I 
 
COMPENDIOUS SYSTEM 
 o P 
 
 Mineralogy & Metallurgy; 
 
 tXTRACTED FROM 
 
 THE AMERICAN EDITION 
 
 O F 
 
 THE ENCYCLOPAEDIA, 
 
 N OW PUBLISHING 
 
 BT r HO MAS DOBS01\ r , 
 
 ,0 
 
 AT THE STONE-HOUSE, N u 41, SOUTH SECOND-S-TRFT. 
 M DCC,XC1V. 
 
CONTENTS. 
 
 Page. 
 
 INTRODUCTION i 
 
 PART I. 
 
 Of Experiments upon Earth and Stones, 2 
 
 Experiments upon Metals and Ores, 1 4 
 Description of a portable JLabaratory for 
 
 a/faying Minerals, 3^ 
 
 PART IL 
 
 ARRANGEMENT of MINERAL BODIES, 41 
 
 CLASS I. EARTHS, - -4.2 
 
 Order I. Calcareous Earths, - 43 
 
 IT. Ponderous Earths ^ 60 
 
 III. Magnefian Earths, - - 62 
 
 IV. Siliceous Earthy - . ' 68 
 V. Argillaceous Earth, - - 101 
 
 CLASS II. SALTS, - 108 
 
 Qrdir I. Acid Salts - - 1 09 
 
 II. Alkaline Salts, HO 
 
 III. Neutral Salts, - - 118 
 
 IV. Earthy Neutral Salts, - 1 28 
 V. Metallic Salts, - 138 
 
 VI. Triple Salts, 144 
 
 CEASS III. MINERAL INFLAMMABLE SUB 
 STANCES 148 
 CLASS IV. METALLIC SUBSTANCES, 184 
 
 Order I. Noble or P erf eft Metals, 188 
 
 II. LnperfeS or Bafe Metals, 2io 
 
 III. Semimetals, - 239 
 
 A 2 AJPEM- 
 
iv CONTENTS. 
 
 Page. 
 
 APPENDIX. Of Saxa and Petrifactions, . 266 
 
 Order I. Saxa * - ib. 
 
 II. Mineral Changes or Petrifactions, 306 
 
 III. Volcanic Produces, - - 310 
 
 METALLURGY, 323 
 
 Part I. Seel. I. Of Metals aud Metallization, 324 
 
 II. Mines and Ores in general, 343 
 
 III. Pyrites, 347 
 
 IV. E/aying Ores in general, 355 
 Part II. Containing a Swnmary Defer iption of 
 
 the Principal Ores of each Metal, 
 and the Method of E/aying them. 
 
 St5t. I. Ores of Gold, 360 
 
 II. of Platina, 363 
 
 III. of Silver, - ' - 364- 
 
 IV. of Copper, - 405 
 V. of Lead, 420 
 
 VI. of Tin, - 423 
 
 VII. of Iron, - - 425 
 
 VIII. of Mercury, 432 
 
 IX. of the Regulus of Antimony, 434 
 
 X. of Bifmuth, 437 
 
 XL of the Regulus of Cobalt, . - 438 
 
 XII. of Zinc, - 443 
 
 XIII. of Arfenic, 443 
 
 Part III. Smelting of Ores, 445 
 
 Stfl. I. Extraction of Sulphur from Pyrites 
 
 and other Minerals, 
 H. Smelting of Ores in general, 
 
 III. of Ores of Silver, 
 
 IV. of Ores of Copper, 
 V. of Ores of Iron, 
 
 VI. of Tin Ores, 
 
 VII. of Ores of Lead, 
 
 VIII. Ores of the Semimctals, 
 
MINERALOGY. 
 
 M: 
 
 .INERALOGY is thatfcience which teaches 
 us the properties of mineral bodies, and by which we 
 learn how to character ife, diftinguifh, and clafs them 
 into a proper order. 
 
 INTRODUCTION. 
 
 MINERALOGY feems to have been in a manner co 
 eval with the world* Precious ftones of various kinds 
 appear to have been well known among the Jews and 
 Egyptians in the time of Mofes ; and even the moil 
 rude and barbarous nations appear to have had fome 
 knowledge of the ores of different metals. As the 
 fcience is nearly allied to chemiftry, it is probable that 
 the improvements both in chemiftry and mineralogy 
 have nearly kept pace with each other ; and indeed it 
 is but of late, fmce the principles of chemiftry were 
 well underftood, that mineralogy has been advanced 
 to any degree of perfection. The beft way of ftudy- 
 ing mineralogy, therefore, is by applying chemiftry to 
 it ; and not contenting ourfelvcs merely with infpecl- 
 ing the outfides of bodies, but decompounding them 
 according to the rules of chemiftry, This method 
 has been brought . to the greateft perfection by Mr 
 Pott of Berlin, and after him by Mr Cronftedt of 
 B Sweden* 
 
C * ] 
 
 Sweden. To obtain this end, chemical experiments 
 in the large way are without doubt neceffkry : but as 
 a great deal of the mineral kingdom has already been 
 examined in this manner, we do not need to repeat 
 all thofe experiments in their whole extent, unlefs 
 fome new and particular phenomena fhould difcover 
 themfelves in thofe things we are examining ; elfe the 
 tedioufnefs of thofe proceffes might difcourage fome 
 from going farther, and take up much of the time of 
 others that might be better employed. An eafier 
 way may therefore be adopted, which even for the 
 mod part is fufficient, and which, though made in 
 miniature, is as fcientifical as the common manner 
 of proceeding in the laboratories, fince it imitates 
 tha% and is founded upon the fame principles. This 
 confifts in making the experiments upon a piece of 
 charcoal with the concentrated flame of a candle 
 directed through a blow-pipe. The heat occafioned by 
 this is very intenfe ; and the mineral bodies may here 
 be burnt, calcined, melted and fcorified, &c. as well 
 as in any great works. 
 
 For a defcription of the blow-pipe, the method of 
 tifing it, the proper fluxes to be employed, and the 
 different fubjscls of examination to which that inftru- 
 ment is adapted, fee the article Biotr-pipe, where all 
 thofe particulars are concifely detailed. It may not 
 be improper here, however, to refume thofe details at 
 greater length ; avoiding, at the fame time, all unne- 
 ceffary repetitions. After which we (hall exhibit a 
 fcientific arrangement of the mineral kingdom accord 
 ing to the mo ft approved fyftem. 
 
 PART L 
 
C 3 ] 
 PART I. 
 
 EXPERIMENTAL MINERALOGY ; 
 
 WITH A 
 
 DESCRIPTION OF THE NECESSARY APPARATUS '*. 
 
 SECTION I. 
 Of experiments upon Earths an:d Stones. 
 
 VV HEN any of thefe fubftances are to be tried, we 
 muft not begin immediately with the blow-pipe ; but 
 fome preliminary experiments ought to go before, by 
 which thofe in the fire may afterwards be directed. 
 For inftance, a (tone is not always homogenous, or of 
 the fame kind throughout, although it may appear to 
 the eye to be fo. A magnifying glafs is therefore ne- 
 ceflary to difcover the heterogeneous particles, if there 
 be any ; and thefe ought to be feparated, and every 
 part tried by itfelf, that the efrecis of two different 
 things, examined together, may not be attributed to 
 or.e alone. This might happen with fome of the finer 
 mics, which are now and then found mixed with fmall 
 particles of quartz, fcarcely to be perceived by the eye 
 The trapp (in German fchwartzftein) is alfo fometimes 
 
 * From Enjrerftrom's Treatife on the Blow- pipe, and Magel 
 lan's Defcription of Pocket-Laboratories, &c. fubjoined to the 
 En<rlifh Translation of Croniledt's Minerdogy, ad edit in a vols. 
 Pilly. 
 
 B 2 mixed 
 
3 4 1 
 
 mixed with very fine particles of feltfpar (fpatam fcin- 
 -tittans) or of calcareous fpar, &c. After this expe 
 riment, the hardnefs of the (tone in queft ion muft be 
 tried with fteel. The flint and garnets are com 
 monly known to ftrike fire with fteel ; but there 
 are alfo other ftones, which, though very feldom, are 
 found fo hard as likewife to ftrike fire. There is a 
 kind of trapp of that ha.rdnefs, in which no particles 
 of feltfpar are to be feen. Coloured glaffes refemble 
 true gems ; but as they are very foft in proportion to 
 thefe, they are eafily difcovered by means of the file. 
 The common qaartz-cryftals are harder than coloured 
 glaffes, but fofter than the gems. The loadftone dif- 
 covers the prefence of iron, when it is not mixed in too 
 fmall a quantity in the ftone, and often before the ftone 
 is roafted. Some kinds of haematites, and particularly 
 the ccerulefcens, greatly refemble fome other iron ores; 
 but this diftinguifhes itfelf from them by a red colour 
 when pounded, the others giving a blackifh powder, 
 and fo forth. 
 
 The management of the Btow-pipe'h'a.s beendefcribed 
 under that article ; but ? few particulars may be here 
 recapitulated, or added. 
 
 The candle ought to be fnuffed often, but fo that 
 the top of the wick may retain fome fat in it, becaufe 
 the flame is not hot enough when the wick is almoft 
 burnt toaflies; but only the top muft be fnuffed off, 
 becaufe a low wick gives too fmal! a flame. The blue 
 flame is the hotteft ; this ought, therefore, to be 
 forced out when a great heat is required, and only the 
 point of the flame muft be directed upon the fubje<5l 
 which is to be effayed. M. Magellan recommends, as 
 being moft cleanly and convenient, that the candle be 
 made of wax, and the wick fhould be thicker than or 
 dinary. Its upper end muft be bended towards ihe 
 matter intended to be heated, and the ftream of air 
 muft be directed along the furface of the bended part, 
 fo as not abfolutely to touch it. 
 
 The 
 
C 5 3 
 
 The piece of charcoal made ufe of in thefe expe 
 riments muft not be of a difpofition to crack. If this 
 Ihould happen, it muft gradually be heated until it 
 does not crack any more, before any afTay is made up 
 on it. If this be not attended to, but the affay made 
 immediately with a ftrong flame, fmall pieces of it will 
 fplit off in the face and eyes of the aiTayer, and often 
 throw along with them the matter that was to be af- 
 fayed. Charcoal which is too much burnt confumes 
 too quick during the experiment, leaving fmall holes 
 in it, wherein the matter to be tried may be loft ; and 
 charcoal that is burnt too little, catches flame from 
 the candle, burning by itfelf like a piece of wood, 
 which likewife hinders the procefs. 
 
 Of thofe things that are to be afTayed, only a fmall 
 piece muft be broken off for that purpofe, not bigger 
 than that the flame of the candle may be able to act 
 upon it at once, if required ; which is fometimes ne- 
 ce/Tary, as, when the matter requires to be made 
 red hot throughout, the piece ought to be broken as 
 thin as poffible, at leaft the edges ; the advantage of 
 which is obvious, the fire having then more influence 
 upon the fubjeft, and the experiment being more 
 quickly made. 
 
 Some of tiie mineral bodies are very difficult to be 
 kept fteady upon the charcoal during the experiment, 
 before they are made red hot ; becaufe, as foon as the 
 flame begins to aft upon them, they fplit afunder with 
 violence, and are difperfed. Such often are thofe which 
 are of a foft confidence or a particular figure, and 
 which prefer ve the fame figure in however minute par 
 ticles they are broken ; for inftance, the calcareous fpar, 
 the fparry gypfum, fparry fluor, white fparry lead- 
 ore, the potters ore, the teffellatcd mock-lead or 
 blende, &c. even all the common fluors which have no 
 determinate figure. Thefe not being fo compact as 
 common hard ftones, when the flame is immediately 
 urged upon them, the heat forces itfelf through and 
 B 3 
 
[ <5 3 
 
 in':o their clefts or pores, and caufes this violent ex- 
 panfion and difperfion. Many of the clays are like- 
 wife apt to crack in the fire, which may be for the 
 moil part afcribed to the humidity, of which they al 
 ways retain a portion. 
 
 The only way of preventing this inconvenience is 
 to heat the body as flowly as poffible. It is bed, fird 
 of all, to heat that place of the charcoal where the 
 piece is intended to be put on ; and afterwards lay it 
 thereon ; a little crackling will then enfue, but com- 
 monly of no great confequence. After that the flame 
 is to be blown very flowly towards it, in the beginning 
 not directly upon, but fomewhat above it, and fo ap 
 proaching nearer and nearer with the flame until it 
 become red hot. This will do for the mod part ; 
 but there are neverthelefs fome, which, notwithltand- 
 ing all the precautions, it is almoft impoflible to 
 keep on the charcoal. Thus the fluors are generally 
 the mod difficult ; and as one of their principal ch.i- 
 raclers is difcovered by their effects in the fire per fe, 
 they ought necefTarily to be tried that way. To this 
 purpofe, it is bed to make a little hole in the charcoal 
 to put the fluor in, and then to put another piece of 
 charcoal as a covering upon this, leaving only a fmall 
 opening for the flame to enter. As this ft one will never- 
 thelefs fplit and fly about, a larger piece thereof than is 
 before-mentioned mud be taken, in order to have atlead 
 fomething of it left. 
 
 But if the experiment is to be made upon a done 
 whofe effe&s one does not want to fee in the fire per fe, 
 but rather with fluxes, then a piece of it ought to be 
 forced down into melted borax, when always fome 
 part of it will remain in the borax, notwithdanding the 
 greated part may fometimes fly away by cracking. 
 
 I. Offubjlances t& be tried in tbejlre per fe. As the 
 ftones undergo great alterations when expofed to the 
 fire by them (elves, whereby fome of their characlerif- 
 ticks, and often the mod principal, are difcovered, 
 
 they 
 
[ 7 ] 
 
 they ought fird to be tried that way, obferving what 
 has been faid before concerning the quantity of mat 
 ter, direction of the fire, c. The following are ge 
 nerally the refults of this experiment. 
 
 Calcareous earth or Jlom, when it is pure, does not 
 melt by itfelf, but becomes white and friable, fo as to 
 break freely between the fingers ; and, if fuffered to 
 cool, and then mixed with water, it becomes hot, juft 
 like common quick-lime. As in thefe experiments 
 only very fmall pieces are ufed, this laft effect is bed 
 difcovered by putting the proof on the outfide of the 
 hand, with a drop of water to it, when inftantly a 
 very quick heat is felt on the fkin. When the calca 
 reous fubftance is mixed with the vitriolic acid, as in 
 gypG'rn, or with a clay, as in marie, it commonly 
 melts by itfelf, yet, more or lefs difficultly in propor 
 tion to the differences of the mixtures. Gypfum pro 
 duces generally a white, and marie a grey, glafs 
 or flag. When there is any iron in it, as a white 
 iron ore, it becomes dark, and fometimes quite black, 
 &c. 
 
 The Ji/icia never melt alone, but become generally 
 more brittle after being burnt. Such of them as are 
 coloured become colourlefs, and the fooner when it 
 does not arife from any contained metal ; for inftance, 
 the topazes, amethifts, c. fome of the precious ftones, 
 however, excepted : And fuch as are mixed with a 
 quantity of iron grow dark in the fire, as fome of the 
 jafpers, &c. 
 
 Garnets melt always into a black flag, and fometimes 
 fo eafily that they may be brought into a round glo 
 bule upon the charcoal. 
 
 The aroillacea, when pure, never melt, but become 
 white and hard. The fame effects follow when they 
 are mixed with phlogifton. Thus the foap-rock 
 is eafily cut with the knife ; but being burnt it cuts 
 glafs, and would ftrike fire with the fteel, if as large 
 a piece as is neceifary for that purpofe could be tried 
 
 in 
 
C 8 ] 
 
 in this way. The foap-rocks are fometlmes found of 
 a dark brown and nearly black colour, but neverthelefs 
 become quite white in the fire like a piece of China 
 ware. However, care muft be taken not to urge the 
 flame from the top of the wick, there being for the 
 inoft part a footy fmoke, which commonly will darken 
 all that it touches ; and if this is not obferved, a mif- 
 take in the experiment might eafily happen. But if 
 it is mixed with iron, as it is fometimes found, it does 
 not fo eafily part with its dark colour.. The argillaceas 
 when mixed with lime melt by themfelves, as above- 
 mentioned. When mked with iron, as in the boles, 
 they grow dark or black ; nnd if the iron is not in too 
 great a quantity, they melt alone into a dark flag ; 
 the fame happens when they are mixed with iron and 
 a little of the vitriolic acid, as in the common clay, &c. 
 
 Mica and ajbejlos become fomewhat hard and brittle 
 in the fire, and are more or lefs refractory, though 
 they give fome marks of fufibility. 
 
 Thej^W-j- difcover one of their chief characteriftics 
 by giving a light like phofphorus in the dark, when 
 they are flowly heated; but lofe this property, as well 
 as their colour, as foon as they are made red hot. 
 They commonly melt in the fire into a white opaque 
 flag, though fome of them not very eafily. 
 
 Some forts of the zeolites melt eafily, and foam in the 
 fire, fometimes nearly as much as borax, and become a 
 frothy fl:ig, &c. 
 
 A great many of thofe mineral bodies which are im 
 pregnated with iron, as the boles, and fome of the 
 white iron ores, &c. as well as fome of the other iron 
 eres, viz. the bloodftone, are not attracted by the 
 loadftone before they have been thoroughly roafted, &c. 
 
 2. Of fubftances heated with Jinxes. Alter the mine 
 ral bodies have been tried in the fire by themfelves, 
 they ought to be heated with fluxes to difcover if 
 they can be melted or not, and fome other phenomena 
 attending this operation. For this purpofe, three dif 
 ferent 
 
ferent kinds of falts are ufed as fluxes, viz. fal foday 
 borax, and fal fufible microfmicum ; (fee the article 
 Bi.ow-Pipe). 
 
 The fal foda is, however, not much ufed in thefe 
 fmall experiments, its effects upon the charcoal render 
 ing it for the moft pan unfit for it ; becaufe, as foon 
 as the flame begins to act upon it, it melts inftantly, 
 and is almoft wholly abforbed by the charcoal. When 
 this fait is employed to make any experiment, a very 
 little quantity is wanted at once, viz. about the cubical 
 contents of an eighth part of an inch, more or lefs. 
 This is laid upon the charcoal, and the flame blown 
 on it with the blow-pipe ; but as this fait commonly 
 is in form of a powder, it is neceffary to go on very 
 gently, that the force of the flame may not difperfe 
 the minute particles of the fait. As foon as it begins 
 to melt, it runs along on the charcoal, almoft like melc- 
 ed tallow ; and when cold, it is a glafly matter of an 
 opaque dull colour fpread on the coal. The moment 
 it is melted, the matter which is to be tried ought to 
 be put into it, becaufe otherwife the greateft part of 
 the fait will be foaked into the charcoal, and too little 
 of it left for the intended purpofe. The flame ought 
 then to be directed on the matter itfelf ; and if the fait 
 fpreads too much about, leaving the proof almoft alone, 
 it may be brought to it again by blowing the flame on 
 its extremities, and directing it towards the fubject of 
 the experiment. In the aflays made with this fait, it is 
 true, we may find whether the mineral bodies which are 
 melted with it have been diflblved by it or not : but 
 we cannot tell with any certitude whether this is done 
 haftily and with force, or gently and flow ; nor whe 
 ther a lefs or a greater part of the matter has been 
 diflblved : neither can it be well diftinguiihed if the mat 
 ter has imparted any weak tincture to the flag ; be 
 caufe this fait always bubbles upon the charcoal during 
 the experiment, nor is it clear when cool ; fo that 
 
C 10 ] 
 
 fcarcely any colour, except it be a very deep one, can 
 be difcovered, although it may fometimes be coloured 
 by the matter that has been tried. 
 
 The following earths are entirely folnlle in this flux 
 with effervefcence : Agate ; chalcedony ; carnelian ; 
 Turkey ftone f , (cos 'Turcica) ; fluor mineralis -j- ; 
 onyx ; opal ; quartz ; common flint ; ponderous fpar. 
 The following are divifible in it with or without effer 
 vefcence, but not entirely foluble : Amianthus ; af- 
 bertus ; bafaltes ; chryfolite \ ; granate \ ; hornblende ; 
 jafper; marlftone ; mica; the mineral of alum from 
 Tolfa 5 petrofilex ; aluminous flate and roof (late from 
 Helfmgia ; emeralds , fteatites ; common flint ; fchoerl; 
 talc ; trapp ; tripoli ; tourmalin. And the following 
 are neither fufible nor diviiible in it : Diamond j hy 
 acinth ; ruby ; fapphire ; topaz. 
 
 The other two falts, viz. borax and the fa! microcof- 
 muurn, are very well adapted to thefe experiments, be- 
 caufe they may by the flame be brought to a clear un- 
 coloured and tranfparent glafs ; and as they have no 
 attraction to the charcoal, they keep themfelves always 
 upon it in a round globular form. The fal fufible mi- 
 crocofmicum is very fcarce, and perhaps not to be 
 met with in the fhops ; it is made of urine. 
 
 The following earths are foluble in borax, with more 
 or lefs effervefcence : Fluor mineralis f ; marie ; mica f ; 
 the mineral of alum from Tolfa ; aluminous flate, and 
 roof-flate from Helfmgia f ; ponderous fpar ; fchoerl ; 
 talc f ; tourmalin. And the following without effer- 
 vefcence ; Agate ; diamond ; amianthus ; afbeftus ; bi- 
 faltes ; chalcedony ; carnelian ; chryfolite ; cos turcica ; 
 granate ; hyacinth * ; jafper ; lapis ponderofus ; onyx ; 
 opal ; petro-iilex ; quartz * ; ruby ; fapphire ; com 
 mon flint * ; fteaute ; trapp ; trippel, or tripoli ; 
 topaz ; zeolite ; hydrophanes. 
 
 in the microcofmic fait, the following are foluble 
 with more or lefs effervefcence ; Bafaltes f ; turkey 
 
 (lone 
 
C " ] 
 
 ft one ; fluor mineralis -} ; marie ; mica ; the mineral of 
 alum from Tolfa ; fchiftus aluminaris, fchiflus tegula- 
 lis from Mdfmgiaf ; fchoerl ; fpathum ponderofum ; 
 tourmalin f ; lapis ponderofus. And the following 
 without viable effervefcence : Agate ; diamond ; ami 
 anthus ; aibeftus ; chalcedony ; carnelian ; chryfolite ; 
 granate; hyacinth; jafper; onyx || ; opal; petrofi- 
 lex ; quartz II ; ruby ; fapphire ; common flint [| ; 
 emerald ; talc ; topaz ; trapp ; trippel ; zeolite ; horn- 
 blend ; hydrophanes ; lithomarga ; fteatites. 
 
 Calcareous earth, ponderous fpar, gypfum, and 
 other additaments, often uffitl the folution, as well in 
 the microcofmic fait as in borax. To which it is ne- 
 ceflary to add, that in order to obferve the effervef 
 cence properly, the matter added to the flux fhould 
 be in the form of a fmall particle rather than in fine 
 powder ; becaufe in this laft there is always air between 
 the particles, which being afterwards driven off by 
 the heat afford the appearance of a kind of effervef 
 cence (A). 
 
 The quantity of thofe two falts required for an ex 
 periment is almoft the fame as thefa/fod<e ; but as the 
 former are cryftallifed, and consequently include a 
 great deal of water, particularly the borax, their bulk 
 is confiderably reduced when melted, and therefore a 
 little more of them may be taken than the before men 
 tioned quantity. 
 
 Both thofe falts, efpecially the borax, when ex- 
 pofed to the flame of the blow-pipe, bubble very 
 much and foam before they rnelr to a clear glafs, 
 which for the mod part depends on the water they 
 
 (A) In the above lifts, the articles marked f effer- 
 vefce very little ; thofe marked f not. at all ; thofe mark 
 ed * require a larger quantity of the flux and a longer 
 continuance of heat than the reft ; thofe marked || are 
 more difficultly diiTolved than the others. 
 
 contain. 
 
contain. And as this would hinder the aflkyer from 
 making due obfervations on the phenomena of the ex 
 periment, the fait which is to be ufed muft firft be 
 brought to a clear glafs before it can ferve as a flux \ 
 it muft therefore be kept in the fire until it become 
 fo tranfparent that the cracks in the charcoal may be 
 ieen through it. This done, whatfoever is to be tried 
 is put to it, and the fire continued. 
 
 Here it is to be obferved, that for the afTays made 
 with any of thefe two fluxes on mineral bodies, no 
 larger pieces muft be taken than that altogether they 
 may keep a globular form upon the charcoal ; becaufe 
 it may then be better diftinguifhed in what manner 
 the flux acts upon the matter during the experiment. 
 If this be not obferved, the flux, communicating itfelf 
 with every point of the furface of the mineral body, 
 fpreads all over it, and keeps the form of this laft, 
 which commonly is flat, and by that means hinders the 
 operator obferving all the phenomena v hich may hap 
 pen. Befides, the flux being in too fmall a quantity 
 in proportion to the body to be tried, will be too weak 
 to act with all its force upon it. The beft proportion 
 therefore is about a third part of the mineral body to 
 the flux ; and as the quantity of the flux abovemen- 
 tioned makes a globe of a due fize in regard to the 
 greateft heat that is poffible to procure in thefe expe 
 riments, fo the fize of the mineral body muft be a 
 third part lefs here than when it is to be tried in the 
 fire by itfelf. 
 
 Thefalfoct*, as has been already obferved, is not of 
 much ufe in thefe experiments ; nor has it any partU 
 cular qualities in preference to the two laft mentioned 
 falts, except that it diifolves the zeolites eafier than 
 they do. 
 
 The microcofmic fait fhows almoft the fame effects in 
 the fire as the borax, only differing from it in a very few 
 circumftances ; of which one of the principal is, that, 
 when melted with manganefe, it becomes of a crim- 
 
 iba 
 
C 13 ] 
 
 fon hue inftead of a jacinth colour, which borax takes. 
 This fait is, however, for its fcarcity Mill very little in 
 life, borax alone being that which is commonly employ- 
 ed. Whenever a mineral body is melted with any of 
 thefe two laft mentioned falts, in the manner already 
 defcribed, it is eafily feen, Whether it quickly diffolves ; 
 in which cafe an effervefcence arifes, that lafts till the 
 whole be difiblved : Whether the folution be (lowly 
 performed ; in which cafe few and fmall bubbles only 
 rife from the matter : or, Whether it can be diifolved 
 at all ; becaufe if not, it is obferved only to turn round 
 in the flux, without the leaft bubble, and the edges 
 look as fharp as they were before. 
 
 In order farther to illuftrate what has been faid about 
 thefe experiments, we fhall give a few examples of the 
 effects of borax upon the mineral bodies. The calca 
 reous fubftances, and all thofe ftones which contain any 
 thing of lime in their compofition, di/Tolve readily and 
 with effervefcence in the borax. The effervefcence is 
 the more vielent the greater the portion of lime contain 
 ed in the (lone. This caufe, however, is not the only 
 one in the gypfum, becaufe both the constituents of 
 this do readily mix with the borax, and therefore a 
 greater effervefcence arifes in melting gypfum with the 
 borax than lime alone. The Jilicea do not diflblve ; 
 fome few excepted which contain a quantity of iron. 
 The argillacea!) when pure, are not acted upon by the 
 borax : but when they are mixed with fome heteroge 
 neous bodies, they are diffclved, though very flowly ; 
 fuch are, for initance, the ftone-marrow, the common 
 clay, &c. % 
 
 The granatesj zeolites, and frapp, difTolve but flowly. 
 Thej^ttcrj-, ajbeflintf, and micacea 9 diffolve for the moil 
 part very eafily ; and fo forth. Some of thefe bodies 
 melt to a colourlefs tranfparent glafs with the borax ; 
 for inftance, the calcareous fubftances when pure, the 
 fluors, fome of the zeolites, &c. Others tinge the bo 
 rax with a green tranfparent colour, viz. the; granules, 
 
 C trapp, 
 
C 4 ] 
 
 trapp, fome of the argillaceas, andfome of die micaceas 
 and afbeftinse. This green has its origin partly from 
 a fmall portion of iron which the granates particularly 
 contain, and partly from phlogifton. 
 
 Borax can only diffolve a certain quantity of the 
 mineral body proportional to its own. Of the calca 
 reous kind it diflblves a vaft quantity ; but turns at 
 laft, when too much has been added, from a clear 
 tranfparent to a white opaque flag. When the quan 
 tity of the calcareous matter exceeds but little in pro 
 portion, the glafs looks very clear as long as it remains 
 hot : but as foon as it begins to cool, a white half 
 opaque cloud is feen to arife from the bottom, which 
 fpreads over the third, half, or more of the glafs globe, 
 in proportion to the quantity of calcareous matter ; 
 but the glafs or flag is neverthelefs fliining, and of a 
 glaffy texture when broken. If more of this matter be 
 added, the cloud rifes quicker and is more opaque, 
 and fo by degrees till the flag becomes quite milk 
 white. It is then no more of a fhining, but rather 
 dry appearance, on the furface ; is very brittle, and 
 of a grained texture when broken. 
 
 SECT. II. Of Experiments upon Mdals and Ores. 
 WHAT has been hitherto faid relates only to the 
 Jtones and earths : We fhall now proceed to defcribe the 
 manner of examining metals and ores. An exaft know 
 ledge and nicety of procedure are fo much the more 
 neceilary here, as the metals are often fo difguifed in 
 their ores, as to be very difficultly known by their ex 
 ternal appearance, and liable fometimes to be miftaken 
 one .for the other : Some of the cobalt ores, for in- 
 ftance, reiemble much the pyrites arfenicaus ; there are 
 alfo fome iron and lead ores, which are nearly like 
 one another, &c. 
 
 As the ores generally confift of metals mineralifed 
 with fulphur or arfenic, or fometimes both together, 
 they ought firft to be expofed to the fire by them- 
 
 felves, 
 
C 15 ] 
 
 felves, in order not only to determine with which of 
 thefe they are mineralifed, but alfo to fet them free 
 from thole volatile mineralifing bodies : This ferves 
 inftead of calcination, by which they are prepared for 
 further allays. 
 
 Here it mud be repeated, that whenever any me 
 tal or fuiible ore is to be tried, a little concavity mud 
 be made in that place of the charcoal where the mat 
 ter is to be put ; becaufe, as foon as it is melted, it 
 forms itfelf into a globular figure, and might then roll 
 from the charcoal, if its furface was plain ; but when 
 borax is put to it, this inconvenience is not fo much 
 to be feared. 
 
 Whenever an ore is to be tried, a fmall bit beinsj 
 broke off for the purpofe, it is laid upon the charcoal, 
 and the flame blown on it flowly. Then the fulphur 
 or arfenic begins to part from it in form of fmoke : 
 thefe are eafily diftinguilhed from one another by their 
 fmell ; that of fulphur being fufficiently known, and 
 the arfenic Ixnelling like garlick. The flame ought 
 to be blown very gently as long as any fmoke is feen 
 to part from the ore ; but after that, the heat mutl 
 be augmented by degrees, in order to make the cal 
 cination as perfecl: as poflible. If the heat be applied 
 very ftrongly from the beginning upon an ore that 
 contains much fulphur or arfenic, the ore will prefent- 
 ly melt, and yet lofe very little of its mineralifing 
 bodies, by that means rendering the calcination very 
 imperfect. It is, however, impoffible to calcine the 
 ores in this manner to the utmoft perfection, which is 
 eafily feen in the following inftance, viz. in melting 
 down a calcined potter's ore with borax, it will be 
 found to bubble upon the coal, which depends on the 
 fulphur which is ftill left, the vitriolic acid of this 
 uniting with the borax, and caufing this motion. How 
 ever, lead in its metallic form, melted in this manner, 
 bubbles upon the charcoal, if any fulphur remains in 
 it. But as the lead as well as fome of the other metals, 
 C 2 may 
 
[ 16 ] 
 
 may raife bubbles upon the charcoal, although they 
 are quite free from the fulphur, only by the flames 
 being forced too violently on it, thefe phenomena 
 ought not to be confounded with each other. 
 
 The ores being thus calcined, the metals contained 
 in them may be difcovered, either by being melted 
 alone or with fluxes ; when they fhow themfelves ei 
 ther in their pure metallic ftate, or by tinging the flag 
 with a colour peculiar to each of them. In thefe expe 
 riments it is not to be expected that the quantity of 
 metal contained in the ore fhould be exactly deter 
 mined ; this mud be done in larger laboratories. This 
 cannot, however, be looked upon as any defect, fmce 
 it is fufficient for a mineralogift cnly to find out what 
 fort of metal is contained in the ore. There is an 
 other circumftar-ce, which is a more real defect in the 
 miniature laboratories, which is, that fome ores are not 
 at all. capable of oeing tried by fo fmall an apparatus ; 
 for inftance, tne gold ore called pyrites aureus, which 
 confiiis of gold, iron, and fulphur. The greateft quan 
 tity of gold which this ore contains is about one 
 ounce, or one ounce and an half, out of 100 pounds 
 of the ore, the reft being iron and fulphur : and as 
 only a very fmall bit is allowed for thefe experiments, 
 the gold contained therein can hardly be difcerned by. 
 the eye, even if it could be extrafted ; but it goes 
 along with the iron in the flag, this laft metal being 
 in fo large a quantity in proportion to the other, and 
 both of them having an attraction for each other. 
 
 The blendes and black-jacks, which are mineral 
 zinc ores, containing zinc, fulphur, and iron, cannot 
 be tried this way, becaufe they cannot be perfectly 
 calcined, and befides the zinc flies off when the iron 
 fcorifies. Neither can thofe blendes, which contain 
 filver or gold mineralifed with them, be tried in this 
 manner, which is particularly owing to the imperfect 
 calcination. Nor are the quickfilver ores fit for thefe 
 experiments : the volatility of that femimetal mak 
 ing 
 
[ 17 ] 
 
 ing it impoflible to bring it out of the poorer fort 
 of ores : and the rich ores, which fweat out the quick* 
 filver when kept clofe in the hand, not wanting any 
 of thefe allays, c. Thefe ores ought to be affayed 
 in larger quantities, and even with fuch other methods 
 as cannot be applied upon a piece of charcoal. 
 
 Some of the rich filver ores are eafily tried : for in- 
 ftance, minera argentl "u/Yra?, cemmonly called Jilyer- 
 glafs, which confiits only of filver and fulphur. When 
 this ore is expofed to the flame, it melts inftantly, and 
 the fulphur goes away in fume, leaving the filver pure 
 upon the charcoal in a globular form. If this filver 
 fliould happen to be of a dirty appearance, which often 
 is the cafe, then it muft be melted anew with a very 
 little borax ; and after it has been kept in fufion for a 
 minute or two, fo as to be perfectly melted and red- 
 hot, the proof is fuffered to cool : it may then be 
 taken off the coal ; and being laid upon the fteel- 
 plate, the filver is feparated from the flag by one or 
 two ftrokes of the hammer. Here the ufe of the brafs 
 ring is manifeft ; for this ought firft to be placed up 
 on the plate, to hinder the proof from flying offby the 
 violence of the ftroke, which otherwife would happen. 
 The filver is then found inclofed in the flag of a glo 
 bular form, and quite fliining, as if it was polifhed. 
 When a large quantity of filver is contained in a lead 
 ore, viz. in a potter's ore, it can likewife be difcove- 
 red through the ufe of the blow-pipe, of which more 
 will be mentioned hereafter. 
 
 Tin may be melted out of the pure tin ores in its 
 metallic ftate. Some of thefe ores melt very eafily, 
 and yield their metal in quantity, if only expofed to 
 the fire by themfelves : but others are more refractory- ; 
 and as thefe melt very flowly, the tin, which fvveats 
 out in form of very fmall globules, is inftantly burnt 
 to afhes before thefe globules have time to unite in 
 order to compofe a larger globe, which, might be feen 
 C 3 by 
 
[ iS ] 
 
 by the eye, and not fo foon deftroyed by the fire ; it is 
 therefore neceffary to add a little borax to thefe from 
 the beginning, and then to blow the flame violently at 
 the proof. The borax does here preferve the metal 
 from being too foon calcined, and even contributes to 
 the readier collecting of the fmall metalic particles, 
 which foon are feen to form themfelves into a globule 
 of metallic tin at the bottom of the whole mafs, near- 
 erh to the charcoal. As foon as fo much of the me 
 tallic tin is produced as is fufficient to convince the 
 operator of its prefence, the fire ought to be difcon- 
 tinued, though the whole of the ore be not yet melt 
 ed ; becaufe the whole of this kind of ore can be fel- 
 dom or never reduced into metal by means of thefe 
 experiments, a great proportion being always calcined : 
 and if the fire is continued too long, perhaps even the 
 metal already reduced may likewife be burnt to afhes ; 
 for the tin is very foon deprived of its metallic (late by 
 the fire. 
 
 Moft part of the lead ores may be reduced to a 
 metallic (late upon the charcoal. The minera pluml'i 
 calciformeS) which are pure, are eafily melted into lead ; 
 but fuch of them as are mixed with an ochrafcrri, or 
 any kind of earth, as clay, lime, &c. yield very little 
 of lead, and even nothing at all, if the heterogenea are 
 combined in any large quantity : this happens even 
 with the minera pluml'i calciformis arfernco mlxia. Thefe 
 therefore are not to be tried but in larger laboratories. 
 However, every mineral body fufpecled to contain- 
 any metallic fubftance may be tried by the blow-pipe, 
 fo as to give fufficient proofs whether it contain any 
 or not, by its effecls being different from thofe of the 
 ftones or earths, &c. 
 
 The mlncra plumb't miner alt fata leave the lead in a 
 metallic form, if not too large a quantity of iron is 
 mixed with it. For example, when a teflellated or 
 fteel-grained lead ore is expofed to the flame, its ful- 
 
 phur, 
 
C '9 ] 
 
 phur, and even the arfenic if there be any, begins to 
 fume, and the ore itfelf immediately to melt into a 
 globular form ; the reft of the fulphur continues then 
 to fly off, if the flame be blown flowly upon the mafs ; 
 but, on the contrary, very little of the fulphur will go 
 off, if the flame be forced violently on it : in this cafe, 
 it rather happens that the lead itfelf crackles and difli- 
 pates, throwing about very minute metallic particles. 
 The fulphur being driven out as much as poflible, 
 which is known by finding no fulphureous vapour in 
 fmelling at the proof, the whole is fuffered to cool, 
 and then a globule of metallic lead will be left upon 
 the coal. If any iron is contained in the lead-ore, 
 the lead, which is melted out of it, is not of a metal 
 lic {Lining, but rather of a black and uneven, furface : 
 a little borax muft in this cafe be melted with it, and 
 as foon as no bubble is feen to rife any longer from 
 the metal into the borax, the fire muft be difcontinued : 
 when the mafs is grown cold, the iron will be found 
 fcorified with the borax, and the lead left pure and of 
 a fhining colour. 
 
 Borax does not fcorify the lead in thefe fmall expe 
 riments when it is pure : if the flame is forced with a 
 violence on it, a bubbling will enfue, refembling that 
 which is obferved when borax diflblves a body melted 
 with it ; but when the fire ceafes, *the flag will be 
 perfectly clear and tranfparent, and a quantity of very 
 minute particles of lead will be feen fpread about the 
 borax, which have been torn off from the mafs during 
 the bubbling. 
 
 If fuch a lead ore is rich in filver, this laft metal 
 may likewife be difcovered by this experiment ; becaufe 
 as the lead is volatile, ir may be forced off, and the 
 filver remain. To effect this, the lead, which is melt 
 ed out of the ore, muft be kept in conftant fufion with 
 a flow heat, that it may be confumed. This end will 
 be fooner obtained, and the lead part quicker, if du 
 ring the fufioa the wind through the blow-pipe ba 
 
 directed 
 
[ 20 ] 
 
 directed Immediately, though not forcibly, upon the 
 melted mafs itfelf, until it begin to cool; at which 
 time the fire muft be directed on it again. The lead, 
 which is already in a volatilifmg ftate, will by this ar 
 tifice be driven out in form of a fubtil fmoke ; and by 
 thus continuing by turns to melt the mafs, and then 
 to blow off the lead, as has been faid, until no fmoke 
 is any longer perceived, the filver will at laft be ob 
 tained pure. The fame obfervation holds good here 
 alfo, which was made about the gold, that, as none 
 but very little bits of ores can be employed in thefe 
 experiments, it will be difficult to extract the filver 
 out of a poor ore : for fome part of it will fly off with 
 the lead, and what might be left is too fmall to be dif- 
 cerned by the eye. The filver, which by this means 
 is obtained, is eafily diftinguiihed from lead by the 
 following external marks, viz. that it muft be red-hot 
 before it can be melted : it cools fooner than lead : 
 it has a filver colour ; that is to fay, brighter and whi 
 ter than lead : and is harder under the hammer. 
 
 The miners cupri calciformes (at lead fome of them), 
 when not mixed with too much ftone or earth, are ea- 
 fily reduced to copper with any flux ; if the copper is 
 found not to have its natural bright colour, it muft be 
 melted with a little borax, which purifies it. Some of 
 thefe ores do not all difcover their metal if not imme 
 diately melted with borax ; the heterogenea contained 
 in them hindering the fufion before thefe are fcorified 
 by the flux. 
 
 The grey copper ores, which only confift of copper 
 and fulphur, are tried almoft in the fame manner as 
 abovementioned. Being expofed to the flame by 
 themfelves, they will be found inftantly to melt, and 
 part of their fulphur to go off. The copper may af 
 terwards be obtained in two ways : the one, by keep 
 ing the proof in fufion for about a minute, and after 
 wards fuffering it to cool; when it will be found to 
 have a dark and uneven appearance' externally, but 
 
 which 
 
C ] 
 
 which after being broken difcovers the metallic copper 
 of a globular form in its centre, furrounded with a re- 
 gulus, which ftill contains fome fulphur and a portion 
 of the metal: the other, by being melted with borax, 
 which laft way fometimes makes the metal appear 
 fooner. 
 
 The miners cupri pyritacex, containing copper, ful 
 phur, andiron, may be tried with the blow-pipe if 
 they are not too poor. In thefe experiments the ore 
 ought to be calcined, and after that the irofa fcorified. 
 For this purpofe a bit of the ore muft be expofed to 
 a flow flame, that as much of the fulphur as poffible 
 may part from it before it is melted, becaufe the ore 
 commonly melts very foon, and then the fulphur is 
 more difficultly driven off. After being melted, it 
 mull be kept in fufion with a ftrong fire for about a 
 minute, that a great part, of the iron may be calcined ; 
 and after that, fome borax mud be added, which fco- 
 rifies the iron, and turns with it to a black flag. If 
 the ore is very rich, metallic copper will be had in the 
 flag after the fcorifioation. If the ore be of a moderate 
 richnefs, the copper will ftill retain a little fulphur, 
 and fometimes iron: the product will therefore be 
 brittle, and muft with great caution be feparated from 
 the flag, that it may not break into pieces ; and if 
 this producl is afterwards treated in the fame manner 
 as before faid, in fpeaking of the grey copper-ores, 
 the metal will foon be produced. But if the ore is 
 poor, the producl: after the firft fcorification muft be 
 brought into fufion, and afterwards melted with fome 
 frefh borax, in order to calcine and fcorify the remain 
 ing portion of iron ; after which it may be treated as 
 mentioned in the preceding paragraph. The copper 
 will in this laft cafe be found in a very fmall globule. 
 
 The copper is not very e'afily fcorified with this ap 
 paratus, when it is melted together with borax, unlefs 
 it has firft been expofed to the fire by itfelf for a while 
 in order to be calcined. When only a little of this 
 
 metal 
 
C 2* ] 
 
 metal is diffolved, it inftantly tinges the flag of a red- 
 difli brown colour, and moRly opaque ; but as foon as 
 this flag is kept in fuiion for a little while, it becomes 
 quite green and tranfparent : and thus the prefence of 
 the copper may be difccvcred by tlyj colour, when it 
 is concealed in heterogeneous bodies, fo as not to be 
 difcovered by any other experiment. 
 
 If metallic copper is melted with borax by a flow 
 fire, and only for a very little time, the glafs or flag 
 becomes of a fine tranfparent blue or violet colour, in 
 clining more or lefs to the green : but this colour is 
 not properly owing to the copper, but it may rather 
 be to its phlogifton ; becaufe the fame colour is to be 
 had in the fame manner from iron ; and thefe glaffes, 
 which are coloured with either of thofe two metals, 
 foon lofe their colour if expofed to a ftrong fire, in 
 which they become quite clear and colourlefs. Be- 
 fides, if this glafs, tinged blue with the copper, is again 
 melted with more of this metal, it becomes of a good 
 green colour, which for a long time keeps unchanged 
 in the fire. 
 
 The iron ores, when pure, can never be melted 
 per fe, by the means of the blow-pipe alone; nor 
 do they yield their rnetal when melted with fluxes ; 
 becaufe they require too ftrong a heat to be brought 
 into fufion ; and as both the ore and the metal itfelf 
 very foon lofe their phlogifton in the fire, and cannot 
 be fupplied with a fufficient quantity from the char 
 coal, fo likewife they are very foon calcined in the fire. 
 This eafy calcination is alfo the reafon why the fluxes, 
 for inftance borax, readily fcorify this ore, and even 
 the metal itfelf. The iron lofes its phlogifton in the 
 fire fooner than the copper, and is therefore more ea- 
 fily fcorified. 
 
 The iron is, however, difcovered without much dif 
 ficulty, although it were mixed but in a very fmall 
 quantity with heterogeneous bodies. The ore, or 
 thofe bodies which contain any large quantity of the 
 
 metal, 
 
metal, are all attra&ed by the loadftone, fome without: 
 any previous calcination, and others without having 
 being roafted. When a clay is mixed with a little 
 iron, it commonly melts by itfelf in the fire ; but if 
 this metal is contained in a limeftone; it does not pro 
 mote the fufion, but gives the ft one a dark and fome- 
 times a deep black colour, which always is the charac 
 ter of iron. A minerafern calcifornus pura cr^flallifata^ 
 is commonly of a red colour : This being expofed to 
 the flame, becomes quite black ; and is then readily 
 attracted by the loadftone, which it was not before. 
 Eefides thefe figns, the iron difcovers itfelf, by tinging 
 the flag of a green tranfparent colour, inclining to 
 brown, when only a little ot the metal is fcorified ; but 
 as foon as any larger quantity thereof is dillblved in 
 the flag, this becomes firft a blackifli brown, and after 
 wards quite black and opaque. 
 
 Bifmuth is known by its communicating a yellow- 
 ifh brown colour to borax ; and arfenic by its volatili 
 ty and garlick fmell. Antimony, both in form of re- 
 gulus and ore, is wholly volatile in the fire when it is 
 not mixed with any other metal except arfenic ; and is 
 known by its particular fmell, eafier to be diftmguifh- 
 ed when once known than defcribed. When the ore 
 of antimony is melted upon the charcoal, it bubbles 
 conftantly during its volatilifmg. 
 
 Zinc ores are not eafily 'tried upon the coal ; but 
 the regulus of zinc expofed to the fire upon the char 
 coal burns with a beautiful blue flame, and forms it 
 felf almoft inftantly into white flowers, which are the 
 common flowers of zinc. 
 
 Cobalt is particularly remarkable for giving to the 
 glafs a blue colour, which is the zaffre or frnalt. To 
 produce this, a piece of cobalt ore muft be calcined 
 in the fire, and afterwards melted with borax. As 
 foon as the gbfs, during the fufion, from being clear, 
 feems to grow opaque, it is a fign that it is already 
 tinged a little j the fire is thsn to be difcontinued, and 
 
 the 
 
C 24 ] 
 
 the operator mud take hold, with the nippers, of a little 
 of the glafs, whilft yet hot, and draw it out flowly 
 in the beginning, but afterwards very quick, before 
 it cools, whereby a thread of the coloured glafs is 
 procured, more or lefs thick, wherein the colour may 
 eafier be feen than in a globular form. This thread 
 melts eafily, if only put in the flame ol the candle with 
 out the help of the blow-pipe. If this glafs be melted 
 again with more of the cobalt, and kept in fufion 
 for a while, the colour becomes very deep ; and thus 
 the colour may be altered at pleafure. 
 
 When the cobalt ore is pure, or at lead contains 
 but little iron, a cobalt regulus is almoft inftantly 
 produced in the borax during the fufion ; but when 
 it is mixed with a quantity of iron, this lafl metal 
 ought firft to be feparated, which is eafily performed 
 fmce it fcorifies fooner than the cobalt ; therefore, as 
 long as the flag retains any brown or black colour, it 
 muft be feparated, and melted again with frefli borax, 
 until it fliows the blue colour. 
 
 Nickel is very feldom to be had ; and as its ores are 
 feldom free from mixtures of other metals, it is very 
 difficultly tried with the blow-pipe. However, when 
 this femimetal is mixed with iron and cobalt, it is 
 eafily freed from thefe heterogeneous metals, and re 
 duced to a "pure nickel regulus by means cf fcorificati- 
 on with borax, becaufe both the iron and cobalt fooner 
 fcorify than the nickel. The regulus of nickel itfelf is 
 of a green colour when calcined : it requires a pretty 
 ftrong fire before it melts, and tinges the borax with a 
 hyacinth colour. Manganefs gives the fame colour to 
 borax ; but its other qualities are quite different, fo as 
 not to be confounded with the nickel. 
 
 BY means of the foregoing explanations, and thofe 
 given under the article Bu>w-Pipe, any gentleman, 
 who is a lover of this fcience, will be able, in an eafy 
 manner, to amufe himfelf in difcovering the properties 
 
 of 
 
C 25 ] 
 
 ef thofe works of nature, with which the mineral 
 kingdom furnilhes us ; or more ufefully to employ 
 himielf by finding out what forts of ftones, earths, 
 ores, &c. there are on his eftate, and to what econo 
 mical purpofes they may be employed. The fcienti- 
 fic mineralift may, by examining into the properties 
 and effects of the mineral bodies, dilcover the natural 
 relation thefe bodies ftand in to each other, and there 
 by furnifti himfelf with materials for eftabliihing a mi 
 neral fyftem, founded on fuch principles as Nature her- 
 felf has laid down in them ; and this in his own (ludy, 
 without being forced to have recourfe to great laborato 
 ries, crucibles, furnaces, &c. which is attended with 
 much trouble, and is the reafon why fo few can have an 
 opportunity of gratifying their defire of knowledge in 
 this part of natural hiftory. Farther improvements 
 of this apparatus may ftill be made by thofe who 
 choofe to beftow their attention upon it. 
 
 A great number of fluxes might, perhaps, be 
 found out, whofe effects might be different from, 
 thofe already in ufe, whereby more diftincl cha 
 racters of thofe mineral bodies might be difcover- 
 ed, which now either fhow ambiguous ones, or which 
 it is almoft impoffible to try exactly with the blow 
 pipe. Inftead of the Jal fod&, fome other fait might 
 be difcovered better adapted to thefe experiments. 
 But it is very neceffary not to make ufe of any other 
 fluxes on the charcoal than fuch as have no attrac 
 tion to it: if they, at the fame time, be clear and 
 tranfparent, when melted, as the borax and the fal 
 fiijibile mlcrocofmicum, it is ftill better : however, the 
 tranfparency and opacity are of no great confequence, 
 if a fubftance be affayed only in order to difcover its 
 fufibility, without any attention to its colour ; ia 
 which cafe, fome metallic flag, perhaps, might be ufe- 
 ful. 
 
 When fuch ores are to be reduced whofe metals 
 
 -are very eaiily calcined., as tin, zinc, &c. it might 
 
 1) perhaps 
 
- C 26 ] 
 
 perhaps be of fervice to add fome phlogiftic body, 
 iuch as hard refm, fmce the charcoal cannot afford 
 enough of it in the open fire of thefe afiays. The 
 manner of melting the volatile metals out of their 
 oies per defcenfum might alfo, perhaps, be imitated : 
 for inftance, a hole might be made in the charcoal, 
 wide above and very narrow at the bottom ; a little 
 piece of the ore being then laid at the upper end 
 of the hole, and covered with fome very fmall pieces 
 of the charcoal, the flame muft be directed on the top : 
 the metal might, perhaps, by this method, run into the 
 hole below, concealed from the violence of the fire, 
 particularly if the ore is very fufible, &c. 
 
 The ufe of the apparatus above referred to, and 
 which may be called a pocket laboratory (as the whole 
 admits of being eaiily packed into a fmall cafe), is 
 chiefly calculated for a travelling mineralift. But a 
 perfon who always refides at one and the fame place, 
 may by fome alteration make it more commodious 
 to himfelf, and avoid the trouble of blowing with the 
 mouth. For this purpofe he may have the blow-pipe 
 go through a hole in a table, and fixed underneath 
 to a fmall pair of bellows with double bottoms, fuch 
 sis fome of the glafs-blowers ufe, and then nothing 
 more is required than to move the bellows with the 
 feet during the experiment ; but in this cafe a lamp 
 may be ufed inftead of a candle. This method would 
 be attended with a ftill greater advantage, if thsre 
 were many fuch parts as c, fig. 13. the openings of 
 which were of different dimenfions : thofe parts might 
 by means of a fcrew be fattened to the main body of 
 the blow-pipe, and taken away at pleafure. The ad 
 vantage of having thefe nozzles of different capacities 
 at their ends, would be that of exciting a ftronger 
 or weaker heat as occafion might require. It would 
 only be neceffary to obferve, that in proportion as the 
 opening or noz/.le of the pipe is enlarged, the quan 
 tity of the flame muft be augmented bj a thicker 
 
 wick 
 
wick in the lamp, and the force of blowing encreafed 
 by means of weights laid on the bellows ; a much in- 
 tenfer heat would thus be produced by a pipe of a 
 considerable opening .at the end, by which the expe 
 riments muft undoubtedly be carried farther than the 
 common blow-pipe. 
 
 A traveller, who has feldom an opportunity of 
 carrying many things along with him, may very well 
 be contented with this laboratory and its apparatus, 
 which are fufficient for mod part of fuch experiments 
 as can be made on a journey. There are, however, 
 other things very ufeful to have at hand on a journey, 
 which ought to make a feparate part of a portable la 
 boratory, if the manner of travelling does not oppofe 
 it : this ccnfifts of a little box including the different 
 acids, and one or two matrafles, in order to try the 
 mineral bodies in liquid menftrua if required. 
 
 Thefe acids are, the acid of nitre, of vitriol, and 
 of common fait. Moft of the ftones and earths are 
 attacked, at leaft in fome degree, by the acids ; but 
 the calcareous are the eafieft of all to be diiTolved by 
 them, which is accounted for by their calcareous pro 
 perties. The acid of nitre is that which is moft ufed 
 in thefe experiments ; it diffolves the limeftone, when 
 pure, perfectly, with a violent effervefcence, and the 
 iblution becomes clear : when the limeftone enters in 
 to fome other body, it is neverthelefs difcovered by 
 this acid, through a greater or lefs effervefcence in 
 proportion to the quantity of the calcareous particles, 
 unlefs there are fo few as to be almoft concealed from 
 the acid by the heterogeneous ones. In this manner 
 a calcareous body, which fora-times nearly refembles 
 a fiiiceous or argillaceous one, may be known from 
 thsfe latter, without the help of the blow-pipe, only by 
 pouring one or two drops of this acid upon the fiuV 
 jecl: ; which is very convenient when there is no oppor 
 tunity nor time of ufmg this inftrument. 
 
 D 3. The: 
 
[ 28 ] 
 
 The gypfa, which confift of lime and the vitriolic 
 acid, are not in the leaft attacked by the acid of 
 nitre, if they contain a fufficient quantity of their own 
 acid ; becaufe the vitriolic acid has a ftronger attrac 
 tion, to the lime than the acid of nitre : but if the 
 calcareous fubflance is not perfectly faturated with 
 the acid of vitriol, then an effervefcence arifes with the 
 acid of nitre, more or lefs in proportion to the want of 
 the vitriolic acid. Thefe circumftances are often very 
 effential in diftinguifliing the calcarea and gypfa from 
 one another. 
 
 The acid of nitre is likewife necetfary in trying the 
 zeolites, of which fome fpecies have the fmgular ef 
 fect to diilblve with efrervefcence in the abovemention- 
 ed acid ; and within a quarter of an hour, or even 
 fometimes not until feveral hours after, to change the 
 whole folution into a clear jelly, of fo firm a confidence, 
 that the glafs wherein it is contained may be reversed 
 without its falling out. 
 
 If any mineral body is tried in this menftruum, and 
 only a fmall quantity is fufpected to be difiblved, 
 though it was impoffible to diftinguifti it with the eye 
 during the folution, it can be eafily difcovered by 
 adding to it ad faiuntatem a clear folution of the al 
 kali, when the diiTolved part will be precipitated, and 
 fall to the bottom. For this purpofe the falfodce may 
 b e very ufeful. 
 
 The acid of nitre will fuffice for making experiments 
 upon ftones and earths ; but if the experiments are to 
 be extended to the metals, the other two acids are alfo 
 necefTary. 
 
 Another inftrument is likewife necefiary to a 
 complete Pocket Laboratory, viz. a waihing -trough 
 (fig. 21.), in which the mineral bodies, and particu 
 larly the ores, may be feparated from each other, and 
 from the adherent rock, by means of water. This 
 trough is very common in laboratories, and is ufed of 
 different fizes ; but here only one is required of a 
 
 moderate 
 
t *9 3 
 
 moderate fize, fucli as 12 inches and a half long, three 
 inches broad at the one end and one inch and a half 
 at the other end, floping down from the fides and 
 the broad end to the bottom, where it is three quar 
 ters of an inch deep. It may, however, be made of 
 much fmaller dimenfions. It is commonly made of 
 wood, which ought to be chofen fmooth, hard, and 
 compact, wherein are no pores in which the minute 
 grains of the pounded matter may conceal themfelves. 
 It is to be obferved, that if any fuch matter is to be 
 wafhed as is fufpected to contain feme native metal, 
 iuch as filver or gold, a trough fhould be procured for 
 this purpofe of a very ihallow Mope ; becaufe the mi 
 nute particles of the native metal have then more pow 
 er to affemble together at the broad end, and feparate 
 from the other matter. 
 
 The management of this trough, or the manner of 
 wafhing* eonfifts in this : That when the matter is 
 mixed with about three or four times its quantity of 
 water in the trough, this is kept very loofe between 
 two fingers of the left hand, and fome light ftrokes 
 given on its broad end with the right, that it may 
 move backwards and forwards ; by which means the 
 heavieft particles affemble at the broad and lower end,, 
 from which the lighter ones are to be feparated by 
 inclining the trough and pouring a little water on 
 them. By repeating this prccefs, all fuch particles 
 as are of the fame gravity may be collected together, 
 and feparated from thofe of different gravity, provided 
 they were before equally pounded : though fuch as 
 are of a clayey nature, are often very difficult to fe 
 parate from the reft, which, however, is of no great 
 confequcnce to a Ikilful and experienced wafher. The 
 walliing procefs is very neceiTary, as there are often 
 rich ores, and even native metals, found concealed in 
 earths and fand in fuch minute particles as not to be 
 difcovered by any other means. 
 
 D 3 SECT. III. 
 
E 30 3 
 
 SECT. III. Defcription of an Improved Portable Labora 
 tory for a/faying Minerals. 
 
 THE chief pieces and implements of the portable 
 laboratories are reprefented in Plate XCIX. at B Low- 
 Pipe, and in Plate CCCXIII. annexed to the prefent 
 article. 
 
 I. The firft contains thofe belonging to the Dry Labo 
 ratory, fo called on account of its containing whatever 
 is required to try all kinds of foffils in the dry way by 
 fire, without any of the humid menftruums. They 
 are made to pack in a box of the fize of an octavo 
 book, lined with green velvet, and covered with black 
 fifh-fkin ; the infide divided into different compart 
 ments, fuited to the fize, form, and number of the 
 implements it is to contain. Of thefe the principal 
 are defcribed under BLOW- Pipe. We muft here, how 
 ever, add the following remarks and alterations of that 
 inftrument by Mr Magellan. 
 
 D and Q__ (fig, 13.) are the two pieces that form 
 the blow-pipe, which is here reprefented entire. This 
 very ufeful inftrument has been considerably improved 
 of late in England. The mouth-piece a a is made of 
 ivory, to avoid the difagreeable fenfation of having a 
 piece of metal a long time between the teeth and lips,, 
 which, if not of filver or gold, may be very noxious 
 to the operator ; a circumitance that has been hardly 
 noticed before. 
 
 i. If the mouth-piece a a be made of a round form, 
 it cannot be held for any length of time between the 
 teeth and lips, to blow through it, without draining 
 the mufcles of the mouth, which produces a painful 
 fenfation. It muft, therefore, have fuch an external 
 figure, as to adapt itfe/f accurately to the lateral 
 angles of the lips, having a flattifh oval form external 
 ly, with two oppofite corners to fit thofe internal an-j 
 gles of the mouth, when it is held between the lips, as 
 may be feen in that reprefented in the figure. 
 
 2. The_ 
 
C 3' 1 
 
 2. The fmall globe Ib is hollow, for receiving the 
 moifture of the breath ; and muft be compofed of two 
 hemiipheres, exadtly fcrewing into one another in bb ; 
 the male-fcrew.is to be in the lower part, and foldered 
 on the crooked part Q^of the tube Q_P> at fuch a 
 diftance, that the infide end of the crooked tube be 
 even with the edge of the hemifphere, as reprefented 
 by the pointed lines in the figure. But the upper he 
 mifphere is to be foldered at the end of the ftraight tube 
 D. By thefe means, the moifture arifmg from the 
 breath falls into the hollow of the lower hemifphere, 
 where it is colle&ed round the upper infide end of the 
 crooked part Q^of the blow-pipe, without being apt to 
 fall into it. 
 
 3. The fmall nozzles, or hollow conical tubes, ad- 
 vifed by MelTrs Engeftrom, Bergman, and others, are 
 wrong in the principle ; becaufe the wind that palfes 
 from the mouth through fuch long cones lofes its ve 
 locity by the lateral fridion, as happens in hydraulic 
 fpouts ; which, when formed in this manner, do never 
 throw the fluid fo far as when the fluid pafles through 
 a hole of the fame diameter, made in a thin plate of a 
 little metallic cap that fcrews at the end of the large 
 pipe. It is on this account that the little cap c is em 
 ployed, having a fmall hole in the thin plate, which 
 ferves as a cover to it ; and there are feveral of thefe 
 little caps, with holes of fmaller and larger fizes, to 
 be changed and applied whenever a flame is required 
 to be more or lefs ftrong. 
 
 4. Another convenience of thefe little caps is, that 
 even in cafe any moifture fhould efcape falling into the 
 hemifphere bb, and pafs along with the wind through 
 the crooked pipe Q^, it never can arrive at nor obftruct 
 the little hole ot the cap c, there being room enough un 
 der the hole in the infide, where this moifture muft be 
 flopped till it is cleaned and wiped out. 
 
 The ftream of air that is impelled by the blow 
 pipe (as feen in fig. 3.) upon the flame, muft be ccn- 
 
 ftant 
 
ftant and even, and muft laft as long as the experi 
 ment continues to require it. This labour will fatigue 
 the lungs, unlefs an equable and uninterrupted infpi- 
 ration can at the fame time be continued. To fucceed 
 in this operation without inconvenience, fome labour 
 and practice are neceflary, as already explained under 
 the detached article. 
 
 Every affay ought always to begin by the exterior 
 flame, which muft be firft directed upon the mafs under 
 examination ; and, when its efficacy is well known, then 
 the interior blue flame is to be employed. 
 
 After the ore is roafted, it is to be rounded up 
 on the fteel plate by the hammer ; the particles being 
 prevented from being diflipated by the ring H (fig. 9, 
 Plate XCIX.), within which the pieces to be broken 
 are to be put. 
 
 Among the apparatus, befide the particulars al 
 ready mentioned, three phials are necerTary, contain 
 ing the required fluxes, viz. the borax, the fal fodte, 
 and fcl fufil tie microcofmicum. Other ufeful particulars 
 are, A fmall link of hard fteel, to try the hardnefs or 
 foftnefs of mineral fubftances, and alfo to ftrike fire 
 for lighting the candle when required : A piece of 
 black flint, toferve as a touch-ftone ; (for being rubbed 
 with any metal, if it be gold the marks will not be 
 corroded by aqua fortis) ; and alfo to ftrike fire, when 
 necerTary, with the link of fteel : An artificial load- 
 ftone, properly armed with iron, for the better pre- 
 fervation of its attractive power ; (it ferves to difcover 
 the ferrugineous particles of any ore after it has been 
 roafted and powdered:) A triple magnifier, which, 
 differently combined, produces feven magnifying 
 powers, the better to diftinguifh the ftructure and me 
 tallic parts of ores, and the minute particles of native 
 gold, whenever they contain that metal : A file, to try 
 the hardnefs of ftones and cryftals, &c. : Some pieces 
 of dry agaric or tinder, and fmall bits or fplinters of 
 wood tipped with brimftone, to ferve as matches for 
 
 lighting 
 
C 33 3 
 
 lighting the candle ; and various other little articles of 
 ule in thefe experiments. 
 
 II. For performing experiments in the Humid IVay, 
 the chief additional articles (and which muft be kept 
 in a feparate cafe) confift of a collection of phials, 
 containing the principal acids, tefts, precipitants, and 
 re-agents, both for examining mineral bodies by the 
 humid way, and for analyiing the various kinds of mi 
 neral waters. Thofe with acids and corrofive folutions 
 have not only ground ftoples, but alfo an external cap 
 to each, ground over the ftople, and fecured down 
 ward by a bit of wax between both, in order to con 
 fine the corrofive and volatile fluids within. But thofe 
 which contain mild fluid liquors have not fuch external 
 caps : and thofe with dry inoffenfive fubftances are 
 only flopped with cork. Befides thefe phials, there 
 are two fmaller cylindrical ones,which ferve to exhi 
 bit the changes of colour produced by fome of the re 
 agents in thofe analytical aflays. There are alfo two 
 or three fmall matrafles, to hold the fubftances with 
 their folvents over the fire; a fmall glafs funnel, for 
 pouring the fluids ; a fmall porcelain mortar, with its 
 peftle ; one or two crucibles of the fame fubftance ; a 
 imail wooden trough to wafti the ground ores ; fome 
 glafs flicks to flir up the fluid mixtures ; and, finally, 
 pieces of paper tinged red, yellow, and .blue, by the 
 tinctures of Fernambuc wood (commonly called Brafil 
 wood), turmeric, and litmus, thickened with a little 
 March. 
 
 The following lift contains the names of the various 
 fluid tefts and re-agents that are neceffary for thefe af- 
 fays. But the whole number being too large to be all 
 contained in a portable cafe, every one may give the 
 preference to thofe he likes beft. 
 i. Concentrated vitriolic 2. Nitrous acid, purified 
 
 acid, whofe fpecific by the nitrous folution 
 
 gravity may be expref- of filver. 
 
 fed in the outfide. 
 
 s. Con- 
 
[ 34 ] 
 
 3- Concentrated marine 4. Marine acid dephlo- 
 
 acid, with its fpecifk giilicated. 
 
 gravity. 
 5. Aqua regia for gold, 6. Aqua regia for platina 
 
 viz. 2 nit. and i ma- viz. half marine and 
 
 rine, half nitrous acid. 
 
 7. Nitrous folntion of fil- 8. Nitrous folution of mer- 
 
 ver. cury, made in the cold. 
 
 9= Muriatic folution of 10. Nitrous folution of 
 
 barytes. lime. 
 
 n. Muriatic folution of 12. Mercury in its metal- 
 
 lime. lie ftate. 
 
 13. Corrofive fublimate 14. White arfenic. 
 
 of mercury. 
 15. Nitrous folution of 16. Nitrous folution of 
 
 filver. copper. 
 
 17. Acid of fugar. 18. Liquor probatorius 
 
 vim. 
 19. Hepar fulphuris. 20. Oil of tartar per dell- 
 
 21. Salt of tartar. 22. Cauftic vegetable al 
 
 kali. 
 
 23, Pearl-afhes. 24. Soap-makers ley. 
 
 25. Common fait. 26. Vitriolated argilla 
 
 (alum.) 
 27 Vitriol of iron (cop- 28. Nitrous folution of fil- 
 
 peras) ver. 
 
 29. Acetous folution of 30. Acetous folution of 
 
 lead. barytes. 
 
 31. Phlogifticated alkali 32. Lime-Water. 
 
 by the Pruflian blue. 
 
 33. Lime-water phlogifti- 34. Cauftic volatile alkali. 
 cated by the Pruffian 
 blue. 
 35. Mild volatile alkali 36. Reclified fpirit (aU 
 
 (dry.) cohol. 
 
 37. uEther. 38. Spirituous tinclure 
 
 of galls. 
 
 The 
 
C 35 ] 
 
 The following tefts are very fit alfu for thefe allays, 
 viz. 39, Spirituous folutions of foap ; 40* Syrup of 
 violets; 41 Tincture of litmus; 42. Tincture of Brafil 
 wood ; 43. Tincture of turmeric ; 44. Oil of olives ; 
 45. Oil of linfeed : 46. Oil of turpeatine ; 47. Effential 
 fait of wild -for rel ; 48. Hepar fulphuris : 49. Sugar of 
 lead ; 50. Solution of alum. 
 
 The method of applying the above tefts of acids 
 and re-agents may be feen in Bergman's treatifes of 
 the Analyfis of Waters, and of Allaying by the Hu 
 mid Way ; in Kirwan's Elements of Mineralogy ; in 
 the Elements of Chemiftry of Dijon ; in 'the Memoirs 
 of the fame Academy ; in Fourcroy's Lectures of Che- 
 mi ftry, &c. 
 
 III. The Lamp-furnace Laboratory, for experiments 
 both by the humid a.\\& the dry way, is a very curious and 
 uieful, though fmall apparatus. It is an improvement 
 of that which was contrived by M. de Morveau, in 
 confequence of the information he received from his 
 friend the prefident de Virly, who faw at Upfal how 
 advantageoufly the late eminent profeffor Bergman 
 availed himfelf of this convenience for many analytical 
 procefles in miniature, by the ufe of very fmall giafs 
 veffels about one inch diameter, and other implements 
 of proportional fixe, for performing various chemical 
 operations. (See the Dijon Memoirs for 1783. Part i 
 p. 171.) 
 
 There can be no doubt but that whenever thefe 
 proceiles are properly conducted, though in miniature, 
 the lamp-furnace will prove amply fufficient to per 
 form in a few minutes, and with very little expence, 
 the various folutions, digeftions, and diftillations, 
 which otherwife would require large vefTels, (tills, re 
 torts, reverberatory furnaces, c. to afcertain the com 
 ponent parts of natural bodies ; though it is not always 
 fufficient to afcertain their refpective quantities. In 
 this laft cafe, operations muft be performed in great 
 laboratories, and on a large fcule, at a conflderable 
 
 expence 
 
C 36 ] 
 
 expence. But the fubftances are fometimes too valu 
 able ; as, for inflance, when precious ftones are exami 
 ned ; and of courfe the lafl way never can be attemp 
 ted in fuch cafes. 
 
 Thefe fmall procefles have likewife another advan* 
 tage before noticed, which cannot be obtained in 
 works at large. It confifts in one's being able to ob- 
 ferve the gradual progrefs of each operation ; of eafily 
 retarding or urging it, as it may require : and of af- 
 certaining at pleafure each ftep of every experiment, 
 together with the phenomena attending the fame. 
 
 The lamp-furnace is mounted in a fmall parallelo 
 gram of mahogany, about fix inches long and four 
 wide, marked fig. 5. This is kept fteady over the 
 edge of a common table, by means of the metallic 
 clamp auiu, which is fattened by the fcrew x. The 
 pillar rs is fcrewed in a vertical pofition on the plate s, 
 being about ten inches high : the other is fcrewed to 
 the oppofite corner, marked/^, and is only 7^ inches 
 long ; both are compofed of two halves, that fcrew at 
 fly to be eafily packed up with all the implements in 
 a cafe covered with black fifh fkin, and lined with 
 green velvet, like the other laboratory already de- 
 icribed. 
 
 The lamp /, fig. 3. is fupported on the plate /, 
 which has a ring / that runs in the column pk, and 
 may be fixed by its fcrew / at the required height.- 
 This lamp has three fmall pipes of different fizes, to 
 receive as many wicks of different thicknefs, and to 
 be filled with fpirit of wine. By a fimilar method > 
 a piece of charcoal is mounted and fupported by the 
 pliers or little forceps fcrewed to the arm ac 9 fig. i. 
 which has all the motions requifite for being fixed by 
 means of proper fcrews, at a proper di fiance from 
 the flame of the wick h. The blow-pipe, fig. 4. is, 
 by a fimilar mechanifm, mounted on the fmaller co 
 lumn pq, at fuch adiftanceasto blow the flame/?*' to 
 the piece of ore m 9 which is upon the charcoal gf. 
 
 4 Every 
 
[ 37 ] 
 
 Every thing being difpofed in this manner, the ope*, 
 rator blows through the mouth-piece of the blow 
 pipe, fig. 4. and remains with his hands free to make 
 the changes and alterations he may think proper. 
 
 JV. B. The large round cavity e in the middle of the 
 parallelogram, fig. 5. is to receive the lamp /, fig. 3* 
 when all the implements are packed up in their cafe of 
 black fifh-fkin : and the cover of the lamp is reprefented 
 by fig. ^12.] 
 
 But if the operator has the double bellows, fig. 14. 
 and 15. he fixes them, at a due diftance, to the fame 
 table by the brafs clamp y. He then unfcrews the 
 blow-pipe at % z, joins the month m of the flexible 
 tube of the hemifphere z z, paffing each orifice thro* 
 the leather tube fig. 1 1 , and tying both ends with a 
 waxed thin pack-thread. If he works with his foot 
 on the pedal, the ftring of which is feen hanging from 
 the end of the bellows, fig. 15. (and is always up, on 
 account of the weight <?), then the air is abforbed by 
 the bellows fig. 15. from whence it is propelled by 
 the motion of the foot on the pedal to the bellows, 
 fig. 14. whofe conftant weight r drives it out through 
 the flexible pipe, fig, 10. it of courfe enters the 
 curved part z/ of the blow-pipe, and drives the flame 
 on the piece m of the ore, that is to be examined upon 
 the charcoal. 
 
 {N. B. i. This double bellows is packed up by it* 
 felf in a mahogany cafe, about 9 inches long. 6 ~ wide, 
 and about 3^ deep, outfide meafure. 2. The laft 
 blowing bellows, fig. 1 4, has an infide valve^ which 
 opens when the upper furface of it is at its greatelt 
 height ; in order to let the fuperfluous air efcape out, 
 as it would ctherwife iflue with great velocity out o 
 the tube, fig, 1 1. and fpoil the operation.] 
 
 If the operator choofes to apply the vital or dephlo- 
 
 gifticated air in his procefs, let him fill the glafs-jar h 9 
 
 fig. 17. with this air; and put it within the tube 
 
 marked by abzs, filled with water, fattening the neck 
 
 E of 
 
C 3 ] 
 
 of the jar within by a crofs-board /, which has a 
 hole in it for thatpurpofe : then introducing the two 
 ends of the flexible hollow tube, fig. 16. both to the 
 mouth of the jar and to the hole of the bellows fig. 15. 
 he opens the hole m of the jar, that was flopped 
 with the ftopple n ; the column of the water palfes in 
 through w, and forces up the vital air, which enters 
 the bellows, and of courfe, by the alternate motion 
 of the pedal, paiTes through the end of the blow-pipe, 
 to urge the flame upon the piece of ore m, fig. 2. on 
 the charcoal g. But the dephlogifticated air may be 
 jilib received at the fame time that it is produced, by 
 tying the pipe,, fig. 16. to the mouth of an earthen 
 retort, or even of a glafs retort well-coated, accord 
 ing to the method of Mr Willis, defcribed in the 
 Tranfaclions of the Society of Arts, Vol. V. p. 96. 
 This laft confifts in diflblving two ounces of borax in 
 a. pint of boiling water, and adding to the folution as 
 much flacked lime as is neeeflaiyto form a thin pafte. 
 This glafs retort is to be covered all over with it, by 
 means of a painter's brufli, and then fuffered to dry. 
 It -mutt then be covered w T ith a thin pafte made of 
 linfeed oil and Hacked lime, except the necfc that en 
 ters into the receiver. In two or three days it will 
 dry of itfelf ; and the retort will then bear the great- 
 eft fire without cracking. Two ounces of good nitre 
 being urged in the retort, by a good fire on a chafing - 
 difh, will afford about 700 or 800 ounce-meafures of 
 dephlogifticated air. 
 
 To make, any other kind of chemical afTays, the 
 ^forceps of fig. 2. which fupports the charcoal, is ta 
 ken off by unfcrewing thefcrew^; the blow-pipe is 
 alfo taken off, by loofening the fcrew n ; the hoop fig. 
 7. is put in its place, where the metallic bafin of fig. 19, 
 is put filled with fand ; the piece of fig. 8, is fet on the 
 other pillar r,r, fig. i. to hold the matrafs, fig. 18. up 
 right, or the receiver fig. 20, &c. 
 
 Jn 
 
[ 39 ] 
 
 In the fame manner, the retort, fig. 9. may be pat 
 in the fand-bath inftead of the matrafs, with its re 
 ceiver fig. 20. which may bs fupported on a bit of 
 cork or wood, hollowed to its figure, and held by the 
 pliers, inftead of the charcoal fig. 2. 
 
 But if the operation is to be made in the naked 
 fire, the neck of the retort, fig. 9. being luted to the 
 receiver, or balloon, fig. 20. may be Jianged by a little 
 chain with its ring over the flame, being fufpended 
 from the piece of fig. 7. or 8. fcrewed to either of the 
 pillars as may be molt convenient. Otherwife the 
 receiver, fig. 20. may be fupported by the round hoop 
 of brafs, fig. 8. or 7. fcrewed at a proper height to ths 
 pillar, fig. i. tying round it fome packthread to de 
 fend the glafs from the contact with the metallic fup- 
 port. 
 
 The piece of fig. 6. may bs fcrewed by its collar 
 and {crew efto any of the pillars ; carrying with it the 
 retort and us receiver, at proper did.mces, higher or 
 nearer to the lamp according as the iUme is more or 
 lefs violent. 
 
 It eaiily may be conceived, that thefe implements 
 afford all forts of conveniences for making any kind 
 of fmall operations and affays in miniature, provided 
 the operator pays a proper attention to the difpofition 
 requifite for each procefs or operation. 
 
 Every glafs retort, receiver, matrafs, bafon, fmall 
 funnels, &c. are made by the lamp-workers, thac 
 blow beads, thermometers, and other fmall glafs in- 
 ftruments. 
 
 It is directed that the lamp , fig. 3. be filled 
 with fpirit of wine, becaufe it gives no difagreeable 
 fmell, and does not produce any fuliginous and difa 
 greeable cruft on the vefiels as oil does : moreover, 
 the fpirit gives a dry flame, without fmoke, and 
 ftronger than oil ; belides the fpots and difagreeable 
 confequences this lad caufes, if fplit, &c. M. de 
 Morveau adds, that the expence of fpirit is quite in~ 
 E 2 confide- 
 
[ 4 ] 
 
 eonfiderable ; and that he performed in eight or ten 
 minutes, with this apparatus, various diffolutions, eva 
 porations, and other proceffes, which otherwife would 
 have taken more than three hours, with the expeVice 
 only of two or three halfpence for the fpirit of wine, 
 whilft the fuel of charcoal would have coil near ten or 
 eleven pence. 
 
 4 But a very important circumftance is, as Morveau 
 obferves likewife, that many philofophers do not ap 
 ply themfelves to chemical operations, for want of op 
 portunity of having a laboratory to perform them : it 
 requiring a proper room, and fuitable expences of 
 many large furnaces, retorts, crucibles and numerous 
 other implements, c. whilft thefe miniature laborato 
 ries may in great meafure afford the fame advantages ; 
 at leaft to that degree of fatisfadion fufficient to afcer- 
 tain tli contents and products of any fubftance that 
 is fubjected to trial : for with this fimple apparatus 
 a man of fome abilities may, without any embaraff- 
 ment, in a Very fhort time, and with little expence, 
 perform fuch diftillations as require a reverberatcry fur 
 nace ; all forts of proceffes, digeftions, and evapora 
 tions, which require a regular fand heat ; he may 
 vary his experiments or trials, and multiply them to 
 a great number of various performances, draw up his 
 conclufions, and reafon upon them, without lofs of 
 time, without the hinderance of long preparations to 
 work at large. And even when fuch large works are 
 to be performed, he may obferve beforehand various 
 phenomena of fome fubftances, which being known in 
 time, would otherwife impede the proceffes at large, 
 or make them fail abfolutely ; and all this without the 
 rifk of a eonfiderable lofs, and without expofing him- 
 felf to a great fare, Sec, 
 
 PART II. 
 
PART II. 
 
 ARRANGEMENT* OF MINERAL 
 BODIES. 
 
 i. HE bodies belonging to the mineral kingdom are- 
 divided into four different clafTes, viz. 
 
 1. Earths -f , or thofe fubftances which are not duc 
 tile, are moftly indiifoluble in water or oil, and 
 preferve their conftitution in a ftrong heat. 
 
 2. Salts : thefe diffolve in water, and give it a tafte ; 
 and when the quantity of water required to keep 
 them in difTolution is evaporated, they concrete 
 again into folid and angular bodies. 
 
 3. Iiiflammallesy which can be diflblved in oils, but 
 not in water, and are inflammable. 
 
 4. Metals, the heavieft of all bodies ; fome of which 
 are malleable, and fome can be decompounded. 
 
 Here, however, it muft be, obferved, that thefe claf- 
 
 fes are unavoidably blended one with another; and 
 
 - , E 3 therefore 
 
 * According to the fyftem of Cronfledt -, altered^*, 
 augmented, and improved from the Obfervations of } 
 ther Mineralogies. / 
 
 f By earths, the author (Mr Cronftedt) does not 
 mean (ftriclly fpeaking) only earths, but includes un 
 der that title all the kinds of it ones or foilils not 
 faline, or metallic. 
 
C 4* ] 
 
 therefore fome exceptions muft be allowed in every 
 one of them : for inllance, in the firft clafs, the calca 
 reous earth is in fome meafure difibluble in water, and 
 pipe-clay with fome others diminifh fomewhat in their 
 bulk when kept for a long time in a calcining heat. 
 In the third clafs, the calx of arfenic has nearly the 
 fame properties as falts ; and there is no poffible defi 
 nition of fait that can exclude the arfenic, though at 
 the fame time it is impoiTible to arrange it elfewhere 
 than among the femimetals. In the fourth clafs it is 
 to be obferved, that the metals and femimetals, per 
 fect or imperfect, have not the fame qualities common 
 to them all ; becaufe fome of them may.be calcined,, 
 or deprived of their phlogifton, in the fame degree of 
 fire in which others are not in the lead changed, un- 
 kfs- particular artifices or procefles are made ufe of: 
 feme of them alfo may be made malleable, while others 
 are by no means to be rendered fo. That the convex 
 farface metals take after being melted, is a quality net 
 Particularly belonging to them, becaufe every thing 
 that is perfectly fluid in the fire, and has no attraction 
 to the veffel in which it is kept, or to any added mat 
 ter, takes the fame figure ; as we find borax, fat fufi- 
 lile microcojmicum^ and others do, when melted upon 
 a piece of charcoal : therefore, with regard to all that 
 has been faid, it is hardly worth while to invent fuch 
 definitions as fhall include feveral fpecies at once ; we 
 ought rather to be content with perfectly knowing; 
 them feparately. 
 
 CLASS I. EARTHS. 
 
 EARTHS, are thofe mineral bodies, not 'ductile, for 
 the mo ft part not diifoluble in water or oils, and which 
 preferve th&'r conftitution ia a flrong heat. 
 
 \ Thefe 
 
E 43 3 
 
 Thefe bodies are here arranged accordiftg to their 
 condiment parts, fo far as hitherto difcovered ; and are 
 divided into five orders. See the article EARTH. 
 
 Order I. CALCAREOUS EARTHS *. 
 
 THE properties of thefe are as follow : 
 i. Friability and falling into a fine white powdeY 
 after calcination. 
 
 2. Par- 
 
 * Calcareous earth is moil commonly found in tha 
 form of lime-ftone ; hard, compact, and of various co 
 lours ; under which general name may be compre 
 hended all the different kinds of marbles. Near Bath 
 in England is found a kind of grey ftone, rather foft 
 than hard. This contains calcareous earth in a mild 
 ftate, and likewife fome in a ftate of caufticity : hence, 
 when newly dug out of the earth, it will dilfolve ful- 
 phur, or make lime-water without any calcination. 
 By attraction of fixed air from the atmofphere, it foon 
 hardens after it has been dug up. 
 
 Mr Williams divides the lime-Hones of Scotland into 
 the following fpecies : 
 
 1 . Grey, whitifh, and pure white ; regularly Gratifi 
 ed ; of a granulated texture ; and much ufed in the 
 Highlands for building bridges. Some of it is com- 
 pofed of fine glittering fpangles like the fcales of fifties ; 
 and fome is as pure white as the bell refined fugar, 
 which kind he thinks may be called Parian marble. 
 
 2. Coarfe-looking grey mountain lime ftone, hard 
 and'ftrong, of a granulated texture, difficult to work, 
 in fome 'places rough and unequal, in others fmooth 
 and even. Sometimes regtraiiy ftratified, at other 
 times- appearing like one vail irregular bed or rock, of 
 various thic .u .ics. 
 
 3. Aih-coL ured mru -tain I'm^ftones, confiftihg 1 of 
 finall giaJEb of a fine iinootli : . xtuie, ; when broken re- 
 
 icmbling 
 
[ 44 3 
 
 2. Partial folution in water, with which they con 
 tract great heat, and by fprinkling with water they fall 
 more readily into powder. 
 
 3. Infufibility without addition. 
 
 4. They 
 
 fembling flint. In the Highlands there are hills of 
 this kind of ftone, which our author informs us he 
 has feen ; fome of which have regular ftrata, while 
 others appear in one vaft mafs like a rock of granite. 
 
 4. Regularly-ftratified limeftone, found in the low 
 countries, exhibiting a vaft variety of colours ; as black, 
 blue, grey, brown, purple, red, and afh -coloured ; with 
 various mixture?, of all degrees of hardnefs and purity. 
 
 5. Limeftone accompanying coal, and frequently the 
 immediate roof of the vein. This likewife fhows a great 
 variety of colour, texture, and quality ; fome being fo 
 much adulterated with clay and other heterogeneous 
 mixtures as to be good for nothing, while others are 
 very pure and fine. Thefe limeftones are always found 
 in regular ftrata. " They are found (fays our author) 
 as regular as the coals they accompany ; and the coal- 
 ftrata are more regular in continuation upon the bear 
 ing, as far as the clafs of ftrata belonging to the coal 
 reaches, than any Other that I have inveftigated ; and 
 I look upon it, that this obfervation may be of uie in 
 praaice." 
 
 For difcovering limeftone at fome dl fiance, Mr 
 Williams gives the following directions : Let them 
 keep the line of ftretch, or bearing of the ftrata ; and 
 in the coal-country, they will be fure to difcover it 
 at nearly the fame parallel diitance from a feam of coal > 
 or other given ftratum, as the place where it was laft 
 feen. But many of the mountain-limeftones are not 
 much to be depended on. Though you may have, 
 a good and plentiful quarry in one place, yet, perhaps,, 
 fcaif a mile, or half a quarter of a mile farther for* 
 
C 45 ] 
 
 4. They attract the fixed air from the vegetable 
 and mineral alkalies, and thus rendering them much 
 more caultic, becoming at the fame time mild them-, 
 feives. 
 
 5. Solu- 
 
 ward, you cannot difcover it : it is dwindled away to 
 nothing, and yet will appear again farther forward ; 
 which makes the mountain-limeftones uncertain to be 
 difcovered where you do not fee them ; as thefe rocks 
 very frequently grow thicker or thinner, and fometimes 
 fqueezes out to nothing : and I comprehend under 
 this denomination all the limeftones not accompanying 
 the coals and coal-metals. The limeftcnes.of the coal 
 fields are often diftinguiihable by containing a great va 
 riety of fhells, coral, and other marine bodies, which 
 are found blended in the heart and compofition of the 
 ftone." 
 
 6. The Scotch marbles are of great variety and beau 
 ty ; and the parts of the kingdom moft unfit for cul 
 tivation are found to abound moft in them. Affint in Su 
 therland has a kind of white ftatuary marble, which Mr 
 Williams fays is the pureft and bed he ever faw. " I am 
 perluaded (fays he) there is none better, if any fo good, 
 in all Europe, and there is enough of it to ferve all Bri 
 tain ; perfectly folid and pure, free of any blemifnes, 
 flaws, or {tains, and blocks or {labs of any fize may be 
 cut out : but there is bad accefs to it ; nor would it be 
 eafily quarried, there being a little cover above it, of a 
 foft, loofe, whitifh limeftone. This marble accompa 
 nies a prodigious rock of grey limeftone, of a granula 
 ted texture, appearing in regular ftrata at Affint ; but 
 it is one of thofe which varies in thicknefs as you advance 
 along the bearing of the ftrata. The good white mar 
 ble of Affint is only to be feen in the bed of the river, 
 near a confiderable houfe a mile or two fouth of the 
 
 church ; 
 

 C 46 ] 
 
 5. Solubility in all acids except the vitriolic, tarta* 
 rous, and fome anamalous vegetable acids. 
 
 6. Fufibility with borax and microcofmic falts. 
 The fufion is attended with effervefcence, and the re- 
 fult is a tranfparent and colourlefs glafs. 
 
 7. With metalline calces they melt into a corrofive 
 flag. 
 
 church ; but I cannot remember the name of the parti 
 cular place." 
 
 Near Blairgourie in Perthfhire, not far from the 
 fide of the high road, is an excellent, granulated, 
 broad-bedded limeflone, of a fugar-loaf texture, and 
 as white as the fineft ftatuary marble, which Mr 
 Williams fuppofes to be a good fpecies of the true 
 Parian marble, and that it requires only to be known 
 and brought into ufe to become of great value, In 
 the duke of Gordon's lands, in the foreft of Gle- 
 navon, there is alfo a kind of marble compofed of 
 broad glittering grains like fpangles, as large as the 
 fcales of fifhes j but the fituation is remote, and dif- 
 cult of accefs. 
 
 In Lochaber, near the farm-houfes on the north 
 fide of the ferry of Ballachyliih, is a limeftone or 
 marble rock, of a beautiful aflien-grey colour, and a 
 fine regular uniform grain or texture ; capable of be 
 ing railed in blocks or flabs of any fize, and of receiv 
 ing a fine polifh. It is beautifully fprinkled with fire 
 bright grains of mundick or pyrites, and likewife with 
 grains or fpecks of beautiful lead ore of a fine texture. 
 
 About three miles fouth of Fort-William, in the 
 bed of a river, is a curious kind of marble with a 
 black ground, flowered with white, like fine needle 
 work, or rather refemb'Jng the froft-flowering upon 
 glafs windows in winter ; and this flowering is not 
 only on the outfide, but quite through all parts of the 
 Jx>dy of the ftone. 
 
 Scotland 
 
E 47 3 
 
 8. They imperfectly reduce the calces of lead and 
 bifmuth, and have even fome effect upon thofe of cop 
 per and iron. 
 
 The cajcareous earth is found, 
 I. Pure. 
 
 1 . In form of powder. Agaricu? mineralis, or lac lun. 
 
 a. White, in moors, and at the bottom of lakes. 
 
 b. Red. 
 
 c. Yellow. 
 
 2. Friable and compact. Chalk, creta. 
 
 a. White, creta alba-. Chalk is a name alfo applied 
 to other ea/ths ; whence we hear of chalks of va 
 rious colours : but there are none which are 
 known to be of a calcareous nature, except this 
 kind here defcribed, and of which there are no 
 other varieties, otherwife than in regard to the 
 loofenefs of the texture, or the finenefs of the 
 particles. 
 
 3, Indurated, or hard ; Limeftone ; Lapis calcareus. 
 A. Solid, or not granulated. 
 a. White. 
 . Whitifh yellow. 
 
 c. Flefh-coloured, found in loofe mafTes. 
 
 d. Reddifh brown. 
 
 e. Grey. 
 
 /. Variegated with many colours, and particular 
 ly called marble. 
 g. Black. 
 JB. Grained or granulated limeftone. 
 
 i . Coarfe-grained, and of a loofe texture, called 
 fah-jtag in Swedifh, from its refemblance to 
 kimps of fait. \ 
 
 a. Red. 
 
 Scotland has alfo chalk in abundance ; fome of 
 vhich is regularly ftratified, and much appears in thick 
 rregular maffes like fediment. 
 
[ 48 ] 
 
 a. ReddiiK yellow, b. White. 
 
 2. Fine grained. 
 
 a. White, b. Semi-tranfparent, from Solfatara 
 in Italy, in which native brimftone is found. 
 
 3. Very fine grained. 
 
 a. White and green. I. White and black. 
 C* Scaly limeftone. 
 
 1. With coarfe or large fcales. 
 
 a. White, b. Reddifh yellow. 
 
 2. With fmall fcales. 
 a. White. 
 
 3. Fine glittering or fparkling. 
 
 a. White, b. Of many colours. 
 ZX Lime or calcareous fpars. 
 
 (i.) Of a rhomboidal figure. 
 &. Tranfparent or diaphanous. 
 
 1. Refracting fpar ; Spatum ijlandicum ; Iceland 
 fpar, or Iceland cryftal. This reprefents the 
 objects feen through it double. 
 
 2. Common fpar, which fhows the object fingle. 
 #. White, or colourlefs. 
 
 b. Yellowifli and phofphorefcent. 
 u. Opaaue. 
 
 i. White. 2. Black. 3. Brownifh yellow. 
 (2.) Foliated or plated fpar. 
 
 a. Opaque white. 
 
 j. Cryftallized calcareous fpars. Spar. Drufcn *. 
 (i.) Traniparent. 
 
 a. Hexagonal truncated. 
 I. Pyramidal. 
 
 I . Dog's teeth ; Pyramldales SJlinftix. 
 
 2. Balls 
 
 * The tranflator of Mr Cronftedt's Treatife has 
 adopted -this German term drufcn into the Englifti lan 
 guage, for a clufter of regular figured bodies, as a 
 groupe conveys the idea of a clr.fter only, whether 
 regular or of indeterminate figures. 
 
