals, almoft already confumed, and the 
 Afhes, may moreeafily fall through the Interftices of 
 the Grate, and the larger Coals ft ill fit to keep up 
 the Fire, be retained. Finally, I have added the 
 Funnel {Plat. III. Fig. I. /.) that the blov/ing of 
 the Fire being, by means of it, increafed as much as 
 poflible, this might at laft be carried to the reqnifite 
 Degree : For the Fire may always be diminifhed,. 
 but not always be increafed at Pleafure, without the 
 Afiiftance of a proper Apparatus. 
 
 239. The other Furnace neceftary to the Afifayer 
 is called a melting Furnace , and is likewife com- 
 pared of Iron Plates. The Cavity of it may be 
 formed according to the elliptical Mould {Plat. III. 
 Fig. V). i st , Make an hollow Ellipfis, the Focus’s 
 12 Inches afunder, and the Ordinate 5 Inches long; 
 cut it off in both its Focus’s, that it may aflume the 
 Figure {Plat. III. Fig. VI). 2 dly , Then make in 
 this hollow Body, and near its lower Aperture, four 
 Holes, eight Lines in Diameter, and directly oppo- 
 fite {cc). 3 dly , Then fatten two flat iron-Rings (d)^ 
 almoft one Inch and a half broad, at both the upper 
 and the lower inward Edge of this oval Cavity ; and- 
 fill the Infide of it with fmall iron-Hooks, jutting, 
 out about fix Lines, and three or four Inches diftant 
 from each other. Thefe, together with the Rings 
 juft mentioned, ferve to fallen the Lute. Thus will 
 the Body of the Furnace be made : Only you muft 
 add at the outfide two iron-Handles {e e ), to be ri- 
 vetted on each Side of it, that it may be taken hold 
 of, and moved. 4 th17 , Then make the Cover of the 
 Furnace, which may be formed like the Part cut off 
 from the Ellipfis {Fig. V. a) (See Fig. VII). Let 
 this have an opening (b) made in it, four Inches high, 
 five Inches broad at its lower Side, and four Inches 
 at the upper *, and adapt to this an iron-Boor hung 
 on Hinges to fhut it clofe, and having at the Infide a 
 Border faftened to it, anfwering exatftjy to the Cir- 
 cumference of the Door, and as prominent inwardly 
 
 as 
 
Assaying Metals. 
 
 as the Thick nefs of the Lute to be applied to it re- 
 quires : (fee Fig. VIII). For the fame Purpofe, Jet 
 final J iron- Hooks be fattened to the In fide of this 
 Door, which is intercepted by the faid Border. And 
 left this Cover fhould be burnt within, by the Force of 
 Fire ; you mutt cover the Infideof it over with the 
 fame Lute mentioned before (§233.) for the Aflay- 
 oven : Therefore it mutt Jikewife be furnifhed with 
 a Ring and iron- Hooks to fatten the Lute ; as was 
 faid before (N a 3.) when we fpcke of the Body of 
 this Furnace. Befides this, you mutt fatten two iron* , 
 Handles (Plat. III. Fig. VII. c c) on the outfide 
 of this Cover. Then a round Hole mutt be made in 
 the Top of it, being three Inches in Diameter, pro- 
 longued into a hollow Tube (d) almoft cylindrical, 
 and a few Inches high, upon which the iron-Funnel 
 defcribed (§ 232. N° 8.) may, in Cafe of Necefiity, 
 be put after the Manner mentioned in the fame Place 
 when we fpoke of the Aflay-oven. After this, 
 
 the Lining of both the Body and Cover of the Furnace 
 within, is made in the fame Manner above defcribed 
 (§ 233). Moreover, you mutt make for this Fur- 
 nace two moveable Bottoms, viz. One to receive the 
 Allies, and admit the Air ; the other to ferve for 
 Reductions. The firft is made with an Iron P'ate, 
 formed into a hollow Cylinder, open at Top, and 
 to be Ihut at Bottom with an orbicular iron- Plate, as 
 with a Bafis, five Inches high, and of fuch a Diameter, 
 as that it may receive the inferior Orifice of the Body 
 of the Furnace (N° 2.) the Depth of half an Inch 
 (See Plat. III. Fig. IX.) Therefore, let an iron-Ring 
 (r) half an Inch broad, be fattened on the Infide of 
 the faid Bottom, and at the Dittance of half an Inch 
 from its upper Border, to fupport the Body of the 
 Furnace put into it. Again, let this Bottom have a 
 fquare Door, four Inches high, and as r*any Inches 
 broad ; that may be fhut clofely with a Door hung 
 on Hinges, that you may by means of it increafe or 
 diminifh the Draught of the Air, and thus govern 
 the Fire at pleafure. Then, on the left Side of this 
 
 G 2 Door, 
 
84 The Art of 
 
 Door, and at about half the Height of this bottont 
 Part, let a round Plole be made, one Inch and a half 
 in Diameter, to admit the Pipe of the Bellows when 
 Need requires. Next to this, let another bottom Part 
 be made of the fame Matter and Figure as the forego- 
 ing : Let it be like wife of the fame Diameter, but two 
 Inches higher, fo that it may be of the Height of feven 
 Inches. Likewife let it have round it a like iron- 
 Ring below its upper Border, to fupport the Body 
 of the Furnace to be received in it. But let a Hole 
 two or three Inches broad, and one Inch high ( Fig . 
 X. r), be cut out juft below this Ring, in the Side 
 of this bottom Part. Then let another round Hole 
 be made in the left Side of this firft Hole, fit to ad- 
 mit the Pipe of the Bellows (d). Further, let ano- 
 ther round Hole like the foregoing (e) be made on 
 the right, and at the Diftance of one Inch from the 
 Bottom. Then let the .whole Infide of this bottom 
 Part (the Fait above the Ring excepted) be overlaid 
 with Lute, and a Bed be made at the Bottom, of a 
 Figure like that reprefented by the Line (fg h ). The 
 Matter of which this is.made, is common Lute pulve- 
 rized, paTed through a Sieve, and mix’d with fuch 
 a Quantity of Dull of Charcoal, fifted in the fame 
 Manner, as that the Mixture being moiftened in the 
 fame Manner as the Alhes (§ 178), and prelfed 
 down, may at leaft be lightly coherent. Of this 
 Matter prelfed on the Bottom of the bottom-Part, a 
 Bed is made, like a Segment of a Sphere, having in 
 the Middle a fmall Cavity fomewhat lower, and 
 made extremely frnooth, after the Manner mentioned 
 before (§ 184.) when we fpoke of large Afh-Vef- 
 fels or Tells. 
 
 240. This Furnace (§ 239.) is chiefly fit for Fu- 
 fions, which may be made in it with and without 
 Velfels. When you are to melt with a Velfel, put 
 the Body of the Furnace (Flat. III. Fig. VI.) upon 
 the firft Bottom (F^. IX.) that has a Door to it to 
 open on Hinges ; introduce two Iron Bars (Fig. XI.) 
 through the Holes of the Furnace (Fig. VI. sc) put 
 
 upon 
 
• Assaying Metals. 85 
 
 upon them the iron-Grate {Fig. XII.) which you are 
 to introduce through the upper Mouth of the Fur- 
 nace : Then put in the Middle of this Grate a Brick 
 or fquare File, very fmooth every where, warmed, 
 and perfectly dry : Otherwife the Vefiels put upon 
 it, elpecially the large ones, are eafily fplit by the 
 moift Vapours coming out of it in the Operation. 
 Let the Height and Depth of this Stone be a fmall 
 Matter broader and higher than the Bottom of the 
 Crucible or Pot to be let upon it : For if it were lefs 
 high, the Bottom of the VefTel could not be fuffici- 
 ently warmed ; and if it were lels broad, the VefTel 
 might eafily fall from it. Then put upon this File 
 the VefTel containing the Matter to be melted, and 
 iurround it immediately with Coals on every Side, 
 which rnufl be ranged according to the Method pre- 
 fcribed before (§ 234). Then you govern the Fire, 
 by opening and lliutting the Door of the Afh-hole 
 {Fig. IX. b) : You excite it by putting the Cover 
 {Fig. VII.) upon the Body of the Furnace j and if 
 befides you put the Funnel (§ 232. N° 8.) upon 
 the cylindrical Mouth {d) of this Cover, the melting 
 Fire becomes ftill more violent. But if you more- 
 over introduce the Bellows through the Hole of the 
 bottom Part {Fig. IX. d ), and the joint of the Fur- 
 nace with the bottom Part, and the Door of the Afh- 
 hole, unlefs it can be fhut very clofe, being exa&ly 
 ftopt with thin Lute [or TVindjor Loam ] the Fire 
 thus excited by the blaft of the Bellows is carried 
 to the higheft Degree, and far furpafTes that which 
 may be made in a Smith’s Forge. Another Advan- 
 tage of this Method is, that theVeffels are not fo eafily 
 broken, becaufe the blowing of the Bellows cannot 
 affefl them immediately, and becaufe a Fire perfectly 
 equal is excited on every Side. One may eafily ex- 
 amine with this Apparatus , how Stones are affected by 
 the Violence of the Fire only. Now, if you have a 
 mind to perform any Operation without aVeffel, and 
 with a naked Fire } for Inftance, to melt and reduce 
 the Calxs or Scorias of Copper , Fin, Lead, and Iron , 
 
 • * G 3 or 
 
86 The Art of 
 
 or the Oars of thefe Metals *, the Body of the Furnace 
 mu ft be put upon the other Pedeftal, having a Bed 
 in it (Plat, III. Fig.X). However, you mu ft bef ore 
 this open with a Knife the oblong Hole (r), and the 
 round one (d) of this bottom Part, which are flopped 
 with the Lute flicking to the Infide. Then you ap- 
 ply at the round Hole (d) on the left the Bellows, in 
 inch Manner that the Nozel of it being directed ob- 
 liquely downwards, may blow ftrongly againft the 
 Bed (f g b) : By this Means, all the Afhes that fall 
 into the Bed are blown away, and the Strength of the 
 Fire determined to fuch a Degree, that all the melted 
 Bodies that fall into the faid Bed, remain in their 
 State of Fufion : And were it otherwife, the melted 
 Bodies would immediately wax cold, and adhere in 
 Grains to the Bed, whereas they ought to have melt- 
 ed into one Regulus. The oblong Hole in the fore- 
 part of this bottom-Part (r) ferves to difeover by 
 means of a Poker, whether the Matter in the Bed be 
 melted, or not : It ferves likewife to take away 
 through it whatever might flop the Bellows, and in 
 fome Cafes to take away the Scoria. Then you put 
 firft Coals into the Furnace, one Span high, and blow 
 them well with the Bellows, to make them burn, that 
 the Bed may be very hot before the Matter to be 
 melted is put into it : For if this is not previoufly 
 done ; the melted Mafs feldom runs into a Regulus> 
 but remains difperfed among the Scorias which foon 
 grow hard. The Bed being well heated, and frefh 
 Coals added to the Fire, put into it fuch Quantity of 
 the Matter to be melted, as cannot hinder the Fire 
 from being carried to the requifite Degree : Which 
 cannot be determined otherwife than by Experience : 
 Again, put frefh Coals, and upon them another 
 Quantity qf the Matter to be melted ; they may be 
 like Strata one upon another. But if the Mafs once 
 melted could not long fuftain the Strength of the 
 Fire; or if you had a mind to melt a greater Quan- 
 tity of Matter than what can be contained in the 
 Bed ; you muft open the round lower Hole (Plat. III. 
 
A s saying Metals. 87 
 
 Fig. X. e.) that you may make a Channel patting from 
 that Hole through the Lute, and reaching to the 
 fmall Cavity at the Bottom ot the Bed (g) : To this 
 Hole at the outfide, apply an earthen Difh like the 
 Bed within, or any other proper Recipient, ftirround- 
 ed with burning Coals, into which the Matter melted 
 running from the Bed through the Hole (Fig. X. e) 
 may be colle&ed ( Fig XIII. i). 'The other Particu- 
 lars hereto belonging, and to be obferved in fpecial 
 Cafes, will be more eafily recited, when we come to 
 the Operations hereafter to be explained in the practi- 
 cal Part of Allaying. 
 
 Scholion. In determining the inward Figure of the 
 Furnaces which are employed to carry the Fire to the 
 higheft Degree of Strength , you muft not he fo fir iff ly 
 exalt in giving it fuch a Figure , as that the reflected Rays 
 of the Fire may all he collected in one certain Point or 
 Line . For the Matter wherewith the Furnaces are 
 lined within , can never affume fo fmooth a Figure : Nay\ 
 if this Matter might affume it hy any Art , it would foon 
 he f polled again hy the Violence of the Fire. Befides , the 
 Rays of the Fire caft hy the Coals , do not fall with the 
 fame Regularity as thofe of the Sun and of Sound •, nor can 
 they of courfe he fo exaffly reflected towards the Body to 
 be changed , or the faid Matter itfelf being naked , is moft 
 commonly covered all over with Coals. On the other 
 Hand , a Focus collected within fo fmall a Compafs y 
 would he of almoft no Service *, hecaufe it can off only upon 
 a very fmall Part of the Body to he changed. It is then 
 enough to give the Furnace J'uch a Figure and Size , as 
 that it may i . admit a fuff c lent, though not fuperfluous 
 Quantity of Fuel for the Fire : 2. Float it may confine 
 the Heat of the Fire , fo as that it may neither all with 
 too much Liberty, nor he diffipated before it has ailed 
 firongly enough upon its Subjell : For which Purpofe 
 fome Sort of Cover muft he added p 
 
 241. The Furnaces hitherto (§ 231 to 240) de- 
 feribed, are fufRcient for the performing of docimaf- 
 tical Operations ftridtly fo called. But the Aftayer 
 mutt: alfo perform other Operations, fubfervient to 
 
 G 4 the 
 
88 The Art of 
 
 the foregoing : Such are the Diftillation of acid Spi- 
 rits, Cementations, Calcinations, & 5 V. which cannot 
 be conveniently done in the Furnaces above defcribed. 
 Therefore, as thefe Operations mod commonly want 
 a long and conftant Fire *, it will be very proper, for 
 this Furpofe, to conftrudt a Furnace called an Atha- 
 nor , which can contain as much frefh Fuel as will 
 keep up the Fire for many Hours together, and ad- 
 mits of a different, an accurate, and moil conftant 
 Regimen of the Fire. 
 
 242. Let then, i ft , a fmall fquare hollow Tower 
 {Plat. IV. Fig.l. a a a a) be conftructed of fuch 
 Atones , [or of Bricks made of tFindfir Loam ,] as may 
 .refill: the Fire , let the Sides of it be fix Inches thick, 
 .and forming a fquare Cavity within, of ten Inches 
 on each Side (bbbb). The height of it is deter- 
 mined, according as it is to keep up the Fire long, 
 without any Addition of new Fuel : Five or fix Foot 
 are molt commonly fufficient *. 2. At the bottom 
 
 of this Tower make an Opening (c), fix Inches broad 
 and as many Inches high •, hang to it an iron-Door, 
 being on every Side one Inch broader than the Open- 
 ing, and fuch as may flint it very clofe: For which 
 Purpofe, the external Edge of this Opening muft be 
 excavated all round in fuch Manner, that it may 
 form a Groove one Inch broad, into which the Edges 
 of the Door may be received. 3. At the diftance of 
 ten Inches from the Bottom of the Tower, put a 
 Grate (d) 9 made of prifmatical, quadrangular iron- 
 Bars, one Inch thick, and three quarters of an Inch 
 diftant from each other : Let alfo each of thefe iron- 
 Bars, be fo fituated with regard to the Tower, that 
 the two oppofite acute Edges of each may look per- 
 pendicularly, one downward, the other upwards, 
 that, by this Means, the Afhes may eafily fall into 
 
 * Thefe Towers may likewife be made of cart: Iron, in form 
 of a truncated Cone, fix Inches c.iameter in t^e Clear within at top, 
 and twelve at bottom, made with a Groove round the Top ior an 
 hcmifpherical Cover to be put upon it ; and the Bottom of the 
 jrori-Tower mufl be fet upon the. Stone or Brick- work, juft'above 
 the Opening at (c) defcribed at N°2. 
 
Assaying Metals. 89 
 
 the Afh-hole. 4. Make above this Grate an Open- 
 ing circular at Top (^), fix Inches high, feven 
 Inches broad, that may, as well as the Afh-holc 
 (N w 2), be opened and fliut with an iron-Door. 
 
 5. Adapt to the Top of the Tower an iron Cover (/), 
 exceeding the Aperture of the Tower all round two 
 Inches, and having a Handle, wherewith it may be 
 eafily taken away, and put on again. Thus you are to 
 make the Furnace called in Latin Furnus primarius. 
 
 6. Thencut out in any Side of the Tower, for Inftance 
 in the left, an oblong fquare Aperture, going up oblique- 
 ly toward the outfide (gg), four Inches and a half high, 
 ten Inches broad, having its inward inferior Edge, 
 one Inch and a half, or two Inches above the Grate 
 (d), that, by the intervening of this Hole, the Ca- 
 vity of this Tower may communicate with another 
 immediately to be deferibed. 7. Nearly over-againft 
 the fame Side of the Tower, make a Cavity with 
 Stones, whofe inferior Part muft be a hollow Prifni 
 (P/at. IV. Fig. I. h h h h ), fix Inches high, twelve 
 Inches broad, ending at Top in a Semi cylindrical 
 Arch (i i ) deferibed by a Radius of fix Inches ; that 
 by this Means, the Height of the whole Cavity be 
 twelve Inches in the Middle. Let this anterior Ca- 
 vity be totally open, though, when requifite, to be 
 fhut very clofe with an iron-Plate (£&&), whofe in- 
 ward Surface is to be conftru&ed, in the fame Manner 
 preferibed [Plat. III. Fig. VIII.) for the Hiding Door 
 of the melting Furnace, and then luted two Inches 
 thick within. Moreover, let there be in the Middle 
 of this Plate, a round Hole(P/tf/. IV. Fig. I. /), four 
 or five Inches in Diameter, and let the Circumference 
 of this Hole have an iron cylindrical Border made to 
 it, and prominent within ; that by means of it, the 
 Lining of Lute within may be fupported, and kept 
 from falling down eafily. Let a Notch one Inch 
 broad, and two Inches deep, be made in the outward 
 Circuit of the Aperture of this Cavity, to receive the 
 Extremity of the Plate that fhuts the Aperture. The 
 Hole of this Plate (/) either is fhut with a Stopple 
 
5>o The Art of 
 
 ( m ), or ferves to pafs the Neck of the Retort through. 
 This Plate likewife is fattened with two Boies ( nn)y 
 to be put horizontally with the iron-Hooks [ooo o ), 
 driven into the Wall near the Edge of the Aperture, 
 fo that one Bolt may fatten the upper Part of the 
 Plate, and the other the lower. -8. It is moreover 
 proper, that the fquare Aperture (gg), through 
 which the Fire enters from the Tower into the Cavity 
 hitherto deferibed (N a 7.) may be lhut and opened 
 at Pleafure with an iron-Slider : For if this is not 
 done, an excefiive Fire, employed fometimes by an 
 unexperienced Hand, cannot be fo eattly checked. 
 For this Purpofe, let a Slit half an Inch broad, and 
 eleven Inches long, be left in the Wall that confti- 
 futes the upper Part of the Cavity (N° 7), and is con- 
 tiguous to the Tower ; fo that it may exceed the 
 Length of the fquare Aperture (gg) a fmall Matter 
 on every Side, and reach before and behind into the 
 fmall Groove, going down along the perpendicular 
 Sides of the fa id Aperture [gg)<> and retain the 
 iron-Slider to be put into it to keep it fteddy. How- 
 ever, let this iron-Slider (6) be fix Lines thick, eleven 
 Inches broad, and five Inches high' ^ and let a Couple 
 of fmall iron-Chains [p p) be fattened on each Side of 
 its upper Edge, wherewith the Slider may be lifted 
 up and let down again. Therefore, let a Couple of 
 ftrong iron -Nails ** be drove into the contiguous Wall 
 of the Tower, perpendicularly over thofe Places, in 
 which the faid fmall Chains are fattened to the iron- 
 Slider, that any of the Links of the Chains may be 
 fufoended on them at Pleafure. Moreover, let the 
 upper Edge of the Slit above deferibed be entirely 
 fhut up with Stones and Cement, leaving only two 
 fmall Holes through which the fmall Chains may be 
 patted. 9. On the left of this (N° 7.) Cavity, and 
 at the Dittance of eight Inches from the Bottom of it. 
 Jet a fquare (q q q q) Chimney or Funnel be erefted 
 with Bricks , three Inches and a half in the clear, 
 four Foot high, and a fmall Matter convergent up- 
 wards, fo that the Diameter of it at Top may be 
 three Inches. This Funnel mutt be contrived to be 
 
Assaying Metals. 91 
 
 fhut clofely with an iron- Slider, having a Handle to 
 it (rr), which Slider muft move freely between a 
 double iron fquare Frame (s s s s) faftened in the 
 Walls of the Funnel, at fuch a Height from the 
 Hearth as fhall feem convenient to any Artificer. 
 
 10. Below this Chimney, let a fquare Aperture be 
 made, like the foregoing (N°6. gg), leading oblique- 
 ly up to the Bottom of another cylindrical Cavity 
 (u u u u)y which is eight Inches deep, defcribed by a 
 Radius of fix Inches, open at Top, and there con- 
 verging inwardly into a Border one Inch thick, and 
 fix Lines broad, defigned to fupport an iron- Pot. 
 Likewife, cut in the anterior Wall of this Cavity, 
 and at the upper Part of its Mouth, a Segment two 
 Inches and a half deep, five Inches broad, and (loop- 
 ing forward (vv), to receive the Neck of a Retort. 
 
 11. To this Cavity (N° io.) belongs an iron-Pot 
 (ww ) 9 eleven Inches broad, and about nine Inches 
 deep, which muft be incompaffed with an iron- Ring 
 (xx), one Inch broad, and faftened at the Diftance 
 of one Inch and a half from the upper Edge of the 
 Pot. Let a Segment (y) be likewife cut oft' the upper 
 Edge of this Pot, which Segment muft be four Inches 
 and a half deep, and five Inches broad : The iron- 
 Ring juft defcribed muft be bent all round the Edges 
 of this Segment. 12. Over againft the Aperture 
 (//) which communicates from the firft Cavity (N° 7.) 
 into the fecond (N° 10.) let another fuch Aperture (z) 
 be made two Inches diftant from the Bottom of the 
 fecond Cavity (N° 10.) perfectly like the foregoing 
 (gg t /), and communicating obliquely upwards 
 with a third Cavity (1 1 1 1), like, and equal to the 
 fecond cylindrical Cavity ( uuuu ) ; that the Fire 
 may pafs from the latter into the former. 13. In the 
 hinder Part of the Wall which makes the Aperture 
 juft mentioned (2), let a Chimney like the foregoing 
 (qqqq), and of the fame Height (2222) be 
 erefted, that may be fhut with a Slider like that (3). 
 14. Finally, on the left Side of the third Cavity 
 (1 1 1 1) let an Aperture be made in the fame Man- 
 ner 
 
9 Z "The Art of 
 
 ne r (4), and like the foregoing ones (gg tt z) 
 more remote however from the Bottom of the Cavity, 
 without a Paftage at the other Extremity, and com- 
 municating only with the Cavity of the third Chim- 
 ney (5 5 5), which mud be eredted in the fame Man- 
 ner as the two foregoing ones {q qq q. 2222). Thus 
 you will have a Furnace very proper for a great many 
 Operations. 
 
 243. We are now to fpeak of the ufe of the Alba- 
 vor juft defcribed (§ 242) *, and chiefly to mention, 
 to what Operations each of its Parts ferve in particu- 
 lar, and then how the Fire may and muff be governed 
 in it. 1. You muft put at the upper arched Door {e) 
 of the lower within, a Semi-cylindrical Muffel twelve 
 Inches long, which muft be introduced through the 
 Door : Which for this Reafon muft be of the fame 
 Height and Breadth as that Door, three Quarters of an 
 Inch thick, and open behind, being fhut there by 
 the hinder Part of the Athanor, as far as which it muft 
 reach. For this Purpofe, a Tie muft be fet upon the 
 Grate (d) to fupport the Muffel. Let alfo this 
 Muffel have fmall Pieces cut out near its Bafis, as 
 common Affay-muffels {Plat. II. Fig. Land II.) You 
 may put under this Muffel your Cement Pots, or fuch 
 Bodies as muft be calcined with a long violent Fire : 
 'Which can be done without a Muffel, though notfo 
 neatly. 2. In the firft Chamber {Plat. IV. Fig. L 
 bhhh i i) you may make the moft violent Diftilla- 
 tions with an open Fire : For Retorts or large Veffels 
 are introduced into it, after you have taken away the 
 Door {k k k ), and are put either upon the Hearth it- 
 felf of this Chamber, or upon a particular Support of 
 Stone. But you muft place thefe Veffels in fuch man- 
 ner, that their Necks may eafily pafs through the 
 Hole (/) of the Door, when put on again : For 
 which- Purpofe, they chufe a Support fomefimes 
 higher, fometimes lower, according to the different 
 Heights of the Veffels. When afterwards the Door is 
 put on again, and faftened with both its Bolts {n n\ 
 you muft clofe with Lute all the Chincks which lie 
 
 open 
 
Assaying Metals'. pj 
 
 Open about the Neck of theVefiel, and between the 
 Edges of the Door and the Entrance of the Chamber. 
 Then you apply to the Neck of the Veflef a cylindrical 
 Segment, ten or more Inches long : By means of 
 which the Heat and the boiling Vapours coming forth 
 are gradually diminifhed •, left the Recipient, which 
 is always chofen a Glafs Veflfel, fhould iplit. The 
 Recipient, which muft be united with the other Ori- 
 fice of the faid Segment, is fupported either by the 
 Pavement, or by a certain kind of Trivet, the Con- 
 ftnnftion of which is fuch, that it may be let lower or 
 higher by means of three Screws. 3. In this lame 
 Chamber, inftead of Diftillations, you may alfo make 
 Cementations, Calcinations, &V. In which Cafe the 
 round Hole (/) of the iron-Plate may be fhut and 
 again opened with a Stopple ( m ), that one may view 
 the Infide. 4. The fecond and third Cavities ( u u u u m 
 1 1 1 i)ferve chiefly to fuchOperations as are made in 
 Baths [orBeds] of Sand, AJloes , ox Filings. For Inftance, 
 you put into each of thefe Cavities a Pot ( w ) and you 
 flop with thin Lute or with Sand , which muft previ- 
 ously be moiftened, the Slit between the iron-Ring 
 (x , x), and the Border of the Cavity, upon which this 
 Ring refts. 5. Befides, you may alfo make in thefe. 
 two Cavities, Diftillations by a reverberating Fire, 
 as well as in the firft : Only the Fire is lefs violent in 
 thefe, though fufficient to extract Aqua Forlis . You 
 then take out the iron- Pot ( w ), and inverting it, you 
 put it upon the Mouth of the Chamber ; fo that the 
 Brim of the Pot, being the Depth of one Inch and a 
 half above the iron-Ring (x x), wherewith this Pot is 
 furrounded, may be received within the Mouth of the 
 Cavity, and fo that the Segment cut in the Pot (y) 
 may, together with the Segment cut out from the 
 Side of the Cavity ( v v ), form a Hole to let the Neck 
 of the VelTel through. 6 . All the Apparatus being 
 thus ready ; you firft introduce through the Top of 
 the Tower (b b b b ), a few burning Coals : And put 
 upon them fome of the unkindled Fuel of the Fire ; 
 that the Cavity of the Tower may, according as it is 
 
 thought 
 
94 Th e Art of 
 
 thought neceftary, be filled either entirely or only in 
 part. Then with all Speed you put upon it the iron- 
 Cover (/), and ftrew the Border of this on the out- 
 fide, with Sand or AJhes , which you prefs gently with 
 your Hands : For if you lhould negleft this Point, 
 all the Fuel contained in the Tower would be kindled, 
 and may endanger fetting the Houfe on Fire. 
 
 244. We fhall here annex a few general Rules 
 concerning the Regimen of the Fire in this Furnace: 
 For it is hardly neceffary to explain all Particulars, 
 fince Pradtice willeafily hint them to fuchas fhall be 
 ever fo little acquainted with Chemiftry. The Fire 
 may be made very ftrcng, in the firft Chamber 
 {Plat. IV. Fig. I. hh h h i i), when the Door of the 
 Afh-hole (r), and the Funnel (qqqq) of the Cham- 
 ber is quite open, and when the iron-Slider fufpended 
 with Chains ( 6 . p p) does not hinder the Fire from 
 paffing freely from the Tower into this Cavity. But 
 theclofer the Funnel is fhut, together with the Door 
 of the Afh-hole j the more the Violence of the Heat 
 diminilhes: And this will be foon effected, if the 
 iron-Slider fufpended with Chains, is letdown in part : 
 For the Fuel contained in the Tower, burns at leaft 
 as high as the Space between the lower Edge of the 
 iron-Slider and the Grate {d). Obferve befides, in 
 thofe Operations, wherein the round Hole ( 1 ) of the 
 Door is ftoptwitha Plug (m), that when the ftrong- 
 eft Fire is required, this Hole muft not be kept long 
 open : Becaule the Air rufhing violently through it, 
 foon cools the Bodies put into the Cavity. The Ope- 
 ration mentioned (§ 243.) may be performed in the 
 fecond and third Chamber, in, and at the fame Time, 
 and with the fame Fire, as they are in the firft Cham- 
 ber : For the Fire penetrates from the firft 'Cavity 
 into the fecond, and increafes, when the Funnel 
 (2222) erected on it is opened. Bur before you 
 do this, the Funnel of the firft Cavity muft be fhut 
 as much as that of the fecond is opened. By the 
 fame Means, you may hinder the Fire, which fervex 
 for the Operations made in the two firft Cavities, 
 
 from 
 
 3 
 
Assaying Metals. j 
 
 From going out through their Funnels, and you force it 
 out, on the contrary, through the third Cavity and 
 through its Funnel (5 5 5) ; that it may alfo a (ft upon 
 the Bodies placed in that Cavity. For the more the 
 Funnel ere&ed upon the third Cavity is open, the more 
 one or even both Funnels of the other two Cavities 
 muft be clofed. Thence it is plain, that you cannot 
 kindle the ftrongeft Fire in the third Cavity, unlefs 
 there be one equally flrong in the other two ; and 
 that on the contrary, the Heat in the third Cavity 
 may be rendered lefs, byclofing its Funnel ; though 
 it be violent in the others. The fame is true of the 
 fecond Cavity, with regard to thefirft. Finally, you 
 cannot make the ftrongeft Fire under the Muffel 
 placed within the upper Door (<?) of the Tower, un- 
 lefs you have an equal Fire in the firfl Cavity, which 
 Fire may confequently be increafed, by fhutting the 
 Door quite againft the Muffel (<?), and diminished, 
 by opening it ; there being mean while an equal 
 Heat in the firft Chamber, and in the following 
 ones. The Reft will eafily be learned by Practice. 
 
 III. Of the other Utenfils of Allaying. 
 
 245. Affayers make ufe of four Sorts of Tongs. 
 The firfl {Plat. IV. FigA\.) confifts of two iron- 
 Legs, two Foot long, as many Lines thick, joined 
 together in the Middle with a Rivet (a), fo as that 
 they may be fhut and opened fteddiiy. Let the fore 
 Part of thefe Legs wherewith the Veffels are laid hold 
 of, be curved on the infide (b) into a Semi -1 unarFigure ; 
 and let the hinder Part have two Rings (c) to manage 
 the Tongs with. This Tool ferves to draw the Tells 
 and fmaller Crucibles out of the Furnace. 
 
 246. The fecond kind of Tongs are made of a 
 Plate of Steel, hardened to a Spring-temper. Let 
 them be fix Inches long, almoft fliarp in the fore Part, 
 and well poiifhed (Fig. III). With thefe you take 
 up the metallick Grains remaining in the Coppels, 
 and other minute Bodies. 
 
 247. The 
 
p6 The Art of 
 
 247. The third kind of Tongs {Plat. IV. Fig. IV.) ard 
 adapted to melting Crucibles of a middle Size, three 
 Foot long, having very ftrong Legs, and as to the 
 reft made like the firft (§ 245) •, except that each of 
 the Legs muft be bent downwards at their Extremi- 
 ties, into a fort of Beak, fome Inches long, and one 
 Inch and a half broad *, that the Sides of the Cruci- 
 ble being fqueezed fail between thefe, it may be held 
 fteddily. Thefe Tongs are chiefly ufed, when Me- 
 tals melted in VeiTels of a middle Size, are to be 
 poured out into Moulds or Ingots. 
 
 248. The largeft Veflfels, containing a great Quan- 
 tity of Metal, are more eafily cracked in the Fire 
 than the fmall ones •, and their Cracks, if they do 
 not proceed from the Moiftnefs of the Tile fet under 
 them, are always found in the higher and larger Part 
 of the VeflTel, and moft commonly run from the Top 
 towards the Bottom, feldom tranfverfely. To be 
 able to take fuch Veflfels fafely out of the Fire ; you 
 muft have Tongs ftronger and longer {Fig. V.) than 
 the foregoing (§ 247). Let one of their Legs be 
 curved a fmall Matter at the End, and end in a ftrong 
 Semi-circle eight Inches in Diameter, and fo fixed, as 
 that it may make half right Angles with the Leg of 
 the Tongs (a) : Let the other Leg be curved in the 
 fame Manner at the End, and have at its Extremity 
 two Semi-circles like the foregoing, but fo fituated 
 among themfelves, and with regard to the foregoing, 
 that they may be diftant from each other about one 
 Inch, fo that there may be a Space in which the Semi- 
 circle of the other Leg may be received {b ) : The Efifedb 
 of this Structure is, that fmall and large Veflfels may 
 be managed with them. The Veflfel to be taken out, 
 is laid hold of a little below its upper Border, with 
 the curved Extremity of thefe Tongs, which muft 
 be firft heated juft red hot in the Fire ; and being 
 thus furrounded with a whole Circle, is fafely taken 
 out of the Fire. 
 
 249. When the Matter put into fmall Veflfels is to 
 be furred , you muft make ufe of an iron- Hook, 
 
 two 
 
 t 
 
Assaying Metals. 97 
 
 two Foot long, and one Line and a half thick {Plat. 
 IV. Fig. VI). It is proper to have two or three of 
 thefe Hooks, that is, as many as there are Veffels to- 
 gether under the Muffel, with the Matter to be flirred, 
 that you may not be obliged to ufe the fame Hook to 
 flir them all, and that the Matter in one Veffel may 
 not be fpoiled by Particles of that of another, which 
 may happen to flick to the Hook : For you have 
 not always Time enough to beat off with a Hammer, 
 or to file off the adhering Particles. 
 
 250. When Afhes mufl be removed from the Con- 
 vexity of the Muffel ; or. when Vacuities and Inter- 
 faces happen to be between the burning Coals, thac 
 render the Fire unequal *, you fometimes introduce 
 into the Hole of the Afiay-oven {Plat. III. Fig. I. p) 
 an iron-Rod(Ffo-.VII), wherewith you throw the Afhes 
 down, and make the burning Coals fall together. 
 
 251. The Matter in- the Crucible is to be flirred 
 with the iron-Hook {Fig. VIII.) 
 
 252. When Operations are to be made in the 
 larger kind of Tells, it is proper to have a flirring 
 Iron {Fig. IX.) four Foot long, with which you ei- 
 ther flir the Mafs, or take out the more clammy 
 Scoria's. 
 
 253. When the Grates are flopped, you clear them 
 with the Hook (Fig. X.) the Size of which is felf- 
 evident. 
 
 254. The fmall iron-Ladle {Fig. XI.) fix Lines in 
 diameter, well polifhed, and having a Handle two 
 Foot long, ferves to put Bodies, which mull be pre- 
 vioufly broken fmall, into the Veffels, efpecially fuch 
 Veffels as are under the Muffel. You mufl have a 
 larger hollow Ladle, whole Figure is fufficiently 
 known, to melt Lead, Tin , &c. in a gentle Fire. 
 
 255. A flrong Fire, if you look at it too long, 
 not only dims your Eyes, but alfo hinders you from 
 obferving diflinclly the feveral Changes of the Bodies. 
 To remove this Inconveniency, you mufl provide a 
 fmall Board, made of the driefl Wood, and one Foot 
 both in Length and Breadth ; that it may fcreen your 
 
 H whole 
 
The A rt of 
 
 whole Face. It has a Handle one Foot and a half 
 long : And a Slit is cut in the Middle of it horizon- 
 tally, one Line and a half broad, divergent towards 
 the other Side of the Board, to be turned againft the 
 Fire, and fufficiently extended each way ; that 
 there may be a larger Field forVifion, and both Eyes 
 may at once eafily diftinguiffi the Objects. We will 
 call this Inftrument a Screen , through the Slit of 
 which the Workman may fee, without any Appre- 
 henfion from the Fire, or from the Sparkles that fly, 
 and thus fafely contemplate his Objeft. ( Plat . IV. 
 Fig. XII.)' 
 
 256. To kindle the Fire, you mull befides the 
 fmall hand-Bellows, have a larger double Pair of Bel- 
 lows, three Foot long {Plat. V. Fig. I)., fuch as are 
 tifed by Golufmiths and Farriers. Let them be fup- 
 ported by a wooden-Frame, fo well fitted, as that 
 they may at Pleafure be raifed up, and let down be- 
 fore and behind, about the Height of one Foot. The 
 Structure of this Inftrument is fufficiently known, from 
 the above-mentioned Figure. If thefe Bellows lie by 
 unufed, they muff be kept ftretched, and every 
 Quarter of a Year rubbed with Neat 5 s-foot or Train 
 Oil : for, this being negledted, the Leather cracks- 
 foon, and the Ligaments grow ftiff y which occafions 
 a weak and unequal Blaft. 
 
 2 57; Some, in (lead of Bellows, ufe an Eolipyle , 
 which is a hollow Ball, made of a Plate of Copper, 
 and about fixteen Inches in Diameter, having an open 
 Pipe coming out of it, in the Direction of a Tan- 
 gent, and nearly fuch as is put on a large Pair of 
 Bellows.. If you fet this Veffel two thirds full of 
 Water, on the Fire, fo that the Water within may 
 boil ffrongly •, and then direct the Aperture of this 
 Tube towards the Fire to be blown *, a Blaft ruffies 
 out of it, and blows the Fire with great Force. 
 However, you muft forbear ufing this Inftrument, 
 when Copper is melted without a Veflel, and is 
 colledted in the Bed of the Furnace (§ 240) : the 
 more,, becaufe it is not uncommon to fee large Drops 
 
Assaying Metals. pp 
 
 of Water fpouting out of the Tube of the Eoli- 
 pyle *. 
 
 258. When fmall Pieces of Metal are to be melt- 
 ed ; the belt Way to do it, is to put them upon a hard 
 Piece of Charcoal, with a fmall PIollow made in it ; 
 and then diredt the Flame of a Lamp having a large 
 Cotton, upon the fmall Mafs of Metal to be melted, 
 by blowing it thereon with a fmall crooked Pipe : 
 For by this Means, Iron itfelf may be melted without 
 any Apparatus : Which fucceeds (till better, by ad- 
 ding Borax . Let the Pipe' with which this is per- 
 formed, be made of Copper, and let it have in its 
 bending Part, a hollow Globe one Inch in Diameter, 
 through which the Wind is to pafs, that the Moif- 
 ture of the Breath gathering into fmall Drops may 
 be colledled within the Cavity of this Globe, and not 
 reach the fmall Flame, and hinder the Adlion of the 
 Fire. Let the lefs Aperture of this Tube through 
 which the Wind comes out, be fo fmall, as to admit 
 hardly the fmalleft Needle. This is called the 
 vienting Tube, or Blow-pipe. 
 
 259. The Load-Stone is often fufficient to difcover 
 Iron : For want of this Stone, you muft haveRecourfe 
 for that Purpofe, to a long and tedious Apparatus . 
 Therefore, the A flayer ought to be provided of one 
 well armed, and keep it loaded in a dry Place. 
 
 260. You muft likewife be provided of an Anvil , 
 the upper Surface of which muft be perfectly well 
 polifhed, and about one Inch fquare, with a fmall 
 Hammer adapted to it : Both thefe muft always be 
 kept perfectly clean, left they fhould be fpoiled by 
 Ruft and Dirt, and contract Furrows : Otherwife, if 
 the Metal is vitiated, or any thing goes from it, it 
 hinders many Operations, efpecially that Separation 
 of Gold from Silver , which is called Quartation , and 
 ihall be explained in our practical Part. 
 
 * A very cheap and ingenious kind of Bellows have been newly 
 invented by Mr. Triewald , Captain of Mechanicks, &c, to the King 
 of Sweden, a particular Defcription of which is to be feen in Pbilof. 
 Trznf. N° 448, to which I refer the Reader. 
 
 H 2 
 
 261. How- 
 
fdcf The Art’ of 
 
 261. However, he that purfuesthe Art of A flay- 
 ing, can never be without an Anvil, large Ham^ 
 mers, a Vice, Files, Wedges, &c. but thefe being 
 fo well known, want no Defcription, 
 
 262. It remains, that we fhould examine and give 
 an exadt Defcription of the Affay Balance , and the 
 Manner of correcting the Defebts of it •, becaufe 
 it is an Inft rumen t of the utmoft Importance in 
 docimaltical Operations, and ferves to determine ex- 
 actly the Weights of minute Bodies. 
 
 263. Let this Balance be made of the' bell Steel : 
 For it may be conftructed much better of this Metal, 
 which mull be of the hardeft Kind, though fuffici- 
 ently tradlable, than of any other Matter. Befides, 
 Steel is not fo eafily fpoiled with Ruft, as Iron ; and it 
 is more apt than other Metals to take a perfedl Polifh, 
 which at the fame Time prevents the Ruff. Mean 
 while, let the Steel to be employed for this, be tem- 
 pered a. little fofter than a' perfebf Spring •, that it may 
 return to its State, when flightfy bent ; for it cannot 
 then eafily contrabl Faults, arid if it does, they may 
 be eafily mended. 
 
 264. The Structure of the A flayer’s Scales is 
 hardly different from that of common Scales, other- 
 wife than by its Nicety and Smallnefs. The longer 
 the Beam of it (Plat. V. Fig, II.) is, the more fmaft 
 Faults will be fenfible in it : Therefore, the longer 
 muff be pfefered to the fhorter. However, ten or 
 twelve Inches are a fufflcient length. Let the Thick- 
 nefs of it be fo very fmall, that two Drachms may 
 hardly be hung at either of its Extremres (#£), with- 
 out its bending. For the largeft Weight put upon it 
 feldom exceeds one Drachm. The whole Surface of 
 this Beam muff be altogether without Ornaments, 
 which do but increafe theWeight, and gather Filthr- 
 nefs. The Beam is fufpended in a Fork (Fig. III.) 
 the two Legs of which are fteel-Springs joined at Top, 
 but kept together below with a brafs, pliant Clafp 
 (Fig. IV) parallel, and two Lines and a half diftant 
 from each other. This. Clafp being taken off, and 
 
JOI 
 
 Assaying Metals. 
 
 ike Legs of the Fork being Hretched out, the Axis 
 of the Beam may be put into two Holes (a a) made 
 for that Purpofe at the Ends of the Legs, or be taken 
 away from them. Let a very fharp Needle (c) be 
 •fixed in the Head of the Fork, Handing perpendicu- 
 larly downwards, if the Fork is fufpended, and fo 
 long, as that it may almoH touch the Top of the 
 Tongue of the Beam (Plat. V. Fig. II. c) put into 
 the Fork, when in equilibrio. This Needle is the 
 Mark of the Equilibrium \ and that the Artift, who 
 Hands over-againH it, may be able to obferve this, - 
 the Legs of the Fork muH be broader in that Place, 
 nnd have an Opening two or three Lines (d) wide. 
 Flowever, this Fork may be adorned at Pleafure ; 
 provided the Motion of the Balance is not hindered 
 by fuch Ornaments. Then take -two Scales made of a 
 thin Plate of Silver , almoH flat, one Inch and a half 
 in Diameter, hanging on three fmall filk-Strings, al- 
 moH as long as the Beam, tied together at Top with 
 a Silver Hook, in Form of an S, and hang them to 
 the Extremities of the Beam. A fmaller* filver-Difh, 
 fcmewhat lefs than one Inch in Diameter, belongs to 
 each of thefe Scales (Fig. V). You firH put into 
 .thefeDiflies, with a Pair of Pincers, the Bodies to be 
 weighed, or with a Spoon or a fmall Shovel, when 
 they are pounded, and then you put them into the 
 Scales : Therefore, the fmall Difhes muH be perfectly 
 equal in Weight. We ufe them, that Bodies may be 
 more conveniently put into and taken out of the 
 Scales, and that thefe, which are vaHly thin, may 
 not be bent, foiled, and fo be rendered falfe by wip- 
 ing. 
 
 265. This Balance (§ 264.) is fufpended on a 
 moveable brafs or copper-Support, -which conflHs of 
 a Pedeflal (Fig. VI. a ), and of a Column fet upon 
 it ( b ) about twenty Inches high, at the Top of which 
 comes out at right Angles an Arm (c) one Inch long. 
 At the Extremity of this Arm, put a fmall Pully (d) 
 
 * Or if made of Steel blue’d over Charcoal they are lefs apt to 
 Wear. 
 
 h 3 
 
 three 
 
io2 The Art of 
 
 three Lines in Diameter : Put another at the Top of 
 the Column (<?), and a third near the Bottom of it 
 (/) : All which Pullies, muft turn very'eafily on their 
 Axis. At the Diftance of one Inch and a half below 
 the upper Arm, let another Arm one Inch and a half 
 long (g) come out of the Column at right Angles, 
 having a Hole through it (jb) two Lines long, a 
 quarter of a Line broad, and placed perpendicularly 
 below the Pully of the upper Arm (/), to receive a 
 fmall Plate (i), one Inch and a half long *, and of fuch 
 Breadth and Thicknefs, as that it may freely move 
 up and down, and yet not have too much play within 
 the Hole. Moreover, let this Plate have a fmall 
 Hook at each Extremity. 
 
 266. And as fuch a Balance is very ticklifh, and 
 will hardly hand ftill in the open Air, and becomes 
 falfe, when fpoiled with Duft : It muft be put together 
 with its Support into a fmall Cafe, having Glaftes at 
 Top and all round it, that you may fee what is with- 
 in. The Size of fuch a fmall Cafe is evident *, and 
 muft be fuch, as that the Balance fufpended on its 
 Support, may be conveniently placed and turned in 
 it. The Windows of the right, left, and fore Sides 
 of it, muft be made in fuch Manner, that they may 
 be opened and lhut without any great ftiaking of the 
 Cafe. The Bafts of it muft be a Draw, two Inches 
 high, equal in Breadth to the Cafe, jutting out in the 
 fore Part four or five Inches beyond the Front of it, 
 and eafy to be drawn out and thruft in again. In 
 this Draw you muft put the Weights, inclofed in 
 their little Partitions, a fmall Pair of Pincers, a fmall 
 Shovel, or a Spoon, wherewith to put the Powders 
 into the fmall Difhes of the Scales, and other Things 
 if any are requifite : By which Means, you will have 
 all thefe Inftruments at hand, and keep them perfectly 
 clean (See Plat . V. Fig. VII.) 
 
 267. The apparatus we have hitherto deferibed 
 (§263 — 266), isdifpofed forufe in the following Man- 
 ner. Pafs a Silk String over the three Pullies of the 
 Support (Fig. VI. ef d ) 7 and tie it at its upper Extre- 
 mity 
 
Assaying Metals. 103 
 
 mity to the fmall Hook of the Plate (z), which is 
 then introduced into the Hole of the inferior Arm {h). 
 Then you put the Support (§ 265.) in the Middle of 
 the fmall Cafe (§ 266), and you pafs the other Ex- 
 tremity of the filk-String below, through a Hole 
 bored in the Middle of the lower Border of the Frame, 
 containing the Window in the fore Part of the Cafe, 
 and fallen it to a Weight of a few Ounces (K), re- 
 duced into a cubick Form. Next to this, you muft: 
 fufpend the Fork of the Balance {Fig. Ilf.) on the in- 
 ferior Hook of the Plate (z) Fig. VI). By this Means, 
 if you move backwards and forwards, the Weight 
 faftened to the String (K), placed upon the Top of 
 the Draw, that juts out beyond the fore Part of the 
 Cafe, the Balance within is either lifted up, or let down. 
 But you muff put the Bodies to be weighed, and the 
 Weights themfelves in the fmall fi Iver- Difhes (Fzg\V), 
 and you put thefe, when loaded, into the Scales, through 
 the fide- Windows, which muft be opened for that 
 Purpofe. When any thing is to be added to, or taken 
 out of them, you do it with the fmall Pincers, or, if 
 it is Powder, with the fmall Shovel or Spoon. How- 
 ever, you muft let the Balance down, every Time 
 any thing is to be added, or taken away *, that the 
 Scales may reft upon the Bottom of the Cafe : But 
 then you muft fhut the Windows, before the Balance 
 is lifted up again, efpecially if the Air is not perfedl- 
 ly calm {Plat.V . Fig. VII.) 
 
 268. To fee whether the Balance (§ 264.) is juft, or 
 no, you muft interchange the fmall Difhes. That is, 
 you firft put the faid Difhes into the Scales, and lift up 
 the Balance, to fee whether it is in equilibria , or 
 not : If not, you will procure the Equilibrium , by 
 adding granulated Lead to the 1 ighteft Difh. This 
 Equilibrium once obtained, you put the Difhes in the 
 Place of one another, and again lift up the Balance : 
 If it keeps ftill in equipoife, it is a Sign of its being 
 juft : But if after the Permutation of the Difhes, vou 
 no longer find the Balance in equilibrio ; it is a fare 
 Sign of its being faulty. Moreover, when the Ba- 
 
 H 4 lance 
 
104 The Art of 
 
 lance being elevated, you fee the Beam moving in the 
 Fork, not only up and down, but alfo fide-ways, 
 this like wife .Thews a Defedt in the Balance. You 
 muft, befides, reckon it one of the Faults of your 
 Balance ; if, when having lifted it up, and put it in 
 equilibria') you lower one of the Scales with your 
 Finger, and this does not return to its Equipoife, 
 when the Finger is removed : If this be the Cafe, 
 your Balance may indeed be right, as to the Length 
 and Weight of the Arms of the Beam, but it can 
 hardly be reftored to an exadt Equipoife, whence it 
 is lefs fit to weigh any thing exadlly. 
 
 269. But it is not enough to have known whether 
 a Balance was juft or defedtive : We muft likewife be 
 able to corredt the Faults detedled in it. You muft 
 then above all know the Caufes of the Defedts *, that, 
 by removing them, the perfedl Exadinefs defired may 
 be obtained. Nay, the Allayer ftands in greater 
 Need of knowing how the Faults of a Balance are 
 corredled, than the Manner in which the Balance is 
 made ; becaufe, by mending, he at laft obtains the 
 fcrupulous Exadinefs requifite in docimaftical Ponde- 
 rations. Let us then take this Point in hand. Firft, 
 it is a teafing Fault in a Balance, when it cannot ei- 
 ther be reduced to a Situation perfedlly horizontal, 
 or, when being reduced to it, and either of its Scales 
 being lowered, it is not immediately reftored to its 
 firft State, by the Removal of the Power that lowers 
 it. This Thews that the Axis upon which the Beam 
 of the Balance is fupported, is in the fame horizontal 
 Line with thofe Points to which the Powers are ap- 
 plied. To corredl this, take the Beam out of the 
 Fork, and with a Pair of Pincers, lower a little the 
 ringed Extremities {a b) cf the Arms •, with fuch 
 Evennefs however, that a Thread extended from one 
 Ring to the other, along the Length of the Beam, 
 may be on either Side at right Angles with the Tongue 
 of the Balance, which muft be proved by applying to 
 it a Square. 2. But if the Balance put in equilibria , 
 does not eafily change its Situation, with a very fmall 
 
 Weight 
 
Assaying Metals. 105 
 
 Weight added on one Side ; it fhews, either that the 
 Axis is not fufficiently acute, or that the Holes of 
 the Fork in which the Axis turns, being too nar- 
 row, refill to the Motion of it ; or, in fhort, that 
 the Axis is placed too high above the horizontal 
 Line, drawn from one of the Rings of the Arms 
 to the other. The two firft Faults are very 
 eafily mended, by either fharpening the Axis, or 
 widening the Hole. As to the third Defctl, as 
 the Axis cannot be removed, the Rings mult be 
 elevated : Which may be done in the Manner 
 
 mentioned (N° 1). 3. It is a Fault in a Balance, 
 
 when being equipoifed, it does not Hand the inter- 
 changing of the Powers ; or if the Powers being re- 
 moved, it declines on either Side : This fhews, when 
 the Scales and Difhes are equiponderous, that either 
 one of the Arms of the Beam is fhorter than the 
 other, or the one out-weighs the other, or that the 
 Defeat proceeds from both Caufes. Therefore, to 
 corredl it, you muft firft lift up the Balance unload- 
 ed, and if it is not in equilibrio , let the Equipoife 
 be reftored, by putting Grains of Lead into the 
 Scale. Then put the fmall Dilhes into the Scales, 
 and if the Balance does not remain in equilibrio , . let 
 the Equilibrium be again reftored, by putting granu- 
 lated Lead into the fmall Difh, not into the Scale. 
 This done, if the Difhes can be interchanged, without 
 altering the Equilibrium it fhews, that you muft 
 take as much matter from one of the Scales, with a 
 Whetftone or a File, as you have put Grains of Lead 
 in the other, to obtain an Equilibrium : For one is 
 heavier than the other : Which Inequality is moft 
 commonly occafioned by Dirt, orRuft. But if you 
 cannot interchange your fmall Dilhes, and preferve an 
 Equilibrium , you may be fure that one or the other 
 of the Extremities of the Beam, and even that which 
 goes down after the interchanging of the Dilhes, is 
 more remote from the Axis than the other. Where- 
 .fore, this Arm muft be made fhorter: Which is done, 
 -by prefiing foftly, and a fmall Matter towards the 
 
 Axis, 
 
io6 The Art of 
 
 Axis, with a delicate Pair of Pincers, the fmall 
 ringed Bow which is at the Extremity of this Arm : 
 Taking care mean while, not to raife or lower at 
 the fame Time the Extremity of the Beam : Other- 
 wife it would be but fuhftituting the firft (N° i.) or 
 the fecond (N° 2.) Fault, to the Fault corrected. 
 Therefore, this being done, take away the fmall 
 Difhes, and, by taking fomething of the granulated 
 Lead, which you had put before into the other Scale, 
 reftore the Equilibrium , which had been wanting all 
 the while : For then the Arm of the Beam which had 
 been raifed before, will certainly be lowered. Then 
 again put the fmall Difnes into the Scales, and if you 
 do not find an Equilibrium , reftore it, by putting 
 granulated Lead into either of the Difhes : Which 
 done, interchange the Paid Difhes *, and you will fee 
 from the Want of Equilibrium , which of the Arms of 
 the Beam is ftill longer than requifite : If you find 
 it to be fo ; mend the Fault as before, that is, by 
 fhortening the lowered Arm, or by lengthening that 
 which is raifed, having always an Attention to the 
 Cautions already prefcribed. Repeat thefe manual 
 Operations over and over, till the Balance unloaded, 
 and equipoifed either of itfelf, or by Means of granu- 
 lated Lead put into either of the Scales, may undergo 
 the interchanging of the fmall Difhes, without difturb- 
 ing the Equilibrium : For then both the Arms of the 
 Beam will be of equal Length. If after that, the firft 
 Defect, that confifted in the Inequality of the Scales, 
 remains ftill, it may be removed in the Manner above- 
 mentioned. The Caufes of the other Faults being 
 more fenfible, may of courfe be more eafily mended : 
 Therefore, we leave it to the Skill of the Artificer, 
 to detect and correct them. 
 
 270. I fhal], in favour of fuch as would try to 
 make the Scales themfelves, add the following Di- 
 rections. 1. The whole Beam together with its 
 Tongue, muft be cut out of one and the fame Plate 
 of Steel : For any foldered Bit may be eafily fepa- 
 rated, becaufe this Beam muft be worked with extra- 
 ordinary 
 
Assaying Metals. 107 
 
 ordinary Delicacy. 2. The Axis being a very fine 
 Peg, mu ft be fattened with Solder, in the Hole 
 pierced in the Center of the Beam : Which is very 
 eafily obtained, if you cover over with a thin Lamina 
 of Gold, the Middle of the Axis which is to go 
 through the Center of the Beam : For Steel may be 
 foldered with Iron by means of Gold, in a gentle Fire ; 
 otherwife you mutt ufe a more violent Fire, whereby 
 the Axis is eafily dettroyed. 3. To temper the Beam 
 you mutt firft, when it is white hot, extinguilh it in 
 cold Water, and then rub it all over with 0 / 7 , and 
 keep it upon the Fire, till the Oil is burnt and con- 
 fumed : And if you do this two or three Times over 
 in the fame Manner, you will at laft give it a lpring- 
 Temper. However, you mutt do this, before the 
 Beam is quite worked. Next to this, you mutt make 
 again the Extremities of your Beam white hot, at a 
 Candle ; that being made a little fofter by this Means, 
 they may be bended without Difficulty •, and in Cafe 
 of Neceffity be lengthened or fhortened, to be cor- 
 rected. 
 
 271. If the Fault of the Balance confitts in the Ine- 
 quality of the Arms, as to their Length orWeight, and 
 if it is good in any other Refpeft, and you have not 
 Time to mend the Fault previoufly : You may ufe it 
 mean while, in the following Manner. Put the Bo- 
 dy to be weighed in one of the Scales, and put in the 
 other. Weights to an equipoife : Then mark exa&ly 
 the Sum of the Weights : And then interthange the 
 Powers, without however changing the fmall Diffies : 
 Mark likewife the Sum of the Weights, to be added 
 for the procuring of an Equipoife, which will cer- 
 tainly be different from the foregoing Weights : Then 
 multiply the Quantities of both thefe Weights by 
 each other, after having firft reduced them into very 
 minute Parts, as for inftance into Drachms : And 
 finally, extradl the fquare Root of the Produce of this 
 Multiplication, which will mark the true W eights of 
 the Body in queftion. 
 
 272. As the Affayer’s Scales hitherto (§ 263 — 271.) 
 
 deferibed. 
 
io8 The Art of 
 
 defcribed, and made as delicate and nice as is re- 
 quifite, cannot without Detriment, bear above two 
 docimaftick Centners, or Drachms ; you mull have 
 another fomewhat ftronger Balance, that may be 
 loaded with a few common Ounces, which ferves to 
 weigh the feveral Fluxes , the Additions , Lead and 
 ■Ores, efpeciall.y thofe of Copper , Iron , Lead , Fin,, 
 '&c. Let this likewife be made exaft, and fufpended 
 on a Support. 
 
 273. As many kinds of JVeights are ufed by Ar- 
 tificers .that work in Metals, to weigh them, fo many 
 muft the A flayer have at hand, becaufe he is much 
 more taken up with his Art than any, and muft not 
 be obliged to confume his Time in arithmetical Cal- 
 culations, for the Reduction of his Weights. But 
 the Weights which are properly called Allayer’s 
 Weights, are a thousand times fmaller than common 
 ones •, becaufe, the Portions of Metals or of Ores 
 examined in docimaftical Operations, are extremely 
 fmall. 
 
 274. The Metallurgifts, wlio extradl Metals out 
 of their Ores, ufe a Weight divided into a hundred 
 equal Parts (they call them Pounds ) the whole of 
 which they call a Centner , or an hundred Weight. 
 The Pound is divided into thirty two Parts called 
 half -Ounces , (in German ; the half Ounce again, 
 is divided into two Quarters, and the Quarter into as 
 many Drachms, called in German £UuiltlniI. There 
 is hardly any further Subdivifion of the Weights, 
 ufed in large Works. However it is proper, that 
 the Allayer fhould alfo have a Drachm divided into 
 two equal Parts ; becaufe he muft fometimes have 
 regard to fuch minute Quantities. Finally, to be 
 able to weigh all the Parts of a Centner juft mentioned, 
 you muft have at hand as many different Weights, as 
 are requifite, to compofe from them each of the Parts 
 of the Centner* 
 
S ' ~ 
 
 Assaying Metals. 109 
 
 r 
 
 2 
 
 o 
 
 o 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 Toil muft therefore have at hand, 
 
 A Centner weighing — ioo^ ] 
 A Weight — 64 
 
 > Pounds. 
 
 9 A Weight | Pound 
 
 f. 16) 
 
 f. 8/ 
 
 f. 4S Loths. 
 f. 2^ 
 f. l) 
 
 14 A Weight J Loth. f. 2> 
 
 1 5 £ f. 1 > Drachms. 
 
 16 t f - P 
 
 275. The Divifions and Denominations of Weights 
 hitherto given (§ 274.) are equally ufed by Aftayers 
 and Metallurgifts ; with this Difference however, that 
 the Centner of Metallurgifts contains one hundred 
 common Pounds ; whereas that of the Aftayers con- 
 tains only one real Drachm, to which the other Parts 
 are afterwards proportioned. 
 
 276. As then the docimaftical Weights are divided 
 to fuch a Degree of Minutenefs (§ 275), and fo vaftly 
 different from the common ones ; the Affayer muft 
 be able to make them with his own Skill, which 
 we muft now teach him how to do. 
 
 277. Thefe Weights (§ 274.) are made of fquare 
 filver * Plates, of fuch a Size, as that the Mark of 
 each different Weight, may be put upon them. Let 
 
 * If you do not care to bellow Silver on your Weights, thin Pieces 
 of fine Solder will do as well. 
 
 US 
 
i io The A et of 
 
 us firft take for a Bafis one Weight, being about two 
 thirds of a common Drachm, and Jet it be marked 
 (64. lb). Then have at hand granulated Lead, 
 walked clean, well dried, and fifted very fine : Put 
 as much of it in one of the fmall Difhes of the Afiay- 
 balance, as fhall be neceffary to equipoife the Weight 
 (64. lb.) juft mentioned, which is in the oppofite 
 fmall Difh. This done, take out of the Difh the 
 filver- Weight, and put in the Room of it half of the 
 granulated Lead •, fo that a perfect Equilibrium may 
 be obtained. Then pour the granulated Lead out of 
 each fmall Difh, and inftead of it put another filver- 
 Weight already made, like the foregoing, being a 
 little heavier than half of it, and mark it (32. lb.) 
 taking great Care, that not the minuted Part of the 
 granulated Lead remain in the fmall Difh. If this 
 fecond filver- Weight exceeds by much that of the 
 granulated Lead being ftill in the other fmall Difh ; 
 you muft take a little from it, with a delicate thin 
 File : And if it exceeds it but little, ufe a fmall 
 Whetftone, that will rub off* but a little at a time, 
 comparing your Weights pretty often, till you render 
 this perfectly equal to the granulated Lead. Then 
 interchange the fmall Difkes *, that, if the Balance 
 has pofiibly been vitiated, or any Error committed, 
 it may necefiarily appear. Go on in the fame Man- 
 ner, till you have made all the fmall Weights. But 
 if you finally will have one entire hundred ; add to 
 the Weight 64. lb. One of 32, and another of 
 4. lib ; and taking them together, make one larger 
 Silver Plate of equal Weight with them, and mark it 
 (100 lb.) Thus you will have a fufficient Number 
 of Weights, out of which you will be able to com- 
 pofe all the Parts of the Hundred, by intermixing 
 them. 
 
 278. You will often want a centner- Weight larger 
 than the common Drachm, which may likewife be 
 eafily made of one Size, according to the Rules (§ 2 77.) 
 above prefcribed. However, it is proper that this 
 Weight be proportioned to the fmaller Centner, and 
 
 to 
 
Assaying Metals. hi 
 
 to its Parts ; that for Inftance it fhould be exaCtly 
 the Double or Quadruple : By which Means the lef- 
 fer Centner, together with its Parts, ferve to deter- 
 mine alfo the Parts of the larger. 
 
 279. You will find out, whether the Weights are 
 made exaCt, or have contracted Faults in the ufing, 
 by comparing the Centner,, or its larger Parts, with 
 the leffer ones : For Inftance, the whole Centner,. 
 
 -with 64, 32, and 4 lib. the 64 lib. with 32 lib. and 
 with two 16 lib. and fo on. It is then proper to have 
 two Weights of each peculiar Part of the hundred lb. 
 Which is the more eafily done, becaufe in the making 
 of the Weights, it is a moft tedious Work to deter- 
 mine the right Quantity of the granulated Lead 1 
 Which being once done, it is an eafy Matter to pre- 
 pare two filver- Plates equipoifmg the fame Quantity 
 of granulated Lead, 
 
 280. Put thefe Weights (§ 277, 278.) into a final! 
 Cafe or Box, that may be fhut, and in which there 
 are for each of them proper and neat fmall Partitions 
 contrived, and lined with Leather or Cloth : That 
 every one may immediately be found, and that many 
 of them being put together in one and the fame Par- 
 tition, may not rub again ft and wear out each other, 
 whereby they are very eafily fpoiled. 
 
 Scholion. In the making of the Weights (§277.) fo?ne' 
 life to determine the fmall eft of them fir ft, and then to ar- 
 rive at the hundred lb. by multiplying \ but then an in - 
 fenfible Error committed in the fmalleft Weight , becomes 
 very confiderable , as it is multiplied over and over , and 
 you lofe all your Labour. On the contrary , if you firft 
 determine the largeft Weight , as fome ufe to do *, you have 
 much ado afterwards to find out the fmalleft : For it is 
 hardly pofftbie to proceed with dividing into two , from 
 100 to 25, and more. This is the Reafon why 1 begin 
 from 64 lb. not making any Weights of 5 o, or 25 lb ; 
 becanfe they may eafily be obtained by the Combination of 
 the others . , 
 
 281. The common hundred Weight varies accord- 
 ing to the different Places : For it often contains more 
 
 5 than 
 
m The Art of 
 
 than ioo lb. and moft commonly it is carried to one 
 hundred and ten. Therefore, when the docimafticai 
 Operations mud be adapted to the Proportion of the 
 common Centner, you muft add as many Pounds to 
 the docimafticai ioo lb. as the common hundred 
 Weight contains above one hundred Pounds. 
 
 282. The Workmen, to determine the Weight of 
 
 Silver and Gold , ufe one half Pound, or a Weight of 
 eight Ounces, which they call Mark , and divide it 
 varioufly. To afiay filver-Coins, and Copper mixt 
 with Silver , they divide the Mark into 16 half 
 Ounces, The half Ounce into four Drams, 
 
 (HutntletJt) j the Drachm into four Penny-weights 
 (dwt), (gfenmge) ; and finally, the dw fc into two 4 
 dwt , (feller) » this Weight is called Nummularium , 
 pfennig or Penny-weight. 
 
 283. It will not be neceftary to have at hand the 
 Weight juft deferibed (§ 282.) if you can fubftitute to 
 it a Weight of fixteen Pounds of the docimafticai 
 Centner (§ 274, 277.) for if this reprefents the entire 
 Mark ; in that Cafe each Pound of it will be equal 
 to half an Ounce of the Weight (§282.) eight half 
 Ounces will be equal to one Drachm, two half Oz . 
 equal to one dwt, and at laft one half Ounce be equal 
 to one { dwt. 
 
 284. To temper Silver with Copper , the Mark is 
 likewife divided into fixteen half Ounces, as (§283.) 
 But the half Ounce is then divided into eighteen Parts, 
 which they call Grana or Grains, but Georg . Agricola in 
 better Latin calls them Quaternas S'tliquas , and finally 
 the Grain is divided into four Quarters. Therefore 
 in this Cafe, the greateft Weight is the Mark , or 
 half Pound, which weighs about half a Dram of the 
 common Weight : The fecond is half-Ounces, the 
 third is four ; the fourth two the fifth one ; the 
 fixth one half of this, or nine Grains ; the feventh 
 fix Grains, the eighth three, the ninth two, and the 
 tenth bur one Grain ; the eleventh one half Grain, 
 and finally the twelfth one quarter part of a Grain. 
 There is no peculiar Obfervation to be added con- 
 cerning 
 
Assaying Metals. 113 
 
 ccrning the making of Weights of this kind, befides 
 what was faid before (§ 277, and following). For this 
 is as commonly ufed as the foregoing (§ 282), efpe- 
 dally in Germany. 
 
 285. In Holland , inftead of the Weights defcribed 
 (282, 284). A flayers ufe the Marca Nummulana , 
 or Mark of the Mint, which is divided into twelve 
 Penny-weights, and each Penny-weight is fubdivided 
 into twenty-four Grains. Now this Mark of the Mint 
 weighs a common half Dram, which is the fir (l 
 Weight ; the fecond is fix Penny-weights, the third 
 three, the fourth two, the filth but one Penny-weight, 
 the fixth twelve Grains, the feventh fix, the eighth 
 three, the ninth two, and the tenth one Grain. 
 They make no further Subdivifion. 
 
 2 86. To temper Gold with Silver and Copper , they 
 ufe the Caract- weight ( Carath-Gewicht ), the Mark 
 of which is divided into four and twenty Caradts 
 ( Caratk ), and the Caradt into twelve Grains. There- 
 fore the firft Weight is here, as in the foregoing, a 
 Mark of four and twenty Caradls *, the lecond is 
 twelve Caradls, the third fix Caradls 3 the fourth 
 three ; the fifth two •, and the fixth one •, the feventh 
 one half Caradl or fix Grains *, the eighth three Grains, 
 the ninth two, and the tenth one Grain. 
 
 Scholion. I. Befides the Varieties of Weights, hitherto 
 (§ 273, and following) mentioned, there are ftill a great 
 many others different from them : But it is not our Bufi- 
 nefs here , to treat of them all in a ??iore particular Man- 
 ner. See G. Agricola. Lib. VII. De re Metallica. 
 
 Scholion. II., As the Dutch Mint-Mark (§285), the 
 German Grain -Mark (§ 284), and the Caradl- Mark 
 f§ 286), are each divided into two himdred and eighty 
 eight Grains *, it is felf -evident, that you need have but 
 one of thefe three ; for twelve Grains of either of thefe 
 Weights make one Penny -weight, eighteen make one half 
 Ounce, and four and twenty ?nake one Caradl. 
 
 287. Any Metal whatfoever, when pure, mufthave its 
 fpecifick Colour, that diftinguifhes it from the Reft. 
 But Metals being the moft opaque of all known Bo- 
 
 I dies. 
 
1 14 The Art of 
 
 dies, the fpecifick Colour of every one appears very 
 diftindtly, when you rub it againft a very black hard 
 Stone. If then the Colours of two or 'more Metals to 
 be allayed, are expreffed by large lively Spots made 
 near each other in the fame Plane, after having rubbed 
 them againft the Surface of fuch a Stone, you will by 
 that Means eafily difcern their Difference, or their 
 Likenefs. 
 
 288. The Stone adapted for this Ufe (§287.) is 
 called the Touch-ftone \ which muft have the following 
 Properties. 1. It mull be of the deepeft Black, left 
 the Tindture of the Metal fhould be hindered, by 
 fpurious Rays of Light fhining between them. 2. It 
 muft be capable of being pretty well polifhed : For 
 when too rough, the Colours of the Metals rubbed 
 againft it, cannot be neatly perceived : And if it is 
 too fmooth, the Metals are but faintly and flowly 
 fcraped by it, efpecially Gold. 3. It muft be neither 
 too hard, nor too foft : For Tripoly , Coal-duft , and 
 Tin- a/he s rub off the lmall metalline Crufts : So that, 
 in a fbortTime this Stone, though ever fo hard, ac- 
 quires too great a Smoothnefs : And when it is too 
 foft, it is eafily ground into a fine Duft, and con- 
 tracts Furrows. Therefore, black rough Marble •, 
 or black foft River- Pebbles, are excellent lor that Ufe. 
 They muft be made into a quadrangular Prifm, a- 
 bout one Inch thick, and two or three Inches long ; 
 which is the moft convenient Figure for that Pur- 
 pofe. 
 
 289. The Metals which are tried in the Manner 
 mentioned, are Gold , Silver , Copper , when pure, or 
 mixt among themfelves by Fufion, in many different 
 Proportions. But in order the better to find out the Pu- 
 rity and various Mixtures of thefe Metals, whenever 
 they are to be examined •, the Maffes to be tried are 
 compared with fmall pureMaffesof the fame Metals, or 
 of Metals mixt in a known Proportion, and defignediy 
 prepared for that Ufe, which are called Touch-need- 
 les. Now the aforefaid Metals, both thofe pure and 
 thofe mixt in different Proportions, are made into 
 
 Lamina’s 
 
Assaying Metals. 1 1 j 
 
 Lamina’s one Line broad, one fourth Part of a Line 
 thick, and one Inch and a half long, upon each of 
 which you engrave a Mark, indicating their Purity, 
 or the leveral Mixtures of the Metals which they are 
 made of. 
 
 290. Let us now fhew the Manner of making 
 tHele Touch-needles (§ 289) ; and fir ft of all the 
 Silver ones. Thele mult be tempered only with Cop- 
 per : But the Proportion is determined by the Mark 
 (§ 284.) divided into half-Ounces and Grains. There- 
 fore, you muft ufe for that Purpcfe one Mark of fuch 
 a Weight, as that it may conftitute a fuffic-ient Mafs 
 of Metal for the making of one Needle : Let it then, 
 weigh, for Inftance, one whole Dram. Then weigh 
 fuch a Mark of the pureft Silver, wrap it in a frnall 
 Paper, upon which you will write fixteen half 
 Ounces ; which will fignify, that the whole Mark of 
 this Metal is the pureft Silver. Make the firft Needle 
 with this Mafs. Next, weigh fifteen half Ounces of 
 pure Silver, and one half Ounce of pure Copper * 
 wrap them both together in a Paper, and mark upon 
 it fifteen Ounces, which will fignify, that there are 
 in that fmall Mafs fifteen Parts of pure Silver, and 
 one of pure Copper. Make of this the fecond Needle. 
 Then add two half Ounces of Copper to fourteen half 
 Ounces of pure Silver ; and mark it fourteen half 
 Ounces. Make a third Needle of this. Goon thus, 
 and proportion the fmall Mafifes of Silver and Copper 
 for the making of the other Needles, and put In- 
 fcriptions upon every one, in the following Manner. 
 
 I 2 
 
 For 
 
The Art of 
 
 116 
 
 r + .h 
 
 J 3 
 
 3*y 
 
 fth 
 
 b 
 
 1 2 
 
 4 
 
 6 th 
 
 1 1 
 
 5 
 
 7 th 
 
 10 
 
 6 
 
 8 th 
 
 9 
 
 7 
 
 9 th 
 
 8 
 
 8 
 
 -< 10 th 
 
 7 half oz. of Silver 
 
 9 > 
 
 1 i th 
 
 6 
 
 10 
 
 12 th 
 
 5 
 
 1 1 
 
 1 3th 
 
 4 
 
 1 2 
 
 H th 
 
 3 
 
 13 
 
 i 5 th 
 
 2 
 
 *4 
 
 ^i6 th 
 
 1 
 
 1 5J 
 
 half o fc. 
 of Copper 
 
 Let then each of thefe Portions of Metal, as they 
 are wrapt in a particular Paper, be put feparately in- 
 to a new Crucible, never ufed for any Operation, and 
 adding a little Borax, melt them in a very quick Fire, 
 which muft be well kindled before with Bellows ; or 
 what’s ftill better, throw them fuddenly into a white 
 hot Crucible, and fo foon as they melt, ftir them 
 with a dry wooden-Peg, burnt at the End, and pour 
 them immediately into an Ingot. This mingled Fu- 
 fion may as well, and almoft more conveniently, be 
 made with a cementatoryTube (§ 258). Next to this, 
 wrap each fmall Mafs grown cold, into its Paper again, 
 to avoid Confufion, and again try them fmgly in the 
 Balance. If they ftill weigh a whole Mark, they are 
 good : But if there is any confiderable Deficiency in 
 the Weight*, it is a Sign that your Fire having been 
 too weak, or of too long a Duration, has confumed 
 as much Copper, as is wanting in the Weight: There- 
 fore inftead of this fmall deficient Mafs, another 
 muft be made in the fame Proportion. Then with 
 a Hammer, make a Needle (§ 289.) of each of thefe 
 fmall Mafles, making them a little red hot, when the 
 Metal begins to grow ftiff under the Hammer. This 
 done, engrave upon every one of thefe Needles the 
 Number of half Ounces of Silver which they contain ; 
 that is, upon the firft, 16 *, upon the fecond 1 5 j and 
 fo on. Then pierce them at one End, and running a 
 
 Silver- 
 
Assaying Metals. i 17 
 
 Silver-Wire through their Eyes, collect them in Or- 
 der, according to their different Numbers. Thefe are 
 called Silver Touch-Needles, but they call the feve- 
 ral Temperings of Silver with Copper, Allays. 
 
 291. Some determine the Proportions of their 
 Needles by half Loth’s : Others ufe (till fmaller Di- 
 vifions, the Compofitions and Numbers of which 
 may be eafily known from (§ 290). But you can 
 hardly diftinguifh any thing of filver- Allay, by your 
 Needles, when you divide beyond half Loths. 
 
 292. You may alfo add to thefe filver- Needles 
 (§ 290.) one made of pure Copper : For with thefe 
 you may at the fame Time find out the Purity of the 
 Copper, or its various Mixtures of Silver. 
 
 293. In Holland they ufe the Mint-Mark (§285) 
 divided into Grains, for the making of Needles. 
 But then, the fir ft Needle made of pure Silver, is faid 
 to be twelve Penny-weights. The fecond is made of 
 eleven Penny-weights and eighteen Grains, by 
 the Addition of fix Grains of Copper. The third is 
 made of eleven Penny-weights and twelve Grains, 
 with twelve Grains of Copper ; and fo on : the Pro- 
 portion of the Silver decreafing always fix Grains at a 
 Time, that is, one quarter Part of a Penny-weight, 
 and that of the Copper being always increafed in the 
 fame Proportion ^ till at laft the Weight of the Sil- 
 ver is diminifhed to one Penny-weight, and the Quan- 
 tity of theCopper augmented to eleven Penny-weights : 
 Which Proportion conftitutes the lafl Needle, beyond 
 which you are not to proceed. 
 
 294. However, it is needlefs to go through the 
 whole Series of the Needles, by fo fmall Progreflions, 
 to the very lafl. It is enough for us, to have indi- 
 cated quarter Parts of a Penny-weight to one Needle 
 of nine Penny-weights (§ 285), and the half-Ounces 
 to one Needle of ten Semi-ounces (§ 2S4) •, for af- 
 terwards, you cannot accurately diftinguifh Propor- 
 tions fo very delicate, in the following Needles. 
 
 295. Gold , when you are to make gold-Needles, 
 muft be mixt either with Silver alone, or with Silver 
 
 I 3 and 
 
1 1 8 The Art of 
 
 and Copper variously intermixed. But this Mixture 
 is called allaying, or carrafting , and is determined 
 with a Mark divided into Caradts, or Weights of 
 two frxth Parts of an Ounce (§ 286). There is 
 nothing to be obferved about the making of thefe 
 Needles, befides what has been already fa id of the 
 Silver-Needles (§ 290), except that the Proportions 
 of the Weights are determined in another Manner. 
 Thefe Needles are made according to the following 
 Divifion and Order. They all weigh eight Ounces, 
 or one Mark. 
 
 ♦ 
 
 The fir ft is entirely made of pure Gold. 
 
 2 d 23 Car. 6 Gr. ^ 1 
 
 r 6 Gr. ^ 
 
 3 a 23 Car. 
 
 
 1 Car. 
 
 4 th 22 Car. 6 Gr. 
 
 
 1 Car. 6 Gr, 
 
 5 th 22 Car. 
 
 
 2 Gr. 
 
 6 th 21 Car. 6 Gr. 
 
 Pare 
 
 2 Car. 6 Gr. 
 
 7 th 2 1 Car. 
 
 ■ Gold. 
 
 : 3 Car. > 
 
 8 th 20 Car. 6 Gr. 
 
 
 3 Car. 6 Gr 
 
 9 tIa 20 Car. 
 
 
 4 Car. 
 
 lo ch 19 Car. 
 
 
 5 Car. 
 
 1 I th 1 8 Car. 
 
 ' \ 
 
 \J) Car. y 
 
 The Decreafe goes on thus by whole Caracas, till 
 the Weight of the Gold is arrived at one Caradt, and 
 that of the Silver at twenty three : for after the ninth 
 Needle, you cannot make fo exadt a Diilindfion of the 
 half Caradts. Now, this Mixtyreof Gold with Silver 
 is called the white Allay. 
 
 296. But when Copper together with Silver enters 
 into the Mixture of the Gold, it then is called a mixt 
 Allay : This is compofed in the'fame Manner as the 
 foregoing (§295), except only that thofe Portions, 
 which in the nrft Cafe were pure Silver, here confift 
 of Copper and Silver. Therefore, you have here again 
 a double Series : For you mixt either two Parts of 
 Silver and one of Copper, or two Parts of Copper and 
 one of Silver , for Inftance : 
 
 Thg 
 
Assaying Metals. 
 
 up 
 
 The iirft is of pure Gold. 
 
 o r + Gr - a C r 2 Gr. 
 
 -n V 8 Gr. //T V 4 
 
 ? Y Car. ( Ej \ 6 
 « 5^1 Car. 4Gr. / ^2. < >' 8 
 ££ j i Car. 8 Gr.f .o A io 
 n / 2 Car. \ / 1 Car. 
 
 •* > 2 Car. 4 Gr. ' ^ L i Car. 2 Gr. 
 
 And fo on, as in the foregoing, 
 
 297. If in the Table juft mentioned (§ 296), you 
 take pure Copper, inftead of pure Silver, and Silver 
 inftead of Copper ; this gives you a third Series of 
 golden-Needles. And you will have a fourth, by 
 mixing with Gold equal Quantities of Silver and 
 Copper, in the fame Proportions mentioned (§ 296). 
 
 298. The Allays of Gold hitherto explained (§ 295, 
 and foil.) are very much in ufe. However, it is 
 plain, that Workmen may eafily employ an infinite 
 Number of other Variations ; which being compared 
 with thofe above-mentioned, may be diftinguifhed in 
 a thoufand different Ways, by an experienced Man : 
 So that it is neither poffible, nor neceffary, to imitate 
 them all. 
 
 299. But left the golden-Needles (§ 295 and foil.) 
 fhould be too expenfive *, they may be made much 
 Ihorter than the Silver ones (§ 289, 290), and be fol- 
 dered to Plates of Copper ; that they may be fuffici- 
 ently long for Ufe. 
 
 300. Now, if you light upon a Metal (§ 289), 
 which you think wants to be tried upon the Touch - 
 / lone i wipe it firft with a clean Towel, or Leather ; 
 that you may fee the true Colour of it : for from this 
 you may, in a Manner, judge before-hand, what 
 Metal it is, and how much, or with what ether Me- 
 tal it is mixt. Then chufe a convenient and not over 
 large Part of the Surface of your Metal, and at feveral . 
 Times rub it ftrongly againft the Load-ftone ; that, 
 in cafe a deceitful Cruft fhould have been laid upon 
 
 I 4 the 
 
 2 3 Car. 6 Gr. 
 23 Car. 
 
 22 Car. 6 Gr 
 22 Car. 
 
 Q ^ 21 Car. 6 G 
 Car. 
 v 20 Car. 6 Gr 
 
 l 
 
I 20 
 
 The Art of 
 
 t he Metal, it may be fcraped off by a ff rong Fri&ion : 
 which however may be done ft ill quicker with a Grind- 
 ffone, or a delicateFile, if you have them at hand. Then 
 wipe a fiat and very clean Place (§ 288.) of the 
 Touch-ftone, and rub againff it the fame Part juft 
 mentioned of the Surface of your Metal over and 
 over *, till the flat Part of the Stone be equally and 
 neatly covered with a metallick Cruft, one Inch 
 long, and one Line and a half broad. This done, 
 chufe the Needle, that you ftiall judge anfwers neareft 
 to the Meta] rubbed ; which Choice is learned by fre- 
 quent Practice. Then wipe the loweft Extremity of 
 this Needle very well, and rub it againft the Touch- 
 ftone, as you did the Metal, by the Side of the firft 
 Plain, and in a Diredion parallel to it. If you can 
 find no Difference between both Plains *, you may 
 pronounce with Probability, that the Metal to be 
 tried is of the fame Temperature, as the Needle you 
 have compared with it: whichTemperature is fhewed 
 by the Number ingraved (§ 290. and foil.) upon it. 
 But if you find a Difference between the Colours ; 
 chufe another Needle, in cafe you ftiall find the Metal 
 of a deeper or a lighter Colour than the firft Needle : 
 Thus you will atlaftfind a proper Needle, anfwering 
 to the Temperature of the Metal ; or at leaft you 
 will be able to judge, that the Allay of Metal is ex- 
 traordinary, and cannot be determined by your 
 Needles. 
 
 301. Meanwhile, as not only the Surface, butalfo 
 the whole Mafs of the Metal may be dyed with a 
 fpurious Colour, which may be produced many dif- 
 ferent Ways ; you may eafily fee, from the Colour 
 of any Metal compared with your Needles, that you 
 can pafs no certain Judgment upon it, unlefs you 
 know that the Gold and Silver are mixt, and what the 
 Metals are wherewith they are fo mixt : whether, for 
 Inftance, it is Gold and Silver, Silver and Copper, or 
 all thefe three perfectly pure, without any Mixture of 
 another Metal. For, in this Cafe, the Comparifon 
 of the Colours with thofe of your Needles 3 may in- 
 form 
 
Ill 
 
 Assaying Metals. 
 
 form you of their Temperature. Nor can, however, 
 this Determination be made exadt to a few Grains, by 
 this Method. 
 
 302. But if the Colour of the Metal has been al- 
 tered (§57,71,83,88.) by Tin, Arfenick, Zink, fefr. 
 the Workman may be deceived by the Colour, fo 
 as to take ior pure Gold or Silver, what is not fuch 
 by the greateft Part. You find out the Deceit with 
 Aqua Fortis , when the metallick Mafs is of the Co- 
 lour of Gold *, and with Aqua Regis , when it is like 
 Silver : for the firft of thefe Liquors aiftolves all Me- 
 tals, Gold excepted ; and the other likewife all Me- 
 tals, but Silver . In fuch Cafe then, you pour upon 
 the metallick Streak, or thin Cruft rubbed upon the 
 Touch-ftone, one fingle fmall Drop of either of thefe 
 diftolving Liquors, and extend it gently with a Fea- 
 ther : if it is neither Gold nor Silver: the whole Streak 
 will be confumed : but if there is any Gold or Silver 
 in it *, this remains undiffolved, and fhews another 
 Colour ; becaufe the other Parts have been feparated 
 from it by the Solution. Take care however, when 
 you make ufeof thefe Menftrua , that there is no oily 
 Mixture with them ; becaufe this would render them 
 of no Effedt. 
 
 303. Befides this, you are to obferve the following 
 
 Particulars concerning the Ufe of the Touch-ftone. 
 1. Gold and Silver pure and feparate, or both mixt 
 together, without any other Matter added to them, 
 when made white hot in the Fire, not only preferve 
 their Colour, but alfo entirely recover all their 
 Splendor there, when tarnifhed, not lofing the lead 
 part of their Weight (§ 6, 7) : on account of which 
 Quality th z Caratura alba, or white Allay, is diftin- 
 guifhed from all the others. But if you have not the 
 Liberty to try the whole Mafs in the Fire •, you 
 may make only a fmall Part of-it white hot, with a 
 blow-Pipe (§ 258). 2. If you find a Needle, whofe 
 
 Colour agrees with that of the Metal to be tried ; 
 both the Streaks imprinted upon theTouch-ftone, mu ft 
 undergo Changes altogether the fame, when Aqua 
 
 Fortis , 
 
12 2 - The Art of 
 
 Forth , or Aqua Regis is poured upon them ; that you 
 may thus be certain, that there is no Fraud at Bot- 
 tom : otherwife, you are not to doubt, upon any Ac- 
 count, your being deceived by a faife Colour. 3. All 
 Gold rendered brittle, when compared with the Needle 
 upon the Touch-ftone, appears lefs pure, than it is 
 indeed found to be, by an accurate docimaftical Exa- 
 mination : and on the contrary, all Silver rendered 
 brittle, has the Whitenefs of pure Silver in a higher 
 Degree. Nor is it difficult to find out the Reafon of 
 this Difference : for the Bodies which make Silver or 
 Gold brittle, are only a few Metals and Semi-metals, 
 all of a very bright white Colour : fuch as Fin, Lead , 
 Iron , Regulus of Antimony , Bifmuth , Zink, and Arfenick. 
 Now thefe dilute the yellow Colour of Copper and 
 Gold, or change it into white : fo that the Colour of 
 the Copper mixt with Silver is then hidden ; whereas 
 Gold on account of thefe Mixtures, appears to have a 
 great Deal of Silver in it. 4. In a white Allay Aqua 
 Fortis does not difcover 302. ) the Prefence of Sil- 
 ver, from twenty three to feven Carats ^§2959, 
 becaufe Aqua Forth does not feparate Silver from Gold , 
 uniefs the Mafs contains three times more Silver than 
 Gold. 5. Metallick Streaks or Crufts, which have 
 been imprinted a while upon the Touch-ftone, can- 
 not be compared with freffi ones : for their remain- 
 ing long upon it, commonly occafions an Alteration 
 in the Colour. 6. Silver, when tempered with Brafs, 
 appears whiter, than it would, if mixt with a like 
 Quantity of Copper : but as it may then be rendered 
 fufficiently dudlil by a proper Operation ; you will 
 hardly be able to find out the Fraud with the Touch- 
 ftone, uniefs you make a fecond Time the Com pa - 
 nfon with a Needle of the fame Colour, having 
 previoufiy poured Aqua Regis 302. ) upon the 
 metallick Cruft, laid by rubbing on the Touch-ftone. 
 Nor are the Touch-Needles tempered with Brafs, of 
 any great Ufe here becaufe this artificial Metal is 
 fometimes more, fometimes lefs yellow. 7. If the 
 Metal applied upon the Touch-ftone by rubbing, 
 
 does 
 
Assaying Metals. 123 
 
 does not appear neatly enough, lick it over with 
 Spittle not frothy, and then the Colours will be more 
 lively reflected. 
 
 304. Befides the Lftenfils hitherto defcribed (§ 1 68, 
 301 ) you muft have a convenient Place for the per- 
 forming of the docimaftical Operations. You muft 
 have a Chimney, large enough to place the Furnaces, 
 and capable of quite confining the Fumes ; which, 
 tho* not all mortal, are neverthelefs always hurtful, in 
 almoft all Operations when they can come out freely. 
 But as thefe acid Fumes corrode the Metals them- 
 felves, it is not proper to keep in the Laboratory 
 fuch metallick Utenfils, as muft be preferved very 
 clean *, for inftance the Scales, with their Weights, 
 the Touch-Needles, &c. which muft be kept in a 
 cleaner Place : nor muft you keep there many dif- 
 ferent Menjirua , except they are in Veffels perfectly 
 clofed : for fome of them, by fending forth their Va- 
 pours, change the others, and are mutually altered 
 by them ^ fo that you can no longer make any exaeft 
 Experiment with the fame. Moreover, as you muft 
 frequently obferve very minute Bodies, and their fe- 
 veral Changes in* and out of the Fire *, the Laboratory, 
 which in thefirft Cafe muft be darkened, in this muft 
 be rendered very bright : which may be eafily ob- 
 tained, by hanging up thick or black Curtains againft 
 the Windows. 
 
 CHAP. IV. 
 
 Of compound Minerals . 
 
 Of Ores. 
 
 305. T tAV I N G in our firft Chapter given an Ac- 
 £1 count of the fimpler Minerals, and in the 
 Second that of their principal Actions upon each 
 other, as far as they can be fo difpofed by no great 
 
 Art ^ 
 
124 The Art <y 
 
 Art ; we may now underhand and explain the Nature 
 of thofe Bodies, which being compofed of the forego- 
 ing, are found natural in the foffile Kingdom. The 
 Knowledge of thefe, though we could hitherto give 
 it only hiftorically , has neverthelefs a vaft Utility in 
 the exercifmg the pra&ical Part of Affaying j for he 
 that is well imbued with it before-hand, may very 
 well difpenfe with many vague Experiments, which 
 he is obliged to go through, when altogether a 
 Stranger to the feveral natural compound Bodies. 
 
 306. But the ufelefs Defcriptions given by many 
 Authors, and derived mod of them from accidental 
 Properties •, the Difficulty of obtaining the bed Speci- 
 mens from different Countries ; the Variety with 
 which Minerals are mixt together in their minuted 
 Particles 327 ; in diort the Difference of theWorks 
 of Nature, and of thofe of Art, though they are made 
 of the fame Principles united in equal Proportions ; 
 render this Part of natural Hiftory equally difficult 
 and defetdive. Add to thefe the Variety of outward 
 Figures, wherein Nature feems to delight dill more 
 in the mineral, than in the vegetative and the animal 
 Kingdoms. 
 
 307. Nor is the fpecifick Gravity of any great 
 Help, in the didinguifhing of compound Minerals. 
 For, 1. when more than two Bodies of different fpe- 
 cifick Gravities are mixt together, you can detecff 
 nothing by an hydroftatical Calculation •, becaufe a 
 compound Mafs of the fame fpecifick Gravity, may 
 be produced by many dmple Bodies, very different 
 from each other, and mixt in a thoufand different 
 Proportions : Now the fame is in reality found in the 
 mineral Kingdom, as is fhewn by docimadical Ope- 
 rations. 2. The accidental Matters inherent to Mi- 
 nerals, and the very Air imprifoned in the fmall Ca- 
 vities and Clefts of feveral Ores, hinder an exaft 
 Ponderation, and now and then render it very diffi- 
 cult. 3. The fimple Stones, which being joined with 
 almod all compound Minerals, are not only of infi- 
 nite Variety, as to their fpecifick Weight, but fome 
 
 are 
 
Assaying Metals. 125- 
 
 are almoft as ponderous as Metals themfelves : fuch 
 are a great many Species of Spaad. 
 
 308. However, I would not have the fpecihck 
 Gravity, nor the Figure be altogether overlooked, 
 but rather made ufe of with the other Charafterii- 
 ticks ; though no conftant and accurate Judgment 
 can always be drawn from thele alone. 
 
 309. But cur Defign being to lay down the Prin- 
 ciples of the Art of Afiaying ; it will be neceffarv 
 only, to mention the Charaflerifticks and diftinguifh- 
 ing Marks of compound Minerals, as they are the 
 molt frequent Objects of the faid Art (§ 2), and to 
 Fiew their conftituent Parts, as far as they make 
 themfelves known, together with the Difpofition of 
 the whole Body with leveral Menfirua. It is likewife 
 evident, that we cannot here mention all Ores with- 
 out Exception, but that we muft only chufe thofe that 
 are lefs compound, or thofe at lead: which are more 
 frequently met with. 
 
 310. We fhall refer every compound Mineral to 
 the Clafs of that Simple, of which it contains the 
 greatelf Part in itfelf ; except however Stones , and 
 li triple Earths : for if the Clafles of thefe were to be 
 determined from their predominant Parts *, the Num- 
 ber of the Ores to be referred to that Clafs, would be 
 by much the greatefl. 
 
 Scholion. For lnftance , let us fuppofe , that there are 
 in a Lump , fix Parts of Copper , one of Sulphur , a 
 very fmall Quantity of Arfenick , and twenty Parts of 
 Quartz or Flint-ftone *, we fhall clafs this compound 
 Body with the Copper-kind , and fo on . 
 
 31 1. But we fhall call a Mineral proper to that 
 Simple, which makes the greatefl Part of it (§ 310), 
 and improper to thofe which it contains in lefs Quan- 
 tity : However, they are contained in it in fuch Man- 
 ner, that they indeed enter into the Mixture of it, 
 and muft always accompany it wherever fuch Mineral 
 is found. Finally, we fhall call it accidental to thofe 
 Simples, which enter not into the Mixture of it, be- 
 ing only adherent to the Out-fide : Wherefore, they 
 
 may 
 
iz6 The Art of 
 
 may be or not be found with the Mineral now men* 
 tioned, and yet this Mineral remain ftill the fame. 
 
 Scholion. Let us clear this Matter by the foregoing 
 Example (Schol. § 310). Fhe Mineral fuppofed there , 
 containing Copper in the great eft Part , is called proper 
 to Copper. But fo long as Sulphur and Arfenick are 
 mixt together with the Copper , and render it of a parti- 
 cular Species , this Mineral , on account of the fmall 
 Quantity of its fulphureous and arfenical P art j, is faid to 
 he improper to them . Finally , the Stones or other Bo- 
 dies placed about or among that Mineral , are called ac- 
 cidental to it , as they are no conftituent Parts thereof and 
 it might fubfift without them . 
 
 Of Sidphur and fulphureous Minerals . 
 
 312. Mineral Sulphur or com?non Brimftone , when 
 free of all foreign Mixtures, is of a folid, friable 
 Confiftence ; yellow, made up of large Maflfes, and 
 more or lefs half-tranfparent *, it burns, makes a 
 bluilh Flame, with a furfocating acid Vapour (§ 22), 
 and thus is entirely confumed : Being put upon a gen- 
 tle Fire, and in clofe Vefiels, it melts without taking 
 Fire, and, when melted, changes its Colour into a 
 bright Red: it no fooner grows cold again, but it re- 
 fumes its Solidity- and yellow Colour. It is compofed 
 of the pureft inflammable Principle (§ 24), and of a 
 much greater Quantity of Acid of Vitriol (§ 22) : on 
 which Account it finks in Water, being much heavier 
 than pure Oil. The Chemical Analyfls, and the 
 Produ&ion by Art of true Sulphur, out of the two 
 Principles juft mentioned, confirm what has been 
 faid of it. 
 
 313. In this State (§ 312.) native Sulphur is digged 
 out of the Earth \ though not fo very frequently : it 
 is likewife brought in fuch a State by Waters, which 
 on this Account are called particularly medicinal, 
 and it applies itfelf to the Walls of the Springs. 
 
 314. It is frequently found mixt with fimple Earths 
 and Stones j varying its dye, and being fometimes 
 
 white. 
 
Assaying Metals. 127 
 
 white, fometimes grey, yellow, or of other Colours, 
 belonging to the Bodies mixt with it. 
 
 315. Whenever Sulphur is tinctured with a dark, 
 or bright Orange or red Colour, this always betrays 
 Arfenick in it : Wherefore, Sulphurs thus coloured are 
 not true, nor very valuable. 
 
 316. The moft frequent and almoft the proper Mi- 
 neral of Sulphur is the Pyrites flavus , or yellow Py- 
 rites. This, when free of all heterogeneous Matters 
 at the outfide, and bright, has all the Appearance of 
 polifhed Brafs, and is more various as to its Form, - 
 than any other Mineral : however it is mod com- 
 monly found of a globulous Form, then of a cubi- 
 cal, hexagonal, both regular and irregular Figure. 
 
 It is folid ; unlefs it be rendered foft by a Mixture of 
 loft Stones and Earths : when {truck with a Steel, it 
 gives fparks like a Flint : when brought near a gen- 
 tle Fire, it foon burfts, with a crackling Noife * and 
 emits fmall Flames almoft fulphureous : it changes its 
 yellow Colour into a dark red, and its neat Surface 
 into adufty one. It is very rich in Sulphur, and con- 
 tains one quarter, fometimes almoft one third Part 
 of it. Moreover, there is always a Quantity of Iron 
 lurking in it its fulphureous Part is fometimes great- 
 er, fometimes lefs : and Henckel has found that it alfo 
 contains a kind of Earth not metallick, and in a va- 
 rious Proportion as to the other Parts : which makes 
 us eafily guefs, that the fpecifick Weight of the Py- 
 rites muft be very various. The Author juft menti- 
 oned, has, in his Treatife on Pyrites*, given us a 
 very ample Hiftory of this Mineral, together with a 
 very accurate Analyfis of it. 
 
 317. There are very few Minerals altogether de- 
 ftitute of Sulphur : but as the extracting of it would 
 never pay the Charges, and they befides contain Me- 
 tals and Semi-Metals in a greater Quantity *, for this 
 
 * Pyritologia, oDcr Kiefs-Hijlorie , Sec. gefctttgCt t)0U D. Jo- 
 hann Friedrich Henckel; Leipzig, 1725, in 8 vo . 
 
 Reafon, 
 
12 8 The Art of 
 
 Reafon, we fhalf mention them in thofe Places, to 
 which they properly belong (§ 310, 311). 
 
 3 1 8. We may alfo refer to this Clafs all the inflam- 
 mable Minerals, that differ from Sulphur ftri&ly fo 
 called (§ 312.) by the Quantity and Quality of their 
 Acids. Such are Naphta and Petroleum , that difl.il 
 from Stones , or fvvim upon the Waters of Fountains. 
 They differ hardly among themfelves, and are fome- 
 times very limpid and thin, fometimes yellow and 
 thick. But when thefe Matters are grown very thick, 
 and have aflumed a dark Colour, they are called Bi- 
 tumen *, Pix Juda'ica ; Afphaltum : and when at laft 
 grown harder, they turn into a Stone called Gagates 
 or Jeat *. There occur befides, other the like Names 
 of fulphureous Matters, which, however, feem hardly 
 to fignify other Concretes, different from thofe juft 
 mentioned. 
 
 319. The very fame (§ 318.) oily Mineral, when 
 it hardens, and adheres to a ftony Matrix, becomes 
 that kind of foffil Coal, called Stone-coal, Quarry-coal 
 or Sea-coal 7 .* which is a black concrete Body, eafy 
 to be cleft, confifting of Lamina’s, and bright : much 
 heavier than the foregoing (§ 318) *, not quite fo 
 quickly inflammable, but preferving its Flame, when 
 once kindled, longer and more violently than any 
 other Fuel ; leaving after it is burnt, not fo much 
 Afhes, as a Mafs half fcorificated, blackifh, fpungy, 
 and often containing a yellow Pyrites (§ 316.) in it. 
 
 320. Amber , called in Latin Elettrum, Succinum , 
 of a blackifh, dark yellow Colour ; half tranfparent, 
 frequently very tranfparent ; light ; finking however 
 in Water ; very hard, fo as not to foften at the Heat 
 of boiling Water * melting neverthelefs in a ftrong 
 
 * Of which Kind is the greateft Plenty in fome Parts of England 
 and Scotland, known by the Name of Kennel-coal, Staffordjhire- 
 coal, and Scotch-coal: out of the firft feveral curious Vcffels are turned 
 and carved, as of Amber, of which Jeat is a Species, and may be 
 called black Amber. 
 
 f Which is the common Fuel in London and the maritime Parts 
 
 of England . 
 
 Fire, 
 
Assaying Metals. 129 
 
 Fire, foaming, and yielding a folid acid Salt, belongs 
 alfo to this Clals. It diflolves, by a Chemical Di- 
 ftillation, into Oils, which are thin at firft, and by 
 degrees become thicker, and into an acid folid Salt : 
 Thefe Oils have fo much Affinity to Naphtha and 
 'Petroleum (§ 3 1 8), that we fee* if not always, at leaft 
 moft frequently. Apothecaries and Druggifts ufe 
 them in room of thefe natural Foffils. The Caput 
 Mortuum remaining after the Diftillation, is not un- 
 like Bitumen (§ 318), and is even fold under that 
 Name. 
 
 Of Arfenick, and arfenical Minerals . 
 
 321. The Cryftalline, pure Arfenick deferibed 
 (§ l j) *> is got out of the Mines under the fame 
 Form, and looks white and dufty : however it is 
 very feldom found natively fuch. 
 
 322. The fan^e (§ 321.) is digged out under the 
 Form of a black or afh-coloured Stone, which being 
 broken when frelh taken out, is within of a bright 
 bluiffi White, which however, being expofed to the 
 open Air, becomes dark and blackiffi in a few 
 Days. 
 
 323. Next to this the white Pyrites, which is heavy* 
 bright, ftriking Fire againft a Flint, and of a Figure 
 altogether irregular, contains a very great Quantity 
 of Arfenick, of Iron but little, more of Earth not 
 metallick, and is moft frequently found in Mines. 
 
 324. Orpiment , which is a Mineral of a golden 
 Colour, filled here and there with fmall Maffesof the 
 Colour of Cinnabar, eafy to be cleft, made up of 
 Flakes, foft with fomeTenacity, bright when broken, 
 contains a great Deal of Arfenick, lefs of mineral Sul- 
 phur (§312) : wherefore, it burns dark in the Fire, 
 giving a whitifh blue Flame, with a moft tnick white 
 
 * Arfenick is vulgarly called in Englilh Rats-bane , and from its 
 Colour is diitingui fhed into the white and yellow Rats-bane, being 
 the Poifon ufually employed for deftroying Rats, 
 
 K 
 
 Smoak. 
 
1 30 The Art of 
 
 Smoak. It melts as foon as it burns ; when melted* 
 if you pour it upon a clean Iron or marble-Table, 
 growing cold, it turns into a folid Body, of a dark 
 red Colour, brittle, bright, and half-tranfparent * : 
 However, there remains upon it a Cream which is of 
 a lefs fluid Nature, like imperfe<5t Sconce, which be- 
 ing burnt in a great Fire, Separates into Earth. It 
 is digged out in Hungary , and in the Eaft Indies . 
 