C 49 ] 
 
 2. Balls of cryftallized fpar, Pyramldales concrete. 
 Jp. Staladlitical fpar ; Sta'aSites calcareus* Stalactites^ 
 
 Stone-icicle, or Drop-ftone. 
 ( i.) Scaled ftala&ites of very fine particles. 
 
 a. Of a globular form. 
 ^. White, the pea-ftone. 
 
 2. Grey, plfiKthus, oolithm. Alfb the hammites, 
 from its refemblance to the roes or fpawn of 
 fifh. It has been exhibited by authors as petri 
 fied roes. The Ketton free-fione, of Rutland* 
 fhire, is a remarkable (lone of this fort. 
 
 b. Hollow, in the form of a cone* 
 i. White. 
 
 c. Of an indeterminate figure. 
 
 d. Of coherent hollow cones. 
 
 (2.) Solid ftalactites of a fparry texture. 
 
 a. Hollow, and in form of a cone. 
 i. White, and femitranfparent. 
 
 II. Saturated or combined with the acid of Vitriol. 
 Gypfum, Plafter-ftone, or Parget. 
 
 1. Loofer and more friable than a pure calcareous 
 earth. 
 
 2. Either crude or burnt, it does not excite any ef- 
 fervefcence with acids ; or, at moft, it effervefces 
 but in a very flight degree, and then only in pro 
 portion as it wants fome of the vitriolic acid to 
 complete the faturation. 
 
 3. It readily falls into a powder in the fire. 
 
 4. If burnt, without being red hot, its powder rea 
 dily concretes with water into a mafs, which fooa 
 hardens ; and then, 
 
 5. No heat is perceived in the operation. 
 
 6. It is nearly as difficult to be melted by itfelf as 
 the limellone, and fhows moftly the fame effecls 
 with other bodies as the lime-ftone : the acid o 
 vitriol feems, however, to promote its vitrifica 
 tion. 
 
 F 7, Whea 
 
C 5 3 
 
 7. When melted in the fire with borax, it puffs 
 and bubbles very much, and for a long while, 
 during the fufion, owing to the nature cf" both the 
 falts. 
 
 8. When a fmall quantity of any gypfum is melted 
 together with borax, the glafs becomes colour- 
 lefs and tranfparent ; but fome forts of alabafter 
 and fparry gypfa, when melted in fome quan 
 tity with borax, yield a fine tranfparent yellow 
 coloured glafs, refembling that of the bed to 
 pazes. This phenomenon might probably hap 
 pen with every one of the gypfeous kind. But it 
 is to be obferved, that if too much of fuch gyp 
 fum is ufed in proportion to the borax, the glafs 
 becomes opaque, juft as it happens with the pure 
 limeftone. 
 
 9. Burnt with any inflammable matter, it emits a 
 fulphureous fmell ; and may as well by that 
 means, as by both the alkaline falts, be decom 
 pounded ; but for this purpofe there ought to be 
 five or fix times as much weight of lalt as of 
 gypfum. 
 
 10. Being thus decompounded, the calx or earth 
 which is left iliows commonly fome marks of iron. 
 
 The gypfeous earth is found, 
 
 (i.) Loofe and friable. Gypfeous earth, properly fo 
 
 called ; Guhr. 
 
 A. White. 
 (2.) Indurated. 
 
 A. Solid, or of no vifible particles, Alabafter. 
 a. White, alabafter. 
 
 1. Clear and tranfparent. 
 
 2. Opaque, 
 . Yellow. 
 
 i. Tranfparent, from the Eaftern countries. 
 2 Opaque. 
 
 B. Gypfum of a fcalded or granulated ftru&ure. 
 This is the common plafter-ftone. 
 
 j. With 
 
[ 5' ] 
 
 1. With coarfe fcales. a. White. 
 
 2. With fmall fcales. a. Yellowifh. I. Greyifh. 
 C. Fibrous gypfum, or plafter-ftone, improperly 
 
 (though commonly) called Englijh talc by the 
 druggifts. 
 
 i. With the fibres coarfe. a. White, from Li 
 vonia. 
 
 - TXfM, r,^o Tvpc n Whi^P. 
 
 X). Spar-like gypfum. Selenites, by feme alfo call 
 ed gtacies mat 1,2 ; and confounded with the ckar 
 and tranfparent mica. 
 
 1. Pure felenites. 
 A. Tranfparent. 
 
 a. Colourlefs. I. Yellowiili. 
 
 2. Liverftonc, fo called by the Swedes and Ger 
 mans. 
 
 . Cryftallized gypfum. Gypfecus drufen. 
 
 ( i ). Drufen of chryftals of pure fparry gypfurn. 
 
 A. Wedge formed, ccmpofed of a purs fpar- 
 like gypfum. 
 
 a. Clear and colourlefs. b. V/hitifh yellow. 
 
 B. Capillary. 
 
 a. Opaque whitifh yellow, t. Hexagonal, 
 prifmatic. c. Globular, confjfting of ciuie- 
 ated rays proceeding from the centre, 
 F. Stalaclitical gypfum. Gypfum finter. 
 
 j . Of no vifible particles ; in French, grignard. 
 A. Of an irregular figure. 
 a. Yellow, b. White. 
 2. Of a fpar-like texture. 
 
 A. In form of a cone. 
 a. White and yellow. 
 
 B. Of an irregular figure. 
 a. White. 
 
 III. Calcareous earth faturated with the acid of com 
 mon fait. Sal ammoniacumjixum nalurale. 
 
 This is found, i. In fea-water. 2. In fait pits. 
 
 F 2 IV. Cal- 
 
C !' ] 
 
 IV. Calcareous earth combined or faturated with fpany 
 acid, known by die name of f parry Jluor and Hue 
 John. 
 
 Thefe are commonly caUed^xi^w/r^/, org/afs- 
 fpars ; bccaufe mod part of them have a fparry form 
 and appearance : they are, however, often met in an 
 intkterniinate figure. 
 
 They are only known m an indurated itate, and di- 
 
 ftingujfh themfelves from the other earths by the fol 
 lowing characters. 
 
 1. They are fcarce harder than common calcareous 
 fpars, and confequently do not ftrike fire with 
 Heel. 
 
 2. They do not ferment with acids neither before 
 nor after calcination. 
 
 3. They do not melt by themfelves, but crack and 
 fplit to pieces when expofed to a ftrong fire. But, 
 
 4. In mixtures with all other earths they are (ge 
 nerally) very fufible, and efpecially with calca 
 reous earth, with which they melt into a corro 
 ding glufs that diffclves the ftrongeft crucibles, 
 unlefs fome quartz or apyrous clay be added 
 thereto. 
 
 5. When heated {lowly, and by degrees, they give 
 a phofphorefcent light : but as foon as they are 
 made red-hot, they loofe this quality. The co 
 loured ones, efpecially the green, give the ftron- 
 geft light, but none of them any longer than whilft 
 they are well warm. 
 
 6. They melt and diflblve very eafily by the addi 
 tion of borax , and, next to that, by the micro- 
 cofmic fait, without ebullition. 
 
 A* Indurated fluor. 
 
 (i.) Solid, of an indeterminate figure; of a dull 
 texture, femitranfparent, and full of cracks in the 
 rock. 
 
 a. White. 
 
 (2.) Sparry 
 
C 53 ] 
 
 (2.) Sparry fluor. This has nearly the figure of 
 fpar ; though on clofe obfervation it is found not 
 to be fo regular, nothing but the gloffy fur faces 
 of this (tone giving it the refemblance of fpar. 
 
 a. White, b. Blue. c. Violet, d. Beep green. 
 e. Pale green. /. Yellow. 
 
 (3.) Cryftallifed fluor. 
 
 1. Of an irregular figure, a. White. I. Blue. 
 c. Red. 
 
 2. Of a cubical figure, a. Yellow. I. Violet. 
 4. Of a polygonal fpkerical nVure. a. White. 
 
 b. Blue. 
 
 4 Of an o^loedral figure, a. Clear, colourlefs. 
 
 V. Calcareous earth faturated with a particular acid, 
 
 perhaps of the metallic kind, viz. the tungftenic 
 
 acid. The tungjleln of the Swedes. 
 This refembles the garnet-ftone and the tin-grains ; 
 is nearly as heavy as pure tin ; very refractory in the 
 air, and exceffively difficult to reduce to metal. Iron 
 has, however, been melted out of it to more than 30 
 per cent. It is very difficultly diflblved by borax and 
 alkaline falts, but melts very eafily with the microcof- 
 mic fait, giving a black ilag ; and for this reafon the 
 lad mentioned fait muft be employed in the aifays of 
 this ftone. It is found, 
 
 1. Solid and fine-grained. 
 
 a. Reddifh or fbfh-colcured. I. Yellow. 
 
 2. Spathofe, and with an undluous furface. 
 a. White, b. Pearl-coloured., 
 
 VI. Calcareous earth united with the inflammable fub* 
 
 (lance. 
 
 Thefe have a very offenfive fmell, at lead when rub 
 bed. They receive their colour from the phlogifton,, 
 being dark or black in proportion as it predominates, 
 (i.) Calcareous earth mixed with phlogifton alone ; 
 Lapis fui/lus, fetid ftone and fpar, or fwine-ftone 
 and fpar, 
 
 F d. elid> 
 
C 54 1 
 
 v/. Solid, or of no viiible or diflinct particles. 
 
 a. Black. 
 JB. Grained. 
 
 a. Blackifh brown. 
 
 C. Scaly, partlculis micaceis* 
 
 1. With coarfe fcales. a. Black. 
 
 2. With fine fparkling fcales. a. Brown. 
 
 D. Sparry. 
 
 a. Black. I. Light brown, c. Whitifh yellow* 
 
 E. Cryftallifed. 
 
 i. In a globular form. 
 
 VII. Calcareous earths blended with an argillaceous 
 earth. Marie, Marga. 
 
 1. When crude, it makes an effervefcence with 
 acids: but, 
 
 2. Not after having been burnt ; by which opera 
 tion it is obferved to harden, in proportion as 
 the clay exceeds the calcareous fubftance. 
 
 3 It eafily melts by itfelf into a glafs, and even 
 when it is mixed with the moft refraftory clay. 
 
 4. It is of great life in promoting the growth of 
 vegetables, fmce the clay tempers the drying qua 
 lity of the calcareous earth. 
 
 5. When burnt in a calcining heat, it readily attracts 
 water : and, expcfed to the air, in time it falls 
 
 into a powder. 
 
 The varieties of this kind worthy to be taken 
 notice of, depend on the different quantities of 
 each of their component parts, and on the quality 
 of the clay. The following are fpecified as ex 
 amples. 
 
 A. Loofe and compadl, Marga fnabiTis. 
 a. Reddifh brown. 
 
 I. Pale red. This, when burnt, is of a yellowifli 
 colour, and ufed for making earthen ware in 
 fome places. 
 
 J]. Semi-indurated ; which is nearly as hard as ftone 
 when firft dug up, but moulders m the.o.pen air, 
 
 &. Grey. 
 
C 5J ] 
 
 a. Grey. I. Red. 
 C. Indurated or ftone marie. 
 
 A. in loofe pieces, Marga tndurata amorpha ; by 
 the Germans called duckjlem or topbjkin* 
 
 <7. White, b. Grey, formed from a fediment 
 which the water carries along with it. 
 
 B. In continued ftrata. Hard ilaty marie. 
 
 VIII. Calcareous earth united with a metallic calx. 
 
 Here, as well as in the others, fuch a mixture or 
 combination is to be underftood, as cannot be difco- 
 vered by the eye alone without the help of fome other 
 means. 
 
 The fubjefts belonging to this divifion lofe the pro 
 perty of raifing an effervefcence with acids, when they 
 are rich in metal, or contain any vitriolic acid. How 
 ever, there have been found fome that contained 20 
 or 30 per cent, of metal, and yet have fhoun their cal 
 careous nature by the nitrous acid. 
 
 There are no more than three metals hitherto known 
 to be united in this manner with the calcareous earth, 
 viz. 
 
 ( i ) With iron. White fpar like iron ore, Mlnera 
 Jerri alia. The jtahlftein or tuelfes eifenerz, of the 
 Germans. 
 
 1. This ore, however, is not always white, but 
 commonly gives a white powder when rubbed. 
 
 2. It becomes black in the open air, as likewife in 
 a calcining heat. 
 
 3. In this laft circumftance it lofes 30 or 40 per 
 cent, of its weight, which by diltillation has 
 been found owing to the water that evaporates ; 
 and it is poffible that fome fmall quantity of 
 vitriolic acid may, at the fame time, evaporate 
 with the water. 
 
 It is of all the iron ores the moft eafy to melt, 
 and is very corrofive when melted. 
 
 This, 
 
C 56 J 
 
 This kind is found, 
 
 A. Loofe ; the mouldered part of the indu 
 rated fort. 
 
 a. Black, like foot. 
 
 b. Dark brown, fomewhat refembling umbre. 
 
 B. Indurated. 
 
 1. Solid, of no diftinft particles. 
 
 a. Red. Looks like red ochre, or the 
 red haematites, but diflblves in the acid 
 of nitre with a great effervefcence. 
 
 2. Scaly, par faults micaceis. 
 a. White. 
 
 I. Blackifh grey. 
 
 3. Spar-like. 
 
 a. Light brown. 
 
 4. Drufen. 
 
 a. Blackifli brown. 
 
 b. White. 
 
 1. Porous. This is often called eifen- 
 blute, orjlosferri. 
 
 2. Cellular. 
 (2) With copper. 
 
 A* Loofe and friable. Mountain blue ; Germa- 
 Ciice, Bergllau. This diffolves in aquafortis 
 ^ r ith effervefcence. 
 
 B. Indurated. 
 
 1. Pure calcareous earth mixed with calx of 
 copper. Armenian fione, lapis Armenus. 
 
 2. Gypfeous earth united with calx of copper. 
 Is of a green colour ; and might perhaps be 
 called turquoife ore, or malachites ; though we 
 do not know if all forts of turquoife ore are 
 of this nature. 
 
 a. Semi-tranfparent, is found at Ardal in 
 
 Norway. 
 (3.) With the calx of lead. 
 
 This is a lead ochre, or a fpar-like lead-ore, 
 which, in its formation, has been mixed with a 
 
 calca- 
 
I 57 ] 
 
 calcareous earth, and for that reafon eflervefces 
 with acids. 
 
 A. Loofe and friable, 
 i. White. 
 
 B. Indurated, 
 i. Scaly. 
 
 tr 11 -t\ 
 
 Boththefe varieties contain a considerable 
 quantity of lead, in*. 40 per cent, more or 
 lefs ;*and the calcareous earth, is as equally 
 and intimately mixed with it, as in the white 
 iron ore. 
 
 IX. The following compounds of calcareous earth 
 with different mineral fubftances are added from 
 Mr Kirwan's Elements of Mineralogy. 
 
 1. A compound of calcareous and barotical earths : 
 of this fpecies are fome yellowifh ftones found in 
 Derbyfliire, confiding of lumps of limeftone in- 
 terfperfed with nodules of barofelenite. Many 
 more may occur as compounds of gypfum and ba 
 rofelenite, fluor and barofelenite, &c. &c. 
 
 2. Compounds of calcareous and magnefian earths ; 
 fuch as, 
 
 a. The white marble, interfperfed with fpots of 
 fteatites of foap-rock, either green or black, 
 called by Crondftedt kolmord marble. This mar 
 ble is of a fcaly texture. 
 1. The pletra takhina of the Italians, which confifts 
 
 of white fpar with veins of talc. 
 c. The verde antico of the Italians, which is a light 
 green marble, with deep green, black, white, 
 and purple fpots. According to Mr Bayen, 
 it contains 62 parts of mild calcareous earth, 
 30 of green talc, i of magnefia, and i of fe- 
 miphlogifticated iron. 
 
 3. Compounds of calcareous and argillaceous earths; 
 fuch as, 
 
 a. The 
 
a. The green Campan marble from the Pyrenees. 
 It is flaty and fomewhat magnetic. Accord 
 ing to Mr Bayen, it contains 65 of mild calca 
 reous earth, 32 of the argillaceous, and 3 of fe 
 miphlogifticated iron. 
 
 . The red Campan marble : this is not magne- 
 
 tUUJt .contains 82 parts of mild calcareous 
 eann, 1 1 01 argmaxtuuo imnu^, .nva / v>i uv- 
 
 phlogifticated iron. 
 
 t. Yellow figured marble from Florence : accord 
 ing to Mr Bayen, it contains 75 parts of mild 
 calcareous earth, 13 or 14 of fhiftus, and 4 or 
 5 of dephlogifticated iron. 
 
 J< Griutte marble from Autun of Burgundy in 
 France : it contains 67 parts of mild calcare 
 ous earth, 26 of reddifh fchiftus, 2 of iron, 
 and i of magnefian earth. 
 
 e. The Amandola, which is a green marble, ho 
 ney-comb like, with white fpcts. It contains 
 76 parts of mild calcareous earth, 20 of fchiftus, 
 and 2 of femiphlogifticated iron. The cellular 
 appearance proceeds from the fchiftus. 
 4* Compounds of calcareous earth and mica ; fuch 
 
 as, 
 
 a. The cipolin from Autnn in France : it is of a 
 gree.n colour, and confifts of 83 parts of chalk, 
 12 of green mica, and i of iron. 
 
 b. The micaceous limeftone, is of a glittering ap 
 pearance, of various degrees of hardnefs, and 
 effervefces with acids. Such as the macigno of 
 the Italians; their yelloxv pietra bigia; and 
 their blue pietra columbina or turkina. 
 
 5. Compounds of calcareous and filiceous earths j 
 fuch as, 
 
 a. The calcareous quartz and pudding-flone : this 
 
 confifts of lumps of quartz, and fometimes of 
 
 felt-fpar in a calcareous cement. 
 
 I, The limeftone with veins of quartz ; fuch as 
 
 \hzfaxumfahibergenfe, and feveral marbles of 
 
 Sweden 
 
[ 59 ] 
 
 Sweden and Siberia, which ftrike fire with 
 
 fteel. 
 
 6. Calcareous volcanic pudding-ftone ; fuch as, 
 a. The cierchina, which confifts of lumps of fpar 
 
 and lava, in a calcareous cement, mentioned by 
 
 Mr Ferbei. 
 I. The marble mixed with veins of black or green 
 
 lava, mentioned by the fame anthor. 
 r. Compounds of calcareous earth, mixed with two 
 or more kinds of earth ; fuch as, 
 
 a. The cipolin from Rome, which is fa green 
 marble with white zones : it ftrikes, though 
 difficultly, fire with fteel : it contains 67,8 
 parts of mild chalk, 25 of quartz, 8 of fhiftus, 
 andg|,2 of iron, befides the iron contaiaed in 
 the argillaceous fhiftus. 
 
 b. The calcareous porphyry, which confifts of 
 quartz, felt-fpar, and mica in feparate grains 
 united by a calcareous cement. 
 
 c. The limeftonc interfperfed with fhoerl and 
 mica. 
 
 d. To thefe compounds belongs the pyritaceous 
 lime (tone called by the French Pierre de Sf 
 Ambroix. It is of an iron grey colour, inter 
 fperfed with jQiining particles. Its texture is 
 compact, and fcarcely gives fire with fteel. Its 
 fpecific gravity is 2,7034. It is foluble in acids, 
 and moftly with elfervefcence ; calcines in a 
 ftrong fire ; makes nitre flightly detonate ; 
 and if diftilled affords a fmall portion of vitrio 
 lic acid, and fome fulphur fublimes. Its com 
 ponent parts are 75 of mild calcareous earth 
 and 25 of pyrites; in which are contained 14 
 of argill, 7 of quartz, and fulphur, and 4 of 
 iron. 
 
 Order 
 
Order II. PONDEROUS EARTH. 
 PONDEROUS earth, (Terra Ponderofa) : Cauk, or 
 calk. See EARTH, Art. I. This is a particular kind 
 of earth (like chalk in appearance, but with fome 
 very different properties), difcovered in Sweden about 
 1774, which by its refults with other bodies has fome 
 fimilarity to the known alkalis. It has not yet 
 been found pure, but mixed with other fubftances : 
 however, its great fpecific weight eafily diftinguilhes 
 it from the others, it being the heavieft of all earths. 
 i. Its fpecific gravity when confiderably purified 
 
 by art is 3,773. 
 
 a. This earth combines with aerial acid : and in 
 this cafe effervefces with ftronger ac^s. 
 
 3. With vitriolic acid it forms the ponaerous fpar, 
 which is mfoluble in water. 
 
 4. Its cr/ftallization, after being combined with the 
 nitrous, or with the muriatic acids, is hardly fo- 
 ^uble ; 
 
 5. "b>c with acetous acid, it becomes deliquefcent. 
 
 6. When pure ; viz. without any mixture of acid or 
 alkali, it does not vitrify in the fire. 
 
 7. If deprived of the aerial acid (fixed air) by cal 
 cination, is then foluble in 900 times its weight 
 of boiling water.. This folution expofed to air, 
 forms a cremor, like that of lime-water in the 
 fame circumftances, and like it changes alfo the 
 vegetable colours. 
 
 8. Whilft combined with aerial acid, it is only fo 
 luble in about 1550 times its weight of water, 
 chiefly if the water has been impregnated alfo 
 v/ith the fame aerial acid, 
 
 9. It expels the cauflic volatile alkali from ammoni- 
 acal fait. 
 
 10. Mixed with brimftone it produces a hepar ful- 
 phuris, whofe folution in water is but incomplete 
 ly 
 
C 61 ] 
 
 ly decompofed either by the nitrous or the muria 
 tic acid, on account of the great attraction be 
 tween this earth and the acid of fulphur, which is 
 fo ftrong that it 
 
 u. Separates this acid (the vitriolic) from the ve 
 getable alkali. 
 
 I. Combined with aerial acid ; Terra Ponderofa aerata. 
 
 See CHEMISTRY-/^V. 
 
 It refembles alum, but is hard and ftriated, as if 
 compofed of radiating fibres coming from a cen 
 tre. It is found in Alllon-moor in England. 
 A. Spar-like gypfum. 
 
 1. Ssmitranfparent, fpatum Bononienfe. The Bono- 
 nian ftone, or native phofphorus. 
 
 2. Opaque, a. White, b. Reddifh. 
 J3. Ponderous Drufen fpar. 
 
 1. Jagged, crtftatum. Thefe refemble cock's combs, 
 and are found in clefts and fiflures accreted on the 
 furfaces of balls of the fame fubftance. 
 
 2. White. 
 
 3. Reddifh. 
 
 II. United with phlogifton and the vitriolic acid. 
 
 Leterjlein of the Germans and Swedes. Lapis 
 
 hsfaticus. 
 This ftone in fome fpecimens conftantly, but in 
 
 others only when rubbed, fmells like the hepar 
 
 fulphurls, or gun-powder. 
 It is found. 
 
 A. Scaly. 
 
 1. With coarfe fcales. a. Whitifh yellow. 
 
 2. With fine fparkling fcales. a. Black. 
 
 Order III 
 
Order III. MAGNESIAN, MICACEOUS, and 
 ASBESTINE EARTHS. 
 
 i. Jftfagjufian Earths. 
 
 MAGNESIA is a white, loofe, and light earth, only 
 known fmce the beginning of this century. It is ge 
 nerally found combined or mixed with other hetero 
 geneous fubftances, as other fimple earths are. 
 
 1. When pure its fpecific gravity is 2,330, and 
 then, 
 
 2. It neither hardens, contracts, nor melts by the 
 application of heat, even by the folar rays. 
 
 3. But it melts eafily with borax, or microcofmic 
 fait ; though it is fcarcely affecled by fixed alka 
 lis or calces of lead. 
 
 4. Mixed with other earths, it produces by fire dif 
 ferent hard mafTes. 
 
 5. It gives no caufttcity except to the volatile al 
 kali : and, 
 
 6. Does not efFervefce with any acid. 
 
 7. When mixed with water it fhows a very fmall 
 degree of heat, but without any effervefcence. 
 And when the water exceeds the weight of 
 magnefia about 7,692 times, it is totally dif- 
 folved. 
 
 $ and 9. Being put in water and afterwards dried, 
 it contains ^ L -/- u parts of its weight ; though when 
 f iturated with aerial acid, it will abforb and re 
 tain after being dried T 6 / . parts of water. 
 
 10. This earth combined \\ith aerial acid is more 
 foluble in cold than in hot water. 
 
 11. Combined with vitriolic acid it cryftallizes into 
 a bitter fait, known by the name of Epfom and 
 Seydlitz or Scidfchulitz fait, which is foluble in lit 
 tle more than its own vi eight of water. 
 
 12. With nitrous acid it forms a del'-quefcent fait. 
 
 13. With 
 
C 63 3 
 
 13. With the muriatic or the acetous acids- it does 
 not cryftallize : and the mafs being dried, at 
 tracts humidity from the air. 
 
 14. It has a ftronger attraction to the fluor acid 
 than to any other (Berg.) : and cryftaliizes with- 
 it into hexangular priims whofe ends are formed 
 of two low pyramids, of three rhombs (Rome de 
 !' IJk). 
 
 15. It is not precipitated from other acids by the 
 vitriolic, as calcareous earth is. 
 
 1 6. According to Lavoifier and Macqner, when 
 magnefia is calcined, it becomes phofphercicent. 
 
 I. Magnefia combined with vitriolic and other 
 
 acids. 
 
 d. When fattirated with the vitriolic acid, it forms 
 a bitter fait, called jEngli/b or Epfvm, Seydftu?-* 
 cr Sedlit-x, fait. The falts known under thefe d;f- 
 ferent names only differ from one another on ac 
 count of fome heterogeneous fuhftance, which is 
 combined in them, the vitriolated magnefia be 
 ing the characterise and principal ingredient in 
 them all. 
 
 JB. Magnefia is found not only combined with the 
 vitriolic acid in the waters of Epfom, Sedlitz, &c. 
 but alfo with the marine acid to a confiderable 
 quantity in fea-water and other fait fprings. 
 
 C. It is contained frequently in frefh waters, where 
 it is diifolved by means of a quantity of aerial 
 acid. 
 
 II. Combined with other earths. 
 
 A. Magnefia, when combined with filiceous earth, 
 is commonly unctuous to the touch, and more 
 or lefs difficult to be cut or turned in proportion 
 to its different degrees of hardnefs. 
 
 It is not diffufible in water: grows hard, and 
 is very refractory in the fire. 
 
 G 2 When 
 
C 6 4 ] 
 
 When pounded and mixed with water, it will 
 not eafily cohere into a pafte : however, if it is 
 managed with care, it may be baked in the fire 
 to a mafs, which being broken, fhow^s a dull and 
 porous texture. 
 
 It takes for the moft part, and without much 
 labour, a fine polifh. It is found, 
 ( i.) Compact and foft ; Smeftis, Bnangon or French 
 Chalk. 
 
 a. White, from the Lands-End, in Cornwall, 
 
 b. Yellow. 
 
 c. Red and white, from the Lands-End - the foap- 
 earth, from Switzerland : it looks like Caftile- 
 foap. 
 
 (2.) Solid and compact ; of impalpable particles: 
 Steatites or foap-rock. 
 a. White, or light green, b. Deep green. 
 
 c. Yellow. 
 
 ( 3. ) Solid, and of vifible particles ; ferpentine flone. 
 A. Of fibrous and coherent particles. 
 This is co/rpofed, as it were, of fibres, and might 
 therefore be confounded with the afbeftus, if its 
 fibres did not cohere fo clofely with one another, 
 as not to be feen when the ftone is cut and po- 
 lifhed. The fibres themfelves are large, and feem 
 as if they were twifted. 
 
 a. Deep green. It is fold for the lapis nephriticus, 
 and is dug at fome unknown place in Ger 
 many, b. Light green, from Skienfhyttan, in 
 Weftmanland ; is ufed by the plate-fmiths in- 
 ftead of French chalk. 
 
 p. Of granulated particles ; fine grained ferpentine 
 ftone, the Zoeblitz ferpentine. 
 a. Black, b. Deep green, c. Light green. </. 
 Red. e. Bluifli grey. /. White. Thefe co 
 lours are all mixed together in the ferpentine 
 ftone from Zoeblitz, but the green is the moft 
 predominant colour. 
 
 JB. Porcelain 
 
C i 3 
 
 .5. Porcelain earth mixed with iron j terra porcellanea* 
 
 rr<i 
 
 Ihis is, 
 
 A. Diffufible in water. 
 
 a. Red, from Montmartre, and China. The wa-. 
 ttr-clinkers which are imported from certain 
 places in Germany feern to be made of this 
 kind. 
 B. Indurated. 
 
 1. Martial foap earth. 
 a. Red. 
 
 2. Martial foap-rock, 
 
 a. Black. 
 
 b. Red. 
 
 C. The telgften of the Swedes ; lapis ellarls. 
 
 a. Light grey. b. Whitith yellow, c. Dark 
 grey. d. Dark green. 
 
 The ferpentine ftone has many varieties ; being 
 found, (i.) Veined or fpotted with green fteatites, 
 (2.) Red, with veins of afbeftos. (3.) Red, green, 
 yellow, or black with veins or fpots of white calcare 
 ous fpar, is called potzevera. The black is called nero 
 dipraio ; the green verde dl Suza ; but thefe names are 
 not retrained to this fpecies. (4.) Veined or fpou 
 ted with gypfum. (5.) Veined or fpotted with baro- 
 felenite. (6.) Veined or fpotted with fhiftiis. And, 
 (7.) With veins of quartz, feltfpar, or fhoerl, (Kir* 
 wan's Mineralogy.) 
 
 What is commonly caNed ferpentine is a true lapis olla 
 rls ; but being variegated with green, yellowifh, and 
 brown fpots, like the fkin of feme common ferpents, it 
 is called by that name. Great quantities of this ftone 
 are found in Italy and Switzerland, where it is often 
 worked into the fhape of difhes and other vafes. (Fa- 
 Ironi.) And the gabro of the Italians is nothing elfe 
 but a kind of ferpentine, ( Kirwan. ) 
 
2. LTicaceous Earths. 
 
 Thefe are known by the following charade rs : 
 
 1. Their texture and compofition confift of thin 
 flexible particles, divifible into plates or leaves, 
 having a filming furface. 
 
 2. Thefe leaves or fcales expofed to the fire lofe 
 their flexibility and become brittle, and then fe- 
 parate into inner leaves : but in a quick and 
 ftrong fire, they curl or crumple, which is a ftep 
 towards fufion ; though it is very difficult to re 
 duce them into pure glafs by themfelves or with 
 out addition. 
 
 . They melt pretty eafily with borax, the micro- 
 cofmic fait, and the alkaline fait : and may by 
 means of the blow-pipe be brought to a clear glafs 
 with the two former falts. The martial mica is, 
 however, more fufible than the uncoloured ones : 
 its fpecific gravity is 3,000. 
 A. Colourlefs or pure mica ; daze, glimmer, orglift. 
 
 1. Of large parallel plates ; Mufcovy glafs. This 
 is tranfparent as glafs ; found in Siberia and Elf- 
 dalen in the province of Wermeland. 
 
 2. Of fmall plates, from Silfverberget, and Runne- 
 by, in the province of Blekinge, 
 
 3. Of fine particles like chaff; chaffy mica.. 
 
 4. Of twitted plates; crumpled mica. 
 J$. Coloured and martial glimmer.. 
 
 1. Brown, femi-tranfparent.. 
 
 2. Of fine and minute fcales. 
 
 a. Brown. 1. Deep green, g. Light greefta, 
 d. Black. 
 
 5. Twitted or crumpled glimmer, 
 a.. Light green. 
 
 4. Chaffy glimmer. 
 a. Black. 
 
 5. Chryftallifed glimmer.- 
 
 .0f 
 
r 67 3 
 
 a. Of concentrated and erect fcales. 
 
 b. Of hexagonal horizontal plated. 
 
 The tranfparent Mufcovy glafs is ufed for windows, 
 and upon all occasions where p^nes of ^la^'s a^e want 
 ed. Perhaps it might alfo be ad/antageoufly employ* 
 cd to cover houfes. 
 
 The twifted or crumpled mica, which is found at 
 Hardnl in Jemtland, is there manufactured into kettles 
 and other vdfels, as alfo for hearths of chimnies : and 
 the powder which falls in the working may be mixed 
 with the common fait for the diftillation of the muria 
 tic acid. 
 
 3. Afoejl'me Eart&s. 
 
 Thefe are only yet difcovered in an indurated ftate ; 
 and their characters are as follows : 
 
 j . When pure, they are very refractory in the fire. 
 
 2. In large pieces they are flexible. 
 
 3. They have dull or uneven furfaces. 
 
 4. In the fire they become more brittle* 
 
 5. They do not ftrike fire with the fteeL 
 
 6. They are not attacked by acids. 
 
 7. They are eafily brought into fufion by borax 
 or alkali. 
 
 In this feftion are included both thofe varieties 
 xvhich by foffilogifts have been mentioned under the 
 names of amiantus and afbeftus, and have often been 
 confounded together. 
 
 I. Afbeftus, which is compounded of foft and thin 
 
 membranes ; amiantus Walhrii. 
 
 A. Of parallel membranes : Corium,Ji<ve caro tnon 
 tana^ Mountain-leather. 
 
 1. l?ure. a. White. 
 
 2. Martial, a. Yello\vifli brown. 
 
 B* Of twifted foft membranes ; mountain-cork* 
 I. Pure. a. White. 
 2,. Martial, a. Ycllowifh brown. 
 
 n. or 
 
C 68 ] 
 
 II. Of fine and flexible fibres ; or earth flax : a 
 
 tus Wallerii. 
 4. With parallel fibres : By/us. 
 
 1. Pure and foft. a. Light green, b. White. 
 
 2. A little martial, and more brittle. 
 
 a. Greenifli, from Baftnas Grufva, at Ryddar- 
 hyttan in Weftmanland. There it forms the 
 greateft part of the vein out of which the copper 
 ore is dug ; a great part of it is confequently melt 
 ed together with the ore, and is then brought to a 
 pure femi-tranfparent martial flag or glafs. 
 B. Of broken and recombined fibres. 
 I. Martial, a. Light green. 
 
 Order IV. SILICEOUS EARTHS. 
 
 SILICEOUS earth is, of all others, the mod diffi 
 cult to defcribe and to diftingwifh perfectly ; however, 
 it may be known by the following characters, which 
 are common to all bodies belonging to this order, 
 i. In its indurated ftate it is hard, if not in regard 
 to the whole, yet at leaft in regard to each par 
 ticle of it, in a degree fufficient to flrike fire with 
 fteel, and to fcratch it, when rubbed againft it, 
 though the fteel be everfo well tempered. 
 a. When pure, and free from heterogeneous par 
 ticles, it does not melt by itfelf, neither in a re-. 
 verberatory nor in a blaft furnace. 
 
 3. After being burnt, it does not fall to a powder, 
 neither in the open air nor in water, as the cal 
 careous earth does, but becomes only a little 
 loofer and more cracked by the fire, unlefs it has 
 been very flowly, and by degrees, heated. 
 
 4. It excites no eflfervefcence with acids. 
 
 5. In the fire it melts eafieft of all to a glafs with the 
 fixed alkaline fait ; and hence it has got the name 
 of vitrefcqnt, though this name is, properly 
 
 fpeaking, 
 
C 69 ] 
 
 fpeaking, lefs applicable to this order than to a 
 great many other earths. 
 
 To the above we may add the following properties from 
 Bergman. 
 
 6. It is not foluble in any of the known acids, the 
 fluor-acid only excepted. But, 
 
 7. It may be diflblved by ihe fixed alkali, both in the 
 dry and wet way. 
 
 8. If the fixed alkali is only half the weight of the 
 filiceous earth, it produces a diaphonous and 
 hard glafs : but when it is in a double or triple 
 proportion, then the glafs deliquefces of itielf 
 by attracting the humidity of the atmofphere.. 
 
 9. It melts eafily with borax ; but 
 
 jo. With microcofmic fait it is more difficult, and 
 requires a longer time to melt. 
 
 1 1. This earth has a great analogy to acids, as it is 
 perfectly diflblved in that wonderful natural hot- 
 water ipout above ninety feet high at Geyfer, in 
 Iceland, where by cooling it forms a filiceous 
 mafs. 
 
 I. Gems, orpreciousjlones. 
 
 I. Diamond. Adamas gemma. See DIAMOND. 
 
 1. Of all ftones, it is the hardeft. 
 
 2. Is commonly clear, or tranfparent ; which qua 
 lity, however, may, perhaps, only belong to its 
 cryftals, but not to the rock itfelf from which 
 they have their origin. 
 
 3. Its fpecific gravity is neareft 3,500. When 
 brought to Europe in its rough Hate, it is in the 
 form either of round pebbles with filming fur- 
 faces, or of chryftals of an ocloedral form. 
 
 a. Colourlefs, or diaphonous, or the diamond pro 
 perly fo called. 
 
 But it alfo retains this name when it is 
 tinged fomewhat red or yellow. Being rub 
 bed, 
 
E 70 ] 
 
 bed, it difcovers feme eleclrical qualities, and 
 attracts the maftic. 
 
 1. Red ; Ruby. Adamas ruler ; Rublnus. 
 Which, by lapidaries and jewellers, is, in re- 
 gard to the colour, divided into, 
 
 1. The ruby of a deep red colour inclining a 
 little to purple, 
 
 2. Spinel), of a dark colour. 
 
 3. The balafs, pale red, inclining to violet. 
 Thisisfuppofed to be the mother of the rubies. 
 
 4. The rubicell, reddifh yellow. 
 However, all others do not agree in the 
 
 characters of thefe ftones. 
 
 II. Sapphire. Sapphyrus gemma* 
 
 It is tranfparent, of a blue colour | and is faid to 
 be in hardnefs next to the ruby, or diamond* 
 
 III. Topaz. TTopai&htJ gemma* 
 
 a. The pale yellow topas j whkh i nearly un- 
 
 coloured. 
 
 I. The yellow topaz. 
 f. Deep yellow, or gold coloured topaz, or orien* 
 
 tal topaz. 
 
 d- Orange-coloured topaz. 
 e. The yellowifh green topaz or cljryfoKte. 
 f. The yellowifh green, and cloudy topaz, the 
 
 chryfoprafe (A) 
 
 . Bluifli 
 
 (A) In the Annals of Chemiftry, Vol. I. we have the 
 following account of the method of digging for the 
 chryfoprafes, and of the earths and ftones with which 
 it is accompanied. 
 
 This precious ftone is found in certain mountains in 
 Silefia, which feem to begin thofe of Tradas, extend 
 ing to within half a league of Glatz. Thefe moun 
 tains appear, in general, to confifl of a number of 
 ftrafa, horizontal or inclined, compofed chiefly of fub- 
 
 ftancefr. 
 
C 7' 3 
 
 g. Bluifli green topaz, or the beryl. 
 
 This varies in its colours ; and is called, when 
 
 1. Of a fea-green colour, the aqua-marina. 
 
 2. When more green, the beryl. 
 
 IV. Erne- 
 
 fiances containing magnefia, but likewife mixed with 
 calcareous, argillaceous, and filiceous earths. The 
 greaic.;-, part of thefeconfilt of ferpentinej mixed with 
 afbcllos 'inn amianthus, grey argillaceous earths, 
 boles, and red or green ochres, (lone marrow, ftea- 
 tites, or ibap-ftone, and talc. In thofe mountains 
 alfo we meet with quartz, petrofilex, opal, and chal 
 cedony, in detached fragments, and fomctimes in con 
 tinued veins. We alfo difcover in them veins of fand, 
 of the nature of granite. Sometimes the ferpentine 
 \s met with at the furface ; fometimes at the depth of 
 20 or 30 feet. The ilone marrow feems here to be 
 produced by the decomposition of a very milky fpg- 
 cies of opal agate named dackolong ; for at the depth 
 of 50 feet and upwards the veins of this foapy earth af- 
 fume a degree of folidity, and we find nothing but hard 
 and femitranfparent chacholongs. 
 
 The abovementioned (trata are croiled by a great 
 number of cracks filled with green-coloured earths 
 and (tones ; but thefe frequently do not contain a fingle 
 true chryfoprafus. They ai e fometimes found imme. 
 diately under the vegetable mould, or at the depth of 
 fome feet, in ihapelefs mattes, covered with a heavy- 
 clay, and fometimes enveloped by an uncluous earth of 
 a beautiful green colour, which it derives from the 
 calx of nickel. In other places, the chryfoprafus has 
 been found in uneven laminae of feveral yards in 
 length and breadth, either immediately under the 
 mould, or in the upper ftrata of ferpentine, which have 
 kittle folidity ; and very beautiful ones have been found 
 at the depth of feven or eight fathoms 5 and fome have 
 
 been 
 
C 72 3 
 
 IV. Emerald. Smaragdus gemma. 
 
 Its chief colour is green and tranfparent. It 
 is the fofteft of precious ftones and when heated 
 it is phofphorefcent like the fluors. 
 
 V. To 
 
 been met with in grey clay at the depth of four fa 
 thoms. In fome places alfo they are met with in 
 a kind of red ochre, which is attracted by the magnet ; 
 in others they are found in the clefts of rocks. The 
 beautiful green chryfoprafus is found moil plentifully 
 in the mountain of GlafTendorf. In another moun 
 tain named Kofemutz, where it is alfo found, the pie 
 ces are fo porous, and fo much fpotted with white, &c. 
 that fometimes upwards of 1000 of them have not af 
 forded one large enough for the ufe of the jewellers. 
 The defects are frequently only difcoverable on polifh- 
 ing, as the green opal, while rough, perfectly refem- 
 bles the chryfoprafus ; but, on polifhing the ftones in 
 which it is contained, it is detected by its want of lu- 
 ftre. 
 
 The quantity in which thefe ftones are found is not 
 fufficient to afford the expences of regular mining ; the 
 mod profitable way, therefore, of obtaining them is by 
 making trenches in the earth from four to fix feat 
 deep. Almoft all the mountain of Kofemutz, how 
 ever, has already bee'n examined in this manner ; fo 
 that they now dig for the chryfoprafus in quarries by 
 uncovering a bank of earth or ftone, and deicending 
 to other banks by fteps in the open air, fo as to throw 
 the rubbifh back from bank to bank. This method, 
 however, cannot be continued farther than 24 or 30 
 feet, otherwife the produce would not defray the ex- 
 pence. The only tools employed in digging for the 
 chryfoprafus are a fpade and pick-ax ; the former to 
 remove the earth, the latter to detach the chryfoprafus 
 itfelf from the ftones which furround it. 
 
 Various 
 
I n ] 
 
 V. To the precious ftones belong alfo the jacmths, 
 or hyaeinths ; which are chryftals harder than 
 quartz cryftals, tranfparent, of a fine reddifh- 
 yellow colour when in their full luftre, and form 
 ed 
 
 Various accounts hava been given of the component 
 parts of this precious (lone. Lehmann thinks, that 
 the colour of it is owing to fome ferruginous particles 
 modified in a particular manner : but the experiments 
 he adduces for this opinion are not fatisfaclory. Mr 
 Sage attributes the colour to cobalt from the blue co 
 lour it imparts to glafs. Mr Achard thinks the ftone 
 contains calx of copper as well as calx of iron ; be- 
 caufe a part of the metal feparable from it may be dif- 
 folved in volatile alkali. The following are the expe 
 riments of M. Klapioth upon the fubjeft. 
 
 1. On heating feveral pieces of very pure chryfo- 
 prafus red4iot, and quenching them in water, the co 
 lour was changed from green to bluifh grey : and, 
 on repeating the operation, it became a white giey-. 
 They were found to have loft in weight one and an halt 
 per cent, and were eafily pulverable in a glafs mortar. 
 
 2. Three hundred grains of chryfoprafus were mix 
 ed with double its weight of mild mineral alkali, and 
 the mixture heated for fome hours red hot, in a por 
 celain crucible. The mafs was then powdered, and 
 digefted in diftilled water. By filtration, a yellowifh 
 grey refiduum was obtained, weighing 44 grains ; the 
 filtered liquor was limpid and colourlefs, a copious 
 precipitate bein-g formed with muriatic acid, which be 
 ing wafhed and dried was found to be filiceous earth. 
 
 3. The 44 grains of yellowifh grey refiduum were 
 digefted in a retort, with 552 grains of aqua regia ; a 
 groat part of which w is evaporated. The acid which 
 carrie over was returned into the retort, and filtered 
 after a fecond digeftion. The refiduum was a very 
 
 H fine 
 
[' 74 ] 
 
 ed in prifms pointed at both ends : thefc points 
 are always regular, in regard to the number of 
 the facets, being four on each point ; but the fa 
 cets feldom tally ; the fides alfo which form the 
 
 main 
 
 fine white filiceous earth, which, after being waftied 
 .dried, and heated red hot, weighed 20 grains. 
 
 4. The filtrated folution was of a pale green, but 
 on fuperfaturation with volatile alkali immediately 
 turned of a blu fh colour, precipitating a fmall quan 
 tity of brownifh gelatinous matter ; which, when col 
 lected, twice diftilled with nitrous acid, and afterwards 
 firongly heated, yielded a brown calx of iron, weigh 
 ing no more than a quarter of a grain : whence our 
 author concludes, that iron does not contribute to the 
 colour of the chryfoprafus, as we know many colour- 
 lefs ftones which contain as great a quantity of that 
 metal. This fmall quantity of calx was left after dt- 
 gefting the gelatinous reiiduum. On precipitating 
 the foluble parts, they appeared to coniift of alumi 
 nous earth, in an exceffively divided Mate ; which be 
 ing wafhed and dried, weighed half a grain. 
 
 5. To find whether the folution contained calcare 
 ous earth or not, he mixed with that, fuperfaturated 
 with volatile alkali, a faturated folution of mild mine 
 ral alkal', which precipitated four grains and an half 
 of white and very pure calcareous earth. 
 
 6. Nothing more was precipitated from the folution, 
 either by acids or alkalies, after the feparation of the 
 calcareous earth, though it fall retained a bluiih co 
 lour. It was poured into a retort, and evaporated to 
 drynefs ; the reiiduum was of a yellowilh colour, which 
 became green on being dilfolved in diftilled water. 
 Mild mineral alkali threw down only a little earth of a 
 greeniih white colour ; which being re-diffblved in de- 
 phlogifticated nitrous acid, and precipitated with 
 
 Pruffiaa 
 
[ 75 3 
 
 main body, or column, are very uncertain in re 
 gard both to their number and fhape ; for they 
 are found of four, five, fix, feven, and fometimes 
 of eight, fides ; further the column or prifm 
 
 is 
 
 Pruflian alkali, the liquor yielded 17 grains of a fea- 
 green powder. This precipitate, in our author's opi 
 nion, is the colouring principle of the chryfoprafus ; 
 and this principle heafterwards found to be calx cf 
 nickel. 
 
 7. Our author likewife attempted to analyfe the chry 
 foprafus in the moid way by concentrated viziblic acid ; 
 in which procefs his chief view was to difcover whe 
 ther the ilone contained any volatile particles or not. 
 On an ounce of crude chryfoprafus, therefore, when 
 put into a retort, he poured an equal quantity of recli- 
 fied^vitriolic acid, and two parts of diftilled water. Af 
 ter the latter had pafied over into the receiver, the fire 
 was increafed to force over the fuperabundant acid } 
 a part arofe in white vapours, and fome fell into the 
 receiver with an hiding noife. Boiling water, which 
 had been diftilled, was then poured upon the refi- 
 duum, and the folution filtered. The powdered chry 
 foprafus left on the filter had not been perfectly dilTol- 
 ved, and, in general, had .undergone but little altera 
 tion, fo that he could not by this method determine 
 the component parts. M. Achard, however, was 
 more fuccefsful, and by a fimilar method determined 
 the component; parts of this gem to be five grains of an 
 earth, which, diftilled with vitriolic acid, became vo 
 latile ; eight grains of calcareous earth, fix grains of 
 magnefia, two grains of calx of iron, three grains cf 
 calx of copper, and 456 of filiceous earth. 
 
 M. Klaproth never met with any volatile earth or 
 magnefia in his experiments on this gem ; and there 
 fore concludes, that the chryfoprafus ufed by him had 
 H 2 been 
 
is in feme alfo fo comprefTed, as almoft to re- 
 iemble the face of a fpherical facetted garnet. 
 
 Mr Cronftedt fays, he got foma jacinths of a 
 quadrangular figure, which did not melt in the 
 fire, but only became colourlefs. 
 
 VI. The 
 
 been eflentially different from that made ufe of by 
 M. Achard ; and he feems not to give credit to the 
 account of any copper being found in it. 
 
 8. One part of crude chryfoprafus, well powdered 
 and wafhed with two parts of mild vegetable alkali, 
 yielded a violet-coloured glafs, which in the atmof- 
 phere ran into a brownilli-ccloured liquor. 
 
 9. Five parts of the gem, with four of mild alkali, 
 gave a beautiful violet-coloured glafs after being two 
 hours in fufion. 
 
 io Equal parts of crude chryfoprafus and mild mi 
 neral alkali, yielded a tranfparent glafs in thin laminae, 
 cf a brown colour, refembling that f the tourmalin, 
 the furface being marked with fine reticulated veins ; 
 which veins arofe from fmall grains of very fine redu 
 ced nickel placed in lines againft one another. 
 
 1 1 . Equal parts of crude chryfoprafus and calcined 
 borax, gave a clear, tranfparent, and brown glafs, re* 
 fembling the fmoky topaz. 
 
 12. Equal parts of chryfoprafus, extracled by vitri 
 olic acid and calcined borax, yielded a fimilar glafs of 
 a clear brown colour; " which proves (fays our au 
 thor), that the vitriolic acid was incapable of per 
 fectly analyfmg the chryfoprafus, though I had ufed a 
 double portion of the earth." 
 
 13. Eighty grains of prepared filiceous earth, fixty 
 grains of mild fixed alkali, with the three grains of 
 calx of nickel procured from the chryfoprafus, yielded 
 a beautiful, clear, and violet-coloured glafs. 
 
 14.. Qn fubftituting three grains of calx produced 
 
 from 
 
C 77 3 
 
 VI. The amethyft is a gem of a violet colour,- with 
 great brilliancy, and as hard as the bed kind of 
 rubies or fapphtres, frcm which it only differs 
 by its colour. This is called the oriental ame- 
 
 tlyjl; 
 
 from an ore of nickel, a glafs was produced exactly 
 like the former. 
 
 15. Sixty grains of prepared filiceous earth and caV 
 cined borax, with three grains of calx of nickel from 
 the chryfoprafus, yielded a tranfparent glafs of a clear 
 brown colour. 
 
 1 6. Sixty grains of prepared filiceous earth and vi 
 trified phoiphoric acid, with three grains of calx of 
 nickel from the chryfoprafus, gave a glafs of the co 
 lour of honey. 
 
 17. Thus the attempts of M. Klaproth to recompofe 
 the chryfoprafus proved abortive. From his experi 
 ments, however, he deduces the following conclufions : 
 i. The blue colour obfervable in the glafs produced 
 by fusing the chryfoprafus with vegetable alkali, ariits- 
 entirely from the nickel contained in the gem : and the 
 experiment (hows that the calx of nickel, when puri 
 fied as much as poffihle, has the furpriiing property. 
 of tinging glafs frits prepared with vegetable alkali of 
 a. blue colour,. " But (fays he) why was not this co 
 lour alfo obtained with foda ? and what is the caufe 
 of a difference fo little to be expected?" 2. By thefe 
 experiments the fuppofition of M. Sage is refuted,, 
 that the 1 ' metallic matter which colours the chryfopra 
 fus is cobalt : " many metallic fubftances befides co- 
 foalti it is well known, give by certain procefTes ;i blue 
 glafs; thus cobalt gives a blue colour to cornbma'.ions 
 ef the mineral alkali with phofphoric acid, to mineral 
 alkali itlclf, to potafh, and to borax. The a^i \ of 
 tiingften (falfelyfo calbd) alfo nives a blue col-- 
 
 frits made with phofphoric ialts, but 'not to tl-ioic; m i'Jcr. 
 H 3 with. 
 
C 75 J 
 
 thy/I s and is very rare: when it inclines to the 
 purple, or rofy colour, it is more efteemed than 
 when it is nearer to the blue. 
 
 Thefe 
 
 with borax ; the calx of nickel gives a blue colour on 
 ly to frits made with potafh, brown to thofe with mi 
 neral alkali and borax, and yellow, like honey, to 
 combinations of phofphoric acid with mineral alkali.'* 
 3. As the chryfoprafus gives a brown colour with bo 
 rax, and the foluiion of this (tone in muriatic acid 
 gives no figns of cobalt diflblved in the fame acid ; this 
 fhows that there is no cobalt in the ftone. Mr Sage, 
 indeed, pretends, that he has obtained a blue glafs 
 from the chryfoprafus and borax ; but this is contra 
 dicted by experience. 4. The mineralogical character 
 of the chryfoprafus, therefore, is a quartz coloured 
 green by nickel. Three hundred grains of it contain 
 2887 of filiceous earth calcined to redaefs, one quar 
 ter of a grain of pure aluminous earth, two grains 
 and an half of calcareous earth calcined to rednefs, 
 three grains of calx of nickel, and one quarter of a grain 
 of calx of iron. All thefe were extracted in the expe 
 riments ; and there were befides five grains and an half 
 of wafte. 
 
 Our author mentions, that in the collections of chry 
 foprafus which have been brought to him,, he has con- 
 ftantly observed green opal, in bits of vein from half 
 an inch to an inch, and fixed in its borders : the red- 
 difh, yellow, and white opals, on the contrary, are ge 
 nerally met with on a green or brownifh petrofilex. 
 But the white opal, which, as well as the green, is 
 found in pieces of the nature of matrix, differs from 
 the true opal, approaching the chalcedony and the 
 epaque milky quartzes. This kind of tranfparent 
 opal, radiated with a whitifh blue, contains the fol- 
 fcwjng ingredients in its competition ; Siliceous earth, 
 
 237 
 
C 79 3 
 
 Thefe amethyfts have the fame figure, hard- 
 Befs, fpecific gravity, and other qualities, as the 
 beft fapphires or rubies; and come from the fame 
 places, particularly from Perfu, Arabia, Arme 
 nia, and the Weil Indies. 
 
 The arjethyfts called occidental, are of the 
 fame nature as rock cryllals, and have the fame 
 gradations, viz. of a violet inclining to the 
 purple or rofy colour, or inclining to the blue ; 
 very often they are femi-tranfparent, without 
 any colour in one end, and violet towards the 
 other. The bed are found in the Vic moun 
 tains of Catalonia in Spain, and at Wiefenthal 
 in Saxony, as well as in Bohemia in Germany, 
 in Italy, and in the province of Auvergne in 
 France. 
 
 Cryftals within the geodes, or hollow agathe- 
 balls, are very often found of an amefhyit co 
 lour, and fome are very tine. 
 
 What we call amethyjl root, or mother of ame* 
 tbyjl, is but a fparry fluor, of which there are 
 plenty in Derbyihire : many fine ornamental pie 
 ces are made of this fubftance in different forms 
 and fhapes, Thefe fpars are found in infulated 
 maffes, ibmetimes pretty large ; but never in the 
 form of large rocks. 
 
 VII> The garnet, (Granatus.) This ftcne, when 
 tranfparent and of a fine colour, is reckoned 
 among the gems : but it varies more than any, 
 both in the form of its cryftals and in its colour, 
 
 fome 
 
 237 grains; aluminous earth, a quarter of a grain; 
 calx of iron, a quarter of a grain in all, 23 yt grains. 
 In 240 grains were two and an half of wafte. The 
 colour of this ftone, as well at the chryfoprafus, in our 
 author's opinion, is derived from nickel* 
 
C 80 J 
 
 fome being of a deep and dark red, fome yellow- 
 ijfh and purplifh, and fome brown, blackifh* and 
 quite opaque. In general, their luftre is lefs than 
 that of oiher gems, as well as their hardnefs, 
 which yields to the file, although they may ftrike 
 fire with fteel. But as to rheir form, thefe cry- 
 ftals take almoft all forts of figures, as the rhom- 
 boidal, tetradecaedral, c. and fome ar.e of an 
 irregular form. 
 
 Their colour proceeds from the iron which en 
 ters into their compofition ; and, according to 
 M. de Sauflure, even the fined oriental garnets 
 attracl the magnetic needle at a fmall diftance. 
 
 The Syrian garnet is the fineft and beft efteem- 
 ed. It is of a fine red, inclining to the purple 
 colour, very diaphanous, but lefs brilliant than 
 the oriental amethyft. It feems to be the ame- 
 thyjlizontas of Pliny : the Italians call it rublno di 
 rocca 9 and is found in Syria, Calcutta, Cananor, 
 Camboya, and Ethiopia. 
 
 The fine garnet of a red inclining to a yellow 
 colour,., is the f-;ranus of the ancients,, the *uer- 
 ntdlle of the Fiench, and the giaclnto guarnacino 
 of the Italians. Its name is taken from So- 
 rian t or Surian 9 .a. capital town of Pegu, from 
 whence thetc gems are brought : when they 
 have a browniili taint, they are then called hy 
 acinths. 
 
 The occidental garnet is of a deep and dark 
 red, and its hardnefs is leffer. However,, fome 
 very fine hard garnets are found in Bohemia. 
 Garnets are alfo found in Hungary, at Pyrna in 
 Silefia, at S. Sapho in the canton of B^rne, in 
 Spain, and r n Nonvay. 
 
 The garnet melts in the focuis of a good burn 
 ing gbfs into a brown mafs, which is attracted 
 by the loadstone ; and this ftiows that iron enters 
 e.cnfidcrabiy into its ccmpofition,. 
 
 Some 
 
t ' ] 
 
 Some garnets are found, which contain a little 
 gold. Thofe called ztngraupen by the Germans 
 contain tin, 
 VIII. Tourmalin ; Lapis eleflricits. 
 
 This is a kind of hard ftone, lately brought 
 into notice by its electrical properties. See 
 TOURMALIN. 
 
 j. Its form is a prifm of nine fides of different 
 breadths, moftly truncated, and feldom termi 
 nating in a pyramid at each end, which is ei 
 ther compofed of three pentagons, or of nine 
 triangles. 
 
 2. When heated in the fire, it gives figns of con 
 trary electricity on the two oppofitc- ends of their 
 prifmatic form. But many of thefe ftones are not 
 in the leaft electric. However, on being rubbed, 
 they become electric in their fides, like other dia 
 phanous gems. 
 
 3. It is as hard almoft as the topaz, and ftrikes fire 
 \viih fteeL 
 
 4. It melts by itfelf in a flrong fire, though with 
 difficulty. 
 
 5. With the microcofmic fak it welts perfeftly j 
 but only in part with borax. 
 
 6. With mineral alkali it is divided into a kind of 
 powder. 
 
 7. The three mineral acids diflblve it when firftrc 
 duced to a powder. 
 
 8. It bears a greater fimilarity to fchoerl than 
 to any other ftone : but its component parts 
 fhow that it may be ranged with propriety in 
 this place, along with other precious ftones : as 
 the argillaceous earth is alfo the moft prevalent 
 in its compofition. 
 
 a. The oriental tourmalines are found in the 
 ifland of Ceylon. They are tranfparent, of a 
 dark brown yellow ; and their fpecific gravity- 
 is from 3062 to 3295. 
 
 t. Froia 
 
[ 82 ] 
 
 . From Brafil. Tranfparent. Thefe are green 
 for the mod part ; but there are alfo fome red, 
 blue, and yellow : their fpecific gravity is from 
 3075 to 3180. 
 
 c. From Tyrol. Of fo dark a green as to ap 
 pear opaque. Their fpeciiic gravity is about 
 3050. Thefe are found in beds of ftcatites 
 and lapis-ollaris, among the micaceous veins, 
 talcs, and hornblende of Schneeberg, Jurzagl, 
 and Zillerthal, in the mountains of Tyrol. 
 </. From the mountains of Old Caftile in Spain. 
 Thefe are tranfparent, and have the fame pro 
 perties as the preceding ones. 
 The opal, Opalm ; the girafok of the Italians.- 
 This is the moft beautiful of all the Flint kind, 
 owing to the changeable appearance of its co 
 lours by reflexion and refraction, and mud there 
 fore be ddcribed under both thefe circumftances. 
 The opal of Nonnius, the Sangenon of the Indi 
 ans. This appears olive -coloured by reflection, 
 and feems then to be opaque ; but when held a- 
 gamft the light, is found tranfparent and of a fine 
 ruby red colour. 
 
 There is, however, another of the fame kind 
 in Sweden, which by reflection appears rather 
 brown ; but by refraction it is red, with violet 
 veins. 
 
 The white opal. Its ground is white, of a glafs- 
 like complexion, from whence are thrown out 
 green, yellow, purple, and bluifh rays ; but it is 
 of a reddifh or rather flame-colour when held a- 
 gainft the light. 
 
 a. Of many colours ; the oriental opal. 
 
 b. Of a milky colour. 
 
 c. Bluifh, and femi-tranfparent. This is not 
 fo much valued as thofe which are more o* 
 paque, becaufe it is eafier to be imitated by art. 
 
C *3 ] 
 
 2. Of Quartz. 
 
 This (lone is very common in Europe, and e&fier to 
 be known than defcribed. It is diitinguiftied from 
 the other kinds of the filiceous order by the following 
 qualities : 
 
 1. That it is moft generally cracked throughout, 
 even in the rock itf-lf ; whereby, 
 
 2. As well as by its nature, it breaks irregularly, 
 and into fharp fragments. 
 
 3. That it cannot eafily be made red-hot without 
 cracking ftill more. 
 
 4. It never decays in the air. 
 
 5. Melted with pot-afhes, it gives a more folid 
 and fixed glafs than any other of the filiceous or 
 der. 
 
 6. When there has been no interruption *n its na 
 tural accretion, its fubftance always cryftallifes 
 into hexagonal prifms pointed at one or both 
 ends. 
 
 7- It occurs in clefts, figures, and fmall veins in 
 rocks. It very feldom forms large veins, and ftill 
 feldomer whole mountains, without being mixed 
 with heterogeneous fubftances. 
 
 According to Mr Kirwan, quartz neither lofes 
 its hardnefs nor its weight by calcination. Its 
 texture is lamellar. Thefe ftones are in general 
 the pureft of the filiceous kind, though mod 
 contain a flight mixture of other earths ; the moft 
 obvious diftincHon among them arifes from their 
 * tranfparency or opacity. 
 Quartz is found, 
 (i.) Pure. 
 
 A. Solid, of no vifible particles, with a gloffy fur- 
 fkce. Fat Quartz. 
 
 a. Uncoloured and clear. This has no cryftallized 
 form, but is neverthelefs as clear as quartz cry- 
 ilals of the beft water. 
 
 b. White, 
 
C 84 ] 
 
 b. White, the common fat quartz. 
 <?, Blue. 
 d. Violet. 
 
 B, Grained. 
 
 a. White. I. Pale green. 
 
 C. Sparry quartz. 
 
 This is the fcarceft; and ought not to be con 
 founded with the white felt-fpar, being of a 
 -imoother appearance, and breaking into larger 
 and more irregular planes. 
 a. Whitifh yellow, b. White. 
 Z>. Cryftallifed quartz. Rock cryftal. Quartz 
 cryftal. 
 
 1. Opaque, or femi-tranfparent. 
 
 a. White, or of a milk colour. 
 
 b. Red, or of % carnelian colour. 
 
 c. Black. 
 
 2. clear. 
 
 a. Blackifh brown, fmokey topaz, or raunch topaz of 
 the Germans. 
 
 b. Yellow ; found in Bohemia, and fold inftead 
 of topazes. 
 
 c . Violet ; the amethyft from Saxony, Bohemia, 
 and Dammemore in Upland (B.) 
 
 (B.) The moft tranfparent are called falfe diamonds, 
 Briftol, Kerry Jlones, and Alsngon dlamsnds, &c. The 
 coloured tranfparent cryftals derive their tinge gene 
 rally, from metallic calces, though in exceeding fmall 
 portions: they all lofe their colours when ftrongly 
 heated. Thefe are what we call falfe gems, viz. 
 
 The red, from Oran in Barbary,/2z^ rubies. 
 
 The yellow, from Saxony,/^ topazes, 
 
 The green, from Dauphiny, (very rare) fclfe emeralds, 
 or frnfes. 
 . The violet, from Vil in Catalonia, falff amethyfts. 
 
 'The blue, from Puv in Valay, Franc s, falfe fapphircs. 
 
d. Uncoloured : rock cryftal, properly fo called. 
 When thefe coloured cryftals are not clear, 
 they are called^/> / for inftance, topaz-flufs , 
 ameihyjl fufs ) &c. (c-) 
 (2. Impure quartz. 
 
 A. Mixed with iron, in form of a black calx. 
 This is of a glofly texture, and contains a great 
 quantity of iron. 
 
 B. Mixed with copper in form of a red calx. 
 a. Red. 
 
 There are alfo opal, or rainbow cryjlals^ fome of which 
 make a very fine appearance ; the various colours of 
 which are thrown out in zones acrofs the furface, tho* 
 they never fliine like the oriental opal. 
 
 ( c \ M. Fourcroy makes a remarkable difference be 
 tween the cryftals and the quart/, by affirming that 
 the former are unalterable in the fire, in which they 
 never lofe their hardnefs, tranfparency, nor colour ; 
 whilft the quartz lofes the fame qualities, and is re 
 duced by it to a white and opaque earth. He claffes 
 the rock cryftals, 
 
 i ft, According to their form, viz. i. Infulated-hexa- 
 gonal-cryftals, ending in two pyramids of fix faces, 
 which have a double refraction or fhow two images of 
 the fime object when looked through. 2. Hexagonal 
 cryftals united, having one or two points. 3. Tetrasd- 
 ral, dodecsedral, flated cryfta'is; and which though 
 hexagonal have neverthelefs their planes irregular. 4. 
 Cryilals in large maiTes, from the iiiand of Madagaf- 
 car, which have a fimple refraction. 
 
 2dly, As to the colour, they are either diaphonous, 
 reddiin, fmokey, or blackifh. 
 
 3dly, As to accidental changes, fome are hollow, 
 
 fome contain 'water within one or more cavities : fome 
 
 are cafed, viz. one withjn the other : fome are of a 
 
 round form, as the pebble vf the Rhine; fome have a 
 
 I cruft 
 
3 Of Flints. 
 
 THE flint (Szlex pyromachus, Lapis corneus, or the 
 bornjlim of the Germans) forms a kind of interme 
 diate fubftance between quartz andjafper; both which, 
 however, it fo nearly refembles, that it is not eafy to 
 point out fuch characters as fhall readily diftinguih it 
 from them. We can only, therefore, fpeak of its pro 
 perties comparatively. 
 
 1. It is more uniformly folid, and not fo much 
 cracked in the mafs as the quartz ; and, 
 
 2. It is more pellucid than the jafper. 
 
 3. It bears being expofed to the air without decay 
 ing better than the jafper, but not fo well as the 
 quartz. 
 
 4. It is better for making of glafs than the jafper, 
 but' is not quite fo good as quartz for that pur- 
 pofe. 
 
 5. Whenever there has been an opportunity in this 
 matter of its fhooting into cryftals, quartz cry 
 ftals are always found in it ; juft as if the quartz 
 made one of its conftituent parts, and had in cer 
 tain circumftances been fqueezed out of it ; this 
 is to be feen m every hollow flint and its clefts, 
 which are always filled up with quartz. 
 
 3). It often fhows moft evident marks of having been 
 originally in a foft and flimy tough ftate like glue 
 or jelly. 
 
 cruft of metallic calces, or of a pyrites : Ibme are of a 
 .geodical form, viz, cryftallifed in the infide of a cavity ; 
 fome feem to contain amianthe, or afbeftus, and others 
 contain (hirls. 
 
 The fame author reckons among cryftals, the orien 
 tal topaz, the hyacinth, the oriental fapphire, and th 
 amethyft. Mr Daubenton had always looked on this 
 laft as a quartzous cryftal. 
 
C 87 ] 
 
 The feveral varieties of this fpecies have ob 
 tained more diftincl: names with refpecT: to their 
 colours than from any real difference in their 
 fubftance ; but thefe are ft ill neceflary to be re 
 tained, as the only names ufed by jewellers and 
 others, who know how to value them accord 
 ingly. 
 I. Jade. Lapis nephriticus. jfajpachates* 
 
 The true lapis nephriticus feems to belong to 
 this filiceous order, as it gives fire with fteel, 
 and is femi-pellucid like flint ; it does not har 
 den in fire, but melts by the folar heat in the 
 focus of a burning lens into a tranfpareiat green 
 glafs with fome bubbles. That called by the 
 name of circoncifion Jlone^ which comes from the 
 Amazon river, melts eafier, in the fame folar 
 fire, into a brown opaque glafs, which is far lefs 
 hard than the ftone itfelf. (Macquer.) 
 
 This ftone is fuperior in hardnefs to quartz^ 
 though from its uncluofity to the touch, one 
 would fufpect it to contain a large portion of 
 argillaceous earth, or rather of magnefian earth, 
 as Mr Kirwan feems to fufpect. 
 
 Its fpecific gravity is from 2,970 to 3,389 
 
 It is of a granular texture, of a greafy look, and 
 exceedingly hard: is fcarcely foluble in acids, 
 at leaft without particular management, and is 
 infufible in the fire. M. Saufiure feems to have 
 extracted iron from it. 
 
 a. It is fometimes of a whitilh milky colour, from 
 China : but moftly 
 
 If. Of a greenilh, or 
 
 c. Deep-green colour, from America. 
 
 d. Grey, yellowifK, and olive colour : thefe are the 
 vulgar lapis nephriticus, they being fuppofed to 
 cure the nephritic pains by their external appli 
 cation to the loins. 
 
 I* The 
 
L 83 J 
 
 The femi-pellucidity, hardnefs, and fpecific gra 
 vity, are the characters by which the lapis ne- 
 phriticus may be diftinguilhed from other ftones. 
 
 II. Cat's eye ; Pfeudopalus. The fun-ftone of the 
 Turks, called gunechc. 
 
 This ftone is opaque, and reflects green and yel- 
 lowiih rays from its furface : it is found in Sibe 
 ria. It is very hard and femi-tranfparent, and 
 has different points, from which light is reflected 
 with a kind of yellow-brown radiation, fomewhat 
 fimilar to the eyes of cats, from whence it had 
 its name. Jewellers do not fail to cut them 
 round to the gre.ateft advantage. The beft of 
 thefe ftones are very fcarce. One of thefe of one 
 inch diameter was in the cabinet of the grand 
 duke of Tuicany. 
 
 III. Hydrophanesy or Qculus Mundl ; alfo called Lapis 
 mutabilis. 
 
 The principal property which diftinguifhes this 
 from all other ftones, is that it becomes 
 tranfparent by mere infufion in any aqueous 
 fluid ' 3 but it gradually relumes its opacity when 
 dry. 
 
 IV. The onyx. Onyx camehuja. Memphites. It is 
 found of two forts. 
 
 a. Nail-coloured onyx, having pale fiefh- coloured 
 
 and white lines. 
 I}. With black and white lines. The oriental 
 
 onyx. 
 
 V. The chalcedony, or white agate, is a flint of a white 
 
 colour, like milk diluted with water, more or lefs 
 epaque : it has veins, circles, and round fpots. 
 It is faid to oe fofter t;han the onyx, but much 
 harder than thofe agates which are fometimes 
 found of the fame colour. 
 
 a. The white opaque Chalcedony, or caholong, 
 from the Buckharifh Calmucks. This was firit 
 made known by one Renez, a Swedifh officer, 
 
 who 
 
C S 9 ] 
 
 who for feveral years had been in the country. 
 The inhabitants find this flint on the banks of 
 their rivers and work idols and domeftic vef- 
 fels out of it. 
 
 b. Of white and femi-tranfparent ftrata; from 
 Ceylon. 
 
 c. Bluifh grey : from Ceylon and Siberia. 
 
 VI. The carnelian. Carniolus. 
 
 Is of a brownilh red colour, and often entirely 
 brown. Its name is originally derived from its 
 refemblance to flefh, or to water mixed with 
 blood. 
 
 a. Red. 
 
 b. Yellowilh brown, looks like yellow amber. It 
 is faid not to be fo hard as the chalcedony. 
 
 VII. The fardonyx. 
 
 This is a mixture of the chalcedony and carnelian, 
 fometimes ftratumwife, and fometimes confufedly 
 blended and mixed together. 
 
 a. Stripped with white and red ftrata ; this ferves 
 as well cut in cameo as the onyx. 
 
 b. White, with red dendritical figures. This 
 very much refembles that agate which is called 
 the mocha Jlone ; but with this difference, that 
 the figures are of a red colour in this, infteacl 
 of black, as in that agate. 
 
 Between the onyx, carnelian, chalcedony, 
 fardonyx, and agate, there feems to be no real 
 difference, except fome inexplicable degrees of 
 hardnefs. 
 
 VIII. The agate ; debates. 
 
 This name is given to flints that are variega 
 ted with different colours, promifcuouily blended 
 together : and they are efteemed in proportion to 
 their mixture of colours, their beauty, and ele-- 
 gance. Hence alfo they have obtained variety 
 of names, moftly Greek, as if the bufmefs.of the 
 lapidary in cutting of them, and admiring their 
 I 3 
 
C 90 J 
 
 feveral beauties and figures,had been derived from 
 
 that nation alone *. 
 
 a. Brown opaque agate, with black veins, and 
 
 dendritical figures : the Egyptian pebbles. 
 . Of a Chalcedony colour j debates cbalcedoni- 
 
 fans. 
 
 c. Semi-tranfparent, with lines of a blackifh 
 brown colour, and dendritical figures ; the mo 
 cha ftone. 
 
 d. Semi-tranfparent, with red dots ; Gemma dlvi 
 Stepham. When the points are very minute, fo 
 as to give the ftone a red appearance, it is 
 by fome called Sartlea. 
 
 e. Semi tranfparent, with clouds of an orange co 
 lour. 
 
 f. Deep red or violet, and femi-tranfparent. 
 
 f. Of many colours, or variegated. 
 . Black. 
 IX. Common Flint ; Pyromachus. 
 
 This in reality, is of the fame fubftance as the agate ; 
 but as the colours are not fo ftriking or agreeable, 
 it is commonly confidered as a different fub- 
 ibince. 
 
 a. Blackifh grey, from the province of Skone. 
 /'. Yellow femi-traufparent, from France. 
 
 f. Whitifti grey. 
 
 iL Yellowiih brown. 
 
 * On the fide of a hill near the church of Rothea 
 in Moray, is a quantity of fine agate of elegant red and 
 white colours. It is very hard, heavy, of a fmooth 
 uniform texture, and of a considerable brightnefs ; in 
 which the red are remarkably clear, and finely mixed 
 and ihaded through the ftone. Mr Willamsfays that 
 this is the largeft and moil beautiful agate rock he 
 ever favv ; and fo fine and hard us to be capable of the. 
 bigheft luftre in polifliing. 
 
 When 
 
C 91 3 
 
 When the flints are fmiall, they are in Eng 
 land called /<?/>.!; and the Swedilh failors, who 
 take them as ballaft, call \\izmjingel. 
 X. Chert ; Petrofikx, Lapis Corneus. The bornjlein of 
 
 the Germans. 
 
 This is of a coarfer texture than the preceding, 
 
 and alfo lefs hard, "which makes it confequently 
 
 not fo capable of a polifh. It is femi-tranfparent 
 
 at the edges, or when it is broke into very thin 
 
 pieces. 
 
 a. Chert of a flefh colour, from Carl-Scakt, at 
 the filver-mine of Salberg, in the province of 
 Weftmanland. 
 
 b. Whitilh yellow, from Salberg. 
 
 c. White, from Kriftierfberg, at Nya Kopparberget 
 in Weftmanland. 
 
 d. Greeniih, from Preftguvfm, at Hellefors in 
 Weftmanland. 
 
 Chert runs in veins through rocks, from whence 
 its name is derived. Its fpecific gravity is from 
 2590 to 2700; In the fire, it whitens and de 
 crepitates like filex, but is generally fo fufible as 
 to melt per fe. It is not totally dillblved in the 
 dry way by the mineral alkali ; but borax and 
 microcofmic fait difiblve it without effervefcence, 
 Its appearance is duller and lefs tranfparent than 
 common flint. The reddifti Petro-filex ufed in 
 the Count de Lauragar's procelain manufacture, 
 and called there felt fpat. contained 72 per cent. 
 of filex, 22 of argill, and 6 of calcareous earth. 
 
 There are not yet any certain characters known 
 by which the cherts and jafpers may be di- 
 ftinguifhed from each other: by light, how 
 ever, they can eafily be clifcerned, viz. the for 
 mer (the cherts) appearing tranfparent, and of 
 a fine fparkling texture, on being broken ; 
 whereas the jafper is grained, dull, and opaque, 
 liaving the appearance of a dry clay; The cheit 
 
 is 
 
C 92 1 
 
 is alfo found forming larger or fmaller veins, or 
 in nodules like kernels in the rocks ; whereas the 
 jafper, on the contrary, fometimes conftitutes the 
 chief fubftance of the higheft and moft extend 
 ed chain of mountains. The chert is likewife 
 found plentifully in the neighbourhood of fcaly 
 limeftone, as flints in the ftrata of chalk. What 
 connection there may be between thefe bodies, 
 perhaps time will difcover. 
 
 But flints and agates being generally found in 
 loofe and fmgle irregular nodules, and hardly in 
 rocks, as the chert, it is a circumftance very in- 
 fufficient to eftablifh a difference between them ; 
 for there is the agate-ftone, near Conftantinople, 
 running vein-like acrofs the rock with its coun 
 try of the fame hardnefs, and as fine and tranf- 
 parent as thofe other agates which are found in 
 round nodules at Deux-ponts. We muft, there 
 fore, content ourfelves with this remark con 
 cerning flints, viz. That they feem to be the 
 only kind of ftone hitherto known, of which a very 
 large quantity has been formed in the ihape of 
 loofe or feparate nodules, each furrounded with 
 its proper cruft ; and that the matter which con 
 ftitutes this cruft has been feparated from the 
 reft of the fubftance, in like manner as fandiver 
 or glafs-gall feparates from, and fwims upon, 
 glafs, during its vitrification ; though fometimes 
 the formation of this cruft may be prevented by 
 the too fudden hardening of the matter itfelf. 
 
 Other fpecies of ftones, which are found in loofe 
 pieces or nodules, except ores and fome forts 
 of ftalactites, fhow evidently by their cracks, 
 angles, and irregular figures, that they have been 
 torn from rocks, rolled about, and rubbed againft 
 one another in torrents, or by fome other violent 
 motions of water. 
 
 That 
 
[ 93 ] 
 
 That flints had originally been in a foft Hate, 
 M. Cronftedt obferves, is eafy to be feen in the 
 .Egyptian pebbles, which have impreffions of 
 fmall ftones, fand, and fometimes, perhaps, grafs ; 
 which, however, have not had any ingrefs into 
 the very flint, but feem only to have forced the 
 above agate gall or cruft out of the way. 
 
 $4- VJafpers 
 
 JASPER, jafpis, (the diafpro of the Italians), is a 
 name given to all the opaque flints whole texture re- 
 fembles dry clay and which have no other known qua 
 lity whereby they may be dirlinguifhed from other 
 flints, except that they may be more eafily melted in 
 the fire ; and this quality perhaps may proceed from 
 the heterogeneous mixture, probably of iron. 
 
 I. Pure jafper ; which by no means yet known can 
 be decompounded. 
 
 a. Green with red fpecks or dots : the helio 
 trope, or blood-ftone. 1. Green : . Reu* 
 d. Yellow, e. Red with yellow fpots and 
 veins, f Black. 
 
 II. Jafper containing iron : Jafpis martiales S'mople. 
 A coarfe -grained. 
 
 a. Red and reddifh brown ; finople. 
 B. Steel-grained, or fine-grained. 
 
 a. Reddifh brown ; looks like the red ochre or 
 chalk ufed for drawing ; and has partition 
 veins, which are unctuous to the touch, like 
 a fine clay, and other like kinds. 
 
 C. Of a folid and Ihining texture, like a flag. 
 
 a. Liver-coloured ; and, b, Deep red. c. Yel 
 low. This laft mentioned, when calcined'*, is 
 
 * Near Portfoy in BaniF-ftiire is an extenfive rock 
 of jafper ; fome parts of which contain a beautiful 
 mixture of green and red, which appear finely fhaded 
 
 and 
 
E 94 3 
 
 attracted by the loadftone : and being affayed, 
 yields from 12 "to 15 percent, of iron. 
 
 5. Felt-fpars. 
 
 I. Rhombic quartz; Spatum fcintiflatu. 
 
 This has its name from its figure, but feems to be 
 of the fame fubftance as the jafper. We have not, 
 however, ranked them together, for want of trne 
 marks to diftinguifh the different forts of the flin 
 ty tribe from one another. 
 This kind is found, 
 
 1. Sparry. 
 
 a. White. . Reddifti brown, c. Pale yellow. 
 d. Greenifh. 
 
 2. Cryftallized. 
 
 a. In feparate or diftincT: rhomboidal cryftals. 
 
 II. Labradore ftone ; Spatum rutilum ver/ico'or. 
 
 Its colour is commonly of a light or of a deep 
 grey, and moftly of a blackifh grey : but when 
 held in certain pofitions to the light, difco- 
 vers different varieties of beautiful fhining co 
 lours, as lazuly-blue, grafs-green, apple-green, 
 pea-green ; and feldom a citron-yellow ; fome 
 have an intermediate colour betwixt red-copper 
 and tombac-grey ; befides other colours between 
 grey and violet. Thefe colours are feen for moft 
 part in fpots ; but fometimes in ftripes, on the 
 ifame piece. 
 
 III. White feltlpar ; Terra Silicea Magnefia & fcrro m- 
 timk mixfa. 
 
 This ftone has been defcribed by Mr Bayen : and is 
 found at St Marie aux mines in Lorrain, It is 
 
 and clouded through the body of the ftone when po- 
 lifhed. Mr Williams is of opinion that it would be a 
 very valuable quarry if worked. 
 
 of 
 
[ 95 ] 
 
 of a -white opaque colow, ipotted witli ochre on 
 the outfide. 
 
 6. Of the Garnet Kinds. 
 
 THE fubftances of this ge*w (which is confidered by 
 Cronftedt as an order) are analogous to gems ; fmce 
 all thefe are compofed of the filiceous, calcareous, and 
 argillaceous earths, with a greater or lefs proportion 
 of iron. The opaque and black garnets contain about 
 20 hundredths of iron : but the diaphanous ones only 
 two hundredths of their weight, according to Berg 
 man. The garnets, properly fo called, contain a great 
 er quantity of filiceous earth than the fhirls, and both 
 are now juftly ranked with the filiceous earths. 
 
 The fpecies are, 
 I. Garnet; Granattis. 
 
 This is a heavy and hard kind of (lone, cryftallizing 
 in form of polygonal balls, and moftly of a red, or 
 reddifh brown colour. 
 
 A. Garnet mixed with iron ; Granatus martialis. 
 
 1. Coarfe -grained garnet-ftones, without any par 
 ticular figure; in Swedifli called Granatberg ; 
 in German, Granatjlsm. 
 
 a. Reddifh-brown garnet, b. Whitifii yellow. 
 c. Pale yellow. 
 
 2. Cryftallized garnet. 
 
 a. Black, b. Red : femi-tranfparent, and crack 
 ed; tranfparent. c. Reddifli-yellow ; tranf- 
 parent ; the jacinth, or hyacinth, d. Red 
 difh brown, e. Green, f. Yellowifh-green* 
 g. Black. 
 
 B. Garnet mixed with iron and tin. 
 
 1. Coarfe-grained, without any particular fi 
 gure. 
 
 a. Blackifh-browsn. 
 
 2. Cryftallized. , 
 a. Blackiih-brown. 
 
 I. Light 
 
C 96 ] 
 
 I. Light-green or white. 
 C. Garnet mixed with iron and lead. 
 i. Cryftallized. 
 
 a. Reddifh-brown. 
 II. Cockle, or fhirl. Corneus eryflalllzatus Wallerii ; 
 
 Stannum cryjlallis columnaribus n'tgris Linnai. 
 This is a heavy and hard kind of (tone which fhoots 
 into cryftals of a prifmatical figure, and whofe 
 chief colours are black or green. Its fpecific 
 gravity is the fame as the garnets, viz. between 
 3000 and 3400, though always proportionable 
 to their different folidity. 
 A. Cockle, or fhirl, mixed with iron. 
 
 1. Coarfe, without any determined figure. 
 a. Green. 
 
 2. Sparry. 
 
 a. Deep green, (the mother of the emeralds)., 
 
 from Egypt. 
 I. Pale green. 
 c. White. This occurs very frequently in the 
 
 fcaly limeftones ; and its colour changes 
 
 from deep green to white, in proportion as it 
 
 contains more or lefs of iron. 
 
 3. Fibrous, ftriated cockle, or fhirl : it looks like 
 fibres or threads made of glafs. 
 
 A. Of parallel fibres, a. Black. I. Green 
 c. White. 
 
 B. Of concentrated fibres : The ftarred cockle 
 or fhirl, from its fibres being laid ftellarwife 
 
 a. Blackifh green. />. Light green, c. White 
 
 4. Cryftalli/ed cockle, or fhirl. 
 
 a. Black. To this variety belong moft of thofi 
 fubftances called imperfia a/befit ; and as th< 
 cockle perfectly refembles a flag from at 
 iron furnace, both in regard to its metallic 
 contents and its glaiTy texture, it is no won 
 der that it is not foft enough to be takei 
 for an a&eftus. It has, however, only fo: 
 
 2 til. 
 
E 97 ] 
 
 the fake of its ftru<5hire, been ranked among 
 the afbefti. The ftriated cockle, cr fliirl, 
 compared to the aibefti, is of a fhining and 
 angular furface (though this fometimes re 
 quires the aid of the magnifying-glafs to 
 be difcovered) always fomewhat tranfpa- 
 rent, and is pretty eaiily brought to a glaf? 
 with the blow-pipe, without being confum- 
 ed as the pure afbefti feem to be. 
 
 b. Deep green. 
 
 c. Light green. 
 
 d. Reddilh brown. The tanffsteln is of this 
 colour, and confifls of two hexagonal cry- 
 ftals of cockle grown together in form of a 
 crofs ; this the Roman Catholics wear as an 
 amulet, and is called in Latin lapis crucifer, 
 or the crofs (lone. 
 
 The figure of the cockle cryftals is uncertain, 
 but always prifmatical : the cockle from Yxfio, 
 at Nya Kopparberg, is quadrangular : the French 
 kind has nine fides or planes; and the tauffsteia 
 is hexagonal. 
 
 The naine cockle for thefe fubflances is an old 
 Cornifh mineral name ; but is alfo given fometimes 
 to other very different matters. 
 
 There is not in England any great quantity of 
 fpecies of cockles ; the chief are found in the tin 
 mines of Cornwall, and fome fine cryftallizecl 
 kinds have been brought from Scotland. 
 
 The Englifli mineral name of call, has been ufed 
 by fome authors as fynonymous with cockles, and 
 they are confounded together at the mines ; but 
 the call, definitely fpeaking, is the fubftance call 
 ed wolfram by the Germans, &c. 
 
 Garnets, though fmall, are often found in mica 
 ceous (tones in England j but extreme good gar 
 nets are found in great plenty alfo in like ftones 
 in Scotland. 
 
 K III. 
 
gil, ar 
 IV. Silic 
 
 III. Rowley rag, (Kirivan). This flone is of a 
 dufky or dark grey colour, with numerous minute 
 iliining cryftals. Its texture is granular : by ex- 
 pofure to the air it acquires an cchry cruft. Its 
 fpecilic gravity is 2748. Heated in an open fire 
 it becomes magnetic. In ftrong heat it melts 
 fer fe, but with more difficulty than bafaltes. 
 According to Dr Withering's analyfis, 100 parts 
 of it contain 47,5 of filiceous earth, 32,5 of ar- 
 ;il, and 20 of iron. 
 
 Siliceous muriatic fpar, (Id) This done is of 
 a hard, folid, and fparry texture ; of a grey, 
 cchry, dull colour, but internally bright. It gives 
 fire with fteel : yet it eifervefces with acids. In 
 a ftrong heat it grows brown ; but at la ft it melts 
 per fe. One hundred parts of this ftone contain 
 fifty parts of lilex : the remainder is mild mag- 
 reiia and iron ; but in what proportion is not 
 mentioned ( See Journal de PJmfijyue t Supplement, 
 vol. xiii. p. 216. 
 
 V. Turky ftone ; cos Tunica. (LI.) This ftone is 
 cf a dull white co^ur, and often of an uneven 
 colour, feme pans appearing more compadt than 
 others, fo that it is in ibme meafure ihattery. It 
 is ufed as a whetilone : and thofe of the fir.eft grain 
 are the heft hones for the rnoft delicate cutting 
 tools, and even for razors, lancets, &c. Its fpe- 
 ciftc gravity is 2598. It gives fire with fteel ; 
 yet efFervefces with acids. Mr Kirwan found 
 that ico parts of it contains 25 of mild calcareous 
 earth, and no iron. There probably are two forts 
 cf ftones known by this name, as Mr Wallerius 
 affirms, that which he clefcribes neither to give 
 fire with fteel nor efFervefce with acids. 
 
 VI. Ragg ftor.e. The colour of this ftone is grey. 
 Its texture is obfcurely laminar, or rather fibrous, 
 but the lamince or fibres confift of a congeries of 
 trains of a quartzy appearance, coarfe and rough. 
 
 Its 
 

 [ 99 3 
 
 Its Specific gravity is 2729. It efFervcfces with 
 acids ; and gives fire with fteel. Mr Kirwaa 
 found it to contain a portion of mild, calcareous 
 earth, and a fmall proportion of iron. It is ufcd 
 as a whet-ftone for coarfe cutting tools. 
 
 [The filiceous grit, cos arenariusy and other 
 compounds of the filiceous earth, c. will be 
 found in a fubfequent divifion of this article.] 
 
 Oyervations on the economical Ufes of the Siliceous Order* 
 
 THE Europeans have no farther trouble with th'j 
 precious ftones than either to cat them from their na 
 tural or rough figure, or to alter them when they have 
 been badly cut in the Eall Indies j in which latter cir- 
 cumftances they are called labora : and it may be oh- 
 fervcd, that for cutting the ruby, fpinell, balks, and 
 chryfolite, the oil of olive is required, infte.id or any 
 other liquid, to be mixed with the diamond powder, 
 in the fame manner as for cutting the diamond it- 
 ftlf. 
 
 If the petty princes in thofe parts of the Indies, 
 where precious ftones are found, have no other power 
 nor riches proportionable to the value of theie gems, 
 the reafon of it is as obvious as of the general weak- 
 nefs of thofe countries where gold and filver abound, 
 viz. becaufe the inhabitants, placing a falfe confidence 
 in the high value of their poffeffions, neglect ufeful 
 manufactures and trade, which by degrees produces a 
 general idlenefs and ignorance through the whole 
 country. 
 
 On the other hand, perhaps, fome countries might 
 fafely improve their revenues by fuch traffic. In 
 Saxony, for example, there might probably be other 
 gems found befides aqua marines and topazes ; or 
 even a greater trade carried on with thefe than at pre- 
 fent, without danger of bad confequences, efpecially 
 under the direction of a careful and prudent govern 
 ment. 
 
 K 2 The 
 
C IGO ] 
 
 The half-precktu ftones, fo called, or gems of lefs 
 value, as the common opal, the onyx, the chalcedony, 
 the cornelian, and the coloured and colourlefs rock 
 cryftals, have been employed for ornaments and econo 
 mical utenfils, in which the price cf the workmanfhip 
 greatly exceeds the intrinfic value cf the (tones. The 
 ancients ufed to engrave concave and convex figures 
 on them, which now a-days are very highly valued, but 
 often with lefs reafon than modem performances cf 
 the fame kind. Thefe ftones are worked by means of 
 emery on plates and tools cf lead, copper, and tin, or 
 with other ind ruments : but the common work on 
 agates is performed at Oberftein with grind-Mones at 
 a very cheap rate. When once fuch a manufactory is 
 eftabliihed in a country, it is neceffary to keep it up 
 with much induftry and prudence, if we would wifh it 
 to iiii-mount the caprice of fafhions ; fmce, how much- 
 icev.cr the natural beauties of thcfe itonek feem to 
 plead l\r tk;,:v pre-eminence, they will at feme periods 
 unavoidably fink in the eikem cf mankind j but they 
 will likewiie often recover, and be reilored to their 
 former value. 
 
 The grindflones at Oberfiein are cf a red cclcur, 
 and of itich particular texture, that they neither be 
 come fmooth, nor are they of too loofe a ccmpofitior. 
 
 Moft part cf the flinty tribe is employed for ma- 
 Jang glafs, as the quartz, the flints, the pebble?, and 
 the quartzofe fands. The quartz, however, is the 
 bell ; and if ufed in due proportion with refpect to the 
 alkali, there is no danger of the glafs being eafily at 
 tacked by the acids, as has fometimes happened with 
 glafs made of other fubitances, of whicli we had an 
 inftance cf bottlts filled with Khenifh and Mofelle 
 wines during the time cf a voyage to China. 
 
 In the fmelting of copper ores, quartz is ufed, to 
 render- the flag glaify, or to vitrify the iron ; quartz 
 being more ufeful than any other ftor.e to prevent the 
 calcination of the rcetah 
 
 The 
 
I 1 01 ] 
 
 The quartzofe fand which conftitutes part of many 
 ftones, and is alfo ufed in making crucibles and fuch 
 veifels contributes mod of all to their power of refill 
 ing fire. 
 
 It appears likewife probable that the quartzofe: 
 matter makes the grind and whetftone fit for their in 
 tended purpofes. (Magellan.} 
 
 Order V. The ARGILLACEOUS EARTHS. 
 
 THE principal character whereby thofe may be di- 
 ftinguifhed from other earths is, that they harden in 
 the fire, and are compounded of very minute particles, 
 by which they acquire a, dead or dull appearance when, 
 broken. 
 
 I. Argilla aerala ; lac luna*. 
 
 This fancimi name was heretofore thought to de 
 note a very fine fpecies of calcareous earth ; but 
 Mr Screber has lately ftiown, that the earth to 
 which this name is given, is a very uncommon 
 fpecies of argill. It is generally found in fmall 
 cakes of the hardnefs of chalk j and like that, if 
 marks white. Its hardnefs is nearly as that to 
 fteatites, and it does not feel fo fat as common 
 clay does. Its- fpecific gravity is 1669 ; its co 
 lour fnow white. When examined with a micro- 
 fcope, it is found to conlifl of fmall tranfpa- 
 rent cryftals; and by his experiments it appears 
 plainly to be an argill faturated with fixed air. 
 It effervefces with acids, and contains a very fmall 
 proportion of calcareous earth and fome times of 
 gy.pium,, befides fonie feeble traces of iron. It 
 is found near Halles. 
 
 II. Porcelain clay ; Terra porcellanea, vulgo Argylla 
 
 apyra y very refractory ; the kaolin of the Chinefe, 
 CL) Pure. 
 
 A. Diffufible in water. 
 i. Coherent and dry. 
 A. White. 
 
 K 3. 2.. Friable" 
 
[ 102 ] 
 
 2. Friable and lean. 
 
 a. White. 
 
 (2.) Mixed with phlogifton. 
 A. DifFufible in water. 
 
 a. White and fat pipe clay. I. Of a pearl colour. 
 r . Bluifti grey. cL Grey. e. Black. /. Violet. 
 Thefe contain a phlogifton, which is difcovered 
 by expofmg them to quick and ftrong fire, in 
 which they become quite black interiorly, afTuming 
 the appearance of the common flints, not only in 
 regard to colour, but alfo in regard to bardnefV: 
 but if heated by degrees, they are flrft white, and 
 afterwards of a pearl colour. The fatter they feem 
 to be, which may be judged both by their feeling 
 Tmooth and unctuous, and by their flnning when 
 fcraped with the nail, they contain a larger quanti 
 ty of the inflammable principle. It is difficult to 
 determine, whether this ftrongly inherent phlogifton 
 be the caufe of the abovementioned pearl-colour, 
 or prevents them from being burnt white in a ftrong 
 fire ; yet no heterogeneous fubftance can be extracl- 
 cd from them, except fand, which may be feparated 
 from fome by means of water ; but which fand does 
 not form any of the condiment parts of the clays. 
 If they be boiled in aqua regis in order to extract 
 any iron, they are found to lofe their vifcofity. 
 Ill, Stone-marrow; Lithomarga Kiffikil of the Tar 
 tars. 
 
 1. When dry, it is as fat and ilippery as~ foap ; 
 but, 
 
 2. Is not wholly diffufible in water, in which it 
 only falls to pieces, either in large bits, or re- 
 femhles a; curd-like mafs. 
 
 3. In the fire it eafily melts to a white or reddiih 
 frothy flag,, confequently is of a larger volume 
 than the clay was before being fuied. 
 
 4. It breaks into irregular fcaly pieces. 
 
 A, Of coarfe particles :.Coarfe ftone -marrow. 
 
 t:. Ore}; 
 
a. Grey, 
 
 B. Whitifh yellow, from the Ciim Tartary, 
 where it is called keffekil, and is faid to- be 
 ufed for wafhing inftead of foap. 
 . Of very fine particles ; fine ftone-marrow. 
 
 a. Yellowifh brown ; Terra Lemma. Is of a 
 fhining texture, falls to pieces in the water 
 with a crackling noife ; it is more indura 
 ted than the preceding, but has otherwife the 
 fame qualities. 
 IV. Bole, (iron clay.) 
 
 This is a fine and denfe clay of various colours, 
 containing a great quantity of iron, which makes 
 it impoflible to know the natural and fpecifical 
 qualities of the bone itfelf, by any eafy method 
 hitherto in ufe. It is not eafily foftened in wa 
 ter, contrary to what the porcelain and the com 
 mon clays are, ( I. and VI. ) ; but either falls to 
 pieces in form of fmall grains, or repels the wa 
 ter, and cannot be made ductile. In the fire it 
 grows black, and is then attracted by the loadftone. 
 A. Loofe and friable boles, or thofe which fall to a> 
 powder in water. 
 
 a. Flefh-coloured bole. 
 
 b. Red. 
 
 1. Fine ; Bolus Ar menus, 
 
 2. Coarfe ; JBolus communis officinalis. 
 
 3. Hard ; Terra rulrica. 
 c* Green ; Terre verte. 
 
 1. Fine. 
 
 2. Coarfe. 
 
 d. Bluiih grey, is ductile as long as it is in the 
 rock, but even then repels the water ; it con 
 tains 40 per cent, of iron ; which metal be 
 ing melted out of it in a clofe veflel, the iron 
 cryftallizes on its lurface. 
 
 t. Grey. 
 
 i. Chryftal- 
 
C 104 ] 
 
 . I. Cryftallized in a fpherical polygonal fi 
 gure. 
 
 2. Of an unde terminate figure. 
 JB. Indurated bole. 
 
 A. Of no vifible particles. 
 
 This occurs very often in form of flate, or 
 layers, in the earfh ; and then is made ufe of as 
 an iron ore. However, it has ufually been 
 corifidered more in regard to its texture than 
 to its conftituent parts ; and has been called 
 jlats, in common with feveral other earths 
 which are found to have the fame texture. 
 a. Reddifh-brown ; in moft collieries, betweea 
 
 the feams of coal. 
 ' b. Grey. 
 
 B. Of fcaly particles. The hornblende of the 
 Swedes. 
 
 It is diflinguifhed from the martial glimmer, 
 or mica, by the fcales being lefs ihining, thicker,- 
 and rectangular. 
 a. Black. This, when rubbed fine gives a 
 
 green powder. 
 b- Greenifh.. 
 V. Zeolyte. 
 
 This is defcribed in its indurated data in the 
 Tranfactions of the academy of fciences at Stock 
 holm for the year 1756, and there arranged as 
 a Rone fut generis in regard to the following qua 
 lities. 
 
 1. It is a little harder than the fluors and the* 
 other calcareous fpars ; it receives, however, 
 fcratches from the fteel, but does not itrike 
 fire with it. 
 
 2. It melts eafily by itfeif in the fire, with a, 
 like ebullition as borax does, into a white 
 frothy flag, wbich cannot without great dif 
 ficulty be brought to a iblidity and tranfpa- 
 
C '05 ] 
 
 3. It is more eafily ditfblved in the fire by the 
 mineral alkali (fai fod*), than by borax or 
 the microcofmic fait. 
 
 4. It does not ferment with this lad fait, as lime 
 does ; nor with the borax, as thofe of the 
 gypfeous kind, 
 
 5. It diflblves very flowly, and without any 
 effervefcence, in acids, as in oil of vitriol 
 and fpirit of nitre. If concentrated oil of 
 vitriol be poured on pounded zeolites, a heat 
 arifes, and the powder unites into a mnis. 
 
 6. In the very moment of fufion it gives a 
 phofphoric light. 
 
 There have lately been difcovered fome of 
 the zeolites, particularly at Adelfors's gold 
 mines in SmolanJ, in Sweden ; of which 
 fome forts do not melt by themfelves in the 
 lire, bat diilblve readily in the acid of nitre, 
 and are turned by it into a firm jelly. 
 The zeoiyte is found hi an indurated ftate : 
 
 (i.) Solid, or cfnovifible particles. 
 
 A. Pure. 
 
 a. White. 
 
 B, Mixed with filver and iron. 
 
 a. Blue, Lapis laxuli. 
 
 (2.) Sparry zeolite. Th : s refembles a calcareousfpar, 
 though it is of a more irregular figure, and is more 
 brittle. 
 
 a. Light red, or orange-coloured. 
 (3.) Cryftalliled zeolite. This is more common 
 than the two preceding kinds; and is found, 
 
 A. In groupes of cryftals, in form of balls, and 
 with concentrical points. 
 
 a. Yellow, 
 
 b. White. 
 
 B. Prifmatical and truncated cryftal?* 
 
 a. White. 
 
 C. Capillary 
 
[ io6 ] 
 
 C. Capillary cryftals, which are partly united in 
 groupes, and partly feparate. In this latter 
 accretion they refemble the capillary or fea 
 thery filver ere: and are perhaps iometimes call* 
 z&fbs ftrri, at places where the nature of that 
 kind of ftone is not yet fully known, 
 
 a. White. 
 VI. Tripoli. 
 
 This is known by its quality of rubbing or wear* 
 ing hard bodies, and making their iuriaces to 
 ihine ; the particles of the tripoli being fo line 
 us to leave even no (cratches on the furface. This 
 effect, which is called poltjkirtg t may likewife be 
 cffecled by other fine clays wjien they have been 
 burnt a little. The tripoli grows fbxnewhat 
 harder in the fire, and is very refractory : it is 
 with difficulty diflblved by borax, and ftill with 
 greater difficulty by the microcofrnic fait. It 
 becomes white when it is heated : when crude, 
 it imbibes water, but is not difiuflble in it : it 
 lafteslike common chalk, and is rough and fandy 
 between the teeth, although no fund can by any 
 means be feparated from it. It has no quality 
 common with any other kind of earth, by which 
 it might be ccnfidered as a variety of any other. 
 That which is here deicribed is of a yellow co 
 lour, and is fold by druggtfts. This kind of 
 tripoli has been lately discovered in Scotland. 
 But the rotten- fione, fo called, is another fort 
 found in England, viz. in Derbyfhire, It is 
 in common tife in England among workmen for 
 all forts of finer grinding and polifhing, and is 
 alfo fometimes ufed by lapidaries for cutting of 
 ftones, &c. 
 The tripoli is found, 
 
 i. Solid : of a rough texture. 
 
 a. Brpwn. 
 
 b. Yeilowifk 
 
 c. Spotted 
 
 
[ 107 1 
 
 e. Spotted like marble. 
 2. Friable and compact. 
 
 a. Granulated. 
 
 b. Brown. 
 
 c. Yellowifli. 
 
 VII. Common clay, or brick clay. 
 
 This kind may be diilinguifhed from the other clays 
 by the following qualities : 
 
 1. In the fire it acquires a red colour, more or 
 lefs deep. 
 
 2. It melts pretty eafily into a greenifli glafs. 
 
 3. It contains a fmalt quantity of iron and of the 
 vitriolic acid, by which the preceding effects are 
 produced. 
 
 It is found, 
 
 A, Diffufible in water. 
 i. Pure. 
 
 a. Red clay. 
 
 /;. Fleih-coloured, or pale-red. 
 c. Grey. 
 </. Blue. 
 f . White. 
 
 f. Fermenting clay. 
 
 2 Mixed with lime. See MARLE, above, 
 . Indurated. 
 
 1. Pure. 
 
 a. Grey flate. 
 
 b. Redflaty. 
 
 2. Mixed with phlogifton, and a great deal of 
 the vitriolic acid. See ALUM Ores, above. 
 
 3. Mixed with lime. Sec LIME, above. 
 
 VIII. Argillaceous fiflile (tones. 
 
 Thefe and many other different kinds cf earth 
 have been comprehended under the denomination 
 Qfjchiftt} but to avoid ambiguity we will confine 
 this name to ftones of the argillaceous kind. 
 i. The bluifli purple fchiilus, or common roof 
 
 (late ; fchiflus tegit/aris. 
 
 Its 
 
[ io8 ] 
 
 Its colour varies to the pale, to the {lightly 
 
 purple, and to the bluifh. 
 
 a. The dark-blue zte,f<:hi/liis fcriptorius. 
 
 2. The pyritaceous fchiftus. 
 
 This is of a grey colour, brown, blue, or 
 ; ' black. 
 
 3. The bituminous fchiftus. 
 
 This is generally black, of a lamellar tex 
 ture, and of different degrees of hardnefs. 
 
 4. Flag ftone. 
 
 This is of a grey, yellowifh, or reddifh white 
 colour. 
 
 5. The argillaceous grit. 
 
 This is called alio fandjlone and free Jtone, be- 
 caufe it may be cut eafily in all directions. 
 
 6. Klllas. 
 
 This ftone is of a pale grey or greenifli co 
 lour ; either lamellar, or coarfely granular. 
 It is found chiefly in Cornwall. 
 
 7. Toad/lone. 
 
 Dr Withering, who has given an analyfis of 
 this ftone, defcribes it as being of a dark 
 brownifh grey colour, of a granular texture, 
 not giving fire with fteel, nor effervefcing 
 with acids. It has cavities filled with cryftal- 
 lifed fpar, and is fufible per fe in a ftrong 
 heat. It is found in Derbyiliire. See TOAD- 
 STONE. 
 
 For the ceconomical ufes of the argillaceous 
 earths, fee the article CLAY. 
 
 [The compounds of this and other earths will 
 fall to be mentioned under a fubfequent divi- 
 iion.] 
 
 CLASS II. SALTS. 
 
 BY this name thofe mineral bodies are called which 
 
 can be diflolved in water; and give it a tafte ; and 
 
 which have the power, at leaft when they are mixed 
 
 i with 
 
[ io 9 ] 
 
 with one another, to form new bodies of a folid and 
 angular ftiape, when the water in which they are dif- 
 folved is diminilhed to a lefs quantity than is required 
 to keep them in iblution ; which quality is called cry- 
 Jlall'tfation. 
 
 In regard to the principal known circ am (lances or 
 qualities of the mineral- falts, they are divided into 
 
 1. Acid falts, or mineral acids. 
 
 2. Alkaline falts, or mineral alkalies. 
 
 Order I, ACID SALTS. 
 
 FOR the characters, properties, and phenomena of 
 thefe, fee the article ACID, and CHEMISTRY-/^^. 
 
 Till of late no more mineral acids were known 
 than the vitriolic and marine ; the boracic or fedative 
 fait being reckoned as produced artificially : but later 
 difcoveries have proved that we may reckon at leaft 
 eleven m'mtral acids ; out of which only two or three 
 have been found in an uncombined ftate. Thofe hi 
 therto known are the following, viz. the vitriolic, the 
 nitrous, the marine, the fparry, the arfenical, the rnolyb- 
 denic, the tvngjlemc, the phofphoric, the boracic, the fuc~ 
 cinous, and the aerial,. See the article ACID, and 
 C H E M i s T R y- Index. 
 
 I. The vitriolic acid. See CHEMISTRY-//^*. 
 
 II. Nitrous acid. 
 
 This acid is by fome excluded from the mineral 
 kir^dom, becaufe they fuppofe it to be pro 
 duced from putrefaction of organic bodies. But 
 thefe bodies, when deprived of life, are again re 
 ceived amongft foffils, from whence their more 
 fixed parts were originally derived. For the na^ 
 ture of this acid, See CHEMISTRY-/^;*, 
 
 III. Acid of common or fea-falt. See CHEMISTRY- 
 Index, at Acid and Marine. 
 
 IV. The Jiuor acid, or fparry fluor acid. See CHE- 
 
 L This 
 
This acid is obtained by art, as it has never been 
 found difengaged, but united to calcareous earth, 
 forming a fparry fluor, called Derbyjlire Jttior, 
 Cornifbjftuor) blue jfohn, or amcthyjl root, when of a 
 purple colour. See p. 72. col. 2. concerning the 
 fubitances arifing from the combination of this 
 acid with calcareous earth* 
 
 V. The acid of arfenic. See CHEMISTRY-//^/*?*. 
 
 VI. The acid of molybdena. Ibid. 
 
 VII. The acid vitungjlcn. Ibid. 
 
 VIII. The phofphork acid. Ibid. 
 
 IX. The loracic acid. Ibid. 
 
 X. The fuccinous or amber acid. Ibid. 
 XL Aerial acid, orfaedair. Ibid. 
 
 Order II. ALKALINE MINERAL SALTS. 
 
 FOR the characters, properties, and phenomena of 
 thefe, fee the article ALKALI; alfo CHEMISRTY-//W&JC, 
 at AlMy Alkalies. 
 
 New acids are daily detected : but no additions have 
 been made to the three fpecies of alkali long fince known. 
 
 Thefe alkali falts are, 
 I. Vegetable fixed alkali (A.) 
 
 (A) With regard to the origin ot' the vegetable fixed 
 alkali, there are fnfficient proofs that it exifts already 
 formed in plants, and alfo that a portion is if rmed by 
 combuflion : but in each cafe, the alkali is obtained in 
 an impure (late, through the admixture of other mat 
 ters, which mull be feparated before it can be ufed for 
 chemical purpofes. 
 
 The ctiidres gra velees are made by burning the hulks 
 of grapes and wine lees. They contain the pureft alka 
 li met with in common, and are ufed by the dyers. 
 
 Pot-afh is made by burning wood and other veget> 
 ables. This alkali is much phlogifticated, and con 
 tains 
 
[ III ] 
 
 Vegetable fixed alkali, deprived of every acid, 
 is not found any where by itfelf ; but it is fome- 
 times met with in combination with the vitriolic 
 acid or the muriatic, generally with the nittous, 
 rarely with the aerial (B.) 
 
 The fixed vegetable alkali (or potciffe of Morveau), 
 is of a powdery appearance, and of a dead white 
 colour. When pure, it is much more cauftic 
 than the neutral fait ; it forms with the aerial 
 acid, and even corrodes the (kin (c.) 
 
 tains many foreign and faline matters, which, however* 
 niay.befeparated. 
 
 That which is obtained from the afhes of wood 
 burned in kitchens is the moft pure of all. On the con 
 trary, that which is got from tartar, properly burned, 
 then diflblvecl in boiling water, and purified by filtra 
 tion and cryftallifation, is called ^/f of water. It is the. 
 bcft. 
 
 (B) The vegetable alkali is feldom found in the 
 enrth, except in wells of towns, as at Doway, or in the 
 argillaceous alum-ore of la Tolfa : it is found alfo unit 
 ed to the nitrous acid, near the furface of the earth, in 
 Spain, and in the Eaft-Indies, probably from the putre 
 faction of vegetables. 
 
 (c) Common vegetable alkali, fait of tartar, and 
 pot-aih, were formerly confidered by chemifts as fimple 
 alkalis ; but Dr Black has demonftrated them: to be 
 true neutral falts, arifmg from the combination of 
 the vegetable alkali with the aerial acid, From hence 
 it follows, that the above common alkalies, even after 
 any other extraneous fubftance has been extracted, 
 muft be freed from this acid, by putting each in a 
 crucible, and expofmg it to a ftrong fire, which will 
 didipate this aerial acid. The alkali fo purified, is to 
 be put in a glafs vial before it be entirely cold, and 
 kept clofev?ith a proper (lopple; othervvife the aerial 
 L z acid 
 
C n2 J 
 
 1. It changes the blue colours of vegetables into a 
 deep green. 
 
 2. It has no fmell when dry ; but when wetted, it 
 has a flight lixivious odour. 
 
 3. Its tafte is ftrongly acrid, burning, cauftic, and 
 urinous (D). This latt fenfation arifes from the 
 volatile alkali it difengagesfrorn animal fub (lances. 
 
 4. When expofed to the air, it attracts humidity, 
 and is reduced into a tranfparent colourlefs li 
 quor. According to Gellert, it attracts three 
 times its own weight of water. 
 
 5. It likewife attracts fometimes the aerial acid 
 from the atmofphere, and is thereby deprived of 
 its property of deliquefcing. 
 
 6. When it is diflfolved in an equal weight of wa 
 ter, it has an oily feel, owing to its action oa the 
 fatty parts of the fkin, whence it is, though im 
 properly, called oil of tartar. 
 
 -. In a moderate heat it melts ; but in a more vio 
 lent fire, it is difperfed or volatilifed. 
 
 8. It is a moil powerful folvent by the dry way : 
 in a proper heat, it diflblves calcareous, argilla 
 ceous, filiceous, and metallic earths : and when 
 the alkali is nearly equal in quantity to the earth, 
 it forms various kinds of hard, folid, and tranf 
 parent glafs. 
 
 9. But if the alkali be in quantity three or four 
 times that of the earth, the glafs is deliquef- 
 cent. 
 
 acid which floats in large quantities on the atmofphere 
 will combine again with the pure alkali. ( Mongez.) 
 
 (D) The alkali muft ba largely diluted with water, 
 in order to be tafted ; otherwife it will act on the 
 tongue, and corrode the parts where it touches. (Mac- 
 quer.) 
 
 10, Tht 
 
C "3 I 
 
 10. The mild vegetable alkali unites with the vi 
 triolic acid with a violent effervefcence, and pro 
 duces vitriolated tartar. 
 
 11. With the nitrous acid, it forms the cryftalli- 
 fable fait, called nitre. 
 
 12. With the marine acid it forms a kind of faltlefs 
 grateful than common fait, which is called the 
 
 febrifuge fait of fyhius. . 
 
 13. With vinegar it forms a neutral deliquefcent 
 fait of a {harp tafte, called terra foliata tartari. 
 
 14. With cream of tartar it forms tartarized tartar. 
 
 15. It diffolves fulphur, and forms the fubftance 
 called livsr of fulphur , winch is a powerful folvent 
 cf metallic fubftances. 
 
 1 6. It attracts the metals, and diffolves fome of 
 them with peculiar management. Silver, mer 
 cury, and lead, are more difficultly diffolved than 
 gold, platina, tin, copper, and efpecially iron. 
 The lad gives a line reddiili faffron colour, fir ft 
 obferved by Stahl, who called it the martial al 
 kaline tincture* 
 
 17. It diffolves in the dry way all the dephlogifti- 
 cated metallic calces. 
 
 1 3. It unites with oils and other fat fubftances,. 
 with which it forms foap. 
 
 19. This alkali becomes opaque when expofed to 
 the flame of the blow-pipe : it decrepitates a 
 long time, and forms a glaffy button, which is 
 permanent in the little fpoon ; but is abfoib- 
 ed with fome nolle on the charcoal when blown 
 upon it. 
 II. Foffile fixed alkalis. 
 
 A. Alkali ofthefea, or of common fait (E.) 
 
 (E) This fait is not met with pure in Europe ; but 
 
 it is faid to be found in both the Indies, not only in 
 
 great quantity, but likewife cf a tolerable purity: it is 
 
 L 3 there 
 
L 4 3 
 
 i. Pure. 
 
 This has nearly the fame qualities with the 
 lixivious fait, which is prepared from the allies 
 of burnt vegetables. It is the fame with the 
 fal fod<z, or kelp : for the kelp is nothing 
 elfe than the allies remaining,, after the burn 
 ing of certain herbs that abound in common 
 fait ; but which common fait, during the 
 burning of thofe vegetables, has loft its acid 
 (F). 
 
 The properties of the foffile alkali are as 
 follows : 
 
 there collected in form of an efflorefcence in the ex- 
 teniive deferts, a profitable trade being carried on in 
 it for the making of foap and glafs ; and, therefore, it 
 is very probable that the ancients meant this fait by 
 their natron or bavrack. (Magellan.) 
 
 (F) The mineral alkali is often combined with 
 the vitriolic and marine acid, alfo with the aerial 
 acid ; with which laft it retains not only the name but 
 many of the properties of a pure alkali, becaule this 
 lail acid is eafily expelled. 
 
 It is eafily known by its cryftallifation and its folu- 
 bility in two times and an half of its weight of water, 
 at the temperature of 60 degrees. 
 
 One hundred parts of this alkali, when pure and re 
 cently cryftallifed, contain 20 of mere alkali, 16 of 
 aerial acid, and 64 of water. (Mccquer.) 
 
 Mineral alkali is found in Hungary, in marfhy 
 grounds, of an argillaceous or marly nature, either 
 mixed with water or cryfiallifed and efflcrefcing. It 
 is found alfo in Egypt at the bottom of lakes, and dried 
 up by the rummer's heat ; and alfo in the province of 
 Surhena, 28 days journey from Tripoli, where it has 
 the name of Trona ; in Syria, Perfia, as well as in the 
 Eaft-Indies, and China, where it is called kien. It fonie- 
 
 times 
 
[' "5 ] 
 
 1. It effervefces with acids, and unites with 
 them. 
 
 2. Turns the fyrup of violets to a green colour. 
 
 3. Precipitates fnblimate mercury in an orange- 
 coloured powder. 
 
 4. Unites with fat fubftances, and forms foap. 
 
 5. DifTolves the nliceous earth in the fire, and 
 makes glafs with it, &c. It diftinguifhes it- 
 felf from the fait of the pot-aihes by the fol 
 lowing properties (G). 
 
 6. It ihoots eaiily into rhomboidal cryftals ; 
 which 
 
 7. Fall to powder in the air, merely by the lofs 
 of their humidity (H). 
 
 times germinates on walls, and is called by many 
 apbronitron. In its native ftate, it is frequently mixed 
 with magnefian earth, common fait, muriatic magne- 
 fia, and marine felenite. ( Kirwan.) 
 
 (G) This mineral alkali likewife differs from the 
 vegetable, I. By its tafte, which is lefs corrofive and 
 burning. 2. By its not deliquefcing. 3. By the fmall 
 degree of heat it produces if calcined, and afterwards 
 added to water. 4. By its property of cryftallifing, by 
 evaporating the water from its folution, as i praclifed 
 with neutral falts ; whereas the vegetable alkali does 
 not cryftallife unlefs combined with a large portion of 
 aerial acid. 
 
 ( H ) This alkali being a very ufeful commodity, and 
 eflentially neceflary in a number of manufactories, 
 many ingenious procefTes have been contrived and 
 attempted to procure it at a cheap rate, by decora- 
 poiing the fea-falt ; but it is believed, that till lately 
 none of thefe new manufactures have fucceeded, ex 
 cept that of Mr Turner, mentioned by Mr Kir wan in 
 the fecond part of the Philofophical, Tranfactions for 
 
 1782. 
 
C "6 3 
 
 S. Mixed with the vitriolic acid, it makes the 
 fal mirahile Glauberi. 
 
 9. It melts more eafily, and is fitter for produ 
 cing the fal commune regeneratum, nit rum cu< 
 licum &c. Perhaps it is alfo more conveni 
 ently applied in the preparation of feveral me 
 dicines. 
 
 10. It is fomewhat volatile in the fire. 
 III. Volatile mineral alkali. 
 
 This perfectly refembles that fait which is extrac 
 ted from animals and vegetables, under the name 
 of alkali volatile or fal urinofum, and is com 
 monly conftdered as not belonging to the mine 
 ral kingdom ; but fmce it is difcovered, not only 
 in moft part of the clays, but likewife in the fub- 
 limations at Solfatara, near Naples, it cannot pof- 
 
 fibly 
 
 1/782. The procefs is faid to confift in mixing a> 
 
 quantity of litharge with half its weight of common 
 fait, which, on being triturated with water till it 
 affumes a white colour, is left to ftand fome hours ;. 
 after which, a decompofition enfues, the alkali being 
 left alone, whilft the acid unites to the metallic calx ; 
 and this laft being urged by a proper degree of fire* 
 produces a fine pigment of a greenifli yellow colour, 
 \vhofe fale pays for the moft part of the expences. 
 
 'Mr Kirwan fays, in the place already quoted, that 
 if common fait perfectly dry be projected on lead 
 heated to iacandefcence* the common fait will be de- 
 compofed, and a horn-lead formed, according to Mar- 
 graaf. He adds alfo, that according to Scheele, if a 
 iblution of common fait be digefted with litharge, the 
 common fait, will be decompofed, and a cauitic alkali 
 produced ; and finally, that Mr Scheele decompofed 
 common fait by letting its folution flowly pals thro' 
 a funnel filled with litharge. 
 
C 117 ] 
 
 fibly be quite excluded from the mineral king 
 dom ( i). 
 Its principal qualities are, 
 
 a. In the fire it rifes in forma fieca> and volati- 
 lifes in the air in form of corrofive vapours, 
 which are ofFenfive to the eyes and nofe (K). 
 
 (i) It is eafily known, by its fmell, though in a 
 mild ftate, by its volatility, and by its action on cop 
 per; the folutions of which, in the mineral acids, are 
 turned blue by an addition of this alkali. It is fre 
 quently found, though in fmall quantities, in mould, 
 marie, clay, fchiftus, and in fome mineral waters. It 
 probably derives its origin in the mineral kingdom, 
 from the putrefaction or combuftion of animal or ve 
 getable fubftances. (Kirivan.) 
 
 The fame is cauftic when uncombined with aay acid, 
 not excepting even the aerial acid. It differs from the 
 other two alkalies in many effential particulars, i* 
 By its aeriform or gafeous nature. For the volatile 
 alkali, in a ftate of purity, is nothing more than an al 
 kaline gas difFufed in water, as Dr Prieftley has de- 
 monftrated. 2. By its volatility. 3. By the nature 
 of the falts it forms with acids, which are very different 
 from thofe whofe bafes are formed either of the veget 
 able or mineral alkali. ( Monge-z.) 
 
 (K) Pure volatile alkali, in an aerial form, refem- 
 bles atmofpheric air, but is more heavy. Its fmell is 
 p;-ntetrating, and fuffocates animals. Its tafte is acrid 
 and cauftic. It quickly converts blue vegetable co 
 lours to green, and produces heat during its combi 
 nation with water. But if the wat?r be frozen, it 
 melts, producing at the fame time an extreme degree 
 of cold. It has a remarkable action on moil metals, 
 particularly copper. 
 
 This fubftance is obtained by the putrefactive fer 
 mentation from animal and fome vegetable matters. 
 
 It 
 
. It precipitates the folution of the mercurial 
 
 fublimate in a white-powder. 
 f. Italfo precipitates gold out of aqua-regia, and 
 
 detonates with it ; becaufe, 
 d. It has a re-ac~Hon in regard to the acids, tho* 
 
 not fo ftrongly as other alkalies, 
 f. It tinges the folution of copper blue, and dif* 
 
 folves this metal afreiH if a great quantity is 
 
 added (L). 
 f. It deflagrates with nitre, which proves that it 
 
 contains a phlogifton. 
 It is never found pure. 
 
 Order III. NEUTRAL SALTS. 
 
 ACIDS united to alkalies form neutral falls. Thefs 
 difTolved in water are no ways difturbed by the addi 
 tion of an alkali ; and generally, by evaporation, con 
 crete into cryftals. If, by proper tefts, they fhow 
 neither acid nor alkaline properties, they are faid to be 
 neutrals ; but imperfeO 9 when, from defect in. 
 
 quantity 
 
 It is this fait which caufes that ftrong fmell which 
 is perceived in drains and privies on a change of 
 weather. (Monger)* 
 
 Its volatility arifes from a very fublile and volatile 
 (or phlogiftic) oil, which enters as a principle into its 
 compofition. (Macquer). 
 
 (L) The folution of copper by this alkali, which is 
 of a fine blue, prefents a remarkable phenomenon. 
 For if it be kept in a well clofed phial, the colour de 
 cays, and at length difappears, giving place to tran- 
 fparency. But on opening the phial, the furface or 
 part in contact with the air becomes blue, and the 
 colour is communicated through the whole mafs. 
 This experiment may be many times repeated with 
 the fame fuccefs. 
 
-quantity or flrength of one ingredient, the peculiar 
 properties of the other more or lefs prevail. 
 
 I. Vitriolated tartar, vitriolated vegetable alkali, or 
 
 (as Morveau calls it) the vitriol of pot-ajh. 
 
 This is a perfectly neutral fait, which remits from 
 the combination of the vitriolic acid with the ve 
 getable fixed alkali. According to Bergman, it 
 feldom occurs fpontaneouily in nature, unlefs 
 where tracks of wood have been burnt down : and 
 Mr Bowles, quoted by Mr Kirwan, fays it is con 
 tained in fome earths in Spain. See CHEMJSTRY- 
 Index. 
 
 It is eafily obtained, by pouring the vitriolic acid 
 on a folution of fixed vegetable alkali till it is fa- 
 turated. Cryitals of this neutral fait are then 
 formed. This cryftallifation fucceeds better by 
 evaporation than by cooling, according to Mon~ 
 gez. 
 
 The tafte of this fait is difagreeable, though fome- 
 what refembling common fait. 
 
 II. Common nitre, (Alkali vegetalile nltratum). 
 
 This is known in commerce by the name of falt-petre^ 
 and is alfo calkd prifmatlc nitre, to diftinguifh it 
 from the cubic nitre after-mentioned. It is per 
 fect neutral fait ; refulting from the combina 
 tion of the nitrous acid with the pure vegetable 
 alkali. 
 
 According to Bergman, it is formed upon the fur- 
 face of the earth, where vegetables, efpecially 
 when mixed with animal-fubitances, putrify. 
 See CH EMI STR -/</?#, at Nitre. 
 
 III. Digeftive fait, fait of Sylvius, (Alkali vegetable 
 fal.tum). 
 
 This neutral fait is fometimes, though rarely, met 
 with on the earth, generated perhaps, as profef- 
 for Bergman bferves, by the deftruclion of ani 
 mal and vegetable fubftances. 
 
 According 
 
[ 12 ] 
 
 According to Macquer, this {alt has been very 
 wrongly called regenerated marine fait ; and the 
 epithet offe&rifuge has alfo been given to it, with 
 out any good reafon, to evince that it has fuch a 
 property. But M. d Morveau calls it muriate de 
 potaffe with great propriety. 
 
 This fait is produced by a perfect combination of the 
 vegetable alkali with marine acid. It has been 
 wrongly confounded with common fait. It is 
 found in fome bogs in Picardy, and in fome mi 
 neral waters at Normandy, according to Monet, 
 quoted by Kir wan. Mongez adds alfo the fea- 
 water, as containing this fait, and that it is ne 
 ver found in large quantities, although its com 
 ponent parts are abundantly produced by nature. 
 See CHEMISTRY-//<W, at Digejlive. 
 IV. Mild vegetable alkali, (aJkali vegetable aeratum.) 
 
 This fait was formerly confidered as a pure alkali, 
 known by the name of poiafn and fait of tartar , 
 but fince the difcovery of the aerial acid, it is ve 
 ry properly claffed among the neutral falts, and 
 ought to be called aerated potaffe. 
 
 It refults from a combination ot the vegetable alkali 
 with theaeiial acid, and is hardly ever found na 
 tive, unlefs in the neighbourhood of woods de- 
 flroyed by fire. 
 
 On being expofed on a piece of charcoal, urged by 
 the blow-pipe, it melts, and is abforbed by the 
 coal ; but, 
 
 In the metallic fpoon, it forms a glaify bead, which 
 becomes opaque when cold. 
 
 V. Vitriolated acid faturated with mineral alkali ; 
 Glauber's fait. Alkali mmerale vltriolatum. 
 
 This is a neutral fait, prepared by nature (as well ! 
 as by art), containing more or lefs of iron, or of 
 a calcareous earth ; from which arifes alfo fome 
 difference in in its effe&s when internally ufed. 
 It ftiocts cafily into prifmatical cryftals, which 
 
 become 
 
 ii 
 
C 121 ] 
 
 become larger in proportion to tlie quantity cf 
 water evaporated before the cryftallifation. 
 When laid on a piece of burning charcoal, or 
 elfe burnt with a phlogiftrn, the vitriolic acid dif- 
 covers itfelf by the imell refembling the hepar 
 fulphuris. 
 
 It is found in a diifolved ft ate in fprings and 
 wells. Some of the lakes in Siberia and At^rd- 
 can, and many fprings in other places, contain 
 this fait, according to Bergman. It is found 
 in the fea-water; a!fo in the earth, at feveral 
 parts of Dauphine in France, and in Lorraine ; 
 and fometimes it germ.inates on the furface of the 
 earth, according to Monet, quoted by Kirwan. 
 It is found, in a dry form, en walls, in iiich places 
 where aphronitrum has efHorefced through them, 
 and the vitriolic acid has happened to be pre- 
 fent ; for inilance, where marcafites are roa/led 
 in the open air. This fait is often confounded 
 with the aphronitrum or mild mineral alkali. 
 
 VI. Cubic or quadrangular nitre. Alltc.li minerals /- 
 f reft am. 
 
 This is the neutral fait which refults from the 
 combination of mineral alkali with nitrous acid. 
 It has almoit all the characters of prifmatic or 
 common nitre, from which it only differs on ac 
 count of its bafe ; and takes its denomination 
 from the figure of its cry Pails, which appear cu 
 bic. 
 
 This fait rarely occurs but where marine plants 
 putrify. According to Bowles, quoted by Kir- 
 wan, it is found native in Spain. See CHEMISTRY* 
 n74i, &c. 
 
 VII. Common fait, or fea-falt ; Alkali minerals falitum, 
 fal commune. 
 
 This fait flioots into cubical cryftals during the 
 very evaporation ; crackles in the fire, and at 
 tracts the humidity of the air. It is a perfectly 
 M neutral 
 
C i 3 
 
 Central fait, compofed of marine acid, faturated 
 with mineral alkali. It lias a faline but agree 
 able flavour. See CHEMIST&Y-//U/IX, at Sea- 
 fait. 
 
 A. Rock fait, foffile fait ; Sal montanum. Occurs 
 in the form of folid ilrata in the earth. 
 j. With fcaly and irregular particles. 
 a. Grey, and 
 
 I.. White. Thefe are the mod common, but 
 the following are fcarcer : 
 
 c. Red; 
 
 d. Blue ; and 
 
 e. Yellow, from Cracow in Poland, England, 
 Salzberg, and Tirol. 
 
 2. Cryftallized rock fait ; fal g^mma. 
 
 a. Tranfparent, from Cracow in Poland, 
 
 and from Tranfylvania. 
 JS. Sea-falt. 
 
 This is produced alfo from fea-water, or from 
 the water of fait lakes by evaporation in the fun, 
 or by boiling. 
 
 The feas contain this fait, though more or lefs 
 in different parts. In Siberia and Tartary there 
 are lakes that contain great quantities of it. 
 C. Spring fea-faU. 
 
 This is produced by boiling the water of the 
 fountains near Halle in Germany, and other 
 places. 
 
 Near the city of Lidkoping, in the province of 
 Wcftergotland, and in the province of Dal, 
 falt-fprings are found, but they contain very 
 little fait : and fuch weak water is called folsn by 
 the Swedes. 
 VIII. Borax. 
 
 This is a peculiar alkaline fait, which is fup- 
 pofed to belong to the mineral kingdom, and 
 cannot be otherwife defcribed, than that it is 
 ...... diilbluble in water, and vitrefcible ; 
 
 ...... that it is fixed in the fire ; and melts 
 
 to 
 
C 3 H 
 
 to a glafs ; which glafs is afterwards dtflbluble ia 
 water. See the detached article BORAX. 
 IX. Mild mineral alkali ; Alkali miner ale aeratum. Na 
 tron, the nitre of the ancients. 
 
 This neutral fait is a combination of the mine 
 ral alkali with the aerial acid or fixed air. It is 
 found plentifully in many places, particularly in 
 Africa and Afia, either concreted into cryila 1 - 
 lized tlrata, or fallen to a powder ; or e r ilorcfcing 
 on old brick w.ills ; or laftly, diifolved in fprings. 
 It frequently originates from decompofed com 
 mon fait. 
 
 This is an imperfeft neutral fait, and was for 
 merly confidered as a pure alkali ; but the difco- 
 very of the aerial acid has fhown the miilake. 
 
 1. It has nearly all the properties of the pure 
 mineral alkali N II. A. i. (p. 90.), but with 
 lefs energy. 
 
 2. The vegetable blue colours are turned green 
 by this fait; k efflorefces with acid;, and 
 has an urinous tafte. 
 
 3. It is foluble in twice its weight of cold wa 
 ter ; but if the water is hot, an equal weight 
 is fufticient for its folution. 
 
 4p It efflorefces when expofed to the action of 
 the atmofphere. 
 
 5. It fufes eafily on- the fire, but without being 
 decompofed. 
 
 6. Facilitates the fufion of vitrifiable earths, 
 and produces glafs more or lefs fine accprd- 
 ing to their qualities. 
 
 7. It is decompofable by lime and ponderous 
 earth, which attract the aerial acid. 
 
 8. And alfo by the mineral acids , but thefo 
 expel the aerial acid of this fait, by feizing 
 its alkaline bafis, (Monger.) 
 
 Wallerius confounds this fait with the apljroni- 
 
 trum after-mentioned, and calls it /jalinitritKt,'Vfhcn 
 
 M 2 k 
 
t 1*4 ] 
 
 Jt contains fome phlogifton. Mr Kulbel, quoted 
 by Wallerius, lliowed that it exifls in fome vege 
 table earths, and takes it to be the caufe cf their 
 fertility; but this (M. Magellan obferves) can 
 only be on account of its combination with the 
 oily parts of them, and forming a kind of foap, 
 which is mifcible with the watery juices. 
 X. Vitriolic ammoniac, (Alkali volatile vitrio'atum.) 
 
 This neutral fait was called ficret fait of Glauber, 
 and is a combination of the volatile alkali with 
 vitriolic acid. According to Bergman, it is 
 fcarcely found any where but in places where the 
 phlogifiicatcd fumes of vitriolic acid arife from 
 burning fulphur, and are abforbed in putrid places 
 by the volatile alkali. Thus at Fahlun the acid 
 vapour from the roaded minerals produces this 
 fait in the neceirary-houfes. Dr Withering, how 
 ever, obferves, that as volatile alkali may be ob 
 tained in large quantities from pit-coal, and pro 
 duced by procefles not dependent upon putrefac 
 tion, there is reafon to believe that the vitriolic 
 nmmoniac may be formed in feveral ways not no 
 ticed by the above author. 
 
 It is faid to have been found in the neighbour 
 hood of volcanoes, particularly of Mount Vefu- 
 vius, where, indeed, it might well be expecled ; 
 yet its exigence feems dubious, fmcc Mr Berg 
 man could fcarce find any trace of it among the 
 various Specimens of falts from Vefuvius which 
 he examined. The reafon (according to M. Ma 
 gellan) probably is, that the vitriolic acid difen- 
 gaged by the combuftion of fulphur is in a phlo- 
 gifticated (late ; and all its combinations in this 
 fcate are eatily decompofed by the marine acid, 
 which plentifully occurs in volcanoes. It is alfo 
 faid to 'be found in the mineral lakes of Tufcany, 
 which is much more probable, as the vitriolic acid 
 when united to water eafily parts with phlogiflon, 
 
 and 
 
[ 125 ] 
 
 and recovers its fuperiority ever other acids. It 
 is faid iikewife that this neutral fait is found on 
 the furface of the earth in the neighbourhood of 
 Turin. 
 
 1. This fait is of a friable texture, and has an 
 acrid and urinous tafte. 
 
 2. Attracts themoiihrre of the atmofphere. 
 
 3. Js very foluble in water, it requiring only 
 twice its weight of cold water, c-r an equal 
 weight of boiling water, to be cliifolved. 
 
 ^.. It becomes liquid on a moderate fire ; but if 
 urged, 
 
 5. It becomes red hot, and volatilizes. 
 
 6. The nitrous and muriatic acid decompofc 
 this fait by feizing the volatile alkali. But:. 
 
 7. Lime, ponderous earth, and pure fixed al 
 kali, fet the volatile alkali free, and combine 
 with the vitriolic acid. 
 
 8. According to Kirwan, 100 parts of this 
 fait contain about 42 of real vitriolic acid,. 
 40 of volatile alkali, and 18 cf water. 
 
 This 'vitriolic ammoniac is eafily known ; for if 
 quicklime or fixed alkali be thrown into its fo- 
 lution, the fmell of the volatile alkali is perceived ; 
 and if this folution be poured into that cf ch il'c 
 or ponderous earth by the nitrous acid, a precipi 
 tate will appear. 
 XI- Nitrous ammoniac, (Alkali volatile niiraiinn.) 
 
 This is a neutral fait, waich rcfuits from the com 
 bination of the nitrous acid with the volatile, 
 alkali. It is freomently fov.nd in the mother-li- 
 .quor of nitre. When mined wi.h a fixed alkali,, 
 the volatile betrays itfelf by its fmell. 
 
 1. It is cf a friable texture, cf a (harp bitter,, 
 nnd of a nitrous or cooling taire. 
 
 2. According to Mongez, it attracts the moif- 
 tirre of the atmosphere; but Rome de I'Ifle: 
 alitrls, that. its cryitals are net dcliqucfcent : 
 
 M 3 the. 
 
the experiment may be eafily tried, and the- 
 truth afcertained. 
 
 3. It is foluble in cold water ; but half the 
 quantity of water, if boiling, is fufficient 
 for dillblving it. 
 
 4. It liquefies on the fire, and afterwards it 
 becomes dry. 
 
 5. It detonates with a yellow flame before it 
 is red hot ; and what is peculiar to this fait, 
 it needs not, like common nitre, the contact 
 of any combuftible matter for its detenation ;. 
 from whence it appears that the volatile al 
 kali itfelf poffefTes a great ihare of phlogifton. 
 
 6. Its component parts, viz. the nitrous acid 
 and the volatile alkali, are not very intimate 
 ly united ; and of courfe, 
 
 7. It is eafily decompofed by all the fubflances 
 that have any affinity to either of them. 
 
 8. Mixed with the muriatic acid it makes- 
 aqua regia. 
 
 9. One hundred parts of this neutral fait con 
 tain 46 of nitrous acid, 40 of volatile al 
 kali, and 14 of water,, as Mr Kirwan 
 thinks. 
 
 XII. Native fa! ammoniac. The muriatic (or marine) 
 
 acid faturated with a volatile alkali. 
 This is of a yellowilli colour, and is fublimed from 
 the flaming crevices, or fire-fprings, at Solfatara> 
 near Naples* 
 
 XIII. Aerated <?>r mild volatile alkali* 
 
 This neutral fait rcTults from the combination 
 of volatile alkali united to the aerial acid. It 
 was formerly conlidcr-ed as a pure alkali : 
 But the difcovery of the aerial acid (or fix 
 ed airj has fhown it to be a true neutral fait, 
 though imperfect ; as it retains ilill all the pro 
 perties of an alkali, though in a weaker degree,, 
 on account of its combination with the aerial 
 
r "7 3 
 
 acid, which is itfelf the moft weak of all acids, 
 and of courfe other ftronger acids eafily diflodge 
 it from its bafe, and from various ammonial falts. 
 
 1. This imperfect neutral fait has an urinous 
 taile, and a particular fmell, which is very 
 penetrating, though lefs pungent, than the 
 pure volatile r.lkali ; and in the fame manner 
 it turns the blue vegetable juices green, 
 But, 
 
 2. It effervefces with other acids flronger thaa 
 the aerial one, which the pure or cauftic vo 
 latile alkali does not. 
 
 3. It fublimes very eafily with a fmall degree 
 of heat ; 
 
 4. And dilfolves in twice its weight of cold 
 water ; but in a lefler quantity, when this 
 Lift is boiling hot. 
 
 5. It acls on metallic fubdances, chiefly on cop 
 per, with which a blui colour is produced.. 
 
 According to Bcr^m m, this fait v/as found iu 
 a Well in London (Phil. Trar.f. for 1767), at; 
 Frankfort on the Main, and at LauchftadtSi 
 Meifrs. Hierue, Henkcl, and Brandt, have- 
 found alfo this fall in, the vegetable eirth, in va 
 rious kinds of argil, and in f:me flony Jubilances... 
 Mr Vozel found it aifo in fome of the incrufta- 
 tions at Gottingcn ; and Mr Maloain in fome 
 acidulous waters in France. 
 
 M. Magellan obferves, that the borax and the 
 three aerated alkalis are called imperfect ne ia\iis ; 
 whillt the other neutral falts have acqr.i--e.l- the 
 name of psrfett-, bccauie thefe lail do ivot r-xhihit :<. \j 
 of the diftingtuflimg properties of tlieir coir.j o?i j nt 
 parts. The three aer-ited alkalis have a v ry Jilt'ncl: 
 alkaline chamber, a> llioy turn blue vejctaole ju.i :es 
 green, though not of To vivid a colour as the- cauilic 
 alkali- does ; and the borax is capable oi icceivin r :il- 
 
 mofti 
 
C "8 J 
 
 moft an equal quantity of its fedative acid, without lof- 
 fmg all its alkaline properties. 
 
 In general, thofe neutral falts, confiding of fixed al 
 kalies combined with acids, are more faturated than 
 thofe compofed of volatile alkali called ammoniacal 
 falts, or thofe called aerated ; which laft are only com 
 pofed by the combination of the aerial acid, united 
 to any alkaline or earthy bafe. 
 
 The aerated alkalis are called alfo by the name of 
 mild alkalis, becaufe they poflefs no longer that fharp 
 corroding quality which they exhibit when deprived of 
 the aerial acid or fixed air ; in which cafe they are 
 termed cauftic alkalis. 
 
 Thefe aerated alkalis differ alfo from the cauftic 
 ones, not only on account of the mildnefs of their 
 tafte, from which comes their epithet of mild alkalis, 
 but alfo by their property of cryftallifmg, and by their 
 effervefcing with other acids, which expel the aerial 
 one, the weakeft of all acids we know. 
 
 Order IV. EARTHY Neutral Salts. 
 
 THE compounds of earths and acids which poflefs 
 Solubility are decompofed and precipitated by mild, 
 but not by phlogillicated alkalis. 
 I. Calcareous earth combined with vitriolic acid. 
 Vitriolated calx; Selenite ; Gypfum. See p. 72., 
 
 col. i.fttpra. 
 
 The gypfum, or plafter, is not only found dii- 
 folved in various waters, but alfo in many places 
 it forms immcnfe ftrata. It is placed by all mi- 
 neralogifts among the earths, which it greatly re- 
 fembles ; but it rather belongs to the ialine fub- 
 ftances of the neutral kind, as appears by its 
 conftituent parts. When burnt, it generates heat 
 with water, but in a lefs degree than lime does.. 
 Berg. Sciag. 59. 
 
 This fait has a particular tafte, neither bitter nor 
 aitnngent, but earthy, when applied to the 
 
 tongue ; 
 
C "9 3 
 
 tongue ; and it is owing to it that fome. waters, 
 chiefly from pumps and wells, are called hard wa 
 ters, becaufe they lie heavy on -the (lomach. 
 
 It is. unalterable whilft kept in a dry place ; but 
 on being expofed to a m >ift air, it is much alter 
 ed, and fufFers a kind of decompofition. 
 
 When expofed to fire fo as to lofe the water of 
 its cryilallifation, it aiTumes a, dead white co 
 lour ; and it is then what we call plafter of Paris ; 
 but if the fire is too flrong, it melts and vitri 
 fies, after lofing the vitriolic acid with which it is 
 faturated. See GYPSUM. 
 
 The moft famous quarries of gypfum in Europe, 
 are thofe of Montmartre, near Paris. See Jour 
 nal dc Phyfique ; 1 780, vol. xvi. p. 289 and 1782, 
 vol. xix. p. 173. 
 
 It is found alfo in the vegetable kingdpm. Mr 
 Model found that the white fpots in the root 
 of rhubarb are a fclenkical or gypfeous earth 
 (Journal ds Phyf. vol. vi. p. 14,) 
 
 What is called foffil flour (farlns foffOe in 
 French), generally found in the fiflures of rock 
 and gypfeous mountains, is very different from 
 the agaricus mineralis p. 71. col. I. and from the 
 lac lunae, p. 87. col. r.; as it is a true gypfeous 
 earth, already defcribed p. 72. col. I. which, ac 
 cording to Moagez, is of a white and fhining 
 colour, though fometimes it affiimes a reddifh or 
 bluifli colour, on account of fome martial mix 
 ture. 
 II. Nitre of lime, (Calx nitrata). 
 
 This earthy fait is fometimes found in water, 
 but very fparinly. It is faid that the chalk hills 
 in fome parts of France become fpontaneoufly 
 impregnated with nitrous acid, which may be 
 wartied out, and after a certain time they will be 
 come impregnated with it again. It is a combi 
 nation of the nitrous acid with calcareous earth. 
 (Berg. Sslagr.) 
 
 I. It 
 
C 13 1 
 
 is It Is defiquefcent ; and is foluble in twice Its 
 weight of cold water, or in an equal weight 
 of boiling vrater. 
 
 2. Irs tafte is bitter. 
 
 3. Is decompofed by fixed alkalies, which form- 
 the cubic and the prifmatic nitres. 
 
 4. But cauftic volatile alkali cannot deccm- 
 pofe it. 
 
 5. It does not deflagrate in the fire ; yet paper 
 moiftened with a faturated folution of it 
 crackles in burning. 
 
 6. In a ftrong heat it lofes its acid. 
 
 7. Its folution does not trouble that cffilverin 
 nitrous acid. 
 
 8. The vitriolic acid precipitates its bafis. 
 
 9. As does likewife the acid of fugar. 
 
 10. One hundred parts of it contain, when 
 well dried, about 33 of nitrous acid, 32 of 
 calcareous earth, and 35 of water. 
 
 It exifts in old mortar, and in the mother li 
 quor of nitre ; and alfo in the chalk rocks near 
 Roche Guyon, in France. (Kirni-an.) 
 III. Muriatic chalk, or fixed fait ammoniac. Acidum 
 fulls comtnunis terra calcareafaturaium. 
 
 This fomewhat deliquefces, or attracts the humidity 
 of the air. It is found in the fea water. 
 
 It is with great impropriety that this fait has ob 
 tained the name of ammoniac, on account only 
 of its being formed in the chemical laboratories 
 during the decompofition of the ammoniacal fait 
 with Time, in the procefs for making the cauftic 
 volatile alkali. In this cafe, the muriatic acid 
 unites to the calcareous bafis, while this la ft gives 
 its water to the volatile alkali ; \vhich, therefore, 
 comes over in a fluid cauftic ftate : but if chalk 
 is employed inftead of l-'me, the volatile alkali 
 receives the aerial acid inftead of water, and comes 
 ever in a concrete form. In n-either cafe, the new 
 
 combination^ 
 
f '3' 3 
 
 combination of calcareous earth with mnriatic 
 fait has any volatile alkali to deferve the name of 
 ammoniac al fait. ( Macquer.) 
 
 1. This earthy fait has a faline and very difa- 
 greeable letter talte. It is fuppofed to be 
 the caufe of that bitternefs and naufeous tafte 
 of fea- water, 
 
 2. It fufes in the fire, and becomes phofphoref- 
 cent, after undergoing a ftrong heat. 
 
 3. It becomes hard, fo as to (Inkx- fire with fteeL 
 
 4. It is then the ph^fphorus of Homberg. 
 
 5. It is decompofabie by ponderous earth and 
 fixed alkalis, 
 
 6. And alio by the vitriolic or nitrous acid ; 
 which expel the muriatic acid, to unite with 
 the calcareous bafis. (Mongez.) 
 
 7. Its folution renders that of iilv.r in the ni 
 trous acid turbid, at the fame time that 
 
 8. It makes no change in that of nitrous felenite. 
 
 9. It obftinately retains its acid in a red heat. 
 
 10. One hundred parts of this earthy fait con 
 tain, when well dried, about 42 of marine 
 acid, 38 of calcareous earth, and 20 of water. 
 
 11. It is found in mineral waters, and in the 
 fait works at Saltzburg. (Kirwan.) 
 
 IV. Aerated chalk, (Calx aerata.} 
 
 Whenever calcareous earth is overfaturated with 
 the aerial acid, it becomes a true earthy neutral 
 fait ; becomes foluble in water, and has a flight 
 pungent bitter tafte. It is commonly found dif- 
 folved in waters, in confequence of an excefs of 
 the aerial acid. When this greatly abounds, the 
 water is faid to be hard (cruda). By boiling or 
 by evaporation, it depofits ftreaks or crults of cal 
 careous matter. 
 
 But when the calcareous tarth is only faturated with 
 the aerial acid without excefs, it is not eafily fo 
 luble j it is then the calcareous fpar, p. 7-1. co/. 2. 
 
 and 
 
[ 13* ] 
 
 and is properly referred to the clafs of earths, 
 p. 71. col. i. 
 
 V. Vitriolated ponderous earth. Terra pondercfa vi~ 
 
 triolata ; barytes vitriol at a, 
 
 This earthy fait, known by the name of ponderous 
 fpar, is a combination of the ponderous earth def- 
 cribed in p. 75. col. i. with the vitriolic acid ; and 
 has been already treated of. 
 
 The nitrous ponderous earth, according to Berg 
 man, has not yet been found, although it may 
 perhaps exift fomewhere, and of courfe be difco- 
 vered in nature. 
 
 VI. Muriatic barytes, marine baro-felenite. Barytes 
 Jalita* 
 
 This earthy fait confifts of marine acid united to the 
 ponderous earth. It is faid to have been found 
 in feme mineral waters in Sweden ; and may be 
 known by its eafy precipitability with vitriolic 
 acid, and by the great insolubility and weight of 
 this refulting compound, which is the true pon 
 derous fpar of the preceding fection. 
 
 VII. Aerated ponderous earth. Barytes aerata. 
 This earthy neutral fait vas found by Dr Wither 
 ing in a mine at Alfton-moor in the county of 
 Cumberland in England. He fays that it is ve 
 ry pure, and in a large mafs. This fubftance is 
 anew acquifition to mineralogy, and may be turn 
 ed to ufeful purpofes in chemilhy. 
 
 1. It efFervefces with acids, and melts with the 
 blow-pipe, though not very readily. 
 
 2. In a melting furnace, it gave force figns of fu- 
 fion ; but did not feel cauftic when applied to 
 the tongue, nor had it loll its property of effer- 
 vefcing with acids. 
 
 3. But the precipitated earth from a faturated 
 foluticn of it in the marine acid, by the mild 
 vegetable or mineral alkali being burned, and 
 thrown into water, gave it the properties of 
 
 i lime- 
 
[ '33 J 
 
 lime-water, having an acrid tafte in a high- 
 degree : and a Tingle drop of it added to the fo- 
 lutions of vitriolated falts, as the Glauber's fait, 
 vitriolated tartar, vitriolic ammoniac, alum, 
 Epfom fait, felenite, occafioned immediately a 
 precipitation ; from whence it appears to be the 
 niceft teft to difcover the vitriolic acid. By if 
 the marine acid may alfo be eafily freed from 
 any mixture of vitriolic acid, by means of this 
 calx of ponderous earth. See CHEMISTRY n 6 
 1049. et.Jeq. 
 VIII. Vitriolated magnefia. 
 
 This earthy neutral fait is called by the Englifhxs^- 
 fomfalt ; Sel d* Angleterre by the French, and allb 
 Jel de SedlitZ) de Seydfchutz, fel amsr, fel cathartiqnc 
 amer, &c. Thefe various names are given to it, 
 either on account of its properties, it being a ve 
 ry mild purgative ; or from the places where it is 
 found, befides many others* as in the waters of 
 Egra, of Creutzbourg, Ohernental, Umea, &e. 
 It has alfo been round native, mixed with com 
 mon fait and coaly matter, germinating on fbme 
 free ilones in coal mines. See Kirivan's Minera 
 logy, p. 183. 
 
 1. It has a very bitter taftc. 
 
 2. It is foiuble in one part and a half of its weight 
 of cold water : but in hot water, a given wen-he 
 of it difTolves the double of this fait. 
 
 3. It cfHorefces when expofed to a dry atmofphere, 
 and is reduced to a white powder. 
 
 4. Expofed to the fire, it lofes the u ater of its cry- 
 ftallifation, and is reduced into a friable mais. 
 
 5. This eaithy fait is decompofed by fixed and vo-> 
 latile alkalies. 
 
 6. Lime-water precipitates the magnefia from its 
 folution, the calcareous earth of lime-water 
 combining itfelf with the vitriolic actd, and for 
 ming a felenite. A r . . By this teit the vilri- 
 
 N elated 
 
c 134 : 
 
 elated magnefia is eafily diftinguifhcd from the 
 vitriolated mineral alkali or Glauber's fait, 
 which it refembles. 
 
 7. Bat crude chalk, or aerated calcareous e~rth, 
 has not fuch an effect in the fame cafe ; which 
 fhows ho\v much the efficacy of this fubftance, 
 viz. the calcareous earth, is diminifhed merely 
 by its union with the aerijl acid. 
 
 8. When urged by the flame with the blow-pipe, 
 it froths ; and may be melted by being repeat 
 edly urged with that inftrument. 
 
 9. With bcrax it eflfervefces, and alfo when burn 
 ed with the micrccofmic fait. 
 
 10 According to Bergman, 100 weight of this 
 fait contains only 19 parts of pure ma^nefia, 
 33 of vitriolic acid : and 48 of water. But 
 
 ii. According to Kin-van, 100 parts of it contain 
 about 24 of real vitriolic acid, 19 of magnefi- 
 an earth, and 57 of water. 
 IX. Nitrated magr.efia ; nitrous Enfom fcilr. 
 
 This earthy fait is ufually found together with nitre. 
 
 It is a combination of the nitrous acid with the 
 
 niagnefian earth. 
 
 1. It has an acrid tafle, very bitter. 
 
 2. Attracts the motiuire from the atmofphere, 
 and deliquefces. 
 
 3. Is very foluble in water. 
 
 4. Is eafily decompo&ble by fire. 
 
 5. The ponderous and calcareous earths deccm- 
 pole it, and alfo the alkalies. 
 
 6. On being urged by the blow-pipe, it fwells up 
 with fome noife, but does not detonate. 
 
 7. If faturated folutions of nitrous felenite and 
 of this fak be mixed, a precipitate will appear ; 
 but, 
 
 8. Neither vitriolic acid, ncr mild magnefia, will 
 ^ccaflon any turlidnefs in its folution. 
 
 c. One 
 
[ * 35 ] 
 
 9. One hundred parts of this fait contain about. 
 
 36 of real nitrous acid, 27 of magnefian earth, 
 
 ar.d 37 of water. 
 
 It exifts in old mortar, and is found alfo in the 
 mother liquor of nitre. As lime-water decorn- 
 pofes it, M. da Morveau has indicated the ufe ci" 
 this procefs, not only to complete its analyils ; 
 bat alfo to feparate, in large quantities, and at 
 a very cheap rate, the magnefian from the calc > 
 reous earth, as M. Mongez relates upon this fub- 
 jed. 
 'X. Muriatic magnefia. Magne/iafallta. 
 
 This earthy fait is a combination of magnefian earth 
 with the muriatic acid. According to Bergman, 
 itU found in the fea in greater plenty than any o- 
 ther fait except the fea-falt. 
 
 1. It has a very bitter tafte : and being always 
 mixed in the fea-water, it is the principal caufe 
 o its bitternefs. 
 
 2. It is very delifquefcent, and Tollable in a fmall 
 quantity of water. 
 
 3. All the alkalies, even the cauftic volatile al 
 kali and lime, decompofe it by precipitating its 
 bafis. 
 
 4. The vitriolic, nitrous, and boracic acids expel 
 the muriatic acid from the bafe of this neutral 
 fait. 
 
 5. Its folution does not trouble that of nitrous or 
 marine felenite ; but, 
 
 6. It caufes a cloud in the nitrous folution of ul- 
 ver. 
 
 7. The vitriolic acid throws down no vifible pre 
 cipitate from the folution of this neutral fait. 
 
 8. Itlofes its acid in a red heat. 
 XI. Aerated magnefia. 
 
 Common magnefia, with an excefs of aerial acid is 
 
 a true neutral fair, like the aerated felenite of 
 
 p. 96, col. i. and becomes foluble in cold water. 
 
 N 2 Othetwife 
 
C 136 ] 
 
 Otberwife it is fcarce foluble at all ; and is then 
 cl ailed among the earths. 
 
 This neutral fait is decompofable by fire, by which 
 its water and its acid are expelled j and it may be 
 come phofphoric. 
 
 When urged by fire, it agglutinates a little : and fome 
 pretended that it melts. But it mud be in an im 
 pure ftate to vitrify at all. 
 
 The three mineral acids, and the alkalies, dliTolve 
 this fait with efFervefcence, by expelling the ae 
 rial acid, 
 
 XII, Argillaceous earth combined with vitriolic acid. 
 The alum kind. See ALUM, and CHEMISTRY- 
 ffte/fx t 
 
 . With a ftnall quantity of clay j native or plumofe 
 alum, 
 
 It is found en decayed alum ores in very ftr.aH 
 quantities ; and therefore, through ignorance, 
 the alabaftrkes and felenites, both of which are 
 found among mod of the alum flates, are often 
 rubilrtuted in its Mead, as is alib fometimes the 
 afbeftus, not with (binding the great difference 
 there is between the alum and thefe both in rur 
 gard to their ufes and effects. 
 
 I. With a greater quantity of pure clay ; white alum 
 ore. 
 
 i. Indurated pale-red alum ore, (fcltjius alumtn'u 
 Romanus.) It is employed at Lumini, not far 
 i^om Civita Vecchia in Italy, to make the pale- 
 red allum called rocb allum. This is, of ail 
 alum ores, the moft free from iron ; and the 
 reddifn earth which can be precipitated from 
 it, does not fnow the leaft marks of any metal 
 lic fubflance. 
 
 r, With a very large quantity of martial clay, which 
 likewife contains an inflammable fubflance ; 
 Common alum- ore. This is commonly in 
 durated 
 
C 13? ] 
 
 durated and ilaty, and is therefore general 
 ly called alumjlate. 
 It is found, 
 
 i . With parallel plates, having a dull furface ; 
 from Andrarum in the province of Skone, 
 Hunneberg and Biilmgen in the province of 
 Weft erg Gitl and, Rodoen in the province cf 
 Jemtland, and the ifland of Oeland, &c. In 
 England, the great alum works at Whitby in 
 Yorkshire are of this kind. 
 
 2. Undulated and wedge-like, with a Chining 
 furiace. This at the firft fight refembles pit- 
 coal ; it is found in great abundance in the pa- 
 rilh of Nas in Jemtland. 
 
 XIII. Argillaceous earth faturated with muriatic acid. 
 Argilia falita. 
 
 ProfelTor Bergman fays, that the combinations 
 of the argillaceous earth with the nitrous, muria 
 tic, and aerial acids, had not yet been found na 
 turally formed as far as he knew. But Dr "Wi 
 thering affirms, that he found the muriatic argil 
 to exilt in a considerable: quantity, in the Nevil 
 Holt water, when he analyfed that mineral water 
 about the year 1777: and he adds, that it is pro 
 bably contained alfo in the Bally caftle water i-ii 
 Ireland. 
 
 XIV. Argillaceous earth mixed with volatile alkali. 
 [Although this mixture is by no means a neutral 
 
 fait, this feems to be the place to treat of it ac 
 cording to the order of faline fubftances adopted 
 in this article. 1 
 
 The greateil part of the clays contain a volatile al 
 kali, which difcovers itfelf in the diftillation of the 
 fpirit of foa-falt, &c. 
 
 3 N Or.isr 
 
C 138 
 
 -)rdkr V. METALLIC SALTS. 
 
 THE native falts belonging to this divifion may be 
 djilinguiilied by the pblogillicated alkali, which preci 
 pitates them ail. The few which have faiine proper 
 ties, according to the definition of falts formerly gi 
 ven, fhall be mentioned here ; referring the reft to the 
 minei allied metals ; as the luna eornea y the faiine quick- 
 Silver or murutic mercury, &c. 
 
 I. Vitriol of copper ; blue vitriol. Fitrioluw veneris, 
 
 f?u cyprium. 
 
 This neutral metallic fait is a combination of 
 the vitriolic acid with copper, and is found in all 
 ximent waters, as they are called. Its colour is a 
 deep blue ; and being long expofed to the air, it 
 degenerates into a nifty yellow blue. Urged by 
 the flame of the blow-pipe on a piece of charcoal, 
 it froths at firft with noife, giving a green flame, 
 and the metallic particles are often reduced to a 
 finning globule of copper, leaving an irregularly 
 figured icoria. But with borax the fcoria is 
 diifolved, and forms a green glafs. 
 
 This fait rarely occurs cryftallifed : but is often 
 found naturally diilblved in water in Hungary, 
 Sweden, and Ireland : from this water a blue vi 
 triol is generally prepared, Thefe natural wa 
 ters are called cemen:atory or cementing ones. Ac 
 cording to Monet, this concrete fait, when found 
 naturally formed, only proceeds from the evapo 
 ration of fitch waters. It is alfo occafionaliy ex 
 tracted from fulphurated copper ores after torre- 
 faction. See CHEMISTRY-/^/*?.*, at vitriol. 
 
 II. Muriatic copper, or marine fait of copper. Cuprum 
 fallium. 
 
 This fait has been found in Saxony, in the mine 
 
 of Johngeorgenftadt. I. It is of a greenifh 
 colour, and foliated te 
 
 xture. 2. It is moderate- 
 
[ 139 1 
 
 ly hard. 3. Sometimes it is transparent and cry- 
 ftallifed. 
 
 It has been taken for a kind of mica : but Pro- 
 feiibr Bergman found it to confift of copper 
 and marine acid, with a little argillaceous earth. 
 
 Another fpecimen of a purer fort was depofited 
 in the mufeum of Upfal. This is of a bluifh 
 green colour, and friable. It effervefced with ni 
 trous acid, to which it gave a green colour : and 
 by adding a proper folution of filver, a luna cor 
 nea was formed, by which the prefence of the 
 muriatic acid was afcertained. ( Kirivan and Berg 
 man. ) 
 
 III. Martial vitriol ; vitriol of iron. Common green 
 vitriol or copperas. 
 
 This is the common green vitriol, which is na 
 turally found diifolved in water, and is produced 
 in abundance by decayed or calcined marcaiites. 
 
 This metallic neutral fait refults from the com 
 bination of the vitriolic acid with iron. 
 
 1. It is of a greenifh colour when perfectly and 
 recently cryftallifed ; but, 
 
 2. Efflorcfces by being expofed to the air, be 
 comes yellowifh, and is covered with a kind of 
 ruft. Sometimes it becomes white by long 
 {landing. 
 
 3. It requires fix times its weight of water, in 
 the temperature of 60 degrees, to be diilblved. 
 
 4. It has an aftringent, harfh, and acidulous tafte. 
 
 5. Expofed to a moderate heat, even to that cf 
 the funiuine, it falls into a yellowiih powder : 
 but, 
 
 6. On being expofed to a fudden heat, it melts ; 
 and on cooling, aflumes a whitiih brown colour. 
 
 7. When ftrongly urged by fire, it lofes its acid, 
 becomes of a dark red colour, and is then call 
 ed colcothar ; a powder which is employed in 
 polutung metals, and to which the artifts have 
 
 applied 
 
C HO 3 
 
 applied the improper name of crocus martis, 
 though this name only belongs to the yellow 
 preparations of the iron-calces, ufed in phar 
 macy and in enamelling, &c. 
 
 8. Pure fixed alkali precipitates the iron from its 
 folution in deep green flakes ; the mild alkali, 
 in a greenifh white colour ; pure volatile alka 
 li, in fo deep a green, that it appears black ; 
 but the mild volatile alkali precipitates it in a 
 greyifh-green colour. 
 
 9. All vegetable aftringents, as the tindure of tea, 
 quinquina, gales, &c. precipitate the iron in a 
 black colour: hence they are ufed as teds 
 to difcover its pretence in chemical analyfes ; 
 and it is from this black precipitate that the 
 common writing ink is made, being diluted 
 in water, and there fufpended by the Arabic or 
 Senegal gums. 
 
 10. One hundred parts of this fait, recently cry- 
 ftallifed, contain 20 of real vitriolic acid, 25 of 
 iron, and 55 of water. 
 
 11. Its acid is known by this, that its folu 
 tion mixes without turbidity with the folutions 
 of other falts that contain vitriolic acid ; ;:s 
 Epfom, felenite, vitriolated tartar, &c. 
 
 12. And the bafis of this metallic fait is known 
 by the black colour produced by the folution 
 of vegetable aftringents. 
 
 13. On being urged by the fiame thrown by the 
 blow-pipe, it offers the fame phenomena as the 
 vitriol of copper, except that it does not colour 
 the flame. 
 
 Green vitriol is frequently found native, ei 
 ther in coal mines or in the cavities of pyriui- 
 ceous mines, or adhering to their fcaffolds in a 
 ftalaclitical form. It is found alfo in fmall 
 round ftones, called ink-Jlonef, of a white, red, 
 grey, yellow, or black colour, which ar,e almoft 
 
 iblubie 
 
foluble in water, and contain a portion of copper 
 and zinc. Alfo fometimes in form of fchiftus 
 or flaty pyritaceous ftones. But the greateft 
 part of that in ufe is prepared by art, from the 
 martial pyrites or mundic. See CHEMISTRY, 
 n 619. 
 IV. Aerated iron. Ferrum aeratum. 
 
 This metallic fait is a combination of the ae 
 rial acid with iron ; and is found in the light 
 chalybeate waters, where it is diffolved by an ex- 
 cefs of this acid. 
 
 Mr Lane was the firft who discovered in Eng 
 land the aclion of the aerial acid on iron, when, 
 the water is impregnated with that menftruum. 
 The late R. Rouelle demonftrated the fame 
 phenomenon in France upon this and other me 
 tals. But ProferTor Bergman Teems to have pre 
 ceded them both nearly about the fame time, 
 though neither had any knowledge of each other's 
 difcoveries. 
 
 The great volatility of this acid i-s the caufe why 
 this neutral fait is not often found. For the 
 mere evaporation of the ferruginous mineral wa 
 ters, in order to analyfe them, is fufficient to let 
 loofe the aerial acid ; To that the iron which was 
 there diffolved by its power falls down to the 
 bottom in the from of a light ore, which amounts 
 to nearly TT * TT of the weight of the water ; and 
 when frefh retains fo much phlogifton as to obey 
 the magnet, as Bergman Says. 
 V. Vitriol of cobalt, or vitriolated cobalt. 
 
 This metallic fait refults from the combination of 
 the vitriolic acid with cobalt. 
 i. When found native, it is always in an efHo- 
 refcent ftate ; whence it arifes that, in this 
 cafe, 
 
 ?. Its colour is greenifh, mixed with a grey tint : 
 but, 
 
C >4* 1 
 
 3. It is of a rofy colour when artificially made ; 
 
 4. Efflorefces when expofed to the action of the 
 atmofphere ; and, 
 
 5. Takes then a greenifh colour mixed with a 
 pale purple, or a LiTias colour, as the French 
 call it. 
 
 6. It is difficultly foluble in water ; and, 
 
 7. Its folution is of a red colour. 
 
 8. The phlogifticated alkali precipitates the co 
 balt from the folution of this fait, which with 
 borax gives an azure glafs. 
 
 By the above qualities, chiefly the rofy co 
 lour of the folution of this neutral fait, its ba- 
 fis is fufficiently diftinguifhed. As to its acid, 
 it is eafily known by the fame tefts as thofe of 
 the preceding vitriols. 
 
 It is laid to be found native in fmall pieces, 
 mixed with a greenifh efflorefcence in cobalt 
 mines. (Kirwan and Mongez.) 
 VI. Vitriol of zinc, vkriolated zinc, or white vitriol. 
 This neutral metallic fait refuks from the combina 
 tion of vitriolic acid with zinc. 
 j. Its colour is white. It, 
 
 2. Requires little more than twice its weight cf 
 water to dilTolve it in the temperature of 60 
 degrees of Fahrenheit's thermometer^ and de- 
 pofits a greyiih yellow powder. 
 
 3. Its fpecific gravity is 2000. 
 
 4. Its tafte is very ftyptic. 
 
 5. It mixes uniformly with vitriolic neutral falts. 
 j6. Precipitates nitrous or marine felenites from 
 
 their folutions, by which its acid is afcer- 
 tained. 
 
 7. It is precipitable in a whitifh powder by al 
 kalies and earths ; but, 
 
 8. Neither ii en, copper, nor zinc, precipitate it : 
 by which circumftance its bafis is fufficiently 
 indicated. 
 
 9 . if 
 
[ 143 ] 
 
 9. If it contains any other metallic principle, 
 this may be precipitated by adding more zinc 
 to the folution ; excepting iron, which will 
 of itfelf precipitate by expofure to the air or 
 boiling in an open velTel. 
 
 10. One hundred parts of this metallic fait con 
 tain 22 of vitriolic acid, 20 of zinc, and 58 
 of water. 
 
 1 1 . Urged by fire, it lofes a good part of its acid. 
 
 12. Treated with the blow-pipe it exhibits nearly 
 the fame phenomena as other metallic vitri 
 ols ; except only that the flame is brilliant 
 
 . when the zinc is reduced, and gives out white 
 floes called Jlowers of zinc. 
 
 This neutral metallic fait is fometimes found 
 v native, mixed with vitriol of iron, and in the 
 form of white hairy cryftals ; or in a ilalac- 
 titical form in the mines of Hungary, . cr 
 as an efflorefcence on ores of zinc. It is alfo 
 found difiblved in mineral waters, and gene 
 rally with feme proportion of vitriols of iron 
 and copper. Bergman fays it is fometimes 
 produced by the decompofition of pfeudoga- 
 Issna, or black-jack ; but this rarely happens, 
 becaufe this iubftance does not readily decom- 
 pofe fpontaneoufly. 
 
 But that in common life is moftly prepared 
 at Gofiaar, from an ore "which contains zinc, 
 copper, and lead, mineralifed by fulphur and 
 a little iron. The copper is firft feparated as 
 much as poffible : the remainder after torre- 
 faction and diftillation is thrown red-hot into 
 water and lixiviated. It is never free from 
 iron. ( Kirwan, Mongez. ) 
 VII. Variolated nickel, or vitriol of nickel. 
 
 This neutral metallic fait refults from the com 
 bination of the vitriolic acid with nickel. It ex- 
 ills fometimes in confequence of the decornpofi- 
 
 tion 
 
C 144 3 
 
 tion of the fulphureous ores of this femimetal. 
 It is found native, effiorefcing on Kupfer-nickel ; 
 and generally mixed with vitriol of iron. It is 
 of a green Colour, as well as its foliation. It is 
 precipitated by zinc ; but when joined with iron, 
 this laft is not precipitated by the fame. 
 
 Its origin is perhaps owi::g to the decompofition 
 of the pyritaceous and fulphureous ore of Kupfer- 
 nickel, mentioned by Waller ins. This ore con 
 tains a great quantity of arfenic and fulphur, as 
 well as cobalt, nickel, and iron. And if it comes 
 to be decompofed in the b .wcls of the earth, it 
 is natural to expect that 'he vitriolic acid of the 
 fulphur will atu ckel and the iron, with 
 
 which it will form neutral metallic falts (Mongez, 
 Kir wan. ) 
 VIII. Muriatic mangane. Manganejitim falitnm. 
 
 M. Hielm is the only perfon who has as yet 
 found this middle fait in fome mineral waters of 
 Sweden. It is ccmpofed by the combination of 
 the regulus of Mauganefe with muriatic acid. 
 
 i. It is precipitated of a whitlih yellow colour, 
 by the Pruffian (phlogiflicated) alkali; and of a 
 brownifh yellow, by the mineral alkali. 2. It 
 does not cryftallife in any diftinct form. 3. It 
 abftracls the moifture of the air. 4. To obtain 
 its bafis free from iron, it muft be precipitated 
 by the mineral alkali ; rediilblved in nitrous acid ; 
 then calcined until this acid is expelled ; and the 
 refiduum is to be treated with difliiled vinegar, 
 which will then take up only the manganefe. 
 ( Ktriuan. ) 
 
 Order. VI. TRIPLE SALTS. 
 
 THE neutral falts hitherto enumerated are fitch as 
 
 arc compofed of two ingredients only ; but fometimes 
 
 three or more are fo united as not to be feparated by 
 
 i cryftalli- 
 
[ '45 3 
 
 cryftallization. The vitriols that we are acquainted 
 with are hardly ever pure ; and two or three of them 
 fometimes are joined together. 
 
 Sometimes likewife it happens that neutral falts join 
 earthy falts, and earthy falts metallic ones, Bergman 
 generally diftinguiihes compound falts according to 
 the number of their principles, whether the fame acid 
 be joined to feveral bafes, or the fame bafe to diffe 
 rent acids ; or, laftly, whether feveral menftrua and 
 feveral bafes are joined together. Hence arife falts 
 triple, quadruple, &c. which the diligence of after- 
 times muft illuftrate. The mod remarkable examples 
 of triple and quadruple native falts which have yet 
 occurred are, 
 I. Mineral alkali, with a fmall quantity of calcareous 
 
 earth. Alkali falls communis. Aphronitrum. 
 This is fo ftrongly united with the calcareous 
 earth, that the latter enters with it into the very 
 cryftals of the fait : though by repeated folutions 
 the earth is by degrees feparated from it, and 
 falls to the bottom after every folution. 
 It grows in form of white froft on walls, and 
 under vaults ; and in places where it cannot be 
 wafhed away by the rain. 
 
 Hence it would appear, that this is not only a 
 triple, but a multiple fait ; as thefe pieces of old 
 mortar covered with this white froft, on ancient 
 walls, are the very fame from which the faltpetre 
 makers extract the mother- water of nitre, after 
 mixing therewith the vegetable afhes, to furnifli 
 the alkaline bafe to it. M. Fourcroy fays in his 
 feventeenth Lefture, that this mother-water con 
 tains not only nitre, but five other kinds of fait, 
 viz. the marine fait, nitrous magne/ia, calcareous 
 nitre, magnsfta nitrata, and calx Jalita ; to which 
 the chemifts of Dijon add the digeft'mt fait of Syl 
 vius, and in fome cafes various vitriols with alka 
 line or earthy bafes. 
 
 O When 
 
C" 
 
 s When it contains any confidera'ble quantity of 
 
 . the calcareous earth, its chryftals become rhom- 
 
 boidal, a figure which the calcareous earth often 
 
 affumes in inooting into chryftals : but when it is 
 
 purer, the cryftals Ihoot into a prifmatic figure. 
 
 , This is a circumftance which neceiFarily muft con- 
 
 jfufe thofe who know the falts only by their 
 
 figure, ; and ihows, at the fame time, how little 
 
 certainty fuch external marks afford in a true 
 
 diftincHon of things. 
 
 This fait is very often confounded with the 
 fal mirabile Glauber i. 
 
 II. Common fait with magnefia ; or muriatic mineral 
 
 alkali contaminated by muriatic magnefia. 
 ; This is a compound of the common fait with 
 muriatic magnefia : and by the expreilion conta 
 minated (inqulnatum) of profelfor Bergman', we 
 may fuppofe that the magnefian fait is not inti 
 mately united to the alkaline b^rfe. 
 Tliis triple fait is very deliquefcent ; a quality 
 it owes to its integrant part, the muriatic magne- 
 ila, (p. 79. co.l. i.) For the pure muriatic alkali 
 does not deliquefce : but this degree of purity is 
 feldom found, even in the native foffil offal gem, 
 (p. 93. col. 2.) In general all the earthy marine 
 falts are very deliquefcent-, as the muriatic chalk, 
 the muriatic barytes, and the muriatic magnefia. 
 Bergman, Macquer^ and Jhlongez. 
 
 III. Mineral alkali with fuccinous acid and phlogifton. 
 This fub (lance will be afterwards mentioned among 
 
 the inflammables. 
 
 IV. Vitriolated magnefia with vitriol of iron. Epfom 
 fait contaminated with copperas. 
 
 . Found in fome mineral waters, according to Mr Mo 
 net, (Treattfe on Mineral Waters.) 
 
 V. Native-alum contaminated by copperas. Vitriola 
 
 ted argil with vitriol of iron. 
 
 Found 
 
C H7 1 
 
 Found in the aluminous fchiPcus. It fometimes 
 effiorefces in a feathery form. Perhaps this is 
 the plumofs alum of the ancients. 
 VI'. Native alum, contaminated by fulphur. 
 
 At the places about Wednefbury and Bilflon, in 
 Staffordshire, where the coal-pits are on firej 
 this fubftance fublimes to the furface ; and may 
 be collected, in confiderable quantity, during dry 
 or frofty weatlier. 
 
 A fmiilar compound fubftance fublimss at the 
 Solfaterra near Naples. 
 
 VII. Native alum contaminated by vitriolated cobalt. 
 In the mines of Herregrund and Idria this fait 
 
 may be feen (hooting out into long {lender fi> 
 laments. Perhaps this is the tnchi'es of the 
 Greeks. 
 
 1. DiiTolved in water, it immediately betrays 
 the prefence of vitriolic acid upon the ad 
 dition of terra ponderofa falita (muriatic" acid 
 faturated with heavy earth). 
 
 2. By the addition of phlogiflicated alkali, a 
 precipitate of cobalt is thrown down, which 
 makes blue glafs with borax or microcofmic 
 ialt. (B:rg. Sci^.} 
 
 VIII. Vitriol of copper with iron. 
 
 This fait is of a bluifh-green colour. It is the 
 wirio/urn ferreo-ctipreum cyamum of LinnGeus. Its 
 colour varies, being fometimes more orlefs greeny* 
 and fometimes more or lefs blue. It is found at 
 Saluberg and at Falhun. This vitriol is called 
 vit/iol of Hungary becaufe it is found ia the 
 Hungarian mines of this kind. (Monger.) 
 
 IX. Vitriol of copper, iron, and zinc. 
 
 This is the oittiolum ferreo zincs?) cupreu-r. cyin?i'.~T. 
 of Linnxus. Its colour is of a blue incliiv- 
 ing to green. If rubbed on a polifhed furface of 
 iron, the copper is not precipitated thereby, as 
 it happens to the blue vitriol;, which (hows th?.- 
 O 2 thi 
 
the vitriolic acid is perfeclly faturated in this fait 
 by the three metallic bafes. 
 
 X. Vitriol of copper and zinc. 
 
 This is the blue vitriol from Collar, According 
 to Mongez it is the vitrwlum mnceo-cufreuin cacru* 
 kum of Linnaeus. 
 
 XI. Vitriol of iron and zinc. 
 
 This is the green vitriol from Collar in the 
 Hartz. According to Monger, this in the vitri- 
 v/um %incQ-firreum i)ir'ide of Linnaeus, 105* 6. Its 
 colour is a pale-green caft. 
 XI L Vitriol of iron and nickel. 
 
 This fait is of a deep-green colour, and is con 
 tained in the ochre, or decayed parts of the nic 
 kel, at the cobalt-mines of Los, in the province 
 of Helfmgland. 
 
 CLASS III. MINERAL INFLAMMABLE SUB- 
 
 STANCES. 
 
 To this clafs belong all thofe fubterraneous bodies 
 that are diffoluble in oils, but not in water, which they 
 repel ; that catch flame in the fire ; and that are elec 
 trical. 
 
 It is difficult to determine what conftitutes the dif 
 ference between the purer forts of this clafs, fince they 
 all muft be tried by fire, in which they all yield the 
 fame product ; but thofe which in the fire (how their 
 differences by containing different fubftances, are here 
 <:onfidered as being mixed with heterogeneous bodies : 
 that fmall quantity of earthy fubftance, -which allphlo- 
 gifta leave behind in the fire, is, however, not attend 
 ed to. 
 I. Inflammable air ; fire damp. 
 
 This aeriform fubftance is eafily known by its 
 property of inflaming when mixed with twice or 
 thrice its bulk of common atmofpheric air; and 
 
 it 
 
L 149 J 
 
 il is afierted to be the real phlogiftonalmoft pure, 
 See AEROLOGY-//?^/?.* and INFLAMMABLE Air. 
 
 It admits coniiderable varieties, according to the 
 nature cf the fubitances from which it is pro- 
 oinced, and often gives different refiduums upon 
 combuftion, fome of which are of the acid kind. 
 If it is produced from charcoal, it yields aerial 
 acid or fixed air : from folutions of metallic fub- 
 ftances in the vitriolic, nitrous, or marine acids, 
 it yields thefe refpeclive acids, as M. Lavoifrer 
 admits. 
 
 ./Edier, converted into vapour in a vacuum, gives 
 a permanent elaflic vapour, which is inflam 
 mable. The atrnofphere, which floats round the 
 fraxinella, is inflammable from the admixture, 
 of its vapours, which feem to be of the nature of 
 an effential oil : fo that on approaching the flame 
 of a candle under this plant, in hot weather, it 
 takes fire in an inftant; although the effential oil, 
 extracted from this plant by diftillation, is not in 
 flammable on account of the watery particles 
 mixed with it, as M. Bomare aiferts. 
 
 Mr Scheele is of opinion, that every inflamma 
 ble air is ccmpofed of a very fubtile oil. This 
 coincides with the idea entertained by chemiftsoF 
 their phlogiiion; and is confirmed by the facly 
 cf its being naturally foufitl in thofefprings from 
 whence iifues petrol, whole exhalations are very 
 inflammable. 
 
 The refiduum, which remains in the atmofphers 
 after the combuilion of inflammable air, is ex-, 
 trcmely noxious to animals. Doftor Prieftley 
 takes it to be a combination of phlogifton v ith 
 fiure air, and on this account calls it phlo^tfti- 
 caled air. But M. Lavoifier, on the contrary, 
 eonfiders it to be a primitive fubfta.'ics of an un- 
 changeable nature, and give:- it ,the finguhur n.'.mc 
 f atmvf&heric mephil'.s. 
 
 O 3 IL. He- 
 
C '5 ] 
 
 II. Hepatic air. 
 
 This air feems to confift of fulphur, held in fo- 
 lulion in vitriolic or marine air. It is inflam 
 mable when mixed with three quarters of its 
 bulk of common air. Nitre will take up about 
 half the bulk of this air ; and when faturated 
 with it, will turn filver black : but if ftrong de- 
 phlogifticated nitrous acid be dropped into this 
 water, the fulphur will be precipitated. 
 
 One hundred cubic inches of this air may hold 
 eight grains of fulphur in folution in the tempe 
 rature of 60; and more if hotter. 
 
 Atmofpheric air alfo decompofes hepatic air. 
 
 It is found in many mineral waters, and particu 
 larly in the hot baths of Aix-la-Chapelle. The 
 caufe and mannerof their containing fulphur which 
 was long a problem, has at laft been happily ex 
 plained by Mr Bergman. 
 
 It plentifully occurs in the neighbourhood of vol 
 canoes and in feveral mines. 
 
 Hepatic air is eafily obtained by art, from all 
 forts of liver of fulphur, whether the bafe be an 
 alkali, an earth, or a metal, if any acid is poured 
 upon it ; and the better, if ufe be made of the 
 marine acid, becaufeitcontains phlogifton enough, 
 and does not fo ilrongly attra<5l that of the hepar 
 fulphuris. For this reafon the nitrous acid is not 
 fit for this procefs, as it combines itfelf with the 
 phlogifton, and produces nitrous air. It may 
 iilfo be produced, by diftilling a mixture of ful 
 phur and powdered charcoal, or of fulphur and 
 oil, &c. See the detached article HEPATIC Air, 
 and AEROLOGY-///^ -x. 
 
 III. Phlogifton combined with aerial acid; black 
 lead, or wadd, Plumlago, See the detached article 
 
 It is found, 
 
 a. Of 
 
[ 'Jl ] 
 
 *. Of a fteel-graincd and dull texture. It is na 
 turally black, but when rubbed it gives a dark 
 lead colour. 
 
 b. Of a fine fcaly, and coarfe-graincd texture ; 
 coarfe black-lead. 
 
 IV. Mineral tallow. Serum minerale. 
 
 This was found in the lea on the coafts of Fin 
 land in the year 1736. Its fpecific gravity 
 is 0.770; whereas that of tallow is 0.969. It 
 burns with a blue flame, and a fmell of greafe, 
 leaving a black vifcid matter, which is with more 
 difficulty confumed. 
 
 It is foluble in fpirit of wine only when tarta- 
 rifed: and even then leaves an infoluble reii- 
 duum ; but exprefled oils diflblve it when boil 
 ing. 
 
 It is alfo found in fome rocky parts of Perfia, 
 but feems mixed with petrol, and is there called 
 fchebennaadj tfienpin^ kodrett. 
 
 Dr Herman of Strafburg mentions a fpring in the 
 neighbourhood of that city, which contains a 
 fubftance of this fort difFufed through it, which 
 feparates on ebullition, and may then be col 
 lected. (Kiriuan). 
 
 V. Ambergris. Ambra grlfea. 
 
 It is commonly fuppofed to belong to the mi 
 neral kingdem, although it is faid to have doubt 
 ful marks of its origin (A). 
 
 a It 
 
 (A) Ambergris, according to the aflertion of M. 
 Aublet in his Hijloire de la Guiane}, is nothing more 
 than the juice cf a tree infpiflated by evaporation in 
 to a concrete form. This tree grows in Guyana, 
 and is called cuma but has not been inveftigated by- 
 other botanifts. When fome branches are broken by 
 high winds, a large quantity of the juice comes out ; 
 
#. It has an agreeable fmell, chiefly \vhen burnt : 
 
 b. Is confumed in an open fire : 
 
 c. Softens in a flight degree of warmth, fo as 
 to (tick to the teeth like pitch. 
 
 d. It 
 
 and if it chances to have time to dry, various maiies 
 (fome of which had been fo large as to weigh 1200 
 pounds and more) are carried into the rivers by hea 
 vy rains, and through them into the fea : afterwards 
 they are either thrown into the ihore or eaten by 
 fome fifh, chiefly the fpermaceti whale, known by the 
 name of fibyfettr-macroftpbalus among ichthyologiils. 
 This kind of whale, is very greedy of this gum-refm, 
 and fwallows fuch large quantities when they meet 
 with it, that they generally become fick ; fo that theie. 
 employed in the filliery of thefe whales,- always ex- 
 peci to find fome amber mixed with the excrements 
 and remains of other food in the bowels of thofe 
 whales who are lean. Various authors, :;mong whom 
 is Father Santos in his Ethiopia Orkntalis, \\ho travel- 
 1-ed to various places of the African coaft, and Bomare, 
 fay, that fome fpecies of birds are fond of eating 
 this fubftance as well as the whales and other fifhes- 
 This accounts very well for the claws, beaks, bones, 
 and feathers of birds, parts of vegetables, fhells, and 
 bones of fifh, and particularly for the beaks of the 
 cuttle fifh or fepia oftopedia, that are fometimes found 
 in the mafs of this fubftance. Dr Swediar, however, 
 attended only to thefe laft, though he had mentioned 
 alfo the other fubftances in his paper inferted in the 
 Philofophical Tranfaclions for 1783 ; wherein he at 
 tempts to eftablifh an opinion, that the amber is no 
 thing elfe but a preternaturaliy hardened dung, or 
 feces, of the phyfetcr' whale. Dr Withering and Mr 
 Kirwan have embraced this notion ; as did alfo, inad 
 vertently, the editors of this Work. See 'AMBER.-.' 
 
 GRIS. 
 
C 53 ] 
 
 t!* It is of a black or grey colour ; and of a dull 
 
 or fine grained texture (B). 
 
 The grey is reckoned the beft, and is fold very 
 dear. This drug is brought to Europe from the 
 Indies. It is employed in medicine ; and alfo as 
 a perfume (c). 
 
 VI. 
 
 (B) Mr Aublet brought fpecimens of this gum- 
 refm, which he collected on the fpot, from the cuma 
 tree at Guiane. It is of a whitifh-brown colour with 
 a yellowifh (liade, and melts and burns like wax on 
 the fire. The fingularity of this gum-refm is, that it 
 imbibes very ftrongly the frnell of the aromatic Al 
 liances which furround it ; and it is well known that 
 perfumers avail tbemfelves very confiderably of this 
 advantage. M. Rouelle examined very carefully this 
 fubdance brought over by Mr Aublet, and found that 
 it produced the very fame refults as in other good kinds 
 of amber. Befides Mr Aublet's authority, which is 
 decifive, as being grounded upon direct proofs of faft, 
 Rumphius, quoted by Bergman, long fince menti 
 oned a tree called Nanarlum, whofe infpiflated juice 
 refembles amber. It cannot therefore at prefent be 
 doubted that the origin of this phlogiftic fubftance is 
 the vegetable kingdom, although it may be often found 
 and reputed as a product of the foffile kind. 
 