 325. Cobalt belongs to the fame Clafs. It is a pon- 
 derous Mineral, finely ftriated, or fometimes granu- 
 lated, fometimes alfo fmooth at the Outfide, fome- 
 times of a light, greyifh, almoft: femi-metallick Co- 
 lour, and fometimes of a dark blackifh Dye. It con- 
 tains a great Deal of Arfenick, and a good Quantity 
 of a certain fixt Earth, which being melted with 
 Flints and fixt Alcali, turns into Glafs, of the fineft 
 Blue, inclining howfoever to the violet Colour called 
 Smalt -f\ Befides, Cobalt moil commonly contains 
 Bifmuth (§ 15.) There are alfo many different 
 Minerals called Cobalt , which neverthelefs have Pro- 
 perties altogether different from thole juft menti- 
 oned. 
 
 326. However, the Flower called Flower of Cobalt, 
 which is finely ftriated, not very compafl, and on 
 this Account lighter than the foregoing (§ 325), and 
 of a fine red purple Colour, belongs likewife to the 
 Cobalt kind. For it is a very arfenical Mineral, fo 
 that it lofes above one half of its Weight in the Fire : 
 but you may afterwards melt a great Quantity of Bif- 
 muth out of what remains : and this befides gives 
 
 * And when it hath been thus melted, and of a vermilion-Colour, 
 it is called red Arfenick or Sandaracb. 
 
 f The Stone-blue , or flaky Blue for fprinkling upon Wood 
 frefh painted over, and the Powder-blue ufed in wafhing Linnen are 
 Preparations of this Mineral ; and the Manufacturing of it brings in 
 great Profits in fome Parts of Germany ; but if our Englifh Minera- 
 lifts were curious in their Refearches, they might certainly find both 
 Cobalt and Bifmuth-Ore \n Cornwall, and other Parts of England: 
 there having been formerly fent to the Royal Society Specimens of 
 thefeOres, among Specimens of Tin and other Ores. See the Note 
 (§ 4°7') 
 
 Glafs 
 
Assaying Metals. 131 
 
 Glafs the azure Colour, as the other true Cobalts do. 
 On which Account it is true Cohalt , though outward- 
 ly it Teems to differ very much from the common Sore 
 (§ 325). h as indeed Cobalt (§ 325), for its Bafis, 
 and Teems to be produced by it, by a Germination as 
 it were like that of Plumofe AH urn. 
 
 327. Thefe (§ 325, 326.) are the principal Spe- 
 cies of true Cobait, which all agree in this Point, that 
 they have a very great Quantity of Arfenick in diem : 
 wherefore they are here referred to the Clafs of arfe- 
 nical Minerals , though they fometimes have that 
 Difference from other arfenical Bodies, that after the 
 Sublimation of the Arienick, they leave a Caput Mor- 
 tuiun , which tinges white Glafs of an azure Colour. 
 There are likewife many other Minerals, which they 
 commonly call Cohalt . But as they are totally dif- 
 ferent from the true Cobalt, and even do not con- 
 tain the lead Sign of Arfenick ; for this Reafon, and 
 to avoid Confufion, they deferve to be expelled out 
 of the Clafs of Cohalt . 
 
 328. Neverthelefs, there is a certain Mineral, that 
 deferves to be referred to this Clafs : it is rich in Arfe- 
 nick, fomewhat like Cobalt (§ 32 5), of a grey reddifh 
 Colour, it looks like a Semi-metal ; it contains alfo 
 a little Copper, and a little Sulphur •, the Germans call 
 it Kupfer Nickel . 
 
 329. There are alfo a great many other Minerals, 
 which, on account of theArlenick contained in them, are 
 likewife referred to this Clafs. But as there is in them 
 a greaterQuantity of Metal than of Arfenick ; for this 
 Reafon, they fhall hereafter be reckoned among other 
 Clafles, as being improper (§ 3 1 1.) to Arfenick. I 
 ihall only add, that Arfenick makes itfelf known in 
 all Minerals, by its white Smoak, and by its foetid 
 garlick-like Smell, when you put them upon burn- 
 ing Coals, or in a fmall Veffel made white hot in the 
 Fire. 
 
 330. Finally, you are to obferve here, that Arfe- 
 nick lies hidden in a great many fimple Stones and 
 Earths, efpecially thofe that fhine, and adheres 
 
 K 2 ftrongly 
 
The Art of 
 
 drongly to them *, and that, when agitated by a vio- 
 lent Fire, it renders them for the greated Part vola- 
 tile. The famous Hankel has obferved, that it fome- 
 times lies hidden in marly and clayey Earths. See his 
 Pyritolog . p. 6 1 1 . 
 
 Of O r £ s in general. 
 
 331. When Metals and Semi-metals are penetrated 
 with Sulphur and Arfenick, they always lofe, either 
 that univerfal Character which is common to all Me- 
 tals and Semi-metals, or that which is peculiar 
 (§ 517* ) to them alone. Lead and Tin, confounded 
 with Sulphur , not only lofe that Character which is 
 common to all Metals, viz. their Malleability, but 
 are alfo deprived of the Properties peculiar to them, 
 that is, when in a certain Situation in the Fire : for 
 then, they both require a much greater Fire to be 
 melted, than they would, if they had been free from 
 Sulphur, and lofe befides their Colour. The pureft 
 granulated Silver, confounded with Sulphur, retains 
 its Malleability, Fufibility, and the other Properties 
 that are common to all Metals ; but it lofes thofe that 
 are peculiar to itfelf : for its moft white Colour 
 changes into that of Lead ; its hard Confidence turns 
 into the Softnefs of the fame Metal •, and finally, 
 when it is but a little heated in the Fire, it then, if 
 pure before the Fufion, melts fo foon as it grows red. 
 But metallick Bodies are mod commonly in that 
 State naturally, except Gold alone. 
 
 332. Natural Concretes, of Metal or Semi-metal, 
 mixt with Sulphur or Arfenick, or with both together, 
 are called Ores. But when fuch Alliances are made 
 by Art, we then fay that the Metals or Semi-metals 
 are reduced to the State of Ores. 
 
 333. As, therefore it has been found hitherto, that 
 the Caufes of this particular drange Form (§33 1 .) given 
 to metallick or femi- metallick Bodies, refide in the 
 Sulphur and Arfenick incorporated with their Sub- 
 dances j it would feem to be an eafy Matter, to imi- 
 tate 
 
Assaying Metals. 133 
 
 tate (§ 332.) by Art natural Concretes of this Kind : 
 and it indeed has fucceeded very well with fome. 
 Thus for Inftance, the Silver vitreous Ore, the Ores 
 of Mercury, and of Regulus of Antimony, may, by 
 Art, be rendered perfect and like the natural ones ; 
 if to Silver you join Sulphur, or Regulus of Antimony 
 by Fufion, and to Mercury by Trituration and Subli- 
 mation. But the other Ores have not hitherto been 
 fo well imitated by Art: nay, this gives Birth to 
 Products very different, though you ufe the fame 
 Ingredients, fuch as may be fetched out of natu- 
 ral Bodies, and even in the fame Proportion. 
 But the Reafon of this Variety, feems to be in the 
 Manner and Time, in which Arfenick and Sulphur 
 are by Nature joined with Metals or Semi-metals not 
 yet thoroughly tried, and fometimes perhaps, when 
 there is another Body, either not known at all, or 
 not diffidently known : fuch is the Earth containing 
 no Metal in the true Pyrites and Cobalt (§316, 325), 
 the Nature of which is not yet tried, with a diffident 
 D egree of Certainty. 
 
 334. Ores (§332.) are didinguifhed by Affayers, 
 intofufible, refractory, and not fufible at all, accord- 
 ing to their relative Difpofitions, with regard to the 
 Fire and the Menftrua. Thofe are called fufible, 
 which, either by Means of a middling Fire only, or 
 by adding a fit Menftruum to them, melt eafily, and 
 as far as is neceffary to obtain the Fufion of a Metal 
 or Semi-metal. The RefraCtory are thofe, which re- 
 quire a very drong and lading ACtion of the Fire, 
 to be melted in the requifite Manner. But when 
 they cannot be melted in the mod violent Fire alone, 
 and require the additional AClion of a Menftruum , 
 to be put in Fufion, they are called not fufible. 
 But it is plain enough, that there are dill many dif- 
 ferent Degrees, in each of thefe Claffes. 
 
 335. The Reafon of the Difpofition of Ores in the 
 Fire, and with regard to the Menftrua , lies hidden 
 either in the Nature itfelf, or, as they call it, in the 
 Effence of the Ore, or in the Nature of fome Body 
 
 K 3 accidentally 
 
134 7£'<? Art of 
 
 accidentally refiding in it. But this Body again, has 
 this Property of itlelf, or at leaft is fuch relatively 
 to this or that Ore to which it is adherent. 
 
 336. As we are here upon Ores in general, we 
 fhall only touch upon thofe Things, which, by their 
 Prefence, render almoft all Ores refractory, or alto- 
 gether unfufible. But we fhall mention in our practi- 
 cal Part, when we treat of Ores in a more fpecial 
 Manner, the Things which produce this Effect, only 
 with regard to feme particular kind of Ore. All Ores 
 lie hidden in Earths, Stones, or in other Ores, as in 
 Matrices : if then thefe Matrices of themfelves melt 
 in the Fire with very great difficulty, or not at all ; 
 the Ore contained in them, may indeed of its own 
 Nature be put in fufion ; but yet it cannot be thus 
 delivered of its Matrix, becaufe this is not fufible. 
 Such are for Inffance iron-Ores, which by their Na- 
 ture are always difficultly melted, and on thisAccount 
 render other Mines difficult to be put in Fufion, when 
 they are naturally intermixed with them. It is the 
 fame with almoft all the Stones and Earths , a few only 
 excepted, which are ranked among the vitrificable 
 ones : nor are thefe all of them very eafy to be 
 melted : for though they are put in Fufion by Fire •, 
 they rnoft commonly become at the fame Time fo 
 clammy, that they hinder the Precipitation and Ex- 
 cuffion of the fmall metallick Maffes. The Lime- 
 Stones (§ 30), and thofe that are not affected by Fire 
 (§31), render the Ores intermixt with them moft 
 ftubborn of any *, fo that they cannot be perfectly 
 melted with Fire alone, even the moft violent. Of 
 thefe rwo the latter are ft ill worfe than the former. 
 What we have hitherto faid, is equally underftood 
 of all Ores, whatfoever they may be. 
 
 337. Some of the Stones juft mentioned (§ 336.) 
 are much lighter than the Ores intermixt with them : 
 fo that thefe may be eafily removed, either by only 
 pounding, waffling, and extinguiffing them in Wa- 
 ter, or by a previous Calcination, leaving the 
 weightier Particles of the Ore at the Bottom of the 
 
 j Yeffei 
 
Assaying Metals. 137 
 
 Veflel or Trough. Thefe kinds of Ores are called 
 decan table, (in German They are known 
 
 to be fuch : i. from the great fpeciflck Gravity of 
 the Ore, which fhews us that the metallick Mafies, 
 adherent to its Matrix, are large and folid, not too 
 frriall and difperfed. 2. From the Lightnefs of the 
 ftony Matrix. 3. From the Brittlenefs of the fame, 
 either natural or procured by burning it, or by ex- 
 tinguifhing it in Water, which Brittlenefs renders the 
 Comminution eafy. In this Cafe however, it is pro- 
 per that the Ore itfelf be fufficiently fixt, and do not 
 fly away by burning, or at lead that it ihould thus 
 melt into finall fpheroidal Maflfes. Among Ample 
 Stones, the vitrificable ones (§ 29.) and the calcareous 
 (§ 30.) are of this Kind *, and among thofe that are 
 not affefted by Fire (§ 31.) the chalky, and other 
 foft, light, brittle Stones. 
 
 338. But when Stones containing an Ore in them, 
 cannot be feparated from it by the above-mentioned 
 (§ 337.) Flelps, they are called indecantable, (in 
 German 3 Uufc!)te 0 tgC*) Such are light brittle Ores, 
 that contain a great Quantity of Sulphur, and are in- 
 terfperfed with the minutefl: Mafies of the largefl: Sur- 
 face of the Particles of the Matrix, or inclofed in a 
 ponderous, hard Matrix, efpecially of that kind that 
 cannot be aftedled by Fire (§ 31), and which neither 
 Fire nor Water can fplit. 
 
 339. Finally, if there is in the Body of the Ore 
 itfelf any thing intangled, or only adhering to its 
 Outfide, that will caufe the Metal contained in it to 
 vanifh into a Vapour, or turn it into Scoria with it- 
 felf, while the Ore is expofed to the Fire, then fuch 
 an Ore is faid to be hungry, miner a rapax . The 
 Caufesof this are commonly Arfenick, Antimony, and 
 thofe Minerals out of which Zink is produced. 
 
 340. The three Differences hitherto explained 
 
 (§ 334 — 339-) mu ft always be chiefly regarded, in 
 the diftinguifhing of all kinds of Ores: Therefore, 
 unlefs you may be certain of them by outward Signs, 
 1 4 K 4 you 
 
The Art of 
 
 you muff: always do your utmoft to find them out by 
 other Experiments. 
 
 341. As Metals and Semi-Metals are fpeciffcally 
 the mod ponderous of Minerals; and the Sulphur and 
 Arfenick, with which the former make up Ores, are 
 none of the lighteft ; it is felf-evident, that pure fo- 
 lid Ores diftinguifn themfelves from the other com- 
 pound unmetallick Minerals, by their great Weight ; 
 only a few Pyrites very fulphureous (§ 316.) excepted. 
 I fay pure folid Ores : for when thefe are difperfed 
 here and there, in fmall Quantities, among large 
 Maffes of Stones and Earths, they can never be dif- 
 tinguifhed by their Weight. 
 
 Of I r o n, and its Ores. 
 
 342. As Iron is mixt with all Ores, is prefent al- 
 Hioft every where, perfectly known, and manifefting 
 itfelf eafily, wherever it lies hidden, it deferves to be 
 placed here at the Head of the reft. 
 
 343. Pure native Iron, if there is any to be found 
 in the mineral Kingdom, is indeed of the utmoft 
 Scarcity. They take for Iron of this Kind, fmall 
 osftoedral Stones, as likewife Cubes that are alone, 
 or grown together among themfelves many different 
 Ways, having a Form like that of Pyrites of the 
 marchafiteKind (§ 316), having fometimes Fibres like 
 Wood ; of a yellow, rufty, brown, dark Colour, 
 very rich in Iron indeed, but yet having under the 
 Hammer, neither the Ductility of common Iron, 
 nor the Hardnefs qf Steel : For which Reafon, they 
 are to be reputed rather Ores very rich ip Iron, than 
 pure native Iron. 
 
 344. But the Ore of common Iron has no certain 
 Form ; being altogether irregular, moft commonly 
 of a rufty Colour, having but a middling fpecifick 
 Gravity among Ores. It is eafy to extrad: good Iron 
 out of it. Its Brittlenefs, Hardnefs, and Weight, are 
 fometimes greater, fometimes lefs ; and the red Co- 
 
Assaying Metals. 137 
 
 lour, fometimes deep, fometimes light, (hews how 
 much Iron it contains in it. 
 
 345. There is alfo an Ore, which is very ponde- 
 rous, and of a red bluifli Colour, v^hen broken, and 
 which refills the Hammer by its Hardnefs. It is very 
 rich in the bed kind of Iron, and commonly yields in 
 thefirft Fufion, fromfixty to eighty Pounds weight of 
 Iron, in the Center or an hundred Weight. 
 
 346. There is a fingular Species of Iron-Ore, which 
 has the Figure of Spaad (§ 30, 1) : it is of a pale yel- 
 lowifh Colour, though not uncommonly grey, and 
 even fometimes of a half tranfparent White *, it yields 
 in the Fufion about thirty hundredth Parts of the bed 
 Iron, though the outward Sight of it affords no pro- 
 bable Sign of it whatever. 
 
 347. The yellow Pyrites (§ 31 6.) has indeed been 
 referred to the fulphureous Minerals ; but the Propor- 
 tions of Iron and Sulphur being fo inconftant in it, 
 that it is fometimes the latter, fometimes the former 
 which predominates in it, it may alfo be properly 
 numbered among Ores: though, it is hardly ever 
 expofed to the Fire, to have Iron fetched out of it, be- 
 caufe there are Ores more abundant in this kind of 
 Metal. 
 
 348. If you compare the Iron- Ores hitherto 
 (§ 342 — 347.) defcribed, with the Ores of other Me- 
 tals, they are indeed refradtory : but thofe which are 
 to be called the mod fufible (§ 334.) among Iron- Ores, 
 are thofe that contain but little Sulphur, or fulphure- 
 ous Acid in them ; which is betrayed by the Smell 
 that (trikes the Noftrils, while thefe Ores are made 
 red hot. 
 
 349. The Haematites (called in German HBlutlf CtlT, 
 <2>laskopf, and in Englifh Blood-ftone ), is of a more 
 refradtory Nature in the Fire. As it is gibbofe and 
 arched in Part, and partly angular and redtilineal, 
 confiding of Planes directed towards one Point, on 
 this Account it looks like an irregular Pyramid : 
 which will appear much more fo, if you break it. 
 The Outfide of it is pretty well polifhed, when the 
 
 Rud: 
 
138 The Art of 
 
 Ruft has been firft wiped off ; but the Infide is com- 
 pofed of convergent Striae like the Amianth. If you 
 break it in a tranfverfe Dire&ion to its Striae, it is 
 like the breaking of Steel that is not tempered very 
 hard. It is of a dark red Colour, very heavy and 
 hard. Moreover, it is almoft the pureft iron-Ore, 
 and mixt with a very fmall Quantity of Arfenick *. 
 But it is rendered refractory, by a kind of Earth not 
 to be affedted by Fire, which may happen to be con- 
 cealed in it. On this Account, the white Regulus of 
 Iron, which is brittle, and very difficult to be ren- 
 dered malleable, requires the greateft Fire to be 
 melted. 
 
 350. Smiris (in German ^cljmergel, in Englifh 
 Emery , and in Dutch Smattll,) is the hardeft of all 
 the iron-Ores that are known : it is a little lefs pon- 
 derous than the Blood-ftone, very refradlory, of a 
 brown Colour, and really contains Iron ; though the 
 extracting of it is not worth the Charges : Where- 
 fore Workmen pound it only, and ufe it to polifh 
 Steel : it is Jikewife employed to cut Glafs, and polifh 
 certain Jewels. 
 
 351. Magnefia (in German UBtunlfCttt? in Englifh 
 Manganefe ) is here and there nicely ftriated with 
 convergent Striae : it has no certain Figure, and is of 
 a greyifh black Colour. It is frequently met with in 
 iron-Mines ; and itfelf contains Iron ; but the ex- 
 tracting of the Iron out of it by Fire, never anfwers 
 the Charges, it being rapacious, and yielding no 
 other but friable Metal. It is of greater Ufe among 
 thofe that make cryftal-Glaftes, to take away their 
 green or blue Colour, and to abate their too great 
 Tranfparency. 
 
 352. There is a kind of Ore not unlike the fore- 
 going (§351), which is of a dark grey Colour, fhin- 
 ing, ftriated, and alfo containing Iron, but rapaci- 
 
 * Some Sorts of Hematites are fo very rich in Iron, as to be ca- 
 pable of taking fo fine a polifh, as to look like burnifhed Steel, par- 
 ticularly a kind called in Italian Pietra di Nicola. 
 
 ous. 
 
Assaying Metals. 139 
 
 ous, and arfenical : for which Reafon Metal lurgifts 
 do not extract Iron out of it. It is called in German 
 
 CSifenmait, GEtfcngltmmm 
 
 353. There is alfo, but efpecially in tin-Mines, 
 a kind of ftriated Ore, made of Filaments of an ir- 
 regular Texture, and dark coloured, which, when 
 fcraped, appears fometimes ol a dark red Colour : it 
 is ponderous enough, and likewife contains Iron, but 
 it is at the fame Time very arfenical ; on which Ac- 
 count it is always rejected by Meta! lurgifts* as being 
 very prejudicial. The Germans call it OToolfratlt, 
 
 Scholion, "7 he iron-Ores hitherto (§ 342 — 353.) men- 
 tioned,, as well as all the other Minerals , are called by 
 different Names , which often flgnify but one and the 
 fame : and as thefe Names vary in all Places , it is im- 
 poffble , and would even be fuperfiuous, here to mention 
 them all : Efpecially , becaufe many of the faid Names 
 are derived from a Comparifon very often defective, of Fi- 
 gures obfervcd hardly once or twice , and of courfe very 
 little effential. 'Therefore you will fee Pepper , Beans > 
 Peas , Confections of Coriander , Cinamon , Iron, &c. 
 reckoned among iron-Ores , by Authors curious of trifling 
 Matters. 
 
 354. We fhall alfo clafs here the Oker of Iron, 
 which feems to have its Origin from comminuted 
 iron-Ore, and efpecially from the yellow Pyrites de- 
 (troycd. It looks like a kind of fattifh Earth, it has 
 the Colour of Ruft, which neverthelefs is rendered 
 fometimes yellow, fometimes darker, by a Mixture 
 of other Earths ; this occafions a Variety in the 
 Weight of this Oker. It is found both in dry and 
 marfhy Places, it forms here and there whole Veins 
 and Strata, and is likewife found, though impure, in 
 almoft every Place, as in Marls, Clays, and Boles. 
 This Oker is fo very rich of Iron in feveral Parts, 
 that it anfwers equally the Charges of extracting, as 
 the belt iron-Ore. 
 
 355. Red-Lead, or red- Chalk, feems to be def- 
 cended from this kind (§ 354.) of Oker, and to have 
 been hardened by a Mixture of Bole and Clay. It is 
 
 of 
 
140 The Art of 
 
 of the reddeft Colour, of a middling Weight, ten- 
 der, fo that it may be eaflly fcraped and figured with 
 a Knife *, it has a foapy Feeling : when expofed to a 
 great Fire, it grows very hard, and aftumes a darker 
 and fhining Colour ; it contains much Iron in it. 
 
 356. It has been obferved, that whenever Sand is 
 of a blackirh Die, it has Iron or Lead in it. But its 
 great Weight fhews, that it contains a confiderable 
 Quantity of Metal. 
 
 3 57. We might very well range in the fame Clafs, 
 all native vitriolicMinerals ; fuch as the ftalacfticVitriol, 
 and the Stones ufed for the making of Ink : for they 
 either are purely of Iron, or at leafb, ccnfift in great 
 Part of Iron corroded by the Acid of Sulphur. We 
 might alfo place here the Lapis Calaminaris , and many 
 other Minerals *, but as the feveral Metals drawn out 
 of them, require each a fpecial Management, we 
 fhall treat of them more at large hereafter. 
 
 358. The Mineral called Flos ferric or Bloffoms of 
 Iron, is nothing but a Stalactites (§ 30, 3), refemb- 
 ling a Germination like that of Coral. It is called 
 Ferri Flos , becaufe it has now and then been found 
 about a calcareous iron-Ore : Nor does it feem to de- 
 ferve this Name, upon any other Account. 
 
 359. There is found, in feveral iron-Mines, efpe- 
 cially thofe of Sweden and Norway *, an Ore called 
 the Magnet or Load -ft one : which is a black ponderous 
 Stone, not very hard, when pure. It is often inter- 
 mixt with Flints and Spaad, in which Cafe it is lefs 
 good. You may fee the wonderful Properties of this 
 Stone, mentioned in the Writings of Natura lifts. 
 But we fhall here chiefly treat of that of its Qualities, 
 by which we may find out the occult Prefence of Iron. 
 The Load-ftone attracts Iron at a great Diftance, and 
 holds it ftrongly to itfelf, unlefsan excefiive Weight, 
 or fome other Obftacles hinder the Effefl *, nor is 
 there any other Body but Iron, that is attra&ed in 
 
 * And in many Parts of England , whereof feveral Specimens are to 
 be feen in the Mufeum of the Royal Society. 
 
 this 
 
Assaying Metals. 141 
 
 thisManner by the Load-ftone ; as has been evidenced 
 by a Multitude of Experiments made with it. Now, 
 whether any Body contains Iron in it or no, we find 
 with the Load-ftone in the following Manner. You 
 firft reduce the Body to be tried into a fine Powder : 
 which muft be done in a brafs-Mortar, efpecially 
 if the faid Body be hard, but never in an iron one : 
 then you put this Powder into a Crucible, having a 
 Cover to it, and well luted, either without any 
 Addition, or, for greater Security, with a fmall 
 Quantity of Tallow ; and make it red hot for about 
 an Hour in a ftrong Fire. When it is grown cold, 
 if you extend it upon a fmoorh Paper, bring the 
 Load-ftone itfelf, or its armed iron-Poles near to it*. 
 If there are any iron-Particles in this Powder, they 
 will apply themfelves either to the Load-ftone itfelf, 
 or to its armed Poles, and hang on it like Beards. 
 When you fee this, wipe off the adhering Particles, 
 that they may fall afunder, and then put the Load- 
 ftone again into the Powder, and move it up and 
 down. By the fame Thing often repeated, you will 
 at laft have taken away all the Iron, leaving only the 
 Particles that partake not of Iron. 
 
 360. But there are very few iron-Ores attracted 
 by the Load-ftone, before they have been made red 
 hot in the foregoing (§ 359.) Manner, not excepting 
 even the Blood-ftone (§ 349)? though ever fo rich of 
 Iron. Which is the more wonderful, becaufe Iron, 
 though adulterated with other Metals, or Semi-metals, 
 and even mixt with Arfenick, is not thereby ren- 
 dered altogether unapt to be attra&ed by the Load- 
 ftone. Antimony is the only metallick Body, that can 
 hinder this Addon. Sulphur can hardly hinder it, 
 becaufe the Blood-ftone juft mentioned, red Chalk, 
 Oker, and the more folid iron-Ores, that are not of 
 the Pyrite kind, lofe but very little, and fome of 
 
 * If you have not a Load-ftone at hand, the Blade of a Knife or 
 ony other polifhed Piece of Iron which hath been touched on a Load- 
 ftone, will have the fame Effeft, but not fo ftrongly, 
 
 them 
 
14 * The Art of 
 
 them nothing at all of their Weight, by being burnt 
 in the Fire. Nor does it feem probable, that there 
 is any Antimony hidden in all thefe Minerals. But 
 what makes this Matter more obfcure is, that the 
 Blood-done, red Chalk, and fome other iron -Ores, 
 without adding any phlogidical Matter to them, are 
 rendered capable of yielding to the magnetick Vir- 
 tue, by being only made red hot in a Veflel well 
 clofed ; while, on the contrary, the other Bodies, 
 when made red hot, require the Addition of a more 
 fixt Phlogidon, without which the Load-done would 
 have either no Iron at all, or a much lefs Quantity 
 of it to attract. On this Account, there have been 
 two Opinions efpoufed by Authors. Some are of 
 Opinion, that mineral Sulphur, and the Acids adher- 
 ing to Iron, hinder it from being attracted by the 
 Load-done ; and that confequently they mud either 
 be difiipated or changed, to reftore to Iron its mag- 
 netick Virtue. But it is repugnant to their being 
 difiipated, that fome Ores made red hot in clofe Vef- 
 fels, without any Addition, and lofing not the lead 
 Part of their Weight thereby, yet become capable of 
 being attracted by the Load-done ; as it is repugnant 
 to their being changed, that mineral Sulphur, and 
 its Acid, are never altered in clofe Vefiels, by Fire 
 alone, without any Addition ; and that on the con- 
 trary the fulphureous Acid, with an Addition of a true 
 Phlogidon, regenerates the true mineral Sulphur, 
 which neverthelefs is fuppofed to redd the Action of 
 the Load-done. Now' the Phlogidon made red hot 
 with iron-Ores, is very proper to revive the Attradli- 
 bility : Nor can this be any way obtained, when the 
 Udulation is made with pure alkaline Subdances, 
 that really change the Acid of Sulphur. The other 
 Opinion, taken from the Decifions of the illudrious 
 Mr. Sthal , is, that Iron is ingendered by a Phlo- 
 gidon, mixt with a ferruginous Earth, by Means of 
 Emulation : which will appear the more probable, if 
 you attend to the following Condderations. i. The 
 Ores and Earths which being made red hot without 
 
 any 
 
Assaying Metals. 143 
 
 any Addition, are not attracted by the Load-ftone, 
 if you melt them either alone without adding any 
 Phlogifton, or only by Means of an unphlogifticalFlux, 
 in the ftrongeft Fire, will turn into a metallick Glafs, 
 not into a Regulus. 2. With this Glafs, and by 
 Means of a due Addition of Phlogifton, you will pro- 
 duce the moft perfeCt Iron in the Fire. 3. Iron de- 
 ftroyed by Acids, Fire, or any other Means, or only 
 turned into Ruft, is not attracted by the Load-ftone : 
 and then when it is melted by a ftrong Fire, without 
 adding Phlogifton to it, the fame Thing happens, 
 that was mentioned (N° 1). Whence it is plain, that 
 by an inflammable Oil, Iron is produced from what 
 was no Iron. See (§ 90 — 9^). Nor is it a Contra- 
 diction to this Opinion, that fome Ores receive a 
 magnetick Virtue, though made red hot without any 
 thing added to them. For nothing hinders the Phlo- 
 gifton, which is necefiary to conftitute the metallick 
 Nature, from being already prefent in the Ore, 
 though it be not as much united with the fine Part 
 that conftitutes the Iron, as is required to give it its 
 metallick Form : fo that it is neceffary previoufty 
 to unite it thereto by the ACtion of a ftrong Fire \ 
 which is always requifite in all Reductions. 
 
 Of Copper, and its Ores. 
 
 361. Native Copper, that is Copper in its metal- 
 lick Form, is found much more frequently and more 
 perfedt than Iron. However, it is yet fomewhat 
 lefs malleable than Copper well forged. 
 
 362. It muft be obferved of copper-Ores in gene- 
 ral, that none of them diftinguifhes itfelf by any cer- 
 tain Figure , but that they are almoft all of them 
 irregular. But the fineft Colours of any Kind, red 
 and the diaphanous Colours excepted, moft commonly 
 betray the Prefence of Copper, when they are to be 
 feen in any Ore. For this Reafon, there is hardly 
 any copper- Ore, that is not mixt with Iron in greater 
 Quantity, than the Ores of other Metals commonly 
 are. Neverthelefs, there is a much lefs Quantity of 
 
144 A rt of 
 
 it in fome of them, than in others. But we reckori 
 thofe that contain lefs Iron in them, to be naturally 
 more fufible than the reft. Such are, 
 
 363. The vitreous copper-Ore (in German iUipftjt 
 < 0 laf$-Gi;rt$). This is of a darkifh violet fky-Colour, 
 like that of a Piece of Steel that has touched a red 
 hot Iron. Befides, this Colour is commonly inter- 
 rupted here and there by Spots and grey Veins. It 
 is very ponderous, and of a middle Hardnefs. One 
 hundred Pound Weight of it, contains from fifty to 
 eighty Pound Weight of Copper. 
 
 364. The azure copper-Ore, is of a molt beautiful 
 blue Colour ; it is fo ft, not very heavy, broken, 
 fhining like blue Glafs ; of all the copper-Ores it is 
 the mod free from Iron , Arfenick , and Sulphur , 
 though it exhales a little of the latter in the Uftula- 
 tion : wherefore, a great Quantity of excellent Copper, 
 is extradled out of it with very great Eafe. 
 
 365. The green copper-Ore is like green Cryftals, 
 often very neatly ftriated : it looks almoft like a Ger- 
 mination *. As for the reft, this Ore has the Pro- 
 perties of the (§ 36 4.) foregoing. 
 
 366. The light, dufty, blew Concretes, Ceerulettm 
 Montanum , in German 215 crgblatl, and the green ones, 
 viride montanum , lefs properly Gold-fodder , in German 
 
 being alfo called both by the Name of 
 copper-Okers , yield a great Deal of very good Copper, 
 when they are pure, which appears from the Colour 
 and Weight of them. But the lighter ones are mixt 
 with unmetallick Earths : thofe that are yellow con- 
 tain iron-Oker : on which Account they are more 
 difficult to be melted, and yield lefs Copper, and of an 
 inferior Goodnefs. This Mountain-blue, and the green 
 are carried here and there by Waters, and apply 
 themfelves to the Outfide of Lumps, like a Paint. 
 
 367. The white Copper Ore, in German 
 
 has been hitherto found only in one fingle Mine of 
 
 * Some of this copper-Ore germinates like the Blofloms of Iron 
 (§ 358 ), looks like white Coral tinged of a bluifh green Colour, 
 and may as properly be called Flores Cupri, or Blofioms of Copper. 
 
 Mifnia ; 
 
Assaying Metals. 14 y 
 
 Mifnia •, the grey one, in German •*$.- and 
 
 the dark affi-coloured, in German liitlpfeivCrlL 
 defcribed by Henckel, in Pyrilol. Pag. 195, 197, are 
 folid, ponderous, and rendered white by Arfenick. 
 The firft Species is diftinguiffied from the white Py- 
 rites (§ 323), by a Colour fomewhat yellowiffi, but 
 the others are diftinguifhed from it, by a much darker 
 Colour : They at the fame Time are all dillinguifhed 
 by their greater Weight, and breaking fmoother : 
 which is more exactly perceived, when you compare 
 together the native Specimens of the Bodies to be dll- 
 cerned. 
 
 368. There is alfo a copper- Ore, called by fome 
 Vitrean, and poffibly not very different from that 
 above defcribed (§ 363), except in the Quantity of 
 Iron it contains : on which Account it is harder than 
 the former, and of a darker Colour : it melts with 
 greater Difficulty than the foregoing ones, and is ne- 
 verthelefs very rich in Copper. We muff like wife 
 rank in the fame Clafs, that kind of dark red Ore which 
 is almoft of a Liver-colour, and which is not eafily 
 difcerned by the bare Sight, from an iron-Ore of the 
 fame Colour. 
 
 369. The merely fulphureous copper-Pyrites is of 
 a yellow gold Colour, with a light Tinflure of green, 
 both within and without ; if you break it, the Infide 
 has a kind of granulated Surface ; it is eafily beat 
 into Powder, and contains Sulphur and Copper in 
 many different Proportions, whence its fpecifick 
 Weight varies likewife very much. But if it is very 
 rich in Copper, and at the fame Time mixt with any 
 Quantity of Arfenick, its gold-Colour becomes yel- 
 lowiffi, and when you break it, the Surfaces are 
 fmoother, neater, and more even. In this Cafe, it is 
 called in German Kupfet;glant$. Very often, it is of 
 the brighteft Green and Blue, both at the Outfide, 
 and between the Chinks : Neverthelefs, it you break 
 it, and thusdifplay a new Surface, thefe Colours feem 
 not to penetrate through the whole Subftance of it. 
 But when the copper-Pyrites are mixt with a confk 
 
 L derable 
 
i^6 The Art of 
 
 derable Quantity of Arfenick, they then look pale* 
 like the lulphureous Copper (§316.) Pyrites; and 
 even are whiter than this, according as the Quantity 
 of the Arfenick is greater. Neverthelefs, they, even 
 in this Cafe, are diliinguifhed from the iron-Pyrites, 
 becaufe they are more ponderous, and give not 
 Sparkles fo eafily, if even they give any, when ftruck 
 with a Steel : which every iron-Pyrites (§316, 323), 
 and any folid iron-Ore will do. 
 
 370. The Reafons why the copper- Ores above' 
 mentioned (§ 363 — 369.) are rendered refractory, 
 and even entirely unfufible, are explained (§ 336). 
 
 371. The yellow lulphureous iron-Pyrites (§ 316.) 
 belongs likewife to this Oafs, though improperly. 
 For it often contains in it a Quantity of Copper, 
 not to be defpifed, but it is looked upon as improper 
 to Copper, and as very refractory, on account of its 
 great Quantity of Iron. In the mean Time you find 
 out whether it contains Copper *, 1. From its not be- 
 ing of a globular Figure : for it is evident from the 
 Obfervations of Henckel , that globular Pyrites are 
 altogether deftitute of Copper. 2. From its unufuai 
 Yellownefs, fpreading through the whole Subftance 
 of it. 
 
 Coroll. From the above-mentioned (§ 369, 371.) 
 Particulars, we may eafily deduce feme Rules, where- 
 by we fhull be able pofitively to affirm, that a Pyrites 
 contains Copper in it. For Inftance, let this be a 
 Rule : The gold greenijh Colour of a Pyrites is a Sign 
 cf its containing a great Quantity of Copper : which is 
 confirmed by Experience. But you cannot by any 
 Means invert this Rule thus : If a Pyrites contains a 
 great Quantity of Copper , it is of a gold greenijh Colour ; 
 becaufe when Arfenick is mixt with a Pyrites, even 
 one that is very rich of Copper, it makes it entirely 
 look pale (§ 369). The fame may be faid of every 
 fuch Rule. 
 
 37 1* The Ore which has been mentioned (§328), 
 tinder the Title of Kupfer-nickel , when we treated of 
 Arfenick and arfenical Minerals, may have a Place 
 
 here. 
 
A s saying Metals. 147 
 
 * here, but only as being improper. It contains a 
 Quantity of Copper not inconfiderable, but it is 
 negledled, becaufe the Cobalt wherewith it is incum- 
 bered, renders it almoft untraClable In the mean 
 Time you are to oLferve, that what renders Ores 
 intractable, is not the Arfenick itfelf, but a kind of 
 Earth,- which is always united to the proper Minerals 
 of Arfenick, efpecially to Cobalt (§ 325), which refills 
 Fuficn very much, and by Means of the Arfenick that 
 is fixt in it, adheres with great Tenacity to Metals, 
 efpecially to Copper and Iron. 
 
 0/ Lead and its Ores . 
 
 372. There are very few Inftances, of native Lead*s 
 exifting naturally pure and malleable, among other 
 Metals *. 
 
 373. Galena tejfulata , or the Cubic Dice-Lead Ore, 
 
 called in Germany is an Ore very rich of 
 
 Lead, confifting of a Quantity of fmall equilateral 
 Cubes, or of oblong Parallelopipeds. But thefe Cubes 
 are, as it were, compofed of very thin, well polifhed 
 Lamina’s, that fhine very bright, and are of a black- 
 iffi blue Colour. However, this Ore is very ponde- 
 rous, foft, and brittle ; it is more fufible than a great 
 many other Ores, though it requires a much greater 
 Fire to be melted, than Lead itfelf : the Caufe of 
 which is the Abundance of Sulphur, that lies hidden 
 in the lead-Ore, and conftitutes almoft one quarter 
 Part of it. In a Fufion well managed, one hundred 
 Pounds weight of pure and folid lead-Ore, will yield 
 from 65 to 70 Pounds weight of Lead. 
 
 374. If the lead-Ore (§ 373.) confifts of fmall, 
 thin, oblong Cubes-, when broken, it appears finely 
 ftriated, and is called in German I&lar ^ptelligec 
 S 5 le^glanfj. 
 
 * Some pure native malleable Lead hath been found at the Day 
 in New England . What is commonly taken for native Lead, is really 
 a very rich, fomewhat malleable iilver-Ore of a lead-Colour. See 
 <§ 385 ). 
 
 L 2 
 
 Sch©* 
 
148 The Art of 
 
 Scholion. I. You will always fee this cubical Figure 
 (§ 373.) in the lead-Ore ; nor was ever any other Fi- 
 gure obferved in it , except fiuch as had been given it by 
 fome external Power or Refiftance ; for , even in this 
 Cafe , it has always the fame Form within. But lead- 
 Ores are called by different Names, according to the va- 
 rious either regular or irregular Application of the Cubes 
 to each other , according to their Magnitude , and their 
 Brightnefs thereon depending , and to their Surfaces , whe- 
 ther fmooth or rough and granulated. There is alfo a 
 Difference obferved in them , as to their Colour *, fome 
 being of a lighter and more bright Colour , and others of 
 a darker blackifiJo Dye. 
 
 Scholion. II. Lazarus Ercker, pag. 161. mentions 
 a red kind of lead -Ore, which he fays is ponderous and 
 like red Clay. But I found that this red Mineral, 
 which appeared to me to be lead- Ore, and has beenfalfely 
 miftaken for Cinnabar, was nothing ?nore than the lead- 
 Ore, having here and there larger Cubes , eafy to be di- 
 ftinguijhed by the Eye without any Help, and an infinite 
 Number of very minute Ones, not to be feen without a , j 
 JMicrofcope , and lying hidden in a red marly Kind of 
 Earth : fo that it does not confiitute a particular Species. 
 
 The fame Author mentions in the fame Place another lead - 
 Ore, refembling a white fandy Stone. There are alfo 
 fandy Rocks, now and then very rich of Lead ; but 
 which being well examined , contain an Ore not in the 
 leaf: different from that deferibed (§ 374). The Rock 
 indeed, which is moft commonly fofi , and on this Account 
 does not deferve to be called Rock, bears a true lead-Ore 
 which is irregular on the Out fide, looks globular, and is 
 filled throughout the Subftance ofi the Rock, with fmali 
 Maffes ofi very various Sizes, and not very bright : fio 
 that , when the Rock is broken, there appears the perfect 
 Species (§ 373) of lead-Ore. Abundance ofi thefie are 
 digged out of the Mines at Breybach. 
 
 375. The Stones that are of a lighter Colour, efpe- 
 cialiy the Flints and their like (§ 29, 4), when they # 
 are mixt with afh or black Colour, or only marked 
 here and there with Veins and Spots of the like Dye, 
 
 thereby 
 
Assaying Metals. 149 
 
 thereby fhew that they contain either Iron or Lead 
 in them. They, in the fird Cafe, are called by the 
 Germans ; and in the fecond Cafe 
 
 But they, by the Word 1151 tty 
 underftand in a fpecial Manner, the ful- 
 phu reous arfenical lead-Ore, which on this Account 
 is rapacious, of a yellow Colour, intermixt with afh- 
 coloured or blackidi Spots, and fomewhat fattifh to 
 the Touch. 
 
 376. The green lead-Ore, is very rare, of a yel- 
 lowifh green Colour very much varied, and half 
 tranfparent. It varies its Figure, though it mod 
 commonly has that of Spaad, fhutting in Form of 
 Nitre, but lefs regular. It is likewife ponderous, not 
 hard, and at the fame Time very rapacious. Ne- 
 verthelefs, one hundred Pound weight of it yields 
 from 70 to 80 Pound weight of Lead. The white 
 and afh-coloured lead-Ore are looked upon as being 
 like this, and are every bit as rare. 
 
 377. The lead- Ores hitherto (§ 373 — 376.) men- 
 tioned, are never rendered refractory by a Mixture 
 of iron-Ore, or of the fulphureous iron-Pyrites (§3 16), 
 as are the other Ores (§336) : forunlefs the Ore that 
 contains Iron, be naturally affociated to the lead-Ores, 
 the major Part of Afifayers, in order to road then> 
 with greater Eafe and Benefit, commonly ufe an ad- 
 dition of Iron, or of its fufible Scoria’s that are dill 
 reducible. Of this, more at large, when we are up- 
 on the Operations. However, the white arfenical 
 Pyrites f§ 323J, if it is ever thought worthy to be 
 claffed among Ores, ought in this Cafe to be except- 
 ed, partly on account of its Rapacioufnefs, and partly 
 on account of the refractory Quality (§ 325.^ of the 
 abundant terredrial Caput Mortuum , that remains 
 of it after the Arfenick has been blown away. 
 
 Of T 1 n and its Ore . 
 
 378. That Tin everexided naturally in a true metal- 
 lick Form, is very uncertain, or at lead, it has been 
 
 L 3 feen 
 
tfo The Art of 
 
 feen very feldom. Neverthelefs, Matthefius fays, 
 that the Thing has happened fometimes. 
 
 379. The mod rich tin-Ore is of a black or dark 
 Colour, of a polyhedral, but altogether irregular 
 Figure ; having its Surface very gloffy. This fur- 
 paffes almoft all the Ores of the other Metals, in its 
 fpecifick Gravity : which feems to be the more won- 
 derful, becaufe Tin is the lighteft of all Metals. But 
 as Arfenick is exhaled alrnofc pure out of this tin-Ore 
 in the roafting, and as the Part of it that remains af- 
 ter the roafting (if you confider how much of the Tin 
 is deftroyed during the whole Time of the Reduction) 
 is to be reckoned purely metallick •, it is eafy enough 
 to guefs at the Caufe of this Gravity. As for the reft, 
 it is of a middle Hirdnefs, and, with regard to the 
 Tin itfelf, is very refractory : for it fuftains a quick 
 Fire, without either melting or growing clammy ; 
 and if you expofe it to a fudden Heat, it neither 
 burfts violently, nor crackles, except when an Ex- 
 periment is made upon large Lumps, among which 
 other Ores, or fome Stones, efpecially of the Quartz- 
 Kind are intermixed. This Ore is called in German 
 ^inn^raupen, in Englifh tin~Grains. 
 
 380. The moft common tin-Ore, called in German 
 
 is of a dark yellowifh rufty Colour : fo 
 that on this Account it cannot, by the bare Sight, 
 be eaftly diftinguifhed from the iron-Ore ; efpecially 
 as it contains itfelf Iron. The Figure of it is irregu- 
 lar, and agrees in every Refpedt with that of the 
 foregoing (§ 3 79) *, for which Reafon it feems to be 
 another of the fame Kind, and to differ from it only 
 by its Degree of Purity. 
 
 381 .We may, after having explained (§ 379.) what 
 happens to the tin-Ore in the Fire, find out by an 
 Experiment made ex tempore in the following Man-* 
 ner, whether there is any Quantity of this Ore con- 
 tained in any Lump offered for Trial, and about 
 
 f Infomnch as fometimes to have a greater fpecifick Gravity 
 than a Piece of Tin of the fame Size melted from it. 
 
 what 
 
Assaying Metals. iji 
 
 what Part of it lies hidden therein. Pound the Lump 
 into a Powder not very fine, and wafh off from ic 
 with Water the light terreflrial Filth that is in it. 
 Then with a fiat, not over broad Shovel, made quite 
 white hot, and having not a high Border, fprinkle 
 your Ore, after having pounded, wafhed, and dried 
 it, and divide it in fuch Manner, that it may not be 
 heaped up in any Place, but quite fpread : This mud 
 be done, that all the fprinkled fmall Parcels of the 
 Ore may grow red hot quick enough, and that the 
 fmall Stones which may happen to be under or in- 
 termixed with them, may not, in their flying afun- 
 der, carry a confiderable Quantity of the Ore away 
 with them. Thus the fmall Stones will be difnpated 
 with a gentle Noife, as alfo the heavy intermixed 
 Ores of other Metals that are lefs weli wafhed ; be- 
 caufe there is hardly any of thefe, that can bear a 
 fudden Heat : There will remain the tin-Ore, be- 
 come of a reddifh Colour, and covered with a kind 
 of 'grey arfenical Flowers. 
 
 382. The Garnate is reckoned among precious 
 Stones: its of an unfettled Figure, though mod com- 
 monly dodecaedral -f, regular enough, not rare, half 
 tranfparent, and having its Name from the Flowers 
 of Pomegranates of which it has the Colour. This 
 now and then contains Tin *, fo that on this Account 
 it deferves to be reckoned among the Ores of this 
 Metal. Neverthelefs, all kinds of Garnates ought 
 not to be referred to this Clafs. For they fell, under 
 the fame Name, Stones that have indeed the fame 
 Colour, but are more tranfparent, vitrean, and are 
 rather of the Nature (§ 29, 4.) of Flints. 
 
 383. The tin-Ores mentioned (379, 380.) which 
 are rendered refradtory by the Stones and Earths 
 mixt with them, may among the other Ores be very 
 well improved by wafhing and roafling, on account 
 of their confiderable Weight, and Condancy in a 
 middle Fire. But they can never be totally freed 
 
 t Ore compofed of twelve Sides. 
 
 L 4 
 
 from 
 
iji The Art of 
 
 from the iron-Ore, efpecialJy that kind of rapacious 
 iron-Ore, that was mentioned (§ 353), which is very 
 often intermixed with tin Ore. For this Reafon, the 
 Tin melted out of thefe Ores, is lefs perfect and true 
 than that yielded by a pure Ore. For Iron mixt 
 with Tin, turns into a hard untraftable (§59.) Regu- 
 lus , that can never be feparated with any Benefit. 
 The copper- Ore, likewife, is fometimes found mixt 
 with tin-Ores, under the Form of Oker, or of Pyrites : 
 it renders- the Tin extremely brittle, when it melts 
 together with it in any' confiderable^ Quantity : But 
 this Ore is more eafy to be fetched out by wafhing 
 and roafting, than the iron-Ore. 
 
 Coroll. From what has been juft (§ 383.) faid, you 
 may eafily guefs, what kind of Tin any Ore will 
 produce *, and why Englilh Tin is the befl of all. 
 For its Ore is, of all tin*- Ores, that which is lefs de- 
 filed with Iron. 
 
 Of S 1 l v e r , and its Ores. 
 
 \ 
 
 384. Pure ductile Silver, not defiled by Sulphur 
 or Arfenick, is found naturally and much more fre- 
 quently than the foregoing Metals, in fmall Malles 
 of many different Figures, elpecially under the Form 
 of Filaments and Scales, in many various Stones, and 
 Earths, and in feveral Kinds of Sand, that are even 
 expofed on the Surface of the Earth 
 
 385. The vitrean filver-Ore, is of an irregular'and 
 altogether unfettled Figure. It is very ponderous, 
 eafy to be flatted with the Hammer, and to be cleft, 
 not much harder than Lead, and much of the fame 
 Colour \ it melts prefently, and foon grows red 
 hot *f. It confifts of Sulphur and of pure Silver : 
 which the Regeneration of it (§ 140.) and the Che- 
 
 * The mod beautiful is in thin Plates with various Furrows on 
 them, fo as to make the Plates refemble real woven filver-Lace. 
 f Thjs is often midaken for native Lead. See the Note to (§ 372-) 
 
 mica! 
 
Assaying Metals. 1^3 
 
 mical Analyfis fhew. It contains above three quar- 
 ter Parts ot Silver. 
 
 386. The horny filver-Ore is half tranfparent, it 
 is of a deeper or lighter yellow or brown Colour, ac- 
 cording as it confifts of larger or fmaller Lumps, it 
 looks like Rofin, and has an irregular Figure on the 
 Outfide ; but when examined clofely within, it ap- 
 pears to confift of very thin Plates. Nor is it very 
 ponderous, nor hard, but eafy to be ground : when 
 brought fuddenly to the Fire, it crackles, burfts at a 
 great Diftance, as moft Ores do, and in this Cafe 
 exhales a fulphureous Smell, and fometimes burns 
 lightly, and finally calls forth fomething arfenical, 
 but in a very fmall Quantity. On this Account, it 
 feems to differ from the foregoing (§ 385), at leaft 
 with regard to the Quantity of Sulphur. For it 
 hardly contains two thirds of Silver in it. 
 
 387. The red filver-Ore, is of a fcarlet Colour, 
 fometimes lighter, fometimes deeper * ; in the firft 
 Cafe, it is tranfparent like the arfenical Ruby *, and 
 in the fecond Cafe, it is of a deeper Dye. It varies 
 its Figure, though it is often of the cryflalline prif- 
 matical Form ; it is heavier than the foregoing 
 (,§ 386.) horny filver-Ore *, but it burfls, when 
 brought near a Candle, or a mild Fire, and the re- 
 maining Part of it melts immediately, before it grows 
 red hot ; and then it emits the difagreeable Smell of 
 Arfenick, together with a thick vifible Smoak : It 
 has fomething fulphureous in it, which is evidenced 
 by its burning violently, and by the Smell of the 
 nitrous Acid, which rifes from it when you fprinkle 
 upon it Nitre put in Fufion, and made red hot: 
 which Phenomena are the Effetts neither of the Ar- 
 fenick, nor of the Silver •, fo that the fcarlet Colour of 
 this Ore feems to proceed from this Caufe (§ 148.) 
 You may fometimes extract with the Load-ftone 
 
 * Much refembling a Garnate, and hath by its outward Appear- 
 ance been miftaken for tranfparent Cinnabar. See the Note (§ 402.) 
 
 (§ 359 -) 
 
IJ4 Th e Art of 
 
 (■§ 359.) out of the Caput Mortuum of this Ore, fome 
 Iron remaining after the Sublimation made in clofe. 
 VefTels ; though you ufe the choicefl Bits of the Ore 
 for this Experiment. However, it has in it the fame 
 Quantity of Silver, as the horny Ore above-menti- 
 oned (§ 3 8 6.) 
 
 3 88. The white filver-Ore, of a light grey Co- 
 lour, of an irregular Figure, pretty ponderous, and 
 very brittle, has at the fame Time fome Copper in 
 it ; nay, it even contains mod; commonly more Cop- 
 per than Silver : fo that it differs from the white 
 copper-Ore (§ 367.) only on account of the Quantity 
 of Silver it contains. It is heavier than the two fore- 
 going (§ 386, 387.) yielding however Jefs Silver than 
 they. The lead-Ore, efpecially the granulated Ore 
 (§ 373), which is of a lighter Colour, is fold for it. 
 See Henckel’s PyritoL Pag. 170, 195. 
 
 389. We have not hitherto known any befides 
 thefe four (§385 — 388.) filver-Ores, though many 
 others are looked upon by fome, as fuch : However, 
 the Thing being well examined, they either are im- 
 proper to Silver, or prove to be compofed of the al- 
 ready mentioned proper filver-Ores *, that is, fome- 
 timesof them all, and lometimesof only fome of them, 
 mixt together in many different Proportions. And 
 this Mixture isfometimes fo very fubtle, that it can 
 hardly be perceived with a Microfcope. And in- 
 deed among the iron, copper, lead, and tin- 
 Mines, already explained (§ 342 — 382), you will 
 fometimes find fome, that will yield no inconfiderable 
 Quantity of Silver ; but as thefe contain more of the 
 other Metals, they on this Account muft be called 
 improper filver-Ores, when they have any Silver in- 
 termixed with their Subftance (§311.) or accidental 
 filver-Ores, when there is only fome Silver adhering 
 to their Outfide (§311.) 
 
 390. The white and grey copper-Ores (§367)9 
 may be called improper filver-Ores, as they are al- 
 ways impregnated with Silver. But the other copper- 
 Ores, though they moft commonly contain Silver, 
 
 fo 
 
Assaying Metals. iyy 
 
 lo that there is fometimes a great Quantity of Silver 
 got out of them ; neverthelefs, cannot always be re- 
 ferred to this Clafs, unlefs you have, in fome fpecial 
 Cafe, found out by Experiments, that they contain 
 Silver in them : for we have not hitherto found out 
 any certain Chara&erifticks, and outward Signs, from 
 which we might decide, whether any Ores contain Sil- 
 ver in them, or no. And if any fuch Characters have 
 been found out, they ufually are regarded only with 
 relation to the Mine that yields the faid determined 
 Ores : fo that People that do not ufe the neceflary 
 Cautions, are often deceived in making an univer- 
 sal Application of fuch external Signs. 
 
 391. It is the fame with the lead-Ores: for the 
 more nicely ftriated, among thefe, the granulated 
 Ores (§374), and thofe that have a changeable 
 Brightnefs, are referred to the Clafs of the Ores that 
 contain Silver : becaufe, there is fometimes fo much 
 Silver in them, that it is of greater Price than the 
 Lead thereto adhering. Some look upon them, and 
 not without Foundation, as real filver-Ores. But 
 this Rule fuffers a great many Exceptions ; while, 
 on the contrary, the lead-Ore con lifting of large cu- 
 bical Parts, which is generally thought to contain 
 Silver, is of equal Value to that of the foregoing, 
 with regard to the Silver. 
 
 392. Finally, it is proper to forewarn every one, 
 
 not to be overhafty in thinking, that there is gene- 
 rally Silver contained in the Ores of Copper, Lead, 
 Iron, &V. becaufe Silver may be extracted out of the 
 Lump, in which this kind of Ore predominates, or 
 out of the Metal that has been melted from it : nay, 
 before you make your Experiment, and determine 
 any thing, you mufl previoufly and with great Care 
 chufe an Ore, perfectly pure, looking homogeneous, 
 and altogether free within and without from any 
 Mixture of Stones, that might perhaps conceal fome 
 filver-Ores (§ 384 — 388). For, unlefs you take 
 
 fuch an Ore for your Experiment, you will never be 
 able to conclude with certainty, from anySilver fetched 
 
 out 
 
1 5 6 The Art of 
 
 out of it, that it is fruitful in this Metal ; as there 
 are very few Ores, that are not fometimes contigu- 
 ous to filver-Ores. But if fuch a Concretion has 
 been made by minute Malles, you cannot ealily per- 
 ceive at firft Sight, whether it is proper to the Ore, 
 or only accidental. Hence the Reafon may be un- 
 derflood, why Reg ulus's precipitated feparately and 
 at different Times, out of impure Bits of Ore, when 
 tried, do not yield at every Time the fame Quantity 
 of Silver, in proportion to that of the Metal, 
 though no Errors are committed in the Operation : 
 which never happens, when the Ore is well beaten 
 and mixt before, or when you ufe it perfectly 
 pure. 
 
 393. The pure (§ 3S4 — 388.) proper Ores of Sil- 
 ver, either thofe that are incorporated with fome pure 
 copper or lead-Ores, or thofe that are only inter- 
 mixed with them, are of themfelves fufible. Now, 
 what Ores are refractory and not fufible, may be un- 
 derftood from what was faid before (§ 334), as it 
 holds equally true of all kinds of Ores. But the tin- 
 Ore requires here a particular Confideration : for, in 
 the Fire, it is refradlory neither alone, nor joined to 
 other Ores : nay, Tin may be very ealily mixt with 
 Silver, but above all with Lead (§41 and 57) : How- 
 ever, it fometimes happens, that, as foon as you in- 
 creafe the Fire, fo as that the Lead may grow red, 
 the Tin feparates from it (§41.) in form of Calx ; 
 which Calx is altogether indiffoluble by Lead, and 
 with great Difficulty diffolved by the Glafs of it, 
 and takes away a great Quantity of the Silver, when 
 this has been mixt before with Tin. But Silver is, by 
 Lead, wafhed off with a flrong Fire, from all he- 
 terogeneous Metal, Gold excepted. Whence it is 
 plain, that Silver and its Ore, when Tin or its Ore 
 is mixt to it, muff be looked upon as refradloty* 
 and for what' 'Reafon-. 
 
 1 
 
 Of 
 
Assaying Metals. 157 
 
 Of Gold, and its Ores * 
 
 394. Gold , whofe Character i dicks are very (§ 6 .) 
 remarkable, is free from Sulphur and Arfenick; of 
 
 j all other Metals it is mod frequently found native; 
 has no certain didin&ive Figure, and confifts only 
 of fmall irregular Mafles. It will not be improper 
 here to mention at lead its principal Matrix's. 
 
 395. There is a Flint , or white Quartz (§ 29. 
 N° 4.) in which Gold commonly lies hidden in very 
 iolid and large Malfes. It is concealed like wife, but 
 more feldom, and in lefs Quantity, in that yellow and 
 blue kind of Stone, which fome call the Lapis corneas . 
 
 396. That kind of blue Stone, which may be cleft, 
 and, on Account of its Colour, is called Lapis Lazu- 
 reus i\ often mod elegantly fparkling with very fmall 
 fpeckles of Gold: The Gold, neverthelefs, is lefs 
 iolid in this Stone, than in the foregoing ones (§395.) 
 
 397. There is hardly any Gravel in the Nature of 
 Things* that does not contain Gold in it: as do 
 likewife leveral fat flimy Earths: But they are fel- 
 dom rich enough in Gold to pay the Charges of ex* 
 tracling it therefrom by wafliing and Amalgamation. 
 But that kind ofGravel which is found in the Channels 
 of Torrents and Rivers, or near them, efpecially 
 where the Canal makes many Windings, is commonly 
 richer in Gold than all the red*. 
 
 398. This native Gold (§ 394.) is very feldom 
 found altogether pure; but is commonly mixed with 
 Silver : Neverthelefs, that which is found in the 
 Gravel and Earths mentioned (§39 7), is rather more 
 mixt w'ith Silver, than that which is wedged into 
 a folid Matrix (§395, 396.) 
 
 4 Lapis Lazuli. 
 
 * Suck Cola Daft is to be found in fmall Quantities, in fome of 
 the Rivers of Scotland . At the Coronation of King Charles I. f ( , me 
 Medals were made of this Gold, with this Legend round the Ede;e, 
 Lx auro , ut in Scotia reperittir. One of which is to be feen in that 
 admirable Collc&ion of Sir Hans Sloans Bart. &c. and many of 
 the Country People have gathered enough to make Rings o'F. ' 
 
 399. No 
 

 158 The Art of 2/1 
 
 (11 *J£/OtOO ^I£337 vl^C tfjn * • 'T**fr>T 
 
 399. No Or<?, that I know, hath' beep; hitherto 
 
 found, in, which .Gold conftituted the greateft me- 
 tallick Part ; fo that I cannot mention "any Ore 
 (§ 31 1.) proper to Gold. The fame is teftified by 
 the Authors that are molt fkilful* in the Knowledge 
 and Trial of Minerals. There are' indeed feveral 
 Ores fold under that Title ; but which, after a ilri< 5 l 
 Examination, are found not to be fuch ; for in thofe 
 Places where Gold is wafhed out from Gravel and 
 Earths (§ 397.) you often find Tin Ores in Grains, as 
 likewife the Gar nates mentioned (§379 — 3#2.) In 
 which Cafe, the rapacious Iron- Ore, called in German 
 (353.) Mclffram, Which is commonly joined' to 
 thefe, is feldom wanting: Nay, it has fometimes 
 happened, that many People deceived by the' red 
 yellowifh Colour of thefe Ores, looking as if there 
 was Gold in. them, have miftaken them For 
 golden Ores: Mean while:, I never faw airy Body 
 grow rich by Means of them, or any Gold melted 
 out of them. The fame thing is to be concluded of 
 the Golden Marchafitks \ To called becaufe they are 
 nothing but fulphureous Marchdfites ^§ 3 1 6.) 
 
 400. There are no Ores improper to Gold, but 
 Silver Ores : For it is in. thefe alone, that Gold pe- 
 netrated with Sulphur and Arfenick, ha^di veiled its 
 metal-lick Form. If Gold is found -in other Ores, 
 there is a much greater Quantity of Silver joined to 
 it: So that they rather belong to the Clafs of the 
 Silver Ores; among which they have already been 
 reckoned. 
 
 Coroll f As Gold ismoftconllant and incorruptible in 
 the Fire (f 6), its molt fubt-le Particles areeafily dif- 
 tinguifhed from Particles ofth£f lame Colour (§316) : 
 
 * LutZi Ercfc, Aula Suhi errancy ,p. Georg.' Leonard. Von 
 
 d.obneyfs'. Naebricbt yom Bergvoerk, p. 125. J . F. Henckcl Pyrito- 
 log. p 167^-2.2:6, 667. iA 
 
 . . ,f The Evgliflj ^ Miners coufoupd.. the. MarcfraJitesan&fyrUp-, and 
 .generally. call- jhem by-,., the common. Marne of Mundicks. See 
 Woodward's Method of Fofll!s.r ... 
 
 For 
 
Assaying Metals. 159 
 
 Tor the foririer not only retain their Colour in the Fire, 
 hut, i^ they 3 have been defiled, they even become the 
 ..more beautiful. Whereas the Colour of the latter 
 changes entirely intoadark Red, and their fhining Sur- 
 face becomes dully ; nay, if* there is then any golden 
 Particles in them, they are but the more confpicuous 
 for it. 
 
 Of Mercury, and its Ore. 
 
 401. Native, fluid, Qiiickfilver , call Virgin Mer- 
 cury, mod commonly lies concealed in an afh-colour- 
 ed loft Stone, eafy to be cleft: In which it may be 
 detected by the naked Eye, or by Meafts of Micro- 
 fcopes, under the. Form of fmall Drops. It is found 
 in great Quantity efpecially about Idria m f, fo that 
 fometimes little Drops of it running together out of 
 th t Matrix, may be gathered in fmall Veffels. 
 
 402. There is but one Tingle Ore of Mercury 
 known, called Cinnabar , of which you will find 
 very good Specimens in every DruggilPs or Apothe- 
 cary’s Shop, under the Name of native Cinnabar*. 
 It is of the.fi neft fcarlet Colour, and, when broke, ap- 
 pears ftriated with fmall parallel Furrows : Befides, it 
 is very heavy and foft, and confifts of mere Sulphur 
 and Mercury ; in fuch Manner however, that- the 
 Quantity of the Mercury is commonly above fix 
 Times greater than that of the Sulphur, and that the 
 Beauty of the Colour of the Cinnabar depends" on ; the 
 Abundance of it: As the Regeneration and Chemical 
 Analyfis of Cinnabar fhew. Hence the Reafon is 
 Jikewife evident, why this Ore is fo very volatile, in 
 comparifon of other Ores. 
 
 •f Idrui is a Town in the County of Gorki* and Province of 
 C.irmoU. See Dr. Bwtb’s Travels, Lond. 1685, Fol. p. 81. 
 
 * There is in London great Plenty of the fineft native Cinnabar 
 or Quickfilver Ore to be had, as yearly imported by the Zaji -India 
 Company from China j it is of 1 beautiful red or vermilion Colour, 
 and Semi-tranfparent; refembling the red Silver-Ore (fee the Note 
 to § 387) but of a lighter Colour. 
 
 403, Mer- 
 
1 60 The Art of 
 
 403. Mercury, and its Ore, Cinnabar (§ 402.) 
 more feldom found than any Metal ; fo that accord- 
 ing to the Calculations of Dr. Hoffman ff , there is 
 fifty Times more Gold got every Year out of the 
 Mines, than Mercury or its Ore. This indeed is 
 very true, but it feems to be no lefs .certain, that 
 Mercury and its Ore offer much more frequently than 
 we think, but are not known to us. This will ap- 
 pear probable to any that will confider, that Metal- 
 lurgies try the Minerals unknown to them, in affrong 
 open Fire only, making with them Scorifications, 
 Coppellations, and various meltingPrecipitations *, and 
 neglect, or perhaps are ignorant of thofe Operations 
 that are made in clofe Veffels *, becaufe they hardly 
 ever think of Mercury, except when Quickfilver it- 
 felf, or the fcarlet Colour of its Ore (§ 402) offers 
 to their Eyes. Befides, the Colour, Weight, and 
 Figure of Cinnabar ("which is neverthelefs moft eafily 
 diftinguifhed from other Minerals, when pure) are 
 altered to fuch a Degree by the other Minerals mixt 
 with them, that it can never be detected by the mere 
 outward View, and without making an Experi- 
 ment. 
 
 Coroll. You will indeed find in the Wojrks of Che- 
 miffs, feveral Experiments mentioned, by which 
 they fay that "Mercury has been fetched out of Mi- 
 nerals ; but all thefe Experiments are here of little 
 Service to us. For, 1. Thefe Minerals are not ex- 
 actly defcribed ; fo that they could not be difxin * 
 guifhed, if they fliould offer to us : And if they have 
 been called by a Name, the fame is alfo common to 
 many other Things, or the Signification of it known 
 to none but the Author himfelf. 2. The Particulars 
 neceffary in the relating of Experiments, have been 
 almoff entirely omitted. 
 
 f DifTert. Phyfico-Chemica, de Mercurio Sc Medicam. ex Mer- 
 curio felediovibus, Thef. II, 
 
Assaying Metals. i 6 t 
 
 Of the Reg ulus of Antimony *, and its Ore. 
 
 404. I am not certain from any Obfervation, that 
 the pure Regulus of Antimony was ever found native ; 
 nor do I remember to have read in any Author, of 
 its having been fetched pure out of the Mine. 
 
 405. The Ore of Antimony, is of the Colour of 
 Jead-Ore (§ 373), it has very fine, long, parallel 
 Striae, in form of Needles, that cut each other acrofs; 
 and more feldom fmall fhining Scales, with a light 
 reddifli Colour intermixed ; it is heavy, and refolves 
 partly into a Regulus (§ 16), and common Sulphur, 
 out of either of which, it may likewife be eafily rege- 
 nerated (§ 333.) by a proper Operation. 
 
 Scholion. The Defcription of the Regulus of Anti- 
 mony (§ 404.) has indeed a very great Affinity with 
 the Defcriptions which we have given of fome iron- Ores 
 (§ 35i> 35 2 ? 353)’ ejpecially (§353); and there is in- 
 deed fo great a Likenefs between them *, that they are 
 fometimes confounded with one another . Neverthelefs* it 
 is eafy to diftingnifh the Ore of Antimony from the reft, 
 hecaufe a fmall Particle of it applied to the Fire of a 
 Lamp , will melt immediately ; which rapacious iron - 
 Ores can either not be put at all in Fufion , or at leafi 
 not without ufing theblow-Pipe (§258). Befides , when 
 a Man has once exactly confidered the external Habit of 
 all thefe Mines , and filled his own Imagination with the 
 Impreffion of it , he finds out a certain Difference , which 
 IV >rds cannot eafily deface, but which is neverthelefs fo 
 remarkable , that he is able for the future to diftinguifh 
 them from each other , by bare lnfpettion . 
 
 Of B 1 s m u t h, and its Ore. 
 
 406. Bifmuth lies fometimes inclofed fo very pure 
 in its Ore, that you need not ufe any other Opera- 
 
 * The common Antimony to be met with in Shop', hath under- 
 gone a Fufion from its Ore, and therefore our Author calls it Regu- 
 lus Antimonii. 
 
 M tion. 
 
1 6t The Art of 
 
 tion, to fetch it out, but breaking of it not very 
 fine ff. 
 
 407. Every Ore of Bifmuth, as is fhewn by the 
 Chemical Analyfis, is reduced to the State of Ore by 
 Arfenick : For this goes out of it by Sublimation. 
 You find in the fame Ore that kind of Earth, that 
 gives an azure Colour to Glaffes, of which we have 
 already fpoken (§ 325, 326), in the Article of Co- 
 balt. Whence it is evident, that the Ore of Bifmuth 
 may without Impropriety be called Cobalt of Bif- 
 muth : The more, becaufe you will find in any Ore 
 of Bifmuth the fame Principles as in Cobalt, only in 
 a different Proportion. 
 
 Scholion. It will not be improper , here to give an 
 Account of the making of Zafre and Smalt , which Kun- 
 kel has fir ft described with Clearnefs , in his Ars Vi tri- 
 aria. For Inftance , Cobalt leaves after the Sublimation , 
 and Bifmuth after the Fufion , a Caput Mortuum, 
 which is in a fpecial Manner called by the Germans 
 OTtfmuflp^raupcrr, when there remains fomething of 
 the Ore of Bifmuth. It contains an Earth , which being 
 melted together with the Ingredients of Glafis , gives Glafs 
 an azure Colour. It is firft beaten into Powder , then 
 Jifited through a fine 1 Sieve, then mixt , by grinding and 
 fiercing , with a very fine Flower , made either of Sand or 
 of white Flints , and which is even double in Quantity^ 
 with regard to the foregoing . If you fpr inkle with JVa- 
 
 ter this compound Powder , which is called Zafre , the 
 whole will then make a Stone of a middling Confiftence : 
 But as this J'prinkling is alwajp done before the Zafre is 
 fold , fame have taken it , on this Account , for a native 
 Mineral. 
 
 But if you grind and mix this Zafre together with a 
 fufficient Quantity, for Inftance , once and a half as ?nuchof 
 
 f In the Mufeuin of the Royal Society are Pieces of Bifmuth- 
 Ore, Pent from Cornwall under various miftaken Names, but fo 
 very rich of Bifmuth, that by only holding a Piece with a Pair of 
 Tongs againfl: a clear Fire, the melting Bifmuth will run down in 
 form of melted Tin or Solder, almolt as foon and as eafy as Cheefe 
 will drop in toahing. 
 
 Pot - 
 
Assaying Metals. 16 $ 
 
 Tot-AJhes , and then melt it in a great Fire *, this pro- 
 duces a Glafs , whofe Colour is almod black ; which how- 
 ever, if thrown into Water immediately after it is put in 
 Fufion , and then ground and ftf ted, produces the finefi 
 blue Powder, which is called Smalt f. 
 
 If the felf-fame Zafre , or the Smalt made of it, is mixt 
 with a hundred limes as much, or more, of cryftalline 
 pounded Glafs, or with any other of the Ingredients cut of 
 which white Glaffes are made \ then the Colour which 
 appeared fo very black in the melted Smalt alone,- turns 
 into the moft beautiful blue faphirine Colour ; whence 
 fome pretend, that the Word Zafre has had its original . 
 
 Of Z i n Kj and its Ore. 
 
 408. Zink, is called in German ConfCafatf 
 
 ttt : whether it is or ever was found native, in the 
 fame Form mentioned (§ 14), is a Secret to me : 
 nor is there any known kind of Ore, out of which 
 this femi-Metal may be melted, in the fame Manner 
 as the other Metals and femi-Metals are melted out 
 of theirs. 
 
 409. Therefore, all the Zink that is prepared in 
 Germany, efpecially at Goflar, is obtained by Subli- 
 mation, not by Eliquation, and not got out of any 
 fingular Ore, but out of fuch an intricate and con- 
 fufed Mixture of different Ores, that feveral other 
 Metals and femi-Metals may be feparated at the fame 
 Time from it. Iron, Lead, and Copper art alfo 
 contained in it in great* Plenty : and are almoft all 
 involved in Sulphur and Arfenick. 
 
 410. There are no peculiar Sublimations made for 
 the extracting of Zink, but, by a Sort of fecondary 
 Operation, it is collected during the Eliquation of 
 the other Metals, efpecially of Lead. 
 
 41 1. It is proper here to explain the Manner, in 
 which the Sublimation of Zink (§ 409.) is made, be- 
 caufe there is hardly any accurate Defcription of it to 
 
 M 2 
 
 f See the Note (§325.) 
 
 be 
 
1^4 7$<? Art 0/* 
 
 be found in Authors. The Ores that yield Zink, are 
 by a long and feveral Times repeated Roafting, freed 
 from Sulphur, and in a Manner from Arfenick by 
 the fame Operation. When laid into Strata (§ 240.) 
 with Coals, they next are put into prifmatical, qua- 
 drangular Furnaces, the Height of which is feveral 
 Times greater than their Breadth and Length. Three 
 of the Sides of every fuch Furnace, are fo many 
 thick Walls ; but the fourth, which is in Front, is 
 fhut up clofe with Flates, cut out of a kind of Stone 
 eafy to be cleft, and hardly above one Inch and a half 
 thick. There is another Plate made of the fame 
 Stone, applied within to the inferior Border of the 
 lowermoft of thefe Plates, and placed in fuch Man- 
 ner, that riling up obliquely and inwardly from the 
 laid Border, it makes a Channel declining towards 
 either Side of the Furnace, ending in a Hole left 
 in that Part of the Furnace, and defigned to carry 
 thence into this Hole, whatever falls into its Cavity. 
 If then the Ores (§ 409.) melt in a great Fire, ex- 
 cited with Bellows, placed below the back-Part of 
 the Furnaces *, at the fame Time the Zink, which is 
 altogether volatile, applies itfelf Drop by Drop to 
 the juft defcribed thin, foremoft, and always lefs 
 hot Wall of the Furnace, and very much likewife to 
 the Joints of the ftony Plates of which it is made ; 
 becaufe thefe Joints form Chinks and Furrows that 
 are inequal. In this Cafe, if the faid foremoft Wall 
 of the Furnace is ftruck lightly many times over, 
 during the Fufion, the Zink flowing down Drop by 
 Drop, falls into the hollow Channel juft defcribed, 
 and is, by its Declivity, determined to run towards 
 the fmall Hole which is at the End of this Channel, 
 and thence to fall and gather into a fmall Veffel put 
 under it. Neverthelefs, a very great Part of the 
 Zink is burnt and diflipated during this Operation ; 
 which is alfo evidenced a Priori , by the eafy Com- 
 buftibility of Zink in a much milder Fire ; and 
 chiefly by the beautiful green Colour of the Flame, 
 that rulhes out of the Furnaces at that Time, and by 
 
 the 
 
Assaying Metals, i 6 $ 
 
 the white, thick Smoak that comes out along with 
 it. For you always fee, and with no fmall Pleafure 
 too, a Flame of this Kind, efpecially towards the 
 End of the Operation. Therefore, out of the vaft 
 Quantity of Ores, which is at feveral Times put into 
 any one of the Furnaces, within the Space of 28 
 Hours, and which is more than fixty hundred 
 Weight, not reckoning the additional Ingredients, 
 you will hardly obtain three, four, or at molt five 
 Pounds of Zink. 
 
 Coroll. It is then plain from what was faid (§408 
 and 41 1.) how difficult it is, to pafs any certain 
 Judgment upon the Ore of Zink, as it proceeds 
 from fo great a Confulion of Ores and Minerals, and 
 in fo lingular a Manner. 
 
 412. However, there are befides the Matrixs of 
 Zink hitherto mentioned, that are found at Gojlar , 
 fome others which may be called Zink-Ores. To 
 this Clafs belongs efpecially the Lapis Calaminaris , 
 or Calamine, in German <E>a(ttTC£, and alfo native Cad - 
 mia 9 to diftinguiffi it from that which is called(§ 89.) 
 Furnace-cadmia . This is of a Figure altogether ir- 
 regular, fometimes fpongy, and now and then folid. 
 It is yellow, gold Colour, red, fometimes grey, or 
 even of a Colour which is a Mixture of all the fore- 
 going : As for the reft, it is not very heavy, nor 
 hard : when roughly broken in Pieces, and thrown 
 into a violent Fire, it immediatly renders the Flame 
 of the Colour mentioned (§ 14), and exhales a white, 
 thick, copious Smoak, which however has not the 
 Smell of Sulphur or of Arfenick, but a fweeter Smell 
 peculiar to it, and vaftly aftringent, and which con- 
 denfates into very light Flowers, which are at firft 
 bluiffi, and then of a greyiffi White. Only take care 
 not to make this Experiment with fuch Bits of the 
 Lapis Calaminaris , as are accompanied with the yel- 
 low fulphureous Pyrites (§316), or with the white 
 Arfenical one (§ 323), or alfo with lead-Ore (§ 373) : 
 for they now and then happen to be affociated with 
 this kind of Stone, Befides, the volatile Part juft 
 
 M 3 defended* 
 
1 66 The Art of 
 
 defcribed, there is a great Deal of Iron in the Cala- 
 mine,, and moreover no inconfiderable Quantity of 
 unmetallick Earth. 
 
 413. You can never, by the only Force of Fire, 
 or by the help of the common reducing Fluxes, pro- 
 duce any Zink out of this Stone (§412). However, 
 the Agreeablenefs of the Flowers of the faid Stone 
 (§412.) with thole of Zink *, the changing of the red 
 Colour of Copper into the yellow gold Colour, which 
 Alteration is effeCled both by the Calamine, and by 
 Zink f (§ 88) *, and finally, the Production of Zink 
 itfelf out of the Lapis Calaminaris , to be obtained by 
 feverai manual Operations, require that we fhould 
 clafs it among Zink-Ores : of this more particularly, 
 when we come to the Operations. 
 
 414. Some Authors have given us feverai Obferva- 
 tions, concerning the Ores that are proper to Zink, 
 and out of which it may be melted, as other Metals 
 are out of their Ores. But though I would not inva- 
 lidate their Authority ; there are however many Rea- 
 fons, why I cannot believe, that the Ores to which 
 they afcribe the Name of Zink, are fuch in reality. 
 For, 1. Zink is confounded with Bifmuth by feverai 
 Authors : fo that both thefe Names are looked upon 
 asfynonymous *, while there is neverthelefs a very great 
 Difference between thefe two Bodies, as it clearly 
 appears from the CharaClerifficks of each, exhibited 
 (§ 14, 15), and which are eafily difcerned by the 
 Senfes ; not to mention greater Differences, between 
 them, which are manifefted by Chemical Operations. 
 It will be enough, for Inftance, to mention one fingle 
 Author, even G. L. de Lohneyfs , a Man indeed of no 
 little Rank among Metallurgifts, and who neverthe- 
 thelefs, fpeaking of the Manner in which the Zink 
 of Gojlar is got- out of ’its Ore, fays ; Hoc Zinquum 
 
 *f Out of Zink and Copper may be made as fine a beautiful 
 yellow Metal, refembling Gold to the Eye, as the famous Bath- 
 metal fo long in vogue, or a more modern Metal at prefent, in 
 great Ufe for Cane-heads, Buckles, and other Toys. 
 
 five 
 
Assaying Metals. 167 
 
 five Bifmutbum avide ab alchemiftis defideratur . See 
 
 his tom UBergtocrcft, p. 83. b. 2. Authors 
 
 have either entirely negleded the Defcription of the 
 Zink they fpeak of ; or, if they have faid a few 
 Words about its Chara6terifticks, the very fame Pro- 
 perties belong likewife exadlly to Bifmuth. Befides, 
 Bifmuth-Ores are rather found in many of thofe Places, 
 which Authors fay contain Zink in plenty, than 
 Zink- Ores : for Inftance, in England , the Zink of 
 which Country is very much talked of *, though at 
 the fame Time it feems hardly to exill at all there : 
 what confirms me more in this Opinion, is a clear 
 Paffage in IVebfter' s Met allograph! a, p, 339 ; where- 
 in this Author owns, that he has to no Purpofe 
 looked out every where for Zink-Ores, efpecially in 
 England *. 
 
 415. The Dutch bring to Europe in their Eajl 
 India Ships, a great Quantity of Zink, which is a 
 little more blue than the German Zink, and in every 
 Refpect more tenacious f. But we know nothing 
 certain, either of the Country where the Ore that con- 
 tains this Zink is digged out, or, and much lefs of 
 the Manner in which Zink is obtained out of it : For 
 they fay no European is granted the Liberty of enter- 
 ing into thofe Countries. 
 
 Of Vitriol, and vitriolick Minerals. 
 
 416. When a Metal or a femi-Metal is difiolved 
 by the acid Salt of Sulphur, in fuch Manner that 
 both may appear under the Form of Salt, when 
 joined together *, fuch a Concrete is flri&ly called 
 Vitriol. 
 
 * Thefe are his Words. I know not, what ufe is made of this 
 Spelter , but only that the Br after s do mix it with Copper, and thereof 
 make their Cement or Solder : for from them we have U, and that at 
 ‘very dear Rates. The Ore of it 1 have not feen, nor as yet could pro - 
 cure ; and I fhculd be very glad to hear that any of it could be obtained , 
 or any of it found in England. 
 
 f h is known in England by the Name of Tutinag. 
 
i<$8 The Art of 
 
 417. We have hitherto found but two Metals in 
 the mineral Kingdom, that are naturally diffolved by 
 this Acid of Sulphur, viz. Iron and Copper. There- 
 fore, they reckon only two native Vitriols, viz. that 
 of Iron, and that of Copper. The former, which is 
 green, femi-diaphanous, confiding of rhomboidal 
 Crydals, and of a fweet, adringent, dyptick Tade, 
 melts fird in the Fire, and cads out an aqueous Va- 
 pour, and then dries up, and turns into a grey Pow- 
 der, which, by increasing the Fire, at lad becomes 
 of a reddifh Colour *, while at the fame Time an acid 
 fuffocating (§22.) Vapour is expelled out of it. But 
 the Vitriol of Copper, when artfully feparated from 
 the foregoing, and rendered pure, is blue, lefs tranf- 
 parent and aqueous, more ponderous, not melting fo 
 eafiiy in the Fire, of a very unpleafant, caudick 
 Tade ; and otherwife not very different from the 
 other. Both thefe Vitriols diffolved in Water, im- 
 part to it their own Colours. 
 
 418. Thefe two Vitriols mod commonly are found 
 joined together ; jud as the two Metals out of which 
 they are extradled when the faid Metals have been 
 diffolved by the Acid of Sulphur, are hardly ever 
 found folitary, but are mod commonly mixt with 
 each other in many different Proportions. In the 
 mean Time, the Vitriol of Iron is very predominant 
 in thefe concrete Bodies. It is an eafy Matter to find 
 out, whether there is any Copper in any Vitriol, if 
 you put a well polifhed Plate of Iron into the Solution 
 of Vitriol : for then there is always fome Copper 
 driven out, which applies itfelf immediately to the 
 Surfaceof the Plate, under the Form of a very fine red 
 Powder. But, whether, or in what fubterraneous 
 Places, the Vitriol of Copper may be found as pure 
 as the blue Vitriol we buy, I indeed know not. That 
 Vitriol feems rather to be artificial, which is fold 
 under the Name of Roman Vitriol , Cyprian Vitriol , 
 He. 
 
 419. Native Vitriol is inherent and diffolved in 
 many Waters : for Water mud always concur,- to 
 
 caufe 
 
Assaying Metals. \ 6 g 
 
 caufe the Acid of Sulphur, to affume the Form of 
 Vitriol together with the Metal *, becaufe no Salt can 
 exert its faline Virtue, unlefs it be diiTolved by Fire, 
 or by Water. Befides, the cryftalline Form and 
 Tranfparency of Vitriols, can never be procured with- 
 out the Intervention of Water. But the vitriolick 
 Salts conftitute many Waters, called on this Account 
 medicinal Waters, as are the Pyrmont Waters, and 
 feveral others. Wherefore, you may alfo ex tempore 
 find out, whether fuch Waters contain Vitriol, by 
 pouring fome Water upon a boiled rough Vegetable, 
 for Inftance upon Tea, Galls, the Herb Tormentil, 
 Snake-weed, &c. for this Mixture turns immediately 
 into a black opaque Ink, ii there is any Vitriol of 
 Iron mixt with it. But whether the Water contains 
 Vitriol of Copper, will appear, if after having put 
 pieces of Iron into it, they are fuccefiively confumed, 
 and the Copper on the contrary precipitated, which 
 is of courfe. Nay, if there is a great Quantity of 
 Vitriol of Copper inherent in the Waters, the Cop- 
 per, on this Account, being abundantly expelled by 
 the faid Pieces of Iron, at laft grows folid, and ap- 
 pears rough and bliftered on the Outfide, and feems 
 to confift within of a great Number of parallel 
 Filaments, and to be more eafy to break in the Di- 
 rection of the faid Filaments, being otherwife of a 
 duftil Nature. In this Cafe, fuch precipitated Cop- 
 per is called by the Germans CoementdlUipfer ; and 
 theWaters which are impregnate:: with an Abundance 
 of Vitriol of Copper, are called Coemsnt^ladet*, 
 This occafions the Cuftom among the Germans, of 
 calling all vitriolick Waters by the Name of I^upfcr^ 
 Waders , though they contain a very great Quan- 
 tity of Iron, and very little Copper. 
 
 420. Pure Vitriol is alfo found here and there in 
 the Mines, in a folid various Form. It is fometimes 
 congealed like Water frozen, and is then called Vi - 
 triolum Stalafticum (§ 357), which is of a green Co- 
 lour, mixt more or lei's with blue, indicating the 
 Prefence of tempered Copper. It is compact, and is, 
 
 neither 
 
170 The Art of 
 
 neither within nor without, of the Figure it affumes 
 when cryftalized according to Art. They have at 
 Gojlar native white Vitriol of this Kind, which being 
 diflolved in Water, and infpiffated again, p'referves 
 its white Colour, and is found no where elfe, as I can 
 remember. It contains Copper and Iron, and fome- 
 thing befides, that is not metallick •, the Nature of 
 which is not yet thoroughly known. So that no 
 body, that I know, has been hitherto able to imitate 
 it fo well, as that the artificial one might not be dif- 
 tinguifhed from the natural. There are befides feve- 
 ral Germinations, and vitriolick Efflorefcencies with- 
 in the Mines, and even in the Surface itfelf of the 
 Earth, they are fometimes of a denfe Nature, fome- 
 times woolly ; they may be found white, green, 
 and bluifh *, an infinite Number of needlefs Names 
 has been given them, which can have no other Deri- 
 vation, but the infinite Variety both of Figures and 
 Colours, reful ting from a fortuitous Mixture of he- 
 terogeneous Matters, and of courfe deferve to be 
 overlooked. 
 
 421. The ink- Stones, Lapides atr ament arii , called 
 in German SframcttkSdetit, are mineral Concretes, 
 in which the Vitriol already perfect (§417.) lies hid- 
 den, but confounded fometimes with many other 
 Earths and Minerals. Whence it again eafily ap- 
 pears, that the Diverfity of thefe Stones is infinite, 
 with regard to their Weight, Hardnefs, Colour, 
 and cannot be determined with Certainty. It 
 likewife follows hence, that the various Names, ta- 
 ken from thefe accidental Differences, are altogether 
 ufelefs, becaufe all the Vitriols extrafted out of any 
 one of thefe Bodies, and purified, are entirely the fame 
 as that already (§417.) mentioned. There are four 
 Species of thefe Stones chiefly reckoned, with regard 
 to the Difference of Colours : viz. the black, the grey, 
 the yellow, and the red ink-Stone. Among thefe, the 
 yellow is very remarkable, by its moft beautiful but 
 very decaying Colour, by its foft Confidence, and 
 by the Quantity of Vitriol it contains. But the others 
 
 cannot 
 
Assaying Metals. 171 
 
 cannot always be diftinguifhed fo eafily ; nay, they 
 commonly enough refemble the Ores of other Metals ; 
 and indeed fometimes carry Particles of feveral Ores, 
 that have grown together with them. Neverthelefs, 
 as they contain Vitriol already perfedt, the vitriolick 
 Tafte is an infallible Charadteriftick of them all ; fo 
 that they immediately manifeft themfelves (§ 417.) 
 to the very firft Taker that brings them to his 
 Lips. 
 
 422. We muft alfo here fpeak of the fulphureous 
 Pyrites of Iron and Copper (§ 316, 347, 3 69). 
 They certainly have in them all the Principles, that 
 may give Birth to Vitriol (§417), viz. Copper, 
 Iron, and the Acid of Sulphur. For fome of the 
 Pyrites of Iron, being expofed in the Air, fplit of 
 their own Accord, and turn in part into Vitriol. Of 
 this kind are the pure, merely fulphureous (§3 1 6.) Py- 
 ritesoflron: But the Pyrites of Copper, even of arfeni- 
 cal (§ 369, 323.) Copper, do hardly fo. The others 
 muft be previoufly roafted, and expofed in the Air 
 for fome Weeks or Months, to produce Vitriol. Of 
 this Kind are the Pyrites of Iron and Copper, and 
 thofe which have fomething arfenical in them, toge- 
 ther with Sulphur, as is obferved by the illuftrious 
 Henckel. Neverthelefs, you muft make a great many 
 Experiments as to this ; for there are fome Pyrites of 
 Iron, which being expofed to the Air, will not turn 
 into Vitriol of their own Accord ; although they do 
 not contain more Copper or Arfenick, than fome 
 others, which turn into Vitriol in a few Days. 
 
 423. There are alfo many Calamine-Stones (§ 412), 
 which will produceVitriol, after a previous Roafting ; 
 though they are not of the Pyrites kind, and though 
 you cannot demonftrate by the Succefs of any Expe- 
 riments, that they contain as much Acid, as is necef- 
 fary for the Generation of the Vitriol that is got out 
 of them. 
 
 Scholion. He that is willing to enquire into the mean - 
 ing of thefe ohfcure Words, Sory, Mify, Chalcitis, Ma- 
 lenteriae, &c. to know the Things they fignified among 
 
 the 
 
i7i The Art of 
 
 the Ancients , will perhaps here find the Place to which 
 they belong . 
 
 Of Allom, and the Minerals out of which it is 
 extracted. 
 
 424. Allom (O) is a Salt of a white or a light 
 reddifh Colour, and of a fweet ftyptick Tafte. When 
 diftolved in Water, and duly infpiflated and grown 
 cold, it forms femi-tranfparent o&oedral Cryftals, 
 which firft melt, boil, and foam in the Fire, and 
 emit Phlegm in great Plenty, and then turn into a 
 light, fpungy, and very white Mafs : But the Fire 
 being increafed, they at laft give the fame acid Spirit 
 as Vitriol (§417), or burning Sulphur (§ 312.) do, 
 there remaining a light kind of white Earth, nearly 
 of the Nature of (§ 31, 2.) Marl. 
 
 425. Allom (§ 424.) is produced, either out of a 
 black, fhining, bituminous Mineral, eafy to be cleft, 
 hence of the Nature of (§ 319.) Sea-Coals, very uni- 
 form, but light, fometimes fibrous, and refembling 
 Wood i or out of a foft bituminous Lump. Thefe 
 Lumps are inflammable, and, when gathered into 
 Heaps, they of themfelves grow hot, and take Fire, 
 fending forth mean while a foetid, bituminous, ftrong 
 Odour, and leaving after they are burnt a kind of 
 fpongy Earth, that has a little Tafte. But when they 
 do not take Fire, but only grow warm, and cleave j 
 then they become very fruitful of Allom : therefore, 
 you muft prevent their taking Fire, by pouring a 
 little Water upon them *, becaufe their happening to 
 be inflamed renders the Mattes unfruitful. 
 
 426. But the other Minerals out of which Allom 
 is produced, are not bituminous, nor of Courfe in- 
 flammable. To this Clafs belong fome Concretes, 
 refembling common Clay, that cleave eafily, as like- 
 wife the Calamine mentioned (§ 412). However the 
 latter, as well as the foregoing (§425.) bituminous 
 Species, requires to be gently roafted previoufly in an 
 open Fire, to produce Allom. 
 
 427. Ic 
 
Assaying Metals. 
 
 i 
 
 427. It often happens, that, while the Pyrites is 
 preparing for the Generation of Vitriol (§ 422.) a 
 confiderable Quantity of Allom comes along toge- 
 ther with the Vitriol *, which may commonly be ob- 
 ferved in ink- Stones (§ 421) ; as thefe often depofite 
 Vitriol and Allom together, by pouring Water upon 
 them •, which however is not common to them all. 
 
 428. New, pure, aluminous Minerals, which are 
 not of the Pyrite kind, when chemically examined, 
 yield but very little of the Acid of Allom, or none 
 at all, or at leaft not a Quantity anfwering to that of 
 the Allom gotten out of them, after they have been 
 a while expofed to the Air. Nor can one fee the 
 Earth contained in thefe Minerals, which remains 
 after the burning (§ 424.) of the Allom. The crude Ca- 
 lamine (§ 412, 423.) likewife when it is pure, not 
 mixt with any Pyrites, nor accompanied with any 
 fleel-grained lead-Ore, appears to contain thefe Prin- 
 ciples in a much lefs Quantity. Nor indeed is there 
 any metallick or unmetallick Earth in this Stone, 
 like the Caput Mortuum of (§ 424.) Allom. But if 
 we muft believe that it contains Acid in reality ; it is 
 hardly conceivable, how it can lie fo much concealed 
 therein. Now we leave it to the Judgment and Ex- 
 perience of every body, to determine whether the 
 Acid of Allom, carried by the Air, is thus depofited 
 in the Matrix of the Allom, according to the Opi- 
 nion of the illuftrious F. Hoffman % or if the new Ge- 
 neration of the two Principles of Allom, that is of 
 the terreftrial and the faline Acids (§ 424.) is made by 
 Means of the Air, or of the Fire, or of both toge- 
 ther, as is thought by Henckel b ; but, as it is hardly 
 pofiible to have an accurate Notion of this Matter, 
 before we know the Operations, we fhall have Oc- 
 cafion to treat of thefe Things more at large, when 
 we come to our practical Part. 
 
 a Obferv. Phyfico-Chemic. L. hi. Obf. 8. pag. 275. 
 
 b Pyritologia, pag. 756. 
 
 Of 
 
174 
 
 The Art of 
 
 Of common Salt, and the Methods by which it is 
 obtained . 
 
 429. There are in feveral Countries Mines eafily 
 come at, out of which the purefc, native, common 
 Salt (§ 20.) is gotten in a folid Form : it is called 
 Sal Gem , or Rock-Salt. This Salt is perfectly pure, 
 white, half-tranfparent, and different from the other 
 common Salt, by its large, compact, and apparently 
 homogeneous Cryflals, which larger Cryftals pro- 
 duced by Art, are a Collection of many fmaller Ones : 
 It is much more permament in the common Air, nor 
 does it contract a Moifture fo foon as the vulgar 
 Kind of Salt. But thefe fo very pure Pieces of Sal 
 Gem are not found in fo great Plenty ; but, as one 
 may eafily guefs, they are now and then infeCted with 
 other compound Minerals that mix with them. But, 
 when thefe foreign Bodies are mixt with the Salt in 
 large Quantities, it is freed of them, by dilfolving it 
 in Water, letting it fettle, and then (training it ; and 
 finally, by evaporating the Brine (for that is the 
 Name of the Solution of it in Water), the Salt is 
 again reflored to its folid Form. But then it is no 
 longer ftyled Sal Gem *. 
 
 430. The whole Ocean, and the feveral mediter- 
 ranean Seas, (or larger Lakes) are full of common 
 Salt : Neverthelefs, the Waters of them all are not 
 equally faturated with it. Some, in one Pound of 
 Water, will have above an Ounce of Salt diffolved ; 
 and fome others hardly half an Ounce, and even lefs. 
 Above all, the Seas that lie under and about the tor- 
 rid Zone, are more full of Salt, than the icy Seas 
 towards the North. The Salt, which is fetched out 
 of them, either by the bare Evaporation in the Sun 
 
 * But Sea-Salt, or the common Salt ufed in domeflick Affairs. 
 
 and 
 
Assaying Metals. 175 
 
 and the dry Air f, or by being infpi (fated on a 
 Kitchen Fire, is called Marine or Sea-Salt %. 
 
 431. Finally, there are many Springs, the Waters 
 of which are impregnated with common Salt, out of 
 which it is obtained in the manner mentioned (§430) : 
 They call it Sal fontium. 
 
 432. Thefe three Species of common Salt (§ 429 — 
 431.) do not differ upon any other Account than 
 
 1. That of the Place where they are found, and 
 from which they have all their peculiar Names. 
 
 2. Of their Purity ; for the heterogeneous Bodies 
 mixt with them, fpoil the Colour and outward Look 
 of the Salt. This is the Reafon why feme Brines 
 drop their Sait eafily, and without any Addition, 
 by bare Evaporation, and fome others with great 
 Difficulty, or not at all, unlefs you add clarifying In- 
 gredients. Mean while, as fuch foreign Bodies are 
 not effential, but merely accidental to common Salt ; 
 they noway conftitute a real Difference *, for any com- 
 mon Salt, provided it be well purified, appears al- 
 ways one and the Erne ||, after many Examinations. 
 You may read on thefe Subjedts F. Hoffm * Ohf. Phyf 
 Chemic. Lib, II. Obf. XVI. G. Agrk. de Re Metallica . 
 Lib. XI. P . Snellius de Sale communis and others. 
 
 433. Salt Ammoniac may be referred to this Clafs, 
 as being a femi- volatile kind of common Salt. They 
 
 •f Is called in Englifh Bay-Salt, the fineft of which comes from 
 the Rocks on the Coafts of Sicily , and great Plenty of it is prepared 
 in the fait- Ponds near la Rochelle in France. 
 
 f Great Quantities of which is made in England by diiTolving 
 rock-Salt in fea- Water, and evaporating the Water till it bears an 
 Egg, which being fet to cool, the Salt fnoots in it in the Form we 
 have it for Ufe 3 the Crystals being hrft dried. The Brine which 
 is poured off, is of a very bitter Take, and is therefore called Bittern ; 
 this again, boiled down, and let to cryftalize, gives a bitter tailed 
 Salt fo much in ufe of late for Purging, and is commonly fold under 
 the Name of Epfom-Salt , from its Refembiance to the Salt prepared 
 cut of thole medicinal Waters. 
 
 Jj Bay-Suit is the nick impure, having more earthy Particles in 
 it. Concerning the beffc Method of making Salt or fea- Water frefh 
 and wholefome to drink, fee thofe curious Experiments in a Book 
 entituled Philo/dphical Experiments , &c, by Stephen Hales, D. D. 
 F. R. S. Lend. 1,739, in 8 vo , 
 
 fay. 
 
ty 6 The Art of 
 
 fay, that this fofiil Salt is found native about the 
 Vulcano’s, or Mountains that vomit Fire, as alfo in 
 the fandy, dry, burning Places that are about and un- 
 der the torrid Zone ; and that it is likewife evapo- 
 rated from the Crevices of the Rocks in Perfia . But 
 the vulgar Salt Ammoniac which is fold, is all arti- 
 ficial, and is produced out of the Bodies, which ac- 
 tually, and in reality contain common Salt, or its 
 Acid, and the volatile alkaline Salt. Becaufe thefe 
 are two Principles, of which every Kind of Salt Am- 
 moniac confifts, and into which it may be refolved 
 by Art ; therefore the Urine of Animals, efpeci- 
 ally of thofe that ufe common Salt ; the Suet of many 
 inflammable Bodies, &c. yield Salt. They fay, 
 that the Salt which is brought us from Egypt , which 
 is the moft common, is prepared by Sublimation, ei- 
 ther out of the Soot of burnt Dung * of Animals 
 alone, or out of this very Soot mixt again with com- 
 mon Salt, and with the Urine of Animals. See Affa 
 Parifina , and Boerhaave'sElem . Chem. T. II. Proc. cii. 
 That which is brought from the Eaft- Indies , not in 
 flat convex Loaves, but in conical Ones, like fugar- 
 Loaves, is rare, and the Manner in which it is made, 
 unknown. It is enough for us to be certain, that 
 every true Salt Ammoniac may be refolved into the 
 two Principia before- mentioned, and that likewife 
 out of thefe. Salt may be made in every Refpect per- 
 fectly like native or artificial Salt. 
 
 Of B o r a c e, and its Origine . 
 
 434. We have already (§ 131.) treated of Borace, 
 as of a Menftruum. It is otherwife, though Jefs 
 ufually, called Chryfocolla, that is, Gold-Sodder : tho* 
 at the fame Time, this Name is much properer to it, 
 than to the green Oker (§ 366.) of Copper ; which, 
 though called by the fame Name, yet is altogether 
 
 * Efpecially the Dung of Pidgeons, and the Urine of Camels. 
 
 different 
 
Assaying Metals, 177 
 
 different from Borax, and on this Account ought not 
 by any Means to be confounded with it. But the 
 vulgar Borax we buy, which they call (refined) 
 when purified, appears to be in every Refpedt adul- 
 terated. That which is crude and called fat Borax, 
 or Tincal, and is brought us from the Eaft, efpeci- 
 ally the Eaft- Indies , is certainly very different from 
 that which is called refined Borax. But we know 
 not yet, what additional Ingredients they make Ufe 
 of for the purifying, or rather the adulterating of it : 
 for they look upon it as a Secret. Nor do the Puri- 
 fyers of Borax willingly admit any Body into their 
 Laboratories, which are chiefly at Amfterdam and 
 Venice . 
 
 435. We obfervea Figure conftant enough in crude 
 Borax or Tincal (§ 434) : It confifts of prifmatical, 
 hexaedral, nitrous Cryftals, truncated on every Side, 
 and fufficiently thick ; neverthelefs, not fo long or 
 regular, as are the nitrous, nor fo clofely joined, as 
 is feen in other Salts, but more fimple and folitary, 
 of a bluifh Colour, pretty hard, ponderous, very diff 
 ficult to be diffolved in Water, of a fweetifh Tafte 
 
 I at firfl, and then having an alkaline after-Taffe ; 
 eafily melting in the Fire, and not fo apt to rife into 
 a Foam, as that called refined Borax. 
 
 436. We have not hitherto heard any certain Re- 
 lation, concerning the Manner in which Borax is 
 primitively obtained ; whether it is found native in 
 the Earth, fuch as it was defcribecl (§ 435) •, or wa fil- 
 ed out of a. certain Matrix, like Nitrp, and then by 
 Cryftallifation reduced to the already* mentioned Fi- 
 gure : which indeed appears to be more probable 
 than the former. 
 
 O/Nitre, and its Matrix and Generation. 
 
 437. Nitre, or Salt-petre (§ 21), is always ingen- 
 dered on the Surface of the Earth *, it is never gotten 
 out of the Mines ; for if you dig into the Earth 
 above one Foot deep, you hardly find any more Ma- 
 
 N trixa 
 
1^8 The Art of 
 
 trix impregnated with Nitre : nor is it even Found 
 at fo great a Depth, unlefs it has been by Waters 
 wafhed off from its Matrix, and thus carried lower 
 down together with the faid Waters : Which, ne- 
 verthelefs, happens in this only Cafe, when the Soil 
 under it is chopped, or of a ffony, porous Nature ; 
 becaufe the Water itfelf can hardly penetrate above 
 two Foot deep into a great many Earths. 
 
 438. The chief Matrix of Nitre are calcareous, 
 clayey, loomy Earths, and a kind of moift Earth 
 which has all its Origine from vegetable and animal 
 Bodies, ddlroyed by the Viciffitudes of the Air. If 
 there join to them Afhes of burnt Vegetables, efpe- 
 cially of thofe out of which a great Deal of fixt alka- 
 line Salt is fetched by Fire ; if the faid Afhes are not 
 quite deprived of their Salt by boiling : and if the 
 fat, oily, rotten ing, or already rotten Parts of the 
 faid Animal, and vegetable Bodies are added ; then 
 a perfedl Generation of Nitre is performed in the faid 
 Matrix : for there is never any Nitre produced in 
 an Earth quite deflitute of all Phlogiflon : you are 
 only to take care, heedlefly, not to miftake for Ni- 
 tre, the calcareous, ftala&ical EfHorefcencies, that are 
 found againfl Bridges and Walls. 
 
 439. Nor is it very important, where the already 
 mentioned (§ 438.) Matrix of Nitre be placed : for 
 there never was yet any Place found unfit for the 
 Generation of Nitre, provided the abovefaid Bodies 
 (§ 438.) do concur to it. However, it is requifite 
 that the Place be quite in the open Air, and tempe- 
 rate as to Moiflure and Drynefs : for an excefiive 
 Humidity wa flies off the Nitre already conceived, 
 and when a diluting Moiflure is altogether deficient, 
 the faline Matters hardly act one upon another. In 
 the mean Time, it is certain that Heat and Cold are 
 here neither much ufeful nor noxious, unlefs both be 
 very exceffive. However, the greatefl Heat of the 
 Sun is to be avoided. 
 
 CorolL It is plain, from what has (§ 437 — 4 39.) 
 already been faid, that Niye may be ingendered in 
 
 all 
 
Assaying Metals. 179 
 
 all Countries, and that fome Places are more proper, 
 fome lefs, for erecting Salt-petre Works. It is like- 
 wife plain, that moil probably the Air is either the 
 inftrumental or the material Caufe, or perhaps both 
 together, of the Generation of Nitre, or at lead car- 
 ries it in its Bofoin. For you infallibly hinder the 
 Generation of Nitre by obilrudfing the Railage of the 
 Air. The Reafon is likewife plain, why the Fail 
 and North- Winds are fo beneficial to the Places 
 where Nitre grows, in thofe Regions, and in the 
 Climates between them, efpecially during the Spring 
 and the Autumn ; while on the contrary, the Well 
 and South-Winds are quite unproductive of it. For 
 it has been obferved, that, in the Spring and Autumn- 
 time, the Fall and North-Winds are neither too 
 moifl nor too dry, efpecially during the Night ; and 
 1 that being too drying in Winter and Summer-time, 
 they parch every thing. But the fouth and welter] y 
 j Winds, being ftormy, and bringing Rains along 
 with them, are there very hurtful : however, it is 
 well worth our Inquiries, nor have we hitherto found 
 out by Experiments fufficiently accurate, whether 
 thefe Winds are detrimental to the nitrous Matter, 
 merely by an excefiive Moifture, or (fuppofing this 
 to be prevented) are hurtful to it upon fome other 
 Account. 
 
 440. Whoever would be pleafed to make Experi- 
 ments in thefe Matters, and to do it eafily, and with 
 little Apparatus, might procure himfelf a Nitre-houfe, 
 by expofing in a proper Place (§439.) the Matter in 
 which it is (§ 438.) ingendered. An Example will 
 clear this Point. Chufe any Place quite open to the 
 
 I Air : However, a Field or a Garden will be belt. 
 Upon the Area of it, which muft be eight Foot long, 
 and as much broad and deep, build a fmall Flat of 
 Mud, having its Top thatched with Straw, and 
 iloaping, to fhelter it from the falling Rains : Lee 
 the Height of it from the Ground be fuch, that a 
 Man Handing upright may walk under the Roof, 
 
 ' Let a Door be made, through which the Artificer may 
 
 N 2 get 
 
 
1 80 The Art of 
 
 get into the faid Hut, and that may be opened and 
 fhut. Befides, leave here and there in the Walls 
 fmall 'Windows with fmall Shutters to them •, that 
 you may at Pleafure admit or keep off the Air from 
 it. Againfl the right, left, and hinder-Walls of this 
 Hut within, contrive fquare Partitions too Foot 
 long, as much broad, and one Foot deep, divided 
 with wooden-Boards one Inch and a half thick. Fill 
 them with many different Com pofitions of the Things 
 mentioned (§ 438). By this Means, you will be able 
 to make feveral Experiments upon this Matter. If 
 you make a Paffe with Mortar *, Afhes, or moiff: 
 Earth, pouring Urine upon it, and fill one of your 
 Partitions therewith ; if befides, you water it a fe- 
 cond Time with Urine, when dry, and beat it well 
 with a Stick, after every fuch watering •, you will 
 find in a fhort Time, that Nitre has foon been ingen- 
 dered in thefe filthy Matters : For, unlefs a very fe- 
 vere cold Seafon happens, a Pound of fuch a Mafs 
 will, in a Month or two, contain about two Ounces 
 of Nitre. Now the Method of finding out whether 
 there is any Nitre in a Matrix, and what Quantity 
 of it lies hidden therein, fhall be fhewn in the fecond 
 Volume of this Work, when we come to the Opera- 
 tions ff . 
 
 441. Befides, the Ores and compound Minerals 
 hitherto (§ 305 — 440.) defended, there are fome, 
 whofe Nature and Principles are not yet fufficiently 
 known ; fo that they cannot have any certain and de- 
 termined Clafs affigned them. Neverthelefs, it is 
 beyond ail doubt, that they no way belong to the 
 Cl a ffes of fuch as yield precious Metals. For Me- 
 tal] tirgiffs and Affayers, in all the Trials they make 
 about Minerals unknown to them, have almoft no 
 other View, but that of finding out, whether Gold, 
 Silver, Copper, &c. may be extra&ed out of them 
 
 * Or the Rubbifh of old Stone-buildings, efpecially where the 
 Cement hath been ftone-Mortar. 
 
 4 Salt-petre is brought to us in the greatefl Plenty from the Eaft~ 
 Indies , but we are not certain whether it may not be found native 
 in thofe Countries. 
 
 with 
 
Assaying Metals, i 8 i 
 
 with Benefit : and when the Negative is the Cafe, they 
 moil commonly forbear from any further Inquiry. For 
 this Reafon, there has been hardly any Mineral hither- 
 to found, that went not through a ftridt Trial in the 
 fame View. There are even a great many compound 
 Minerals, among fuch as have been afcribed to certain 
 Claffes, which are known only in part, and not at all 
 thoroughly. Of this Kind are, for Inftance, the 
 Haem kites or Blood-ftone (§ 349). The filamentous 
 flriated iron-Ore (§ 353). The fhining, fcaly, 
 ftriated iron-Ore (§ 352). The native Manganefe 
 (§ 35 l ) the Principles of which are not known, 
 except that Part of them only, that turns into Iron. 
 For this Reafon, the Iron which moil commonly con- 
 ftitutes the major Part of the Pyrites, has long been 
 a Secret to the Ancients, who only regarded the Cop- 
 per envelopped in it : whence, the many Names gi- 
 ven to many Pyrites are almoft all derived from 
 Copper •, till at la ft fome of the Moderns, efpecially 
 the ingenious Mr. Henckel , gave us a compleat Analyfis 
 of them in his Book cited (§ 399) above. 
 
 442. Among the Minerals not yet examined 
 (§441), that which chiefly dcferves our Confiderati- 
 on is, the Molybdcena , or otherwife called Cerujfa ni- 
 gra, Plumbum marinum , in Englifti Wad or black- 
 Lead , in German • it muft not be con- 
 
 founded with the Galtena, or Steel-grained lead-Ore 
 (§ 373), which though commonly called by the fame 
 Name, yet is altogether different from it *. The 
 black- Lead is a Mineral of a lead Colour, confiding 
 of fmall fhining Scales, fofc, fo as to be eafily fcraped 
 with a Knife. It is much heavier than the glimmer- 
 Stones (§ 310 N° 7), of which it has almoft the whole 
 Texture : it feels much like Soap, and its rubbing 
 
 * Formerly, the almoft only Mine for black-Lead was in Bar- 
 rowdale , near Keswick in Cumberland ; but a very large rich Mine 
 of it was iince found out at Bantiufquis in New- E nglannd by the 
 famous Governor Wintrbop , at his lirft fettling that Country. The 
 aforefaid Mine is at this Day part of the Eftate of his Grandfon and 
 Heir John Winthrop , Efq; it is found by the Curious to contain a 
 great Deal of Silver. 
 
 • N 3 againft 
 
1 82 The Art of 
 
 agalnft folid Bodies, renders them ftippery : whence. 
 Workmen rub their Preffes, and other Tools, with 
 black-Lead inftead of Soap *, partly to facilitate Mo- 
 tion, and partly to cover and keep offRuft, by fuch 
 a Lay of a fhining black Colour. It is likewife com- 
 monly ufed for writing-Pencils. It hardly fuffers any 
 Alteration in the ftrongeft open Fire* ; except that, 
 being thus divided into very final! Particles, it lofes 
 its Colour entirely, and becomes of a Confidence 
 fomewhat fofter. We thall, when there isOccafion, 
 in our fecond Part at large mention this Mineral, 
 and all the Particulars thereto belonging, . 
 
 CHAP. V. 
 
 Of docimafical Operations , 
 
 443 • Hp HOSE Actions which change the Objects 
 J, of the Art, according to the Rules it pre- 
 fcribes, and by Means of the Inftruments it employs, 
 are called by Chemifts Operations . 
 
 444. All the Changes juft (§ 443J mentioned are 
 efteded by Solution and Conjunction ; fo that what- 
 ever the Chemift does, may in general be eaftly re- 
 ferred to thefe two Gaffes, nor can a third Species of 
 Mutation be imagined, notwithstanding all fome can 
 fay, 
 
 445. As the Art of Affaying confifts in a well 
 made Separation of Minerals, especially of Metals, 
 and in a Divifton from each other (§ 1.) of the feve- 
 ral conftituent Parts of them, that the Quantity and 
 Quality of each in particular may be known ; it is 
 plain, that thofe Operations, which belong to the 
 
 * Black-Lead is of great Ufe for making Crucibles which bear 
 the ftrongeft Fire; the Powder of it mixt with Windfor-Loam 
 makes a good Lute for coating Veftels over with, and it is of great 
 Ufe among the brafs-Founders, who rub over the Infides of their 
 
 Moulds with it. 
 
 • general 
 
Assaying Metals. 183 
 
 general Clafs of Solution (§ 444) appertain ft r idly 
 and primarily to this Place ; and that the others 
 which are performed by the Allayer, are only fecon- 
 dary or auxiliary Operations. 
 
 446. As therefore Conjundions are to be confidcred 
 (§ 445.) here as only fecondary *, one may eafily ap- 
 prehend, that the docimaftical Operations cannot be 
 divided in general into Solutions and Conjundions, 
 as chemical Operations are. Nay, any Operation 
 performed by a Che miff or an A flayer, commonly 
 has the Effed of both the Solution and the Conjun- 
 ction , fo that no Solution can ever be performed with- 
 out a new Conjundion, nor any Conjundion without 
 a Solution. For Inftance,. while heterogeneous Bo- 
 dies are feparated from Gold and Silver by Scorifida- 
 tion, do not the Particles of Gold and Silver rnek 
 together into a greater Bulk ? Likewife, do not the 
 Bodies feparated, either of their own Accord, or 
 with an Addition of fome fcorifying Body, melt to- 
 gether into Glafs, and thus join again in another 
 Manner? It will then be very wifely done, always to 
 be attentive to either of thefe Effeds in any Operation 
 whatfoever, and to derive the Differences and Deno- 
 minations of the Operations from the principal of the 
 faid Effeds, and from the Diyerfity of the Apparatus 
 of the Inftruments ('Chap. II. and III), by which the 
 Changes to be effeded, are made in the Obje&s. 
 (Chap. I. and IV.) of the Art. 
 
 447. But there is hardly any chemical Operation', 
 which is not fometimes necefTary to be performed in 
 the Art of Allaying. There are many on the con- 
 trary, which are peculiar to allaying alone. There- 
 fore, we ihall here give a general View of chofe 
 which belong properly to it, or of thofe which, tho’ 
 taken from Chemiftry at large, are neverthelefs very 
 frequently ufed by Aflayers *, and ihall then add fhd're 
 Descriptions of each of them in particular, derived 
 from their primary Differences, their Effeds, and the 
 Methods uteri in performing them ; that any Novice 
 in this Art may thus be eafily led to the Pradiee, 
 
 N 4 when 
 
The Art of 
 
 when we fhall attempt to propofe in a more exad 
 and clear Manner, fpecial Obfervations upon every 
 individual Operation. 
 
 448. Every primary docimaftical Operation may* 
 on Account of its Effect, be called Solution (§444)5 
 fince, in every Operation, the Menftrua , among 
 which I think the Air and Fire have a right to be 
 claffed, effed a true Solution, by interpofing them- 
 felves between the Particles of the Objeds to be 
 changed. 
 
 f Fuji on. 
 
 Vitrification. 
 
 Scorification. 
 
 Coppelling. 
 
 Reduction. 
 
 Amalgamation . 
 
 Sublimation. 
 
 Cementation. 
 
 J 
 
 Thefe may be called al- 
 moji Univerfal; be- 
 caufe they dijfiolve ei- 
 > they the whole Mafs> 
 or at leafi by much the 
 greater Fart of the 
 Subject in Hand. 
 
 f Dry.' 
 
 Now a doci- 
 znafiical So- < 
 lution is ei 
 
 ther 
 
 or 
 
 Roofing. 
 
 Calcination. 
 
 Eliquation. 
 
 ^Precipitation by Fufion. j the Subjetl in Hand 
 
 e We may call thefe 
 Partial, as they all dif 
 (j folve but one Fort of 
 
 l Moifl 
 
 Elutriation. 
 Edulcoration. 
 
 1 jfihiartation. 
 
 Moifi Frecipitation. f 
 
 / dll thefe are Partial, 
 V and feparate fome Farts 
 \ from the others. 
 
 449. When the Cohefion of a folid Body is fo 
 minifhed by the Strength of the Fire, as that it may 
 become fluid ; then it is faid to be in Fufion , or melt- 
 ed *, and the Adion itfelf, whereby this Effed is pro- 
 duced, is called Fufion or Meltings which is the moft 
 frequent among the Operations, that are proper to the 
 Art of Allaying. 
 
 450. All the Hxt Bodies hitherto known in the 
 Nature of things, may be brought into (§449.) Fu- 
 fion ; with this Difference however, that fome melt of 
 themfelves in the Fire, and fome not, unlefs you add 
 to them a dilfolving Body, that is, a Flux (§159 — 1 66.) 
 There are alfo many among the volatile Bodies, that 
 
 may 
 
Assay m S e t a l s. i Bf ' 
 
 may ticTpuFih Fufion ; but 'then they evaporate at V 
 the itpeql ponn^M isM o bn& 
 
 451. When a Body melted (§ 449.) "and grown 
 cold,: ' bfebifles "brittle^ fixt, not difioluble by Water, - 
 and mbits' again when expofed to the Fire ; then it is 
 called' ( &lajs ; " and the Operation which changes it in 
 this Manrie^ ' is called Vitrification. 
 
 452. This Vitrification (§451.) is made ufe of by 
 Metdldf^tev ' to the End, that any Metal irnpri- F 
 foned in a folid Body, may on account of its Weight / 
 defcend and feparate' itfelf therefrom : and when the 
 Metal itfelf affumes the Appearance of Glafs, this 
 Operation is technically called Scarification, in Ger- 
 man tierfcpatfeltng ; and the Glafs thus produced is 
 called Scoria, in German ^cfjlacfee| in Englifh 
 Drofs. 
 
 453. All fixed Bodies experience the fame (§452.) 
 Alteration, not totally excepting even Gold and Sil- 
 ver. There are alfo among the volatile Bodies, fome 
 that can be fixed, and which aiTume the Form of . 
 Glafs again, by adding fixing Bodies to them. 
 
 Scholion. They alfo call Scoria that J aline Mafs r 
 which is produced by melting Metals and Ores | together - 
 with faline (§ 159— -166), and reducing Mutt Nor 
 ought , however, the Word Scoria be then ’ 'underflood of 
 all this Mafs , but only of the vitrified Particles which 
 adhere between the fmall Maffes of the Salts , and which 
 may be : feparate d from them by a Difolution in Water^ 
 and by Filtration. * iNNNzs 
 
 454. It is oftentimes proper, to make, the Scoriir- : 
 cation (§ 352.) in a Vefiel, that may abforb the Scoria;.* 
 itfelf, and retain the metallkk Part. In this Cafe, it . 
 is called Coppelling. T he Tells and alfo Veffels : 
 mentioned (§ 168, 184, 185,) are defigned for tliisii 
 Operation. 
 
 455. It is then felf-evident, that a great A ttenuate 
 tion of the Scoria Is requifite, that it may be able to ... 
 pals through the V eflfeh Nor is there any fitter Body : 
 for this Purpofe than Lead, which by its felf. under-.: 
 going a like A ttenuation in the Fire for this ReakI 
 
 foil 
 
\%6 The Art of 
 
 fon difpo fes to the fame Attenuation the other Bodies 
 to be reduced into fo fubtile a Scoria. 
 
 456. There are Earths, which turn into Metal, 
 by being intimately joined with an inflammable Prin- 
 ciple : As Metals deftroyed, and changed into Scoria 
 or Afhes, are, by their Union with the fame Matter, 
 again reftored to their rnetallick Form. This Ope- 
 ration is called Reduction. 
 
 457. All Metals and femi-Metals may be reduced 
 by this Method (§ 456), except Zink ; which being 
 burnt to Afhes admits of no Reduction. However, 
 the Mixture of Gold and Silver was never radically 
 diflolved by any Experiment hitherto known *, 
 wherefore, both thefe Metals need not be reduced by 
 the Addition (§ 456.) of Phlogifton. 
 
 Coroll. Therefore, we muft upon no Account refer 
 to this Clafs, that Reduction by which the foreign 
 Bodies, which do but conceal the rnetallick Form, 
 are taken away. For Inftance, Sulphur, Arfenick, 
 Salts, &c. 
 
 458. The Obfervations to be made concerning 
 Amalgamation, are already clearly hinted (§ 65 — 68), 
 by what was faid, when we treated of Mercury con- 
 fidered as a Menftruum. 
 
 4 59. When you are to join to a folid fixt Body, by 
 Vapour, another that is volatile, the Vapours mult 
 be confined, left they fhould be too eafily diftipated 
 in the Air ; and the Body itfelf which is to be pene- 
 trated, muft be fo placed, that the Vapours very 
 much agitated by the Fire, may as it were continu- 
 ally lick it *. The Manner of producing them has 
 been already (§ 153.) explained, when we fpoke of 
 the menftrual Acids, which are to be applied in this 
 Manner to Bodies, efpecially to Metals. Therefore, 
 as thefe Things are very ftridtly joined to our Sub- 
 ject:, they muft of Courfe be repeated. But as they 
 moft commonly, in this Operation, lay firft one Stra- 
 tum of the diftolving Menftmum* reduced into Pow- 
 der* 
 
 * Pafs lightly over it. 
 
Assaying Metals. 187 
 
 der, and lightly moiftened, and then another Stratum 
 of the Body to be diffolved, upon the foregoing, and 
 then again one Stratum of the Menftruum, and fo 
 on *, Affayers, on this Account, have called this Oper- 
 ation Cementation, from the Analogy it has with the 
 Works of Mafons, when they make Walls. 
 
 460. However, there are other volatile Bodies be- 
 Tides acid Menftrua (§ 153.) that are joined in the 
 fame Manner (§ 459.) to hxt Bodies. For Inftance, 
 if fuch a Union cannot be made otherwife, than by 
 Means of a ftrong and long-lafting Fire, that may 
 diffipate the volatile Parts, then, by ufing a Cemen- 
 tation, the volatile Menftruum, to which you fome- 
 times add fome fixing Body, is rendered capable of 
 fuftaining a more violent Fire without evaporating, 
 the free Adlion of the Air being flopped ; and the 
 Body itfelf which is thus to be diftolved, being alfo 
 attenuated, and more opened by the fame Adtion of 
 the Fire, is extremely well difpofed to receive foon 
 the volatile Menftruum. Thus Arfenick and Sulphur 
 are conveniently united with Iron and Copper, and 
 are eafily corroded by a fmall Quantity of Acid, to 
 which they refift more obftinately at other Times. 
 Pure Iron impregnated in this Manner with a great 
 Quantity of Phlogifton, changes into Steel : for the 
 Adion of the Air being flopped in this Operation, 
 there are hardly any Bodies totally deprived of their 
 Phlogifton by the Violence of the Fire. Char-coals 
 are fo lead of any ; becaufe, though they were ever 
 fo minutely pulverized, they fuftain for whole Days 
 together the moft violent Fire, in a Veffel which is 
 but negligently covered, yet without being quite burnt 
 to Afhes. But you will in vain expedt the Effect 
 defired, unlefs you ufe an exadl Regimen of the Fire 
 in thefe Operations. 
 
 461. There are fome Bodies fixt of themfelves, 
 which may be rendered volatile, by adding volatile 
 Bodies to them ; fo that they are, by different De- 
 grees of Fire, refolved into dry Vapours. If Vapours 
 thus produced colledt together, when you oppofe to 
 
 them 
 
x 8 8 The Art of 
 
 them the cold Surface of a folid Body, that they may 
 apply themfelves to it, they are called Sublimates, 
 and the Operation itfelf Sublimation : but they are 
 chiefly and efpecially called Sublimates, when they 
 Form a folid Cruft ; and when they remain only un- 
 der the Form of a fine Powder, they are called 
 Flowers. The Sublimation is performed either in 
 clofe VefTels (which Method is fufficientiy explained 
 in almoft all the Writings of Chemiits), or in an 
 open Air, in which Cafe it is particularly called ei- 
 ther Geber or Glauber’s, Sublimation. The latter is 
 not indeed very common, but chiefly known among 
 Metallurgies, in molt of the Operations of which it 
 is always made ufe of, while thefe Vapours apply 
 themfelves to the Walls and Funnels of Furnaces, 
 and form the Scurfs and Flowers of the Furnaces 
 (§ 89 )* 
 
 462. Sublimations are alfo made very well in clofe 
 Vefifels, by the firft Method (§461) *, efpecially if 
 your glafs-Veflels are capable of bearing the Fire : 
 But there are many Foffils, which, though you ufe 
 the violenteft Fire, yet prove very refractory in clofe 
 VefTels ; fo that you can do but very little, or even 
 nothing at all with them. They, on the contrary, 
 are by the fecond Method called Geber’s, preiently 
 refolved into abundant Vapours, in an open Fire, 
 which muil be blown very gently ; as it is eafy to 
 experience in the Calamine, in the feveral Tutties, 
 and the like. But that this Sublimation may be made 
 perfedlly, and the Flowers and Sublimates be exa&iy 
 collected ; a particular Apparatus is required, which 
 may be very conveniently made in the following 
 Manner: Inftead of the Funnel (§ 239. N° 4), put 
 upon the Cover of the melting Furnace a large earth- 
 en Pot, not glazed within, of a round Figure, hav- 
 ing at Bottom four or five Holes almofl: one Inch in 
 diameter ; in fuch Manner, that the wide Orifice of 
 the laid Pot inverted, may be received into the 
 Mouth of the Cover, and the Bottom of it look up- 
 wards : then put upon this Pot in an inverted Situa- 
 
Assaying Metals. 189 
 
 tion another of the fame Kind, fomewhat fmaller, 
 bored at Bottom in the fame Manner as the firft Pot 
 which was fet on the Cover : You may, if there is 
 any Neceflity, put upon this fecond Pot a third 
 of the fame Kind, and in the fame Manner : Secure 
 the Joints of the Cover and Pots on the outfide, with 
 Lute not very tenacious, that the Pots may be eafily 
 taken away and feparated. The Pots, or other Vef- 
 fels adapted to this Ufe, are commonly called Aludu- 
 lior Aludels . 
 
 463. Roafting, called in German Ftoffetf, is when 
 volatile Bodies are feparated from fixt ones by the 
 combined Adtion of Fire and Air. 
 
 Coroll. Therefore this Operation agrees with the 
 Sublimation (§461, 462), when a volatile Body re- 
 folved in Vapours, is collected : becaufe, after this 
 Manner, Sulphur and Arfenick are extracted out of 
 a great many Ores, and are refined. 
 
 464. But this Separation (§ 463.) is fometimes dif- 
 ficult enough *, when, for Inftance, the whole com- 
 pound Body melts in almoft the fame Degree of 
 Fire, that is neceffary to caufe a volatile Body to be 
 diffipated in the Air. Therefore, it is chiefly necef- 
 fary at that Time, 1. Previoufly to pound a little the 
 Body to be roaited, that its Surface contiguous to the 
 Air may be increafed : (2.) A gentle Fire is required : 
 (3.) A freer Accefs of the Air, which is the Vehicle 
 of Vapours. (4.) When the Body reading grows 
 into large Clots, the Surface of it muff be reftored to 
 its former Extent, by repeating the pounding. 
 (5 ) It is neceffary that the Matter be fpread wide, 
 and never collected in a Heap. Bodies refractory in 
 the Fire, are more eafily roafted : for you may con- 
 ftantly ufe a great Fire to them, nor need you repeat 
 the Operation fo often. However, you muff always 
 take Care, that, while the volatile Bodies are diffi- 
 pating, they, at the fame Time, do not take fome- 
 thing from the fixt ones (§ 461). For this happens 
 in a great many Cafes, when you ufe too impetuous 
 
 a Fire 
 
ipo The Art of 
 
 a Fire in the Beginning : to prevent this, they ufe 
 fometimes to add fome fixing Body ; of which we 
 fhail fpeak in a more fpecial Manner, in its proper 
 PJace. 
 
 465. Calcination differs little from roafting 
 (§463, 464), as to the Manner of operating, but 
 only with regard to the Aim of it. For in Calcina- 
 tion (though this be often attended with the Difiipa- 
 tion of the Volatiles) they only have Regard to the 
 fine Comminuting of the Body. Therefore, by Means 
 of this Operation, the Body falls prefently into Duft, 
 under the Fire itfelf of the Calcination, or at leaft 
 fplits eafily, when a moift Air, or Water, comes af- 
 terwards in theWay ; which happens in Lime-ftones : 
 Another Effect of Calcination is, that pliant Bodies 
 affume a brittle Texture, as may be obferved in Me- 
 tals *, and that the hardeft Bodies may be fplit, and 
 thus be afterwards more eafily broken in Pieces : In 
 which Cafe, it is often ufeful all of a fudden to pour 
 cold Water upon calcined Bodies, even when they 
 are hot to the utmofl Degree. You have Inftances 
 of this in Flints, &c. Sometimes the Calcination is 
 better performed by adding certain Helps. Thus 
 Tin turns immediately to a Calx or to Afhes, by ad- 
 ding Lead to it, and by Means of a very ftrong 
 Fire. 
 
 CorolL Thence it is plain, that you muft ufe in 
 Calcination the fame Manner of Operation, as in 
 roafting (§ 464) *, becaufe the former is performed by 
 the Separation of the volatile Bodies : Neverthelefs, 
 it is not fo in others. 
 
 Scholion. Both thefe Operations (§ 463, 4 65.) are 
 inoft commonly confounded with each other, on account of 
 their great Affinity ; fo that fometimes Calcination is 
 called Roafting , & vice verfa. 
 
 466. When any Part of a compound Body melting 
 in the Fire, is feparated from the Reft, in fuch Man- 
 ner, that one Part links to the Bottom, and the other 
 fwims at Top, this Operation is called Precipita- 
 tion, 
 
Assaying Metals, ipi 
 
 tion by Fufion, in German 2 CrocfeciTC ^c!)CtO«ng *. 
 The inferior, heavier Part is called Regulus. 
 
 467. This Operation (§ 4 66.) almoF always re- 
 quires the Addition of fueh Ingredients, as may 
 take away the mutual Connexion between the Parts 
 to be feparated *, that is, the menftrual Virtue, by 
 Means of which one keeps the other in a State of 
 Difiblution. For InFance, the reguline Part (§ 16.) 
 of Antimony, and mineral Sulphur (§ 138.) diffolve 
 each other mutually, and conflitute crude Antimony 
 (§ l A 5 ) j nor can they be feparated from each other 
 by Fire alone, without deilroying the Regulus : But 
 if you add Iron, Copper, Silver, &c. which are 
 more throughly penetrated by Sulphur (§ 147. Co- 
 roll. 3), and are thus reduced to the State of Ore 
 (§ 332) ; then the Regulus of Antimony is freed of 
 the Sulphur *, and links to the Bottom, as it is hea- 
 vier than the additional Bodies then joined to the 
 Sulphur. Such a Precipitation by Fufion, happens 
 in Vitrifications (§ 451), Scorifications (§ 452), and 
 Coppellings (§ 454) while one Part turns into Glafs 
 or Drofs, the other metaljick Part, if there is any, 
 keeping Fill its metallick Form, is colledled at the 
 Bottom of the fpherical Veffel. Therefore, Silver 
 and Gold, which are hardly fubjedl to a perfect Vi- 
 trification, do conFantly remain, and on this Ac- 
 count, though they were in ever fo fmall a Quantity 
 in a Coppell ing, they fhew themfelves very clearly to 
 the Eye, when the Scoria is abforbed ; whereas fo 
 fmall a Regulus of thefe Metals would have been as 
 it were buried and hidden under fo great a Quantity 
 of Scoria. Nor is Precipitation by Fufion lefs ne- 
 ceffary, to obtain almoft all the other Metals, which 
 on this Account are called imperfedt , unlefs, per- 
 haps, you except a very fmall Quantity of native 
 Metal, which, neverthelefs, can hardly be called 
 truly pure. Befides, they are all to be had either in 
 
 * That is dry Parting , or feparating in a dry Manner, without 
 any fluid Menftruum, 
 
 Form 
 
ipz The Art of 
 
 Form of Earth, or in that of a folid Ore : in the firft 
 Cafe, you make Glafs by a bare Fufion : in the fe- 
 cond, if the Sulphur and Arfenick, which together 
 with the metaliick Part do conftitute an Ore, are 
 fcattered by the Roafting (§ 4 63.) the Ore deftitute of 
 the oily Phlogifton, becomes Glafs in a pure Fire ; 
 which Glafs may be mixt with unmetallick Stones and 
 Earths : but, by adding Phlogifton to it, this me- 
 taliick Glafs is reduced to its metaliick Form, and 
 fo long as it keeps under this Form, it cannot be 
 united with the Glafs of the other Species, but finks 
 to the Bottom of it *, except only a very fmall Quan- 
 tity of it, which is detained by the Clamminefs of the 
 Glafs. Therefore the precipitating Body here is 
 truly the Phlogifton. For any Body that takes away 
 the Connexion, by the Removal of which a Precipi- 
 tation is operated, is called precipitating, in German 
 
 468. When fuch is the Nature of the Ores, or of 
 the metaliick Mixtures, that while one Part of them 
 melts in the Fire, the other more* refractory remains 
 ftill folid, then the firft melted in a mild Fire, flows 
 out of the Interftices of the other, and is thus fepa- 
 rated. Which kind of Separation is called Eliquati- 
 on, in German ^aipniitg *♦ 
 
 469. The Perfection of this Operation (§ 468.) 
 requires, 1., the different Fluidity of the Parts that 
 conftitute the Mafs. Lead, for Inftance, melts into 
 one Mafs with Copper in a great Fire ; whereas both 
 cannot diffolve each other in a middling Fire : but if 
 the Mafs compofed of both Bodies confounded toge- 
 ther, is afterwards expofed to a mild Fire on an in- 
 clined Plane, then the Lead alone melts, and the 
 Copper become brittle and fpongy, remains in its 
 folid Form. However, this Separation is not fo per- 
 fectly made, but there remains a little Lead in the Cop- 
 per, and a little Copper is carried away by me Lead : 
 Wherefore, it is requiftte, for this Experiment, that 
 
 * In Englifh Smelting, or running down the Ore. 
 
Assaying Metals. *9? 
 
 thefe Metals be not mixed together in too fmall Pro- 
 portions : for if one thoufand th Part of Lead was 
 mixt with the Copper; £ff vice verfa, the Eliquation 
 delired would not fucceed. 2. It is fometimes necef- 
 fary to add Ingredients, that may either deftroy the 
 Force by which the feveral Parts cohere together, or 
 even fometimes procure an eafier Flux of the Matter 1 
 for the Mixtures of the other Metals, cannot without 
 Additions be feparated by Eliquation, as Copper and 
 Lead were juft faid to be. For Inftance, Gold, Sil- 
 ver, and Copper, confounded together, remain in 
 the fame State in any Degree of Fire. Therefore* 
 to make the Eliquation of the Gold and Silver, out 
 of fuch a Mixture, you muft ufe the fame Additions 
 as in the (§ 4 67.) Precipitation by Fufion. Sulphur 
 added in this Cafe, does indeed difpofe the Copper to 
 abandon the Gold and Silver : but if thefe two, as it 
 moft commonly happens, are mixt in a very fmali 
 Quantity to a very confiderable one of Copper ; then 
 you cannot yet obtain the Separation of them : For 
 befides, that what we faid before (§ 469.) concerning 
 the Eliquation of Copper and Lead, is alfo true 
 here ; Sulphur does alfo render Copper fluid, by al- 
 moft the fame Degree of Fire, by which Gold and 
 Silver are melted. Wherefore, a confiderable Quan- 
 tity of Lead muft be added in this Cafe ; that by 
 Help of it, the Gold and Silver may be diffolved in 
 a gentle Fire ; and thus the Copper be in a Manner 
 walked out of them. 
 
 470. Both thefe (§ 4 66, 468.) Operations are of 
 infinite ufe in Metallurgy : for, by Means of them, 
 minute Portions of Gold and Silver, may, without 
 any great Ex pence be feparated from a large Mafs of 
 other Metals : which it has not hitherto been pofiible 
 to effed with Profit, by any other Method. Never- 
 thelefs, thefe Operations have not been hitherto fo far 
 cultivated, as that Precipitation by Fufion, and 
 Eliquation may fucceed completely in all Mixtures of 
 ^Metals : for which Reafon, Metals that are of a 
 
 O fmall 
 
ic >4 Art of 
 
 fmall Price, mod commonly muft be deftroyed, c# 
 obtain a Separation. 
 
 471. We call Solutions moift:, when a Body is dis- 
 tributed through the very minuted Particles of an 
 aqueous, or in great part aqueous Fluid, in fuch 
 Manner that both may turn into a Fluid to Appear- 
 ance homogeneous, which goes through all Filters 
 without being detained in them, and the fmallelt Part 
 of which contains in it a proportionable Quantity of 
 both the difiolvent and the diftblved Body. The So- 
 lution of Gold in Aqua Regis ; that of Silver in Aqua 
 Fortis /, and that of all Salts in plain Water, are fo 
 many fuch moift Solutions. 
 
 472. That kind of moift; Solution, by which Sil- 
 ver is feparated from Gold by Aqua Fortis , is called 
 in Latin Quart atio *, and deferves a particular Con- 
 fiderarion. If, for Indance, Silver and Gold are con- 
 founded in one Mafs, and the Gold is not lefs than 
 one third Part of the whole Mafs with regard to the 
 Weight : then the bed Aqua Fortis poured upon it 
 is not capable of diffolving the Silver : but if you add 
 more Silver to this Mafs melting in the Fire ; then 
 indeed Aqua Fortis poured upon it, when it is grown 
 cold, will corrode the Silver from it : which is alfo 
 the more drongly performed, as the Quantity of the 
 Gold is lefs than one third Part of the whole Mafs. 
 But Experience has taught us, that Aqua Fortis dif- 
 folves Silver mixt with Gold quickly enough, when 
 the Gold conditutes but one, and the Silver three 
 quarter Parts of the Mafs : Nay, if the Solution is 
 not too impetuoufty performed, the Gold commonly 
 retains in fuch a Proportion, without any Alteration, 
 the fame Figure which txhe whole Mafs had before 
 the Diftfolmion *, fo that in this Cafe there is no Rea- 
 fon to apprehend, that the Gold torn into minute 
 Particles will be diftipated in part : which can hardly 
 be prevented, * when the Silver exceeds the three 
 guarter Parts of the Mafs with regard to the Gold*. 
 
 J da Englilh Parting. 
 
 There# 
 
Assaying Me TA L 35. Ip J 
 
 Therefore, Artificers make it their Study, always to 
 obferve exactly the Proportion juft mentioned : 
 Whence, the Reafon and Origine of the Name 
 Stuart atio , is felf-evident. 
 
 Coroll Now, from what has been faid (§ 471.) it 23 
 eafy to conclude, how fallacious the Examination is 
 made with Aqua Fortis alone (§ ^03.) of the Gold 
 that has been rubbed againft the Touch-ftone. 
 
 473. Edulcoration * is called a kind of moiit 
 (§ 47i-) Solution, when the faline Part adhering to 
 a folid Body not difToluble in Water, is diffolved by 
 an aqueous Fluid ; and then the Solution is feparated 
 from the remaining Solid, either by fubfiding, or by 
 being palled through a Filtre ; and this is repeated 
 over and over, till there remains no fen fi hie Quantity , 
 of the faline acrid Body. 
 
 474. It is proper in this Operation (§ 473.) to in- 
 large the Surface of the Body to be edulcorated, by 
 pounding of it •, that the Solution may have a fpeedier 
 Succefs : for which Purpofe indeed, they moreover 
 break it in Pieces, or ftir it with a Stick : That all 
 the Particles of the Body to be edulcorated, which 
 otherwife would fink to the Bottom, may on all Parts 
 be contiguous to the Particles of the walking Fluid : 
 by which Artifice all Solutions are facilitated. Like- 
 wife, boiling Water is fometimes requifite : for the 
 Heat, by the inward Motion and Rarefablion it oc- 
 cafions, promotes in an extraordinary Manner all fa* 
 line Solutions. 
 
 475. However, a perfefl Ablution of the Salt, is 
 4iot always obtained by this (§ 474.) Method : for, as 
 every Part of the Menftruum, contains in it a pro- 
 portionable Quantity of the Body to be diffblved 
 (§471), and there remains always feme Part of the 
 Menftruum in the Body to be edulcorated 5 it is as 
 evident as Light itfelf, that there remains at the fame 
 
 f That is literally tranllated Fourthing , becaufe the Gold mull 
 be but one fourth , when the Silver is three fourths. 
 
 * Or walking from the Salts. 
 
 O 2 
 
 Tim# 
 
ip 6 The Art of 
 
 Time a proportionable Tart of the Salt, anfwering 
 to the remaining Quantity of the Menftruum. Let 
 us take for an Inftance the fait, alkaline, Afhes of 
 Woods : pour upon them hot Water ; make this 
 boil together with them for fomeTime ; and then by 
 Decantation or Straining, feparate the Lye from the 
 reft : There will remain a* lead one quarter Part of 
 the Lye among the Afhes and of Courfe alfo a pro- 
 portionable fmall Part of the diftolved Salt itfelf: 
 pour frefh Water a fecond Time, and decant it: A 
 Quantity of Salt, though much lefs confiderable, will 
 for the fame Reafon again remain ; and fo on for 
 ever. For which Reafon, this Operation muft be 
 repeated, at leaft fo often as that there remains but a 
 very fmall and infenfible Portion of Salt. 
 
 Coroll. Hence, the Reafon is plain, why Calxs of 
 Gold and Silver made with Acids, are fo frequently 
 reduced with great Lofs : for the Acids as yet ad- 
 hering, being agitated by an impetuous and efpecially 
 an open Fire, carry a great Quantity of Metal away 
 with them not even excepting Aqua Forlis itfelf ; 
 which neverthelefs, is faid to be, and in reality is of 
 a fixing Nature, but that only with certain Limits. 
 
 476. Precipitation is called moift, in German 
 jFalltmg, when a Body, which has been diftolved 
 (§ 471.) the moift way, is again driven out of the 
 Diftolvent, fo as either to fwim in the Menftruum, or 
 to fink to the Bottom of it : which moft commonly 
 looks like Powder ; but the Separation of the Mem 
 ftruum from the Body precipitated, is afterwards 
 performed by either decanting, or filtrating. 
 
 477. This Operation (§ 476.) is performed, either 
 by extrading, or evaporating in a gentle Fire, the 
 diftblving Menftruum out of the fixt diftolved Body ; 
 or by adding fuch a Body, as is greedily diftolved by 
 that Menftruum : as if one Metal diftolved in an 
 Acid, is precipitated by another Metal, or by alka- 
 line Salt i for Inftance, Silver diftolved in Aqua 
 Forth , precipitated by Copper, Copper by Iron, 
 Iron by Zink, and all Metals and Semi-Metals eithe? 
 
 partly. 
 
Assaying Metals. 197 
 
 jfertly, or intirely by pot-Afhes, volatile and urinous 
 Salts. In fhort, a Precipitation is alfo made by pour- 
 ing fuch Things, as cannot diflolve the Body in hand* 
 either alone, or joined to a Menftruum that contains 
 the faid Body, or at lead diflolve it in another Man- 
 ner, or even in a leffer Quantity, than if the Men* 
 ruum had at firft been ufed pure. In the firft Cafe* 
 a total Precipitation is performed, as may be feen in 
 the Precipitation of Silver out of Aqua Fortis , made 
 by Spirit of Salt. In the fecond Cafe, a great De - 
 turbation and Precipitation is made ; but a fecond 
 Solution foon follows : As it happens, when Iron be- 
 ing diflblved in Aqua Fortis , you add to it in a pro- 
 per Manner, a Liquor perfedly clear from alkaline 
 fixt Salt : but then there remains mod commonly a 
 certain Part, which is not perfectly difiolved a fecond 
 Time. In the third Cafe, there is but a partial 
 Precipitation made : You will have an Indance of 
 this, if Mercury diflblved in Aqua Fortis faturated 
 with it, is precipitated by common or ammoniac 
 Salt, or by their acid Spirit. A Precipitation is alfo 
 fometimes made by adding only a Quantity of Water 
 to dilute : Such is that made with Regulus Antimonii 9 
 diflblved in Spirit of marine Salt, or in Aqua Regis : 
 For thefe Menftrua do not diflolve this ferai-Meta!$ 
 unlefs they are concentrated. 
 
 478. All this Precipitation (§ 477.) is helped on 
 by a moderate Heat *, by Means of which the preci- 
 pitating Body enters more eafily into the Menftruum . 
 Then, you mud have a confiderable Quantity of Wa- 
 ter to dilute with, except in the fird Kind of Preci- 
 pitation : For mod commonly, the more concentrated 
 Diflolutions, aflame the Confidence of a Fade, f© 
 foon as the precipitating Body is added to them 1 
 which hinders this from mixing equally with the 
 Solution. 
 
 479. We might annex to mold Solutions (§ 471.) 
 the Elutriation *, which is made, when folid Bodies 
 
 f Or wafhing with plain Water. 
 
 O 3 not 
 
198 The Art of 
 
 not diffoluble in Water, are feparated from each othef 
 by Water very well ftirred, fo as that the lighter, to- 
 gether with the more fubril Ones, may be forced out 
 of the Water, and the Heavier and more folid, that 
 is thofe which refill more, may remain at the Bot- 
 tom of the VeiTels. See what was faid before (§ 337.) 
 of this Operation. 
 
 CHAP. VI. 
 
 Of the Effects and Ufe of the Art of Assaying. 
 
 480. HP H E chief Effects of the Art of AfTaying, 
 Jt are to purify Metals, femi-Metals, and 
 other Foffils, of all the heterogeneous Bodies they 
 are found mixt with by Nature, and tofeparate them 
 therefrom : Nor has the Allayer any other Aim in 
 all his Undertakings, as will more clearly appear in 
 our pra&ical Part : For which Reafon we fhall not 
 at prefent defcend to Particulars. 
 
 481. Nor is it very difficult from thence to con- 
 ceive, how ufeful and neceffary is that Art, which, 
 at the fame Time that it confifts in the Knowledge 
 and Separation of Minerals, and in the appropriating 
 them to the Ufe of Men, affords befides an infinite 
 Number of Benefits to Chemifts, Handicrafts, Phy- 
 ficians, Naturalifts, Metallurgies, &c t The Art 
 of AfTaying is nothing but Metallurgy brought into a 
 narrower Com pafs : Therefore, whoever has per- 
 ceived the Ufe ninefs of the Latter, can never que<* 
 Hion that of the Former. For if the Properties and 
 Nature of a Mineral found, were not previoufiy 
 detected by docimaftical Operations ; who would 
 dare to be at fo ccnfiderable Charges, for the making 
 of a greater Apparatus ? Which mull be chiefly un- 
 derfeed of Silver, and of the Gold concealed in it 2 
 IJecaufe thefe Metals are moil commonly fo inti- 
 mately 
 
Assaying Metals. if? 
 
 fftately adherent to other Metals, that they cannot 
 be diftinguifhed by the bare Sight. 
 
 482. Befides, Aflfaying is neceftary to the other 
 Arts, wherein the Knowledge of the Mixture or 
 Purenefs of Minerals, as well as the Purifying of them* 
 or the feveral Com potions thereof, are required. 
 For this Reafon, its Ufefulnefs is very great, chiefly 
 in that Part of Phyfick called the Materia Medic a 1 
 Becaufe there are a great many Minerals made ufe of 
 in Medicines : Therefore, a Phyfician muft know 
 them, as fo many Jnflruments of his Art : Unlefs he 
 will run an equal Chance, of either hurting or doing 
 Good, or even of doing nothing at all. This will 
 be eafily granted by every one that knows, how fe» 
 cretly the mofl poifonous Minerals, fuch as Arfenick,. 
 Copper, Lead, &c. lie hidden in all the Species of 
 Minerals : So that all of them, whatever they may 
 be, ought to be previoufly committed to the ftriCieil 
 docimaftical Examination, before they are received 
 into the Shops of Apothecaries. 
 
 483. But they above all bellow their Trouble in 
 vain, who being ignorant of the docimaftical Art* 
 yet attempt to make chemical Operations, as thefe* 
 among other Particulars, have in view both the Per- 
 fection of Metals, and a thorough- Knowledge of 
 them. Nor is there any more ridiculous Thought* 
 than to pretend to bring Metals to a greater Degree 
 of Perfection and Purenefs, and at the fame Time to 
 be ignorant of the common Knowledge of, and the 
 Manner of feparating them, a Title they give to the 
 docimaftical Art *. Whence it is no wonder, that 
 Quacks and Boafters very frequently fpend great 
 Riches about the moft trifling Operations. 
 
 484. The utility of Aflaying extends alfo to the 
 Art of making Giafs. When any, for Inftance, has 
 a Mind to make Giaffes of the Colour of Jewels -f\ 
 
 * By way of Contempt. 
 
 f Thus are made the Paftes for imitating antique Gems : anal 
 m this depends the whole Art of Enameling . 
 
200 The Art of, Sec. 
 
 For, in order to this, the Calxs of Metals are mod 
 commonly necedary : Becaufe, the Calx of every 
 Metal, even the lead Quantity of it, tinges Glades 
 with a fpecifick Colour. The refore, that you may 
 with Certainty produce the Colour defired : It is ne- 
 ceffary that your Metals be of the utmoft Purenefs : 
 Now, this can never be effected without docimaftical 
 Operations : For, when but one thoufandth Part of 
 Metal mixes to the Tritt of which Glafs is made, 
 that is to the Mixture of Salts and Flints, to which 
 Litharge or lead- Calx is fometimes added, ycur 
 Glafs is immediately tinged with fome Colour, 
 whereas it was to have none, but be quite cryftaltine. 
 But if you are willing to give your Glafs a certain 
 Colour, to be produced by the Addition of one or 
 many Metals, another Metal mixt with it in ever fo 
 fmall a Quantity, changes it entirely ; hence it is fo 
 very difficult to give the pureft ruby-Colour to 
 Glades. 
 
 485. But the Knowledge of the Art of Adaying, 
 is likewife abfolutely necedary, in the making of 
 phyfical Experiments, efpecially fuch as have a Re~ 
 lation to the Nature of Fire, and its Effe&s upon 
 mineral Bodies : That you may know, whether the 
 Body under Trial is pure, or no : Unlefs you have a 
 Mind to indicate an uncertain Caufe for a certain 
 one, and to fee always fome new Event refulting 
 from the Repetition of the fame Experiment, I 
 might here alledge many Reafons, to demonftrate 
 this Adbrtion : Were I not obliged either to call in 
 Queftion with great Reafon, or intirely to annihilate 
 thofe Experiments, which are fo much valued by the 
 Multitude, and illuftrated with Speculations which 
 their Authors are extremely fond of. But a Word 
 to the Wife is enough ! 
 
 Th* End of the theory of the Art of Affaying* 
 
DOCIM ASIA: 
 
 OR THE 
 
 ART of ASSAYING- 
 
 METALS. 
 
 PART the Second, 
 
 Being the Practice of ASSAYING. 
 
 ■ . > ,1 
 
 Q 
 
1 
 
[ *«3 ] 
 
 TABLE 
 
 O F T H E 
 
 PROCESSES. 
 
 Procefs L 
 
 Proc. II. 
 Proc. III. 
 
 Proc. IV. 
 
 Proc. V, 
 Proc. VI. 
 Proc. VII. 
 Proc, VIII. 
 
 P Recipitation of S ilver (Part L 
 §452, 467) made with Lead , 
 by Scorifi cation ; out of its- 
 eafily-fufible , proper (ibid. §385 — 
 388.) and improper (ibid. § 3 89—* 
 391.) Ore Page 205 
 
 The Separation of Silver cut of the Re - 
 gulus (Proc. I.) by Coppelling (Parti. 
 §454.). 21 1 
 
 1*0 precipitate Silver with Lead by 
 Scorifi cation , out of an Ore that can «* 
 not be wa/hed , <2^ which is ren- 
 
 dered refractory , by a Mixture of un- 
 met allick Earths (Part I. § 334, 336, 
 338.) . . 218 
 
 Precipitation with Lead y by Scorifica- 
 cation , of Silver out of an Ore rendered, 
 refractory by Pyrites (Parti. §316, 
 
 3 2 3r3 42 , 3 6 9 '). , 2 2 * 
 
 Precipitation of Silver out of Iron , by 
 Sc or if cation 222 
 
 Separation of Silver from Copper , by 
 Coppelling. 22 & 
 
 Precipitation of Silver out of Tin, by 
 Scorification . 228 
 
 To examine the Allay of Silver with 
 Copper ? by Coppelling , 230 
 
 o 2 Proc* 
 
[204] Table of the Processes; 
 
 Proc, IX, To precipitate Silver out of its Ore , 
 by Coppelling alone . p, 233 
 
 Proc. X. The purifying of Silver by Lead , in a 
 
 large Left , by the Bl aft of Bellows. 235 
 Proc. XI. purifying of Silver in a large Teft, 
 
 under the Muffle . 238 
 
 Proc. XII. yf Method to feleli Specimens out of 
 Metals that have been refined , as well 
 as out of thofe that are melted together 
 with Sulphur and Arfenick, that there may 
 * be the fame Proportion of the Mixtures 
 
 in the latter , as there is in the former. 
 
 2 39 
 
 Proc. XIII. The Waffling (Part I. § 337, 479.) of 
 an Ore , rendered difficult to be melted , 
 by Means of Earths and Stones . 244 
 
 Proc. XIV. The purifying of Silver with Nitre. 
 
 246 
 
 Proc. XV. The Precipitation .of Silver out of the 
 fame Bodies, as were mentioned in the 
 foregoing Proceffles , by Scorifi cation, in 
 a Crucible. 248 
 
 Proc. XVI. The Precipitation by Iron and Lead , of 
 Silver out of a Mixture containing a 
 great deal of Sulphur. 2 50 
 
 Proc. XVII. The extr ailing of Silver, by Amalga- 
 mation. 252 
 
 Proc. XVIII. The Separation of Silver from the Amal- 
 
 gama. 254 
 
 Proc. XIX. To render Silver very pure, by Preci- 
 
 pitation out of Aqua Fords, with 
 Spirit of Salt , 256 
 
 Proc. XX i To extradl Gold out ^i/rMatrixes.258 
 
 Proc. XXL To render Gold perfectly pure fro?n Sil- 
 ver, by Aqua Regis. 260 
 
 Proc.. XXI L To feparate Gold from Silver, with 
 
 Aqua Fords. 262 
 
 Proc. XXIII, The Silver remaining (Proc. XXI. 
 
 ■N g . 3.) retains feme thing of Gold in 
 " \ and 'the Gold remaining (Proc. 
 
 " XXII. 
 
Table of the Processes. [205] 
 XXII. N°. 2.) fame thing of Silver. 
 
 p. 2 64. 
 
 Proc. XXIV. 5 Vo determine the Quantity of the re- 
 
 maining Silver , which Aqua Forth 
 leaves in Gold. 265 
 
 Proc. XXV. j to invefligate accurately the Allay of 
 
 a Mixture of Gold and Silver . 2 68 
 
 Proc. XXVI. The purifying of Gold by Cementation 
 (Parti. §459, 460.) 270 
 
 Proc. XXVII. The Precipitation and Purifying of 
 Gold by crude Antimony. 275 
 
 Proc. XXVIII, Precipitation of Gold by Fufion (Part 
 I. §4 66.) out of a Mixture eight 
 Carats under Standard. 279 
 
 Proc. XXIX. The Separation of fulminating Gold 
 from the Salts. 2 85 
 
 Proc. XXX. To reduce and precipitate Lead out 
 of a fufible Ore (Part I. § 456, 466.) 
 
 . 287 
 
 Proc. XXXI, To produce and precipitate Lead from 
 an Ore rendered refractory by Pyrites. 
 
 Proc. XXXII. 
 
 292 
 
 Proc. XXXIII. 
 
 The wafting of the Lead-ore out oj 
 Earths and Stones. 294 
 
 To precipitate Lead out of an Ore , 
 rendered refractory by Earths and 
 Stones , and not wajhable. 295 
 
 Proc. XXXIV. To reduce and precipitate Lead out of 
 any of its Ores , by Stratification with 
 Charcoal. ibid. 
 
 The Separation of Lead from Copper * 
 by Eliquation (Part I. §,468.) 298 
 
 To reduce and precipitate Copper out 
 of a pure and fufible Ore> in a clofi 
 Veffel. 301 
 
 Proc. XXXVII. To reduce and precipitate Copper out 
 of Ores (Proc. XXXVI.) rendered 
 refraClory by Earths and Stones that 
 cannot be w a fie d, off'. 30J 
 
 Proc. XXXV. 
 Proc. XXXVI. 
 
 Proc, 
 
[zo6] Table of the Processes. 
 
 Proc. XXXVIII. To precipitate Copper out of an On 
 (Proc. XXX VII.) that contains Iron . 
 
 P* 304 
 
 Proc. XXXIX. TheRoafting of a pyritofe Sulphureous , 
 arfenical*, femi-metallick 3 copper -Ore. 
 
 ibid. 
 
 Proc. XL. 
 Proc. XLI. 
 
 Proc. XLIL 
 Proc. XLIII. 
 Proc. XLIV. 
 Proc. XLV. 
 
 The Precipitation of Copper out of 
 roafted (Proc. XXXIX.) Ore . 307 
 The running down of pyritofe, crude 
 copper -Ore, into a roughs brittle 
 Regulus, by a Stratification with 
 Charcoal . 309 
 
 The melting of pyritofe , crude copper - 
 Ore, in a clofe Veffel , to make a Re- 
 gulus like that of Proc. XLI. 314 
 The farther P urifi cation of the Regu- 
 lus’j of Proc. XLI. and XLII. to 
 make Black Copper. 316 
 
 To find out how much pure Copper 
 may be produced by Scorification , out 
 of black Copper . 3 1 7 
 
 Examination of the Scoria’s of the 
 foregoing Procejfes concerning Copper . 
 
 Proc. XL VI. 
 Proc. XL VII. 
 
 Proc. XL VIII. 
 
 Proc. XLIX. 
 Proc. L. 
 
 324 
 
 The Elutriation or wafhing of the 
 Copper-ore . 32 6 
 
 To find out Copper in a pyritofe Ore, 
 by Solution , and a liquid Precipita- 
 tion. 327 
 
 The Separation of Silver and Copper 
 by fufion with Lead. 323 
 
 The Roafting of Tin -ore. 331 
 
 The wafhing of the Tin-ore , and its 
 farther Preparation for a Reduction. 
 
 Proc. LI. 
 Proc. Lit 
 
 332 
 
 The Reduction of Tin- ore in a clofe 
 Veffel. 33 + 
 
 The Reduction of the Tin-ore ex tem- 
 pore, ' 335 
 
 Proc. 
 
Table of the P rocesses. [207] 
 
 Free. LIII. 
 
 To reduce Tin- ore , by a Stratification 
 with Charcoals . p .336 
 
 Proc. LIV. 
 
 To reduce and precipitate Iron out of 
 its Ore , in a clofe Vejfiel. 337 
 
 Proc. LV. 
 
 The melting of crude brittle Iron , to 
 make it malleable. 341 
 
 Proc. LVI. 
 
 The Preparation of Steel out of ]ron y 
 by Cementation. 344 
 
 Proc. LVII. 
 
 The Production of Steel out of crude 
 
 Proc. LVIII. 
 
 unmalleable Iron , or out of its Ore by 
 Fufion. 348 
 
 The Separation of Mercury out of an 
 tin fulphur eons Ore,, by I) filiation. 350 
 
 Proc. LIX.. 
 
 The reviving of Mercury out of a 
 fulphureous Cinnabar-Ore (Part. I. 
 
 Proc. LX. 
 
 : § 402.) _ # 354 
 
 The running down of Antimony out of 
 : its Ore. 356 
 
 Proc. LXI. 
 
 The roafting of crude Antimony (Proc. 
 LX.) or of its Ore , with and with- 
 out Additions. 357 
 
 Proc. I.XII. 
 
 The Reduction of the Calx’s of Antimony 
 (Proc. LXI.), into a, femi-metailick 
 
 Proc. LXIII. 
 
 . Regulus. 361 
 
 The Precipitation of Regulus of Anti - 
 mony , by Metals (Parti. §147. Coroll. 
 
 Proc. LXIV. 
 
 3.) Iron is taken for an Example. 364 
 The melting ^Bifmuth out of its Ore, 
 
 Proc. LXV. 
 
 .367 
 
 Zink (Part I. § 14.) is fublimed into 
 Irreducible Flowers . 37 0 
 
 Proc. LXVI. 
 
 The Cementation and Fufion of Copper 
 
 Proc. LXVII. 
 
 with Zinh Ore. 
 
 The Difiillation of Sulphur out of the 
 Pyrites, and other fulphureous Mine- 
 
 Proc. LX VIII. 
 
 rals. 380 
 
 The reffifying and fubliming crude 
 Sulphur (Pr.LXVII.) intoFlowers.fS 3 
 
 Proc. LXIX. 
 
 Separation of Arfenick out of its Ore y 
 by Sublimation . 391 
 
 Proc. 
 
j^xoB] Table of the P rocesses. 
 
 Proc. LXX. 
 
 Proc. LXXI. 
 
 Proc. LX XII. 
 
 Proc. LXXV. 
 Proc. LXXVI. 
 
 Mercury feparates mineral Sulphur 
 from Arfenick. P -397 
 
 5 The purifying of Arfenick by Sublima- 
 tion with fixt Alkali , to make it white 
 and cryftalline , . 400 
 
 Arfenick is reduced into a femi-metallick 
 Formp with ^ Phlogifton, 402 
 Proc. LXXIII. To ex traffi Vitriol out of the Ink-ftones 
 (Part I. § 421.) and to cryftallize it.. 
 
 406 
 
 Proc. LXXIV. The making of Vitriol out of the Ores 
 of Iron and Copper. ,’T'. 409 
 
 P reparation of A 1 In m . 413 
 
 The Preparation of Nitre,/ 416’ 
 
 Proc. LX XV II. T 0 try faline W aters. 420 
 
 Proc. LXXVIII. To try , how much Glafs the Caput 
 Mortuum of Cobalt , or of Bifmuth , 
 will be able to change into blue Smalt. 
 
 • 422 
 
 Proc. LX XIX. To find out what fort of Metal lies hid- 
 den in an Ore unknown , from the Co- 
 lour it gives GlafTes. ' 4 24X 
 
 Proc. LXXX. - The rooking of common Glafs, and the 
 Extraction of Salts out of Afhes 9 for the 
 preparing of them. 434 
 
 Proc. LXXXI. The Preparation of the Salts 9 and the 
 making of cryftalline Glafs. 437 
 
 Proc. LXXXII. The chufing and preparing of Flint s 9 
 for the making of cryftalline Glafs . 
 
 439 
 
 Proc.LXXXIII. The Compofition of cryftalline Glafs . 
 
 440 
 
 Proc. LX XXIV. To tinge Glaffes with Metals , and other 
 Bodies' . •* 441 
 
 Proc. LXXXV. Of Hydroftatical and Statical Exa- 
 minations of Metals and Minerals . 447 
 
 DOCI- 
 
[ * 0 > ] 
 
 DOCIM ASIA: 
 
 O R T H E 
 
 ART of ASSAYING 
 
 METALS. 
 
 PART the Second, 
 
 Being the Practice of ASSAYING. 
 
 Wherein the Manner of performing the doci- 
 maftical Procefles is taught. 
 
 Preliminary Difcourfe . 
 
 C Hemifts call Procejfes thofe Apparatus’s, by 
 which they perform thofe Adions, whereby 
 certain determined Changes are produced in 
 the Objeds of their Art. Therefore they have been 
 in another Place (Part I. § 443.) called Operations. 
 For as a fimple Adion, when alone, cannot always 
 effed the defired Change ; it is eafy to conceive, 
 that, not only fimple Operations, but alfo many of 
 them combined together in a thoufand different Man- 
 ners, are comprehended in the ProcelTes. Whence it 
 happens, that fo great, nay, an infinite Number of 
 Proceffes may be compofed of the few Operations we 
 have (Part I. Chap. V.) mentioned : For according 
 as thefe are varioufly employed and managed about 
 the fame Subjed, fo there are many various Procefles 
 
 occafioned^ 
 
20 z The Art of 
 
 occafioned, and as many Effects produced upon the 
 Objed ; though thefe different Series of Operations; 
 do not always anfwer the Intention of the Artificer* 
 Therefore, as the Change of the Subject, which is 
 our chief Purpofe, cannot be perfected in the Pro- 
 teffes by a fimple Operation ; it is evident, that we 
 cannot here proceed according to that Series which 
 we have given (Part I. § 448),' in the Table of 
 Operations; partly, becaufe, in the proceeding, the 
 greateft Skill conftfts, in chafing the Operations necef- 
 fary for the Change proportionably to the Variety 
 of the Subject, and the Intention, and in compofing 
 them fuitably 5 which cannot be done, when any 
 Procefs is refolved into its fimple Operations, and 
 thefe afterwards grammatically referred to one and 
 the fame Clafs : Partly, becaufe a great many che- 
 mical Operations, not properly belonging to our 
 Suhjed, nor even mentioned, are often made ufe of 
 in a fuhfidiary Manner *, for Inftance, Diftillations, 
 Evaporations, Cryflallizations, and the like. For, 
 in the Explication we are about to give of the doci- 
 maftical Procelfes, our chief Regard muff be, to fa- 
 tisfy the Underflanding rather than the Memory of 
 Beginners ; that it may be an eafy Matter for them 
 to imitate the Procelfes explained to them. We gain 
 the fir ft of thefe Ends, by giving the firft Rank to 
 thofe Procelfes, which being of themfelves intelligi- 
 ble, require not the Knowledge of the following, 
 but are rather of Help, for the better Underflanding 
 of them, or at lead fuppofe nothing of what fol- 
 lows, that may not immediately be explained in a few 
 Words, or be underftood from what precedes, by 
 Help of a ftiort Theory. Likewife, thofe that are 
 more eafy to be done, niuft as much as poffible be put 
 before®the more difficult. Then, if many Operations 
 are required for producing the Effed, it will be pro- 
 per to divide the whole Apparatus into fome Prcceffes* 
 left, being fo numerous, they fhould perplex one 
 another ; and, as much as poffible, to confider fepa- 
 rately the different Changes, after having deduced 
 
 them 
 
Assaying Metals. 105 
 
 them feparately. For the fame Purpofe, likewife, 
 we ffiali fubjoin to the Defcription of every Apparatus , 
 the feveral Manners of proceeding, and every Thing 
 moreover to be obferved *, left all thefe Things being 
 difperfed, fhould avert the Attention from the De- 
 fcription 'itfelf of the Work, or puzzle the Beginner. 
 But, it will not always be poftible to fulfill every one 
 of the Rules hitherto eftablifiied * 5 becaufe the Firft 
 and Second chiefly, will now and then bear an Ex- 
 ception, to avoid a greater Inconvenience. For this 
 Reafon, it is not always convenient to give the firft 
 Rank to the more fimple Procefies, becaufe they are 
 performed with greater Difficulty $ nor to give 
 it always to the more eafy, becaufe they require a pre- 
 vious Knowledge of fome of the foregoing to be 
 brought to their Perfection. We muft then be al- 
 lowed, to feleCt feveral Series of Procefies, and out 
 of thefe, well compofed among themfelves, to efta- 
 blifh the more convenient Order. We then thought 
 it very proper, to begin with thofe Procefies which are 
 made with Silver and its Ores : For in thefe, there 
 is no Neceffity but of a fimple Separation of the he- 
 terogeneous Bodies anc} even this is performed by 
 Additions more fimple than in the others wherein, 
 befides this Separation, an intimate Combination of 
 the Pblogifton is required, fora Reduction into a me- 
 tallick State. Next, the EfFeCt of the Menftrua , is 
 moil commonly evident to the Senfes, in Operations 
 made upon Silver, during the ACtion itfelf : Where- 
 fore, the Degree of the Fire may be meafured as 
 with the fureft Thermometer : Which does not fuc- 
 ceed fo well in the Procefies to be ufed for the other 
 Metals ; becaufe thefe, moft commonly, muft be 
 treated in clofe Veffels, on account of their Deftru- 
 Clibility. And this Deftru&ibility itfelf is the Caufe, 
 why thefe Procefies fo feldom meet with good Sue- 
 cefs ; becaufe the Greatnefs and Duration of the De- 
 gree of the Fire, are very difficult to be exaClly de- 
 termined, and the EffeCl, while it is produced, can- 
 not be feen \ but, when the Procefs is finiffied, then, 
 
 indeed , 
 
204 7 &? Art of 
 
 indeed, and no fooner, you are capable of determin- 
 ing, whether it has fucceeded well, or no. Befides, 
 as Metals, femi-Metals, and the other Minerals, all 
 them undergo a Trial, to know whether there is 
 my Silver in them ; their Difpofition in the Fire 
 and in the feveral Menftrua, appears with the 
 greateft Evidence in thefe Proceflfes ; and by it, the 
 Proceflfes to be made with them afterwards, are in- 
 deed very much facilitated. Thefe Proceflfes muft be 
 followed by thofc that are made upon Gold : For 
 thefe, in many Refpe&s, have a great Affinity with 
 the foregoing *, befides that both a greater Variety 
 of Operations, and now and then difficult manual 
 Works, are met with in thefe. The Reafon of the 
 Order in which the Proceflfes are to follow each other, 
 with the other Minerals, will appear from the Way 
 kfelf of treating them* 
 
 POCI- 
 
DOCIMASTICAL 
 
 OPER AT IONS 
 
 UPON 
 
 SILVER, and its ORES. 
 
 PROCESS I. 
 
 Precipitation of Silver (Part I. § 462, 467.) made with 
 Lead ; and by Scorif cation , out of its eafily-fufible , 
 proper ( ibid . § 385 — 388.) and improper ( ibid . §389 
 *—391) Or£. 
 
 Fhe Apparatus. 
 
 1. J'^OU N D the Ore in a very dean iron- 
 Mortar, into fine Powder. Of this weigh 
 JL one docimaftical Centner (Part* I. § 275) $ 
 and eight the like Centners of granulated Lead. 
 
 2. Then have at hand the docimaftical Teft (Part L 
 Plat. I. Fig. 7.) which mu ft not have as yet ferved 
 to any Operation : Pour into it about half of the 
 granulated Lead (N°. 1.) and fpread it with your 
 Finger, through the Cavity of it. Then put upon 
 this Lead the pounded Ore (N° 1), and then cover it 
 quite with the Remainder of your granulated Lead. 
 
 3. Put the Teft thus loaded under the MufFel of 
 the afifay- Furnace (Parti* Plat. III. Fig. I), and in 
 the hinder- Part of it : Then make your Fire, and 
 increafe it by the Degrees mentioned (ibid. § 235,) 
 If you look through the Hole of either of the Sliders 
 (ibid. Plat. III. Fig , L m. n.) you will foon fee, that 
 the pounded Ore will be raifed out of the melted 
 Lead, and fwirn upon it. A little after, it wdil 
 grow clammy, melt, *md be thrown towards the 
 
 Border 
 
to 6 The Art of 
 
 Border of the Teft : Then the Surface of the Lead 
 will appear in the Middle of the Teft, like a bright 
 Difc, and you will fee it fmoak and boil {Ibid. § 38). 
 So foon as you fee this, it will be proper to diminifh 
 the Fire a fmall Matter, for a Quarter of an Hour ; 
 fo as that the boiling of the Lead may almoft ceafe. 
 Then again, increafe the Fire to fuch a Degree, 
 that all may turn into a thin Fluid, and the Lead 
 may be feen, as before, fmoaking, and boiling with 
 great Violence : The Surface of it then will diminifh 
 by Degrees, and be covered over with a Mafs of Sco- 
 ria’s. Finally, have at Hand an iron-Hook {Parti. 
 Plat. IV. Fig. VI.) ready heated, wherewith the 
 whole Mafs muff be flirted, efpecially towards the 
 Border * that, in Cafe any fmall Parcels of the Ore 
 not yet difTolved ihould be adherent there, they may 
 be brought down, taking great Care, not to flirr any 
 the leaf! Thing out of the Teft. 
 
 4. Now, if what is adherent to the Hook during 
 the ftirring, when you raife it above the Teft, melts 
 quickly again, and the Extremity of the Hook grown 
 cold is covered with a thin, fmooth, fhining Cruft y 
 it is a Sign that the Scorification is perfect *, and it 
 will be the more fo, as the faid Cruft adherent to the 
 Hook, fhall be coloured equally on every Side. But 
 in Cafe, while the Scoria’s are ftirred, you perceive 
 any confiderable Clamminefs in them, and when 
 they adhere in good Quantity to the Hook though 
 quite red hot, and are inequally tinged, and feem 
 dufty, or rough with Grains interfperfed here and 
 there, it is a Sign that the Ore is not entirely turned 
 to Scoria’s. In this Cafe, you muft with a Hammer 
 ftrike off what is adherent to the Hook, pulverize 
 it, and, with a Ladle {ibid. Plat. IV. Fig. XI), put 
 it again into the Teft, without any Lofs or Mixture 
 of any foreign Body, and continue the Fire in the 
 fame Degree, till the Scoria has acquired its Perfe- 
 «ftion and the above-mentioned Qualities. This once 
 obtained, take the Teft with a Pair of Tongs (ibid. 
 Plat . IV. Fig . II.) out of the Fire, and pour Lead 
 
 together 
 
Assaying M ETALS, 20 7 
 
 together with the Scoria fwimming upon it, into a 
 Funnel {ibid. § 224, 225.) made hot, and rubbed 
 with Tallow. Thus will the firfl Operation of the 
 Procefs be performed, which does not commonly in- 
 deed laft above three Quarters of an Hour. 
 
 5. With a Hammer, ftrike the Scoria’s off from 
 the Regulus grown cold, and again examine whether 
 they have the Character iilicks (N°. 4.) of a perfect 
 Scorifi cation : If they have, you may thence con- 
 clude, that the Silver has been precipitated out of 
 the Ore turned to Scoria’s, and received by the 
 Lead. 
 
 When the ScoriBcation lafts longer than (N°. 4.) 
 we mentioned, the Lead at laft turns to Scoria’s, or 
 Litharge, and the Silver remains collected at the 
 Bottom of the Veffel : But the Fire muft be mode- 
 rately fupplied, and the Veffels be extremely good, 
 to produce this Effebt ; for they feldom refill to the 
 Strength of the Scoria’s of Lead long enough, fo as 
 that the whole ScoriBcation of the Lead may be 
 brought to an End : Which has afterwards this In- 
 conveniency that the Silver is diffipated by Grains ir* 
 the fmall Hollows of the corroded Ore, and can hardly 
 be well collected, again, when the Ore has but little 
 Silver in it : Nay, there is ftill more Time to be 
 confumed, to obtain the perfedl Deftrucftion of the 
 Lead, by Means of the combined Actions of the Fire 
 and Air, becaufe the Scoria’s fwimming atop retard 
 it conliderably. 
 
 The life and Reafons of the Procefs . 
 
 x. The State of the filver-Ore depends upon the 
 Prefence of Sulphur and Arfenick : Both thefe, when 
 they are not very ftrongly inherent to the Silver, and 
 when the Ore is broken fmall, and extended widely 
 in a fmall Quantity, are in Part ealily diffipated by 
 the Fire, and in Part abforbed by the Lead (Parti. 
 
 § 76, 174. Coroll . 2.) the lighter Part of which fwim- 
 ming upon the heavier, becomes very clammy by 
 
 means 
 
2o8 The Art of 
 
 means of the Sulphur which is in j|ie Ore ; but whe» 
 this is diffipated by the Violence of the Fire, it turns 
 into Glafs or Scoria’s. But when Arfenick is predo- 
 minant in the Ore ; the plumbeous Part turns im- 
 mediately into a very penetrating, and. very fufibie 
 Glafs, having a diffolving Efficacy, unlefs the Arfe- 
 nick lies hidden in a white Pyrke or Cobalt. For 
 this Reafon, the fixt Part of the Ore, which is no 
 Silver, isdififolved by that Glafs, melts, and afiumes 
 the Form of Scoria’s : The unmetallick Earths, and 
 the pure Copper or lead-Ores thereto adherent, are 
 of this Kind. The Silver then remains immutable, 
 and being freed of thefe heterogeneous Bodies, which 
 are perfedly diffipated and partly melted, it is preci- 
 pitated, and received by the remaining Regulus of 
 Lead. Therefore this Procefs is completed by three 
 diftind Operations viz. (i.) by roafting, (2.) by 
 Scorification ; (3.) by the melting Precipitation of 
 the Silver, which is the Refult of the two former 
 Operations. 
 
 2. The Ore mull be pulverized very fine, in or- 
 der to increafe the Surface *, that the Diffipation of 
 the Volatiles, and the Difiolution by Litharge may 
 be the fooner effeded. This pulverifing mu ft then 
 be done, before the Ore is weighed, becaufe there is^ 
 always fome Part of the Ore adherent to the Mortar, 
 or the iron Plate on which it is made fine ; which 
 Part being loft, the Operation is not exad. Erkcr 
 was in the right, when he prefcribed 8 Centners of 
 Lead, for the fubduing of the fufibie Ore : Neverthe- 
 lefs, it muft be owned, that this Quantity is fuperfiu- 
 ous in forne Cafes : However, as the Fluxibility of 
 filver-Ore depends from the Abfence of Stones, Py- 
 rites, &c. it iseafy to fee, that there are an infinite 
 Number of Degrees of Fluxibility, which it would 
 beneedlefsto determine exadly, and moft commonly 
 very difficult to determine by the bare Sight. Be- 
 Tides, a little more Lead does not render the Procefs 
 imperfed ; on the contrary, if you ufe too fmall a 
 Quantity of Lead* the Scorification is never com- 
 
 pletely 
 
Assaying Metals, top 
 
 pleatly made. Nay, there are a great many Ores, 
 containing Sulphur and Arfenick in plenty, that de- 
 ft roy a confiderable Quantity of Lead : Such are the 
 red fiiver-Ore, and that wherein there is a great Deal 
 of the fteel-grained lead-Ore. 
 
 3. When you intend to make a perfedf Procefs, 
 it is not proper to make one and the fame Teftferve 
 for many Proceffes, but you mu ft always chufe a new 
 one : For in all Precedes, you mu ft take Care that 
 no foreign Body may accrue to that in hand, or that 
 nothing may be loft of the Weight already deter- 
 mined : Which will eafily happen, if you ufe old, 
 unclean Veffels and Inftruments. 
 
 4. There are Tome, who wrap up their Ore in a 
 Paper, or put it into a fmall Ladle, and hold it * 
 thus upon hot boiling Lead : But we rejedl this Me- 
 thod, becaufe the Volatiles, efpecially the Arfenick, 
 being agitated by fo hidden and violent a Heat, may- 
 carry off along with them a great Deal of the Silver : 
 There are likewife many Ores, but chiefly the red 
 filver-Ore, which being expofed to a hidden, violent 
 Heat, burft afunder and difperfe or if they don’t 
 do fo, at leaft you will never be certain, whether 
 there are not Particles of Flint, Spaad, Allum, and 
 other Stones interpofed, which crackling, may eafily 
 fling fome Part of the Ore out of the Veffel along with 
 themfelves. To prevent this, it is enough to cover 
 the Ore with granulated Lead : For then the Ore 
 grows warm by degrees, and as its Particles, when 
 burft ing out, muft go through the melted Lead that 
 covers them, they are fo much involved by its Calx 
 grown clammy, that they cannot leap out. 
 
 5. If the Fire muft - fometimes be diminifhed in the 
 Middle of the Procefs, it is in order to hinder the 
 too much attenuated Litharge, which is continually 
 generated out of the Lead, from penetrating the Pores 
 of the Teft, and from corroding it : Which is eafily 
 done, when the Fire is over-ftrong : For then the 
 Surface of the Veffel, which is contiguous to the 
 Lead, contracts Cavities, or being totally confumed 
 
 P by 
 
2io The Art of 
 
 by fmall Holes, lets the Regulus flow out of it. 
 The Veffels that are mod fubje£t to this Inconveni- 
 ence, are thofe in the Materials of which. Lime, 
 Plafter, and Chalk are mixt : Nay, thefe Bodies, 
 which are of their Nature refractory, being eroded 
 during the Scorifkation, at the fame Time commu- 
 nicate a great Clamminefs to the Scoria *, fo that a 
 great Quantity of the Mafs remains adherent to the 
 Ted, in the Form of Protuberances, when you pour 
 it out ; whereby a great many Grains of the Regulus 
 are detained. 
 
 6. There are a great many Affayers, who take 
 for a Sign of the Compleatnefs of the Scorification, 
 the Quantity of the Scoria ; that is, when thefe have 
 covered the whole Surface of the Lead. But this is 
 very uncertain : For, if the Ted is a fmall Matter 
 narrower, and of Courfe as much deeper, or if you 
 fcorify filver-Ores that are lefs rich ; then indeed 
 the Regulus of the Lead will be covered over with 
 the imperfect Scoria, long before the Scorification is 
 perfect. The Quality of the Scoria is a much furer 
 Sign *, and this mud appear quite vitrified, according 
 to the Defcription of it given (N°. 4. of the Appar.) 
 In the mean Time, the Colour and Brightnefs of it 
 differs according to the Variety of the Ore ; how- 
 ever, it is mod commonly brown, or black, and opa- 
 que, which is owing to the Iron and Copper, from 
 which the Ore is feldom altogether free : For thefe 
 Metals tinge Glaffes with very deep Colours. The 
 Colour of the Scoria is feldom half tranfparent, red- 
 difh, or yellow, like Rofin. But when thefe Cha- 
 radteridicks are wanting, you may be fure, that all 
 the Silver is not yet precipitated out of the Ore, as 
 it ought to be : Therefore the Fire mud be in- 
 
 creafed. 
 
 PRO- 
 
Assaying Metals. 21 t 
 PROCESS II. 
 
 ‘The Separation of Silver out of the Regulus , Proc. I. by 
 copelling (Part I. § 454.) 
 
 T H E Separation of Silver out of Lead, when it 
 has been precipitated, and received by the 
 Lead, may indeed be intirely made by the Apparatus 
 of the foregoing Procefs as well as (Proc. I. Appar. 
 N°. 5). But this Method is tirefome, on account of 
 the Inconveniencies mentioned in the fame Place : 
 Therefore, the Thing is better done by coppelbng* 
 But for this Reafon a Scorification muff precede •, that 
 thofe Bodies, which greatly refill a fufficient Attenu- 
 ation to be effected by the Scoria of Lead, may be 
 previoufly feparated, and that the Addition of fa 
 great a Quantity of Lead may not be neceffary. 
 
 APPARATUS. 
 
 1. Put into the docimaftical Furnace under the 
 Muffel, two Coppels of the fame Bignefs (Part L 
 Plat . I. Fig . III.) perfectly dry, and of fuch Capa- 
 city, that they may contain a Regulus, at lead one 
 third Part larger than that which is to be put into 
 them : Make a ffrong Fire, that they may be red 
 hot for a Quarter of an Hour, or more, and the 
 aqueous Vapours vanifh intirely. Then free your 
 Regulus quite from Scoria’s, by feveral gentle Blows 
 of a Hammer, wrap it up in a clean Paper, and put 
 it into the Fire gently with a Pair of Tongs , taking 
 great Care, that the hollow Surface of the Coppel be 
 not hurt: For which Reafon, you mull alio take 
 Care, that this be not angular or rough. Now* 
 with a Ladle, put into the other Coppel as many 
 Centners of the fame granulated Lead,, v/hich you 
 have ufed (Proc. foregoing) for the Scorification of 
 the Ore. All the Phenomena will appear the fame 
 as we have defcrihed ( Part I. § 38), and the Scoria’s 
 
 P % which 
 
tit The Art of 
 
 which are perpetually produced by the Lead, being 
 caft upon the Border, will be immediately abforbed 
 by the Coppel, which, on this Account, will be 
 tinged with a yellow, brown, black Colour, in pro- 
 portion as the Scoria fhall have penetrated into it. 
 
 2. But fo foon as you fee the Regulus boil with 
 Violence and Smoke, diminifh the Fire a little *, that 
 the Regulus may for the greateft Part be confumed 
 by a middling Heat. You will know that the De- 
 gree of the Fire is very great, if the Smoke proceed- 
 ing from the Lead, is driven up almoft to the very 
 Ciefing of the Muffel, and if the Regulus in the Cop- 
 pel is gibbous at Top : In which, however, the 
 Quantity of the Metal is to be confidered : For a 
 large Mafs of Regulus makes the fpherical Segment 
 low, and a Idler one makes it more acute, when the 
 fame Degree of Fire has been ufed for each of them. 
 Then, if the Coppels are fo bright with the Fire, 
 as that it be hardly poftible to diftinguifh how far the 
 Scoria has entered, it is a Sign of a Fill greater De- 
 gree of the Fire. But you will know that the Degree 
 of the Fire is middling, if the Surface of the melted 
 Metal is plain, if the Smoke does not rife very 
 high, and if the Coppel is coloured by the Scoria’s, 
 which Signs indicate that the Fire wants a Degree of 
 Force. But if the Smoke wanders to and fro on the 
 Surface of the Metal ; if this is almoft flat, and the 
 Ebullition of the Scoria’s, which are like Drops of 
 Fire, is but weak, and their Motion languid, if in 
 ihort the Coppels appear dark, it is a Sign that the 
 Fire has not its fuflicient Degree of Strength. 
 
 3. If you fee the Regulus confiderably diminifhed, 
 the Fire mu ft ftill be increafed : The Lead being 
 thus confiderably diminifhed, the bright Sparkles 
 will difappear, and inftead of them, you will fee 
 Iris’s, as it were, much livelier than in the Beginning 
 and the Middle of the Operation, quickly moving 
 on the Surface of the Regulus , and crofting each 
 other many different Ways. When at laft all the 
 Lead is confumed, the tender Skin of the thinScoria 
 
 or 
 
Assay in g Metals. 113 
 
 or Utharge, which being perpetually reproduced by 
 the Regulus , had covered the Surface of it, is as it 
 were pulled off. If the Fire at that Time is not 
 ftrong enough to keep the Silver in a State of Fufion ; 
 the Colour of the Regulus of Silver remaining, 
 changes fuddenly from a faint fire Colour, to a Aim- 
 ing one : Which Rrightnefs is called in German 
 215itcfe£iT* Blit if you have ufed in the End fo great 
 a Fire, as that the pure Silver may be kept in Fufion, 
 this Alteration of Colour does not appear, but the 
 granulated Metal continues to fhine bright. Silver, 
 in the Moment it grows folid, commonly emits out 
 of itfelf Ramifications like a Vegetation, and which 
 are fome times very delicate and elegant. 
 
 4. When the Phenomena above-mentioned (N°. 3.) 
 have been feen, leave the Coppel ftill one or two 
 Minutes under the Muffel 3 then take it out, and 
 with a Pair of Tongs ( Part J. Plat. IV. Fig. III.) 
 take away the Metal in Grains : And if any Scoria 
 or any Bit of the Coppel fiiould happen to adhere 
 to it, wrap it up in a Paper, and prefs it between 
 a ftrong Pair of Tongs, or between the Chops of a 
 Vice: That the brittle Drofs may go off without 
 Lofs of the Regulus ; which fiiall be very white, 
 and full of frnall Pits underneath : But if it is tinged 
 with a neat yellow Colour ; you may be fure that 
 it contains a great Deal of Gold. 
 
 5. If you want next to determine how much Silver 
 you have fetched out of the Ore, put in one Scale 
 the filver-Regulus, which has remained of the Re- 
 gulus in the Scorification •, and put in the oppofite 
 Scale, together with the Weights, the Regulus which 
 remained in the other Coppel, out of the fame 
 Quantity of granulated Lead, as you have ufed for 
 the Scorification : For the Lead by which the Scori- 
 fication has been made, contained as much Silver *, 
 and this has joined itfelf by the Force of the Opera- 
 tions, to the Regulus obtained out of the Ore, 
 
214 
 
 The Art of 
 
 ¥he JJfe and Reafons of the Procefs. 
 
 1. When you are chufing a Coppel, you mull 
 have Regard to the Capacity of it *, for Inftance, 
 whether it anfwers the Quantity of Metal to be put 
 into it, or no. Too large a Size is no way detri- 
 mental, but only ufelefs. Whereas, if it is too Small, 
 the Operation does not fucceed well. For if the 
 Coppel is loaded with too much Lead, the Infide of 
 it is at laft corroded and fplit, by the Litharge into 
 •which the Lead is diffolved, and which finally con- 
 fumes every Thing : Nay, if the Afhes of the Cop- 
 pel are already Saturated, a greater Quantity of the 
 Litharge cannot get into it fo quickly, and that Part 
 of it, which is then abforbed, runs through upon the 
 Bottom of the MufFel : Which has this Inconvenience, 
 that when the faid Bottom being corroded grows in- 
 equal, the Yeffels put into it do not afterwards Hand 
 fteddy, and are conglutinated to it, if the Heat is 
 considerably increafed. 
 
 2. The Coppels, though extreamly old, and to 
 Appearance very dry, like many other Bodies, being 
 neverthelefs expofed to a Strong Fire, exhale a moift 
 Vapour, as we learn from chemical Diftillations ; 
 But above all, the Afhes of Wood do not eafily part 
 with the Moifture they have once contracted, becaufe 
 of the Salt from which they can hardly be intirely 
 freed. Therefore, thofe Coppels chiefly which are in 
 part compofed of Wood^afhes, muft previoufly be 
 made thoroughly red-hot under the MufFel, without 
 any Lead put into them, that all the Moifture may 
 be diffipated. This roafting is called in German 
 $ija£fjnetl. But if this is not done Sufficiently, the 
 Lead put too Soon into the Fire, flings to the very 
 Cieling of the MufFel, an innumerable Quantity of 
 Small Drops like Sparkles, with a gentle crackling 
 Noife. And as this Lead has in it a proportionable 
 Quantity of Silver, it renders the Procefs uncertain. 
 This emiffion of Sparkles, when perceived foon 
 
 enough 
 
Assaying Metals. 2 iy 
 
 enough by the Artificer, may indeed be at any Time 
 prevented, by a large Coal that clofes the whole Ca- 
 vity of the Coppel, when put upon it like a Tile : 
 But, as this Defed is obferved before it can be reme- 
 died, on this very Account, an exadt Allayer can 
 never trull to fuch a Procefs. Belides, the Opera- 
 tion is alfo retarded by this Remedy : For fcorified 
 Lead, is often reduced by the Phlogifton of the Coal ; 
 wherefore this mull be removed fo foon as the Lead 
 begins to reft. It alfo fometimes happens, when you 
 neglect to heat the Coppel fufficiently, that the 
 Lead continually quivers in the Coppel *, fo that it 
 never fettles ; and thus changing its Place, it nowand 
 then is in Part thrown out of the Coppel. This 
 Fault may be better prevented, by putting a larger 
 Coal upon the Coppel, than the foregoing : Which 
 proceeds from the Eruption of dry, fat Vapours. 
 
 3. Let the Fire be fomewhat gentler, in the Mid- 
 dle of the Operation of coppelling ; left fomething of 
 the Silver inould be carried away, by the too atte- 
 nuated Litharge, and by the Smoke itfelf of the 
 Lead : For in every dry, as well as moift and too 
 turbulent Diffipation of the Volatiles, a Part of a 
 Body howfoever hxt, may at the fame Time be hur- 
 ried away. That degree of Fire is here fufficient, 
 by which Lead is changed into Litharge, and atte- 
 nuated fo far as to be able to penetrate the Coppel. 
 But when in the End of the Operation, the Lead is 
 almoft all confumed, the Fire then mu ft be made 
 very ftrong - 3 left fomething of the Lead fhould re- 
 main with the fmall filver-Mafs : Whereby the 
 Weight becomes uncertain, and the Silver is rendered 
 brittle. For Lead is deftroyed into a fufficiently 
 attenuated Litharge, by a much lefter Fire than is 
 neceffary to melt pure Silver : And Lead adls here 
 as a Menjiruum , by which you obtain the melting of 
 Silver in a weaker Fire : For this Reafon, the more 
 the Lead is confumed, the ftronger the Fire mult be 
 made, that the Quantity of Lead requifite to retain 
 the Regulus in a.State of Fufion, being gnce defici- 
 
 P 4 ent. 
 
ii6 The Art of 
 
 ent, it may be compenfated by the Violence of the 
 Fire : Which being negleded, the Regulus of the 
 remaining Silver hardening too foon, a Part of the 
 Lead preferved from its Deftrudion by the Silver, 
 remains joined to it. Such a refiduous Part cf Lead 
 adhering to the Silver, is called in German 215 iejp 
 
 facfe. 
 
 4. The Operation of coppelling being done, the 
 Grain or Bead of Silver muft be taken out of the 
 Fire with all Speed ; left growing cold, it fhould be 
 conglu tinated to the Coppel by the Litharge : For 
 ©therwife, it can hardly be taken off, without Part 
 of the Coppel adhering to it. The Coppel may alfo 
 be left a While with its Bead under the Muffel, and 
 this is better ; that all the Litharge may retire into 
 the Coppel : For then it is very eafily taken out. 
 As for the reft, you may fee Part I. § 181. CorolL 
 The Operation of Coppelling being duly perfeded, 
 the Bead of Silver will be full of fmall Cavities un- 
 derneath. 
 
 5. By thefe two Proceffes (I. and II.) is corn- 
 pleated the dociroaftick Examination of afufible Ore, 
 whereby it appears how much Silver may be- fetched 
 out of it with Benefit, by a metallurgical Operation : 
 For both being joined, anfwer exadly to the great 
 Operations of Metallurgy. There are fome of thefe 
 Operations, which thole that are well verfed in the 
 Matter, can perform together, at once, and under 
 the fame Muffel provided one Veftel is no Impedi- 
 ment to the other. At leaft the Coppel may be con- 
 veniently heated, atone and the fame Time, and in 
 the fame Fire, while the Scorification is performed in 
 the Teft. 
 
 6. There is no Lead fold, but contains fome 
 Silver : For k is not always worth the Charges of fe- 
 parading it. Such a little Mafs of Silver moft com- 
 monly is one or two Drachms in every Centner of 
 Lead. Therefore, it occafions a very great Error, 
 when it is left in the Coppel, and joins to the Regu- 
 lus feparated from the Ore after the Lead is confumed : 
 
 For 
 
Assaying Metals. 217 
 
 For which Reafon, this increafing of Silver is always 
 fubftra&ed by all accurate AfFayers. Therefore, a 
 confiderable Quantity of Lead is granulated at once 
 for this Purpofe, and well mixt by lifting: Then 
 this granulated Metal alone, muft be tried in a Cop- 
 pel, in the fame Quantity ufed to make the Trial of 
 Ores •, that you may have feparately the Bead of Sil- 
 ver it contains. For this, while the Regulus of Sil- 
 ver, feparated from the Ore by the fame Kind of 
 Lead, is weighing, is put into the other Scale which 
 contains the Weight , to take away the Overplus of 
 Weight, that was added to this Regulus , by the 
 fame Quantity of the Lead imployed for the Scorifi- 
 cation and Coppelling. But whenever a Granula- 
 tion of new Lead is made, the determined Quantities 
 of it commonly imployed for the trying of Ores, 
 muft be as many Times tried in the Coppel ; even 
 though you knew, that the Lead had alfo been digged 
 out of the fame Mine as the firft, and melted out of 
 its Ore in the fame Manner. For while Lead is 
 roaffed. Silver is not very equally diftributed through 
 it: Which proceeds from many Caufes, of which 
 hereafter. 
 
 7. However, we muft alfo obferve in general, 
 that all the additional Ingredients, which we ufe in 
 fuch Operations, muft be tried, to know whether 
 they let any Silver fall into the Regulus of Lead, and 
 how much. For the Litharge itfelf is fometimes 
 loaded with Silver. Therefore, it is proper to try 
 it itfelf in the Coppel, or the Glafs of Lead made 
 out of it, before they are imployed. Copper, Iron, 
 and other Metals, are feldom altogether deftitute of 
 Silver : And though they contain fo little of it, that 
 the Error proceeding therefrom is hardly fenfible ; 
 neverthelefs, you mull beware of the minuted: Mi- 
 flakes : For a great Number of them, though ever 
 fo infignifkant, conftitute, when colle&ed together, 
 an Error, which is not inconfiderable. 
 
 PROCESS 
 
2 I 8 
 
 The Art of 
 
 PROCESS III. 
 
 To precipitate with Lead by Scorification , Silver out of 
 an Ore that cannot be wafhed clean , and which is 
 rendered refractory , by a Mixture of unmetallick 
 Earths (Parti. § 334 > 3 . 3 6 > 33 8 -) 
 
 T H E 'Variety of thofe Things which render 
 Ores refractory, require a different Manner of 
 treating them. But there are fome Ores rendered 
 refraCtory, by a Mixture of an unmetallick Earth, 
 fome of which are, and fome are not feparable by 
 walking. If they are not feparable, you mull pro- 
 ceed in the following Manner. 
 
 APPARATUS. 
 
 1. Bruife the Ore into an impalpable Powder by 
 grinding in a Mortar, to a docimaltical Centner of 
 it, a like Quantity of Glafs of Lead ( Part I. § 54.) 
 finely pulverized : For the more exaCtly both thefe 
 are mixt together, the more eafily the Scorification 
 afterwards fucceeds. Put this Mixture, together 
 with twelve Centners of Lead, into the Teff, accord- 
 ing to the firfh Procefs (N°. 2.) then put the Tell 
 under the Muffel. 
 
 2. Make fir ft under it a ftrong Fire, till the Lead 
 boils very well : When you fee it fo, diminifh the 
 Violence of the Heat, according to the firfh Procefs 
 (N°. 3.) but keep it thus diminifhed a little longer. 
 Then, finally, increafe the Fire again to fuch De- 
 gree, till you perceive the Signs of a Scorification 
 and perfect Fufion. See the whole Procefs I. Now, 
 this Procefs lalts a little longer than the foregoing, 
 and requires a greater Fire towards the End. 
 
 3. It fometimes happens, that a very refraCtory 
 Ore cannot be fufficiently diffolved by litharge i 
 and that a Mafs which has the Clamminefs of Pitch, 
 fwims upon the Regulus, and upon the Scoria’s 
 
 them- 
 
Assaying Metals. 219 
 
 themfelves which are already fubdued in part : When 
 you fee this, fhut theVents of the Furnace, to diminifh 
 the Fire : Then gently touch this refra&ory Body, 
 with a fmall iron cold Hook, to which it will imme- 
 diately flick *, take it off foftly, not to loie any Thing ; 
 pound it into a fine Powder, adding a N little of Glafs 
 of Lead *, and put it again into the Tefl, then con- 
 tinue the Scorification, till it is brought to its Perfe- 
 ction. But you mufl always examine the Scoria of 
 your refradtory Ore •, to fee whether there may not 
 be fome Grains of the Regulus difperfed in it : For 
 fometimes the Scoria’s that grow clammy, retain 
 fomething of the Metal : Which if you fufpedt, 
 
 pound the Scoria into a fine Duff, and thus the 
 Grains of Metal will appear, if there are any left , 
 becaufe they can never be pounded fine. 
 
 4. Silver is feparated out of the Regulus by copel- 
 ling (N°. 3), according to Procefs II. But while 
 you are weighing the Regulus of Silver obtained, 
 you muft put into the oppofite Scale, the fmall Mafs 
 of Silver, which has remained in the Coppel, out of 
 the twelve Centners of the Lead employed. (See 
 Procefs II.) 
 
 The Ufe and Reafons of the Procefs . 
 
 1. All Earths and Stones are refradtory in the Fire : 
 For though fome of them melt naturally in the Fire, 
 as thofe that are vitrificable do ; neverthelefs, all 
 the others, a very few excepted, melt much more 
 difficultly than Metals, and never become fo thin in 
 the Fufion, as is required for the fufficient Precipi- 
 tation of a precious Metal. But Litharge itfelf does 
 not conveniently diffolve thefe refradtory Matters by 
 the Help of Fire alone, unlefs you add fome mecha- 
 nical Mixture to them : For the very Moment the 
 faid Litharge penetrates through the Interflices of the 
 refradtory Ore, and begins to diffolve it, a tenacious 
 Mafs is produced, which hardly admits any further 
 Dilution by the Litharge. You may fee it plain, if 
 you make coloured Glaffes with metallick Calxs : If 
 
 you 
 
220 The Art rf 
 
 you pour carlefly upon them a Calx that gives a Co- 
 lour, you will never obtain that they may be equally 
 died on every Side * even though you fhould torture 
 them for whole Days together in a great Fire. Nay, 
 Glafs already made, can never be perfectly diluted, 
 by only pouring Salts and Litharge upon it : Where- 
 fore, you muft ufe the Artifice of glafs-Makers, 
 who, in the making of the moft perfecft Glades, 
 take great Care, before they put the Species of their 
 Ingredients into the Fire, to have a mechanical Mix- 
 ture proceed, or at lead accede during the Fufion it- 
 felf : Which is done here by pounded Glafs of Lead 
 mixt with the Ore. But if you think that your 
 Glafs of Lead is not fufficiently fufible, you may add 
 to it Litharge melted firfl, and then pounded into a 
 fine Powder. 
 
 2. As this Scorification requires a longer and 
 greater Fire than the foregoing, and as a greater 
 Quantity of Litharge is moreover requifite, to fub- 
 due the refractory Scoria *, it is eafy to fee, why a 
 much greater Quantity of Lead muft be ufed here, 
 than in Procefs I : And though lefs Lead is often 
 fufficient ; it is neverthelefs proper, always to ufe 
 the greateft Quantity that can be neceflary *, left, 
 for Inftance, it fhould be neceffary to try fo many 
 Times the Lead alone ; to make it evident, how 
 much Silver, the Lead, when alone, leaves (Proc. II. 
 N°. 5.) in the Coppel. Nor need you fear, left any 
 Thing of the Silver may be taken away by the Lead ; 
 provided the Coppels be good, and the Ccppelling 
 duly put in Execution j for you can hardly coiled: a 
 ponderable Quantity of Silver, out of the collected 
 Fume of the Lead, which rifes during the Coppel- 
 ling, as well as out of the Litharge that is withdrawn 
 into the Coppel. 
 
 3. If it happens that the Scoria grows clammy, 
 and adheres to the Sides of the Vefiel to fuch a De- 
 gree, as that it can hardly be poured out, and thus 
 retains fomething of the Regulus : Some, in this 
 Cafe, are ufed to add coal-Duft, or the Caput Mor- 
 
 tuum 
 
Assaying Metals. hi 
 
 tuum of Aqua Fortis , or of Vitriol j and to pour it 
 out foon after : But this is neceffary upon no Account, 
 when an exa<ft Mixture of Glafs of Lead is made with 
 the Ore, after the Manner juft mentioned, and a 
 proper Regimen of the Fire obferved. 
 
 P R O C E S S IV. 
 
 Precipitation with Lead by Scarification, of Silver out of 
 an Ore , rendered refir adlory by Pyrites (Part L 
 § 3i 6 >3 2 3>342,3 6 9') 
 
 APPARATUS. 
 
 i. T> Reak your Ore into a rough Powder, and 
 JJ put a Centner of it into the Teft : Put upon 
 this another Teft, in the Manner of a Tile. Put it 
 under the Muffel hardly red hot : Increafe the Fire 
 by Degrees : There will always be a crackling : 
 
 Which being ended, take away the upper-Teft ^ 
 for when theVeftels have been red-hot about one Mi- 
 nute, the Ore ceafes to fplit : Leave the Ore under 
 the Muffel, till the Arfenick and Sulphur are for the 
 moft Part evaporated : Which you will know from 
 the Ceffation of the vilible Smoak, of the Smell of 
 Garlick, or the Acid. Then, take away the Teft, 
 and leave it in a Place not too cold, that it may cool 
 pf itfelf. 
 
 2. Pour out, without any Diftipation, the roafted 
 Ore, and with a Knife take away what is adherent to 
 the Veffel : Pound it to a moft fubtil Powder, and 
 grind it together with an equal Weight of Glafs of 
 Lead ; and finally, fcorify the whole collected Ore, in 
 thefameTeft wherein the reading was made, unlefs it 
 has contra&ed Chinks j as was deferibed in (Proc, III.) 
 
 Fhe Ufie and Reafions of the Procefis . 
 
 i. Yellow pyrites-Ores, contain a very great Quan- 
 tity of Sulphur, even greater than is neceffary, to 
 
 fa tu rate 
 
2iz The Art of 
 
 faturate the Metal that lies hidden in them. For 
 which Rcafon, this fuperfluous Sulphur diflipates in 
 a middling Fire : But if it had been mixt with Lead, 
 it would have rendered it refractory ; nor could it 
 afterwards be diflipated from it ( Part I. § 142.) 
 without a confiderable DeftruCtion of the Lead. The 
 white arfenical Pyrites, turn alfo a great Quantity 
 of Lead into Glafs, on account of the Abundance of 
 the Arfenick they contain. For which Reafon, thefe 
 Ores muft be previoufly roafted, that the Sulphur 
 and Arfenick may be diflipated : Nor need you fear, 
 left any Part of the Silver be carried away by the 
 Arfenick : For when Arfenick is feparated from any 
 fixt Body, by a certain Degree of Fire *, 'it carries 
 nothing of that Body away with it {Part I. § 74, 
 
 3 2 9 -) 
 
 2. Every Pyrites has Iron for its Bafis : But this is 
 not only refraCbory of its own Nature, but has much 
 ado to melt into a thin Scoria, even with the Glafs 
 of Lead. 
 
 3. Near a-Kind to thefe is an unmetallick Earth, 
 annexed in great Plenty ( Part I. § 316, 323.) to 
 every Pyrites. Therefore, after the Sulphur and Ar- 
 fenick are diflipated, the only Thing remaining to 
 be done, is, to ufe the Methods we have defcribed 
 in the third Procefs. 
 
 PROCESS Y. 
 
 Precipitation of Silver out of Iron, by Scorifi cation. 
 
 APPARATUS. 
 
 • P 
 
 UT one Centner of Iron reduced to Filings, 
 or to thin Lamina’s, into a glafs Cucurbite 
 cut off in the Middle, the Belly of which muft be 
 luted over *, then pour upon it as much Oil of Vitriol, 
 diluted in about eight Times the fame Quantity of 
 Water, as is required for the Diffolution of Iron : 
 Put the Cucurbite again upon the Afhes or a warm 
 
 Bed 
 
Assaying Metals. 223 
 
 Bed of Sand ; that the Diffolution may be made by 
 a gentle Heat : This being perfed, put burning 
 Coals under it, that the boiling Diffolution may 
 thicken by Degrees ; till the remaining Mafs be in- 
 tirely dry, of an afii-Colour, and hard : When you 
 fee it fo, then urge the Fire, till the Veflel grows 
 red-hot : Thus will the Oil of Vitriol be for the 
 greateft Part diffipated : But there will remain at 
 the Bottom a pulverulent, dark red Caput Mortuum 9 
 which mu ft be taken out of the Veflel, without lofing 
 any Thing of it. # 
 
 2. Divide this into two equal Parts, and grind 
 each of them feverally with a Centner of Glafs of 
 Lead : Put any one of thefe Mixtures, together with 
 eight Centners of granulated Lead, into a Teft, and 
 compleat the Scarification, in the Manner defcribed 
 in the third Procefs. 
 
 3. Burn off the remaining Regulus 9 s feparately in 
 two Coppels, according to the fecond Procefs, and 
 weigh the remaining Beads of Silver : They will be 
 both of equal Weight. Then fubftrad the Silver 
 proceeding from the Lead added : And thus you 
 will know, how much Silver may be fetched out of a 
 Centner of Iron. 
 
 Another Method . 
 
 1. Put one Centner of comminuted Iron, and two 
 Centners of crude Antimony, into a fmall Crucible, 
 and clofe it with a Tile, and then put it into a ftrong 
 Fire, that it may melt : When it has been in a per- 
 fed: State of Fufion for five or eight Minutes, take 
 it out, that it may cool. 
 