 This fubftance being analyfed by Meflrs Geoffrey 
 and Newman, quoted by M. Fourcroy, yielded them 
 the fame principles as the bitumens ; viz. anacidfpirit, 
 a concrete acid fait, forne oil, and a charry refiduum : 
 which evidently evinces, that all thefe fat and oily 
 foffile fubiiances have their origin from the other tw<* 
 kingdoms of nature. 
 
 (c) Ambergris is not only brought from the Eaft 
 Indies, but trom the coafts of the Bahama Iflands, 
 Brafil, Madagafcar, Africa, China, Japan, the Moluc 
 ca 
 
L '54 3 
 
 VI. Amber. Airibra JJava t fuccinnm, eleftrum, Lat. 
 Carale, French. Agtjlem^ Bernjkln, Germ. 
 
 This fubftance is dug out of the earth, and found 
 on the fea-coafts. According to the experi 
 ments of M. Bourdelin, it confifts of an in 
 flammable fubftance, united with the acid of 
 
 " common fait, which feems to have given it its 
 hardnefs. 
 
 It is fuppofed to be of vegetable origin, fmce it 
 
 . is laid to be found together with wood in the 
 earth. 
 
 By Diftillaticn it yields water, oil, and a volatile 
 acid fait, which the abovementioned author has 
 
 thought 
 
 ca iflands, the coafts of Coromandel, Sumatra, &c. Dr 
 Lippert, in a treatife he publifhed at Vienna 1782, 
 entitled Phlogiftchgia Mineralis, has copied chiefly 
 from Wallerius what he aflerts of this fubftance. He 
 affirms that there are eight known fpecies of amber; 
 five of a fingle colour, viz. the white and the black 
 from the ifland of Nicobar, in the gulph of Bengal, 
 the alh-coloured, the yellow, and the blackifh ; and 
 two variegated, viz. the grey coloured with black 
 fpecks, and the grey with yellow fpecks. This lad 
 he afferts to be the moil efteemed on account of its 
 very fragranc fmell, and to come from the South 
 coaft of Africa and Madagafcar, as v.-ell as from 
 Sumatra; and that the black dark coloured amber 
 is often found in the bowels of cetaceous fifhes. Thd 
 fame author adds alfo from Wallerius, that by difttl- 
 ling the oil of yellow amber (fucdnum) with three 
 parts and a half of fuming "nitrous acid, a refiduum 
 remains like rofin, which emits, a perfect fmell of 
 nuifk ; whence fome conclude, that the ambergris 
 belongs to the v folnle kind: the contrary, however, is 
 evinced in the preceding note. 
 
c 155- ] 
 
 thought to be the acid of common fait united with 
 a fmall portion of phlogifton. 
 
 Infects, fith, and vegetables, are often found in 
 cluded in it, which teftify its having once been 
 liquid. , , ?..:. 
 
 It is more transparent than. moil of the other 
 bitumens ; and is doubtlefs. the fubftance which 
 fir ft gave rife to eleSrical experiments (on account 
 of the power it poifeffes of attracting little, bits 
 of ftraw, or of other light fubltances, when rub 
 bed). 
 
 Its variecies are reckoned from its colour and 
 . tranfparency. It it is found, 
 
 A. Opaque. 
 
 a. Brown. 
 
 b. White. 
 
 c. Blackifh. 
 
 B. Tranfparent. 
 
 a. Colourleis. 
 
 b. Yellow. 
 
 The greateft quantity of European amber is 
 found in Pruffia ; but it is, befides, collected on 
 the fea-coaft of the province of Skone, and at 
 Biorko ; in trie lake Malaren in the province of 
 Upland ; as alfo inFrarice and in Siberia. It is 
 chiefly employed in medicine and for making var- 
 niflies (D). 
 
 VII. 
 
 . (D) Amber, fays M. Fourcroy, is found in fmall 
 detached pieces, for the mod part under coloured 
 fands, difperfed in beds of pyritaceous earth ; and a- 
 bove it is found wood, charged with a blackifh bitumi 
 nous matter. Hence itJs ftrongly fuppofed that it is 
 a refmous fubftance, which has been altered by the 
 vitriolic acid of the pyrites, not with {landing that we 
 know that acids, when concentrated, always blacken 
 
 and 
 
C '56 ] 
 
 VIL Rock-oil. 
 
 This is an inflammable mineral fubftance, or a thin 
 bitumen, of a light brown colour, which cannot 
 be decompofed ; but is often rendered impure by 
 
 and charry refmous fubftances. In faA, the chemical 
 analyfis of this fubftance rather confirms that fuppo- 
 fition. 
 
 The fmgular opinion of Dr Girtanner, about the 
 yellow amber being produced by a kind of ants, may 
 be feen in Journal de Phyftque for March 1786, page 
 227. Or fee the article AMBER in this Dictionary. 
 
 The colour, texture, tranfparercy, and opacity of 
 this fubftance, have {hown fome other varieties befides 
 thefe mentioned in the text. The principal ones are 
 the following : 
 
 6. The yellow fuccinum, 
 
 7. The coloured green or blue by Q Je< 
 foreign matter. ^ 
 
 S, The veined fuccinum, 
 9. The white, "1 
 
 10. The pale.yellow, f 
 
 11. The citron-yellow, f 
 
 12. The deep-red, J 
 
 The golden yellow tranfparent amber, mentioned in 
 the text, is what the ancients called chryfikarum, and 
 the white opaque was called leucoledrum. 
 
 But we muft be cautious about the value of the fpe- 
 cimens remarkable for their colour, fize, tranfpaYen- 
 cy, and the well-prcferved infects they contain inter 
 nally ; fmce there is a probability of deception, feveral 
 perfons pofTefling the art of rendering it tranfparent and 
 coloured, and of foftening it, fo as to introduce fo 
 reign fubftances, &c. into it at pleafure. 
 
 M. Fourcroy fays, that two pieces of this fnbftance 
 may be united, by applying them to one another, af 
 ter being wet with oil of tartar and heated. And 
 
 Wallerius 
 
 \ 
 
[ '57 ] 
 
 heterogeneous admixtures. By length of time it 
 hardens in the open air, and then refembles a ve 
 getable refin ; in this ftate it is of a black colour, 
 whether pure or mixed with other bodies. It is 
 found, 
 A. Liquid. 
 
 1. Naphtha. 
 
 This is of a very fragrant fmell, transparent, 
 extremely inflammable, and attracts gold. It 
 is collected on the fur face of the water in fome 
 wells in Perfia. See NAPHTHA. 
 
 2. Petrol. 
 
 This fmeils like the oil of amber, though 
 
 more agreeable ; andlikewife very readily takes 
 
 tire. It is collected in the fame manner as the 
 
 P Naphtha 
 
 Wallerius mentions, thnt pieces of yellow amber may 
 be foftened, formed into one, and even diffolved by 
 means of oil of turnip-feed, in a gentle heat ; and 
 that according to fome authors, it may be rendered 
 pure and tranfparent, by boiling it in rape-feed oil, lin- 
 leed oil, faltwater, Sec. 
 
 Mr Macquer fays, that for the purpofe of making 
 varnifh, this iubftance mull undergo beforehand a pre 
 vious decompoiition by torrefaction, in order to be 
 diiiblved by linfeed-oil or eifential oils. S^e VARNISH. 
 
 Befides the making of varnifhes, this fubltance was 
 much employed formerly in making various pieces of 
 ornament and jewellery. The beft pieces were cut, 
 turned, carved, or plained, to make vafes, heads of 
 canes, collars, bracelets, muff-boxes, beads, and o- 
 ther toys, frnall tine chefts, Sec. But after diamonds 
 and beautiful hard ftones were brought into ufe, 
 thefe trinkets are little coniidered in Europe : never- 
 thelefs, they are ftill fent to Perfia, China, and to 
 various other eaftern nations, who efteem them dill 
 as great curiofities. 
 
C >J8 ] 
 
 Naphtha from feme wells in Italy. See PE 
 TROLEUM. 
 
 J5. Thick and pitchy ; Petroleum tenax. Barbadoes- 
 tar. 
 
 This reiembles foft pitch. 
 
 It is found at the Dead Sea in the Holy Land ; 
 in Perfia, in the chinks of rocks, and in ftrata of 
 gypfum and limeftone, or floating on water ; al 
 to in Siberia, Germany, and Switzerland, in 
 coal-pits : and in America : likewife in Cole- 
 brookdale in England. 
 C. Elaflic petrol. 
 
 This is a very fmgular foffil, found of late in 
 England. 
 
 By its colour and confiftency, it exactly refem- 
 bles the Indian -rubber, or the gum-refin, from 
 the north part of Brafil, called caoutchouc. It is 
 of a dark brown colour, almoft black ; and fome 
 is found of a yellowifh brown caft, like the fame 
 gum-refin. 
 
 With refpecl to its elaflic confidence, it hard 
 ly can be diftinguifhed from it, except in the co- 
 hefion of its particles, which is weaker. 
 
 It has the fame property of rubbing off from 
 paper the traces of black-lead pencils. 
 
 It burns likewife with a fmoky flame ; and alfo 
 melts into a thick oily fluid ; but emits a difa- 
 greeable fmell, like the foffiie pitch, or Barba- 
 dpes tar. 
 
 It is found in the fame earthy and ftony beds 
 as petrol. Some fpecimens are of a cylindrical 
 form, like bits of thin branches or ftalks of vege 
 tables, though much more flexible, being perfect 
 ly elaftic. 
 
 M. Magellan obferves, that this foffil feems to 
 favour the opinibn of thofe mineralogifts, " who 
 believe that thefe oily combuftibles derive their 
 origin from the vegetable kingdom. It feems 
 
 worth 
 
C '59 ] 
 
 worth trying, whether pieces of afphaltum, bu 
 ried in damp beds of fparry rubbifh, or other kind 
 of earths, would take the fame elaftic confiftence. 
 But fince many beds of fhells and other foffile 
 fubftances, both of the vegetable and animal kind, 
 as impreflions of various plants, and the remains 
 of various quadrupeds, &c. have been found in 
 different parts of the globe, whofe individual 
 fpecies undoubtedly exift no longer alive unlefsin 
 far diftant climates, and in the mod remote coun 
 tries from the fpot where their exuvia are dug 
 cut ; why fhould we not allow that this new foffil 
 may be the fame original elaftic gum, now grow 
 ing naturally in Brafil, China, and other hot cli 
 mates, only altered in its fmell, and in the tena 
 city of its particles, by its long depofition during 
 centaries in the bowels of the earth ?" 
 
 This elaftic petrol was found in 1785, near 
 Caflfel-town, in the county of Derbyfhire in Eng 
 land, but in very inconfiderable quantities, 
 D. Hardened rock-oil ; foffile pitch. Petroleum in* 
 
 duratum, Plx montana, 
 j. Pure afphaltum. 
 
 This leaves no allies or earthy fubftance when 
 it is burnt. 
 
 It is afmooth, hard, biittle, inodorous, black 
 or brown fubftance. When looked through in fmall 
 pieces, appears of a deep red colour. It fwims 
 in water. 
 
 It breaks with a fmooth finning furface. 
 Melts eafily : and, when pure, burns without 
 leaving any afhes ; but if impure, leaves alhes or 
 a flag. 
 
 According to M. Monet, it contains fulphur, or 
 at leaft the vitriolic acid. 
 
 It is flightly and partially afted on by alcohol 
 and asther. 
 
 P 2 From 
 
t 1 60 ] 
 
 From tliis, or the preceding fubftance, it is pro 
 bable the afphaltum was prepared that the Egyp 
 tians ufed in embalming their dead bodies, and 
 which is now called mummia. 
 
 It is found alfo on the fhores of the Red Sea, 
 in the Dead Sea, in Germany, and France. 
 ( Kirwim , ) 
 
 .And it comes likewife from Poito Principe, in 
 theifland of Cuba. (Britn.) 
 
 It is found iilfo in many parts of China : and 
 is employed as a covering to ihips by the Arabs 
 and Indians. (Fourcroy,} 
 a. Impure ; Fix Montana impura. Pi/Taphaltnm. 
 
 This contains a great quantity of earthy mat 
 ter, which is left in the retoit after diftilla- 
 tion, or upon the piece of charcoal, if burnt in an 
 open fire ; it coheres like a flag, and is of the 
 colour of black-lead : but in a calcining hsat, 
 this earth quickly volatiiiles, fot&at the nature of 
 it is not yet kr.own. 
 
 It is found in Moflgrufran in Norberg 1 , and 
 in Grengierberget, both in the province of Weft- 
 mainland ; and alfo in other places. 
 
 The piiTaphaltum is of a mean confidence be 
 tween the afphaltum and the common petroleum. 
 It is the very bitumen which is collected in Au- 
 vergne in France in the well called de la Pegs, near 
 Ckrmcnt Ferrand. 
 VIII. Jet. Gffgas, Sficcinum mgnnn. 
 This is a very compact bitumen, harder than afphal 
 tum, always black, and fufceptible of a good po- 
 lifli. It becomes electrical when rubbed ; attraft? 
 light bodies like the yellow amber ; and it fwims 
 on water. 
 
 It feems to be nothing elfe than a black Jimber, or 
 fuccinum ; but fpecifically lighter, on account of 
 the greater portion of bitumen that enters into its 
 
 ccmpo- 
 
[ 161 ] 
 
 compofkion. When burned, it emits a bitumi 
 nous Cm ell. See the article JET. 
 IX. Mineralphlogifton united with earths. 
 
 A. With calcareous earth. 
 
 i. With pure calcareous earth. This is the fe 
 tid or fwine fpar formerly defer ibed. 
 
 B. United with calcareous, argillaceous', ponde 
 rous, and (i lie eons earth and vitriolic acid. Li- 
 verftone : Lapis hepdticus. 
 
 C. With an argillaceous earth ; Pit or Stone Coal. 
 
 1. With afmall quantity of argillaceous earth and 
 vitriolic acid. LitLanthrax. See the articles 
 COAL and PIT-COAL. 
 
 This is of a black colour, and of a filming 
 texture : it burns with a flame, and is moftly 
 confumed in th. c i lire ; but leaves, however a 
 fmall quantity of afnes. 
 a. Solid coal. b. Slaty coal. 
 
 2. Culm-coal, called kolm by the Swedes. 
 
 This has a greater quantity of argillaceous 
 earth and vitriolic acid, and a moderate propor 
 tion of petrol. 
 
 It has the fame appearance with the preced 
 ing one, though of a more dull texture : it 
 burns with a flame ; and yet is not confumed, 
 but leaves Behind a flag of the fame bulk or vo 
 lume as the coal was. 
 
 From England, and among the alum rocks 
 at Moltorp and Biliingen in the province of 
 Weftergottland. 
 
 3. Slate-coal. 
 
 This coal contains abundance of argillace 
 ous earth. It burns with a flame by itlelf, o- 
 therwife it looks like other dates. 
 
 It is found at Gullerafen in the parifli of 
 Rettwik, in the province of Dalarne, and alfo 
 with the coals at Boferupin Skone. 
 
 P3 This 
 
This Teams to be the fame with the bitumi 
 nous fchiftus, already defcribed amon.g the ar 
 gillaceous earths. 
 . Canncl-coal. 
 
 Mr Kirwan has put together this variety of 
 coal with that other called KiUhnny-foal, tho* 
 they have fome different properties. 
 
 The cannel-coal is of a dull black colour * 
 breaks eafily in any direction ; and, in its frac 
 ture, prefents a fmooth conchoidal furface, if 
 broken tranfverfely. 
 
 It contains a considerable quantity of petrol, 
 in a lefs denfer irate than other coals ; and 
 burns with a bright lively flame, but is very 
 apt to fly in pieces, in the fire. It is faid, 
 rowever, to be entirely deprived of this pro 
 perty, by being previously immerfed in water 
 for fome hours. 
 
 Its fpecific gravity is about 1270; and 
 being of an uniform hard texture may be 
 eafily turned in the lathe, and receive a good 
 polifh. 
 
 It is from this kind of coal thatfmall vafec, 
 as ink-Hands, various trinkets, and other curi- 
 ofities, are made in England, which appear as 
 if made of the fineft jet. 
 Kilkenny-coal. 
 
 This contains the largeft proportion of pe 
 trol or afphaltum ; burns with lefs flame and 
 {moke, and more flowly.,. though intenfely, than, 
 the cannel-coal. 
 
 The quantity of earth in this coal does not 
 exceed one-twentieth of its weight. Its ipe- 
 cific gravity is about 1400. It is frequently 
 mixed with pyrites. 
 
 It is found in the county of Kilkenny, be 
 longing to the province of JLeinfter in Ireland. 
 The quality of this coal burning almoil with 
 out 
 
[ 163 J 
 
 out fmoke, is znentione4 in a proverb bj 
 which the good qualities of that country are ex- 
 prefied. 
 0- .Sulphureous coal. 
 
 This confifts of the former kinds of coal, 
 mixed with a notable proportion of pyrites : 
 hence it is apt to moulder and break when ex- 
 pofed to the air. It contains yellow fpots 
 that look like metal ; and burns with a ful- 
 phureous fmell, leaving either red afhes, or a. 
 flag, or both. Water acts upon it, after it 
 has mouldered. Its fpeciftc gravity is 1500, 
 or more. 
 
 Befides the above varieties, fchiftus, mica 
 ceous fchiilus, and gneifs, are frequently found 
 in the neighbourhood of coal-mines, fo pene 
 trated with petrol bitumen as to constitute 
 an inferior fpecies of coal ; but the bitumen 
 being burnt, they prelerve their form, and in 
 ft>me meafure their hardnefs. Alfo fome grey 
 toes, that are ib foft as to be fcraped with the 
 nail, and arc greafy to the touch, burn like coal. 
 
 All the differences of coal arife from a mix 
 ture of the varieties already mentioned ; and 
 it is obfervable,. that wherever coals exift, 
 Gates are generally found near them. Salt 
 or mineral fprings are alfa often found in their 
 tie tghbourhaocL 
 
 Bovey coaL 
 
 This is of a brown, or brownHh black co 
 lour, and of a yellow laminar texture. 
 
 The larain.se are frequently flexible when 
 rll dug,, the ugh generally they harden when 
 expofed to the air. 
 
 It confiils of wood penetrated with petrol 
 or bitumen ; an.d fi equently contauis pyrites, , 
 , and .vitriol. 
 
 Its allies afedrafmall quaiuity of oxed al- 
 
C 164 ] 
 
 kali, according to the German chemifts ; but 
 according to Mr Mills, they contain none. 
 
 By diftillation it yields an ill fuelling li- 
 cmor, mixed with a volatile alkali and oil, part 
 of which is foluble in fpirit of wine, and part 
 infufible, being of a mineral nature. 
 
 It is found in England, France, Italy, Swif- 
 ferland, Germany, Ireland, &c. (Kir wan.) 
 
 8. Peat. Geaxtbrax. 
 
 There are two forts of inflammable fub- 
 (lances known by this name, viz. 
 
 The fir ft of a brown, yellowifh brown, or 
 black colour, found in mooriih grounds ; in 
 Scotland, Holland, and Germany, When 
 freih, it is of a vifcid confidence, but hardens 
 by expofure to the air. It confifts of clay 
 mixed with calcareous earth and pyrites ; and 
 fometimes contains common fait. While foft, 
 it is formed into oblong pieces for fuel, after 
 the pyritaceous and ftony matters are fepa- 
 rated. When diftilled, it affords water, acid, 
 oil, and volatile alkali. Its afhes contain a 
 frrjall proportion of fixed alkali. They are 
 either white or red, according as it contains 
 more or lefs ochre or pyrites. 
 
 The fecond is found near Newbury in 
 Berkfiiire. It contains but little earth ; but 
 confifts chiefly of wood, branches, twigs, 
 roots of trees, with leaves, grais, flraw, and 
 weeds. ( Kir<wan. ) 
 
 9. Ctone-turf. 
 
 Cronfteut has ranged the turf among the 
 foflils of h,is appendix ; but as that called in 
 JEngland by the name of fane-turf contains a 
 Considerable proportion of peat, it may be men 
 tioned with propriety in this clafs. 
 
 Soon after it is dug out from the ground, 
 where it keeps a foft confidence, it at firfl har 
 der, s 
 
C '65 'J 
 
 liens ; bnt afterwards it crumbles by long ex- 
 pofure to the air. 
 
 As to the other common tuirf, it only con- 
 fifts of mould interwoven with the roots of 
 veg-tibles; but when thefe roots are of the 
 bulbous kind, or in a large proportion, they 
 form the woril kind cf turf. 
 
 Although it may appear incredible, it is 
 nevertheleis a real fact, that in England pit-turf 
 is advantageoufly employed in Lancafhire to 
 fmelt the iron-ore of that county. Mr Wil- 
 kinfon, brother-in law to Dr Prieftley, and fa 
 mous for his undertakings in the exteniive iron 
 works, perhaps the greateft in Europe, makes 
 ufe of pit-turf in his large fmeldng furnaces of 
 that provim e 
 
 THOSE foffil fubitances, which furnifh fuel for the 
 various purpofes of human life, are diitinguiihed by 
 the name of coals, on account of their being a fucce- 
 daneum for wood and other vegetable productions, 
 which when dry or of an oleaginous kind ferve for 
 the fame ufes. If thefe vegetable fubftances are de 
 prived of the accefs of air, by covering them after ig 
 nition, the half conlumed remainder, which is of a 
 black colour, is called by the name of coal or char- 
 co-J. ; and from hence the foflil which affords fuel has 
 alfo been called by the ia-me name, though of a very 
 different nature. 
 
 Pit-coal and earth-coal are fynonymous, and mean 
 coals dug cut of a pit or from the earth. But the 
 lithanthrax denotes ftone-coal, and more properly in. 
 dicates the cannel-coal, which has the greateft firm- 
 larity to a ftony fubftance, by the dull appearance 
 of its fractures and by the uniform texture of its 
 parts. 
 
 All tkefe coals are in general a bituminous black 
 or biown and dark fubftance : for the moil part they 
 
 have 
 
C 166 ] 
 
 have a lamellated texture, which breaks eafily, and al 
 ways with a fhining furface. 
 
 The varieties of pit-coals abovementioned are the 
 moft remarkable, by which they may be diftinguifh- 
 ed from one another. But they are far from being 
 homogeneous in each kind ; as the accidental quali 
 ties, and the various proportions of their component 
 parts, produce a far greater number of properties, 
 which renders them more or lefs fit for different pur- 
 pofes ; though thefe are generally overlooked, and 
 confounded with the common one of affording fuel 
 for making fire to warm our rooms, or for culinary 
 operations. 
 
 This foffile bitumen, as Fourcroy remarks, being 
 heated in contact with a body in combuftion, and a 
 free accefs of air, kindles the more flowly, and with 
 more difficulty, as it is more weighty and compact. 
 When once kindled, it emits a brifk and very durable 
 heat, and burns for a long time before it is confumed.. 
 If eninguifhed at a proper time, the remaining cin 
 ders may ferve feveral times for a new firing with 
 a fmall addition of frefh coals. The matter that is 
 burned, and produces the flame, appears very denfe, 
 as if united to another fubftance which retards its de- 
 ftruclion. Upon burning, it emits a particular ftrong 
 fmell, which is not at all fulphureous when the earth- 
 coal is pure, and contains no pyrites. 
 
 When the combuftible, oily, and mod volatile parts, 
 contained in the earth-coal, are diffipated and fet on 
 fire by the firft application of heat ; if the combuftion 
 is flopped, the bitumen retains only the moft fixed 
 and leaft inflammable part of its oil, and is reduced to 
 a true charry ftate, in combination with the earthy 
 and fixed bafe. Pit-coals in this charry ftate are call* 
 ed coafa, which are capable of exciting the moft in- 
 tenfe heat ; and are employed all over Britain in the 
 fmelting of iron, copper, and other metallic ores, to 
 
 the 
 
t ? i 
 
 the greatefl advantage. See COAKS, COAI, COAL 
 ERY, and PIT-COAL (E). 
 
 X. The 
 
 (E) The coal-metals, or ftone ftrata inclofing coals, 
 are very numerous. Mr Wiliianis f gives the follow, 
 ing general account of thofe in Scotland. 
 
 "The fand-ftones. Of thefe there is a great Vari 
 ety, diftinguifhable by colour, texture, and degrees 
 of hardnefs, generally difpofed into thick, middling, 
 and thin ftrata. The only fpecies our author takes 
 notice of is the regular broad-bedded free-ftone of a 
 laminated texture. This commonly rifes in thin or 
 middling ftrata; appearing at the edges of a fe&ion,, 
 when broken or cut, to be formed of thin lamina or 
 layers of fand, equally laid on the whole breadth of 
 the ftone, and well cemented together. A great 
 deal of both red and white free-Hone rife in layers of 
 rive or fix inches, and fo upwards, with regular 
 ftreaks of a fifth or fixth part of an inch appearing 
 the whole length of the ftone, when the edge of a llab 
 is polifhed, as if fo many gentle waves of water had 
 formed the layer. The regularity of the ftruclure of 
 this ftone dorrefponds exactly with the regularity of 
 its layers ; and our author is of opinion, that the flag 
 gy grey-ftrata of free ftone, with many of the black 
 and grey-ftrata of coal metals, the grey flate, as well 
 as many other thin ftrata of the coal metals, may be 
 ranked with this free ftone for perfect and regular ftra- 
 tification. 
 
 Along with thefe he clafles fome of the thin argil 
 laceous ftrata. " Many of the grey regularly ftrati- 
 fied mountain limeftones (fays he) are alfo ftreaked 
 or ftriped ; and the ftreaks in thefe appear more con- 
 fpicuous when broken than the ftreaked free ftones. 
 Some of the hard regularly ftratified mountain rocks 
 
 are 
 
 i 
 
C 1 68 ] 
 
 X. The mineral phlogifton or bitumen, united with, 
 the vitriolic acid : fulphur or brimftone. Seethe 
 article SULPHUR. 
 
 This 
 
 are alfo ftratified ; and in all thefe three kinds of ftones, 
 the ftreaks are regularly and exadly parallel to the bed 
 of the ftone." 
 
 Another remarkable inflance of regularity of ftrata 
 i met with in the grey flaggy ftrata of Caithnefs. 
 Throughout all the low country of Caithnefs, afquare 
 of about 10 or 15 miles, there are bluiih argillaceous 
 flrata, with generally a fmall quantity of lime in the 
 competition of the ftone, which is indurated to a grea 
 ter degree than is common to fuch thin ftrata. The 
 ftone is ftrong and tough, every where difpofed in 
 thin broad-bedded, regular ftrata ; and in feveral parts 
 of the country the flags are fo thin and regular, and 
 are raifed fo light and broad, that they are ufed for 
 covering houfes ; and three or four of them will cover 
 the fide of a fmall one. Our author mentions a gen 
 tleman who has an eftate on the fouth fide of the Pent- 
 land frith, and who in a bay there raifes flags of any 
 fize and tbicknefs he pleafes ; fo truly flat and 
 fmooth, that he has only to iquare the edges to make 
 of them good loft floors, partitions, chefts, mangers, 
 roofs of houfes ; in flicrt, he does every thing with 
 them. The face of thefe flags are as fmooth and true 
 a. plane, as if artificially finilhed by the beil work 
 man." 
 
 In mod coal fields there are a great variety of ftrata 
 of different kinds accompanying and lying between 
 the feams of coal, of all forts of colours, confiftencies, 
 and dimenfions; all of them blended together without 
 any certain order or regularity ; fo that if there be 20 
 feams of coal, it is poflible that there may be as many 
 different roofs ; that is, the ftratum which is the iro- 
 4 mediate 
 
t 171 3 
 
 This is very common In the earth, and difcovers it- 
 
 lelf in many an 1 various forms. It is found, 
 A. Native. Sulphur ttativum. 
 
 In 
 
 mediate roof of one feam of coal, (hall diifer from that 
 of another feam in quality, thicknefs, and colour, fo 
 that perhaps ao two of the twenty Ihall be in any re- 
 fpecl alike. 
 
 The various kinds of coal-roofs (a) commonly met 
 with are the following. 
 
 i. Bafaltes. This is very common in Scotland, 
 where it is frequently called whin ftone; and atBorrowf- 
 tounnefs there are feveral thick beds of it between the 
 feems of coal. One of them being the immediate roof 
 of a ieam of coal there at H'llhouie lime quarry, there 
 is a thin feam of coal beneath a beautiful bed of colum 
 nar bafaltes. In the Bathgate hills to the fouthward of 
 Linlithgow, alfo, there are feveral ftrata of coal blended 
 with thole of bafaltes. Thefe bafaltine ftrata are always 
 very hard, frequently very thick, and generally cf a 
 black or blackifh grey colour; " there are but few people 
 (fays Mr Williams) fufficiently verfecl in natural hilto- 
 ry, to know that they are bafaltes, as this kind of rock, 
 both in England and Scotland, goes by the name of 
 ivhln rock, In the north of Scotland it is calledySzwv/y / 
 and among the miners in Cornwall it has the name of 
 cockle (/>)" 
 
 (a) The ftratum which is placed immediately above a feam 
 of coal, is called the roof of the coal, and that v.-'nich is placed 
 immediately below the feam, is called the pavement of the coal : 
 which three, viz. the itratu;n of coal, and its roof and pave 
 ment, with the other concomitant ftrata lying; above and below 
 them, always prclorve thoT ftations and parallelling ; that is, 
 are ail fhotrhecl out and fpread one above another upon the 
 fo.:r.o inclining plane, aud have the fame line of bearing and of 
 declivity. 
 
 (b) We mufi obferve, however, that according to Bergman 
 ar,d other eminent imntralogifts, the cockles or ihirls ought net 
 
 Q, to 
 
I 172 J 
 
 In this the two conftituent parts are mixed 
 in due proportion in regard to each other, ac 
 cording to the rules of that attraction which is 
 between them. It is eafily known, 
 
 i. By 
 
 2. Strata of limeftone of various thicknefTes are met 
 'with in different coal-fields. Sometimes the lime is 
 the immediate roof; but fometimes there is 'an argil 
 laceous ftratum of about the thicknefs of a foot be 
 tween the coal ftratum and that of lime. In the coal 
 fields at Gilmerton, near Edinburgh, are feveral beds 
 of limeftone, fome of them very good, and of confide- 
 rable thicknefs. At Blackburn in Weft Lothian, alfo, 
 there is a ftratum of limeftone fix or feven feet thick, 
 Avhich is the immediate roof of a feam of coal about 
 five or fix feet thick. At Carlops and Spittlehaugh in 
 T weedale, they have a feam of coal immediately below 
 their lime quarries, which they work for burning their 
 lime. 
 
 3. Poft-jlone, a kind of thick and folid ftratum of 
 free ftone, is one of the roofs of coal, generally with 
 out the intervention of any argillaceous ftratum, 
 though fmetimes a ftratum of this kind is inter po- 
 Icd. Frequently this kind of ftone is rendered very 
 hard by a mixture of iron or pyrites. In moft coal 
 fields, thinner ftrata of free ftone are met with as the 
 
 roofs of coal feems. 
 
 4. Dogger-land, as it is called by the Scots colliers, 
 is frequently met with as the roof of coal feams. This 
 name is applied to various lubftances. Sometimes 
 they call ftrata of iron-ftone dogger bands ; fometimes 
 the name is reftricted to the ball iron-ftone ; fometimes 
 to pyrites ; and fometimes the dogger band is a kind 
 
 of 
 
 to be confounded with bafaltes; w-hich laft name does not at all 
 fit thofe iubftances. fee Volcanic PioUi&s in the Appendix to 
 
 1 <his article. 
 
E 173 1 
 
 1. By its inflammability, and by its flame., 
 
 2. By its fmell when burnt; and, 
 
 3- 
 
 of imperfect ilone, compofed of feveral heterogeneous 
 mixtures, among which pyrites bears a considerable 
 proportion, and by which the whole is fo ftrongly 
 bound together, that it is frequently very difficult to 
 break through'it. 
 
 5. Wi'mjtwSi properly fo called, not of a bafallic 
 nature. Thefe roofs are always very hard, and of va 
 rious colours, as black, blackilh grey, brown, red, 
 &c. fometimes not above two or three feet in thkknefs, 
 but fometimes much more. 
 
 6. PQJl-jione) of a fofter nature than that already 
 mentioned. This has no mixture of ferruginous mat 
 ter. 
 
 7. Regular Jlrata offree-jlone, of various colours, tex 
 tures, and thickneiTes, but not fufficiently thick to de- 
 ferve the name of poftjlone, which our author thinks 
 they do not, unlefs they are above three or four feet. 
 Thefe thin flrata of free (tone are very numerous in 
 coal fields, and very frequently form the roofs of ccal- 
 feams. Some of them are three or four feet thick, while 
 others do not exceed three or four inches. They make 
 good roofs, eafily cut through,, and may be readily 
 quarried out for other purpofes. 
 
 8. Grey-bands, or grey-coloured free- (tone, frequent 
 ly form the roofs of coal feams. A great number of 
 them are generally arranged in one place, lying imme 
 diately above one another; and they .are frequently 
 found of all degrees of thicknefs from one to twenty 
 inches, though the mod common dimenfions are from 
 two to fix. By the Scots colliers thefe are called grey 
 
 fekes as well as grey bands. Frequently they are found 
 
 of moderate hardnefs, and fufficiently ftrong to make 
 
 good flags and covers for fev/ers. Thefe roofs are 
 
 Q_2 ftrong 
 
C '74 ] 
 
 By its producing a liver of fulphur, when 
 mixed w;th a fixed alkali, like that made 
 from artificial fulphur. It is found, 
 
 a. Pellucid 
 
 ftrong and fafe when the ftone partakes of the nature 
 of the coal, and has a black or blackiili grey colour j 
 but when they have a mixture of tilly or argillaceous 
 matter, they are more friable. 
 
 9. Blaes, when hard, ftrong, and well Gratified, are 
 reckoned tolerably good coal-roofs. Thefe are always 
 of a bluifti-black or black-grey colour, and are of great 
 variety m refpecl to hardnefs and ftrength. Some of 
 the ftrongeft and hardeft are either entirely black or 
 greyifli black; while iome of the different {hades, of 
 black are pretty thick, and others are but thin. The 
 thickeft, however, are not above 18 inches, and the 
 thinneil two or three inches or lefs. The medium 
 thicknefs is from one foot to three or four inches. Some 
 of them are furTiciently hard to make a good and fafe 
 coal-roof; but they feldom acquire fuch a degree of 
 hardnefs as to give any confiderable obftruclion in fuck 
 ing. All of them feem to have a confiderable quantity 
 of black argillaceous matter in their compofition ; and 
 the ftrong blaes have alfo a confiderable quantity of 
 jfand ; often alfo containing a large portion of ernpy- 
 reumatic oil, and fometimes have a confiderable mix 
 ture of coaly matter. There is a great variety both in 
 the thicknefs and quantity of rhtfe blaes found above 
 feani> of coal. In feme' places the thirncft ftrata make 
 the immediate roof; in ethers, the th.ckcft. Some 
 times we find only five or fix inches of blues upon the 
 coal ; in others as many fathoms, or even much more ; 
 and it is common to find them of all the intermediate 
 thickness. 
 
 I o. WklCtfb and ofa-colourcd argillaceous Jlrata, of mid 
 dling ftrength, are frequently found to be the immedi 
 ate 
 
[ '75 . ] 
 
 a. Pellucid, of a deep yellow colour. 
 
 b. Opaque, white, and greyila. 
 
 Thefe 
 
 ate roofs of coal. Some of thefe are of middling 
 thicknefs, others thin.. They are commonly fouiul 
 from two inches to two feet in tlucknefs. A great ma 
 ny of thefe roofs are very dangerous on account of 
 their fragility ; while others are quite fafe, owing to 
 the more perfect formation of their ftrata, or t3 fome 
 ingredient in their composition. 
 
 ii. Streaked roofs. Thefe are of two {bits : i. Such 
 as are compofed chiefly of land, with a very fro all 
 mixture of clay and blaes ; and, 2, Thofe compofed 
 principally of clay or blaes with a fmall quantity of 
 fand. Some of thefe have large, others i'mall, ftreak-i 
 or ribs. Mr Williams fays that he has feen them ib 
 beautifully ftreaked as to refemble the fineft ftriped 
 cotton fluffs. Thefe ftripes or ftreiaks always lie ex 
 actly parallel to one another, as well as to the bed of 
 the ftone, and are always fpread out the whole bread; h 
 of the ftratum. Their colours are various in d.ffcrent 
 ftrata. fome of the iiripes being nearly bl ick and white:, 
 others v/hite and red, and others yellow and red. In 
 fome the ftripes appear of a lighter and darker grey 
 colour. Some of the finely ftriped Hones have thtir 
 about a quarter cf an inch in diameter ; fome* 
 t'mes ids : an-.l it is con:nyon to fee (tripes from a quar 
 ter to three quarters of an inch broad ; but in the fine 
 ly ftriped Hones it is rare to find them a full inch thick 
 without fome different iuade on one fide or other of 
 the ftripe. The fscond kind of thefe ftreaked roofs, 
 viz. fuch as are compofed of blaes, with a fmaller mi?:- 
 tuie of fand, differ but litth from the former ; only the 
 colours are r.ot always fo bright, nor ;he ft: pes fo fine j 
 neither is the roof quite fo hard. 
 
 I*- Tf* 
 
[ J 7 6 I] 
 
 Thefe are found in Siberia, at Bcvieux m 
 Swiiferland, and at Solfatara near Naples. 
 c. Cryftallifed in octoedral prifms, with blunted 
 points. 
 
 d. Tranf- 
 
 12. The foft I lae roqfs frmetimes confift of pretty 
 thick ftrata ; others of fuch as are thin or ef mid 
 dling thicknefs. There are likewife arrangements or 
 dalles of regularly ftratified blaes, found immediate 
 ly above feams of coal, from three or four inches to fe- 
 veral fathoms in thicknefs, though forne are even met 
 with little exceeding one inch in thicknefs ; though in 
 trie fame place there might be a confiderabls thick 
 nefs of blaes above the coal, taking in all the different 
 ilrata, thick and thin, which lay above it. Some of 
 thefe roofs have an oily appearance on the outfide, and 
 through all the fiifures and joints of the ftrata ; that 
 is, they appear fmooth and gloffy, and are very ilip- 
 pery to the tench. Others have no appearance of this 
 kind ; but all of them are tender, weak, and fragile, 
 fo that they make a very indifferent and dangerous 
 roof. 
 
 13. Another kind of coal-roof confifb likewife o 
 l*/aes, but fuch as are 'r.nperfe8ly jlratijied. It is alto 
 gether the fame in quality and colour as the laft, the 
 only difference that can be diftinguiihed being in the 
 diiFcrent degrees of Gratification. The beds of this 
 kind are not perfect, but unequal ; whence it is a bad 
 and dangerous roof, as great pieces of it are frequent 
 ly apt to fall down by reafon of the inequality and 
 ditlorent joints of the ftrata. Some of thefe blaes ap 
 pear in thick, and others in thin or middling thick 
 beds : while fome have an oily fmoothnefs, called by the 
 Scots colliers crcefky (greafy) blaes. It is owing to this 
 oilinefs particularly that thefe kinds of roofs are fo dan r 
 gerou$ % ; for. the. oil pervad.es the joints, and, icnder- 
 
C 177 1 
 
 Tranfparent. Mr Davila had been informed 
 that this was brought from Normandy in 
 France. (Brim.) 
 
 2. Native 
 
 ing them flippery, makes the pieces more apt to fall 
 out as loon as the coal is worked away from below 
 them. Some of thefe have fuch a quantity of natural 
 oil, that they will flame a little in the fire ; and in 
 fome places there are hard blaes which will burn when 
 fire is let to them, though they will not confume. At 
 Pitfirran in Fitefhire there is a fpecies of thefe blaes fo 
 inflammable, that when fire is fet to one corner of a hil 
 lock it will burn throughout the whole ; neverthelefs it 
 is not reduced in bulk by this combuftion, nor does it 
 produce any afhes. Inilead of this it becomes confidc- 
 rably harder than before, and acquires a pale red co 
 lour. By reafori of its hardnefs, it is proper for being 
 laid upon horfe and foot paths, but is not fo for roads 
 over which heavy wheel-carriages pafs. 
 
 14. Soft blaes not jlrat'ified at all. Of thefe there is no 
 more than one bed from two or three inches to feveral 
 fathoms in thicknefs, without any others either above 
 or below it. They are as common as any above the 
 coal feams ; but their fubftance is not always uniform 
 throughout the whole ftratum. Some of them are 
 found divided into fmall angular maffes, and others in 
 to larger ones ; but whether thefe are uniform or net, 
 they always make a bad and dangerous roof. Thefe 
 argillaceous ftrata are fometimes called beds of till ; the 
 uniform fort are called dauk y and the glebous kir 
 blaes, by the Scots colliers. Both the uniform and gle 
 bous fo ft blaes frequently contain a quantity of ball 
 iron-done, though fome of it contains none at ail. 
 The regular continuous itrata of ironstone are com- 
 aionly found in ftratifisd foft blaes. There is a varior 
 
C 178 ] 
 
 Native fulphur is found in different forms, 
 wa. either in folid pieces of indeterminate 
 figure, running in veins through rocks ; 
 or in fmall lumps, in gypfum and lime- 
 
 ftones ; 
 
 ty of foft coal roofs of a grey odour, and of which 
 fome are regularly ftratified, and fome not. 
 
 1 5 . Regularly J'jft grey coal-roofs. Of thefe there are 
 feveral forts. Some have a confiderable quantity of 
 fand in the composition of the ftrata ; and many of 
 thefe are as regularly ftratified as any coal-metals 
 \vhafever. Numbers are found very thin, and others 
 of middling thicknefs ; though in all cafes they are fo 
 tender and friable, that they make very bad and dan 
 gerous roofs. Some of them indeed look pretty^ well 
 ;it fir ft ; but they foon crumble and comedown, efpe- 
 cially when they have been expofed to the air. This, 
 in the opinion of Mr Williams, is owing partly to 
 their having too much clay in their compofition, aiid 
 partly to the want of a fufficient quantity of natural 
 cement to connect the feveral particles of the ftune to 
 gether. 
 
 16. Soft grey regular f}rata> or grey bands of an ar 
 gillaceous 'kind ; and of thefe there is likewife a con- 
 iiderable variety. Some are of a dark, others of a 
 lighter grey ; feme thick, others thin : they are very 
 numerous in coal-fields, and are frequently to be found 
 as the immediate roofs of coal. Thefe, as v/ell as the 
 black kinds, are found ia all quantities or degrees of 
 thicknefs above different coals, from a few inches iip 
 to feveral fathnms ; but whether they be in great cr 
 fmall quantity, the roof they compofe is generally very 
 frail and tender. 
 
 17. Soft grey argillaceous lands, mpsrfeflly ftraiijicd. 
 Thefe differ little or nothing in fubftance from the 
 former; the only difference is in the {^ratification. 
 
 Many 
 
ftones ; in confiderable quantities at Sol- 
 fatara, and in the neighbourhood of vol 
 canoes ; or cryftallifed in pale, tranfparent, 
 or femitranfparent, octogonal, or rhom- 
 
 boidal 
 
 Many of the flrata of the former are of a middling 
 thlcknefs, or rather thin, finely and regularly fpread 
 out, and every part of each ftratum of an equal thick- 
 nefs. But this fort, though it has the appearance of ftra- 
 ta, is clumfy ah4 irregular ; that is, the feveral beds 
 are unequal, and divided by many irregular joints in 
 to unequal miihapen mafles, which makes this a very 
 bad roof; the maffes being apt to feparate at the 
 joints, and to fall down when the coal is worked out 
 from below them. 
 
 1 8. Soft grey argillaceous led* of metal or coal roofs 
 notjlratified at all. Thefe are of two kinds, viz. x. 
 fuch as are found broken or formed in the ftratum 
 into glebes or mafles ; and, 2. fuch as are found in 
 one ujiifojrm mafs throughout the whole bed, without 
 any dtvifion into maffes or ft ata. Thefe grey foft 
 roofs are of all degrees of thicknefs, from a few inches 
 up to many fathoms, as well as the black ; and there 
 is but very little difference between them in any re- 
 fpecl excepting the colour. Eat in this, .is well as in 
 the black unftmtified blaes, and th.it both in the gle. 
 bous and uniform beds, ball or glebnus iron-done is 
 frequently found ; and ftrata of iron-itone are alfo 
 found in the ftratified foft grey blaes. 
 
 1 9. White and afo-cohured foft argillaceous ccal roofs ; 
 and of thefe there is alfo a great variety. Some of 
 this kind are regularly ftratified ? others imperfectly, 
 and fome not at all. Some of the whitifh argillace 
 ous roofs are compounded of gritty fand and clay ; 
 others appear to be chiefly compofed of pure clay ; 
 and fome of a loamy clay. Thofe which are regu 
 larly 
 
boidal cryftals, in the cavities of quartz ; 
 and particularly in the matrices of ores ; 
 or in the form of fmall needles over hot 
 fprings, or near volcanoes (Kirwan). 
 
 Sometimes it is formed in old privies : 
 cf this Mr Magellan faw feme Jumps that 
 were found in a very old one at Paris. 
 
 2. United 
 
 larly flratified and mixed with fand, either coarfe or 
 fine, are of great variety with regar4>o thicknefs and 
 the arrangements of the ftrata ; htft'all of them are 
 tender and fragile, and thus make very troublefome 
 and dangerous roofs. 
 
 20. Wkiiifk argillaceous roofs, Jlrai'tfed, and of a ho 
 mogeneous quality, or not mixed with fand. Some 
 of thefe are finely and perfectly ftratified, and are of 
 different degrees of hardnefs; but in general, make 
 but a weak roof. Some of them are found in irregu 
 lar ftrata, with all the other varieties and imperfedi- 
 ons already mentioned. 
 
 21. Wilts and ajlo- coloured argillaceous coal-roofs, not 
 jlrat\fi.cd at all. Sometimes thefe are found in 'Very 
 
 thick beds in the coal-fields ; and fomc of thefe, as well 
 as of the black foft roofs, rife in glebes and rnafles of 
 different fizes ; while others are homogeneous through 
 out the whole bed, however thick, from two or three 
 inches to feveral fathoms. Some of thefe beds of white 
 argillaceous mark-like matter are found to be a fancly 
 or loamy clay ; others a pure homogeneous clay, 
 which does not feel gritty between the lingers nor in 
 the mouth. The iliades and varieties of this kind are 
 as numerous as thofe of any of the foregoing ; and 
 all of them, by the Scots colliers, are called dau&, 
 whatever be thein colour. Mr Williams informs us, 
 that he has frequently taken fome of thefe fine white 
 clays to waOi his hands, and has found them anfwey 
 almoft as well as foap. 
 
2. United with clay in the aluminous ore 
 of La Tolfa, and alfo at Tarnowitz in 
 Silefia. This laft refembles a li ; -at grey 
 earth : when dry, burfts or cracks in the 
 wat.rlik: rmrle ; and poffeffes a ftrong 
 peculiar fmeli 1'ke camphor. If diftilled, 
 the fulphur fuhlimes. One hundred parts 
 of *his earth afford eight of fulphur, be- 
 fides gypfum and a quantity of iron. 
 
 3. Mixed with clay, iron, and felenite. This 
 compound is of a grey, brown, or black co 
 lour, found near Rome, Auvergne, Spain, 
 and Iceland. 
 
 4. With limeftone in the form of a calcare 
 ous hepar. This is found at Tivoli, near 
 Rome, and ellewhere in Italy. It is fome- 
 times diflblved in mineral waters, three 
 pounds of which contain as much as 25 
 grains of fulphur. It often forms incruf- 
 tations on the brinks of thefe Iprings. 
 
 5. In the form of an alkaline hepar. This 
 is faid to be found in fome waters in Ruf- 
 fia ; as will be hereafter noticed. 
 
 6. United to iron and clay of pyrites, -&c. 
 of which hereafter. 
 
 7. United to metallic fubftances, as hereaf 
 ter fpecified. 
 
 J5. Saturated with metals (F). 
 
 I. With iron. Pyrites, or copperas-ftone ; Py 
 rites. This is the fubftance from which moil 
 fulphur is prepared, and is therefore ranked 
 
 here 
 
 (F) Sulphur is the mod common mineralifer of me 
 tals ; and therefore moft of its combinations with 
 thofe fubitances fall to be ranked hereafter among the 
 metallic ores. 
 
t i** 3 
 
 here with all its varieties. It is hard, and of a 
 metallic fhining colour. 
 
 A. Pale yellow pyrites ; Pyrites Julflavus. Mar- 
 cafite. This is very common, and contains 
 a propoitionable quantity of fulphur with 
 refpect to the iron ; when once thoroughly 
 inflamed, it burns by itfelf. 
 
 a. Of a compact texture; Pollta piedra del 
 ynca, Htfpanoruin. 
 
 b. Steel-grained. 
 
 c. Coaiie-grained. 
 
 d. Cryftallifed. It {hoots moftly into cubi 
 cal and octoedral figures, though it alfo 
 cryftallifes into innumerable other forms. 
 
 B. Liver-colt ured marcafite. Its colour can 
 not be defcribed, being betwixt that of the 
 preceding marcafite and the azure copper 
 ore. The iron prevails in this kind ; it is 
 therefore lefs fit to have fulphur extracted 
 from it, and alfo for the fmelting of copper 
 ores. It is found, 
 
 a. Of a compact texture. 
 
 b. Steel-grained. 
 f. Goalie-grained. 
 
 o Variously combined with iron and other metallic 
 fubftances. 
 
 1. With iron and copper; forming yellow or 
 marcafitical copper ore. 
 
 2. With iron, lilver, and lead ; potters lead ore. 
 
 3. With iron and zinc ; mock lead, black jack 
 or blende. 
 
 4. With iron and arfenic ; arienical pyrites. 
 
 5. With iron and cobalt. 
 
 6. With iron and bifmuth. 
 
 7. With iron and nickel. 
 
 8. With iron and gold ; pyritical gold ore. 
 
 9. With diver ; glafs filler ore. 
 
 10. With copper 5 grey cr vitreous copper ore. 
 i 1 1. With 
 
11. With lead ; potters lead ore. 
 
 12. With bifmuth. 
 
 13. With quickiilver; cinnabar. 
 
 14. With arfenic ; orpiment, realgar. 
 
 XI. Mineral phlogilton mixed with metallic earths. 
 This is not found in any great quantity : in regard 
 
 to its external appearance, it refembles pit-coal ; 
 
 and the fat fubftance contained in it, at times, 
 
 partly burns to coal, and partly volatilifes in a 
 
 calcining heat. 
 The only known varieties of this kind are, 
 
 A. Mlncra c upn pbloglftlca. 
 
 When it h'-is been inflamed, it retain? the fire, 
 and at lafl burns to allies, out of which pure 
 copper can be fmelted. 
 
 B. M'msra fern phloy/Tica. 
 
 This is not very different in its appearance from 
 the pit coal or fotiile pitch, but it is fome- 
 what harder to the touch. There are txvo va 
 rieties of this fpecies : 
 
 1 . Fixt in the fire ; Mineraferri pUogifllca f.xa. 
 Expofed to a calcining heat, it burns with a 
 
 very languid though quick flame ; it pre 
 fer ves its bulk, and lofes only a little of its 
 weight. It yields above 30 per cent, of iron. 
 
 a. Solid, which refembles black fealiag-wux. 
 
 I. Cracked, and friable. 
 
 2. Volatile in the fire. 
 
 This is unalterable in an open fire,' either cf 
 charcoal, or even upon a piece of charcoal 
 before the flame of the bio v-pipe ; but under 
 a muffle the greateft part of it volatilifss, f > 
 that only a fmall quantity of calx cf iron re 
 mains. It is found, 
 a. Solid. 
 I- Cracked. 
 
 This lad kind leaves more afaes : thefe aflie-, 
 
 when farther expofed to the fire, become 
 
 firil yellowiih-grjen, and afterwards red* 
 
 R difli 
 
C 184 1 
 
 difh-brown ; when, befides iron, they then 
 alfo difcoverfome marks of ccpf.er : it has, 
 however, u<t been poffible to extr.cl: any 
 metallic fubftance from them, the effects 
 of the loadftone, and the colour ccmmuni- 
 cated to the glafs of borax, having only 
 given occafion to this fufpicion. 
 
 CLASS IV. METALLIC SUBSTANCES. 
 
 METALS are thrfe minerals which, with refpect to 
 their volume, are the heavieft of all known be dies. 
 Some of them are malleable; and fome may be de 
 compounded; and, in a melting heat (G), be brought 
 
 (G) The various degrees of heat required to reduce 
 metals to a fluid (late, are feen in the following table, 
 which was extracted, for 'he moft part, by Dr Wither 
 ing, from the printed treatifes of the late celebrated 
 Profeflbr Bergman. It exhibits, in a fimple view, i. 
 Tl'C fpecific gravity of each metal; 2. The degree of 
 heat by Fahrenheit's fcale, in which it melts ; 3. The 
 quantity of phlogiflon it requires for its faturation ; and 
 4. Its attraction to the fame faturatirig pblogifton. We 
 mini, however, obferve, that if the feccnd column 
 bi compared with that of Wedgwood's thermometer, 
 their great difagreements betray fomefundameRtal error 
 in the a (Turned data : for the degrees of heat afligned 
 by Mr Wedgwood for melting gold, filver, and cop 
 per, are mere than quadruple of thofe afllgned by 
 Bergman, and that for melting iron is more than e- 
 leven times greater ; although they both nearly agree 
 in the red heat of iron, which Bergman fays to* be 
 1050 degrees, and Wedgwood 1077. ^- r Magellan is 
 ofopinirn, that the fault: lies in Mortimer's thermo 
 meter, which Bergman quotes with fome diffidence 
 (Sect. 197. of his Sciagrapkia) ; and thinks it probable, 
 that the changes caufed by heat, on this metallic ther 
 mometer, are in a much lefs ir.creafmg proportion by 
 
 intenfe 
 
 
C 185 ] 
 
 back again to their former ftate by the addition of 
 the phlogifton they had loft in their decompofitioa. 
 
 intenfe fire, than thofe indicated by the contradiction 
 of the pure clay, happily employed by Wedgwood in 
 his thermometer. He therefore added another column 
 to this table, marked ffledgw. with the degrees of the 
 melting heats already afcertained by this lad thermo 
 meter, as being the neareft to truth. 
 
 O > !z! W H t? p t- 1 ,0 g 3 O 
 
 r* i <*-*-n ~ ^" ^ 
 
 11. If., ."-.- ? 
 
 ' '.' 
 
 00 CO 00 ^j U O O b,t> OO^OO'^ ^ C^ ?N ^ 
 ^^^O OOO-^ONO-j^^C^XP^ S "K 
 
 OU ^ OOOo -^OONW ^o"o ^^ 
 
 >-< o ^ b 
 
 VO v^ I 
 
 ^j oo -4^ 
 --4 -J O 
 
 MO^ " 
 
 ^ z*$ 
 
 WKJCO OOlWlHH^^^^JQ 
 
 ^4Ot>4 VDON'-JI-^-tJWUi^O 
 
 00 I 3 
 >- ^-4 hn t-r "{ S > -t Oj 
 
 fp' 
 
 TV. ^?. By faturating phlogifton, Profeflbr Bergman 
 means to exnrefs the nrnnottioaate quantities taken 
 
C 1 86 ] 
 
 ee METALLURGY, Part I. Seel, i. and CHEMISTRY- 
 Index at Metallic Calces and Metals. 
 
 All the metallic fubftances contain phlogifton ; and 
 when, to a certain degree, deprived of it, fall into a 
 powder like an earth ; but their attraftions for phlo- 
 giikn are different. 
 
 Moll of them, when melted in a common way, and 
 expcfed to the air, have an earthy cruft formed upon 
 the furfac?, which cannot again be reduced tdhnetal 
 without the addition of fome inflammable matter. The 
 bafe metals have this property. 
 
 But the noble metals, viz. platina, gold, and diver, 
 are fo firmly united to the phlogifton, that they never 
 calcine under fulion, however long continued ; ard, af 
 ter being changed into a calx in the liquid way, when 
 melted in the fire, they reaiTume their metallic form 
 wiihout any other phlogifloa than what is contained 
 in the matter cf heat. 
 
 Quickfilver holds a kind of middle place : for, like 
 the bafe metals, it may be calcined, though not rea 
 dily ; and, like the noble ones, it may be reduced by 
 heat alone. 
 
 We may therefore reckon four noble or perfect me 
 tals ; viz. gold, platina, filver, anil mercury; becaufe, 
 when calcined, they recover their phlogifton without 
 the addition of any phlogiftic fubftauce. 
 
 But as tin, lead, copper, and iron, cannot be redu 
 ced without fiich addition, thefe are called Ignoble and 
 iir.perficl or bafe metals. Kirivar? s Mineralogy. 
 
 However, 
 
 away from each metallic fubftance, when diiTolvcd by 
 means of acids, and of courfe reduced to a calciform 
 ftate. The laft column only expreifes their attraction 
 to this part of their phlogifton, not to that which ftill 
 remains united to them in a calciform ftate. Withering. 
 
However, all thofe eight metals (even mercury, when 
 folid) are malleable to a confiderable degree, and are 
 called entire metals. But 
 
 Bifmuth, zinc, antimony, arfenic, cobalt, nickel, 
 manganefe, molybdena, and wolfram, are fcarce at all 
 malleable, and hence they are called femimetals. Ne- 
 verthelefs, zinc and purified nickel are more malleable 
 than any of the other femimetals ; fo that we have 
 four perfect or noble metals, four imperfect or bafe, 
 eight entire, and nine femimetals (H). 
 
 Order 
 
 (H) MrMongez remarks, that the following are the 
 general properties of metals, when confidered as phy- 
 fical bodies ; viz. their opacity, great fpecific gravity, 
 ductility, tenacity, cryftallization, flavour, and even 
 imell, at leaft in fome of them. 
 
 It is from their denfity that their gravity and opaci 
 ty proceed ; this Lift being fuch, that, even reduced 
 to the thinned plates, no rays of light can pafs through 
 their particles, unlefs there remains an interftice or 
 pore quite free from the metallic fubftance. Gold leaf 
 muft, however, be excepted, which exhibits a fine green 
 by tranfmitted light. 
 
 As to their cryftallization, it has been found to take 
 place whenever they are pure, and left to cool very 
 ilowly by themfelves, after having been perfectly fufed. 
 ( See Journal de Pbyftque for July 1 7 8 1 , p. 74 ) The 
 favour and fmell abovementioncd are very perceptible 
 in the reguline fubftances of arfenic and antimony, as 
 well as in lead, copper, and iron. 
 
 All metals are conductors of electricity ; and more 
 perfectly fo than any other bodies during their union 
 with plilogiften. 
 
 They are foluble either in nitrous acid and in de- 
 phlogifHcated marine acid, or in aqua-regia ; and are 
 preeipitable in fome degree by cauflic alkalies ; and ex 
 cept platina by the Pruflun alkali. 
 
 R 3 When 
 
C 188 
 
 Order I. NOELE or PERFECT METALS. 
 
 I. Gold ; Aunim fol clymlcorum. See the articles 
 Gold; alfb CHEMISTKY-/;^' ; and METAL 
 LURGY, Part II. feel, I. 
 
 When dephlogifticated, they communicate a tinge 
 to borax and to microcofmic fait, or at leaft render 
 them opaque. 
 
 They alfume a convex furface when melted, and even 
 a globular form, if in a fmall quantity ; and though 
 they mix for the moft part with one another whilfl in- 
 fed, yet they refufe to unite with unmetallic fubftan- 
 ces,even their own calces, iron only excepted, which 
 does to its own calx {lightly dephlogifticated and to 
 plumbago. Nickel alfo, and fome others, may contain 
 i'ulphurin their leguline ftate. 
 
 Metals, when calcined, are capable of uniting with 
 other calces and falts. 
 
 Three of the metallic calces have been found to be 
 of an acid nature ; nnz. t;he arfenical, molybdenic, and 
 tungftenic ; from which, by analogy, the nature of o- 
 tlier calces may be conjectured. 
 
 The phlogifton contained in metals is in a pure Rate ;. 
 viz. without water and aerial acid, with which it is 
 invariably accompanied in all other compounds except 
 acid airs and fu'phur. 
 
 When metallic fubftances are naturally found in the 
 e-.mh united to their full fliare of phlogifton, and confe- 
 quently pofTeiling their peculiar properties, they are 
 qalled native. 
 
 But when they are found more or lefs deprived of 
 their phlogiflon and of their properties, combined 
 with other -fubftances, they are then called nilneralfiJ. 
 is the mc.fl. common ftate of the. mineral king-, 
 
[ 1 89 ] 
 
 This is efteemed the principal and firO: among the 
 metals ; and that partly lor its fcamty, but chiefly 
 for the following qualities : 
 
 1 . It is of a yellow fhining colour. 
 
 2. It is the heavieft of all known ! dies, its fpe- 
 cilic gravity to water being as 19,640 to loco. 
 
 3. It is the moft tough and ductile of all metals ; 
 becaufe one grain of it may be ftretched out fo 
 as to cover a lilver wire of the length of 98 yards, 
 by which means T . S . T I 7TT of a grain becomes vi 
 
 4. fible to the naked eye. 
 
 Its foftnefs comes neareft to that of lead, and 
 confequently it is but very little elaftic. 
 
 5. It is fixed and alterable in air and water, and 
 is indeftruclibleby the common action of fire. 
 
 6. When 
 
 dom. The fubflance fo combined with them is called 
 the mlneraltjer^ and the whole is called ore ; by which 
 name are alto diftinguifhed thefe earths and ftones in 
 which metallic fubftances are contained. 
 
 But if both metallic fubftances are mixed together 
 in their metallic or reguline form, without the lofs of 
 phlogifton, they are then faid to be alloyed. 
 
 When the mineralifer is of a faline nature, and ren 
 ders the metallic combination foluble in lefs than 
 20 times its weight of water, the compound is ranged 
 among falts. Thus the vitriols of iron, copper, and 
 zinc, are rather claifed with falts than with ores. 
 
 The moft common mineralifers are, fulphur, arfenic, 
 and fixed air or aerial acid. The lead common are 
 the vitriolic and the marine acids. The phofphoric 
 has been found only in two in (lances ; p/ss. united t 
 lead, difcovered by Gahn ; and to iron, in the fiderite, 
 as Mr Meyer believes. 
 
 Thofe metallic fubftances, mineralifed by aerial acid, 
 a.r called calclform ores* 
 
 M. 
 
[ 190 j 
 
 6. When melted, it reflects a bluifli-green colour 
 from its furface. 
 
 7. It difTolves in aqua-regia, in the dephlogifticated 
 marine acid, and alfo (according to Crell J) in 
 an acid obtained by diftilling vitriolic acid from 
 offmanganefe. 
 
 8. When mixed with a volatile alkali and a little 
 of the acid of nitre, by means of precipitation 
 out of aqua-regia, it burns off quickly, in t!.e 
 leaft degree of heat, with a ftrong fulmination. 
 
 9. It is diflblved, fa forma Jictfl, by the liver of ful- 
 phur, and alfo fomewliat by the glafs of bifmuth( i ). 
 
 10. It is not carried away by the antimony du 
 ring the volatilifation of that femi-metal, and 
 
 M. Magellan obferves, that if the new doctrine of 
 the French chemifts, who afiert, that calces of metals 
 are a compound of dephlogifticated or vital air with the 
 metallic fubftance, were juft, all calciform ores ihould 
 produce this vital air inftead of aerial acid, when they 
 are reduced to their metallic form ; which is not the 
 cafe ; neither fhould all the bafe metals and femimetals 
 absolutely require the mixture of fome phlogiftic fub- 
 ftance in order to their being reduced from the Mate 
 of calces to their metallic form, which otherwife would 
 be quite ufelefs, if their redu&icn fimply conufted ia 
 their feparation from the vital or dephlogifticated air, 
 
 (i) Neither fulphur nor fixed alkali, has any aft ion 
 on gold ; but the liver of fulphur, which is a com 
 pound of both, can diliblve it in the dry way ; fo that 
 if a proper quantity of gold-leaves be put in a cru 
 cible together with liver of fulphur, afid it be melted 
 in a brifk fire, the gold is thoroughly dilfolvecl; 
 and if the whole be diluted in water, the gold will 
 be kept in the folution, and even pafs through the filtre 
 along with it, 
 
 (K) 
 
is therefore conveniently feparated from other 
 17 ictals by the help of crude antimony ; in which 
 procefs the other metals are partly made volatile, 
 and fly off with the antimony, and partly unite 
 with the fulphur, to which the gold has no at 
 traction, unlefs by means of ibme uniting body, 
 or by along digeftion (K). 
 
 11. The phofphorus is faid to have ingrefs into 
 gold (L). 
 
 12. If mixed with a lefs portion of filver, platina, 
 copper, iron, and zinc, it preferves tolerably 
 well its ducYilfty. But, 
 
 13. When mixed with tin, it becomes very brittle ; 
 and it attracts likewife the fmoke of that metal, 
 fo as to be fpoiled if melted on an hearth 
 where tin has been lately melted (M). 
 
 14. It 
 
 ( K ) Antimony is ufed alfo to refine gold from its 
 alloy, as it attenuates and carries off all other metallic 
 fubftances mixed with it, without excepting the filver ; 
 whilft lead leaves this laft behind, and even adds feme 
 of its own to the gold. -PauBon, p. 659. 
 
 (L) Gold, reduced into thin leaves, is not acled 
 upon by the phoiphoric acid in the humid way, though 
 the fire be urged till luminous decrepitations take 
 place ; but when it paffes that point which feparates 
 the humid from the dry way, Mr Margraaf obfer- 
 ved that feme purple fcoria were formed, which is 
 an indication that this concrete acid had partly cal 
 cined the gold during its fuiion. Elements de Chymie 
 tie Dijon, Vol. III. p. 131. 
 
 Beiides this, a drop of the phofphoric acid on the 
 folution of gold by aqua-regia precipitates the metal 
 in its revived ftate, as aflerted by the academicians of 
 Dijon. Magellan. 
 
 ( M ) The fumes of a fmgle grain of tin are capable 
 of rendering hard eight ounces of gold ; but it eafily 
 
 reco- 
 
[ 192 ] 
 
 14. It requires a ftrong beat before it melts, nearly 
 as much or a little more than copper. 
 
 15. It mixes or amalgamates readily with qiiick- 
 filver. See METALLURGY, Part II. feet. I. (N). 
 
 1 6. It is not difiblved by the glafs of lead, and 
 therefore remains on the cupel. 
 
 A. Native 
 
 recovers its malleability by being melted on the fire* 
 (Wallerius and Bomarees Mineralogy.) But when gold 
 is ^ mixed with arfenic, cobalt, nickel; bifmnth, or 
 with the regulus of antimony, it only lofes great 
 part of its malleability ; and when in a certain pro 
 portion, it may be calcined and vitrified with them. 
 (Falronl.) 
 
 (N) Bergman doubts if ever gold has been found 
 perfectly pure ; and Mr Kir wan fays that it is very fel- 
 dom found fo, being generally alloyed with filver, 
 copper, or iron, or all three. As to the gold com 
 monly ufed in toys and other objects of luxury, eve 
 ry one knows that it is purpofely debafed by the ar- 
 tifts with copper or other metals ; and of late it has 
 been employed in various pieces of jewellery, to form 
 ornaftierits of various colours : thus a great alloy of 
 filver (viz. one-third part), gives it a fhade of a green 
 colour ; a fimilar quantity of copper, a reddifli one ; 
 a mixture of arfenic, or filings of fteel, in the pro 
 portion of one-fourth part, gives it a bluifh caft ; fo 
 that having the yellow naturally in the pure gold, 
 and the white in pure filver, the jewellers have al- 
 xnoft all the colours to diver fify their work. Even 
 in the currency of nvoney, there is none coined out 
 of pure gold, which, by common agreement, is cal 
 led gold of 24 carats. The gold coin of England, 
 France, and Portugal, only contains 22 parts of pure 
 gold, and two of alloy, viz. it is only 22 carats, in 
 the common faying; that of Spain is but of 2i T -| 
 
 carats t 
 
C 193 ] 
 
 A. Native gold. With refpecl to the figure or the 
 quantity in which gold is found in one place, it 
 is by miners divided into, 
 
 1. Thin fuperficial plated or leaved gold ; which 
 con flits of very thin plates or leaves, like paper. 
 
 2. Solid or maflive, is found in form of thick 
 pieces. 
 
 3. Cryftallifed, confifts of an angular figure. 
 
 4. Waih gold, or gold duft, is wafhed out of 
 fands, wherein it Les in form of loofe grains 
 and lumps (o). See other diftinclions of 
 form under the article GOLD. 
 
 J5. Mineralifed gold. This is an ore in which the 
 gold is fo far mineralifed, or fo entangled in other 
 bodies, as not to be diflplved by the aqu;a-regia. 
 
 1. Mineralifed whh fulphur by means of iron. 
 Marcafitical gold-ore ; Pyrites aureus. 
 
 2. By means of quickfilver. It is found in 
 Hungary. 
 
 3. By means of 2mc and iron, or filver. The 
 Schemnitz blende. 
 
 See 
 
 carats : but the dncat of Holland is of 23|4 carats ; 
 and the zecchino of Venice, of i$\\ carats: which 
 lad therefore, it would feem, is the purefl gold coin of 
 Europe. (Paudon's Metrologte.) 
 
 (o) M. Daubenton, in his Methodical Tables of 
 Mineials, enumerates eight forts of native gold, viz. 
 i. In powder ; 2. In grains ; 3. In fmall fpangles ; 
 4. In malles or lumps ; 5. In ftiaments ; 6. In bran 
 ches like vegetables; 7. In lamella; and 8. In oclo- 
 edral cryflals. He obfervcs alfo, that gold, in its 
 reguline (late, is formed, either i. Into angular cry- 
 ftals, compofed of yellow octoedres ; or, 2. Into irre 
 gular yellow mafTes, which, being broken, ihow a gra~ 
 nular iiibftancs. 
 
[ '94 3 
 
 See otiier varieties of mineralifed gold ores 
 under the detached article GOLD, 'already re 
 ferred to. 
 
 IT. Silver: Argentum, Luna. See the article SILVER. 
 See alfo CHEMISTRY-//.'^; and METALLURGY, 
 Part II. feel. iii. and Part III. left. iii. 
 This metal is, 
 
 a. Of a vrhite fliining colour. 
 
 b. Its fpecific gravity to water is, according to 
 Cronfledt, as 11,091 to 1000; accordir.)- to 
 Bergman, = 10,552 ; and according to Kir- 
 wan, 11,095. 
 
 c. It is very tough or du&ile, 'fo that a grain of 
 it may be frretchcd rut to three yards in 
 length and two inches in breadth. 
 
 d. It is unalterable in air, water, and fire. 
 
 e. It diflblves in the acid cf nitre, and alfo by 
 boiling in the acid of vitriol. 
 
 f. If precipitated out of the acid nitre with 
 the common fait, or with its acid, it unites 
 fo ftrongly with this laft acid, that it does not 
 part from it, even in the fire itfelf, but melts 
 with it into a rnafs like glafs, which is called 
 him cornea (p.) 
 
 (p) The marine acid attracts the calx of filver, but 
 cannot remove its phlogifton ; and therefore cannot 
 diflblve it in its metallic {late, (Bergman.] However, 
 the marine acid, if well concentrated, or rather re- 
 duTcdipto an aerial form, difiblves filver in its metal 
 lic flare, (Fabronl.) 
 
 Mr Scheele, and after him Mr Bertholet, aflert po- 
 fltirely, that the marine acid, being dephlogiilicated 
 by its diftiilation over manganefe in the form of a yel 
 low air or gas, difiblves all the metals, without excep- 
 
 I ting 
 
[. 195 1 
 
 n. It does not unite with the fcm'-metal nickel 
 during the fufion. . 
 
 b. It amalgamates eafily with quickfilver. 
 
 z\ It is in the dry way difTolved by the liver of 
 fulphur. 
 
 k. It has a ftrong attraction to fulphur, fo as rea 
 dily to take a reddith yellow or black colour 
 when it is expofed to liver vapours. 
 
 /. If has no attraction to arfenic ; whence, when 
 the red arfenical filver ore, or ret/.^ultkn ertz 
 of the Germans, is put into the fire, the arfe 
 nic flies off, and leaves the fulphur (which in 
 this compound was the medium unutu,) behind, 
 united with the filver in form of the glafs di 
 ver ore, or glafs ertz. 
 
 m. It is not diffolved by the glafs of lead, and 
 consequently it remains on the cupel. 
 
 n. It is exhaled or carried off by volatile metals 
 and acids ; as by the vapours of antimony, 
 zinc, and the ac'd of common fait. 
 
 o. According to Cronftedt, it melts more eafily 
 than copper ; and this was a general opink :. 
 But the contrary, as Mr Magellan remarks, 
 has been proved by means of the nice ther 
 mometer lately invented by Wedgewood. 
 See THERMOMETER.. 
 
 Silver is found, 
 
 A. Native 
 
 gold, filver, or mercury. See Scheele's Effay 5. 
 
 The vitriolic acid being diRilled alfo over tfre man- 
 , diifolves filver, sjold, and mercury, as Dr Crell 
 illerts, (Journal de PLyfiqne, Oct. 1785, p. 297.) 
 Sliver is precipitated from the vitriolic and nitrous 
 -:.rine ; and from the nitrous, in great 
 lie, (Kir wan.) 
 S 
 
st. Native or pure ; which mod generally is nearly 
 of 16 carats ftandard (CL). 
 
 1. Thin, fuperficial, plated or leaved. 
 
 2. Ip form, 
 
 a. Of fnaggs, and coarfe fibres. 
 
 b. Of fine fibres. Capillary filver. 
 r. Arborefcent. 
 
 cl. Cryftalline or figured. This is very rare : 
 
 it has diftincl fibres, with fhining furfaces. 
 JS. Mixed or alloyed with other metals. 
 
 The following are the known inftances of thefe 
 mixtures : 
 
 1. United to gold, (Bergman's Scingraphia, 154.) 
 
 2. Mixed with copper ; (Berg. Sc. 155.) 
 
 3. United to gold and copper ; (Berg. Sc. 156.) 
 
 4. Amalgamated with mercury, found in the 
 mines of Salberg ; (Fojler's notes to Brunnich.) 
 
 5. United to iron ; (Berg. Sc. 157.) 
 
 6. United to lead, fometimes in fuch quantities 
 as to be worth the expences attending the fe- 
 paration. 
 
 7. United to arfenic ; (Journal de Phyjique, 1778, 
 p. 50.) 
 
 8. United to antimony ; (Berg. Sc. 159.) 
 
 9. Joined to the regulus of arfenic and iron ; 
 (Berg. Sc. 160.) 
 
 10. Mixed with the alkaline limeftone from 
 Annaberg, defcribed by Mr Jufti ; (Brun- 
 M.) 
 
 1 1 . Sandy filver-ore, without pny metallic fhining. 
 
 12. Silver-ore in a red-brown fchillus, defcribed 
 by Lehman : it is ccmpofed of argillaceous 
 
 earth, 
 
 (qj Wallerius diftinguifhes feven fpecies of filver : 
 (fee the article SILVER). Dauhenton reckons eight 
 varieties of nathe wbifefiher, arifing from their pecu 
 liar forms. 
 
C 19? ] 
 
 earth, micaceous hematites, fulphur, calcarfc- 
 ous fpar, fluor mineralis, lead, and filver. 
 It contains about feven or eight ounces of iil- 
 ver on the hundred weight. 
 1 3. Soft filvgr-ore. It is found among the marles 
 and argillaceous earths ; and is of various co 
 lours, either fmgly or mixed. 
 C. Diffblved and mineralifed. 
 (i.) With fulphur alone. Glafs filver ore. 
 This is duclile, and of the fame colour as 
 lead ; tfl& however, becomes blacker in*the 
 air. It has therefore, though very improper- 
 ly, got the name of glafs-ore ; for that name 
 rather belongs to the mlnera argcn'i cornea* 
 or horn filver ore, if indeed any filver ore 
 can be confidered as glafly. 
 It is found, 
 
 1. In crufts, plates, or leaves. 
 
 2. Grown into 
 
 ft. Snaggs, and 
 
 b. Cryitalline figures. 
 
 It is generally either of a lamellar or a 
 
 grained texture. 
 
 The glafs filver ore is the richeft of all filver 
 
 ores ; fmce the fulphur, which is united 
 
 with the filver in this ore, makes but a very 
 
 fmall quantity of its weight 
 
 (2.) Arfenico-martial filver ore, Wall ertz, 
 
 Germ.) 
 
 This ore contains illvcr and iron mineralifed 
 by arfenic ; the arfenic in a larger propor 
 tion than the iron. This is the Pyrites ar- 
 gentcus of Henckel. 
 
 1. It is a hard fubftance, of a white (liming 
 appearance, and of a compact, lamellar, or 
 fibrous texture. (Kiriuan, fp. 7.) 
 
 2. Of a yellowiih white colour, and of a (Iri- 
 a:?d ftruflure, refembling bifmuth, but 
 
 S 2 much 
 
r i 9 s ] 
 
 much harder. [Kirwan, fp. 3.) It is 
 found near Guadanal canal in Spain. 
 
 3. Near the fame place is found alfo another 
 ore of the fame kind, which is very ibft and 
 eafily cut ; and when cut, has a brilliant 
 metallic appearance. It confifts of con- 
 choidal laminae. The quintal contains only 
 from four to fix ounces of filver ; but it is 
 eafily reduced by evaporating the arfenic, 
 which then leaves the fifrer flightly conta 
 minated with iron. (KJfrwan, fp. 4.) 
 (3.) With fulphur and arfenic. The red or 
 ruby-like filver ore. The rotbguldcn of the 
 Germans. 
 
 The colour of this ore varies as the propor 
 tion of the ingredients varies in the mix 
 ture, viz. from dark grey to deep red ; but 
 xvhen it is rubbed or pounded, it always 
 gives a red colour. 
 
 a. Grey arfenical filver ore. 
 
 1. Plated, crufted, or leaved. 
 
 2. Solid. 
 
 b. The red arfenical filver ere : 
 
 1. Plated crufted, or leaved ; 
 
 2. Solid or fcaly. 
 
 3. Cryftallifed(R.) 
 
 In 
 
 (R) Wallerius mentions the fix following varieties 
 of this notable ore in his Species 388, viz. i. The red 
 opaque, like cinnabar, from Andreafberg in the Hartz, 
 and from Salberg in Weflmannia : 2. The bluifli, from 
 Freiberg and Annaberg : 3. The grey, from Freiberg 
 and Andreafberg : 4. The red tranfparent amorphous, 
 of the garnet colour, from Potcfi and loachimu 1 al : 
 5. The red tranfparent, cryftallifed into prifmatic de- 
 caedres, or dodecaedres, from Hungary, Alface, and 
 
 the 
 
[ 199 J 
 
 In this laft form it Ihows the moft beati- 
 tiiul red colour, and is often femi- 
 tranfparent. It contains about 60 p:r 
 cent, in filver. 
 
 (4.) With fulphur, little arfenic, and iron. 
 Schwartz, ertz Schwartz gu/dtrt, Silber muun. 
 Germ.) 
 
 This is a friable, weathered, decayed ore. 
 a. Of a black or footy colour ; and is there 
 fore called by the Germans J^tterfekwartz,, 
 or ru/Jjgtes-enz,. 
 (5*) With fulphurated arfeni: and copper. The 
 
 tv ij^dden of the Germans. 
 This, in its folid form, is of a light grey co 
 lour, and of a dull and fteel-grained tex 
 ture. Its proportion of filver is from 10 to 
 ^O per cent. 
 
 (6) With fulphurated arfenic and iron. The 
 tvsifertz, or while filver ore of the Germans. 
 This is an arfenical pyrites, which contains 
 Silver; it occurs in the iaxon mines, and fo 
 exactly refembles the common arfeuical py 
 rites, as not t) be diftinguifhed from it. by 
 fight alone, or without other means. 
 (7.) With fulphurated antimony. 
 
 a. Of a dark grey and fomewhat brownifn co 
 lour ; the labcrel-z, of the Germans. 
 I. Of a blackifh blue colour. 
 
 i. In form of capillary cryftals. FqdereriZy 
 
 or plumofe filver ore. 
 (8.) With iron, arfenic, and cobalt, inineralifed 
 
 by fulphur. 
 
 This ore looks like the f iu?:ij~^.!.! i n defcribcd 
 
 above ; but is diftinguifhed by the rofe co- 
 
 S 3 loured 
 
 the Duchy of Deux Fonts : 6. The only fuperficially 
 red ore, from Salberg and EhrenfriederichRlorf. 
 
[ 200 ] 
 
 loured particles of cobalt, difperfed through 
 dark brown, blackifh, or grey, and fometimes 
 fhining folid mafs. It is to this fpecies of 
 ores that the filver goofe dung ore belongs. 
 (9.) With fulphtirated copper and antimony. 
 
 The Dn\fat>-Iertiz. 
 
 This refembles both in colour and texture the 
 dark-coloured weiffgialden. When rubbed, it 
 gives a red powder. 
 
 a. Solid. 
 
 b. Cryftallifed. 
 
 (10.) With fulphurated zinc. The pechllsndc of 
 
 the Germans. 
 This is a zinc ore, mock lead, or blende, 
 
 which contains filver, and is found among 
 
 rich filver and gold ores. 
 a. Of a metallic changeable colour. 
 
 1. Solid and with fine fcales. 
 
 2. In form of balls. The kugel-erte, or ball ore. 
 I, Black mock lead, r blende, found in 
 
 Saxony. This is alfo found, 
 
 1. Solid, and with fine fcales ; 
 
 2. And in form of balls. 
 
 ( 1 1. ) With fulphurated lead; potters ore. Ga~ 
 
 Una ; lleyglanz,. 
 
 (12.) With fulphurated lead and antimony, call 
 ed Jtiiperz. 
 ( i 3- ) With fulphurated iron. Silberhalitgier lues ; 
 
 marcafite holding filver. 
 
 (14.) With fulphurated and arfenical cobalt; 
 dentil fces being fometimes found in the (tone. 
 Thefe kinds keep well in water ; but general 
 ly wither in the air, and lofe the filver they 
 contain. 
 
 (15.) Mineralifed by fulphur, with regulus of 
 antimony and barytes. The butter-milk ore., 
 This is found in the form of thin particles, oa 
 granular fpar, (Kirwan, fp. 13.) 
 
 (16. Coir* 
 
[ 201 ] 
 
 (16.) Combuftible filver ore. 
 
 This is a black and brittle fubftance, and 
 
 leaves about 6 per cent, of filver in its afhes. 
 
 It is in fact a coal in which filver is found. 
 
 (Kir<wan, fp. 14.) 
 
 (17.) With the acid of common fait. Minera 
 
 argenti cornea. Hornefz, or horn-filver ore. 
 This is the fcarceft fdver ore ; it is of a white 
 or pearl colour, changeable or varying on 
 the Aiiface, femi-tranfparent, and fomewhat 
 ductile both v\hen crude and when melted. 
 It cannot be decompofed without forne ad 
 mixture offuch fabllances as attract the acid 
 offea.falt. 
 III. Platina del Pinto ; Juan blanca* 
 
 This metal is a recent difcovery of our times ; and 
 is defcribed with great accuracy by Scheffer, in 
 the Acts of the Royal Academy of Sciences at 
 Stockholm for the year 1752; as alfo by Dr 
 Lewis, in the Philosophical Tranfaclions for the 
 year 1754* vol. xlviii. and by many other wri 
 ters. By thefe defcriptions we are convinced of 
 the refemblance this metal bears to gold ; ancl 
 therefore wemuft allow it to be called white gold. 
 It has, however, a variety of diftinguiiliing qua 
 lities befides its colour, which afcertain its pecu. 
 liar nature : All which, with its hiflory, ufes, 
 Sec. are particularly defcribed under the detached 
 article PLATINA. See alfo CHEMISTRY-//^* ; and 
 METALLURGY, Part II. Sect, ii. 
 
 1. It is of a white colour. 
 
 2. It is fo refractory in the fire, that there is no 
 degree of heat yet found by which it can be 
 brought into fufion by itfelf, the burning- 
 glafs excepted. But, when mixed with 
 other metals and femimetals, it melts very 
 eafily, and efpecially with arfcnic, both in 
 its. metallic form and in form ofa calx orglafs. 
 
 IV, 
 
[ 202 ] 
 
 JV. Quickfilver, mercury. Hydrargyrum^ Argentum vi- 
 <vum> Mercurius. See the article QUICKSILVER; 
 CHEMISTRY-/WW, at Mercury ; and METALLUR 
 GY, Part II. feet, vlii. 
 
 Mercury diftinguifhes itfelf from all metals by the 
 following qualities (s.) 
 a. Its colour is white and fhining, little darker 
 
 than that of filver. 
 I. It is fluid in the cold, and divifible by the lead 
 
 force ; but, as it only (licks to a few bodies to 
 
 which it has an attraction, it is faid that it 
 
 does not wet. 
 c. It is volatile in the fire. 
 
 d. It 
 
 (s) It were almoft fuperfluous, fays Mr Kirwan, to 
 mention any other character of quickfilver than its li 
 quidity, to diftinguifh it from other metals. In re 
 gard to this property, Bergman obferves, that mer 
 cury constitutes one extreme among the metals, and 
 platina the other ; fmce it requires to be melted only 
 in fuch a degree of heat as is rarely wanting in our at- 
 mofphere, and boils at the 600 degrees nearly after 
 lead melts. See the table at p. in. Note. But when 
 the cold is increafed to the temperature denoted by 40 
 degrees below both of Fahrenheit's and of the Swediih 
 thermometer, which both coincide in that point (fmce 
 212 32, or 180 : 100 : : 32+40, cr 72 : 40), this 
 metal concretes like any ether metal, and becomes 
 quite folid ; (fee Philofophical Tranfactions for 1783, 
 p. 303.) Mercury in its common (late, therefore, 
 according to Bergman (Treatife cf Ele<3, Attract, j, is 
 to be confidered as a meul in fufion ; and fmce in its 
 {olid (late it is nearly as malleable as lead, it by no 
 means ought to be placed among the femimetals, 
 btherwife every other entire metal fhould be confide 
 red' as brittle, for none is malleable when in fufion. 
 
C 203 J 
 
 (1. It attraJb the other femimetals and metals : 
 and unites with them all except cobalt and nic 
 kel, with which it cannot by any means yet 
 known be made to mix. This union is called 
 amalgamation. This amalgamation, or mix- 
 tion of metallic bodies, according to the rea- 
 dinefs with which they unite or mix, is in the 
 following progreilion, vi:s. gold, filvcr, lead, 
 tin, zinc, bifmuth, copper, iron, and the rc- 
 guhis of antimony ; the three latter, how 
 ever, do not very readily amalgamate. The 
 iron requires a folution of the vitriol of iron, 
 as a medium to promote the union. 
 
 f. It diilblves in fpirit of nitre, out of which it is 
 precipitated by a volatile alkali, (T) and com 
 mon 
 
 (T) i. Mercury is diiTolved with great rapidity by 
 nitrous acid : the liquor is of a greenifh blue colour, 
 but afterwards lofes it and becomes limpid. This fo 
 lution, when made without heat, is ufed as a teft 
 for the analyfis of mineral waters, and has different 
 properties from that made with the help of he.it. In 
 the firft cafe, fays Bergman, very little phlogiilon is 
 loft, and the fait eafily cryftallifes, being white and 
 fcarcely acrid. It is not precipitated by diftilled wa 
 ter ; but by cauftic vegetable alkali, it is precipitated 
 of a yellowifh colour ; by mild alkali, the precipita 
 tion is white ; by mineral alkali, it is yellow, but it 
 foon grows alfo white ; by volatile alkali, it turns to a 
 greyifh-black colour ; by Glauber's fait or by pure vi 
 triolic acid, the precipitation is white, granulated, and 
 in a fmall quantity ; nor, if this precipitant has been 
 fparingly ufed, does this colour appear in lefs than an 
 hour ; by muriatic acid, or common fait, the pre 
 cipitation is alfo white, but in a Urge quantity, and in 
 curdles. 
 
 2. But 
 
[ 204 ] 
 
 mon fait, in form of a white powder ; but if 
 <i fixed alkali is ufed, a yellow powder or calx 
 is obtained 
 
 2. But if the mercurial folution be put over a fand- 
 hcat, it may be charged with a quantity of mercury 
 equal almoft to its weight. Ac-cording to the chemiils 
 of Dijon, 10 ounces of nitrous acid may diflblve eight 
 of mercury. The action of the folvent becomes ftronger 
 with the heat ; emits great quantity of vapours ; und 
 if not taken from the fire, will be too far evaporated. 
 Difiilled water will precipitate from this fulution a 
 Avhite calx, becaufe it is more dephlogillicated, and 
 t:he folvent is overcharged with it ; and the water 
 changing the denfity of the liquor, diminilhes the 
 adheiion of the calx, as Fonrcroy remarks. This 
 white calx w'll turn yellow, if boiling water be pour 
 ed on it. The vegetable alkali precipitates it of a 
 brownilli yellow, which by degrees afTumes a pale 
 yellow tinge: the mild vegetable, and the mineral al 
 kalies, produce nearly the fame colour ; though when 
 this laft is employed, the colour turns afterwards to 
 white. The precipitation by volatile alkali is quite 
 white alfo ; that by the vitriolic acid is yellow ; and 
 finally, a copious, white mucilaginous matter is the 
 precipitate by the marine acid. 
 
 $. This folution by nitrous acid is very cauft'c ; 
 corrodes and deftroys animal fubftances ; when it 
 falls on the (kin, ftains it of a deep purple brown co. 
 Icur, which appears black : the ftains do not go oiF 
 Before die fepar.uicn of the epidermis, which Kills a- 
 way in fcales or a kind of fears. It is ufed in furgery as 
 a powerful efcharotic, and is called mercurial <wc t lcr. 
 
 4. The fame folution, by cooling, is fufceptible of 
 forming cryftals, which vary from one another ac 
 cording to circumftances : for the moil part they are 
 like needles ; are very cauftic ; redden the {kin ; av-.l 
 
 detonate 
 
C 205 ] 
 
 /. But it requires a boiling heat to diffolve it in 
 
 oil of vitriol (u). 
 g. It is not affected by the acid of common fait, 
 
 unlefs it be previoully di delved by other acids 
 
 detonate when put on burning coals, provided they be 
 dry. They are called mercurial nitre, which fufes when 
 heated in a crucible ; exhales reddifn fumes ; afiumes a 
 deep yellow colour, which afterwards turns to orange, 
 and at laft to a brilliant red : in this ftate it is called 
 rtd precipitate, or arcanum coraliinum. It mufl: be made 
 in a rrmtrafs with a gentle heat if it is defigned to be 
 corrofive for chirurgical purpofes. 
 
 (u) i. The vitriolic acid, concentrated and boiling 
 hot, feizes on mercury, and prefently reduces it if ur 
 ged by heat to a kind of white powder, which turns 
 yellow by the afTufion of hot water, but does not dif- 
 iblve in it : this is called turlith mineral : but if cold 
 water, inftead of hot, was poured in the white rnafs, 
 the powder would not change its wlute colour into yel 
 low as was faid above about the nitrous folution. 
 
 2. If Mercury be rarefied by heat into vapours, nnd 
 theie meet with thofe fomarine acid in the fame ftate, 
 corrofive fublimate at will be formed. This metallic 
 fait fhoots into cryftals pointed like daggers, which are 
 the ftrongeft of all poifons. But there are various o- 
 ther procefies found in chemical authors to make this 
 fait with more or kfs trouble. See CHEMISTRY, n 
 814 8 [8. 
 
 3. If corrofive fublimate be mixed with tin and di- 
 ftilled, a very fmoking liquor is produced, called by 
 the name of its inventor the footing licitor r.f Libavius. 
 See CHEMISTRY, n oic. 
 
 The muriatic acid in the fublimate is net faturated, 
 and from hence proceeds its great corrofive power ; for 
 if afrefii quantity of mercury be added to L, and fub- 
 iimed a fecond or third lime, a fweet, or mixed fub 
 limate 
 
[ 206 ] 
 
 (v) ; in which cafe only they both unite with 
 one another, and may be fublimed together ; 
 this fublimate is a Mrong poifon. 
 It unites with fulphur by grinding ; and then 
 produces a black powder called atbiops mincra- 
 lis (w), which fublimes into a red ftriated body 
 cinnabar. 
 
 limate, called m.rcurius dulcis, is produced, which is 
 not poifcnous, and is given internally as a purgative, 
 or anemetic, according to the dofe. See CHEMISTRY, 
 n8i9. 
 
 (v) Muriatic acid does not act upon quickfilver un- 
 lefs this lait be previoufly deprived of as much phlogi- 
 fton, as TTO^O of the quantity contained in the hundred 
 of filver, or of T y T in the hundred of zinc. (See Berg 
 man's Sciagraphia, and his treatife De Phlogijti qvami- 
 tatc.) 
 
 (w) The academicians of Dijon fay, that the true 
 proportion to make this sethiops, is that of one part 
 of brimftone witlrfour of mercury. Fourcroy directs 
 cnly one of mercury, with three of flowers of fulphur, 
 to be triturated, till the mercury is extinguished. A 
 black powder is then produced, which is the sethiops 
 mineral. The combination is better effected when the 
 mercury is mixed with die fufed fiilphur : by agita 
 ting this mixture, it becomes black, and eafily takes 
 fire ; it fhould be then^token from the fire, and the 
 flame fhould be extinguished a little after, Mining the 
 xnafs till it becomes into folid clots. If this fubftance 
 be expofed to a great degree of heat, it takes fire, the 
 fulphur is confumed, and a fubftance remains which is 
 of a violet colour when pulverifed. This powder be 
 ing put into malraiies, till their bottoms become red 
 by the force of fire, is fublimed after fome hours, and 
 artificial cinnabar is found in the top of the veiiels cry- 
 ftallifed into brown red needles. 
 
 2 Mercury 
 
I 207 ] 
 
 i* Thefulphur is again feparated from the quick- 
 filver, by adding iron or lime, to which the ful- 
 phur attaches itfelf, leaving the quickfilver to 
 be diftilled over in a metallic form ; but if a 
 fixed alkali be ufed, fome part of the quickfil 
 ver will remain diiTl ved in the refiduum, which 
 is a liver of fulphur. 
 