 2. Break the Crucible when grown cold : You 
 will find Scoria’s at Top, and a Regulus underneath : 
 Throw the firft away, and pound the Regulus to a 
 fine Powder, and fcorify it with twelve Centners of 
 Lead, upon a continual, though not over-ftrong 
 Fire j till you fee the Lead quite covered with Sco- 
 ria’s : Then pour it out into a Funnel ; nor are you 
 
 to 
 
224 7 &? Ar t of 
 
 to take fo much Notice of the Scoria’s* as of the Re- 
 gains ; which muft be tough, and of a light lead- 
 Colour within and without. If it proves blackifli 
 and brittle, it then is not fit yet to be put into the 
 the Coppel, but it mull be put into the Teft a fecond 
 Time, and the Scorification be repeated : Thus will 
 all the Antimony be at laft confumed. 
 
 3. Let the CoppelJing be performed, as in the fe- 
 cond Procefs. 
 
 tfhe Ufe and Reafons of th$ Procefs . 
 
 1. Iron, in its metallick State, yields neither to 
 Lead nor to Glafs of Lead. But when it is deftroyed 
 by the Privation of its Phlogiflon, and difpofed for 
 a Vitrification, it is eafily difiolved by the Scoria or 
 the Glafs of Lead ; and melts together with it into a 
 thinly fluid black Glafs. He therefore that attempts 
 a Scorification, mud previoufly pound this Glafs very 
 fine, becaufe this promotes very much the Diftipa- 
 tion of the Phlogiflon ; which is eafily obtained by 
 acid Spirits difiblving Iron •, but moft perfectly by 
 Oil of Vitriol : For this deprives Iron of Part of its 
 Phlogiflon, during the Solution itfelf : As we may 
 fee from the inflammable Spirit that rufhes out, and 
 is produced in the actual Solution not only of Iron, 
 but alfo of Copper and Zink. The fame Comminu- 
 tion and Deftrudion of Iron, is alfo performed with 
 Sulphur, if this is mixt with Filings of Iron, and 
 melted firft in a clofe Teft by a gentle Heat, and 
 finally burnt intirely in a ftronger Fire: But the Dif- 
 folution is never made fo perfed thus, as by the firft 
 Methods : For the Sulphur is much fooner burnt, be- 
 fore it can fufticiently penetrate the Iron. Sulphur 
 poured upon red-hot Filings, diflolves them indeed *, 
 but then it can hardly be taken out of the Vefifels ; 
 on which Account it is not rendered fo proper for a 
 Scorification, as by the firft Method, unlefs it be 
 beaten fmall and roafted a fecond Time : The very 
 fame Operation is much better performed with a yel- 
 
Assaying Metals, iij 
 
 low, fulphureous Pyrites,which hath been thoroughly 
 proved to be deftitute of Silver ; if it is ground to- 
 gether with an equal Weight of Filings of Iron ; and 
 expofed to the Fire, in the fame Manner as was faid 
 about Sulphur, The Sulphur, however fixt in the 
 Pyrites, requires a great Fire to be expelled ; and by 
 Means of that Heat penetrates and diffolves the Body 
 of the Iron at the fame Time, till at laft the Fire be- 
 ing made (till greater, it is intirely dillipated. But 
 this Method has the Inconveniency, that the Mafs of 
 the deftroyed Iron is greatly increafed, and rendered 
 more refractory by the unmetallick Earth of the Py- 
 rites : Wherefore theprefcribed Quantity of Lead, is 
 not fufficient in this Cafe $ and twelve Centners mult 
 be added to each Part. 
 
 2. Crude Antimony is the mod potent Menftruum 
 of Iron, partly on Account of its reguline Subftance, 
 and partly becaufe of the mineral Sulphur that con- 
 11 1 rates about one quarter Part of it. Therefore, a 
 double Quantity of it, mixt with Filings of Iron, 
 diffolves them foon, in a middling melting Fire *, but 
 then at the fame Time the Iron abforbs the Sulphur 
 of the Antimony {Parti. § 147. Coroll. 3), and to- 
 gether hinders the Sulphur from getting into the Sil- 
 ver ; becaufe Iron is a greater Friend to Sulphur 
 (Ibid. Coroll 1) : Therefore, Silver with one Part 
 of Regains of Antimony (which both diffolve each, 
 other alike) finks to the Bottom ; and it is, as it 
 were, wa (lied clean of the Iron {Parti. §467.) by 
 the faid reguline Part. But, that this Precipitation 
 may fucceed perfedly, a pretty ilrong Fire is re- 
 quired, and muff be continued for fome Time *, and it 
 would not be amifs, if a little of the Iron fhould fe- 
 parate and turn into a Regulus. Nor muff the Regu- 
 lus be poured out into an iron-Cone, but muff be left 
 in the Crucible, and be taken out of it, by breaking 
 it when grown cold : For fo fmall a Quantity of 
 Scoria, being too foon cooled, would eafiiy retain 
 fomething of the reguline Part together with the Sil- 
 ver. Therefore, this Regulus mult be previouOy 
 
 Q fcorified 
 
n6 The Art of 
 
 fcorified with Lead : Becaufe the Coppel cannot bear 
 any Regulus of Antimony : For when this is joined 
 with Lead, it fplits the Coppels, and often corrodes 
 them to fuch a Degree, that the whole Infide of them 
 fwells like a Spunge. Therefore, after the Scorifi- 
 cation, you mud have Regard to the Regulus alone, 
 to know whether its Brittlenefs and black Colour, 
 communicated to it by the Regulus of Antimony, 
 will require the Repetition of the Operation. But, 
 you are previoufly to examine, whether the Anti- 
 mony contains Silver in it : Which may be done in- 
 tirely by the fame Method already defcribed relating 
 to Silver. For the Regulus and Silver is precipi- 
 tated out of crude Antimony by Iron, Copper, Lead, 
 and Tin. But, before this Examination is made, 
 all thefe Metals mud be tried likewife, to know whe- 
 ther any Silver remains of them after the Scoridcation 
 and the Copelling, and what Quantity. 
 
 3 . As Iron is of fuch Difpofition in its Ore, that 
 it turns into Glafs, by means of Fire alone, on ac- 
 count of its Want of a pure Phlogidon ; it is plain 
 enough, why iron-Ore is fit to be fcorified. with Lead, 
 without any previous Diflipation -of its Phlogidon : 
 Although it be the only Ore refractory to fuch a De- 
 gree, as not to be brought without great Difficulty to 
 a diffident Degree of Fufion, unlefs it be joined to a 
 great Quantity of mineral Sulphur, or Arfenick. 
 
 PROCESS VI. 
 
 Separation of Silver from Copper , by copelling , 
 
 * 
 
 i . tj Educe the Copper into Filings, or thin Plate's, 
 1\ which you mud cut into final! Bits with a 
 Pair of Sheers : Weigh one Centner, or one Mark 
 of either *, and the Double and Sextuple, with Re- 
 gard to the Copper, of granulated Lead : Put the 
 latter with a Ladle into a large well baked Coppel ; 
 make a great Fire, and continue it fo, till the Lead 
 begins to fmoak well and boil : Then add the Cop- 
 S per 
 
Assaying Metals. i%j 
 
 per wrapt up in a fmall Paper, fo that it may be i ra- 
 re er fed into the lyliddie of the boiling Lead : This 
 preferves the Copper which adheres to the Border, 
 from being difficultly, or even not diffolved at alh 
 
 2. When all the Copper is diffolved, fupprefs the 
 Fire* till you fee on the Surface a Smoak wandering 
 here and there like melted Metal, and the metallick 
 Mafs not very high nor bright, but low, moderately 
 white* and the Coppel brown, as far as it has been 
 penetrated by the Litharge. However, take Care 
 that the Ebullition of the Lead does not ceafe intire- 
 ly : For it is a very good Indication of the Degree 
 of the Fire. If you employ too great a Fire* you 
 will certainly lofe fome of your Silver \ efpecially, 
 if you are not provided with the belt Coppels. 
 
 3* When you fee the greateft Part of the Metal 
 already confumed, increafe the Fire gradually, and 
 make it pretty flrong towards the End, that it may 
 burn quite bright and clean Then take out the 
 Coppel *, and if the Operation has been rightly made, 
 you will find the Bead of Silver, if there was any in the 
 Copper, quite bright, and furrounded with bright 
 Scoria’s of a yellow Colour, in Form of Cryftals. 
 The Coppel is always tinged with a dark Coloun 
 But if you perceive the Grains of Silver, either quite 
 dark, or only the Surface of it tarniffied with dark- 
 coloured Scales •, it is a Sign, that there is ftill a great 
 Deal of Copper mixt with it : Which mull be attri- 
 buted to the Defed of the Fire or of the Lead, or to 
 the too late Immerfion of the Copper into the boiling 
 Lead : For then a confiderable Part of the Lead be- 
 ing confumed, the remaining Part has not the Power 
 of confuming the Copper fufficiently. But if all the 
 Scoria is intirely vaniffied, you have ufed too great a 
 Fire in the Middle and towards the End of the Cop- 
 pel ling : In which Cafe, you muft, for the greater 
 Security, repeat the Procefs, 
 
228 
 
 The Art of 
 
 The Ufe and Reafons of the Procefs. 
 
 1. Among all Metals, and all the Minerals which 
 are feparated from Gold and Silver by Lead, Copper 
 is the only one that remains joined to the refidous 
 Regulus of Lead after the Scorification, and is fit to 
 undergo theCoppelling : For the others either are not 
 at all received by Lead, or if they are, it reje&s and 
 deftroys them before the Scorification ; or, if they 
 remain united with the Lead, they fplit and corrode 
 the Coppels. The Coppels are alfo eafiiy fplit, ef- 
 pecially the larger Ones, when you put Lead into them 
 before they are quite red-hot. 
 
 2. The Scoria which is produced during this Pro- 
 cefs is indeed that common Litharge, which is fold : 
 It is a Texture of fmall fcaly Lamina’s looking like 
 Glimmer, and if you break it, it refills like other Li- 
 tharge, by a certain Toughnels. 
 
 3. There is no Metal but Copper alone, that melts 
 together with Lead into one Mafs, and dies the Cop- 
 pels with a blackifli Colour. Therefore, when you 
 fee this, you may fafely conclude, that there is Cop- 
 per in the Lead. 
 
 PROCESS VII. 
 
 Precipitation of Silver out of Tin , hy Scorification. 
 
 APPARATUS . 
 
 1. TV vide one f in gl e Centner of Tin into two 
 
 I J equal Parts : Put each of them into a fepa- 
 rate Tell, and add to each fixteen Centners of gra- 
 nulated Lead, and one of Copper : Put the whole 
 under the Mufifel, and make a very llrong Fire : The 
 Tin will be calcined immediately, and fwim upon the 
 Lead {Parti. §41.) 
 
 2. Then diminifh the Fire a little ; till the Alhes 
 ©f the Tin that fwim atop, do no longer fparkle : 
 
 When 
 
Assaying Metals. 229 
 
 When you fee this, add with a Ladle two Centners 
 of Glafs of Lead into each Teft ; in fuch Manner, 
 that it may be fpread wide, through the whole Sur- 
 face of the rejected Calx. Thus the Calx of the Tin 
 is fo much involved and penetrated by the Glafs of 
 Lead, that at laft it changes its Form of a Powder, 
 into the tenacious Form of Glafs. If you perceive 
 this, increafe the Fire to its higheft Degree ; ftir up 
 the Scoria’s with a warm Poker, and when you have 
 feen the Signs of a compleated Scorification, pour 
 out the Mafs ; and for the Reft, obferve here the 
 fame Things, which we prefcribed in the third Pro- 
 cefs. 
 
 3. The Scoria’s being feparated, put both Regu- 
 lars into two Coppels well heated ; and put into a 
 third Coppel fixteen Centners of Lead, and one Cent- 
 ner of the fame Copper which you have ufed for the 
 Scorification (N° i.) of Tin that you may be able 
 to determine, how much Silver, Copper, and Lead, 
 thefe Quantities contain, which muft be afterwards 
 fubftradted ( Proc . II. N° 5). For if you negleft to 
 do this, you cannot be fure of having feparated the 
 Silver from the Tin. Let the Regimen of the Fire 
 be the fame during the Coppel ling, as in the fixth 
 Procefs. But the other two firft Regulars , muft 
 weigh the fame in the Balance : If not, the Procefs 
 muft be repeated. 
 
 Another Method. 
 
 1. Reduce your Tin into thin Lamina’s or 'into 
 Filings ; or, if it is brittle, pound it to a fine Pow- 
 der : Then put two half Centners of it into two fepa- 
 rate Tefts ; put them under the Muffel, and make a 
 middling Fire, that they may turn to Afhes : Then 
 take out the Tefts : Mixt with each Part of the Afhes 
 two Centners of Glafs of Lead, and then put each 
 feparate Mixture with twelve Centners of Lead into 
 the fame Tefts, and perform the Scorification in the 
 fame Manner as in the third Procefs. But make the 
 
 Q. 3 Cop- 
 
$3° The Art of 
 
 pelling according to the fecond Procefs. And thus 
 will the Operation proceed without Copper. 
 
 2. The Calcination of Tin is more fpeedily per- 
 formed, if you put into the Teft half a Centner of 
 Tin upon twelve Centners of Lead, and lay it on the 
 foreTart of the Muftel that is lefs hot : For then the 
 Tin will be perfedtly calcined in a few Minutes. 
 Then take out the Veftfels ; let them grow cold, that 
 the Afhes may be collected •, mixt them with Glafs 
 pf Lead, and finally, fcprify them upon the fame Lead 
 and in the fame Teft, as before (N°i,) 
 
 The Ufe and Reafons of the Procefs. 
 
 i. The firft Method by which the Scorification is 
 performed with Copper, is more fpeedy than the 
 foregoing : But, on account of the Copper added, 
 you muft not only add an enormous Quantity of Lead, 
 becaufe Copper requires fixteen Times the Quantity 
 pf Lead to be deftroyed (fee the fixth Procefs), but 
 you muft befides examine alfo feparately in a Coppel, 
 whether the Copper contains any Silver. The two 
 laft Methods are cleverer ; but they can hardly be 
 perfectly executed in two Hours : Becaufe the Scoria 
 of Tin, without adding Copper to it, is with great 
 Difficulty brought to the fame Degree of Perfedlion, 
 as when Copper is added. 
 
 PROCESS VIII; 
 
 To examine the Allay of Silver with Copper , by Cop - 
 
 pelling . 
 
 APPARATUS . 
 
 %' IQ U B the Metal upon the Touch ftone well 
 
 JLV wiped, and compare the proof* Needles ; to 
 know nearly what the Proportion of the Mixture is, 
 and of Courfe how much Lead muft be added, to 
 coofume all the Copper : But as the Lead neceftary 
 
 T . for 
 
Assaying Metals. 231 
 
 for the confuming of the Copper, is not in a Quan- 
 tity proportionable to that of the Copper, when 
 this is mixt with Silver ; we fhall here indicate the 
 Quantity to be added in every Cafe which was pre~ 
 fcribed by Erker ; though fome others differ very 
 muchdfrom him. But we fhall take for our Exam- 
 ple a Series of Needles, made according to the Mark 
 divided into half-Ounces and Grains {Part I. § 2 90), 
 
 5 . Ounc. Suv. ~ Ounc. Copp.« Marks of Lead to be added . 
 
 1 5 ~ ~ — 
 
 4 
 
 15 — — 1 — 
 
 6 
 
 14 - — ~ — - 2 * 
 
 8 
 
 12 & 13 — 4 & 3— 
 
 10 
 
 9 — 12—7 — 4 — 
 
 14 
 
 4 — 8—12 — 8— 
 
 15 
 
 1 — 4 — 15 — 12— 
 
 16 
 
 Every Body may eafily reduce this Table to the 
 Needles made according to the Mark of the Avoir- 
 depoids, or that of Karats : Nor is it neceffary to 
 proportion the Quantities of Lead to be added, fo 
 far as one half-Centner. 
 
 2. In the mean Time, let the Metal to be tried 
 with the Needles, undergo the Operation of Cop- 
 pelling, together with the Quantity of Lead indi- 
 cated (N° 1), as in the fixth Procefs. Only you 
 are to obferve concerning the Regimen of the Fire, 
 that you mull make it the gentler, as the Silver is 
 allayed with a greater Quantity of Copper \ and on 
 the contrary, the fmaller the Quantity of the Allay 
 of Copper is, the ftronger mult be the Fire to be 
 ufed in the Operation. As for the Reft, all we 
 have faid in the fixth Procefs doth likewife belong 
 to this. 
 
 Lit 
 
 0.4 
 
2$z The Art of 
 
 The TJfe and Reafons of the Procefs . 
 
 1. Pure Copper, in whatfoever Quantity, is in- 
 tirely confumed by fixteen Times as much Lead. But 
 it is quite otherwife, when it is mixt with Silver : 
 For Copper is the more defended by the Silver, in 
 Proportion as it is in leffer Quantity mixt with Sil- 
 ver, and vice Verfa . For Inftance, half an Ounce of 
 Copper is confumed in the Coppel by fixteen half- 
 Ounces of Lead : But if one half-Ounce of Copper 
 fs confounded in the Fire, with eight half-Ounces of 
 Silver, fixteen half-Ounces of Lead will never fuffice, 
 to deftroy the whole half-Ounce of Copper. Now, 
 if you have found out by Experiment, the lead Quan- 
 tity of Lead that is fufficient, and repeat the Expe- 
 riment anew, with half an Ounce of Copper mixt 
 to fixteen half-Ounces of Silver ; you will fee, that 
 the fame Quantity of Lead, which in the firft Cafe 
 had the Power of compleating the Purification of 
 the Silver, is by no Means fufficienc, to convert the 
 whole Copper into Scoria *, and that fome more Lead 
 mult be added : and fo on. 
 
 2. Thence you may derive the Reafon why Silver 
 cannot be intirely freed from all Copper by copel- 
 lirig ? Refides, you will never buy any Lead, that is 
 altogether void of Copper : For you will find in no 
 Place any Heap of the pared lead- Ores, that are not 
 Rightly mixt with copper-Ore, or Pyrites. Now, the 
 perfect Separation of fuch a fmall Quantity of Cop- 
 per, which is indeed very difficult, would never re- 
 pay the Charges of it ; wherefore, it remains in 
 the Lead, after this is melted out of the Ore. There- 
 fore, whatfoever Quantity of Lead you may ufe for 
 the Purifying of Silver from Copper, there remains 
 always iome minute Quantity of the Latter adherent 
 to the Former : And as Copper is the more diffi- 
 cultly leparated from Silver by Lead, as the Propor- 
 tion of the Copper with Regard to the Silver dimi- 
 mfhes ; for this Reafon, a greater Excels of Lead 
 
Assaying Metals. Z33 
 
 is required with Regard to this refiduous Copper, 
 than is necefiary, even in the Lead itfelf, with Re- 
 gard to the Copper mixt to it. He therefore who 
 attempts the moft intimate Depuration of Silver by 
 coppelling, mull previoufly render the Lead per- 
 fectly pure from all Copper : of which hereafter. 
 
 P R O C E S S IX. 
 
 To precipitate Silver out of its Ore , by coppelling alone » 
 
 APPARATUS . 
 
 i. TjOund one Centner of the Ore ; roaft it (Proc a 
 A IV. N°. I.) *, when roafted, beat it to a moft 
 fubtil Powder ; and, if it melts with Difficulty on 
 the Fire, grind it together with one Centner of Li- 
 tharge, which is not necelfary, when the Ore melts 
 eafily. Then divide the Mixture, or the Powder of 
 the Ore alone, into five or fix Parts, and wrap up 
 every one of them feve rally, in fuch Bits of Paper as 
 can contain no more than this fmall Portion. 
 
 2. Put a very large Coppel under the Muffel : 
 Roaft it well firft, and then put into it fixteen Cent- 
 ners of Lead : When the Lead begins to fmoak and 
 boil, put upon it one of the faid (N°. i.) Portions 
 with the fmall Paper it was wrapt up in, and dimi- 
 niffi the Fire immediately, in the fame Manner as if 
 you would make a Scorification in a Teft, but in a 
 lefier Space of Time. The fmall Paper, which turns 
 prefently to Allies, goes off of itfelf, and does not 
 ♦ fenfibly increafe the Mafs of the Scoria’s : The Ore 
 proceeding therefrom, is call on the Border, and turns 
 to Scoria’s very foon. Increafe the Fire again imme- 
 diately, and at the fame Time put another Portion 
 of the Ore into the Coppel, as was juft now faid : 
 The lame Effeds will be produced. Go on in the 
 faille Manner, till all the Portions are thrown in, 
 and confumed in the Lead. Finally, deftroy the re- 
 maining Lead with a ftronger Fire. 
 
 3. The 
 
234 Art of 
 
 3. The Silver that was in the Ore and the Lead, 
 will remain in the Coppel : If you take out of it the 
 Bead proceeding from the Lead, you will have the 
 Weight of the Silver contained in the Ore, If the 
 Ore employed was eafy to be melted, all the Scoria 
 vanifhes ; but if it was refraftory or not fufible, all 
 the Scoria does not always go away ; but there re- 
 mains now and then fomething of it in the Form 
 of Dtift. A great many Ores and Metals may be 
 tried in this Manner, except only fuch as fplit and 
 corrode the Coppels : There are likewife fome of 
 them, which mull be previoufly prepared, in the 
 fame Manner as is required, to render them fit for 
 going through a Scorification. See all the foregoing 
 Procefies. 
 
 ! The Ufe and Reafons of the Procefs . 
 
 jr. The Ore thrown at feveral Times upon Lead 
 boiling in a Coppel, may be difiolved without the 
 foregoing Scorification. But this is very far from 
 having an equal Succefs with all Kinds of Ores : For 
 there are Ores and Metals which refill very much to 
 theirDiflolution by Litharge; and which being on this 
 Account thrown on the Border are not fufficiently 
 difiolved ; becaufe the Litharge Heels foon away into 
 the Coppel. Neverthelefs, there are fome others, 
 which vanifh intirely by this Method, except the 
 Silver and Gold that was contained in them, 
 
 2. A previous Roafiing is necefiary, firfl for the 
 Reafons mentioned (Pm. IV. Uf N°. 1.) and then 
 becaufe the Ore thrown upon boiling Lead, fhould 
 not crackle and leap out : For, having once pafied 
 the Fire, jt bears the mod fudden Heat. 
 
 3. Though this Method requires no previous Sco- 
 rification, you are not to conclude from thence, that 
 it is the fame with the Operation by which Metallur- 
 gifis feparate Silver from its Ores : For in thefe Cafes 
 2 Scorification is always previoufly made : For which 
 
 Reafon 
 
Assaying Metals. 235' 
 
 Reafon thefe two Operations are not always attended 
 with the fame Effe< 5 ts. 
 
 PROCESS X. 
 
 The purifying of Silver by Lead , in a large Teft, by the 
 Blaft of Bellows . 
 
 APPARATUS. 
 
 1. T)U T into a large Ted made in an earthen Pot 
 JL (Part I. Plat . I, Fig. II.) and dried before- 
 hand in a warm Place, red burning Coals, till it is 
 thoroughly dry, and quite burning hot. Then make 
 a Hole in the Hearth of the Smith’s Forge, fit to re- 
 ceive the Pot with its Ted, and fill it with Allies, to 
 fuch a Height as that the Border of the Ted put into 
 it may be as high as the Hearth of the Forge. Place 
 the Pot in a horizontal Situation, and fill the Space 
 between the Ted and the Cavity of the Hole, with 
 Allies well prelfed down, led they fhould be eafily 
 blown away. Then difpofe the Nofel of the Bel- 
 lows in fuch a Manner, that blowing obliquely down- 
 wards, it may play drongly upon the Cavity of the 
 Ted : And this you will know to be well done, if 
 the Wind proceeding from thence, diffipates the 
 Allies fallen into the Ted. 
 
 2. Put into the hollow of the Ted, fo much Straw, 
 Paper, Linen, or worn out Cloth, as is neceflary to hin- 
 der the Surface of it from being damaged by the Silver 
 to be put into it : Put your Silver thereupon, and cover 
 it well all over with red burning Coals : Then excite 
 the Fire with the Bellows, till the Silver melts: This 
 done, remove towards the Border the Coals hitherto 
 kept in the Middle of the Ted. Add next fome 
 new Wood and Coals, efpecially towards the Bellows ; 
 and place the Coals all round in plenty, provided 
 they do not intercept the Sight of the Mafs in fufion : 
 And mean while, continue to make a drong Fire 
 with the Blad of the Bellows. 
 
 3. Then 
 
2 $ 6 The Art 
 
 3. Then add at feveral Times fome Lead reduced 
 into fniall Globules of a determined Weight : The 
 fame Phenomena will appear, that were mentioned 
 ( Proc . II). Go on with adding fome Lead, and then 
 dimini fh the Fire a little, which muft not be greater 
 than is neceffary to keep the Silver in fufion : Conti- 
 nue thus, till the Silver is rendered quite pure : 
 Which may be guefied nearly, from tlie Examination 
 previoufly made of its Purity or Impurity, by the 
 Needle or by a docimaftical Trial ; and from the al- 
 ready confumed Quantity of Lead, that was judged 
 necefiary for the Purifying of it. However, you 
 will be more fure of this ; if, the Lead being con- 
 fumed, you thrull a moift iron-Wire into the melted 
 Silver, and look upon what adheres to it, thelnftant 
 it is fetched out, to fee whether it is become yellow, 
 or white, polifhed, and malleable : If not, more 
 Lead muft be added. The melted Silver muft be 
 ftirred fometimes v/ith a crooked Iron ( Part I. Plat . 
 IV. Fig. IX), towards the End ; that the Lead pof- 
 fibly adhering underneath, may be intirely con- 
 fumed. 
 
 4. The Operation being nnifhed, pour Water 
 Drop by Drop, or with a final! Stream, upon the 
 melted Mafs *, that the Silver may grow folid. When 
 it is fo, take it out of the Teft with a Wedge, rub 
 off all the Filth and Allies adherent to it, with a brafs- 
 Brufh made of final 1 brafs Wires colle&ed into a 
 frtiall Bundle, pouring in the mean Time conftantly 
 fome Water upon the Silver. 
 
 'The Ufe and Reafons of the Procefs. 
 
 x , Take Care in this Procefs, that the Fire be not 
 continued too ftrong : For by that Means the Tefts 
 grow foft, and a great Deal of the Silver is loft. 
 For the fame Pur pole, the Teft muft be put into the 
 Pit, and furrounded on all Sides with Alhes > whereby 
 you hinder at the fame Time the Pot that contains 
 the Teft, from fplitting and fallingdown, and all the 
 
 Silver 
 
Assaying Metals. 237 
 
 Silver from being fpilled, if the Ted fhould at the 
 fame Time contract a large Crack. 
 
 2. If you add the Lead at feveral Times, the puri- 
 fying of the Silver may be performed, with a much 
 lefs Quantity of it, than that indicated in the eighth 
 Procefs. However, though, in this Operation, the 
 Silver be found pure at Top ; neverthelefs. Part of 
 the Lead, which is heavier, commonly hides itfelf 
 underneath (Proc. II. Uf. N °. 3), unlefs the Mafs in 
 fufion be now and then ftirred with a Piece of Iron, 
 towards the End. But the fame Inconvenience may 
 be prevented in the fmall Teds or Coppels, if you 
 ftrike thefe little Veffels with an iron- Wire, while 
 the Silver is dill in fufion, that this being melted may 
 be fhaken. Whence it plainly appears, that Silver 
 and Lead mixt only by Fire, are not fo well mixt to 
 each other, as that a perfectly proportionable Quan- 
 tity of both, may be found in any Part of the Mix- 
 ture whatever : Which being either unknown to or 
 negledled by Artificers, deceives them very often. 
 
 3. By this Method, a condderable Quantity of 
 Silver may be purified at one and the fame Time : 
 But if a very refradlory Scoria is produced, for In- 
 dance by a Mixture of Tin, it mud now and then be 
 funk to the Bottom with a Poker, that the Silver 
 may be walked off from it : And thus cad on the 
 Border of the Ted. But it is proper afterwards to 
 examine fuch a Scoria, to fee whether it has not car- 
 ried away with it, a Quantity of Silver deferving the 
 Charges of a Separation. 
 
 4. The Lead may again be reduced out of the 
 Teds employed in this Operation ; nay, this Lead 
 is not even without fome Silver ; efpeciaily if the 
 Teds were not good, or the Operations not exactly 
 made: But then it will be proper again to ufe the 
 fame Lead for a like Operation * that the Silver may 
 at lad be feparated from it. 
 
 PRO- 
 
238 
 
 The Art of 
 
 PROCESS XI. 
 
 The purifying of Silver in a large Tefi, under the 
 Muffel. 
 
 APPARATUS. 
 
 1. t\UT the Teft inclofed in an iron-Ring ( Part L 
 X Plat . I. Fig. VIII), into the Furnace repre- 
 fented ( Part I. Plat. IV), as you may very well un- 
 derftand, from the feveral Figures of the Furnace, 
 and from the Defcriptions given of them. When 
 the Teft has been red-hot in a ftrong Fire for about 
 half an Hour *, put into it the Silver wrapt up in Bits 
 of Cloth or of Paper, and divided into feveral Por- 
 tions : Fill the Orifice of the Furnace with red burn- 
 ing Coals, which mu ft be kindled with a Pair of hand- 
 Bellows, till the Silver is in Fufion. 
 
 2. This done add fome Lead 3 diminifh the Fire a 
 little : And do the Reft as has been prefcribed in the 
 foregoing Procefs. 
 
 The Ufe and Reafons of the Procefs. 
 
 1. The purifying of Silver is made in a much 
 neater Manner, by this Method than by the forego- 
 ing : And as the Regimen of the Fire may be obferved 
 here with great Exa&nefs, fo the Silver is purified 
 with a lefs confiderable Lofs : For which Reafon it 
 is always preferred to the foregoing, when you are to 
 purify Silver mixt with a great Deal of Copper : But 
 it is a very long Operation. 
 
 2. When you are to purify only a few Ounces, or 
 one fingle Mark of Silver •, you may put fuch a fmall 
 Apparatus into the docimaftical ( Part I. Plat . III. 
 Fig. I.) Furnace. 
 
 P R 
 
Assaying Metals. 235? 
 
 PROCESS XII. 
 
 A Method to feleft Specimens out of Metals that have 
 been boiled , as well as out of thofe that are melted 
 together with Sulphur and Arfenick , that there may 
 be the fame Proportion of the Mixtures in the latter r as 
 there is in the former. 
 
 W E have, in the foregoing Procefs, explained in 
 what Manner Silver, together with the Gold 
 that lies hidden therein, may be feparated from fo- 
 reign Bodies : But you cannot conclude otherwife 
 than hypothetically from thefe Proceffes, how much 
 Silver and Gold may be fetched, out of a greater 
 Quantity of the fame Matter, from which you have 
 ‘taken your Specimen for the docimaftical Trial : For 
 Inftance, whirher there is the fame Proportion of In- 
 gredients in a feparate Specimen, as in the whole 
 Mafs to be tried. But fuch an equal Union is not 
 always met with, in pure Metals confounded toge- 
 ther by the Fire : Which we have feen plainly 
 
 ( Proc.X. Uf N°. 2); where Silver melted with 
 Lead, and left to itfelf, was not evenly diffolved by 
 the Lead, but the fame Portion of the Mixture con- 
 tained more Silver at Top, and lefs underneath, and 
 Lead in an inverted Proportion. The fame Thing 
 happens likewife with Gold and Lead, and with Cop- 
 per and Lead : Unlefs you have Recourfe to fome 
 other manual Operation befides the Fire, in order to 
 obtain a more perfedft Mixture. Befides, it alfo de- 
 pends much from the greater or lefs Degree of the 
 Fire j which may increafe, diminifh, or totally dis- 
 turb the Addion of the Menftrua. Nay, the Mix- 
 ture of fome Metals, for Inftance of Gold, Silver, 
 and Copper, which eafily diftolveeach other equally, 
 is fo much troubled by the Addition of fome other 
 Metal, for Inftance of Lead ; that an equal Pro- 
 portion of the Metals is no longer preferved in every 
 Part of the Mafs : For Qojd and Silver yielding 
 
 more 
 
240 The Art of 
 
 more to Lead than to Copper, fink to the Bottom in 
 Company with it j fo that the Mixture is much richer 
 in Gold, Silver, and Lead there, than in the Middle, 
 and at the upper Surface. But if Sulphur and Arfe- 
 nick are joined to the Mixtures of Metals, they can- 
 not but make a great Alteration there : For as they 
 both diffolve one Metal more greedily than another ; 
 they not only render the Mixture inequal, but fome- 
 times deftroy it intirely : So that a Metal diffolved 
 by rhem, becoming lighter, it fwims at Top like 
 Scoria’s, while the other Part of the Mixture finks 
 towards the Bottom, by its Gravity. 
 
 APPARATUS. 
 
 1. When Ores grofly melted, are colleded into 
 brittle Regulus' s in the Beds of the Furnaces, you are* 
 to proceed in the following Manner. With a Ham- 
 mer and a Wedge, feparate from the Regulus two 
 Pieces of equal Weight, forlnftance of half an Ounce ; 
 that is, one in the Middle of the upper Surface, be- 
 tween the Center and the Circumference *, and the 
 other in the inferior Surface of the Regulus , but on 
 the oppofite Side. Beat both to a fine Powder, of 
 which weigh a Centner, and as Sulphur, Arfenick, 
 Iron, and a Portion of unmetallick Earth are not 
 wanting therein, proceed according to Proc. IV. 
 
 But when you have a Mind to examine a greater 
 Number of Regulus' s 9 together in one and the fame 
 Trial, cut off" Bits from each Regulus 9 in the Manner 
 mentioned : You need only take Care, that the 
 Weights of the Bits cut off, be nearly proportioned 
 to the Weights of the Regulus' s : Beat them all into a 
 fine Powder, and do the Reft as before. 
 
 2, But, when you are to examine Regulus' s that 
 are not brittle ; Bits muft likewife be cut off, in the 
 Manner juft (N°. 1.) mentioned : But when cut, and 
 weighed exadly, you muft put them altogether into 
 a new Crucible, well rubbed with Soap within, and 
 melt them : When they are well melted, ftir them 
 
 immediately 
 
Assaying Metals.. 241 
 
 immediately with a dry Stick half-burnt ; that they 
 may all be well mixt together : Leave them fo for 
 about one Minute •, then ftir them again' for the lad 
 Time, and throw into them a fmall Bit of Paper 
 Folded up, and rubbed with Wax or Tallow : And 
 while it burns with a clear Flame, pour the whole 
 Mafsat one Stream into the Moulds {Part I. Plat. II. 
 Fig. XX), placed quite horizontal, and rubbed with 
 Tallow *, and let this grow cold of itfelf, together 
 with the Mafs therein contained. But the Mafs ta- 
 ken afterwards out of the Moulds, and commonly 
 called Ingot , as is alfo the Cone itfelf ( Part I. § 223), 
 mud be fmooth, folid, and of an equal Thicknefs all 
 round : But if it appears rough, and the Infide of the- 
 Crucible (as far as the Mafs has touched it during the 
 melting and the pouring out) is feen covered with a 
 metallick Skin, it is a Sign that the Fire has been 
 defedive : And confequently an equal Mixture has 
 not been obtained. Beildes, a Fire too great and 
 continued too long, produces a Scoria fometimes fo- 
 lid, fometimes fpongy, full of Bubbles, covering the 
 Mafs here and there when it has been poured out and 
 cooled, or infmuating itfelf deeper into it, while it is 
 pouring out : If this be the Cafe, the Procefs mud 
 be repeated. If the Mafs is in good Condition, 
 fcour it well with coal- Duft, and weigh it, to know 
 how much of its Subftance has been loft. Then cut 
 off from it a Bit, in the Place which is diftant one 
 quarter Part of the Length of the whole Mafs from 
 each F.xtremity, in fuch Manner however, that the 
 Mafs may at the fame Time be divided by a tranf- 
 verfal Sedion. This done, fubftrad as much from 
 the Centner or docimaftical Mark, as all the Speci- 
 mens cut off from the Regains* s , and weighed toge- 
 ther before the Fufton, have loft of their Weight : 
 Let the reft go for an intire Centner or docimaftical 
 Mark, and with a File make the Specimen, which 
 you have cut off from the Mafs of the Ingot, equal 
 to it. However, take care not to fcrape oft' any 
 Thing from another Place, except from the two Sur- 
 
 R , faces 
 
24 2 7^<? Art of 
 
 feces which have been formed by the tranfverfal 
 Sedlion ; efpecialJy if there is any Lead in it. The 
 Scorification is made as in Proc . Ill, but without 
 iead-Glafs. Neverthelefs, if an imperfedfc and re- 
 fractory Scoria is produced, pour upon it a little of 
 lead-Glafs, to fubdue it. Let the remaining Remlus 
 go through the Operation of coppelling, as in 
 Proc. IL or, if there is any Copper, as in Proc. IV. 
 
 3. By thefe Precautions (N°. 1, 2) all the Silver 
 and Gold remaining out of the Teds, or reduced into 
 the Form of Tables, may and ought to be cut off, 
 and prepared for a Trial : However, it is not always 
 neceffary to begin by a Scorification j uniefs Iron, 
 Tin, are mixt to the Mafs : We have already 
 Ihewed the Manner of managing them. 
 
 4. When Coins are to be tried, you muft cut ofi 
 a fmall Bit from them along your Diameter, and with 
 a File reduce it to the Weight of the Mark, in the 
 feme Manner as the fmall Bit cut off from the Mafs 
 of the Ingot. 
 
 5. But when Coins of different Kinds, and old 
 Utenfils, that have been coloured by having been 
 boiled, are to be examined, the Thing is hardly 
 done with more Eafe and Security, than if all thefe 
 Metals are granulated ( Part I. § 216, 217.) together. 
 
 Pbe life and Reafons of the Procefs . 
 
 5. There is almoft a greater Care required, in the 
 Choice of thefe Specimens, than in the Operation it- 
 felf, by which Gold and Silver are feparated from the 
 other Minerals. Great Errors may be committed, 
 when an Ingot is to be melted out of the fmall Maffes 
 cut off. For Sulphur, Arfentck, Copper, Lead, 
 and all the other Minerals, evaporate in Part, when 
 the Fire is too itrong and too long kept, and partly 
 turn to Scoria’s, while the more fixt Part of the Sil- 
 ver and Gold does remain : For this Reafon, the 
 Proportion which ought to have been preferved in 
 the remaining Ingot, is taken away ; Whence it hap- 
 5 P ens * 
 
Assaying Metals. 243 
 
 pens, that the Examination indicates a greater Quan- 
 tity of Silver and Gold, than the Mixture out of 
 which the Specimens have been taken, does in Reality 
 contain. But this may be avoided, if you fubftrad: 
 that Part, which the Specimens taken together have 
 loft in the Fire, from the Centner or docimaftical 
 Mark : That the remaining Part may be of equal 
 Value with the Whole : Thus the Silver and Gold 
 remaining after the Operation, will perfectly anfwer 
 to the Quantity contained in the whole Mais of the 
 Mixture. 
 
 2. When Lead enters into the Mixture together 
 with Copper, the Ingot ought never to be extin- 
 guillied with Water : For the Copper growing cold 
 on a fudden in Water, contracts, and repels the Lead 
 ftill in Fufion towards the Outfide, and towards that 
 Part of the Ingot which is immerfed the laft into the 
 Water* Like wife, the Ingot is always richer in Sil- 
 ver and Gold, in the Place where the Cone has been 
 inclined towards the Horizon, than it is in the oppo- 
 fite Extremity : Which is efpecially true of thofe 
 Mixtures, in which Lead and Copper enter together. 
 The Reafonof this is felf-evident, from what has been 
 laid at the Beginning of this Procefs. But the Copper 
 muft be tried before it is roafted, to fee whether it 
 contains Silver, or Gold : For after that, their Sepa- 
 ration is hardly worth the Charges (Part I. § 468* 
 
 4690 
 
 3. Old Utenfils and Coins may be very well tried* 
 if previoufly granulated. For when the Boiling hap- 
 pens to render them white, or when the Metal with, 
 which the Allay has been made, is not mixt in an 
 even Manner, you are infallibly deceived. Now, 
 they are rendered white by all luch Bodies, as corrode 
 Copper the moift' Way, and leave the Silver untouched. 
 When fuch Silver is allay’d with Copper, you muft 
 firft wipe it very well, or make it (lightly red in the 
 Fire ^ that the fat Filthinefs may be diffipated. Then 
 put it into a brafs Kettle tinned over, and pour upon 
 it enough of tartifti Small-Beer, or of Water* that the 
 
 R 2 Silver 
 
144 The Art of 
 
 Silver may be intirely immerfed : Then throw into 
 the Liquor a Quantity of fea-Salt, and Tartar : Put 
 the whole together upon the Fire, and make it boil : 
 Thus will the Copper be eroded from the Surface in a 
 few Hours, and the Silver remain alone. Therefore, 
 though you had put the moil poliflied Lamina into 
 the Fire, you will take it out quite deditute of Bright- 
 nefs, but of the whited Colour. Then wafli it with 
 Small-Beer, and rub the Surface of the Silver, with 
 Bruflies made of thin brafs-Wires. But if this Surface 
 is again rubbed with a fmooth Piece of Steel, it reco- 
 vers its former Polifhing. It is here neceffary to 
 know this deceitful Colour, not only when you ufe 
 the {Part I. §300.) Touch-done, but alfo in a doci- 
 madical Trial : For when the Specimen taken off 
 from fuch Silver, is thin, or of a large Surface, it 
 leaves more Silver in the Coppel, than if you cut 
 from that Silver a fmall Bit of the fame Weight, in a 
 Place where a leder Surface has been contiguous to 
 the corroding Solution. 
 
 PROCESS XIIL 
 
 The wajhtng (Part I. § 337, 479-) of an Ore , ren - 
 dered difficult to be melted , by Earths and Stones. 
 
 APPARATUS . 
 
 i.TJREAK your Ore in an iron-Mortar, to a 
 JO Powder not very fine : Weigh twenty or 
 
 thirty docimadical Centners of it, in a large Balance : 
 Put them into a wafhing Trough ( Part I. Plat. II. 
 Fig. XVI.) pour fome Water upon them, that the 
 Powder of the Ore may be thoroughly moid : Then 
 have a Veflel full of Water, the Diameter of which 
 mud be a little larger than the Length of the Trough : 
 Take the Trough with your left-Hand, at the Top 
 of the hinder-Part, and dip it horizontally into the 
 Water, and move it gently with your right-Hand, 
 from the fore-Parc of the Trough, which is lefs deep, 
 
 towards 
 
Assaying Metals. 247 
 
 towards the hinder- Part, which is deeper : Then take 
 out the Trough, and incline it a little on the fore- 
 Part ; that the Water may run out, and the heavier 
 metallick Part remain at the Bottom : Repeat this 
 feveral Times over, till the Ore remains quite pure. 
 
 2. If the Ore is inherent to a very hard Stone 
 hardly yielding to Iron, fuch as are Flints, and the 
 other Stones of that Kind, or to a ponderous, cal- 
 careous, Spaad-like Stone ; it muft firfl be weighed, 
 and then be made quite red-hot in a Crucible, and in 
 this Condition be thrown into a VelTel full of cold 
 Water, and after that be pounded very fine and 
 walked very clean. 
 
 3. When the Ore is walked, weigh it, and try 
 one Centner of it : that is, according as the Nature 
 of the Ore requires it. Thus you will ealily com- 
 pute, how much Silver or Gold you will be able to 
 obtain from twenty Centners of Ore. 
 
 The life and Reafons of the Procefs . 
 
 1. From what has been juft faid, and from what 
 was faid ( Part I. § 338) it appears, that every Ore 
 will not bear walking *, it Ikews likewife what kind 
 of wafhing each Ore will require ; and what Ores 
 can be walked without a Preparation : Of this lalt 
 Kind are thofe which confill of folid pure Particles, 
 and lie hidden in a foft fat kind of Earth, or in Sand. 
 Thence, you likewife fee, in what Manner they mult 
 be previoully pounded, or calcined (Compare Part I. 
 § 337). By Calcination, you not only break Stones 
 into Pieces with greater Facility, but Ores befides 
 melt into folider Malles, which molt commonly are 
 fpecifically heavier, on account of the Sulphur and 
 Arfenick in a Manner difperfed through them. 
 
 2. The Intention of walking is, to, render the Ore 
 more tradable in the Fire ; and to hinder the metal- 
 lick Parts from being difficultly precipitated, or 
 even totally detained by fo great a Mafs of Scoria’s, 
 
 R 3 and 
 
246 The Art of 
 
 and that a much greater Quantity of Ore may b$ 
 fluxed in the fame Fire, and in the fame Time. 
 
 3. But the lighted: Powder wafliea off, muft fome- 
 times be tried 1 For it now and then happens, that 
 the Water carries away a greater Quantity of Ore, 
 than there remains of it in the Bottom of the Veffel : 
 In which the mod experienced People are oftentimes 
 deceived. Nay, the Waters which run by Veins of 
 Ores, commonly enough carry Part of them away, 
 and after having dragged it a long Way together with 
 them, at laft let it fall at the Bottom of the Channels 
 As for the reft, fee G . Agric. de re Met. Lib. VJIL 
 
 PROCESS XIV. 
 
 The purifying of Silver with Nitre , 
 
 APPARATUS . 
 
 t, T> Educe your Silver to Grains, or Plates ; put 
 
 JtV them into a Crucible : Add about one quarter 
 Part of the drieft Nitre pulverized. Put upon this 
 Crucible another of a lefter Size, having at its Bot- 
 tom a Hole about as large as a Pea, in an inverted 
 Situation, that the Border of it may be received into 
 the Orifice of the other. Shut up the Joint of the 
 two Crucibles, with a Lute that may bear the Fire : 
 And when this is dry, put the Crucibles in a wind- 
 Furnace, and furround them with Charcoals, to the 
 Height of the Bottom of the upper Crucible, and not 
 further. 
 
 2. Then light the Fire at Top, and increafe it 
 till the Veftels are middling red-hot. Then with a 
 Pair of Tongs take a burning Coal, and hold it at 
 one Finger’s diftance diretftly above the Hole at the 
 Bottom of the upper Crucible : If you fee a fudden 
 clear Light produced near and about the Coal, toge- 
 ther with a crackling Noife, this fhews that the Fire 
 has a&ually the requifite Degree of Strength : But if 
 this either does not appear at all, or only very faintly. 
 
Assaying Metals. 247 
 
 the Fire mult be increafed. If, on the contrary, you 
 hear a violent Blad of Air, coming forth with a loud 
 crackling Noife, though you have not put the above- 
 mentioned Coal at Top, the Fire is too violent, and 
 mud of Courfe be diminilhed. Which being neg~ 
 le&ed, you will not only fuffer a great Lofs of Sil- 
 ver ; but large Vefiels, charged with a great Quan- 
 tity of Nitre, now and then burd afunder with Vio- 
 lence and Danger. 
 
 3. When this Phenomenon is over, increafe the Fire 
 as much as is necefiary, to make the Silver melt with- 
 out any Addition : Take the VefTelsout of the Fire : 
 Break the under one, when it is grown cold : You 
 will find the Regulus of Silver at Bottom, and alka-- 
 line Scoria’s (commonly green) at Top. If the Sil- 
 ver is not yet diffidently purified, or too rigid dill, 
 put it into another Crucible, and this thus open into 
 a wind-Furnace, throw upon it a little Nitre, and as 
 foon as it melts, pour it into a Mould for Ingots : 
 Thus it will be purified of every thing that’s not 
 Gold. 
 
 The Ufe and Reafons of the Procefs . 
 
 1. We have already confidered [Parti. § 137, 
 161.) the Action of Nitre upon Metals and Semi- 
 Metals. Therefore, if you operate in a due Manner, 
 Silver is, by this Method, rendered perfectly pure 
 and eafy to be bent. But if your Silver is very im- 
 pure, a final! Matter of it is deftroyed in this Opera- 
 tion , which mud be afcribed to the drong Detona- 
 tion of Nitre with other Metals, and to the Clammi- 
 nefs of the Scoria’s made by their Calxs. 
 
 2. The Nitre in this Procefs fee ms partly to be- 
 come volatile, and partly tochangeinto a fixt Alkali, 
 fo very pure, that there remains not the lead Foot- 
 dep of Nitre : For when you pour upon it Oil of 
 Vitriol, it does not in the lead excite the unpleafint 
 Smell of Slqua Fortis , which nevertheless is commonly 
 produced, when you prepare fixt Nitre in the ufual 
 
 R 4 Man- 
 
i 4 3 The Art c/ 
 
 Manner : The Reafon of this Diverfity is, that they 
 do not imploy a Fire fufficiently ftrong, to confume 
 or diffipate all Sorts of Nitre. 
 
 3. Silver thus purified for the firffc Time, has al- 
 ways in it a fmall Quantity of heterogeneous Metal : 
 But if you melt it a fecond Time (N°. 3.) with Ni- 
 tre, and pour it out the Moment it is in Fufion, you 
 free it of that Refidue, and render it very eafy to be 
 bent. But your Silver will not acquire fo great a 
 Degree of Purity and Pliantnefs, unlefs you pour it 
 out the very Inftant it is in Fufion. For the Nitre, 
 when left too long in the Fire, difiipates, or changes : 
 And when this happens, the Metals calcined by the 
 Nitre, though in ever fo fmall a Quantity, are re- 
 duced by the fat Exhalations of the Coals, and much 
 more flili when the Coals themfelves fall into them : 
 Nor is the refiduous alkaline Salt an Obftacle, but ra- 
 ther a Help to this. And as Gold, above all, is ren- 
 dered very rigid, or even quite brittle, by the lead 
 Quantity of Tin, Regulus of Antimony, &c. the 
 Reafon is plain, why unfkilful Artificers, try ten 
 Times and more, to render Gold pliant by Means of 
 Nitre, before they can obtain it. 
 
 PROCESS XV. 
 
 Precipitation of Silver out of the fame Bodies as were 
 mentioned in the foregoing Procejfes by Scorif cation , 
 in a Crucible . 
 
 APPARATUS. 
 
 1. H E Body out of which you intend to preci- 
 1 . pitate Silver, mull be prevsoufiy prepared for 
 a Scorification with its proper Ingredients*, of which 
 we have already fpoken in the foregoing Procefs j 
 then in the fame Manner, and with the fame Quan- 
 tity of granulated Lead, put it into a Crucible ftridHy 
 examined, that it be intire, foil'd, not fpeckled with 
 black Spots, like the Scoria of Iron, efpecially at its 
 
 inferior 
 
Assaying Metals. 249 
 
 inferior Part, and capable of containing three Times 
 as much. Add befides glafs-Gall and common Salt, 
 both very dry, and enough that, when the whole is 
 melted, the Salts may fwim atop, at the Height of 
 about half an Inch. 
 
 2. Put the Crucible thus loaded into a wind-Fur- 
 nace ; fhut it clofe with a Tile j put Coals round it, 
 but not higher than the Upper-Border of the Cruci- 
 ble : Then light them with burning Coals, and in- 
 creafe the Fire till the whole melts very thin : Which 
 will be done by a middling Fire, maintained always 
 equal, and never greater ; leave it thus for about one 
 Quarter of an Hour, that the Scorification may be 
 perfectly made : Take off the Tile, and ftirr the 
 Mafs with an iron-Wire, and a little after pour it 
 out into the Mould. 
 
 3. When the Regulus is cleaned from Scoria’s, try 
 it in a Tell by coppelling it. 
 
 The Ufe and Reafons of the Procefs . 
 
 1. The Scorification of any Ore whatever, or of 
 any other Body fetched out of Ores, may indeed be 
 made by this Apparatus , as well as in a Tell under 
 the Muffle : But it ferves Chiefly, to the End that a 
 greater Quantity of Metal may fometimes be melted 
 from it with Profit : For you may put many common 
 Pounds of it, at one ftngle Time into the Crucible : 
 But then you need not obferve the Proportion of Lead 
 prefcribed in the foregoing Procefs, nay, a Quantity 
 of Lead two or three Times lefs, is fufficient accord- 
 ing to the different Qualities of the Object. But the 
 Mafs will certainly be fpilt, unlefs you chufe a very 
 good Crucible. For there is no Veffel charged with 
 Litharge, that can bear a ft rang Fire having a 
 Draught of Wind, without giving Way through it to 
 the Litharge. 
 
 2. You add glafs-Gall and common Salt, that they 
 may forward the Scorification, by fwimming atop. 
 For the refr itory Scoria rejected by the Litharge, 
 
 and 
 
lyo The Art of 
 
 and adhering between this and the Salts that fwim 
 atop, is foon brought to a FJux *, and the Precipitation 
 of the Silver is thereby accelerated. They alfo in a 
 Manner hinder a imall burning Coal, fallen into the 
 Crucible, from fetting the Litharge a boiling, which 
 troubles the Operation. For the Litharge or Glafs 
 of Lead, efpecially that which is made without 
 any Addition, fo foon as the Phlogifton gets into it, 
 raifes into a foamy Mafs, confifling of a Multitude 
 of fmall Bubbles, very difficult to be confined, unlefs 
 the Phlogifton be intirely confumed, and the Litharge 
 reduced to Lead, which fometimes rifes above the 
 Border of the Veflel. 
 
 PROCESS XVI. 
 
 Precipitation by Iron and Lead , of Silver out of a Mix- 
 ture containing a great Deal of Sulphur . 
 
 APPARATUS, 
 
 T HIS may be done in the fame Manner as in the 
 foregoing Procefs, but much better after the 
 Manner following. 
 
 i. If you do not know already, how much Silver 
 lies hidden in the Mixture, you muft, for that Pur- 
 pofe, make a Trial, according to the firft, the fe- 
 cond, or the fourth Procefs. This done, let the 
 Mixture be melted in a wind-Furnace on a middling 
 Fire, in a Crucible, having a Capacity two or three 
 Times larger. Then caft upon it at feveral Times, 
 iron-Filings, not very rufty, and being one third 
 Part with regard to the Weight of the Silver: In the 
 mean Time increafe the Fire : When you fee the iron- 
 Filings quite difiblved by the Sulphur, and melted, 
 pour thereupon an equal Weight of granulated Lead 
 with regard to the Silver, in fuch a Manner, however, 
 that it may be difperfed all over the whole apparent Sur- 
 face of the melted Mixture : Then ftirr it with an iron- 
 Hook, that all thefe Things may be thoroughly mixt. 
 
 2. Shut 
 
Assaying Metals, ifi 
 
 2. Shut the Crucible very clofe : Increafe the Fire 
 ftill more *, j*nd after having left it fo for about half 
 a Quarter of an Hour ; pour the Mafs out into a 
 melting Cone, rubbed with Tallow, and warmed, 
 or into an iron-Mortar, prepared after the fame 
 Manner. 
 
 3. When it is grown cold, fhake the Matter out : 
 You will find at Top Scoria’s to be taken off, and 
 at Bottom a Regulus , that will have all the Silver in 
 it, together with the Lead, or at leaft with Part of 
 it. The Regulus, may be coppelled in a Teft. 
 
 4. If you know that there is already the fame Quan- 
 tity of Lead in the Mixture, it is not neceflary to add 
 any granulated Lead ; but rather to double the 
 Weight of the iron-Filings. 
 
 The U/e and Reafons of the Procefs. 
 
 1. All that was faid ( Part I. § 147. Coroll. 1, 4.) 
 is very well and plain. But you mull add Lead to- 
 wards the End ; that the Silver which is perhaps ftill 
 inherent in the Mixture, being quicker difiblved by 
 the Lead, may be precipitated, and fink to the Bot- 
 tom ; or that the Sulphur may be intirely" taken away 
 by the Lead (/. r), if it has not been thoroughly de- 
 ftroyed by the Iron, There are alfo fome other Me- 
 tals, that have the fame Effed ; but Lead is chofen 
 in this Cafe, becaufe it is very conveniently feparated 
 a fecond Time from the Silver : For there is always 
 fomething of the precipitating Metal, that mixes with 
 the Metal to be precipitated ; the more fo, as the Se- 
 paration is more exactly done : For who can fo exa&ly 
 determine the Point of Saturation, and the Degree of 
 the Fire ? 
 
 2. You muft not ufe Filings quite fpoiled with 
 Ruft : For they have no Virtue for abforbing the 
 Sulphur. 
 
 3. The Crucibles, which haveferved tothefe Pro- 
 ceftes, retain a little of the Silver, efpecially if they 
 are rough at the Infide : For this Reafon, the fame 
 Crucible, fo long as it remains intire, muft always 
 
 ferve 
 
2 The Art 0jf 
 
 ferve for the fame Operation. But when it breaks to 
 Pieces at Jaft, and the Bits are plunged into the boil- 
 ing Lead, all the Silver is feparated/rom it : Which 
 Lead, muft ferve for the like Operations, as well as 
 that which is reduced out of larger Tells : Thus all 
 the precious Metal is preferved. 
 
 PROCESS XVIL 
 
 The extracting of Silver , by Amalgamation , 
 
 APPARATUS . 
 
 lWTASH the Ores, Earths, Stones, and Sand, 
 W in which Silver lies hidden in its metallick 
 Form, according to Proc. XIII. when walked, in- 
 fufe them in very four Vinegar, in a wooden or glafs- 
 Veffel perfeflly clean ; but about a tenth Part of 
 Allum mull be firft boiled and diffolved in this Vi- 
 negar, that the walked Powder may be intirely co- 
 vered over : Leave them thus for one or two Days 
 and- Nights. 
 
 2. Decant the Vinegar, and walk the macerated 
 Powder in pure warm Water ; till the Water be- 
 comes quite infipid, when jull poured upon it : Dry 
 the Powder *, put it into an iron-Mortar : Then add 
 Mercury four Times the Quantity of the dried 
 Powder, and with a wooden Pellle, ending in a large 
 round Head, and adapted to the Infide of the Mortar 
 by its Figure and Size, beat the whole, till you fee 
 every little Part of the Powder rendered of a blackilk 
 Colour by the minute Globules of Mercury mixt 
 to it. 
 
 3. Then pour Water thereon, and continue the 
 Trituration for a While : becaufe you thus will walla 
 away the terrellrial Powder and the other heterogene- 
 ous Bodies remaining, and becaufe all the Globules 
 of the Mercury, will by that Means be aggravated 
 with the Silver and Gold. Pour out the turbid Wa- 
 ter, and add fomefrefh \ then grind the whole again. 
 
Assaying Metals. 253 
 
 til! all the remaining Powder be wafhed off at laft. 
 Then dry the remaining Amalgama with a Spunge, 
 and by a gentle Heat. 
 
 The Ufe and Reafons of the Procefs . 
 
 1. Amalgamation is chiefly ufed, when Silver lies 
 hidden in its metallick Form in Stones, Earths, and 
 Sand. But when it is in a State of Ore, the Bodies 
 that concur with it to form the Ore, muft be diffi- 
 pated ( Part I. § 463) : Otherwife, the Amalgama- 
 tion would not fucceed. Therefore, a previous Waffl- 
 ing muft be made, that the other Bodies which can- 
 not be diffolved by the Mercury, may be waffled off 
 as much as poffible : For, unlefs this be done, the 
 Mercury cannot a 61 freely upon the Silver : Nay, if 
 the Waffling is done afterwards, a great Deal of the 
 Mercury is wafhed off together with thefe heteroge- 
 neous Bodies. For which Reafon, likewife, the Ore 
 is foak’d in Vinegar prepared with Allum, that the 
 terreftrial dufty Bodies, or even the fat Ones, may 
 be wiped off the Surface of the Silver. As for the 
 reft, fee Part I. § 65. and follow. For this Reafon, 
 the Mercury fometimes refufes to diffolve the Silver : 
 Which neverthelefs is correfled, if the Mercury is 
 rubbed with common Salt and Water, and afterwards 
 wafhed very clean. 
 
 2. If you continue to grind the Amalgama with 
 Water, longer than till you fee no more Filth in it ; 
 the Water poured upon it will neverthelefs be always 
 turbid, and you will lofe Part of your Amalgama. 
 
 3. They make a particular kind of Mills, in which 
 a great Quantity of Amalgamations, are made, and 
 
 , which are well defcribed by G. Agricola , de re Met a 
 
 Lib. VIII. 
 
 PRO- 
 
The Art of 
 
 254 
 
 PROCESS XVIII. 
 
 The Separation of Silver from the Amalgama . 
 
 APPARATUS. 
 
 I. r^Pread a thin Leather upon a wide earthen of 
 glafs-Veflel, very clean : Fold it up in the 
 Form of a Bag, and pour the Amalgama into it : 
 Then tie the Bag very ftrongly at Top, that the 
 empty Spaces of the Plaits may not give Paflage to 
 any Part of the Mercury. This done* if you com- 
 prefs the Bag by wringing it hard, the major Part of 
 the Mercury will pafs through it, and run into the 
 Veflel under it. If you can no longer lqueeze any 
 Thing out, open the Bag, and you will find in it a 
 white Pafte, which fhall be the Silver and the Gold 
 that were in the wafht Powder : But there remains 
 about an equal Quantity of Mercury ftill mixt with 
 them after the Squeezing. 
 
 2. Put the remaining Pafte into a glafs Retort $ 
 and this into an iron-Pot full of Sand {Plat. IV* 
 Fig . I.) : Apply to it a Recipient, in which there 
 muft be fuch a Quantity of Water, as that the Orifice 
 of the Neck of the Retort may be immerfed into it : 
 Nor is it neceffary to clofe the Joints with Lute. 
 Make under this a ftrong Fire, till you fee the Mer- 
 cury applying itfelf by large Drops to the Neck of 
 the Retort, and falling into the Water, with a hif- 
 fing Noife : But if you hear a Crackling in the Re- 
 tort, then diminifh the Fire a little ; and if at laft 
 nothing more is diftilled by the great Fire, let the 
 Retort grow cool, then take it away, and fplit it 
 with a Thread dipped in Brimftone, which, for this 
 Purpofe, muft be tied about the Middle of the Belly 
 of the Retort, and fet on Fire : Then in the Fire 
 with Borax run the remaining Metal into a Mafs. 
 
 The 
 
Assaying Metals. ijj 
 
 f he life and Reafons of the Procefs. 
 
 1. As Mercury requires a Fire three Times ftrong- 
 er, to be volatilized, than Water does *, fo when it 
 is refolved into Fumes, it coagulates immediately, if 
 touched by Water ; nor are you to apprehend left 
 the leaft Quantity of it fhould evaporate in open VeL 
 fels, provided the Orifice of the diftillatory Veflel is 
 immerfed under the Water, You are only to take 
 Care not to irnmerfe it too deep : For in this Cafe* 
 not only the Neck of the Retort fplits eafily, but, 
 when the Degree of the Fire is very great at firft, 
 and afterwards lefs, the Water afcends through the 
 Neck of the Retort, and falls into the Belly of it, 
 which, on this Account, fplits when it is hot *, and thus 
 the Operation is deftroyed. But when the Neck of 
 the Retort is not immerfed, the Joints muft in this 
 Cafe be clofed with Lute : But if you imploy then 
 too great a Fire, the Vefiels burft violently afunder, 
 with fome Danger, becaufe of the pernicious Fume. 
 Befides, when your Fire is too ftrong. Part of the 
 Silver eafily gets into the Recipient together with the 
 Mercury. 
 
 2. If, for Want of an Apparatus for Scorification 
 and Coppelling, you have a Mind to indicate by this 
 Method, the Quantity of Silver contained in the Body 
 wa Hied ^ in this Cafe, the whole Amalgama muft be 
 diftilled through the Retort 5 becaufe Part of the Sil- 
 ver and Gold gets through the Leather : Nay, there 
 remains nothing at all of the Silver or Gold within 
 the Leather, if you ufe too great a Quantity of Mer- 
 cury, to extradl a fmall Quantity of thefe Metals : 
 Unlefs the Mercury be faturated with them, by a like 
 previous Procefs ^ and even then, you may be eafily 
 deceived as to the Quantity and Quality of the 
 Metal 
 
 PRO- 
 
 L 
 
iy6 
 
 The Art of 
 
 PROCESS XIX. 
 
 To render Silver very pure , by Precipitation out of 
 Aqua Fortis, with Spirit of Salt. 
 
 APPARATUS. 
 
 i.ittHEN Silver has been coppelled, difiolve 
 VV it with Aqua Fortis , in a very clean glafs- 
 Cucurbite : And if the Solution is the lead in the 
 World turbid, ftrain it through a double filtring 
 Paper, into another clean glafs-Vefiel. Pour into 
 this Solution, by little and little, Spirit of Salt, or 
 Solution of common Salt, or Salt Ammoniack, 
 enough to produce a perfect Aqua Regis ( Part I. 
 § 128. &c.) : The limpid Difiblution will im- 
 
 mediately become milky : Let it reft for fome Hours, 
 that the Silver extracted in Form of a white Powder, 
 may all fink to the Bottom : Which is fooner effected, 
 by pouring a great Quantity of pure Water upon the 
 Solution, if it be highly charged. This done, de- 
 cant gently the Liquor at Top. But, you muft pour 
 upon the Calx adherent to the Bottom, frefh Water, 
 or, what is ftill better. Phlegm of Spirit of Salt, or 
 of Aqua Fortis ; that all the Metal may be extracted 
 out of it : For the Calx is no longer diftolved in Aqua 
 Fortis , nor in Spirit of Salt. Finally, let it boil at 
 feveral Times in frefh Water, till the Calx and Wa- 
 ter are at laft perfectly infipid. Shake them toge- 
 ther, and pour them into a filtring Paper, that the 
 Water may go through it and then dry the 
 Calx. 
 
 2. Put it into a Crucible, well rubbed on the In- 
 fide with Soap, and cover it with about one Half of 
 any fixt alkaline Salt, very dry, and beaten to a very 
 fine Duft : Squeeze the Whole well with your Finger : 
 Cover the Crucible with a Tile, and put it in a wind- 
 Furnace, and make at firft a middling Fire for a 
 Quarter of an Flour, only to make the Vefiels grow 
 
Assaying Metals. 257 
 
 red-hot ; and then increafe it as much as is required 
 for a perfed: Fufion of the Silver and Salt. The Fu- 
 ll on being obtained, take out the Crucible, that the 
 whole may cool of itfelf ; or pour it into an Ingot i 
 the Silver fliall be reduced perfe&ly pure out of this 
 Calx. 
 
 3. If this filver-Calx (N°. i.) is expofed alone to 
 the Fire, it melts fo foon as it grows red ; and if you 
 then increafe the Fire a little more, it vanifhes in Fume ; 
 when poured out quickly it appears a Body of a light 
 fcarlet Colour, half-tranfparent, ponderous enough, 
 and fo tenacious, that it is difficult to reduce it ro 
 Powder, and if you break it, it feems to be of a fibrous 
 Texture within : Whence it is called Lunce Cornua , 
 on account of its refembling the Horns of Animals 
 on the Outfiae, 
 
 The life and Reafons of the Procefs, 
 
 r. Silver is not to be difiblved the moift Way m 
 Aqua Regis and Spirit of Salt ; on the contrary, when 
 it is already difiblved in Aqua Fortis , you precipitate 
 it thence with Spirit of Salt: But fo foon as this is 
 done, a Solution of the Silver by the Acid of Aqua 
 Regis happens in the dry Way : For a confiderable 
 Quantity of Aqua Regis is joined to the Calx of Silver 
 precipitated to the Bottom ; whence its Volatility 
 depends. For this Reafon iikewife, if you mix a 
 little of Spirit of Salt to Spirit of Nitre, you eafily 
 obtain the Separation of the former from the latter 
 by Silver. See Part I. § 122. But the Copper 
 whereof any fmall Quantity remains mixt with the 
 Silver, in the Operation of coppelling, is not to be 
 precipitated by Spirit of Salt : Therefore, when the 
 other Metals are confumed in the Coppel, the metal- 
 lick Part of this Calx is perfect and pure Silver, 
 Gold itfelf is alfo perfectly feparated in the fame 
 Manner, if the Aqua Fortis is not quite faturaced by 
 the Silver. 
 
 c. 
 
 ft. The 
 
2 j 8 The Art of 
 
 2 . The Spirits niuft be pure, and the Calx per- 
 fectly well wa fhed : Otherwife you will not always 
 purify your Silver. 
 
 3. This Luna Cornua , niuft be reduced the dry 
 Way, that is, by whatever abforbs Aqua Regis with 
 great Force. Therefore you fee this Property in 
 fome Metals, for Inftance, in Lead, Tin, and all the 
 alkaline fixt Salts. But the Silver is fpoiled anew by 
 the two former, and a great Quantity of it is deftroyed 
 at the fame Time : Which may be guefled from the 
 thick Smoak, which is produced in a violent Reduc- 
 tion made after this Manner. But all your Silver is 
 preferved by a fixt Alkaly, provided you ufe a proper 
 Courfe. 
 
 4. If you pour into the fixt Liquor remaining from 
 the Precipitation, and decanted, a fixt alkaline Li- 
 quor, or a volatile urinous concentrated Spirit, in 
 fuch Quantity as fhall greatly exceed the exact Point 
 of Saturation : The Colour of both, which was hard- 
 ly fen fible before, turns to a deep Azure, which muft 
 be owing to the Prefence of Copper : For when this 
 is in a final! Quantity, it diflolves the moift Way in 
 alkaline Salts, and then produces this Colour. The 
 downy whitifh Powder which is produced during this 
 Mixture, and at firft fwims like Flocks of Wool, 
 and then finks to the Bottom, is not Copper, but 
 proceeds from the Earth, which is produced in every 
 Regeneration of neutral Saits, and to which the final! 
 Quantity of Gold which poftibly was in the Silver, is 
 inixt. 
 
 PROCESS XX. 
 
 To extract Gold out of its Mdtrixs . 
 APPARATUS. 
 
 A L L the Procefies by which Silver is got out of 
 the Ores in which it lies hidden, and is fepa- 
 
 rated 
 
Assaying Metals. 259 
 
 rated from foreign Bodies, from Proc. I. to XVIII* 
 belong to this Article. For Gold, as well as Silver* 
 is free from the Addon of Lead and Glafs of Lead* 
 and fuitains the Coppel and the Teit, in which all 
 the other Bodies turn to Scoria’s. Therefore, Gold 
 rnixt with Silver is collected in the very fame Procefs 
 by which the faid Silver is feparated from its Ores : 
 as we have already mentioned feveral Times, in the 
 foregoing Chapters. Amalgamation itfelf is more 
 proper to Gold than to Silver 5 that is, as they are 
 both feparated from their Matrixs by this Operation 2 
 For there is no Metal, that is not more frequently 
 met with in a State of Ore, than in its metallick 
 State : But Gold, is always found in a true metallick „ 
 State ; unlefs its Quantity is many Times inferior to 
 that of the Silver adherent together with it in the 
 fame Matrix. But Gold, even in this Cafe, cannot 
 always be faid to be in a State of Ore (See Part L 
 § 400). Now, a true metallick State is required for 
 an Amalgamation ; becaufe no Extraction can other- 
 wife be made by Mercury. 
 
 There is indeed a great many Proceifes recommend- 
 ed by feveral Artificers, for the extracting of Gold 
 out of its Matrix ; and by which they fay that you 
 will obtain more than by the ordinary Method : But 
 they, for the moil Part, are fo trifling and fo tedious 
 in the Work, that they hardly deferve to be defcribed* 
 fo far they are from being worthy to be imitated. The 
 molt common of them are thofe, in which the Ore is 
 prepared by roafting ; which mull not be always neg* 
 leCted , as it is fometimes altogether neceffary. But to 
 repeat it fo many Times over, to extinguish the Ore 
 after each mailing in Urine of Children, or in other 
 Lies prepared in a particular Manner, then to fcorify 
 it firft in a Crucible with Lead and other Ingredients, 
 and afterwards to put it in a Tefl to fcorify it a feccnd 
 Time, and fo on, is a Method as filly as it is toil* 
 fome ; by which Gold is rather difiipated than it h 
 colleCled, 
 
 S 2 
 
 We 
 
z6o The Art of 
 
 We have then nothing to do here concerning Gold, 
 but to give the Methods by which Gold is feparated 
 from Silver, and thofe by which it is feparated from 
 the other Metals *, as far as thefe Methods differ from 
 thofe which we have already given, for the Separation 
 of Silver from other Metals. 
 
 PROCESS XXI. 
 
 To render Gold perfectly pure from Silver , by Aqua 
 
 Regis. 
 
 APPARATUS. 
 
 i. HE Mixture of Gold and Silver, muff firft 
 1 be coppelled according to Proc. II. or VIII. 
 with a fufficient Quantity of Lead, that the other 
 Metals may be feparated : In which a little more 
 Lead is preferable to a Jeffer Quantity. Out of the 
 remaining Regulus forge thin Plates ; and whenever 
 the Metal grows rigid under the Hammer, make it 
 red-hot in a gentle pure Fire, whereby its Dudlility 
 will again be reftored. 
 
 2. When the faid Plates are fufficiently thin, make 
 them red-hot for the laft Time, and cut them into 
 fmall Bits with a Pair of Sheers, and then keep them 
 in a warm Place, in a Cucurbite made of tranlparent 
 Glafs, pouring upon them a fufficient Quantity of 
 the pureft Aqua Regis, which muff be flrong enough. 
 In the mean Time, let the Orifice of the Cucurbite 
 be ffiut clofe with a Cornet of Paper, to prevent 
 any Duft from falling in. 
 
 3. The Diffolution being finiffied, pour out foftly 
 the fupernatant Fluid into a wide open glafs-Veffel ; 
 taking Care that the leaf Part of the Silver, adhe- 
 rent to the Bottom in Form of a white Powder, does 
 not go out along with it. Pour upon this remainingCalx 
 fome Phlegm of Spirit of Salt, and make it boil with 
 it a While, that the refiduous Diffolution of Gold may 
 be wafhed off, and added- to the fir ft by decanting. This 
 
 done. 
 
Assaying Metals. 261 
 
 done, infpifiate the Liquors over a gentle Fire, till 
 they are dry : Put what remains into a Crucible, and 
 cover it with Powder of Borax, melted before-hand 
 with a little Nitre : Cover the Crucible clofe with a 
 Tile ; and make the Melting fir ft with a gentle, and 
 a little after with a great Fire. Then pour it into a 
 Mould to have an Ingot. 
 
 The remaining Calx of Silver being wafhed out 
 of the Cucurbite, by pouring Water upon it, may in 
 a wide Veftel be decanted, and being dried by Fire, 
 may be melted in the fame Manner. 
 
 The Ufe and Reafons of the Procefs. 
 
 1. All the Metals that are diftolved in Aqua Regis , 
 muft be confumed by Coppelling, before the Difto- 
 lution ; left being diffolved together with the Gold, 
 and infpiftated, they be again confounded with it : 
 But the fmall Quantity of Copper remaining after the 
 Coppelling ( Proc . VIII. Uf N°. 2), being much 
 divided by that Degree of Fire which puts Gold in 
 Fufion, is deftroyed partly by itfelf, partly by the 
 Nitre, and turns to Glafs, and is received by the 
 Salts. 
 
 2. Gold may be precipitated quicker out of its 
 DiiTolution, by a fixt or volatile Alkali : But the Calx 
 proceeding therefrom, which is of a dark yellow Co- 
 lour, being dried on a gentle Fire, becomes that kind 
 of Gold called Aurumpulminans^ becaufe,when theHeat 
 is not increafed too fuddenly but only by Degrees, it 
 decrepitates with great Violence, and with a thunder- 
 ing Noife, and fcatters every Thing round it with 
 fuch a Force as was hitherto never obferved in any 
 other Body. We fhall foon teach, how this ought 
 to be reduced, or rather feparated from the Salts, 
 which produce this thundering Noife together with it. 
 
fOi The Art of 
 
 PROCESS XXII. 
 
 To feparate Gold from Silver with Aqua Fortis. 
 
 APPARATUS. 
 
 %. AS Aqua Fortis cannot corrode Silver off from 
 Gold, unlefs the former be three Times in 
 greater Quantity than the latter ( Part I. § 472) 5 
 it is not every Mixture of Gold and Silver that can be 
 feparated by Aqua Fortis. Let therefore the Mixture 
 of the white Allay be purified in a Coppel from the 
 other Metals, if there is any in it ; and be tried with 
 the Needles ( Part I. § 295). If the Allay of it is 
 fiich, that it contains fix Carats or Ids of Gold, and 
 eighteen or more of Silver ; you may reckon it fit to 
 make a Separation with Aqua Fortis : If not, you 
 muft either add a fufiicient Quantity of Silver by 
 melting together in the Fire, or make the Separation 
 with Aqua Regis , according to the foregoing Pro* 
 cefs. 
 
 2. Now, if the Mixture is fo allayed, as to admit 
 of the Addon of Aqua Fortis ; reduce it to fmall 
 PJates; put it into a fmall Cucurbite, and pour upon 
 it a double Quantity of Aqua Fortis , of a proper 
 Strength, and tried, that the leafl Quantity of Silver 
 may not be precipitated out of i t (Parti. §121, 122); 
 then put it in a warm Place, with a proper Cover. 
 If the Bubbles and red Smoak which are produced 
 during the Diffolution, make you think that the 
 Silver is corroded, decant the Solution, while it is 
 yet warm, into another glafsVefTel, and pour upon 
 what remains frefh Aqua Fortis , but in Quantity 
 twice as little as the firft Time : Expofe it again to 
 the Fire, to make it boil ; then decant it again warm, 
 and repeat this once more ; then wafn the Refidue 
 with frefn Water ; which will be your Gold, of a 
 dark Colour, light, fpungy, and brittle, out of 
 Which the Silver is corroded, 
 
 3. You 
 
Assaying Metals. 26 $ 
 
 3. You may pour it out, in the fame Manner as 
 you have done the remaining Calx of Silver, in the 
 foregoing Procefs (N°. 3). But the firft DifToluticn 
 being fatura ted, muft either be drawn off ( Part I. 
 § 125) to feparate from it the Silver, which will 
 then be perfedlly pure, or it muft be diluted with 
 Water: Put it into very clean thin copper Plates, 
 and immediately the Silver will firft cover the Copper 
 all over, under the Form of very thin and fmail 
 Leaves, and then by Degrees be precipitated to the 
 Bottom, and the Solution which was before deftitute 
 of Colour, fhall be tinged with a greenifh azure Co- 
 lour: Pour this together with the Calx into an edul- 
 corating Veffel {Part I. Plat. II. Fig. XIII) and ex- 
 pofe it a While to a Fire almoft ftrong enough to~ 
 make it boil : Thus all the Silver will at laft bedif- 
 engaged : Decant the Solution of Copper from the 
 lighter filver-Duft fubfiding, and pour upon it at fe- 
 veral times Water, which muft boil till it becomes 
 perfedHy infipid. Finally, let the dulcified Calx of the 
 Silver be melted together with Borax, firft by a gen- 
 tle Heat, and then by a ftrong Fire. But this Sil- 
 ver will not be perfectly free from Copper. 
 
 Fhe Ufe and Reafons of the Procefs . 
 
 See on this Point ( Part I. § 472. and the foregoing 
 Procefs) and obferve moreover, that, unlefs you 
 pour out the Solution of Silver warm, fotne Cryftals 
 of Silver will be produced, very difficult to be dif- 
 folved, .which furround the Remainder of the Gold 
 in fuch Manner, that the Silver remaining to be cor- 
 roded off from the Gold with recent Aqua Forth , is 
 very difficult to be diffolved. 
 
The Art of 
 
 264 
 
 PROCESS XXIII. 
 
 The Silver remaining (Proc. XXI. N°. 3.) retains Some- 
 thing of Gold in it *, and the Gold remaining (Proc. 
 XXII. N°. 2.) Something of Silver. 
 
 APPARATUS. 
 
 1. |F the Silver which (Proc. XXI. N°. 3.) remains 
 jL under the Form of a white Calx, is diffoived in 
 the purefi: Aqua Forth , there will remain at Bottom 
 a fmall Quantity of a Powder not diffoived, and of a 
 dark Colour ; but the Part of it which melts into a 
 Regulus and proves to be Gold, is extreamly fmall. 
 
 2. If the Gold out of which Silver has been cor- 
 roded by Aqua Fortis (Proc. XXII.) is diffoived in 
 Aqua Regis according to Proc. XXI, it leaves at the 
 Bottom of the Veffel a fmall Quantity of white filver 
 Calx, which the Aqua Fortis had not corroded from 
 the Gold, 
 
 The Ufe and Reafons of the Procef. 
 
 1. Every Thing is plain in the two foregoing Pro- 
 ceffes : But, the Aqua Fortis or Aqua Regis are more 
 or lefs pure, and of a proper Strength, according as 
 they are more or lefs frequently poured recent upon 
 the Mixture, and left to a£t a due Time upon the 
 remaining Metal with a fufficient Heat. In Chort, the 
 greater or Jeffer theThicknefs of the fmall Plates of 
 Silver and Gold is, and their Surface rendered more 
 or lefs clean by the Fire *, the more or lefs of the 
 Metal to be corroded by a proper corrofive Water, 
 remains undiffolved in the Refidue of the Mixture. 
 
 2. If, therefore, you would have either of thefe Me- 
 tals perfectly pure ; this mufl be corroded off from 
 the other by its Menftrnum : Gold, for Inftance, 
 out of Silver by Aqua Regis , and Silver out of Gold 
 by Aqua Fortis : But the Refidue of the corroded 
 
 . Body 
 
Assaying Metals. ^ 6 $ 
 
 Body remaining in the Mixture, commonly confti« 
 tutes T j 0 or of the whole Refidue. 
 
 PROCESS XXIV. 
 
 To determine the Quantity of the remaining Silver which 
 Aqua Fort is leaves in Gold. 
 
 T HIS Procefs is not effen daily different from 
 Proc. XXII. and XXIII. N°. 2, except 
 that many Cautions muff be taken, and a perfedl 
 Knowledge of the Proportion of the Gold and Silver 
 which conilitute the Mixture, is required in the 
 foregoing. 
 
 APPARATUS. 
 
 1. Take then of the pureft Gold prepared accord- 
 ing to the foregoing Proc. N°. 2. or to the XXI ft , 
 and altogether void of Silver, one docimaftical Mark 
 divided into Carats, and divide this into two Parts 
 perfedly equal : Add to each of thefe Portions the 
 Triple, that is one Mark and a half of the pureft 
 Silver {Proc. XXIII. N°. 2. or XXIL XIX). How- 
 ever, that the Mafs may not be too great, you may 
 take half a Mark inflead of an whole one : Which 
 muff alfo be underftood of the Parts of the Mark. 
 Put every one feparately into two Coppels well 
 heated. Make a ftrong Fire, that they may be made 
 red-hot : Then with a Ladle pour upon them one 
 Centner of granulated tried Lead, not containing any 
 ponderable Quantity of Gold in it. When the Lead 
 has been confumed in a bright Fire, leave it Hill for 
 one or two Minutes : Thus you will prevent the re- 
 maining of even the fmalleft Quantity of Lead 
 {Proc. II. Uf N°. 3). If both Regulus 9 s are equipon- 
 derous in the docimaftical Balance, the Operation 
 hitherto has fucceeded right, which otherwife muft 
 be repeated. 
 
 2. According to thefe Rules, make fmall thin 
 Plates with an Anvil and Hammer, both perfectly 
 
 fmooth 
 
266 The Art 
 
 fmooth and polifhed ; left any Thing fhould be 
 fcraped off. Mean while, the Metal muft be fre- 
 quently made red-hot, under the Muffel, in a golden 
 Difti put upon a Trivet ( Part I. Plat. II. Fig. XIV, 
 XV) *, left any ftnall Scales ihould go away from 
 thence. Roll thefe Plates fpirally, and after having 
 made them red-hot again, put a fmall Plate of each 
 Portion feverally into two fmall feparatory Cucur- 
 bites ( Part I. Plat. II. Fig. XI, XII) : Pour upon 
 them fome of the beft tempered Aqua Forth : Stop 
 the Orifice of the Cucurbite with a paper-Cornet, or 
 rather put upon it a Piece of fiat fmooth Glafs : Be- 
 caufe it is requifite that the elaftick Spirits fhould have 
 a Vent left them. If the Solution goes on then but 
 fiowly, you may put a fmall burning Coal under the 
 Trivqp. As for the reft, perform the Diffolution ac- 
 cording to Proc. XXII. 
 
 However, take Care, mean while, left the fmall 
 Cucurbite be fhaken, whereby the fmall brittle Plates 
 of the remaining Gold, which had hitherto preferved 
 their Figure perfect, might break afunder, or any 
 Thing of this Subftance be rubbed off. Having then 
 decanted the Diffolution, invert the Cucurbites gent- 
 ly, that the fmall Plate rolled up may fall foftly out 
 of every one of them into the golden Difh put under- 
 neath. 
 
 •3. Then fet the Difh upon its Trivet, and put it 
 under the docimaftical Muffel, which muft not be 
 warmer yet than your Hand can bear, and out of 
 which all the Afnes which may have fallen into it, 
 muft have been blown firft with a Pair of hand- Bel- 
 lows : Increafe the Fire fiowly, that the Difh may at 
 ■ 3 aft grow moderately red-hot within a Quarter of an 
 Hour: This fmall Plate thus heated being grown 
 cold, put it in a good Balance, to weigh it.' 
 
 4. Then let the fmall Lamina of Gold which is in 
 the other fmall Cucurbite, be roafted in the fame 
 Manner, and put it in the other moveable Scale to 
 compare it with the foregoing. They muft be both 
 perfectly equiponderous : if not, you have commit- 
 
Assaying Metals. 16/ 
 
 ted a Miftake, and the Procefs muft be repeated. 
 This done, put both Portions into one and the fame 
 Scale, and weigh them •, you will find by the Dif- 
 ference of the Weight (N°. i.) that the Mark of Gold 
 imployed has been increafed one or two Grains, 
 which proceeds from the Reftdue of Silver which 
 the Aqua Forth could not extract. But if both Por- 
 tions are lefs than the Mark imployed, it is an infalli- 
 ble Sign of a Defed, to be underftood from the 
 three foregoing Proceffes. The Excefs of Weight 
 proceeding from the Refidue of Silver, is called in 
 German and muft be noted exadly ; that 
 
 it may be fubftraded from the Gold in the fubfequent 
 Quartation *, that you may not believe that there 
 was more Gold in the Mixture, than there is in 
 reality. 
 
 Floe Ufe and Reafons of the Procefs . 
 
 1. By the foregoing Procefs (N°. i.) you cannot 
 exadly determine, how much Silver remains in the 
 Gold after the Separation by Aqua Forth : For while 
 the Gold is diftblved by Aqua Regis, it is a difficult 
 Matter perfedly to colled the minute Dull of Silver, 
 to free it from the Acid of the Aqua Regis , and to 
 weigh it, without fome Part of it being diffipated* 
 But if Gold diffolved by Aqua Regis , is again fepa- 
 rated from it by Infpiffation, Roafting, and Melt- 
 ing, it always fuffers a Lofs fuch as muft be here con- 
 fidered over and above. For this Reafon the Method 
 already mentioned is chofen, to deted this Increafe 
 of Silver. 
 
 2. The melting of Gold with Silver, is made with 
 greater Meatnefs and Perfedion with a little Lead in 
 a Coppel, than in a Crucible ; nor is it then fo eafy 
 to lofe any Thing of the Gold. Of this you will be 
 fure, if, after the Coppeliing, you weigh again the 
 Regains , which muft weigh four Marks : In this Cafe 
 kkewife you do not beftow afterwards your Labour 
 
8 The Art of 
 
 in vain, when an Error has been committed in the 
 Beginning. Nor do you lofe your Labour or Time, 
 if after having made fmall Plates with the Mixture, 
 you examine again the faid Plates rolled up in a Pair 
 of Scales : For then you not only are certain whether 
 you have committed any Error *, but you at the fame 
 Time detedf the Caufe of it. 
 
 3. Take Care that your Aqua Fortis be not too 
 much concentrated, and that the Diffolution be not 
 made more impetuous than is proper, by an exceffive 
 Heat, efpecially in the Beginning : For by fo doing 
 it happens, that the Aqua Forth which corrodes the 
 Silver out of the Interfaces of the fmall Plates, bif- 
 joins the Particles of the Gold by its elafack ErFer- 
 vefcence, whence it is eafy to lofe Part of it. Like- 
 wife every moift Body, refolved into Fumes with 
 great Hurry, may lecretly carry away along with it 
 Part of the inherent Body : Which is chiefly true 
 with Regard to acid Spirits. Thence it is plain, 
 that Silver mixt with Gold in much greater Quan- 
 tity, may be corroded by Aqua Forth , and at the 
 lame Time preferve the Figure which the Gold had 
 before, if you know what proper Strength Aqua Forth 
 ought to have. 
 
 PROCESS XXV. 
 
 'Tohyvefitgate accurately the Allay of a- Mixture of Gold 
 and Silver . 
 
 APPARATUS . 
 
 x, A Ccording to the carat-Mark in little (fProc. 
 
 XX XXIV. N°. 1.) weigh* of the Gold to be 
 tried one half Mark *, and after having found the 
 Allay of it by proper Needles, put it into a Coppel 
 with a fufficient Quantity ( Proc . VIII. N°. 1.) of 
 Lead : That the Copper mixt with it may be con- 
 fumed. If you have made the Coppelling in the End, 
 with a Fire flrong enough to diflipate all the Lead ; 
 
 you 
 
Assaying Metals. 2 69 
 
 you will be able to detedt, by Needles of the white 
 Allay, the Temper of the Refidue of Silver and 
 Gold, with dill greater Accuracy, than at firft by the 
 Needles of the mixt Allay. If you then weigh the 
 remaining Regulus , you know how much Copper 
 there was in the Mixture. This Trial may be made 
 previously, to know how much Silver mull be added 
 ftilJ, to prepare an Entrance for the Aqua Forth into 
 the Mixture. 
 
 2. Likewife, you muff, for the Examination of 
 your Gold, feparate two Specimens, ftrictly obferving 
 the Cautions prefcribed ( Proc . XII. N°. i, 2), if the 
 Circumftances require it. Let each of them weigh 
 half a Mark : Put both feverally into two Coppels 
 well heated, and perform the Coppelling with a fuffi- 
 cient Quantity of Lead. When there is a Corufca- 
 tion, add one Centner more of granulated Lead, and 
 jfuch a Quantity of the pureft Silver, as that it may, 
 together with the Silver already found in the Mixture 
 (N°. 1.) be threefold with regard to the Gold. We 
 Shall illuftrate this Matter with an Example. Let us 
 fuppofe, according to the Trial (N°. 1.) that the half 
 Mark has loft four Carats of its Weight in the Cop- 
 pelling : Subftradl them from the half Mark : There 
 will remain eight Carats, which conftitute the Gold 
 and Silver ^lone : Let them be rubbed upon the 
 Touch- hone, and agree with the Needle of the 
 white Allay, which is marked with eighteen Carats 
 of Gold, that is, in which one Part of Silver is mixt 
 with three Parts of Gold : You thence know, that 
 there are in the remaining Regulus of eight Carats, 
 one quarter Part, that is, two Carats of Silver, and 
 three Quarters, that is, fix Carats of Gold. As 
 then there mull be three Times more Silver than Gold 
 in the Mixture 5, add lixteen Carats of Silver, which 
 together with the two Carats already in the Mixture, 
 make eighteen Carats, 
 
 3. Moreover, melt the Mixture in a Coppel, with 
 the fame Cautions as in Proc . XXIV. then reduce 
 it to fmall Plates rolled up, and diiTolve it in the 
 
 fame 
 
270 The Art of 
 
 fam zAqua Forth which you have ufed in the foregoing 
 Procefs ; then wafh off the Salts with Water, roaft, 
 and after having compared the two Refidues in the 
 Balance, weigh together the Gold remaining from 
 the two half-Marks. Thus you will have found out 
 with Certainty, and to the very leaft Weight, the 
 Quantity of the Gold, which at firft you could but 
 have gueffed with Uncertainty : Subftrad: from this 
 Weight, as much as has been left of the Silver in the 
 fame Quantity, according to Proc. XXIV. Let us 
 then fuppofe in the prefen t Cafe, that the two fmall 
 Plates of Gold remaining, weigh twelve Carats and 
 fix Grains, and that the Refid ue of the Silver, ac- 
 cording to the foregoing Procefs, is two Grains in 
 the whole Mark of Gold : Therefore, if there re- 
 mains a little more than a half-Mark of Gold, you 
 muft fuhftradt one fmgle Grain *, and there will re- 
 main twelve Carats and five Grains. 
 
 The Ufe and Reafons of the Procefs . 
 
 i. Obferve befides what has been faid in the fore- 
 going Procefs, that you are not to imploy any other 
 Aqua Forth , but that wherewith you have tried the 
 remaining Silver : For fuppofing the other Opera- 
 tions to be the fame, the Difference of this Aqua Forth 
 makes the Difference of the Refidue. Therefore, 
 you muft repeat the foregoing Procefs as many Times 
 as you ufe other Aqua Forth . 
 
 PROCESS XXVI. 
 
 The purifying of Gold by Cementation (Part I. § 459, 
 
 460.) 
 
 APPARATUS. 
 
 2. i HU S E fome Tiles, or Bricks, not vitrified 
 by an excefiive Fire, nor too much tempered 
 with Sand : The oldeft are the belt. Clean them well 
 
 from 
 
Assaying Metals. 271 
 
 from Lime and all other Filthinefs, pound them in 
 an iron-Mortar, and then fift them through a coarfe 
 Sieve. Take four Parts of this Powder, and one 
 Part of Colcothar not wafhed, and of common Salt, 
 mix them together, the more the better, and grind 
 them in the fame Manner, as if you would make 
 Spirit of Salt. Moiften thefe Powders with a little 
 Water or Urine, fo as that they may cohere when 
 preffed between your Hands. 
 
 2. Take a clean earthen Veflfel, quite found, fuffi- 
 ciently thick, not glazed, and of the requifite Size 
 ( Part I. § 218J, ftrew the Bottom of it with your 
 moiftened (N°. i.) Powder, or Cement, and diftri- 
 bute this every where with your Finger, preffing it 
 down very gently, fo that the Thicknefs of the Ce- 
 ment may be half an Inch all about. Put upon it 
 Gold extended in thin Plates, not thicker nor larger 
 than a golden Duckat, and rendered perfectly clean 
 by making them a little red-hot in the Fire, fo that 
 the Cement may be covered all over with them. Then 
 put a fecond Layer of Cement after the foregoing 
 Manner ; and likewife the fame Plates of Gold upon 
 this as before, till the Pot is full to half an Inch dis- 
 tance from the Brim of it. Let this remaining Space 
 be filled up with Cement ; then at lafl cover the 
 Mouth of the Pot with a Tile, and flop $he Joints 
 clofe with Lute, left the Spirits forced out by the 
 Firefhould have the Liberty to get out. 
 
 3. Put this cementatory Pot thus filled, into a 
 Furnace in which fuch a Fire may be kindled for fe- 
 veral Hours, as that the Veftels put into it may be 
 made red-hot in an equal Manner : Such is the Jtha- 
 nor defcribed (Part I. Plat. IV. Fig . I), in which 
 the Veftels may be placed under or without a Muffel, 
 in the Middle of the Coals, or in the firft Chamber. 
 At firft, make a gentle Fire, and increafe it fuccef- 
 lively, till the Pots grow middling red-hot, and not 
 more : For if you fhould ufe too great a Fire, your 
 Gold would melt, and again be in Part fpoiled by 
 the fame Things corroded off by the Vapours of the 
 
 Cement.. 
 
271 The Art of 
 
 Cement. When the Veflfels have been red-hot for 
 fixteen or twenty Hours, take away the Fire, that 
 the whole may cool of itfelf. 
 
 4. This done, open the Pots, take out the Ce- 
 ment, which muft be foftened by pouring Water up- 
 on it, in cafe it fhould have hardened too much. If 
 there has been any Silver in the Mixture, you muft 
 preferve the Cement, as it contains in it the Metal 
 which has been corroded from the Gold. After this, 
 pour upon the Plates of Gold a little Water, to wafh 
 them clean, then make them boil in other Water, 
 which you are to renew feveral Times, till it is per- 
 fectly infipid : For, there are faline Spirits, that lie 
 hidden in the Plates of Gold, together with the Me- 
 tal corroded by them. After that, try the Gold 
 with the Touch-ftone, or more furely (till, by Quar- 
 tation, whether it has the Degree of Purity which 
 you defire *, unlefs you already know it, from a Series 
 of repeated Experiments. 
 
 5. If your Gold is not yet fufficiently pure, cement 
 it anew once or twice more. Workmen commonly 
 add fome Salt-ammoniac to the foregoing Cement, 
 that the other Metals may be the eafier corroded : 
 But in this Cafe, there muft be no Colcothar among 
 the Ingredients, for it fometimes happens that Gold 
 cannot be brought to a fufficient Degree of Purity, on 
 account chiefly of the Copper which it is commonly 
 mixt with. 
 
 ¥be Ufe and Reafons of the Procefs . 
 
 1. This Procefs fhews, that the ACtion of the Spi- 
 rit of common Salt is different, according to its dif- 
 ferent Purity, and the different Degrees of the Fire> 
 Likewife, if, inftead of common Salt, you imploy 
 Nitre in the Cement, the Spirit of it being difen- 
 gaged, confumes the Silver diftributed in the greateft 
 Part of the Gold : Which EffeCl it could not pro- 
 duce, even the moift Way, though it conftituted 
 two Thirds of the Mixture of Silver and Gold. For 
 
 the 
 
Assaying Metals. 273 
 
 the red (See Part I. § 152, &c.) However, Fire 
 cannot diffipate any Thing of Silver diffolved in this 
 Manner ; though it acquires fuch a Degree of Vola- 
 tility, efpeciaily through the Spirit of Salt: This 
 feems to proceed from the A&ion of the Air’s being 
 prevented. 
 
 2. Salt Ammoniac may alfo be imployed in the 
 fecond Cement *, though the Spirit of Salt is more 
 eafiiy expelled out of it, even without any Addition : 
 which is fhewed by the Liquid that precedes its Subli- 
 mation. Befides, Salt Ammoniac itfelf has a very 
 flrong Power over the other Metals. But as it is fo 
 very dear, and the whole Bufinefs may be performed 
 at lad with common Salt, Cements for this Reafon ' 
 may be done without it. The fame Thing mud be 
 obferved of all the other Ingredients, which enter 
 into Cementations, befides thofe already mentioned. 
 Obferve moreover, that, by a Variety of Additions, 
 you fometimes communicate to Cements a dony Con- 
 fidence, which cannot be conquered, and lofe pretty 
 often Part of your Gold, or even change the acid 
 Vapours to fuch a Degree, that they cannot exert 
 their Adion, or at lead are of no Service at all *, fo 
 that you increafe your Charges much more than is 
 neceffary. Thus, fometimes they prefer ibe feverai 
 Proportions of Gem, Fountain, or Marine Salt, of 
 which the different Effects are a perfed Secret to me. 
 The fame is true of the Blooddone, the Crocus Mar* 
 tis , the white Vitriol, the codly Verdigreafe, the 
 blew-Vitriol, the plumofe Allum, and the like ”, of 
 which Kinds of odd Mixtures we have a Multitude 
 preferibed by feverai Authors, who have written of 
 metallick Matters. 
 
 3. If you have a Mind to purify brittle Gold by 
 Cementation, it mud be granulated, before you 
 mix it with the Cement. But as thefe Grains are not 
 all made fo fine, as that the Vapours may penetrate 
 them thoroughly; the Granulation mud, be repeated 
 as many Times, as they are to go through a new 
 
 T Gemen- 
 
274 Art of 
 
 Cementation *. But the Grains, after each Cemen- 
 ration, muft be ieparated from the Cement, by 
 wa filing. 
 
 4. If a much greater Quantity of other Metals is 
 mixt with the Gold, it is ne t proper to feparate 
 them by a Cementation •, but in this Cafe, the Cop- 
 pel and Precipitation by Fufion ( Part L§ 466.) mud: 
 be preferred. 
 
 5. As the Cement receives the Silver that was in 
 the Gold, this may be reduced together with other 
 the like Sweepings mixt with Gold and Silver. For 
 this Purpofe, th.ofe Things are melted at lead with 
 lead- Ore or Litharge, and with the other Drodes of 
 Lead, in the Manner deferibed ( Part I. § 240.) 
 All the Silver and Gold is then received by the Lead, 
 from which thefe precious Metals may afterwards be 
 feparated by the Coppeh 
 
 6 . There are other Cements befides thefe, which 
 are called gradatory ; becaufe they give Gold, though 
 already perfectly pure, a much deeper yellow Colour 
 than it naturally has. But Copper, or at lead the 
 Bodies proceeding from it, and not yet intirely de-* 
 ilroyed, enter into all thefe Cements.- For Indance, 
 the Filings of Copper are calcined with Sulphur, and 
 the Crocus proceeding therefrom, ferves indead of 
 Cement, eicher alone, or mixt with the common 
 Ingredients of Cements •, and the Gold cemented 
 with it during twenty Hours, is thereby rendered 
 more yellow. The blue Vitriol has the fame Virtue. 
 But Verdigreafe has it chiefly ; and thefe Cements 
 are commonly fprinkled with the Solution of Salt 
 Ammoniac, and with Vinegar. But the Colour 
 they give proceeds from the Copper which joins with 
 the Gold , wherefore it is again didipated by Lead, 
 Antimony, and the ordinary Cements. Therefore, 
 thefe Kinds of Cements, it feems, ought to be called 
 degradatory , rather than gradatory , becaufe they in 
 Reality, render Gold impure. 
 
 * Un-lefs flatting; them with an Hammer upon an Anvil may 
 
 arifwef the fame Purpofe. ‘M 
 
 PRO- 
 
Assaying Metals. 275 
 
 PROCESS XXVII. 
 
 ‘The Precipitation and Purifying of Gold , ly crude 
 Antimony . 
 
 APPARATUS . 
 
 1. YjE FORE you come to the Procefs itfelf, you 
 
 JLJ muft previously know the Allay of your 
 Gold : which you may try either with the Touch- 
 stone, or with Aqua Forth (Proc. XXII) : For it is 
 not neceftary to try it by an exacl Quartation. But 
 the Diverfity of the Allay of Gold, demands a cer~ - 
 tain Variety in the Way of proceeding. If then the 
 Quantity of the Gold in the Mixture, is not lefs 
 than three Quarters, that is, eighteen Carats, the 
 Mafs muft be melted in a wind Furnace, and in the 
 mean Time the Crucible be covered, to prevent Coals 
 falling into it. This done, put into it at feverai 
 Times the double Quantity of crude Antimony pul- 
 verized in fuch Manner, that fo foon as one of the 
 Portions put into it is melted, another be immediately 
 fup plied : Leave thefe Things melted in the Fire for 
 fome Minutes more ; then pour them into the melt- 
 ing Cone {Part I. Plate II. Fig. XIX.) which muft 
 be warm and rubbed with Tallow, and immediately 
 ftrike with a Hammer the Floor on which the Cone 
 Hands *, that the heavier Part freed from the Sul- 
 phur may the fooner Sink to the Bottom : Invert the 
 Cone when grown cold, and ftrike it. The Body 
 that was poured into it will fall out, and have at Bot- 
 tom a Regulus more or lefs yellow, according as- there 
 was more or lefs Gold in the Mixture. This Regulus 
 may, with a gentle ftriking, be feparated from the 
 fulphureous Cruft which is at Top. 
 
 2. Immediately after this, melt on a lefter Fire the 
 faid Regulus in the fame Crucible, if it is intire : 
 When in Fufion add to it the double Quantity of 
 prude Antimony, and pour it out a little after. Se- 
 
 T 2 parate 
 
t r ]6 The Art of 
 
 parate the Regulus from the Antimony at Top, ac- 
 cording to N° 0 i : This you may repeat even a third 
 
 Time. 
 
 3. Next, put this Regulus into a thick Teft well 
 conditioned : Place it before the Bellows, according 
 to Procefs X, put Coals round it, and one or two 
 Pieces of Wood upon them, and make a middling 
 Fire, that is, fuch as is fufficient to melt the Regulus . 
 The reguline Part of the Antimony will vanilh in a 
 thick Smoak : Towards the End increafe the Fire 
 more and more, and keep it fo, till the Fumes are 
 over, and the Surface of the Gold of a green and neat 
 Colour. If the Regulus is but in lmall Quantity, 
 this Operation may be performed with a Pair of hand- 
 Bellows. Melt the remaining Gold with Borax and 
 Nitre, according to Proc. XXI. N°. 3 ; that being 
 freed of the fmall Quantity of Regulus of Antimony 
 which may happen to remain, it may be rendered 
 pliant : Which may be done fbill better by Cemen- 
 tation, when there is Occafion. 
 
 4. But when the Gold is impure to an Allay of 
 eight Carats ; it is not proper to perform the Preci- 
 pitation by Antimony alone : But you muff add to 
 the Antimony as many Times two Carats of common 
 Sulphur, as the Allay of the Gold is fo many Carats 
 lefs than eighteen. As for the Reft, let the Operation 
 be made as (N°. 1). Likewife let the Regulus be 
 melted twice or thrice more, with crude Antimony, 
 and the reguline Part of this, which was joined to 
 the Gold, be diftipated. 
 
 5. The fulphureous Mafs fwimmingat Top of the 
 Regulus (N°. 1, 2, 4), and broken off from it, 
 contains all the Metal feparated from the Gold : 
 Therefore it muft be kept, that you may feparate 
 from it the Silver, together with the fmall Quan- 
 tity of Gold which has been carried away by it. 
 