 Quickfilver is found, 
 
 A. Native, or in a metallic flate. Msrcunus nati- 
 
 wist or virgineus. 
 
 This is found in the quickfilver mines at Idra in 
 Friuli, or the Lower Austria, in clay, or in a 
 black flaty lapis ollaris, out of which it runs, 
 either fpontaneoufly, or by being warmed even 
 in the hands. 
 
 B. United to gold or filver. Hydrargyrum argents 
 
 vel aitro adunatum. 
 
 Mr Kirwan aflerts, on the authorities of Monet 
 and Lin, Von Gmelin, that in Sweden and 
 Germany mercury has been found united to 
 filver in the form of a fomewhat hard and brit 
 tle amalgam. 
 
 Rome de 1'Ifle had a fpecimen of this natural 
 amalgam from Germany, which is imbedded 
 in a quartzofe mafs, and mixed with cinnabar, 
 as Mr Mongez afferts ; and he adds, that in 
 the royal cabinet, at the king's garden at Pa 
 ris, is depofited another fine fpecimen of this 
 mercurial ore, which was found cryftallifed in 
 the mine called Carolina at Muchel-lanfberg in 
 T the 
 
 Mercury, divided by means of a rapid and continu 
 al motion, as that of a mill-wheel, gradually change* 
 itfelf into a very fine black powder, which is called 
 athiops per fe, on account of its colour, in order to di 
 ftinguifli it from this athiofs mineml'u mentioned in the 
 text. 
 
[ 208 ] 
 
 the duchy of Deux Fonts. M. de Plfle fpeaks 
 alfo very politively of a fpecimen of native 
 gold from Hungary, which feems to be a na 
 tural amalgam of gold and mercury. It is 
 compofed of quadrangular prifms, of a grey- 
 idi yellow colour, and of a brittle texture. 
 This fpecimen is alfo in the king's cabinet at 
 the royal garden at Paris. 
 
 Mr Kirwan, fpeaking of the method of examin 
 ing the purity of gold by the moid way, fup- 
 pofes, with Sir Torbern Bergman, that there 
 are natural amalgamations cf mercury with 
 gold and filver : and Neumann obferves, that 
 ibmetimes a mineral, containing gold or fil- 
 ver, is met with among mercurial ores, al 
 though this is a ejreat rarity. 
 
 It is evident, therefore, that there naturally ex- 
 ifl various ores of quickfilver, amalgamated 
 with filver, gold, and other minerals, although 
 they be butfeldom met with. 
 C. Mineralifed, 
 
 [i.] Withfulphur. 
 
 A. Pure cinnabar, Ctnnataris nattva. 
 
 a. Loofe or friable cinnabar like red ochre. 
 I. Indurated or folid cinnabar. It is of a 
 
 deep red colour ; and, with refpecl to its 
 
 texture, is either, 
 
 1. Steel-grained; 
 
 2. Radiated ; 
 
 3. Compofed of fmall cubes, or fcaly ; or 
 
 4. Cryftallifed, in a cubical form ; it is 
 tranfparent, and deep red like a ruby. 
 
 B. Impure cinnabars. 
 
 (i.) A mercurial ore is found in Idria, 
 fays Gellert, where the mercury lies in an 
 earth or (lone, as if it were in a dead form ; 
 and has the appearance of a red-brown iron- 
 flone ; but it is much heavier than that. It 
 
 contains 
 
C 
 
 contains from three quarters to feven eighths 
 of the pureft mercury ; leaves, after diftilla- 
 tion, a very black ftrong earth behind ; and 
 gives fome marks of cinnabar. 
 
 2.) Liver ore, which is moft common in 
 Idria, and has its name from its colour.- 
 Outwardly it refembles an indurated iron- 
 clay ; but its weight difcovers that its con 
 tents are metallic. It yields fornetimes 80 
 pounds of quickfilver per hundred weight. 
 
 3. Burning ore; brand-trz in German. 
 This ore may be lighted at the candle ; and 
 yields from nine to 50 pounds of quicklilver 
 per hundred weight. Brunnlcb. 
 [[2.3 With iron by fulphur. Pyritous cinnabar. 
 Sir Torbern Bergman "mferted this ore in the 
 1 77th fe&ion of his Sciagraph ia t and feems doubt 
 ful whether this be a diftincl fpecies from the 
 cinnabar ; as the iron is perhaps, fays he, on 
 ly mechanically diffufed therein. Mr Mongcz 
 remarks, that there are but a few inftances of 
 cinnabar in which iron is not found in its cal 
 cined form ; though, in the act of the ore be 
 ing reduced, it paifes to its metallic ftate, and 
 becomes capable of being acted en by theload- 
 llone. 
 
 Another pyritotis ore of cinnabar was found 
 at Menidot, near St Lo in Lower Normandy. 
 It confided in grains of different fizes, of a 
 red brown colour: they had a vitriolic tafte 
 and fulphureous fmell. Found alfo at Al- 
 maden in Spain, and at Stahlberg in the Pa 
 latinate , though at this laft place they are of 
 a dodecaedral form. 
 
 3-] With filver by the aerial acid, and ful 
 phur. 
 
 This feems to be a native precipitate per /, 
 
 or calx of mercury. It is faid to have been 
 
 T 2 lately 
 
[ 210 ] 
 
 lately found in Idria, in hard compact mallei 
 of a brownifh-red colour ; fee Journal de Pky~ 
 Jtguefcr Jar nary 1784, p. 6l. If this account 
 can be relied upon, it will prove, that quick- 
 filver, even in a calciform itate is naturally 
 found mineralifed with filver by means of ful- 
 phur. 
 4.] With fulphur and copper. 
 
 This ore is blackifli grey, of a glaffy texture, 
 and brittle ; crackles and fplits exccflively in 
 the fife \ and when the quickfilver and fulphur 
 are evaporated, the copper is difcovered by its 
 common opaque red colour in the glafs t>f bo 
 rax, which, when farther forced in the fire, 
 or dilutedj becomes green and tranfparenf. It 
 is found at Mufchlanfberg in the duchy of 
 Deux Fonts. 
 
 [5.] Mincralt&d by the nwine and vitriolic 
 acids. 
 
 Mineralogy owes the difcovery of this ore to 
 Mr Woulfe, who publifhed an account of it 
 in the Philofophical Tranfaftions for 1776. 
 It was found in the duchy of Deux Fonts, at 
 the mine diftinguifhed by the name of Obertnof- 
 chal It had a fpar-like appearance. This ore 
 is either bright and white, or yellow or black. 
 It was mixed with cinnabar in a {tony matrix ; 
 and being well mixed with one-third of its 
 weight of vegetable alkali, afforded cubic and 
 oclagonal cryilals ; that is, fait of Sylvius and 
 vitriolated tartar. 
 
 The marine fait of this mercury is in the 
 (late of fublimate corrofive. 
 
 Order II. IMPERFECT or BASE METALS. 
 
 Tin. Stannum ; Jupiter. (See the detached article 
 TIN: Alfo CHEMISTRY-//^*; and METALLURGY, 
 Part II. fetf. vi, and Part IIL-fed. vi.) 
 
 This 
 
C 213 ] 
 
 2. In the form of cryftalline metallic laminse, or 
 laminated cryftals, rifmg fide by fide out of an 
 edging, which fhone like melted tin : they 
 were almoft as thin 'as flakes or fcales of talc, 
 interfering each other in various directions, 
 with fome cavities between them, within which 
 appeared many fpecks and granules of tin, that 
 could be eafily cut with a knife : this was alfo 
 found in Cornwall. 
 
 3. In a mafTy form, more than one inch thick 
 in fome places, and inclofed in a kind of quart- 
 zous ftone ; or rather in an hard cruft of cry- 
 ftallifed arfenic. 
 
 (2.) Calciform Ores of Tin. 
 
 A. In form of a calx, Stanntim cakiforme. 
 A. Indurated, or vitrified. 
 
 i. Mixed with a fmall portion of the calx of 
 arfenic. 
 
 a. Solid tin ore, without any determinate 
 figure. Tin-ftone. 
 
 It refembles a garnet of a blackifh 
 brown colour, but is much heavier ; and 
 has been confidered at the E-nglifti tin- 
 mines as a ftone containing no metal, 
 until fome years ago it began to be 
 fmelted to great advantage. 
 j. Cryftallifed. 
 
 a. Tin fpar, or white tin ore. This is ge 
 nerally of a whitifti or grey colour ; forne- 
 times it is yellowifh, femi-tranfparent, 
 and cfyftullifed, either of a pyramidical 
 form, or irregularly. 
 
 I. Tin-grains. This ore, like the garnets, 
 is of a fpherical polygonal figure; but 
 feems more unctuous on its furface. 
 
 1. In large grains. 
 
 2. In fmall grains, 
 j?. Mixed with metals. 
 
 I. With 
 
C 
 
 1. With the calx of iron, as in the garnet. 
 
 2. With manganefe. See the Semimetals, 
 C. Mineralifed. l 
 
 1. With fulphur and iron. 
 
 2. With fulphur. Aurum mufivum. 
 
 This was difcovered by ProfefTor Berg 
 man, among fome minerals which he recei 
 ved from Siberia. He obferved two forts 
 of it, analogous to the two artificial combi 
 nations of tin with fulphur. 
 
 1. One nearly of the colour of zinc, and 
 of a fibrous texture, which contained 
 about 20 per cent, of fulphur, and the 
 remainder tin. 
 
 2. The other enveloped the former like a 
 cruft ; refembled aurum mufivum ; and 
 contained about 4.0 per cent, of fulphur, a 
 fmall proportion of copper, and the re 
 mainder tin. Mem.StockLfor 1 7 2 1 ,p. 3 2 8. 
 
 At Huel Rock, in St Agnes in 
 Cornwall, there has been found a me 
 tallic vein, nine feet wide, at 20 yards 
 beaeath the furface. Mr Rafpe was 
 the firft who difcovered this to be a 
 fulphurated tin-ore : it is very com 
 pact, of a bluilh white colour, ap 
 proaching to grey fteel, and fimilar to 
 the colour of grey copper ore: it is 
 lamellar in its texture, and very brittle. 
 It confifts of fulphur, tin, copper, and 
 fome iron. Mr Rafpe propofes to cail 
 it bell-metal ore. 
 
 According to Mr Klaproth's ana- 
 lyfis of this ore, 119 grains contain 30 
 of pure fulphur ; 41 of tin ; 43 of cop 
 per ; two of iron ; and three grains of 
 the Ilony matrix. In another fpeci- 
 men. of the fame fulphurated tin-ore 
 
 iroin 
 
This is diftinguiihed from the other metals by the 
 
 following characters and qualities, It is, 
 
 a. Of a white colour, which verges more to the 
 
 blue than that of filver. 
 1. It is the rncft fufible of all metals ; and, 
 c . The leaft ductile ; that is, it cannot be ex 
 tended or hammered out fo much as the 
 others (x). 
 
 d. In breaking or bending, it makes a crack-*- 
 ling noife. 
 
 e. It has a fmell particular to itfelf, and which 
 cannot be defcribed. 
 
 f. In the fire it is eafily calcined to white afhes, 
 which are 25 per cent, heavier than the me 
 tal itfelf. During this operation, the phlo- 
 gifton is feen to burn off in form of fmall 
 fparkles among the aihes or calx. 
 
 (x) Tin is fufficiemly ductile to be beaten into very 
 thin leaves. But ductility and extenfibility are two dif 
 ferent properties, lefs connected with one another than 
 is generally imagined. Iron and fteel are drawn into 
 exquifite fine wire, but cannot be beat into very thin 
 leaves. Tin, on the other hand, is beat into fine leaves, 
 and may be extended between rollers to a confiderable 
 furface. The tin-fheet ufed in various arts, is com* 
 monly about 7 ^ ff th part of an inch ; but may be ex 
 tended twice as much in its dimenfions without diffi 
 culty. Notwithftanding this extenfibility, tin cannot be 
 drawn into wire, on account of the weak cohefion of 
 its particles. A tin wire, however, of one-tenth of 
 an inch diameter, is able to fupport a weight of 49^ 
 pounds, according to Fourcroy. Gold and filver poflefs 
 both properties of ductility and extenfibility the moft 
 eminently of all metallic bodies ; whilfl lead, notwith- 
 ftanding its flexibility and foftnefs, cannot be made eU. 
 tUerlnto leaves or wire f any finenefs* 
 
 T 3 S> Thfe 
 
j. This calx is very refraclory ; but may, how 
 ever, with a very ftrong degree of heat be 
 brought to a glafs of the colour of colophony. 
 But this calx is eafily mixed in glafs com- 
 pofitions, and makes with them the white 
 enamel. 
 
 h. It unites with all metals and femimetals ; 
 but renders moft of them very brittle, except 
 lead, bifmuth, and zinc. 
 i. It amalgamates eafily with quickfilver. 
 k. It diffolves in aqua-regia, the fpirit of fea- 
 falt, and the vitriolic acid ; but is only cor 
 roded into a white powder by the fpirit of 
 nitre. The vegetable acid, foaps, and pure 
 alkaline falts, alfo corrode this metal by de 
 grees. 
 /. Its fpecific gravity to water is as 7400 to 
 
 icoo, or as 7321 to 1000. 
 m. Diffolved in aqua-regia, which for this pur- 
 pofe ought to confift of equal parts of the 
 fpirit of nitre and fea-falt, it heightens the 
 colour of the cochineal, and makes it deeper j 
 for otherwife that dye would be violet. 
 (i.) Native Tin. 
 
 The exiftence of native tin has long been 
 queliioned : but it has undoubtedly been found 
 feme years ago in Cornwall, as Mr Kirwan 
 remarks. 
 
 3 . Malleable tin, in a granular form, and alfo in 
 , a foliaceous fhape, ifluing out of a white hard 
 matter like quartz : but which, after being 
 properly aflfayed, proved to be arlenical cry- 
 Jlals ; a circumftance that evinces its being na 
 tive tin, fince the arfenic could not remain 
 in this form if the tin had been melted. It 
 appeared like a thick, jagged, or fcolloped 
 lace or edging j and was found near St Auftle 
 in Cornwall, 
 
 2. In 
 
r *$ 3 
 
 from Cornwall, there were in the hun 
 dred 25 parts of fulphur, 34 of tin, 36 
 of copper, three of iron, and two of 
 the ftony matrix. 
 
 II. Lead ; Plumlum> Saiurntu. (See the article LEAD, 
 and CHEMISTRY-/^/C .- Aifo METALLURGY, 
 Part II. fed. v. and Part III. fed*, vii.) 
 The properties of lead are as follows. 
 
 a. It is of a blui'h white colour when freih broke, 
 
 but foon dulls or follies in the air. 
 I. It is very heavy j viz. to water as 11,325 to 
 
 1COO. 
 
 t* It is the fofteft metal next to gold ; but it 
 has no great tenacity, and is not in the leaft 
 fonorous, 
 
 d< It is eafily calcined j and by a certain art in 
 managing the degrees of the fire, its eal% be 
 comes white, yellow, and red. 
 
 t. This calx melts eafier than any other metallic 
 calx to a glafs, which becomes of a yellow co 
 lour, and femitranfparent. This glafs brings 
 other bodies, and the imperfect metals, into 
 fufion with it. 
 
 /. It diflblves, ift, In the fpirit of nitre ; 2dly, 
 In a diluted oil of vitriol, by way of digeftion ; 
 3dly, In the vegetable acid ; 4thly, In alkaline 
 folutions ; and 5thly, In exprefied oils, both 
 
 - in the form of metal and of calx. 
 
 g. It gives a fweet tafte ; to all folutions. 
 
 /j. It amalgamates with quickfilver. 
 
 i. With the fpirit of fea-falt it has the fame ef 
 fect as filver, whereby is produced a faturnus 
 corneuj. 
 
 k. It does not unite with iron, when it is alone 
 added to it in the fire. 
 
 /. It works on the cupel, which fignifies that its 
 glafs enters into certain porous bodies, defti- 
 tute ofphlogifton and alkaline falts. 
 
 m. It 
 
t 216 ] 
 
 m. It melts in the fire before it is made red-hot, 
 
 almoft as eafilyas the tin. 
 n. Its calx or glafs may be reduced to its metallic 
 
 ftr,te by p< t-afhes. 
 i,] Native Lead. 
 
 For proofs of lead being naturally found in 
 its metallic ftate, fee the article LEAD.- It may 
 be here added, that Henckel likewife affirms its 
 exiftence, in his Flora Saturnifans ; (fee Kinvan's 
 Elements of Mineralogy, p. 297, 298.) Walle- 
 rius aflerts, that it has been fo found in Poland, 
 a fpecimen of which war, kept in the collection of 
 Richter ; and adds, that a fimiiar one fr-und at 
 Schneberg, was ft en in the collection of Spener. 
 (Mineralogy, vol. ii. p. 301.) 
 
 Dr Lawfon, in his Englifh edition of Cra 
 mer's Art of Eifaying Metals, fays, that fume 
 pure native malleable lead had been lately found 
 in New England; (p. 147.) And kftly, Pro- 
 feffor Bergrran did not hefitate to infert, by it 
 felf alone, the plumbum naiwum, in Seel. 180. of 
 his Sciagraphies. 
 2*~\ Calciform Lead. 
 Lead is found, 
 ^. In the furm of a calz. 
 
 A. Pure. 
 
 a. Friable lead ochre, native cerufe. 
 
 b. Indurated lead fpar, or fpatofe lead ore. 
 i. Radiated, or fibrous. 
 
 i. White, from Mendip-hills, in Eng 
 land, 
 ii. Cryftallifed in a prifmatic figure, 
 
 1. White, from Norrgrufva in Weft- 
 manland, 
 
 2. Yellowifh green, from Zchopau in 
 Saxony. 
 
 B. Mixed. 
 
 i. White 
 
1. With the calx of arfenic, arfenical lead 
 fpar. 
 
 2. Indurated* 
 
 a. White. Mr Cronftedt has tried fuch 
 an ore from an unknown place in Ger 
 many, and found tiiat no metallic A ead 
 could be melted from it by means of 
 the blc'.v-pip?, as can be done out of 
 other lead ipurs ; but it muft be per 
 formed in a crucible. (See the article 
 LEAD, par. ili.) 
 
 3. With a calcareous earth. 
 
 This ore efferveices with aqua-fortis, and 
 contains 40 per cent, of lead : on which 
 account it is placed here rather than 
 among the calcareous earths. 
 B. Mineralifed. 
 
 1. With fulphur alone : the bley-fck { witff t or bley 
 gfanz, of the Germans. 
 
 a. Steel-grained lead ore. 
 
 b. Radiated, or antimoniated lead ore. 
 f. TefTellated, or potter's lead-ore. 
 
 At Villach in Auftria there is faid to be 
 found a potter's lead-ore, which contains not 
 the leafl portion of filver. 
 
 2. Mineralifed by the vitriolic acid^ 
 
 This ore was difcovered by Mr Monnet. 
 It occurs fometimes, though rarely, in the 
 form of a white ponderous calx ; and feems 
 to originate from the fpontaneous decompoii- 
 tion of t)ie fulphurated lead-ores abovemen- 
 tioned. 
 
 3. By tie acid of phofphorus. 
 
 This ore was lately difcovered by Ghan ; 
 and is of a greeniih colour, by reafon of a 
 mixture of iron. See the article LEAD, 
 par. 6. 
 
 4. With fulphurated filver. Galena ; alfo called 
 
 bkyglatm 
 
C ."8 ] 
 
 lleyglany, by the Germans. Potter's ore. 
 
 a. Steel-grained. 
 
 b. With fm all fcales. 
 . Fine-grained. 
 
 d. Of a fine cubical texture ; and, 
 
 e. Of coarfe cubes. Thele two varieties are 
 found in all the Swedilh filver-mines. 
 
 / Cryftallifed. 
 
 The fteel-grained and fcaly ores are of a 
 dim and dull appearance when they are 
 broken, and their particles have no deter 
 mined angular figure : they are therefore in 
 Swedifti commonly called blyfchwiif ; in op- 
 pofition to the cubical ores, which are call 
 ed blyglan-z. The moft part of the ores call- 
 ed blyglanz contain filver, even to 24 ounces 
 $er cent, of which we have inftances in the 
 mines of Salberg, where it has been obfer- 
 ved, that the coarfe cubical lead ores are ge 
 nerally the rich eft in filver, contrary to 
 what is commonly taught in books; the 
 reafon of which may perhaps be, that, in 
 making the eflays on thofe two ores, the 
 coarfe cubical can be chofen purer or 
 freer from the rock than the fine cubical 
 ores. 
 
 5. With fulphurated iron and filver. This is 
 found, 
 
 a. Fine-grained, b. Fine cubical, c. Coarfe- 
 cubical.. When this ore is fcorified, it yields 
 a black flag ; whereas the preceding lead* 
 ores yield a yellow one, becaufe they do not 
 contain any iron. 
 
 6. With fulphurated antimony and filver ; anti- 
 moniated or radiated lead-ore. This has the 
 colour of a bleyglanz, but is of a radiated tex 
 ture. 
 
 It is found, 
 
[ 9 ] 
 
 a. Of fine rays and fibres; and, . 
 
 b. Of coarfe rays or fibres. The lead in this 
 ore prevents any ufe being made of the anti- 
 many to advantage ; and the antimony like- 
 wife in a great meafure binders the extrac 
 ting of the filver. 
 
 ^. Mineralifed by arfenic 
 
 This ore was lately difcovered in Siberia 
 Externally it is of a pale, and internally of 
 a deep red colour. See the article LEAD, 
 par. 10. 
 
 C. Mixed with earth ; ftony, or fandy lead ores. 
 Thefe confill cither of the calcifbrm or of the 
 galena kind, intimately mixed and diffufed 
 through ftones and earth, chiefly of the calca 
 reous or of the barytic genus. See LEAD^ 
 par. 1 1 . 
 
 Ufssy &c. of Lead. See LEAD, and the other 
 articles above referred to. 
 
 III. Copper; Cuprum, Venus, JEs. (See the article 
 COPPER: Alfo CHEMISTRY-/;?^.* ; and METAL 
 LURGY, Part II. fea. iv. and Part III. fed. 
 iv.) 
 This metal is, 
 
 a. Of a red colour. 
 
 b. It is pretty foft and tough. 
 
 c. The calx of copper being diflblved by acids 
 becomes green, and by alkalies blue. 
 
 </. It is eafily calcined in the fire into a blackifh 
 blue fubftance, which, when rubbed to a fine 
 powder, is red ; when mdted together with 
 glafs, it tinges it firft reddifh brown, and af- 
 terw.irds of a tranfparent green or fea-green co 
 lour. 
 
 *.. It didblves in all the acids, and likewife in al 
 kaline folntions. It is eafier diffolved when in 
 f^rm of a c dx than in a metallic ft ate, efpeci- 
 U ally 
 
[ 220 ] 
 
 ally by the acids of vitriol and fea-falt, and the 
 vegetable acid. 
 
 f. Vitriol of copper is of a deep blue colour; but 
 the vegetable acid produces with the ccpper a 
 green fait, which is verdigris. 
 
 g. It can be precipitated out of the folutions in a 
 metallic (late ; and this is the origin of the pre 
 cipitated copper of the mines called Ziment 
 copper. 
 
 h. It is not eafi-ly amalgamated with quickfilver ; 
 but requires for this purpofe a very ftrong tri- 
 turation, or the admixture of the acid of nitre. 
 
 . It becomes yellow when mixed with zinc, which 
 has a ftrong attraction to it, and makes brafs, 
 pinchbeck, c. 
 
 I. When the metal is expofed to the fire, it gives 
 n. green colour to the flame in the moment it 
 begins to melt, and continues to do fo after 
 wards, without lofing any thing confiderable 
 of its weight. 
 1.3 Native copper. 
 
 Copper found naturally in a metallic ftate, is 
 called virgin or native copper. It is met with, 
 
 1. Solid. 
 
 2. Friable, in form of fmall, and fomewhat co 
 herent grains. Precipitated or ziment copper. 
 
 2.] Calciform. 
 
 Copper, in form of a calx, is found, 
 j.) Pure. 
 
 A. Loofe or friable ; Ocbra veneris. 
 
 1 . Blue ; Cceruleum montanum. Very feldom 
 found perfectly free from a calcareous fub- 1 
 ftance. 
 
 2. Gre'zn ; Viride monlanum. Both this and 
 the former colour depend on menftrua, 
 which often, are edulcorated or wafbed 
 away. 
 
 3. Red. 
 
[ 221 ] 
 
 3. Red. This is an efflorefcence of the glafs 
 
 copper ore. 
 B. Indurated. Glafs copper-ore. 
 
 a. Red. This is fometimes as red as feal 
 ing wax, and fometimes of a more liver- 
 brown colour. 
 
 It is always found along with native 
 copper, and feems to have loll its phlo- 
 giilon by way of efflorefcence, and to be 
 changed into this form. It is likewife 
 found with the iulphurated copper, impro 
 perly called glafs c of per ere. 
 2.) Mixed. 
 
 A. Loofe or friable ; Oc/ira vener is friab'ilis im- 
 pura. 
 
 1. Mixed with a calcareous fubilance,; Cce- 
 rukum montanum. In this (late copper-blue 
 is moftly found. It ferments during, the 
 folution in aquafortis. 
 
 2. Mixed with iron. Black. It is the de- 
 compoiition of the Fahlun copper ore. 
 
 B. Indurated. 
 
 1. Mixed with gypfum, orplafler. Gree?. 
 
 2. Mixed with quartz, a. Red, from Sun- 
 nerfkog in the province cf Smoland. 
 
 3. Mixed with lime. a. Blue. This is the 
 JLapis Armenia j according to the accounts 
 given of it by authors. 
 
 3.) Cupreous (lones. 
 
 Analogous to the calciform copper ores, are, 
 
 1. The lapis ar/nenus. 1 See the detached ar- 
 
 2. The turquoife. J tide COPPER, n 7. 
 
 3.] Diifolved and mineraiifedj Cuprum 
 fat urn. 
 
 A. With fulphur alone. Grey copper-ore ; alfo 
 called, improperly, g'afs copper-ore. 
 a. Solid, without any certain texture, and very 
 foft, fo that it can be cut with a knife almoft 
 as eafily as black lead. 
 
 U 2 b. Fine 
 
222 
 
 t. Fine cubical. In Smoland this 1 is fome- 
 times found dccompofcd or weathered, and 
 changed into a deep mountain blue. 
 . With fulphurated iron. Minera cupri pyntacea / 
 yellow copper ore. Marcafitical copper ore ; 
 Pyrites cupri. This is various both in regard to 
 fcolour and in regard to the different propor 
 tion of each of the contained metals ; for in- 
 ftance, 
 
 a. Blackifh grey, inclining a little to yellow ; 
 Pyrites cupri grifeus. When decayed or 
 weathered, it is of a black colour ; is the 
 richeft of all the varieties of this kind of 
 copper ore, yielding between 50 and 60 
 per cent, and is found in Spain and Ger 
 many. 
 
 I. Reddifh yellow, or liver brown, with a blue 
 coat on the furface ; Minera cupri lazurea, 
 This ore yields between 40 and 5^0 per cent. 
 of copper, and is commonly faidto be blue, 
 though it is as ed, when frefli broken, as a 
 red copper regulus. 
 
 t. Yellowifh green ; Pyrites cupri flavo -viridefcens. 
 This is the moft common in the north part of 
 Europe : and is, in regard to its texture, 
 found, 
 r. Solid, and of a mining texture. 
 
 2. Steel grained, of a dim texture. 
 
 3. Coarfe-grained, of an uneven and finning 
 texture. 
 
 4. Cryftallifed marcafitical copper ore, 
 a. Of long octoedrtcal cryftals. 
 
 d. Pale yellow. This cannot be defcribed but 
 as a marcafite, though an experienced eye 
 will eafily difcover fome difference between 
 them. It yields 22 per cent, of copper. 
 
 e. Liver-coloured. 
 
 c. With fulphurated filver, arfenic, a<nd fome iron, 
 Fallow copper-or&j which contains only a few 
 
 ounces 
 
ounces of filver. *This ore is found iri Hunga 
 ry and Germany, where it is called black topper 
 ore, 
 
 D. With fulphurated arfenic andiron. 'White cop 
 per ore. 
 
 E. Pyritous copper, -with arfenic and zinc. 
 
 According to Mr Monnet, this ore is found 
 at Catliarineberg in Bohemia. It is of a brown 
 colour ; of a hard, folid, compact, granular 
 texture ; and contains from 1 8 to 30 per cent. 
 of copper. 
 
 F. DifTolved by the vitriolic acid ; Witriolum *os- 
 neris. See the article copper, n x r iii. 
 
 c. With phlogifton. Copper coal ore, confiding 
 of the calces of copper, mixed with a bitumi 
 nous earth. 
 
 H, Mineralifed by the muriatic acid. This ore 
 was found in Saxony, and had been generally 
 rniftaken for a micaceous fubftance, which in 
 fact it greatly refembles. It has not yet been 
 found in large maffes, but only in a fupeificial 
 form, like a cruft over other ores. It is mo- 
 derately hard and friable ; of a fine green co 
 lour, and fometimes of a bluiih green, cry- 
 ftallifed in a cubic form, or with a foliated 
 texture, or in little fcales refembling green 
 mica or talc. This ore is eanly diilblved by 
 nitrous acid : the folution takes a green colour ; 
 arid the metal may be precipitated en a po- 
 IHhed plate of iron. If fome drops of a ni 
 trous lolution of filver be mixed with it, a 
 white powder of hna cornea will bs precipita 
 ted, which difcovers the- prefence of the muria 
 tic acid in this ore. 
 
 The ufes of copper are very numerous, although 
 
 not thoroughly known to every one. Several of 
 
 thefe have been mentioned under the detached 
 
 U 5 article, 
 
[ "4 J 
 
 article, and in CHEMISTRY. Others of great im 
 portance may be here added. Its great ducYilky, 
 lightnefs, ftrength, and durability, render it of very 
 extenfive utility. Blocks, or bars of copper, are 
 reduced into flat fheets of any thicknefs, by being 
 firft heated by the reverberation of the flame, in 
 a low vaulted furnace, properly confliructed for 
 the purpofe ; and then immediately applied be 
 tween large rollers of fteel, or rather of cafe-har 
 dened iron, turned by a water-wheel or by the 
 frrength of hcrfes, fo that the hot metal is there 
 quickly fqueezed ; and the operation is repeated, 
 bringing the rollers every time nearer to one an 
 other, till the metallic iheet acquires the intended 
 thicknefs. 
 
 Thefe copper fheetS are very advantageoufly em 
 ployed in fneathing the bottoms of men of war 
 and other veiTels, which by this means are pre 
 vented from being attacked by the fea worms, 
 and are kept clean from various marine concre 
 tions, fo as to fail with confiderably greater fwift- 
 nefs. Copper iheets are alfo employed to cover 
 the tops of buildings iiul^ad of flates or earthen 
 tiles, as is ufed in Sweden ; and fome architects 
 have begun to introduce the life of copper cover 
 ing into Great Britain, which is much lighter, 
 and may be ufed with great advantage, although 
 it inuft be much dearer in prime cod. 
 
 Sundry preparations of copper are employed in 
 painting, Raining, and for colouring glafs and 
 enamels. See GLASS and ENAMEL. ' 
 
 The folution of copper in aqua-fortis ftains marble 
 and other ftones of a green coleur ; when preci 
 pitated with chalk or whiting, it yields the 
 green and the blue verditer of the painters, Ar- 
 cording to Lewis, a folution of the fame metal 
 in volatile fpirits ftains ivory and bones: when 
 macerated for fome time in the liquor, they be 
 come 
 
C 225 ] 
 
 come of a fine blvie colour, which, however, tar- 
 nifhes by expofure to the air, and becomes green 
 afterwards. 
 
 The fame author prepared elegant blue glafTes, by 
 melting common glafs, or powdered flint and fix 
 ed alkaline fait, with blue vitriol, and with an 
 amalgam of copper ; fine green ones were made 
 with green verditer, and with blue verditer, as 
 well as with the precipitate of copper made by 
 iixed alkalies, and with a precipitate by zinc ; and 
 a reddifb glafs was produced by the calx and fco- 
 ria of copper made by fire alone. Even in this 
 vitreous (late, it feems as if a continuance of fire 
 had the fame effect in rega'rd to colour, as air has 
 upon copper in other forms ; as fome of the moft 
 beautiful blue glafTes, by continued fufion, have 
 changed to a green colour. See farther the article 
 BRASS in the Glafs -trade. 
 
 Verdegris is a preparation of copper diflolved by 
 the vegetable acids, which act on this metal, dif- 
 folving it very {lowly, but in confiderable quanti 
 ties. It produces a fine green pigment for paint 
 ing both in oil and water colours, inclining more 
 or lefs to the bluidi according to circumilances. 
 
 So great is the tenacity of copper, that a wire of 
 a tenth of an inch in diameter is capable of Sup 
 porting 299.5 potfftds weight before it breaks. 
 Copper may be drawn into very fine wire, and 
 beaten into extremely thin plates. The German 
 artifts, chiefly thofe of Nurenberg and Aufburg, 
 are faid to poiTefs the beft method for giving to 
 thefe thin plates of copper a fine yellow colour 
 like that of gold. See the articles BRASS- Colour 
 and BzASS-Leaf. 
 
 The parings or fhreds of thefa very thin leaves of 
 yellow copper being well ground on a marble 
 plate, are reduced to a powder fimilar to gold, 
 which ferves to cover, by means of fome gum- 
 water, 
 
t 
 
 water, or othdr adhefive fluid, the furface of va 
 rious moulding or other pieces of curious Work- 
 manfhip, giving them the appearance of real 
 bronze, and even of fine gold 1 ; ^t a Very trifling 
 expence ; becaufe the gold colour of this metallic 
 powder may be eafily raifed and improved by 
 ftirring it on a wide earthen bafon over a flow 
 fire. 
 
 In fome of its ftates, copper is as difficulty ex 
 tended under the hammer as iron, but proves 
 fofter to the file, and never can be made hard 
 enough to ftrike afpark with flint or other ftones ; 
 from whence proceeds the ufe that is made of this 
 metal for chifels hammers, hoops, &c. in the 
 gun-powder works. 
 
 *lhe vitriolic acid does not aft on copper unlefs 
 concentrated and boiling : during this folution a 
 great quantity of fulphureous gas flies off; after 
 wards a brown thickifh matter is found, which 
 contains the calx of the metal partly combined 
 with the acid. By folution and filtration, a blue 
 folution is obtained, which being evaporated to a 
 -certain degree, produces after cooling long rhom- 
 iboidal cryftals of a beautiful blue colour, called 
 vitriol of copper ; but if this folution be merely 
 expofed a long time to the air, it affords cryftals, 
 and a green calx is precipitated, a colour which 
 all calces of this metal aflume when dried by the 
 air. Blue vitriol, however, is feldom formed by 
 diffolving the metal diredlly in the vitriolic acid. 
 That fold in the fliops is moflly obtained from 
 copper pyrites. It may alfo be made by ftratify- 
 ing copper-plates with fulphur, and cementing 
 them together for fome time ; becaufe the vitrio 
 lic acid of the fulphur being difengaged, attacks 
 and corrodes the metal, forming a metallic fait, 
 w'hich by affufion of water yields perfect cryftals 
 of blue vitriol. Se'e VITRIOL. 
 
 The 
 
I M.7. J 
 
 The nitrous acid, on the contrary, diflblves copper 
 when cold with great rapidity ; and a great quan 
 tity of fmoaking air or gas flies off, which, on 
 being received in a pneumatic apparatus, and 
 mixed in a glasfs tube with atmofphefic air, ftiows 
 its god or bad quality for the refpiration of li 
 ving animals, according as the common bulk is 
 more or lefs dirniniihed. This is one of the moft 
 important of Dr Prieftley's difcoveries ; and va 
 rious instruments known by the name of eudiome 
 ters have been fmee invented for making thefe ex 
 periments with eafe and fatisfatfion. See EUDIO 
 METER. 
 
 But the moft common ufe of copper is to make all 
 ibits of large ftills, boilers, pots, funnels, and 
 other veflels employed by diRillers, dyers, che- 
 rnifts, and various other manufacturers, who make 
 ufe of large quantities of hot liquors in their va 
 rious operations. 
 
 Although copper when pure is extremely valuable, 
 on account of its ductility, lightnefs, and ftrength, 
 it is, however, lefs ufeful on many occafions from 
 the difficulty of forming, large maifes of work, 
 as it is not an eafy matter to cad copper folid, fo 
 as to retain all its properties entire. For if the 
 heat be not fwfficiently great, the metal proves 
 deficient in toughnefs when cold ; and if the heat 
 be raifed too higfe, or continued for a le.ngth of 
 time, the copper blifters on the furface when caft 
 in the moulds : fo that the limits of itsfufion are 
 very contracted. And from thefe circumibnces 
 .pure copper is rendered lefs applicable :o feveral 
 purpofes. 
 
 We find, however, that the addition of a certain 
 proportion of zinc removes alrnoft all thefe incon 
 veniences, and furnifhes a mixed metalmore fu- 
 f'blethan copper, very ductile and tenacious when 
 cold ; which does- not fo readily fcorify in a mode-' 
 
 rate 
 
E "8 j 
 
 rate heat, and which is lefs apt to ruil from the 
 action of air and moifture. 
 
 Copper is the bafis of fundry compound metals 
 for a great number of mechanical aad ceconomi- 
 cal ufes of life, fuch as brafs (Y), prince's-metal, 
 
 (Y) Brafs is frequently made by cementing plates 
 of copper with calamine, where the copper imbibes 
 one-fourth or one-fifth its weight of the zinc which ri 
 tes from the calamine. The procefs confifts in mix 
 ing three parts of the calamine and two of copper with 
 charcoal dud in a crucible, which is expofed to a red 
 heat for fome hours, and then brought to fufion . The 
 vapours of the calamine penetrate the heated plates of 
 copper, and add thereby to its fufibility. It is of 
 great confluence for the fuccefs of this procefs to 
 have the copper cut into irnall pieces, and intimately 
 blended with the calamine. See CHEMISTRY, n 1 151,. 
 
 In moft foreign founderies the copper is broken frnall 
 by mechanical means with a great deal of labour ; bu-t 
 at Briftol the workmen employ an eafier method. A 
 pit is dug in the ground of the manufactory about four 
 feet deep, the fides of which are lined with wood. The 
 bottom is made of copper or brafs, and is moveable by 
 means of a chain. The top is made alfo of braf? with a 
 fpace near the centre, perforated with fmall holes, which 
 are luted with clay; through them the melted copper is 
 poured, which runs in a number of ftreams into the wa 
 ter, and this is perpetually renewed by a freih dream 
 that pafles through the pit. As the copper falls dowry 
 it forms itfelf into grains, which collect at the bot 
 tom. But great precaution is required to hinder the 
 dangerous explofions wbich melted copper produces 
 when thrown into cold water ; which end is obtained by 
 pouring fmall quantities of the metal at once. The 
 granulated copper is completely mixed with powder 
 ed calamine, and fufed afterwards. The procefs lafts 
 
 eight 
 
C 
 
 tombac, bell-metal, white copper, &c. See CHE 
 MISTRY, n 1154, &c. 
 
 If the mixture is made of four to fix parts of cop 
 per, with one part of zinc, it is called Prince' s-me- 
 tal. If more of the copper is taken, the mixture 
 
 eight or ten hours, and even fome days, according to 
 the quality of the calamine. 
 
 It is a wonderful thing, fays Cramer, that zinc it- 
 felf, being fimply melted with copper, robs it of all 
 its malleability ; but if it be applied in form of vapour 
 from the calamine, the fublimates, or the flowers, it 
 does not caufe the metal to become brittle. 
 
 The method mentioned by Cramer to make brafs 
 from copper, by the volatile emanations of zinc, feems 
 to be preferable to any other procefs, as the metal is 
 then preferved from the heterogeneous parts contain 
 ed in the zinc itfelf, or in its ore. It confifts in mixing 
 the calamine and charcoal with moiftened clay, and 
 ramming the mixture to the bottom of the melting pot, 
 on which the copper, mixed alfo with charcoal, is to 
 be placed above the rammed matter. When the pro 
 per degree of heat is applied, the metallic vapour of 
 the zinc contained in the calamine will tranfpire 
 through the clay, and attach itfelf to the copper, lea 
 ving the iron and the lead which were in the calamine 
 retained in the clay, without mixing with the upper, 
 metal, Dr Watfon fays that a very good metallurgifl 
 of Briftol, named John Champion, has obtained a patent 
 for making brafs by combining zinc in the vapourous 
 form with heated copperplates ; and that the brafs from 
 this manufacture is reported to be of the fined kind ; but 
 he knows not whether the method there employed is 
 the fame with that mentioned by Cramer. 
 
 Brafs isfometimes made in another way, by mixing 
 the two metals diieclly ; but the heat requisite to melt 
 the copper makes the zinc burn and flame out, by which 
 
 the 
 
C 230 ] 
 
 wiU be of a deeper yellow, and then goes by the 
 name of tombac. 
 
 Bell-metal is a mixture of copper and tin, forming 
 a compound extremely hard and fonoiouvmd is 
 lefs fubject to alterations by expofure ti> the air 
 than any other cheap metal. On this account it 
 is advantageoufly employed in the fabrication of 
 various utenfils and articles, as cannons, bells, fta- 
 tues, &c. in the compofition of which, however, 
 other metals are mixed in various proportions, ac 
 cording to the fancy and expei ience of the artift. 
 
 White-copper is prepared with arfenic and nitre, as 
 mentioned under CHEMISTRY, n 1157. 
 
 But the principal kind of white-copper is that with 
 which fpeculums of reflecting telefcopes are made. 
 See the article SPECULUM. 
 
 VII. Iron ; Ferrum, faars. This metal is, 
 
 a. Ofablackifh blue fhining colour. 
 
 b. It becomes duclile by repeated heating be 
 tween coals and hammering. 
 
 f. It is attracted by the loadftone, which is an 
 iron ore ; and the metal itfelf may alfo be ren 
 dered magneticaL 
 
 d. Its 
 
 the copper is defrauded of the due proportion of zinc. 
 If the copper be melted feparately, and the melted zinc 
 poured into it, a confiderable and dangerous explofion 
 ettfues ; but if the zinc is only heated and plunged 
 into the copper, it is quickly imbibed and retained. 
 ^The union, however, of thefe two metals fucceeds better 
 if the flux compofed of inflammable fubftances be firft 
 fufed in the crucible, and the copper and zinc be poured 
 into it. As foon as they appear thoroughly melted, 
 they are to be well ftirred, and expedttioufly poured our, 
 or elfe the zinc will be inflamed, and leave the red cop 
 per behind. 2 
 
a. Its fpecific gravity to water is as 7,645, or 
 
 8000 : 1000. 
 e. It calcines eafily to a black fcaly calx, which, 
 
 when pounded, is of a deep red colour. 
 /. When this calx is melted in great quantity 
 with glafs compofitions, it gives a blackifti 
 brown colour to the glafs ; but in a fmall 
 quantity a greenifh colour, which at lafl va- 
 nifhes if forced by a ftrong degree of heat. 
 g It is diflblved by all falts, by water, and like- 
 wife by their vapour. The calx of iron is dif* 
 folved by the fpirit of fea-falt and by aqua- 
 regia. 
 
 1. The calx of the di/Tolved metal becomes yel 
 low, or yellowifh brown : and in a certain de 
 gree of heat it turns red. 
 
 i. The fame calx, when precipitated from acids 
 by means of the fixed alkali, is of a greenifh 
 colour ; but if becomes blue when precipitated 
 by means of an alkali united with phlogifton ; 
 in which laft circumftance the phlogifton unites 
 with the iron : thefe two precipitates lofe their 
 colour in the fire, and turn brown. 
 L The vitriol of iron is brown. 
 
 Iron is found, 
 
 i.j Native. See the detached article IRON. 
 l_2.~] Inform of calx. 
 A. Pure. 
 
 A. Loofe and friable. Martial ochre ; Miners. 
 ochracea. 
 
 i. Powdery; Qchra ferrl. This is commonly 
 yellow or red, and is iron which has been 
 diffolved by the vitriolic acid> 
 -2. Concreted. Bog-ore. 
 
 a. In form of round porous balls. 
 I. More folid bars. 
 
 c. In fmall flat pieces, like cakes or pieces 
 of money. 
 
 X d. In 
 
d. In fmail grains. 
 
 e. In lumps of an indeterminate figure. 
 All thefe are of a blackiih brown, or a light 
 
 brown colour. 
 
 , Indurated. The blood-ftone ; Hematites. 
 ( i . ) Of an iron colour ; Hematites azrulefcens : 
 This is of a bluifli grey colour"; it is not 
 attracted by the loadftone, yields a red 
 powder when rubbed, and is hard. 
 
 a. Solid, and of a dim appearance when 
 broken. 
 
 b. Cubical, and of a (liming appearance 
 when broken. 
 
 c. Fibrous, is the molt common torrjlen of 
 Sweden. 
 
 d. Scaly : the elfenram of the Germans. 
 
 1. Black. 
 
 2. Bluifli grey. When this is found 
 along with marcafite, it is not only 
 sittracled by the loadftone, but is of 
 itfelf really aloadPcone. 
 
 c. Cryftallifed. 
 
 1. In ocloedrical cryftals. 
 
 2. In polyedrical cryftals. 
 
 3. In a cellular form. 
 
 Thefe varieties are the moft common in 
 Sweden, and are very feldoin blended 
 with marcafite or any other heteroge 
 neous fubftance except their different 
 beds. It is remarkable, that when thefe 
 ores are fousd along -with marcafite, 
 thofe particles which have lain nearel 
 to the marcafite are attracted by the 
 loadftone, although thsy yield a red or 
 reddiOi Ijrown powder, like thofe which 
 are not attracted by the load-ftone : it 
 is like wife worth obfervation, that they 
 generally contain a little fulphur, if they 
 are imbedded in a limePtone rock. 
 
C 233 ] 
 
 (2.) Blackifii brown bloodftone ; Hematites 
 nigrefcens. Kidney ore. This yields a red 
 or brown powder when it is rubbed ; it 
 is very hard, and is attracted by the load- 
 ftone. 
 
 a. Solid, with a glafiy texture. 
 
 b. Radiated. 
 
 c. Cryftallifed. 
 
 1. In form of cones, from Siberia. 
 
 2. In form of concentric balls, with 
 a facetted furface. Thefe are very 
 common in Germany, but very 
 fcarce in Sweden. 
 
 (3.) Red blood done; Hamatltes Ruler. Red 
 kidney ore. 
 
 a. Solid, and dim in its text'.ire. 
 
 b. Scaly. The ilftnram cf the Germans. 
 This is commonly found along with the 
 iron-coloured iron g'immsr, and fmears 
 the hands. 
 
 tf. Crydallifed, in concenuie balls, \vitha 
 
 fiat or facetted furface. 
 (4.) yellow blood-done ; Htmatites Jtat>us. 
 
 a. Solid. 
 
 b. Fibrous. 
 
 The varieties of the colours in the blood-done 
 are the fame with thofe produced in the 
 calces of iron made by dry cr liquid men- 
 flrua and afterwards expofed to different 
 degrees of heat. 
 13. Mixed with heterogeneous fubftances. 
 
 A. With a calcareous earth. White fpathofe 
 iron ore. Thejlahljkifi of the Germans. 
 
 B. With a filicecus earth. The martial jafper 
 of Sinople. 
 
 c, With a garnet earth. Garnet and cockle 
 
 or fhirl. 
 D. With an argillaceous earth. The bole. 
 
 X 2 E. With 
 
C *34 J 
 
 E. With a micaceous earth. Mica. 
 
 F. With manganefe. 
 
 G. With an alkali and phlogifton. Blue mar 
 tial earth. Native Pruffian-like blue. 
 
 i. Loofe or powdery. 
 
 H. With an unknown earth, which hardens in, 
 water. Tarras ; Ccmentum. 
 
 1 . Loofe or granulated ; Terra Puzzolana. 
 This is of a reddifh brown colour, is rich 
 in iron, and is pretty fuiible. 
 
 2. Indurated ; Cementum induratum. This is 
 of a whitiih yellow colour, contains like- 
 \vife a great deal of iron, and has the fame 
 quality with the former to harden foon in 
 water when mixed with mortar. This 
 quality cannot be owing to the iron alone, 
 but rather to fome particular modification 
 of it occafioned by fome accidental caufes,, 
 bccaufe thefe varieties rarely happen at 
 any othor places except where volcanoes 
 huvs been, or are yet* in the neighbour 
 hood. 
 
 [3.] DiiTolved or mineralifed. 
 A. With fulphur alone. 
 
 A. Perfectly faturated ; Ferrum fulfhure faturct' 
 turn. Marcafite. 
 
 B. With very little fulphur. "Black. iron ore. 
 Iron ftone. 
 
 This is either attracted by the loadftone, 
 or is a loadftone itfelf attracting iron ; it re- 
 fembles iron, and yields a black powder when 
 rubbed. 
 
 i.) Magnetic iron ore. The loadftone, 
 Magnes. . 
 
 a. vSteel-grained, of a dim texture, from 
 Hogberget in the parifh of Gagncef 
 in Dalarne : it is found at that place 
 almoil to the day, and is of as great 
 
 ftrength 
 
C 235 3 
 
 ftrength as any natural loadilones wees 
 ever commonly found. 
 
 b. Fine grained, from Saxony. 
 
 c. Coarfe-grained, from Spetaligrufvan at 
 Norberg, and Kierrgruivan, both in the 
 province of Weftmanland. This lofes 
 very foon its magnet ical virtue. 
 
 d. With coarfe fc lies, found at Sandfwoer 
 in Norway. This yields a red powder 
 when rubbed. 
 
 2.) Refractory iron ore. This in ks crude 
 ftate is attracted by the Icadftone. 
 a. Giving a black powder when rubbed j 
 Trifura aira. Of this kind are, 
 
 1. Steel-grained. 
 
 2. Fiae grained. 
 
 3. Coarfe grained. 
 
 This kind is found in great quantities 
 in ail the Swedifh iron mines, and of this 
 moil part of the fnfible ores confift, be- 
 caufe it is commonly found in iuch 
 kinds of rocks as are very fulible : and 
 it is as feldom met with in quartz as 
 the hxmatites is met \vith in lime- 
 flone* 
 
 I. Rubbing into a red powder. Thefe are 
 real hcernatites, that are fo far modified 
 by fulphur or lime as to be attrafted 
 by the kadftone. 
 
 1. Steel-grained. 
 
 2. Fine-grained. Emery. This k im 
 ported from the Levant :. it is mned. 
 with mica, is ftrongly attracted by 
 the loadllone, and fmells of fulphur 
 when put to the fire. 
 
 3. Of large iliining cubes. 
 
 4. Coarfe, Scaly. The c'if.ngHmmer or 
 
 X 3 [4.] Mixed. 
 
C 23^ 3 
 
 [4-0 Mixed with various foifile fubftances. 
 
 1. With fulphur and clay ; Pyrites. 
 
 2. With arfenic ; called mlfptckel by the Germans, 
 and plate mundic in Cornwall. 
 
 3. With fulphurated arfenic. Arfenical pyrites. 
 
 4. With vitriolic acid. Martial vitriol. 
 
 5. With phlogifton. Martial coal ore. 
 
 6. With other fulphurated and arfenicated metals, 
 See thefe in their refpeclive arrangements. 
 
 Ufss and Properties of Iron. Iron is the mod com 
 mon metal in nature, and at the fame time the 
 rnoft ufeful in common life ; notwithstanding 
 which, its qualities are perhaps very little known. 
 
 Iron has a particular and very fenfible fmell when 
 ftrongly rubbed or heated ; and a ftyptic tafte, 
 which it communicates to the water in which it 
 is extinguifhed after ignition. Its tenacity, duc 
 tility, and malleability, are very great. It exceeds 
 every other metal in elafticity and hardnefs, when 
 properly tempered. An iron wire of one-tenth 
 of an inch thick is able to fupport 450 pounds 
 weight without breaking, as Wallerius afferts. 
 
 Iron drawn into wire as (lender as the fineft hairs. 
 It is more eafily malleable when ignited than 
 when cold ; whereas other metals, though ductile 
 when cold, become quite brittle by heat. 
 
 It grows red-hot fooner than other metals ; never- 
 thelefs it melts the moft difficultly of all, platina 
 and manganefe excepted. It does not tinge the 
 flame of burning matters into bluifh or greeniih 
 colours, Uke other imperfect metals, but brightens 
 and whitens it ; hence the filings of iron are ufed 
 in compofitions of fire-works, to produce what is 
 called <wbite-fire. 
 
 Iron, or rather fteel, expands the lead of all hard 
 metals by the action of heat; but brafs expands 
 the mod : and on this account thefe two metals 
 are employed in the conftru&ion of compound 
 
 pendulums 
 
[ 237 3 
 
 pendulums for the beft fort of regulating clocks 
 for aftronomical purpofes 
 
 Iron, in the act of fufion, inftead of continuing to 
 expand, like the other metals, (brinks, as Dr 
 Lewis obferves ; and thus becomes fo much more 
 denfe as to throw up fuch part as is unmeked 
 to the furface ; whilft pieces of gold, filver, cop 
 per, lead, and tin, put in the refpeclive metals in 
 fulion, fmk quickly to the bottom. But in its 
 return to a confident (late, inftead of fhrinking, 
 like other metals, it expands ; fenfibly rifing in the 
 veflel, and aflaminga convex furface, whilft the 
 others fubfide, and appear concave. This pro 
 perty of iron was firft taken notice of by Reamur, 
 and excellently fits it for receiving impreffions 
 from the moulds into which it is caft, being for 
 ced into their minuteft cavities. Even when, 
 poured thick into the mould, it takes, neverthe- 
 leis, a perfect impreffion ; and it is bferved, that 
 cad iron is fo me what larger than the dimenfions 
 of the mould, whilft caft figures of other metals 
 are generally fmaller. 
 
 The vitriolic acid diifolves iron readily, and forms 
 green vitriol. 
 
 This acid requires to be diluted with 304 times its 
 quantity of water, to enable it effectually to dif- 
 folveiron; and, during the diflblution; a ftrong 
 aerial fluid arifes, called inflammable air, which, on 
 being mixed with atm&ipheric air, takes fire at 
 the approach of the flame of a candle. A glafs 
 phial, of about two ounces meafure, with one 
 third of inflamHiable air, and the reft of common 
 air, produc.es a very loud report if opened in the 
 lame circumftance ; and if it be filled with two- 
 thirds of inflammable air, mixed with one of de- 
 phlogifticated air, the report will be as loud as 
 the explofion of a piftol with gunpowtler. 
 
 Dilute nitrous acid dilfblves iron j but ibis faline 
 
 combina- 
 
C 238 3 
 
 combination is incapable of cry ftallifing. Strong 
 nitrous acid corrodes and dephlogifticates a con- 
 fiderable quantity of iron, which falls to the bot 
 tom. 
 
 Marine acid likewife diflolves iron, and this foluli- 
 on is alfo incryftallifable. 
 
 The Pruffian acid precipitates iron from its foluti- 
 ons in tlie form of Pruffian blue. 
 
 f his metal is likewife fenfibly acted upon by alka 
 line and neutral liquors, and corroded even by 
 thofe which have no perceptible faline impregna 
 tion ; the oils themfelves, with which iron uten- 
 fils are ufually rubbed to prevent their rutting, 
 often promote this effect in fome meafure, unleis 
 the oils have been previoufly boiled with litharge 
 or calces of lead. 
 
 Galls, and other aftringent vegetables, precipitate 
 iron from its folutions, of a deep blue or puiple 
 colour, of fo intenfe a (hade as to appear black. 
 It is owing to this property of iron that the cora- 
 inon writing ink is made. The infufion of galls, 
 and alfo the Pruffian alkali, are tefts of the pre- 
 fence of iron by the colours they produce on any 
 fluid. Acids, however, diflblve the coloured pre 
 cipitates by the former; and hence it arifes that 
 the marine acid is fuccefsfully applied to take off 
 ink'fpots and iron ftains from white linens. Al 
 kalis, however, convert thefe iron precipitates in 
 to a brown ochre. 
 
 Iron rm a Crong affinity with fulphur. If a bar 
 of iron be ftrongly ignited, and a roll of brim- 
 ftone be applied to the heated end, it will com 
 bine with the iron, and form a fuiible rnaf?, which 
 will drop dowa. A'veflel of water ought to be 
 placed beneath for the purpofe of receiving and 
 extinguishing it, as the fumes would otherwife be 
 very inconvenient to the operator. 
 
 A mixture of iron-filings and fulphur in powder, 
 
 moiftened 
 
C 239 3 
 
 moiftened with water, and prefTed fo as to form 
 a pafte, will in a few hours fwell, become hot, 
 fame, and even burft into a flame, if the quan 
 tity is large. The refiduum furnifhes martial 
 vitriol. This procefs is fimilar to the decompofi- 
 tion of martial pyrites ; from which fome philo- 
 fophers account for hot fpring-waters and fubter- 
 raneous fires. The mixture of water in. this pafte 
 feems to be neceflary to enable the vitriolic acid of 
 the fulphur to act on the iron. 
 
 For other chemical properties of this metal, fee 
 CHEMISTRY-//;^*; ; for its electrical and mag 
 netic properties, fee ELECTRICITY and MAGNE 
 TISM. For a more particular account of its na 
 ture and ufes, and the methods of making and 
 manufacturing it, fee the articles IRON and 
 STEEL ; alfo METALLURGY, Part II. feet. vii. and 
 Part III. feel. v. 
 
 Order III. SEMIMETALS. 
 
 I t Bifmuth j tln-glafs. Vifmutum t Bifmutum, Marcq/ita 
 ofjicmalis* It is, 
 
 a. Of a whitifh yellow colour. 
 
 b. Of a laminated texture, foft under the ham- 
 mer, and neverthelefs very brittle. 
 
 c. It is very fufible ; calcines and fcorifies like 
 lead, if not rather eafier : and therefore it 
 works oa the cuppel. It is pretty volatile in 
 the fire. 
 
 t/. Its glafs or flag becomes yellowifh brown, and 
 has the quality of retaining foroe part of the 
 gold, if that metal Has been melted, calcined, 
 and vitrified with it. 
 
 e. It may be mixed with the other metals, ex 
 cept cobalt and zinc, making them white and 
 brittle. 
 
 /, It diiiblves in aqua-fortis, without imparting to 
 
 it 
 
C 2 4 II 
 
 it any colour ; but to the aqua-regia It gives 
 a red colour, and may be precipitated out of 
 both thefe folutions with pure water into a 
 whice powder, which is called Spanl/b white. 
 It is alfo precipitated by the acid of fea-falt ; 
 which laft unites with it, and makes the vifmu- 
 tnm corneum. 
 
 g. It amalgamates eafily with quickfilver. Other 
 metals are fo far attenuated by the bifmuth, 
 when mixed with it, as to be ftrained or forced 
 along with the quickfilver through {kins or 
 leather. 
 
 Bifmuth is found in the earth. 
 
 A. Native. This refembles a regulus of bifmutb, 
 but confifts of fmallerfcales or plates. 
 
 1. Superficial, or in crufts. 
 
 2. Solid, and compofed of finall cubes. 
 J5. In form of calx. 
 
 I. Powdery or friable \ Odn-a v/fmuti This fs- 
 of a whitiih yellow colour'; it is found in 
 form of an efHorefcence. 
 
 It has b?-;n cuftomary to give the name of 
 faivers of bfauth to the pale red calx of co 
 balt, but it is wrong; becaufe neither the. 
 calx of bid : ; h, nor its folutions, become 
 red, this being a quality belonging to the 
 cobalt. 
 
 C. Mineralifed bifmuth. This is, with refpedt to 
 colour and appearance, like the coarf; teflela- 
 ted potter's lead ore ; but it confifts of very 
 thin fquare plates or flakes, from which it re 
 ceives a radiated appearance when broken crofs- 
 wife. 
 
 1. Withfulphur. 
 
 a. With large plates or flakes. 
 I. With fine or fmall fcales. 
 
 2. With fulphuratsd iron. 
 
 a. Of 
 
r *4' i 
 
 a. Of coarfe wedge-like fcales. 
 
 This miueralifed bifmuth ore yields a fine 
 radiated regulus ; for which reafon it has been 
 ranked among the antimonial ores by thofe 
 who have not taken proper care to melt a pure 
 regulus ore deftitute oi' fulphur from it ; 
 while others, who make no difference between 
 regulus and pure metals, have {till more po- 
 iitively aflerted it to be only an antimonial 
 ore. 
 
 . With fulphur and arfenic. 
 a. Of a whitifh yellow or afti colour. It has 
 a (hilling appearance j and is compofed of 
 fmall fcales or plates, intermixed very fmall 
 yellow flakes : It is of a hard and folid tex 
 ture : Sometimes ftrikes fire with hard 
 fteel : Has a difagreeable fmell when rub 
 bed : Does not effervefce with aqua-fortis ; 
 but is partially diifolved by the fame acid 
 (z). 
 
 I. Grey, of a ftriated form ; found at Helfmg- 
 land in Sweden, and at Annaberg in Saxony. 
 c. With variegated colours of red, blue, and 
 yellow grey ; found at Schneeberg in Sax 
 ony. 
 
 J. With green fibres like an amianthus ; at Mif- 
 nia in Germany, and at Gillebeck in Nor 
 way. 
 
 e. With yellow red fhining particles, called 
 mines de bifmuth "Threes in French, at Geor- 
 genftadt in Get many, and at Annaberg in 
 Saxony. 
 
 /. The 
 
 (z) This folution, being diluted with water, becomes 
 a kind of fympathetic ii.-k ; as the words written r/ith 
 it on white paper, and dried, are not diftinguiflid by 
 by the eye ; but on being heated before the lire, 
 thrv aiTunic a ycllowifh colour. 
 
C *4* ] 
 
 f. The minera lifmuthi arenacea, mentioned by 
 Wallerius and Bomare, belongs alfo to the 
 fame kind of the arfenicated ores. 
 4. By vitriolic acid. This ore is called wifmuth 
 bluth by the Germans. It is faid to be of a yel- 
 lowifn, reddifh, or variegated colour ; and to 
 be found mixed with the calx of bifmuth, in- 
 crufting other ores. Kirwan, p. 334. 
 Ufa, &c. of Bifmuth. See the article BISMUTH. 
 Alfo CHEMISTRY-/W^JC / and METALLURGY, Part 
 II. fed. x. and Part III. fed. viii. 
 II. Zinc ; fpeltre. Zincum. 
 
 a. Its colour comes neareft to that oflead, but it 
 
 does not fo eafily tarnifh. 
 
 1. It Giows a texture when it is broken, as if it 
 were compounded of flat pyramids (A). 
 
 c. Its fpecific gravity to water is as 6,900 or 
 7000 to 1000. 
 
 d. It melts in the fire before it has acquired a 
 glowing heat ; but when it has gained that 
 degree of heat, it burns with a flame of a 
 changeable colour, between blue and yellow. 
 If in an open fire, the calx rifes in form of 
 foft white flowers j but if in a covered vefiel, 
 with the addition of feme inflammable, it is 
 di (tilled in a metallic form : in which opera 
 tion, however, part of it is fcmetimes found 
 vitrified. 
 
 (A) It cannot de reduced into powder under the 
 hammer like other femimetals. When it is wanted 
 very much divided, it muft be granulated, by pouring 
 it while fufcd into ccld water; or filed, which is very 
 tedious, as it fluffs and fills the teeth of the file. But 
 if heated the mod poflible without fufingit, Macquer 
 afferts, that it becomes ib brittle as to be pulverifcd in 
 a mortar. 
 
[ 243 ] 
 
 e. It unites with all the metals (a) except bif- 
 muth and nickel, and makes them volatile. 
 It is, however, not eafy to unite it with 
 iron without the addition offulphur. It has 
 the ftrongeft attraction to gold and copper, 
 and this laft metal acquires a yellow colour 
 by it ; which has occasioned many experi 
 ments to be made to produce new metallic 
 compofitions. 
 
 /. It is diilblved by all the acids : of thzfe the 
 vitriolic acid has the ftrongeft attraction to it ; 
 yet it does not diflblve it, if it is not previoufly 
 diluted with much water. 
 
 g. Quickfilver amalgamates eafierwidi zinc than 
 with copper ; by which means it is feparated 
 from competitions made with copper. 
 b. It ieems to become electrical by iriclicn. 
 Zinc is found, . 
 
 A. Native. 
 
 Zinc has been met with native, though rarely, 
 in the form of thin and flexible filaments, 
 of a grey colour, which were eafily iiiflarnc-d 
 when applied to a fire. And Bomare affirms 
 that he has feen many fm ill pieces of native 
 
 zinq 
 
 (B) It brightens the colour of iron almofl into a fil- 
 ver hue ; changes that of copper to a yellow or gold 
 colour, but greatly dcbafes the colour of gold and de- 
 ftroys its malleability. It improves the colour and luftre 
 of lead and tin, rendering them firmer, and confe- 
 quently fitter for fundry mechanic ufes. Lead will 
 bear an equal weight of zinc, without lofing too much 
 of its malleability. The procefs for giving the yellow 
 colour to copper, by the mixture of zinc, and of its 
 ore called calamine, has been defcribed above under 
 the Ufes of Copper. 
 
 Y 
 
C 
 
 zinc among the calamine-mines in the duchy 
 of Limbourg and in the zinc-mines at Go- 
 flar, where this femimetal was always fur- 
 rounded by a kind of ferruginous yellow earth, 
 or ochraceous fubftances. See the detached 
 article ZINC. 
 B. In form of calx, 
 (i.) Pure. 
 
 a. Indurated. 
 
 1. Solid. 
 
 2. CryRallifed. 
 
 This is of a whitifh-grey colour, and 
 its external appearance is like that of a 
 lead fpar ; it cannot be described, but 
 is eafily known by an experienced eye. 
 It looks very like an artificial glafs 
 of zinc ; and is found among other cala- 
 mines at Namur and in England. 
 (2.) Mixed. 
 
 A. With a martial ochre. 
 
 i. Half indurated. Calamine; Lapis 
 calamlnaris. 
 
 a. Whitilh yellow, 
 
 b. Reddifh brown. This feems to be a 
 mouldered or weathered blende. 
 
 B. With a martial clay or bole, 
 c. With a lead ochre and iron. 
 
 D. With quartz : Zeolite of Friburgh. ' 
 
 The real contents of this fubttance were 
 firft difcovered by M. Pelletier. It was 
 long taken for a true zeolite, being of 
 a pearl colour, cryftallifed, and femitran- 
 fparent. It confifts of laminae, diverging 
 from different centres, and becoming ge 
 latinous with acids. Its contents are 48 
 to 52 per cent, of quartz, 36 of calx of 
 zinc, and 8 or 12 of water. (Juroww, 
 p. 318.) 
 
 C. Mine- 
 
C 245 ] 
 
 C. Mineralifed. 
 
 (i.) With fulphurated iron. Blende, mock- 
 lead, black-jack, mock-ore; pfeudogalena and 
 blende of the Germans. 
 
 A. Mineralifed zinc in a metallic form. Zinc 
 ore. This is of a metallic bluifh-grey 
 colour, neither perfectly clear as a pot 
 ter's ore, nor fo dark as the Swedifh iron 
 ores. 
 
 1. Of a fine cubical or fcaly texture. 
 
 2. Steel-grained. 
 
 E. In form of calx. Blende. Mock-lead ; 
 Sterile nigrum. Pfiudo-galenz (c.) This is 
 
 found, 
 I . Wi th c oti rfe fc al e s. 
 
 a. Yellow ; femi tranfparent, 
 
 . Greenifh. 
 
 c. Greenifh-black ; peclblends t or fitch 
 
 Iknde of the Germans. 
 {/. Blackiih -brown. 
 2. With fine fcales, 
 
 a. White. 
 
 b. Whitifh-yellow, 
 
 c. Reddifh-brown. 
 
 3. Fine and fparkling ; at Gofbr called Iraun 
 blyeriz. Its texture is generally fcaly ; 
 ibmetimescryftallifed and femitranfparent. 
 
 y 2 it. 
 
 (c) The varieties of pfeudo-galena, or black-jack,. 
 are in general of a lamellar or Icaly texture, and fre 
 quently of a quadrangular form, refembling galena, 
 They all lofe much of their weight when heated, and 
 burn with a blue flame ; but their ipecific gravity is con- 
 fiderably inferior to that of true galena. Almoll all 
 contain in mixture of lead-ore. Moft of them exhale a 
 fulphureous fmell when fcraped, or at leaft when vitri> 
 olic or marine acid is dropped on then:. 
 
It gives fire with fteel ; but docs not de 
 crepitate, nor fmoke when heated : yet it 
 lofes about 1 3 per cent, of its weight by 
 torrefaclion. 
 
 a. Dark-brown. 
 
 b. Red, which becomes phofphorefcent 
 when rubbed ; found at Scharfenberg 
 in Mifnia. ( Brnnich ) . 
 
 . . Greenilh, yellowifli-greep., or red. It 
 has different degrees of tranfparency, 
 and is fometimes quite opaque. When 
 fcraped with a knife in the dark, it emits 
 light, even in water; and after under 
 going a white heat, if it is diftilled^r 
 ft, a dliceous fublirnate rifes, which 
 ihows it contains the fpai ry acid, pro 
 bably ur.iud to the metal, imce it iub- 
 limes. 
 
 4. Of a metallic appearance ; glanz llcnds. 
 
 This is of a bluifh-grey, of a fcaly or 
 fleel-grained texture, and its fc;rm gene 
 rally cubical or rhomboidal. It lofes 
 nearly one flxth of its weight by calcina- 
 nation ; and after calcination it is more fo- 
 luble in the mineral acids. 
 
 ico parts of this ore afforded to Berg 
 man about 52 of zinc, 8 of iron, 4 of 
 copper, 26 of fulphur, 6 of filex, and 4 of 
 water. 
 
 5. Cryflalline. 
 
 a. Dark-red, very fcarce ; found in a 
 mine near Freyberg. Something like 
 it is found at the Morgenftern and 
 Himmelsfufte. 
 
 I. Brown. In Hungary and Tranfylva- 
 
 T('TL. 
 
 c. Black. Hungary. 
 
 Thefe 
 
[ 2 4 7 J 
 
 Thefe varieties may eafily be mifhi- 
 ken for rock cryftals ; but by expert- 
 eiice they may be difttnguifhed on ac 
 count of their lamellated texture and 
 greater foftnefs. Their tranfparency 
 arifes from a very fmall portion of iron 
 in them. 
 (2.) Zinc mineralifed by the vitriolic acid. 
 
 This ore has been already defcribed among 
 the middle Salt*, at Vitriol of zinc.- 
 Ufes, &c. of zinc. See the detached article ZINC ;. 
 Alfo CHEMISTRY-/-?^; aod METALLURGY, 
 Part II. feet xii. and Part III. under feel. iii. 
 
 III. Antimony ; Anlimomum Stibium. This femime- 
 tal is, 
 
 a, Of a white colour almofl like filver. 
 
 b. Brittle ; and in regard to its texture, it coruiftj 
 of finning planes of greater length than breadth. 
 
 c. In the Ere it is volatile, and volatilifes part of 
 the other metals along with it, except gold and 
 platina. It may, however, in a moderate fire, 
 be calcined into a light-grey calx, which is pretty 
 refractory in the' fire ; but meks at la-ft to a glafs, 
 of a reddiih-brown colour.. 
 
 d. It di Halves in fpirit of fea-falt and aqua-regia, 
 but is only corroded by the ipirit of nitre into- 
 n white cab: ; it is precipitated out of the aqna.- 
 regia by watsr* 
 
 e. It has an emetic quality when its calx, glaf?,. < 7 
 metal, is diffrlved in an. acid, except when in thi 
 fpirit of nitre, which has nc>t this eiTeol:. 
 
 f. It amalgamates with q.uickfilver, if the regulu c ,, 
 when fuied, is put to it ; but the quiekfilver ought, 
 for this purpofe to be covered with w,irm water ; 
 it amalgamates with it likewife, if the regulus c,f 
 antimony be previoufly melted with an addition* 
 
 Y 3, Antuacnjr 
 
C 248 ] 
 
 Antimony is found in the earth. 
 A. Native. Regulus antlmoniinai'wus. 
 
 This is of a filver colour, and its texture is 
 compofed of pretty large {Lining planes. 
 
 This kind was found in Carls Ort, in the 
 mine of Salberg, about the end of the laft cen 
 tury ; and fpecimens thereof have been prefer- 
 ved in collections under the name of an arienical 
 pyrites, until the mine-m after Mr Von Swab dif- 
 covered its real nature, in a treatile he communi 
 cated to the Royal Academy of Sciences at 
 Stockholm in the year 1748. Among other re 
 markable obfervationa in this treatife, it is faid, 
 firft, That this native antimony eafily amalga 
 mated with quickfilver ; doubtlefs, becaufe it was 
 imbedded in limeftone ; fince, according to Mr 
 Pott's experiments, an artificial regulus of anti 
 mony may, by means of lime, be difpofed to an 
 amalgamation : Secondly, That when brought 
 in form of a calx, is (hot into cryftals during the 
 cooling. 
 
 JB, Mineralifed antimony. 
 (i)Withfulphur. 
 
 This is commonly of a radiated texture, 
 
 compofed of long wedge-like flakes or plates ; 
 - it is nearly of a lead-colour, and rough to the 
 
 touch. 
 
 a. Of coarfe fibres. 
 
 b. Of fmall fibres. 
 
 <7. Steel-grained, from Saxony and Hungary. 
 <?. Cryftallifed, from Hungary. 
 
 I. Of prifmatical, or of a pointed pyrami 
 dal figure, in which laft circumftance the 
 points are concentrical. 
 
 Cronftedt mentions a fpecimen of this,. 
 in which the cryftals were covered with 
 very minute cryftals or quartz, except at 
 the extremities, where there was always 
 
 a little 
 
t 249 3 
 
 a little hole : this fpecimen was given for 
 afosferri fpar. 
 
 (2.) With fulphur and arfenic. Red antimony 
 ore ; Antimonium folare. 
 
 This is of a red colour, and has the fame 
 texture with the preceding, though its fibres 
 are not fo coarfe. 
 
 a. With fmall fibres. 
 
 b. With abrupt broken fibres, from Braunf- 
 dorffin Saxony, and from Hungary. 
 
 All antimonial ores are fomewhat arfe- 
 nical, but this is more fo than the preceding 
 kinds. 
 (3.) With fulphurated filver. Plumofe filver- 
 
 ore, vrfederertz of the Germans. 
 (4.) With fulphurated filver, copper, and arfe 
 nic ; the dalfahl-ertz of the Germans. 
 
 With iulphurated lead ; radiated lead-ore. 
 By the aerial acid. 
 
 This ore was lately difcovered by Mongez, 
 among thofe of native antimony from the 
 mine of Chalanc'es in Dauphiny. It confifts 
 of a group of white cryftallifed filaments of a 
 needle-form appearance, diverging from a com 
 mon centre, like zeolite. They are infoluble 
 in nitrous acid ; and, on being urged by the 
 flame of a blow-pipe, upon apiece of charcoal, 
 they are diffipated into white fumes, or anti 
 monial flowers, without any fmell of arfenic ; 
 from whence it follows, that thefe needle form 
 ed cryftals are a pure calx of antimony, form 
 ed by its combination with, or mineralifed by, 
 the aerial acid. See Kirzuan, p. 325, and 
 Journal de Phyfique for July 1787, p. 67. 
 Iffes, &c. By the name of antimony is commonly 
 underftood the crude antimony (which is com 
 pounded of the metallic part and fulphur) as it is 
 
 melted 
 
 J.1K 
 
 It} 
 
5o J 
 
 melted out of the ore ; and by the name of regu 
 lus, the pure femimetal. 
 
 r. Though the regulus of antimony is a metallic 
 fubftance, of a confiderably bright white colour,, 
 and has the fplendor, opacity, and g: ivity of a 
 metal, yet it is quite unmalieable, ana falls into 
 powder initead of yielding cr expand" i r uuder 
 the hammer ; on \vhich account; it is clalled among 
 the femimet.ils. 
 
 2. Regulus of antimony is ufed in various metallic 
 mixtures, as [or pr.nting types, metallic fpecu- 
 lums, &c. and it enters into the belt fort of pew 
 ter ware. 
 
 3. It mixes with, and diflblves various metals 5 in 
 particular it affects iron the moft powerfully ; and 
 what is very remarkable, when mixed together, 
 the iron is prevented from being attracted by the 
 load (lone. 
 
 4. It affects copper next, then tin, lead, and filver; 
 promoting their fufion, and rendering them all 
 brittle and unmalleable : but it will neither unite 
 with gold nor mercury ; though it may be made 
 to combine with this laft by the interpolation of 
 fulphur. In this cafe it refembles the common 
 JEthiops, and is thence called antimontal JEth'iops. 
 
 5. Regulus of antimony readily unites with fulpbur 
 and forms a compound of a very faint metallic 
 fplendor : it afiuitfes the form or long needles ad 
 hering together laterally : it ufually formed na 
 turally alfo in this fhape. This is called cruJs 
 antimony. 
 
 6. But though antimony has a confrderable affinity 
 to fulpkur ; yet all the metals, except grid and 
 mercury, have a greater affinity to that com 
 pound. If therefore iron, copper, lead, filler, 
 or tin, be melted with antimony, the fulphur will 
 unite with the metal, an j be fcparated- from the 
 
 regulus* 
 
[ 25' 1 
 
 re^ulus, which, however, takes up fome part of 
 the metal, for which reafon it is called martial re- 
 gufuSf regiAus veneris, &c. 
 
 7. When gold is mixed, or debafed by the mixture 
 of other metals, it may be fufed wirh antimony j 
 for the fulphur combines with the bafe metals, 
 which, being the lighter, rife up into fcoria, 
 while the regulus remains united at the bottom 
 with the gold ; which being urged by a (Ironger 
 degree of heat, is freed from the femimetal, which 
 is very volatile. This method of refining gold is 
 the eafieft of all. 
 
 8. But the moft numerous purpofes to which this 
 metal has been applied are thofe of the chemical 
 and pharmaceutical preparations. Lemery, in 
 bis Treat ife on Antimony, dffcribes no lefs than 
 2CO procefTes and formulas; among which there 
 are many good and many ufelefs ones. The fol 
 lowing deferve to be mentioned on account of their 
 utility. 
 
 9. Antimony melts as foon as it is moderately red 
 hot, but cannot fuftain a violent degree of fire, 
 as it is thereby diffipaced into fmoke and white va 
 pours, which adhere to fuch cold bodies as they 
 meet with, and are collected into a kind of fariua 
 or powder, called Jiowers of antimony, 
 
 jo. If it be only moderately heated, in very fm all 
 pieces, fo as not to melt, it becomes calcined in 
 to a greyifh powder deftitute of all fplendor, cal 
 led calx cf antimony . This calx is capable of en 
 during the moft violent fire ; but at latl it will run 
 into a glafs of a reddifh-yellow colour, fimilar to 
 that of the hyacinth. The infufion made of this 
 coloured antimonial glafs, in acidulous wine (fuch 
 ris that of Bourdeaux) for, the fpaoe of 5 or 6 
 hours, is a very violent emetic. 
 
 ii. If equal parts of nitre and regulus of antimony 
 be de-flaunted over tho fi'-e, the grey calx which 
 remains is called liver of antimony. 
 
 12. If 
 
1 2. If regulus of antimony be melted with two parts 
 of fixed alkali, a mafs of a reddifli-yellow colour 
 is produced, which being diflblved in water, and 
 any acid being afterwards added, a precipitate is 
 formed of the fame colour, called golden Julphur of 
 antimony. 
 
 13. Fixed nitre, viz. the alkaline fait that remains 
 after the deflagration of nitre, being boiled with 
 fmall pieces of regulus of antimony, the folution 
 becomes reddifh ; and, on cooling, depoOts the 
 antimony in the form of a red powder, called mi 
 neral kermes. 
 
 14. Equal parts of the glafs, and of the liver of an 
 timony, wellpulverifed and mixed with an equal 
 quantity of pulverifed cream of tartar, being put 
 mto as much water as will diflblve the cream of 
 tartar, and boiled for 12 hours, adding now and 
 then fome hot water to replace what is evapora 
 ted, the whole is to be filtered while hot ; then 
 being evaporated to drynefs, the faline matter 
 that remains is the emetic tartar. 
 
 15. The regulus of antimony being pulverifed, and 
 diftilled with corrofive fublimate of mercury, a 
 thick white matter is produced, which is ex 
 tremely corrofive , and is called butter of antimony. 
 This thick fubftance may be rendered limpid and 
 fluid by repeated diftillations. 
 
 1 6. On mixing the nitrous acid with this butter of 
 antimony, a kind of aqua regia is diftilled, call 
 ed bezoardic fpirit of nitre. 
 
 17. The white matter that remains from this lad 
 diftillation may be rediftilled with frefh nitrous 
 acid ; and the remainder being waftied with wa 
 ter, is called be%oar mineral, which is neither fo 
 volatile nor fo cauftic as the antimonial butter. 
 This butter being mixed with water, a precipi 
 tate falls to the bottom, which is very improper 
 ly called mereurius vite, for it is in fa& a very vi 
 olent emetic. 
 
 1 8. But 
 
C *53 D 
 
 1 8. But if, inftead of the regulus, crude antimony 
 be employed, and the fame operation be perfor 
 med, the regulinepartfeparates from the fulphur, 
 unites to the mercury, and produces the fubftance 
 which is called cinnabar of antimony. 
 
 19. Crude antimony being projected in a crucible, 
 in which an equal quantity of nitre is fufed, deto 
 nates ; is calcined, and forms a compound called 
 by the French fondant de Retrou, or antlmoine di 
 aphoretique non lave. This being diffolved in hot 
 water, falls to the bottom after it is cold ; and 
 after decantation is known, when dry, by the 
 name of diaphoretic antimony. This preparation 
 excites animal perfpiration, and is a good fudori- 
 fic. ^The fame preparation may be more expedi- 
 tioufly made by one part of antimony with two 
 and a half of nitre, mixed together and deflagra 
 ted : the refidue of which is the mere calx of an 
 timony, void of all emetic power. 
 
 20. And if the detonation be performed in a tubu 
 lated retort, having a large receiver, containing 
 fome water adapted to it, both a clyffus of anti 
 mony and the antimonial flowers rnay be oblain- 
 edat the fame time, as Neumann afierts. 
 
 2 1 . When nitre is deflagrated with antimony over 
 the fire, the alkaline bafis of the nitre unites with 
 the calx of the femimetal, which may be fepara- 
 ted by an acid, and is called materia perlata. See 
 farther the article ANTIMONY ; alfo METALLUR 
 GY, Part II. fe6t ix. 
 
 IV. Arfenic. In its metallic form, is, 
 
 a. Nearly of the fame colour as lead, but brittle, 
 
 and changes fooner its fKining colour in the air, 
 
 firft to yellow, and afterwards to black. 
 I. It appears laminated in its fractures, or where 
 
 broken. 
 c. Is very volatile in the fire, burns with a fmall 
 
 flame, and gives a very, difagreeable fmell like 
 
 garlic. 
 
 t 
 
C 2 54 ] 
 
 <L It is, by reafon of its volatility, very difficult 
 t^ be reduced, unlefs ft is mixed with other me 
 tals : However, a regulus may be got from the 
 white arfenic, if it is quickly melted with equal 
 r. arts of pot allies andfoap; but this regulus con 
 tains generally fome cobalt, mod of the white 
 arfenic being produced from the cobalt ores du 
 ring their calcination. The white arfenic, mix 
 ed with a phlogifton, fublim^s likewife into cc*lo- 
 edral cryitals of a metallic appearance, whofe fpe- 
 cific gravity is 8,308. 
 
 t. The calx of arfenic, which always, on account of 
 
 its volatility, muft be got as a fublimation, is 
 
 white, and eafily melts to a glafs, whole fpecific 
 
 gravity is 5,000. When fulphur is blended in 
 
 ^ this calx, it becomes of a yellow, orange, or red 
 
 ^colour; and according to the degrees of colour 
 
 is called orpiment or yellow arfenic ; fandarach, re- 
 a/gar, or red arfenic ; and alfo rubinus arfenlci. 
 
 f. This calx and glafs are diflbluble in water, and 
 in all liquids ; though not in all with the fame 
 facility. In this circumltance arfenic refembles 
 the falts ; for which reafcn it alfo might be rank 
 ed in that clafs. 
 
 g. The regulus of arfenic diffolves in fpirit of nitre; 
 but as it is very difficult to have it perfectly free 
 from other metals, it is yet very little examined 
 in various menftrua. 
 
 h. It is poifonous, efpecially in form of a pure 
 calx or glafs : But probably it is lefs dangerous 
 when mixed with fulphur, iince it is proved by 
 experience, that the men at mineral works are 
 not fo much affected by the fmoke of this mix 
 ture as by the fmoke of lead, and that fome na 
 tions make ufs of the red arfenic in fmall dofes 
 as a medicine. 
 
 i. It unites with all metals, and is likewife much 
 ufed by nature itfe.lf to diffoive, or, as we term 
 it, to minera/ifc, the metals, to which its vola 
 tile 
 
[ J5 3 
 
 tility and diftblubility in water mud greatly con 
 tribute. It is likewife moft generally mixed with 
 fulphur. 
 
 k. It abforbs or expels the phlogiflon, which has co 
 loured glafTes, if mixed with them in the fire. 
 
 Arfenic is found, 
 
 [t.] Native; called Scherbencoboh and FKegenflein 
 by the Germans. 
 
 It is of a lead colour when frefh broken, and 
 may be cut with a knife, like black lead, butfooti 
 blackens in the air. It burns with a fznall flame, 
 and goes off in fmoke. 
 
 A. Solid and teftaceous ; Scherbencoboh. 
 
 B. Scaly. 
 
 C. Friable and porous ; Fllegenftein. 
 ( i.) With fhining mTures. 
 
 This is by fome called Spigel cobalt. 
 [2.3 In form of a calx. 
 
 A. Pure, or free from heterogeneous fubftances. 
 
 1. Loofe or powdery. 
 
 2. Indurated, or hardened. This is found in 
 form of white femi-tranfparent cry Hals. 
 
 B. Mixed. 
 
 A. With fulphur. 
 i. Hardened. 
 
 a. Yellow. Orpiment ; Auripigmentnm. 
 
 b. Red. Native realgar, or fandarach. 
 B. With the calx of tin, in the tin-grains. 
 
 c. With fulphur and filver; in the rotkguldcn 
 or red filver ore. 
 
 D. With calx of lead, in the lead-fpar. 
 
 E. With calx of cobalt, in the efflorefcence 
 of cobalt. 
 
 [3.] Mineralifed. 
 
 A. With fulphur and iron. Arfenical pyrites 
 or marcafite. Thefe kinds in Cornwall are 
 called Jilvsry or white mundics and plate mun- 
 dies. 
 
 7, This 
 
This alone produces red arfenic when calci 
 ned. It is of a deeper colour than the follow 
 ing. 
 
 . With iron only. This differs with regard to 
 its particles ; being, 
 
 1. Steel-grained. 
 
 2. Coarfe-grained. 
 
 3. Cryftallifed. 
 
 a. In an oclcedral figure. This is the moft 
 common kind. 
 
 b. Prifmatical. The fulphureous marcafite 
 is added to this kind when red arfenic is 
 to be made ; but in Sweden it is fcarcer 
 than the fulphureous arfenical pyrites. 
 
 C. With cobalt, almoft in all cobalt ores. 
 
 D. With filver. "> c , .. 
 
 E. With copper. [ See " nc l er . ***" 
 
 F. With antimony. j and Antl ^ 
 
 For the Ufes of Arfemc, fee the detached article 
 ARSENIC, and CHEMISTRY -Index ; alfo ME 
 TALLURGY, Part II. fecr. xiii. and Part III. 
 feel:, viii. 
 
 V. Cobalt. 
 
 This fernlmetal is, 
 
 a. Of a whitifh grey colour, nearly as fine-tern- 
 pered fteel. 
 
 b. Is hard and brittle, and of a fine-grained tex 
 ture; hence it is of aduiky, or not fhining ap 
 pearance. 
 
 c. Itsfpecific gravity to water is 6000 to 1000. 
 
 d. It is fixed in the fire, and becomes black by 
 calcination : it then gives to glalfes a blue co 
 lour, inclining a little to violet, which colour, 
 of all others, is the moft fixed in fire. 
 
 A The concentrated oil of vitriol, aquafortis, and 
 aqua-regia, diffolve it ; and the folutiorts become 
 red. The cobalt calx is likewife diflblved by 
 
 the 
 
the -fame menflrua, and alfo by the volatile al 
 kali and the ipirit of fea fait. 
 
 f. When united with the calx of arferiic in a flow 
 (not a brifk) calcining heat, it aiiiimes a red 
 colour : the fame colour is naturally produced 
 by way of efflorefcence, and is then called the 
 lloom orjlutvers of cobalt. When cobalt and ar- 
 fenic are melted together in an open fire, they 
 produce a blue flame. 
 
 g. It does not amalgamate with quickfilver by any 
 means hitherto known. 
 
 h. Nor does it mix with bifrrmth, when melted 
 
 with it, without addition of fome medium to 
 
 promote their union. 
 
 i.] Native cobalt. Cobalt "with arfenic and iron 
 in a metallic form. 
 
 Pure native cobalt has not yet been found : 
 that which pafles fox fuch, according to Kirvvan, 
 is mineralifed by arfenic. Bergman, however, in 
 his Sciagraphia, has entered this prefent ore un 
 der the denomination of native cobalt: and cer 
 tain it is, that among all the cobaltic ores, this 
 is the neareft to the native ftate of this femime- 
 tal. It always contains a fmall quantity of 
 iron, befides the arfenic, by which it is minerali 
 fed. 
 
 This is of a dim colour when broken, and not 
 unlike fteel. It is found, 
 c. Steel -grained, from Loos in the parifh of Fa- 
 
 rila in the province of Helfmgeland, and Schnee- 
 
 berg in Saxony, 
 1. Fine-grained, from Laos. 
 
 c. Coarfe-grained. 
 
 d. Cryftallifed : 
 
 1. In a denditrical or arborefcent form ; 
 
 2. Polyhedral, with (Lining furfaces ; 
 
 3. In radiated nodules. 
 
 Z 2 [>] Cal- 
 
[2 ] Ciilciform cobalt. Cobalt is mod commonly 
 found in the earth mixed with iron. 
 A. In form of a calx. 
 
 j.) With'iron without arfenic. 
 
 a. jLooie or friable ; cobalt ochre. This 
 is black, and refembles the artificial 
 z a fire. 
 
 l\ Indurated : Mlnera colal.il vtirea. The 
 fchlacken or flag cobalt. Th's is likewife 
 of a black colour, but of a gialTy texture, 
 and feems to have loft that i'ubftance which 
 rnineralifed it, by being decayed or wea 
 thered. 
 
 J.) With arfenical acid; cobalt-blut, Germ. 
 Ochra cobahi rulra ; bloom, flowers, or efflo- 
 refcence of cobalt. 
 
 a. Loofe or friable. This is often found of 
 a red colour like other earths, fpread very 
 thin on the cobalt ores ; and is, when of a 
 pale colour, erroneoufly calhdfawers of 
 btfmnth. 
 
 b. Indurated. This is commonly cryftalli- 
 fed in form of deep red femitranfparent 
 rays or radiations : It is found at Schnee- 
 berg in Saxony. 
 
 jB. Mineralifed. 
 
 i.) With fulphurated iron. 
 
 This ore is of a light colour, nearly re- 
 fembling tin or filver. It is found cryftalli- 
 fed in a polygonal form. 
 a. Of a flaggy texture. 
 I. Coarfe-grained. 
 
 This ore is found in Baftnafgrufva at 
 Raddarfhyttan in Weftmanland, and difco- 
 vers not the leaft mark of arfenic. The 
 coarfe-grained becomes ilimy in the fire, and 
 iticks to the ftirring hook during the calci 
 nation in the fame manner as many regules 
 
 do: 
 
[ *S9 ] 
 
 do : It is a kind of regule prepared by na 
 ture. Both thefe give a beautiful colour. 
 2.) Withfulphur, arlenic, and iron. This re- 
 fembles the arfenicaved cobalt ore, being on 
 ly rather of a. whiter or lighter colour. It 
 is found, 
 
 a. Coarfe-grained. 
 
 b. Cryftalliied; 
 
 I. In a polygonal figure, with ftiining fur- 
 faces, or glanzkobolt. It is partly of a 
 white or light colour, and partly of a 
 fomewhat reddiih yellow. 
 (3.) With fulphurate-d and arfenjcated nickel 
 
 and iron ; fee Kupfcr-nickel, below. 
 Ufes, &c. See the article COBALT. S?e alfo CHE- 
 MISTRY-//W/WC/ and METALLURGY, Part II. 
 feel. xi. 
 
 VI. Nickel ; Nicolum. This is the lateft difcovered 
 femimetal. It was firft defcribed by its difco- 
 verer Mr Cronftedt, .in the Ads of the Royal 
 Academy of Sciences at Stockholm for the years 
 1751 and i 54, where it is faid to have the fol 
 lowing qualities : 
 
 j. It is of a white colour, which, however, in 
 clines fomewhai to red. 
 
 2. Of a folid texture and fhining in its frac 
 tures. 
 
 3. Its fpecific gravity to water is as 8,500 to 
 
 IOOO. 
 
 4. It is pretty fixed in the fire ; but, together 
 with the fulphur and arfenic, with which ies 
 ore abounds, it is fo far volatile, as to rife in 
 form of hairs and branches, if in the calcina 
 tion it is ^eft without being ftirred. 
 
 5. It calcines .to a green calx. 
 
 6. The calx is not very fu'ible, but, however, 
 tinges glafs of a tranfjparent reddifli-brown or 
 jacinth colour. 
 
 Z 3 7- It 
 
[ 260 ] 
 
 ' 7. It diffulves in aqua-fortis, aqua-regia, and the 
 fpirit of fea-falt ; but more difficultly in the vi 
 triolic acid, tinging all thefe folutions of a deep 
 green colour. Its vitriol is of the fame co 
 lour ; but the colcothar of this vitriol, as well 
 as the precipitates from the folutions, become 
 by calcination of a light green colour. 
 
 8. Thefe precipitates are diflblved by the fpirit 
 offal ammoniac, and the folution has a blue 
 colour ; but being evaporated, and the fediment 
 reduced, there is no copper, but a nickel re- 
 gulus is produced. 
 
 9. It has a flrong attraction to fulphur ; fo that 
 when its calx is mixed with it, and put on a 
 icorifying teft under the muffle, it forms with 
 the fulphur a regule : this regule refembles the 
 yellow fteel-grained copper-ores, and is hard 
 and ihining in is convex furface. 
 
 10. It unites with all the metals, except quick- 
 filver and filver. When the nickel regulus is 
 melted with the latter, it only adheres clofe to 
 it, both the metals lying near one onother on 
 the fame plane; but they are eafily feparated 
 with a hammer. Cobalt has the ftrongeft at 
 traction to nickel, after that of iron, and then 
 to arfenic. The two former cannot be fepa 
 rated from one another but by their fcorifica- 
 tion ; which is eafily done, fmce, 
 
 11. This femnnetal retains its phlogifton a long 
 time in the fire, and its calx is reduced by the 
 help of a very fmall portion of inflammable 
 matter: it requires, how ever, a red heat before 
 it can be brought into fufion, and melts a little 
 fooner, or almoft as foon, as topper or gold, 
 confequently fooner than iron. 
 
 Nickel is found. 
 A Native. 
 
 This 
 
r 261 ] 
 
 This is mentioned by Mr Rinman to have 
 been lately met with in a mine of cobalt in HefTe. 
 It is very heavy, and of a liver colour, that is, 
 dark red. When pulverifed and roafted under a 
 muffle, it forms green excrefcences, and fmokes ; 
 but its fraoke has no particular fmell : and no 
 fublimate, whether fulphureous or arfenic^l, can 
 be caught. It is foluble in acids, and the folu- 
 tion is green ; but a polifhed iron plate difcovers 
 no copper. 
 
 B. In form of a calx. Nickel ochre, aerated nic- 
 kel. 
 
 i. Mixed with the calx of iron. This is green, 
 and is found in form f flowers on kupfer- 
 nickel. 
 
 C. Mineral! fed. 
 
 1. With fulphurated and arfenicated iron and co 
 balt; KupfirnickeL This is of a reddiih yel 
 low colour; and is found, 
 
 a. Of a flaggy texture. 
 
 I. Fine-grained ; and 
 
 c. Scaly. Thefe two are often from their co 
 
 lour confounded with the liver-coloured 
 
 marcafite. 
 
 2. With the acid of vitriol. This is of a beau 
 tiful green colour, and may be extracted out 
 of the nickel ochre, or efflorefcence of the 
 Kupfernickel. 
 
 For a fill; account of this femimetal, fee the ar 
 ticle. NICKEL, and 
 
 VII. Manganefe. Mangane/ium. 
 
 The ores of this kind are in Swedifh called 
 Irunjlen ; in Latin fyderetf, or magmfia nigr#, in 
 order to diftinguifh them from the magncfia alba 
 offictnalis ; and in French manganefe, &c. 
 3. Manganefe confifts of afubftance which ofives 
 a colour both to glaffes and to the folutiong 
 
 of 
 
 
C 262 ] 
 
 of falls, or, which is the fame thing, both 
 to dry and to liquid menft: ua, viz. 
 
 a. Borax, which has diilolved manganefe in 
 the fire, becomes transparent, of a reddifh 
 brown or hyacinth colour. 
 
 b. The microcofmic fait becomes tranfparent 
 with it, of a crimfon colour, and moulders in 
 the air. 
 
 e. With the fixed alkali, in compofitions of 
 glafc, it becomes violet ; but if a great 
 quantity of manganefe is added, the glafs is 
 in thick lumps, and looks black. 
 
 d. When fcorified with lead, the glafs obtains 
 a reddilh brown colour. 
 
 c. The lixivium of deflagrated manganefe is cf 
 a deep red colour. 
 
 2. It deflagrates with nitre, which is a proof 
 that it contains fome phlogiilon. 
 
 3. When reckoned to be light, it weighs as 
 
 much as an iron ore of the fame texture. 
 
 4. When melted together with vitreous compo 
 
 fitions, it ferments during the folution : but it 
 ferments in a ftill greater degree-when it is 
 melted with the microcofmic fait. 
 
 5. It does not excite any eiFervefcence with the 
 nitrous acid : aqua-regia, however, extracts 
 the colour out of the black manganefe, and 
 duTolves likewife a great portion of it, which 
 by means of an alkali is precipitated to a white 
 powder. 
 
 6. Such colours as are communicated to glafles 
 by manganefe, are eafUy deftroyed by the calx 
 of arfenic or tin : they alfo vaniih of themfelves 
 in the fire. 
 
 7>. It is commonly of a loofe texture, fo as to co 
 lour the fingers like foot, though it is of a me 
 tallic appearance when broken. 
 
 Manganefe is found, 
 
 [i.] Nar 
 
[ 26 3 3 
 
 j~i.] Native; of the difcovery and qualities of 
 which, an account is given under the article 
 MANGANESE in its alphabetical order. See alfo 
 CHEMIST R TL -Index. 
 
 [2.] Calciform. 
 
 A. Loofe and friable. 
 
 a. Black ; which feems to be weathered or de 
 cayed particles of the indurated kind. 
 
 B. Indurated. 
 
 i.) Pure, inform of balls, whofe texture con- 
 fids of concentric fibres. Pura fpbarica ra- 
 dns concentratis. 
 a. White ; very fcarce. 
 2.) Mixed with a fmall quantity of iron. 
 a. Black manganefe, with a metallic bright- 
 nefs. This is the mod common kind, 
 and is employed at the glafs-houfes and 
 by the potters. It is found, 
 
 1. Solid, oi a flaggy texture. 
 
 2. Steel-grained. 
 
 3. Radiated. 
 
 4. Cryftallifed, in form of coherent hemi- 
 fpheres. 
 
 VIII. Molybdena. 
 
 A. Lamellar and fliining, its colour fimilar to that 
 of the potter's lead ore. 
 
 This fubftance refembles plumbago or black- 
 lead ; and has long been confounded with it, 
 even by Cronftedt. But it poffeiTes very different 
 properties ; in particular, 
 
 1. Its laminse are larger, brighter: and, when 
 thin, flightly flexible. They are of an hexa 
 gonal figure. 
 
 2. It is of a lead colour, and does not flrike fire 
 with hard fteel. 
 
 3. Its fpeciftc gravity is = 4,569, according to 
 Kirwan ; and 457385, according to Briflbn. 
 
 12. This 
 
264 ] 
 
 4^ When rubbed on white paper, it leaves 
 traces of a dark brown or bluiih colour, as 
 the plumbago or black lead does ; but they 
 are rather of an argentine glofs ; by which cir 
 cumftance tire molybdena, according to Dr 
 d'Arcet, may be eafily diiVinguiihed from 
 black-lead, as the traces made by this laft are 
 of a lefs brilliant, and of a deeper tinge. 
 
 5. In an open fire, it is almoft entirely volatile 
 and infufible. Microcofmic fait or borax 
 fcarcely affect it ; but it is ailed upon with 
 much effervefcence by mineral alkali, and forms 
 with it a reddiih mafs, tvhhh fmells of fulphur. 
 
 6. It confifts of an acid of peculiar nature (fee 
 CHEMISTRY-/^*. ) united to fulphur. A 
 fmall proportion of iron is commonly found in 
 it, but this feems merely fortuitous : ico parts 
 of molybdena contain about 45 of this acid 
 and 55 of fulphur. 
 
 7. It is decornpoied either by detonation with ni 
 tre, or by folution in nitrous acid. 
 
 8. This acid is foluble in 570 times its weight of 
 water in the temperature of 60; the folu 
 tion reddens that of litmus, precipitates ful- 
 phur from the folution of liver of fulphur, 
 &c. The fpecifk gravity of the dry acid is 
 3,460. 
 
 9. This acid is precipitable from its folution in 
 water by the Pruffian alkali, and alfo by tinc 
 ture of galls : the precipitate is reddiih brown. 
 
 10. If this acid be diftilled with three times its 
 weight of fulphur, it reproduces molybdena. 
 
 1 1 . The folution of this acid in water unites to 
 fixed alkalies, and forms cryftallifable falts ; as 
 it alfo does^with calcareous earth, magnefia, 
 and argil : thefe laft combinations are difficult 
 ly foluble. It acts alfo on the bafc metals, and 
 with them aiTumes a bluifh colour. 
 
12. This folution precipitates filver, mercury, or 
 lead, from the nitrous acid, and lead from the 
 marine, but not mercury. 
 
 13. It alfo precipitates barytes from the nitrous 
 and marine acids, but no other earth. Mo- 
 lybdenous barofelenite is foluble in cold water. 
 
 14. This acid is itfelf foluble in the vitriolic acid 
 by theaffiilar.ee cfheat; and the folution is 
 blue when cold, though colourlefs while hot ; 
 it is alfo foluble in the marine acid, but not in 
 the nitrous. 
 
 15. Molybdena tartar and ammoniac precipitate 
 all metals from their folutions by a double affi 
 nity. Gold, fublimate correfive, zinc, and 
 manganefe, are precipitated white ; iron or tin, 
 from the marine acid, brown ; cobalt, red ; 
 copper, blue ; alum and calcareous earth, white. 
 
 1 6. This acid has been lately reduced by Mr 
 Hielm ; but the properties of the regulus thus 
 obtained are not yet publifhed. 
 
 17. Mr Pelletier obtained alfo the regulus or 
 molybdena, by mixing its powder with oil into 
 a pafte, and expofing it with powdered char 
 coal in a crucible to a very violent fire for two 
 hours. See CHEMISTRY-/^.V, n 14, 97, 
 
 18. This femimetal being urged by a ilrong fire 
 for an hour, produces a kind of filvery flowers, 
 like thofe of antimony. 
 
 19. Molybdena is faid to be foluble in melted ful* 
 phur ; which feems highly probable, as ful- 
 phur is one ot its component parts. 
 
 See Farther the article MOLYBDSNA, and 
 
 C H E M I S T R Y - 
 
 IX. Wolfram. IVolfranum, Spuma Lvpi t Lat. See 
 the detached article WOLFRAM. 
 
 This mineral has the appearance of manganefe, 
 blended with a fmall quantity of iron and tin. 
 
 i. With 
 
[ 266 ] 
 
 I. With coarfe fibres. 
 
 a. Of an iron-colour, from Altenberg in Sax 
 ony. This gives to the glafs compofitions, 
 and alfo to borax and the microcofmic fait, an 
 opaque whitifh yellow colour, which at laft 
 vanifhes. 
 
 X. Siderite. 1 See thofe words in the order of the 
 
 XI. Saturnite.j alphabet. 
 
 APPENDIX. 
 
 Of Saxa and Petrifactions. 
 
 THOUGH the Saxa, and foffils commonly called 
 PetrifaBiom, camu t, in ftrictnefs, be ranked in a 
 mineral fyftem, for the reafons formerly given ; yet 
 as thefe bodies, efpecially the latter, occupy fo con- 
 iiderable a place in mod mineral collections, and the 
 former muft neceflarily be taken notice of by the miners 
 in the obfervations they make in fubterranean geogra 
 phy, it appeared proper to fubjoin them in fuch an or 
 der as migfit anfwer the purpofe for which they are re 
 garded by miners and mineralogifts. 
 
 Order I. SAXA. Petra. 
 
 Thefe maybe divided into two kinds, 
 
 1. Compound faxa, are ftones whofe particles, con- 
 fitting of different fubftances, are fo exactly fitted and 
 joined together, that no empty fpace, or even cement* 
 can be perceived between them ; which feems to indi 
 cate, that fume, if not all, of thefe fubftances have 
 been fo! t at the inftant of their union. 
 
 2, Conglutinattd ftones, are ftones whofe particles 
 have been united by fome cerwentitious fubftance, 
 which, however, is feldom perceivable, and which of- 
 
 been 
 
C 267 3 
 
 been hard, \vorn cfF, and in loofe, fmgle, unfigured 
 pieces, before they were united. 
 I. Compound faxa. 
 
 A. Ophites. Scaly limeftone with kernels or 
 bits of ferpentine ft one in it. 
 
 1. Kolmord marble. It is white and green. 
 
 2. Serpentine antico, is white, with round pieces 
 of black fteatites in it. This muft not be 
 confounded with llizferpentino verde.antico. 
 
 3. The Haraldfio marble. White, with qua 
 drangular pieces of a black fteatites. 
 
 4. The marmor> pozzevem di Geno<va. Dark 
 green marble, with white veins. This kind"* 
 receives its fine polilh and appearance from 
 the ferpentine ftone, 
 
 B. Stellften or geJleljleiK. Granitello. 
 
 1. Of diftin<2: particles. In fome ofthefeths 
 quartzofe particlespredominate, and in others 
 the micaceous : in the laft cafe it is com 
 monly flaty, and eafy to fplit. 
 
 2. Of particles which are wrapt up in one ano 
 ther. 
 
 a. Whitifh grey. 
 
 b. Greeniih. 
 
 c. Reddiflh. 
 
 C. Norrka. Murkjltn of the Swedes. Saxum 
 cojnpojitiim mica, quarfzo, et gramto. 
 
 1. With diftincl garnets or fhirl. 
 
 a. Light grey. 
 
 b. Dark grey. 
 
 c. Dark grey, with prifmatical, radiated, or 
 fibrous cockle or fhirl. 
 
 2. Wi^h kernels of garnet-ftone. 
 a. Of pale red garnet ftone. 
 
 The firtl of this kind, whofe flaty ftrata makes 
 it commonly eafy to be fplit, is employed 
 for mill-ftones, which may without difficul 
 ty be accomplilhed, if land is firft ground 
 A a with 
 
[ 268 ] 
 
 with them ; becaufe the fand wearing away 
 the micaceous particles on the furfaces, and 
 leaving the garnets predominant, renders 
 the ftone fitter for grinding the corn. 
 D. The whetftone, Cos. Saxum compofitum mca 9 
 quartxot et oran argilla martiali in nonnullis fpe~ 
 debus. 
 
 1 . Of coarfe particles. 
 a. White. 
 
 t. Light grey. 
 
 2. Of fine particles. 
 
 a. Liver-brown colour. 
 l>. Blackifh grey. 
 . Light grey. 
 
 </. Black. The table-date, or that kind tifed 
 for large tables and for fchool dates. 
 
 3. Of very minute and clofely combined par 
 ticles. The Turkey-ftone. This is of an 
 olive colour, and feems to be the fined mix 
 ture of the firft fpecies of this genus. The 
 beft of this fort come from the Levant, and 
 are pretty dear. The whetftone kinds, 
 when they fplit eafily and in thin plates, 
 are very fit to cover houfes with, though 
 moft of them are without thofe properties. 
 
 F. Porphyry ; Porphyntes. Italorum porfido. 
 Saxum compofitum jafpide etfe/t/pafo, inter dum mica 
 etbafahe (D). See the article PORPHYRY. 
 
 (D) Great part of the hill of Bineves in Lochaber is 
 compofed of a kind of porphyry. It is remarkably 
 fine, beautiful, and of an elegant reddifh colour; "in 
 which (fays Mr Williams) the pale rofe, the blufh, 
 and the yellowifli white colours, are finely blended and 
 lhaded through the body of the ftone ; which is of a 
 jelly like texture, and is undoubtedly one of the fined 
 and moft elegant ftones in the world. On this hill alfo 
 
 k 
 
 
C 269 3 
 
 a. Its colour is green, with light-green feltfpat, 
 Serpsntino *oerde ant'ico. It is faid to have 
 been brought from Egypt to Rome, from 
 which latter place the fpecimens of it now 
 come. 
 
 I, Deep red, with white feltfpat. 
 
 c. Black, \vithwhiteandredfeltfpat. 
 
 d. Reddiih brown, with light red and white 
 feltfpat. 
 
 r. Dark grey, with white grains of ieltfpat 
 alfo. The dark red porphyry has been 
 moft employed for ornaments in building ; 
 yet it is not the only one known by the 
 name of porfido, th*o Italians applying the 
 fame name alfo to the black kind. 
 G. The trapp of the Swedes. Saxum compofitum 
 jafplde martiali wo///, feu argilla martialt indurata. 
 Seethe article TRAPP. 
 
 This kind of (lone fometimes conftitutes or 
 forms whole mountains ; as, for example, the 
 mountain called Hunneberg in the province of 
 Weftergotland, and at Drammen in Norway ; 
 but it is oftener found in form of veins in moun 
 tains of another kind, running commonly in a 
 ferpentine manner, contrary or acrofs to the 
 direction of the rock itfelf. It is not homoge 
 neous, as may be plainly feen at thofe places 
 where it is not preffed clofe together ; but 
 where it is prerfed clofe it feems to be per 
 fectly free from heterogeneoits fubftances. 
 When this kind is very coarfe, it is interfper- 
 
 is found a kind of porphyry of a greenifli colour, with 
 a tinge of brownilh red. It is fmooth, compact, and 
 heavy ; of a clofe uniform texture, but has no bright- 
 nefs when broken. It has angular fpecks ia it of a 
 white quartzy fubflance." 
 
 A a 2 fed 
 
[ 2 7 ] 
 
 fed with feltfpat ; but it is not known if the 
 finer forts likewife contain any of it. Befides 
 this, there are alfo fome fibrous particles in it, 
 and fomething that refembles a calcareous (par ; 
 this, however, does not ferment with acids, 
 but melts as eafy as the ftone itfelf, which be 
 comes a black folid glafs in the fire. By cal 
 cination it becomes red, and yields in aflays 1 2 
 or more per cent, of iron. No other fart of 
 ore is to be found in it, unlefs now and then 
 fomewhat merely fupeificial lies in its fiflures; 
 for this (lone is commonly, even to a great 
 depth in the rock, cracked in acute angles, or 
 in form of large rhomboidal dice. It is em 
 ployed at the glafs houfes, and added to the 
 compofition ot which bottles are made. In 
 the air it decays a little, leaving a powder of a 
 brown colour ; it cracks commonly in the fire, 
 and becomes reddiih brown if made red-hot. It 
 is found, 
 
 1. Of coarfe chaffy particles. 
 
 a. Dark grey. 
 
 b. Black. 
 
 2. Coarfe -grained. 
 
 a. Dark grey. 
 
 b. Reddiih. 
 
 c. Deep brown. 
 
 3. Of fine imperceptible particles. 
 
 a. Black. The touchftone ; Lapis lytKus. 
 
 b. Bluifh. 
 
 c. Grey. 
 
 d. Reddifti. 
 
 The black variety (3. a.) is fometimcs 
 found fo compact and hard, as to take a 
 polifti like the black agate : it melts, how- 
 ever, in th'e fire to a black glafs ; and is, 
 when calcined, attracted by the load-Hone. 
 
 If. Am\-g 
 
C *7> ] 
 
 If. Amygdalo'ides. The carpolithi or fruit-ftone 
 rocks of the Germans. 
 
 It is a martial jafper, in which elliptical ker 
 nels of calcareous fpar and ferpentine itone are 
 included. 
 
 &. Red, with kernels of white limeftone, and 
 of a green fteatites. This is of a particular 
 appearance, and when calcined is attracted' 
 by the loadftone ; it decays pretty much in 
 the air, and has fome affinity with the trapp, 
 and alfo with the porphyry. There are- 
 fometimes found pieces of native copper in 
 this ftone. 
 L The gronjlsn of the Swedes. 
 
 Its bafis is horneblende, interfperfed with 
 mica. It is of a dark green colour, and in 
 Smoland is employed in the iron furnaces as a 
 flux to the bog-ore. 
 
 K. The granite. Saxum compofitum fdtfpata^ mica 
 et qtiartzo, qtibus accidentalitcr intcfdum home- 
 bknde JlsatiteS) granatus et Ixifalies immixti funt. 
 Its principal conftituent parts are felt fpat, or 
 rhombic quartz, mica, and quartz. See the 
 article GRANITE. 
 
 It is found, 
 
 ( i.) Loofe or friable. This is ufed at the Swed- 
 ifh brafs-works to caft the brafs in, and comes 
 from France. 
 (2.) Hard and compact. 
 a. Red. 
 
 i . Fine-grained ; 
 2 Coarfe-grained. 
 I. Grey, with many and various colours (E). 
 
 (E) Mr Wiegleb has analyfed a fpecies of green gra- 
 
 r.ite found in Saxony. The cryftals aie heaped together, 
 
 and form very compact layers; the colour fometimes an. 
 
 A a 3 olive 
 
C 27* ] 
 
 II. Conglutinated fa'xa. 
 
 A* Of larger or broken pieces of ftones of the fame 
 kinds conglutinated together. Breccia. 
 
 olive green, fbmetimes refembling a pear, and fome- 
 times of a reddifh brown : fome of them being per 
 fectly tranfparent, and others nearly fo. According 
 to Mr Warren, they contain 25 per cent, of iron ; 
 whence they have been called green ore of iron. An 
 ounce of thefe cryfbils heated red hot in a crucible loft 
 two grains in weight, and became of the colour of 
 honey. The remainder was put into a retort, and 
 diftilled with marine acid, with which it evidently ef- 
 fervefced. The refiduum was lixiviated with diftilled 
 water, frefh muriatic acid added, and the diftillation 
 and lixiviation repeated. The iron precipitated from 
 this lixivium, and reduced partly to its metallic ftate, 
 weighed two drachms. M. Wiegleb concludes, that 
 the fpecimen contained two drams 26^- grains of lime. 
 From further experiments he concludes, that 100 
 parts of the fubftance contained 36.5 of filiceous earth ; 
 lime 30.8 ; iron 28.7 ; and water and fixed air 4.0. 
 
 Scotland is remarkable for a great number of ex 
 cellent granites, little or nothing inferior to porphyry. 
 Of thefe the following kinds are mentioned by Mr 
 Williams. 
 
 j. The grey granite, or moor-Jlone as it is called in 
 Cornwall, is very common in this country. In fome 
 places it (hows no marks of ftrata ; and in others it is 
 difpofed in thick unwieldly irregular beds, which are 
 commonly broken tranfverfely into huge mafTes or 
 blocks of various fizes and ihapes. There is a great 
 variety in this kind of ftones ; fome of them differing 
 but little in appearance from bafaltes ; others are 
 compofed of aim oil equal parts of black and white 
 grains, about the fize of imall peafe, whence it is 
 ailed feafy whin by the common people. In Gal 
 loway 
 
C 273 ] 
 
 i. Of limeflone cemented by lime. 
 
 0. Calcareous breccia; the marmi brecciati of the 
 Italians. 
 
 loway and other places it frequently has a longitudi 
 nal grain, as if the component parts had been all 
 moved one way by a gentle flow of water. When this 
 kind of granite begins to undergo a fpontaneous de- 
 compofition by expoiure to the atmoiphere, we ob- 
 ferve that it is compofed of pretty Urge grains of the 
 figures of cubes, rhomboids, &c. fome of them fo 
 large as to deferve the name of fragments; and the 
 largeft of thefe are always of quartz or feldfpath, and 
 talc. 
 
 2. Reddifh granite, of a gellied texture, which, 
 Mr Williams fays, is one -of the fineft and rnoft ele 
 gant ftones in the world. The mountains of Bineves, 
 he fays, are principally compofed of this ftone; and 
 it is found in great abundance in many other parts "of 
 Scotland, but he never faw it exhibit any marks of 
 {^ratification. 
 
 3. The fine reddifh granites, in which feveral fine 
 fhades of colours are blended together, not fpread out 
 in tints as in the former. Neither this nor the former 
 are ftratified : " On the contrary (fays our author), 
 both exhibit fuch a degree of uniform regularity, that 
 in fome places there is no difference between a ftone 
 and a mountain, excepting only in magnitude; as 
 many mountains of granite are nothing more than one 
 regularly uniform mafs throughout, in which not the 
 Jeaft mark of a bed is, to be fjeen, nor hardly a crack 
 or fifTure, unlefs it be at the edge of fome precipice or 
 declivity. Thefe two varieties of elegant red granite 
 are met with in the Highlands and Lowlands of Scot 
 land, in Galloway, and many other places. We of 
 ten find malTes of talc fo large in this fecond variety, 
 that fome of them may be called fragments, not dif- 
 
 pofed 
 
C 274 1 
 
 When thefe kinds have fine colours, they 
 are polifhed and employed for ornaments in 
 architecture and other ceconomical ufes. 
 
 pofed in any order, but higgledy-piggledy through 
 the body of the flone. 
 
 4. Stratified reddiih granite, refembling the third in 
 colour and quality, but not always quite fo pure or 
 free from admixture of other ftony matter of a dif 
 ferent quality. This variety frequently contains lar 
 ger and fmaller fragments of fine laminated talc. Mr 
 Williams, however, has feen this kind of granite dif- 
 pofed in pretty regular ftrata in the (hires of Moray 
 and Nairn, and other parts of Scotland. 
 
 5. Granite of a white and whitifh colour, generally 
 of a granulated texture, containing a great quantity 
 of mica, or fmall-leaved talc, and the grains of quartz 
 Ibmetimes large and angular. This variety is fubjecl 
 to fpontaneous decompofition ; part frequently dif- 
 folves and falls into lakes, in fuch an exceedingly fine 
 and attenuated date, that it does not fink in the water. 
 " I have found (fays Mr Williams) this fubftance in 
 many places where water had been accidentally drain 
 ed off, refembling fine (hell marie, only much lighter. 
 When thoroughly dry, it is the lighted foflile fubrtance 
 I ever handled j and, when blanched with rain, it is as 
 \vhite as mow. This variety of granite is either not 
 flratified, or exhibits thick irregular beds. It fre 
 quently contains a considerable quantity of talc, in 
 rnafTes and fcales too large to be called mica." 
 
 Our author is of opinion, that this fine white fub 
 ftance produced from the decompofition of the gra 
 nite, is the true kaolin of the Chinefe, one of the com 
 ponent parts of porcelain ware. " The authors of 
 the Hiftory of China (fays he) informs us, that the 
 fine porcelain ware is compofed of two different foffile 
 fiabftances, called by them pstuntfs and kaolin. We are 
 
 iurther 
 
C *75 ] 
 
 b. The lumachdla of the Italians, or fhell mar 
 bles. Thefe are a compound of fhells and 
 corals, which are petrifisd or changed into 
 
 further told, that the petuatfe is a fine white vitref- 
 clble ftone, compact and ponderous, and of confider 
 able brightnefs in the infide when broken, which they 
 grind to a fine powder; and that the kaolin is not a 
 {tone, but a fine white earthy fubftance, not verifiable, 
 at lead not in the heat of a common potter's fimiace ; 
 that they mix the kaolin and the flour of the petuntfe 
 together, and form a pafte of this mixture, which they 
 mould into all forts of porcelain ve/Tels. Now, frora 
 the beft accouats of this matter which I have been 
 able to obtain, after a good deal of fearc'h and inqui 
 ry, it appears to me, that the fediment which I have 
 mentioned above is the true kaolin; and that as the 
 fine white glafly quartz, which is found in irregular 
 mafTes, and in irregular difcontinuous veins or ribs, 
 in fome of the rocks of fchidus, is the true petuntfe; 
 nd if this obfervation is really true, it deferves to be 
 remarked, that Scotland is as well furmihed with the 
 beft materials for making fine porcelain as moil coun 
 tries in the world. The ipecies of quartz which I fup- 
 pofe to be petuntfe is of a pure fine unih.i m glafly tex 
 ture, femitranfparent, and of a pure fnowy whitenefs. 
 A broken piece of this (tone, and a newly broken 
 piece of fine porcelain, are very like one another. 
 There is a great quantity of petuntfe, or pure white 
 quartz, in many places of Scotland, particularly in 
 the north and Highlands. There is a confiderable 
 quantity of it upon th? fhore and wa'fhed by the tide 
 between Banff and Cullen, generally in pretty large 
 maffes in rocks of bluifh fchidus; and to the befl of 
 my memory it is very fine of the kind. There is alfo 
 a confiderable quantity of it in difcontinous ribs ;md 
 LiafTes, in rocks of blue fchift, about three or four 
 
 miles 
 
C 276 ] 
 
 lime, and conglutinated with a calcareous 
 Jubilance When they have many colours, 
 
 miles north of Callendar in Monteith, upon the fide of 
 the high road which runs parallel to Lochleodunich, 
 which I think alfo very fine. In fome places this fort 
 of quartz is tinged with a rfefh colour from the neigh 
 bourhood of iron, which renders it unfit for porcelain ; 
 but there is plenty to be found of a pure white in al- 
 moft all parts of Scotland, without any mineral tinge 
 whatever. The kaolin is perhaps as plentiful in Scot 
 land as the petuntfe, there being many extenfive lakes 
 eafily drained, which contain a confiderable depth of 
 it ; and moreover, it is to be found in many places 
 that have been lakes, which are now laid dry by ac 
 cident. There is a quantity of kaolin about ico yards 
 below the high road upon the fouth fide of a bridge, 
 about a mile and a half or two miles fouth of the inn 
 of Aviemore in the Highlands. It lies beneath a ftra- 
 tum of peat bog, in a place which has been a lake, 
 but is now drained by the river Spey cutting through 
 one fide of the mound which formed the lake. There 
 is more than one (Iratum of the kaolin in this place, 
 and fome of it is exceedingly white, especially when 
 blanched by the rain ; and there is a white granite rock 
 up the rivulet, at fome diftance above the bridge, the 
 decomposition and dilfolution of which is fuppofed to 
 produce this fine and curious fediment. Several lakes 
 in the Highlands of Scotland are nearly full of kaolin. 
 One of them is fituated in the country of Stratherig in 
 Invernefs-fhire, lefs than a mile north of the public 
 road, and upon the weft fide of the farm of Drimin. 
 It is a pretty long lake, and there is a confiderable 
 depth of kaolin in it, which may be drained at a mo 
 derate expence ; and, if I remember well, the granite 
 rocks which furround it are pretty white and fine. If 
 the kaolin originates from coloured granite, it is good 
 
 for 
 
C 277 ] 
 
 they are called marbles, and employed for the 
 fame purpofes as the preceding * (F). 
 
 for nothing, efpecially if it contains the lead tinge of 
 iron, becaufe this will difcolour and fpoil the beauty 
 of the porcelain ; but wherever white granite is found 
 compofed of quartz, feldfpath, and mica, without any 
 admixture of ihirl, and efpecially iron, the kaolin 
 fhould be diligently fought after in that neighbour 
 hood. Lochdoon, in Galloway, is faid to contain a 
 great quantity of kaolin. It was drained fome years 
 ago on the fuppofition of its containing (hell marie ; 
 but on trying the fubftance contained in it, it was found 
 not to be marie but kaolin. Thefe fubftances may 
 eafily be miftaken for one another at firft ; but they are 
 cafily diftinguiihed by trying them with acids, the marie 
 readily effervefcing with the weakeft, and the kaolia 
 not at all with the ftronge-H: acid liquors." 
 
 6. Grey compofite granite is a very beautiful (lone, 
 and when broken looks as if compofed of fmall frag 
 ments of various fizes and fhapes, not unlike calve' s- 
 head jelly. When polifhed, the fragments appear as 
 if fet or inlaid in a fine pellucid or water coloured mat 
 ter. There is a (ingle (Iratum of very curious com 
 pofite granite, a little to the weft of Loffiemouth, in 
 the county of Moray, in Scotland, of about fix or 
 eight feet thick. It is compofed chiefly of grains and 
 fragments of various bright and elegant colours, moft 
 of which are as large as peafe and beans, all fine, hard, 
 andfemipellucid ; there is about an eighth part of good 
 lead ore in the compofition of this ftone, of the kind 
 commonly called potter's ore ; and it is likewife re 
 markable, that there is no other granite in that neigh 
 bourhood but this fmgle ftratum, all the ftrata above 
 and below it being moftly a coarfe, imperfect, grey 
 fund-done. 
 
 7. Gra- 
 * ?ee note (r) In page 279, 
 
2. Of kernels of jafper cemented by a jafpery fub- 
 ftance. Breccia jafpidea. Dlojpro Irecciato of 
 the Italians. 
 
 7. Granite of a loofe friable texture, fubjecl: to fpon- 
 taneous decompofition, and redu&ion to granite gra 
 vel. There is a remarkable rock of this kind near the 
 Queen's -ferry in Scotland, on the road to Edinburgh, 
 which appears in prodigious thick irregular ftrata. 
 This rock feems to be compofed chiefly of quart/, 
 fhirl, and force iron ; and produces excellent mate 
 rials for the high roads. 
 
 8. In many parts of the north of Scotland, in the 
 Highlands, and in Galloway, there is found an ex 
 cellent fpecies of grey granite, compofed chiefly of red 
 and black coloured grains. This is a fine and very 
 durable ftone, v^ry fit for all kinds of architecture. 
 
 In fpeakmg of thefe ftones, Mr Williams obferves, 
 that the finer and moft elegant red granites, and the 
 fineft granite-like porphyries, fo much refemble one 
 another, that he does not attempt to diftinguifh them ; 
 and Scotland is remarkable for a great number and va 
 riety of them, " The elegant reddiih granite of Bi- 
 neves, near Fort William (fays he), is perhaps the bed 
 and moft beautiful in the world ; and there is enough 
 of it to ferve all the kingdoms on earth, though they 
 were all as fond of granite as ancient Egypt. There 
 are extenfive rocks of red granite upon the fea-fhore 
 to the weft of the ferry of Ballachylifh in Appin, and 
 likewife at -Strontian, as well as many other parts of 
 Argylefhire. I have feen beautiful red granite by the 
 road fide, near Dingwall, and in feveral other parts 
 of the north of Scotland, which had been blown to 
 pieces with gun-powder, and turned off the fields. 
 There are extenfive rocks of reddifti granite about 
 Peterhead and Slains, and both of red and grey gra 
 nite in the neighbourhood of Aberdeen. The hill of 
 3 Cruffel 
 
[ 299 ] 
 
 Of this kind fpecimens from Italy are fccn 
 in collections. A coarfe jafper breccia is faid 
 to be found not far from Frejus in Provence in 
 France. 
 
 Cruffel in Galloway, and feveral lower hills and ex- 
 tenfive rocks in that neighbourhood, are of red and 
 grey granite, where there are great varieties of that 
 Hone, and many of them excellent. Upon the fea ihore 
 near Kinnedore, weft of Loffiemouth, in Moray, there 
 is a bed of ftone about eight feet thick, which I think 
 ihonld be called a compofite granite. It is compofed 
 of large grains, or rather fmall pieces of bright and 
 beautiful ftnnes of many different colours ; and all the 
 ilony parts are exceedingly hard, and fit to receive 
 the higheft polifh. About a fiith or eighth part of it 
 nlfo confifts of lead ore, of that fpecies called potter's 
 ore. The feparate ftony parts compofmg this ftratum 
 are all hard, fine, folid, and capable of the moft bril 
 liant polifh ; and if iolid blocks can be raifed free from 
 all cracks and blemiuhes, I imagine, from the beauty 
 and variety of colours of the ftony part, and the quan 
 tity of bright lead ore which is blended through tha 
 compofition and body of the (lone, that this would be 
 u very curious and beautiful ftone when polifhed.'' 
 
 (F) The ftones called Lur/i Belmontii or Paracelji, 
 have fome fimilarity in their form to the breccia, a. b. : 
 for they are compofed of various lumps of a maily 
 whitifti-brown matter, feparatcd into a great number 
 of polygonous compartment?, of various fixes, formed 
 of a whitifh -yellow cruft of a red calcareous fpar, 
 fnmetimes pyritous, which often rife a little above the 
 external furface, and inclofe each of them on the in- 
 fide. According to Bomare, the ludvt Jtel/atui Lclmon- 
 tii, found in the county of Kent, is covered with a 
 kind of ftriated felenite refembling the zeolite. They 
 are for the moft part of a globcfe figure, feldom fl.it, 
 B b but 
 
3- Of filiceous pebbles, cemented by a jafpery 
 fubftance, or ibmething like it. The plum- 
 pudding ftone of the Englifh ; Breccia Jilicea. 
 Its bafis, which at the fame time is the ce 
 ment, is yellow; wherein are contained fmgle 
 flinty cr ag*ty pebbles, cf a grey colour or 
 variegated. This is of a very elegant appear 
 ance when cut and polifhed : it is found in 
 England and Scotland (G). 
 
 but often convex on the outfide; and fornetimes with 
 a concave furface. 
 
 According to Wallerius, the Indus helmontii lofes by 
 calcination about half of its weight ; and, on being 
 urged by fire, is melted into a black glaffy flag. It 
 effervefces (Irongly with aqua-fortis, and this folution 
 is of a yellow colour. But what feems very extra 
 ordinary, by adding to it fome oil of tartar per ddi- 
 quium, bubbles are produced, from which a great num 
 ber of flender black threads or filaments are produced, 
 flicking like a cobweb to the fides and bottom of the 
 veffel. 
 
 Thefe (tones are found quite feparate by themfelves, 
 as well as various ft.ilagmites and cruftaceous bodies, 
 on the ftrata of argillaceous earth, in various parts 
 of Europe, chiefly in Lorrain, Italy, England (in the 
 counties of Middlefex and Kent), and elfewhere. 
 
 Wallerius ranges the Indus helmontn among the tophi, 
 in the Spec. 425. of his fy ft em of Mineralogy. Para- 
 celfus had attributed to thefe ftones a lithontriptic 
 power, tind Dr Grew fays that tkey are diuretic; but 
 there is not the leail proof of their ^really poficffing 
 fuch qualities. 
 
 (G) The breccia ftratum, or plumbpudding-rock, 
 exhibits a (ingular appearance as it lies in the ground ; 
 being compoied of water-rounded ftones of nil quali 
 ties and of all fizes, from fmall gravel up to large 
 
 rouudsd 
 
4. Of quartzofe kernels combined with an un 
 known cement. Breccia quartzvfi. 
 
 5. Of kernels of feveral different kinds of flones. 
 Breccia faxofa . 
 
 rounded (tones of feveral hundreds weight each ; the 
 interfaces being filled up with lime and fund. It fre 
 quently alib contains lime and iron. Sometimes it ex 
 hibits a grotefque and formidable appearance ; con 
 taining many large bullets of various fizes and fhape<, 
 without any marks of regular {^ratification, but look. 
 ing like one vaft mafs of bullets of unequal thicknefs ; 
 and in this manner frequently fwelled to the fize of a 
 confiderable mountain. It is frequently cemented 
 very ftrongly together ; fo that parts of the hills com- 
 pofed of it will frequently overhang in dreadful pre 
 cipices, lefs apt to break off than other rocks in the 
 fame (ituation ; one reafon, for which, befides the 
 ftrength of the cement, is, that the breccia, when 
 compofed of bullsts, is lefs fubjecl to fiflures and cut 
 ters than other rocks; being frequently found in one 
 folid mafs of great extent and thicknefs. Some of 
 the plumpudding-rocks are made up of fmallsr parts, 
 coming near to the fize of coarfe gravel. It is evident 
 however, that all the parts of the breccia, whether 
 coarfe or fine, have been rounded by agitation in wa 
 ter, as the rocks differ nothing in appearance from the 
 coarfer and finer gravel found upon the beach of the 
 fea, excepting only that the parts are ftrongly cement 
 ed together in the rocks, and are loofe upon the 
 fhores of the ocean. 
 
 Some of the breccia is compofed of finely rounded 
 (tones of various and beautiful colours, about the fr/.e 
 of plums or nuts, all very hard and fine. Were this 
 fpecies fawed and poliflied, it would appear as beauti 
 ful and elegant as any ftone in Europe ; much refem- 
 bling mofaic work in fmall patterns. 
 
 B b 2. la 
 
C 302 ] 
 
 Of kernels of porphyry, cemented by a por 
 phyry or coarie jafpery fubftance; Bteccia 
 porphyrea. 
 
 In general, the breccia is regularly ftratified or not 
 according to the fize of the component parts of the 
 itone. Such rocks as are compofed of round gravel 
 and fmall bullets are generally very regular in their 
 iUtificatien, while thofe which contain bullets fome- 
 what larger in fize are commonly difpofed in thick 
 and coarie beds, and fuch rocks as are made up of 
 the largeft kind of bullets feldom (how any marks of 
 jft ratification at all. 
 
 Among many other places in Scotland, where brec 
 cia or pudding-ftone abounds, there are extenfive rocks 
 and high cliffs cf it upon the fouth (hore at the weft 
 end of the'Pentland Frith, to the weft ward of Thurib 
 in Caithnefs, which ftretch quite acrofs the county of 
 Caithness into Sutherland ; and in Sutherland as well 
 as Caithnefs, this reck is of a rough contexture, and 
 appears in pretty high hills, deep glens, overhanging 
 rocks, and frightful precipices, to the weft of Brcra, 
 Dunrcbin, and Dornoch, which gives it a grotefque 
 and formidable appearance in that country. This 
 range of breccia ftretches alfo quite through Suther 
 land, and likewife through Rofsfhire, the weft fide cf 
 Ferndonald, and Ding wall, where it exhibits the very 
 iame phenomena as in Sutherland and in Caithnefs. 
 It continues the fame longitudinal line of bearing, 
 which is nearly from north-eaft to fcuth-weft, quite 
 through the highland countries of Invernefs and Perth- 
 ihire; and it forms confiderable hills, and very high 
 and rugged rocks, upon both fides of that beautiful 
 piece of frefh water Lochnefs. Much of the ftone here 
 as well as in other places in this range, is compofed of 
 large bullets ; the rock is, very hard and ftrong, and 
 \t hangs in frighthful precipices upon both fides of the 
 
 lake 
 
b. Of kernels of feveral faxa; Breccia indeter 
 minate. 
 
 c. Of conglutinated kernels of fandftone ; Brec 
 cia arenacea. This kind confiits of fandltone 
 kernels, which have been combined a fecorid 
 time together. 
 
 The abovementioned breccue of themfelves mud 
 demand the diilinctions here made between, 
 but which perhaps may fcem to be carried too 
 far, fmce their particles are fo big and plain 
 as to be eafily known from one another. Thefe 
 Hones are a proof both of die fubverfions 
 which the mountains in many centuries have 
 undergone, and of fome hidden means which 
 nature makes ufe of in thus cementing diffe 
 rent kinds of ftones together. Any certain 
 bignefs for the kernels or lumps in fuch com 
 pounds, before they deferve the name of breccia? 
 cannot be determined, becaufe that depends 
 on a comparifon which every one is at liberty 
 to imagine. In fome places, the kernels of 
 porphyry have a diameter, of fix feet, while in 
 
 lake, through which rock General Wade cut a fine mi 
 litary road upon the fouth fide of the lake, at a great 
 expence of time, labour, and gun-powder. Thefe rocks 
 are leen ftretching through the mountains of Stratherig 
 into Badenoch, where it forms a remarkable rock and 
 precipice called Craigdow or the Black Rock. The 
 lame range is again feen farther towards the fouth- 
 weft, in feveral places to the fouth of the Black Mount, 
 and in the country of Gienoichy in Argyleihire : and 
 Mr Williams fuppofes, that the longitudinal line of 
 this rock, fp far as it has been juft pointed out, is 
 little lefs than 200 miles, and in fome places it fpreads 
 eight or ten miles in what may be. called the latitudinal 
 line acrofs the bearing of the rocks. 
 B b 3 
 
C 304 ] 
 
 citicrs they are no bigger than walnuts. Some 
 times they have a . prp.greffive fiz6 down to 
 that of a find frrdfcone. Mult of this kind of 
 ftcne is fit for ornaments, though the work- 
 manihip is very difficult ar.d coftly. 
 JS. Conglutinated ftones of granules or fands of dif 
 ferent kinds. Sandftone; Lapis arenaceus. 
 
 In this divifion are reckoned thofe which confift 
 of fuch minute particles, that all of them cannot 
 eafily be difcovered by the naked eye. The great- 
 eft part, however, confift of quartz and mica; 
 which fubftances are the moft fit to be granulated, 
 withput being brought to a powder. 
 
 1. Cemented by clay. 
 
 a. With an apyrous or refractory clay. This 
 is of a loofe texture; but hardens, and is very 
 refractory in the fire. 
 
 b. With common clay. 
 
 2. With lime ; refembles mortar made with coarfe. 
 fand. 
 
 a. Confiding of tranfparent and greenifli grains 
 
 of quart'/ and white limeftone. 
 # Of no vifible particles. This is of a leofe 
 
 texture, and hardens in the air. 
 
 3. With an unknown cement. 
 a. Loofe. 
 
 I'.. Harder. 
 
 c. Compact. 
 
 d. Very hard. 
 
 4. Cemented by the ruft or ochre of iron, is 
 found in form of loofe ftones at feveral places, 
 and ought perhaps to be reckoned among the 
 miner a arenacea or fand ores; at leaft when the 
 martial ochre makes any confiderable portion 
 of the whole. 
 
 5-, Giit-ftone. This is of greater orlefs hardnefs, 
 moftly of a grey, and fometimesof a yellowifli 
 colour; contpofed of a filiceous and micaceous 
 
 fand 
 
[ 35- 3 
 
 fand, and rarely of a fparry Knd, with greater 
 or lefler particles clofely compacted arid united 
 by an argillaceous cement. I 1 " .* ; -. ibme 
 fparks with flee), is mdilToiuble i\ r ,': . . ruoft 
 part in acids, and vitrifiab?.: in a ilrong fire. 
 It is uicd for iT.iililones and whetftcnes, fome- 
 times for filtering ftones and for building. Fa- 
 Irom. 
 
 N. B. The argillaceous girt has been before 
 defcribed, p. 89. col. i. 
 
 6. Elatlic. A fmgular fpecies of fandftone, of 
 which a fpecimen was iliown fome years ago to 
 the Royal Academy of Sciences at Paris by the 
 Baron de Dietrich. It is flexible and elaftic; 
 and confifts of fmall grains of hard quartz, that 
 ftrike fire with tempered fteel, together with 
 fome micaceous mixture. The elafticity feems 
 to depend on the micaceous part, and foftnefs 
 of the natural gluten between both. It is faid, 
 that this elaftic ftoae was found in Brazil, and 
 brought to Germany by his excellency the 
 Marquis de Lavradio. 
 
 There are alfo two tables of white marble, 
 kept in the palace Borghefe at Rome, which 
 have the fame property, But the fparry par 
 ticles of their fubitance, though tranfpa:rent, 
 are rather foft; may be eafily feparated with 
 the nail, and effervefce with aqua-fortis; and 
 there is alfo in it a little mixture of fmall par 
 ticles of talc or mica. Se Journ. de Phyf. 
 for Ocl 1784, p. 275. See alfo the article 
 MARBLE (Elaftic.) 
 
 C. Stones and ores cemented together; Mine ra are- 
 nacex. 
 I. Of larger fragments. 
 
 a. Mountain green, or utricle montanum cupri r 
 and pebbles cemented together, from Sibe 
 ria^ 
 
 b. Potter* 
 
C 
 
 1. Potters lead-ore, with limeftone, Hate-ker 
 
 nels, and (hells. 
 c. Yellow or marcafitical copper ore, with fmali 
 
 pebbles. 
 2. Of fmaller pieces. 
 
 a. Potter's lead-ore with a qua* tzofe fand. 
 
 b. Mountain green with fand from Siberia, 
 
 c. Cobalt ore with fand. 
 
 d. Martial ochre with fand. 
 
 Order II. MINERAL CHANGES, or PETRIFACTIONS. 
 
 THESE are mineral bodies in the form of animals or 
 Vegetables, and for this reafon no others belong to 
 this order than fuch as have been really changed from 
 the fubjefts of the other two kingdoms of nature. 
 I. Earthy changes; "Terra tarvattz- 
 
 A. Extraneous bodies changed into a lime fubftance, 
 or calcareous changes; Larv< ca'carca. 
 (i.) Loofe or friable. Chalky changes; Crete 
 
 a. In form of vegetables. 
 
 b. In. form of animals. 
 
 i. Calcined or mouldered fliells ; Humus con- 
 
 cbaceus. 
 (2.) Indurated ; Petrifafta cakarea. 
 
 a. Changed and rilled with folid limeftome. 
 
 1. In form of animals. 
 
 2. In form of vegetables. 
 
 1. Changed into a calcareous fpar; PetrifaSa 
 
 calcarea fpatofa. 
 ,:. i . In form of animals. 
 
 2. In form of vegetables. 
 
 . Extraneous bodies changed into a flinty fubftance. 
 Siliceous changes; Larvae Jillcca. Thefe are, 
 like the flint, 
 (i) Indurated. 
 
 a- Changed into flints. 
 
 r. Car- 
 
C S7'- 1 
 
 1 , Carnelians in form of fhells, from the 
 river Tomm in Siberia. 
 
 2. A gat in" form of wood. Such a piece is 
 faid to be in the collection of Count 
 Teffin. 
 
 3.^Gorai!oids of white flint, ( Millepora. ) 
 4. Wood of yellow flint. 
 
 C. Extraneous bodies changed into clay. Argillil* 
 ceous changes; Larvtf argttiaet** 
 
 A. Loofe and friable. 
 i. Of porcelain clay. 
 
 a. In form of vegetables, 
 
 A piece of white porcelain clay from Ja 
 pan, with all the marks of the root of a 
 tree, has been obferved in a certain collec 
 tion. 
 
 B. Indurated, 
 
 l. In an unknown clay. 
 a. In form of vegetables. OJkocoHa. It is 
 faid to be changed roots of the poplar 
 tree, and not to confift of any calcareous 
 fubftance. 
 
 A fort of foffile ivory is faid to be 
 found, which has the properties of a 
 clay ; but it is doubtful if it has been right 
 ly examined. 
 
 II . Saline extraneous bodies, or fuch as are penetrated 
 by mineral falts. Corpora pet egnna infallta. Larva 
 tnjalitte. 
 A. With the vitriol of iron. 
 
 1. Animals. 
 
 a. Human bodies have been twice found in 
 the mine at Falun in Dalarne j the laft 
 was kept a good many years in a glafs-cafe, 
 but began at laft to moulder and fill to 
 pieces. 
 
 2. Vegetables. 
 a. Turf, an-4 
 
 . Roots 
 
I 308 J 
 
 i>. Roots of trees. 
 
 Th-.;fe are found in water ftrong'y im 
 pregnated with vitriol. They do not burn 
 \vith a flame, but only like coal in a ilrcn.ij 
 fire; neither do they decay in the air. 
 
 III. Extraneous bodies penetrated by mineral inflam 
 mable fubftances, or mineral phlogftion. 
 
 d. Penetrated by the fubftance of pit-coals. 
 
 j. Vegetables, which commonly have Bea-n woods, 
 or appertaining to them. 
 a. Fully faturated. Gages, Jet. (See p. 104. 
 col. 2.) The jet is of a folid fhining texture. 
 1. Not perfectly faturated; Mumia vtgttaliiis. 
 It is loofej refembles umber, and may ufed 
 as fuch. 
 
 J5. Penetrated by rock-oil or afphaltuxn. 
 i. Vegetables. 
 a. Turf. 
 
 The Egyptian mummies cannot have any 
 
 place here, fvnce art alone is the occauort 
 
 that thofe human bodies have in length of 
 
 time been penetrated by the afphaltum, in 
 
 the fame manner as has happened naturally 
 
 to the wood in pit coal ftrata. See Mu M M v. 
 
 C. Penetrated by fulphur which has diflblved iron, 
 
 or by marcafite and pyrites. Pyrite impregnata. 
 
 Petrifatla pyritacta. 
 
 i. Animals. 
 
 a. Human. 
 
 b. Bivalves. 
 
 c. Univalves, 
 
 d. Infecls. 
 
 IV. Metals inform of extraneous bodies i Larva me - 
 talUferrt. 
 
 A. Silver; Larva argentlfer<s . 
 (i.) Native. 
 
 a. On the furfaces of fliells. 
 (2.) Mineralifed with copper and fulphur. 
 
 a. Fahlertz, 
 
a. Fahlertz, or grey filver ore in form of ears 
 of corn, &c. and fuppofed to be vegetables, 
 are found in argillaceous Hate at Franken- 
 berg and Tahlitceren in HefTe. 
 JR. Copper; Larva cupriferx. 
 (i.) Copper in form of calx. 
 
 a. In form of animals, or of parts belonging to 
 them. 
 
 i. Ivory and other bones of the elephant. 
 The Turcois or Turquoife ; which is of 
 a bluiih green colour, and much valued 
 in the ea(t. 
 
 At Simore in Languedoc bones of ani 
 mals are dug, which during the calcina 
 tion afmme a blue colour; but it is not 
 probable that the blue colour is owing to 
 copper. 
 
 (2.) Mineraiifed copper, which impregnates ex 
 traneous bodies; Cuprum miner a 'if alum corpora 
 peregf'ina ingreflimi* 
 
 A. With fulphur and iron. The yellow or 
 marcafittcal copper ore that impregnates. 
 i. Animals. 
 a. Shells. 
 I. In form of fifn. 
 
 i. With fulphur and filver. Grey filver ore 
 orfahlerts, like ears of corn, from the flate- 
 quaries in Heffe. 
 C. Changes into iron; Larva ferriftrx. 
 
 (i.) Iron in foim cf calx, which has aflumed 
 the place or the lhape of extraneous bodies; 
 Ferrum calciforme corpora peregrina IngreJJinn. 
 a. Loofe ; JLarve ocLracete. 
 i. Of vegetables. 
 
 Roots of trees, from the lake Langelma 
 in Finland. See the afts of the Swediih 
 Academy of Sciences for the year 1742. 
 
 b. Indu 
 
I. Indurated; Larvx h<tnatitic<e . 
 
 i. Of vegetables. 
 
 (2.) Iron mineralifed, aiTuming the fliape of ex 
 traneous bodies. 
 
 a. Mineralifed with fulphur. Marcaflte. .Lrtr- 
 va pyritacce. 
 
 V. Extraneous bodies decompofing, or in a way of 
 deftru&ion; Corpora percgrina in gradibus deftruc- 
 twnis conjiderata. Mould; Humus. Turf; Turba. 
 4* From animals. Animal-mould; Humus animatis. 
 
 1. Shells. Humus concbaceus. 
 
 2. Mould of other animals; Humus diver/orum 
 animalium. 
 
 JB. Vegetable mould ; Humus vegetabllis. 
 
 1. Turf; Turla. 
 
 u. Solid, arid hardening in the air; Turbafolida 
 aereindurefcens. This is the bed of the kind 
 to be ufed for fuel, and comes neareft to the 
 pit-coals. It often contains a little of the 
 vitriolic acid. 
 
 b. Lamelated turf; Turla foliata. This is in 
 the firil degree of deftru<ftion. 
 
 2. Mould of lakes; Humns lacuftrls. This is a 
 black mould which is edulcorated by water. 
 
 3. Black mould; Humus dter. This is univerfally 
 known, and covers the furface of that loofe 
 earth in which vegetables thrive beft. 
 
 Order III. VOLCANIC PRODUCTS (H) 
 
 I. SLAGS; Scoria vulcanonim. 
 
 Slags are found in great abundance in many places 
 of the world, not only where volcanoes yet exift, 
 
 (H) For the nature, hiftnry, theory, &c. of volca 
 noes, fee the article VOLCANO. 
 
 but 
 2 
 
but likewise where no fabterraneons fire is now 
 known: Yet, in Mr Cronftedt's opinion, they 
 cannot be produced but by means of fire. Thefe 
 are not properly to be called natural* iince they 
 have marks of violence, and of the laft change 
 that mineral bodies can fuffer without the cie- 
 ftrucYion of the world: nor are : they artificial, ac 
 cording to the univerfally received meaning of 
 this word. We cannot, however, avoid giving 
 them a place here, efpecially after having ad 
 mitted the petrifactions ; and (hall therefore ar 
 range the principal of them, according to their 
 external marks. 
 
 A. Iceland. agate; Achates ijlundicus ntger. 
 
 It is black, folid, and of a glafly texture; but in 
 thin pieces it is greenifh and femitranfparent 
 like glafs-bottles, which contain much iron. 
 The mod remarkable circumftance ?s, that fuch 
 large folid mafles are found of it, that there is 
 no poffibility of producing the like in any glafs- 
 houfe. 
 
 It is found in Iceland, and in the ifland of A- 
 fcenfion: The jewellers employ it as an agate, 
 though it is too foft to reiift wear. 
 
 B. Rheniih millftone; Lapis molaris Rhenanus. 
 
 Is blackilh-grey, porous, and perfectly refembles 
 a fort of flag produced by mount Vefuvius. A 
 variety of lava, according to Kirwan. 
 
 C. Pumice-ftcne; Pumex. 
 
 It is very porous and bliilered, in confequence 
 of which it is fpecifically very 1'ght. It re 
 fembles that frothy flag which is produced in 
 the iron furnaces. 
 
 1. White. 
 
 2. Black. 
 
 The colour of the firfc is perhaps faded or 
 
 bleached, becaufe the fecond kind comes in 
 
 C c tljat 
 
C 3" 3 
 
 that ftate from the laboratory itfeTf, viz. the 
 . volcanoes. 
 Pearl flag; Scoria ec-vjlantes glolulis vitreis con- 
 
 glomeratls. 
 
 It is compounded of white and greenilh glafs 
 
 particles, which feem to have been congluti- 
 
 nated while yet foft or in fufion. Found on 
 
 the Ifle of Aicenfion. 
 
 . Sla^-fand or aihes; Scoria fuherulente, clneres 
 
 This is thrown out from volcanoes in form of 
 larger or fmaller grains. It may perhaps be 
 the principle of the Terra Puzzolana; becaufe 
 fiich an earth is faid at this time to cover the 
 ruins of Herculaneum near Naples, which hi- 
 ftory informs us was deftroyed by a volcano 
 during an earthquake 
 II. Lavas. 
 
 JLava has been generally underftood to denote the 
 aggregate xnafs of melted matters which flow 
 out of the mouths, or burft out from the fides, 
 of burning mountains. According to Mr Kir- 
 wan, however, lavas are the immediate produce 
 of liquefaction or vitrification by the volcanic 
 fires, and " fiiould carefully be diftinguifhed 
 from the fubfequent productions affected by the 
 water either m a liquid or fluid ftate, which ge 
 nerally is ejected at the fame time." Ar ; d of 
 lavas, fo diftinguilhed, he defcribes feveral va 
 rieties. See the article LAVA, in the order of 
 the alphabet; where the nature, origin, kinds, 
 and phenomena of lavas, are copioufly defcribed 
 and explained. 
 ill. Eafaltes. 
 
 This ion of ftone was by Cronftedt, in the firft 
 edition of his Mineralogy, ranked among the 
 garnet earths, and confounded with the ftioerls; 
 
 an 
 
[ 3-3 3 
 
 aft impropriety which was pointed out by BLT^ 
 man in his Sciagraphta, feel. 120. Mr Kinvaa 
 conliders bafaltes as an imperfect lava, and 
 afcribes its origin both to fire and water. He 
 defcribes it as found, either, I. In opaque tri. 
 angular or polyangular columns^ which ii the 
 proper bafaltes: Or, 2. In amorphous maffes 
 of different magnitudes; forming folid blocks, 
 from the fmalleic fize to that of" whole mountains: 
 which kind is called trapp. See the detached 
 article BASALTES (i); where its fpecies and va 
 rieties are particularly defcribed, and different 
 opinions dated concerning its formation. See 
 alfo the article TRAP?. Some plaufible argu 
 ments again-ft the volcanic origin of bafaltes will 
 be mentioned in the courfe of "the fubjoined_nojte 
 (K), extracted from WiUlamfj Natural Hrj$ory -of 
 the Mineral Kingdom. 
 
 (i ) In that article, p, 46. col. i . 1. 9. dele the words, 
 " The Englifh miners call it cockle, the German/'/W/," 
 P. 47. col. 2. 1. 28. for " a. kind of marble," read 
 ** a volcanic produflion." The'Lapb Lydius t or Touch- 
 done, mentioned in the fame paragraph, fliould have 
 bew'n fpecified to be of the fort called Trafip. 
 
 (K) There is a great variety of bafaltes in Scotland, 
 particularly of the grey kinds; forne of which are ca 
 pable of the higheft degree of polilh. - A good black 
 kind is met with on the fouth fide of Arthur's Seat 
 near Edinburgh, where it forms a fmooth perpendi 
 cular rock, with feveral of the columns broken oft, 
 and the fufpended pieces threatening to full down up 
 on- -the paflengers below. This ftone, is capable of 
 receiving a fine poliih ; and, in the opinion of Mr Wil- 
 liam^/Avbtrld be fit for-all forts'of ornaments -about 
 fepwlchral monument!-. It will polifh to a bright and 
 beautiful black which will be unfading. 
 
 C c 2 ' There 
 
There is another kind, heavy and hard, of a black, 
 or blackifti-grey colour ; of which great quantities have 
 keen carried from the Frith of Forth to pave the ftreets 
 <of London. This, for the moft part, is coarfely gra 
 nulated in the infide, though fometimes the grain is 
 pretty fine. Sometimes it is bright in the infide when 
 broken. It is compofed of grains of quartz and ihirl 
 of different fizes, and commonly contains fome iron. 
 It always appears in thick, irregular, beds, fome of 
 which are enorrnoully thick; and feldom or never 
 equally fo : on the contrary, where it is found upper- 
 moil, it frequently fwells into little hills of various 
 iizes. Molt of the fmall iflands in the Frith of Forth 
 are compofed of this kind of ftone ; as well as fome 
 hills in the neighbourhood of InverkeithiBg and of 
 Edinburgh. 
 
 The known characterise of the bafaltes is to form 
 itfelf into balls, columns, and other regular figures. 
 The columnar kind affumes a pentagonal, hexagonal 
 or heptagonal figure ; but quadrangular columns are 
 net common. They are all fmooth o the outfide, arid 
 lie parallel and contiguous to one another ; fometimes 
 perpendicular, fometimes inclining, in proportion to 
 the pofition of the flratum which is thus divided: If 
 the (Iraturn lies horizontal, the columns are perpen 
 dicular ; if inclining," the pillars alfo incline in exaft 
 proportion to the declivity of the Ilrata, being ahvays 
 broken right acrofs the (tralum. Some are of one piece 
 from top to' bottom ; others divided by one or more 
 joints laid upon one another, which form a column 
 cf feveral parts. The reck called the Giant's Cavfeway 
 in Ireland is a pretty good fpeciirien of the jointed co 
 lumnar bafaltes : but there is a more beautiful fpecies 
 above Hilihoufe lime-quarry, about a mile fout.h of 
 Linlithgow in Scotland; and a coarier one near the 
 toll-bar north fide of Queen's Ferry, and feveral 
 other places in Fife. la fome places the bafaltes are 
 
 formed 
 
E S'5 I 
 
 iormed inio magnificent columns of great length ; and 
 in others afford an afiemblage of {mall and beautiful 
 pillars refembling a range of balluftrades or organ 
 pipes. Some of the columns on the fouth fide of Ar 
 thur's Seat already mentioned are very long ; and 
 there are likewife magnificent columns of great length 
 in the ifland of Egg, and others of the Hebrides. 
 Thefe columns, when broken, are frequently of a 
 black, or blackifa grey, in the infide ; fame ot them 
 being compofed of fmall grains, which gives them an 
 uniform and fmooth texture ; but much of this fpecies 
 of llone has larger grains in its compofition, rough, 
 lliarp, and unequal, when broken. All the grains, 
 houever, are fine, hard, and bright; and the ftone 
 >n general is capable of a fine polifh. 
 
 The other fpecies of bafaltes which forms itfelf in 
 to diftinct malTes, aulimes fometimes a quadrangular, 
 fomatimes an oval* globular, or indetermiaate figure. 
 They are found of all (izes from the frze of an egg 
 to that of an houfe : but though they differ in fhape 
 from the columnar bafaltes, they agree in almoft 
 every other refpect ; whence Mr Williams thinks that 
 they are only to be accounted a variety of the co 
 lumnar kind. It is common to fee one ftratum of 
 the bafaltine rocks exhibiting, in one place, regular- 
 pillars or globes ; and near thefe, very irregular ones, 
 differing very little from the common cutters found 
 in all rocks ; and at no great diftance, the fame rock 
 is found to run into one entire mafs, exhibiting no 
 tendency to be broken or divided into any columns 
 whatever, Of this the rock of Arthur's Seat is an 
 inftance. Some of thefe or>ly produce folid mafies of 
 different figures and fixes ; while others produce 
 quantities of a fofter, friable, ftony matter, of the 
 fame quality in which the hard ma/Tes of different 
 figures are found imbedded. Pretty good fpecimens 
 of the fecond kind or variety of bafaltes are met with 
 C c 3 on 
 
on the road-fide between Cramo-nd bridge and the 
 Queen's Ferry, and in feveral other places in the 
 LtOthians and in Fife. 
 
 The cruftated bafaltes are of two kinds ; r. Such as 
 have the crufts more dry and friable than the internal 
 parts ; and, 2. Such as are dry and friable throughout 
 the whole rnafs. 
 
 The firft of thefe has not only a cruft of the fria 
 ble matter adhering to it, but is likewife imbedded 
 in a quantity of the fame. Our author has feen ma 
 ny quarries of this kind of bafaltes dug tor the high 
 roads, in which the quantity of foft friable matter 
 greatly exceeded that of the hard matfes, and in 
 which incrufted ftones of various fizes and (hapes ap 
 peared. In fuch quarries, fome of the largeft mattes 
 have only a few coats of penetrable friable matter, 
 1 unrounding a nucleus which varies in fize, but is 
 uniformly hard throughout ; and we ihall find other 
 yolks in the fame quarry imbedded in the fofter mat 
 ter, which, when broken, exhibit a neft of (tones in 
 cluding one another like the feveral coats of an onion. 
 Thefe cruftated ba&ltes which envelope one another 
 are a curious fpecies of ftone. The feveral coats of 
 furronnding matter differ nothing in quality from the 
 ftones contained in them, and fome of the inner crufts 
 are often very hard ; but the nucleus within, though 
 fmall, is always the hardeft. The decompofition by 
 the weathering f the fofter matter found fnrround- 
 ing and enveloping tlae harder rnaifes of ftone in this 
 and the fecond fpecies of bafaltine rocks, has pro 
 duced a phenomenon frequently met with in Great 
 Britain, especially in Scotland, which greatly puzzles 
 many. It is very common in low grounds, and upon 
 fome moderate eminences, to fee a prodigious multi 
 tude of ftones of all fhapes and fizes, very hard, and 
 pretty fmooth on the outfide. Thefe ftones are fome- 
 fo numerous and large, that it is often found 
 
 imprao 
 
r 3*7 
 
 impracticable to clear a field of them. Where tKofe 
 (tones are a fpecies of bafaltes, which they commonly 
 are, and of the fecond i'pecies of bafaltes defefibed 
 above, they always originate from a decompoiiti.'n 
 of the more foft or friable parts of thofe rocks, which 
 moulder or fall away, and leave the harder (tones de 
 tached and fcattered about, and the decompofed mat 
 ter dilTolves by degrees, and becomes good corn mould. 
 Here Mr Williams takes occaiion to conteit the 
 opinion of thofe who think that (tones grow or vege 
 tate like plaots. He owns indeed th^t they increase 
 in bulk : but this, he fays, is only in fuch fituations 
 as are favourable for an accretion of matter carried 
 down and depoiited by the water ; in all other fitua 
 tions they grow lefs and lefs. " Others (fays he) ima 
 gine, that thefe (tones (on which this extraneous mat 
 ter has been depofited) were rolled about ; that the 
 afperites and fharp angles were by that means worn 
 off; and that they were all at laft depofited as we fee 
 them, by the waters of the univerial deluge : and, 
 having their obtule fides and angles, as if they had 
 been rounded by rolling in wa:er, makes thefe gentle 
 men confident that they are right ; and if we did not 
 frequently find (tones exactly of the fame figure, fize, 
 and quality in the rock, it would be very difficult to' 
 overthrow this hypo-thefts. I have taken great pains 
 to inveftigate this point, having frequently examine^ 
 circumftances ; and never failed to difcover the ftra- 
 tum of rock which thofe detached (tones originally be 
 longed to. " The ftrata or beds of the feveral fpectes 
 of bafaltes f-read as wide, and (tretch as far, as the 
 ovher concomitant (trata in the neighbourhood where 
 they are found : but they often lie very flat, or with a- 
 moderate degree of declivity ; and consequently, when 
 the fofter and more friable matter found in the inter- 
 itices of thefe rocks, which inclofes and binds the har 
 der rnaffes in their Dative beds, is decompofed, the 
 
 harder 
 
E 
 
 harder ftones mud then lie fcattered wide upon the 
 face of the ground." 
 
 The fecond fpecies of the cruftated bafaltes, viz. 
 that which is dry and friable throughout the whole 
 inafs, is generally .;f a coarfe and granulated texture, 
 and of ail the various (hades of grey colours ; from 
 a rufty black to a light-coloured grey. This kind of 
 crurtated bafaltes is developed when the maffes are 
 either broken or in a ftate of decompofition ; and there 
 are maffes of it of all fizes and (hapes found in the 
 rocks, refembling the fecond and third fpecies of the 
 bafaltes ; appearing alike fmcoth on the outfide, with 
 obtuie angles ; in fhort, refembling the bafaltes in 
 every refpect : but when they are expofed to the ex 
 ternal air and weather for any confiderable time, the 
 feveral incruftations decay, decompofe, and crumble 
 down by degrees. When they quarry this fpecies of 
 bafaltes for the roads, they are able to break and pound 
 them fmall with eafe ; but the harder fptcies are fo 
 hard and cchefive, that they, are with the greateft dif 
 ficulty broken into fufficiently fmall parts, 
 
 Compofite bafaltes refembles the three laft fpecies, 
 in figure, colour, and all other external appearances ; 
 being diftinguifhable from them only in the internal 
 ftructure or grain of the (lone. It refembles fome of 
 the granites, as confiding of much larger grains than 
 the other bafaltes. Many of the larger grains in the 
 compofite bafaltes are more than an eighth part of an 
 inch over, and fome more than a fourth ; appearing 
 with fmooth flat furfaces, and of a tabulated texture, 
 exactly refembling the quartzy grains fo commonly 
 found in the compofition of rnoft of the granites. The 
 chief, if not the only, diftinguifhable difference be 
 tween the grains in each of them is the colour. They 
 are evidently large grains of quartz, &.c. which exhibit 
 flat filling furfaces in both. Thofe grains or frag 
 ments are coznmonly white, yellowift, red, or black, 
 2 in 
 
in the compofitiqn of mod .of the granites ; whereas 
 they are often feen of a pale blue, or a bluilh grey 
 colour, in the composite bafaltes, and fome of them 
 approaching to white. It is only in the internal ftruc- 
 ture, however, that thefe bafaltes have any refem- 
 blances to the granites ; in all the external characters, 
 they differ nothing from the reft of their own genus. 
 
 A fifth fpecies of bafaltes is indurated through the 
 xvhole ftra.turn,folid and uniform through all its parts, 
 and exhibiting only fuch cracks and fiflures or cutters 
 as are commonly met with in other hard beds of ilones. 
 Many beds of this fpecies are frequently met with in 
 the coal-fields, and the miners are often obliged to 
 fink through them in their coal-pits. " The Salii- 
 bury craig's at Edinburgh (fays our author) might 
 be fingled out as a good example of this fpecies of 
 ftone, were it not that part of the fame ftratum is 
 formed into columns on Arthur's feat ; though, I be 
 lieve, this is no good exception, as it evidently ap 
 pears that the beds of bafaltes which are formed into 
 columns, globes, &c. only alfume thefe figures where 
 they are expofed to the influence of the external air, 
 or have but little cover of rock above them. When 
 any of thofe beds ftrike deep under the cover of feveral 
 other ftrata, they are not found in columns, Sec. No 
 thing but an uniform mafs then appears, although the 
 fame bed is regularly formed near the furface ; which 
 proves that the columnar and other b:i(altes are formecl 
 by {link king and chapping. 
 
 " THe ftrata of bafaltes fpread as wide, and ftretch 
 as far in the longitudinal bearing, as the other differ 
 ent ftrata which accompany them in the countries 
 where they are found. The rocks of bafaltes alfo are. 
 generally found in very thick Grata $ and that gene 
 rally in places where no other rock is found above 
 the bafaltes, the ftrata of it are often very unequal in 
 thicknefs. But this, in general, is only in filiations 
 
 where 
 
C 320 ] 
 
 where no other rock is found above it ; for when it 
 fairly enters into the furface of the earth, fo as to 
 have other regular ftrata above it, which is feen in an 
 hundred places in the Lcthians, "Fife, and other parts 
 of Scotland, it then appears pretty equal in thicknels, 
 as equal as moft other beds of fuch great thickneis 
 are ; and yet it is remarkable, that although moft of 
 the ftrata of bafaltes are of great thicknefs, there are 
 frequently thin ftrata of various kinds found both 
 above and below it. We have numerous examples 
 of this in all the parts of Scotland where bafaltes is 
 found; as for inftance, there are thin and regular 
 ftrata feen and quarried both above and below the 
 thick bed of that rock in the Salisbury craigs near 
 Edinburgh. In the Bathgate hills, fouth of Linlith- 
 gow, and many other parts of Scotland, tfcere are 
 ieveral ftrata of bafaltes, and likewi.e of coal, lime- 
 {lone, freeftone, and other concomitants of coal blend 
 ed promikuouftyjfratumjufirjtratunt ; and the bafalt 
 is frequently found immediately above, and immedi 
 ately below regular ftrata of coal ; of courfe bafaltes 
 is not the lava of volcanoes. We can prove to occular de- 
 monftration, from the component parts, and from the 
 fituation, ftretch, and bearing of the ftrata of bafaltes, 
 that they are real beds of ftone, coeval with all the 
 other flrata which accompany them ; and are blended 
 with them in the ftruclure of that part of the globe 
 where they are found, as they dip and ftretch as far 
 every way as the other itrata found above and below 
 them. If bafaltes, therefore, be a volcanic production, 
 the other ftra'a muft of neceffity be fo likewife. But 
 how volcanoes fhould produce coal, and how that coal 
 fhould come into contact with burning lava, is not a. 
 little problematical : or rather it is ftrangely abfurd to 
 imagine that burning lava can come into contact with 
 ceal without deftroyino- it. 
 
 The 
 
The regularly ftratified quartzy white-mountain 
 rock is fcarce or rather not to be found in moft parts 
 of Britain. In the Highlands, however, it is very 
 common ; and in fome places of them Mr Williams 
 has feen it ftratifled as regularly as any of the fand- 
 ftoncs, with other regular ftrata of different qualities 
 immediately above and below it ; and fometimes com- 
 pofmg large and high mountains entirely of its own 
 ftrata. This (tone is exceedingly hard, dry, and brit 
 tle, lull of crack^ and (harp angles ; the different ftrata 
 fometimes moderately folid, but oiten naturally broken 
 into fmall irregular maffes, with angles as fharp as 
 broken glafs, av:dof an uniformly fine and granulated 
 texture, reiembiing the fineft iugar-loaf. There are 
 large and high mountains of this ftone in Rofsfhire 
 nnd Invernefsfhire, which, in a clear day, appear at a' 
 diftance as white as fnow, without any lort of vegeta-r 
 tion on them except a little dry heath round the edge 
 of the hill. 
 
 END OF MINERALOGY- 
 
METALLURGY 
 
 ETALLURGY, according to Boerhaavr, 
 comprehends the whole art of working metals, from 
 the glebe or ore, to the uteniil ; in which fenfe efl ay- 
 ing, fmelting, refining, parting, fmithery, gilding, 
 &c. are only branches of metallurgy. But, in the 
 prefent work, Gilding, Parting, Purifying, Refining, 
 Smithery, &c. are treated under their proper names. 
 With others, therefore, we have chofen to reftrain 
 Metallurgy to thofe operations required to feparate 
 metals from their ores for the ufes of life. Thefe opera 
 tions are of two kinds : the fmaller, or Eflaying ; and 
 the larger, or Smelting. But a particular defcrip- 
 tion of the ores themfelves fcemed likewife neceflary 
 to be given ; and to this place, tot , we have refer 
 red a general account of metals, metallifation, mines, 
 and ores, as a proper introduction to the fubject. 
 Hence the following divifion into three parts. The 
 Jirjl treating, I. Of metals and metallifation. 2. Of 
 mines and ores in general. 3. Of the pyrite c . 4. Of 
 the eflaying of ores in general. Thefecom/, Of the par 
 ticular ores, and the methods of eflaying them. The 
 tfxref, Of fmelting of ores, or the methods of extracting 
 metals from large quantities of ores for the purpofes 
 of commerce or manufacture. 
 
 D d PART 
 
3*4 3 
 
 PART L 
 
 SECTION I. 
 
 Of Metals and Metattifaihn. 
 
 NDER the general name metal, we compre- 
 bend here not only the metals properly fo called, but 
 alfo the femimeta/s, or all mvitters which have the ef- 
 fential metallic properties which we fhall here recount. 
 Thus the word metal and metallic juljlance will be fy- 
 nonymous in this article. 
 
 Metallic fubftances form a clafs of bodies, not very 
 numerous, of very great importance in chemiflry, me 
 dicine, arts, and the ordinary affairs of life. Thefe 
 fubftances have very peculiar properties, by which 
 they differ from all other bodies. 
 
 The natural bodies from which metals differ the lead 
 are, earthy and pyritous matters, on account of their 
 folidity and denfity. Metals and ftones are, neverthe- 
 lefs, very different ; the heavieft ftones which are un- 
 metalltc being much lighter than the lighted metals. 
 A cubic foot of r.*.rble weighs 252 pounds; and an 
 equal bulk of tin, the lighted of metals, weighs 516 
 pounds. The difference is much greater when the 
 weight of fuch done is compared with that of gold, 
 .a cu'ric foot of which is 1326 pounds. 
 
 Opacity is another quality which metals poffefs emi 
 nently, the opacity of metals being much greater than 
 that of any unmetailic fubftance. 
 
 This great opacity of metals is a confequence of their 
 denfity ; and thefe two properties produce a third, pe 
 culiar alfo to metals, namely, a capacity of reflecting 
 
 much 
 
C 3*5 3 
 
 ttiuch more light than any other body : hence metals 
 whofe furfaces are polifhecl, form mirrors reprefenting 
 the images of bodies more clearly than any other 
 matter. Thus looking-glaifes produce their reflection 
 merely by the lllvering, which is a covering of 
 metal upon their furfaces. To this reflexive proper 
 ty metals owe their peculiar luftre, called the metallic 
 luftre. 
 
 Although the feveral metallic fubftances differ con- 
 fiderably in^hardnefs and fufibiHty, we may fay in ge 
 neral, that they are lefs hard and kfs fufible than pure 
 earths* 
 
 Metals cannot unite with any earthy fubftance, not 
 even with their own earths, when thefe are deprived 
 of their metallic itate : hence, when they are melted, 
 they naturally run into globes, as much as the abfo- 
 lute gravity of their maf> and their prdTure upon the 
 containing vdFels, Vfill allow. Accordingly, the fur- 
 fkee of a metal in fufion is always convex. A metul in 
 that ftate always endeavours to acquire afpheiiealfonn, 
 which it does more perfectly as the mafs is leis. This 
 effect is very fenfiV;le in quickfilver, which is nothing 
 but a metal habitually fluid or fufed. A mafs of feve 
 ral pounds of mercury, contained in a {hallow wide- 
 mouthed veflel, is fo fprcad out, that its upper furfacc 
 is almoft flat, and the convexity is not very fenlible 
 but at its circumference ; on the contrary, if we put 
 very fmall maiTes of mercury into the fame veifel, as, 
 for inftance, maffes weighing a grain each, they be 
 come fo round as to feem perfect globes. This effect 
 is partly occafioned by the inaptitude of metals to unite 
 with the velieis containing them when in fufion, by 
 which quality the whole affinity which fubfifts betwixt 
 the integrant parts of thefe metals is capable of acting ; 
 and partly allo by this affinity, which difpofes the ir> 
 teg ant parts to con.e as near to each other as they 
 can, and confequently to form a iphere. 
 
 D d 2 This 
 
C 3*6 3 
 
 This property is not peculiar to melted metals, but 
 to all fluids, when contiguous to bodies, folid or fluid, 
 with which they have no tendency to unite. Thus, 
 for initance, mailes of water upon oily bodies, or oily 
 iriailes upm bodies muiftened with water, aflume al- 
 w&ys a fVrm fu much nearer to the fpherical as they 
 are fmaller. Even a large drop of oil poured upon a 
 watery liquor, fo that it ihall be furrounded with this 
 liquor, becomes a perfect iphere. 
 
 All metals are in general f< luble by all acids; but 
 often thefe ft,lutions require particular treatment and 
 circnmflances, which are mentioned under CHEMISTRY, 
 With acid's they form a kind of neutral falts, which 
 have all more cr lefs caufticity. The affinity of me 
 tals is lefs than of abforbent earths and alkaline falts 
 to acids ; and therefore any metal may be feparated 
 from any acid by thefe fubftances. 
 
 Alkaline falts are capable of ading upon all metal 
 lic fubftances, and by proper management will keep 
 them diffolved. 
 
 Metals may in general be united with fulphur and 
 liver of iulphur. With fulphur they form compounds 
 lefemblsng the peculiar fubltance of ores, which are 
 generally nothing elfe than natural combinations of 
 fulphur and metal. Metals have lefs affinity with ful 
 phur than with acids ; hence fulphur may be fepara- 
 ed from them by acids. Some exceptions from thefe 
 general rules, concerning the affinity f metals to ful 
 phur and liver of fulphur, and concerning their fepa- 
 ration from fulphur by acids, may be feen under thg 
 articles of the feveral metals. But thefe exceptions do 
 probably take place, only becaufe we have not yet 
 found the method of furmpunting fome obftacles 
 which occur in the ordinary methods of treating cer 
 tain metals. 
 
 All metals may in general be united with each o- 
 ther, with which they form different allays which have 
 
 peculiar 
 
peculiar properties ; but this rule alfo is not without 
 fome exceptions. 
 
 Metals have a ftrong affinity with the inflammable 
 pri :-.: p!c, and are capable of receiving it fuperabun- 
 dantly. 
 
 LaCtly, oily fubftances feem to be capable of acting 
 upon all metals. Some metals are eafily and copiouf- 
 ly diil" Ived by oils ; and perhaps they might all be 
 found to be entirely foltife^e in oils, if the methods 
 known in chtmiflry were tried for the accomplishment 
 of theie folutions. 
 
 The properties abovementioned agree in general to 
 all metallic fubftances : but, befides the properties pe 
 culiar to each meta-, feme properties are common to 
 a certain number of them ; and hence they have been 
 divided into feverul clafles. 
 
 Thofe metallic matters which, when ftruck by a 
 hammer, ar lirongly ccmpreffcd, are extended, length 
 ened, and flattened, without being broken (which 
 property is called duSiHty or malleability)^ and which 
 alio remain fixed in the mod violent and long conti 
 nued fire, without diminution of weight^ or other fen- 
 fible alteration, are called perfeft metais. Thefe perfect 
 metals are three ; gold, Jilver, platlna. 
 
 The metallic matter^ which are ductile and fixed in 
 the fire to a certain degree, but which are dellroyed 
 by the continued a-tion of fire, that is, changed into 
 an earth deprived of all the character] ftic properties of 
 metals, are called imperfitt metals* Of this kind are 
 _our ; copper t iron y tin, lead. 
 
 The metallic fubttances which, as well as the im 
 perfect metals, lofe their metallic properties by expo- 
 fure to fire, but which alfo have no ductility or fixity^ 
 are diftinguifhed from the others by the name ofjemi-. 
 metals. Of this clafs are feven ; rcgulus of antimony y 
 bijmuth) zinc 9 nickel, regulus of cobalt, regulus of arfcnic^, 
 and of manganefe* 
 
 D d 3 Laftl 7> 
 
C 3*8 ] 
 
 Laftly, mercury, which has all the general proper 
 ties of metals, makes aclafs feparatefrom the others ; 
 becaufe in punty and gravity it is fimilar to the per- 
 fel metals, and in volatility to the femi metals. Its 
 fufibility alfofo far furpafTes that of any other metallic 
 matter, that it is fufficient to diftinguifh it from 
 all, and to give it a diftincl: clafs. We have enume 
 rated, therefore, in all, 15 metallic fubftances; four 
 of which were unknown to the ancients, namely, pla- 
 tina, regulus of cobalt, of manganefe, and nickel. 
 
 As chemifts can compound bodies by being capable 
 of feparating the principles of fuch bodies, and even 
 of reuniting their principles fo as to reproduce fuch 
 compounds as they were originally ; and as hitherto 
 they have not been able to accomplish any fuch decom- 
 pofition upon the perfect metals : hence, if all the other 
 metallic fubftances were equally unalterable,- we fhould 
 be very far from having certain notions concerning 
 metals in general: but if we except gold, filver, and 
 platina, all the other metallic matters are fufceptible 
 of decompoiition and of recompofition, at leaft to a 
 certain decree*; and experiments of this kind have 
 thrown much light on the fubjedl. 
 
 We maiy obferve, that even if we had not been able 
 to decompofe any metallic fubftance, we might ft ill, 
 by reflecting on the eflfential properties of metals, 
 difcover fufficiently well the nature of their princi 
 ples. 
 
 The folidity, the confidence, and efpecially the gra 
 vity, which they poffefs in a degree fo fuperior to all- 
 other bodies, wottld not have allowed us to doubt that 
 the earthy element, of which thefe are the characlerif- 
 tical properties, enters largely into their compofition, 
 and makes their bafis. 
 
 The facility with which they combine with almoft 
 all inflammable matters, and with all thofe which have 
 great affinity with phlogifton, fuch as acids ; joined to 
 their incapacity of being allayed with meagre matters 
 
 that 
 
C 3*9 1 
 
 that are purely earthy or purely watery, wkich have 
 no dif petition to unite with phlogiiton ; would alfb have 
 furniihed very iironger motives to believe, that the in 
 flammable principle enters largely into the compofition. 
 of metals. 
 
 The deftruftible metals prefent exa&ly the fame 
 phenomena as all other bodies containing the inflam 
 mable principle do, in the ftate of combustion. When 
 expoled to fire, without accefs of air, that is, in clofe 
 velfels, they become red-hot, melt, or fublime, ac 
 cording to their nature : but they receive no alteration 
 in their compofition from fire applied in this manner, 
 and they are afterwards found to be exactly in the fame 
 {late as before. In this refpetf, they refemble periedt- 
 ly all bodies which contain no other inflammable mat 
 ter than pure phlogifton. 
 
 But when imper'ecl: metals are expofed to fire, with 
 accefs of air, as, for inftance, under a inurHe in a fur 
 nace which is made very hot, then they burn more or 
 lefs fettfibly, as their inflammable principle is more or 
 lefs abundant, or more or lefs combined. Some o 
 th-em, as iron and zinc, burn with a very lively and 
 brilliant flame ; but this flame is of the fame nature as 
 that of charcoal, offulphur, of all bodies, the comb u- 
 ftible principle of which is pure phlogiilon, and is not 
 in an oily itate, that is, furniihes no foot capable of 
 blackening. 
 
 The imperfect metals detonate with nitre, and their 
 phlogift n is coniumed by this method much more 
 quickly and completely than by ordinary calcination 
 orcombuftion. Their flame is alfo much more lively 
 and brilliant ; and me of them, as iron and zinc, are 
 ufecl in compofitio-ns for fireworks from their very 
 vivid and beautiful flame. 
 
 Nitre is alkaiifed by thefe metallic detonations ex 
 actly in the fame manner as in its detonation by 
 coals. 
 
 Laftly, 
 
C 33 3 
 
 Laftly, imperfecl: metals being treated with acids 
 which have an affinity whh plogillon, that is \vith the 
 vitriolic and nitrous acidt., and deprived by the'e acids 
 of a more or lefs confiderable part ot their inrlarnrna-' 
 b!e principle ; they give a fulph'ireous quality to vi 
 triolic acid, and are even capable of producing fulphur 
 with that acid. 
 
 Although the experiments now mentioned were the 
 only proofs of the exillenre of an ir flammable principle 
 in metallic Jubilances, they will.: ;^e fufficient to 
 eftablifli it inconteftably. But we 1l' ill lee, when we 
 continue to examine the phenomena attending the de- 
 compofition of metals, that thofe are not the only 
 proofs. 
 
 If the inflammable matter which fliows itfelf fo evi 
 dently in the burning of metals, is really one of their 
 ccnilitucnt parts, th ii efTential prope. t:es mult be al 
 tered in propoitiun to the quantity of it taken from 
 them: and this evidently happens up n trial, for the 
 refiduum ( f metallic matters, alter calcination, departs 
 from the metallic c^a> ater, and approaches to the na 
 ture of mere earth. The opacity, brilliancy, ductility, 
 gravity, fufibility, volatility, in a W.-TCI, all the pro 
 perties by which metallic fubftances :V*fi-;r front fimple 
 earths, diminiih or entirely difiippear, by taking frrm 
 them their infl.immabl: pri; tijple ; fo that when their 
 caliina*i< n has been carried as far as is pcffible, they 
 refemble mere earths, and have no 1< n^jer a)-y thi in 
 common with metals. TKefe earths can no long -e 
 combined with acids (^r with metals, Vut are capable 
 ef uniting with ppre earths. Thev are then ca. ed 
 falxes or metallic earths. See CHEMISTRY. 
 
 We muft obferve concerning the decompaction of 
 metals, i Tl;at when a fnull qii'-rntivy of inflammable 
 principle is taken from n Ual, ( nly a fmall quantity 
 of calx is formed, and the remaning part continues in 
 the metallic ftate : hence, as the portion of calcined 
 matter can no longer remain united with that which 
 
C 33' 3 
 
 is deftroyed, it feparates in form of fca'es from the 
 furface of the metal, when the calcination has been 
 performed without fulion, as general. y happens to iron 
 and to copper : or thefe fcales float upon the furface 
 of the melted matter when the calcination is perform 
 ed during fulion, becaufe the calx is fpecifically light 
 er than the metal ; as happens to the very fulible me 
 tals, as tin, lead, and moil of the femimetals. 
 
 2. The imperfect metals are not all equally eafily 
 and completely calcinable. In general, as "much of 
 their pblogifton may be eafily taken from them, as is 
 fuiHcient to deprive them of their metallic properties ; 
 but the remaining portion of their phlogifton cannot 
 be fo eafily driven off. Some of them, as copper, 
 refill the firft calcination more than the reft: and 
 others, as lead and bifmuth, may be very eafily calci 
 ned, but only to a certain degree, and retain always 
 obftinately the laft portions of their inflammable prin 
 ciple ; laftly others, as tin and regukis of antimony, 
 may not only be eafily and quickly calcined, but alfo 
 much more completely. All the other metals partake 
 more or lefs of the properties relating to their calci 
 nation. In general, if \ve except the labours of al- 
 chemifts, which are not much to be depended upon, 
 we have not yet made all the proper eiforts to arrive at 
 a perfect calcination of the feveral metallic fubftances ; 
 which however is abfolutely neceffary, before we can 
 arrive at a c< mplete knowledge of the nature of their 
 earths, as we fhall afterwards fee. 
 
 When metallic earths have loll but little of their 
 phlogifton, and are expofed to (Irong fire, they melt, 
 and are reduced to compact maffes, ftill heavy and 
 opake ; although much lefs fo than the metals, and al 
 ways brittle and abfolutely unmalleable. If the calci 
 nation has been more perfect, the metallic earths are 
 ftill fufible by fire, but lefs eafily, and convertible into 
 brittle and trar.fparent maffes poffefled of all the pro 
 perties cf glafs, and are accordingly called meta-lk 
 
 gla/v. 
 
t 33* J 
 
 Thefe glaffes do not pofTefs any of the proper 
 ties of their metals, excepting that they are fpecifically 
 heavier than other glailes, that they are capable of 
 being attacked by acids, and that the glaffes of the 
 femimetals are fomewhat lefs fixed than unmetallic 
 glaffe?. LafUy, when the calcination of metals has 
 been carried to its greateft height, their earths are ab- 
 folutely fixed, and unfufible in the fire of our furnaces, 
 and poffefs no longer the Iblubility in acids by which 
 metals are characlerifed* 
 
 Thefe are the principal changes which metals fufFer 
 by lofing their phlogifton. They are thus changed 
 into fubftances which have no properties but thofe of 
 earth. This is a certain proof that the inflammable 
 principle is one of their conftituent parts. But we have 
 alfo other proofs of this important truth* The reduc 
 tion of metallic calxes into metal, by the addition of 
 phlogifton alone, completes the preen andthewhele 
 forms one of the cleared and mod f&tiifa&ory demon* 
 ftratlom in all the fciences, Thii reduction is eftec- 
 ted in the following manner t 
 
 If the earth of a metal be mixed with any inflam 
 mable matter, which either is or can be changed into 
 the ftate of coal, together with fome fait capable of 
 facilitating fufion, but which, from its quantity or qua 
 lity, is incapable of receiving the inflammable princi 
 ple ; arid if the wjiole be put into a crucible, and the 
 fufton promoted by a fire gradually railed; then an 
 effervefcence will happen, accompanied with a hiding 
 noife, which continues a certain time, during which 
 the fire is not to be increafed ; afterwards, when the 
 whole has been well fufed, and the crucible taken from 
 the fire and cooled, we fhall find at the bottom, upon 
 breaking it, the metal, the earth of which was em 
 ployed for the operation, poflefled of all the properties 
 which it had before calcination and reduction. 
 - We cannot doubt that this transformation of an 
 earthy fubftance into a metal, is folely caufed by 
 
 the 
 
C 333 ] 
 
 phloqjifton pafling from the inflammable matter to 
 the metallic earth. For, firft, in whatever manner and 
 with whatever fubftance metallic earths be treated, 
 they cannot be ever reduced into metals without a con 
 currence of fome fubflance containing phlogillon. 
 2dly, The nature of the fubilance which is to fu nilh 
 phlogift.m is quite indifferent, becaufe this principle is 
 the fame in all bodies containing it. 3<ily, If> after 
 the operation, the fubftance furnilliing the phlogiilon 
 be examined, we ihall find that it has left as much of 
 that principle as the metallic earth has received. See 
 PHLOGISTON. 
 
 The facts related concerning the decompofition and 
 the recompofition of metals, prove inconteftably that 
 they are all compofed of earth and phlogifton. But 
 we do not yet certainly know whether thefe two be 
 the only principles of metals. We might affirm this 
 if we could produce metals by combining phlogifton 
 wirh fome matter which is certainly known to be limple 
 earth. But this hitherto has not been accomplished ; 
 for if we try to treat any earth, which has never been 
 metallic, with inflammable matters, we fhall perceive 
 that the fimple earths are not combinable with phlogi- 
 fton fo as to form metals. We mail even perceive that 
 the metallic earths refill this combination, and are in- 
 capable of reduction into metal, when they have been 
 fo much calcined as very nearly to approximate the na 
 ture of fimple earths. 
 