Assaying Metals. 277 
 
 The TJfe and Reafons of the Procefs. 
 
 1. Crude Antimony, befides its reguline Subflance, 
 has in it about one Part of common Sulphur, where- 
 with the Regulus is joined. But this Sulphur dif- 
 folves with greater Efficacy the Silver and Copper 
 wherewith the Gold is allayed, it abandons the Re- 
 gulus ( Part I. § 147. Coroll. 3) which finks gradu- 
 ally to the Bottom, on account of its being heavier 
 than thofe Metals which arediffolved by the Sulphur, 
 and were mixt with the Gold before. But though 
 the Gold itfelf does not admit this Adion of the 
 Sulphur ; yet while the Silver and Copper are cor- 
 roded by it, a confiderable Part of it divided into 
 minute Particles, is carried away at the fame Time, 
 and will not go again to the Bottom, unlefs the 
 Regulus itfelf, joining with it, fhould conftitute 
 larger Particles, which are more quickly precipitated, 
 becaufe the Surface of contad is diminiffied ; and fo 
 melt into one Regulus together with the Gold remain- 
 ing at the Bottom of the Veflel: Whence proceeds 
 the pale yellow Colour of the Gold. 
 
 2. When the Regulus is feparated, it muft be 
 melted again once or twice with frefh crude Anti- 
 mony, that the remaining Silver and Copper may be 
 feparated from the Gold in the fame Manner. 
 Whence it is plain, that the more Gold is allayed 
 with Silver and Copper, the greater Quantity of the 
 Regulus of Antimony is precipitated, and joined 
 with the Gold ; and on the contrary. Thence again, 
 the Reafon is plain, why the Separation of Gold from 
 Silver and Copper is not performed as well as could he 
 wiffied with the Sulphur alone ? Nor is it lefs evident 
 thence, that the Separation of Gold from Silver and 
 Copper muft be attributed chiefly to the Sulphur of 
 Antimony. 
 
 3. The Regulus of Antimony, which becomes vo- 
 latile by a middling Fire, is eafily diflipated from 
 the moft fixt Gold, by the Blaft of the Bellows 1 
 but you lofe fomething of your Gold, when you in- 
 creafe the Fire too foon, and too much. Nor is it 
 yet eafy, by this Means to bring Gold to a perfect 
 
 T 3 Dudility, 
 
278 The Art of 
 
 Duftility, unlefs it is afterwards melted with Nitre 
 and Borax ( Proc . XXI), or intirely corroded by the 
 Cement which remained from the Antimony. 
 
 4. As then the Sulphur of Antimony takes away 
 the menftrual Force between the Gold, the Copper, 
 and the Silver *, and the reguline Part does but help 
 the Precipitation *, it is eafy to find out, why it is not 
 proper to precipitate Gold from the other Metals, 
 with only Antimony, and that fome more Sulphur 
 muft ftill be added. For unlefs this be done, a 
 greater Quantity of crude Antimony is required, for 
 the fupplying of a fufficient Quantity of Sulphur : 
 But then in this Cafe fo much Regulus is precipi- 
 tated out of it, and joined to the Gold, that you 
 cannot diffi pate it without Lofs of your Time, La- 
 bour, and Gold : For this Regulus is very rapacious, 
 nor does it altogether fpare your Gold. 
 
 5. Such Gold, that is well purified by crude An- 
 timony, is indeed fo pure, that being compared 
 with the pureft Gold (Proc. XXI.) on the Touch- 
 Hone, its pale Colour, proceeding from the Silver, 
 is not eafily perceived ; but if the very fame Gold 
 is dififolved, according to Proc. XXI, by Aqua 
 Regis , there appears neverthelefs fomething of the 
 Silver. 
 
 6. As the Sulphur of x^ntimony has in it the Sil- 
 ver feparated from the Gold, this may again be pre- 
 cipitated out of it, according to Proc. XVI : But then 
 at the fame Time the remaining reguline Part of the 
 Antimony finks to the Bottom together with the Sil- 
 ver. Let then a Specimen be feparated from this 
 Mixture, and examined by Scorification (Proc. I.) 
 and by Coppelling (Proc. II) ; this done let the Re- 
 fidue of the Silver be put into Aqua Fortis , to know 
 whether there remained any Gold joined with the 
 Silver (Proc. XXII), and how much, if any : Which 
 may afterwards be intirely precipitated, according 
 to Proc. XXVIII, if it will pay the Charges. But the 
 Antimony which is melted with the Gold already 
 pure, as likewife that which is at three or four diffe- 
 rent 
 
Assaying Metals. 275? 
 
 rent Times put upon any Gold of any Allay what- 
 ever, has a very fmall Quantity of Silver in it : 
 Therefore, being hardly different from crude Anti- 
 mony, if you mix it with frefh crude Antimony, it 
 may again ferve for the fame Operations. 
 
 PROCESS XXVIII. 
 
 Precipitation of Gold by Fufion (Part I. § 466.) out of 
 a Mixture eight Carats under Standard . 
 
 I F the Quantity of the Gold in a Mark of the 
 Mixture, does not exceed three or four Carats, 
 it is not convenient to make a Cementation, nor a 
 Separation by Aqua Fortis , nor a Precipitation by 
 crude Antimony : Which is feif-evident, to any who 
 confiders the Nature of thefe Operations, and the 
 necefiary Expences which attend them. Therefore, 
 another Method mull be ufed. Likewife, if you 
 happen to have a Mixture of five, fix, or feven 
 Carats, fit to make a Separation by Aqua Fortis ; 
 you may perform the Separation the dry Way, when 
 particular Circumftances will not admit of the fore- 
 going Method. 
 
 APPARATUS . 
 
 1. Find out by the Experiment of Proc. XXII, 
 or by the Touch- flone, fir ft, whether there is in the 
 Mixture a Quantity of Gold fufficient to pay the 
 Charges of the Separation, and whether it does not 
 exceed three or four Carats. This being found out, 
 granulate the whole Mixture which is to go through 
 the Operation. Weigh half a Mark of the Grains 
 dried, and then examine again the Proportion of the 
 Gold and Silver, by an accurate Coppelling and Se- 
 paration in Aqua Fortis {Proc. XXV.) This you do 
 in order to know, whether all the Gold has been pre- 
 cipitated out of the Silver in the following Opera- 
 
 T 4 don. 
 
i8o The Art of 
 
 tion, or no. For if you take your Specimen out of 
 the Granulation, you are perfedly fure of the Pro- 
 portion of the Mixture. 
 
 2. Maiden flightly again with Water the granu- 
 lated Gold, and put it into a hollow Vefiel of a fufH- 
 cient Capacity, and add common Sulphur pounded 
 to a fine Powder one quarter Part with regard to the 
 granulated Metal, and mix the whole well with your 
 Hands, that a fmall thin Cruft of the pounded Sul- 
 phur may adhere to each moiftened Grain. Put this 
 again into an earthen glazed Vefiel, not much larger 
 than is necefifary to contain the Granula covered 
 with Sulphur : Shut the Pot clofe with a Tile, and 
 dofe the Interftices with thin Lute, and put it thus 
 in the Middle of the Hearth of a Fire Efficiently 
 large. Make a circular Fire round the Pot, diftant 
 from it about an Hand’s Breadth all round ; which 
 muft firft be gentle, and afterwards increafed gradu- 
 ally ; that the Sulphur may be melted, and the Gra- 
 nula dififolved by it : It will be a Sign of this Dififo- 
 lution, if Fumes and fmall fulphureous Flames, be- 
 gin to break forth here and there, through the Joints, 
 or through Chinks that may happen to be made : 
 Then remove your Fire, and when the Pot is grown 
 cool of itfelf, break it : You will find a black Mafs, 
 which you muft colled: after having feparafed it from 
 the Pieces of the Pot. 
 
 3. Make ready the wind-Furnace reprefented ( Part I. 
 Plate III. Fig . VI, or Plate IV. Fig, I), and in the 
 afh-Hole of it, make a Bed with Lute, to colled: 
 the Metal without any Lofs, or any great Trouble, 
 in cafe it fhould be fpilt out of the Crucible that fhould 
 happen to break. Put into this Furnace a Crucible 
 full of the granulated Metal calcined in the foregoing 
 Manner, putting under it a Piece of Tile well dried, 
 for it to ftand upon. Put upon this as many half 
 Ounces of granulated Copper, as there are Marks in 
 the Mixture in the Crucible : But if there is already 
 Copper in the Mixture ; do but com pleat the Defici- 
 ency of every Ounce : But if there is but one half 
 
 Ounce 
 
Assaying Metals. 28 1 
 
 Ounce of Copper in the Mixture, nothing muff be 
 added. Shut the Crucible clofe with a Tile, and 
 fill the Furnace up to the very Brink of the Cruci- 
 ble, with pickt Coals of a middle Size, taking great 
 Care not to leave any Vacuity : Kindle thefe Coals 
 by throwing upon them burning Coals, that a Mafs 
 fufficiently Fluid may be melted by a middling Fire : 
 Try with an iron-Hook pretty thick, whether the 
 Fufion is perfect : Then ftir the melted Mafs with 
 the fame Hook not keeping it too long immerfed, 
 becaufe it would foon be confumed. This done, 
 have at Hand a precipitating Flux, compofed of four 
 Parts of granulated Lead, of glafs-Gall, of common 
 Salt melted, and of Litharge one Part each, to which „ 
 you may add one Part of Filings of Iron and of Cop- 
 per. Weigh as many half- Ounces of this Flux, as 
 there are Marks of the granulated Gold, and with 
 an iron-Spoon pour it thereupon at feveral Times, 
 that it may be equally diftributed all over the Sur- 
 face of the melted Granula. After each Injeblion, 
 ftir the melted Mafs with an iron-Hook ; that all 
 the Things may be well mixt : Cover the Crucible 
 with a Tile, and leave it thus for a few Minutes, be- 
 fore you throw in another Portion. Mean while, 
 you mult here and there fupply with frefh Coals the 
 Fuel that is confumed, taking great Care not to let it 
 be wanting in any Place, left you fhould thus render 
 the Fire unequal, or left the Fuel being too much di~ 
 minifhed, you fhould be obliged to add too much 
 Coals at one Time : For, by that Means, theVeffels, 
 efpecially the larger Ones, eafiiy contradl Chinks, 
 and fjpill the melted Matter. 
 
 4. After the Quantity mentioned of the precipi- 
 tating Flux has been put in, let the Matter remain 
 in the Fire for about half a Quarter of an Flour more : 
 Then pour it into a melting Cone, rubbed within 
 with Tallow, or, if the Quantity is too great, pour 
 it into a warm iron-Mortar, covered over with a thin 
 Lute, and made very hot : Immediately after this, 
 put the Crucible again into the Furnace, and fur- 
 
 round 
 
i8z The Art of 
 
 round it with Goals : Mean while, invert the melt- 
 ing Cone or the Mortar, and throw out of it the Mafs 
 already grown folid. The inferior Part of it will 
 be a Regulus , which confifts of feme Part of the Sil- 
 ver, and of the whole Quantity of the Gold that was 
 in tHb Mixture. The upper-Part will be a Mixture 
 of the Remainder of the Silver, and of part of the 
 precipitating Flux : Take off* the Regulus and 
 
 keep it : Put the fulphureous Mixture broken and 
 ffill warm, into the fame Crucible ; make it melt; 
 and put upon it the fame Quantity of the precipitat- 
 ing Flux, juft as you did the firft Time, that the 
 Regulus may be again precipitated : Pour it anew 
 into the Cone or Mortar *, and after having feparated 
 the upper Mixture from the Regulus , precipitate it a 
 third Time, and by the fame Quantity of Flux, in 
 the fame Crucible : Nay, if you find by the Experi- 
 ment (N°. i.) that there is a^great Deal of Gold in the 
 Granula •, it will be proper to do the fame for the 
 fourth Time. 
 
 5. Finally, melt the precipitated Regulus in a 
 new Crucible, and pour it intoaVefiel full of Water 
 ftirred up with a birch- Broom, that it may be granu- 
 lated : Then pour the fecond Regulus into the fame 
 Crucible, taking, mean while, the granulated Metal 
 out of the Veffel : This done, granulate in the fame 
 Manner the fecond or third Regulus , and alfo at laft 
 the firft •, that you may have each Regulus granulated 
 feparately. Take of the dried Granulation of each 
 Regulus , one docimaftical Mark of the fmalleft 
 Weight, Free. XXIV. N°. 1, and try each of them 
 feparately in a fmall Coppel, to know whether any 
 Part of the precipitating Metals has not perhaps 
 been mixt with them, and how much. Then make 
 the fmall Portions of Gold and Silver remaining in 
 the Coppel, go through a ftriefter Trial by Aqua 
 Fortis, 
 
 You will find the Gold of the whole Mixture found 
 out by Experiment, N°. 1, either totally, or at leaft 
 in the greateft Part concentrated in the firft Regulus : 
 
 But 
 
Assaying Metals. 283 
 
 But if any Parc of the Gold is ftill deficient, it lies 
 hidden in the Granula of the following Regains . 
 Befides, it is no Rarity, to find fome fmall Part of 
 the Gold ifi a Regains that has been precipitated 
 three and even four Times, in fuch Manner, how- 
 ever, that the ftrft is always richer in Gold than the 
 following. Now, this Granulation, which is not 
 lefs than five Carats of Gold in one Mark, may af- 
 terwards be eafily feparated by Aqua Fortis> after 
 having been previoufiy purified in a Teft (Pm*. XIV.) 
 But it you have not yet fuch a Proportion, every 
 Granulation that contains fuch a fmallQuantity of Gold 
 as is worth the Charges of a Precipitation, muft be 
 cemented together with Sulphur, according to N°. 2^ 
 and the Gold muft be again fetched out of it with 
 Part of the Silver, by a precipitating Flux, in the 
 Manner juft defcribed (N°. 3. & foil) till the juft Pro- 
 portion is at laft obtained. 
 
 6. The Silver remaining in the fulphureous Mix- 
 ture, is fetched out by Lead, or by iron-Filings, in 
 a large Teft, or according to Proc. XVI. 
 
 If you have neither the Opportunity nor the Time, 
 to feparate from the Silver with Aqua Fortis , the 
 Gold which is fufnciently concentrated in the Rega- 
 ins' s ; the granulated Regulus may be cemented anew 
 with Sulphur (N°. 2.) to which you muft add twice 
 as much of crude Antimony, and the Gold may be 
 fetched out by a precipitating Flux, in the Manner 
 above defcribed. Thus the Gold will fink to the Bot- 
 tom, in the Room of the Silver, together with the 
 reguline Part of the Antimony. This done, you 
 muft melt again feveral Times the Regulus with 
 Frefh Antimony *, that the Silver, which has at the 
 fame Time crept into the Regulus in a fmall Quan- 
 tity, may be feparated : Finally, blow away the re- 
 guline Part of the Antimony. See Proc. XXVII. 
 Neverthelefs, if you are not verfed in thefe Opera- 
 tions, you can hardly perform this without fome 
 fmall Lofs of your Silver and Gold, 
 
 The 
 
284 The Art of 
 
 The Ufe and Reafons of the Procefs . 
 
 x. This Method of Proceeding, is ufed only in 
 fuch a Cafe when you have a great Quantity of Sil- 
 ver mixt with a fmall Quantity of Gold, nor can you 
 determine the fmalleft Portion of Gold that will 
 anfwer the Charges and Trouble of the Separation. 
 Neverthelefs, when Coals are cheap, and you have 
 a good Quantity of Silver mixt with Gold, you may 
 with fome Profit feparate one or two Grains ( Part I. 
 § 285.) or even one Penny- weight of Gold from it. 
 
 2, The DifTolution of Silver by Sulphur is perform- 
 ed in a clofe VefFel ; other wife, a vaft Quantity of 
 Sulphur would evaporate before the DifTolution fhould 
 be made ; unlefs you fix it by fome other Body, for 
 Inftance by the reguline Subftance of Antimony, as 
 in Proc. XXVII, which Body, however, mu ft not 
 hinder the Action of the Sulphur upon the Silver. 
 
 Let a precipitating Flux be fprinkled as equally 
 as poftible upon the melted Mixture : For if this be 
 negle&ed, and the Flux is gathered in a Heap in 
 any particular Place of the Surface •, the granulated 
 Lead which enters into the Flux, creeps out of it as 
 foon as it melts, and coming down into the Mixture 
 precipitates the Silver, which brings the Gold along 
 with it from that Column only through which the 
 Lead defcends, and falling further down, leaves the 
 reft, which is adherent to the Sides, in the Mix- 
 ture. For the fame Reafon, you muft alfo ftir up 
 the Flux together with the Mixture, with an iron- 
 Hook. Likewife, Saits, Litharge, Iron, and Cop- 
 per, perform a Precipitation, by abforbing the Sul- 
 phur, but they do it flower and more equally than 
 Lead, and the two laft ftill better, rendering at the 
 fame Time the Mixture fpecifically lighter, and more 
 fufible, fo that the Precipitation of the Particles of 
 Gold and Silver is the better performed, and they 
 hinder too great a Diffipation of the Sulphur. For 
 this Reafon, Gold mixt with a fmall Quantity of 
 
 Silver 
 
Assaying Metals. 28 5: 
 
 Silver, is more exa£Uy feparated from the Mixture 
 by this Flux well irn ployed, than it can be without 
 it, by means of Lead and Copper Only. It is at the 
 fame Time evident, that one or the other Ingredient 
 of the Flux may be fpared, unlefs you have it at 
 hand. 
 
 4. In this Manner, if any Part of the Gold has 
 crept into the fulphureous Mixture ( Proc . XXVII.) 
 along with the Silver, it may be precipitated again 
 out of it : Nor is there any other eftential Diffe- 
 rence between this and the foregoing Procefs, except 
 that the Precipitation of the Gold is here helped on 
 by Silver, whereas it is facilitated in the other Pro 
 cefs by the Regulus of Antimony. 
 
 5. The reft of the Silver is precipitated out of the 
 fulphureous Mixture according to Proc. XVI. This 
 Precipitation is performed, even to the fmalleft 
 Quantity of Silver, when you do it firft with Lead 
 alone, and then with Iron : For then the Lead itfelf 
 is again expelled out of the Mixture, and carries all 
 the Silver along with it : Which can by no Means 
 be done fo exa&ly by Iron alone. The fame may 
 be performed with a little Lead in a larger Teft $ 
 for this Mixture js nothing elfe than Silver diffolved 
 with Sulphur: On which Account it may be com- 
 pared with the richeft and moil fufible vitreous 
 filver-Ore {Parti. § 385 ;) as it has all the Proper- 
 ties of it, except that it contains a little Copper and 
 Lead. 
 
 PROCESS XXIX. 
 
 The Separation of fulminating Goldfro?n the Salts, 
 
 APPARATUS . 
 
 T AKE Flowers of Rrimftone two Parts, grind 
 them in a Mortar, and while you grind them, 
 add to them at feveral Times one Part of fulminating 
 Gold •, that the whole may be equally mixt : Put 
 this Powder into a Crucible, and put it upon a very 
 
 gentle 
 
2%6 The Art s/ 
 
 gentle Fire, which is fufflcient to melt the Sulphur* 
 refolve the Sulphur partly into Fumes, and finally 
 make it burn : When the Flame is vanifhed, increafe 
 the Fire, that the Veflei may grow red hot : W 7 hen 
 you fee no longer any Smoak fmelling of Sulphur, 
 add a Quantity of Borax, which muft be previoufly 
 melted, and of glafs-Gall, and melt the whole in a 
 great Fire : You fhall have a Regulus of Gold at the 
 Bottom* 
 
 The life and Reafons of the Prccefs. 
 
 i. Gold, Aqua Regis , and alkaline fixt Salt, when 
 expofed to the Fire, do not fulminate ; nor any two 
 of thefe jointly * except that the fixt Alkali makes 
 a fmall crackling Noife with the Acid of fea-Salt, 
 and Nitre accelerates with great Violence the con- 
 fuming of inflammable Bodies in the Fire : But all 
 the three united together by DifTolution and Precipi- 
 tation, produce this Phenomenon beyond all Expec- 
 tation. No Body has been able hitherto to give 
 any Explication of this Event : For thofe who at- 
 tribute the Caufe of it to the regenerated Nitre, do 
 not confider that Nitre produces no Fulmination, un- 
 jefs you add a Phlogifton to it, and ufe a greater 
 Fire than that required by fulminating Gold : Now, 
 there is not in the pureft alkaline fixt Salt 
 a fufficient Phlogifton, nor do they detonate, 
 when only joined to each other. But thofe who 
 fancy that the Nitre has this Phlogifton from 
 the Gold, are no lefs wrong : For in this Cafe, the 
 Mixture of Gold would be diflolved : Whereas it 
 happens on the contrary, that the Gold appears again 
 perfect in the Form of a very fine Powder, when 
 this Fulmination is performed with very fmall Por- 
 tions, under a large glafs-Bell, and upon a very neat 
 Surface. The crackling Noife of common Salt, is 
 no better an Explanation of the Cafe : For though 
 it agrees in every Refpedl* with the Fulmination of 
 Gold, except the Violence ; nevertheleis, the Pre- 
 cipitation of fulminating Gold by a volatile Alkali, 
 
 h Y 
 
Assaying Metals. 287 
 
 by which common crackling Salt is not regenerated, 
 is an Objection to this. The ammoniacal Sub- 
 itance which proceeds from the Acid of common 
 Salt, &c. and from volatile Alkali, alfo detonates with 
 Nitre : But if you take this for the Caufe of the 
 Detonation, the firft Experiment is repugnant to it, 
 by which fulminating Gold, having exactly the fame 
 Effect, has been produced by fixt Alkali: Nor does 
 the Inclufion of decrepitating or detonating Salts in 
 the compact Body of the Gold, produce the Violence 
 of the Fulmination : For if fulminating Gold is long 
 boiled in Water, this its violent Strength perifhes, 
 and the major Part of the Salts may be walked off* 
 Which could never be done, if they were inclofed- 
 in the Particles of the Gold, as in fo many Veffels 
 that fhould retain and imprifon them. Therefore* 
 the Explanation of this Point mull ftill be fetched 
 out of Dmocritus 9 s Well. 
 
 OF LEAD. 
 
 PROCESS XXX. 
 
 To reduce and precipitate Lead out of a fufible Ore . 
 
 (Parti. §456, 466.) 
 
 A P P A R A TU S. 
 
 1. TJ E AT your Ore into a coarfe Powder, juft 
 JD like the Grains of coarfe Sand : Weigh of 
 this Powder two docimaftical Centners, and put 
 them into a Teft. Put upon this a Tile or another 
 Teft : But you mud fpread the comminuted Ore as 
 wide as poffible in the Teft : Roaft it next, firft in a 
 gentle Fire, which mu ft be gradually increafed, till 
 the Veffei is almoft red hot : Leave it thus for a few 
 Minutes : then take off the Tile : and in a fliort 
 Time the blackifh Colour of the Ore will become of 
 a yellowifh a Ih- Col our : Which fhews that the Sul- 
 phur is diftipated at leaft for the greateft Part. 
 
 2. Beat the roafted Ore into a fubfil Powdef, and 
 add twice as much of the black Flux ( Part I. § 162), 
 
 of 
 
288 The Art of 
 
 of Filings of Iron not rufty, and of glafs-Gall ( Part I. 
 § 1 3 ?•) each half a Centner. Beat all thefe Things in 
 a Mortar, that they may be well mixt together, and 
 put them immediately into the Crucible, or into the 
 Skillet ( Part I. Plat. II. Fig . V, VI, X.) having 
 twice or thrice as much Capacity ; then cover them 
 over, a Quarter of an Inch thick, with common Salt, 
 and prefs them with your Finger. Shut the Crucible 
 clofe with a Tile, or with fome other fmaller inverted 
 Crucible, whole Brink may be received into the infe- 
 rior-one : Stop the Joint with fuch Lute as may bear 
 Fire : and then dry the whole at a moderate Heat. 
 But the Salts muft be very dry, and not fuffered to 
 melt by too great a Slownefs in the Operation. 
 
 3. Put the Crucible into the wind-Furnace ( Part I. 
 § 240.) and heap Coals upon it, fo as that it may be 
 covered over with them a few Inches high ; govern 
 the Fire in fuch Manner, that it may firfb grow 
 flightly red hot. Soon after you will hear your common 
 Sait crackle ; and then there will be a gentle hilling 
 Noife : So long as this lafts, keep the fame Degree 
 of Fire, till it is quite over. Then increafe fuddenly 
 the Fire, till the whole Mafs is melted : Which may 
 be done in a Quarter of an Hour, in a moderate 
 melting Fire. Take out the Crucible, and put it 
 upon the Hearth of the Furnace, which mull be 
 very dry : Strike it a few Times with a Hammer, 
 that the Lead that may perhaps be difperfed in 
 Grains at the Bottom of the Vefiel, may run into a 
 folid Regulus. When the Crucible is grown cold of 
 itfelf, and broken, you will find the Regulus , which 
 being weighed, will fhew how much Lead the Smelt- 
 ers may fetch out of the Ore. But the Silver, if 
 there chances to be any, is by that Means precipi- 
 tated alone with the Lead, and muft be dete&ed at 
 laft by coppeliing. 
 
 4. You will know that the Operation is happily 
 performed, if the Scoria fubfide in the Vefiel, and 
 if they do not foam over the Brink of the Vefiel, 
 and thus part of them make .their Way through the 
 
 Lute: 
 
Assaying Metals. 289 
 
 Lute : Another Sign of Succefs is, when no Parti- 
 cles of Lead appear feparate in the whole Veffel, but 
 when they all gather into a folid, tenacious, duftil, 
 bluifh, not very bright Regulus *, and when the Sco- 
 ria’s are hard, black and folid, except when there are 
 a few fmall Cavities in the Middle, when they are 
 contiguous with the common Salt : For the Sait does 
 not mix with the Flux ; but remains feparate, and 
 fwims a Top, being however of a black Die. When 
 the Scoria is foft, light, pulverulent, taking not 
 much lefs Room than the other Things put into the 
 Crucible, this Ihews that the Fire having been defec- 
 tive both in Strength and Duration, the Lead has not 
 on this Account been fufficiently precipitated out of * 
 the Scoria ; the fame will be ihewn by a rough Re- 
 gulus , having high Protuberances, as alfo a blackiih. 
 Brightnefs like that of the Jead-Ore, and finally by 
 Grains of Lead inherent among the Scoria’s efpeciaily 
 towards the Bottom, in which Cafe the Operation 
 muff be repeated. The laff Cafe fometimes happens, 
 when a red hot Crucible is fuddenly exdnguiflied in 
 Water, or put up in a moift Place. You know 
 from the outward filvery Colour of the Regulus , 
 that the Fire is too great or has lafted too long ; 
 you know it alfo, when the Scoria’s and the Bottom 
 of the Veffel appear covered with a Sort of white 
 and neat Scale, while they are contiguous with the 
 Regulus . The Operation has fucceeded worfe (till, 
 
 when the Regulus appears full of Cavities, when 
 thefe Cavities feem to fhine at the Iniide, with an 
 Intermixture of the Colours of the Rainbow, and 
 when the Litharge has penetrated the Bottom of the 
 Veffel. 
 
 The life and Reafons of the Procefs . 
 
 1. To get Lead out of its Ore, you mull firft fe- 
 parate the heterogeneous Bodies, which make the 
 Lead appear in the State of Ore : Such is the mineral 
 Sulphur, which conftitutes no inconfide table Part of 
 
 U every 
 
290 TJje Art of 
 
 every common Lead-ore. But this may be diiTipated 
 by roafting. {See Part I. § 464.) And as this Ore 
 crackles, the Veil'd muft be covered in the Beginning 
 of the Roafting. However let not the VeiTel grow 
 quite red hot, but only of a dark red Colour: For 
 this Ore eafily grows clammy, and the VeiTel, by 
 Corrofion, adheres To ftrongly to it, that it cannot 
 be taken off without Lofs. This Sulphur may alfo 
 be feparated without roafting, by Filings of Cop- 
 per, when it melts on the Fire: but as fome Lead- 
 ores are charged with a femimetallick and chiefly 
 antimonial Subftance, which muft likewife be fepa- 
 rated from the Lead with Iron, it is better to let the 
 Roafting precede : For Iron mixt with mineral Sul- 
 phur has no Adtion upon a Semimetal *, but joints it- 
 felf only to it ; which we fee from any Fufion of 
 Iron made of crude Antimony, in which the Iron 
 abforbs the Sulphur, and lets the reguline Subftance 
 link to the Bottom. The Fear of thofe is altoge- 
 ther groundlefs, who imagine that Lead is fpoiled 
 by adding Iron to it ; for, there is no Method known, 
 whereby any Particle of Iron can be made to remain 
 in Lead reduced into a metallick Form, as it is 
 conftantly and altogether rejected by it. {See Part 
 L § 42.) 
 
 Nor are you here to have any Regard to the re- 
 fractory Quality of Iron ; becaufe when it melts to- 
 gether with the Subftances which it ought to abforb, 
 it does it as foon as the Flux is added •, and though 
 it fhould not melt, the Lead may neverthelefs be 
 precipitated ; becaufe it does not in this Cafe adhere 
 to the Interftices of the Iron. 
 
 2. But as the Phlogifton is diflipated out of the 
 Ore during the Roafting, there remains a Matter that 
 will turn into Glafs with Fire alone: Therefore, 
 fomething muft be added that may fupply the Place 
 of the Phlogifton, fuch as the black Flux. {Part I. 
 § 93. 162.) To this you muft add moreover Glafs- 
 gall, that will bring to a quicker Fufion the black 
 Flux, -which is refractory enough with regard to the 
 
 Lead , 
 
Assaying Metals. 291 
 
 Lead ; for Glafs-gall melts fo loon as it begins to be 
 flightly red. But the Veffel nmft be clofely fhut» 
 left the Phlogiffon fhould be eafily diffipated ; for 
 Experience has taught, that, in a VeiTel well doled* 
 a Piece of Charcoal, fuch as is the black Flux, can 
 hardly be deprived of its oily Part, on Account of 
 the Adion of the Air’s being hindered : The com* 
 mon Salt that fwims a-top, ferves alfo for the fame 
 Purpofe, as it flops every Way all immediate Com - 
 munication with the external Air. 
 
 3. You are to obferve as to the Regimen of the 
 Fire, that in the Beginning it muff be moderate for 
 a While ; becaufe the Bodies reducible out of Lead, 
 foam very much while they are reduced into a me- ' 
 tallick Form by the Phlogiffon, which you may per- 
 ceive, if you pour a fmall Quantity of Charcoal - 
 Duff, upon Litharge melting foftly in a Teff under 
 the docimaffical Furnace *, and this happens by mix- 
 ing a very fmall Quantity of Phlogiffon ; wherefore 
 you feldom melt Litharge, but it foams and boils 
 with a hilling Moife. For this Reafon, if the Fire 
 is encreafed too much, the calcined Ore, exadly 
 rnixt with a Flux of Charcoal and Salt, rifes into a 
 Foam, makes its Way through the Lute, and the 
 Lead is thus for the moft Part difperfed in Grains. 
 This is prevented, if you make the Fire not very 
 great, till the Redudion is performed : Of this you 
 have a Sign, when the noify Ebullition, which hap- 
 pens during the Redudion, ceafes ; provided it is 
 not occafioned by the Moiffnefs of the Flux. But 
 as this Redudion is performed in a Fire much great- 
 er than is neceffary to melt the Flux itfelf, the boil- 
 ing Matter is mean while retained by the Body ftiil 
 remaining folid, and hinder’d from dilating itfelf to 
 fuch a Degree. Therefore, when the Redudion is 
 at daft made in a great Fire, you no fooner increafe 
 this, but the whole melts, fo that the Lead adhering 
 in Grains in the Flux may be precipitated. Never- 
 thelefs, a too violent Fire is more hurtful, than one 
 continued a little longer than 'it ought to be. For 
 
 U 2 this 
 
2pz The Art of 
 
 this Reafon, a Fire that has a Draught of Air procu- 
 red without Bellows, is preferable for the performing 
 of this Procefs, to a Fire made with Bellows, becaule 
 the Fire may be governed more accurately in the 
 former than in the latter Cafe. It is better to leave 
 the Veffels a little too long in the Fire, than to take 
 them out too foon •, for when the Fire is too flack, 
 there is more of the Lead detained in the Scoria’s 
 than there can be confumed of it, by a proportion- 
 able Excefs of the Fire ; Therefore, unlefs you per- 
 ceive Signs of a very great Excefs, there is no need 
 of repeating the Operation ; whereas the repeating 
 of it is unavoidable, if you find that the Fire has 
 been wanting. 
 
 PROCESS XXXI. 
 
 To reduce and precipitate Lead fmn an Ore rendered - 
 refractory by Pyrites . 
 
 APPARATUS. 
 
 i. OAST two Centners of the Ore, (accord- 
 
 XV ing to Proc. XXX. No. i.) with only this 
 Difference, that you mufl make a Fire a little ftrong- 
 er from the Beginning to the End. The Pyrites, es- 
 pecially that which is merely of Iron, hinders an 
 Ore eafily growing clammy, from turning into large 
 Lumps, or intireLy from melting. Beat the Ore 
 roafled and grown cold to a fubtile Powder, and 
 repeat the Roafting a fecond, and even a third Time j 
 till growing at lalt a little red hot in the Fire, there 
 does remain no Smell of Sulphur at all. 
 
 2. Mix the roafled Ore with fix Centners of black 
 Flux, and with two of Glafs-gall. Do the reft as 
 in the foregoing Procefs *, except that the Fire muft 
 be a little greater and longer continued in the End 
 than if you had a fufible- Ore to fmelc. 
 
Assaying Metals. 2p$ 
 
 The Ufe and Reafons of the Procefs . 
 
 i. If the Ores of Lead are charged with Pyrites, 
 a greater Quantity of the faline Flux, which dif- 
 pofes thefe Earths to a Vitrification, is required, on 
 Account of this refradory Quality, proceeding part- 
 ly from the martial, and partly from the unmetal- 
 lick Earth, and for the fame Reafon the Fire muff 
 be made a little ftronger ; that a fufficient Precipi- 
 tation of the Lead out of them may be made. 
 
 As every Pyrites already contains a martial Earth 
 in it, which is reduced to a metallick Form, when 
 it is melted together with an oily reducing Flux, for 
 this Reafon, this Earth produces here the fame Ef- 
 fect, that was produced by the Ufe of the Iron-fi- 
 lings in the foregoing Procefs *, that is, it becomes 
 capable of purifying Lead from the heterogeneous 
 Bodies mentioned in the fame Place. Nor does it 
 hinder the Degree of the Fire which is ufed for 
 melting the Lead-ore, from being fit to precipitate 
 Iron out of its Ore into a Regulus : For it is enough, 
 provided it returns to its metallick State ; which a 
 middling Fire with fome Phlogifton will efifecl *, for 
 then Iron is already fit for the above-mentioned Pur- 
 pofe. But you are to obferve, that the martial 
 Earth deftitute of Phlogifton, and any Produd of 
 Iron whatever, deprived of Phlogifton, by the vio- 
 lence of the Fire, is not fit to abforb Sulphur, 
 Arfenick, Antimony, and the like ; neverthelefs by 
 joining the Phlogifton to it again, it recovers its 
 former Virtue. You mu ft likewife examine, whe- 
 ther the Pyrites is in a fufficient' Quantity in the Lead- 
 ore ; if not, its Defed muft be fupplied with a lit 
 tie Filings of Iron. 
 
 3. It is neceffary to let a fufficient Roafting pre- 
 ceed ; for Iron, already lato rated with Sulphur in a 
 Pyrites, has not the fame Effect as pure (See Proc . 
 XXX. Ufe No. 1.) Iron. A ftrong Roafting is 
 chiefly required, when the Pyrites are arfenical *, for 
 
 U 3 Arfenick 
 
2c?4 The Art of 
 
 Arfenick is much more fixt, and more ftrongly ad- 
 herent to the Ores, than Sulphur ; nay, when with 
 a black Flux, it turns into a femjmetallick Regulus , 
 which being joined with Lead, a great Part of it 
 molt fuddenly turns into ( Part I. § 73.) Glafs. And 
 as there is but very little Iron in fucha Pyrites; that 
 Iron has not the Virtue of hindering this Effed of 
 the Arfenick. 
 
 4. The Lead which is got out of fuch a pyritofe 
 Ore, is not commonly fo pure as that which proceeds 
 from a purer Ore ; but it is found blackilh and lefs 
 dudile. The Caufe of this Difference is Copper, 
 which lies hidden in leffer or greater Quantity in e- 
 very Pyrites, and which is reduced at the fame Time, 
 and melts with the Lead into one Regulus ; where- 
 fore it mufl be feparated by a particular Eliquation. 
 
 PROCESS XXXII. 
 
 The wajhing of the Lead- ore out of Earths and Stones . 
 APPARATUS. 
 
 i. Hjp H E walking of the Lead-ore is performed in 
 JL the fame Manner, as that of the Silver-ore. 
 ( Proc . XIII.) But take Care not to be deceived by 
 the great Weight of the Ore ; for when it is inclo- 
 fed in a Matrix that is a little hard, the very brittle 
 Lead-ore, on Account of its foliaceous Texture, is, 
 by the frequent Beating of the Peftle, broken into a 
 very thin, fcaly Powder, which fwims in Water, in 
 form of a blew Powder. 
 
 2., If the remaining Ore is rendered pure by the 
 Walking, let it be melted, as in Proc. XXX. If 
 you find it pyritofe and full of Iron, do what has 
 been prefcribed, Proc . XXXI. 
 
 PRO- 
 
Assaying Metals. 29 f 
 
 PROCESS XXXIII. 
 
 T 7 precipitate Lead out of an Ore , rendered refractory 
 hy Earths and Stones , and not wajhahle . 
 
 APPARATUS . 
 
 T A K E of the roafted Ore two Centners beaten 
 into a fubtil Powder, mix them with an equal 
 Quantity of Glafs-gall, the more exa&ly, the better*, 
 add alfo fomething of Filings of Iron, unlefs the 
 Ore be of itfelf pyritous *, then mix the Whole with 
 eight Centners of black Flux, and melt it as in Proc. 
 XXXI. 
 
 The Ufe and Reafons of the Procefs. 
 
 Every thing is already clear from Proc. XXX L 
 There is need here of a very exact Comminution 
 and Mixture, that the Scorification of the Stones 
 mix’d with the Ore, and of the unmetallick Earth 
 may be performed with greater Eafe, and that there 
 may be no Neceflity of promoting it with fo ilrong 
 and fo long a Fire. On this Account alfo a great 
 Addition of the Fluxes, efpecially of Glafs-gall, is 
 required, to facilitate the Precipitation of the redu- 
 ced Particles of Lead through the fufhciently attenua- 
 ted Scoria. 
 
 PROCESS XXXIV. 
 
 To reduce and precipitate Lead out of any of its 0 res 9 
 hy Stratification with Charcoal . 
 
 APPARATUS . 
 
 1. /~'iHUSE for a docimaftical Centner an hundred 
 Half-ounces, or three common Pounds and 
 four Half* ounces, that by this Means each Half-ounce 
 
 U 4 may 
 
t$6 The Art of 
 
 may (land in Lieu of one docimaftical Pound. Beat 
 fuch a Centner of any Lead -ore to a coarfe Powder, 
 the Particles of which muft be about the Size of a 
 Pea*, put it into a large earthen or iron-Frying-pan, 
 and heat it fir ft by a gentle Fire, which muft be in- 
 creafed gradually, that the greateft Part of the Sul- 
 phur may be diffipated. 
 
 2. Have at Hand a melting-Furnace, with a Bed 
 made of Lute and Duft of Charcoal in its bottom- 
 Part deferibed ( Part I. § 239, 240.J; apply to this 
 at the Outfide, another Bed, ( Ibid. Plate III. Fig. 
 1 3 . lett. i.) and join them with Lute, that the Mat- 
 ter running out of the inferior Hole when open, may 
 be received into it *, furround this outward Bed both 
 withfrefh and burning Coals, and fill the Furnace with 
 the fame Fewel that it may be dried *, then with a 
 Pair of Bellows excite the Fire for a Quarter of an 
 Hour ; and then put the Ore into it at feveral Times ; 
 nor will it be amifs to add to it fome Scales * of I- 
 ron. But you muft put the Ore in fuch a Manner, 
 that it may be above the Coals, facing the Hole 
 through which the blaft of the Bellows is admitted 
 into the Furnace : However let it not touch the 
 Walls of the Furnace ; for it is caft upon the Side, 
 where the Hole has been faid to be, the melted Ore 
 in its coming down is cooled by the blaft of the Bel- 
 lows, and the fcorificated Part remains there more 
 refraftory than the Metal itfeJf : it flops the Paffage 
 of the Wind, and hinders it from exciting the Fire 
 freely and equally : If this happens to be the Cafe, 
 you muft remove the Scoria with a Poker, to be in- 
 troduced through the oblong Aperture of the (Plat. 
 III. Fig. 10. lett. c.) Bottom-part. In the mean 
 Time while the Ore is put into the Fire, the Fur- 
 nace muft be filled, two thirds at leaft, with Coals 
 of a middling Bignefs, and after each Portion of the 
 Ore is put in, add a larger of Coals above it. 
 
 * as flake off from Iron red hot, while under the Strokes of 
 
 a Smith’s Hammer, 
 
 3. When 
 
Assaying Metals. ryy 
 
 3. When all the Ore is put into the Fire, conti- 
 nue to blow till the Fire is confumed in the Furnace, 
 Pour Water upon the foremoft-Bed, Drop by Drop, 
 to cool the Lead gathered in it. Look alfo into the 
 Scorias, to fee whether there are any Grains of Lead 
 difperfed among them ; if you find it to be fo, beat 
 the Scorias, and wafh the fmalleft Particles off with 
 Water, that you may have the Lead feparate. Fi- 
 nally, weigh this intirely: and the Weight will an- 
 fwer to that which the Smelter will at lafl have. 
 
 The JJfe and Reafons of the Procefs . 
 
 1. The Lead is reduced in this Procefs by its im- 
 mediate Contad with the Coals ; that is, the oily 
 Part of the latter being agitated by a great Fire, 
 and intirely extorted, penetrates the fmall vitrefcent 
 metallick Particles, which being open by the Violence 
 of the Fire run down through the Interfaces of the 
 burning Coals, which, in the foregoing Proceffes, 
 was effeded by the black Flux in clofe Vefiels. 
 
 2. But this Method is preferable to the foregoing, 
 except that the Apparatus is attended with greater 
 Trouble. For when the Redudion is finifhed, the 
 Lead colleded in the Bed of the bottom Part, runs 
 thence into the outward or foremoft Bed : there it is 
 preferved by a much gentler Heat, under the burn- 
 ing Coals that fupply it perpetually with a Phlogi- 
 flon, and leaves its remaining Impurity. But take 
 Care in this Operation, if you have a mind to make 
 your Experiment with many common Pounds 
 Weight, not to put too much at a Time to be re- 
 duced ; for, if you do this, you will not make a fuf- 
 ficient Redudion, and the Fire is in feme Meafure 
 fuftocated. Nor muft you put the roafted Ore into 
 the Fire, before the Furnace and the Beds are well 
 dried and made red hot on the Infide; for in this 
 Cafe you will find Grains of Lead difperfed among 
 the Scoria’s. The fame ufes to happen, if the Ore 
 is melted crude, or at lead: not diffidently roafled : 
 for, the Sulphur which adheres in great Quantity to 
 the Lead-ore, is hardly diffipated, and not feparating 
 
 quickly 
 
2^3 The Art of 
 
 quickly from the Scoria’s, the Metal is rendered re- 
 iraftory and brittle. Befides let the Bellows not be 
 loaded with too great a Weight , for this defhrudi- 
 ible Metal is partly confumed by the too great Vi- 
 olence of the Fire ; efpecially when too impetuous 
 an Adion of the Air is joined to it. Let the No- 
 fel of the Bellows not be too narrow ; that a fuffici- 
 ent blaft may be admitted : Nor is it always poffible 
 to compenfate this Narrownefs by a greater Weight ; 
 for if you load the Bellows to an Excefs, it has been 
 found by Experience, that the Fire is thereby rendered 
 equal, and even diminifhed. 
 
 3. Gold and Silver may be reduced out of the 
 Drofs, and united with Lead by this Method *, if 
 you add to them the vitrefcent Drofs of Lead, fuch 
 as is Litharge, and all the Calx of Lead, and the 
 Things in which they lie hidden in this Manner, or 
 even the Lead-ores themfelves. For allthefe Things, 
 when they have recovered their Phlogifton, are re- 
 duced into a metallick State, they abforb the Gold 
 and Silver out of their Drofs, and render the refrac-. 
 tory Scoriae fufible and foft. But the Lead thus got 
 may be again feparated in a large Teft, or even be 
 ufed to purify fome other Gold or Silver, fo that the 
 Metal which is already in the Lead, may be added to 
 them. See Proc . X, XL 
 
 PROCESS XXXV. 
 
 Lhe Separation of Lead from Copper , by Eliqiiation 
 (Part I. § 468.) 
 
 W HEN Lead has fomething of Copper in it, 
 it is thereby rendered lefs dudile, and 
 when broken, the Surface of it appears as it were 
 granulated, if the Quantity of the Copper is but very 
 little increafed ; on the other Hand, when itsTough- 
 nefs makes it cohere, if you break it, it looks like a 
 Heap of acute prifmatical Particles. Finally, if there 
 is a great Quantity of pure Copper in it, it looks 
 
 reddifh 5 
 
As s-A y x n g ■ Metal s. 299 
 
 reddifh ; but if it is mixt with Sulphur, it looks 
 blackifh, and is very brittle : But the fame Effect is 
 produced by the femi-Metals, as by Sulphur and 
 Arfenick. Neverthdefs, the Separation of the two 
 latter has already been made in the foregoing Pro- 
 cefs ; but the Copper muff be feparated by a peculiar 
 Apparatus. 
 
 APPARATUS. 
 
 1. Make with Lute and charcoal-Duft a Bed, the 
 Capacity of which muff be proportioned to the 
 Quantity of the Mixture of Lead and Copper to be 
 feparated. But let this Bed be very low, and decline 
 mg forward towards the lower Part. Let there be a 
 fmall narrow Channel, running from the Bottom of 
 the Bed, to the other Bed which is contiguous to the 
 fore-Part of the Former, and placed a little lower. 
 In the Place where this Channel leads out of the End 
 of the upper Bed *, put a fmall iron- Plate, and prefs 
 it acrofs the Channel ft ill moift ; in fuch Manner, 
 that there remains only a fmall PafTage at the Bottom 
 of it, through which the melted Lead may run 
 flowly. Dry the whole well, by putting red burn- 
 ing Coals thereon. 
 
 2. Put the Mixture of Copper and Lead into the 
 upper-Bed : Make in both Beds, with Wood or 
 Charcoal, a Fire gentle enough that it may only bring 
 the Lead to a Fufion : This being melted by Degrees 
 and flowly, will run through the narrow Paffage left 
 between the fmall iron-Plate and the Bottom of the 
 fmall Channel, and will be collected into a Regulus , 
 in the lower Part of the foremoft Bed. If nothing 
 more runs with this Fire, make it a little ftronger, 
 till the Bed grows dark red-hot : Continue the Fire 
 thus for fome Minutes ; and then put it out. 
 
 3. You will find the Lead collected in the inferior 
 Bed ; but the Copper that was in the Mixture, will 
 remain in the upper-Bed, with a little Lead adhering 
 to the Outfide of it \ whence it has the Colour of it, 
 
 and 
 
300 The Art ^ 
 
 and is full of Pores ; and if the Copper is not % 
 quarter or a fifth Part lefs than the Portion of Lead, 
 and the Fire has been made gentle and flow, you 
 will find that it has intirely preferved the fame 
 Figure, which the Mixture had before the Eli- 
 quation. 
 
 4. Find the Weight of the Copper with a Ba- 
 lance, and put the whole, or the melted Part of it, 
 intoaTeft, or, if you are only willing to try it, put 
 it into a fmall Coppel well heated, and fufficiently 
 hot, till the Lead is intirely confumed, and the Cop- 
 per remains motionlefs : Then take it out immedi- 
 ately, and extinguifh it in Water. You will find the 
 formerWeight of the tried Specimen diminifhed : But 
 the Part of it which is deficient, will be the Lead de- 
 ft royed : And as Lead mixt in fmall Quantity with 
 Copper, confumes about the fifteenth Part of the Cop- 
 per, with regard to itfelf j for this Reafon, you 
 muft add the fifteenth Part of the deficient Weight 
 to the remaining Copper, that you may have the 
 Portion of Copper, which has been left by the Lead 
 in the upper (N°. 2.) Bed. Thence you may eafily 
 calculate, how much Copper may be feparated from 
 Ixad. If you put the melted Lead into a Coppel, 
 you will find not only the Portion of Gold and Sil- 
 ver which was in the Mixture, and which the Lead 
 has carried away with it ; but you will know alfo, 
 from the pure fulphureous yellow Colour of the 
 Coppel, or from its greater or lefs Blackifimefs, 
 whether nothing, or a little, or a great Quantity of 
 the Copper has vanished with the Lead ; though you 
 cannot however, from this, precifely determine the 
 exad Quantity of it. 
 
 The Ufe and Reafons of the Procefs. 
 
 1. Lead, when it is not more -hot than only 
 enough to be in fufion, does not diiTolve Copper : 
 Whence Lead may be melted in a copper-Veflel, 
 when you do not exceed this Degree of Fire: But, 
 
 fo 
 
Assaying Metals. 301 
 
 fo foon as the Lead begins to grow white, to fmoak 
 and boil, it foon diffolves Copper : Therefore, you 
 are to take Care, that the Fire be not too violent, 
 efpecially in the Beginning. But the mofl fi tuple 
 Operation of the Eliquation, is that which is per- 
 formed without any Addition. 
 
 2. The fmall iron-Plate is applied, to the End 
 that, in cafe a few fmall Particles of Copper fhould 
 go off, thefe fwimming atop may be ftopt there, 
 and the Lead run as it were through the narrow low 
 Paffage left, as through a Sieve, while thefe Parti- 
 cles of Copper remain. 
 
 PROCESS XXXVI. 
 
 To reduce and precipitate Copper out of a pure andfufi - 
 ble Ore, in a clofe Veffel. 
 
 APPARATUS. 
 
 1 ^yrlX one, or, if you have fmall Weights, 
 1Y1 two docimaftical Centners of Ore beaten 
 extremely fine, with fix Centners of the black Flux, 
 and having put them into a Crucible or a Pot, cover 
 them one half-inch high with common Salt, and prefs 
 them down with your Finger : But let the Capacity 
 of the Veffel be fuch, that it may be only half-full; 
 fhut the Veffel clofe ; put it into the Furnace, and 
 make the Fire as in Proc . XXX. 
 
 2. Increafe the Fire {lowly, till you hear the com- 
 mon Salt put upon the Ore crackle : Then increafe 
 the Fire immediately, either with the Funnel and 
 Cover put upon the Furnace, or with a Pair of Bel- 
 lows applied to the Hole of the bottom-Part, that 
 the Velfel may grow very red hot. Thus you will 
 precipitate and reduce your Copper in about a Quar- 
 ter of an Hour: Then take out the Velfel, and 
 ftrike with a few Blows the Pavement upon which 
 you put it, that all the fmall Grains of 'Copper may 
 be colle&ed in one Mafs. 
 
 3. Break 
 
302 The Art of 
 
 3. Break the VefTel, when grown cold, in two, 
 from Top to Bottom, as neatly as you can : If the 
 whole Procefs has been well performed, you will find 
 a Solid, perfectly yellow, and malleable Regulus^ ad- 
 hering to the Bottom of the VefTel, with Scoria’s, re- 
 maining atop of a brown Colour, folid, hard, and fhin- 
 ing, from which the Regulus muft be feparated with 
 federal gentle Blows of a Hammer ; this done, 
 weigh it, after having wiped off all Filthinefs. 
 
 4. A foft, dufty, and very black Scoria, is a Sign 
 of a Fire not fufficiently ffrong. Small neat Grains 
 of Copper reduced, but not precipitated, and adher- 
 ing ft ill to the Scoria’s, efpecially not very far from 
 the Bottom ; and an unequal and ramificated Regulus , 
 are Signs of the fame Thing. A folid, hard, Alin- 
 ing, red-coloured Scoria, efpecially about the Regu- 
 lus , or even the Regulus itfelf when covered with a 
 like fmall Cruft, are Signs of an Excefs in the De- 
 gree and Duration of the Fire. 
 
 ‘The life and Reafons of the Procefs . 
 
 1. You may confult what has been faid in 
 Proc. XXX. Uf N°. 1, 2. But all the Ores which 
 are ealily melted in the Fire, are not the Objedts of 
 this Procefs ; for they muft alfo be very pure. Such 
 are the vitreous copper- Ores, but efpecially the green 
 and azure coloured- Ones, and the cceruleum & viride 
 Montanum (Part I. § 363—366.) which is not very 
 different from them. But if there is a great Quan- 
 tity of Sulphur, Arfenick, or of the Ore of another 
 Metal or iemi-Metal joined to the Ore of Copper, 
 then you will never obtain a malleable Regulus of pure 
 Copper •, though Ores are not always rendered re- 
 fractory by the Prefence of thefe. 
 
 P R O- 
 
Assaying Metals. 303 
 PROCESS xxxvir. 
 
 fo reduce and precipitate Copper out of Ores fProc. 
 XXXVI.) rendered refractory by Earth and Stones 
 that cannot he wajhed off. 
 
 A P PARA F U $. 
 
 1. yj E AT your Ore into a mod fubtil Powder, of 
 JJ which weigh one or two Centners, and mix 
 as much glafs-Gall to them : This done, add like- 
 wife four Tirnes as much of the black Flux, with re- 
 fpedt to the Ore : For, by this Means the fteril ter- 
 reftrial Parts are better difpofed to a Scorification, 
 and the reducing and precipitating Flux may adb 
 more freely upon the metallick Particles freed of 
 all their Incumbrances. 
 
 2. As for the reft, make the Apparatus accord- 
 ing to Proc. XXXVI ; but you muft make the Fire 
 a little ftronger for about half an Hour together. 
 When the VefTel is grown cold, and broken, exa- 
 mine the Scoria’s, whether they are as they ought 
 to be : The Regulus will be as dudlil and fine as the 
 foregoing. 
 
 SChe JJfe and Reafons of the Procefs. 
 
 1. Every Thing has been already explained in 
 Proc. XXXIII : But as fuch copper-Ores hardly con- 
 ceal any Sulphur and Arfenick in them, the Roafting 
 would be of no EfFedt, and a great Deal of Copper 
 would be loft : For mo metallick Calx, except thofe 
 of Gold and Silver, improperly fo called, can be 
 roafted, without you find a Part of the Metal loft 
 after the Reduction : But the Stones which here are 
 fuppofed not to be elutriable, cannot be feparated 
 by Fire alone : See Part I. § 33 $. 
 
 P R G- 
 
3°4 
 
 The Art of 
 
 PROCESS XXXVIII. 
 
 To precipitate Copper out of an Ore (Proc. XXXYII.) 
 that contains Iron. 
 
 APPARATUS. 
 
 i. T^O all according to Proc. XXXVII. But 
 1 J you will find, after the Veffel is broken, a 
 Regains upon no Account fo fine, but lefs dudtile, 
 wherein the genuine Colour of the Copper does not 
 perfectly appear, and which muft be further 
 purified. 
 
 The Ufe and Reafons of the Procefs. 
 
 The Fire ufed in this Operation, is not quite fo 
 flrong, as that the Iron may turn to a Regains : But as 
 Copper is the Menftruum of Iron, which is of itfelf very 
 refractory in the Fire \ for this Reafon, while the 
 Ore and the Flux are moll intimately mixt and con- 
 founded by Trituration, the greatefl Part of the Iron 
 being diffolved by the Copper, turns into a j Regains 
 along with it. 
 
 PROCESS XXXIX. 
 
 The roafting of a pyritofe , fulphureous , arfenical , femi- 
 metallic ! , copper -Ore. 
 
 APPARATUS . 
 
 i.TjREAK two docimaftical Centners of the 
 13 Ore to a coarfe Powder, put them into a 
 Teft covered with a Tile, and place them under the 
 Muffe! of the docimaftical Furnace : But the Fire 
 muft be fo gentle, as that the Muffel may be but 
 very faintly red hot. When the Ore has decrepi- 
 tated, .open the Teft, and continue the Fire for a 
 
Assaying Metals. 30 j 
 
 Few Minutes ; then increafe it by Degrees, that you 
 may fee the Ore perpetually fmoaking a little : In the 
 mean Time it is alfo proper, now and then to ftir 
 it tip with an Iron-hook: The fbining Particles will 
 affume a dark red or blackifh Colour: This done, 
 take out the Tell, that it may grow cold 3 if the 
 fmall Grains are not melted, nor ftrongly adherent to 
 each other, hitherto all is well 3 but if they run into 
 one fingle Cake, the Procefs muft be made again with 
 another Portion of the Ore, in a more gentle Fire. 
 
 2. When the Ore is grown cold, beat it to a Pow- 
 der fomewhat finer, and roaft it by the fame Method 
 as before ; then take it out, and if the Powder is not 
 melted yet, beat it again to a moft fubtil Powder 3 
 in this, you are to take care that nothing be loft. 
 
 3. Roaft the Powder a fecond Time in a Fire 
 fomewhat ftronger, but for a few Minutes only : If 
 you do not then find the Ore any Way inclined to 
 melt, add a little Tallow, and make it burn away 
 tinder the Muffle, and do the fame another Time 
 again, till the Fire being very bright, you no longer 
 perceive any fuiphureous, arfenical, unpleafant Smell, 
 or any Smoak 3 and there remains nothing but a thin s 
 foft Powder, of a dark red, or blackifh Colour, 
 
 The Ufe and Reafons of the Procefs . 
 
 1. Every Pyrites contains Iron, with an unmetal- 
 lick Earth : To which Sulphur or Arfenick, and 
 moft commonly both, (Part I. §316, 323, 347, 369, 
 371.) always join. Bejfides, there is Copper in many 
 Pyrites, but, fometimes more, fometimes lefs : Some 
 of them (ibid.) are altogether deftitute of Copper, 
 Therefore, fo much as Pf rites differ with Regard to 
 the Proportion of their conftituent Particles, fo much 
 do they differ as to their Difpofition in the Fire. 
 For inftance, the more Copper there is in a Pyrites, 
 the more it inclines to Colliquation. The more Sul- 
 phur and Arfenick it has in it, the more quickly the 
 melting of k is procured, and the Reverfe : The 
 
 X more 
 
3 06 The Art of 
 
 more Iron and unmetailick Earth it contains, the 
 more it proves refra&ory in the Fire./ Now, if fuch 
 Pyrites melt in the Roading, as happens to fome 
 of them, if they grow but a little red-hot, the Sul- 
 phur and Arfenick that lyes hidden therein, are fo 
 dridtly united with the fixtPart, that you would in 
 vain attempt to diffipate them: Nay, in this Cafe, 
 when it is reduced again into a Powder, it requires a 
 much greater Time, and Accuracy in the Regimen of 
 the Fire, to perform the Operation. For this Rea- 
 fon it is much better to repeat it with new Pyrites. 
 But you can road no more than the double Quan- 
 tity at once of the Ore, you have a Mind to im- 
 ploy in the foregoing Experiment : to the End that 
 the Precipitation by Fufion not fucceeding, there 
 may remain dill another Portion intire *, led you 
 fhould be obliged to repeat a tedious Roading : If 
 you fee the Signs of a ferreous refractory Pyrites, the 
 Operation mud be performed with a greater Fire, 
 and much more quickly. However, take Care not 
 to do it with too violent a Fire : For a great deal of 
 Copper, is confumed not only by the Arfenick, but 
 alfo by the Sulphur, and this happens even inVeflels 
 fhut very dole, when the Sulphur is expelled by a 
 Fire not quite fo drong: Which a reiterated and 
 milderSublimation of the Sulphur, in aVelfel both very 
 clean and well clofed, will clearly fhew. 
 
 2 . When the greated Part of the Sulphur and the 
 Arfenick is diflipated, by fuch Caufes as promote 
 Colliquation, you may make a dronger Fire: But 
 then it is proper to add a little of fome fat Body ; 
 for this didolves mineral Sulphur, it changes the 
 Mixture of it in fome Part, which for Indance con- 
 fids in a certain ProportiorP of Acid and Phlogidon, 
 and at the fame Time hinders the Metallick Earth to 
 be reduced into Copper, from being burnt to an Ex- 
 cels. From thefe Effe&s the Reafon is plain, why 
 Adayers produce lefs Metals in the trying of Veins 
 of Copper, Lead, and Tin, than lkilful Smelters do 
 in large Operations, For, the former perform the 
 
 Roading 
 
Assaying Metals. 307 
 
 Roafting under the Muffle, with a dear Fire, and 
 without an oily reducing Menftruum ; whereas the 
 latter perform it in the Middle of Charcoal or of 
 Wood, which perpetually emit a redu&ive Phlogifton. 
 
 3. The darker and blacker the Powder of the 
 roafted Ore appears, the more Copper you may ex- 
 pect from it : But the redder it looks, the lefs Cop- 
 per and the more Iron it affords : For roafted Cop- 
 per dilfoived by Sulphur or the Acid of it, is very 
 black ; and Iron, on the contrary, very red. 
 
 4. If a pure Copper-Ore lyes hidden, together with 
 Ores of other Metals or femi-Metals, full of Sulphur 
 and Arfenick, in one and the fame Glebe, that can- 
 not be feparated with the Hand, it muft be roafted: 
 For, while the Copper is reduced and precipitated to- 
 gether with thefe other Metals, it participates of their 
 Sulphur and Arfenick ; - wherefore, it is the fame as 
 if the Ore of the Copper itfelf had been defiled by 
 them. 
 
 PROCESS XU 
 
 The Precipitation of Copper out of roajled (Proc. XXXIX,} 
 
 Ore . 
 
 APPARATUS . 
 
 D ivide the roafted Ore into two Parts : Each of 
 them fhall go for a Centner : add to it the 
 fame Weight of Glafs-Gall, and four Times as much 
 of the black Flux, and mix them well together : As 
 for the Reft, do all according to Proc. XXXVIII 
 The precipitated Regulus will be half-malleable, 
 fometimes quite brittle, now and then pretty much 
 like pure Copper in its Colour, but fometimes whit- 
 ifh, and even blackifh : Whence it is moft commonly 
 called black Copper (in German Ikttpfer) % 
 
 though it is not always of Jo dark a Dye. 
 
308 The Art of 
 
 ‘The Ufe and Reafons of the Procefs . 
 
 1 * It is eafy to conceive, that there is as great a 
 Difference between the feveral. Kinds of this Metal 
 called black Copper, as there is between the pyri- 
 tofe and other copper-Ores, accidentally mixt with 
 other metallick and femi-metallick Bodies. For, all 
 the Metals, the Ores of which are intermixed with 
 the copper-Ore, being reduced are precipitated to- 
 gether with the Copper •, which is brought about by 
 Means of the black Flux. Wherefore, Iron, Tin, 
 Lead, the reguline Part of Antimony, and Bifmuth, 
 moft commonly are mixt with black Copper, in a 
 Multitude of different Proportions. Nay, it is felf- 
 evident that Gold and Silver, which are diffolvable 
 by all thefe Matters, are collected in fuch a Regains , 
 when they have been firft hidden in the Ore. Befides, 
 Sulphurand Arfenick are not always altogether abfent. 
 For they can hardly be expelled fo perfe&ly by the ma- 
 ny preceeding Roaftings, but there remain fome Vefti- 
 ges of them, which are not diffipated by a hidden 
 Melting, efpecially in a clofe Veffel, wherein the 
 Flux fwimming a-top hinders the Adlion of the Air. 
 Nay, Arfenick is rather fixt by the black Flux, and 
 affumes a reguline femi-metallick Form, while it is at 
 the fame Time preferved from diffipating, by the Cop- 
 per. But, the Variety of the Colours, of the Con- 
 fidence, and even of the Goodnefs of black Cop- 
 per depends on this. 
 
 P R Ot 
 
Assaying Metals. 309 
 
 PROCESS XLI. 
 
 The running down of Pyritofe , crude ^ Copper-ore , into 
 a rough , brittle Regulus, by a Stratification with 
 Charcoal . 
 
 APPARATUS . 
 
 1. H USE a Weight of as many common half- 
 Vi Ounces for a docimaftical Centner, as there 
 are Pounds in a large Centner, that each half-Ounce 
 may reprefent a common pound Weight ; weigh in a 
 large Balance one or many Centners of crude Ore 
 not rcafted, and broken in fmall Pieces of about the 
 Bignefs of a Pea, Let the melting Furnace have a 
 frefh Bed, and be altogether difpofed as in Proc a 
 XXXIV. N°. 1. and Part I. § 239, 240. Stop 
 with the fame Lute which the Bed is made of, the 
 Hole of the Bottom-part, through which the Body 
 melted may run from the inward into the outward 
 and foremoft Bed, When the Furnace and both 
 Beds are well dried and made white hot within, put 
 the Ore into them at fevera .1 Times; meanwhile 
 let the Furnace be conftantly kept full of Coals, 
 and the Bellows blow very ftrongly at the fame 
 Time; let the Nofel of thefe be direfted obliquely 
 downwards, that it may determine the Flame to- 
 wards the Surface of the inward Bed, and of the 
 Matter which is melted in it, to make it keep in a 
 State of Fufion : All which Particulars mult be ob- 
 lerved more exactly than in Proc. XXXIV. N°. 2. 
 becaufe of the refradlory Scoria. But if you know 
 from the outward Appearance of the Ore, or from 
 the Experiment already made before, that this Ore, 
 or the Scoria which will be produced out of it, is of 
 a refractory Kind ; it is proper that you fhould add a 
 fufible Scoria, that has already born the Fire feveral 
 Times, and is well tried that nothing of any Metal 
 can be reduced out of it, of which you cannot de~ 
 
 X 3 termine 
 
310 The Art of 
 
 termine the Proportion with Regard to the Ore* 
 otherwife than by Trial. 
 
 2. When you have put one Centner of the Ore 
 into the Fire, continue the Fire, till you can judge 
 that all the Ore is collected into the Bed: Try with 
 an Iron-poker, which you are to introduce into the 
 Bed through the oblong Hole of the Bottom-part, 
 whether all the Ingredients are melted ; efpecially if 
 the Scoria’s are melted thin enough, or have a pitchy 
 Confiftence ; for, they mult be fetched fuch out of 
 the faid Hole with the Poker, left the Inferior Aper- 
 ture, through which the melted Matter is conveyed 
 into the outward Bed, fhould be obftruCted. Then, 
 with an iron Rod cutting at one of its Ends, open 
 the Hole that is ftopt with Lute; that the melted 
 Matter may run out into the hot foremoft Bed. Now, 
 if you have a Mind to melt many Centners of your 
 Ore ; remove from the Hole the fmall Coals, or the 
 tenacious Remains of the Scoria’s ; and flop it with 
 frefh Lute : This done, take the hardened Mafsout of 
 the fore-moft Bed, with a Pair of Tongs : Then you 
 may, in the fame Manner, put into the Fire, melt, 
 and convey into the foremoft Bed, another Centner of 
 your Ore. 
 
 3. When all the Ore you intended, has paft 
 through the Furnace, and the Fire is confumed, 
 and the Furnace grown cold, break the Beds ; that 
 you may colied: what has been infinuated into the 
 Chinks, which they poftibly have contracted during 
 the Operation. Likewife, examine clofely the broken 
 Scoria’s, that you may fee whether any Thing of the 
 reguline Part has been detained therein: This muft 
 be feparated either with the Eland, or by wafhing ; 
 and examined in the Balance together with the Re- 
 gulus collected in the outward Bed, which is purged 
 of all Scoria’s. But, the Regulus in which the Metal 
 lyes ftill hidden in its State of Ore, will be very 
 brittle. 
 
 fbe 
 
Assaying Metals. 311 
 
 ne Ufe and Reafons of the Procefs . 
 
 1. In this Fufion, the Ore melts on Account of too 
 fudden an Application of the Fire 5 for this Reafon 
 it lofes its Sulphur and Arfenickonly in a fmall Quan- 
 tity (Proc. XXXIX. uf. N° 1.) the Reft joins more 
 ftridly with the fixt Subftance of the Ore. Therefore, 
 as Iron, which abounds in every Pyrites, feparates 
 the Sulphur and Arfenick from all the other Metals 
 and femi-Metals, and unites them to itfelf ( Part , I. 
 § 147. coroll. 1.) ; on this Account thefe heavy Bo- 
 dies fink to the Bottom, and the Iron, freed of Sul- 
 phur and Arfenick, fwims a-top, together with the 
 unmetallick Earth. But this Separation does not fuc- 
 ceed fo perfectly, but there remains fomething of the 
 Iron and of the unmetallick Earth in the Regulus^ 
 and fome Copper in the Scoria’s; The Reafon of this 
 
 is, that the Iron which is in the pyritofe Ore is not 
 
 fufficient to abforb all the Sulphur and Arfenick, and 
 that by Means chiefly of the Arfenick, which, toge- 
 ther with the Metals, turns to a reguline femi-metal- 
 lick Subftance, Part of this fubtil Earth remains joined 
 to the Regulus . This Regulus is called Lapis Cupri^ 
 
 in German Ikltpfgrff ettt, becaufe it has hi- 
 
 therto preferved the Nature of the crude Pyrites. 
 
 2. But every pyritofe Copper-Ore muft not be made 
 to go through this rough Melting ; but only that 
 which has a great Deal of iron and a little Copper in 
 
 it. For, the Reafon why the melting is done here 
 without a previous Roafting, is, (1.) that the Iron may 
 be feparated from the Copper ; which is performed 
 like a Precipitation by Fufion, through the Adion 
 of the Sulphur upon the Iron (N° 1.) : Nor could the 
 Separation of fo much Iron from the Copper be 
 made with any Benefit by another Method. (2.) That 
 the melting may be performed conveniently : For if 
 an Iron-pyrites is deprived of its Sulphur by roafting, 
 it is hardly tradable by Fire alone, on Account of 
 the refradory Nature of the martial Earth: This may 
 
 X 4 be 
 
31Z The Art of 
 
 be obferved in any Iron-ore, though it be ever fo fu- 
 fible in its kind*, becaufe it wants a far more violent 
 Fire to be melted, than any other Ore whatever,, 
 Nay, it is proper alfo here to ufe an unmetallick Earth, 
 altogether unfufible by itfelf, which enters in greater 
 Quantity into the Compofition of the Pyrites, as it 
 contains a leffer Quantity of Copper. But both thefe 
 are freed, by a violent Fire fuddenly applied to them, 
 from the Sulphur which is in fome Meafure fixed in 
 the Pyrites, and cannot evaporate very quickly *, and 
 the Iron is at the fame Time feparated from the Cop- 
 per, and thus the Copper is freed from Sulphur, by 
 Means of Iron, and reciprocally from Iron, by Means 
 of Sulphur. 
 
 3. By the fame Method, you will obtain Silver, 
 Gold, and Copper, if the Ores in which they lie 
 hidden, are difperfed among a great Quantity of Stones 
 and Pyrites, which admit oi no Walking *, nor can 
 the Metal be feparated therefrom with Benefit, by 
 any other Method hitherto known : for Inflance, 
 after fuch an Ore has been beaten to a coarfe Pow- 
 der, if there is not already a fufficient Quantity 
 of yellow fulphureous Pyrites in it *, you mull chufe 
 fulphureous Iron-pyrites, and even among thofe you 
 have at hand, thole that contain the greatefl Quan- 
 tity of Silver, Gold, and Copper j for by this Means 
 you obtain in one fingle Operation, and at the fame 
 Expence, the abovefaid Metals, which fome times 
 cannot be fetched with Benefit out of the Pyrites, 
 by a particular Procefs. You mull add fufible Scoria’s 
 to thefe Ores and Pyrites, efpecially thofe that re- 
 main of the Melting of lead- Ore, and thofe chiefly 
 out of which a littleLead may Hill be fetched ; or even 
 the very Ore of Lead itfelf: Nay, fome other addi- 
 tional Ingredients too, that are eafy to be melted ei- 
 ther of their own Nature, or at leafl: by the Me- 
 thods here prefcribed, and the Quantity and Choice 
 ot which can hardly be determined with Certainty, 
 otherwife than from a long Experience in thefe Mat- 
 ters, by Experiments, and a great Attention to every 
 
 Circum fiance 
 
Assaying Metals. 315 
 
 Circumftance. All thefe Things pafs through the 
 Furnace, whence proceeds a Regulus , in which Gold, 
 Silver, Copper, and Lead are concentrated, but in 
 a rough Manner (N° i.) : However, the Lead which 
 chiefly receives the Gold and Silver, is fometimes 
 colle&ed into a Regulus by itfelf, and gets to the 
 lower Part of the Bed, with an Abundance of 
 Scoria’s. 
 
 4. The Precipitation of the Ore out of the fcori- 
 flcated Stones, mud be chiefly attributed to the Py- 
 rites in the Procefs, For the Martial Earth which is 
 in the Pyrites, leaves its Sulphur in the very Begin- 
 ning, when the Fire begins to ad ; and this Sul-, 
 phur being agitated by fo great a Fire, carries away 
 a great many metallick Particles, efpecially of Iron 
 (Proc. XXXIX. ufN°. i.): Therefore, both thefe, 
 which are found every where, the Stones, that conceal 
 Ores and are intermixt with them, being broken final], 
 diflolve and penetrate them, and difpofe them to a 
 Scoriflcation ; which happens the more conflantly, 
 becaufe Sulphur is fo ftrongly fixed by iron Particles 
 adherent to it, that it cannot evaporate very quickly, 
 though it is expofed to ever fo violent a Fire. The 
 other Part of the Martial Earth turns to a Scoria, 
 which, by adding Scoria’s that contain Lead, and 
 other fufible Matters, diflolves the Stones intirely, 
 and bring them to a Fufion. Then the Ores get free 
 therefrom, and are precipitated •, and their remaining 
 Part of martial Earth being reduced to a metallick 
 State, abforbs a little of the Sulphur and Arfenick : 
 On this Account the Metals are concentrated into a 
 folid weighty Regulus , to which a great Quantity of 
 the reduced Iron mixes. Therefore you are to make 
 the following Obfervations concerning this Proeefs. 
 (1.) That Sulphur is neceflarily required, and that 
 the above-mentioned Operations are performed by the 
 Concurrence of it, is very plain, becaufe the Pyri- 
 tes deftitute of Sulphur is not capable of affifiing the 
 Scoriflcation, but is rather an Obftacle to it, by its 
 refractory Quality. (2.) That Iron is not only of a 
 
 fcorifying 
 
314 The Art of 
 
 fcorifying, but alfo of a precipitating Nature, fince 
 it abforbs Sulphur and Arfenick : For a Scorification 
 maybe performed by the lead-Ore, or its Scoria, and 
 by adding other Fluxes : But the greateft Part of the 
 Lead is retained in the Scoria’s, together with the 
 metallick Part inherent in the Ores, when a Pyrites 
 containing Iron is wanting : Nay, Lead itfelf, can- 
 not be fufficiently, and fometimes not at all precipi- 
 tated out of its Ore, and rendered pure, without the 
 Affiftance of Iron. (3.) A too great Quantity of Ar- 
 fenick is hurtful here, and for the moil Part hardly re- 
 ducible into Glafs, on Account of its Rapacioufnefs, 
 and of the Deflrrudlion of the Lead {Part I. § 73.) But 
 a great Deal of the Arfenick is alfo fixt with metal- 
 lick and unmetallick Earths, and is mixt with both 
 of them : Whence very coarfe Regains’ s are produced 5 
 the Scoria’s, on the contrary, retain a great Deal of 
 the Metal: Thence are alfo produced femi-arfe- 
 
 nical Subftances, that are diftindt from the Scoria’s 
 and the Regains , containing chiefly Copper and Iron ; 
 which are called by the German Metallurgifts Ikujte 
 f txAt% y when they contain a great Quantity of Cop- 
 per with Iron ; but are called by the fame, 
 
 when they confifl: only of Iron and Arfenick : Thefe 
 have much of the unmetallick Earth in them: 
 
 PROCESS XLII. 
 
 The melting of Pyritofe crude Copper-ore , in a clofe Vejfel , 
 to make a Regulus like that of Proc. XLL 
 
 APPARATUS. 
 
 lTAKE two Centners of the fmall docimaftical 
 A Weight of that Ore not roafted *, beat them to a 
 fine Powder, mix them with twice or thrice as much 
 of pulverifed common Glafs, which you are to have 
 at Hand, and which mult be very fufible : Or, in- 
 flead of this ufe Scoria’s altogether deftitute of a me- 
 tallick reducible Earth, and eafily melting in the 
 
 Fire* 
 
Assaying Metals. 315 
 
 Fire. Put them into a Crucible or Pot ; and cover 
 them over with common Salt, fhutting the VefTei 
 clofe with a Tile, and Hopping the Joints with 
 Lute. 
 
 2. If thefe Things melt in the Wind-furnace, by 
 Means of a violent Fire, you will find at the Bottom 
 of the VefTei a Regulus like that of Proc . XLL 
 
 The Ufe and Reafons of the Procefs. 
 
 1. No fulphureous Ore that has not been 
 roafted, ought to be melted by adding to it an al- 
 caline Flux : For, fixt Alcali together with mine- 
 ral Sulphur, turns to a Body, called Hepar Sulphurise 
 which retains in it diffolved metallick Bodies 
 (Parti. § 149.) : For this Reafon, if you melt in the 
 Fire an Ore containing a great Deal of Sulphur, or 
 of the Acid of it, with a black or a white Flux of 
 an alcaline oily Nature ; you either have no Regulus 
 at all, or at leaft the greateft Part of it is detained 
 in the Scoria’s, that is, according as there is in the 
 Ore a greater or a lefs Quantity of the Metal to be 
 precipitated. If the Ore is mixt with Glafs-gall, and 
 expofed to a melting Fire, the Regulus is eafily pre- 
 cipitated out of this moil fufible Salt : But this Re- 
 gulus moil commonly retains the Colour of the Pyri- 
 tes itfelf, and when . expofed to the Air in a Ihort 
 Time turns to a brown and very fait Powder ; which 
 fhews that a great Quantity of Salt has mixt to it : 
 Nor is the Scoria that fwims a-top deftitute of Metal, 
 which renders both the Weight and Quality of the 
 Regulus uncertain. 
 
 2. This Mixture of Sulphur with oily alcaline 
 Matters, moft commonly mull be acknowledged to 
 be an accefibrv Reafon, why the Ore melted in clofe 
 Veffels, or the Metal itfelf, when mixt with Sul- 
 phur, afford a leffer Quantity of pure Metal, than 
 when the melting is performed in an open Fire ; un- 
 lefs fome precipitating Metal is added : As, for In- 
 stance, Iron in the melting of Lead : But this does 
 
 not 
 
3 1 6 The Art of 
 
 not fucceed in the prefen t Cafe : for Iron, that may 
 be raixt with Copper while it precipitates it, mixes 
 in great Part with the precipitated Copper. For, 
 according to the moft accurate Experience, the pre- 
 cipitated participates of the precipitating Body, if 
 not in all, at leaft in a great many Precipitations; 
 and this happens in the moift as well as in the dry 
 ones ; Neverthelefs, this happens fometimes more, 
 fometimes Ids. 
 
 The further Purification of the Regulus’s ofiProc . XLL 
 and XLII, to make Black Copper. 
 
 E T th t.Regtdus be beaten to a coarfe Powder, 
 
 and be roafted and comminuted feveral Times 
 
 over, that the Sulphur and Arfenick may be diffipated 
 ( Proc . XXXIX.): Then, let it be reduced with the 
 black Flux [Proc. XL.) or by Stratification with 
 Coals. The Regulus thereby produced will be like 
 that of Proc. XL. 
 
 i. As the Regulus 9 s of the foregoing Proceftfes, are 
 made of the Particles of the Pyrites melted together, 
 with this only Alteration in the Proportion of the In- 
 gredients, that there is lefs Sulphur and Arfenick, and 
 lefs alfoof thefubtil unmetallick Earth in the Regulus’ s 
 than there was in the Pyrites out of which they have 
 been produced [Proc. XLL N°. 3.): It is neceffary to 
 make previous Roaftings by the fame Methods that 
 were prefcribed Proc. XXXIX, to make the black 
 Copper fo called Proc. XL. Nay, one or two Fu- 
 fions muft fometimes precede the Roaftings, when the 
 Regulus’ s are very coarfe, and tainted with a great 
 Quantity of Iron j that the Iron may, by a repeated 
 
 PROCESS XLIII. 
 
 APPARATUS. 
 
 TheUfe and Reafions of the Procefis. 
 
 Precipi- 
 
Assay i n g Metals. 317 
 
 Precipitation, and by the Sulphur and Arfenick 
 dill remaining, be feparated from the Copper; 
 whereas, both Metals would otherwife be confounded 
 together by a fubfequent Fufion, the Sulphur and 
 Arfenick being intirely diffipated, and could hardly 
 be feparated (Proc. XLI. Uf, N°. 2.). 
 
 PROCESS XLIY. 
 
 To find out how much pure Copper may he produced by 
 Scarification , out ofi black Copper . 
 
 W Hoever attempts to find this out with theTouch-' 
 done, muft be acquainted with the Ufe of the 
 Proof-needles ( Part L § 289.J ; one of which muft be 
 made of the pureft Copper, the others of black Copper 
 more or lefs pure ; the Nature and Goodnefs of which 
 may be afcertained by the foregoing Experiments. 
 Then the Copper to be examined, muft be rubbed 
 upon theTouch -done, and compared with the Needles 
 rubbed upon it in the fame Manner. If the black 
 Copper is of the bed Kind, after having compared 
 the Colour and Ducdility of it with the Needles, 
 you may in fome Meafure judge of the Goodnefs of 
 it. But, if it is lefs pure, you can conclude nothing 
 that is certain by this Method ; becaufe the Colour 
 and Confidence of Copper may be changed by many 
 Caufes, fometimes by one, fometimes by feveral at 
 once, there being a Multitude of Proportions that 
 concur to vary it a thoufand different Ways. For, 
 Copper, for indance, is rendered white equally by a 
 great Deal of Tin, by a little of Bifmuth, and by a 
 a very little Arfenick. What will then be your Un- 
 certainty, if many other Caufes concur with thofe 
 juft mentioned, to increafc it ! You mud then exa- 
 mine your Metal by another Method. 
 
 AFPA- 
 
3«8 
 
 The Art of 
 
 APPARATUS. 
 
 1. Separate a Specimen of your black Copper' of 
 the Weight of two fmall docimaftical Centners at 
 leaftj and do it in the fame Manner, and with the 
 fame Precautions, as if you would detedft a Quantity 
 of Silver in black Copper (Proc. XII. N°. i, 2.) 
 
 2. Then with Lute and Coal-duft make a Bed in 
 the Cavity of a Teft moiftened : When this Bed is 
 dry put it under the Muffle of the docimaftical Fur- 
 nace, in the open Orifice of which there muft be 
 bright burning Coals, wherewith the Teft muft like- 
 wife be furrounded on all Parts : When the Whole is 
 perfectly red-hot, put your Copper into the Fire, 
 alone, if it contains Lead, but if it is altogether defti- 
 tute of it, add a fmall Quantity of GlafsofLead, and 
 with a Pair of Hand-bellows, increafe the Fire, that 
 the Whole may melt with all Speed : This done, let 
 the Fire be made a little lefs violent, and fuch as 
 will fuffice to keep the metallick Mafs well melted, 
 and not much Greater. The melted Mafs will 
 boil, and Scoria’s will be produced that will ga- 
 ther at the Circumference. All the heterogeneous 
 Matters being at laft partly diffipated, and partly 
 turned to Scoria’s, the Surface of the pure melted 
 Copper will appear : So foon as you fee it, take the 
 Pot out of the Fire, and extinguifh it in Water: 
 Then examine it in a Balance, and if Lead has been 
 at firft mixt with your black Copper, add to the 
 Regulus remaining of the pure Copper, one fifteenth 
 Part of its Weight, which the Copper has loft by 
 Means of the Lead: Then break it with a Vice, 
 and thus you will be able to judge by its Colour 
 and Malleability, and by the Surface of it after it 
 is broken, whether the purifying of it has been well 
 performed, or no. But, whatever Caution you may 
 ufe in the performing of this Procefs, the Product 
 will, neverthelefs, be always lefs in Proportion than 
 
 what 
 
Assaying Metals. 3 19 
 
 what you get by a greater Operation ; provided the 
 Copper be well purified in the fmall Trial. 
 
 Another Method . 
 
 1. Take black Copper, chofen in the fame Manner 
 as before (N°. i . ) and break into fmall Pieces a Quantity 
 of it a little more than two docimaflical Centners : This 
 may be done very well with a Hammer and a Chizzle ; 
 that the fmall Bits may be made of the Size of large 
 Pieces of granulated Metal : Then reduce it to the exact 
 Weight of two Centners : Weigh alfo two Centners of 
 pure comminuted Copper: Add to each, being granu- 
 lated, an equal Weight of pure granulated Lead, not 
 having the lead Appearance of a Mixture of Copper, 
 which may bediftinguifhed from a dark Colour remain- 
 ing in it, when you vitrify it alone in a Coppel : Wrap 
 up both thefe granulated Metals feparately in fmall Bits 
 of Paper. 
 
 2. Put two Coppels under the Muffle, and heat them 
 for a While with a itrong Fire : This done, put your 
 granulated Metals into them ; and bellow all your Care 
 here to hinder the Adlion of the Fire from being 
 greater upon one Coppel than upon the other. How- 
 ever, let the Procefs be performed with a pretty llrong 
 Fire : When all the Lead is con fumed, and the Smoak 
 ceafed, take both Coppels out of the Fire, as nearly 
 at the fame Time as poffiblyyon can, and extin'guilh 
 in Water the remaining Beads of Copper: Then 
 weigh them, and as much as there is wanting of 
 the two Centners of pure granulated Copper, fo 
 much are y< 5 u to add to the Regulus remaining of the 
 two Centners of black Copper *, becatife a like Quan- 
 tity of it has been confumed by the Lead : But if the 
 black Copper contained Lead of itfelf, obferve be- 
 Tides the Difference of the Weights of both Regulus' s 9 
 and add furthermore the fifteenth Part of it. You 
 will have gathered by this Means the Weight of 
 pure Copper that may be fetched out of the black 
 ©ne, Let, for Inftance, the Regulus remaining of the 
 
 two 
 
3 20 The Art of 
 
 two Centners of pure granulated Copper weigh 1 86 lb. 
 This has loft 14 lb, by the Coppelling. If the Regu* 
 lus remaining of the black Copper weighs 154 lb. 
 you muft of Courfe add 14 lb. to the 154 lb. thereby 
 to reftitute as much Copper, as has been confumed 
 of your Copper by the fame Lead, and in the fame 
 Degree of Fire: The Sum 168 will indicate how 
 many Pounds Weight of pure Copper may be fetched 
 out of the black one. But if the black Copper had 
 already fome Lead in it 8 , this being confumed, carries 
 away with it about the fifteenth or fixteenth Part of 
 the pure Copper, which muft of Courfe be addled 
 over and above. But you may take for the Quantity 
 of the Lead, the Difference of the Regulufs remain- 
 ing after the coppelling; Therefore in the Example 
 juft propofed, the Difference between 186 and 154 
 will be 32: For which Reafon you muft add two 
 Pounds; and the whole Weight will be 170 lb. This 
 Method proves more exad than the foregoing. 
 
 The Ufe and Reafons of the Procefs. 
 
 1. This is the laft purifying of Copper, whereby 
 the Separation of the heterogeneous Bodies begun 
 in the foregoing Proceffes, is completed as perfectly 
 as it poffibiy can be. For, except Gold and Silver, 
 all the other Metals and Semi-metals are partly difii- 
 pated and partly burnt together with the Sulphur and 
 Arfenick: But, in the Fufion, they either turn of 
 themfelves to Scoria or Fumes ; or this is performed 
 by Means of Iron, which chiefly abforbes Semi-metals, 
 Sulphur and Arfenick, and the Deftru&ion of it is at the 
 fame Time accelerated by them. Thus the Copper is 
 precipitated out of them pure: For it is felf-evident,that 
 theunmetallick Earth is expelled, the Copper being re- 
 duced from a vitrefcent terreftrial to a metallick State, 
 and the Arfenick being diftipated, by Means of which 
 the faid Earth has been chiefly joined to the coarfer 
 Regnlufs of the firft Fufion. But there is at the fame 
 Time a good Quantity of the Copper that gets into 
 
Assaying Metals. 324 
 
 the Scoria’s 5 however a great Part of it may be re- 
 duced out of them by repeating the Fufion. 
 
 2; However, though Iron, when melted alone, or 
 even with Copper, is raoft eafily burnt, and fcorified ; 
 nevertheJefs, when it is once melted, and confounded 
 with Copper, it can never be entirely feparated 
 by Fire alone, without tlie greateft Part of the 
 Copper be deftroyed along with it. Therefore, ac- 
 cording to the Diverftty of the Ores, and of the 
 Skill they are managed with, there is avail Difference 
 in Coppers produced by divers Proceifes, not only 
 from many different Ores, but even from Ores of 
 the fame Kind : which Difference aim oft always de- 
 pends upon the Iron mixt with them: But, this is ea- 
 fily feparated by a little Lead : For the latter that 
 can upon no Account be mixt with Iron in a metal- 
 lick State, diffolves the Copper, and rejeds the Iron *, 
 but the Lead itfelf not being able to fufiain fo ftrongT 
 Fire, refolves partly into Fumes, and partly into Sco- 
 ria. This is alfo the Reafon* why a better Kind of Cop- 
 per is got from Copper-ores that contain Lead, and 
 from black Copper from which Silver has been fe- 
 parated by an Eliquation made with Lead, than 
 would have been got, hadLead been altogether wanting. 
 Therefore, when black Copper containing Lead is 
 to be purified, it is not without Reafon, that you 
 add to the remaining melted Copper, the fifteenth 
 Part of the Portion, which has been loft in the 
 Operation, that the Quantity of pure Copper that 
 lies hidden in the black Copper, may be more exactly 
 determined: On the other Hand, Iron has been fo 
 much rejefted in the foregoing FrocefFes, that it 
 hardly deferves any Confideration : Which is like- 
 wife true of many other Bodies that are joined with 
 Copper. However, you muft examine whether the 
 other Circumftances will permit it : Becaufe black 
 Copper is yet fometimes full of a great Quantity of 
 Sulphur : But if the latter abounds, it is proper to 
 feparate it before the Excodlion, by roafting, and 
 by a reducing Fufion, with an Addition oi fome- 
 
322 The Art of 
 
 thing that abforbs Sulphur *, for Inftance, of Scoria 
 of Iron. 
 
 3. Obferve, as to the Application of the Fire in 
 this Procefs, that it muft be applied to Copper with 
 all imaginable Speed, to make it foon run : For, if 
 you negleft this, a great Deal of your Copper is 
 burnt: Becaufe Copper that is only r$d hot, cleaves 
 much fooner and in much greater Quantity into half 
 fcorihed Scales, than it is diminifhed in the fame 
 Time, when melted. However, too impetuous a 
 Fire, and one much greater than it is neceffary for 
 the Fufion of it, deftroys a much greater Quantity 
 of it, than a Fire fufficient only to put it in Fufion, 
 would do. For this Reafon, when the purifying is 
 fm idled, the Body melted muft be extinguished in 
 Water, together with the Veftel ; left being already 
 grown hard, it fhould ftill remain hot for a While. 
 
 4. As there is more or lefs Copper deftroyed by the 
 fame Quantity of Lead, on Account of a different 
 Regimen of the Fire, the fureft Way is to make two 
 Operations at once, when Lead is fuperadded to the 
 black Copper, or when the Operation is made toge- 
 ther with Lead in a Coppel. For, by this Means, 
 you may conclude from the Portion of pure Copper 
 deftroyed, the Quantity of which is exactly known, 
 how much of the pure Copper the fame Weight of 
 Lead has carried away with it from the black Copper ; 
 as likewife, how much of it was burnt by itfelf. But, 
 though you fhould ufe ever fo many Cautions, you 
 will never have in a fmall Procefs a Product pro- 
 portionable to that of a large one : For, imperfecft 
 Metals are fooner or later deftroyed, according as 
 they are cxpofed to a greater or lefs Surface of Air : 
 Now, a fmallerMafs, ceteris paribus, is refpeflively 
 expofed to a larger Surface of Air, than a larger 
 Mafs : Wherefore, more is loft of a fmaller than of 
 a greater Quantity. To remedy this in fome Mea- 
 sure,. feveral Centners are employed for the Experi- 
 ment : But the Nature of the Operation is fuch, that 
 
 ' • you 
 
Assaying Metals. 323 
 
 you can neither intirely corred, nor altogether ex- 
 clude the Adtion of the Air. 
 
 5. It is proper here to mention the Danger occa- 
 fioned by a fortuitous or imprudent Application of 
 Water, or of a moifl, nay, of a merely cold Body, 
 to melted Copper *. For, of all Metals -'there is 
 none that fcatters with fo great a Violence all the 
 Things round it, as melted Copper, efpecially boil- 
 ing purified Copper, called in German CaljC^tlpfer ; 
 infomuch, that the Fall of a Coal, or of a imall 
 moift or cold Stone, has often broken afunder whole 
 Furnaces, and burned whole Laboratories : And this 
 happens efpecially, if but a fmall Quantity of Wa- 
 ter extended wide, touches a large Surface of Copper. 
 Likewife, Copper that does begin to grow folid, 
 being thrown on a moift, cold, but efpecially wide 
 Surface, flies about with great Danger to thofe that 
 itand by, and of fetting the Building on Fire. Where- 
 fore, if you have not a Mind to be expofed to the 
 fame Danger, you muft take Care in the Granulation 
 of Copper by Water, that it may fall from a {leap- 
 ing Surface, or through a bored Veil'd, and with a 
 fmall Stream, into Water that is ftirred about with 
 great Force. 
 
 * N. B. There Is the fame Danger in melted Brafs or bell-Metal, 
 or any other Mixture, whereof Copper makes a Part ; fo that Found- 
 ers of all Sorts fhould be equally cautious in this Refpe£b : A melan- 
 choly Accident of this Kind happened at the brafs-Foundery at 
 Windmill-hill near Moorfields , London , about twenty Years ago, when 
 feveral People of Quality were invited to fee the Calling of two 
 large brafs-Cannom at a Time ; the Heat of the Metal of the hrft 
 Gun drove fo much Damp into the Mould of the fecond, which 
 was near it, that as fcon as the Metal was let into it, it blew up 
 with the greateft Violence, tearing up the Ground feme Feet deep, 
 breaking down the Furnace, untiling the Koufe, killing many of 
 the Spectators on the Spot with the Streams of melted Me tab, 
 and fealding many others in a mod miferable Manner. 
 
 y 2 
 
 PRO- 
 
£24 The Art of 
 
 PROCESS XLV. 
 
 Examination of the Scoria's of the foregoing ProceJJt ; 
 concerning Copper* 
 
 APPARATUS* 
 
 I F the Scoria is much charged with Sulphur, beat 
 two or three docimaftica]* Centners of it to a fub- 
 tile Powder, and mix it, either alone, or, if its re- 
 fradory Nature requires it, with fome very fufible, 
 common, pounded Glafs, without a reducing faline 
 Flux, and- melt it in a clofe Veflel, and in a Fire 
 having a Draught of Air, as in Proc. XLII : You 
 will have a Regulus like that Proc « XLII. 
 
 But when the Scoria has little or no Sulphur at all 
 in it, take one Centner of it, and with the black Flux 
 manage it as you do the fufible copper-Ore 
 (Proc, XXXVI): You will have a pure Regulus. 
 
 But, if you have a Mind to try a greater Quan- 
 tity of Scoria, perform the Operation according to 
 Proc . XLI 
 
 The Ufe and Reafons of the Procefs. 
 
 i, While Metals are precipitated by Scorificatiorr, 
 and with a melting Fire, out of the folid Bodies in 
 which they are inclofed, the Scoria’s, on account of 
 their Clamminefs, mod commonly retain fomething 
 of the Metal ( Part L § 98. Schol.) : Befides, when 
 the juft Quantity of Phlogifton is wanting, and the 
 Fire is either too drong or of too long Duration, a 
 great Deal of the already precipitated Regulus* s of the 
 Metals of an imperfed Mixture, being half-vitrified,' 
 turns to Scoria’s again : Like wife, the Excefs of Sul- 
 phur and Arfenick is oftentimes an Obftacle to a fuf- 
 ficient Precipitation, eipecially when precipitating 
 Matters are wanting, or milapplied : Finally, the 
 Deftru&ibility of the Metal itfelf, hinders one from 
 
 attempt- 
 
Assaying Metals. 3 i j 
 
 attempting a complete Precipitation at once : It is 
 better to feparate only the Part which is firH: expelled 
 out of the Scoria’s •, and thefe afterwards are expofed 
 to a reducing reiterated Fufion : Which Method is 
 the more beneficial, becaufe thefe Scoria^s ferve fome- 
 times inftead of a Menftruum to melt other Ores, 
 and thus leave at the fame Time the Metal remaining 
 in them. 
 
 2. From thefe Things, might perhaps be explained 
 the pretended Obferva-tions, how a new Generation 
 of Metals has been operated, by the Influence of the 
 Stars and of the Atmofphere, in Scoria’s rejected a 
 great While ago. 
 
 3. The per fed; Scoria coming out of pure Cop- 
 
 per, out of Stones, and other vitrified Bodies, is of a 
 blue Colour. But, if there is in it more Copper not 
 quite vitrified, it looks reddifh ; and the more hill, 
 as it contains more Copper : Wherefore, a great 
 Quantity of Copper may alfo be reduced out of luch 
 a Scoria. But this Colour may be in ti rd y ob-feu red,, 
 by the Addition of many other Bodies, especially of 
 metallick ones : Which is chiefly effeded by Iron ; 
 becaufe a fmall Quantity of it gives the Scoria’s a 
 very black Colour. For this Reafon, you muft 
 never negled a docimaftical Examination of the Sco- 
 ria’s. But the metallick Regulars which are preci- 
 pitated out of them, are as various as thefe produced 
 by the Ores themfelvcs. For, the Regulm which is 
 precipitated out of the Scoria’s of ( Proc . XLI1L) the 
 pyritofe-Gre, as much coarfer than the fir ft Regulus 
 proceeding from it : For a precipitating Iron lies 
 hidden in the Scoria’s united with Sulphur, when the 
 greateft Part of the finer Metal is expelled : There- 
 fore, the Regulus which is elpecially called by the 
 Germans is more full of Iron and 
 
 Sulphur. Thus, all the Regulus* s produced from 
 the Scoria’s are commonly lefsgood than thofe ob- 
 tained by the foregoing Proceflfes : Becaufe there is a 
 greater Number of heterogeneous, and chiefly of 
 feu Bodies, in the Scoria’s, which, on this Account* 
 
 Y 3 muif 
 
326 The Art of 
 
 rnuil be compared with an Ore much impurer, than 
 that from which the Scoria’s are produced. 
 
 P R O C E S S XLVI. 
 
 The Elutriation or Wajhing of Copper-ore. 
 
 APPARATUS * 
 
 1. J "y ERE every Thing muft be done as in the 
 
 O Wafhing of the Ores of the foregoing Me- 
 tals : But you are to obferve in a fpecial Manner, that 
 the green and blue Okers of Copper ( Part I. § 366.) 
 admit of no wafhing; although they lie hidden in a 
 foft and not very ponderous Earth : For, they are 
 very light, and are carried to very great Diftances, by 
 Waters not very rapidly moved. 
 
 2. The green copper* Ores, and the blue azure 
 ones ( Part I. § 364, 365.) can never go through 
 any Roafling, without cleaving into a light blackifh 
 Powder : And as Copper, next to Iron, is of all 
 other Metals the mofl eafily burnt away, if the roaft- 
 ing is continued a little longer, or even repeated. 
 Part of the beft Copper is loft, that can by no Means 
 be recovered. For this Reafon, as the abovefaid 
 Ores are at once light and eafy to be reduced to a 
 fubtile Powder, they will not bear wafhing, unlefs 
 they are adherent to Earths, or at leaft intermixt 
 between very foft and light Stones, very eafy to be 
 comminuted by a previous Roafling: And even in this 
 Cafe feme Lofs or other is hardly to be avoided. 
 However, beware not to take for fuch Ores thofe, 
 to the Surface of which a fmall infignificant Cruft 
 of the blue or the green Oker has applied itfelf. 
 
 3. The other pyritofe, fulphureous. Copper-ores, 
 inclofed in hard ponderous Stones, on Account of the 
 Sulphur they contain, fufter, and even require a 
 Roafling ; not only to the End, that the Stones may 
 be difpofed to a more convenient Comminution, but 
 alfo that the Ore itfelf may be rendered more weighty 
 
Assaying Metals. 327 
 
 and folid : For thefe Kinds of Ores are very britt/e 
 and light, and are comminuted moreeafily and finely 
 by pounding, than the crude Stone itfelf: Whence they 
 afterwards are, for the greatefl Fart, carried away by 
 Water. 
 
 4. Therefore, when you meet with Ores that are 
 difficult to melt, on Account of Stones intermixt with 
 them, and either not feparable at all, or at lead fo 
 with great Difficulty, and never without fome Lofs 
 of the Ore itfelf, it is better to manage them accord- 
 ing to Froc. XLI. Uf. N°. 3, 
 
 PROCESS XLVII. 
 
 To find out Copper in a pyritofe-Ore , by Solution , and 
 m liquid Precipitation . 
 
 I F there is but a few half-Ounces of Copper in a 
 Centner of the Pyrites ; they can never be found 
 out by a Precipitation by Fufion : For fo final! a 
 Quantity of Copper difperfed among fo great a Heap 
 of heterogeneous Matter, is unavoidably burnt away 
 by fo many repeated Readings and Fufions. Where- 
 fore, a Method mud be chofen, whereby the Copper 
 may be feparated from the Ore by Means of liquid 
 Menjtrua , and then again eadly precipitated. The 
 Acid of Sulphur, which is already in great Plenty 
 in Pyrites, is very proper for this Operation. Make 
 a Solution of Vitriol out of fuch an Ore, by a light 
 Roading in an open Fire, and by expoiing it. after- 
 wards to an Air fome what mold, and pouring warm 
 Water upon it : Next, put into this Solution final l 
 iron-Plates, extremely well poliffied, and perfectly 
 clean of all Greafe. If there is any fmall Quantity 
 of Copper in the Pyrites, it will certainly dick dole 
 £0 the iron-Plates, in Form of a very fubtile Powder, 
 of a deep yellow Colour, and all of it will be fetched 
 out of the Solution, if you have but Time enough, 
 and a moderate Warmth : Of which more hereafter, 
 when v/e treat of Vitriol. By this Means, the very 
 
 Y 4 lead 
 
3 z 8 The Art of 
 
 lead Quantity of Copper is detedled in Iron, when 
 you make well faturated Vitriol, with Spirit of Vi- 
 triol diluted and perfedtly pure. The fame may alfo 
 be done with feveral metallick Mixtures, in which 
 Copper entefs : But it would be too long here to 
 mention the feveral Methods to be obferved in this 
 Cafe •, and the Perfon that makes the Operation will 
 eafily find them out. 
 
 PROCESS XLVIII. 
 
 f ’he Separation of Silver and Copper by Fufion with 
 
 Lead . 
 
 L E T the Copper be freed of all heterogeneous 
 Matters, by the Methods prefcribed in the fore- 
 going Proceffes : But the Gold and Silver being 
 much more conftant than Copper itfelf, remain there- 
 in in the foregoing Operations. But, the Copper 
 muft be tried, before it is intirely melted, to know 
 whether the Quantity of Gold and Silver it contains, 
 will repay the Charges of the Separation. For, this 
 Separation muft be made with Copper ftill impure, 
 called black Copper, by way of Fufion with Lead : 
 Becaufe this Separation does not fucceed as well with 
 melted Copper : See the Reafon of this ( Part I. §468, 
 469). Befides, any Portion of the Lead remaining 
 in the Copper after the Eliquation, renders the Melt- 
 ing of the Copper more perfect and eafy, than if it 
 was performed without Lead. It will not be im- 
 proper, to give a fhort Expofition of the Reafons of 
 this Procefs : But whoever is defirous to know the 
 feveral and peculiar Furnaces, Machines, and Ways 
 of proceeding, fit for this Purpofe, let him perufe 
 the Writings of Ercker *, Agricola and others, 
 whofe Methods have been reaiHed by a certain Au- 
 
 * Tranflated into Ungiifh by Sir John Tettus, under the Title of 
 Ileta Minor : Or the Laws of Art and Nature, in knowing, aiTay- 
 ing, &c. of Metals, Lond. 1686, in Folio. 
 
 f De re Metallic#, Libb. XII. Baf t, 1621. in Folio. 
 
 thoi 
 
Assaying Metals. 329 
 
 thor in a Treatife tElom ©eigcccn UttO CEttf. Bcttjert 
 
 But Mr. Swedenborge has collected all thefe Things if. 
 This Separation is performed chiefly by two Opera- 
 tions *, viz. a juft proportioning the Mixture with 
 Lead, and the running off the Lead, from the Gold 
 and Silver diffolved by it. As the Lead is not perfectly 
 feparated from the Copper byFuflon, but there remains 
 a Quantity of itadheringto theCopper(Pm\XXXV), 
 and there remains alfo fome Gold and Silver in the 
 Copper, according to the Quantity of the remaining 
 Lead ; for this Reafon, the Silver and Gold ought 
 to be diluted in fuch a Quantity of Lead, that in 
 that Portion of Lead, which cannot be run off, fo 
 fmall a Quantity of the above-tnentioned Metals may 
 remain diflblved, as doth not deferve the Addi- 
 tion of more Lead. You are to obferve, that, 
 in the Computation of the Expences, you muft have 
 Regard to the Lofs of Lead and Copper ; fince 
 it is felf-evident, that Part of thefe Metals muft 
 be loft in the Courfe of this Procefs. You are 
 iikewife to examine with the fame Exa&nefs a$ 
 in the Copper, by coppelling, what Qjanfity of 
 Silver there is in the Lead wherewith the Sepa- 
 ration is to be made: For, it is the fame Thing 
 whether Silver and Gold were already in the Lead 
 which is to be melted down, or whether they 
 have been received by it out of the Copper, in the 
 Fufton of it with the Lead. Finally, a certain Pro- 
 portion is required between the Lead and the Copper $ 
 for, if the Lead exceeds ever fo little the quadruple 
 Quantity of the Copper, you will hardly avoid the 
 falling of the latter into fmall Bits, and a great Deal 
 of it is carried away by the melted Lead. For this 
 Reafon, Iikewife, you are to add to your Copper, 
 which is eafy to be melted by itfelf as well as with 
 
 4 In his great Work called Emanudis Smdenbotgii Trmcipm Reruw 
 mturalium, five novorum Tentaminum Vh^nomena rnmdi Element arL 
 Tbilofophice explicandi. Drefd& & Ldpfi& 1734, in 3 Tom. in Fol. 
 
 Lead# 
 
33° The Art of 
 
 Lead, fome crude Copper containing Iron, and 
 which is difficult to be run down either by itfelf 
 or with Lead, and this chiefly, when your Copper 
 is fo rich in Silver and Gold, that it requires a con- 
 fiderable Addition of Lead for a fufficient Fufion. 
 Neither are you to add much lefs Lead to your Cop- 
 per than twice and a half the Quantity of it : Be- 
 caufe, if you diminifh the Proportion to an Excefs, 
 there remains behind as much Lead, as is run off. 
 But, they molt commonly add as many Portions of 
 Lead, weighing 17 lb. each, as there are half- 
 Ounces of Silver and Gold in the Mixture of Copper 
 and Lead, after the melting of them together: How- 
 ever, you fubftratft as much from thefe taken toge- 
 ther, as the Copper contained Lead before : By this 
 Means, you may feparate out of one Centner of Cop- 
 per, one Ounce, or even one half- Ounce of Silver. 
 Now, if there are in your Copper fo many half- 
 Ounces of Silver, that as many Portions of feven- 
 teen Pounds weight of the fuperadded Lead, exceed 
 the quadruple Quantity of the Copper ; this Copper 
 nuift be mixt with Copper that is poor, or made 
 Inch, to obtain a juft Proportion, or it muft go twice 
 through this Procefs. But, when the Copper is rich, 
 and there are no Obftacles in other Refpe<fts, they 
 ufe Litharge in great Part inftead of Lead, and fub- 
 ftitute 125 lb. of it, for 100 lb. of Lead : For you 
 will get that Quantity of Lead from it by Reduction. 
 They even alfo take the Scoria’s remaining in the 
 Tefts, which differ from Litharge only in Purity, 
 and which pafs through the reducing Furnace toge- 
 ther with the Copper, while this is melted. The Cakes 
 or Loaves which are made of this Mixture, com- 
 monly do not contain above three Quarters of a 
 Centner of Copper, and two or three Centners of 
 Lead. 
 
 A great Quantity of Lead is melted out of thefe 
 Cakes, firft by a gentle flaming Fire, and Silver is 
 afterwards feparated from it in a Teft. But the 
 Lead remaining of thefe Cakes is feparated in a 
 
 Furnace, 
 
Assaying Metals, 331 
 
 Furnace, which admits a Draught of Air fomewhat 
 ftronger, and a great Deal of the Copper falls from 
 the Cakes along with it. Thefe Matters laftly melted 
 out, are commonly added in the Allays of other 
 Copper. You will find feveral Examples, and 
 Methods of proceeding, in the above-mentioned 
 Authors. 
 
 OF TIN. 
 
 PROCESS XLIX. 
 
 5 The Roafting of Tin- ore. 
 
 APPARATUS . 
 
 R O AS T a determined Weight, for Inftance, fix 
 Centners of Tin-ore pounded to a Powder not 
 over fine, in a Teft, under a Muffel thoroughly red- 
 hot, Abutting firft the Vefifel for a few Minutes, and 
 then opening it. For the Melting of this Ore does 
 not require a ftronger Degree of Fire, than the fore- 
 going copper and lead-Ores. If your Fire is pretty 
 ftrong, you will fee a volatile Part of it expelled in 
 Form of a white Smoak, of the unpleafant Smell of 
 Garlick : When this is over, take out the Teft, and 
 when the Ore is grown cold, beat it anew, and roaft 
 it a fecond Time in a Fire fomewhat ftronger : till 
 you no longer perceive any arfenical Fumes : Which 
 is better detected by the Smell, when you take it 
 out, than by the Sight of it ; or if you will not make 
 this Trial, put upon the red-hot Teft, when taken 
 out of the Fire, a thick, cold Plate of Iron, and 
 look at the inferior Surface of it before it is grown 
 very hot ; this will be covered with a Email whitifh 
 Cloud, jf the Metal ftill exhales any Arfenick. 
 
33 1 
 
 Tloe Art of 
 
 The Ufe and Reafons of the Procefs . 
 
 i. Tin- Ore is never found charged with Sulphur, 
 but difpofed into a State of Ore by Arfenick: It 
 is chiefly white, femidiaphanous, and on the Out fide 
 refembles in fome Meafure Spaad, or the white Sta- 
 lactites. But the Sulphur, which is of a dark Colour 
 in Tin-ores, is hardly worth any Confideration with 
 regard to its Arfenick, Now, as Arfenick carries 
 away a great Deal of Tin by the Fire, and foon re- 
 folves Tin into Afhes, and deflroys the reft of it, 
 reducing it to a brittle Body, looking like a femi- 
 Metal ; it is necelfary to free every Tin-ore from its 
 Arfenick, as perfedly as poftible, by roafting. But 
 the longer this Ore is in melting in a ftrong Fire, the 
 eafier a great Part of it is burnt, fo as not to be re- 
 ducible, and fo as to turn to a pretty refractory 
 Scoria in a reducing Fire. Befides, Tin is never got 
 fo good out of an Ore too long agitated by the Fire, 
 as when the juft Time and Strength of the Fire are 
 obferved. The fame may be experienced with fome 
 of the beft Tin already reduced : For the oftener it 
 is reduced and burnt to Afhes, or the longer the Afhes 
 are tormented by a ftrong and pure Fire, the worfe 
 your Tin will conftantly prove after the Redu&ion. 
 
 PROCESS L 8 
 
 The Wajhlng of Tin-ore , and its farther Preparation for 
 a Reduction. 
 
 APPARATUS . 
 
 T IN- ORE, which furpafies the Ores of all 
 other Metals in fpecifick Gravity, admits 
 likewife more wafhing than any of them. You may, 
 by Elutriation, feparate from the Tin-ore, not only 
 Earths and Stones, but alfo other Ores fpecifically 
 lighter than itfelf \ especially Copper and Iron-ores, 
 
 and 
 
Assaying Metals. 333 
 
 and among thefe chiefly the light pyritofe ones. 
 But the Waffling of the other Ores fucceeds likewife 
 the better, becaufe the tin-Ore is not to eafllv com- 
 minuted to a fine Powder, as the other Ores are ; 
 except, however, iron-Ores, which are the moil 
 rigid and hardeft of them all. The tin Ore is always 
 found of a folid * Figure, and when pounded, it 
 always retains a f folid granulated Form. This 
 Ore will fometimes bear a pretty flrong Roafting, 
 without falling into fmall Bits on this Account. 
 Therefore, when hard, ponderous Scones are to be 
 waffled off, it will be no Detriment to the tin-Ore, 
 if they are previoufly difpofed by Fire for an eafy 
 Comminution. Nor do the interfperfed Pyrites turn 
 lefs into a light dufty Caput Mortuum , when the 
 Roafting is but gentle at firff, and repeated feveral 
 Times : Whereby the copper and iron-Particles, are 
 afterwards eafily waffled off by Elutriation. But if 
 there remains a hard, more intricate, ponderous 
 iron-Ore, not eafy to be calcined, it isextra&ed with 
 the Load-ftone after the Roafting and the Elutriation. 
 But the Separation of the Copper-ores, and of the 
 iron pyritofe Ones from the tin-Ore before the melt- 
 ing, is the more to be regarded, becaufe none are 
 found mixt with the tin-Ores fo frequently as thefe : 
 But as Tin diffolves Iron and Copper, and even with 
 a Fire much milder than is required to make them 
 melt of themfelves ; it is eafy to conceive, that all is 
 confounded, when a reducing Fufion is made, be- 
 fore the Separation of both by Elutriation or by the 
 Load-ftone has been previoufly made : Whence the 
 Confidence of the Tin thereby produced, is fpoiled, 
 and it is rendered unfit for a great many Ufes. But 
 a moft exad Separation of the Earths and Stones 
 from the tin-Ore, is required ; becaufe reduced Tin 
 can never fuftain fo ft rang and long-lafting a Fire, as 
 is required to perfe<5t a fufficient Scorification for 
 
 * A cubic Figure. 
 
 f A cubic Figure., even when granulated. 
 
334 
 
 The Art of 
 
 the Precipitation of the metallick Particles. Like- 
 wife, the Calx itfelf of reduced Tin, renders all the 
 Scoria refradory and clammy in the Fire. 
 
 PROCESS LI. 
 
 The Reduction of Tin- ore in a clofe Vejfel. 
 
 APPARATUS. 
 
 HIS Procefs is done in the fame Manner, as 
 
 the like with the Lead-ore (Proc. XXX) ; only 
 let the Fire be carried as foon as poflible to the 
 higheil Degree which is neceffary here ; and fo foon 
 as you judge that the Flux is melted, take out the 
 Veffel, let it grow cold of itfelf, break it, and exa- 
 mine the Scoria and the Regulus. 
 
 The Examination of all Metals that are dedruc- 
 tible in the Fire, and above all that of Tin by Pre- 
 cipitation and Redudion in clofe Veffels, is ex- 
 tremely deceitful ; infomuch that the mod experi- 
 enced Allayer, will moil rarely find Regulus's of a 
 perfedly equal Weight, from one and the fame Ore, 
 though it be comminuted, and all the Particles well 
 mixt together, if he makes this Procefs feveral 
 Times over : For, the Ore or Calx of Tin, is refradory 
 enough, when a Redudion is to be completed, where- 
 fore, it requires a more violent Fire *, but, reduced 
 Tin, on the contrary, is mod quickly dedroyed 
 again by the fame Fire. You may, indeed, in feme 
 Meafure judge, whether an Ore is rich, poor, or 
 middling ; but you can hardly do it to a Pound : 
 For, during the Operation, you have no certain 
 Sign, whether the Redudion and Precipitation are 
 perfed, or no : And have only meer Conjedures as 
 to that. The faline Flux, which helps the Scorih- 
 cation, has nothing to convert into Scoria but the 
 
 The Ufe and Reafons of the Procefs . 
 
 Tin 
 
Assaying Metals. 335 
 
 Tin itfelf : For* the terreftrial adherent Particles, are 
 feparated with greater Care, and more perfectly from 
 the tin-Ore, than from the others ( Proc . L). Ne- 
 verthelefs, you may know from the perfed: or im- 
 perfect faline Scoria, from the fmall metallick Grains 
 difperfed among the Scoria, or even from the very 
 Scoria proceeding from the deftroyed Metal, which 
 may be reduced again, but chiefly from that part next 
 the metallick Regulus^ whether a great Fault has 
 been committed. Therefore, the Examination of 
 the tin-Ore is better done by the following Method. 
 
 PROCESS LIL 
 
 5 the Reduction of Tin-ore , ex tempore. 
 
 APPARATUS. 
 
 l /iHUSE a large *, thick, extinguifhed, and 
 well burnt Coal of foft Wood, not very fi- 
 brous, nor crackling in the Fire, fuch as lime-tree or 
 hade-tree Wood : Make the largeft Surface of it flat 
 and fmooth with a Knife. Excavate in that Plane a 
 Channel open in the fore-Part and above, beginning 
 at the Side and reaching to the Middle of the Plane : 
 Make a fmall pretty deep Pit at the hinder Extre- 
 mity of this Channel : But, the Capacity of both the 
 Channel and the Pit mu ft be fo great, as that feme 
 docimaftical Centners of the Ore, may hardly fill 
 the third Part of both. 
 
 2. Put into the above-deferibed Channel (N°. 1.) 
 two docimaftical Centners of tin-Ore, well prepared, 
 and beaten to a moft fubtile Powder, with a little 
 of common Pitch, and let them be fpread fo wide, 
 that the Ore thus heaped up, may no where come 
 up to the Height of the Channel. Put upon this 
 Coal another, of equal Length and Breadth, and 
 made fmooth in fuch Manner that the Channel and 
 
 * Or a large Piece of unlighted Charcoal,, 
 
 fmall 
 
33<S The Art of 
 
 fmall Pit may be both quite covered over. Make in 
 the Place where the Channel and fmall Pit are con- 
 tiguous to the upper-Coal, a fmall Hole through the 
 whole Thicknefs of it. Then join both Coals toge- 
 ther with an iron-Wire, or with Lute applied at the 
 Joints. 
 
 3. Put this Apparatus upon' Allies or Sand, that it 
 may not vacillate, and in a declining Situation, that 
 the Aperture of the Channel may be uppermoft, and 
 look towards the Affayer, and the back-Part, where 
 the fmall Pit is, be much lower. Then, furround 
 it on all Parts with black and burning Coals ; in fuch 
 Manner however, that the PalTage of the Wind 
 through the Channel before, may not be intercepted. 
 Now, if you blow the Fire with a Pair of hand-- 
 Fellows, fo as that the Rlaft may enter dire&ly into 
 the open Extremity of the Channel, and again go 
 out through the Hole made in the upper-Coal, the 
 Flame following the fame Direction, foon melts the 
 Ore in the Channel, and reduces it at the fame Time : 
 Which is alfo helped on by the Pitch. But fo foon 
 as the Ore is in fufion, the Metal runs into the fame 
 Pit, where it is free from the great Violence of the 
 Fire. This done (which is perceived by Sight* 
 or felt by a fmall iron-Wire) remove the burn- 
 ing Coals around, and with a fmall Brufh fprinkle 
 it foftly, and Drop by Drop with Water *, that the 
 Regains of Tin may indeed be quickly cooled, but 
 not diihpated in Grains. 
 
 PROCESS Till. 
 
 To reduce Tin- ore, by a Stratification with Coals . 
 
 APPARATUS. 
 
 Y otr muff here obferve all that has been faid of 
 a like Procefs (XXXIV.) with Lead : Provided 
 the Ore be well prepared, and the Bellows be not fo 
 much diredled downwards towards theBed, nor blowing 
 
 fo 
 
Assaying Metals. 337 
 
 drongly, Let the Coals be fmall, and of a foft 
 Wood, that a pretty ftrong Fire may be mod quickly 
 kindled, and extinguished foon. For, if fmall Coals 
 are agitated with Bellows, they grow reck hot, and are 
 confumed much fooner than the large ones ; and if 
 you fprinkle them here and there with Water drop 
 by drop with a fmall Broom, the Fire grows of the 
 ut mod Strength : For which Purpofe, likewife, you 
 may put moidened Ore into the Fire. 
 
 OF IRON. 
 
 PROCESS. LIV. 
 
 To reduce and precipitate Iron out of its Ore , in a clofe 
 
 VefleL 
 
 W E have already mentioned, how the martial 
 Earth and the Iron-ore may be known by the 
 AClion of the Magnet ( Part L § 359, 360.) but ic 
 is plain from what follows, that this Examination is 
 upon no Account Sufficient. For, all Metals, femi- 
 Metals, Sulphur, and Arfenick, except only Anti- 
 mony and Lead (which lad is not to be considered, 
 becaufe it never admits of any Mixture of Iron) be- 
 ing united in great Quantity with Iron by Fire, 
 hinder not the Magnet from attracting the Iron. 
 (Fid. Cl. Henckelii pyritolog. pag. 41 3). And though 
 the Adtion of the Load-done is the weaker upon 
 Iron, as there is a greater Quantity of the Minerals 
 juft mentioned joined with it, and vice verfa *, never- 
 thelefs, we can upon no Account conclude from the 
 ftrong or weak ACtion of the Magnet, what 
 Quantity of Iron can be reduced out of the Ore, or 
 out of any other martial Compound : Becaufe 
 
 the various Strength of Load-ftones, and the Quality 
 and Proportion of the feveral Bodies that may be 
 combined with Iron, occa lions a very great Diffe- 
 rence among the Effe&s of the Magnet : For more 
 may be mixt of one Body with Iron, than of ano- 
 
 2 ther* 
 
3 3 § Art of 
 
 ther, fo that a Mafs cannot be attracted with equal 
 Strength by the Load-Hone. The eafier and more 
 difficult melting of Iron, and its Quality, when melt- 
 ed, likewifedo depend upon thefe kinds of Mixtures, 
 Befides, the Bodies which are contiguous to Iron 
 only on the Outfide, are partly taken up along with 
 it by the Load* Hone, let the Iron or its Ore be ever fo 
 finely pulverized. For this Reafon, you muH have 
 Recourfe to an Examination by Fire, to know with 
 Certainty the Quantity and Quality of she Iron to be 
 reduced out of the Ore. 
 
 APPARATUS, 
 
 1. Roaft for a few Minutes, in a TeH under the 
 Mu-ffel, and with a pretty ftrong Fire, two Cent- 
 ners of the fmall Weight of your iron-Ore grofly 
 pulverized : That the Volatiles may be diffipated in 
 Par^ and the Ore itfelf be foftened, in cafe it ffiould 
 be too hard. When it is grown cold, beat it ex- 
 tremely tine, and roaft it a fecond Time, as you do 
 the copper- Ore, but in a much Hronger Fire ; till it 
 no longer emits any Smell : Then let it grow cold 
 again. 
 
 2 . Com pole a Flux of three Parts of the white 
 Flux (Part I. § 163)5 with one ^ art °f hafible pul- 
 verized Glafs, or of the like fteriie unfulphureous 
 Scorias ; and add glafs- Gall and coal- Dull of each 
 one half-Part. Add of this Flux three Times the 
 Quantity of your roafted Ore, and mix the whole 
 very well together. Then chufe a very good Cruci- 
 ble, well rubbed with Lute within, to Hop the Pores 
 which may be here and there unfeen ; put into it 
 your Ore mixt with the Flux ; cover it over with 
 common Salt, and ffiut it clofe with a Tile, and with 
 Lute applied to the Joints. 
 
 3. Put the wind-Furnace upon its bottom-Part* 
 having a Bed made of coal-BuH ( Part L Plate III. 
 Fig. X) : Introduce, befides, into the Furnace a 
 fmall Grate fupported on its iron Bars, and a Stone 
 
 upon 
 
Assaying Metals.' 339 
 
 upon it, whereon the Crucible may Hand as upon a 
 Support. Surround the Whole with hard Coals not 
 very large, and light them at Top. When the Vef- 
 fel begins to grow red, which is indicated by the 
 common Salt’s ceafing to crackle, Hop with grofs 
 * Lute the Holes of the bottom-Part, except that in 
 which the Nozel of the Bellows is received : Blow 
 the Fire, and excite it with great Force, adding now 
 and then frefh Fuel *, that the Veffel may never be 
 naked at Top. Having thus continued your Fire in 
 its full Strength for three Quarters of an Hour, or 
 for a whole Hour, take next the VelTel out of it, 
 and ftrike feveral Times the Pavement, upon which it 
 is fet, that the fmall Grains of Iron which happen to 
 be difperfed, may be collected into a Regulus , which 
 you will find after having broken the VefTel. 
 
 4. When the Regulus is weighed, try its Malleabi- 
 lity then make it red-hot, and, when fo, ftrike it 
 with a Hammer ; if it bears the Strokes of the Ham- 
 mer, both when cold and when red-hot, and extends 
 a little ; you may pronounce your Iron very good : 
 But if, when either cold or hot, or in both States, 
 it happens to prove brittle : You may judge it not to 
 be quite pure, but ft ill in a femi-mineral Condition. 
 But, the worfe the Chara (fieri flicks of your Iron are, 
 the greater the fmall Grains or Furrows will be 
 found in it when broken, which is called in German 
 t^Ofeftootntg, Cftrofe^petlfig;* Whence the Work- 
 men, at the Sight of broken Iron, ufe to judge of 
 its Goodnefs, though not with demon ft ra live Cer- 
 tainty. 
 
 "The Ufe and Reafons of the Procefs . 
 
 1. Before you reduce your iron-Ore by Fire, the 
 Arfenick, but much more the Sulphur, muff be dif- 
 iipated at lead in Part : For the former renders the 
 
 ? _ Or windfbr- Loam* f Coarfe grained, coarfe fibred. 
 
34° The Art of 
 
 N Iron, that comes out of the Ore, brittle, and, the latter 
 not only does the fame, but being managed in a clofe 
 Veffel, with a faline alkaline Flux, turns to Liver 
 of Sulphur, to the Ad ion of which Iron yielding in 
 every Refped, it can upon no Account be precipitated, 
 and, if not the whole, a great Fart of it, at leaf!, is 
 retained by the fulphureous Scoria ; fo that in this 
 Cafe, you will moft commonly look in vain for a Re- 
 gulus . See the Effed of the Ingredients, of which 
 the Flux is compofed ( Part I. § 164). 
 
 2. The Iron which is obtained from this fir ft Pre- 
 cipitation, has hardly ever the requifite Dudility ; 
 but is rather brittle : The Reafon of which is, that 
 the Sulphur and Arfenick remain in it. It is true, 
 when a Vein of Iron is roafted, if it abounds in both 
 thefe Matters, it loofes the greateft Part of them, 
 and even the more fo, as the Ore is lefs difpofed to 
 melting : But, feme Part of them feems to be fo 
 ftridly inherent in the Ore, that it can never be fepa- 
 rated, but with abforbent, terreftrial, alkaline In- 
 gredients, that change the Nature of the Sulphur : 
 For this Reafon, in a larger Operation, they add 
 quick-Lime, or marble Stones that turn into an acrid 
 Calx, which, while they abforb the faid Minerals, 
 are by it, and by the Help of the deftroyed Part of 
 the Iron, brought to a Fufton, and turn to a vitri- 
 fied Scoria ; though, at other Times, they refift fo 
 much by their own Nature a Vitrification. Another 
 caufe of the Brittlenefs of Iron is the unmetallick 
 Earth, when it is not yet feparated from it : For the 
 iron-Ore contains a great Quantity of it, and in the 
 melting remains joined with the reguline Part : 
 Whence the Iron is rendered very coarfe and brittle. 
 Some iron* Ores are altogether untradable : Never- 
 thelefs, the Regulus’s produced out of them, when 
 broken, have fometimes a neat femi-metallick Look : 
 Which proceeds undoubtedly from a Mi'xture of a 
 fmall Quantity of fome other Metal or femi-Metal. 
 But they generally negled a further Examination of 
 thefe Sorts of Mixtures, and the Methods of fepa- 
 
 rating 
 
Assaying Metals. 341 
 
 rating them, which are certainly difficult •, becaufe 
 we find almofl every where iron- Ores, that are both 
 richer, and of a better Kind. 
 
 3. This Fufion and Reduction 6f the iron-Ore by 
 Stratification with Charcoal, fucceeds with great 
 Difficulty in a final 1 portable Apparatus : For, be- 
 fore the iron-Ore can be put into the Fire, the Walls 
 of the Furnace mufl be very red-hot : Which can- 
 not be done without fome Detriment to the Apparatus , 
 unlefs the Infide be done over with thick Lute *. 
 Befides, if the Lute is not of the beft Kind, it is almofl 
 confumed by fo violent a Fire, and by the Scoria’s, 
 as are likewife the Walls of the Furnace. It is bet- 
 ter, for this Experiment to make a fmall Furnace 
 with Stones, in the Hearth of a Smith’s Forge *, then 
 the Operation is finifhed in the fame Manner, as a 
 like Procefs with Copper. Neverthelefs, a ftill more 
 violent Fire is required here ; and Scoria’s of Iron, or 
 fome other very fufible Stones, fometimes together with 
 Lime, mufl be put into the Furnace before and with 
 the Ore to be tried ; not only to promote the Melt- 
 ing, and to feparate the Iron from the heterogeneous 
 Bodies, but alfo that thefe Things fwi mining upon 
 the Regains, may hinder its being confumed by the Fire 
 and the Biafl. The Furnace mufl be kept very full 
 with Coals during the Operation, and but a fmall 
 Quantity of the Ore be put in at a Time. 
 
 The melting of crude brittle Iron , to make it malleable v 
 
 O reflore Malleability to Iron, the Bodies which 
 
 render it brittle mufl be feparated, and the Par- 
 ticles of it be made to flick clofer to each other, that 
 every heterogeneous Matter, lying hidden in its Inter- 
 Ilices, may be expelled. This may be conveniently done 
 on a Hearth like that of a Smith’s Forge, having a Bed 
 
 PROCESS LV. 
 
 * Of WindforToam* 
 
 made 
 
34i The Art of 
 
 made with coal- Dull : Put into this Bed the Coals 
 and the Iron to be melted, heaped up in good Quan- 
 tity in Strata , then with the Bellows blow the Fire 
 pretty ftrongly, that the Iron may be brought to a 
 Fufion : And if it does not melt foon of itfelf, and 
 emit Abundance of Scoria’s, it is neceffary to help 
 on the Fufion with fufible Scoria’s, or with Sand, 
 Let the Fire not be much greater than is necefiary 
 to make all thefe Matters melt as equally as poffible : 
 Let the melted Mafs be agitated here and there, that 
 all the Parts of it may feel the Adtion of the Fire and 
 Air equally: And let the increafing Scoria’s betaken 
 out at one or two Times. In the mean Time, a 
 great many Sparkles, like Rain, will be thrown out 
 from the Iron, which diminilh the more, as the Iron 
 comes nearer to the defired Degree of Purity, but 
 they never ceafe intirely. Then let the burning 
 Coals be removed, and the Scoria’s be conveyed out 
 of the Fire, through a Channel made for that Pur- 
 pofe •, but, when the Iron grows folid, let it be taken 
 red-hot out of the Fire, and tried by flriking it with 
 a Hammer : If it proves crude (till, let the Melting 
 be repeated : And when at laft fufficiently purified, 
 let it be hammered, and extended feveral Ways, by 
 making it red-hot many Times over : This done it 
 will no longer be brittle, even when cold. 
 
 The TJfe and Reafons of the Procefs . 
 
 The remaining volatile Materials which make Iron 
 brittle, and keep it in a mineral State, are diflipated 
 in this Operation by the Fire and Air •, the terref- 
 trial, unmetallick, vitrified Parts, are rejected under 
 the Form of Scoria’s, while the Iron is in a perfect 
 State of Fufion : Nor can this, however, be done 
 with fufficient Exadmefs by a fingle Fufion : Nay, 
 Iron does not even acquire its defired Degree of 
 Malleability by a fecond Fufion alone, but when cold, 
 and ftrongly hammered, it flies afunder, or at leafl 
 cracks , for which Reafon it mull be hammered feveral 
 
 Times* 
 
Assaying Metals. 343 
 
 Times, by making it very red-hot over and over 
 again ; that the remaining terreftrial, fcorified Parts, 
 may be expelled out of its Interfaces, and the metal- 
 lick Particles be united together. This is called in 
 German SDPCC^fcfjUJCtffClt : And when the Opera- 
 tion is well performed, it communicates to Iron, 
 whether red-hot or cold, its due Malleability. It is 
 obfervable here, that any Iron, though ever fo pure, 
 is perfectly malleable, when melted in a reducing 
 Fire ; but yields with Difficulty to the Hammer im- 
 mediately after the Fufion. It like wife becomes ri- 
 gid, if fuddenly cooled, efpecialiy if it is immerfed 
 in Water : However, this Rigidity happens only in 
 cold Weather, and is not fo great as that of melted 
 crude Iron, and may be perfe&ly reduced to its fir ft 
 State, if after having been red-hot for a few Hours 
 in a pure gentle Fire, it cools of itfelf very (lowly. 
 Nay, other hard Metals, fuch as Copper, Brafs, 
 Silver, and Gold, harden after the Fufion, or after 
 having been beaten over and over with the Ham- 
 mer, but never to fuch a Degree as Iron, and their 
 Flexiblenefs is reftored by the lame Artifice, that is, 
 by being made red-hot, and cooled by very (low 
 Degrees ; fo that they afterwards grow almoft as 
 pliant as Lead. But you muft take Care that there 
 is no fmoaking Flame proceeding chiefly from the 
 cruder Charcoals, otherwife the Softening does not 
 fucceed. This may be obferved chiefly in Gold, 
 which, though very pliant and tenacious, yet be- 
 comes more rigid than Copper, when an extinguifhed 
 Charcoal, (fill fmoaking, and half burnt, fails into 
 it, while it is perfectly red-hot, or melted in a Cru- 
 cible. 
 
 As for the re ft , you muft obferve here, that there 
 is no Metal, that buffers fo great a Diminution of its 
 Subftan.ee in the Exception, or only in a Ample Fu- 
 fion, as Iron does : Nay, if only made very bright 
 red-hot, it burns away moft fpeedily, or wears out 
 into fcorified Scales* But this Conibuftion happens 
 
 Z 4 quicker 
 
344 7 $<? Art of 
 
 quicker in malleable purified Iron, than in Iron to 
 which Sulphur has been added. 
 
 PROCESS LYI. 
 
 The preparation of Steel out of Iron , by Cementation . 
 
 S TEEL is made of Iron in two different Manners, 
 viz. by Cementation ( Part I. § 459.), or by Fu- 
 fion. The Cementation is performed in the follow* 
 ing Manner. 
 
 APPARATUS . 
 
 1. Chufe fome Bam of pure Iron, not over-thick, 
 and quite free from heterogeneous Matters, the Flexi- 
 blenefs of it, both when hot and when cold, is a very 
 good Sign thereof. Prepare a Cement compofed of 
 fuch Ingredients as emit an abundant Phlogifton, 
 when agitated by the Fire, provided the faid Phlo- 
 gifton be altogether free from the fulphureous mine- 
 ral Acid : Such as are all extinguished Coals, and in 
 fhort all Parts of Animals and Vegetables *, among 
 which, thofe, however, are much fo, which contain a 
 greater Quantity of Oil in them, and which being freed 
 of an exceilive Phlegm, have been burnt before into 
 a femi- carbonaceous Mafs. Avoid whatever abforbs 
 oily Vapous with great Force, or even fpreads the 
 Acid of Sulphur, or the mineral Sulphur itfelf. It 
 is better to add a few Compofitions, in Order to 
 clear the Matter. 
 
 Take Charcoal- dufi: moderately pulverifed 1 Ph of 
 Wood-allies y P\ Mix them together. 
 
 Take Charcoal-duft 2 P ts . P>ones, Horns, Leather, 
 Hairs of Animals (it is all one if you ufe but one, 
 or feveral, or even all of them mixt together j for 
 one of them alone is as fufticient as the Mixture of 
 them all) burnt with a gentle Fire till they are black 
 in a clofe Veffel, then pulverife them 1 P*. Wood- 
 allies £ P\ Mix them together. 
 
 As 
 
Assaying Metals. 345 
 
 As for the reft, it has been found, that the Parts 
 of Animals, on Account of the Abundance of Oil 
 they contain, are of a quicker Effect than the Reft. 
 
 2. Prepare an Earthen-veffel, the beft Figure of 
 which is the Cylindrical, two or three Inches higher 
 than thelron-barrs N°. i.) are long : Put into the Bot- 
 tom of it your Cement prepared in the aforefaid 
 Manner, fo that being gently preffed down, it may 
 cover the Bottom of the VefTel to the Height of one 
 Inch and a half. Place the Iron-bars perpendicu- 
 larly, in fuch Manner, that they may be about one 
 Inch diftant from the Sides of the VefTel, and from 
 each other: Fill the empty Interfaces with the fame 
 Cement ; and cover alfo the Bars with it, that the' 
 VefTel may be quite full; next cover it with a Tile, 
 and ftop the Joints with thin Lute. 
 
 3. When thus prepared (N°. 2.) put this VeffH 
 in a Furnaci, where you may for feveral Hours main- 
 tain an equal Fire, as either in the Bottom of the 
 Tower, or in the firft Chamber of the Athanor 
 {Part I. § 243.) Make a Fire fo ftrong, as that the 
 VefTel may be moderately red-hot for fix or ten 
 Hours together: When this Time is over, take it 
 out of the Fire, and dip the red Iron-barrs into cold 
 Water. They will then be brittle, and turned to 
 Steel, there will appear no Scoria at the Out-fide, nor 
 will the Weight be diminifhed, if you have but rightly 
 made your Procefs according to the Regimen of the 
 Fire. 
 
 4. The Signs of the Iron’s being changed into Steel 
 arc, if being red-hot, and extinguifhed in cold Wa- 
 ter, it becomes very hard, not yielding to the Ham- 
 mer, brittle when more ftrongly hammered, and re- 
 fill ing the hardeft File: By which Quality it is diff 
 tinguifhed from Iron rendered malleable, which in- 
 deed grows rigid when extinguifhed in Water, but 
 yet retains a confiderable Degree of Dudbility in the 
 Cold, and may be extended in all Dimenfions with 
 the Hammer. However, Steel that is cooled foftjy, 
 and by flow Degrees* may be filed and extended with 
 
! The Art s/" 
 
 the Hammer any Way, fome more, fome lefs : By 
 which Quality it may be diftinguifhed from crude 
 melted Iron : For this is often brittle, both when cold 
 and when hot, though it has not been extinguifhed in 
 Water. But, there are a vail many Degrees in the 
 hardening of Steel : For, if it has been made too red- 
 hot, and is fuddenly extinguifhed in cold Water in 
 Motion, it hardens more than if it had been but 
 faintly red, and cooled in warm Water. This Hard- 
 ening is caufed by all fuch Bodies as fuddenly abforb 
 the Heat, and at the fame Time do not eafily pe- 
 netrate the Steel, but change its Nature. Steel is 
 moreover of a darker Colour, and the Surface of it, 
 when broken, appears to con fill of fmaller granulated, 
 and even filiated Particles, than the Iron which it is 
 made of: The Germans call it * 
 
 But, this appears more diitindly, when 
 Steel is welded to the fame Kind of Iron, which it 
 was made of, and when the Mafs made red-hot is 
 well incorporated together, by hammering : If then 
 you harden it again by extinguifhing it in cold Water, 
 and polifh it, the Veins of Iron may he very well 
 diftinguifhed from thofe of Steel : For, the Iron-ones 
 are more whitifh, and almoft of a Silver-colour, but 
 the Steel-onesof a darker Dye, and almoft of the Co- 
 lour of Water. For which Reafon Dr. Stahl is of Opi- 
 nion, that the Steel of Damafcus , which has the fame 
 Colour on the Out-fide, is made in the fame Manner. 
 But, if fuch Steel mixt with Iron is broken, you may 
 like wife obferve the Difference of the Largenefs and 
 Colour of its Particles. 
 
 'The Ufe and Reafons of the Procefs . 
 
 i. All you do in this Operation is, to apply oily 
 Vapours to pure Iron, the rigid Body of which being 
 mollifyed by the Heat, and made quite red hot, is pe- 
 netrated by the faid* Vapours, which, then ftridly 
 
 * Fine grained* fine fibred* 
 
 unite 
 
Assaying Metals. 347 
 
 unite to it : Which is thought to be fo, becaufe the 
 Iron thus change^, not only preferves its fir ft Weight 
 (whereas when made red hot, it other wife lofes al- 
 ways a great Quantity of its Subftance, which goes 
 away in Form of fcaly Scoria’s) but even proves to 
 have increafed it a fmali Matter, uniefs too great and 
 long-lafting a Fire has burnt the Surface of it ; which 
 the Scales going off from it do fhew. For this Rea- 
 fon, the effential Difference between pure Iron and 
 Steel, confifts in the greater Proportion of Phlogifton 
 more intimately joined to one than to the other. 
 Thence the Reafon is like-wife clear, why a too thick 
 Piece of Iron being put into fuch a Cement, or the 
 Iron-barrs not being left long enough in the Fire 
 with the Cement, they are only furrounded with a 
 fteely Cruft, while the inward Subftance remains 
 Iron. 
 
 2. That every oily Subftance free from the Acid of 
 Sulphur, is fit for changing Iron into Steel, is plain 
 from the feveral Experiments of Workmen, fome of 
 which ufe for their Cements a Multitude of different 
 Particles of the animal and vegetable Kingdoms, 
 and yet all of them produce the very fame Kind of 
 Steel, provided the other Ingredients are alike: But 
 if you employ for your Cement any Body exhaling 
 Acid of Sulphur, or even Sulphur itfelf in a ftrong 
 Fire, you not only will have no Steel, but inftead of 
 it the Subftance of the Iron changes, and goes away 
 into a Scoria. For this Reafon Sea-coals * are not 
 fit to render Iron malleable, nor to turn it into Steel : 
 Nay, Iron and Steel are more eafily burnt and de- 
 li royed by them, than they are by an open Fire 
 
 * Our Sea-coals or Ne-vocafile Coals, or In general all the foflil 
 Coals which cake in burning and run into Cinders, abound with 
 Sulphur, and therefore are improper to be ufed about Iron, always 
 making it brittle 5 but Pit-coals, Kennel-coals, and Scotch-coals, 
 which burn to a White-afh like Wood, and abound more in a Bitu- 
 men, may be ufed in the hrft fluxing of the Iron from the Ore, and 
 if the Iron prove not fo malleable as is required, this Property may 
 be given to it by melting the Metal a fecond Time with Wood. 
 
 Of 
 
348 The Art of 
 
 of Wood-coal, unlefs you ufe a peculiar Remedy 
 for it. 
 
 3. Therefore, the bed Steel made red hot a long 
 Time, or frequently, efpeeiallym an open Fire, the 
 phlogiftick Part being difiipated, turns to Iron again, 
 provided the Fire is managed, fo as that it may not 
 quickly turn the whole Mafs into Scoria’s. 
 
 PROCESS LVir. 
 
 The Production of Steel out of crude unmalleable Iron> or 
 out of its Ore , by Fufton . 
 
 W E dial! here in a clear and general Manner give 
 the Method for making Steel by Fufion. Chufe 
 for Indance, Iron-Ore, or the Iron itfelf dill crude 
 of the fird Fufion, which we know can be rendered 
 tough and firm by being melted, made red hot, and 
 hammered. For, according as Iron, or its Ore is 
 different in its Kind, fo you may make with it diffe- 
 rent Sorts of Steel, and with greater or lefs Eafe, or 
 Difficulty. Put at one or feveral Times into a Bed 
 mac\e with Charcoal Dud in a Smith’s Forge, fuch 
 Quantity of this Metal divided into fmall Parcels, 
 as that the Metal remaining after the Melting of it 
 is compleatly performed, may not be more than two 
 or three common Centners •, not only that the Melt- 
 ing may be fooner finifhed, but alfo becaufe a fmall 
 Mafs may be better and more equally penetrated 
 with the Vapours of the Phlogidon : Nay, they alfo 
 add, as a defenfive Mendruum, fome of the 
 vitrefcent fufible Scoria’s, either of Sand, or of final] 
 Stones of the lame Nature: Then put upon them 
 Abundance of Charcoal, light them, and admit only 
 a gentle Blaft of the Bellows •, that the Scoria’s and 
 the Metal may both melt very well: Take out now 
 and then Part of the Scoria’s, and often dirr the 
 melted Mafs with a Stick ; that all the Parts of it 
 may as much as polfible feel the fame Degree of 
 Fire. Having at lad removed the Fire and the Sco- 
 
 ria’s a 
 
Assaying Metals. 349 
 
 ria’s, and the Mafs being grown folid, put it upon an 
 Anvil, and with a Hammer divide it into two Parts, 
 which muft be extended into long Barrs by being 
 made red hot, and hammered feveral Times over: 
 Then extinguifh them in cold Water, whereby they 
 are rendered fo very hard, that they will fly afun* 
 der when (truck with great Force, and will not be 
 filable ; which (hews that the Operation has been well 
 made. But, if you have a 1 Mind at the firfl: Time to 
 change Iron-Ore or crude Iron into Steel, nothing but 
 a Repetition of Trials will inform you, how long and 
 at how many Times the Matter in Hand mull 
 fnelted, made red hot, and hammered. For, there 
 are Ores, which, by a firfl Fufion, produce MaflTes' 
 which are intermediate between malleable Iron and 
 Steel •, or refemble Steel that is but half-worked : 
 Whence fuch Steel-Ores are commonly called by the 
 Germans * Other Ores, on the con- 
 
 trary, muft often go through a Number of long- 
 Jafting Fufions and Hammerings, and fometimes lofe 
 half the Weight of the crude Iron in the firfl; Fufion, 
 and yet never yield a right Kind of Steel. But, it is 
 eafy to guefs at the Reafon, why this Procefs is very 
 much forwarded, when you now and then add to 
 your burning Coals, a fat, oily, and fixt Fewel, 
 taken out of the animal or the vegetable Kingdom ; 
 For, the Metal muft be penetrated by the Phogifton, 
 and receive it both in great Plenty and very inti- 
 mately : While, at the fame Time, the terreftrial 
 and fulphureous Particles which render the Iron crude 
 and brittle, are diflipated: For, the abovemen tioned 
 Fewel produces Nothing of thefe Matters, but only 
 conftantly fupplies a Phlogifton deftitute of Acid of 
 Sulphur. Take Care, on the contrary, not to torture 
 your Metal with too violent, too long, and too dry 
 a Fire, nor with an exceflive Blaft of Wind: Other- 
 wife, you would in vain expect: the cleared Change. 
 
 ? Steel Stone. 
 
 By 
 
35® Art of 
 
 By this Means, you will prepare a good Quantity 
 of common Steel, fit for Sale : If any Reader is de- 
 li ro us to have any more particular Apparatus’s, fuch 
 as are pradlifed in feveral Places, he will find many 
 of them, though no Way efifentially different among 
 themfelves, in Swedenborg? s Treatife of Iron *f\ 
 
 OF MERCURY, 
 
 PROCESS LVIII. 
 
 5 the Separation of Mercury out of a unfulphureous Ore , 
 by Diftillation. 
 
 APPARATUS. 
 
 i. Hip A K E a Lump of the pulverized Ore, one 
 JL common Pound, which muft Hand for one 
 Centner ^ put it into a Glafs Retort perfectly clean, 
 well loricated, or coated up, to half the Length of its 
 Neck : This muft be very long, and turned back- 
 wards with fuch Declivity, that a Glafs-Recipient 
 may be perpendicularly applied to it. But, you muft 
 chufe a Retort fmall enough, that the Belly of it 
 may be filled hardly two Thirds by the Ore. This 
 Retort muft be placed fo, as that nothing of the Fluid 
 adherent to the Neck of it may fall into the Cavity of 
 the Belly, but that the Whole may run forward into 
 the Recipient : Therefore, unlefs the Pavement of the 
 Hearth is already high, make one ex tempore with 
 Bricks, or with an Iron-plate, put upon a Trevet or 
 fome other high Support : It is enough if the Area 
 of it is one Foot fquare. In the Middle of the 
 Hearth, put a fmall Heap of Sand, to fet the Retort 
 upon, left it fhould vacillate. But, the Neck muft 
 be fupported, at the Place where it is neareft to the 
 Belly, with a fquare Stone of a proper Height, placed 
 
 •f In the Work cited, p. 329. 
 
 and in that moil curious and elaborate Work of Mr. Reaumur, end • 
 tied, V Art de convertir le fer forge en Acier. 4to, 
 
 at 
 
Assaying Metals. 3 j i 
 
 at the Extremity of the Hearth, which will at the 
 fame Time hinder the Heat from affeding the Glafs- 
 recipient. Finally have a fmall Recipient, full of 
 cold Water ; let it be perpendicularly fituated, and 
 receive the Neck of the Retort in fuch Manner, that 
 the Extremity of it be hardly one half-inch immerfed 
 into the Water ; as for the reft, it is not neceffary 
 to (lop the Joints. 
 
 2. Let the Retort be furrounded with hot burning 
 Coals, placed at fome Diftance, in Form of a Circle 
 left the Veffel fhould burft by too fudden a Pleat. 
 Then by Degrees bring the burning Coals nearer and 
 nearer, and at laft furround the whole Retort with 
 them and with frefh Charcoal : that it may grow ' 
 llightly red hot. This Fire having been continued 
 for an Hour, let the Retort cool of itfelf. Then 
 ftrike the Neck of it gently, that the large Drops 
 which are always adherent to it, may fall into the Re- 
 cipient : When the Recipient is taken away, wipe off 
 with a Pencil the remaining fmaller Drops, and col- 
 led; them in a low open Veffel fet under, leaving 
 mean-while the Retort in its fir ft Situation. Add 
 this Portion of Mercury to the other already collected 
 in the Recipient. Let the Water be well fhaken firft, 
 and decanted, and the Mercury be poured into a 
 Filtrum, made of a two-fold filtrating Paper j that the 
 fuperfiuous Moifture may be abforbed ; and then 
 weigh it in a Glafs-Veffel. 
 
 3. If you have at Hand a Furnace having a Sand- 
 bath, this Procefs will be much more eafily per- 
 formed ; but the Pot which contains the Sand miift 
 be middling red-hot, and the Retort be able to touch 
 the Bottom of it immediately, nor is it then neceffary 
 that the Retort be loricated. 
 
 Another Method , by Descent, 
 
 When the Apparatus for the lateral Diftillation 
 (N°. 2.) is wanting, you may eafily procure an Appa- 
 ratus by Defcent* Viz, Chufe two Earthen Pots, or 
 * melting 
 
3 ft The Art of 
 
 melting Vefifels, the Orifices of which mu ft be of 
 equal Diameter. Then adapt an Iron-plate to the 
 Orifice of one of the two Pots in fuch Manner, that 
 it may indeed reft upon the Brink of it, but not jut 
 out too much all round: Let this Vefifel have feve- 
 ral Holes bored here and there in it. Put it on the 
 Pavement of the Hearth ; 'pour into it pure Water 
 about two Inches high then ftiut it with the Iron- 
 plate. Put upon this Plate a fmall Vefifel of a leffer 
 Capacity, and full of a Matrix that contains Mer- 
 cury: Next, clofe thefe Vefifels with the fecond Pot 
 inverted : Stop the Joint moft ftriddy with Lute, 
 which muft be applied pretty thick all round. Bury 
 the inferior Pot in Afhes and Stones, placed thick and 
 clofe round it, and heaped up to the very Joint : 
 Put upon thefe Things a moderate Fire, and conti- 
 nue it for about half an Hour, fo that the upper Pot 
 may grow (lightly red hot. The Mercury that lies 
 hidden in the Matrix will dififolve into Vapours, 
 which being ftopt above, will come down when again 
 condenfated : They are preferved under the Water 
 from the too great Heat : For, this does notaamit that 
 Degree of Heat whereby the Mercury may continue 
 in the Form of Vapours, or be refolved into Vapours 
 when once condenfated ; unlefs there is fome Air per- 
 fectly imprifoned in the Vefifel, and fo inclofed as 
 not to be able to perfpire: When the Vefifels are 
 grown cold, open them, and (hake well the Water 
 contained in the inferior Pot, that all the fmall Drops 
 of Mercury difper fed here and there, and adhering 
 to the Sides of the Vefifel, may gather into one Mafs. 
 
 The Ufe and Re a fins of the Procefs . 
 
 i. Mercury intirely volatilifed is obtained pure by 
 Diftillation in a moderate Fire, without any Deft ruc- 
 tion, and even without any Charge, unlefs the di- 
 gefting Fire is continued too long ; provided the 
 Diftillation is performed with Difcretion, and no 
 
 other 
 
Assaying Metals. 553 
 
 other Mineral, efpecially Sulphur, be in the Cafe* 
 For the latter may be mixt with Mercury by a bare 
 Trituration, or even by Heat, and with it makes a 
 black Powder called Phe JEthiops Mineral , which 
 being agitated by a ftrong Fire in a high, nar- 
 row, clofe, glafs or earthen Veftel, is fublimatecl, 
 and produces that Kind of Cinnabar, which is called 
 factitious Cinnabar *, becaufe it is quite like that native 
 Ore of Mercury which goes by this Name ( Part I. 
 § 402.) As for the reft, you muft ufe iri this Dif- 
 tillation the fame Precautions as in Proc. XVIII, 
 where a Procefs almoft like this is defcribed : Nay 
 this may even be performed with the fame Apparatus 
 if you have it at Hand. 
 
 2. We reject here the Diftillation by Afcent ; be- 
 caufe Mercury can hardly be forced up fo high, 
 without fome Danger of the Veflel’s being cracked : 
 Befides, it is in this Cafe difficultly colleded, and 
 Part of it eafily fteals away, on Account of the too 
 great Joints. It fucceeds indeed better by Defcent ; 
 Neverthelefs, even then fome Part of the Mercury 
 either hides itfelf in the rough Surface of thefe Veflels, 
 or penetrates through the Veftel itfelf s becaufe the 
 latter contra£is Chinks pretty often, on Account of the 
 moift aqueous Vapours that make damp the upperVef- 
 fel. Therefore, an Iron- Veftel, if you have any, is pre- 
 ferable: For then, when the Joints are well ftopt, 
 you obtain the fame Quantity of Mercury, as if it 
 was expelled laterally. 
 
 3. In every Procefs to be made by Fire with Mer- 
 cury, the mercurial Vapour is to be avoided by all 
 Means : For breathing too much of it caufes a Sali- 
 vation *, and breathing little and frequently of it caufes 
 Tremblings, Afthma’s, Palfies, and finally Con- 
 fumptions : Nay, it is alfo hurtful to fome, if but ma<* 
 naged with naked and chiefly fweating Hands, 
 
3J4 
 
 The Art of 
 
 PROCESS LIX. 
 
 the reviving of Mercury out of the fulpbureous China - 
 bar-Qrc (Part I. §402.). 
 
 A P P A R A V U $, 
 
 B EAT your Ore extremely fine, and mix it exact- 
 ly with an equal Portion oflronFilings, not rufty : 
 And ufe the fame Apparatus as in the foregoing Pro- 
 cefs, or in Proc. XVIII, but urge it with the Itrongeft 
 Fire that can poflibly be made j the Mercury will 
 thus be revived. 
 
 A’he Ufe and Reafons of the Procefs. 
 
 1. When you have a Mind to feparate both thefe 
 volatile Minerals, you muft fix one of them : Which 
 is done by any fixt Body abforbing Sulphur : Such 
 as Lime, fixt Alcaline Salt of what Kind foever, Re- 
 gulus of Antimony, and chiefly Iron: For, thefe 
 mult adhere to the Sulphur alone, and no way to 
 the Mercury. Thus will you revive any Mercury 
 charged with Sulphur, and even diifolved by Acids. 
 It is obfervable in this Reviving of fulphurated Mer- 
 cury by Iron-filings, that there does not come forth 
 the Odour of Mineral Sulphur, but an tinplealant, 
 and mod lingular Smell, which bbng condenfated into 
 an undtuous rancid Matter, darkens the Sides of the 
 V efiels, and makes the Water turbid, into which the 
 revived Mercury is received. But this Reviving, 
 when accurately performed, fhews that in the belt 
 Cinnabar, Mercury is above feven Times the Quantity 
 of the Sulphur. 
 
 2. Cinnabar may be feparated from Stones by Sub- 
 limation, thus: Beat it to a fine Powder, and put it 
 into a fmall, narrow, glafs, or earthen Cucurbite, 
 die Belly of which, it mull not fill more than one 
 
 third 
 
Assaying Metals. 3 j j 
 
 third Part. Stop the Orifice at Top ; this muft be 
 very narrow, to hinder the free Adtion of the Air. 3 
 Pur this fmall Cucurbite in an earthen-Pot above 
 two Inches wide in Diameter, and gather Sand around 
 this Pot, about as high as the pulverized Ore rifes 
 in the Cucurbite: Then put upon it burning Coals in 
 fuch Manner that the Bottom of the Pot may be 
 middling red hot : Thus will your Cinnabar 2.{cQnd^ 
 and form a folid ponderous Ring, which muft begot 
 out by breaking the Veftel. Obferve, that if you 
 have pure Cinnabar, whether Fadlitious or Native, 
 you muft feparate from it the fuperfluous Sulphur 
 which has not beert thoroughly mixt with the Mercury : 
 This may be done very well by putting your pulve- 
 rized fulphurated Mercury into a Cucurbite, and by 
 expofing it to a Fire not much greater than that which 
 is requifite to fublime common Sulphur : Thus will 
 your fuperfluous Sulphur afcend with a little Mercury, 
 and form a black Cruft all over the Cavity of the 
 Veflel. For Sulphur and Mercury are much more vo- 
 latile when feparate, than the Cinnabar made of both. 
 This Sublimation muft alfo be performed fuddenly 
 with a ftrong Fire •, nor are you to fear any Danger 
 from it, provided you take Care that the upper-Part 
 of the Veflel be not expofed to an exceflive Heat* 
 efpecially if you make Ufe of afmallMatras : For, 
 by that Means the narrow Orifice of it may be ftopt, 
 and the Veflel break afunder with great Violence. 
 
The Art of 
 
 3A 
 
 OF ANTIMON Y. 
 
 PROCESS LX, 
 
 The running down of Antimony out of its Ore , 
 
 APPARATUS. 
 
 x. i HUSE a melting Crucible, or an Earthen- 
 V j pot not glazed, that may contain fome com- 
 mon Pounds of the Ore of Antimony, broken into 
 Email Bits, of the Size of a Hade-Nut: Bore at the 
 Bottom of it a few fmall Ploles, two Lines in Dia- 
 meter : This may be eafily done with a common 
 Wimble, or, if this cannot do on Account of the 
 Hardnefs of the Pot, with a fmall Wedge, which 
 muft be moved Circularly with the left Hand, and 
 mean While inceffantly ftruck with a Hammer in the 
 right. Let the Bottom of this Veffel be received by 
 the Orifice of a fmaller one, upon which it mud be 
 put, and when the Ore is put into it, let it be co- 
 vered with a Tile j and all the Joints be ftopt clofe 
 with Lute. 
 
 2. Put thefe Veflels upon the Pavement of the 
 Hearth, and put Stones all round them, at the Di- 
 llance of fix Inches : Fill this intermediate Space with 
 Allies, fo high as that the inferior Pot be covered to 
 the upper-Brim. Then put frefh and burning Coals 
 upon it, and with a Pair of Hand-bellows excite the 
 Fire, till the- upper- Veffel grows red-hot: Take off 
 the Fire a Quarter of an Hour after, and when the 
 Veflels are grown cold, open them. You will find 
 that the melted Antimony has run through the Holes 
 made at the Bottom of the upper- Veffel, and makes 
 in the inferior one a Regains , from the Proportion of 
 the Weight whereof with that of the Ore, you will be 
 able to know how much fqay be got out of one Centner. 
 
 The 
 
Assaying Metals. 
 
 The Ufe and Reafons of the Procefs. 
 
 1. The Ore of Antimony, which is always found 
 charged with Sulphur, is extremely fufible, and when 
 you continue to© long a Fire that is fomewhat too 
 ftrong, a great Quantity of it is loft in the Form of 
 Fumes : Nay, it burns very bright, on Account of 
 the Abundance of the mineral Sulphur, and it cannot 
 bear the faline reducing Fluxes {Part I. § 159, &c.) 
 Therefore, this Kind of Apparatus is required 
 for the running of it down, that the Aflion of the 
 Air may in fome Meafure be ftopt, and the Anti- 
 mony be in a cold Place fo foon as it is melted : 
 This is done by the Afhes wherein the inferior Veftel 
 is immerfed, which grow red-hot more difficultly 
 than other Bodies, wffiich bear the Fire 2 Where- 
 fore, dry Baths are made with them rather than with 
 Sand or Filings of Iron, when too great a Heat may 
 be detrimental, 
 
 PROCESS LXI. 
 
 The Roafting of crude Antimony (Proc, LX.) or of its 
 Ore , with , and without Additions. 
 
 APPARATUS . 
 
 1 . H U S E an earthen, flat, low Difh, not glazed, 
 Vj and if it cannot bear being made middling 
 red hot, cover it over with a Coat of Lute without : 
 Spread it thinly over with crude Antimony, or with 
 its Ore, beaten to a pretty coarfe Powder, not exceed- 
 ing a few Ounces at once. Put the Difh upon a 
 Fire-pan, having a few burning Coals in it ; increafe 
 the Fire, till it begins to fmoak a little 2 Mean while, 
 you niuft incefiantly move the Powder with a Piece 
 of a new Tobacco-pipe : For this caufes the Sulphur 
 to evaporate the fooner. If you increafe the Fire a 
 little too foon, the Powder immediately gathers into 
 
 A a 3 large 
 
35S The Art of 
 
 large Clots, or even begins to melt. When this 
 happens, take it immediately off the Fire before it 
 melts entirely : Then pulverife it again, and finally 
 make a gentle Fire under- it: Your black fhining 
 Powder will aflame an afh-Colour almoft like that of 
 Earth, and become more refraflory in the Fire ; 
 wherefore, you may then increafe the Fire till your 
 Powder grows middling red-hot ; and let it lad, till 
 it ceafes to fmoak. 
 
 2. If you add to your crude Antimony, or to its 
 Ore pulverized, half or an equal Quantity of Char- 
 coal-duft, and perform the Reft as above, the Read- 
 ing will be done more conveniently : For it does not 
 gather fo eafily into Clots, and melts with much 
 greater Difficulty : When Part of the Sulphur is 
 evaporated, add fome Fat to it at feveral Times, as 
 in Proc. XXXIX. N°. 3. 
 
 Thus, you will fooner finiffi the Operation, and 
 the remaining Calx will not be burnt to an Excefs : 
 However, take Care, not to expofe it thus, to too 
 violent and long-lading a Fire : Otherwife a great 
 Quantity of it evaporates. Nor does it ceafe entirely 
 to fmoak in a great Fire : And it will be enough if 
 growing middling red-hot, it does no longer emit 
 the unpleafant Smell of the Acid of Sulphur. 
 
 3. This Roafting is moft fpeedily performed by 
 another Method with Nitre ; if for Inftance you 
 pound Antimony charged with Sulphur,' with an equal 
 Weight of Nitre, and throw it at feveral Times, 
 and not above a few Drachms at once, into a deep 
 earthen Veffel not glazed, and middling red-hot : A 
 ftrong Detonation will be made, and the Mixture 
 will be changed into a half-vitrified Mafs, of the 
 Colour of Liver : Take it out, grind it, and with 
 warm W T ater waffi off ( Part I. § 473. &V.) the 
 Salt that lies hidden in it. The remaining Calx is 
 called Crocus Metallorum , or He par Antvnonn (Liver 
 of Antimony.) 
 
Assaying Metals. 3 jp 
 
 The Ufe and Reafons of the Procefs . 
 
 i. No Roafting requires fo great a Patience as that 
 of Antimony loaded with Sulphur. For, the regu- 
 - fine Part of it is, by the mineral Sulphur, rendered the 
 moftfufibleofall Metals and Semi-metals, Arfenick ex- 
 cepted : But, if it melts, then a further Exhalation of 
 the Sulphur cannot be procured by continuing the 
 Fire, otherwife than by a great Lofs of the Regulus 
 itfelf ; which being not of itfelf very well ftxt in the 
 Fire, is the more eafily carried away by the Sulphur 
 joined to it, fo that it will be entirely diffipated along 
 with it, though it is at leaft above three Times the 
 Quantity of the Sulphur. Therefore, you mufl road: . 
 but a fmall Quantity of it at once, and extend it 
 wide, and ftir it perpetually : Becaufe, when it is 
 too finely pulverized, or heaped up only a few Lines 
 thick, it will not be feen to exhale any Thing, unlefs 
 you ftir it, though it already begins to melt at Bottom. 
 For, the Vapours of the Sulphur pading through the 
 Interflices of the lefs hot Powder which is upon them, 
 condenfate : Whereby the Powder becomes of a yellow 
 Colour. The Roafting is done a little more eafily 
 without adding any Thing to the Ore of Antimony ; 
 efpecially if you prevent the Melting in the Begin- 
 ning. As for the Red:, this Method is hardly made 
 ufe of, except when you have a Mind to make com- 
 mon Glafs of Antimony, which is made with the 
 already prepared Calx of crude Antimony. For In- 
 fiance, you put this Calx in a ftrong compadl Cru- 
 cible, and make your Fire gradually, leaving the 
 Veflfel open in the Beginning *, that the Sulphur dill 
 remaining, may be entirely expelled : Then increafe 
 the Fire, till the Ore melts, theVeffel being covered, 
 to keep the Charcoal from falling into it, which re- 
 duces Glafs to a reguline femi-metallick Subftance, 
 When melted, leave it fo for a Quarter of an Hour, 
 or longer, if the Veffels can bear it : Then at {ail, 
 pour it out upon a flat, dry, warm Stone : It will 
 be a Glafs more or lefs tranfparent, and of a deep 
 
 A a 4 yellow 
 
3^0 The Art of 
 
 yellow Colour j according as the Roafting and Melt- 
 ing have been performed more perfe&ly, and in a 
 neater Manner. 
 
 2. Kunkel has made Ufe of another Method of 
 roafting crude Antimony, in order to prepare a 
 greater Quantity of the fimple Regulus of Antimony : 
 For, a greater .Quantity of it is obtained by that Me- 
 thod than by any other j for, during this Roafting 
 the mineral Sulphur carries off a fmall Quantity of it. 
 But, if you urge it with a Fire too long lading, and 
 fo ftrong as that it may come almofl to the Degree 
 of a reducing Fire, fome Fart of it is diffipated. 
 For Inftance, the Calx of Antimony which is of itfelf 
 pretty well fixt, or the Glafs of it, is difpoled to a 
 Reduction, when you urge it by a frequent Addition 
 of a Phlogifton ; now, the Regulus is diffipated by a 
 Fire a little too ftrong ; therefore, the Glafs or Calx 
 of. Antimony is by this Method rendered volatile. 
 
 3. Nitre ground with Antimony charged with 
 Sulphur, detonates with the fulphureous Part, and 
 confumes it as to the Phlogifton •, but the Acid of 
 Sulphur being agitated by a ftrong Fire, and meet- 
 ing the Nitre, the latter expels the acid Spirit of the 
 former in a gentler Manner, and unites itfelf with 
 the fixt Bafts of the Nitre, and together with it con- 
 llitutes a middle vitriolated Salt, perfectly like 
 Tartar vitriolate, or like Salt Polychreft, which 
 being waffied off with warm Water, there re- 
 mains the pure Calx of Antimony half vitrified. But 
 if you ufe more Nitre, for Inftance, twice or thrice 
 as much for the Detonation, the Calx becomes yellow 
 or white, and is much burnt *, in the firft Cafe it is 
 called Emetick^ and in the fecond Biaphoretick Antimony. 
 
 4. The Separation of Sulphur may likewife be 
 performed by feveral liquid Dififolutions, and by 
 Precipitations : For which Reafon it is called by 
 fome Calcination or Roafting the moift Way. Thus, 
 for Inftance, Aqua Regis , and Spirit of Nitre, efpe- 
 cially when they are concentrated, erode the reguline 
 fubftance of Antimony out of the Sulphur with a 
 
 moderate 
 
Assaying Metals. 361 
 
 moderate Heat, and diffolve it; while they leave the 
 Sulphur untouched : When the Solutions decanted 
 are precipitated by a Solution of fixt alcaline Salt, 
 and edulcorated, they produce the Calx of Anti- 
 mony *, which is nothing elfe but the intire Regulus 
 diftolved by the Acids. 
 
 PROCESS LXIL 
 
 The Reduction of the Ca lx’s of Antimony (Proc. LXI.) 
 into a femi-metallick Regulus. 
 
 APPARATUS. 
 
 M I X fome Calx of this Kind with a quarter Part 
 of the black Flux, and put it into a Crucible ; 
 cover the Veftel with a Tile ; make the Fire as quick- 
 ly as the VefTels can bear it, but not greater than is 
 neceftary to melt the Flux itfelf : When the whole 
 has been well in Fufion for half a Quarter of an Hour 
 (which may be tried with a Tobacco-pipe taking off 
 the Tile) pour it into the melting Cone, which muff 
 be warm and done over with Tallow : Then imme- 
 diately ftrike the Cone feveral Times ; When you 
 have inverted the Cone, and fhaken out the Matter 
 grown cold in it, you will find at the Point a Regulus 
 like (Part I. § 77), and at the Bafis a faline Scoria. 
 If you have a Mind to reduce or try a fmall Quantity 
 of it, you rnu ft do it either upon a Charcoal with 
 the cementatory or blow-Pipe {Parti. § 258) ; or 
 in theManner prefcribed with regard toTin Proc . L 1 L 
 
 The Ufe and Reafons of the Procefs. 
 
 i f The Reduction of the Regulus out of the Calx of 
 Antimony is performed the moft eafily of all Metals, 
 It is enough, if you add to the Calx's of Antimony 
 only Charcoal-duft, or any Kind of Phlogifton what- 
 ever : Nor need you have Recourfe to a melting 
 Menftruum , on Account of its Fufibility. But there 
 
 happens 
 
362 The Art of 
 
 happens fome Difference, between the Calx's prepared 
 ( Proc . LXI.) for, more or lefs Regulus may be re- 
 duced out of one or the other, not only with regard 
 to the crude Antimony, but alfo with refpedt to the 
 Calx you make Ufe of. For Inftance, you will ob- 
 tain, after the Reduction, above one Pound of Re- 
 gulus * out of one Found and an half of crude Anti- 
 mony either alone, or roafted with Charcoal-duft ; 
 unlefs you have committed fome Miftake, by making 
 too great or too long lafting a Fire, or by ufing im- 
 pure Antimony : For, by the firft Method, you will 
 prepare pure, unmixed Calx of Antimony, by the 
 Diffipation of the mineral Sulphur and the Phlogif- 
 ton *, but you cannot prepare any Calx ftrictly fo 
 called by the fecond Method, that is, with Charcoal- 
 duft ; becaufe, a pure Fhlogifton, that is, one dedi- 
 cate of Acid of Sulphur, has been continually fup- 
 plied, during the Diffipation of the mineral Sulphur : 
 Therefore, in this Cafe, the reguline Part cannot 
 have been burnt into a true Calx j but, being only 
 feparated, it had merely a falfe Appearance of a Calx : 
 For, if you take this out of the roafting Fire in 
 proper Time, and expofe it to a melting Fire in a 
 Veftel ; it does not melt into Glafs, but into a Re- 
 gulus. , not fo abundant however, as if freffi reducing 
 Powder had been added. But, it is always proper, 
 when you are to prepare an abundant Regulus , or a 
 line Glafs, to chufe that Part of the crude Antimony, 
 which in the running down ( Proc . LX.) got into the 
 lower Part of the Recipient *, for it is purer, more 
 reguline, and lefs fulphureous ; whereas that in the 
 upper Part proves lefs reguline, and more fulphureous 
 and terreftrial : On which Account it appears lefs 
 compact and ihining than the foregoing, and much 
 lighter, becaufe full of ftnall Bubbles. 
 
 2. Before you reduce the Calx's made by a Detona- 
 tion with Nitre, you muft previoufly edulcorate them 
 perfedlly : Otherwife, you obtain a much leffier 
 
 Quantity of Regulus , with regard both to the crude 
 Antimony and to the Calx itfelf j becaufe, when you 
 
Assaying Metals. 
 
 add a Phlogifton, the vitriolated Salt ad- 
 hering to it, turns to Liver of Sulphur, which dif- 
 folves the Regulus , and in very great Part retains it 
 joined to itfelf. Nor can you, however, thus ob- 
 tain fo much Regulus , as when the Calcination is 
 made either by itfelf, or with only adding a Ph!o~ 
 gifton : For during fo violent a Detonation, a great. 
 Quantity is flung out of the VefTd, or vanifhes away 
 into Fumes : Befides, fome Part of the reguline Sub- 
 fiance is alfo wafhed off along with the Salt ; which 
 is very plain, when you pour wine-Vinegar upon 
 the Water wherewith the Edulcoration has been 
 made : By Means of which you precipitate a red 
 Powder, called Sulphur Auratum, which is compofed 
 of the Sulphur of your Antimony joined to the femi- 
 metallisk Part. For, the Phlogifton of the crude 
 Antimony, is not totally confimied by an equal Weight 
 of Nitre : But, if you add twice or thrice as much 
 Nitre ; then indeed, it is totally confumed : How- 
 ever, a femi-metaJlick Part remains fo ftridly united 
 with the Salt, that it runs through the Filters. As 
 this laft part is obtained out of the warm Difiblution, 
 in the fame Manner as the Lac Sulphuris and the Sul- 
 phur Auratum are got by Precipitation it has been 
 but improperly called fixt Sulphur of Antimony : For 
 it is deprived of all inflammable Matter, on which 
 Account it is of a white Colour. It is for the fame 
 Reafon, that the Sulphur called fixt Sulphur of An- 
 timony, being melted with a very ftrong Fire, turns 
 into Glafs, of a much lighter Colour, and lefs vio- 
 lent in its Effects, than that which is made of Crocus 
 of Antimony, becaufe it is almoft the fame as Glafs 
 made with Calx of Antimony procured without any 
 Addition. 
 
 3. From what has been faid the Reafon is plain, 
 why fimple Regulus of Antimony is prepared with 
 fome Lofs the ordinary Way. For a Mixture 
 of Tartar, Nitre, and crude Antimony, detonates 
 in a ftrong melting Fire 5 but feizes upon the Nitre, 
 which reduxes the Phlogifton of theTamr as well as the 
 
 mineral 
 
3^4 7 $<? Art of 
 
 mineral Sulphur; for this Reafon the mineral Sul- 
 phur is not intirely confumed : And if it were, the 
 Acid of it detained by the alcaline fixt Salt here pro- 
 duced with it, and joined with the Phlogifton of the 
 Tartar, would neverthelefs make a copious Hepar 
 Sulphuris , whereby a great Deal of the Regulus would 
 be retained. This appears evidently, if you add to 
 the Scoria half its Quantity of Filings of Iron, and 
 melt it a fecond Time : For then, the Regulm re- 
 maining in the Scoria, will fubfide to the Bottom of 
 the Cone. Likewile, a great Deal of Sulphur Aura - 
 turn is precipitated, if this Scoria is edulcorated with 
 warm Water, and Vinegar poured upon the Diffolu- 
 tion. A great Quantity of reducible Flowers is alfo 
 rejected during the Detonation. And as the Mixture 
 muft be put at feveral Times into the Fire, aad muft 
 be left the longer in it, the Veffel being mean while 
 open *, a great Deal of this volatile Semi-metal is 
 confumed, and on this Account, there remains but 
 a very fmall Part of the Regulus , at the Bottom of 
 the melting Cone. 
 
 PROCESS LXIIL 
 
 The Precipitation c/Regulus of Antimony, with Metals(P.\» 
 § 147. Coroll. 3.) Iron is taken for an Example. 
 
 APPARATUS. 
 
 1. yj U T one Part of Iron not ruily into a Crucible 
 jL made thoroughly white-hot in a Wind Fur- 
 nace. But you muft chufe Bits of Iron not very 
 thick, for Inftance, fmall Plates, Nails, or even 
 frefti Filings. When the Iron is perfectly white-hot, 
 add to it, the double Quantity of crude Antimony 
 at feveral Times, left the Veffel fhould break afun- 
 der by the too fudden Application of a cold Body: 
 You will fee youf Iron diffolved by the melted Anti- 
 mony : This done, add to it at different Times, of 
 
Assaying Metals. 3 6 $ 
 
 Nitre, or of any fixt alcaline Salt whatfoever, a 
 quarter Part, with refped to the crude Antifnony ; 
 leave all thefe Things in the Fire for a few Minutes 
 more, that they may melt very thin together ; then 
 pour them into a melting Cone, in which, by ftriking 
 it, the whole regulineMafs contained in the crude Anti- 
 mony, will fubfide : Separate the Scoria’s which will 
 be hard : Expofe them to a free and fomewhat moift 
 Air, and in a few Days they will of themfelves fall 
 into a Powder. 
 
 2. Put the Regulus a fecond Time into the Cru- 
 cible, add to it one quarter Part of frefh crude Anti- 
 mony, cover the Crucible with a Tile, and melt the 
 Matter with a Fire not violently excited : When the 
 whole is in Fufion, add at feveral Times one fixth 
 Part of Nitre, or very dry fixt alcaline Salt, and a 
 few Minutes after pour out the Mafs well melted. 
 
 3. The Regulus may be melted a third or a fourth 
 Time with a very little Nitre : This will detonate, 
 and at the fame Time affume a refractory Nature : If 
 at laft you ufe the ftrongeft Fire, your Regulus , when 
 poured out, will be finally marked with a Star, but 
 a great Portion of it will be confumed by the Nitre 
 and the Fire in thefe laft Fufions. 
 
 21 be Ufe and Reafons of the Procefs . 
 
 i. If you precipitate Regulus of Antimony, with 
 Metals (Parti. §147. Coroll. 3.) you will have 
 the Whole of it without any Lofs *, but, it will be 
 tainted by a confiderable Mixture of the precipitating 
 Metal: But, a greater Quantity of the Metal joins to 
 it, as the Adion of the Sulphur upon it is flower, and 
 as the Sulphur itfelf melts more eafily with t\\tRegu° 
 lus of Antimony. Thus, in every Precipitation by 
 Fufion of Metals by Means of other Metals, the 
 precipitated Body partakes of the precipitating one, 
 except Lead alone, to which the Iron that precipitates 
 it never mixes ; becaufe both thefe Metals do not 
 diflblve each other in the Fire, The firft Scoria 
 
 which 
 
3 66 The Art of 
 
 'which is produced in the prefent Cafe, is Iron dif- 
 foived by the Sulphur of Antimony *, for which Rea- 
 fon this Scoria is of a very hard Nature, and very 
 difficult to be feparated from the Regnlus. To make 
 it feparate eafily you muft add an alcaline Salt, or al- 
 calefcent Nitre, whofe Acid is expelled by that of 
 Sulphur: This Alcali difTolves the Scoria, and makes 
 it loft and diftoluble by the Moifture of the Air. 
 Likewife, the Hepar Sulphujis produced in the Ope- 
 ration does alio efftcacioufty diflbive the precipi- 
 tating Iron, and retains it united to itfelf, left the 
 Part of it which is diftolved by the Sulphur jfhould 
 again unite itfelf ib eafily to the Regulus of the 
 Antimony. 
 
 2. A fecond Fufion is made with crude Antimony 
 and Nitre, or with frefh alcaline Salt, to the End 
 that the Iron remaining in the Regulus may be fur- 
 thermore feparated. For Inftance, the Regulus which 
 is much more refractory in the Fire than the crude 
 Antimqny, is diftolved by the Sulphur of it, and at 
 the fame Time this Sulphur meeting the Particles of 
 the Iron contained in the Regulus , and having aban- 
 doned the reguline Portion of the Antimony, joins 
 with them , when joined, making a lighter Mafs, 
 it is caft up at Top, and forms a Scoria, in which a 
 great Deal of Antimony is adherent, for want ofa 
 precipitating Body. The Salt added over and above 
 has the fame Effect as N°. i. But, it is eafy to con- 
 ceive, that in this fecond Fufion, the Regulus is 
 tainted with fome fmall Quantity of Sulphur. 
 
 3. To con fume this Sulphur intirely, it is neceftary 
 feveral Times to repeat the Fufion ; which is not 
 made fo well with alcaline Salt, as with Nitre : For 
 the latter being flung upon a Regulus boiling by the 
 Violence of the Fire, detonates with the Sulphur that 
 lies hidden in it, and at the fame Time becoming 
 Alcaline by the Strength of the Fire, it aftumes a 
 refractory Nature, which is increafed by a fait like 
 Tartar vitriolate, which is produced by the Acid of 
 the Sulphur, and the alcaline Part of the Nitre. 
 
Assaying Metals. 3 67 
 
 Nor is the pure Phlogidon, that forms the Regulus , 
 free from the Force of the Nitre : Wherefore, a 
 great Deal of the Regulus is calcined, and, together 
 with the very drong alcaline Salt here produced, is 
 changed into a Glafs, which being intermixt with 
 the Scoria’s, is the Caufe of their amber or lafffon- 
 Colour : This Colour is communicated to Glades by 
 Arfenick and the Calx of Antimony, unlefs they are 
 burnt too long in the Fire. Thofe who repeat the 
 Fufion feveral Times with Nitre, at lad confume the 
 Regulus to no Purpofe, becaufe that, which remains 
 in the End, never becomes malleable. Nor does the 
 Prefence of mineral Sulphur at all require a frequent 
 Repetition of the Work ; for, nothing of it can be* 
 iliewed in a Regulus once or twice purified. 
 
 OF BISMUTH. 
 PROCESS LXIV. 
 
 The melting Bifmuth out of its Ore ; 
 
 APPARATUS . 
 
 i. iQlfmuth-Ore may be melted with the fam zAp- 
 JL> paratus ufed for the melting crude Antimony 
 out of its Ore ( Proc . LX). 
 
 2. The very fame may be done in the melting 
 Furnace, if you let it upon its Bottom with the Bed, 
 and a Recipient outwardly applied to it ( Proc «. 
 XXXV). In this Apparatus , you mud break your 
 Ore in finall Bits, and mix it by Strata with Charcoal, 
 or with very foft broken Pieces of Wood. But, 
 your Bellows mud be loaded with a very fmall 
 Weight, that their Blad may be very gentle ; nay, 
 the Fire may even be diffidently excited for this Fu- 
 fion without Bellows, by putting only the Cover and 
 the Funnel a-top of the Furnace : For Bifmuth will 
 not bear fo great a Fire, to make its dony Matrix 
 
 turn 
 
3 68 The Art of 
 
 turn to Scoria. The Ore being thus run down into 
 the inward Bed, mud: be ftirred now and then with 
 a Poker, that the fmall interfperfed Grains of Bif- 
 muth may be driven out, and run into the outward 
 Bed, where they join with the Red into a Regulus. 
 When the femi-Metal is melted, take away the 
 Drofs,with a Sort of wooden Scraper or Hough : And 
 removing the Body of the Furnace, take the Ore re- 
 maining in the inward Bed, and extinguifh it in a 
 VeiTel full of Water, and then walk off and rejedt 
 the fmalieft Particles, collecting only the larger Ones, 
 to melt them together in a gentle Fire. 
 
 3. You may alfo run down Bifmuth in an earthen 
 or an iron-Veflel. Fill this with your Ore broken 
 in fmall Pieces, and make a wood-Fire all round : 
 And thus you will, by the fame Method as before, 
 eafily obtain Bifmuth out of a fufible Ore, efpecially 
 out of a rich one. 
 
 4. You may alfo beat your Ore to a very fine 
 Powder, with the black Flux, glafs-Gall, and com- 
 mon Salt, in a clofe Veffel, like the Ore of Lead or 
 of Tin, and melt it in a middling Fire, having a 
 Draught of Air : But, as this femi-Metal is de- 
 ilrudtible and volatile, you mud, as quick as pof- 
 fible, apply to it that Degree of Fire which the Flux 
 requires to be melted, and foloon as it is well melted, 
 the Veffel mud be taken out of the Fire, and when 
 it is grown quite cold, and broken, you will find 
 your Regulus . 
 
 'The Ufe and Reafons of the Procefs. 
 
 1. Bifmuth is found in its Matrix's, either pure 
 and in a femi-metallick Form, or in a State of Ore, 
 when Arfenick is joined to it : And as this femi- 
 Metal is at the fame Time mod fufible ; on this 
 Account, it does not want the Adidance of any 
 melting Menftruum , or of any reducing Phlogidon ; 
 but may be run down out of its Ore, by only a fi Tu- 
 ple Fufion, and with a gentle Fire. If there is any 
 
 fmall 
 
Assaying Metals. 369 
 
 fmall Quantity of Arfenick in it, the free Air and 
 Fire diflipate it. But you can ufe this Fufion, only 
 with rich and very fufible Ores. 
 
 2. If the Ore is very refradtory, and the defired 
 femi-Metal lies hidden in a fmall Quantity, within 
 very narrow Interftices, then a Fire fomewhat 
 ftronger is required, that, being more attenuated, it 
 may extricate itfelf : But, in this Cafe, it will be en- 
 tirely diflipated, unlefs you apply to it a fmoaking, 
 reducing Fire, which mu ft be at the fame Time mo- 
 derate, and in fome Meafure confined from it. For as 
 Bifmuth is eafily reduced by the Phlogifton of the 
 Fuel of the Fire, it is alfo foon diflblved into Fumes 
 and fublimed. 
 
 3. You will obtain a much greater Quantity of 
 Bifmuth, if you melt your Ore with the black Flux, 
 glafs-Gall, and common Salt, in clofe Veflfels : The 
 Reafon of this is, that the Matrix of Bifmuth, or of its 
 Ore, is fooner diftblved than vitrified by the Force of 
 the Salts : Wherefore, the Particles of Bifmuth being 
 then confined, may be more perfectly precipitated ; 
 whereas, on the contrary, a great Deal of it remains 
 in the Chinks of the Matrix , in the foregoing Eliqua- 
 tions ; becaufe a Matrix of itfelf very refradtory, is, 
 by the Volatility of Bifmuth, hindered from turning 
 to Glafs with Fire alone. Befides, the free Adtion of 
 the Air, being excluded, and a reducing Body added, 
 the fame Quantity can never be diflipated, as when 
 the Air and Fire adt freely upon it, and a little of a 
 reducing Body comes to your Afliftance. Moreover, 
 Arfenick is moft commonly joined in no fmall Quan- 
 tity with Bifmuth : But this (as will afterwards ap- 
 pear in the Procefles to be made with it) is reduced 
 and precipitated, with faline reducing Fluxes, into 
 a femi-metallick Regulus , not unlike Bifmuth, more 
 fixt than Arfenick itfelf, fometimes volatile enough, 
 which, neverthelefs, meeting another Metal or femi- 
 Metal, mixes with it, and is fixt. 
 
 4. The Cobalt of Arfenick ( Part I. § 325), of ah 
 moft every Kind, has fomething of Bifmuth in it : 
 
 B b And 
 
37° The Art of 
 
 And as for the Reft, there is moft commonly no other 
 Difference, between the Ores of Arfenick and thofe 
 of Bifmuth, but the greater or lefs Proportion of 
 either of them mixt with the other. But, when there 
 is but a fmall Quantity of Bifmuth, it cannot be run 
 down with any Profit, though Bifmuth be not a 
 Thing of the loweft Value. But, when the Caput 
 Mortuum of Cobalt remaining after the Roafting of 
 it, is melted with Flints and pot-Afh, to make with 
 it the Glafs called Smalt *, a Regulus is produced 
 much like Bifmuth, though different from it in fome 
 Meafure. See Part I. § 407. Schol. 
 
 OF ZINK. 
 
 PROCESS LXV. 
 
 Zink (Part I. § 14.) is fublimed into irreducible Flowers, 
 
 APPARATUS. 
 
 l IF you put a few Ounces of Zink into a Pot, 
 I or a fmall earthen Cucurbite, and place this 
 Veffel horizontally, or rather with its Orifice upwards, 
 in a reverbatory Furnace, fitted for Diftillations of 
 Oil of Vitriol, or others requiring the ftrongeft 
 Fire, and fit to it, by means of an Aludel, a large 
 glafs-Recipient, in fuch Manner, that you may look 
 within through its tranfparent Bottom, into the 
 Cavity of the fmall earthen Cucurbite ; after having 
 carried your Fire to a very great Degree of Bright- 
 nefs, you will fee your melted Zink fuddenly take a 
 Flame of a green Colour, and at the fame Time a 
 very thick grey coloured Smoke arife, which will be 
 pulhed forward into the Recipient, like Cobb-webbs 
 fluttering in the Air, and cover the whole Infide of 
 it, and a little after hinder you alrnoft entirely from 
 feeing any further. After you have continued your 
 Fire for an Hour or two ; let the Veffels grow cold, 
 
 and 
 
Assaying Metals. 371 
 
 and when you open them, a very thin Fume of the 
 garlick-like Smell of Arfenick, will break forth, and 
 vanifh very foon after. The Recipient will be co- 
 vered over on the Infide, with a Coat of very foft, 
 impalpable, and light Flowers of a bluifh white Co- 
 lour : But, the Aludel will be incruftated, partly 
 with the more ponderous blue Flowers, confiding of 
 coarfer Grains, and partly with the folid Sublimate 
 produced from the fmall Drops of melted Zink en- 
 tirely fublimed, the grey Flowers of the dedroyed 
 Zink being every where interpofed. You will 
 find in the earthen Vedel itfelf fomething {till of the 
 Zink covered and fheltered as it were with a Blider, 
 from being entirely burnt, or fublimed : Which is the 
 Flowers burnt, and aimed half vitrified. If you ufe 
 a Fire fo gentle, as that the Zink may not take 
 Flame ; hardly any Thing will evaporate in Form of 
 Zink, or of Flowers. 
 
 2. If you expofe to a middling Fire having a 
 Draught of Air, two or three Ounces of Zink, in an 
 open earthen Cucurbite, upon a done Support, as 
 one places a Crucible ; Zink takes Flame much fooner 
 than in a clofe Vedel, and fills the whole Cavity of 
 the VelTel with very white Flowers like Locks of 
 Wool : But, fo foon as the Vedel is full with thefe 
 Flowers, fo as that you can no longer fee the Surface 
 of the Zink ; the Flame, which was very bright be- 
 fore, gradually diminifhes, till it at lad ceafes entirely ; 
 fo that the Zink can no more be brought to a DeBra- 
 gration, not only with the fame, but alfo with a d rang- 
 er Fire. If then you take away the Flowers with a 
 fmall iron Ladle, and free the Surface of the melted 
 Zink at the Bottom of the Vedel, from thofe 
 which covered it ; a bright Flame is again pro- 
 duced as before, and in a few Minutes the Cavity of 
 the Vedel is filled with Flowers of the fame Kind : 
 If you continue this Work in the fame Manner ; at 
 lad all your Zink, provided it was pure, is refolved 
 into a great Quantity of very white Flowers ; nor does 
 a great Deal of it dy away, unlefs the Fire adls too 
 
 B b 2 violently. 
 
37 2 The Art of 
 
 violently. But, the Flowers apply themfelves pre- 
 fently to the Sides of the Vefiel, and even adhere to 
 the Surface of the Zink itfelf ♦, nor can they after- 
 wards be further changed, or rendered volatile, by the 
 fame Degree of Fire by which the Zink has been 
 burnt and fubiimed ; fo that by this Method you 
 may prepare abundance of Flowers of Zink in the 
 moil convenient and neateft Way. Neverthelefs, you 
 may alfo adapt Aludels, or only cylindrical Segments, 
 to the Orifice of your Vefiel : By which Means you 
 will obtain a little more abundant and more fubtile 
 Flowers. But, that the Surface of your Zink may 
 be now and then freed from the Flowers that cover it, 
 and the whole Cavity of the inferior Vefiel be ren- 
 dered free, it is proper to make a Hole at the Side 
 of it, fo large as that you may take out through 
 it the Sublimate, with a fmall Ladle, as was faid 
 before. 
 
 3. When you apply fuddenly to pure Zink the 
 
 flrongeft Fire with a Draught of Air ; the whole of 
 it vanifhes : Nor is it confined by the Crucibles 
 
 being ftopt with Lute. For Inftance, if you put an 
 Ounce of pure Zink into a fmall Crucible covered 
 with a fmaller inverted one, flopping all the Joints 
 well with common Lute, and put it into a wind- 
 Furnace, furrounding the whole Vefiel with Charcoal 
 and burning Coals, and excite the Fire to its 
 utmolf Degree, by applying the Bellows to the 
 bottom-part of the Furnace, and continue it for 
 half an Hour, when afterwards you take out the 
 Vefiel, you will not perceive therein the lead Foot- 
 deps of Zink, or of the Flowers of it. The very 
 fame Thing happens with the other Semi-metals, 
 though not fo quickly. 
 
 4. If you mix the white Flowers of Zink, or the 
 blue and grey ones calcined to a white Colour in a 
 middling open Fire, with common reducing Fluxes, 
 fuch as are the black Flux, and the white ( 'Part I. 
 § 162. &c .) adding fluxing Salts to them, they 
 cannot afterwards by any Means be reduced in the 
 
 lame 
 
Assaying Metals. 373 
 
 fame Manner as the other Metals and Semi-metals, 
 by being expofed to a melting Fire. Nor has any 
 Method hitherto been invented, or communicated at 
 lead by the Inventor, whereby the Flowers of Zink 
 may be reduced to a fe mi- m eta Hick State : Since 
 they rather are fixt fo far in the Fire, as to be vitri- 
 fied with Fluxes. 
 
 5. When the grey and blue Flowers are melted 
 with fome very fufible Salt, though this be impreg- 
 nated with none or at lead very little Phlogidon, 
 you may obtain out of them, I fhall not fay, reduce 
 from them, a few Grains of Zink. For Indance, if you 
 mixt by Trition the Flowers jud mentioned, with „ 
 Glafs-gall, or the caudick alkaline Salt which is pre- 
 pared out of the infpififated Lye of Pot-ailies and 
 Quick-lime, and expofe them in a Crucible, to a 
 Fire not greater than is necelfary to melt the Salt 
 well, and then take them prefently out of the Fire, 
 and fling the Crucible with the Salt grown cold into 
 a clean Bafon full of warm Water, you will find, 
 after having waflied ofr the Salt and the lighted 
 Drofs, a few and very fmall Grains of Zink, mod 
 commonly covered with yellow Cruds, precipitated 
 here and there at the Bottom of the Veflel, and not 
 to be colle&ed without a tedious Labour. Thefe 
 Grains of Zink, if not pretty large, hardly melt in- 
 to a Regulus , but perifh intirely, being refolved by 
 the Fire into fmall Flames and Flowers. But, you 
 mud not for this Purpofe ufe the black or the white 
 Flux, becaufe they require fo great a Fire to be 
 melted, that the fmall and widely difperfed Particles 
 of the Zink, are burnt much fooner, than they can 
 be precipitated by the concomitant Matters melted 
 fufficiently thin : Which is very plain from the fmall 
 coloured Flames and Flowers that break forth. Nor 
 does the above-mentioned very acrid Salt bear the 
 Addition of a Phlogidon ; nay, when already 
 melted, if you add the lead Fat to it, it immediately 
 grows folid, and requires a Fire equally drong as the 
 black Flux does, to be brought again to a State of 
 
 6 b 3 Fufioa s 
 
374 Art of 
 
 Fnfion : And this feems to be the Caufe why Grains 
 of Zink fo difficultly run into one reguline Mafs ^ be- 
 caufe this Salt, while it abforbs the Phlogifton where- 
 with Zink is full, forms thofe fmall yellow Crufts 
 round the Grains of the Zink, which Crufts are dif- 
 ficult to be melted. 
 
 The Ufe and Reafons of the Procefs. 
 
 1. The Reafon is plain from this fingular Pro- 
 perty of Zink, why we try in vain, by Pre- 
 cipitation by Fufion, with the Affiftance of faline, 
 oily, reducing Fluxes, to produce Zink from its Ores 
 hitherto known in Europe , in the fame Manner as 
 we commonly ufe for other Metals and Semi-metals. 
 It is as plain, why it can much lefs be collected in 
 the Beds of the Furnaces ( Proc . XXXIV), by a 
 Stratification with Charcoal, by Means of the Vitrifi- 
 cation of the terreftrial Bodies adherent to it, and of 
 a violent Fufion, excited with the Biaft of Bellows ; 
 but ought rather to be collected and fublimed ( Part I. 
 § 409. &c.) in Places pretty cold, and not much 
 expofed to the Action of the Wind. 
 
 2. Mean while, the Zink that lies hidden in Ores, 
 or other compound factitious Bodies, betrays its Pre- 
 fence by the Flowers which it emits from itfelf when 
 urged by a ftrong Fire, and by the golden citron- 
 Colour it gives to Copper. For both thefe Effects 
 were never produced by any other known Body, as 
 much as can be collected from all Experiments : 
 Wherefore, we may as furely conclude the Prefence 
 of Zink from them, as we furely conclude that of 
 Iron from the Adtion of the Magnet. 
 
 3. A ftrong open Fire, and a fublirnatory Appa- 
 ratus ( Part. I. § 462), are required to coliedt thefe 
 b lowers : However, you muft with great Care avoid 
 the too- violent Paftage of the Air through the Fur- 
 nace, and the leaft Biaft of it through the fublima- 
 tory Pots : For the fofteft and lighteft Flowers are 
 diffipated by the leaft Motion of the Air, There- 
 
Assaying Metals. 375 
 
 fore* it is proper to ufe large Aludels : By this Me- 
 thod you will obtain Abundance of Flowers out of 
 Calamine, efpecially if you break it into fmail Bits 
 of the Size of a Pea, and lay it in Strata with Char- 
 coal j when thofe are confumed, you colled: it out 
 of the Afh-hole, and put it in again with frefh Char- 
 coal. Thus it is fometimes for a very great Part 
 refolved into Fumes and Flowers, according to its 
 different Degrees of Purity. Thefe Flowers firft 
 come forth bluifh, then more and more grey, and 
 white at laft. They are vaftly like the Flowers pro- 
 duced out of Zink itfelf, and called Nihil album , Ni- 
 hil gryfeum , according to the Difference of the Colour, 
 which neverthelefs depends on the Impurities mixt 
 with them, or (if the Operation has been neatly per- 
 formed) on very fmail Portions of Zink not yet de- 
 ftroyed, or from both Caufes. For, Zink may indeed 
 be colleded out of them, according to Appar . N°. 5. 
 and if they are again made red-hot for a few Mi- 
 nutes, they grow perfedly white *, becaufe Zink is 
 not very conftant in the Fire. They are alfo called 
 Pompholyx : And we fhall leave to others the Care of 
 finding out, whether it is the fame as the Pompholyx 
 of the Ancients, and whether the Spodium of the 
 Greeks finds alfo its Place here : But, whoever has a 
 Mind to lift thefe Matters, let him not undertake 
 it without having Recourfe to Experiments ; left he 
 fhould afterwards give us Words for Things *, nor 
 pretend to reconcile the various Opinions of all the 
 Authors, many of whom have ftuck to Words much 
 more than to Things. 
 
 4. Pompholyx and Nihilum (Nil) are indeed fold 
 in Shops, but feldom genuine : For, as they are 
 collected in fmail Quantity, they are adulterated in 
 a thoufand different Manners : While the feveral 
 Kinds of light white Marls, the Parget made of 
 burnt Spaad, and the white, fat, Boly Earths, fuch 
 as the Fullers-earth, the Heffian- earth, 6?r. or even 
 compound Maffes, made feveral Ways with 
 thefe, both by Nature and Art, are fold for the 
 
 B b 4 white' 
 
3 76 The Art of 
 
 white Nil of the Shops : See Henckelii Pyritolog . 
 
 p. 58 1. Which Fraud is not always ealily detected : 
 Neverthelefs, it is often known from too great a 
 fpecifick Gravity, from an excefiive Roughnefs, and 
 from the Want of a quick Diflolution in Acids. But, 
 it is better for him who wants to have true genuine 
 Nil, to prepare it himfelf. 
 
 PROCESS LXVI. 
 
 The Cementation and Fufion of Coffer with Zink- ore. 
 
 APPARATUS. 
 
 T AKE of Zink-ore, for Inftance, of Calamine 
 reduced to Powder, one Part and a half \ and as 
 much of comminuted Charcoal ; grind them toge- 
 ther, and moiften them (lightly with Water : Fill 
 any melting Velfel with this Mixture, put between 
 and at top Plates of the pureft Copper one part , and 
 again cover them with Charcoal-dud, and put the 
 Whole in a wind-Furnace, covering it with a great 
 Quantity of Charcoal *, light them by flow Degrees, 
 and then increafe the Fire, to make the Veflel grow 
 white-hot : When you fee a Flame tinged with a 
 grey, bluifh, or purple Colour ; try here and there 
 with a ftrong iron- Wire, whether the Copper is 
 melted under the Charcoal-duft : Which is done with 
 a much lefler Fire, than Copper alone requires for 
 the Fufion of it : Then moderate your Fire, that it 
 may not be too violent : Finally, having continued 
 the Fufion a little longer, let the Veflel be taken out 
 of the Fire, that it may cool of itfelf, or let 
 the melted Mafs it contains, if confiderable, be 
 poured out into a dry and middling-warm Veflel : 
 You will find, when you break the Copper, that 
 it is tinged with a golden Colour, and that the 
 Weight of it is increafed a confiderable Quantity, 
 which is fometimes one quarter or one third Part of 
 the Weight of the Copper made ufe of, its Mallea- 
 
Assaying Metals. 377 
 
 bility remaining perfect in the Cold : But the more 
 it grows hot in the Fire, the more brittle it becomes ; 
 fo that, when it grows middling red-hot, you will 
 eafily break it into fmall Bits with a wooden Mallet, 
 or if it is handled roughly, having then loft all its 
 Tenacity. 
 
 2. If Calamine, or any other Body containing 
 Zink, and to be tried by this Method, is full of a 
 great Quantity of Lead, or of fome other Metal not 
 feparable from it ♦, it is proper, that the Mixture of 
 it with pulverized Charcoal made as before (N°. i), 
 be ground very fine, that fome Lute be mixt with it, 
 and that it be ftrongly compared and crammed into 
 a melting Veflel, to the End that the Plates of Cop- 
 per put at Top being melted, they may not get to 
 the Bottom : Then, you mu ft put a good Quantity 
 of Charcoal-duft upon your Plates of Copper, and 
 do the Reft as before: Likewife, melt the Copper in a 
 Fire much gentler than when it is alone, and'itwill 
 be tinged, though with a Colour fomewhat paler, 
 nor will the Weight of it be fo much increafed. 
 
 5 the Ufe and Reafons of the Procefs. 
 
 1. In this Procefs the Copper is penetrated by the 
 Zink, in form of a Vapour, and the Zink is fixe 
 in it : Which plainly appears, becaufe when you 
 flop the Paflage of the Copper, by putting Lute be- 
 tween, to keep it from running down into the Mix- 
 ture at the Bottom of theVeftel, neverthelefs its Con- 
 fiftence, Colour, and Conftitution change in the Fire, 
 and its Weight increafes, in fo much that it is certain 
 that the fublimed Matter has produced thefe Effe&s. 
 The Charcoal-duft does alfo prevent the burning of 
 the Copper, and hinders the Zink received by it 
 from being again burnt and diflipated. For, if you 
 melt tinged Copper in a Crucible, without any Ad- 
 dition, it takes a bright Flame almoft like Zink it- 
 felf, and fpreads Abundance of white Flowers tinged 
 Jiere and there with a Citron- colour, which feems to 
 
The Art of 
 
 proceed from the Copper carried away along with 
 them, being otherwise like the Flowers produced 
 (Proc. LXV) : But, in this Cafe, a great Part of the 
 Weight of the Copper is loft at the fame Time, and 
 the Colour of it grows every inftant worfe and worfe. 
 For this Reafon, when you tinge Copper with Cala- 
 mine, to get Profit by it, you muft try by Expe- 
 riments, what Degree of Fire you are toufe, and in 
 what Time the Copper acquires the greateft Weight, 
 and affumes the fineft Colour : For, it is plain to the 
 Eye, that a great Deal of it alfo vanilhes in Form of 
 a thick Fume. However, it is obfervable, that Brafs 
 or Copper impregnated with Zink, being made mid- 
 dling red-hot in the Fire, is not fo eafily calcined as 
 pure Copper. There are alfo a great many Differ- 
 ences in the Calamine : For, a Quantity of fome Ca- 
 lamine increafes the Weight of Copper, more than 
 the fame Quantity of fome other does. The Beauty 
 and Malleability of the tinged Metal are likewife dif- 
 ferent : For, fome Calamine affords a great Deal of 
 Lead and Iron ; whereby the Copper is fpoiled and 
 rendered pale and brittle *, though the Weight of it 
 is very much increaled at the fame Time. There are 
 even fome Species of this Stone, that require a pre- 
 vious Roafting, whereby a great Part of it muft be 
 diffipated, before it is rendered fit for this Ufe s 
 while others may be immediately made Ufe of. 
 
 2. There are befides the Calamine, many com- 
 pound artificial Bodies, which likewife tinge Copper 
 with a yellow Colour, and increafe the Weight of it : 
 Such as are the Cadmice Fornacum , or Tutty {Parti. 
 § 89) ; but, all Kinds of Tutty are not fo, but thofe 
 only which proceed from Zink-ores, or from com- 
 pound Metals in which Zink enters : Of which all 
 that has been faid of the Calamine is equally true. 
 A moft elegant and pure Kind of it, is the Tutty ufed 
 in the Apothecaries Shops : It is very ponderous and 
 folid, refembling cylindrical Segments by its Figure, 
 rendered convex and hollow by the Obftacle to which 
 the Vapours have applied themklves, granulated on 
 
Assaying Metals. 379 
 
 the Outfide, of a bluifh Colour, fmooth within, and 
 yellow. Nor is it dubious, that there are feveral na- 
 tive Minerals, or feveral Kinds of Tutty produced 
 from them, that would have the fame Effect : But, it 
 is highly probable, that their Nature is hitherto un- 
 known to us, becaufe the Examination of them has 
 been neglected to this Day. 
 
 3. Copper tinged in this Manner, when it pre- 
 ferves its Malleability, is called Brajs or yellow Cop- 
 per ; and as it is, by its Beauty, eafy Tracftability, 
 and long Duration, very fit to make Utenfils, and 
 the metallick Mafs is fo eafiiy increafed in the mak- 
 ing of it j on this Account, a very great Quantity of 
 it is made in feveral Places, when the neceifary Ingre- 
 dients may be conveniently prepared. 
 
 4. The Flowers, which are colle&ed during the 
 making of Brafs, or the melting of it a fecond 
 Time, and the roafting of the Calamine, as alfo 
 the Flowers of Zink itfelf not yet intirely burnt ; 
 likewife, all the Sublimates proceeding from Bodies 
 of the fame Nature, being cemented in the fame 
 Manner as the Calamine, that is, with Charcoal-duff 
 and Plates of Copper, and melted, make Brafs of the 
 befl Kind. But, the fame being burnt in a flow Fire, 
 are fo fixt, that in clofeYeffels, and a ftrong Fire with 
 a Draught of Air, they turn to a yellowifh Glafs ; as 
 is well obferved by Henckel concerning Zink ; how- 
 ever, he would, it feems, have this underflood only 
 of the Flowers of it : See Proc. LXV. Appar. N°. 4. 
 
 5. It is a wonderful Thing, that Zink itfelf being 
 plainly melted with Copper, robs it of all its Mal- 
 leability : As may be experienced in the making of 
 Prince’s-metal ( Part I. §88) : While being at the 
 fame Time applied by way of Vapour, and lying 
 hidden in the Calamine, in the Sublimates, and in 
 the Flowers, it does not take away the Malleability. 
 If this does not proceed from the Concurrence of 
 Lead, according to the Opinion of the Author juft 
 quoted, or from a very intimate Junction of the 
 Zink and Copper, the Reafon of it is ftill a perfecft 
 
 Secret 
 
380 The Art of 
 
 Secret. Nor is the Reafon yet fufficiently evidenced, 
 why a great Quantity of excellent Calamine requires 
 a previous Roafting, before it can be ufed for the 
 making of Brafs ; unlefs you have a Mind to render 
 this Metal lefs fine and malleable. Which Phcenome- 
 non , as well as a great many others falling under the 
 Hands of one bufied that way, are well worthy of 
 being inquired into. 
 
 OF MINERAL SULPHUR. 
 
 PROCESS LXVII. 
 
 tfhe Diftillation of Sulphur out of the Pyrites , and other 
 fulphureous Minerals . 
 
 A P P A R A T U S. 
 
 B EAT the yellow Pyrites, or any other ful- 
 phureous Mineral, to a coarfe Powder, put it 
 into an earthen Retort, or into a glafs-one coated 
 with Lute, having a long large Neck, and perform 
 the Diftillation in the fame Manner as ( Proc . LVIII.J 
 was prefcribed about Mercury. But, you are to ob- 
 ferve, that, if this Mineral is fo refractory in the Fire 
 that it does not grow foft when made middling 
 red-hot, you may make an Experiment with a greater 
 Quantity of it exceeding two or three Pounds, and 
 increafe the Fire more quickly, and thus perform the 
 Operation in a fhorter Time. Of this Kind is the 
 yellow martial Pyrites, which is chiefly the Ore out 
 of which almoft all the common mineral Sulphur is 
 got ( Parti . §316, 347). But, if it grows foft 
 when it begins to be red-hot, and the Ore is inclined 
 to melt, you mult put a fmaller Quantity of it into 
 the Retort, and manage the Fire more gently, whence 
 the Diflillation lafls a longer Time : This the Py- 
 rites of Copper, or the yellow Copper-ores ( Part I. 
 § 369) d° require, as well as the common Lead- 
 
 Ores 5 
 
Assaying Metals. 381 
 
 Ores ; For fo foon as they melt, the Exhalation of the 
 Sulphur is in clofeVeffels aimed intirely ftopt. Never- 
 thelefs, this Inconvenience may be remedied in fome 
 Meafure, by interpofmg fome refra&ory Body, that 
 exhales no Sulphur in the Fire, though it mull not 
 abforb or corrupt the Sulphur itfelf ; fuch is pure 
 Sand wafhed clean, and of the Nature of the Stone 
 called Quartz. But you mud avoid all Stones of the 
 lime, chalk, or fpaad-Kind. 
 