 Thefe coniiderations, added to this, that we cannot 
 eafily conceive ho^v, from only two certain principles, 
 fo many very different compounds as the feveral me 
 tallic fubftances are, fhould refult, are capable of indu 
 cing a belief that fome other principle is added to thefe 
 two already mentioned in the compofition of metals. 
 
 Many great chemitts, and particularly Becher and 
 Stahl, feem to bs of this opinion. Chiefly from the 
 experiments concerning the mercurification of metals, 
 they believe that this third principle exifts copiouily 
 
 in 
 
t 334 3 
 
 in mercury ; that it is of a mercurial nature ; that it 
 nlfo exifts in marine acid, to which it gives its fpecific 
 character ; that, by extracting this mercurial principle 
 from marine acid, rr any other body containing it co- 
 pioufly, and by combining it with fimple earths, thefe 
 may acquire a metallic character, and be rendered ca 
 pable of receiving phlogifton, and of being completely 
 metallifed. 
 
 Thefe chemifts admit alfo, and with probability, a 
 different proportion of metallic principles in the feve- 
 ral metals ; ar.d believe, that particularly the principle 
 which they call mercurial earth, exifts more copioufly 
 and fenfibly in certain metals than in others. The moll 
 mercurial metals, according to them, are mercury, fil- 
 ver, lead, and arfenic. Moft chemifts diftinguifh them 
 from the other metals, which they call white metals, 
 lur.ar metals^ cr mercurial metals. 
 
 AU thefe confiderations being united, and others too 
 many to be mentioned, give fome probability to the 
 exiftence of the mercurial principle in metals. We muft 
 however acknowledge, that the exiftence of this prin 
 ciple is meiely probable ; and, as Stahl obferves, is 
 n<?t rearly fo well demonftrated as that of the inflam 
 mable principle : we may even add, that wt have flrong 
 motives to doubt of its exiftence. 
 
 To produce metals artificially has juftly been reck 
 oned one of the raoft difficult problems in chemiftry. 
 
 Metallic fubftances, although they refemble each 
 other by their general properties, differ neverthelefs 
 from each ether very evidently by che properties pe 
 culiar to each. Do thefe differences proceed from 
 the different \ roportion, and from the more or his in 
 timate connexion cf the inflammable principle with 
 the earthy principle, fuppofing that this latter fhould 
 be effentially the fame in all metals ? or ought they to 
 be attributed to the difference of earths, which in that 
 cafe would be diftincl: and peculiar to each metal ? or, 
 laftly, do metals differ frcm each other, both by the 
 4 nature 
 
C 335 ] 
 
 nature of their earths, and by the proportion and in 
 timacy of connection of their principles ? All thefe 
 things are entirely unknown ; and we may eaiily per 
 ceive, that till they are known, we cannot difcover 
 what method to purfue in our attempts to acccmpliili 
 the combinations we are now treating of. 
 
 The moil eilential point then is, to arrive at a know 
 ledge of the true nature of the earths which are in me 
 tals ; and the only method of arriving at this know 
 ledge is, by reducing them to their greateft (implicity 
 by a perfect calcination. But this cannot be accom- 
 plifhed but by long and difficult operations. We have 
 feen above, that all metals are not calcinable with 
 equal eafe ; that the perfect metals have not been hi 
 therto calcined truly by any procefs ; and that, in 
 general, the iaft portions of' phlogifton adhere very 
 itrongly to calcinable-metals. 
 
 Some metals, however, -as tin and regulus of an 
 timony, may be eafily calcined fo as to be rendered 
 irreducible. By carrying the calcination ftill fur 
 ther, we might obtain their earths fo pure, that all 
 their eiTential properties may be difcovered, by 
 which they might be eafily compared together. 
 This comparifon would decide whether their nature 
 be efTentially different or not. 
 
 If they vere found to be compofed of earths effen- 
 tially the fame, we might next proceed to compare me 
 tallic with unmetallic earths. If the former were found 
 iimiliir to iome of the latter kind, we fhould be then 
 allured that the earth of metals is not peculiar to them, 
 and that ordinary unmetallic earths are fufceptible of 
 metallifation. From fome late experiments, it was 
 imagined that lime ard mngnefia alba were capable of 
 being converted into n.etaliic fubftances, but the pro- 
 ceifes are now found to be erroneous. 
 
 The greater tl.c i i n her of metals operated upon, 
 
 the more gener. ertam the conferences refiilt- 
 
 ing from thefe would he : fo that, ilr iailance, if the 
 
 1C e operation 
 
C 336 ] 
 
 operation were extended to all calcinable metals ; and 
 if the refult of each of thefe operations were, that the 
 calxes, when perfectly dephlogifticated, do not differ 
 from each other, and are fimilar to earths already 
 known ; we might conclude from analogy, and we 
 Ihould be almoft certain,, that the earths of the per 
 fect metals are alfo of the fame nature. 
 
 They who know the extent and difficulties of che 
 mical operations, will eafily perceive that this would 
 be one of the moft confiderable. Neverthelefs, after 
 having determined this eflential point, we fhould only 
 have done half our work : "For a knowledge of the 
 nature of the earth of metals, and where it is to be 
 found, would not be fufiicient : we muft further en 
 deavour to find a method of combining with this 
 earth a fufficient quantity of phlogtfton, and in a 
 manner fufficiently intimate, that a metal might be 
 formed by fdch a combination. But this fecond 
 difficulty is perhaps greater than the former. 
 
 We muft obferve here, that fome famous chemical 
 procefles have been confidered by many as metallifa- 
 tions, but which are really not fo. Such is Becher's 
 famous experiment of the mln.ra arenarla perpettia, 
 by which that chemift propofed to the States General 
 to extract gold from any kind of land. Such alfo is 
 the procefs of Bcche.r and. of Geolfroy, to obtain iron 
 from all clays by treating them with linfeed oil in cloie 
 vefTels. In thefe, and many other fuch precedes, we 
 only obtain metal that was already formed. Every 
 earth and land, as the intelligent and judicious Cra 
 mer obferves, contains fome particles .of gold. Clays 
 Jo not commonly contain iron ready formed ; but all 
 of them contain a ferruginous earth, naturally dif- 
 pofed to metallifation. (S,;e CLAY.) Accordingly we 
 mud conclude, that, by Mr Geoffrey's experiment, 
 iron is only reduced or revived, but is not produced. 
 
 The great difficulties which occur in attempting to 
 give a metallic quality to fimple earths have induced 
 
 A belief, 
 
. C 337 J 
 
 a belief, that the nature of metals ready formed 
 might be more eafily changed, and the lefs perfect 
 brought to a more perfect date. To effect this, 
 Which is one of the principal objects of alchemy, and 
 is called tranf mutation^ numberlefs trials have been 
 made. As we have not any certain knowledge of 
 what occaiions the fpecific differences of metallic fub- 
 ftances, we cannot decide whether tranfmutation be 
 poifible or not. In fa&, if each metallic fubftance 
 have its peculiar earth, efTentially different from the 
 earths of the others, and consequently if the differ 
 ences of metals proceed from the differences of their 
 earths; then, as we cannot change the effential pro 
 perties of any fimple fubftance, tranfmutation of metals 
 niuft be impofT-ble. But if the earths and other princi 
 ples of metals be efTentially the fame, if they be combi 
 ned in different proportions only, and more or lefs 
 ftrictly united, and if this be the only caufe of the fpe 
 cific difference of metals j we then fee no impoffibility 
 in their tranfmutation. 
 
 Whatever be the caufe of the differences of metals, 
 their tranfmutation fet-ms to be no lefs difficult than 
 the production of a new metallic fubftance ; and per 
 haps it is even more difficult. Alchernifts believe that 
 tranfmutation is poffible, and they even affirm that 
 they have effected it. They begin by fuppofmg that 
 all metals are compofed of the fame principles ; and 
 that the imperfect metals do not differ from gold and 
 filver, but becaufe their principles are not fo well 
 combined, or becaufe they contain heterogeneous mat 
 ters. We have then only thefe two faults to remedy, 
 which, as they fay, may be done by a proper coction, 
 and by feparahng the pure from the impure. As we 
 have but very vague and fuperficial notions concerning 
 the chafes of the differences of metals, we confcfs that 
 we cannot make any reafonable conjecture upon this 
 matter ; and we faall only advife thofe who would 
 E e 2 proceed 
 
C 338 3 
 
 proceed upon good principles, to determine previouily, 
 if metals have each a peculiar earth, or only one com 
 mon to them all. In the fecond place, if it fhould be 
 demrnftrated that the earthy principle is the fame in 
 all metals, and if that be demonftrated as clearly as 
 the identity of the inflammable principle in metals is 
 proved ; they muft then determine whether chefe two 
 be the only principles in metals, whether the mercu 
 rial principle exiits, and whether it be efiential to all 
 metals or to feme only, and what is the proportion 
 of thofe two or three principles in the feveral metallic 
 fubftances. When we (hall clearly underftand thefe 
 principal objects, we may then be able to determine 
 concerning the pofiibility of tranfmutation ; and if the 
 poffibility fhould be affirmed, we (hall. then begin to 
 difcover the road which we ought to purfue. 
 
 We have no reafon to believe that any other prin 
 ciple enters into the ccmpofiticn of metals than thofe 
 abovementioned : no veftige is perceptible of either air 
 or water. Some chemifts have neverthelefs advanced 
 that they contain a faline principle. If that were true, 
 they would alfo contain a watery principle. But 
 all the experiments adduced to prove this opinion are 
 either falfe, or only fhow the prefence of fome faline 
 particles extraneous to the metals, or contained un- 
 knowa to the chemifts in the fubftances employed in 
 the experiments. For metals perfectly pure, fu Reel 
 ed to all trials with fubftances which do not contain 
 and which cannot produce any thing faline, do not 
 difcover any faline propeity. We muft however 
 except arfenic, and even its regulus, thefe being fm- 
 gular fubftances, in which the faline are as fenfible as 
 the metallic properties. 
 
 - Arfenic feems to be one of thofe intermediate fub 
 ftances which nature has placed in alnaofl all its pro 
 ductions betwixt two different kinds, and which par 
 take of the properties of each kind. Arfenic thus placed 
 
 betwixt 
 
C 339 .1 
 
 betwixt metallic and falir.e fubttances has properties, 
 common to both thefe kinds of fubflances, without be 
 ing either entirely a metal or fait. See ARSENIC. 
 
 As water feems to a6t to a certain degree upon iron, 
 even without the concurrence of air, as the operation 
 of martial ethiops fliows, we might thence fufpect 
 ibinething faline in that metal. Nevertheless, what 
 happens in that operation has not been fo well explain 
 ed, that any certain confequences can be deduced, 
 i. The water employed ought to be perfectly pure; 
 that is, diftilled rain-water. 2. The iron employed 
 ought alfo to be perfectly pure, and fuch is very diffi 
 cultly to be procured. 3. The operation ought to be 
 performed in a bottle accurately clofed, that we may 
 be aifured that the air contributes nothing to the action 
 upon the iron. 4. After the water has remained a 
 long time, fuppofe a year, upon the iroH, it ought 
 to be carefully filtrated and examined, to afcer- 
 tain whether it really has diifolved any part cf the 
 metal. 
 
 In the mean time, we way conclude that metals do 
 not feem to contain any faline principle. And when. 
 \ve confider well their general properties, they feem 
 to be nothing elfe than earths combined more or lefs 
 intimately with a large quantity of phlogifton. Al 
 though we can demoniirate that their inflammable 
 principle is not in an oily Hate, and that it is pure 
 phlogillon, they have neverthelefs an oily appearance, 
 in this circuir.ftance, that they adhere no more than 
 oils to earthy and aqueous Jubilances and that they 
 always aflame a globular nVure when fupported by 
 thefe fubftanc.es entirely free from phlogiuV'ii. 
 
 This refemblance is fo fenfihle, that chemifts, be 
 fore they knew the nature of phlogiston, believed that 
 metals contained an oily and fat nutter. The caufe 
 of this quality of metals is th-i quantity of pblogiiton 
 which they contain. Sulphur, phofphorus, oih, and 
 even fats, have this appearance merely from the in- 
 li e 3 flammable 
 
3 
 
 flammable principle which enters into their competi 
 tion: for this pi open y is ccmn.unicated by that prin 
 ciple to every compound which contains a certain 
 quantity of it. See PHLOGISTON. 
 
 When the phlc.giften combines ccpioufly and inti 
 mately with earthy matters fo as to foim metals, it 
 probably fo difpofes them, that the primitive inte 
 grant parts of the new compound, that is, of the me 
 tal, approximate and touch each other much more 
 than the integrant parts of fimple earths can. This 
 is proved by the great denfity or fpecific gravity, and 
 ether general properties, of metals. 
 
 In fact, as we cannot conceive that a body mould 
 be tranfparent, unlefs it have pores and interftices 
 through which rays of light can pafs ; therefore the 
 more denfe a body is, that 'is, the fewer fuch inter- 
 ilices it has, the lefs tranfparent it will be ; fo that the 
 denfeft bodies ought to be the moft opaque as in metals. 
 The difpofition of the pores of bodies contributes alfo 
 much to their greater or lefs tranfpatency ; and bodies, 
 the pores of which are continued and ftraight, are 
 more tranfparent than thole whofe pores are inter 
 rupted, tranfverfe, or oblique ; fo that a body may 
 be much more tranfparent than another which is lefs 
 denfe, as we fee that glafs is more tranfparent than 
 charcoal. But when other circumftances are equal, 
 the denfeft bodies are the moft opaque. Therefore the 
 opacity of bodies is proportionable to their denfity, 
 and to the deviation of their pores from right and pa 
 rallel lines, 
 
 From the great opacity of metals, they probably 
 poifefs both thefe qualities in an eminent degree. We 
 have feen, at the beginning of this article, that the 
 luftre of metals, and their property of reflecting light 
 much better than any other fubftance, are necerlkry 
 confequences of their opacity. This is alfo felf-evi- 
 dent, becaufe the fewer rays any body can tranfmit, 
 *Ue more it muft reflect. 
 
 JLaftlr, 
 
C 34' 3 
 
 Laftly, the ductility of metals proceeds alfo from 
 their denfity, from ti e diipofmon of their pores, and 
 from the action of latent heat , for even the mcft 
 brittle bodies, fuch as glafs, fealing-wax, &c. become 
 ductile by heat. The foitnefs, fufibility, and volati 
 lity, of which all metals partake more or lefs, and 
 which many ; f them poflcfs in a fuperior degree, being 
 properties entirely contrary to thofe of the earthy prin 
 ciple, probably proceed from the inflammable prin 
 ciple. 
 
 The order in which metals compared with each 
 other pofiVfs moft eminer.tly their principal properties, 
 is the fame as that in which they are here enumerated, 
 beginning always with that metal in which the proper 
 ty is moil coniiderable. 
 
 1. Spicifc gravity or dcnfty. Platina, gold, mercu 
 ry, lead, (ilver, copper, iron, and tin. 
 
 2. Opacity. We cannot well compare metals with 
 each other in this refpeet, becaufe it is fo considerable in 
 all, that it feems complete. If, however, they differ 
 in this refpecl, the fame order will ferve for opacity as 
 for denOty. 
 
 3. Metallic litflrc or Ir'illiancy. The fame obferva- 
 tion which was made concerning the laft mentioned 
 property is applicable to this alfo. We muft, how 
 ever, obferve, that as by polifh bodies are rendered 
 brighter, and that as whitenefs contributes rBuch to 
 the reflection of light, the whiteft and hardeft metals 
 therefore reflect beft. Hence according to Mr Mac- 
 quer, platina ought to be placed firft ; and then iron, 
 or rather fteel, filver, g Id, copper, tin, lead. 
 
 Hardnefs of metals may contribute much to the du 
 ration of their polilh ; but certainly foft metals, if their 
 texture be equally compact, are no lefs capable ot re- 
 ceivi: g a poliih than hard rmtals. Some hard metal 
 lic allays have been found to be lefs liable to tarnifh 
 than fofter compounds, and have for this reaf^n alfo 
 been chie3y ufed for fpeculums. The property of re 
 flecting 
 
[ 34* ] 
 
 hefting light feems chiefly to depend on the defends 
 of the particles or on the denfity, on the fro o> -thuds 
 of the furface, and on the colcir being io.ft nru< ; ar to 
 the col. ur of the light to be reflected. The white 
 metals, iilver, mercury, tin, r-fl.ct light rm>rt. -ibim* 
 danily than others. Gold, b?irg the denfcft meta' rext 
 to platina, and perhaps "becaufe the colour of f< 1 r 
 Imht has a flight!} 1 yellowifh tinge, dees alfo reflect 
 light very copioufly. Hence fpeculums made of leaf- 
 gold have been found to he very powerful. Iron or 
 ilecl reflect? much lefs light than any of the abovemen- 
 tiuned metals, although Mr Macquer has confidered 
 it as capable of a greater reflective power. Platina is 
 generally in fo fmall grains, that its reflexive power 
 cannot eafily he determined. The precife degrees of 
 that power which ought to be affi^ned to each of the 
 abovementioned metais, cannot without accurate ex 
 periments be ascertained. Perhaps, howevtr, their 
 reflective powers will be found to be more nearly in the 
 following order, than in that abovementioned from 
 M; Macquer. Silver, quickiilver, tin, gold, copper, 
 iron, lead. 
 
 4. Duft'llfy. Gold, filver, copper, iron, tin, lead. 
 The ductility of mercury and that of platina are not yet 
 deteim ned. 
 
 5. Hardncfs. Iron, platina, copper, filver, gold, tin, 
 and lead. 
 
 6. Tenacity. By tenacity we underftand the force 
 with which the integrant parts of metals rend their 
 feparation. This force appears to be in a compound 
 ratio of their ductility and harcnefs. The compara 
 tive tenacity of metals is meafured by the weight 
 which wires cfthe fame dianjeter, made ofthefeveral 
 metals, can Altai n without breaking. Gold is the 
 moil tenacious; then iron, c pper, iilver, tin, lead. 
 The tenacity of mercury is unknown ; that of pla 
 tina is not yet determined, 'but is probably confider- 
 able. 
 
 7. Fufib'ility* 
 
[ 343 ] 
 
 y. Fufibility. Mercury, tin, lead, filver, gold, cop 
 per, iron, and laftly platiria, which cannot be fufed by 
 the grcateft fire of our furnaces, but only by the iolar 
 focus, or by a fire excited by dephlogifticated air. 
 
 SECT. II. Of Mines and Ores In general. 
 
 THE fubftances found naturally combined with me- 
 tals in the earth, are, particularly fulphur and arfenic, 
 ibmetimes feparately, but generally conjointly. Me- 
 tals combined with thefe fubftances are called metals 
 mmeralijed by fulphur , or by arfenic, or by fulphur and 
 arfenic i and thefe matters are called mineraltfng fub 
 ftances. 
 
 Befides the fulphur and arfenic with which metals 
 are (Iriclly combined in the mineral (late, they are alfa 
 pretty intimately combined with earthy fubtlances, of 
 different natures, and more o-r lefs divided. 
 
 Thefe different matters united together form maMes 
 which are compact, heavy, brittle, and frequently pof- 
 feiied of much metallic laftre. Thefe fubiiances are 
 properly called ores, or the matter of mines, 
 
 Thefe ores are found in earths and ftoncs of different 
 kinds, as fands, flints, cryftals, dates, indurated clays, 
 according to the ground in which they are contained. 
 But two kinds of (lones in particular feem to accom 
 pany ores ; and have therefore been confidered by fe- 
 veral mineralogifts as matrixes in which metals are 
 formed. One of thefe (tones is a kind of cryftal, ge 
 nerally white, milky, and femi-opaque, fcriking fire 
 with fteel, and of the clafs of verifiable earths. It is 
 called QJJARTZ. 
 
 The other ftone is lefs hard, which does not ftrike 
 fire with ileel, and is fomctimes milky like quartz ; 
 fometimes tranfparent and of different colours ; con- 
 fifting of rhornboidal cryftals, which are compofed of 
 plates and faces. This (lone becomes more ibft and 
 friable by being expofed to fire. It is calledjjter. Spar 
 
 is 
 
t 344 ] 
 
 is more like to gypfeous ftones than to any other, but 
 it differs from gypfeous ftones in pofleffing a much 
 greater denfity. Some fpars are fo heavy, that they 
 exceed in this refpect all other ftones. See SPAR. 
 
 Thefe earthy and ftony fubftances form the matrix 
 cf the ore* 
 
 Ores are natural compounds, containing metals al 
 layed with different fubftances. 
 
 Excepting gold, and a very fmall quantity of each 
 of the other metals found in ibme places fo pure as to 
 pojTefs all their chara&eriftic properties, nature exhi 
 bits to us metals and femimetals differently allayed not 
 only with each other, but alfo with feveral heteroge 
 neous fubftances, which fo alter and difguife their qua 
 lities, that in this ftate they cannot ferve for any of the 
 purpofes for which they are proper when they are fui> 
 ficiently pure. 
 
 Ores ccnfift, I. Of metallic fubftances cahtned ; or, 
 2. Of thefe fubftances combined with other matters, 
 with which they are faid to be mneralifcd. 
 
 Calcined metallic fubftances, or caldform ores t are 
 metallic fubftances deprived of phlogifton, and in the 
 ftate of a calx or metallic earth. Such are &\l ferru 
 ginous ochres, which are calces of iron. 
 
 Mineralifed ores, are, I. Simple, containing only one 
 metallic fubftance ; or, 2. Compound, containing two 
 or more metallic fubftances. 
 
 Of the fimple, and alfo of the compound ores, four 
 kinds may be diftinguifhed. 
 
 1. Ores confiftin % of metallic fubftances mineralifed 
 by fulphur. Such is the lead-ore called galena, com- 
 pofed of lead and fulphur. 
 
 2. Ores confiding of metallic fubftances mineralifed 
 by arfenic. Such la the white pyrites, containing iron 
 and arfenic. 
 
 3. Ores confining of metallic fubftances mineralifed 
 lyfulphur and by arfenic. Such is the red filler-ore, con 
 taining filver, arfenic, and fulphur. 
 
 4. Ore* 
 
[ 345 ] 
 
 4. Ores confiding of metallic fubftances mmeralifed 
 by faline matters. Such are the native "jitrish. Such 
 allo is probably the corneous fifosr-nre, which, accord 
 ing to Mr Cronftedt's opinion, is a luna cornea, or fil- 
 ver combined with marine acid. Of this kind of ores, 
 or native metallic falts, is perhaps tke ffdatii&fett of 
 borax, which from Mr Cadet's experiments, published, 
 in the Memoires of the royal Academy for the year 
 176^, is conjectured to be coppc- combined with ma 
 rine acid, and which has been ikiu to bs found native. 
 To this clafs alfo may be referred \\\Q fiver mineralifcd 
 ly an alkalme fubftantt, which ivfr Von Jufti pretends to 
 have difcoveied. 
 
 Henckel, and after him Cramer, and the author of 
 the Dictionary of Chemiftry, pretend, that in .minera- 
 lifed ores, beiides the abovementioned metallic and 
 mir.eralifmg fubftances, are alfo contained a metallic 
 and an unmetallic earth. But Wallerius affirms, that 
 the exiftence of fuch earths cannot be fliown, and that 
 fulphur is incapable of diflblving unmetallic earths, and 
 even the calces of all metallic fubftances, excepting 
 thofe of lead, b ; fmuth, and nickel. 
 
 Metals and metalliferous crcs are found in various 
 places. 
 
 I. Under wafer ; in beds of rivers, lakes, and feas, 
 .jn.i chiefly at the flexures of thefe : fuch are the au 
 riferous and feiruginerusfands, grains of native gold, 
 ochres, and fragments cf ores Wiflied from mines. 
 
 II. D'ljji l-vecl innvahr : fuch are the vitriolic waters 
 containing iron, copper, or /inc. 
 
 III. Upon the fit "face of the earth. Such are many 
 ochres; metalliferous ftoues, fands, and clays; and 
 lumps cf ores. Mr Gmelin fays, that in the northern 
 parts of Afia ores are almcfl always found upon or 
 near the furface of the ground. 
 
 IV. Umlir tie furfii'-s of tie earth. When the quar,- 
 tity of thefe colkcic;] in one place is confiderable, it is 
 
 rd a mine, 
 
 Subtei 
 
t 346 ] 
 
 Subterranean metals and ores are differently difpo- 
 fed in different places. 
 
 1. Some are infixed inftones and earths ^ forming no 
 dules or f pots diverfely coloured. 
 
 2. Some are equably and uniformly dlffufed through 
 tie fubjlance of earths and fanes, to which they give co 
 lour, deniity, and other properties. Such are the 
 greateft part of thofe earths, (tones, lands, clays, cry- 
 ilals, flints, gems, and fluors, wliich are coloured. 
 
 3. Some form Jlrata in mountains. Such are the 
 dates containing pyrites, copper-ore, lead-ore, filver- 
 ore, or blend. Thefe lie in the fame direction as the 
 ftrata of (tones betwixt which they are placed ; but 
 they differ from the ordinary ftrata in this circum- 
 ftance, that the thicknefs of different parts of the fame 
 metalliferous ftratum is often very various ; whereas 
 the thicknefs of the ftony itrata is known to be gene 
 rally very uniform. 
 
 4. Fragments of ores are frequently found accumu 
 lated in certain fubternmean cavities, in fiifures of 
 mountains, or inter pofed betwixt the ftrata of the 
 earth. Thefe are loofe, unconnected, frequently in 
 volved in clay, and not accreted to the contiguous 
 rocks or ftrata immediately, nor by intervention of 
 fpar or of quartz, as the ores found in veins are. 
 Tin, and iron mines are frequently of the kind here de- 
 fcribed. 
 
 5. Large entire mafTes of ores fometimes found in 
 the ftony ftrata of mountains. Thefe are improperly 
 called accumulated veins, be caufe their length, relative 
 ly to their breadth and depth, is not conliderablc. 
 
 6. Some inftances are mentioned of entire mountains 
 confifting of ore. Such is the mountain Taberg in 
 Smoland ; and fuch are the mountains of KeruBavara 
 and Luofavara in Lapland, the former of which is 
 1400 perches long and 100 perches broad. Thefe 
 mountains confiit of iron ere. 
 
 7. Laftly, 
 
 2 
 
[ 347 ] 
 
 7- Laftly, and chiefly, metals and ores are found in 
 oblong tracts, forming malTes called veins, which lie in 
 the ftony ftrata compcfing mountains. See the article 
 
 MINE. 
 
 SECT. III. Of tie Pyrites. 
 
 PYRITE is a mineral refembling the true ores of me* 
 tals, in the fubftances of which it is compofed, in its 
 colour orluftre, in its great weight, and, laftly, in the 
 parts of the earth in which it is found, fince it almoft 
 always accompanies ores. It is, like ores, compofed 
 of metallic fubftances, mineralized by fulphur or by 
 arfenic, or by both thefe matters, and of an unmetal- 
 lic earth intimately united with its other principles. 
 
 Notwithstanding the conformity of pyrites with ores 
 properly fo called, fome chemifts and metallurgies di- 
 i-tinguifn the former from the latter minerals ; becaufe 
 the proportion and connection of the materials compo- 
 fmg the pyrites differ much from thofe of ores. Thus, 
 although fometimes pyrites contains more metal than 
 fome ores, yet generally it contains lefs metal, and a 
 larger quantity of mineralifing fubftances, fulphur and 
 arfenic, and particularly of unmetallic earth. The' 
 connection of thefe matters is alfo much ftronger in 
 pyrites than in ores, and they are accordingly much 
 harder ; fo that almoft every pyrites can ftrike fparks 
 from ft eel. 
 
 From the above property of ftriking fparks from 
 fteel, they have been called pyrites ; which is a Greek 
 word fignifying^r^cw^. Pyrites was formerly ufed 
 for fire-arms, as we now ufe flints : hence it was called 
 carallne-Jlone. It i? ftill named by fome, marcafite. Per 
 haps no other kind of natural body has received fc) 
 many names. Perfons curious to know the other names 
 lefs ufed than thofe we have mentioned, may find them 
 in Henkle's Pyri-v/ogia. We th'nk, with that cele 
 brated chemift, that the fubject has been perplexed by 
 F f this 
 
I S4* 3 
 
 this multiplicity of r,ames ; for before his great and 
 excellent work, the notions conctrsing pyrites were 
 very confufed and inaccurate. 
 
 Pyrite differs alfo from ores by its forms and pofi- 
 tions in the earth. Although pyritous metals generally 
 precede, accompany, and follow veins of ores ; they do 
 not, properly i peaking, themfelves form the oblong 
 and continued maffes called veins, as ores do ; but they 
 form mafles fometimes greater and fometimes fmaller, 
 but always diftincl from each other. Large quanti 
 ties of them are often found unaccompanied by ore?. 
 They are formed in clays, chalk, marles, marbles, pla- 
 fters, alabafters, Hates, fpars, quartz, granites, cryihils, 
 in a word, in all earths and ftones. Many of them are 
 alfo found in pit-coals and other bituminous matters. 
 
 Pyrites is alfo diftinguifhahle from ores by its luftre 
 and figure; which is almoft always regular and uni 
 form, externally or internally, or both. Some ores 
 indeed, like thcfe of lead, many ores of filver, and fome 
 others, have regular forms, and are in feme manner 
 cryftallized; but this regularity of form is not fo uni- 
 verfal and fo confplcucus in ores as in pyrites. The 
 luftre of pyrites feems to be caufed by its hardnefs, 
 and the regularity of its form by the quantity of mi- 
 neralifmg fubftsnces v hich it contains. 
 
 By all thefe marks we may eafily, and without ana- 
 lyfis, diftinguifh pyrites from true ores. When we fee 
 a mineral that is heavy, poifelTed of metallic luftre, and 
 of any regular form, the mafs of which appears evi 
 dently to be entire, that is, not to have been a frag 
 ment of another mafs, and which is fo hard as to be 
 capable of fti iking fparks from fteel, we may be a (lu 
 red that fuch a mineral is a pyrites, and not an ore. 
 
 The claf^ < f pyrites is very numerous, various, and 
 extenfive. They differ one from another in the nature 
 and proportions of their component parts, in their 
 forms, and in their colours. The forms of thefe mi- 
 fcerals are exceedingly various. No fblid, regular or 
 
 irregular, 
 
[ 349 ] 
 
 irregular, can eafily be conceived, that is not p.erfeclly 
 imitated by fonie kind of pyrites. They are fplieri- 
 cal, oval, cylindrical, pyramidal, prifmatical, cubic ^ 
 they are folids with 5, 6, 7, 8, 9, 10, &c. fides. The 
 furface of fome is angular, and coniifts of many bafes 
 of fmall pyramids ; while their fubftance is compofed 
 of thefe pyramids, the points of which all unite in the 
 centre of the mafs. 
 
 Pyritous minerals differ alfo in their component fub- 
 ftances. Some of them are called fulphureous, martial, 
 cupreous, arfcnlcal, as one or other of thefe fubftances 
 predominate. We mud obferve with Henckel, whofe 
 authority is very great in this fubject, that in general 
 all pyrites are martial ; as ferruginous earth is the ef- 
 fential and fundamental part of every pyrites. Thi* 
 earth is united with an unmetallic earth, with fulphiu* 
 or arfenic, or with both thefe matters ; in which cafe, 
 the fulphur always predominates over the arfenic, as 
 Henckel obferves. He confiders thefe as the only ef- 
 fer.tial principles of pyrites ; and believes that all the 
 other matters, metallic or unmetallic, which are found 
 in it, are only accidental ; amongft which he even in 
 cludes copper, although fo much of it exills in fome 
 kinds of pyrites, that thefe are treated as ores of cop- 
 per, and fometimes contain even 5olb. of copper each 
 quintal. Many other metals, even gold arid lilver, are 
 fometimes combined in pyrites ; but thefe are lei's fre 
 quent, and the precious metals always in very fmall 
 quantities ; they are therefore juftly to be considered as 
 accidental to pyrites The different fubftances compo- 
 fuig pyiites feniibly ai'lx'tf its colours. Henckel di- 
 Ainguiflies them in general into three colours, white, 
 yellowiil], or a pale yellow, and yellow. He informs 
 us, that thefe three colours are often fo blended one 
 with another, that they cannot .be eafily diftinguimed 
 unlefs when compared together. 
 
 The white pyntes contain moft arfenic, and are il- 
 uil,j*r to cobalt and other minerals abounding in arfe- 
 
 F f 2 DIC 
 
C 25 3 
 
 'T.ic. The Germans call them tntjffit&te, or mifclii. Iron 
 and arfenic form the greateft part of this pyrites. As 
 -,irfenic has the property of whitening copper; force 
 pyntous minerals almott white, like that of Chemnitz 
 in Mifnia, are found to contain 40 pounds of copper 
 per quintal, and which are fo much whitened by the 
 -.srfenic, that they are very like white pyrites. But 
 H -nickel obferves, that thefe pyritous matters are very 
 rare, and are never fo white as the true white pyrites, 
 which is only ferruginous and arfenical. 
 Yellowifli pyrites is chiefly compofed of fulphur and 
 iron. Very little copper and arfenic are mixed with 
 any pyrites of this colour, and inoft of them contain 
 none of thefe two metallic fubftances. This i.s the moil 
 common kind of pyrites : it is to be found almoft every 
 where. Its forms are chiefly round, fpherical, oval, 
 flattened, cylindrical ; and it is compofed internally of 
 needles or radii, which unite in the centre, or in the 
 axis of the foUd. 
 
 Yellow pyrites receives its colour from the copper 
 and fulphur which enter into its compofition. Its co 
 lour, however, is inclined to a green ; but is fufnciently 
 yellow to diftinguifh it from the other two kinds of 
 pyrites, particularly when they are compared together. 
 To make this comparifon well, the pyrites muft be 
 broken, and the internal furfaces mufl be placed near 
 each other. The reafon of this precaution is, that die 
 colour of minerals is altered by expofure to the air. ; 
 
 Perfons accuftomed to thofe minerals can eafily di- 
 ftin'g-uifti them. The chief difficulty is, to dittingmili 
 white pyrites from cobalt and other minerals ; which 
 alfo contain fome copper and much arfenic. 
 
 Hence then v\e fee, that arfenic is the caufe of white 1 - 
 fiefs in pyrites, tind is obtained in every pyrites of 
 that colour ; that copper is the principal caufe of the 
 yellow colour of pyrites ; and that every pyrites which 
 is evidently yellow contains copper ; that fulphur and 
 iron produce a p.ile-yellpw colour, which is alfo pto:- 
 
 duccd 
 
[ 35' 3 
 
 duced by copper and arfenic ; hence fome difficult; JT 
 may arife in diitingutihing pyiites by its colours. We 
 may alfo obferve, that fulphur and arfenic, without any 
 other fubitance, form a yellow compound, as we fee 
 from the example of orpiment or yellow arfenic. Thus, 
 although the colours of the pyrites enable us to diilin- 
 guifh its different kinds, and to know their nature at 
 firft fight, particularly when we have been accuftomed 
 to obferve them ; yet we cannot be entirely certain 
 concerning the true nature of thefe minerals, and even 
 of all minerals in general ; that is to know precifely 
 the kinds and proportions of the ; r component Jubilan 
 ces, but by chemical analyiis and decomposition. 
 
 Beiides the abovementioned matters which com- 
 pofe, pyrites, it alfo contains a considerable quantity -oi 
 unmetallic earth ; that is, an earth which cannot by 
 any procefs be reduced to metal. Henckel, Cramer, 
 and all thole who have examined this matter, men 
 tion this earth, and prove its exigence. 
 
 We 'ought to obferve, that this earth is combined, 
 with the other principles of the pyrites, and not mere 
 ly interpofcd betwixt its parts. It muft therefore be 
 diRinguifhed from other earthy and ftony. matters mix 
 ed accidentally with pyrites, and which do not make 
 a part of the pyrites, in-ice they may be feparated by 
 mechanical means, and without decompoilng that mi 
 neral : but the earth of which we now treat is inti 
 mately united with the other confUtuent parts of the, 
 pyrites, is even a conitituent part of pyrites, and ef- 
 fential to the existence of this mineral, and cannot be 
 feparated but by a total decompofition of it,. 
 
 According to Henckel, this unmetallic earth a-.. 
 bounds much in the white pyrites, fince he found : 
 from the analyfes which he made, that the iron, which- 
 is the only metal exitting in thefe pyrites, is only about 
 sJ-^th part of the fixed fubftance that, remains, after the 
 arfenic has been expelled by torrefaclion or. fublima-, 
 t^p-n. 
 
 I f 3 
 
A much Lirger quantity of iron is in the pale yel 
 low pyrites, according to Henckel. The proportion 
 of iron is generally about 12 pounds to a quintal 
 of pyrites, and fometimes 50 or 60 pounds : this is 
 therefore called martial pyrites. It contains about 
 one-fourth of its weight of fulphur, and the reft is 
 unmet allic earth. 
 
 The quantity of unmeullic earth contained in the 
 yellow or cupreous pyrites, which are alfo martial, 
 fmce, as we have obferved, iron is an efTential part of 
 every pyrites, has not yet been determined. They 
 probably contain fome of that earth, though perhaps 
 Icfs of it than the others. 
 
 The nature of this unmetallic earth of pyrites has 
 rot been well examine^. Henckel thinks that it is an 
 earth difpofed already by nature to metallifation, but 
 not fufficiently elaborated to be confidered as a metal- 
 } : c earth. This opinion is not improbable; but as 
 alum may be obtained from many pyrites, may we not 
 fufpecl that this unmetallic earth is of the nature of 
 the bafis of alum of argillaceous earth ? Perhaps alfo 
 this earth is different in different kinds of pyrites. 
 The fubjecl deferves to be well examined, 
 
 Although pyrites are not fo valuable as true ores, 
 hecaufe in general it contains lefs metal, and but ex- 
 -c :edingly little of the precious -metals ; and becaufe its 
 metallic contents are fo difficult to be extracted, that 
 excepting cupreous pyrites, which is called /jr/Voi/j cop* 
 per ore, it is not worked for the fake of the contain 
 ed metal ; yet it is applied to other purpofes, and fur- 
 ruilies us with many ufeful fubftances ; for from it we 
 obtain all our green and blue vitriols, much fulphur, 
 orfemc, and or p' merit. See the principal proceffef by 
 which thefe fubjlatices are extracted from pyrites, under the 
 fc^lion SMELTING of ORES. 
 
 As all pyrites contain iron, and moft of them con-: 
 tain alfo fulphur ; as the pyrites moft frequently found 
 contains only thefe two fubilances with the unme* 
 
 talUc 
 
[ 353 1 
 
 tallic earth ; and as iron and fulphur have a fmcnilar 
 action upon each other when they are well mixed to- 
 gether and moifteifed ; hence many kinds of pyrites, 
 particularly thefe ..which contain only the principles 
 now mentioned, fuftain a fmgular alteration, and even 
 a total decompofition, when expofed during a certain 
 time to the combined action of air and water. The 
 moiihire gradually penetrates them, divides and atte 
 nuates their parts ; the acid of ihe fulphur particularly 
 attacks the martial earth, and alfo the unmetallic earth; 
 its inflammable principle is feparated irom it, and is 
 diiiipated. While thefe al eratiens happen, the py 
 rites changes its nature. The acid of the fulphur 
 which is decompofed, forms with the fixed principles 
 of the pyrites, vitriolic, aluminous, and felenitic falts J 
 fo that a pyrites, which was once a ihining, cornpa&j 
 very hard mineral, becomes in a certain time a; grey iffy 
 faline, powdery mafs, the taite of which is faline, au* 
 ftere, and ftyptic. 
 
 Laftly, if this mafs he lixiviated with water, cryftals 
 of vitriol, nn.l fomnimes of alum, according to the na 
 ture of the pyrites emploj ed, may be obtained by eva 
 poration and cryfta Ir/ation. 
 
 Th's alteration and fpontaneous decom:* fit ion of 
 pyrites, is ca 1 led efflvrefience arid uitrio'izafion ; becaufe 
 the pyrites becomes covered with a faline powder, and 
 becaufe vitriol is always formed. This vitriolization is 
 raore or lefs quickly accompliihed : in pyrites according' 
 to its rature. It is a kind of fermentation excited by\ 
 moifture amrngft the condiment j arts cf thefe mine- 1 
 xals ; and it is fo violent in thofe which are moil ciif- 
 pofed to it, that i c , in the pale yellow pyrites, v.hich 
 contain chiefly fulphur and iron, that when the q:.>a-. 
 tity of thefe is confiderable, not only a fnlphu= t( u.- va 
 pour and heat may be perceived but alfo the v.'.ole 
 kindles and burns intenfely. The fame phen'omei..i are 
 obfervablr.-, anH the fame refults are formed, by mix 
 ing well together, and moiftening a large quantity of 
 
 filings 
 
C 3H I 
 
 hlings of iron and powdered fulphur 
 
 nient Lemeri has made to explain the caufes of fub- 
 
 terranean tires and volcanoes. 
 
 We cannot doubt, that, as the earth contains very- 
 large maffes of pyrites of this kind, they muft undergo 
 the fame changes when air and moitiure penetrate the 
 cavities containing them ; and the betl natural philofo- 
 phers agree, that very probably this iarpriiing decom- 
 pofiti'-n of pyrites is the cauie ot fubterr mean fires, of 
 vcl-.anoes, a: id of mineral waters, vitriolic, aluminous, 
 fiilphtireou", hot and cold. 
 
 No other pyrites is fubjecl: to this fpontaneous de- 
 corapofitiun when exp fed t<> humid air, but that, which 
 is both martial and tulphureous ; that is, the pale- 
 yellow pyrites. The arfenizal pyrites, or that which 
 contains tittle or no fulphur, is not changed by expo- 
 fure to air. This latter kind is harder, heavier, and 
 more compact than the former. The pyrites which is 
 angular and regularly ftiaped, is chiefly of this kind. 
 Mr Wallerius in his Mineralogy, propofes to Jifiin- 
 guifh'this kind of pyrites by the name of warca/ita. 
 "When cut, it may be poliilied fo well as to give a lull re 
 almoft equal to that of diamonds, but without refrac 
 ting or <vx>rnpofmg the light ; for it is perfectly opaque. 
 It has been employedTome years p.ift in the manufac 
 ture of toys, as of buckles, necklaces, c. and is call 
 ed in commerce marcafite. 
 
 We cannot, however, concur with Mr Macqucr 
 (from whom the above is taken), .in thinking that 
 there is fnfficient reafon for confidering the minerals 
 called pyrites, as a didinc! clafs of fubftanccs from ores. 
 They have indeed no mark by which they can certain 
 ly and conftantly be diftinguifhed from thefe. The 
 hardnefs or property of ftriking ignited fparks from 
 fteel is not common to all the fubftances generally call 
 ed fyrites ; for we find fome of thefe enumerated by 
 mineralogifts which have not that property. Wallerius 
 even mentions 3 pyrites which contains no iron, altho v 
 
[ 355 3 
 
 that metal is' thought by K nickel to be eiTential to py 
 rites. The diilinction of pyrites fr rn ores has been 
 chiefly introduced by miners ; becaufe the great eft part 
 of the former minerals contain fo, little metal, and fa 
 much of the miner A! i (ing fubftances, fulphur or arfe- 
 nic, that they are feldom imelted. Nevertheless, foms 
 kinds of pyrites are found which contain fo much cop 
 per, that they are fmelted with great pr< .fit, Accord 
 ingly, fo-me later mineralogifts confider the cupreous 
 yellow pyrites as an ore of copper, the pale-yellow 
 martial pyrites as an ore of iron \ and the white arfe- 
 meal pyrites as an ore of nrfenic. See Ores of Copper^ 
 Iron, and of 4rfenic t below. 
 
 SECT. IV. Effaying of Ores in general. 
 
 ESSAYS are chemical operations made in fmall, to 
 determine the quantity of metal or other matter which 
 is contained in minerals ; or to difcover the value or 
 purity of any mafs of gold or filver. The former kind 
 is the fubjed of the prefent fe&ion ; the latter is treat 
 ed under the word ESSAYS, in the order of the alpha 
 bet. 
 
 Before eflays of ores can be well made, a prelimi 
 nary knowledge of the nature of the feveral metallic 
 minerals ought to be attained. Each metal has its 
 proper and improper ores, which have peculiar cha 
 racters and appearances : hence perfons accuftomed 19 
 fee them, know pretty nearly by the appearance, 
 weight, and other obvious qualities, what metal is con 
 tained in a mineral. A good eflaycr ought to be very- 
 intelligent in this matter, that he may at once know 
 what the proper operations are which are requifite to 
 the effay of any given mineral. 
 
 As metals are very unequally diftributed in their 
 ores, we (hould be apt to make falfe and deceitful ef- 
 fays, if we did not ufe all poffible precautions that the 
 proportionable quar.t'ty of metal produced by an eflay 
 
 {hall 
 
C 3JG 1 
 
 ft all be nearly the medium contained in the whole 
 ore. This is effected by taking pieces of the mi 
 neral from the feveral veins of the mine if there be 
 feveral, or from diirerent place-; of the fame vein. 
 All thefe minerals are to be ihaken t-ge her with 
 their matrixes. The whole is to be well mixed toge 
 ther, and a convenient quantify of this mixture is to 
 be taken for the eilay. This is called the lotting of the 
 ore. 
 
 As eflays, particularly the fir[t, are generally made 
 in fin all, eiTayers have very fmali weights corresponding 
 to the v/e glits ufed in the great; that is, to the quin 
 tal or hundred pounds weight, to pounds, ounces, 
 drams, Sec. The erTay quintal and its fubdivifions 
 vary according to the difference of weights in diffe 
 rent countries; and this occafions feme confufion 
 wlitn thefe weights are to be adjufted to each other. 
 Tables of thefe weights are found in treatifes of e& 
 faying ; and particularly in that written by Schlut- 
 ter, and translated and rendered more complete by 
 Hellot, which contains all the details neceifary for ths 
 fubjecl. 
 
 The cuftom is to take, for the eflfay quintal, a real 
 weight of a gros, or a dram, which in France is equal 
 to 72 grains; but as the whole dram reprefents 100 
 pounds, each grain reprefents a pound and a fraction 
 of a pound ; and hence feme difficulty and a confufion 
 arife in making the fubdivifions. A better method is 
 that of Mr Hellot, which is to make the ficTitious or 
 efiay quintal equal to 100 real grains, and then each 
 grain reprefents a real pound. This effay quintal, is 
 Sufficiently exact for ores of lead, t*n, copper, iron, 
 antimony, bifmuth, and mercury. But for ores of iil- 
 ver and gold, another representation is convenient : for 
 thefe metals, as Mr Hellot fays, are generally in fo 
 fmall quantity, that the button or fmall piece of meul 
 obtained in the eflay could not be accurately weighed 
 ii" JDQ real grains were made to reprefent a quintal ; 
 
 anc| 
 
C 357 ] 
 
 and the difficulty of feparnting the gold- from fo finall 
 a quantity would be ftill greater. Ti'jeic mo^Kies have 
 induced Mr Hellot to ufe for thefe or us a fictitious 
 quintal 16 times bigger ; that is, equal to 1600 real 
 grains, which repreient 1600 ounces ; thnt i c , loolb. 
 or quintal. The ounce being reprefemed by a. grain, 
 its feveral fubdivifions muft be reprefented by fractions 
 of a grain. Thus 12 grains of the -fictitious quintal 
 correfpond with ? \ of a real grain (*) ; and this lat 
 ter quantity may be accurately weighed in eilay balan 
 ces : which when well made are fenfible to a much left 
 weight. See (EJky)~Q*\,k*<St. 
 
 When a quintal of aa ore to be efluyed has been 
 weighed, and lotted, as we defcribed above, it is to 
 be roafted in a left under a muffle. It is to be wafned, 
 if necelfary ; and, in fhort, the fame operations are to 
 be made in fmall which are ufually done in great. Ad 
 ditions alfo are to be made, and in proper proportions, 
 according to the peculiar nature of the ore. The fluxes 
 generally mixed with the e flays in ore are three, four, 
 or five parts of black flux ; one, two, or three parts of 
 calcined borax ; and one half of that quantity of de 
 crepitated common fait. The more refractory the ore 
 is, the more neceifary is the addition of thefe fluxes: 
 then the whole mixture is to be fufed either in a forge 
 or in a melting or elfay furnace. 
 
 To make eifays well, all poflible attention and ac 
 curacy are to be employed. This object cannot be too 
 much attended to ; for the leaft inaccuracy in weigh 
 ing, or lofs of the fmalleft quantity of matter, might 
 caufe errors, fo much greater as the difproportion be 
 twixt the weights employed and thofe reprefented is 
 greater. The moil minute accuracy therefore is n ?- 
 ceifary in thefe operations. For inlLmce, the eflay- 
 
 * The pounds, of which 100 are here fuppofed to make a 
 quintal, aie called Paris pounds, one of which contains 1269 
 Troy grains, 
 
 balances 
 
C 353 ] 
 
 balances ought to be fmall, and exceedingly julh The 
 cie ought net to be weighed till it has been reduced 
 to grofs powder fit for roaiMng ; becaufe fome of it is 
 always loft in this pulverization. When the ore is 
 roafted, it ought to be coveied with an inverted teft ; 
 becaufe moil ores are apt to crackle and difperfe when 
 firft heated. To make the fufion good and complete, 
 the preciie degree of fire which is requillte ought to 
 be employed ; when it is finiihed, the crucible ought 
 to be tfruck two or three times with lome inihument, 
 to facilitate the difengagement of the parts of the regu- 
 lus from the fcoria, and to occafion their defcent and 
 union into one button of metal. The crucible ought 
 not to be broken, nor its contents examined, till it is 
 perfectly cold. 
 
 Upon breaking the crucible, we may know that the 
 fufion has been good, if the fcoria be neat, compact, 
 and equal ; if it has not overflowed or penetrated the 
 crucible ; if it contain no metallic grains ; and if its 
 furface be fmooth, and hollowed in the middle. The 
 regulus or button ought to be well collected, without 
 holes or bubbles, and to have a neat convex furface ; it 
 is then to be feparated from the fcoria, well fcraped 
 and cleaned ; and, laitly, is to be weighed. If the ope 
 ration has been well made, its weight fhows the quan 
 tity of metal which every real quintal of ore w*ll yield 
 in the great. If the perfect fuccefs of this effay be in 
 any reJpect doubtful, it ought to be repeated ; but the 
 beft method at all times is, to make feveral eifays of the 
 fame ore. Some jinall differences are always found, 
 however well the effays may have been made. By ta 
 king the medium of the results of the feveral opera 
 tions, we may approach as nearly as pcilible the true 
 product oi the ore. 
 
 Lyftly, as mines are not worked, nor founderies 
 
 eftablifned (which cannctbe done without ccnfiderable 
 
 expence), till the ore has been eifayed, 10 or 12 real 
 
 pounds of the ore ought to be previouily eiTayed : and 
 
 4 elTayer* 
 
[ 359 ] 
 
 eflayers ought to be furnifhed with neceflary furnaces 
 and inftrumeats for thefe larger eflays. 
 
 In Part II. to the feveral articles of the ores of me 
 tals, we (hall add the mod approved method of eiTay- 
 ing thefe ores. We fliall here only further obferve in ge 
 neral, that the methods commonly practifed for eflay- 
 ing ores of imperfect metals, and femimetials efpeci.illy, 
 are infufficicnt to procure the whole quantity of metal 
 contained in ores, or even fo much as is obtained in the 
 imelting of large quantities of ores ; and that there 
 fore the refult of eflays is not to be coufidered as the 
 precife quantity contained in an ore, but generally 
 only as an inaccurate approximation to that quan 
 tity. M. Gellert afcribes one caufe of the want of 
 fuccefs of thefe operations to the alkaline falls em 
 ployed as fluxes to the ores, by which moil metal 
 lic calces are partially foluble, but more efpecially fo 
 when any of the fulphur of the ore remains ; which, 
 by uniting with thefe falls, forms a hepar of fulphur 
 which is the moft powerful of all folvents. He propo- 
 fes therefore to omit the black flux, and other alkaline 
 ihlts, and to add nothing to the ore bil powder of 
 charcoal and fome fufible gbifs. This method, h- 
 fays, he learned from Mr Cramer, and has himfelf 
 ufed with much fuccefs in the eflays of iron and cop 
 per ; but finding that other imperfect metallic fubftan- 
 ces could not fuftaUi the heat necelfary to effect the 
 fufion and vitrification of the unmetallic parts of the 
 ore without being partly diflipatecl, he found it ne- 
 ceffary to add in the eflays of theie latter metallic mat 
 ters fome borax, by which the fufion might be com 
 pleted wi chiefs heat. As we confider this as a confl- 
 derable improvement in the art cf eilaying ores, we 
 (hall, to the articles of the feveral ores, add not only 
 the procefies commonly prefcribcd, but alfo thofe of 
 Mr Gellert, according to the method here mentioned. 
 
 G g PART 
 
E S&> 3 
 PART II. 
 
 Containing 
 
 A SUMMARY DESCRIPTION OF THE PRIN 
 CIPAL ORES OF .EACH METAL, 
 
 AND 
 
 The Methods of Effacing them. 
 
 SECTION I. 
 Ores of Gold 
 
 i. X RO3ERLY fpeaking, no ores of gold exift: 
 for as this metal cannot be allayed with arfenic, 
 nor with fulphur, it is never found directly minera- 
 lifed by thefe fuj>ftances, as the other metals are. In 
 the fecond place, if it be mineralifed indirediy by 
 the union it contracts with other metals naturally 
 <v>-ibined with fulphur and arfenic, fo i'mall a 
 quantity of it only is found in thefe ores, that 
 they fcarcely even deferve the name of improper ores of 
 gold. 
 
 Hence gold is found either in its natural Rate, of 
 a certain degree of purity, porTdled of all its proper 
 ties ; or engaged with fome other metals in certain 
 minerals. 
 
 The gold which is found alone is called native or 
 virgin gold. This is generally incrufted, and fixed in 
 different kinds' of ftones, principally in flints and quartz. 
 Mr Cramer fays, that ihe yellow 'brilliant fpots of the 
 blue ftones called lapis lazuli, are native gold ; but 
 thefe are very fmall. 
 
 TjolS is alfo found in fat and muddy earths ; and 
 .Mr Cramer affirms, that fcarcely any fand can be 
 
 found 
 
found which does not contain gold ; but he ac 
 knowledges, at the fame time, that the quantity is too 
 imall to compenfate for the expence of obtaining it. 
 
 Laftly, the large ft quantity of native gold is to be 
 found in the fands of fome rivers. It is chiefly collected 
 in hollows at the bottom of thefe rivers, and at their 
 feveral bendings. The gold is collected in thefe places 
 by a natural operation, fimilar to that of wafliingof ores. 
 
 A confiderable quantity of gold is in the fands of 
 feveral rivers in France : fo that perfons who collect 
 it find enough to compenfate their trouble. Mr 
 Reaumur, in a memoir that he gave in the year 1718 
 concerning the rivers of France which contain gold, 
 enumerates ten of them: namely,, the Rhine, the 
 Rhone, the Doux, the Ceze, and the Garden ; the 
 Arreige ; the Garonne ; two dreams which flow into 
 tl;e Arreige, called Fernet ancf Benagues ; laftly, 
 the Salat, the fource of which is in the Pyrenean 
 mountains. 
 
 The Ceze is the river which furrrifhes the largeft 
 quantity of gold at certain times. Mr Reaumur ob- 
 ferves, that its particles are larger than thofe of the 
 Rhine and of the Rhone ; and fays, that*!n fome days 
 a peafant will find gold to the value of a piftole, and 
 in others will fcarcely find any. 
 
 The native gold 'found in rivers or elfewhere is ne 
 ver perfectly pure, or of 24 karats. It always con 
 tains a certain quantity of allay, which is generally 
 filver. The gold of the French rivers, according to 
 Mr Reaumur's trials, was found to be from 18 to 22 
 karats, that of the Ceze being the loweft, and that of 
 the Arreige being the pureft. 
 
 Although gold, however, as above obfervecl from. 
 Macquer, cannot be directly dillblved by fulphur, yet 
 it probably may be mineralifed by the intervention of 
 other metallic matters. Thus, although no proper 
 ere of gold exifts, yet it is found in feveral mineral 
 fubftances, in which it is always accompanied, as. 
 G g 2 Cramer 
 
[ 3*2 .3 
 
 Cramer affirms, with a much larger quantity of ftlver j 
 to which hitter metal that author attributes its mine- 
 ralifed (late. Tlie minerals containing gold are blend, 
 cupreous and arfcnical pyrites* ore of antimony, cin 
 nabar, white ore of arienic, vitreous and other filver 
 ores, and the lead-ore called galena. 
 
 Gold is more frequently embedded in quartz than 
 in any other matrix ; but is alfo fc.und in limeftone 
 and in hornblerd. Gold mines are in general very 
 precarious, as they do nrt form regular veins, nor is 
 the gold unifoimly diftributed through a matrix. 
 
 Becher and Cramer think, that no fand is entirely 
 free from gold. The yelloxv, red, black, and violet- 
 coloured ferruginous fands, are faid to contain moil 
 , gold. Mr Hellet relates, that in 1 1 eflays of one kind 
 of fand, from a quintal, or 921,600 grains, were ob 
 tained each time iSrom 848 to 844 grains of noble 
 metal, exclufive of the gold which remained in the 
 fcoria ; and that of the metal thus obtained, two-thirds 
 were gold, and the remaining third was filver. He 
 fays, that parcels of fand taken up at very final! 
 diftances from each other contained very unequal pro 
 portions of gold. 
 
 The gold found in fands is generally lefs pure than 
 that which is imbedded in a folid matrix. Reaumur 
 fays, that a piece of gold, weighing 448 ounces, was 
 ftiown to the Royal Academy at Paris, which was 
 found upon eflay to have different finenefs in different 
 parts of the mafs. 
 
 2. Ores and earths containing gold may le ejjaycd\)j 
 the methods directed for the extraction of gold from 
 large quantities of thefe auriferous matters, (fee Part 
 III.) : or they may in general be e flayed by being fufed 
 in a cupel or teft, placed under the muffle of an effay- 
 furnace, or in a crucible placed in an air furnace, with 
 eight or ten times their quantity of lead if they be eafily 
 fufible, and with a larger quantity of lead if they he 
 difficultly fufible ; and by fcorifying the caithy matters, 
 
 while 
 
[ 3^3 ] 
 
 while the lead becomes impregnated with the noble 
 metal. Thefe operations are entirely fimilar to thoie 
 employed for the feparation of filler from its ores by 
 precipitation with lead ; a detail of which fee fubjoir.cd 
 under the JeB'ion ORES of SILVER, \_Prcceffes I. III. 
 IV. V. VI.]. Thefe metals are afterwards to be fe- 
 parated from the lead by cupeilation, in the manner 
 direcl'ed in the article ESSAY (of tks value of Jil-ver 
 and of gold.) The gold is then to be feparated from 
 the filver by the procefles deicribed in the article 
 PARTING. 
 
 The quantity of le;id to be added to the ore in 
 this efiliy mud be fuch as renders the fcoria very thin, 
 that the whole gold may be imbibed by the lead. 
 Some iron ores containing gold cannot be reduced 
 into a. fcoria fufficiently thin with 16 times their 
 quantity of lead, unlefs the heat be at the fame time 
 conGderably increafed. When the ore is exceedingly 
 refractory, the fcorification ought to be promoted 
 by adding to it four times its quantity of tartar, twice 
 its quantity of nitre, and four times its quantity of 
 litharge. This mixture is to be put into a good eflay- 
 crucible, and covered with the fea-ialt. The cru 
 cible is to be fet in a forge-hearth, and expofed 
 gradually to heat, till the fcoria has acquired fuf- 
 ficient fluidity, aiid the lead has imbibed the noble 
 metal. 
 
 See the methods which have been u fed fir effaying aurl* 
 fffous fandsy under Pait III. 
 
 SECT. II. Ores of P latins. 
 
 PLATIN.A is very rare, and has been but lately dif- 
 eovered. As, like gold, it cannot be allayed with 
 iulphur or with arfenic,. probably no ore, properly fo 
 called, exifts of this metal. Accordingly in the only 
 mines of platina which we knov\, namely, the gold 
 mines of Santafee near Carthagena, the platina is found 
 native like the gold, and in its metallic ftate,, 
 
 O g 3, SE.CT,, 
 
SECT. III. Ores of Sl/ver. 
 
 i. NEXT to gold, filler is the metal moft fre 
 quently found in its metallic (late, that is, not mine- 
 rulifcd by fulphur or by arfenic. This filver, called 
 alfo native or virgin, generally affects ibme regular 
 torm, and confifts of filaments or vegetations of va 
 rious figures. It is found in form of plates, of fibres, 
 or of grains, or crydallized. It lies generally in quartz, 
 flint, fpar, flate, cobalt, and in filver ores. It is fome- 
 times enveloped in a thin ftony cruft. It is generally 
 allayed with Some gold : but filver, like all the other 
 metals, is much more frequently found mineralised by 
 fulphur and by arfenic. 
 
 Three principal proper ores of filver are known, 
 which are very rich, but very rare. Thefe are, 
 
 1. The vitreous fiver ore. This ore has no deter 
 minate figure, and has nearly the colour, foftnefs, and 
 fufibility of lead. It is very heavy, and contains three 
 quarters of its weight of pure filver. In this ore the 
 filver is mineralifed by fulphur alone. Some expert ar- 
 tiits imitate it very well by combining fulphur with fil 
 ver by fuficn in a crucible. 
 
 This ore, according to Cronftedt, is eitl er in form 
 of plates or of fibres, or is cryftallized, or has no de 
 terminate figure. It may be imitated by adding about 
 five parts of fulphur to one part of melted filver ; in 
 which operation moft of the fulphur is confumed ; or 
 it may be imitated by expofing a plate of filver red- 
 hot to the fumes of burning fulphur. 
 
 2. The hcrny or corn ous Jilver ore. This ore is fo 
 called from its colour and femitranfparency, by which 
 it refembles horn or colophony. When Suddenly heat 
 ed, it crackles, as altnoft all ores do, and melts 
 with a gentle heat. Two-thirds of it are iilver, which 
 is mineralifed by fulphur ard arfenic. This ore is very 
 rare. Wallci ius fays, after Woodward, that it is found 
 at Johaun-GeorgeivStadt in Saxony, 
 
 Corneous 
 
Corneous ore has various colours ; white, pearly, 
 brown, yellow, greenifti, or reddifh. It is foliated 
 and feniitraniparent. It is fom^what ductile, and fu- 
 fible with the rlame of a candle. When heated, it emits, 
 as Wallerius lays, a fulphureous and blue flame, and, 
 accrrding to Cramer, alf> a very fmall quantity of an 
 arfenical fume- Wallerius fays, that it contains two 
 thirds of filver, with a confiderable quantity of ful- 
 phur, and a fmall quantity of arfenic. Lehman thinks 
 that it is filver united with a little arfenic. But Mr Cron- 
 ftedt fays, that it is a lima correa, or filver combined 
 with marine acid ; ard that it is incapable of being 
 decompofed but by rubitances which can unite with 
 that acid. This latter opinion feems to be the m"ft 
 probable ; as the ore, according to its dei'cription, is 
 firnilar to luna cornea, and as it cannot be imitated by 
 any mixture of ful phur and of arfenic with filver. The 
 blue flame, and the fmell {lightly arfenical, which are 
 emitted from heated corneous ore, are alfo obfervable 
 from every combination of marine acid v/ith a fub- 
 ftance containing phlogifton. 
 
 3. Red filler ore, called alfo roficlare. Its colour 
 is more or lefs red ; it is fometimes cryftallized, very 
 heavy, and is> futible like the abovementioned ores. 
 In this ore the (ilver is mineralifed by arfenic and by 
 fulplur, but chiefly by the former. It alfo contains 
 a little iron, and furnifhes two-thirds of its weight of 
 filver. Its red colour may proceed either from the 
 iron it contains ; rr from the mixture of arfenic and 
 fulphur ; or, laftly, from the p tracular manner in 
 which the arfenic is united with the hlver, an example 
 of which we h,ive in the red precipitate cf filver made 
 by the neutral arfenical lalt. 
 
 Red Jifo-.r ore is either plared or f lid, or cryftal- 
 lifed, and frequently femitraniparent. Its colour is 
 various, ircm a dark grey to a deep red, according to 
 the proportions of the two mineralifine iubftances. It 
 crackles and breaks in the fire, exhales an arfenical 
 
 fume, 
 
C 35 J 
 
 fume, and is readily fuied. It is found generally in 
 quartz, fpar, cryftal, horneblend. 
 
 Befides the three filver ores above defcribed, the 
 following ores contain filver mixed with other me 
 tals. 
 
 1. Greyfther ore. This contains copper and filver 
 mineralifed by avfenic and fulphur, and generally more 
 of the former than of the latter metal ; but as it is va 
 lued chiefly for the filver, it has been generally enume 
 rated among ft filver ores. 
 
 2. White fdver ore is an arfenical pyrites containing 
 filver. 
 
 3. Black fifoer ore contains fulphur, arfenic, copper, 
 iron, fometimes lead, and about a fourth part or filver, 
 according to Wallerius. 
 
 4. Plumofe Jiher ore is white or black, ftriated like 
 plumb-alum, or like ore of antimony. It is filver mi 
 neralifed by fulphur, arfenic, and antimony. 
 
 5. Peel-blend. In this blend filver, gold, and zinc, 
 are mineralifed by fulphur, probably by intervention 
 of iron, by which the gold and zinc are rendered ca 
 pable of uniting with the fulphur. 
 
 6. Silver is frequently found in galena ; and fome 
 times in martial pyrites ; in the red ore of arfenic ; in 
 various ores of copper, lead, tin, iron, and efpecially 
 eobah ; in Iknds ; in ye//otv or red earths / in black 
 and blue bafaltes ; and alfo in jlrata of Jl ones which 
 do not appear externally to contain any mineral fub- 
 ftance. 
 
 7. Liquid fifoer ore or guhr of filver, is a grey or whi- 
 tifa liquid mafs, which contains, as Wallerius fays, 
 either native filver, or ferae fluid fubftances capable of 
 producing it. Mr Cronfledt mentions, in the Swe- 
 difh Memoirs, a water flowing through a mine in 
 Norway containing filver. Another inftance is al 
 fo mentioned of a (ilver gtihr, in the A%. Erud. UpfaL 
 1720. 
 
 8.. Mr 
 
C 367 J 
 
 8. Mr Von Jufti pretends, that he has found filver 
 mineraltfed by an alkaline fubjlance ; but he has not 
 fpoken Sufficiently diftinftly concerning it, to know 
 whether he means a fa;ine or earthy alkaline mat 
 ter. Henckel alfo pretends, that by treating calcare 
 ous earth or certain clays with pyrites, filver may be 
 obtained. 
 
 2. Ores ofjilver may le ejfaycd by the fame me 
 thods which are employed for the extraction of that 
 metal from large quantities of ores ; which methods 
 are different, and fuited to the different qualities of 
 the different ores. See Part III. Or, in general, ores 
 and earths containing filver may be effayed by the fol 
 lowing proceffe c , which are copied from Dr Mortimer's 
 Englith edition of Cramer's Art of ejjciying metals. Part 
 ILProcefs I. 
 
 PROCESS I. 
 
 To precipitate Siher by meant of Lead from fufillt 
 Om. 
 
 "-Pouao the ore in a very clean iron mortar into 
 fine powder : of this weigh one docimafttcal centner 
 or quintal, and eight of the like centners of granula 
 ted lead. 
 
 " Then have at hand the docimaftical teft, which 
 mud not as yet. have ferved to any operation ; pour 
 into it about half of the granulated lead, and fpread 
 it with your finger through the cavity of it. 
 
 " Put upon this lead the pounded ore ; and then 
 cover it quite with the remainder of the granulated 
 lead. 
 
 " Put the teft thus loaded under the muffle of an 
 efTay-rurnace, and in the hinder part of it ; then make 
 your fire, and increafe it gradually. If you look thro* 
 the holes of either of the fliders, you will foon fee that 
 the pounded ore will be raifed out of the melted lead, 
 
 and 
 
and f\vim upon it. A little after, it will grow clam 
 my, melt, and be thrown towards the border of the 
 left : then the furface of the lead will appear in the 
 middle of the teft like a bright difc, and you will fee 
 it fmoke and boil : fo foon as you fee this, it will be 
 proper to diminifh the fire a fin all matter for a quar 
 ter of an hour : fo 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, fmoking and boiling 
 with great violence. The furface of it will then di- 
 minifh by degrees, and be covered over with a mafs 
 offcorias. Finally, have at hand an iron hook ready 
 heated, wherewith the whole mafs muft be ftirred, 
 efpecially towards the border; that in cafe any fmall 
 parcels of the ore not yet diffolved fhoukl be ad- 
 Kerent there, they may be brought down, taking 
 great eare not to ilir any the leait thing out of the 
 teft. 
 
 " Now, if what is adherent to the hook during the 
 ftirring, when you raife it above the teft, melts quick 
 ly again, and the extremity of the hook grown cold is 
 covered with a thin, fmooth, (hining cruit ; it is a fign 
 that the fcorjfication is perfect ; and it will be the 
 more fo as the fald cruft adherent to the hook fh.ill be 
 coloured equally on every fide : but in cafe, while the 
 fcorias are ftirred, you perceive any confiderable clam- 
 minefs in them, and when they adhere in good quan 
 tity to the hook, though red-hot, and are inequally 
 tinged, and feem dufty or rough with grains inter- 
 fperfed here and there ; it is a fign that the ore is not 
 entirely turned intJ fcorias. In this cafe, you muft 
 with a hammer ftrike off what is adherent to the hook, 
 pulverize it, and with a laddie 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 fcoria 
 has acquired its perfetfion and the abovementioned 
 qualities. This once obtained, take the teft with a 
 
 pair 
 
C 369 ] 
 
 pair of tongs out of the fire, and pour the lead, toge 
 ther with the fcoria fwimming upon it, in^o a cone 
 made hot and rubbed with tallow. Thus will the firit 
 operation of the procefs be performed, which does 
 not commonly indeed laft above three quarters of an 
 hour. 
 
 " With a hammer ftrike the fcorias off from the re- 
 gulus gror/n cold, and again examine whether they 
 have the characleriftics of a perfect fccrifkation ; if they 
 have, you may thence conclude, that the iilver has 
 been precipitated out of the ore turned to fcorias, and 
 received by the lead. 
 
 " When the fccrifkation lafts longer than we men 
 tioned, the lead at laft turns to fcorias or litharge, and 
 the filver remains at the bottom of the veffel : but tho 
 lire muft be moderately fupplied, and the yeflels be 
 extremely good, to produce this effect ; for they fel- 
 dom refift the ftrength of the fcorias long enough : 
 fo that the whole fcorification may be brought to an 
 end ; which has afterwards this inconveniency, that the 
 filver is cliffipated by grains in the final! hollows of the 
 corroded or,e, and cat; hardly be well collected again, 
 "when the ore has but little filver ia it. Nay, there is 
 dill more time to be confurned to obtain the perfect 
 deftruclion of the lead, by means of the combined 
 aftions of the fire and air, becaufe the fcorias fwim- 
 ining at the top retard it confiderably. 
 
 " In this procefs, the fulphur and the arfenic of the 
 filver-ore, when the ore is broken fmall, and extended 
 widely in a fmall quantity, are in parteafily diffipated 
 by the fire, and in part a'oforbed by the lead ; the 
 lighter part of which, iwimming upon the heavier, be 
 comes very clammy by means of the fulphur which is 
 in the ore ; but -when this is difljpated by the violence 
 of fire, it turns into glafs. or fcoriaa: but when arfe 
 nic is predominant in the ore, the plumbeous part 
 turns immediately into a very penetrating and very fu- 
 fible glttfs, having a diifolving efficacy, unlefs the ar- 
 
 Tenic 
 
t 370 3 
 
 feme lies hidden in a white pyrites or cobalt. For this 
 reafon, the fixed part of the ore, which is no filver, is 
 diflolved by that glafs, melts, and aflumes the form of 
 fcorias. The unmetallic earths and the pure copper 
 or lead ores thereto adherent are of this kind. The 
 filver then remains immutable ; and being freed of theie 
 heterogeneous bodies, which are partly diffipated and 
 partly melted, it is precipitated and received by the 
 remaining regulus of lead. Therefore this procefs 
 completed by three diftinct operations; viz. i. By 
 rcafting. 2. By fcorificadon. 3. By the melting pre 
 cipitation of the filver, which is the refult of the two 
 former operations. 
 
 " The ore muft be pulverifed very fine, in order 
 to increafe the furface, that the diffipation of the vo- 
 latiles and the difiolution by litharge may be fooner 
 effected. This pulverifmg muft then be done before the 
 ore is weighed, becaufe there is always fome part of 
 the ore adherent to the mortar or iron plate on which 
 it is made fine ; which part being loft, the operation 
 is not exact. Erker was in the right when he pre- 
 fcribed eight centners of lead tor the fubduing of fu- 
 fible ores. Neverthelefs, it muft be owned, that this 
 quantity is fuperfloous in fome cafes. However, as 
 the fluxibility of the filver-ore depends upon the ab- 
 fcnce of ftones, pyrites, &c. it is eafy to fee, that 
 there are an infinite number of degrees of fluxibility 
 \vhich it would be needlefs to determine exactly, and 
 nioft commonly very difficult to determine by the bare 
 fight. Befides, a little more lead does not render the 
 procefs imperfect ; on the contrary, if you ufe too 
 fmall a quantity of lead, the fcorification is never 
 completely made. Nay, there are a great many ores 
 containing fulphur and arfenic in plenty, that deftroy 
 a confiderable quantity of lead ; fuch are the red fil- 
 ver-ore, and that wherein there is a great deal of the 
 Heel-grained lead-ore. If the fire muft be fcmetimes 
 diminished in the middle ( the procefs, it is in order 
 
 4 to 
 
C 37< ] 
 
 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 overftrong j for then the 
 furface of the veffel which is contiguous to the lead 
 contracts cavities, or, being totally confirmed by fmall 
 holes, lets the regulus flow out of it. The veffels that 
 are moft fubject to this inconvenience are thofe in 
 the materials of which lime, plafter, and chalk are 
 mixed. Nay, thefe bodies, which are in their nature 
 refractory, being eroded during their fcorification, at 
 the fame time communicate a great clamminefs to the 
 fcoria ; fo that a great quantity of the mafs remains 
 adherent to the teft, in the form of protuberances, 
 when you pour it out ; whereby a great many grains 
 of the regulus are detained." 
 
 PROCESS II. 
 
 TH E regulus obtained by the procefs I. contains all 
 the iilver of the ore, and the unfcorified part of the 
 lead. The filver may be afterwards feparated from the 
 lead, and obtained pure by cupellat'wn ; which procefs 
 is defcribed under the article ESSAY (of the value of 
 Silver.) 
 
 PROCESS III. 
 
 If the Jilver-ore cannot be ivajhed clean, or if it be ren 
 dered refraftory by a mixture of unmetallic earths andjlones* 
 the fcorification of thefe earth y matters frequently can- 
 not be completed by the procefs I. Cramer therefore 
 directs, that fuch ores (hall be treated in the following 
 manner. 
 
 " Bruife the ore into an impalpable powder, by grind 
 ing in a mortar ; to a docimaftical centner of it add a 
 like quantity of glafs of lead finely pulverifed ; for the 
 more exactly thefe two are mixed cogether, the more 
 
 H h eafily 
 
t 372 3 
 
 cafily the fcorification afterwards fucceeds. Pat this 
 mixture, together with 12 centners of lead, into the 
 left, according to procefs I. then put the teft under the 
 muffle. 
 
 " Make firft under it a (Irong fire, till the lead boils 
 very well, when you fee it fo, diminiih the violence 
 of the heat, as was directed in the firft procefs ; but 
 keep it thus diminifhed a little longer : then, finally, 
 again increafe the fire to fuch a degree, till you per 
 ceive the figns of a perfect fcorification and fufion. See 
 t/j: w/jote prr.cefs I. Now this procefs lafts a little 
 longer than the foregoing, and requires a greater fire 
 towards the end. 
 
 " It fometimes happens that a very refractory ore 
 cannot be dilfolved by litharge ; and that a mafs, 
 which has the clamminefs of pitch, fwims upon the 
 regulus and upon the fcorias themfelves which are al 
 ready fubdued in part : when you fee this, Ihut the 
 vents of the furnace to diminifh the firg ; then gently 
 touch this refractory body with a fmall iron cold hook 
 to which it will immediately ftick ; take it off foftly, 
 not to lofe any thing; pound it into a fine powder, 
 adding a little glafs of lead, and put it again into the 
 teft; then continue the fcorification till it is brought 
 to its perfection. But you mud always examine the 
 fcoria of your refractory ore, to fee whether there 
 may not be fome grains of regulus difperfed in it ; for 
 fometimes the fcorias that grow clammy retain fome- 
 thing of the metal; which if ycu fufpect, pound the 
 fc< nas into a fine duft, and thus the grains of metal 
 \vill appear if there are any left, becaufe they can never 
 be pounded fine. The (liver is feparated from this 
 regulus by cupelling, as in Prrcefs II. 
 
 " All earths and (tones are refractory in the fire ; 
 for although fome of them melt naturally in the fire, 
 as thofe that are verifiable do ; neverthelefs all the 
 others, a very few excepttd, melt much more diffi 
 cultly than metals, and never become fo thin in the 
 
 fufion 
 
E 373 1 
 
 full on as is required for the fufficient precipitation of . 
 a precious metal. But litharge itfelf does not con 
 veniently diilolve thefe refractory matters by the help ; 
 of fire alone, unlefs you add fome mechan ; cal mixture 
 to them ; for the very moment the faid litharge pene 
 trates through the interftices of the refractory ore, 
 and begins to difiblve it, a tenacious mafs is produced, 
 which hardly admits any farther dilution by the li- , 
 tharge. You may fee it plain, if you make coloured 
 glaffes with metallic calces : if you pour carelefsly upon 
 them a calx that gives a colour, you will never obtain 
 that they may be equally dyed on every fide, even al- . 
 though you fh< uld torture them for whole days toge 
 ther in a great fire. Nay, glafs already made can never 
 be diluted by only pouring falts and litharge upon it. . 
 Wherefore you muft ufe the artifice of glafs-rnakers, 
 who, in the making of the mod perfect glailes, take 
 great care, before they put the fpecies of their ingredi 
 ents into the fire, to have a mechanical mixture pre 
 cede, or at leaft accede, during the fufion itfelf, which 
 is done here by pounding glafs of lead mixed with the 
 ore ; but if you think that your glafs of lead is not fufH- 
 ciently fufible, you may add to it litharge melted firlt, 
 and then pounded into a fine powder. 
 
 " As this fcorification requires a longer and a greater 
 fire than the foregoing, and as a greater quantity of 
 litharge is moreover requifite to fubude the refractory 
 fcoria; it is eafy to fee why a much greater quantity 
 of lead muft be ufed here than in Procefs I. ; and, 
 although lefs lead is often fufficient, it is neverthelefs 
 proper always to ufe the greateft quantity that can be 
 neceifary ; left, for inftance, it fhould be necefTary to 
 try fo many times the lead alone to make it evident how 
 much filver the lead when alone leaves in the cuppel. 
 Nor need you fear left any thing of the filver be taken 
 away by the lead, provided the cuppels be good, and 
 the cuppelling duly put in the execution ; for you can 
 hardly collect a ponderable quantity of filver out of the 
 
 c'olle&ed 
 
C 374 3 
 
 collected fume of the lead, which rifes during the 
 cuppelling, as well as out of the litharge that is with 
 drawn into the cuppeL" 
 
 PROCESS IV. 
 
 If the ore le rendered refractory ly p\rites, Cramer 
 directs that the filver fhould be precipitated by lead 
 in the following manner. (Art of AJfa^in^ Part II. 
 prcc. 4.) 
 
 " Break your ore into a rough powder, and put a 
 centner of it into the tefti put upon this another teft 
 in the manner of a tile ; put it under the muffle hardly 
 red hot : increafe the fire by degrees. There will 
 always be a crackling : which being ended, take away 
 the upper teft ; for when the veflels have been red- 
 hot about one minute, the ore ceafes to fplit. Leave 
 the ore under the muffle till the arfenic and the ful- 
 phur are for the mod part evaporated ; which you 
 will know from the ceifation of the vifible fmoke, of 
 the fmell of garlic, or the acid ; then take away the 
 teft, and leave it in a place not too cold, that it may 
 c col of itfelf. 
 
 ^ PoxiT onf, without s.ny d&Spatteo, the roafte<l 
 ore, and with a kriiie take away what is adherent to 
 the veflel ; pound it to a mod fubtile powder, and 
 grind it together with an equal weight of glafs of 
 lead ; and, "finally, fcorify the whole collected ore in 
 the fame teft wherein the tefting was made, unlefs it 
 has contracted chink?, as was described in Procefs III. 
 
 " Remarks. Yellow pyrites-ores contain a very 
 great quantity of fulphur, even greater than is necef- 
 fary to faturate the metal that lies hidden in them. 
 For which reafon this fuperfluous fulphur diffipates in 
 a middling fire ; but if it had been mixed with lead, 
 it would have rendered it refractory, nor could it af 
 terwards be diffipated from it without a confiderable 
 detraction of the lead. The white arfenical pyrites 
 
 turn 
 
C 375 J 
 
 i 
 
 turn alfo a great quantity of lead into glafs, on Ac 
 count of the abundance of the arfenic they contain. 
 For which reafon theie ores muft be previoufly roafted, 
 that the fulphiir attd arfenic may be diflipated. Nor 
 need, you fear left any part of the filver be carried 
 away with' the arfenic ; for when arfenic is feparated 
 from any fixed body, by a certain degree of fire, it 
 carries nothing of that body away with it." 
 
 PROCESS V. 
 
 Stiver may be precipitated from its ore ly cupellailon only, 
 in the following Procefs, given by Cramer. [Art 
 Part II. Proc. 9.] 
 
 " Pound one centner of ore ; roaft it in the man 
 ner directed in the laft proceis j beat it to a rnoft 
 fubtle powder, and if it melts with difficulty on the 
 iire, grind it together with one centner of litharge, 
 which is not necellary 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. 
 
 " Put a very large cuppel under the muffle ; roaft 
 it well firft, and then put into it fixteen centners of 
 lead : when the lead begins to fmoke and boil, put 
 upon it one of the fa : d portions with the fmall paper 
 it was wrapt up in, and diminifh the fire immediately^ 
 in the fame manner as if you would make a fcorifica- 
 tion in a teft, but in a leiler time. The fmall paper, 
 which turns prefently to allies, goes oft of itfelf, and 
 does not fenfibly increafe the mafs of the fcorias. The 
 ore proceeding therefrom is caft on the border, and 
 turns to fcorias very foon. Jncreafe the fire asrain im 
 mediately, and, at the fame time, put. another por 
 tion of the ore into the cuppel, as was juft now faid. 
 The fame eiTe&s will be produced. Go on in the 
 H h 3 fume 
 
C 376 ] 
 
 fame manner, till all the portions are thrown in and 
 confumed in the lead. Finally, deilroy the remaining 
 lead with a ftronger fire. 
 
 " The filver that was in the ore and in the lead 
 will remain in the cuppel. If you deduct from it the 
 bead proceeding from the lead, you will have the 
 weight of the filver contained in the ore. If the ore 
 employed was eafy to be melted, all the fcoria vaniflies; 
 but if it was refractory or not fufible, all the fcoria 
 does not always go away, but there remains fome- 
 thing of it now and then in the form of duft. A great 
 many ores and metals may be tried in this way, ex 
 cept only fuch as fplit and corrods the cuppels. 
 Tbere are likewife fome of them which muft be pre- 
 vioirfly prepared in the fame manner as is required 
 to render them fit for going through a fcorification. 
 See the for tgo'mg Proceffes. 
 
 " Remarks. The ore thrown at feveral times up 
 on lead boiling in a cuppel may be diflolved without 
 the foregoing fcorification ; but this is very far from 
 having an equal fuccefs with all kinds of ores ; for 
 there are ores and metals which refifl very much 
 their diifolution by litharge ; and which being on this 
 account .thrown on the border, are not fufficiently 
 diflolved ; becaufe the litharge fteals away foon into 
 the cuppel. Neverthelefs, there are fome others which 
 varnfh entirely by this method, except the filver and 
 gold that was contained in them. 
 
 " A previous roafting is neceiTary, firft, for the 
 reafons mentioned, and then tecaufe the ore thrown 
 upon boiling lead fhould not crackle and leap out ; 
 for, having once pafTed the fire, it bears the moft fud- 
 <Jen beau" 
 
 PROCESS 
 
C 377 1 
 
 PROCESS VI. 
 
 Sifos r may le precipitated out of tie Jame bodies as ^?rc 
 mentioned in the foi > going procejjes by fcorsjicaiiun in a 
 irucib.e. [^Craner, Proc. 15. _j 
 
 " The body out of which you intend to precipitate 
 filver muit be previoufly prepared lor a fcorification 
 by pounding and r< ailing, as mentioned in the tormer 
 pioceffes. Then in the fume manner, and with the 
 fame quantity of lead, put it into a crucible itrictly 
 ex.iniint-d, that it be en- ire, folid, not fpeckled with 
 black fp ts, like the fcoria of iron, efpecially at its 
 interior parts, and capable of containing three times 
 as much. Add befides glals gall and common fait, 
 bo:h very dry, and enough, that when the whole is 
 rml.e^t the fairs may fwim at top at the height cf 
 about halt an inch. 
 
 " Put the crucible thus loaded in a wind-furnace ; 
 fhiU it clofe with a tile; put coals round it, but net 
 higher thvm the upper border of the crucible. Then 
 light them with burning coals, and increafe the fire 
 till the whole melts very thin, which will be done by 
 a n. dJiing fire, maintained always equal, and never 
 gri-'er; leave it thus for abc ut one quarter of an 
 hoi'-, that the fcorification may be perfectly made. 
 Take oil the tile and ftir the mafs with an iron wire, 
 and a little after pour it out into the mould. When 
 the regulus is cleaned from fcorias, try it in a teft by 
 cuppelling it. 
 
 *' Remarks. The fcorification of any ore what 
 ever, or of ar.y body fetched out of ores, may indeed 
 be reade by this apparatus, as well as in a telt under 
 a muffle : but it ferves chiefly to the end that a greater 
 quantity of metal may be molted om it with profit. 
 cu may put many common pounds of it at one 
 fii'^;e time into the crucible; but then you need not 
 cbierve the preportion of lead prefcribed m the fore 
 going 
 
i 378 3 ' 
 
 going procefs; nay, a quantity of lead two or three 
 times lefs is fufficient, according to the different qua 
 lities of the object. But the mafs will certainly he 
 fpl't, unleis you choofe a very good crucible ; for there 
 is no veflel charged with litharge that can bear a 
 ftrong- tire having a draught of wind, without giving 
 way through it to the litharge, 
 
 " You add glafs-gall and common fait, that they 
 may forward the fcorificauon, by f\vinirmn<?; at top ; 
 for the refractory fcoria rejected by the litharge, and 
 adhering between this and the.falts that i'vim at top, 
 is foon brought to a flux, and the precipitation of the 
 filver is thereby accelerated. Thty alib hinder in 3, 
 rr.-anner a fmall burning coal fallen into the crucible, 
 from fetting the litharge a boiling, which troubles 
 the operation ; for the litharge or gla s of lead, efpe- 
 cially that which is made without any addition, 1!> 
 foon as the phL gifton gets into it, rifes into a foamy 
 mafs, confiding ot a multitude of fmall bubbles very 
 difficult to be confined, unleis the phlogifton be en 
 tirely confurred, and the litharge reduced to lead, 
 which fom crimes rife*; above the border of the veffel." 
 
 The corneous ere, if it really be, as Cronftedt fays, 
 a luna con <:a, ought to be treated in feme of the me 
 thods directed for the reduction of luna cornea. See 
 
 PROCESS VII. 
 
 Slfaef atid gold may le extracted from their ores ly mercury, 
 
 A new method of extracting the precious metals by 
 means of amalgamation with mercury has lately been 
 introduced into Germany. The attraction between 
 thefe has indeed been known from the moft remote 
 antiquity ; Vitrivius inform us, that by this means 
 gold might be recovered from embroidery and old 
 cloaths 5 ajid Pliny mentions the gilding of brafs and 
 
 other 
 
C 379 3 
 
 ether metals by the fame means. From time imme*' 
 inoiial mercury has been made ufe of in the ftrcaming- 
 for gold, in order to purify and collect together the 
 gold duft which is difperfed in the fands ; and almoft 
 a;l nations who practice this ufe the fame procefr. The 
 gold fand, after being wafhed, is r.rh.u-ated with quick- 
 Silver, and the fuperfluoiis metal feparated by ftrain- 
 ing through leather. By the mineis it was ufed in a 
 fimilar manner ; the ftones containing gold being fi-ft 
 poundd and then triturated in mills along with the 
 mercury. But it was foon found, that in thefe mills 
 there was a large quantity left behind in the refiduum, 
 fo that it was neceflary to fubject what was left to the 
 action of fire ; on which account the mills were deem 
 ed unneceffary, and are now almoft every where dif- 
 ufed. The procefs of extracting gold and filver by 
 amalgamation, however, was looked upon to be eflen- 
 tially deficient, by reafon of an opinion which prevailed 
 among the chemifts, that mercury could not diflolve 
 either of thefe metals except in their pure and perfect 
 ftate ; whence it was fuppofed, that a great quantity 
 which fire could have extracted was left by the mer 
 cury. This opinion was fupported by the moft cele 
 brated metallurgies, as Schlutter, Gellert, Wallerius, 
 and Cramer ; whence it became generally believed, 
 that amalgamation would never aniwer in great opera 
 tions. But of late Baron Inigo Born has not only de 
 mon ftrated that this can be done to great advantage, 
 but has actually introduced it, notwithftanding that 
 fome difficulties were thrown in his way. The fol 
 lowing is an account of the methods which have been 
 practifed for feparating gold and filver from their ores 
 by means of quickfilver. 
 
 This procels was introduced into fome of the mines 
 of Mexico in 1566 by Don Pedro Fernandez de Ve- 
 lafco, and in 1571 into fome of thofe of Peru by the 
 fame perfon ; and from thence it quickly fpread thro* 
 all the mines in the fouth and north-eaft parts of Ame 
 rica, 
 
C 
 
 nca, infomuch that it is almoft the only method ufed 
 in that part of the world for extruding theie metals. 
 The richer ores, however, are purified by fufion with 
 lead; and our author informs us, that ft rmerly the 
 poorer kind of ores were certainly L.roxvn away, and 
 when the method cf amalgamation as introduced into 
 Peru, the old hairows were ieaiched for the ores which 
 had been rejected as ufelefs, but were now put to the 
 quickfilver. 
 
 In the year 1588, Don Juan de Corduba, a Spa 
 niard, applied to the court of Vienna, propofmg to 
 extract filver from its ores, whether poor or rich, 
 by mercury, and in a fhort fpace of time. He made 
 fome experiments upon different kirds of ore, which 
 on a fmall fcale fu receded very well, but on attempt 
 ing it with 20 quintals of it he failed ; and as Lazarus 
 Erker, who was en pl< yed to give in a report concern, 
 ing it, difapproved of the method, it was net purfued 
 any farther. The reafons alleged in Baron Born's 
 book f < r this failure are, that he did not calcine his 
 ore : that he did not uie any fait ; and that the weather 
 was too cold ; thr.ugh this laft circumftance might have 
 been remedied had Corduba attended to it. 
 
 Another Latin and anonymous account of the mode 
 of amalgamation is preferved armngthe records of the 
 aulic chamber. It is directed to the emperor, but the 
 year in which it was written is not mentior ed. Ac 
 cording to the account given by the author of this pa 
 per, he had examined the mines of Guatimala in New 
 Spain, and made fome ufeful regulations for them. 
 He directs the ore to be calcined in furnaces like lime 
 kilns, the fire being kept up according to the nature of 
 the ores, after which they are to be reduced to powder 
 in mills or ftamps. The pulverifed matter is then 
 pafled through fine iron fieves, and put into earthen or 
 copper veflels by 10 or 20 quintals at a time ; more 
 or lefs fait being; mixed with it according to circum- 
 ftances. The light-coloured ore requires 50 Ib. to 
 
 every 
 
C 3" 3 
 
 every thoufand, and the darker fomewhat more. To 
 this mixture are to be added five pounds of dry tartar, 
 two pounds of pulverized horn, and three pounds of 
 brick-duft. Some kinds of ores require but a fmall 
 quantity of thefe additions. 
 
 After the mixtures are put into the boilers, as much 
 water is added as will make the whole of the confidence 
 of pafte moderately thick; the vefTels mull be expofed to 
 funlliine, or kept in a place warmed artificially, adding 
 more water when the matter begins to dry; and it 
 muft be ilirred up three or four times a-day. At the 
 expiration of three or four days, various colours appear 
 upon the furface. After this 15 Ib. of brimftone is to 
 be added to every thoufand pounds of ore, and the 
 whole worked over again ; but this addition is by the 
 baron corifidered as quite fnperfluous. Laftly, loolb. 
 or lefs of quickiilveris added, according to the nature 
 of the ore ; the whole mafs is carefully worked over, 
 and left at reft for 10 hours. A fire muft next be 
 kindled under the boiler, and the matter it contains 
 triturated or ftirred for two days together ; keeping it 
 always fufficiently diluted by a proportional quantity 
 of water. It is, laftly, allowed to reft for 12 hours, 
 and then dried. 
 
 When this operation is fuccefsfully performed, if 
 the ores be rich, par tides of amalgam will be feen in 
 it: thefe are collected, waflied out, and kept for fur 
 ther ufe, the leavings being carried to a place fit for 
 walhing over. This place ought to be on the flope of 
 an hill, where a kind of pit is dug out and lined with 
 brick and mortar, and ought to be large enough to 
 contain 25 quintals. A ftrearn of water is then made 
 to run up^n it, and the matter ftirred without inter- 
 mifiion. The fuperfluous water runs over the rim of 
 the pit, and carries off the lighter ftony and earthy 
 particles, the heavy amalgam remaining at bottom. 
 This is then to be mixed with the fmall clots already 
 mentioned, which were taken out of the mafs origi 
 nally 
 
t 3^ 3 
 
 nally, atid prefTed through a cloth made of hemp cr 
 coarfe linen. The quickfilver, which comes through 
 clean, is kept for farther ufe ; the remainder diftilled off 
 in proper veflels, and the remaining filver melted into 
 ingots. B> th ; s method it is faid that even very poor 
 ores are worked to advantage, the expence being very- 
 moderate. 
 