 2. When the Retort has been middling red-hot for 
 an Hour or more, let the Veffels grow cold : All the 
 Sulphur cooled by theWater, will adhere to the Ex- 
 tremity of the Neck of the Retort, from which it 
 mu ft be melted off, by a gentle Heat that does not 
 kindle Sulphur ; or you may take it out by break- 
 ing or cutting off the Neck •, then weigh it. 
 
 <Fhe TJfe and Reafons of the Procefs. 
 
 1. As there are in Minerals many volatil Matters 
 befides Sulphur; it is eafy to conceive, that it is not 
 always got pure out of them, but often joined with 
 other volatil Subftances, that taint it ; which may be 
 judged with fome Probability, from its Colour: For 
 pure fublimed Sulphur is always of a fine Yellow 
 fomewhat deeper than the Citron-colour ; but, its be- 
 ing of a red Dye fhews that Arfenick has been fu- 
 blimed along with it: But, though Mercury, when fub- 
 limed with Sulphur, does likewife give it a reddifh 
 Colour, it feldom mixes with it. However, if this 
 Ihould be the Cafe, you may eafily diftinguifh it 
 from the ftriated Figure of the broken Sublimate, 
 from its great Weight, and from the Place to which 
 it has applied itfelf during the Sublimation ; for, 
 where Cinnabar applies itfelf, there can remain no 
 Sulphur, nor any Arfenick. 
 
 2. By this Diftillation, a moft confiderable Quan- 
 tity of Sulphur may be got out of the Pyrites ; but 
 there remains a very fmall Quantity of the metallick 
 
 Earth 
 
382 The Art of 
 
 Earth of Copper and Iron joined together, which mull 
 at lad be feparated by Means of a very drong, open, 
 long- lading Fire, and by other Remedies already 
 mentioned in the Proceffes about thefe Metals. 
 
 3. If you want the Apparatus necefiary for this 
 Procefs, or care not to give you rfelf fo much Trou- 
 ble j you may have Recourfe to a plain Roading ; 
 and put, for Indance, one docimadical Centner into 
 a Ted covered with another Ted inverted, and road 
 it under the Muffle of the docimadical Furnace, or in 
 a gentle open Fire dowly applied, like an Ore to 
 be prepared for Fufion: In which you are to take 
 care, that the remaining Calx be not brought to a 
 Fufion, or rendered clammy, by a greater Heat than 
 it can bear : This done, if it ceafes to fpread an un- 
 pleafant fulphureous Smell ; let it grow cold, and 
 weigh it, to know how fhort it falls of one Centner : 
 Which Deficiency will be the Quantity of Sulphur 
 that was in the Ore. But, it is proper that you 
 fhould know, either from the outward Appearance, 
 or from the Smell which your Ore emitts, that it is 
 indeed fulphur Ore, or that Sulphur is at lead prevail- 
 ing in it *, becaufe all volatil Subdances occafion a Di- 
 minution in theWeightof Ores, by roading: Nor will 
 you be as fure of the Purity of your Sulphur, and 
 of Courfe of the Quantity of it when redified, as if 
 you had colleded the volatile Part itfelf. 
 
 4. You may know bituminous Minerals ( Part I. 
 § 318. &V.) from the Flame which they take 
 in the Fire, from a thick footy Smoak, which mi- 
 neral Sulphur never emits, and from their offenfive 
 or pleafant Smell : They may alfo be tried with 
 greater Exadnefs, by Didillation out of a Retort, 
 in feveral Degrees of Fire. 
 
 PRO- 
 
Assaying Metals. 383 
 
 PROCESS LXVIII. 
 
 f %e rectifying and fubliming crude Sulphur int § 
 Flowers , 
 
 APPARATUS. 
 
 P U T your Sulphur again into a Retort, having a 
 wide-open Neck cut off fhorter ; that it may not 
 beeafily ftopt, nor the Extremity of it reach the Wa- 
 ter in the Recipient : Let the Joints be ftrfelly clofed 
 with Lute, and, with the fame Apparatus as in the 
 foregoing Procefs, repeat the Diftillation, which ' 
 may alfo be very well made in a Sand-bath. But, 
 you muff ufe a Fire much gentler than in Proc . - 
 LXVII ^ nor muff the Veffel be red-hot in the End ; 
 but you muff continue the fame Degree of Fire, 
 by which the upper-Part of the Recipient which is 
 "void of Water is darkened, and the Sulphur begins 
 to diftil from the Neck of the Retort 5 becaufe Sul- 
 phur once expelled out of its Matrix by a ffrong 
 Fire, when alone, cannot bear the heating red-hot of 
 the Veffel : The Sulphur will diftil pure ; becaufe it 
 has depofited at the Bottom of the Retort, what it 
 had brought along with it the firft Time, from the 
 Ext Part of the Ore which is metallick, and from 
 the Arfenick (unlefs it is urged by too violent a 
 Fire) becaufe a Refidue more fixt than Sulphur re- 
 mains, which fixes itfelf more ftrongly with fixt 
 Bodies. This Refidue is called Scoria of Sulphur, 
 in German or Drofs of Sul- 
 
 phur. 
 
 2. If you will have very pure Flowers of Sulphur, 
 put Sulphur into a wide Cucurbite, or an iron-Pot ; 
 put upon this an Alimbeck, or another Veffel in- 
 verted and very large, and flop the Joints with 
 Lute : Then, bury the inferior Veffel that contains 
 the Sulphur fo deep in a Sand-bath, that the Sand 
 may be about as high as the melted Sulphur 5 or 
 
 put 
 
384 The Art of 
 
 put fmall burning Coals round the Veffel, as it ftands 
 upon the Pavement of the Hearth. Let the Heat 
 you apply be not greater than what is required to 
 melt the Sulphur *, and continue it fuch for feveral 
 Hours, that is, according as the Quantity of Sul- 
 phur is great, and the Veffel wide : All which Things 
 mull be determined from Experience. You may 
 alfo try whether the Sulphur is melted, and how 
 much of it remains ; by boring a fmall Hole in the 
 Top of the Alimbeck, or in the Bottom of the upper- 
 Veffel, not exceeding the Size of a Pea, through 
 which you may introduce an iron- Wire, to the very 
 Bottom of the Veffel that contains the Sulphur. 
 However, take as much Care as poffibly you can, 
 not to blow any Air in with your Mouth, through 
 the Tobacco-pipe, if you make this Trial with one : 
 For if the Fire is a little too ftrong, the Surface of 
 the melted Sulphur immediately takes Flame, and by 
 this Means the Vapours of it moving upwards, break 
 the Veffels afunder with great Noife, and with fome 
 Danger to thofe that (land by. If the greateft Part 
 of the Sulphur is fublimed, remove the Fire, and 
 when the Veffels are cooled a little and then opened, 
 you will find in the upper-one, and in the Brink of 
 the inferior, light, foft Flowers of Sulphur, of a fine 
 yellow Colour, having the Charafterifticks of per- 
 Fedl mineral Sulphur, and made perfectly pure by 
 Sublimation. There remains at the Bottom the im- 
 pure Sulphur, which muft be taken out of the Pot 
 Hill warm ; becaufe it adheres ftrongly to it, when 
 grown cold. 
 
 \ the life and Reafons of the Procefs . 
 
 1. Sulphur, when it is for the firft Time expelled 
 out of the pyritofe Ore, being agitated by a ftrong 
 Fire, carries fome Copper and Iron away with it : 
 But, a greater Quantity of thefe Metals diftil along 
 with the Sulphur, as the Ore is more arfenical *, be- 
 caufe Arfenick is more rapacious than Sulphur, and 
 
 paffes 
 
Assaying Metals. 3 Sp 
 
 pafies with the Sulphur, chiefly in the End of the 
 Diftillation, when a ftronger Fire is ufed. This ap- 
 pears plainly, when you urge with a ftrong Fire the 
 Refidue which remains in the Retort after the redi- 
 fication ; for then a tranfparent red Arfenick, and 
 a red and yellow Arfenick, are fublimed and come 
 over. The Caput Mortuum which then remains, 
 being roafted in a clofe Crucible, in a violent Fire, is 
 in great Part attraded by the Load-ftone applied to 
 it, and when you excrad a Quantity of it fomewhat 
 greater, it may with the white Flux, Glafs, Glafs-galJ, 
 or Borax, be reduced into a Regulus of Iron (Proc.hlV .) 
 but brittle, and ftill containing a little Sulphur. The 
 Copper betrays itfelf, when you roaft gently the 
 Caput Mortuum , then expofe it to the Air for fome 
 Days, and then extrad it with Water : For Calx of 
 Copper may fometimes be precipitated out of this 
 Water, by putting in it Plates of pure Steel, which 
 Calx mud likewife be reduced to a Regulus ( Proc . 
 XXXVIII). As then this is done in clofe Velfels, 
 and in a flow Fire gradually increafed, it is felf- 
 evident, that the fame fucceeds ftill much better in 
 an open, ftrong Fire, fuddenly applied, fuch as is 
 ufed by Afifayers in the roafting of fulphureous, py- 
 ritofe, arfenical Copper-ores, of which we have 
 fpoken (Proc. XXXIX). But there does not remain 
 an equally great Portion of Caput Mortuum from all 
 Sulphur : But if Sulphur is expelled out of a fmall 
 Quantity of Ore that has once undergone a flow ge*n- 
 tle Fire in a Retort , a very fmall Portion of it is 
 gotten : You obtain more of it, when a greater 
 
 Quantity of Sulphur is expelled haftily. 
 
 2. It has been imagined that there were feveral 
 different Species of Sulphur, from the feveral Mix- 
 tures of theft heterogeneous Matters : For all pure 
 Sulphur is ever one and the fame. For Inftance, 
 the golden coloured Sulphur loth tranfparent and 
 opaque , the red Sulphur , the orange-coloured one 9 
 the ruby coloured Sulphur , and the ruby coloured 
 Arfenick , are' nothing but Sulphur and Arfenick 
 
 C c gftx s 
 
386 The Art of 
 
 mixt in different Proportions, and called by different 
 Names. Likewife, the white, grey, and afh Co- 
 lours, &c. of Sulphur, depend upon the various 
 Mixtures of Earths partly metailick and partly un- 
 metal lick, with the fame : Its very Confidence is on 
 the fame Account changed to fuch a Degree, that 
 you can hardly judge from its outward Appearance, 
 that it is for the greateft Part Sulphur. This may 
 be feen in the Sulphur, which, during the Roafting 
 of pyritofe Ores made in a half fuffocated Fire, runs 
 fometimes between the Bits of the Ore, and being 
 collected when grown cold, is called in German 
 SropfTcI^teftL Sulphur vive, or native Sulphur, is 
 likewife found under various Forms. But you will 
 eafily find out by a gentle rectifying, what Body is mixt 
 with the Sulphur in any Cafe whatever. 
 
 3. Whenever you rectify and fublime Sulphur, it 
 does not always fuffer an effential Change ; but re- 
 mains uncorrupted in a clofe Fire : But, when oily, 
 fat, alkaline, and fuch like Matters are joined to it, the 
 Texture of it is deftroyed. The combined Actions 
 of too free an Air and of the Fire, deftroy it : Be- 
 fides, in an open Fire, the inflammable Part of it 
 takes Fire, and is confumed. Wherefore the acid 
 faline Part being a fecond Time difingaged is by the 
 burning Phlogifton refolved into a moil fuffocat- 
 ing Fume, and again is very greedy of Water, which 
 it intirely rejected in its Conjunction with the Phlo- 
 gifton. Whence, this Acid may then be alfo very 
 well collected by Means of Water or of its Vapour, 
 not being intirely difpofed of itfelf to gather into 
 large Drops, and apply itfelf to the Sides of the 
 Velfels. This acid Fume of inflamed Sulphur, is 
 commonly collected, by putting a Bell or a large 
 A limbeck over it, and is called Spiritus Sulphuris per 
 Camp an am , Spirit or Oil of Sulphur by the Bell. 
 But it is mofl conveniently collected by the following 
 Apparatus . Take a Cucurbite, as large as you can 
 And it, not yet cut off at Top, and with a hard, 
 cut ling, Iharp Flint, mark in the Belly pf it a fquare, 
 
 oblong 
 
Assaying Metals. 3S7 
 
 oblong Figure, Four Inches broad, and three Inches 
 high, dextroufly applying to it the acute Angle of 
 the Stone in fuch Manner, that it may in all its Tra<5t 
 ingrave a deep Furrow in the Glafs : This done, 
 touch every Point of the faid Furrow, with a ftrong 
 red-hot iron Wire : By this Means, you will cut off 
 from the Cucurbite, a Piece of Glafs like the circuin- 
 fcribed Figure. Put this Cucurbite under a Chimney 
 that carries fmoke well, and in fuch a Situation, that 
 the Hole may be forwards, and the Cucurbite in- 
 clined backwards a fmall Matter, and pour into it 
 one or a few Ounces of warm Water : Then intro- 
 duce a fmall fhallow wide China- Veffel full of pure 
 Sulphur, through the Aperture made in the Belly of 
 the Cucurbite, and fet this Sulphur on Fire with a 
 Thread dipt in Brimftoner When the whole Sur* 
 face of it is on Fire ; put a Plate of Lead againft 
 this Hole, that it may not admit more Air than is 
 neGeffary to maintain the Flame. The acid Spirit of 
 Sulphur will apply itfelf to the Sides of the Cucur- 
 bite, made moift by the warm Water, and, running 
 again to the Bottom, it will mix with the Water, 
 which being kept warm by the Contact of the Veffel 
 in which the Sulphur burns, and fpreading Vapours, 
 difpofcs to a Condenfation the acid Spirits that are 
 expelled* But the Sulphur that is burning in a free 
 Air, commonly contracts, at length, a fmall Cruft 
 arifmg from the heterogeneous fixt Matters, fome- 
 what hard, which hinders the Flame from fur* 
 ther confuming the Sulphur : Therefore this 
 
 Cruft muft be removed about every Quarter of an 
 Hour, if the Sulphur is not perfectly pure : Which 
 done the Flame is again revived. Nay, it is alfo ex- 
 tinguished by the Acid, which the half Suffocated 
 weak Flame of the Sulphur has not been able to dif- 
 fipate, there remaining in the Surface of the Sulphur 
 grown cold fmall Drops of a very acid Nature* If 
 you find that this is the Cafe, you muft immediately 
 add frefii Sulphur, and admit a greater Quantity of 
 Air t Otherwife the Flame once excinguifhed, is 
 
 C c a very 
 
388 The Art of 
 
 very difficultly lighted again. You put in frefh 
 Sulphur with a fmall iron-Ladle, with which you 
 muft alfo remove the Filthinels that has fucceflively 
 gathered and been introduced along with the Sul- 
 phur. Do the fame conftantly for one or feveral 
 Days, till you have gathered the defired Quantity of 
 Spirit. It will be as ftrong as if it had been col- 
 lected without Water, and even in greater Quantity. 
 What Methods and Operations foever you may ufe 
 for the collecting of Spirit of Sulphur, you will ne- 
 ver hinder the greateft Part of it from evaporating, 
 unlefs you will have it diluted in a great Quantity of 
 Phlegm, or fixt in fome alkaline Body or other, 
 from which you will hardly feparate it with any 
 Profit.. 
 
 4. You may very well find out with a fixt Alkali, 
 the Proportion in which the Acid and the Phlogifton 
 are combined in mineral Sulphur 3 and feparate them 
 with the fame fixt Alkali, in the following Manner. 
 Take of very pure Flowers of Sulphur, one Part, of 
 very dry pot-Afh beaten to a very fine Powder in a 
 warm iron- Mortar, two Parts 3 mix them 3 fill a 
 Crucible with this Mixture, cover it with a Tile, and 
 put it into a Fire of a middling Strength. The 
 Mixture will foon melt 3 pour it next into a dry 
 iron Mortar, and with all poffibie Care fcrape off 
 what adheres to the Veffel ; then beat the whole to 
 a Powder : Divide this into two equal Parts in a Pair 
 of Scales : Roaflone Part of it in a clean earthen flat 
 Veffel, not glazed, firft with a gentle Fire, which 
 muft be increafed more and more, till the Veffel 
 grows middling red-hot 3 ftir it now and then with a 
 Tobacco-pipe, taking great Care mean while, that 
 no Afhes fall into it 3 left the Weight ffiould be falfly 
 increafed : If the Salt grows quite white, and no 
 longer emits any Smell, it is a Sign that the Phlo- 
 gifton isdiffipated : The Acid of the Sulphur will ad- 
 here to the remaining fixt Salt, with one Part where- 
 of it has turned to a Tartar vitriolate, out of which 
 it cannot be expelled by Fire alone. Weigh the 
 
 remain- 
 
Assaying Metals. 389 
 
 remaining Salt. Diffolve the other Portion of this Li- 
 ver of Sulphur in a glafs VefTel, with treble the 
 Quantity of pure Water : There will remain a brown 
 Sediment, which will be Sulphur not quite difiblved 
 by the Alkali: Pour upon this Solution the flrongeft 
 Spirit of Vinegar drop by drop, a white Powder will 
 be precipitated, which is called Lac Sulphur is ^ or 
 Milk of Sulphur : Stir up this Liquor, and pour it 
 quite turbid into a filtrating Paper, when it is all 
 gone through, pour again upon it Spirit of Vinegar 
 drop by drop, that in Cafe more of the Lac SulpBuris 
 is again expelled, it may be joined to the foregoing, 
 by repeating the Filtration : What gathers in the 
 filtrating Paper being dry, if you diftil it out of the 
 Retort, it will afford Sulphur [Proc. LX VII.) 
 Thence it -appears, how much Sulphur was hidden 
 in the firfl Portion before the Roafling. But as the 
 Acid of the Sulphur remained alone in the firfl Por- 
 tion, after the inflammable Part was difiipated, it is 
 certain that the Excels of the "Weight of the ex- 
 tracted Salt, by which this furpaffes the Half of the 
 Weight of the Alkaline Saltemployed, proceeds from 
 thence, and this Excefs of Weight fhews of Courfe, 
 how much Acid there is in the Sulphur which you 
 have got by Precipitation and Sublimation. Thus 
 you find that the Acid is about fifteen Times more 
 weighty than the Phlogiflon, as has been demon- 
 flrated by Dr. Stahl . But, as during the Fufion of 
 
 the Liver of Sulphur, not only Part of the pure Sul- 
 phur is difiipated, but there is a'lfo an unpleafant 
 Smell perceived, which is different from the Odour 
 of Sulphur, fuch as is emitted in the fubfequent Roaft- 
 ing of the Liver of Sulphur *, we are hereby informed, 
 that Part of the Phlogiflon having left its Acid, is at 
 that Time difiipated, and that on this Account more 
 Acid is attributed to the remaining Sulphur expelled 
 with Vinegar and purified by Sublimation, than it has 
 in reality. Therefore, it is proper, that you fhould 
 life pot-Afh made perfectly pure, and try the Caput 
 Mortuum remaining after the Sublimation of the La-c 
 
 C c 3 Sulphuris , 
 
390 The Art of 
 
 Sui f hurts r whether and how much Tartar vitriolatc 
 it contains *, which is found out by Edulcoration with 
 warm Water, and by the Diminution thus made in 
 the Weight of the dried Refidue •, becaufe the Tar- 
 tar vitriolate being already produced in the Liver of 
 Sulphur, would remain with the Lac Sulphuris , in 
 the filtrating Paper, as a Salt very difficult to be dif- 
 folved : Therefore, as much Acid as is adherent to 
 fuch a Weight of Tartar vitriolate, fo much are you 
 to fubftradt from the Increafe of the Weight. 
 
 5. Mineral Sulphur may be produced by Art fe- 
 veral Ways, out of any Acid and Phlogifton what- 
 ever. This is moft conveniently performed by Stahl’s 
 Method, as follows : Mix with Tartar vitrioiate, 
 in order to facilitate the Melting of the refradtory 
 Salt, an equal Weight of Pot-affi, to which you 
 muft (lightly mix one eighth Part of foft pulve- 
 rized Charcoal. Put this Mixture at feveral Times 
 into a red-hot Crucible, which muft be covered with 
 a Tile, left a great Quantity of the Phlogifton ffiould 
 be diffipated by the Fire. The Mixture will melt, 
 and Liver of Sulphur, all the Principles of which 
 are prefent, will foon be produced : When this is 
 diffolved in Water, Lac Sulphuris may next be pre- 
 cipitated out of it, and this be fublimed into perfedfc 
 Flowers of Sulphur *. 
 
 % Sulphur may be produced of animal Urine, and Stercus, as*~'» 
 cording to the moft ingenious and fkilful Chemift Mr. Ambrofe GoJ~ 
 fry [Hanckewitz] F R. S. in his Account of his Preparation of the 
 Phofphorus, wherein he has fucceeded beyond all, who have at- 
 tempted that moft curious and fur prizing, though dangerous Pro- 
 cefs. See the Thilof. Tranfatt . N°. 428, p, 70. 
 
 O F 
 
Assaying Metals, 391 
 
 OF A R S E N I C K. 
 
 PROCESS LXIX, 
 
 ''The Separation of Arfenick out of its Qre> by Sublimation , 
 
 A P P A R A TU S. 
 
 1. irxG every Thing as was faid about Sulphur 
 U and Mercury : But let the Veffei which is 
 put into the Fire with the Ore in it, be of Earth or 
 of Stone, and the Recipient be of Glafs, and of a 
 middling Capacity : Nor is it neceffary that this 
 
 fhould be filled with Water, fo it be but well luted. 
 The Fire muff likewife be ftronger, and continued 
 longer, than for the extrading of Sulphur. Never- 
 thelefs, every Kind of Arfenick cannot be extraded 
 in a confined Fire : For, it adheres to the Matrix more 
 lirongly than Sulphur and Mercury. You will find 
 in the Part of the VefTel which is more remote from 
 the Fire, pulverulent and fubtile Flowers of Arfenick, 
 but there will adhere to the pofterior Part of the Neck 
 of the Retort, fmall folid Maffes, fhining like fmall 
 Cryflals, tranfparent, fometimes gathered into a fo- 
 lid Sublimate, and perfedly white, if the Ore of the 
 Arfenick was perfedly pure : Which neverthelefs 
 happens very feldom. The Flowers are mofl com- 
 monly thin, and of a grey Colour ; which proceeds 
 from the Phlogifton mixt with the Mafs *, they are 
 often of a citron or a golden Colour •, which is a 
 Sign that there is in the Mixture fome of that mine- 
 ral Sulphur, which commonly proceeds from the white 
 Pyrites, with which fomething of the yellow fulphure- 
 ous Pyrites is almoft always intermixt. But it will 
 be a Sign of a confiderable Mixture of Sulphur, if 
 you fee the red or yellow melted Sublimate, of which 
 we have already fpoken (Proc. LXVII). Whipe off 
 th% whole very clean $ then colled and weigh it, 
 
 Cc 4 
 
 2. If 
 
The Art of 
 
 2. If you road the Refidue in a Crucible till it 
 fin oaks no longer, or rather in an earthen flat Veflel 
 not glazed, and in a ftrong Fire to be ftirred now 
 and then with a Poker, and then weigh it when 
 grown cold, you will be able to know, how much 
 Arfenick remained in it in the clofe Veflel *, unlefs 
 the Ore contained Bifrnuth. 
 
 The Ufe and Reafons of the Procefs . 
 
 i. Arfenick is of itfelf more fixt than Sulphur, 
 and is very ftridtly united to feveral Metals, Earths, 
 and Stones, not even excepting Glafs itfelf, ahd vi- 
 trefcent Stones, and Salts : So that it remains with 
 them, though melted in the mod violent Fire, eva- 
 porating but little, and carrying Part of them away 
 with it, when expelled by a violent Adtion of the 
 Fire and Air: Which appears very plainly in the Cad - 
 ffiia Fornacum, or Tutty. The Glades in which it 
 is fublimed, are alfo penetrated by its Vapour, fo 
 that they grow milk white throughout their whole 
 Subdance : Which evidences its penetrating through 
 all Bodies. It melts with many of the Matrix's in 
 which it lies hidden, when you fuddenly apply to it 
 a middling melting Fire : Thus in the white Pyrites, 
 which can hardly be conquered by Fire alone, be- 
 caufe of the little Quantity of martial Earth and great 
 Quantity of unmetallick Earth it contains, it turns 
 to a Mafs in Appearance of a fern i- metal lick reguline 
 Nature, but not fo in reality : Becaufe a great Part 
 of it is unmetallick, and difficult to be feparated 
 from, the Arfenick, unlefs you ufe a Fire increafed by 
 Degrees, which at lad forces the Arfenick to aban- 
 don the fixt Part of it. The fame happens with 
 almod all Metals and Semi-Metals ; nay, it adheres 
 alfo to their Scoria’s and Calx’s, it melts with them, 
 and cannot be feparated otherwife than by a flow 
 Reading. Arfenick is well flxt in pure Earths, 
 and brings them to a Fufion without any Metal : 
 For this Reafon, when it is fomerimes in fmall Quan- 
 tities 
 
Assaying Metals. 393 
 
 tlties in Spaads, Maries, &c, it exhales nothing in a 
 gentle Fire, and in clofe Veffels: But in . rong 
 open Fire, it at laft fpreads an unpleafant arfenical 
 Smell, and diminifhes the Weight of the whole con- 
 crete Body. Whence thofe who try to make Parget 
 with Spaad, get fometimes Ulneffes, while they bake 
 their Parget, and their Moulds to call Metal into : 
 For this Reafon likewife, Spaad and Parget made 
 with it, which is done with a gentle Roafting, 
 fometimes melts in a ftrong Fire *, whereas it could 
 not otherwife be brought to it by a great Fire. The 
 Efficacy of this Body is very great in promoting dry 
 Solutions, and it is confiderably increafed, when it 
 is joined with a Body fixt in the Fire, and fufible ; - 
 for Inftance, with plain Glafs of Lead, or with Glafs 
 made of Lead tainted with Arfenick, the Effect of 
 which is much greater than common Litharge, or 
 Glafs of Lead. You may find out in clofe Veffels 
 the Prefence of Arfenick lying in a fmall Quantity 
 in any Body whatever, by grinding it together with 
 mineral Sulphur, and then fubliming it, ufing a 
 ftrong Fire in the End of the Operation : If there is 
 then Lome Arfenick, there will arife, towards the End 
 of the Operation, fome Flowers of an Orange-colour, 
 and a half tranfparent ruby-coloured Sublimate, in 
 which the Arfenick lies hidden : For this is raifed 
 along with the volatile Sulphur *, whereas it could 
 not otherwife be eafily detected by Sublimation. But 
 in Orpiment, which, befides the Arfenick, contains 
 a Quantity of Sulphur not inconfiderable, the Earth 
 which in this Mineral contains hardly any Metal, is 
 melted together with them in a gentle Fire, and turns 
 to a half tranfparent red Mafs, out of which you may, 
 by a gentle Sublimation, or by Means of a Defpu- 
 mation, feparate this Earth, which contains a great 
 Deal of Arfenick fixt in it, not to be diffipated with- 
 out a great open Fire, increafed by Degrees, and 
 continued long. 
 
 2. The Phlogifton added, and the Fire applied 
 in various Manners, give Arfenick a Variety of 
 
 outward 
 
394 Art of 
 
 outward Forms : Otherwife, Arfenick is but one and 
 the fame, fo it be but pure. When perfe&Jy pure, 
 it is of a white Colour : When joined with a Phlo- 
 gifton, it becomes of a grey, blackifh, aflh-colour : 
 And this is true not only of fublimed, but alfo of 
 native Arfenick : As it is plain in the native black 
 Arfenick, called in German ^f^artjen^tgCttSetlt, 
 out of which a grey Kind of Arfenick is produced by 
 Sublimation. Arfenick fublimed with mineral Sul- 
 phur, is always of an orange, yellow, or red Colour. 
 But the Phlogilton is eafily dete&ed in Arfenick both 
 fublimed and native, when you reduce this to Pow- 
 der, and call it upon Nitre melted in a Crucible : 
 For then you fee a bright Flame and Detonation, 
 which is produced by the leaft Quantity of any Kind 
 of Phlogilton whatever, mixt with Nitre. They, 
 indeed fay, that Nitre detonates with Arfenick; that 
 it produces a Flame, and that then the blue Spirit of 
 Nitre of Stahl is expelled at the fame Time : But 
 pure, white, cryltalline Arfenick, gives no Flame 
 with Nitre ; though it has the other Properties men- 
 tioned. You mult make the Experiment about this 
 Matter, with the following Precautions. Reduce a 
 few Ounces of the ptireft Nitre into Powder, and 
 put it into a deep wide Crucible : Put the Crucible in- 
 to a wind-Furnace, and add gradually hot burning 
 Coals that have ceafed to crackle, left the Veftel be 
 fplit ; nor mu ft thefe Coals be heaped up higher than 
 half the Height of the Crucible, which, mean while, 
 muft be covered againft the Fall of burning Coals 
 into it : When the Nitre melts in fuch a Degree of 
 Fire as makes it grow moderately red, add at feveral 
 Times Powder made with a folid Bit of white cryf- 
 talline Arfenick : A noify Ebullition is immediately 
 produced, fo that fometimes the foaming Nitre runs 
 over a large Veftel ; a Fume is emitted which is ar- 
 fenical at firft , and afterwards perfectly of the fmell 
 of Aqua Forth 5 which being received through a hol- 
 low Retort into a Glafs Recipient applied to it, re- 
 iembles much the penetrating Spirit of Nitre, You 
 
 muft 
 
Assaying Metals. 395- 
 
 muft be cautious in thisProcefs, not to ufe fmall Bits 
 of Arfenick difperfed in fmall Chip-Boxes, or wrapped 
 up in Paper. For the minuted animal or vegetable 
 Fibre makes a pretty impetuous Deflagration with 
 Nitre melted or burning : For which Reafon alfo, 
 you are to ufe the cleaned Tools ; left any Phlogifton 
 fhould get into it. Next, make the Operation under 
 a Chimney, which carries Smoak very well ; left a 
 noxious Vapour fhould annoy you. If the Mixture 
 of Nitre and Arfenick is once put into VefTels well 
 luted, to diftil the abovemen tioned Spirit ; by in- 
 creating the Fire, the Mixture breaks the Vetiels 
 afunder with a Noife, juft as if a Phlogifton had been 
 mixt with the Nitre, refembling a true Inflammation, 
 not without fome Danger for the People that ftand by. 
 
 3. The Confidence of Arfenick varies, and chiefly 
 depends upon the Fire applied to it. For Inftance, 
 if an arfenical Vapour finds a cold Place, it applies 
 itfelf to folid Objects in Form of a Powder, as Sul- 
 phur does, which Powder is more fubtile in Propor- 
 tion as it is more remote from the Fire. Arfenick 
 is coile&ed under this Form in large Operations, 
 which are made, while the arfenical Ore is thrown 
 into the Furnace with the Fuel of the Fire, out of 
 which Furnace the Smoak is laterally conveyed 
 through a Funnel, into a large Channel made with 
 wooden Boards. This Channel is feveral Fathoms 
 long : Nor is the Direction of it ftrait, but forming 
 feveral Elbows, to the End that the Smoak may 
 meet with more frequent Obftacles, by which being 
 retarded, it may apply itfelf, while the reft goes out 
 at laft, through a wooden Funnel conftrufled at the 
 other Extremity of the Channel. This Powder is 
 called in German and it has a grey or 
 
 alh-Colour, caufed by the Smoak of the Fire. But if 
 it is fublimed in a covered Veffel, left it fhould fly 
 away too freely, the arfenical Flowers begin to grow 
 clammy, in that Part of the Veffel which is at laft 
 made hot by the long Continuation of the Fire, 
 and gather into a ponderous thick Sublimate ; Never- 
 
 thelefs 
 
3 $>6 The Art of 
 
 thelefs, this Sublimate does neither run out, nor get 
 to the Bottom of the Veffel, when the Fire is in- 
 creafed : For a tenacious doughy Clamminefs is in- 
 deed communicated to Arfenick by too violent a 
 Fire ; but Fire alone cannot make it melt, fince it, 
 on the contrary, refqlves it mod quickly into a 
 Smoak, which finding no Way to efcape, breaks 
 afunder the Veflfels that keep it confined. The yel- 
 low Arfenick aflumes more eafily the folid Form of 
 Sublimate, on Account of the tenth or twentieth 
 Part of Sulphur mixt to it, by which Arfenick is 
 brought to a State of Fufion. But the red Arfe- 
 nick, which is mixt with a dill greater Quantity of 
 Sulphur, cannot even be conveniently prepared in a 
 Sublimation by Afcent, on Account of its too great 
 Fufibility, which is communicated to it by an Abun- 
 dance of Sulphur : But it adheres either above in 
 Form of Flowers 3 or runs quite melted to the Bot- 
 tom of the Veffel, leaving only a thin Crud of red 
 tranfparent Sublimate, and fome fmall Drops. There- 
 fore, in order to be able to prepare it quicker, and 
 in larger Bits, it mud be forced out of a Retort *, in 
 the warm, large, though not too long Neck of which 
 it mud be condenfed, and thence fall , as yet fluid 
 into the Recipient applied to the Retort, and grow 
 cold, Arfenick of this Kind may be produced im- 
 mediately out of Pyrites, without any Addition, if a 
 fulphureous Pyrite is intermixed with a white Arfe- 
 nick one, or with fome other Arfenick-ore, or added 
 to it for that Purpofe. And thus you will have 
 yellow or red Arfenick, according to the Quantity 
 of the fulphureous Pyrites. 
 
 5. In all Operations made with Arfenick, you are 
 to take Care not to take in the lead Quantity of 
 it, either in Subdance or in Form of Fumes, nor even 
 to touch it frequently with your Hands : For it is 
 a mod pernicious Poifon ; even when taken in a fmall 
 Dofe it is mortal with mod dreadful Symptoms, 
 and when now and then applied in a very fmall 
 Quantity, it produces Eflfedts, which at lad prove in- 
 curable : Whence a great many have lod their Lives, 
 
Assaying Metals. 397 
 
 for having managed it without Caution. Therefore, 
 let ail Precedes with Arfenick be made under a 
 Chimney that carries Smoak well : For the Vapour 
 of Arfenick is not fo quickly conden fed, but fome- 
 thing of it efcapes through the Joints of the Veffels, 
 and fills the Air with a Poifon, which betrays itfelf, 
 by its unpleafant garlick-like Smell. It is dill more 
 dangerous, when to be reduced to a fine Powder : For 
 notwithftanding its great fpecifick Weight, when 
 the Powder is violently agitated ; it is eafily carried 
 away by the Air, not affecting the Smell nor the 
 Tafle, but yet pernicious, if drawn into the Lungs 
 together with the Breath. 
 
 PROCESS LXX. 
 
 Mercury fepar cites mineral Sulphur from Arfenick « 
 
 APPARATUS . 
 
 1. j E T the Arfenick be reduced to a mod fubtile 
 I j Powder by a flow Trituration: Which is 
 
 very conveniently performed in a done-Mortar. This 
 done, pour upon it a few Drops of Mercury : Con- 
 tinue the Trituration, the Mercury will infenfibly 
 difappear, and the fine yellow or red Colour of the 
 Arfenick will be darkened : This done, add fome 
 more Mercury without ceafing the Trituration ; till 
 at lad the Powder receives no more Mercury, and 
 there remains not the lead Appearance of the yellow 
 or the red Colour in the Mixture, but it a (fumes either 
 a grey Colour, if there was but very little Sulphur 
 in the Arfenick, or a black Dye, if it contained a 
 good Deal : .Which can hardly be done in fome 
 Hours, if you employ a Pound of Arfenick. But in 
 this very Cafe, it is proper to perform the Tritura- 
 tion in feparate Parcels. 
 
 2. Fill 
 
The Art 
 
 2. Fill about one third, or one half Part of the 
 Belly, of a high, narrow glafs-Cucurbite, not cut 
 off : Apply to this, inftead of an Alembick, another 
 large inverted Cucurbite, cut off at Top, and flop 
 the Joints with Lute : Put it into a Sand-bath, in a 
 Situation feme what oblique : Nor muft you gather 
 your Sand around it, higher than the Mixture in the 
 Cucurbite : Then perform the Sublimation, in a Fire 
 fomewhat gentler than Cinnabar requires : The arfe- 
 nical white Flowers will adhere above, together with 
 neat white Cryftals of Arfenick, or they will be 
 grey, and the fublimed Cinnabar will be lower, nor 
 will this, however, be altogether void of Arfe- 
 nick. 
 
 The Vfe and Re a fins of the Frocefs . 
 
 *. A great Quantity of Sulphur melted with Arfe- 
 nick, may be feparated from it for the greateft Part, 
 by a gentle Sublimation ( Proc « LXIX) : But a Part 
 of the Sulphur is fo ftridtly detained by the Arfenick, 
 that they can never afcend but both together ; in fuch 
 Manner however, that the firft Sublimate and the 
 Flowers are richer of Sulphur, while that which af- 
 cends lad, contains little or no Sulphur at all : But 
 this requires a gentle Fire flowly increafed. 
 
 2. A more perfect Separation of Sulphur and Arfe* 
 nick is obtained by Means of Mercury, and even at 
 fir ft the Sulphur is joined to the Mercury the cold 
 way, by Trituration alone : Which we learn from the 
 Production of the jEthiops Miner al, which being af- 
 terwards fublimed by Fire, turns to Cinnabar. But 
 this Experiment will never fucceed to your Sat if* 
 fa&ion, unlefs the Trituration of the Arfenick with 
 the Mercury is very well performed : For elfe, when 
 the Fire begins to acl, there afcend firft of all Flowers 
 of an Orange-colour, on Account of the mineral 
 Sulphur, which Flowers are more volatile than the 
 pure Arfenick that follows, and fill the upper- Part of 
 the VefTels, fpoiling the faid Arfenick ; becaufe 
 
 the 
 
Assaying Metals. 399 
 
 the Sulphur was not yet united with the Mercury : 
 Therefore, you muft add rather more than lefs Mer- 
 cury, that all the Sulphur may be detained. Next 
 let the Fire not be too violent nor too precipitately 
 applied, becaufe it confounds all the Ingredients to- 
 gether : Nor muft the Necks of the Vefiels be too 
 large. However, as Arfenick is employed pure for 
 other Ufes, this Separation is never made * becaufe 
 it requires a great Labour, and yet is never com- 
 pletely performed. For a great Quantity of Arfe- 
 nick, feparated from the Sulphur, adheres to the 
 white, fhining, folid, diftindt, fmali Maftes, which 
 are between the Sublimate of the Cinnabar, and the 
 fmali Drops of the Mercury that have net been dif- 
 folved by the Sulphur. Whence, the Cinnabar ap- 
 pears rather of a grey than a red Colour, and may 
 at laft be totally feparated, by repeating and well 
 performing the Sublimation. 
 
 3. The Foundation of this Procefs is then, that 
 Mercury is diftolvable by Sulphur, and on the con- 
 trary rejedts Arfenick. Therefore, as the other 
 Metals and Semi-metals have an equal Affedtion for 
 Arfenick and Sulphur, or rejedt them both, the Se- 
 paration of the latter by the former will not fucceed ; 
 or if any Kind of it is obtained, it happens in an in- 
 verted Proportion ; for Inftance, when the Sulphur 
 afeends eafily, the Arfenick is detained in the Caput 
 Mortuum , which is diffipated by a ftrong and com- 
 monly an open Fire : If any is obtained, it is gene- 
 rally not true, and impregnated with Phlogiftoa, 
 See Henckel . Pyrit . p. 558. 
 
 P R O- 
 
400 The Art of 
 
 r # * ' 
 
 PROCESS LXXI. 
 
 The purifying of Arfenick by Sublimation with a fixt Alkali , 
 to make it white and cryftalline. 
 
 APPARATUS. 
 
 I F inftead of Mercury ( [Proc . LXX.) you ufe afixt 
 Alkali well burnt, fuch as Pot-afh ; there comes 
 forth a half-tranfparent, white, folid, hard, ponde- 
 rous Sublimate of Arfenick, which adheres below, 
 and pulverulent white Flowers join to it above. But 
 the Fire, muft be much more violent in this Subli- 
 mation than in the foregoing, efpecially towards the 
 End : Wherefore you muft alfo chufe higher Veflels, 
 that the arfenical Vapours may find a Space lefs 
 warm to which they can apply themfelves. You are 
 alfo to take Care, not to add more Alkali than is 
 necefiary to retain the Phlogifton : Which cannot be 
 exadlly determined: For you will obtain Arfenick 
 with greater Difficulty, and in leffer Quantity, as 
 you ufe a greater Quantity of Salt, and on the con-^ 
 trary. 
 
 The Separation of the Phlogifton will fucceed with 
 a fmall Quantity of Arfenick, if you firft fprinkle 
 the Arfenick reduced to a very fine Powder, with a 
 very pure alkaline Solution, and then dry it (lightly 
 before the Sublimation. Likewife, more Arfenick is 
 produced by this Method in a gentle Fire. 
 
 The Ufe and Reafons of the Procefs. 
 
 i. Fixt Alkali well burnt in an open Fire, is very 
 greedy of a Phlogifton, if you except Acids and 
 Water on certain Conditions, and when it has ab- 
 forbed it, it does not entirely quit it again eafily, 
 unlefs you hinder the too free Adtion of the Air ; let 
 the Violence of your Fire be ever fo great : Which 
 
 may 
 
Assaying Metals. 401 
 
 may be experienced in the Diftillations of Tartar and 
 of common Soap, and in the Operations made with 
 reducing Fluxes ; wherein there remains always fome- 
 thing of the Charcoal. Arfenick, with the leaft 
 Quantity of Phlogifton, aftumes a grey, afti, and 
 black Colour, or the orange or red Colour, when 
 Acid of Vitriol is added to the Phlogifton. When 
 the Phlogifton is expelled, it appears again under its 
 white Colour. When white, it is again defiled with 
 the fa id Colours, by a final 1 Addition of Phlogifton, 
 if it is firft digefted with it, and fublimed again, as 
 the above quoted Author fays, with Oil of Ah 
 monds. Vid. Pyntolog. p. 558. 
 
 2. But, the Phlogifton is not only detained by a fixt 
 Alkali ; but a great Part of the Arfenick itfelf is 
 alfo fixt by it to fuch a Degree, that it cannot be 
 inti-rely diffipated out of it by any Fire, not even an 
 open one *, and even turns to Glafs with it by adding 
 fome Flints : Therefore, fixt Alkali muft not be 
 added too liberally. Thence it is plain, that this Se- 
 paration of Arfenick and Sulphur does not take Place, 
 if the latter is mixt in too great a Quantity with the 
 former *, and that you muft have Recourfe to other 
 Remedies. See Proc. LXX. and LXIX, But a 
 fmaller Quantity of Salt is Sufficient to Separate the 
 fame Mixture of Arfenick and Phlogifton, in Pro- 
 portion, as all the Ingredients are more intimately 
 mixt together : Which is better obtained by a Sprink- 
 ling with an alkaline Solution, than by a dry Tritu- 
 ration : Becaufe all the fmall Mafifes of Arfenick are 
 furrounded and penetrated with the Salt in the 
 former. 
 
 3. It is wonderful, that this Separation of the Phlo- 
 gifton and Arfenick can hardly be completely per- 
 formed by any Body, befides fixt Alkali, unlefs 
 by Mercury ; (fee the above-cited Place) although 
 there are much more potent Magnets of inflammable 
 Matters, than Mercury is. The Thing cannot be 
 done at all with Metals * nay, the pureft white crys- 
 talline Arfenick, fublimed upon Metals that are gra- 
 
 D d nulatedj 
 
402, The Art of 
 
 nulated, or filed very fine, (pure Gold and Silver ex- 
 cepted) afeends rather the fooner, and is fuilied with 
 a brown Colour, of which it mufc be again purified 
 by the foregoing Method, 
 
 4. As the remaining alkaline Salt is flill impreg- 
 nated with no fmalj Quantity of Arfenick , it is very 
 good to make white Copper, and to impregnate the 
 other Metals with Arfenick : For which Purpole, 
 fome prepare fixe Nitre by a Detonation with Arfe- 
 nick (fee Proc. LXIX. Uf t N°. 2.) in which Nitre 
 a great Quantity of Arfenick is fixt, wl;iich being 
 afterwards melted with Copper, gives it a white Co- 
 lour *. By which Means a confiderable Malleability 
 is preferved in the Copper. 
 
 PROCESS 
 
 LXXIL 
 
 drfenick is reduced into a fimi- met alii ck Form, 
 Phlogijlon. 
 
 A P P A R A T U S, 
 
 l. /n -RIND together two Parts of white, cryf- 
 talline Arfenick finely pulverifed, or of the 
 Flowers of it, with one Part of the black Flux, cne 
 half Part of Glafs-gall, anq as much of Filings of 
 Iron not roily, that they may mix well together. 
 Fill with this Mixture a flrong wide Crucible, and 
 cover it with common Salt one Finger’s breadth 
 high : Then, cover it with a Tile, or an inverted 
 Crucible having a final! Hole in the Middle. Put it 
 m the wind-Furnace. Make firfl a gentle Fire, that 
 the VeiTels may warm equally. When the Arfenick 
 begins to fmoak, increafe the Fire fuddenly, that it 
 
 # This is the whitp Prince’s Metal, invented by Prince Rupert , 
 of which Buckles, Spoons, and many other Utenfils are made, to 
 imitate Silver ; but they foon tarnifh ; to mend which they cover 
 over this Metal with a thin Coat of Silver, and polilh it, which is 
 fold by the Name of French Plate. 
 
 may 
 
Assaying Metals.- 403 
 
 may be of a moderate melting Degree, and put the 
 Mixture in Fufion : This done (which may be found 
 out with an Iron- wire introduced through the fmall 
 Hole bored in the upper-Crucible) take the Veffels 
 out of the Fire, put them into a cold Place, and 
 •when cooled, break them : You will find a Regulus , 
 which will be more foft, more brittle, and of a 
 darker Colour, in Proportion as it doth contain more 
 Arfenick, and lefslron. On the contrary , if a great 
 Deal of the Arfenick has been diffipated, becaufe of 
 the too flow Application of the Fire, it will then be 
 harder, more folid, and whiter. It may alfo be 
 poured into the melting Cone, when the Mixture is 
 in greater Quantity : And being thus fooner cooled, 
 fo great a Quantity of the Arfenick is not d'ifli- 
 pated. 
 
 2. Regulus of Arfenick may be prepared with Cop- 
 per after the fame Manner, which retaining likewife 
 a great Quantity of Arfenick, will, on this Account, 
 be very brittle, and of a dark Colour ; but, when 
 the Arfenick is in great Part diffipated, it will be 
 neater and harder, fometimes as brilliant as Silver, 
 half-dudtile, with a very flight yellow Call. This is 
 a kinder whitened Copper. 
 
 3. Arfenick intimately mixt with Flux, warmed 
 firft (lowly, and at laft melted fuddenly, though not 
 with too great a Fire, is cohered into a Regulus of a 
 femi-metallick Kind, but foft, light, and pretty 
 bright, though not of a lafting Colour : Nay, the 
 fine Brightness it has at firft when broken, vanifhes 
 in a few Days and turns black, though not throughout 
 the Mafs, but only at the Surface. This Regulus being 
 brought near a Candle, without any Addition of 
 Arfenick, feems to nourifh the Flame, like the red 
 Arfenick charged with Sulphur, and vanifhes at the 
 fame Time into a pernicious Smoak, in which it 
 may be thus totally refolved : This Smoak gathered 
 under the Form of Flowers, is the grey Arfenick 
 (Proc. LXXI. and LXX.) Thefe Proceffies muft be 
 performed under a Chimney that carries the Smoak 
 
 D d 2 _ well. 
 
404 Art of 
 
 well, left the poifonous Fumes coming forth with 
 great Violence, fhould prove hurtful to the Artificer. 
 
 j The Ufe and Reafons of the Procefs . 
 
 1. Copper and Iron render the Precipitation of the 
 Regulus of Arfenick abundant and eafy in this Pro- 
 cefs, but they do it from another Caufe than in the 
 Production of the Regulus of Antimony. For in the 
 latter they were added* that the mineral Sulphur 
 which retained the reguline Part diffolved in crude 
 Antimony, might be abforbed by them ; which done, 
 the Regulus rendered free went to the Bottom, while 
 the Metal that was in the Mixture charged with Sul- 
 phur, fwam a- top in Form of Scoria’s. But, in 
 this Operation, Arfenick which is of itfelf altogether 
 volatile, muff be expofed to a very violent Fire fud- 
 denly applied, that it may be fixt with thefe Metals, 
 after having been reduced to a fern i- metal lick and 
 very woXmXtRegulus. Whence it islikewife felf-evidenr, 
 that the Regulus of it participates very much of any 
 precipitatingMetal whatever, and is lefs uncompounded 
 than the Regulus of Antimony precipitated by Metals, 
 and that of Courfe it cannot be purified again by 
 way of Fufion : For, it is prefently refolved into 
 Fumes, as foon as it is fepa rated from the Metal 
 that fixes it. 
 
 2. If this Regulus precipitated with Copper or 
 Iron, is beaten to a coarfe Powder, and then a great 
 Quantity of it is fublimed, the femi-metallick arfe- 
 nical Part, is for the greateft Part carried up, and 
 muff be looked upon as the pureft reguline Subftance 
 of Arfenick : For, there remains at the Bottom of the 
 Cucurbite, that Metal by which the Regulus has been 
 precipitated; but, it is tainted with a great Deal of 
 Arfenick : Nor can it be diffipated otherwife than by 
 repeating the Roafting and the Pulverifing, in an 
 open Fire increafed by Degrees. See particularly 
 the ProcdTes about Iron and Copper* 
 
 3. The 
 
Assaying Me'tal s'. 40 $ 
 
 3. The Regulus of Arfenick is very difficultly got 
 without any Addition. For, every reducing Flux 
 is very refraCtory, with regard to the great Volatility 
 of this Regulus , fo that it is moF quickly diffipated 
 by the fame Fire that melts it, and then either dis- 
 appears intirely, or adheres difperfed among the 
 Scoria’s to fmall fhining fpungy Mafifes : Which hap- 
 pens alfo, when there is not the Degree of Fire ne- 
 cefiary for the Fufion of the Flux. There is alfo a 
 great Deal of the Arfenick ,that remains in the Sco- 
 ria’s, totally diffolved, and not apparent at all. For 
 this Reafon, there mull be much more Arfenick than 
 Flux, and they mull be mixt together by Tritura- , 
 tion ; the FriCter, the better. Arfenick may be pro- 
 duced under a femi-metallick Form, out of the fame 
 Mixture of Flux and Arfenick, by a Frong Subli- 
 mation : This may be done very conveniently with 
 
 a fmall Earthen Cucurbite, to which another of Glafs 
 mull be applied : This muF by all Means be hori- 
 zontally Ftuated in a Furnace fit to make DiFillati- 
 ons in an open Fire, which being Frongly increafed 5 
 the Arfenick afcends, and applies itfelf to the colder 
 Region of the Vefiels, partly in blackiffi thin-fet 
 Flowers, partly in a Sublimate compofed of a Col- 
 lection of fmall fcaly Fiining Malles. 
 
 4, Let Arfenick be reduced to a femi-metallick 
 Form, by whatever Method you will, according to 
 the foregoing Directions, it will rea Films its white 
 cryFalline Form, by a Sublimation with fixt Alkali* 
 or Mercury ( Proc , LXXI.) 
 
The Art of 
 
 40 6 
 
 OF VITRIOL. 
 
 PROCESS LXXIII. 
 
 To extract Vitriol out of the Inbftones (Part I. § 421,) 
 and to cryftallize it. 
 
 A P P A R A T U S. 
 
 1. A N Aftringent, rough, fweetifh, ftyptick, 
 XJl naufeous Tafte, betrays the Prefence of fome 
 Arfenick, or Allom, in any terreftrial Concrete. 
 Now, if you want to be certain, what this Concrete 
 is, and how much it conceals of the faid Minerals, 
 beat the Clod of Ore to Powder, and boil it in a 
 Glafs-Cucurbite cut off at Top, or in a Veffelunade 
 of milled Lead, with three Times the Quantity 
 of pure Water. Stir up the turbid Water ftsll warm 
 with a wooden Stick, pour it into a double filtrating 
 Paper, previously moiftened with Water, and placed 
 in a Glafs Funnel : This muff be done, left a great 
 Quantity of the Water which contains Vitriol, ef- 
 caping at theupperPart of the filtrating Paper, fhould 
 diminifh the Prodii<ft confiderably, efpecially if you 
 ufe but a little of the Ink-ftone. Let the pulverized 
 Clod of Ore be boiled a fecond Time with a double 
 Quantity of Water, and repeat this fo long as the 
 Tafteof the Vitriol is ftrongly perceived in the boiled 
 Water : Then filtrate thefe 'Solutions, and pour them 
 apon the firft Solution. 
 
 $ 2. When all the Solutions are collected in a Glafs 
 Cucurbite, cut with a wide Opening, put them in a 
 Sand-bath, and make a Fire fo ftrong as that a thick 
 Vapour may come out, but the Fluid not boil : Con- 
 tinue this Degree of Fire equally, and without Inter- 
 million : So foon as you fee thin Pellicles on the 
 Surface of the Solution, like Duft that might have 
 
 fallen 
 
Assaying Metals. 407 
 
 Fallen upon it, fwimming a-top, 1 ft the Veffels 
 grow cold, and put them in a cold dill Place for 
 one Day and one Night, that Cryitals may gather, 
 which muft be collected by decanting the remaining 
 Liquor of the Solution, Dilute the Refidue with the 
 double Quantity of Water, ’filtrate and infpiffate it, 
 and fee it by for Cryflallization, as before ; till what 
 remains at lafb refufes to. turn any more to Cryflals, 
 hut affumes an oily Confidence. Confider every 
 Time feparately the Cry dais produced, to fee whe- 
 ther they have the Properties of Vitriol (Fart I. §417)0 
 But in each Cryflallization, an Okerof a yellow Colour 
 will be produced, which is expelled in a greater Quan- 
 tity, as the InfpiiTation is performed more (lowly ' 
 and inequally, or even when the Solution is kept too 
 long at Red, though it be perfetdly tranfparent. 
 
 The life and Redfcns of the Frocefs. 
 
 'i. There are many Ink-ftones that conceal different 
 Kinds of Vitriol confounded together (Parti. § 417.) 
 and fometimes Allom into the Bargain. The latter 
 is very eafily didinguidied, when the Infpifiatioii 
 and the Cryflallization are difcretely performed : By 
 which Method fome Salts may be feparated from each 
 other, which being confounded with an InfpiiTation 
 too haftily made, cannot be well didinguifhed. The 
 Difference which is between thefe Vitriols, proceeds 
 from a Variety of the Proportion, in which the green 
 Vitriol of Iron * and the blue Vitriol of Copper •f are 
 joined to each other. Allom itfelf mixes with them 
 pretty often, which appears clearly, if you diftil 
 Oil from Vitriol, or calcine this flrongly, and edul- 
 corate with Water the Caput Morluum which is very 
 red. This, Water being infpiTated and cryftallized, 
 produces whitifh Cry dais, which are called Gill a 
 Faracelfi |], and have concentrated in them the Allom 
 
 * In the Shops called Copperas. 
 
 t Known by the Name of Roman Vitriol \ or the blue Stone. 
 
 1 ! Salt of Vitriol. 
 
 Dd 4 
 
 winch 
 
408 The A rt of 
 
 which was in the Vitriol. Nay, this Gilla is more 
 impregnated with Copper, than the Vitriol out of the 
 Caput Mortuiim of which, it has been made. For 
 Allom moll difficultly lofes its Acid in the Fire : 
 Therefore, if you pour Water upon it, after a ftrong 
 Calcination, it may be reduced almoft totally to Cry- 
 ftals again. Likewife, Copper is not fo eafily de- 
 prived of all its Acid by Fire, as Iron is, though the 
 former be precipitated by the latter* 
 
 2. The Vitriols of Iron * and of Copper may 
 eafily be produced by Art, and even that of Iron by 
 fimply pouring upon it Oil of Vitriol, diluted with fix 
 or eight Times as much Water, when it is too much 
 concentrated ( Part I. § 109.) But the Solution mull 
 be left for one or two Days in a moderate Heat, and 
 more Iron be added than the Oil of Vitriol can dif- 
 folve. Then, when the Solution is thoroughly fepa- 
 rated, filtrate it, evaporate it, and reduce it to Cryf- 
 tals as before, and you will have green Cryfials : 
 This Solution alfo lets fall a great Quantity of yel- 
 low Oker during every Infpiffation ; and even when 
 you let it reft for one or two Days, it grows opaque, 
 and aflumes a rufty Colour. But, if you let fall into 
 it a few fmall Drops of Oil of Vitriol, to make it 
 very (lightly Acid, it remains long limpid, and if 
 it is infpiffated and put at Reft for a Cryftallization, 
 this yellow martial Earth doth not fubfide : The 
 Cryftals which are then produced, become lefs yellow 
 of a Grafs-colour, and keep their Whitenefs and 
 Tranfparency longer, but are a little more Acid. 
 Thence it is plain, how vain is the Labour of rhofe 
 who try to purify the Vitriol of Iron, by thefe re- 
 peated Solutions, Infpiftations, and Cryftallizations. 
 For, it is totally refolved into thefe okery Dregs, and 
 if it contains any Copper, there remains at laft almoft 
 mere V itriol of Copper. 
 
 * Vitriol of Iron is called Copperas y and is made in great Quan- 
 tities at Deptford near London, of rufty Iron, old Nails, &c. and 
 Pyrites. 
 
 3- if 
 
Assaying Metals. 409 
 3. If you throwalittleFilings of Iron into [a Solution 
 of] Vitriol made withInk-ftonesorPyrites,theCopper, 
 if it contains any, is precipitated to the Bottom ; fo 
 that with regard to it, it is as pure as the factitious 
 Vitriol of Iron (N°. 2.) 
 
 4. Vitriol of Copper is prepared in an inftant with 
 Oil of Vitriol as (N°. 2.) : But, this is not fo much 
 faturated with Metal : For, Copper does not fo readily 
 yield to Oil of Vitriol, as Iron does. The Opera- 
 tion fucceeds better, if you llratify Plates of Copper 
 with Sulphur in an Ear then- VefTel, fhut clofe with 
 a Tile and with Lute, and then put the VefTel into 
 the Fire, till it is middling red-hot. Thus the Plates 
 are corroded by the Sulphur, and become of a dark 
 Colour, and much thicker than they were before : 
 This is called burnt Copper. The Copper being pe- 
 netrated by the Sulphur, is afterwards roafled in a 
 moderate open Fire, till you no longer fee any ful- 
 phureous Flame : Thus by pouring Water upon it 
 you may get a very fine azure-coloured Solution of 
 Vitriol of Copper, which mull be reduced to Crys- 
 tals. 
 
 PROCESS LXXIV. 
 
 5 The making of Vitriol out of the Ores of Iron and 
 Copper, 
 
 A P P A R A r U S. 
 
 1. A Very great Quantity of common Vitriol, fuch 
 Jf\ as is fold in the Shops, is got out of Pyrites : 
 Some of them having very little or no Copper in 
 them, when expofed to the Air, turn of themfelves 
 to Ink-flones. Thefe are merely charged with Sul- 
 phur, and very little arfenical. However, they do not 
 all fo eafily turn to Vitriol : And feme of them will 
 not do it at all. They mult be beaten to a coarfe 
 Powder, and thus expofed to a pretty moift Air, 
 
^ x o The Art of 
 
 till their outward pyrjtofe Brightnefs and Hard nets 
 do totally difappear, and even the inward when they 
 are beaten afreftn Do the reft as in Proc . LXXIIf. 
 
 i. The other Pyrites, among which fome are 
 coppery, and impregnated with a great Quantity of 
 Arienick, and many purely ferreous and fulphureous, 
 require a previous Roafting. This is performed either 
 in clofe Veffe]s'(by which Operation the Sulphur is 
 collected together {Proc. -LX VII) ; or in a mode- 
 rate open Fired The Vitriol is not yet generated in 
 ibme of them ; but they muft be fjrft expofed to 
 „an open fomewhat-nioift Air, as N°. i *, or if the 
 Air is too dry, you promote' the Production of the 
 Vitriol, by now and then fprinkling them very 
 ilightly with Water. Then the Vitriol is produced 
 fooner or later in the feveral Pyrites. But fome 
 afford Vitriol immediately after the Roafting, though 
 in a much fmaller Quantity, than when they are af- 
 terwards expofed to the Air in the Manner above- 
 mentioned. Then, wadi the Vitriol clean. If you 
 expofe again to an open moift Air what remains of 
 the Edulcoration, which is called the Caput Mortvum , 
 it is commonly ftill impregnated with Vitriol, but in 
 a much leffer Quantity. 
 
 3. There are many Stones of Calamine, which 
 yield a no inconfiderable Quantity of Vitriol, imme- 
 diately after the Roafting : Nor is it neceffary to ex- 
 pofe them any more to the Air. 
 
 < The Ufe and Reafons of the Procefs . 
 
 1. We ought here to give the Reafon, why fome 
 Pyrites turn of themfelves very eafily to Vitriol, 
 when only expofed to a free Air, fome with greater 
 Difficulty, and a great many not at all, even in the 
 Space of many Years together : And again, why 
 fome Pyrites prefentfy yield as much Vitriol as 
 can be got out of them, when waffied in warm Wa- 
 ter, while fome muft at feveral Spaces of Time be 
 again expofed to a moift Air after the Roafting, But 
 
Assaying Metals. 41 i 
 
 this Matter has hot been examined fo clofely, but 
 there remain {till many Doubts about it. I fhall 
 here in a few Words mention the Difcoverits Dr. 
 Henckel the Author fo often quoted, has made by a 
 Multitude of Experiments, and communicated to us 
 in his Pyritology. 
 
 Viz. No Pyrites containing any Copper or Arfe- 
 nick, turn of themfeives to 'Vitriol, but they require 
 a previous Reading. 
 
 The fulphureous Iron-pyrites, void of Copper and 
 Arfenick, turn to Vitriol by the Addon of the Air, 
 and of the Things it contains, and this the quicker, 
 as they are Jefs compact : Such are chiefly thofe 
 which feem to confift of a Multitude of Fibres and' 
 Radii gathered together. But there are a good many 
 Exceptions to this : For there are Pyrites of fuch a 
 Kind, that they perfifl unchanged for whole Years 
 together. 
 
 Therefore we fee Copper and Arfenick refill this 
 Alteration of the Pyrites, and it likewife follows, 
 that there is another fecret Caufe hitherto unknown 
 of this Conflancy of the Pyrites, becaufe the Pyrites 
 which are merely ferreous and fulphureous, do not 
 at all turn to Vitriol of their own Accord. I have 
 expofed fuch Pyrites moderately pulverized and not 
 very hard, to the Injuries of the Air for whole Years 
 together, but they perfifl unchangeable to this very 
 Day. 
 
 2. It is fall lefs known, why Vitriol is found in 
 fome Pyrites, if you but pour Water upon them after 
 the Roafbng, while you find none in fome others, 
 unlefs you have expofed them previoufly to the Air, 
 "at different Times. It even feems that we are to 
 look in the Air for the Reafon of this, as it carries 
 mo ill Vapours with it. And indeed the Acid of Sub 
 phur has not the Virtue to refolve Iron into the Form 
 of Salt, without a fufficient Quantity of Water : 
 Nay, Oil of Vitriol or of Sulphur itfelf, being mo- 
 derately concentrated (though diluted with much 
 more Water, than it is when united ftill with Sul- 
 phur) 
 
412 The Art of 
 
 phur) does not even diffolve Filings of Iron, unlefs 
 you pour four or fix Times as much Water upon 
 them. But, the Thing being well confidered, it is 
 certain, that there is (till fome other hidden Caufe 
 of this ; becaufe it is not conceivable, why Water 
 poured upon fome Pyrites, does immediately extract 
 Vitriol out of them, and none out of fome others ; 
 and again, why fome crude Pyrites turn prefently to 
 Vitriol in a free open Air, and never when immerfed 
 under Water. I have met with fuch fulphureous and 
 ferreous Pyrites on the Shore of the Northern Sea, 
 that fhewed no Sign whatever of Arfenick and Cop- 
 per, neither before nor after their Being changed to 
 Vitriol. They were compofed of parallel Fibres al- 
 moft like Wood, very foft, and of a fine Brightnefs : 
 But they were covered with a coarfe Sand fome Feet 
 deep, which the Water of the Sea could penetrate 
 eafily enough, and they had no Manner of Tafte, 
 and confequently were altogether void of Vitriol. 
 But after they had been expofed to the Air for a 
 Fortnight, they loft intirely their Brightnefs, and 
 were become fo rich of Vitriol, that fmall green 
 Cryftals of the Size of Millet-feeds appeared on their 
 Surface, Now if the Moifture alone was fufficient to 
 produce this Effect, there is no Reafon, why they 
 fhould not have been refolved into Vitriol under a 
 very moift Sand. There remains ftill a wandering 
 foffile Acid, which fills alfo the aerial Region. Many 
 affirm, indeed, that this concurs to promote an abun- 
 dant Production of Vitriol, nor muft we by any 
 Means exclude it intirely, no more than the Moift- 
 ure of the Air. But whoever ferioufty confiders 
 what has been faid before concerning this, will own 
 that there are fome Conditions requifite for the Pro- 
 duction of Vitriol, which we do not as yet clearly 
 underftand. 
 
 3. We might here add fomething concerning white 
 Vitriol, and the other Species of factitious Vitriols ; 
 but we ftiall treat of thefe more at large on another 
 Occafion. 
 
 PRO- 
 
Assaying Metals. 413 
 
 OF ALLUM, 
 
 PROCESS LXXV. 
 
 Preparation of Allum . 
 
 APPARATUS. 
 
 1. HE Minerals of Allum, as well as thofe of 
 X Vitriol, mud be prepared many different 
 Ways, to get Allum out of them. For there are 
 fome alluminous, fat, bituminous Minerals, which 
 being heaped up in the Air, grow warm, fmoak, 
 crumble, and fome times take Flame*, but, this is not 
 done without fome Lofs of the Allum, and it mud be 
 prevented, by pouring Water upon and disjoining 
 the concrete Heap : They finally feparate, and af- 
 lame the fweetifh, ftyptick, naufeousTafte of Allum, 
 which before was but little or even not perceived at 
 all in this Mineral. Some barren Minerals, as well 
 as the Pyrites, require a gentle previous Reading, 
 which being done, the Allum is at lad produced. 
 Chufe out of this Heap a Specimen of fome common 
 Pounds, put it in a Lead or Glafs-veflel, and pour 
 upon it three Times as much Water : Make it boil, 
 and drain it through a' J Fibre ; pour again warm 
 Water upon it, and make it boil another Time, 
 that the remaining Earth may be well edulcorated. 
 Pour the Solutions together, and let them red for 
 one Day and one Night together, that the Dregs 
 may fubdde to the Bottom ; or drain it again through 
 the Fibre : Then, let the clear Liquor be fo in- 
 fpiffated as that it may fudain a new laid Egg put 
 into it : Let it grow cold again, and red four and 
 twenty Hours : At lad you will fee what will be 
 precipitated : For, Crydalsof Vitriol are fometimes 
 produced 5 and fometimes the Allum is expelled. Jf 
 
 it 
 
414 7 $*? Art of 
 
 it is Vitriol, you mu ft throw it away : But the Allum 
 muft be purified by a repeated Solution 'and Cryftali- 
 zation, which will be of a reddifti bay Colour. Con- 
 tinue the fame with what remains of the Solution, 
 till it is intirely exhaufted of Allum. 
 
 2, But if no Allum is precipitated, the Solution' 
 muft again boil on the Fire, then pour into it about 
 one twentieth Part of faturated Lye of Pot-afh, or 
 one third Part of petrified Urine, or alfo fome 
 Quick-lime : Mean while, continue to boil it : If 
 there is any Allum, a white Precipitate will begin to 
 be expelled, when the greateft Part of the Solution 
 is confirmed : Then let it cool and reft, and decant 
 the Solution from what is precipitated, and out of this 
 remaining Solution the Reft of the Allum will be pre- 
 cipitated in the Manner already mentioned, till there 
 remains at laft a thick Liquor void of Allum. This 
 done, diffolve again in a f Efficient Quantity of boil- 
 ing Water, all that has been precipitated, purify 
 it by letting it reft, or by Filtration, and reducing^ 
 to Cryftals according, to Proc . LXXIV,. 
 
 c ±he Ufe and Reafons of the Procefs . 
 
 i. Allum precipitated by itfelf, confifts of a mere 
 Earth, reduced into a Form of Salt by a vague foffile' 
 Acid. But this Earth is of a moil lingular Nature, 
 and different from the other native Earths that are 
 known. For, with Chalk, Lime, and Spaad, dif- 
 folved in this Acid, you will produce Salts fomewhat 
 like Allum, though never perfectly refembling it. 
 But, if this Earth is of that Kind, the Allum is white, 
 or of a light reddifti Colour : And when a Metal 
 mixes to it in the Form of Vitriol, it is tinged with 
 a bluifh green ifh Colour : And the Allum in this Cafe 
 muft be looked upon as 'impure. But, if the Precipi- 
 tation of Allum is performed by a Solution of *a fixt 
 Alkali, or of volatile putrid Urine, then, indeed, as 
 well as in all Precipitations, a great Deal of the pre- 
 cipitating alkaline Salt joins to the Allum: Which 
 
 fee ms 
 
Assaying Metals. 41 4 
 
 feems to be the Reafon why All am is fo lading, fuck 
 as are the Cry dais Compofed of Alkali, and of the 
 vague fofiile Acid united together, and will not eadly 
 abandon its Acid in the Fire. For when it is made 
 middling red-hot in the Fire, there comes out a very 
 little Quantity of Acid ; and if it is afterwards tor- 
 mented by the greated and longed Fire, you can 
 never extort any more of if, fo that on this Account, 
 the Caput Mortuum is mod commonly looked upon as 
 mere Earth, which neverthelefs is in the greated 
 Fart diffolvible by pouring hot Water upon it, and 
 may be almod totally reduced again to its Form of 
 Allum, by a reiterated Evaporation and Crydaliza- 
 tion. But the Alkali is poured upon it not only be- 
 caufe of the Precipitation of the Allum itfelf, but 
 alfo becaufe of the Separation of the Vitriol, - which 
 .other wife would be difficultly performed. You are 
 to take Care at the fame Time, not to add too much 
 Alkali ; therefore, it mud be poured in by fmall 
 Quantities, to be repeated feveral Times, till you 
 are fare of a jud Proportion. For the fame Pur- 
 pofe, an Addition of Lime is not ufelefs, and even 
 mud fometimes be fubdituted, for a greater Security. 
 As for the red, you mud here make the fame Qb- 
 fervations as were made about Vitriol ( Proc . LXXIV). 
 The remaining Earths and Dregs being expofedanew 
 to the Air, are again impregnated with Allum, but 
 not all of them. 
 
 Thefe Precedes about Allum, as well as thofe 
 about Vitriol, do not always agree fo exaddy with 
 thofe which are performed in greater Quantities, for 
 a greater Proportion is commonly produced in larger 
 Operations. For feveral Artifices mud be ufed in 
 every Cafe, which mud be underdood from the pe- 
 culiar Nature of each Mineral, by repeated Experi- 
 ments : Whence you mud generally repeat a few 
 Times thefe Examinations, before you are able to 
 pafs any certain Judgment* 
 
The Art of 
 
 416 
 
 OF NITRE. 
 
 PROCESS LXXVI, 
 
 The Preparation of Nitre . 
 
 APPARATUS. 
 
 1. \TT E have fpoken of the Generation of Nitre, 
 
 W or Salt-petre [Parti. §437, ; there 
 
 remains that we fhould treat of the docimaftical Ex- 
 traction and Purifying of it. The Preparers of Ni- 
 tre, commonly throw a few Pounds of the Earth, in 
 which they fufpeft there is any, into a wooden VefTel 
 with double the Quantity of warm Water, and ftirr 
 it feveral Times with a Stick : Then, they put two 
 fmall Copper-Difhes of equal Weight into one of the 
 Scales of a Balance that is pretty true, and a doci- 
 maftical Centner into the other Scale : They put fome 
 of the Solution drop by drop into the former, till an 
 Equilibrium is obtained. They put the Scale which 
 contains the Solution upon the Afhes, or upon Sand 
 that is middling warm, to make it thoroughly dry, 
 and weigh it again, to know how much there remains 
 of the Centner of the Solution of Salt. Then they 
 take the Salt out of the Scale, and tafte it, to fee 
 whether it is nitrous s and put burning Coals upon 
 it, to try whether it will deflagrate ; which fhews you 
 that the Nitre is pure, if there remains little or no 
 Alkali at all ; but if it decrepitates and flies afunder, 
 you may judge that it contains a great Deal of Salt, 
 and then the Nitre proves the worfe. 
 
 Another Method . 
 
 2. XT OU will find the Nature of it more exactly 
 
 j[ by the following Method. Take many com- 
 mon Pounds, for inftance twenty or thirty, of ni- 
 trous 
 
Assaying Metals. 417 
 
 trous Earth, and mix them with once and a half as 
 much of quick- Li me and alkaline Afhes, or add 
 indead of thefe half a Pound of Pot-afh : Put thefe 
 Things into a wooden Tub of a fufficient Capacity ; 
 pour upon them about the double Quantity of warm 
 Water, and leave them thus for lour and twenty 
 Hours : It is proper to ftirr the Whole now and then 
 with a wooden-Stick. Next, pour the whole Mafs 
 into a linnen-Bag : The Lye will dr it pa fs through 
 turbid *, pour it again into the Bag, to drain it a fe» 
 cond Time ; which done, it will be tranfparent and 
 yellow. This done, let it boil in a large Kettle, till 
 fo much of the Liquor be diffipated, as that a fmall 
 Drop of it let fall upon a cold Surface may congeal* 
 Take the Kettle from the Fire, and let the Solu- 
 tion cool for one Day and one Night : You will fee 
 whether any Crydals {Parti. § 21.) are produced* 
 Dilute the remaining Solution in the double Quantity 
 of warm Water : Then infpifiate it, and let it cool 1 
 Repeat the fame as long as Crydals will be produced 
 by the Solution : There will remain at lad a thick fat 
 Liquid, which may indeed be infpidated, but will 
 not turn to Crydals, and eadly runs to Water again 
 in the Air. 
 
 3. If you are willing to have thefe Crydals very 
 pure, difiolve them in eight Times as much Water 1 
 filtrate them through a Paper add to them a few 
 Drachms of Quick-lime, and make them diged with 
 it a whole Day. Drop into this Liquor a few fmall 
 Drops of an alkaline Solution. If, a little after, you 
 fee fmall Clouds in the Solution, go on, till it is no 
 longer turbid : It is never necedary to drop above 
 half an Ounce into it. This done, filtrate it through 
 a Paper ; evaporate it in a fhort Glafs-Cucurbite, and 
 when you fee a fmall Pellicle, let it grow cold. The 
 dower it cools, the larger and finer the Crydals will 
 be. You mud always dilute the Refidue with the 
 double Quantity of warm Water, before you expofe 
 it to the Evaporation, and repeat the Crydalliza* 
 tion* till the Nitre is entirely exhauded* 
 
 E e fh$ 
 
4i& The Art of 
 
 The Ufe and Reafons of the Procefs. 
 
 i. Nitre is produced out of foft Earths ^impregnat- 
 ed with fat and faline Particles of vegetable and animal 
 Bodies apt to come to a Putrefadbion. But Nitre is ne- 
 ver found perfect in them, unlefs fixt Alkali, ora limy 
 Earth be joined to them. It is then proper to add 
 alkaline Salts to the Earths in which Nitre is to be 
 generated, or at leaf! to mix alkaline Afhes or Lime 
 to them, while the nitrous Earth is boiling for a Lye. 
 For, it is certain from unqueftionable Experiments, 
 that thefe Things enter really into the Compofition 
 of Nitre. This is plain, from the abundant Quantity 
 of Alkali that comes from Nitre by Means of a very 
 fmall Quantity of Coals of Vegetables, having no fixe 
 Alkali in them, fuch as proceed from Muflard-feed, 
 and the like : For if fuch Coals being put upon melted 
 Nitre, detonate with it by increafing the Fire to a 
 high Degree, and the Mafs is brought to a Fufion 
 like Water after the Detonation is compleated, you 
 will have above one Half of fixt alkaline Salt, with 
 regard to the Nitre employed ; unlefs you have Bung 
 much of it out of the Vefifels, on Account of their 
 fmallnefs, or by putting imprudently too much Char- 
 coal at once. This Alkali is called fixt Nitre , and 
 is a little lefs Fufible than any other pure fixt Alkali, 
 becaufe of the fubtil calcareous Earth which is in it. 
 Nor does there then remain any Vefbiges of Nitre in 
 it, which is detedbed by pouring in Oil of Vitriol 
 to a perfedi Saturation. For, if there remains any 
 Nitre, this Refidue will affedt the Nofe with an 
 
 * Large Quantities of Nitre are extrafled at Paris , out of the 
 Rubbifh of old Buildings j which are there all made of Stone and 
 Stone-mortar. The greatefl Quantities of Nitre, whereof the Con- 
 fumption is now become fo great for the making Gunpowder, are 
 brought from the Eaji-Indies, but it is not yet known to us whether 
 it is an artificial Compofition made by the Inhabitants of the inland 
 Countries, or whether there really are any Mines of native Salt- 
 petre, or any natural Earths, out of which it can be extra&ed. 
 
 Odour 
 
Assaying Metals. 419 
 
 Odour of Spirit of Nitre, by expelling the Spirit 
 of it. This Prefence of fixt Alkali in Nitre, is like- 
 wife teftified by the Regeneration of it out of Spi- 
 rit of Nitre and Alkali. Nitre agitated with a itrong 
 Fire, in a fbrong open Crucible, is at laft diffipated 
 in Form of Smoak ( Proc . XIV), there remaining a 
 very final 1 Quantity of Alkali ; which is, however, 
 like wife diffipated by continuing the Fire, becaufe 
 it is not abfolutely fixt. Moreover, the fuperfluous 
 calcareous Earth, which has been introduced in a 
 faline Form by the Spirit of Nitre, and is contained 
 in the Lye, is precipitated by the fixt Alkali. This 
 appears in great Quantities, efpecially in the laft re- 
 maining Lye of the firft Cryftallization, unlefs it has ' 
 been already precipitated, during the boiling of the 
 Lye itfelf,. by the Abundance of Alkali : It is called 
 the white Manganefe. But we are informed, by drop- 
 ping in Oil of Vitriol, that there is Spirit of Nitre in 
 this Refidue ; and if it is diftilled with this Oil, the 
 collected Spirits are Aqua Regis : Becaufe there re- 
 mains fome common Salt in this Lye. 
 
 2. If Nitre is cryftalized a fecond Time, it isftill 
 purer. The fmall Clouds which appear at the Inftant 
 of the dropping in of the alkaline Solution, pro- 
 ceed from the fmall Refidue of white Manganefe i 
 But, the marine Salt is thoroughly feparated by this 
 fecond Operation, becaufe it being eafily diffolvible 
 in Water does not turn fo eafily to Cryftals, as 
 Nitre : Therefore, the firfl Cryftals are always purer 
 than thofe which are produced in the Cryftallization 
 of the Refidue : Which is confirmed by the Diftilla- 
 tion of this with Oil of Vitriol (See N°. i). 
 
 3. Mean while, take Care, never to make the 
 Evaporation and Cryftallization of the Salts in an 
 earthen-Veffel : For, let it be glazed ever fo neatly, 
 yet, all Salts, even the fixt alkaline ones, are not 
 only abforbed thereby, but even find fo ready a 
 Paffage through them, that lanuginous Cryftals fur* 
 round the Veflel on the Outfide, 
 
The Art of 
 
 4*o 
 
 OF COMMON SALT. 
 PROCESS LXXVII, 
 
 To try faline Waters* 
 
 APPARATUS* 
 
 S A L-gem may be extracted fimply out of Earths 
 and Stones with warm Water. But faline Waters 
 mud be purified, by either Filtration, or Reft. Let 
 feveral Pints of them be infpiffated by a ftrong Boil- 
 ing, till a thin Pellicle, or fmall Cryftals appear on 
 the Surface of the Liquor. Next, the Fire muft be 
 diminifhed, that the faline Brine may be only mid- 
 dling warm, and fmoak : The Cryftals which were 
 fmall at firft, will grow of a larger Size : They 
 are of the Figure of a hollow, truncated Pyramid, 
 open at the Bafts, made of a Heap of fmall Cubes, 
 which being become large at laft fink to the Bottom 
 of the Solution. But, if you ufe a ftronger Fire, the 
 whole Surface of the Brine will be covered with an un- 
 formed faline Cruft, which, hinders all further Ex- 
 halation, unlefs you break and precipitate it to the 
 Bottom. When it is fo far infpiffated, as that the fa- 
 line Cryftals may be almoft even with its upper Sur- 
 face ; you muft decant the Brine from the fubfiding 
 Cryftals, and this muft be infpiffated in the fame 
 Manner : The Cryftals of Salt being collected, and 
 dried by a gentle Heat, muft at laft be weighed. 
 
 The Ufe and Reafons of the Proctfs. 
 
 You may plainly fee from thefe Procefles, how 
 common Salt may be feparated from other Salts 
 eafi ]y turning to Cryftals, and chiefly from Nitre. 
 For feme Salts are difficultly and in fmall Quantity 
 
 diflolved 
 
Assaying Metals. 421 
 
 diffolved in cold Water, but they melt mod quickly 
 and in great Quantity in warm Water. Such are 
 Nitre, Tartar, Tartar vitriolate, all Vitriols, Allum, 
 &c. fome of them melt eafily enough and in good 
 Quantity, equally in cold and warm Water ; nay, 
 even in the Air, when they have abforbed the 
 Moidure of it : And though they melt a little 
 quicker in warm than in cold Water, yet the Diffe- 
 rence is very fmall. Of this Nature are, common Salt, 
 vegetable fixt alkaline Salts, and even feyeral neutral 
 Salts diffolvible in the Air. Therefore, the lefs the 
 Difference of the Quantities of the Salts which are 
 diffolved both in warm and cold Water, is, the lefs 
 Quantity of Crydals you will get, and on the con- 
 trary. You will underhand this better, if illudrated 
 by an Example. Let Nitre be diffolved in cold Wa- 
 ter, to a Saturation ; and the Solution boil in an 
 open Veffel : The Water will be fo difpofed by the 
 Heat, as that a much greater Quantity of Nitre may 
 be diffolved, befides what is already fo : Which may 
 be eafily experienced. But, fo foon as the Water be- 
 gins to be diffipated into Vapours, it at lad dimi- 
 nifhes to fuch a Degree, that it can no longer con- 
 tain all the diffolved Nitre, which being then at the 
 Surface which is lefs warm, is neverthelefs fird of 
 all deprived of its Water, and expelled in Form of 
 a fmall Pellicle, which retards the further Evapora- 
 tion. If you continue to infpiffate by increafing the 
 Fire, the whole Nitre turns to an unformed Mafs : 
 But, if the boiling Solution is put in a cold Place, 
 there remains as much Nitre in the Solution, as may 
 have been diffolved in that Degree of Cold, by a 
 Quantity of Water equal to that which is in the So- 
 lution. The red is feparated in Form of Crydals, that 
 is, above half of the Nitre, if the Atmofphere is 
 very cold ; and lefs, if it is very warm. Apply the 
 fame to Brine. But as a cold and very faturated So- 
 lution of common Salt admits but very little more 
 Salt, if it is made warm, the fmall Crydals appear 
 at the Surface, in the very Beginning of the Evapo- 
 
 E e 3 ration^ 
 
4zi The Art of 
 
 ration, and are very little increafed when the Brine 
 grows cold. Now, if you fuppofe that Solutions of 
 Nitre and Salt are mixt together, and confider, at the 
 fame Time, that the Salt will be better diffolved by . 
 cold Water than the Nitre, you will eafily conceive, 
 why the Cryftals of the Nitre are feparated, while 
 the Salt remains in the Solution. 
 
 OF GLASS. 
 
 Our chief Defign does not require that we fhould 
 give in the following Proceffes a compleat Account 
 of the Art of making Glafs. It will not be ufelefs, 
 here to infert only a few Proceffes concerning Glaffes 
 tinged by Minerals, and to add thofe Things which 
 are neceffary to underftand the faid Proceffes. For 
 one has attempted to guefs from the Colours which 
 Glaffes borrow from the Minerals that are mixt with 
 them, what Kinds of Metals they did conceal. 
 Therefore, you will plainly fee from the following 
 Proceffes, whether this peculiar Kind of Trial may 
 be done, and how far it may be carried. 
 
 PROCESS LXXVIII. 
 
 To try, how much Glafs , the Caput Mortuum of C oh alt 
 or of Bifmuth , will he able to change into blue 
 Smalt . 
 
 APPARATUS . 
 
 i. /^HUSE clean fufible Sand, or Flints that 
 are white, or at leafl that can be rendered fo 
 by Calcination j put what Quantity of them you pleafe 
 into a Crucible, and expofe it to a pretty fir on g Fire : 
 Pour the Mafs quite red-hot into a Trough full of 
 cold Water. By this Means, the fmall Stones will 
 be fplit, and rendered fitter for a more eafy Pulve- 
 rization : Pour out the ^turbid Water, and grind 
 
 your 
 
Assaying Metals. 423 
 
 your Stones thus prepared in a very clean Iron-mortar* 
 or upon a very hard Piece of Porphyry, to a fubtile 
 Powder. 
 
 2. Take four Parts of this Powder, as much of 
 Pot-afh, or of fome other alkaline fixt Salt well pu- 
 rified, and one Part of Cobalt well roafted, or of 
 eliquated Bifmuth-ore, both likewife comminuted, 
 and pound them together in a Mortar, that they may 
 be thoroughly mixt : Let them melt for a few Hours 
 in a well tried Crucible covered with a Tile, in a 
 moft violent Fire having a Draught of Air. When 
 the Crucible is taken out of the Fire, cool it by 
 fprinkling it with Water, and then break it : Exa- 
 mine the fmall Bits of Glafs, whether they are opa-. 
 que, of a very dark blue and almoft blackifh Colour ; 
 and finally, whether they are ground to a finer Pow- 
 der, and appear of a pleafant light blue Colour. If 
 the Colour is too light, and the larger Bits of Glafs 
 almoft tranfparent, you muft add two or three 
 Times more of Caput Mortuum of Cobalt, or of Bik- 
 ini] th ; fubft racking fomething, if the Colour proves 
 too deep. 
 
 3. If inftead of the firft Mixture, you ufe Glafs 
 pretty tranfparent, without any Colour, and already 
 made of Flints and Salt, it will be the fame Thing : 
 But as this is refractory not only of its own Nature, 
 but is alfo rendered fuch by the Cobalt, it is proper 
 to add moreover one third Part of Pot-afh with re- 
 fpect to the Cobalt. 
 
 Ti he Ufe and Reafons of the Procefs . 
 
 1. This Earth which tinges Glafles with a blue 
 Colour, has been found only in the Cobalt of Arfenick 
 and Bifmuth, and it may be known ex tempore , if you 
 but melt it with two or three Times as much Borax, 
 on Account of the fpecifick blue Colour which it gives 
 to this Salt. It isnotmetallick: At leaft, Artificers have 
 not been able, by anyMethods hitherto-known, to ex- 
 trad any Metal out of them ; unlefs there remains per- 
 
 Ee 4 haps 
 
424 The Art of 
 
 haps a little Bi {mu th in the Caput Mortuum , the Regulus 
 of which, being colle&ed in larger Preparations of 
 this Smalt, is commonly poured off before it is flung 
 into Water, left all fhould fly about, with great 
 Danger to the Operators, or the Houfe be fet on 
 Fire. But there are Cobalts void of Bifmuth : Nor 
 is even this Colour produced by Bifmuth *, nay, 
 Glaflfes melted with Bifmuth are tinged with a pecu- 
 liar purplifh Colour : In fhort, this Colour can no 
 Way be derived from Copper, nor produced by any 
 Artifice whatever. But Smalt is produced better 
 from one Species than from another ; and is made 
 of the beft Kind, out of the Caput Mortuum of the 
 Ore of Bifmuth. 
 
 2. As for the reft, you are to obferve that this 
 blue Smalt contains a great Deal of Arfenick : Be- 
 caufe it mo ft ftrongly adheres to all Salts and Earths, 
 and emits, when melted in a violent Fire, an arfe- 
 nical Fume, different from the Vapours of flxt alka- 
 line Salt detained by a great Fire. The managing 
 of it with Copper, and finally the Solution of this 
 Smalt by a great Quantity of Alkali both in Fire 
 and Water, fhew this to be true. 
 
 PROCESS LXXIX. 
 
 4 
 
 To find out what Sort cf Metal lies hidden in an Ore 
 unknown , from the Colour it gives to Glajfes . 
 
 APPARATUS. 
 
 I. O AST your pulverized Ore in a Fire ftrong 
 enough to make it middling red-hot, in a 
 Vefiel that is covered, to keep all Filthinefs from 
 Falling into it. Mix a few Grains of this Powder 
 with one Ounce of cryftaliine Glafs reduced to a fub- 
 tile Powder ; taking all imaginable Care, that no- 
 thing metallick, or of any other heterogeneous Body 
 that tinges Glafies, may mix to it. Let them be in 
 Fufion for fome Hours, in a Fire, having a Draught 
 
Assaying Metals. 425 
 
 of Air ; then, take out the Veffel ; let it grow cold, 
 and then break it. They endeavour to judge from 
 the Colour of the fmall Bits of Glafs, what Metal, 
 or metallick Earth, was contained in this Ore ; for 
 Inftance, from the green Colour they conclude that 
 it contained Copper, from the green iffi rufty, that 
 Iron, from the whitiffi and milky, that Tin, 
 and fo on. If the Tindlure is not fo fenfible, the 
 Operation muft be repeated with adding a greater 
 Quantity of the Ore. 
 
 cfhe Ufe and Reafons of the Procefs. 
 
 1. This Method of trying Ores has not yet been 
 made ufe of enough, fo that one may conclude any 
 Thing certain from it. I fhall boldly fay, that in 
 molt Cafes you cannot with any Probability conjec- 
 ture what Metals lie hid in Minerals : And that 
 there is no thinking of the Quantity of them. The 
 following Obfervations render the Thing very diffi- 
 cult, and even makes one defpair entirely, that ever 
 the Art of making Glafs, as to the tinging them with 
 metallick Colours, will be brought to Perfedlion, 
 and the Art of Allaying Metals be fufficient to that 
 Purpofe. For firft, the Colours of Metals, 
 
 * Precious Stones are fuppofed, in their natural State, to be origi- 
 nally of two Claffes, the Adamantine and the Crydalline ; if they 
 are found in their Matrix's untainted by any metalline Subftance, 
 they remain pure Diamonds of the cleared: fined: Water, or Cryftals 
 perfeftiy tranfparent ; but if a Diamond is tinged with Lead it 
 appears yellow ; if with Copper and Iron, it becomes green, and if 
 with Cinnabar, it makes a moil beautiful red, and then changes its 
 Name to a Ruby, and lofes of its Hardnefs in Proportion to the 
 Mixture of the Metal with it : A Crydal tinged with Iron becomes 
 a Garnate ; with Copper and an Alkali, a Saphire ; with Copper and 
 an acid, an Emerald ; with Lead, aTopaz andajacinth ; withGold, a 
 Chryfolite ; with Copper and Iron, an Ao^emarine, and fo on in 
 many Varieties (See Woodward's Method of Fofiils, p. 23, and foil . ) 
 and each of thefe latter may be imitated, by mixing Preparations of 
 Metals with the fined: white flint-Glafs, by which Method all Sorts 
 of Gems being counterfeited, are called Pades, and are ufed to take 
 off Impreffions of antique Intaglio's and Cameo's . 
 
 whether 
 
"The Art of 
 
 whether fimple or mixt in any Proportion and Man- 
 ner whatfoever, whether calcined or joined to Glades, 
 differ very much according to the Degree and Dura- 
 tion of the Fire, which you have employed during 
 the Calcination of the Metals, and the Fufion of them 
 with Glafs when they are melted •, fo, that it is hardly 
 credible, that the lame Glafs, taken out of the Fire 
 at different Times, Ihould appear under fuch a Va- 
 riety of Forms ; nay, that the Colours of it fhould 
 vanilh entirely. Secondly, there are Metals the Calx's 
 cf which give Glaffes a light Colour, and others which 
 being calcined make them of the deeped Dye : 
 Whence it happens, that when fuch Bodies are mixt 
 together, the Colour of the one or the other grows 
 quite obfcure, and vanifhes entirely. But, there are 
 feldom Ores, in which one (ingle Metal lies hid alone : 
 And there are almod always two or more of them 
 joined in the fame Matrix , and in a Multitude of 
 Ways, Proportions, and Qualities. But then the 
 Colours relulting therefrom, are of the greated Va- 
 riety, difiinguifhable again by the Eye, but impoffi- 
 ble to be defcribed, and fo infinitely multiplied, that 
 the moft experienced Artificer could hardly indicate 
 the lead Part of their Caufes. Other Metals, on the 
 contrary, will not manifed themfelves at all by any 
 Colour, in fuch a Mixture. Let there be, for Indance, 
 Ores, in which Lead and Copper lie hid in many 
 Proportions, the Copper, however, not being in too 
 fmall a Quantity therein. Melt one Ounce of crydal- 
 line Glafs with a few Grains of this Ore : The Co- 
 lour will prove of a bluifh green Dye, and the Lead 
 that was hidden in that fmall Quantity of Ore, 
 though it were ten Times more than the Copper, 
 will not in the lead betray its Prefence by the Co- 
 lour, nor will the fpecifick Hardnefs and Weight of 
 the Glafs be fenfibly increafed by fo minute a Quan- 
 tity : If you add a great Deal of the Ore, the Colour 
 will be totally obfcured by the Copper. The fame 
 will, in this Cafe, take Place in Tin, Silver, Gold, 
 and Antimony. Thirdly, there are other Bodies 
 
 not 
 
Assaying Metals. 4 17 
 
 not metallick, which not only give Glafies the deep- 
 ed Colours *, but alfo reduce the dedroyed Colours 
 which had been fird produced by Metals. Such are 
 the Capita Mortua of Cobalt and Bifmuth, feveral 
 Bodies merely terredrial, inflammable, fuliginous, 
 &c. From thefe Matters of Fadl it is plain, that 
 thefe Vitrifications ought to be performed with the 
 utmod Care and Circumfpeclion, and much more 
 neatly than all the other chemical Operations ; fince 
 they may be diflurbed by fo many very fmall and 
 hardly perceptible Caufes. 
 
 2. I fhall, in favour of thofe who love to make 
 Experiments about Vitrifications, here ftiew in a few 
 Words, how they can be performed conveniently 
 with the lead Apparatus and Expence : For which 
 Purpofe, I fhall, to the belt of my Power, here col- 
 led: and mention what Authors have told us on this 
 Matter, and what I myfelf am fure of from my own 
 Experience. The Authors who have given us the 
 Things chiefly appertaining to our prefent Purpofe, 
 are Antonius Neri , an Italian Pried, on whofe Works 
 Dr. Merret has given us a Commentary, and tran- 
 flated them from the Italian into Englijh , and then 
 into Latin. Kunkel has added Notes to both, more 
 valuable than the two foregoing, as he has confirmed 
 what was true, mended the Errors, and, what is 
 much more, unfolded immenfe Difficulties by them 
 left unravelled* the whole written in the German 
 Language *. 
 
 The Furnace that is neceflary for thefe Experi- 
 ments, is reprefented in Tab. VI. Fig. I, II, and III, 
 and defcribed at the End of this fecond Part. I have 
 at lad, by much Experience, fo adapted this Furnace 
 to thefe Operations, that a much more violent Fire 
 may be applied to the Veflels, and many of them be 
 put at once into it, and the Readings and Calcina- 
 tions, here requifite very long, may be performed in 
 
 * But will foon be publiflied in Englijh , being already tranflated 
 by the ingenious Dr. Hampe* 
 
 the 
 
42.8 The A rt of 
 
 the fame Fire. I fhall then defcribe this Furnace, fo 
 as that it may be eafily conftrudled by any attentive 
 Reader : And for the clearer Underftanding of this 
 Matter, I have given the Figure of it, to be feen at 
 the End of this Book. 
 
 For the Matter of it, chufe Stones that will bear 
 the ftrongeft Fire. You will eafily obferve this, if 
 you ufe a Stone for the Support of a Crucible, in 
 which, for In fiance, a ftrong Fufion of Copper is 
 performed : If this Stone does not adhere to the Bot- 
 tom of the Crucible when it is taken out, nor looks 
 to be run to Glafs *, except perhaps it has a very thin 
 vitreous Cruft, nor contrails Chinks, and preferves 
 its Hardnefs when grown cold, it is very fit for the 
 intended Ufe. You may inftead of Cement ufe a 
 clayey * Matter, of which the fame Stones, or 
 Bricks -f, and the docimaftical Furnaces are made. But 
 your Stones muft be fo fitly adapted to each other, 
 that the thinneft Stratum of Lute may be fufficient 
 to conglutinate them. 
 
 Let the Room in which it is to be conftrudled, 
 have a Funnel that gives a rapid Motion and Draught 
 to the Smoak : All the large Railages opened to the 
 Air muft be fuch as may be fhut, and the Furnace be 
 made near this Chimney, in fuch a Place, as that the 
 Artificer may freely move round it. 
 
 The outward Figure of the Furnace may be cylin- 
 drical and arched at Top. Let the outward Diame- 
 ter be twenty four, or more Inches, according to the 
 Difference of the Stones *, the Height muft be forty 
 eight Inches : The Thicknefs of the Wall, where it 
 is thinneft, muft be four or fix Inches at leaft. The 
 inward Cavity is divided into four Chambers, which 
 are formed according to a parabolick Line. The 
 lowermoft ferves for an Afh-hole, and is twelve In- 
 ches high, and its greateft Diameter at Bottom four- 
 teen Inches. Whence the Defcription of the Para- 
 bola is felf-evident. Let this Arch be open at Top 
 
 * Windfor Loam or Sturbridge Clay will anfwer this Purpofe. 
 
 f Windfor Bricks. 
 
 with 
 
Assaying Metals. 419 
 
 with an Hole ten Inches wide *, fo that there may be 
 left in the Back of it, a Margin two Inches broad 
 round the Cavity of the Furnace. This Margin 
 ferves to fupport prifmatical, quadrangular, iron- 
 Bars, which muft be put upon the round Hole, inftead 
 of a Grate. Thefe Iron-bars are faftened with a Stra- 
 tum of the belt Lute of the fame Thick nefs of theBars, 
 at the Place where they reft upon the Margin. This 
 Lute muft be neatly fmoothed, that fmall Veffels may 
 be fet upon it all round. Leave at the Bafe of the 
 Afh-hole, a fquare Open-Door, fix Inches broad, four 
 Inches high, with an iron Door hung on Hinges. 
 
 The other Chamber built upon the foregoing, is a 
 ftre-Place to put in the Fuel of the Fire, and of the 
 fame Breadth and Height as the foregoing ; unlefs 
 the Stones it is made of are lefs durable in the Fire : 
 For, in this Cafe, it muft be a few Inches broader* 
 and be covered over with a Cruft as many Inches 
 thick, of the beft Lute that will bear the ftrongeft 
 Fire. Let the Top of the Arch be perforated with a 
 round Hole fix Inches in Diameter, round the Cir- 
 cuit of it the Arch muft not be thicker than a Fin- 
 ger’s Breadth. Let there be upon the Back of this 
 Arch a Pavement four Inches broad, to put the Vef- 
 fels upon. Make in the Circumference of this 
 Chamber feven equidiftant Doors, fix of which muft 
 be four Inches broad, and as much high, and the 
 feventh two Inches larger, all of them terminated 
 a top by the Arch. Let the Bafes of them be the 
 Height of two Inches diftant from the Margin upon 
 which the Iron-bars are fixt, which Margin muft be 
 confidered as the Pavement of this Chamber. Let 
 the Wall at the Bafts of each Door, and at the above- 
 mentioned Interval, be cut out on the Infide to one 
 third Part of its Thicknefs. But, let all the Doors 
 be of Iron, hung on Hinges, and made in the fame 
 Manner as Part I. §239. N°. 4, coated two Inches 
 thick. When fhut, they muft be received into a 
 Groove, cut on the Infide in the Wall, of the fame 
 Depth as that of the coated Door ? and but a few 
 
 Lines 
 
430 The Art of 
 
 -Lines broad : Let there be befides a frnall Hole at 
 the Top of each Door, that one may conveniently 
 look into the Furnace. 
 
 The third Chamber built over this, is perfectly 
 like the two foregoing, except that the Arch is a few 
 Inches lower, and there is a quadrangular Hole com- 
 municating from this Arch into the fourth Chamber, 
 not in the Middle but towards one Side, and cut equi- 
 lateral, being four Inches fquare. 
 
 The fourth and laft Chamber is arched, equal in 
 Breadth to the foregoing, and only eight Inches high. 
 On the Side oppofite to the Hole which from the 
 other Chamber communicates into this, at the Height 
 of two Inches above the Pavement, let there be a. 
 cylindrical Funnel, made of an Iron-plate, and four 
 Inches in Diameter, which leads the Smoak and the 
 Flame into the Chimney of the Room. Let a Paf- 
 fage into this Chamber be open, through a Door fix 
 Inches wide, and as much high, juft above the 
 Pavement of the Chamber, opened in the Middle 
 of the Circumference, between the quadrangular 
 Hole and the Funnel. To which Aperture let an 
 Iron-door be hung, that theVefifels may be conveni- 
 ently introduced, and taken out. 
 
 Ufe this Furnace in the following Manner. Make 
 a Fire in the fecond Chamber : And ufe for your 
 Fuel Charcoal or Wood very dry, efpecially Beech, 
 which muft be put in through the largeft Door of 
 this Chamber. As to the Choice of the Fuel for the 
 making of a ftrong Fire in general, obferve what 
 follows. If you have a Mind to urge with the 
 ftrongeft Fire a Body furrounded on all Sides with 
 Fuel, you muft in this Cafe chufe the Coals that are 
 of a frnall or a middling Size, nor muft you put be- 
 tween the Grate and the VelTel which contains the 
 Body to be changed, a Support higher than three 
 FingePs Breadth, if the Veflel is very large ; 
 nor lower than one FingePs Breadth, if it is very 
 frnall. But, if the Vefifels are put at the Side, or 
 above the Fuel, as is moft commonly done in this 
 
 F urnace. 
 
Assaying Metals'. 431 
 
 Furnace, that they may be expofed to a ftrong Heat, 
 and to a very quick Flame, you are to chufe larger 
 Pieces of Wood and Charcoal. Now, if you open 
 in the Wall of the Room, a Hole fomewhat larger 
 or at lead equal to that which is at the Bottom of the 
 Afh-hole, and make a Pipe or Trunk of iron-Plates 
 leading from the former into the latter, and on the 
 other Hand Hunting the Room very clofe all round, 
 that the Air may not rufh in too freely ; then, the 
 Blaft of Air that pafles through this Trunk, is the 
 ftronger, as the Chimney of the Room grows the 
 warmer : Whence the greated Degree of Fire pro- 
 duced by a Draught of Air, is at lad obtained. But 
 the Fire will be of the utmod Strength at the fmall 
 Doors of the fecond Chamber, fo that a few Ounces 
 of Copper being flung without any Addition into a 
 Crucible that is red-hot there, will melt in a Mi- 
 nute, being agitated by a Fire greater than is necef- 
 fary for the pouring of Copper into a Mould, to re- 
 prefent any certain Figure. The Veflels are put in 
 through the fmall Doors, and are put upon the Mar- 
 gin, whereon the iron-Bars which form the Grate, are 
 placed. You may place as many Veflels round the 
 Circumference of the Chamber as there are Doors in 
 it. The Veflels which are put in, before the Fur- 
 nace is perfectly warm, may be put upon a low 
 Support, made of a Stone one Inch thick, and not 
 eafy to be vitrified. You may fee and try the Mat- 
 ter in the Veflels, through the fmall Hole made in 
 each of the Doors that are hung on Hinges. In the 
 third Chamber, you may, on Account of its Pave- 
 ment’s being much broader, put a double Row of 
 Veflels therein, that is, twelve in Number, ormore^ 
 if they are of a middling Size. The Fire is milder 
 in this Chamber than in the foregoing, viz. a mid- 
 dling melting Fire. Finally, the Fire is much more 
 gentle in the fourth and uppermod Chamber, and is 
 of very great Ufe for Calcinations and Readings, to 
 be made in a middling Fire : But then, indeed, the 
 Veflels do but grow red-hot there. If you have a 
 
 Mind 
 
43i The Art of 
 
 Mind to put your Veftels in the Furnace already hot, 
 they mud be previoufly made very warm *, then, 
 they are able to bear the Heat in the fourth Cham- 
 ber, out of which they may at laft be put into the 
 Third or Second, when they are already red-hot. 
 
 You mud, before this Furnace is conftrucfted, 
 make an Apparatus for feveral Operations : And thus 
 you will perform a great many Experiments, with 
 very little Trouble and Lofs of Time : So that I 
 can affure my Readers, that none have been more 
 agreeable to me than thofe I have made in this Fur- 
 nace, though they are extreamly tirefome by any 
 other Method, on Account of the ftrongeft Fire 
 which mu ft be continued fo very long. 1 do not 
 indeed exaggerate, in faying that all the Operations 
 are twice aseafy, when you knowhow to make a right 
 Ufe of this Furnace. 
 
 For want of it, I formerly ufed with fome Succefs 
 the Athanor defcribed ( Part I. Plat . IV. Fig. I.) by 
 applying to the Afh-hole of it a Wind-pipe, like that 
 applied to the foregoing : I put the Veftels that 
 
 were fet upon low Supports, into the Chamber next 
 to the Tower: I took quite away the iron-Lamina 
 which intercepted the Paflage of the Fire : I ftopt 
 the fore part of the Chamber, with a Wall made of 
 Cement and Brick, in which I left two fmall Doors, 
 to introduce and take out the Veftels, which Doors 
 might be ihut with Stopples. I placed the Veftels to 
 which the ftrongeft Fire was to be applied, next to 
 the Hole which conveyed the Fire from the fire- Place 
 that was in the Tower, into this Chamber : And 
 thofe which required a more gentle Fire, I placed 
 in the Middle, and over-againft the foregoing : But, 
 as the Stones were not of the belt Kind, and the Fire 
 continued for two Days together was moft violent, 
 the Furnace was a! moft deftroyed, and the Supports 
 of the Veftels almoft immerfed in the vitrified Stones 
 though no Glafs had run out of the Veftels : Which 
 muft be prevented with all imaginable Care *, for, if it 
 
 happens 
 
Assaying Metals. 433 
 
 happens fo a Number of Times, your Furnace will 
 be totally deftroyed. 
 
 They ufe for their Yeffels in Part common Cruci- 
 bles, and melting Difhes, which are put into the 
 Furnace either open, or covered with Tiles. But, if 
 you have a Mind often to try and ftirr up the Matter 
 within them, and are at the fame Time to avoid the 
 falling of Afhes, which fly about, into the Veffels, 
 you muft make an Hole in the upper Part of the Yef- 
 fel on one Side, and then cover it with a Tile to be 
 faftened with Lute. You may alfo make on Pur- 
 pofe fmall cylindrical Yeffels fhut clofe at Top, 
 having a like Aperture. If they are put into the . 
 Furnace, their Opening muft look towards the Door. 
 
 If you ufe triangular Veffels, the Angle muft look 
 towards the Centre, and the oppofite Side towards 
 the Door : For, if you negled this, the Yeffels will 
 eafily fplit, as they are put in. Therefore, we will 
 omit all the Methods of making figured Glaffes i 
 only the Compofitions of them. 
 
 We have already given a general Definition of Glafies 
 {Part I. § 8. Sc hoi. 451—2.) They are in part the 
 fimple ones , which may again be fubdivided, 1. Into 
 merely tereflrial , to which Clafs all the vitrefeent 
 Stones do belong, and it is all one whether they are 
 crude or already melted : For, the crude vitrefeent 
 Stones have all the Charafterifticks of Glafs. 2. In- 
 to metallick , that is, the Metals and Semi-metals 5 
 all of which, except Gold, Silver, Mercury, and 
 Arfenick, turn to Calxs properly fo called, by Means 
 of a gentle Roafting, and into Glafs at laft, by 
 applying a ftronger Fire to them. They are alfo in 
 part compounded ones . Now they are compofed ei- 
 ther of the fimple Ones juft mentioned, or alkaline 
 and neutral fixt Salts are added to them* of which 
 we are going to treat in a more fpecial Manner, 
 
 * Of Sturbridge Clay. 
 
 Ff 
 
 P R Oi 
 
434 
 
 The A rt of 
 
 PROCESS LXXX. 
 
 The making of common Glafs , and the Extraction of 
 Salts out of Afhes , for the 'preparing of it. 
 
 APPARATUS . 
 
 i. A LK ALINE fixt Salts produced out of 
 jOk burnt Vegetables, melted together with vi- 
 trefcent Earths, turn to wha.t is called common Glafs, 
 The alkaline Salt, with its Matrix Earth, that is, 
 Salt-afhes remaining after the burning certain Vegeta- 
 bles, being melted in a flrong Fire, turn to Glafs, 
 with which you may likewife melt a Quantity 
 of Sand, or of pulverized Flints, which may be 
 in greater Proportion, as the Afhes were more Salt. 
 This Glafs is the hardeft of all, more refradory in 
 the Fire than the other common Glaffes, perfectly 
 refilling the Air and Water, and all liquid Menfirua 
 that are known : On which Account it is not to be 
 eileemed lefs than the finefl cryflaline Glafs, becaufe 
 of its vaft Ufefulnefs. Its Colour is commonly of a 
 dark green Dye, fometimes quite opaque and black. 
 The Reafon of this incomparable Durablenels con- 
 fifts in the perfed Mixture of the Salt and the Earth, 
 as likewife in the great Quantity of the latter, where- 
 by it furpaffes the former much more than in any 
 other Glafs. Salt, for Inflance, is moll equally and 
 minutely divided through the Afhes ; whence its 
 diffolving Virtue is fo much increafed, ; that this little 
 Quantity of Salt is able to bring fo great a Quantity 
 of a ,very refradory Earth, to a State of Fufion, 
 The Afhes being deprived of all Salt, by repeated 
 Roaflings and Edulcorations, and rendered fo pure 
 as to be ufed for the making of Coppels, if you mixt 
 them again with their proper Salt, and put them in 
 jhe ftrongefl Fire fit for melting Glafs, it will never 
 
 be 
 
Assaying Metals. 43 j 
 
 be poflible to bring them to fhch a Degree of Fu- 
 fion, as that traceable Glafs to be figured by blowing, 
 may be made out of them ; though this Salt lying 
 Fill hidden in its own Earth of the fame Kind, was 
 able to diffolve not only the faid Earth, but alfo 
 one third Part, and even more, of the Sand which 
 had been added over and above. 
 
 2. To make clear common Glafs more tranfparen t> 
 you mu ft extraCt the Salt out of the faline Allies of 
 anySorts of Vegetables. But you muftchufe Vegetables 
 that have been gathered in their perfeCt Growth, not 
 expofed long to the Injuries of the Air, nor very 
 old neither : ' For, the Rains and the Air it.felf at laft ' 
 walhoff and confume that, out of which fixt alkaline 
 Salt is afterwards to be produced by Fire. Nor can 
 you even produce out of all Vegetables, a Quantity 
 of fixt Alkali that will repay your Charges and 
 Troubles : You muft confult the Experiments of Che- 
 mifts upon this Matter. All thefe Salts are perfeClly 
 the fame, after they have been duly purified, as is 
 obferved by Kunkel : For this Reafon, it is altogether 
 needlefs, to prepare, for the compofing of Glaffes, 
 lb many Salts, fo difficult to be got,, and on this Ac- 
 count fo very dear : Since a fingle Kind of Salt ex- 
 tracted out of the vileft Vegetable, is as good and 
 fufficient for your Purpofe, as all the others toge- 
 ther 1 . The Extraction of Salt out of the Allies, 
 and the Purifying of it is performed, i. By Solution 
 in about three Times as much warm .Water, with 
 which the Allies muft boil for a while, and be itirred 
 now and then with a wooden Stick. 2. By (training 
 through a filtrating Paper, or through a Linnen-bag : 
 Which muft be repeated by pouring back the Water 
 over and over again, till the Lye paffes through quite 
 clear. 3, By Evaporation, which is performed in an 
 Iron- pot well cleaned of all Ruft. During the Eva- 
 poration, you are to avoid that any Allies fhould 
 
 * The Sea-weeds, efpeeially that Sort called Kali or Glafs- 
 wort, abounds moil with this Sort of Salt. 
 
 Ff 2 
 
 fall 
 
43 6 Art ^ 
 
 fall into it, and you muft make under. it a Fire that 
 makes it boil gently : But you muft firft have a fuf- 
 ficient Quantity of Lye ready, that you may be able 
 to fill the Pot eight or fix Times at leaft. Nor muft 
 you pour more at once than is neceffary that the Pot 
 may be half-full, left the Salt fhould form a Cruft in 
 the upper Part of the Pot, that would be difficult - 
 to feparate. As much Water as is diffipated by Eva- 
 poration, fo much frefh Lye muft be now and then 
 poured into the Pot. When the fmall Clots of Salt 
 begin to thicken, and to appear in the Lye, and a 
 fmall faline Cruft covers the Surface of it, diminifh 
 the Fire, and with a Wooden-fcraper, or an Iron- 
 ladle, ftirr it circularly, till there remains a dry pul- 
 verulent Salt. When you fee this, you may bake it 
 quite dry, without any further ftirring. If you neg- 
 led this ftirring, and the Diminution of the Fire, a 
 very hard Cruft of Salt will apply itfelf to the Pot, 
 which cannot be feparated but with a Mallet and 
 a Chizzle, and not without a Mixture of feveral Par- 
 ticles of Iron, by which violent Percuffion, th'e Pot 
 which is of melted Iron, and brittle, is frequently 
 fplit. Mix two Parts of this Salt, which will be 
 brown, or fornewhat yellow, with three Parts of pul- 
 verized Flints, or of Sand *, melt them together in a 
 great Fire, in which the Mixture being left for fe- 
 veral Honrs, will turn to a Glafs finer than the fore- 
 going, but lefs durable •, becaufe it contains much 
 more Salt, and the Mixture is not fo perfed. But 
 we cannot determine a conftant Proportion of the 
 Flintsor Sand, and the Salt, becaufe of the Variety 
 of the Stones. For fome Flints are more fufible than 
 feme others : It is the fame with the different Kinds 
 of Sand j which muft be evinced by Experiments. 
 Salt produced in an Earthen-pan, put immediately 
 into the uppermoft Chamber of the Furnace, or in 
 its Pavement, and calcined with only a gentle Fire, 
 left it fhould melt, and freed of a great Quantity of 
 Fat which it ftill contains, will become perfedly 
 white : Or, if you have ufed too ftrong and long-laft- 
 
Assaying Metals. 437 
 
 tng a Fire, it will affume a light bluifh and greenife 
 Dye, with which you will afterwards make a Glafs 
 more beautiful, more tranfparent, and more free 
 from all Colours than the foregoing. But a drong 
 Fire continued long, very much promotes this Beauty 
 and Duration. A more perfect Mixture is obtained, 
 and the fuperfluous Salt diffipated by the fame j be- 
 caufe the fixt Alkali vanifhes in form of a white 
 Smoak : But, it is impoffible to diffipate it intirely : 
 For, part of it is mod intimately joined by the Flints. 
 Thence now it is plain, Why Glades of different De- 
 grees of Beauty and Durablenefs, are produced out of 
 one and the fame Mixture, it proceeding from the 
 different Degrees of the Strength and Duration of 
 the Fire. For Glaffes taken fuddenly out of the 
 Fire, grow obfcure of themfelves in the Air, and 
 fometimes fall afunder into Powder, though the juft 
 Proportion of the Stones and Salt has otherwife 
 been obferved : Which will alfo happen the fooner, 
 if there is more Salt in the Mixture than is requifite. 
 
 PROCESS LXXXI. 
 
 The Preparation of the Salts , for making of cry falling 
 
 Glafs . 
 
 APPARATUS. 
 
 I F you aye willing to have the fined: cryftalllne 
 Glaffes *, you muff purify your Salt feveral. 
 Times by Solution and Cry ft alligation. For the 
 
 coarfer Earth is not diffidently feparated by the firft 
 Solution ; though you ihould drain your Lye through 
 the denfed Filters. Therefore,, you mud diffolve 
 your Salt (Proc. LXXX.) a fecond Time, and pu- 
 rify the Lye by Filtration u , then infpiffate it in the 
 fame Manner in the cleaned Iron-pot, till the Lye 
 be at lad fo thick, as that a thin faline Crud begins 
 
 * Commonly called white-flint Glafs.- 
 
 Ff 3 
 
 to 
 
43 8 The Art of 
 
 to appear at Top, and fmali faline Ma fifes at the 
 Border and the Bottom of the Pot : Then let the 
 Lye grow cold, and reft for a few Hours *, which 
 done, you may take out a great Quantity of the 
 pureft Salt, with an Iron-ladle: Continue to infpiflate, 
 the Refidue of the Lye in the fame Manner, till no 
 more Salt can be feparated in this Manner, and the 
 remaining Lye turns to a muddy Liquor, which 
 ferves to make the coarfer Kinds of Glafs : When 
 the firft Salt is perfectly clean, dry it. If you purify 
 your Salt thus once more, it will be fit for making 
 the fineft Glaftes. Salt extracted out of Afties, and 
 then purified, and calcined, may at once be rendered 
 as pure as it can ever be by any Art, if byexpofing it 
 to a pretty moift Air, you let in run to Wa- 
 ter and cryftaliiz e the Oleum per Deliqumm of it, 
 in the Manner aforefaid. But it is not neceftary 
 to keftow fo much Labour for final 1 Experi- 
 ments, if you are willing to have the fineft crys- 
 talline Glafies, Pot-afh is to be bought very 
 cheap every where, which have already been ren- 
 dered Sufficiently acrid, by being burnt in the Fire, 
 and become moil fit for this Purpofe, when they have 
 been purified from the neutral Salt (which is raoft 
 difficultly diflolved in Water) and from the coarfe 
 Earth wherewith they are full, by a Solution in four 
 Times the Quantity of cold Water, or much better 
 by decanting, and then (trained, and at laft cryftal- 
 jized. There are alfo ibme other Salts which enter 
 into the Conipofition of Glaftes, efpecially Nitre, 
 which, if not pure, muft be purified by Solution, 
 and by pouring gently upon it a few Drops of Gil of 
 Tartar per Deiiquium-> and finally by Cryftallizatiom 
 It is the fame of Borax, which is prepared for Vitri- 
 fications by a gentle burning, whereby a fmali Quan- 
 tity of it Iwells into a prodigious, moft light, and 
 fpungy Mafs, of a very white Colour : However, it 
 is proper to avoid the melting of it. If you negledt 
 th is Preparation, the Mixture to which it is added, 
 will boil over the VeftTels though ever fo large. 
 
 PRO- 
 
Assaying Metals. 43^ 
 
 PROCESS LXXXIL 
 
 The chufing and preparing of Flints for the making of 
 cryftalline Glafs. 
 
 APPARATUS . 
 
 P U LV E R I Z E Sand and Toft Flints in an Iron- 
 Mortar, not rufty : And if it were rufty, you 
 muft Frit grind in it common Sand, which will make 
 it perfectly clean. This mud always be done, when 
 you have a Mind to make cryftalline Glafs clear from 
 all Colour : But, it is not neceifary to do it, when yom 
 are willing afterwards fto tindure your Glades with 
 Iron. For the making of the hardeft Glades, chufe 
 the hardeft Flints, fuch as are the black Flints that 
 ferve for Gun-flints, and fome very hard Quartzs 
 that will refill any File. All thofe which either are 
 white, or grow fuch when calcined in the Fire, are 
 of this Kind. They muft firft be [dean fed of the 
 chalky Cruft commonly adhering to them, then cal- 
 cined in a ftrong Fire, and thrown as yet red-hot 
 into cold Water. Thus they will be foftened, and be- 
 come the whiter, as they were blacker before. Waili 
 od the Allies that may happen to adhere to them, 
 and at laft pulverize them in a Mortar, that they 
 may pafs through a very fine Sieve. When this 
 Powder is moil fubtile, if you have not a Mind to 
 tinge the Glafs to be made of it with the Crocus's 
 of Iron, pour upon it weak Aqua Fortis,. or its 
 Phlegm. Stirr it firft feveral Times, and let it reft 
 for one Night, then decant it, and again wafh it fe- 
 veral T fimes with pure warm Water : You will thus 
 have Sand perfectly fubtile, as good to make the 
 hardeft cryftalline Glaffes, as if you ufed Rock- 
 er y ft a 1 itfelf, according to . - the Obfervations ..of 
 Kunkd, 
 
 ■ F f 
 
 A 
 
 p r a 
 
44 ° Art of 
 
 PROCESS LXXXIII, 
 
 The Compofition of cryftalllne Glafs . 
 
 APPARATUS . 
 
 irrE have already obferved, that it was impof- 
 W fible to affign a conftant Proportion in the 
 compofifig of Glades, on Account of the different 
 Degrees of Fufiblenefs in the Flints ; therefore* we 
 fliall here infert a few Prefcriptions, by way only of 
 Specimen. 
 
 Take of prepared Flints pp. VIII. of the purefl 
 alkaline fixt Salt pp. V. 
 
 Otherwife : Take of prepared Flints pp. III. of 
 the pored alkaline Salt, and of burnt Borace p. I. 
 each. 
 
 Otherwife : Take of prepared Flints pp. III. of 
 the purefl Nitre pp. II, of the pureil alkaline Salt, 
 and of burnt Borax p. ~ each. Of white cryftalline 
 Arfenick p. | T . 
 
 If you add Arfenick, it mu ft firft be intimately mixt 
 with the Salts, efpecialiy Nitre, and this Mixture 
 be joined with the Flints. The Effect of Arfenick 
 here, is, that the Salts diffolve the Flints with greater 
 Efficacy : And it does not entirely evaporate, as has 
 been already obferved, but being in great Part fixt 
 by the Glafs, it fuftains the mod violent Fire. Whe- 
 ther it alfo takes away the greenifh and bluifli Co- 
 lour of Glafles, if fuch a one is produced by, the Im- 
 purity of the Flints or Salts proceeding from a Mix- 
 ture of metallivk Particles, and in what Manner it 
 does it, if this be the Cafe, mud be evinced by a fur- 
 ther Inquiry. 
 
 If you have a Mind to melt thefe Mixtures, chufe 
 a very clean Veffel, fhut clofe at Top, that noFil- 
 thinefs may fall into it, having. a fmall Hole on the 
 Side, that the Mafs within may be examined. But, 
 before the Matter is put into the Veffel, this mud 
 
 drib 
 
• Assaying Metals. 441 
 
 firffc be baked, and glazed with a vitreous Cruft of 
 Litharge. This is done by putting Powder of Li- 
 tharge into the fmall Vedel ftill moift before the bak- 
 ing of it, (baking it in the Veil'd and expofing it to 
 a moderate Fire, after having thrown out wbat is fu- 
 perfluous : Which may be done in the third Chamber 
 of the Furnace. Thus you will prefer ve your Glafs from 
 being tainted by fmall Stones and Duff loofely ad- 
 hering to thefe Vedels, which are then faftened by 
 the Litharge. Every Thing being thus prepared, 
 fill two Thirds of the Vedel with one Compodtion, 
 and before you expofe it to the ftrongeft Fire, roaft 
 it for an Hour in the fourth Chamber, then, put it 
 into the Third or Second, that it may melt thorough- * 
 ly, there it muft fullain a long Fire, till it is fuffici- 
 ently fine, and free from Bubbles : Which requires 
 the Space of feveral Hours. To try this, touch 
 the Surface of the melted Glafs with a new Tobacco- 
 pipe, to which a fmall Portion of Glafs will adhere 
 when you take it out. Take Care, in making this 
 Trial not to move your Glafs : For as often as you 
 do this, it contracts new Bubbles ; which cannot 
 eafily go away in fo tenacious a Mafs. If thefe 
 Glades are left long enough in the ftrongeft Fire, 
 they are harder and more trahfpafent than any. If 
 you will have large Bits of it, it muft be moft (lowly 
 cooled in the fourth Chamber, and the Vedel be 
 broken, or be ground away upon a grinding Stone, 
 in the Place where it is contiguous to the Glafs. 
 
 PROCESS LXXXIV. 
 
 To tinge Glajfes by Metal's , and other Bodies . * 
 
 APPARATUS . 
 
 W E have already given Specimens about thefe 
 Glafies ( Proc . LXXIX.) where we laid down 
 the general Observations to be made on this Matter : 
 We muft now treat of them in a more fpecial Man- 
 ner. The Preparation of the Calx of Metals where- 
 with 
 
44^ The Art of 
 
 with daffies are tinged, require a Variety of Men- 
 ftrua, according to the Variety of the Metals. 
 
 The Calcination of Iron and Copper is performed al- 
 moft by the fame Things, the principal of which are : 
 i. Fire alone, which deftroys the Metals called im- 
 perfect, and even Iron itfelf very eafily without 
 melting, and Copper more eafily ftill : This is done 
 In a fhortTime, if you reduce thofe Metals to thin 
 Plates, or to Filings, and put them in a VefTel co- 
 vered with a Tile, into the third Chamber, where 
 they are left, till they become perfectly triturabie. 
 When triturated, let them be calcined once or twice 
 over for half a Day or more, that all the fmali 
 MafTes which poffiibly have preferved their metallick 
 State, may be burnt. Let the Fire never be fo ftrong, 
 as that the Calx may have any Difpofition to a State 
 of Fufion. 2. Let the pulverized Sulphur mixtwith 
 Iron-filings, be expofed for a few Hours to a ftrong 
 Fire, in a covered Crucible, in the third Chamber. 
 Let the Filings be corroded, that they may become 
 triturabie, and the triturated Calx be roafted for one 
 or two Days in the fourth Chamber. It will thus 
 turn to Colcothar of a dark red Colour, fit to tingp 
 Glaffes. This ACHon of Sulphur is ftill quicker upon 
 Copper than upon Iron : For pretty thick Plates of 
 the former ftratified with pulverized Sulphur in a 
 clofe Crucible, being expofed to a middling Fire in 
 the third. Chamber, are penetrated in a few Hours, 
 and rendered brittle, much thicker, and of a dark 
 Colour , and when pulverized afterwards, put into 
 the fourth Chamber in an open VefTel, they are 
 roafted for a few Hours, that the remaining Sulphur 
 may be diffipated. Thus you will have Calx of Cop- 
 per prepared with Sulphur. 3. Oil of Vitriol diluted 
 with Water, quickly diffolves Iron, and turns to Vi- 
 triol together with it : A fmali Quantity of Copper is 
 more difficultly diffiolved by it (See Proc . LXXIII). 
 The Cryftals of Vitriol made by Evaporation, being 
 dried over a warm Oven, fall into Powder, which 
 imift again be roafted in the fourth Chamber, edul- 
 corated 
 
Assaying Metals. 443 
 
 torated with warm Water, dried, and kept fuch for 
 Ufe. 4. If you fprinkle Filings of Iron or of Cop- 
 per, feveral Times, with .diftiiled Vinegar, and dry 
 them again over a warm Oven ; they are both cor- 
 roded, and the former turns to a triturable dark 
 afh-coloured Powder, and the latter into a green 
 Ruft. 
 
 Brafs is calcined by Fire alone, but being much 
 more conftant when made red-hot, than pure Copper 
 ( Proc . LX VI), you muft calcine thin Plates of it 
 in a ftrongFire, in the third Chamber ; taking Care, 
 meanwhile, that they do. not melt: Becaufe it, on 
 the contrary, melts much more quickly than pure 
 Copper. This Calx muft be roafted again feveral' 
 Times, in a milder but long-lafting Fire. 
 
 Lead is calcined, i. without Addition, if you 
 melt it in a large Iron-ladle : it prefently contracts 
 a fmall Skin at the Surface, which mu ft -be taken off 
 and thrown away with an Iron-fcraper : For Copper, 
 if there is any in the Lead, like wife, contains in it the 
 Filthinefs which adheres to the Lead : Another fuch 
 Pellicle will Toon be produced : Which muft betaken 
 off, and kept : Continue thus to colled the Pellicles 
 produced in this Manner, till you have gathered a 
 fufficient Quantity : Let them be extended wide in 
 
 the fourth Chamber, and roafted in a gentle Fire, 
 ftirring them now and then with a fmall Hook, till 
 they become perfectly triturable. 2. Lead is, by 
 the Vapour of Vinegar, corroded to a white Calx> 
 which being pulverized under the Name of Cerufe, is 
 fold very Cheap in all PerfumerThops, but proves 
 feldom genuine, and is often mixt with Chalk, Par- 
 get, and other Things: Whence the Glafs- makers 
 who ufe fuch Cerufe to make Glafsof Lead, lofe both 
 their Labour and Materials. If you are willing to 
 prepare the beft Cerufe of this Kind with Vinegar, 
 diftil Vinegar of Wine, out of a Cucurbite through 
 an A limbeck full of thin Plates of Lead, and fo dif- 
 pofed, that the fmall Drops which apply themfelves 
 to them, may neither fall into the Cucurbite, nor 
 
 run 
 
444 The Art of 
 
 run down again, but be all collected in the Channel 
 of the A limbeck, and thence run down through its 
 Neck into the Recipient applied to it. Let the Dif- 
 tillation be performed in a gentle Fire for a few Days : 
 The Vinegar faturated with Lead and dulcified, will 
 be collected in the Recipient. Being infpiflated ac- 
 cording to Art it forms a Heap of Crydals called 
 Sacckarum Saturni , Sugar of Lead : Thefe being 
 calcined in a gentle Fire, fall into a white Powder, 
 which is very ufeful for Glaffes. Calx of Lead made 
 red in an open reverbatory Fire, and called red- Lead, 
 or the Litharge commonly fold, may be fubftituted 
 for the foregoing. But, as the latter in particular, 
 commonly leaves the Regulus of Lead at the Bottom 
 of the Veifel •, it mud be melted, before it is added 
 to the Mixture for the making of Glafs, and then 
 poured into the melting Cone, and the precipitated 
 Regulus of Lead mud be fe para ted, or the Mixture 
 prepared for Glafs be poured into Water, if it has 
 been only a Quarter of an Hour in Fufion ; and the 
 Lead be thus feparated from the pulverized Glafs. 
 Therefore, it is alfo proper, to mix with thofe Glades 
 to which Litharge or any other Calx of Lead is 
 added, a Portion of Nitre, which dedroys the Lead, 
 and vitrifies it foon. For Litharge confids of very 
 fubtil Scales, and of fmall Maffes of Lead outwardly 
 vitrified. 
 
 Tin is dill more eafily calcined than Lead by the 
 fird Method, and with a dronger Fire ; otherwife, 
 it is fooner prepared by the following Method in par- 
 ticular. When your Tin has been melted in a Cru- 
 cible by a gentle Fire, add to it half as much Lead : 
 This done, increafe the Fire by degrees. So foon as it 
 begins to grow red, the Tin is rejected out of the Mix- 
 ture, in form of a Calx of different Colours. Conti- 
 nue the fame Degree of Fire, till this Calx fmoaksno 
 longer, but fparkles : Then take it away with an iron- 
 Ladle, The like will be produced again feveral 
 Times. When it is collected, burn it quite in the 
 
 fourth 
 
Assaying Metals. 44 j 
 fourth Chamber of the Furnace : But, it will not be 
 altogether free from Lead. 
 
 The Calx's of Gold and Silver are prepared by. Solu- 
 tion in their proper acid Menjlrua \ irom which they 
 are feparated by extraction of the Spirits, or by pre- 
 cipitation with other Metals of Salts. Mean while, 
 be aware of fulminating Gold. Calx of Gold pre- 
 cipitated out of Aqua Regis by Tin, is called Calx 
 CaJJii . Mercury itfelf being corroded by Aqua Fortis 
 and Oil of Vitriol, is rendered more fixt, and when 
 infpiffated, it is fometimes added by Artificers, to 
 Compofitions of Calxs for tinging of GlafTes. Semi- 
 metals are calcined by themfelves, which is eafily 
 done chiefly with Regulus of Antimony, or difTolved - 
 by Acids, and precipitated feveral Ways: Nay, when 
 prepared with Nitre by Detonation, they may enter 
 into the Compofition of GlafTes. 
 
 Having prepared thefe Calxs, you will be able to 
 tinge GlafTes in a Multitude of Manners ; efpecially 
 if they are at the fame Time accompanied with feme 
 other Bodies. 
 
 Obferve in general, i. You mnft put your Mix- 
 ture either in a new VefTel, or at leaft in a Veffel in 
 which Glafs has been in the fame Manner coloured, 
 worked, melted, and taken out. 2. The thicker 
 Bits of Glafs require lefs of thetingent Calxs, and the 
 thinner Ones require more. 3. LJfe a Fire of fuch a 
 Strength, as that a warm Tobacco-pipe being intro- 
 duced into it, there may indeed adhere to it a pretty 
 thick Cruft, but not a large Knob of Glafs : Nor 
 muft the Mixture be put at once into the VefTels ; 
 but when part of it is thoroughly melted, the reft 
 may be put gradually into the Veffel with a fmall 
 iron-Ladle : For fome Mixtures are very apt to foam % 
 Of which we fhall foon give Examples. 
 
 1. The green Colour is made of two Ounces of the 
 Mixture for cryftalline Glafs, to which you are to 
 mix about ten Grains of any Copper whatfoever, or 
 of Brafs : If you add to the Calx of Copper a few 
 Grains of Crocus of Iron, you will have the fineft 
 
 Glafs. 
 
44^ The Art of 
 
 Glafsof a yellowifh green-Colour. Thence, you will 
 be able, by changing the Proportion of thefe two 
 Calxs, to vary this Colour in an infinite Number of 
 Manners. 
 
 2. GlafTes are tinged with* blue by Smalt, by ZafFre, 
 or by Cobalt itfelf, previoufly roafled, by mixing 
 three or four Grains of it, with two Ounces of Glafs. 
 
 3. Your Glafs is brown or black, if you mix with 
 it a great Quantity of Cobalt or of ZafFre, for In- 
 llance, one Drachrn. The Croci of Iron, and all its 
 Ores, have the fame EfTedl, if you melt them toge- 
 ther in good Quantity with GlafTes. NevertHelefs, 
 there is a Variety in this brown Colour: Efpecially, 
 if they are finely divided : For, then, the blue Colour 
 of the Smalt, and the rufly Colour of the Iron, may 
 again be diftinguifhed. 
 
 4. You give GlafTes a golden Colour, by adding to 
 the Dofe of the above-mentioned Mixture, twelve 
 Grains of roafled Manganefe, a Drachm and a half oi 
 Tartar, and fix Grains of Charcoal-dufl, or of Soot. 
 
 5. White, milk-coloured, opaque GlafTes are pre- 
 pared with Tin, by adding to your Mixture for Glafs 
 one fifth Part of Calx of Tin, to which the fame 
 Quantity of Calx of Lead muft be added for a more 
 eafy Fufion, with one Grain of roafled Manganefe. 
 
 6. If you melt with Flints alone, the double or 
 treble Quantity of Calx of Lead, you will make a 
 mod beautiful Glafs, of a yellow Colour with a flight 
 greeni fh Caff, more fufible than the foregoing, that 
 will foon reje£l its Bubbles, and calls up all the fmail 
 Stones : You may alfo add Calx of Lead to the fore- 
 going Mixtures. Such Glafs will have the foregoing 
 Colours in a very elegant Manner. Calx of Tin 
 added in an equal, or a double Quantity, renders 
 them of a milk Colour, and they may be moll finely 
 tinged, if you add moreover Calx's of other Metals^ 
 Such opaque and moil fufible Glades, made of Calx 
 of Lead, of the Mixture for cryflalline GlafTes, and 
 of Calx of Tin moll finely mixt together, and tinged 
 together by Calx's of other Metals, are called Encaufia 
 
 (Enamells.) 
 
Assaying Metals. 447 
 
 (Enamells.) Amaufa , or Smalts. You may read fe- 
 deral Things concerning thefe Matters, in the above- 
 men tioned Authors. 
 
 PROCESS LXXXY. 
 
 Of hydroflatical and ftatical Examinations of Metals and 
 Minerals . 
 
 APPARATUS. 
 
 T HIS, as well as the Foregoing Precedes, con- 
 cerning GlaiTes, ftridly fpeaking, do not, in- . 
 deed, belong to the Art of Affaying. This Exami- 
 nation is performed by feveral Apparatus* s, which 
 you will find defer i bed in the hydrodatical Writers, 
 among which you may chufe that, which, from Ufe and 
 Comparifon, you will judge to be mod convenient 
 Make the following Obfervations in general. 
 
 1. Have at hand Water diddled in a glafs-Veffel 
 on a gentle Fire, that may fudain a Solution of Silver 
 or of Lead, without being turbid : For, fountain, 
 river, and rain-Waters, are too different. 
 
 2. Let the warmth of the Water and of the Body 
 to be weighed, be fixt : For, it may occafion a very 
 great Difference : Which appears prefently, if you 
 weigh in the fame Water made warm, the fame Body 
 that has been already weighed. For, it will appear 
 fpecifically heavier : Therefore, you mud be provided 
 with a Thermometer. But, you mud chufe a Degree 
 not exceeding much the greated Summer-heat, for 
 Indance 90, according to Fahrenheit* s Thermometer. 
 You mud warm to the fame Degree not only the 
 Water, but alfo the Body to be weighed ; which 
 may be very well done in a Balneo Maries. 
 
 * Particularly the Medicina Hydrojtaiica ; or Hydroftaticks ap- 
 plied to the Materia Medica , to which is fubjoined a previous by- 
 droftatical Way of ehimating Ores, by the Honourable Robert 
 Eiq; F. K. S. Land. 1 690, in 8 V0 . 
 
 3 . You 
 
448 The Art of 
 
 3. You muft fir ft weigh the Bodies in the Air, fit 
 the mod exact Manner. 
 
 4. Porous, finking Bodies, which abforbe Water* 
 muft previoufly be moiftened in a fhallow Veffel, full 
 of very clean Water, to expel, as much, as poftible, 
 the Air out of the Interftices. For, it renders Bodies 
 fpecifically lighter *, but, the Water that fills the In- 
 terftices of the Body to be weighed, is indifferent 
 with regard to the Water that furrounds the Body* 
 But, when Bodies are moiftened, they muft not be 
 immerfed in the fame Manner, but they muft be con- 
 tiguous at Top to the Air. For, by that Means, the 
 Air inherent in the Interftices of this Body, will re- 
 tire quicker, and more compleatly. 
 
 5. And as forne Bodies do in a Manner rejecft Water, 
 and fmall aerian Bubbles, that render Bodies lighter, 
 are produced at the Surface of almoft all folid Bodies, 
 while they are immerfed in .Water, efpecially warm 
 Water ; they muft be moiftened as foon as poftibly 
 you can. 
 
 6. Therefore, you muft as much aspoffible, give 
 the Bodies to be weighed a fmooth and neat Outfide i 
 For Inftance, Metals reduced to a globular Form, 
 may very eafily be weighed by this Method. 
 
 7. Bodies full of Ffollows, and concealing Air 
 within themfelves, muft be reduced to a Powder, 
 which muft be foaked in Water for a good while, 
 and now and then ftirred before it is weighed. 
 
 8. Salts muft be weighed either in Alcohol (and 
 they muft all of them have the above-mentioned De- 
 gree of Heat) or, if they are diffolved in Alcohol, 
 or if you have none at Hand : You muft make a 
 Brine thoroughly faturated with the faid Salts, with 
 an undetermined Degree of Warmth, and compare 
 the fpecifick Weight of it, by Means of a folid Body, 
 for Inftance of Glafs, immerfed ir\ it, and afterwards 
 immerfed in Water : Which Weight muft be com- 
 pared with that of the Water, 
 
 The 
 
Assaying Metals. 449 
 
 The other Encheirefes depend upon the Quality 
 of the Inftruments imployed, and upon your own 
 Practice. 
 
 9. Metals are more exaftly weighed flatically, if 
 you weigh firft a certain Mafs of the fame Metai 
 rendered perfectly pure : Which is very well done, 
 by drawing it into a (lender cylindrical Wire, and by 
 cutting out of it a Cylinder of a certain Length, which 
 muft be weighed in the docimaftical Balance. Thus* 
 you may compare all malleable Metals drawn to Wire. 
 You will be able to conclude from an Hydroftatica! 
 and a Statical Examination* the Purity chiefly of 
 Gold, as being the heavieft* and of Tin, as being 
 the lighted of all Metals. 
 
[ 45 ° ] 
 
 A N 
 
 APPENDIX. 
 
 Containing a Lift of the chief Authors in 
 , Englijh , who have treated of Minerals 
 and Metals, By the Author of the 
 -Notes. 
 
 F O R the Benefit of fuch Perfons who are curi- 
 ous in Mineral Affairs, but underftand only 
 the Englijh Language, it was thought pro- 
 per to fubjoin the following Lift of Authors who 
 have treated on thefe Subjects. 
 
 Gabriel Platt es, a Difcoveryof fubterranean Trea- 
 fure, viz. Of all Manner of Mines and Minerals 
 from Gold to the Coal, with plain Directions and 
 Rules for the finding of them, in all Kingdoms and 
 Countries, (Ac. 
 
 This fmall but curious Piece hath often been 
 printed at London in 4*°, and lately in 8 V0 , at the End 
 of a T ranflation of Alonfo Barba . 
 
 Albaro Alonfo Barba , Art of Metals, tranfiated 
 [from the Spanijh ] by Edward Earl of Sandwich , 
 Lond . 1674, in Two Parts, in 8 vo , and lately re- 
 printed. 
 
 John Webfter^ Metallographia : Or an Hiftory of 
 Metals, (Ac. Lond. 1671. 4 10 . 
 
 Robert Boyle , Efq; General Heads for the natural 
 Hiftory of a Country, Lond. 1692, 12 0 . In this 
 Book the Author lays down various judicious Rules 
 for the Difcovery of Ores and Minerals. Many curi- 
 ous Things relating to Metals and Minerals, are to 
 be found difperfed in his philofophical Works. 
 
 Sir 
 
A L 1ST of Authors. 4J1 
 
 Sir John Pettus , Fleta Minor ; the Laws of Art 
 and Nature in knowing, judging, aflaying, fining, 
 refining, and inlarging the Bodies of confined Metals , 
 in Two Parts. The firft contains A flays of Lazarus 
 Ercker, chief Prover (or Efiay-mafter General of the 
 Empire of Germany ) in Five Books, originally writ- 
 ten by him in the Leutonick Language, and now 
 tranfiated into. Englijh. The Second contains Effays 
 on metallick Words, as a Dictionary to many 
 pleafing Difcourfes, Lond. 1686, Folio. 
 
 John Houghton , a Collection for the Improvement 
 of Hufbandry and Trade, revifed and published by 
 Richard Bradley , in 3 Vols. Lond. 1727 in S™, with 
 a 4 th Volume, being a Collection of Letters on the 
 fame Subjects, ibid. 1728, 8 V “. 
 
 In Vol. I. You have fome Obfervations 
 
 On Nitre N° XI. XII. 
 
 Of Sulphur N° XIX. L. Vol. II. N° CCXXII. 
 CCXXXVII. 
 
 In Vol. II. 
 
 Of Arfenick N° CCXLIII. 
 
 Of Coal N° CCXXXIX. CCXLI. 
 
 Of Copper N° CCLV. CCI.VI. CCLVIII. 
 CCLX. CCLXI. Vol.' III. N° CCCCLXIV. 
 
 Of Glafs N" CXCV. CXCVI. CXCI. CXCVIII. 
 CXCIX. CLXXIX. 
 
 Of Gun-powder N°CCXXII. CCXXIII.CCXXIV, 
 CCXXVII. to CCXXX. 
 
 Oflron N“ CCLXVIII. to CCLXXVIII. 
 
 Of Lapis Calaminaris N° CCII. 
 
 Of Lead N° CCLXII. CCLXVI. 
 
 Of Cerufs CCLXV. 
 
 Of Mercury N° CCLXXX. CCLXXXL 
 CCLXXXI1I. to CCLXXXVIIL 
 
 Of Metal N° CCXLIII. 
 
 Of Salt-petre N° CCXXI. to CCXXX. 
 
 Of Sal Gem or Sea Salt N° CCX. to CCXV. 
 CCXVII. to CCXXI. 
 
 Of Silver N° CCX L VII. CCXLVIII. CCLXI. 
 
 CCLXXXVII. 
 
 G g 2 
 
 Of 
 
A LIST of Authors. 
 
 Of Vitriol N° CCXXIII. CCXXXIV. CCXXXV. 
 CCXXVI. CCXXXVI 1 I. 
 
 Of AllomN® CCXXXV III. 
 
 In Vol. III. 
 
 Of Soap. N° CCCCV. 
 
 In Vol. IV. 
 
 Of Minerals, &c. p. 290 — 1— 2. 
 
 Of Salt Spanijh , trench , Portugal , Scotch , and 
 Newcaftle , p. 454, &V, 
 
 Ray , aCoiledtion of EngHJh Words not gene- 
 rally in ufe. to this Book is fubjoined an Account of 
 the preparing and refining fuch Metals and Minerals 
 as are gotten in England , Lond . 1737, in 8 y °.viz. the 
 fining Silver in Cardiganjloire. The Preparing and 
 Smelting Tin in Cornwall . The Manner of the Iron- 
 work at the Furnace and at the Forge. The Wire- 
 Work at Einiern in Monmouthjhire . Modus faciendi 
 Vitriolum codlile in Anglia : From Wormius in his Mu- 
 [cum. The making of Minium or Red-lead. The 
 Allum-work at Whitby in Torkfhire . The making Salt 
 at Namptwych in Chejhire . The Manner of making 
 Salt of Sea-fand in Lancajhire . 
 
 John Lawrence , a new Syftem of Agriculture, 
 Lond. 1726. Folio. In this Work (the greatefl Part 
 of which feems to be borrowed from Mortimer's Art 
 of Hufbandry) he hath inferted what he hath col- 
 
 ieded 
 
 Of Mines, Minerals, and Quarries p. 172 
 Of Copper 17-5 
 
 Of Tin 176 
 
 Of Iron and Iron-works 177 
 
 Of Allum 180 
 
 Of Lead 18 1 
 
 Of Salt, Sulphur, &tV. in the Earth 183 
 
 Of Salt made and Salt-works 186 
 
 Of Quarries, &c. 191 
 
 Of Coals and Cowke 194 
 
 But he feems to write like one who never black’d 
 his Fingers or fing’d his Beard in metallick Opera- 
 tions. 
 
 Robert 
 
A LIST of Authors. 455 
 
 Robert Plot L L. D. natural Hiftory of Stafford* 
 {hire, Oxford 1 686. in Folio, of Coal-pits, Chap. III. 
 
 i§ 3 3 l > 34 > 37 > 6o > 62 - 
 
 Edward Brown , M. D. a brief Account of fome 
 1 Travels in divers Parts of Europe , &c. with fome 
 Obfervations on the Gold, Silver, Copper, Quickfilver 
 Mines , &c. of Hungaria, &c. Lond. 16S5, Folio. 
 
 William Waller, an Effay on the Value of the 
 Mines late of Sir Carbery Price, Lond . 1698, 8 Vo . 
 
 The Philofophical T ranfaWions of the Royal Society, 
 
 Of Mines N° 19, 28, 39, 401, 403. 
 
 Damps in Mines, N°. 5, 442, 444. 
 
 Allum, N° 142, 21. 
 
 Nitre, N° 167, 160, 93, 6 . 
 
 Salt, N° 53, 103, 142, 145, 66 . 
 
 Vitriol, N° 3, 103—4, 256. 
 
 Copperas, N° 142. 
 
 Silver, N° 58, 41. 
 
 Lead, N° 28, 39, 407. 
 
 Tin, N° 69, 138. 
 
 Copper, N° 200. OfBrafs, ibid. 2 6p. 
 
 Iron, N° 137, 277, 199. 
 
 Steel, N° 203. 
 
 Mercury 34. 
 
 Cobalt 293, 396. 
 
 Black-lead, N° 239. 
 
 Coal, N° 250, 336. 
 
 The Art of Refining, N° 142. 
 
 Of Refining with Antimony, 138. 
 
 For the Sake of fuch as underftand Latifi, we mud: 
 not pafs by that magnificent and laborious Work of 
 Emanuel Swedenborgius , intituled, Principia Rerum 
 Naturalium, five novorum Lentaminum Phenomena 
 Mundi Elementarii pbilofophice explicandi. Drejdce & 
 Lip fee 1734, in 3 tom * in Folio; in the 2 d and 3 d 
 tome of which he hath given the belt: Accounts, not 
 only of the Methods and neweft Improvements In 
 metailick Works in all Places beyond the Seas, but 
 particularly of thofe in England, and our Colonies m 
 
 G g 3 America \ 
 
 ( 
 
4J4 d LIST of Authors. 
 
 America ; with Draughts of the Furnaces and In- 
 ftruments employed. It is to be wifhed we had Ex- 
 tracts of this Work in Englijh . So induftrious are 
 the Swedes in improving themfeives in the Art of 
 Metallurgy, that they fend young Gentlemen yearly 
 to travel, not only all over England , but all over 
 Europe , to learn every Thing new in regard of 
 Mines ; while we in England fit (till at Home, and 
 feldom go beyond a County or two y though, if more 
 diligent Search was to be made by Ferfons of Skill, 
 there is great Reafon to believe that Nature hath 
 enriched thefe our files with as great fubterranean 
 Treafures, even theVirgin Silver of Potofi not except- 
 ed, as any other Spot of the fame Extent. 
 
 Dr. Woodward hath given fome brief Directions for 
 making Obfervations and Collections, and for com- 
 pofing a travelling Regifler of all Sorts of Foflils, 
 wherein are many good Rules for difcovering Mine- 
 rals and Ores. It is printed at p. 99, &c, of the Ap- 
 pendix to his FoJJilsof all Kinds digefted into a Method , 
 Lend. 1728, 8 V0 . 
 
 As for Catalogues of Minerals and Ores already 
 known in England , fee 
 
 Chriftopher Merrett , Pin ax Rerum Naturalium Bri- 
 tannic arum. continens Vepetabilia. Animalia E? FoJJilia , 
 Lond. 1667 , 8 vo . 
 
 Nehemiah Grew , M. D. Mufaeum Regalis Societatis „ 
 or a Catalogue and Defcrjption of the natural and 
 artificial Rarities belonging to the Royal Society, 
 Lond. 1681, Folio. But the moft compleat is that 
 elaborate Work of Dr. Woodward's . 
 
 An Attempt towards a natural Hiftory of the Fof- 
 fils of England , Lond. 1729, in 2 tomes 8 Vo . 
 
 Concerning the EngliJJo Laws relating to Mines and 
 Metals you have a Propofal for Laws by Fho. 
 Houghton , in his Golden Freafury , or the Compleat 
 Miner , being Royal Infli tutions or Propofals for 
 Articles to eftablifh and confirm Laws , Liberties , and 
 Cuftoms of Silver and Gold Mines, to all the King’s 
 
 SubjeCbs 
 
A LIST of Authors. 4^5 
 
 Subjeds, in fach Parts of Africa and America , which 
 are now or fhall be annexed to, and dependent on the 
 Crown o {England, &c, Lond. 1699, i2 m °. 
 
 The fame Author hath given us another fmali 
 Treatife, entituled, Rara Avis in Terris, or the com- 
 pleat Miner, in two Books : The firft containing the 
 Liberties, Laws, and Cufcoms of the Lead Mines 
 within the Wapentake of JVirkfworth in Derbyfloire . 
 The fecond teacheth, the Art of dialling and levelling 
 Grooves, a Thing greatly defired by all Miners ; 
 being a Subjed never written on before by any, with 
 an Explanation of the Miners Terms of Art ufed in 
 this Book, 1 681, in i2 m °. 
 
 The feveral Laws now in force are fcattered up 
 and down in the Statutes at large : But that which 
 gives the moft Encouragement to Miners and Me- 
 tallurgifts, is the famous Statute procured by the 
 Intereft of the great Mr. Boyle, Anno 1 Gul. and 
 Mar. Chap. 30. intituled, An Ad to repeal the 
 Statute made in the fifth Year of King Henry IV. 
 again fc multiplying Gold and Silver. 
 
 Wherein it is enaded, that all Gold and Silver that 
 fhall be extraded by the Art of Melting and Refin- 
 ing of Metals, and otherwife improving of them and 
 their Ores, be from henceforth imployed for no other 
 Ufe but the Increafe of Monies ; that it be carried 
 to the Tower of London , where the Owner fhall re- 
 ceive the full Value. And that for the future no 
 Mine of Copper, Tin, Iron, or Lead, fhall be 
 hereafter adjudged a Royal Mine, though Gold or 
 Silver may be extracted out of the fame. 
 
 Anno 5 Gul . and Mar. Chap. 6. 
 
 An Ad to prevent 'Difputes and Controv erfies con- 
 cerning Royal Mines . 
 
 In this Ad it is enaded, that any Perfon, &c. that 
 now is or fhall be Owner, lAc. of any Mine or Mines 
 in England, wherein is Copper, Tin, Iron, or Lead, 
 may keep and work fuch Mine, &c. netwithftanding 
 it fhall be pretended or claimed to be a Royal Mine ; 
 
 G g 4 provided 
 
45^ ^ LIST of Authors. 
 
 provided always that thejr Majefties, and all 
 claiming under them, may have the Ore of any Mine 
 (except the Tm-ore of Devon and Cornwall ) paying 
 to the Proprietors, £sV. of the Mine, within 30 Days 
 after the Ore is raifed, for all Ore wafhed, made 
 dean, and merchantable, wherein is 
 Copper 1 6 1 . per Tun. 
 
 Tin 2 /. per Tun. 
 
 Iron 2 /. per Tun. 
 
 Eead 9 /. per Tun. 
 
 And in Default of Payment of filch Prices, the 
 Owners of the Mines may fell the faid Ores to their 
 
 own Ui€S. 
 
 Since thefe Encouragements we fee great Quanti- 
 ties of Silver Coin made of Silver extradled out of 
 Lead in England and Wales : Thefe Coins have in the 
 Quarters between the King’s Arms upon their Re- 
 veries, Rofes or Feathers, or both alternately. 
 
 The Laws relating to wrought Plate were for- 
 merly collected into a fmall Volume, which it is 
 pity we have not a new Edition of, with the Addi- 
 tion of all the new Statutes ; the Title was, 
 
 A Lou ch ft one for Gold and Silver Wares , or a Ma- 
 nual for Gold fin iths. By W. B . of London , Gold- 
 fmith. Lond. 1677, 8 V °. 
 
 E X P L A- 
 
[ 457 ] 
 
 EXPLANATION 
 
 OF THE 
 
 FIGURES. 
 
 PLATE I. 
 
 F IG. I. A Peftle, to ftamp the Coppeh with. 
 It is called in German 
 
 a. b. Its wooden Handle, which is /opened 
 into the hollow Bra/s cylinder in the lower Part of it. 
 
 c. d. e. f. g. j The hrafs Part of the Peftle which is 
 prejfed down into the Ring Fig. II. filled with Afhes, to 
 make the Cavity and Upper-border of the Coppel (§ 177.) 
 
 e. Is a fph eric al Segment very well polifhed , which 
 cor ref ponds to the Cavity of the Coppel. 
 
 d. f. Is a projecting Border , which forms that of 
 the Coppel. 
 
 c. g. Is the hollow hrafs Cylinder , into which the 
 Handle a. b. is received. 
 
 Fig. II. A brafs-Ring, called in German 
 drawn according to the perpendicular Section , reprefent- 
 ing a truncated Cone , open at Top and at Bottom , which 
 is filled with the Aftoes to be pr effect down with the Peftle 
 Fig. I. The pricked Lines mark how deep the Peftle mufl 
 be thruft , before its Border d. f. reaches the Sides of the 
 Ming. 
 
 It is proper to have ready at Hand three or four fuch 
 Mings of different Sizes , with Peftles correfponding to 
 them. The leaft of them muft form a Coppel , of \ of an 
 Inch *, the largeft of them muft form a Coppel two Inches , 
 from out to out . 
 
 Fig, 
 
458 Explanation of the Figures. 
 
 Fig. III. A Coppel cut perpendicularly. 
 
 a. b. c. The Cavity that contains the Metal. 
 
 d. The Bottom of it (§ 176.) 
 
 Fig. IV. A Box made of Plate-brafs , and open at 
 Top *, being \ of an Inch in Diameter , and three Inches 
 high. 
 
 a. b. Its Cover , having at Top a fine clofe Hair - 
 fieve. 
 
 c. Through the Pores of which the Afloes wherewith 
 the Box is filled may be fhaken out (§ 178.) 
 
 Fig. V. A wooden-Peft le like that Fig. I. to make 
 Tefts. 
 
 a. b. c. The convex Part which forms the Cavity of the 
 Tefts. 
 
 Fig.VL An hollow wooden - Ring cut perpendicularly, 
 which is filled with a Mafs of Clay , and incomp aftfed 
 with a. a. b. b. an iron- Ring, left it Jhould break afunder 
 (§ while the Matter is beaten into it. 
 
 Fig. VII. A fcorificatory Teft cut perpendicularly. 
 The Diameter of it muft be about two Inches. Its bottom 
 a. b. muft be narrower , that it may fooner grow warm 
 in the Fire (§ 186.) 
 
 c. d. e. Its Cavity. 
 
 Fig. VIII. A large afli-Veflel, or Coppel, income 
 p affed with an iron- Ring h. i. k. 1. 
 
 a. b. c. The Cavity of it, like a fpherical Segment , 
 fur rounded with a Border d. e. f. g. 
 
 h. i. k. 1 . An iron- Ring, to retain the Afhes (§ 185.) 
 
 Fig. IX. A Shaver, curved according to the faid 
 fpherical Segment, to cut the Afhes prejfed clofe, in order 
 to make the Cavity of the afh-Veffel (Fig. VIII.) 
 
 a. Its Edge . 
 
 b. Its Back. 
 
 c. d. Two Handles to hold it (§ 184. N° 3.) 
 
 Fig. X. A Hand rowling about a fmooth wooden - 
 Ball, therewith to prefs clofe to the Cavity the dry bone - 
 Afhes fprinkled upon it, that it may be made very fmooth 
 (§ 184. N° 3. & 4.) 
 
 Fig. 
 
 V 
 
Explanation of the Figures. 459 
 
 Fig. XL A large afh-Veilel, framed in an earthen - 
 Diflj a. b. c. d. 
 
 e. f. g. Its Border (§ 184.) 
 
 h. Its fpberical Cavity . 
 
 Fig. X II. A toothed, wooden-Y eftle, to prefs clofe the 
 AJhes put into the earth emDiJh (§184. N-° 2 .) 
 
 Fig.- XIII. A final! femi-cylindrical Mould, to form 
 the docimaftical Muffle. 
 
 a. b. c. d. Its convex Back. 
 
 c. g. a. Its hinder-Plane. 
 
 b. d. e. f. Its fore- Plane. 
 
 h. A Hole in the for e-P 'lane , wherein toff aft en the 
 Screw , p. with which the Mould may be pulled out , 
 when the back and the hinder-plane of it are covered 
 with Clay clofely applied to them (§ 199. N° 200.) 
 
 Fig. XIV. A concave Mould, which being applied 
 to the foregoing (Fig. XIII.) the Muffles are made 
 fooner , and more folid. 
 
 ]. A femi-cylindrical Cavity , which is larger than the 
 foregoing convex Mould (Fig. XIII.) to make the Thick - 
 nefs of the Muffle. The hollow Surface of it is done 
 over with the clayey Matter. 
 
 m. The hinder -Board, where the Muffle muft be clofe. 
 
 r. The fore- Board, which ferves forpreffing the Matter 
 clofe. 
 
 i. i. k. k. Two Screws, the f crew-holes of which are in 
 4 he hinder-Board , to make the hinder and the fore- Board 
 
 draw towards each other. 
 
 o. n. The upper- Board which makes the Bottom or 
 Floor of the Muffle. It is fur nifhed with another firnall 
 
 tranfverfal Board , q. that it may refift the Effort of 
 the Screws g. g. (§ 200.) 
 
 s. The Nuts of the Screws g. g. 
 
 PLATE II. 
 
 Fig. I. A docimaftical Muffle, with a ft xt Bottom. 
 It is feen on the fore-part, and fide-ways (§ 194.) 
 
 Fig. II. A docimaftical Muffle Jet upon a moveable 
 Bottom , and to be feen on the hinder-part , and laterally. 
 
 Fig, 
 
460 Explanation of the Figures. 
 
 Fig. If I. A jphero'idal Muffle, which is put upon 
 the large T eft fur rounded with an Iron-Ring (Plat. I. 
 Fig. VIII.) (§201.) 
 
 Fjg. IV. A wooden- Mould, upon which the Mafs 
 if Clay defigned to make the fpheroidal Muffle (Fig. III.) 
 is put (§ 201.) 
 
 Fig. V. A melting- Crucible with a broad fixt Foot. 
 It ferves chiefly to examine the Copper and Lead- ores 
 (§ 202 .) 
 
 Fig. VI. Another melting- Crucible triangular at 
 Top, fit to pour out the melted Mafs (§ 202.) 
 
 Fig. VII. A hollow wooden-Mou\d 9 cut perpendi- 
 cularly , fur rounded with an iron- Ring, divided into two 
 Farts in the Middle , that it may be disjoined by taking 
 off the iron- Ring. The fimall melting-Crucibles (Fig. V.) 
 are made therein (§203.) 
 
 Fig. VII I. The Peftle belonging to the Mould (Fig. 
 VII.) It ferves to make the Cavity of the f mall melting 
 Crucibles . Fig. V. (§ 203.) 
 
 Fig. IX. A hollow Mould, fit to make the triangular 
 melting Crucibles Fig. VI. Cut likewife perpendicu- 
 larly, and to be / unrounded with an iron-Ring . There 
 is a Re file belonging to it, like that of Fig. VIII. The 
 inferior Fart of which, however , which forms the Ca- 
 vity of the Crucible , mufi be of a triangular pyramidal 
 Figure (§ 203.) 
 
 Fig. X.. A. B. mark the Covers, to clofe the large 
 and fimall melting Crucibles (§ 208.) 
 
 Fig. XI. A fimall feparatory Cucurbite (§ 209.) with 
 a paper-Stopple . 
 
 Fig. XII. The Trevet whereon the fimall Cucurbite 
 (Fig. XI.) refs (§210.) 
 
 Fig. XIII. The edulcoratory G?/>/w-Skellet, towafh 
 the fiver -Calx that has been precipitated out of Aqua 
 Fort is by Copper (§211 ) 
 
 Fig. XIV. A fimall golden- Difh to heat the Gold in 
 red-hot , from which Silver has been eroded by Aqua 
 Fortis (§ 2 1,2.) 
 
 Fig. XV. An ’ iron-T revet, whereon the fimall Difh 
 „{Fi£. XIV.) is fiupported (§ 213.) 
 
 Fig. 
 
Explanation of the Figures. 4 61 
 
 Fig. XVI. The wooden or earthen wafhinG;-TrouaIi 
 or T ray , to wajh off the lighter and unprofitable Parti- 
 cles adhering to the Ores. It refembles a J, mall Boat , is 
 about one Foot long , and a few Inches broad and deep. 
 The hinder and higher Part of it ferves as a II anils 
 to it (§ 2 14.) 
 
 Fig, XVII. The granulator y wooden Box (§ 215.) 
 
 Fig. XVIII. The granulatory cylindrical Machine, 
 put upon a Vejfiei full of Water ^ fo that its under-fids 
 may be immerfed in the Water . The Metal to be gra- 
 
 nulated is poured upon it while it turns (§ 217.) 
 
 Fig. XIX. The melting Cone, which is of Copper 
 or Iron (§ 220.) 
 
 Fig. XX. A fet of Moulds to make Ingots (§ 223]) 
 of Metals . 
 
 Fig. XXL A Mould with fpherical Segments , fir 
 the metallick Regulus’s which are to be put into the Cop- 
 pel (§ 224.) 
 
 PLATE III 
 
 Fig. I. The Doeimaftical or Efiay-Furnace. 
 
 a a. b b. c c. The Body of the docmaftical Furnace 
 (§ 2 3 2 0 
 
 d. Its Aperture at Top. (Ibid. N° 1.) 
 
 e. The Door cf the Afh-hole . 
 
 k. k. Sliders to font the Door. 
 
 f. The upper- Door that is contiguous to the Muffle 9 
 which is feen within , in its proper Situation , together with 
 two Coppels in it. 
 
 J. 1 . Sliders to Jhut the upper -Door. 
 
 m. An oblong Hole in one of the Sliders. 
 
 n. Another femi-circular Hole in the other Slider 9 
 through which one may look into the Muffle when the 
 Door is Jhut . 
 
 g. g. h. h. i. i. Iron-Plates , rivet ted to the Furnace * 
 and making between them and the Sides of the Furnace , 
 Grooves in which the Sliders of the Doors may move. 
 
 0.0. Two Holes , to which two others like them made 
 in the hinder-part of the Furnace , do correspond^ and 
 
 through 
 
4 61 Explanation of the Figures. 
 
 through which two /mail iron-Bars are introduced , to 
 fuftain the Muffle . 
 
 p. A round Hole open in the upper 'Part of the Fur- 
 nace, that the AJhes and burning Coals ?nay be ftirred 
 with a f mall iron- Rod introduced through it. 
 
 q. The Cover , which may be moved backward and 
 foreward , between the iron- Plates c. c, rivetted to the 
 Right and Left upper-Edge of the Furnace , and turned 
 down . 
 
 r. A Segment of a Cylinder faftened at Top of the Co - 
 ver q. 
 
 s. s. The Ears of the Cover , ferving as a Funnel , or 
 Flue , and upon which an iron- Pipe may be put . 
 
 t. The conick Tube to be put upon the Segment r. of the 
 Cover , ferving as a Funnel or Flue to excite the Fire. 
 
 Fig. II. A fquare Ledge divided into two Parts , 
 and to be placed within , at Top of the upper- Border g[ 
 the Door of the AJh-hole (Fig. I.) e. and upon which the 
 Lute wherewith the Furnace is inwardly done over , and 
 the prifnatical iron-Bars which fuftain the Grate , do 
 reft. 
 
 Fig. III. Is the perpendicular SePlion of the Furnace 
 (Fig. I.) pafflng through the 'Middle of the fore and 
 hinder -Surface, that one may openly fee the inward Dif- 
 pofttion of the Furnace , as if one Jhould look into it ft de- 
 ways. 
 
 Fig. IV. The Furnace cut perpendicularly, the Section 
 faffing through the Sides of it *, to Jhew the inward Dif 
 pofition , as if one Jhould look into it backwards and for- 
 wards. 
 
 Fig. V. An elliptical wooden Mould, according to 
 which the inward Cavity of the Furnace reprefented in 
 the following Fig. muft be formed. 
 
 a k The upper Part cut off, which forms (Fig. VII.) 
 the inferior Extremity muft be cut off in the fame Man- 
 ner, to make the Body of the Furnace. 
 
 Fig. VI. The melting Furnace, made according to 
 the Mould (Fig. V.) 
 
 d. An iron- Ring, applied to the Border of the Fur- 
 nace , to hold in the Lute wherewith the Inftde of the 
 
 Furiiact 
 
Explanation of the Figures. 463 
 
 Furnace is done over . A like one is faftened at the lower 
 Part of the Furnace , 
 
 e. e. Ears , to lift up and manage the Furnace. 
 
 c. c. T wo Holes , facing which there are two other 
 like ones behind , through which are paffed the two fmall 
 iron-Bars (F i g. XL) wherewith the Grate (Fig. XII.) is 
 fupported. 
 
 F 1 g. VII. The Cover, to fet upon the Furnace , when 
 a ftrong Fire and Draft of Air is necejfary . The Figure 
 of it may be the Complement of the Part cut off of the 
 Ellipjis (Fig. V.) a. 
 
 b. Is a Door hung on Hinges , through which the Fuel 
 of the Fire is introduced into the Furnace . 
 
 c. c. The Ears of the Cover. 
 
 d. A Segment of a Cylinder , upon which an iron - 
 Tube may be put in the Manner of a Funnel to in - 
 creafe the Fire \ like that put upon the docimaftical 
 Furnace Fig. L t. 
 
 Fig.VIII. The Door of the Cover ofEiG.Yll.feen on 
 the Injide , with a projecting iron Plate all round it, to 
 faften the Lute wherewith it is coated. 
 
 Fig. IX, The afh-Hole , or bottom-Part, on which 
 the Furnace (Fig, VI.) is put. 
 
 c. An iron- Ring on which the Furnace is fupported. 
 
 d. A Hole to introduce the Nofel of the Bellows . 
 
 b. A Door , to admit the Air , and take cut the Ajhes. 
 
 Fig. X. Another bottom-Part , coated within, and 
 
 forming the Bed f. g. h. which receives the melted Metal , 
 
 c. A Hole to introduce the Poker. 
 
 d. A Hole for the Nofel of the Bellows. 
 
 e. A Hole from which the melted Matter may be 
 let out of the Bed within , through a Channel that 
 reaches from the Bottom of the Jaid Bed g. down to the 
 faid Hole . 
 
 Fig. XI. Two fmall iron-Bars , which are intro- 
 duced through the Holes o. o. of the docimaftical Furnace 
 Fig. I. or through the Holes c. c. of the melting Fur- 
 nace (Fig. VI.) in the former to fupport the docimaftical 
 Muffle , and to fupport the Grate in the latter. 
 
 Fig, XII. The Grate for the melting Furnace. 
 
 F ig. 
 
4^4 Explanation of the Figures. 
 
 Fig. XII I. The fame bottom- Part of Fig. X. but Jb 
 dijpoj'ed , as that the melted Matter collected in the Bed 
 of it , may be let out through the Hole e. Fig. X. and 
 be received into a Bafon i. placed on the Out fide , fur+ 
 rounded with burning Coals . 
 
 PLATE IV. 
 
 Fig, I. The Athanor (§ 242.) 
 
 a. a. a. 2 . Tower of the Athanor, or chief Fur - 
 
 which receives the Fuel of the Fire : The pricked 
 Lines indicate the Thicknefs of the Wall. 
 
 b. b. b. b. The inner Sides which form the Cavity > 
 sind are each ten Inches long. 
 
 c. The Door of the aJh-Hole. 
 
 e. The upper-Door. 
 
 d. The Grate , which is placed even with the Bottom 
 of the Door e. 
 
 f. The Cover wherewith the upper-Aperture of the 
 Tower is Jhut. 
 
 g. g. A Flue, through which the Fire afcends from 
 the Tower into the firft Furnace. 
 
 h. h. h. h. A hollow Prifine , which forms the firft 
 fecondary Furnace. 
 
 i. i. A feml cylindrical Arch, wherewith the af or ef aid 
 Prifme is clofed atop . 
 
 k. k. k. k. An iron- Plate coated within, wherewith 
 the fore- Part of the firft fecondary Furnace is Jhut. 
 
 l. A round Hole in the Plate k. k. k. k, through 
 which the Neck of the Veffel 7 . may be pajfed. 
 
 m. A Stopple, wherewith the Hole I. may be Jhut . 
 
 n. n. Iron-bars. 
 
 o. o. o. o. Iron-hooks fafiened in the Wall, to receive 
 the Iron- bars. 
 
 6. An ir on- Door to Jhut the Flue g. g. 
 
 p. p. p. p. Iron- chains, with which the faid Dcor may 
 be lifted up. 
 
 **. Hooks on which the Door may be fufpended with the 
 Chains at any determined Height. 
 
 q. q. q. q. 
 
Explanation of the Figures. 46J 
 
 q. q. q» q. j The Funnel of this Furnace. 
 
 r. r. An iron- P late , wherewith the Funnel ?nay he 
 Jhut and opened . 
 
 s. s. s. s. A fqu are Iron-Frame made of a double 
 Plate , receiving the Plate r. r. 
 
 t. t. Another Flue , through which the Fire pajfes 
 from the firft fecundary Furnace into the fee end. 
 
 u. u. u. u. Another fecundary Furnace cylindrical . 
 
 v. v. Its upper circular Aperture , fioped at the fore - 
 Part^ receive. 
 
 w. w. iron- Pot which is to he hung in this fe~ 
 
 cond fecund ary Furnace 
 
 x. x. y^/z iron- Ring, by which the Pot w. w. ' 
 /&? upper-Border of the Furnace . 
 
 y. yf Segment cut out of the Pot and corresponding 
 with the foregoing v. v. 
 
 z. Flue , which conveys the Fire from .the fecond into 
 the third Furnace. 
 
 1. 1. 1. 1. Fhe third fecundary Furnace, like the fe- 
 cond 5 zzzz;/ having alfo a Pot. 
 
 2. 2. 2. 2. ,Fhe fecond Funnel. 
 
 3. A Plate, to Jhut and open the Funnel 
 
 4. yf/z Aperture which leads from the third Furnace 
 into the Funnel 
 
 5. 5. 5. Fhe third Funnel. 
 
 7. yf/z earthen Retort , placed in the firft fecundary 
 Furnace k. k. i. i. having its Neck through the Hols 
 of the Door thereof 
 
 8. yf Recipient. 
 
 9. A glafs Retort, placed in the iron-Pot of the fecond 
 fecundary Furnace , which Pot is filled with Sand. 
 
 10. A Recipient. 
 
 11. A Cucurbits placed in the Pot of the third Fur- 
 nace . 
 
 12. Stands, which fupport the Recipients, and which 
 may be rafted, or lowered with Screws. 
 
 Fig. II. A Pair of Tongs, to take Lefts a nd Coftpel St 
 out of the lire: 
 
 a. An iron-Rivett, wherewith the two Legs of the 
 Fongs are joined. 
 
 Hh 
 
 b. Fhe 
 
4 66 Explanation of the Figures. 
 
 b. The fe mi-lunar anterior Tart of the Tongs , 
 wherewith the Vejfels are taken hold of 
 
 c. The Ears wherewith the Tongs are laid hold of 
 a?id managed . 
 
 Fig. III. A Pair of Pincers, to take up fmall Grains , 
 
 and fmall PVeights. 
 
 Fig. IV. A Pair of Tongs , to take Crucibles and 
 other open Vejfels of a middling Size, out of the Fire . 
 
 Fig. V. A Pair of Tongs, to embrace large Cru- 
 cibles, and the largefi Vejfels charged with a great 
 Quantity of Metal . 
 
 a. A fingle femi-Circle fafened at one of the Legs of 
 the Tongs, 
 
 b. A double femU Circle fajlened at the other Leg , 
 which intercepts the foregoing femi-Circle a, when you 
 Jhut the Tongs. 
 
 Fig. VI. A fmall iron-Ykook, to fir the Matters 
 in the Tefisput under the docimafical Muffle. 
 
 Fig. VII. A Rod of Iron , two Foot and an half long, 
 and half an Inch thick , to fir the burning Coals and the 
 AJhes upon the Convexity of the docimafical Muffle , put 
 in the Furnace Plat . III. Fig. I. 
 
 Fig. VIII. An iron-Yiook, three Foot long, and from 
 a quarter to half an Inch thick, to fir the Maffles in the 
 Crucibles put in . the wind-Furnace. 
 
 Fig. IX. The Poker, wherewith the melted Metal 
 or the Scoria in the large Tefi are flirred. 
 
 Fig. X. A Poker, to be introduced through the Boor 
 of the ajh-llole, to free the Grate of the AJhes or fmall 
 Coals wherewith it is obflrucled. 
 
 Fig. XL A fmall iron- Ladle, with a long Handle, 
 wherewith the Matter is put into the Vejfels that are in 
 the Fire. 
 
 Fig. XII. A wooden-Sc reen, with a Slit in it a. 
 
 Fig. XIII. A cement atory or blow-Pipe. 
 
 Fig. XIV. A Smith’s-Forge not defcribed indeed 
 among the foregoing Furnaces , but eafy to be known from 
 th s Figure, as much as is required in Practice. 
 
 a. A double Pair of Bellows. 
 
 b. A 
 
Explanation of the Figures. 467 
 
 b. A Hole made in the fide Wall , through which the 
 Nozel of the Bellows communicates with the Forge . 
 
 c. A final t Pity in which the Veffels or the larger T ft 
 may he put. 
 
 Fig. XV. A. a Furnace, for a large Teft co- 
 hered with a Muffle , the fore- Part of which is open y 
 that the inward Difpofition of it may be feen . 
 
 a. The Teft. 
 
 b. The Muffle . 
 
 c. c. Two air- Hole Sy through which the Air may enter 
 ■to excite the Fire . 
 
 e. e. e. e. Apertures which admits the Air* 
 
 B. Alike Furnace , fhut before. 
 
 d. A Door to which the Muffle is contiguous , that the 
 Metal and Scoria’s may be feen within , and flirred. 
 
 PLAT. V. 
 
 Fig. I. A Pair of double Bellows, with their 
 Frame. 
 
 a. a. a. a. Iron-ftays, faftened to the Uprights of the 
 Frame of the Bellow s, every one of which may receive 
 the Trunions or Axles of the Bellows , that they may be 
 raifed or lowered at pleafure. 
 
 b. b. Iron- Keys, wherewith the Trunions are f aft- 
 enedy left they Jhould flip off when the Bellows are 
 worked . 
 
 c. c. Two Upright s y which receive the Nozel of the 
 Bellows. 
 
 d. d. d. d. Holes in the Uprights c. c. 
 
 e. An iron- Pin, which being paffled through the Holes 
 
 d. d. d. d. fuftains the Nozel of the Bellow s, that it may 
 be raifed or lowered. 
 
 f. A Weight, which diftends the lower Part of the 
 inferior Bellows. 
 
 g. A Weight, wherewith the upper Part of the 
 Bellows are charged , that they may be prejfed down by 
 a determined Force. 
 
 h. The Handle, wherewith the Bellows are worked, 
 
 H h 2 ' i. A 
 
4^S Explanation of the Figures. . 
 
 i. A Chain, on which the Bellows are fufpended y 
 when at reft. 
 
 Fig. II. The docimaftical Balance. 
 
 a. b. The Beam. 
 
 c. The Tong. 
 
 Fig. III. The Fork. 
 
 a a. Two Holes , in which the Axis turns . 
 
 d. d. Two Holes, which retain the Clafp. 
 
 c. The Needle, which Jhews the Equilibrium. 
 
 b. An Aperture, that the Tongue (Fig. II. c.) may 
 be feen in the Place where it correfponds to the Point of 
 the Needle . 
 
 Fig. IV. The Clafp. 
 
 Fig. V. A. A. The Diihes, or*Scales, which are 
 fufpended with Silk-firings^ on the Extremities of the 
 Beam (Fig. II.) a. b. 
 
 B. B. Two moveable Diihes, which being loaded with 
 the Weights and Things to be weighed , are put into the 
 foregoing Difloes. 
 
 Fig. VI. The Support, on which the Balance is fuft 
 
 pended. 
 
 a. The Pedeftal. 
 
 b. The Pillar. 
 
 e. An Arm. 
 
 d. The firft Pully. 
 
 e. The fecond Pully. 
 
 f. The third Pully. 
 
 g. Another Arm. 
 
 h. An oblong Hole. 
 
 i. A fmall Plate, to he introduced through the 
 Hole h. 
 
 k. A Weight faftened on a Silk-firings where- 
 with the Balance may be kept raifed . 
 
 Fig. VII. A Cafe, in which the Balance is put up. 
 
 a. a. a. The Windows. 
 
 b. The Support (Fig. VI.) with the Balance. 
 
 c. The Silk-fk ring conveyed through a fmall Hole made 
 at bottom of the fore- Window, wherewith the Balance 
 may be raifed or lowered , when the Cafe is flout. 
 
 e. c. 
 
Explanation of the Figures. 46c? 
 
 C. e. Drawers, wherein the Weight s> Scales , and other 
 /mail Utenfils are put up. 
 
 Fig. VIIL It Jhews the Weights inciofed in a Box. 
 
 Fig. IX. The Proof-Needles, faftened together. 
 
 a. a. a. The Extremities of them which are rubbed 
 againjl the Touch-ftone. 
 
 Fig. X. The Touch-ftone. 
 
 P L A T. VI. 
 
 Fig. I. The glafs - Furnace to be feen on the fore- 
 part. 
 
 A. The inferior Chamber, which is the a [h -hole . 
 
 a. Its Door through which the AJhes are taken out 9 - 
 and the Wind if admitted either immediately , or by 
 Means of the Pipe b. which is conveyed thither from a 
 Hole made in the Wall of the Laboratory . 
 
 c. The Place where the iron- Bars are put. 
 
 chch The Ledge upon which the Iron-bars reft , and 
 whereon the VeJJels are put. 
 
 B. The fecond Chamber, or fire-Place. 
 
 e. The great Door. 
 
 f. f. The finaller Doors . 
 
 C. The third Chamber. 
 
 g. A Hole , through which the Flame pajfes from the 
 fecond into the third Chamber . 
 
 h. h. h. Doors . 
 
 i. i. The Hearth or Floor . 
 
 D. The fourth Chamber. 
 
 k. k. A quadrangular Hole for the Pajfage (ft the 
 Fire. 
 
 l. The Door. 
 
 m. The Funnel. 
 
 n. n. n. n. &c. prickt Lines , /hewing the Form of the 
 inward Cavity of the Furnace. 
 
 o. o. o. 0. o. o. o. Small Holes made through every 
 Door. 
 
 Fig. II. The Furnace reprefented at the hinder- 
 part. 
 
 Fig. III. The Piffure of the Furnace cut perpen- 
 dicularly in the Middle : Together with a Reprefentation 
 
 H h 3 of 
 
470 Explanation of the Figures. 
 
 sf the Vejfels within . The Letters correfpond with thoje 
 if Fig. I. 
 
 Fig. IV. A cylindrical VefTel flout clofe at Top. 
 a. A Hole through which the Matter may he put 
 into it, and examined when therein. 
 
 Fig. V. A common triangular Crucible, adapted to 
 the fame Ufe as the foregoing Fig. IV. 
 
2 9^/llynJ+ Jc. 
 

r„ 7 vm j 
 
 MytdeJT. 
 

 
 
 2 £* 
 
 



I N D E X. 
 
 A. 
 
 Bathenen Page 214 
 
 /-% Acids 
 
 29 
 
 A m. their diffolvingVir- 
 
 tue 
 
 
 — — increafed by Heat 
 
 3 ° 
 
 Acid of Vitriol 
 
 ibid. 
 
 Wine 
 
 ibid . 
 
 — (native Foftile) 
 
 ibid. 
 
 Allum 
 
 7 
 
 — - Nitre 
 
 3 1 
 
 Its Production 
 
 3 L 32 
 
 . Nitre in the 
 
 Cement 
 
 
 272 
 
 — — Salt 
 
 38 
 
 It dilTolves Silver the 
 
 dry way 
 
 272 
 
 Its Production 
 
 3 S 
 
 Sulphur 
 
 . 7 
 
 (vague Foflile) 
 
 ibid. 
 
 ► — - (vegetable) 
 
 29 
 
 /Ethiops Mineral 
 
 353 
 
 Air too impetuous diminiflies the 
 
 Fire 
 
 298 
 
 Alkali (fixt) 
 
 z8 
 
 — - Vitrifies Stones, and im- 
 
 nerfeCt Metals 
 
 28, 29 
 
 does not diffolve Gold 
 
 and Silver 
 
 ibid. 
 
 . rejeCts Mercury 
 
 29 
 
 i—— - — — reduces Calxs of Metals 
 
 made with Acids 
 
 ibid , 
 
 — (native) 
 
 7 
 
 — — (volatile native) 
 
 ibid. 
 
 Allay 
 
 1 1 8 
 
 — (white) 
 
 ibid , 
 
 Allay (mixt) 
 
 ibid. 
 
 Allum 
 
 172 
 
 — Its Matrix’s 
 
 ibid. 
 
 — Generation 
 
 ibid . 
 
 — Preparation 
 
 413 - 
 
 — Variety 
 
 ibid. 
 
 — (Plumofe) 
 
 1 1 
 
 Aludels 
 
 189 
 
 Amalgamation 21, 22, 180, 
 
 , 252 
 
 Amarill. See Smiris 
 
 
 Amaufa 
 
 447 
 
 Amber 
 
 128 
 
 Amianthus 
 
 1 1 
 
 Antimony 
 
 191 
 
 (Crocus of) 
 
 35 s 
 
 _ — (Eliquation of) 
 
 out 
 
 of its Ore 
 
 356 
 
 . — (Liver of) 
 
 353 
 
 — — — (Ore of) 
 
 191 
 
 — — — - (Regulus of) 
 
 5 
 
 — It is volatile 
 
 24 
 
 (Simple Regulus of) 
 
 
 361 
 
 By Metals 
 
 3 6 + 
 
 (Sulphur auratum of) 
 
 
 3 5 3 
 
 (Fixt Sulphur of) ibid. 
 
 It purifies Gold 
 
 2 7 7 r 
 
 
 CO 
 
 _ — - May be turned 
 
 into 
 
 Glafs 
 
 24 
 
 — ■ (Glafs of) 
 
 3 59 
 
 Is very rapacious 
 
 ; 24 
 
 Its Rapacioufnefs in- 
 
 creafes by a Phlogifton 
 
 ibid \ 
 
 Anvil 
 
 99 
 
 Apyri (Stones called) 
 
 10 
 
 H h 4 Aqo* 
 
INDEX. 
 
 Aqua Fortis. See Acid of Nitre 
 
 * Regis 38 
 
 Arenarii (Stones called) 9 
 
 Arfenick 6, 1 29 
 
 ■ a femi-metal 5 
 
 «**— « — — lies hidden in feveiil 
 Minerals 1 3 1 
 
 hxes with Earths 22 
 
 .* penetrates Metals ibid . 
 
 & 23 
 
 — — « — is rapacious ibid. 
 •— — (White Cryftalline) is 
 fixt by Mercury’ 397 
 
 * — — Fixt Alkali 400 
 
 — , Fixt alkaline Salt 
 401 
 
 -Earths 392 
 
 — — - Determines Earths to 
 
 come to a Fufiori ibid. 
 
 * — — Does not take Flame 
 
 with Nitre 294 
 
 — Expels the Spirit of 
 
 Nitre ibid. 
 
 (Pure) does not melt 
 
 perfectly 396 
 
 — ~ (Yellow) ibid. 
 
 ■ b- — (Red) ibid. 
 
 Art (docimaftical) 1 
 
 - — — - — — Its Ufe in 
 
 Metallurgy 198 
 
 —— — Phyfick 199 
 
 - — — — * — Glafs- making 
 
 ibid. 
 
 Afbeftus 1 1 
 
 Afphaltum 1 28 
 
 Arrament-iiein. See. Ink-hone 
 
 B. 
 
 Balance (docimaftical)' 160 
 
 — Its Structure' ibid. 
 
 — Examination 103 
 
 — - Correction 104 
 
 Berg-blau 144 
 
 Berg-grun ibid. 
 
 Bilrnuth 5, 25, 3 67 
 
 Ore 1 61 
 
 — — — — Is volatile in the Fire 
 368 
 
 ... (Sublimate of) reducible 
 
 ibid. 
 
 Bitumen 1 28 
 
 Bley-glantz 147 
 
 • Klaar Spieffiger ibid . 
 
 Bley-fack 216 
 
 * Schweifftg 1 49 
 
 Blicken 2 1 3 
 
 Blood-ftone, or Blut-ftein 137 
 
 Bole 9 
 
 Borax 40 
 
 Vitrifies Stones ibid. 
 
 Box (granulating) 70 
 
 Brafs 376 
 
 Brine. See common Salt 
 Brunftein. See Manganefe 
 
 C. 
 
 Cadmia Forna'cum 23,26, 378 
 Cceruleum Montanum 144 
 Calaminaris (Lapis), or Cala- 
 mine 140, 1 7 1, 376 
 
 Calcination ’ 190 
 
 Calxs of Metals 26, 27, 443 
 
 — - — (Refraftory)' 
 
 ibi,d* 
 
 Caratura. See Alla y 
 
 
 Cementation 
 
 270 
 
 Cement- Kupfer 
 
 169 
 
 Wafter 
 
 ibid . 
 
 — — Pots 
 
 71 
 
 Cements 
 
 46 
 
 — - — (Gradatory) 
 
 274 
 
 Cerufta Nigra 
 
 *181 
 
 Chalcitis 
 
 117 
 
 Chalk 
 
 16 
 
 — — — (Red). Seered-Lead 
 
 Ghryfocolla. See Borax 
 
 
 Cinnabar 1 39 
 
 > 3 53 
 
 - — — * (Sublimation of) 
 
 354 
 
 Clay 
 
 9 
 
 Clcer 
 
 5 5 
 
 Coals (Sea) 
 
 128 
 
 Coating. See Lorication 
 
 74 
 
 Cobalt 130 
 
 , 162 
 
 — — — (Flower of) 
 
 128 
 
 Cone (melting) 
 
 71 
 
 Confrafait. See Zink 
 
 
 Coppelling 
 
 185 
 
 Coppels 
 
 52 
 
 — — Are deftroyed by Anti- 
 
 mony 
 
 220 
 
 
 Ren- 
 
i N' D E X. 
 
 Coppels rendered black by the 
 Scoria of Copper 227,228,300 
 Copper- Pyrites 145 
 
 — ■ (Native) 143 
 
 — Ores ibid, and foil. 
 
 (Precipitation of) out of 
 
 its Ores 301, 303, 304 
 
 Ccpper-Ore (the Roaiting of) 
 
 ibid. 
 
 * — — (The Walking of) 
 
 326 
 
 — — — — (Examination of) 
 by a moiit Precipitation 327 
 Copper (Regulus of Crude ) 3 1 1 
 ■ — - Lying hid in moift Men- 
 flrua is found out with Alkali 
 258 
 
 — — - — (Black) 307, 308, 3 1 6 
 — — — • Is precipitated out of 
 Iron by Sulphur 3 1 3 
 
 — — Is purified by Scorifica- 
 tion 208 
 
 Freed from Iron by Lead 
 
 320,321 
 
 - - - (melted) will not bear 
 
 Cold nor Moifture 323 
 
 Corufcation. See Blicken 
 Crucibles 66 
 
 Cucurbits (fmall feparatory) 68 
 
 Eliquation 1 g 2 
 
 — — Of Silver out of Cop- 
 per 328 
 
 Elutriation 1 97 
 
 Encaufta * 446 
 
 Errors to be avoided, proceeding 
 from additional Ingredients 
 217 
 
 Examination of Ores, by Vitri- 
 fications 424 
 
 — ' — - tfc. is uncertain 
 
 . 4^5 
 
 — - (Statical, and hy- 
 
 droftatical) 447 
 
 F« 
 
 Fahl-Ertz 145 
 
 - i — Kupfer-Ertz ibid. 
 
 Fallung 196 
 
 Figure (The) of Minerals is not 
 
 D. 
 
 69 
 
 Difh (The fmall golden) 
 
 Lccimafia (Definition of) 
 
 — — — (Objedls of) Ibid. 
 
 — ~ — — (Ufe of) 13 
 
 — — (End of) ibid. Fufion 
 
 Durch-fchweiffen 343 
 
 conflant 
 Fliegen-ftein 
 Flint 
 Flowers 
 Flux 
 
 — — (Reducing) 
 
 (Black) 
 
 (White) 
 
 Foffils. See Minerals 
 Fourthing. See Quartatio 
 Furnace (docimaftical) 
 (Melting) 
 
 124 
 
 394 
 
 9 
 
 188 
 
 48 
 
 5 ° 
 
 ibid 
 
 51 
 
 75 
 
 82 
 
 — * (Defcription of the) of 
 Glafs-makers, for Experiments 
 427 
 
 184 
 
 G, 
 
 Earths 
 
 E. 
 
 (Sealed) 
 
 8 
 
 9 
 
 195 
 
 Edulcoration 
 
 Eifen-man, Eifen glimmer 139 
 -Grob-koernig, Grob-fpeiffig 
 339 
 
 Klaar-koernig, Klaar- 
 fpeiffig 346 
 
 * — — Schweiffig 149 
 
 E'le&rum. See Amber 
 
 Gahr-Kupfer 
 Galena 
 Garnate 
 GifFt-Mehl 
 Glafs 
 
 Gall 
 
 Of Lead 
 
 — — KopfF. See Haematites 
 Gold ~ 2,2* 
 
 — * (Native) 157, and foil 
 
 Gold 
 
 J 47 
 
 39 > 
 185 
 42 
 18, 19 
 
I N D 
 
 Gold (Fulminating) 261 
 
 — — — — ~ (Reduction of) 
 
 285 
 
 Gold-folder 144 
 
 (Melting Precipitation of) 
 
 279 
 
 — — - (The purifying of) with 
 crude Antimony 275 
 
 — Is not found in any proper 
 Ore 158, and foil. 
 
 — — Refills Coppelling 
 
 259 
 
 Is feparated from Silver by 
 
 Aqua Regis 
 
 260 
 
 Fortis 
 
 262 
 
 Granulation of Lead 
 
 3 5 
 
 — Tin 
 
 16 
 
 Gravel 
 
 8, 9 
 
 Gravity (fpecifick) of Minerals 
 
 124, 
 
 . 12 5 
 
 Grit 
 
 8 
 
 H. 
 
 
 Haematites 
 
 137 
 
 Hepar Sulphuris 
 
 3*5 
 
 Hinterhalt 
 
 267 
 
 I. 
 
 
 feat 
 
 128 
 
 Ink-Hone 
 
 140 
 
 Iron 
 
 4 
 
 — — Ores 
 
 3 3 6 
 
 (Native) 
 
 ibid. 
 
 — Is attracted by the Load- 
 
 ftone 4. 337' 
 
 — Is not diflolved by Lead 
 
 224 
 
 - when deftroyed by Glafs 
 of Lead, is eafily Icorified 
 tbid. 
 
 — when mixt with Antimo- 
 ny, is not attracted by the 
 Load-Hone 337 
 
 — —— when melted, lofes its 
 Malleability 340 
 
 - — - Is freed from Sulphur, by 
 abforbent terrellrial Bodies 
 ibid. 
 
 Becomes malleable by Re- 
 duction, and by hammering 
 
 34i 
 
 — Turns to Steel, by a Ce- 
 mentation with inflammable 
 
 ■ fixt Bodies 344 
 
 E X. 
 
 And by Fuflon, and Ham- 
 mering 348 
 
 K. 
 
 Kupfer-Glantz 
 
 3 45 
 
 ■ — Glafs-Ertz 
 
 ibid. 
 
 — Nickel. 
 
 See Copper- 
 
 Ores 
 
 1 3 1, 146 
 
 Leg 
 
 3 3 4 
 
 - — Stein 
 
 3 1 3 
 
 — Walter 
 
 169 
 
 L. 
 
 
 Laboratory 
 
 123 
 
 Lapis (Lebetum) 
 
 1 1 
 
 Lead (Red) 
 
 3 Li 39 
 
 Lead 2 
 
 , 14, 15, 1 6 
 
 Calcines Tin 1 £ 
 
 (Black,) or Wad 181 
 
 — — (Native) 147 
 
 ■ ■ ■■ — Ores ibid. 
 
 ■ (Glafs of) becomes very 
 
 fufible and. penetrating, by 
 Arfenick 208 
 
 (Precipitation of) out of its 
 
 Ores 2Q2, 295, 297 
 
 — — Does not diflolve Iron 1 5 
 — — — (Calxs of ) ebulliate in the 
 Reduction 291 
 
 (Reduction of) in an open 
 
 Fire 296 
 
 (Separation of) from Cop- 
 per, by Eliquation 298 
 
 ■ ■■■ ■ (Pure) how known ibid. 
 
 — — Does not diflolve Copper, 
 
 unlefs agitated by a ftrong Fire 
 300 
 
 — — Is foon fcorifted by Arfe- 
 hick 222 
 
 To try, whether it contains 
 
 any Copper 299 
 
 Litharge 3, 15, 228 
 
 ■ Turns Stones into Glafs 
 
 3 7 
 
 — - Does not diflolve Metals 
 
 unlefs they are deftroyed ibid. 
 Lorication, v jpr Coating 74 
 
 Luna Cornua 257 
 
 ■ — — ■ Is volatile 256 
 
 Manganefe 
 
I 
 
 N 
 
 D 
 
 M. 
 
 Manganefe 
 
 138 
 
 (White) 
 
 4*9 
 
 Marble 
 
 10 
 
 Marie 
 
 10, 1 1 
 
 Melenterize 
 
 Melting 
 
 *8+ 
 
 Menftrua 
 
 14 
 
 — - (Moift) 
 
 ibid. 
 
 ■ — — (Dry) 
 
 ibid. 
 
 Menftruum (dry) of Metals 40,41 
 
 Mercury 
 
 4 
 
 — — — Is not a perfect Metal 
 
 Is altogether 
 
 ibid. 
 
 volatile 
 
 ibid. 
 
 *» — - — (Native) 
 
 *59 
 
 — (Virgin) 
 
 ibid . 
 
 •— — (Ores) 
 
 ibid. 
 
 
 nor Regulus of Antimony 22 
 
 - — — Amalgama 
 
 ibid . 
 
 Is feparated from amal- 
 
 gamated Metals, by Filtration 
 
 and Diftillation 
 
 234 
 
 — from Minerals 348 
 
 « — — Is revived by Iron 354 
 
 Metal (Prince’s) 
 
 25 
 
 Metals 
 
 2 
 
 Mica 
 
 1 1 
 
 Minerals 
 
 I, 2 
 
 — * Are feldom pure 
 
 ibid. 
 
 - — — . (Gaffes of) 
 
 ibid. 
 
 (Compound) ibid.& 123 
 
 — — ■ Not always known by 
 
 their Outfide 
 
 >3 
 
 (Vitriolick) 
 
 140 
 
 Mify 
 
 * 7 * 
 
 Molybdaena 
 
 181 
 
 Moulds (Set of) 
 
 72 
 
 Muffle (Docimaftical) 
 
 62 
 
 V N. 
 
 
 Naphta 
 
 128 
 
 Nieder-Schlag 
 
 192 
 
 Nihil Album 
 
 26 
 
 - — — Gryfeum ibid, & 375 
 
 Nitre 
 
 6, 1 77 
 
 — » (Generation of) 
 
 178 
 
 E # X, 
 
 — (Matrixs of) ibid. 
 
 — Detonates with a Phlogifton 
 
 6 
 
 — Confumes imperfect Metals 
 
 42 
 
 — {Cryftallizafion of) 416, 
 
 — 4 — Becomes volatile in a great 
 
 Fire 
 
 247 
 
 — Becomes fixt, Gfr. 418 
 
 Detonates and 
 
 becomes 
 
 Alkali 
 
 ibid . 
 
 — Renders Gold and Silver 
 
 malleable 
 
 248, 277 
 
 , O, 
 
 
 Offenbruch 
 
 26 
 
 Oker of Iron 
 
 3 39 
 
 Okers (Copper-) 
 
 144 
 
 Ollaris (Lapis) 
 
 1 1 
 
 Ores 
 
 132 
 
 - — - Crackle in the Fire 209, 
 
 
 221 
 
 (Artificial) 
 
 *33 
 
 (Fufible) 
 
 ibid. 
 
 (Unfufible) 
 
 ibid . 
 
 (Refractory) 
 
 ibid. 
 
 : (Differences of) 
 
 ibid . 
 
 — — - (Elutriable, or decantable) 
 
 — — (Indecantable) 
 
 . 7 * 
 
 ibid. 
 
 Orpine, or Orpiment 
 
 129 
 
 P. 
 
 
 Petroleum 
 
 128 
 
 Phlogifton enters into the Com- 
 
 polition of Metals 
 
 26 
 
 Facilitates the melting 
 
 of Metals 
 
 27, 28 
 
 Pix Juda'ca 
 
 128 
 
 Pompholyx 
 
 26, 375 
 
 Pot (Melting) 
 
 66 
 
 Pots (Cement) 
 
 71 
 
 Precipitating 
 
 192 
 
 Precipitation (Melting) or Preci- 
 pitation by Fufion 190,151 
 
 (Moiil) 196 
 
 Proceffes. What they are 1 
 — Their infinite Multi- 
 tude ibid. 
 
 Pyrites (White) 129 
 
 Pyrites. 
 
INDEX. 
 
 Pyrites (Yellow) 1 27, 137 
 
 - — (Sulphureous) of Iron 1 7 1 
 
 - — —Copper ibid. 
 
 ™ -Why refractory 221,222 
 
 Quartatio 
 
 Quartz 
 
 Reduction 
 
 R. 
 
 *94 
 
 9 
 
 — Of Lead confume theVef- 
 
 fels 207, 210, 214, 250, 269 
 Scorification 1 85 
 
 — — - — (Signs of a perfect) 
 
 206, 210 
 
 — — — — Done by adding In- 
 
 gredients, is facilitated by a 
 mechanical Mixture 2 1 
 
 26, 18 6 
 Does not reftore tin 
 
 Screen 
 Seigerung 
 Semi- Metals 
 
 219 
 
 98 
 
 192 
 
 whole of the Metal 
 
 ibid. 
 
 Silver 
 
 21 
 
 — Is performed with a 
 
 — Ore IC2, & foil . 
 
 pure Phlogifton 
 
 27 
 
 — (Native) 
 
 ibid. 
 
 Regulus 
 
 1 9 1 
 
 — — (The Coppelling of) 
 
 2 II 
 
 ■ Of Antimony 
 
 44 
 
 — — (The purifying of) 
 
 in a 
 
 - — Its Scorias 
 
 ibid. 
 
 large Ted 
 
 235 
 
 Reading 
 
 1 89 
 
 With Spirit of Salt 
 
 256 
 
 — — To be made in a mode- 
 
 With Spirit of Nitre 
 
 246 
 
 rate fire 364 
 
 Jloh-Stein 3 1 1 
 
 Ruby (Al'fenical) ’"45 
 
 — Of Sulphur ibid. 
 
 S. 
 
 Sal-Pontium 1 76 
 
 Sal -Gera 1 74 
 
 Salt (Common) ibid. I3 42 
 f ___(Cryftallizationof Common) 
 420 
 
 — — ■ (Marine) r 7 $ 
 
 — — - (Ammoniac) ibid. 
 
 Its Origine 176 
 
 (Precipitation of) out of a 
 
 fufible Ore 
 
 — (RefraCtory Ore of) 
 dered fuch by Earths 
 
 — (Pyritofe Ore of) 
 
 — (Separation of ) from 
 
 Salts 
 
 (Melting.) 
 (Neutral) 
 
 Their Difference 
 Penetrate earthen 
 
 See Flux. 
 
 40 
 
 , ! 75 
 
 VeSels 
 
 4 1 9 
 
 (Separation of) by Crystal- 
 lization 420, 421 
 
 Sand 
 
 (Black) 
 
 8, 9 
 
 I 4 ° 
 
 185 
 
 3 2 5 
 
 Schlacke 
 Schlack-Stein 
 Schmergek See Smiris 
 Schwartz-Kupfer 
 Schweffel-Schlacke 
 Scoria’s 
 
 — — - Having Metal in them 
 3 2 4 
 
 3 - 
 
 3°7 
 3 S 3 
 .85 
 
 205 
 ren- 
 218 
 
 221 
 Iron 
 
 222 
 
 — Iron-Ore 226 
 
 — — - - — An timony ibid . 
 
 — Tin 228 
 
 — — (An exaCt Separation of) 
 from Copper : Why difficult ? 
 
 232 
 
 — — Is not equally di delved by 
 Lead 237,239 
 
 — Is in almofl every Kind oF 
 Lead 217 
 
 Having Copper in it black- 
 ens in the Fire 227 
 
 Charged with Sulphur is 
 
 precipitated by Iron and Lead 
 250 
 
 Skellet (Edulcoratory) 69 • 
 
 Slate 8 
 
 Smalt 163, 370, 422, 446 
 Smiris 138 
 
 Solution (Moilt) 194 
 
 Sory 1 7 1 
 
 Spaad 1 o 
 
 Specimens to be examined : How 
 to be choferl 239, and foil. 
 Speife 314 
 
 Spiauter. 
 
I N D E X. 
 
 Spjauter. See Zink . 
 
 Spirit of Salt. See Acid of Salt. 
 Spodium 37 5 
 
 Stala&ites, or Drop-Stones i o 
 Steel (The Making and Proper- 
 ties of) 344 
 
 Stone (The Touch-) 1 i 4 
 
 , — — (Load-) 99, 140 
 
 » — — It attra&slron ibid. 
 
 attracts not all the 
 
 Ores of it 141 
 
 (Gravelly) 9 
 
 — (The Cleaving) or Schiftus 
 
 8 
 
 Stones 
 
 (Vitrefcent) 
 
 (Ink) 
 
 — - (Yellow) 
 
 (Grey) 
 
 — (Black) 
 (Red) 
 
 . ibid, 
 ibid. 
 
 140, 170 
 ibid, 
 ibid, 
 ibid, 
 ibid. 
 
 (Lime-) 
 
 Their Differences 8 
 
 Suker Montanum 
 Sublimation 
 
 — — (Geber’s) 
 
 (Glauber’s) 
 
 1 1 
 
 188 
 
 ibid. 
 
 ibid. 
 
 128 
 
 7 > 4 2 
 ibid. 
 
 Succinum 
 Sulphur 
 
 (Mineral) 
 
 • — - Is moil commonly rnixt 
 
 with Acid 7, 42 
 
 (Native) 126 
 
 (Variety of) ibid. 
 
 Is in almoft all Ores 1 27 
 Does not affeft Gold at 
 43 
 
 Penetrates Silver ibid. 
 — — _ — . Tin ibid. 
 
 Lead 
 
 Copper 
 
 all 
 
 timony 
 
 ibid, 
 ibid. 
 
 DifTolves Iron 44 
 
 — — Regulus of An- 
 
 ibid. 
 
 Bifmuth ibid. 
 
 — Does not penetrate Zink 
 
 ibid. 
 
 — — Is abforbed by Metals 
 feveral Ways ibid. 
 
 Auratum 4c, 385 
 
 — ( Liver of) ibid. 388 
 
 — — — Is rapacious 383 
 
 * — ~(Acid of) by the Bell 386 
 — — - (Proportion of the Acid 
 and Phlogifton of) 3 89 
 
 — (Artificial Confeflionof) 
 
 392 
 
 — (Diilillation of) 3 80 
 • — — — ■ (Flowers of) 383 
 
 * (Signs of a pure) 38s 
 
 Sulphuris (Lac) 389 
 
 Talck 
 
 Tell 
 
 Teils called 
 
 1 1 
 
 • ^ 
 
 in German Treib- 
 
 fcherben 
 
 — (The making of) 
 Their Matter 
 
 (Native) 
 
 Renders Metals brittle 
 
 60 
 
 61 
 
 60' 
 
 Tiles 67 
 
 Tin 3 
 
 149 
 19, 
 20 
 
 — — Is calcined with Lead 228, 
 229 
 
 ~ and Copper mixt together 
 are eafily fcorified with Lead 
 ibid, 
 
 Is very deftrudlible by Fire 
 
 334 
 
 — — » Ore io 
 
 (Preparation of the) for a 
 
 Reduction 332 
 
 — — (Reduction .of the) 334, 333 
 - — - (Variety of the) ibid. 
 Tongs . 95 
 
 T rockene-Scheidung 195 
 
 Tropf-Schweffel 386 
 
 Trough (The Walking-) 69 
 Tube (Cementing) * or Blow-pipe 
 
 99 
 
 Tutty 378 
 
 U. 
 
 URulation* See Roafting. 
 
 V. 
 
 Verfchlackung 
 Viride Montanum 
 
 185 
 
 H 4 
 
 Vitri- 
 
INDEX. 
 
 Vitrification 185 
 
 Vitriol ^ 167 
 
 (White) 169, 170 
 
 Of Copper 168 
 
 Of Iron ibid . 
 
 (Native) ibid. 
 
 In medicinal Waters ibid. 
 (Stala&ic) 140, 169 
 
 (Cryftallization of) 406 
 
 (Oil of) deltroys Iron 
 
 and Zink, not Copper 224 
 Vitriols (Artificial) 408 
 
 Volatile Subftances, when agi- 
 tated by a great and fudden 
 Fire, raife all fixt Bodies 2 55, 
 266, 267, 306 
 
 W. 
 
 Wafierbley 1 8 1 
 
 Weight (Docimaftical) 1 08 
 
 — (Centner) ibid. 
 
 — — (Caraft) 1 1 3 
 
 - (Grains) 1 1 2 
 
 Weight (Penny-) orPondus Nura- 
 mularium ibid. 
 
 ■ (Mark-) ibid. 
 
 Weis-Ertz 144 
 
 Wifmuth-Graupen 162 
 
 Wifmuthum 130, 131 
 
 Wolfram 139 
 
 Z. 
 
 ZafFra 163 
 
 Zink ibid. & 5 
 
 Its Origine ibid, and foil . 
 
 -Ore 166, and foil. 
 
 - - Is irreducible 1 86 
 
 - — - Diffolves Metals 25 
 
 — ; — Is very rapacious ibid. 
 
 (Flowers of) 370 
 
 — — Turns to Glafs ibid . 
 
 • ■ The whiteft are ir- 
 reducible ibid. & foil. 
 
 — — Vaniflies intirely, when 
 
 agitated by a violent Fire 372 
 
 Zinn Graupen 1 qo 
 
 Zwitter ibid » 
 
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