 The following method of extracting gold from its 
 ores is very much recommended by our author : '* The 
 auriferous land, which contains gold grains and gold- 
 duft, is concentrated by wafhing; and without any 
 calcination goes to the abovtirientioned waihing-pit, 
 which for this purpofe need not be fo laige. On its 
 upper part is fixed a fquare launder, about 12 feet 
 long, covered in the bottom with a woollen cloth, in 
 order to retain ai : y part of the gold-duft which may be 
 carried over with the water and ftuff gently ithred in 
 the pit. When the water carries off no more mud, but 
 runs clear, the farther fupply is to be flopped ; the 
 water in the pit is pumped or taken out wit.i buckets ; 
 the coarfer fand in the bottom is leparated or fcraped 
 off by hands : and the finer heavieh 1 land at the bottom 
 is mixed with quickfilver. Then it is fqueezed through 
 a piece of cl^th ; the quickfilver comes off vvithoutany 
 gold, which feparated from the fand remains as an 
 amalgam, and is pure after the remaining quickfilver 
 has been evaporated. The fand and heavier duft re 
 maining on the launder is wafhed and treated in the 
 fame manner. 
 
 " The auriferous ores and loadftones, however, 
 which rife from different mines, are calcined like filver 
 ores, more or lefs as the nature ol their matrixes will 
 direct. Then they are ground and rifted ; and the au 
 riferous ftuff, thus prepared, is put into heaps, expo- 
 fed to the funlhine, ani worked and turned about for 
 three or four days. It requires no fait. Afterwards 
 fulphur, and atlaft quickrtlver, are added and mixed 
 \vith, it. There is no occafion for fire under the veffel 
 4 in 
 
in winch it is triturated, except in winter; and two 
 Jays after, though not dried, it is immediately carried 
 to the wafliing pit, and treated like the amalgam of 
 filver. 
 
 " This method of extracting gold and filver is fo 
 certain and fafe, that when other method*; of amalga 
 mation extract only one ounce of gold and filver, this 
 produces three or four from the pooreft ores in a fhor- 
 ter time and with leis expence." 
 
 P. Jofeph Acofta tells us, that at Potofi 6000 or 7000 
 quintals of quickfilver are annually confumed in the 
 drefling of the ore, not to mention what is recovered 
 from the leavings of the firft wafhing. Thefe leavings, 
 called lamas t are burnt-in particular furnaces in order 
 to extract the remaining quickfilver; and there are 
 upwards of 50 fuch furnaces near Potofi and Tarapa- 
 ja. The ore refined there amounts, according to the 
 bed information, to the immenfe quantity of 300,000 
 quintals. Only about 2000 quintals of the quickfilver 
 are recovered, which (hows alofs of about two pounds 
 of quickfilver on every quintal of ore. The ores are 
 of different natures, and in proportion to the filver 
 they contain require more or lefs quickfilver. That 
 which contains moft, requires naturally the greatefl 
 quantity of quickfilver ; though feme of the workmen 
 pretend that there is a kind which contains very little 
 filver, and yet requires a great deal of mercury : but 
 whether this be owing to the ignorance of the work 
 men, or to the mercury being abforbed by feme other 
 matter, is not generally known, The ore is firf'c pul 
 verifed in mills, and then patted through iron or brafs 
 lleves. The mills will grind, when properly regulated, 
 .30 quintals in the fpace of 24 hours. The pulverifcd 
 matter is put into heaps in the open air, and fait is 
 mixed with it in the proportion of 5 to 50 quintals of 
 the ore, in order to macerate and cleanfe it of its im 
 purities, that the quickfilver may the more readily 
 amalgamate with the m^tnl. Upon thefe heaps, and 
 I i while 
 
C 3*4 ] 
 
 while they are {Hiring, the quickfilver is preffed 
 through a cloth. Before the invention of fire-places, 
 the ore was repeatedly kneaded with quickfilver in 
 wooden trough's and formed into large round maf- 
 fes, which were left in that form for two days ; after 
 which they were worked again, until the metals 
 appeared to be embodied together, which took from 
 9 to 20 days ; but it was afterwards fougad that 
 heat aflifted the operation fo far, that by means of 
 proper ovens the fame might be accompliihed in five 
 or fix days. When the quickfilver has taken up the 
 filver, and wholly feparated it from its matrix the lead 
 and the copper, the ovens are opened, the matter is 
 taken out, and the quickfilver expelled and recovered 
 in the following manner. The mixture is put into wa 
 ter troughs, and ftirred therein by means of mills and 
 water-wheels, by which the earthy and extraneous par 
 ticles are waflied away, and the amalgam fettles at the 
 bottom. The fediment looks like fand. It is further 
 wafhed over in flat plates, and perfectly cleanfecl ; what 
 goes off with the water is collected for further ufe un 
 der the name of relates. When the amalgam is be 
 come clean and bright by this method, it is put into 
 a cloth and fqueezed out. This uncombined quick 
 filver runs off, and the remaining body of amalgam 
 contains five parts of quickfilver and one of folid metal. 
 It is made into mafTes named pinnas, having the form 
 of a fugar loaf, hollow within, and weighing about 
 100 pounds. They are expofed to a ftrong fire in 
 order to expel the quickfilver, after being put into pots 
 covered with earthen heads. The filver ftill appears 
 in the form of amalgam, but is reduced to one fixth of 
 the former weight. Its texture is fpongy, and the 
 quality of the metal fo fine, that the filver-fmiths can 
 not work it, neither can it be formed into coin, with 
 out an alloy. Baron Born obferves, however, that it 
 is only cold amalgamation which produces filver of 
 fuch uncommon finenefs ; by hot amalgamation it is 
 
 generally 
 
C 385 3 
 
 generally alloyed with copper, which cannot be parted 
 from it without cupellation. 
 
 The moft circumftantial account of the amalgama- 
 t'on of filver ore is that of Alonzo Barb*. He divides 
 the ores into two claifes : I. thofe which are bed treat 
 ed by fiie and fufion ; and, 2. fuch as are moft fit for 
 amalgamation. Thofe called pacos and tacana, may be 
 amalgamated ; but that none of their richer contents 
 may be loft, it will be bed to combine them with lead, 
 and proceed by cupellaticn. The former of thefe ores 
 has no luftre or brightnefs. It is faid to be of a reddifh 
 yellow, foft and friable ; feldom rich in filver, and 
 moftly valuable on account of its being eafily got from 
 the mine. Tacana is a rich filver ore, of a black co 
 lour, fometimes of a grey or of an afh-colour; or a 
 brown, rich, filvery earth. 3. TheJ&wo is too rich 
 for pulverifation and amalgamation, and is therefore 
 fimply melted down with the tacana. This feems to 
 be the fame with the horn-filver ore ; and is defcribed 
 as almoft entirely confiding of native filver, .of a black, 
 grey, of greenifh-white colour. Barba fays that they 
 found at Potofi fome plomo of a cinnabar colour, which 
 they had not feen any where elfe ; but Baron Born 
 thinks that here he has miftaken the red filver ore for 
 another fpecies. Ffezier aflerts, that in what he calls 
 the plomo ronco^ the native fiiver appears upon rubbing 
 orfcratching it, and that it gives vhite and very pure 
 filverby fimple fufion without any amalgamation. In 
 the imperial cabinet at Vienna, there is a fpecimen 
 weighing about a pound, of black hern filver ore from 
 Potofi, en the po;iilied fur-face of which the virgin 
 filver appears very plainly. 4. The maclacado (virgin 
 iilver or gold grown in the matrix in the form of wire 
 or hair), is amalgamated in the mortar. 5. Theforo- 
 ehes (lead ores containing filver), are melted along 
 with the rofichr and conclifo, two kinds of red filver 
 ore, 6. The negrlllos (grey copper and white filver 
 ' I i 2 ores) 
 
L" 386 3 
 
 I-LV.O) may be refined by amalgamation, though they 
 are mere tit for fire. , 
 
 Belides this cUifnflcation in ftich as are fit for fire, 
 and thofc for amalgamation, the ores require further 
 to be ibited into inch as require the addition of par- 
 ticulur iubftances for their amalgamation. Vitriol is 
 generally -hurtful,, efpecially when fait is added to the 
 vitriolic rj'-js ; and it requires the addition of iron, 
 tin, lead, and lime, in order to counteract its effects ; 
 tut in ii.iae caks k is of fervice, and promotes amril- 
 f>;arnation. The calcination of vitriolic ores is of no 
 ierv : ee, but rather the contrary, as it difengages tlie 
 vitriol, and brings on a vitriolic efilorefcence. It may, 
 however, be feparated by wafliing till the water comes 
 off liiftelels and fweet. The amalgamation Is difturb- 
 f.il by fill pint r, bitumen, and antimony, only by the 
 irnoi thnefs and needle-like figure of the particles, 
 which reduce the quickfilver to a kind of duft. The 
 ores mixed with tliefe always run into reguli, and mud 
 therefore be put into a ilrong calcining fire ; if melted 
 without calcination, they would rim entirely into drofs 
 -and fcoria. 
 
 The finer the ores are pounded Co much the better ; 
 and after putting the powder thro' a fine fieve, the coar- 
 ier part goes again to the mill : they ought to be pre- 
 viouily burnt, in order to affift the operation of grind-* 
 ing. The beft method of obtaining fine powder is by 
 warning over ; but as this is very apt to pack and turn 
 clammy, it ought to be mixed with fand. 
 
 The ores are known to be fufficiently calcined by 
 their change of colour and lofs of brightnefs. Barbii 
 tells us, that all bright ores mull be calcined, but with 
 great care, that no vitriol may be difengaged, as that 
 proves injurious to the amalgamation ; but baron Born 
 lays, that one of the greateit objects in the calcination 
 of the Hungarian ores is to decompole the fulphur into 
 vitriol, as promoting the decomposition of the fait, 
 The amalgamation, is like wife promoted by burning 
 
[ 3*7 3 
 
 and calcination, in as far as it promotes the pulveri 
 zation of the ore, a; d affifts the action of the quick- 
 filver ; but it is chietiy ufeful in the black and grey 
 filver fire-:. It can only be determined by circuwiitan- 
 ces whether it be better to pulverize the ores before 
 or afu-r calcination. Their value is bei't known by 
 pounding them previous to calcinati< n. The ftufFmuit 
 be conftantly ithred during the time it is calcining, and 
 fome powder taken irom the n.afs to be tried with 
 qulcklilver and fu;t. The thickening of the quick- 
 iilver, and the gram of the iluff, jfhowwhat additions 
 are r.ecefiary, or whether calcination be completed 
 or not. When ores are calcined i'i lumps, the fire does 
 not act eqa.il!) up n all their pms; though this me 
 thod is attended with the advantage of lofing much 
 lefs dull, as well as faving the expcnce of (tamps and 
 mills. 
 
 Ores cannot be calcined in reverberatory furnaces, 
 as the heat would run it together, and part of tie 
 metals themfelves would be carried off by the ftrong 
 current of air and the violent fmoke. Barba recom 
 mends a furnace of an oblong fquare figure, with three 
 vaults over each other; the fire is put in the lower- 
 mo ft, and the ore into the two upper ones. The heat 
 circulates by means of lateral openings in the walls, 
 and is let out on the back without a flue. The heat is 
 graduated by registers and dampers on the outfide. 
 Whatever kind of furnace, however, is ufed, fome of 
 the ore \vi 1 have clotted, and muft therefore be ground 
 to a fine powder; but to prevent as much as poflible 
 thefe inconveniences, the hard ores ought to be cal 
 cined before they go to the mill, and the foft ones af 
 ter, but with proper additions. Tne irony ores, which 
 re lift fhe fire longer, are calcined with an addition of 
 fulphur, or of fulphureous and antimonial matter pro 
 portioned to the iron they contain ; but fulphureous 
 and antimonial ores require to be calcined with the 
 fcoi ia of iron. Arfenical ores, or thofe mixed with 
 I i 3 orpiment 
 
C 388 j 
 
 OrpinVent and fandarac, are calcined with lead glance ; 
 afcd tkofc mixed with white or black bitumen muit be 
 calcined with in n fcoria or pounded limeftone. 
 
 The impurities of ores, and the additions proper to 
 be made to them, are determined by pounding them 
 coarfely, and throwing them upon a heated plate of 
 iron. If t.he fmoke be white or black, it mows a mix 
 ture of bitumen of thefe colours ; if yellow, it {"hows 
 crpiment ; if red, fandarac ; if greeniih yellow, ful- 
 phur. 
 
 Salt ought net to be ufed in the calcination of ores 
 as it would calcine the filver; and the duration of the 
 calcining muit be determined by the change of colour 
 which the ores undergo by calcination by themielve^, 
 ;did the brightnefs they afilime by trituration with 
 quickfilver. It is alib a mark of fufficient calcination 
 when ar-itimonial and fulphnreous ores no longer fend 
 out a difagreeable fmoke ; if the thick and black fmoke 
 of bituminous ores become white ; and if the filver in 
 the ft a if appears in white glittering fparks. Vitriolic 
 ores may alfo be calcined in the fame manner ; but they 
 require a longer time with the addition of alum and 
 fait: they, however, require no farther addition in 
 the fubfequent operations ; and in the courfe of four 
 days all their filver will be taken up by the quickfilver. 
 l^efs quickfilver will alfo be loft ; for as there is no ccca- 
 iion for the frequent turning and working of the heap, 
 a very fmall part of it only can be turned into ufcleis 
 duft. Vitriolic ores ought always to be well waftied 
 with water before they are calcined ; and if there is 
 ftill a fufpicion of their being vitriolic, they muft be 
 tr e J by quickfilver : if it takes a lead-colour, the ftuft 
 muft be \vaflied till iron put into it no longer takes a 
 copper colour. The lixivium is kept as an uieful ad 
 dition to fome ores. 
 
 Amalgamation, according to Alonfo Burba's me 
 thod, is performed in three ways, viz. in heaps or 
 caxons, in the boiler, and in mortars. 
 
 1-. In 
 
[ 3*9 3 
 
 1. In heaps. Before the operation takes place in 
 the large XT ay, an eflay is made of three or four pounds 
 of the fine fifted powder taken from the general quan 
 tity ; and according to the produce of this he calcu 
 lates that of the whole. He tries it alfo with quick- 
 filver, tti know perfectly the method he is to follow, 
 and the additions that are to be made. In this ei- 
 fay the following method is adopted: I. The mat 
 ter is elix--vted, to extract the vitriol if there be any. 
 2. One pound of the lixiviated matter is tried with 
 quick filvcr and fait, carefully obferving the colour and 
 ks change. If ihe quickfilver a Humes the appearance 
 of illver filings, and thefe quickfilver flakes become 
 thinner and thinner, it proves that the amalgamation 
 goes on fuccefsfully, and that the<e is no occafion for 
 any addition. The whole is ilirred from time to time, 
 till the qaickfilver feems to diminifh, and recover its 
 natural form, but without dividing into fmall globules; 
 after which fee matter is to be waihed, as all the iilver 
 is by that time complete!} taken up. The ores of 
 Verer.guela de Pacages are treated only with quickfilver 
 and fait, and yield their full produce. 
 
 When the ore turns black, iron is added ; when of 
 a light lead-colour, tin ; if a dark lead-colour, lead ; 
 and if of a y^liowith or gold colour, lime. The three 
 firft of thefe are ftyled, by Baron Born, " very idle 
 and ufelefs additions." The ore frequently divides 
 into fmall and powdery globules, in confequence of 
 the hardnefs of the minerals, or from too much ftir- 
 r'ng ; but this may be prevented by calcination before 
 it is reduced to powder, or by lefs ilirrinsr. In a great 
 many operations, however, this quickfilver dull can 
 fcarcely be avoided. It ferves the workmen as an in 
 dex of the progrefs they have made, or fometimes as 
 a direction how to operate ; and has different names 
 according to the caufe by which it is produced ; as 
 quickfilver duft, the dud of addition, and filver duft. 
 The firft of thefe arifes fimply from too great divifion, 
 
[ 390 ] 
 
 and is white without any quicknefs, frarcely moving 
 when the master is itirred with warer ; it frrks fome- 
 what to the bottom, and runs into gl -hales when bro 
 ken between the fingers. .The lecoud is produced by 
 the amalgam uf lead and tin; and, vv^en prefled be 
 tween the fingers, unites wi'b the q-uickiilver which 
 had bcgu.i to combine with the filver. The third 
 ir-.m the amalgam of filver : it finks toward 
 the coarser fluff 0:1 the bottom, nd floats about in 
 fi .'. < -s of different uzes ; turwi. ;<r ii'.to an amalgam when 
 rubbed or prelTed between the lingers. Ail of thefe 
 a r e produced chiefly when there are lead, marcaf'te, 
 and iiony ores in the mixture ; or by vitriol of copper, < 
 which i^ particularly productive of this minute divilion 
 of the quicklilver. They are produced a-fo by too 
 plentiful an ad.Mi'inn of fait, which thickens the water 
 an I prevents the ddfcent of the particles of quick- 
 filver. 
 
 According to the produce of the effa-y the large 
 heap is regulated. It is fit ft wetted with water, and 
 mixed with ;t due proportion of fait ; but at the be 
 ginning only one third of the quickiilver and one half 
 of the lead and tin are added. It is tinned over once 
 every day during the two fiill: days, becaufe the quick- 
 filver being then uncombincd wou-d be apt to be 
 driven off iu fmall globules, and a great wa'le occa- 
 fioned. The heap is IrkewHe too much cooled by the 
 addition of too much qinckfilver at once ; fo that it is 
 better to put it gradually to the other matters. The 
 lead and tin are always thrown into the heap along 
 wMi the quickfilver ; but too much of either is hurt 
 ful, by deadening the quickiilver, and preventing the 
 amalgamation. All thefe additions, however, muft vary 
 according to circumltances ; obferving that the quanti 
 ties added muft alwayc be lefs and lefs in proportion as 
 the amu!;<am advances to perfection. The matter 
 fhould be !;ept rather dry than otherwife, and two, 
 parts of amalgam be in the heap to one of fluid qmck- 
 
 iilvex 
 
I 59 1 , 3 
 
 fi!ver. Too great an abundance of this fluid mafs is 
 very detrimental, en account of the quantity of quick- 
 filver duft which it occafions ; and if the other ingre 
 dients are accidentally wafted, the duft of addition will 
 be changed into qu'idfiher duft ; which having very 
 little weight, will be poured off along with the water. 
 But when lime is added, the whole mult be mixed at 
 (nice, and the entire heap turned over two or three 
 Jays, till the quickfilver be added. Too much lime 
 prevents the union cf the two metals, and is an incon 
 venience which cannot be remedied. 
 
 The heaps are frequently turned and worked over 
 after the firit two days, which is attended with feve- 
 ral advantages ; as that the quickfilver is thus heated ; 
 more thoroughly mixed with the matter, and the fil- 
 ver is purified by the frequent rubbing. The heaps, 
 however, are fubject to various accidents, owing to 
 the difference between the various kinds of ores, which 
 cannot always be exactly known. When the quick 
 filver is deadened by too large an addition of lead, 
 iron, tin, or lime, it lofes its oval form, and aifumes 
 a vermicular one : if iliaken in a glafs, or Other vcifv 1 , 
 without water, it adheres to the fides in threads, and 
 is unfit for taking up the filver. The beft remedy is 
 vitriol of copper, or the lixivium of vitriolic ores al 
 ready mentioned ; or powder of copper may be thrown 
 into the heap. All additions of this kind, however, 
 mud be made very cautioufiy, and in confluence of 
 experiments made by fmall effays, which determine 
 the quantity of materials to be ufed. When the heaps 
 have too much vitriol, without any correcting ingre 
 dient, the quickfilver has a leaden colour, and the 
 fmaller particles aflume a fpherical form. Iron might 
 be added to abibrb the too great quantity of vitriolic 
 acid ; but thei e is no, certain rule for the proportion 
 to be added, fo that it mult be determined by experi 
 ment, 
 
 When 
 
[ 392 ] 
 
 When the quickfilver apipears, on turning, the heaps 
 like a bunch of grapes, this Ihows an excefs of fait, 
 which prevents the quickfilver from combining with 
 the'filver : it is to be remedied by the addition of ibme 
 coarfe fluff which clsanfes the fluid. Some add allies : 
 but the beft and nioft natural remedy is alum, which 
 is found at Potofi in abundance, and whitens the fil- 
 ver. If the heap be no: turned equally, or the quick- 
 rllver added at a proper time, or if the filver do not 
 unite with it, fome of the filver will appear in a dry 
 form and lie on the coarfer fluff like a cobweb ; and 
 if not fkimmed off in time will be carried away by the 
 wafhmg water. To collect this dry fiiver, and the 
 fineft quickfilver duft, fome filver amalgama is preffed 
 upon it through a chamois fkin ; arid the whole is 
 ,once more turned and worked over. The frequent 
 turning, the heat of the climate and feafon, as well as 
 the fermentation produced in the heap by the vitriol 
 and other additions, all promote the amalgamation ; 
 but cold, neglect of ftirring, and the quickfilver aflum- 
 ing a lead colour, are againft it. It is, however, very 
 difficult to determine the maturity of the heap, when 
 all the filver is taken up, and the matter m.iy go to 
 the wafhmg ; though great inconveniences attend an 
 ignorance in this refpect. If wafhed too fo~>n, fome 
 iilver is left in the leavings: and if worked too 1 >ng 
 there is a lofs of quickfilver as well as time and la- 
 b.mi. The difficulties attending the knowledge of 
 this important point, are by our author enumerated 
 as f 'How ; " The heap may appear not to requ're any 
 additional quickfilver ; the filver daft may appear to 
 be completely coPefted ; that of quickfilver may be 
 gin to make its appearance : the amaljr.MiKi may be 
 gin to appear pure, and to fhow a gold colour: and 
 yet filver may remain in the leavings. The in oft in 
 fallible teft of the maturity of the heap, is the eifay 
 of the triturated ftuff by fire. If no filver is produced 
 thereby, then fo much quickfilver is thrown into the 
 
 heap, 
 
[ 393 ] 
 
 heap, that it may contain three parts of amalgama to 
 two of filver, or at Icaft one part of quicklilvcr to 
 two of amalg.tma. By this additional frefh quick- 
 filver, all 'he d .ft of quickiilver, ard the dry and un- 
 combined quickiilver, are perfectly collected the amal 
 gama is the heavjer for it, and finks the more readily 
 to the bottom when brought to the Waihing-tiibi 
 Some clean quickfilver is alfo put into the bottom of 
 this tub: the infide of which muft be lir-pd with iron 
 plate well cleaned, and rubbed with quickiilver;" 
 (though the laft operation feems to be quite fuperflu- 
 ous, as mercury \vill not in the leaft unite with iron 
 by rubbing.) " The fluff brought into the tub 
 muft be diluted with a great quantity of water, and 
 be ftirred round with a peftle lined with iron-plate in 
 fuch a manner that it may turn round fix times one 
 way and fix times the other, always touching the bot 
 tom ; the unconnected bodies of quickfilver and amal 
 gam are thereby to meet, to combine, and to fall to 
 the bottom. To recover the fait which had been mix 
 ed with the heap, the water muft be evaporated :" 
 but the Baron t'bferves, that at Shemnitz no fait is 
 recoverable from the lixiviam ; and if any be recover 
 ed by the Spaniards, it only ihows that they add too 
 much, and that part of the remainder is undecompo- 
 fed by the vitriolic acid. The quickfilver is feparated 
 from the amalgama much in the fame way as already 
 defcribed. 
 
 2,* Amalgamation ly boiling, \vas accidentally difco- 
 vered by Barba, in an attempt to fix qiuckfilvfer. 
 On mixing filver ore finely powdered with quickfil- 
 ver, and boiling it with water in a copper veifel, he 
 found that the metals readily united ; and thus having 
 difcovered afhorrermethod of amalgamation, he gradu 
 ally improved and introduced it into practice in Peru. 
 In this operation the boilers muft be of copper, ear 
 then or other vefiels being found not to anfwer : the 
 copper alfo muft be pure, becaufe the quickfilver would 
 
 dilTolve 
 
[ 394 J 
 
 diflblve the metals with which it is alloyed. TSey 
 muft be in the fhape of inverted cones and flat-bot 
 tomed. The under part has a rim of fix or eight 
 inches high and half an inch broad, all beat of one 
 piece. Other copper plates are fixed in the infide with 
 copper nails ; and care muft be taken that it be water 
 tight; that no quickfilver may run off; and for the bet 
 ter fecurity, the infide of the boiler may be lined with 
 lime and ox-blood. The boilers may be of any mag 
 nitude ; their upper parts being furrounded with iron 
 rings with ftrong handles, into which a crofs Aboard is 
 wedged. In the middle of this board is a hole for the 
 ipindle to move in. The fpindle is of light wood, 
 and moves on a brafs pivot in the bottom. It has 
 four wooden wings, with three or four perpendicular 
 bars alfo of wood ; the fartheft from the fpindle being 
 the (liorteft ; the nighefl fo long as to fweep the bot 
 tom. It is turned by a moveable handle on the up 
 per end. 
 
 Thefe boilers are put into an *>blong furnace, ca 
 pable of holding 10 of them ; the fire-place being in 
 the middle, and the flame and fmoke pafling under the 
 boilers, and going out at both ends of the furnace by 
 two chimnies. The fire being lighted, firft the wa 
 ter, then the fine fluff, and at laft the quickfilver, is 
 put in ; obferving always that the bottom be fully co 
 vered with quickfilver. The water muft always be 
 kept boiling, otherwife the operation may be inter 
 rupted or become tedious : on account of the evapo 
 ration, the boilers mult be fupplied with a quantity of 
 water, in fmall quantities at a time, that the boiling 
 be not checked. The fluff muil be proportioned to 
 the fize cf the boiler: if too little be put in, the. amal 
 gamation goes on too (lowly ; while too much would 
 not allow the mafs to be thick enough, or to boil with 
 iufficient freedom. Some of the amalgam is to be ta 
 ken out from time to time with a long ladle, and the 
 progrefs of the operation is judged of by-the colour. 
 4 The 
 
C 395 3 
 
 The etfay of the fluff determines whether all "the m*. 
 ver be taken out of it in this manner. Some quick- 
 diver is then thrown upon the furface of a fample of- 
 the boiled fluff, and worked round with it in a velfel- 
 two or three times. If the quickfilver rifes and takes 
 up fome of the fluff, fome filver remains ; if not the 
 whole is taken up. Then the fire is flopped, the 
 fpindle is taken out, and the water and fluff let oft". 
 The coarfer matter on the quickfilver may at all events 
 be wafli-ed in cold water, and go once more to the 
 mill. Almofl the whole of the fllver amalgama lies 
 upon the fur face of the quickfilver, immediately under 
 the (luff, fometimes four or five fingers thick ^ the fire 
 under the boilers preventing the filver from uniting 
 with the quickfilver in the bottom. This metal, when 
 poured off, muft be preiled and treated in the uiu;il 
 manner. 
 
 The advantages attending this method are, that the 
 heat promotes the union of the metals, while the boil 
 ing of the water and ft wring of the mixture with the 
 fpindle bring them more frequently in cental with 
 each other in a quarter of an hour, than they would 
 be in feveral days in the common method ; by which 
 means the whole procefs is finifhed in about 24 hours* 
 Lefs quickfiiver is alfo loft by it ; for being always co* 
 vered with water, it cannot evaporate ; and in well 
 managed and fuccefsful operations, no quickfilver dufl 
 is produced: but the greatefl recommendation is, that 
 it is not attended with any lofs of filver, fo that even 
 the pooreft ores will yield all that they contain. Bar- 
 ba looks upon the profit of this method above the 
 other to amount to 25 dollars for every heap of 50 
 quintals : even making allowance for the coals. The 
 only objections are, that both filver and copper are 
 apt to be loft by the corrofion of the copper-boilers : 
 but if the copper be pure, there is no great reafon to 
 be apprehenfive of any thing of this kind ; or, at all 
 events, the bottom of the boiler, which is conftantly 
 K k expofed 
 
C 596 ] 
 
 to the aftion of the quickfilver, may be fecii- 
 red by a copper ring three or four inches high ; and 
 the bottom itlelf may be fecured in the fame manner ; 
 fo that when corroded they may be changed for new 
 ones : or the boilers may be paved or lined with var- 
 riilhes or mortars of different kinds ; which will as ef 
 fectually prevent any lofs. While the whole is boil 
 ing, the quickfilver violently feizes on the other me 
 tal ; by which means the amalgam is filled with many 
 heterogeneous particles. Thefeare feparated by walh- 
 ing in quickfilver, on the furface of which they fwim 
 like fcoria, and may eafily be taken off, till the 
 quickfilver flic-ws its ufual brightnefs ; and as this can 
 not be done without taking off fom-2 of the metals 
 alfo, thefcum may be referved for the next operation. 
 The advantage of amalgamation by boiling chiefly 
 appears in this, that heaps, in which by too large 
 additions, the quickfilver has been totally diffolved fo 
 as to difappear, may be eafily cured by boiling them, 
 in iron or copper veflels w T ith bits of iron ; for chen 
 the quickfilver appears again in its proper metallic 
 form and brightnefs. 
 
 3. Amalgamation in mortars. It is difficult to pro 
 cure the full produce from ores which contain native 
 gold and filver either in the form of hair or wire, or 
 in larger lumps and nodules. Thefe cannot be com 
 pletely pounded, nor can they be amalgamated ; for the 
 mercury will not diffolve the large particles of gold 
 and filver ; and when they are treated by fire, the ftub- 
 borr nature of their matrices occailons a great lofs of 
 metal. The following method of treating them in a 
 mortar was discovered by a Francifcan friar. 
 
 A r."imd conical hole is cut in a hard ftone, half 
 in diameter at top, of an equal depth, and (lope- 
 ing into a truncated, or rather obtufe and nearly flat 
 bottom, of about four inches in diameter. Some 
 quickfilver is poured 5n*o it, together with a propor 
 tional quantity of fmall bits of the native metal or ore ; 
 
 after 
 
C 397 ] 
 
 after which they are triturated with an iron peftle. 
 By this violent trituration, the gold and filver combine 
 with the quickfilver ; and the finer, lighter fluff of red 
 filver ore and other filver calces, which are generally 
 found with native filver, runs ofF by means of afmall 
 launder and current of water. It is not, however, 
 fuffered to run away, but is left to fettle for common 
 amalgamation. 
 
 Mortars of the dimenfioris above defcribed being' 
 too fmall for any coniiderable quantity of ore, Barba 
 propofes to fubftitute in their place larger fton.es of a 
 concave figure, with vertical grinders, as in oil-mills ; 
 or common horizontal and parallel grinders of the grill- 
 mill. The ore and quickfilver are put between thefe 
 ftones, with a fmall ftream of water ; which, running 
 off, will carry away the lighter ftuff, whi'lft the gold 
 and filver will remain at the bottom, taken up by the 
 quickfilver. 
 
 There are feveral other methods of amalgamation 
 defcribed in Baron Born's work, as praclifed by the 
 Spaniards of South America : but as all of them agree 
 in the mod material circumstances with thofe already 
 mentioned, we ih all only farther take notice of that 
 invented by the Baron himfelf, and by him lately in 
 troduced at Shemnitz in Lower Hungary. 
 
 This method is very pompuoufly related, and at 
 great length, in his work on the fubjeft. His theory 
 contains the following particulars : 
 
 1. Quickfilver has a tendency to unite with other 
 metals and femi metals, and to quicken or animate them 
 according to certain laws of affinity which are deter 
 mined by expeiience. 
 
 2. It unites with gold, filver, copper, tin, lead, bif- 
 muth, and zinc, without heat ; but with other metals 
 and femimetah it will not unite but in a Hate of fuiion. 
 It unites with tin and bifmuth moie eafuy than with 
 gold and iilver ; and with thefe more readily than with 
 copper. 
 
 K k 2 3 The 
 
j. The vmS'pn of qukklllver with other metals is pro 
 moted by heat. 
 
 4. This u.F;5on.ij> alfo greatly promoted by mechani 
 cal comminution. 
 
 5. No amalgamation, or only a very flow and partial 
 one will take place, if the fui face of the quickfilver 
 <sr me tail ic particles be covered with a coat of hete 
 rogeneous matter ; which happens chiefly in the amal 
 gamation of ores where the fine particles of the metal 
 are involved in fulphur and arfcnic. 
 
 . 6. Hence it is necefiary to free the noble metals 
 from the &cny matter which furrotinds them, and to 
 reduce the bafer ones from their calciform to a me 
 tallic Rate, before they can be amalgamated with fuc- 
 . 
 
 7. Particles of gold and filver may be freed from the 
 fior.y mattcrjs which involve them by trituration; and 
 irom fulphur and arfenic, by calcination. 
 
 8. In calcination, feme part of the fulphur is de- 
 itroyed, and vitriolic acid difeagaged ; which, combi 
 ning with. the earthy nratters contained in the ore, as 
 well as the calces of the bafer metals mixed with it, 
 iiill leave the gold and filver involved: whence it is 
 ncceflary to employ fueh chemical agents as will free^ 
 the particles of thele metals irotri their heterogeneous 
 coat, and keep their furface as well as that of the 
 quickfilver clean, without acling either upon the gold 
 -or filver. Thefe agents are principally the mineral 
 acids, which act varioufiy according to their different 
 Features. The marine acid is mod efficacious for gold. 
 
 .or filver ores; but it would be exceedingly expenfive 
 to ufe it in its proper form, fo tjiat it is neceilary to 
 take fome method of expelling it extemporaneou^y 
 irom common fait by means of oil of vitriol. 
 
 9. The calcined ore, when pulverifed, rnufl be 
 .wetted with water, for the purpofe of diilclving ih<; 
 difengaged vitriolic acid and the earthy and m.etallic 
 
 ' Tfalts, which are produced by it in proportion 
 
C 399 I 
 
 to the fulplmr contained in the ore. Vitriol is pro 
 duced by calcination only in this proportion ; and 
 hence if the ore does not naturally contain a fuffici- 
 ency of fulphur to produce vitriol for the purpcfe of 
 decompofition, it will be neceflary to add fom -thing 
 cf this kind. Vitriol of copper or of iron will an- 
 fwer, but the former is preferable. If, therefore, the 
 pulverifed ore, which has once gone through the pro- 
 cefs of amalgamation, fhould (till appear to contain 
 gold or fiivcr, mix it with fome additional vitriol and 
 common ialt ; leave it for fome time to macerate by 
 itfelf ; asd, at a fecond trituration with quickfilver, a 
 coniiderable quantity of filver will be found in the 
 amalgama which had not been extracted in the firil, 
 though common fait had been ufed in it. Thus the 
 common fait may be decompofed in the wet way. 
 
 10. To decompofe the common fait in the dry way, 
 the ore muft be properly (lamped and lifted, and the 
 mixtures made up with a proporti- nal quantity of 
 pnlverifed common or reck fait, and then undergo an 
 adequate calcination in an open fire. Thus the com 
 mon fait will be decompofed according to the nature 
 of the mixture ; either by the vitriolic acid produced 
 by the decompofition of the fulphur, or otherwife. 
 The muriatic acid, thus difengaged, diffolves the he 
 terogeneous particles in wluch the metals are involved, 
 and allows the quickfilver to act npon them much more 
 effectually than it could have been enabled to do by 
 any mechanical comminution ; and this the more 
 fo as it takes up even thofe particles of dephlogiftica- 
 ted iron upon which the other acids arc incapable, 
 of acVirg.. 
 
 u. The calcination and corrofion of the bafer me 
 tals is indifpenfably necelTary, efpecially in a natural 
 combination of gold and copper ; for the affinity of 
 thefe two is fo ftrong, that unlefs the lat.er be per- 
 feftly calcined, or otherwife removed, very little of the. 
 K k 3 goldi 
 
Id can 1 e extracted. The reparation will alfo (v- 
 promoted by the addition of fulphurcous lubftances. 
 
 From thefe conlideracions, the Baron lays down the 
 following rules concerning amalgamation. 
 
 " i. The or&s and mixtures previous to their amal 
 gamation rnuft be mechanically comminuted, and re 
 duced to a fine powder, by Ramping, grinding-, and 
 fifting, that the iurfaccs of the particles, and their 
 points of contact, may be increafed and multiplied. 
 
 " 2. This powder muft be calcuied, that, beiides the 
 pure particles of the nobler metals, thofe which ara 
 difguifed in the ore may be difengaged and laid bare 
 by deful'phuration and calcination. 
 
 " 3. If before its calcination no common fait was 
 added, it muft be added afterwards ;' then it mufl be- 
 triturated with a proportionate quantity of qmcklilver 
 and water, long enough, arid in fuch a manner, that 
 the quicklilver,. by an uninterrupted motion of the 
 e mafs, ..may come Into repeated cc>iitac' r i: \vi'..h the 
 difengaged gold and filler particles, and take them 
 up. 
 
 *' 4. As.much depends onthe jufc-mentioned propor 
 tions, the -infpcclor, diredor, or maftcr of the' work,, 
 muft be well acquainted with the elefHve attraction of 
 bodies, that forming a jilft idea of, ar.d judgment on^ 
 their different mechanical or chemical decompofitioa 
 and combination, he may remedy and remove Tuch un-. 
 tovrard .difficulties and impediments in the prcceis as 
 may, and willfometimes, .prevent its fall fuccefs." 
 
 The vaiious fteps by which the metals are extracted 1 
 from their ores, according to the Baron's method, are,, 
 i. Stamping, grinding, and fitting. 2. Calcination^ 
 sfter which the-grinding and fiftirg muft be repeated. 
 3. Triturp.tion 4. . Wafhing of the refiduurn. 5, K- 
 liqnatibn of the amalgama. 6. He?jting of the fame, 
 7 D\ ft illation of the quickfilver preffed from the amal 
 gam. 8,. Refining of the heated amalgam. 9. Ex-. 
 
 tracling 
 
t 4QI 3 
 
 tnicting from the refidua fuch parts of the noble me 
 tals as may it ill be contained in them. 
 
 1. Stamping, grinding, and Jiftiag. The Baron reccm- 
 men .s dry ftamps and mills for this purpofe ; as wet- 
 ftarnps, he fays, " would bring on great lofs of filver 
 and expenfive coiitnv-.-inces to prevent or recover it." 
 On the other hand, E. Rafpe, the tranflator of his 
 voile, fays, that " late experiments have proved fo 
 much in favour of the wet ftamps, that they have ac- 
 
 .tually been adopted as great improvements." 
 
 Tjie contents of the ores are accurately inveftigated 
 by etiays beibre any thing is done in 'the large way. 
 The ores are delivered to the refpective mills ; the 
 fmuller ores are pafied over a brafs fieve, the mefhes of 
 which are about one-tenth of an inch wide, that the 
 finer particles may be feparated and not lent to the 
 ftamps, which would occafion fome wafte, eipecially 
 in the dry way. The finer fane! is fent direcliy to the 
 mill, and the big lumps to the ftamp. Each box, & 
 fet of ftamps, has three ftamp-heads, weighing 40 or 
 54 pounds, the fole being of call-iron. The matter 
 is every now and then wetted with water to pie- 
 vent the finer parts from flying off. When the ore is 
 fuihciently beat in the ftamps, it is afterwards fifted, 
 and the coarfe part returned to the ftamp. When the 
 coarfeft part is reduced in this manner to the fr/e of 
 coarfe fand, it is fent to the mill ; the running ftone of 
 which muft be kept clofe in a box, and nothing left 
 open but the admiffion-fannel. The millftones are a, 
 kind of porphyry, and the lieves of brafs-wire. 
 
 2. Calcination. The ore being reduced to a fuffideht 
 degree of nneriefs, is next carried to the calcining fur 
 nace ; previous to which it is again to be tried by ef- 
 fay, and to have the proper additions according to its 
 nature. When the furnace is properly heated, the 
 whole quantity of ore deftined to one furnace, about 
 30 quintals, is brought up to the top by wheel-bar- 
 rows \ and being fpread as even as may be, the proper 
 
 cruamitv 
 
quantity of fait and lime is fifted over it ; and the 
 whole turned with crooks and rakes till it be perfectly 
 mixed. The calcination is then performed in the fol 
 lowing manner: The back-door be'ng carefully ihut, 
 eight hundred weight of the matter, prepared as al 
 ready mentioned, is let down through a funnel upon 
 the upper hearth. Here it is again to be ipread and 
 allowed to dry before it is put down on the lower 
 hearth ; and as foon as this is done, another quantity 
 iS put upon the upper hearth, that the two operations 
 may regularly fucceed each other. 
 
 Our author defcribes at great length all the minu- 
 tiiE of this operation : but, as he jultly obferves, " Ex 
 perience and practice are, and omit be, the beft teach 
 ers ; [or triers are many things which iniilt be attended 
 to, and which words and defcriptions will hardly make 
 intelligible." We fhaH therefore only obferve, that the 
 calcining furnace mult be- L -epr ne/ited day and night : 
 but while the ore is fir wed down from the upper to 
 the lower hearth, the fire mud bt- kept very moderate ; 
 and during the calcination it will be neceifary to keep 
 the matter conftantry turning w tn iron rakes, the 
 combs or teeth of which are from four to eight inches 
 long. 
 
 The grinding and fifting after calcination is only 
 neceifary when the matter has run into hard indiflb- 
 luble clots during the operation ; and is performed in a 
 grinding and fifting mill, which turns by water ; but 
 which is unneceifary here to defcribe, as every pof- 
 feifor of mines wruld chcofe fuch mechanical contri 
 vances as beft fuithis purpofe. 
 
 3. Tnturatlony bo'ling, and amalgamation. After the 
 ores have bren prcperly calcined and pounded, the 
 fuccefs of the amalgamation depends moftly on the 
 proportions of quickiilver and water which are added 
 to the ftufF, and the construction of the ftirring appa 
 ratus by which the whole is kept in conttant motion 
 and mutual contact. The lighter the fluff, the mere 
 
 voluminous: 
 
C 403 3 
 
 voluminous and bulky it will prove, and confequentlj 
 the g^ld and filver will be nv re difperfed ; in which 
 cafe the quantity of quickfilver mult be proportioned 
 to the mvifs, that not with it an ding its conftant gravita 
 tion towards the bottom it may th? more frequently 
 come in contact with the gold and filver. It acts in 
 pro portion to its bulk and fur face. A larger quantity 
 is therefore advifeable, as it not only frrms a larger 
 furiace on the bottom of the veflel, but comes likewife 
 into contact with the gold and filver more frequently ; 
 nor is there any greater lofs of quickfilver tn be ap 
 prehended on that accourfc, A larger proportion of 
 fluid metal is in particular neceifary when the matter 
 is mixed with lead or antimony : for, by taking up 
 the lead, it becomes proportionably lefs active and fit 
 for the reception of gold and filver ; and turning greafy 
 by the antimony, it mull in the former cafe leave rich 
 refidua, and in the latter bring on greater lofs. It is 
 alfo determined by experience, that the excefs of 
 quickfilver never does ar.y hurt, while too faiall a 
 quantity never fails to be difadvantageous. 
 
 With regard to the conftruction of the boilers, it is 
 needlefs to be particular, as th^fe recommended by A- 
 lonfo Barba feem to be very adequate to the purpofe. 
 Heat is required ; but it is not necefTary that the mat 
 ter ihould boil, a moderate fire being fufficient for ma 
 king the metals unite. Nor is there occafion for more 
 water than what will make the matter liquid. The 
 ftirring apparatus is put in motion by the crank of a 
 water wheel, and a horizontal rack with cogs ; which 
 being properly fixed in a groove by crofs bars, Hides 
 forward and backward on brufs rollers and cafiersl 
 The cogs of this rack catch into thofe of the perpen 
 dicular trundle and fpindle of the Rirrers, which turns 
 round twice by three and an half feet motion of the 
 Hiding rack. The whole moves quicker and flovrer in 
 proportion to the box of water thrown upon the wheel ; 
 &nd the quicker motion oftliQ rack produces of courfe 
 
 a quick 
 
44 
 
 a quick turn and better trituration. The ftirrers midt 
 be circular fcgments correfponding with the fides and 
 bottom of the boiler, otherwife their motion is irre 
 gular and urif.vtisfaclory. The time of trituration, as 
 depending on the nature of the ore, muft be deter 
 mined by experience. 
 
 4. The wajh'utg of the triturated leavings or refidunm 
 is performed in large tubs, and requires no particular 
 defcription, farther than that it be continued till all the 
 fcluble matter be got out ; and for this purpofe there 
 mu (I be a contrivance for ftirring the matter all the 
 time it is waihing. 
 
 5. E ^iquation of tie qmckji!*ver and amal^ama. For 
 merly this was performed in bags made of deer-lkins, 
 ftrongly comprefled with engines for the purpofe ; but 
 this being found too expenfive, it is now done by fmall 
 quantities at a time, and prefled only by the hand till 
 the ball of amalgam yields no more quickfilver. A 
 fmall quantity always remains in the quickfilver which 
 pafles through ; and this quantity is the greater in pro 
 portion to the warmth of the amalgam when prefled. 
 
 6. The (Vijl'iUation of ike amalgam is performed per 
 defcenfum in large irm pots. The undermoft ftands 
 upright to its middle in a ft ream of cold running wa 
 ter which paries under the hearth ; the upper part 
 h,<;rdly appearing two inches above it. The amalgam, 
 made up into balls, is placed in iron cullenders fixed 
 upon a tripod let in the bottom of the lower pot, 
 and covered in the infide with a coarfe cloth. The 
 upper pot is inverted on the lower one ; and the junc 
 ture being luted, the fire is put all round the outer 
 one, and the heat pafilnpr through to the amalgam 
 quickly liquefies it, and raifes the quickfilver in vapour, 
 which condenfes in the under pot continually kept 
 cool by the ftream of water. The upper pot is kept 
 in a (trong red heat for five or fix hours ; by which 
 means the cloth is entirely converted into tinder, fo 
 that the cullenders muft afterwards be cleaned with a- 
 brafii brufh, 
 
 The 
 
C 4^5 ] 
 
 The other operations contain nothing particular but 
 what may he eafily uudcniood from what has been al 
 ready delivered. 
 
 SECT. IV. Ores of Copper. 
 
 i. COPPER is found under ground in three diffe 
 rent forms: i. Native or virgin copper diverfely ra 
 mified, which is much more rare tnan native fiiver. 
 This native copper is not ib ductile as copper purified 
 by fufions tro.n the ore (A). 2. Copper is found in : 
 form of calx, of verdigrife, of precipitates. Such 
 are the minerals called ftlky copper ores, and feveral 
 whit: and green earths. Theie matters are only cop 
 per almoft pure and but little mmeralifed, but which 
 has been corroded, diJf>lved, precipitated, calcined by 
 faline matters, by the aclion of the air, of water, and 
 of earths (B). 3. Copper is frequently in a truly mi 
 neral ftate, that is, combined with iVdphur and with 
 arfenic, with other metallic matters mixed with earths, 
 
 and 
 
 (A.) Native copper is folid ; or confuting of friable 
 maifes, formed by precipitation of cupreous vitriolic 
 waters called cement, or ziment copper ; or forming cry- 
 ftallifed cubes or grains, leaves, branches, or filaments. 
 
 (B) Calc'tform ores are either pure calxes of copper, 
 or are mixed with heterogeneous matters, i. The 
 pure or loofe friable ochre, called aeruleum montanum 
 " mountain blue," and virtde mantanum " mountain- 
 green ;" and the red indurated calx, called improperly 
 g/afs. copper ore. 2. Mixed calciform ores are thofe in 
 Wuich the calx of copper is mixed, with calcareous earth, 
 forming a mountain-blue ; with iron, forming a black 
 calx ; with g pfum, an indurated green ore, called ma/a- 
 i aod with quartz, a red ore. 
 
[ 4 o6 ] 
 
 and enveloped in different matrices (c). Thefe are the 
 true copper ores. They have no regular forms ex 
 cept they partake of the nature of pyrites. Their co 
 lours are very different, which depend chiefly on the 
 proportion of the mineral fubilancts c^-mpoiing them. 
 JL.afl.ly, in almoft all of them we may perceive green 
 or blue colours, which always indicate an erofion < T cal 
 cination of the copper. Moft copper ores contain alia 
 fome iron or ferruginous earth, to which the ochrey 
 colour is to be attributed, which might make us believe 
 them to be ores of iron. Ores which contain much iron 
 are the moft difficultly fufible. 
 
 Copper 
 
 (c) Copper is mineraltfed, I. By futybur, forming 
 tilt grey copper ore, improperly called vitreous (minera 
 cupri vitrea Wallerii). 2. By fulplmrated Iron, form 
 ing the hepatic copper ore (minera cupri hepatica Wal 
 lerii) of a brown yellow colour. It is a kind of cu 
 preous pyrites, and is called by Cronftedt minera cupri 
 pyrit-acea. Sometimes it is of a blackifh grey colour, 
 and is then called pyrites cupri grift us (minera cupri 
 grifea Wallerii ) ; fometimes of a reddifh yellow, and 
 tarniihed with blue iriies on its furface, when it is call 
 ed minera cupri/a xiirea ; when of a yellowifh green co 
 lour, it is thcpyrittt cupri jlavo-viridefctns (cuprum ful- 
 phure et ferro mineralifatum WalleriT) j and when of 
 a pale yellow colour, it is the pyrites cupre pallid e Jta<uus. 
 Moft of the above pyritaceous ores contain alfo fome 
 arfenic, but their iulphur is predominant. 3. Copper mi- 
 neralijed by jujphur, iron, and arjenic. White copper ore 
 (Minera cupri alba Wallerii). This ore contains alfo 
 fome filver. 4. Copper diffohed by vitriolic acid. Na 
 tive blue -vitriol. 5. Copper united with bitumens. Cup 
 per-coal ore. This is a pit coal, from the afhes of 
 which copper is obtainable. 6. Copper is alfo found 
 -in the mineral called kuffer nickel. 
 
 4 
 
t 407 3 
 
 Copper ores have aimed all a yellow, golden, and 
 fhiniag colour, by which they are eafily diftinguifned. 
 Some of them are coloured with irifes, and frequently 
 have fpots of verdigrife, by which alfo they are diftin- 
 gui ill able from other ores. 
 
 Many copper ores are alfo rich in filver. Such is 
 that called the white copper ore.-, the colour of which 
 is rather occafioned by arfenic than by filver, although 
 it contains fo much filver as to be enumerated by ie- 
 veral mineralogifts amongft filver ores. 
 
 Laftly, the pyrites of a golden yellow colour which 
 contains copper and fulphur, and the white pyiite* 
 which contains copper and arfenic, are confidered as 
 copper ores by feveral chemifts and naturalifts. Henc- 
 fcel and Cramer remark, that no proper ore of copper 
 is known which does not contain a. confiderable qaan- 
 tity of arfenic. 
 
 2. Ores of copper may be effayed in methods fimi- 
 larto thofe employed for fmelting of large quantities 
 of ores (Part III.}, or they may in general be eflay-ed 
 fey the following procefTes. 
 
 PROCESS I. 
 
 'To reduce and precipitate copper from a pure and fujillt 
 ort in a clofe vefeh 
 
 "Mix one, or, if you have fmall weights, two do- 
 cimaftical centners of ore beat extremely fine, with fix 
 centners of the black flux ; and having put them into 
 a crucible or pot, cover them one inch high with com 
 mon fait, and prefs them down with your finger : but 
 let the capacity of the veiTel be fuch that it may be 
 only half lull ; ihut the veflel clofe, put it into the fur 
 nace ; heap coals upon it, fo that it may be covered 
 over with them a few inches high ; govern the fire in 
 ibch a manner that it may fir ft grow flightly red-hot. 
 L 1 Sooa 
 
C 4Q* 3 
 
 Soon after you will hear your common fait crackle; 
 and then there will be a gentle hifling noife. So long 
 as thislafts, keep the fame degree : of fire till it is quite 
 over. Then increafe fuddenly the iiie, either with 
 the funnel and cover put upon the furnace, or with a 
 pair of bellows applied to the hole of the bottom part, 
 that the veffel may grow very red hot. Thus you will 
 reduce and precipitate your copper in abour a quarter 
 of an hour : then take out the veffel, and ftrike with 
 a few blows the pavement upon which you put it, that 
 all the fmall grains of copper may be collected in one 
 mafs. 
 
 " Break the veflfel, when grown cold, in two, from 
 top to bottom, as nearly as you can : if the whole pro- 
 cefs has been well performed, you will find a folid, per 
 fectly yellow and malleable regulus adhering to the 
 bottom of the veffel, with fcorias remaining at top of 
 a brown colour, folid, hard, and fhining, from which 
 the regulus muft be feparate.d with feveral gentle blows 
 of a hammer; this done, weigh it, after having wiped 
 oiFallthefilthinefs. 
 
 A foft, dufty, and very black fcoria, is a fign of a 
 fire not fufficiently ftrong. Small neat grains of cop 
 per reduced but not precipitated, and adhering ftill to 
 icorias, efpecially not very far from the bottom, an4 
 an unequal and ramificated regulus, are figns of the 
 fame thing. A folid, hard, (hining, red-coloured 
 fcoria, efpecially about the regulus, or even the regu 
 lus itfelf when covered with a like fmall cruft, are 
 figns of an excefs in the degree and duration of the 
 fire. 
 
 " Remarks. All the ores which are eafily melted in 
 the fire are not the objecls of this procefs ; for they muft 
 alfo-be very pure. Such are the vitreous copper ores." 
 (Mr Cramer means, it is prefumed, the red calciform 
 ere, called improperly glafs ore, and not the mlnera 
 cupn intrea of Wallerius, which being compofed of cop 
 per mineralifed by fulphur could not be treated pro 
 perly 
 
t 409 ] 
 
 perly by this procefs, in \vhich no previous roafling is 
 required. The fulphur of this ore would with the al 
 kali of the black flux form a hepar, from which the 
 metal would not precipitate). " But efpecially the 
 green and azure-coloured ores, and the cteruhum and 
 vlride montanurfi) which are not very different from 
 them. But if there is a great quantity of arfenic, ful 
 phur, or the ore of another metal and femimetal joined 
 to the ore of copper, then you will never obtain a mal 
 leable regulus of pure copper, tho' ores are not always 
 rendered refradory by the prefence of thefe." 
 
 PROCESS II. 
 
 70 reduce and precipitate copper out of ores rendered refrac 
 tory by earth andjlones that cannot be wafiedojf. 
 
 j 
 
 " BEAT your ore into a moft fubtile powder, of which 
 weigh one or two centners, and mix as much fandiver 
 to them. This done, add four times as much of the 
 black flux with refpeft to the ore ; for by this means, 
 the fterile terreftrial parts are better difpofed to a'fcori- 
 fication, and the reducing and precipitating flux may 
 aft more freely upon the metallic particles freed from 
 all their incumbrances. 
 
 " As for the reft, make the apparatus as in laft pro 
 cefs : but you muft make the fire a little ftronger for 
 about half an hour together. When the vefTel is grown 
 cold and broken, examine the fcorias, whether they are 
 as they ought to be. The regulus will be as fine and 
 ductile as the foregoing. 
 
 " Remarks. As thefe copper ores hardly conceal 
 any fulphur and arfenic in them, the roafting would be 
 of no effeft, and much copper would be loft. For no 
 metallic calx, except thofe of gold and iilver, improper 
 ly fo called, can be roafted, without you find a part of 
 the metal loft after the reduction." 
 
 L 1 2 PROCESS 
 
t 4 1 ] 
 
 PROCESS III. 
 
 To precipitate copper out of an ore (D) that contains 
 
 -" Do all according to laft procefs. But you will 
 find after the vefJ'el is broken, a regulus upon no ac 
 count fo fine, but Icfs ductile, wherein the genuine co 
 lour of the copper dees not perfectly appear, and which 
 muft be further purified. 
 
 J " Remarks. The fire ufed in this operation is not 
 fo. ftrong that the iron mould turn to a regulus. But 
 as copper is the menftruum of iron, which is of itfelf 
 \ery refractory in the fire ; for this reafon, while the 
 ore and the flux are moft intimately mixed and con 
 founded by trituration, the greateft part of the iron be 
 ing diiiblved by the copper, turns into. a regulus along 
 Vvith it," 
 
 PROCESS IV. 
 
 The roajllng of a pyritofe, fulpburous 9 arfenical, fenume 
 
 tallic, copper ore. 
 . 
 " BREAK two docimaftical centners of the ore to a 
 
 ccarfe powder, put them into a teft covered with a 
 tile, and place them under the mufHe of a doctmaftical 
 furnace. But the fire muft be fo gentle, that the 
 muffle may be but faintly red-hot. When the ore has . 
 decrepitated, open the teft and continue the fire for a. 
 few minutes ; thqn increafe it by degrees, that you mayi 
 fee the ore perpetually fmoking a little: in the mean 
 time, it is alfo proper row znd then to ftir it up with . 
 an iron hook. The fhining particles .will alTume a* 
 
 dark 
 
 (D) Mr Cramer ftill means the calciform ores only, ; 
 and not the rnineralifed ores of copper, 
 
C 4 3 
 
 dark red or black ifh colour. This done, take out the 
 left, that it may grow cold. If the fmall grains are 
 not melted, nor Itrongly adherent to each other, hi 
 therto all will be well ; but if they run again into one 
 fmgle c ike, the procefs muft be made again with, 
 another portion of the ore, in a more gentle lire. 
 
 " When the ore is grown cold, beat it to a powder 
 fomewhat finer, and roaft it by the fame method as be 
 fore ; then take it out, and if the powder is not melted 
 yet beat it again to a moft fubtile powder j in this you 
 are to take care that nothing be loft. 
 
 ** Roaft the powder 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 burn it away under the muffle, and do the fame 
 another time again, till, the fire being very bright^ 
 you no Ipnger perceive any fulphureous, arfenical, un- 
 pleafant I'm ell, or any fmoke ; and there remains no 
 thing but a thin, fofr powder, of a dark red, or black- 
 ifh colour. 
 
 " Remarks. Every pyrites contains iron, with an, 
 unmetallic earth ; to which fulphur or arfenic, and 
 moft commonly both, always join. Befides, there is 
 copper in many pyrites ; but fometimes more and fome- 
 limes lefs : fome of them are altogether deftitute of 
 copper ; therefore, fo much as pyrites differ with re 
 gard 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 HI pyrites, the 
 more it inclines to colliquation. The more fulphur 
 and arfenic it has in it, the more quickly the melting 
 of it will be procured, and the reverfe : the more iron 
 and unmetallic earth it contains, the more it proves re- 
 fra&ory in the fire. Now if fuch pyrites melt in the 
 roafting, as happens to fome of them if they grow but 
 red-hot, the fulphur and arfenic that lies hidden therein 
 are fo rtri&ly united with the fixed part, that you 
 would in vain attempt to diffipate them. Nay, in this 
 LI 5 caf 
 
C 42 3 
 
 "cafe, when it is reduced again into a powder it re- 
 a much greater time and accuracy in the regimen of the 
 fere to perform the operation. For this reafon, it is 
 tnuch better to repeat it with new pyrites. But you 
 can road no more than the double quantity at once of 
 the ore you have a mind to employ in the foregoing 
 experiment.; to the end that, the precipitation by fufion 
 *lict fucceeding, there may remain dill another portion 
 entire ; left you fhould be obliged to lepeat a tedious 
 reading. If you fee the figns 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 violeRt a fire : for a great deal of 
 copper is confumed not only by the arfenic, but alfo 
 by the fulphur ; and this happens even in veflels flint 
 very clofe, when the fulphur is expelled by a tire not 
 quite io itrong ; which a reiterated and milder fubli- 
 mati< n of the fulphur in a veflel both very clean and 
 well elf fed will clearly (how. 
 
 " When the greatef; part of the fulphur and the 
 arfenic is diffipated by fuch caufes as promote colli- 
 quation, you may make adrongerfire : but then it is 
 proper to add a little of fome fat body ; for this dif- 
 folves mineral fulphur : it changes the mixture of it in 
 fome part, which, for indance, confiils in a certain 
 proportion of acid and phlogifton ; and at the fame 
 time hinders the metallic earth from being reduced 
 into copper, by being burnt to an excefs. From thefe 
 effecls, the reafon is plain why aflayers produce lefs 
 metal in the trying of veins of copper lead, ar.d tin, 
 than (kilful fmelters do in large operations. For the 
 former perform the roafling under a muffle with a 
 clear fire, and without any oily reducing menftruum ; 
 whereas the latter perform it in the middle of charcoal 
 or <'f wood, which perpetually emit a reductive phlo- 
 gidon. 
 
 " The darker and blacker <he powder of the roafted 
 -ere appears, the more copper you may expect from it. 
 
 But 
 
[ 4-3 3 
 
 But the redder it looks, the lefs copper and the more 
 iron it affords ; for roailed copper dilfolved by fujphur 
 or the acid cf it, is very black, and iron, on the con 
 trary, very red. 
 
 PROCESS V. 
 
 The precipitation of copper out of roafted ore of the Ja$ 
 
 process. 
 
 " DIVIDE the roafted ore into two parts: each of 
 them ihall go for a centner : add to it the fame weight 
 of fandiver, and four times as much of the black flux, 
 and mix them well together. As for the reft, do all 
 according to the procefs I : the precipitated regulus 
 will be half malleable, fometimes quite brittle, now 
 and then pretty much like pure copper in its colour, 
 butfometimes whitilh, and evenblackiih. Whence it 
 is moil commonly called Hack copper, though it is not 
 always of fo dark a dye. 
 
 " It is eafy to conceive, that there is as great a 
 difference between the ieveral kinds of that metal call 
 ed Hack ccpper, as there is between the pyritofe and 
 other copptr -.res accidentally mixed with other me 
 tallic and femi-metallic bodies. For all the metals, 
 the ores of which are intermixed with the copper ores 
 being reduced, are precipitated together with the 
 copper which is brought about by means of the black 
 flux. Wherefore iron, lead, tin, the regultne part of 
 antimony, bifrouth, me ft commonly are mixed with 
 black copper in a mu'.tLtu.ie of different, proportion?. 
 Nay, it is felf-evident, that gold and fiH'er, which are 
 difiulvable by all thefe mitters,. are collected in >fuch 
 -a reguius when they have been firft hidden in the 
 ore. Belides, fulphur and arfeic are not always.alto- 
 gether abfent. For they can hardly be expelled fo 
 perfectly by the many preceeding roaftings, but there 
 remains feme vetliges of them, which are not diffipated 
 
 "by 
 
C 4H C 
 
 by a fudden melting, efpecially in a clofe vefiel, 
 wherein the flux fwimming at top hinders the action 
 of the air. Nay, arfenic is rather fixed by the black 
 flux, and afTume's a regulinefemi-metallic form, while 
 it is at the fame time preferved from diffipating by the 
 copper. 
 
 PROCESS VI. 
 
 To reduce black copper Into pure copper ly fcor'ificatlon. 
 
 *' SEPARATE a fpecimen of your black copper, of 
 the weight of two fmall docimaftical centners at leaft ; 
 and do it in the fame manner, and with the fame pre 
 cautions, as if you would detect a quantity of iilver in 
 black copper. 
 
 " Then with lute and coal-dud make a bed in the 
 cavity of a teft moiftened: when this bed is dry, put 
 it under the muffle of the docimaftical furnace, in the 
 open orifice of which there muft be bright burning 
 coals, wherewith the teft muft likewife 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 deftitute of it, add a fmall quan 
 tity of glals lead, and with a pair of hand-bellows in- 
 creafe ihe fire, that the whole may melt with all fpeed : 
 this done, let the lire be made a little violent, and iuch 
 as win .uffice to keep the metallic mafs well melted, 
 and not much greater. The melted mafs will boil, and 
 fcorias will be produced, that will gather at the cir 
 cumference. All the heterogeneous matters being at 
 lait partly diffipated, and partly turned to fcorias, the 
 furface of the pure melted copper will appear, So foon 
 as you fee it, take the pot out of the fire, and extin- 
 guiih it in water: then examine it in a balance; and 
 if lead has been at firft mixed with your black copper, 
 add to the regulus remaining of the pure copper one 
 35th part of its weight which the copper has loft by 
 
 IB cans 
 
[ 4'5 ] 
 
 means of the lead, then break it with a vice ; and thus 
 you will be able to judge by its colour and malleabi 
 lity, and by the furface of it after it is broken, whe 
 ther 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 you can get by a greater 
 operation, provided the copper be well purified in the 
 fin all trial. 
 
 "Remarks. This is the laft purifying of copper, 
 whereby the feparation of the heterogeneous bodies be 
 gun in the foregoing procefs is completed as perfectly 
 as it poffibly can be. For, except gold and filver, all 
 tile other metals and femimetals are partly diffipated 
 and partly burnt, together with the fulphur and arfe* ' 
 nic. For in the fufion they either turn of themfelves 
 to fcoria or fumes, or this is performed by means of ; 
 iron, which chiefly abforbs femimetals, fulphur, and ar^ ! 
 feme, and the deitruclion of it is at the fame time ac 
 celerated by them. Thus the copper is precipitated ' 
 out of them pure; for it is felf-evident, that the un- 
 metallic earth is expelled, the copper being reduced 
 from a vitrefcent terreftrial to a metallic date, and the 
 arfenic being diffipated by means of which the faid 
 arth has been joined to the coarfer regulufes of the 
 fir ft fufion. But there is at the fame time a good quan 
 tity of copper that gets into the f:orias : however, a 
 great part of it may be reduced out of them by repeat 
 ing the fufion. 
 
 " The fire in this procefs muft be applied with all 
 imaginable fpeed, to make it foon run : for if you ne- ' 
 gleet this, much of your copper is burnt; becaufe ' 
 copper that is only red-hot, cleaves much fooner, and 
 in much greater quantity, into half-fcorified fcales, 
 than it is diminiihed in the fame time when melted.') 
 However, too impetuous a fire, and one much great 
 er than is neceffary for the fufion of it deftroys a much 
 greater quantity of it than a fire fufficient only to put it 
 
C 
 
 in fufion would do. For this reafon, when the purify 
 ing is finifhed, the body melted muft be extinguished 
 in water together with the vefTel, left, being already 
 grovvn hard, it ihould ftill remain hot for awhile; 
 which muft be done very carefully to prevent dangerous 
 explofions. 
 
 " The fcoria of the above procefs frequently con 
 tains copper. To extract which, let two or three do- 
 cimaftical centners of the fcoria, if it be charged with 
 fulphur, be beat to a fubtile powder, and mix it, either 
 alone, or if its refraftory nature requires it, with fome 
 very fufible common pounded glafs without a reducing 
 faline flux, and melt it in a clofe veffel, and in a fire 
 having a draught of air; by which you will obtain a 
 regulus. 
 
 " But when the fcoria has little or no fulphur at all 
 in it, take one center of it, and with the black flux 
 manage it as you do the fufible copper ore, (procefs 
 I.) by which you will have a pure regulus." 
 
 PROCESS VII. 
 
 The following procefs is tranflated from Mr Gellert's 
 Elements of EJfaying, and defcribes a new method of 
 efTaying ores, concerning which, fee the fedion Of 
 EJ/aying in general, p. 338. col. 2. 
 
 To ejfay copper ores. 
 
 ROAST a quintal of ore [in the manner defcribed 
 in procefs IV.J - add to it an equal quantity of bo 
 rax, half a quintal of fufible glafs, and a quarter of a 
 quintal of pitch : put the mixture in a crucible, the 
 inner furface of which has been previoully rubbed with 
 a fluid pafte of charcoal-daft and water: cover the 
 whole with pounded glafs mixed with a little borax, 
 or with decrepitated fea-falt : put a lid on the cru 
 cible, which you will place in an air-furnace, or in a 
 blatt-furnace when the fire lliall have extended to the 
 bottom of the coals, let it be excited briikly during 
 
 half 
 
C 4*7 3 
 
 , 
 
 half an hour, that the crucible may be of a brifk red 
 colour : then withdraw the crucible v and when it is 
 cold break it : obferve if the fcoria be well made : fe- 
 parate the regulus, which ought to be femi-dudile ; 
 and weigh it. This regulus is black copper ; which 
 muft be purified, as in procefs VI. 
 
 If the Ore be very poor, and inveloped in much 
 earthy and ftony matters ; to a quintal of it, a quintal 
 and a half of borax, a quarter of a quintal of pitch, and 
 ten pounds of calx of lead or minium, muft be added. 
 The calx of lead will be revived, and will unite with 
 the fcattered particles of the copper, and together with 
 t-hefe will fall to the bottom of the crucible, forming a 
 compound regulus. When the ores of copper are very 
 rich, half a quintal of borax and a quarter of a quin 
 tal of glafs will be fufficient for the reduction. If the 
 ore is charged with much antimony, a half or three 
 quarters of a quintal of clean iron-filings may be ad 
 ded ; otherwife the large quantity of antimony might 
 ckftroy the copper, efpecially if the ore contained no 
 lead. If iron be contained in copper ore, as in pyrites,, 
 fome pounds, of antimony, or of its regulus, may be 
 added in the effay ; as thefe ftibftances more readily 
 unite with iron than with copper, and therefore dif- 
 cngagethe latter metal from the former. 
 
 PROCESS VIII. 
 
 To effay ores of copper by humid folution. 
 
 SOME pyrites and ores contain fo fmall a quantity of 
 copper, that it cannot be feparated by the above pre 
 cedes, but is deftroyed by the repeated roaftings and 
 fufions. Thefe, and indeed any copper-ores, maybe 
 eitayed by humid folution, or by menftruums. 
 
 i. By reading a fulphureous ore, the fulphur is 
 burnt or decompofed, its phlogifton with part of the 
 
 acid 
 
acid evaporating, while the remaining part of the acid 
 combines with the metals, efpecially with the copper 
 and iron contained in the ore. Accordingly, from an 
 ore thus roafted, a vitriolic folution may be obtained 
 by lixiviation with warm water, efpecially if the ore 
 has been expofed, during a few days after it has been 
 roafted, to a rnoift air ; as the water thus gradually ap 
 plied unites better with the combination of the metal 
 lic calxes with the concentrated vituolic acid of the 
 fulphur : but all the copper is not thus reduced by one 
 operation to a vitriol. More fulphur mu ft therefore be 
 combined with the refiduous ore by fufion, and mult 
 be again burnt off, that the remaining part of the cop 
 per may be attacked by fome of the acid of the ful 
 phur. By repeating this operation, almoft all the cop 
 per and iron will be reduced to a vitriolic lixivium, 
 from which the copper may be feparated and precipi 
 tated by adding clean pieces of iron. 
 
 2. Copper-ores may be more eaiily effayed by hu 
 mid folution in the following manner : 
 
 Road the mineralifed ores in the manner directed 
 in Procefs IV. and pulverife them. If the ores be cal- 
 ciform, they do not require a previous roafting. Put 
 this powder into a matrafs capable of containing ten 
 times the quantity of the ore ; pour upon the ore fome 
 water : fet the matrafs in a fand-bath, that the water 
 may boil : pour off the lixivium : add to the refidous 
 ore more water, with fome vitriolic or marine acid : di- 
 geft as before in the fand-bath, and add this lixivium 
 to the former : repeat this operation, till you find that 
 the acid liquor diflblves no more metal. 
 
 By adding clean plates of iron you may precipitate 
 the copper, which ought then to be collected, fufed 
 with a little borax and char coal dull, 'and weighed. 
 
 We may remark, that although copper is not folu- 
 ble by a dilute vitriolic acid, yet the calx of it obtained 
 by roafting the ore, and alfo the calcifoim ores, are 
 readily foluble in that acid. 
 
 4 3. Stahl 
 
3-Stalil ad'/ifes to cilay copper ores byjbpiling them, 
 after they have been roafted and powdjrcd, in w:iLcr, 
 together with tartar and common i'ilt, or with' altihi 
 and comnif n f ilt : but we have not found this meihod 
 fo effectual as the proceeding. 
 
 Dr FcrJyce's method of cffay'ing copper ores, ly want 
 of a-->ii'i rcg'ia. [Phil. Tranf. for 1781, vol. Ixxr* 
 art. 3.] 
 
 THIS method confuls only in pouring a quantity of 
 an aquarcgia compofed of equal parts of the nitrous 
 and muriatic acids upon a frnail quantity of the ore ill 
 powder, til' afreili affiVQo'rrof the meiiftruurh Ihnws no 
 green or blue tinge ; by which m.ans all the metalline 
 paft of the ere will be diiiblvcd. It is then to be 'pre 
 cipitated by means cf a fruition of iixed allali, or 
 volatile alkali caiitidully riiana;.!.\-cl will anfwcr the fame 
 j.urpr-fe. The metal then i-pp^ars in f -rm of a green 
 precipitate called ^retn ixrj'iter ; but is mixed \vi:h 
 v.-hat ciilcarcr.us earth might: liave been contained in 
 rhe ore ; winch the acidr, wotil'd d5;Tclve, and the fixed 
 li tl-nl; kind \var>'ufct!, vouid precipitate. The 
 cauftic volatile alkali \vould not throw down t;:,'s 
 earth, and is therefore to be prefeive'J to any other; 
 but care mu ft be taken to Ir'c tl:e pcirit of fatnvation 
 very cxa>51iy with it, :. s ; t 
 
 if added in tor, iiimtitj. Br Fbfdyce ol 
 
 this green calx to be diffolred in vitriolic acid, ;md 
 then, by adding a pi' irdrt to the fblfatibn, 
 
 all the copper c> c vill be dbtailled ia 
 
 its metallic form. 
 
 Tins method can be fab-eel to ro fall icy, unlefs the 
 
 ore contains a luminous matter ; in which cu r e feme of 
 
 ^he earih of alnm wiJl be. mixed with the metal, as that 
 
 '& m the 
 
earth will be precipitated by fixed alkali, by cauftic 
 volatile alkali, and by iron. This, however, may 
 very effectually be prevented by dillblving the green 
 calx iirft in volatile alkali, and then in vitriolic acid. 
 It is even probable, that by reducing the ore to a very 
 fine powder, and treating it with cauilic alkali, all 
 the metal might be feparated from the ere, without 
 the trouble of uiing aqua regia. For the principles on 
 which this method is conducted, fee the article CHE- 
 MISTRY pafjlm. 
 
 SECT. V. Ores of Lead, 
 
 i. LEAD is feldom found native ( E ) and malleable. 
 Neither, fays Mr Macquer (F), is it found in form of 
 calx or precipitate, as copper is, becaufe it is much 
 lefs liable to lofe its phlogifticn by the action of air and 
 .water : therefore almoft all lead is found naturally 
 mineralifed. 
 
 Lead 
 
 (E) Cronftedt doubts whether any native lead has 
 been found. Linnaeus fays, he has feen what externally 
 appeared to be fuch. 
 
 (F) But he is miftaken. As lead unites ftrongly 
 Trith vitriolic acid, we might expect to meet ochres of 
 .this metal as well as of copper. Accordingly we find 
 force calciform ores of lead. i. A pure calx of lead, 
 in form of a friable ochre, cerujja native, found on the 
 TUT face of galena ; or it is indurated with a radiated or 
 .fibrous texture, of a white or yellowifh green colour, 
 
 and refembling fpar; it is .called fpatum flumli, fparry 
 leaJ-orS) and lead-fpar. 2. A calx of lead is found 
 mixed with calx of arfenic, forming the ore called 
 arfenicatcd Isad-fpar. Sometimes alfo that calx is mixed 
 with calcareous earth. 
 
Lead is generally mmeralifed by fulphur (G). It$ 
 ores have a dark white, but fhining metallic colour. 
 Thefe ores, although they form irregular mafTes, are 
 internally regularly difpofed, and item to be compofed 
 of cub-s of different fizes applied to each other, but 
 not adherent. Thefe ores are generally diftinguiihed 
 by the name of Gakna. They commonly contain about 
 three quarters of lead and a quarter of lulphur. They 
 are accordingly heavy and fuiible, although much lefs 
 fo than pure lead. 
 
 Moft lead-ores contain filver ; none but thofe of Wil- 
 l:ich in Carinthiaare known to be quite free from it : 
 fome of them contain fo much of it, that they ars con- 
 fidered as improper ores of filver. The fmaller the 
 cubes of galena are, the larger quantity of filver has 
 been remarked to be generally contained. 
 
 2. Lead Ores may be effayed, I. By means of the 
 black flux, in the manner directed by Mr Cramer, as 
 follows : 
 
 " Let one or more quintals of this ore be grofsly 
 powdered, and roalled in a teft till no more fulpureous 
 vapours be exhaled, and then reduced to a finer pow 
 der ; it is then to be accurately mixed with twice its 
 weight of a black flux, a fourth parts of its weight of 
 M m 2 clean 
 
 (G) Lead is mineralifed, i. With fulphur; fucli are 
 the feveral kinds of fteel-grained and tefielated gale- 
 n. is, which alfo contain generally fome filver, 2. With 
 fulphura:ed iron and filver. It is fm?-grained or tef- 
 felated, and is diilinguilhed from the former by yielding 
 a black flag when fcoriaed, whereas the former yields 
 a yellow ilag. 3. With fulphurated antimony and 
 filver. Plumbum Jliliatum Llnnxi. Its colour is fimilar 
 to that of galena, and its texture ftriated. 4. With 
 fulphur and arfenic. This ore is foft, almoft malleable, 
 lead. From this ore lead may be melted by the flame 
 of a caudle. 
 
[ 422 ] 
 
 clean filings cf iron and of brrax. The mixture is to 
 .it into a good crucible, or rather into a tell ; it 
 3 \y,ifh a 01 two or three 
 
 ;rs of clecr'. . >le is to be 
 
 vf.c.kJ, and placed 1. - ^ v;hlch i> to be 
 
 SBgdi with unli; tap of the 
 
 crucible (hall be covered with ; Lhen 
 
 o be thrown upon tie unldne. -.-. -, . .1, ;\n I the 
 
 hide .is left to kindle .lowly, ill .' e red- 
 
 : -t ; fbon after 7v'i feii a hi pi. ceeds .'roin 
 
 '..he crucible, which is oceaiKn.a ry the rcducl:Jon of 
 the lead: the fame degree cf lire is to be maintained 
 v.'hlle this iioife continues, iriid is afterwards to be iud- 
 cienly increafed, fo as to make a perfect fufion ; in 
 which flate it is to be continued during a quarter of 
 an hour; after which it is to be extinguished ; and the 
 operation is then finiihed." The filings of in n are 
 ;idded to the fixture, to abicrb the iuiphur ; a certain 
 quantity of which generally renu.rii., united wii:li the 
 lead-ore, iiOtwithftandlng the roallii:^. We need not 
 rearleaft this metal (hall unite with the lead and alter 
 :'ts purity; bccaufe, altheugh the iuij.-hur ihould not 
 hinder it, theie two ir.etals- cannot be united. The re- 
 fradlory quality of the iron dotrs not impede tl;e iu- 
 llon ; for the union it forme with the fulphnr renders 
 kfo fufible, that it becomes iti>lf a kind of iiux. This" 
 addition ofiionin the ciray of lead-ores would be u Te 
 le fs, if the ores were fuificieiiily roafted, fo that no ful- 
 phur friould remain. 
 ' Or, 2. By the following process of Mr Gellert. 
 
 u Mix a quintal of rcalied lead-ore wi h a c-niniT;! of 
 calcined borax, half a quintal of (.'l-.'fs Hnely pulvtriied, 
 -A quarter cf a quin.- ch, and as nn;ch cf. clean 
 
 iron-flings: pu ! t;- .- l^U) ?. crucible weU:d 
 
 viih charcoa-duf!: and water: place the crucible be- 
 fl-e tlie no'/./.le of the heUr.ws of a for^o, a::d v-Len 
 
 i ',' or jo n.iriUcs ; then 
 break it; v/hcn ccld." 
 
C 4'3 ] 
 
 Some very fufible ores, fuch as the galena of Der- 
 bylliire, may be eflayed, as large quantities of it are 
 fmelted without previous reading, and without addi 
 tion, merely by fufion during a certain time. For this 
 purpofe nothing more is requifite then to keep the ore 
 melted in a crucible with a moderate heat till all the 
 ililphur is deftroyed, and the metal be collected. To 
 prevent the deftruclicn cf any part of the metal after 
 it is feparated from the fulphur, fome charcoal -duft 
 may be thrown over the ore, when put into the cru 
 cible: but if the galena be mixed with pyrites, efpe- 
 dally arienical pyrites, it requires much reading and: 
 feline fluxes. 
 
 SECT, VI. Tm Ores. 
 
 i. TIN is very feldom found pure, but almoft al 
 ways mineralifecl, and chiefly by arfenic. 
 
 The richeit ore of tin is of an irregular form, of a 
 black or tamilhed colour, and almoit the heavieft o 
 all ores. The caufe of this extraordinary weight is, 
 that it contains much more arfenic than fuiphur, 
 whereas moft ores contain more fulphur than a<fenic. 
 
 The moil common tin ore is of the colour of ruft, 
 which proceeds from a quantity of iron or of ir; n-cre 
 mixed with it. The tin-ores of Saxony and Bohemia 
 appear to be all of this kind. 
 
 One kind of tin-ore is fcmi-tranfparent and like fpar. 
 Laftly, feveral kinds of garnets are enumerated by mi- 
 neralogiiis among tin-ores, becaufc they actually con 
 tain tin. 
 
 The county of Cornwall, in England, is very rich 
 in tin-ores; and the tin contained in them is very pure. 
 From tin-mines in the Eaft Indies tin is brought, call 
 ed Malacca tin. No mines of tin have been difcovcr 
 in France ; only in Bretagne garnets are found which 
 contain fume tin. 
 
 Native tin is faid to have been found in Saxony and 
 M m 3 Malacca.. 
 
Malacca. Its ores are all of the calciform kind, ex 
 cepting black-lead, which appears to be tin minera- 
 lifed by fulphur and iron. 
 
 The calciform ores of tin are, i. Tin {lone, which 
 is of a blackiih-brown colour, and of no determinate 
 figure ; and tin-grains, or cryftuls of tin, which re- 
 iemble garnets, an.! are of a ipherical or polygonal fi 
 gure, which they have probably acquired by the attri 
 tion of their angles. The tin-Hone feems to confift of 
 attrited tin-grains. This ore is calx of tin united with 
 calx of arfenic, and frequently with calx of iron. 
 2. Garnets are laid to conuiin calx of tin united with 
 calx of iron. 3. Manganefe is fait! alfo to contain tin. 
 
 2. Ores of tin m:.<y le ej}'\yed in the fame manner, 
 according to Cramer, as he directed for the eiiay of 
 3ead-ores,/'./>;w. Ke further m.ikes upon this eiiay the 
 ft *1 : owi 11 g rein ar k 5 , 
 
 I. Tin-ore, on account of it? grsateir gravity, ad 
 mits better or being /ep^r ifci&H or watli- 
 ing, from earths, (tones, . . 2, A moil 
 exact reparation of earth 1 : .>.. . 
 becaufe the fcorifica'ao:i oft - - re [ui 
 :i heat as w T ould deitroy t _d tin. 3. Tlie ire a 
 ought to b? ieparated by a magnet. ^.. By a previous 
 roailir.g, the arieaic is diffipated, which would o 
 wife cany oif a great deal of tin al nig with it in a melt 
 ing heat, would change another part of it into alhes s , 
 and would vitiate the remaining t'..i, \. 'ihe eflay of 
 tin is very precarious and uncertain ; becaui b tin once 
 r,duc:d is eafily de.rrucl'ible by the tire, and by the 
 faline fluxes reqaifite for the reduction. 
 
 Mr Gellert aireds, that ores of tin Ihoukl be eifayed 
 in the following manner : 
 
 " Mix a quintal of tin ore, wafhed, pulverifed, and 
 twice roaftecl, with ha-f a quintal of calcined borax, 
 rand half a quin"a^bf pulverifed pitch : thefe are to bj 
 put into a crucible rnoiftened with charcnal-diUl and. 
 wal;cr,.and the crucible placed in an uir-farnace; after 
 
 the 
 
[ 4^5 J 
 
 the pitch is burnt, give a violent fire uirrmg a quarter 
 of an hour : and men withdraw your criicible. If the 
 
 ore be not very well wafned from the ea tiiy natters, 
 as it ou^lit to be, a larger qiiarititj of boi .x is r..qui- 
 i:ie ; witn ibme powdered ghii's, by which t,,e too q.nc^ 
 fbfioii of the borax is retarded, ana the precipitation, 
 oftlie earthy matters is prevent^;. If rhc ore contains 
 iron, to the above mixture may be added Ibme alkaline 
 fait. 
 
 S E c T. VI I. Ores of Iron. 
 
 J 
 
 j 2. IRON is feldom found in its metallic ftate, and 
 
 free from admixture ; though Cramer gives an accov.nt 
 
 of an ore which needs only to be put into a forge, and 
 
 heated to a welding heat. Several lands and earths 
 
 alib have the appearance of iron, and are even attract- 
 
 able by a magnet. The ore mentioned by Cramer is 
 
 n:u::d vitreried : with moderate blows the fcorias are 
 
 .1 ou., aild :> i\iafs cf iron obtained, which, by 
 
 beint^ put into the fc.rge :i^a:n, ^'ves tough iron with- 
 
 But in genc!al this rnetal is 
 
 ' a calx ; or, though it is combined 
 
 v of the principle of inflammability, 
 
 it baa ieidcm en^iigh <.fJiQ metallic form ; and it is 
 
 very often intermixed vri:h a certain proportion offul- 
 
 phur 4 . Th_- mi;.era s wrought for iron are three, viz. 
 
 iron ore, iron-iiore. and bog-fire. 
 
 The iron ore is found in veins as the ores of other 
 metals are, and the appearance is very various ; fome- 
 tnrxs it has a rully iron colour refembling that of iron ; 
 fometimes it has a recldifli caft : often it is formed into 
 a fort ocryftaUizations which are protuberant knobs 
 on the c u tiide ; and the;'e confift of fibres tending to a 
 common centre, a~.id it is of a dark colour like coagu- 
 Jaied blood. It is called h<n?m:i 'cs or bkod fom ; and 
 ccnfiils of a calx cf iron with a fmall quamity of vi 
 triolic acid. 
 
 Iron 
 
3 
 
 tron-ftone in Britain is clay found in the ftrata, 
 xvirh coal: but which contains a large quantity of 
 iron, fo as to make the working profitable. Some 
 times it has little appearance of iron ; but when burnt 
 with a certain degree of heat, it becomes of a deep 
 red. 
 
 The bog-o'-e is an ochre of iron, and is found gene 
 rally in L..w filiations, and in fprings containing a 
 fm*dl quantity of iron, w; ich flowing over thefe grounds 
 depoiits it in the form of ochre ; and after a number 
 cf ages it proves a rich mine of iron, and it is extraft- 
 ed Irom a calx of this kind in many parts of the 
 world. There is 3 lib a particular kind of fpar found 
 in different com. trie* of a pale blue colour, fo that 
 fromi:s firft appearance we would expecl copper ; but 
 it contains a fmall quantity of iron, and is a combina 
 tion of the metal \vith inflammable matter, as in Pruf- 
 fian blue. 
 
 The load ft one is a noted iron ore. It is always 
 found in veins, and it is a -lodged that it is only pof- 
 fefTed of its magnetic qualities when near the furface, 
 In appearance, it does not differ from rr any of the ores 
 of iron, and treated as an ore, it affords a considerable 
 quantity of metal. 
 
 Neither is iron generally mincralifed fo diiiinctly 
 as other metals arc, unlefs in pyrites and ores of other 
 metals. 
 
 Mod cf the minerals called Iron ores have an earthy, 
 rufty, yellowifh, or brownift} appearance, which pro 
 ceeds from the facility with which the true iron ores 
 are decompofed. 
 
 Iron is the moft common and moft abundant cf all 
 metals. In Europe, at leaft, we cannot find an eanh, 
 a fand, a chalk, a clay, avitrifiable or calcinab'e Hone, 
 or even the allies of any fubilance, which do net con- 
 lain an earth convertible into iron. All earths and 
 ftor.es which arera urally yellow or red, and all thofe 
 which acquire thefe colours by calcination, receive 
 
 them. 
 
them from the ferruginous earth mixed with them. 
 The yellow and red ochres coniifl aim oil iblely of 
 this eanh : the black and heavy lands are generally 
 very ferruginous. 
 
 The iron ore mod commonly found is a ilone of 
 the colour of rail, of an intermediate weight betwixt 
 thefe of ores in general and unmetallic ilones. This, 
 ore -has no determinate iorm, and eaiily furniftje's an 
 iron of goo.d quality. 
 
 Biocd-ltone or hematites, fa^guine or rcd-cha.k, 
 and emery, are iron ores ; iome or wbiehj ior inua^ce 
 biccd-itone, arc aimed all imn. Moil of thefe lab-; 
 fiances require but a flight calcination to be rendered 
 very attractable by a magnet, and foluble in aqua 
 fortis ; but the iron obtained form them is of a ba 1 
 quality, and they are therefore neglected. Iron from 
 the hematites is very brittle ; that obtained from ochres . 
 is red-inert. All thefe iron ores are fo refractory, that 
 they can fcarcely be fu'e '. 
 
 Iron ores are very various in their form : or rather 
 taey have no determinate form, Sometimes ti:.cy are 
 earth?, fometimcs icones, fometimes grains. Accor- 
 dtngly, thole naturaliils who attend only to the ex 
 ternal form of things in clafilng and fubdividing mi 
 nerals, have been ob iged to multiply the names of 
 iron ores ; hence they are called irox ores in f<:-r-n of 
 peafe, cfbevis, of ccrtander f.cds^ of cfip r-corus t of c inn a- 
 <nc;;, 5:c. which Mr Cramer treats as iiiiculcus trifies. 
 
 2. Grss of Ircn viaj be eftiyed by the following 
 procefs : 
 
 . P R. O C E S S I. 
 
 [CRS.VF.R'S Sirt fff , Proc. 54.] 
 
 ^o reduce a precipitate Iron out oflrs ore in a c j cfe "Jfjjcf. 
 
 ". ROAST for a few minutes in a toft under a muffle, 
 and with a pretty iircng fire, two centners of the 
 iniall weight of your iron ore gioisly pulverifed ; that 
 
 the' 
 
r 
 
 the volatiles may be ditfipated in part, an 1 the ore it- 
 felf be foftened in cafe it ihoald be too hard. When 
 it is grown cold, beat ir extremely fine, and roaft it a 
 iecond time, as you do the copper-ore, but in a much 
 ftronger fire, till it no longer emits any fmell ; then let 
 it grow cold again. Compofe a flux of three parts of 
 the whits flux, with ooe part off ufible pulveri Ted glafs, 
 or of th- like ftertle unfulphureous fcorias, and add 
 fandiver and coal-dud, of each one-half part j add of 
 this flux three times the quantity of your roafted ore 
 and mix the whole very well together ; then choofe a 
 very good crucible, well rubbed with lute within, to 
 ftop the pores that may be here and there unfeen ; put 
 int it the ore mixed with the flux ; cover it over with 
 comm m filt ; and ffaut it clofe with a tile, and with 
 lute applied to the points. 
 
 " Put the wind-furnace upon its bottom-part, ha 
 ving a bed made of coal-daft. Introduce befides into 
 the furnace a fmall grate fupported on its iron bars, 
 and a ftone upon it, whereon the crucible may ftand 
 as on a fupport : furround the whole with hard coals, 
 not very large, and light them at top. When the veiTel 
 begins to grow red, which is indicated by the com 
 mons falt's ceafing to crackle, ftop with grofs lute the 
 holes of the bottom part, except that in which the 
 ncz/le of the bellows is received : blow the fire, and 
 excite it with great force, adding now and then frefh 
 fuel, that the vcflel may be never naked at top ; ha 
 ving thus continued your fire in its full ftrength for 
 three quarters of an hour, or for a whole hour, take 
 next the velfel 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 veiTel. 
 
 " When the regulus is weighed, try its malleabi 
 lity : then make it reel-hot ; and when fo, ftrike it 
 with a hammer : if it bears the ftrokes of a hammer, 
 both when red hot and when cold, and extends a little, 
 
 you 
 
[ 4 2 9 3 
 
 you may pronounce your iron very good ; but if, when 
 either hot or cold, it proves brittle, you may judge it 
 to be not quite pure, but (till in a femi-mincrai con 
 dition. 
 
 " Remarks. The arfenic, but efpecially the fulphur 
 mu ft be diffipated by reading : for the former renders 
 the iron brittle ; and the latter not only does the fim.e, 
 but, being managed in a clcfe veflel, with a falirie al 
 kaline flux, turns to a liver of fulphur ; to the action 
 of which iron yielding in every refpect, it can upon 
 no account be precipitated, and if not the \\hole, a 
 gre it part of it at leaft is retained by the fulphureous 
 fcoria ; fo that in this cafe you commonly in vain look 
 for a regulus. 
 
 " The iron obtain- d from this f.rft precipitation 
 has h.-rdly ever the requilite ductility, but is rat 1 er 
 brittle ; the reaibn o-' which is, that the fulphur and 
 arfenic remains in it ; for notwithstanding that the 
 greateil part of thefe is diiTJp itc-d by roafting, yet 
 ilme part adheres fo ilricViy, that it can never be fe* 
 paratcd but with absorbent, terreftrial, alkaline ingre 
 dients, that change the nature of the fulphur. For 
 which reafon, in larger operations, they add quick 
 lime, or marble ftones that turn into quicklime ; 
 which, while they abfbrh the faid minerals, are, by it 
 and by help of the deftroyed part of the iron, brought 
 to a fufion, and turn to a vitrified fcoria ; although, at 
 other times, they refill fo much by their own nature a 
 vitrification- Another caufc of the brittlcnefs of iron 
 is the unmetaliic e.'.rth, when it is not yet feparated 
 from it ; for the iron ere contains a great quantity of 
 it, and in the melting remains joined with the reguline 
 p.irt : whence the iron is rendered very coarie and 
 brittle. Some iron ores are altogether untractable : 
 ncverthelefs, the regulu.fes produced out cf them, when 
 broken, have fometimcs a reatfemimetallic look; which 
 proceeds undoubtedly from a mixture of a fm all quan 
 tity of ibme other metal or femimetal." 
 
 P P. O- 
 
[ 430 ] 
 
 PROCESS II. 
 
 [[The following Procefs for eflaying iron ores, and 
 ferruginous itones and earths, is extracted from 
 MrGcUert's Efem.-nts of cjjaymg.'} 
 
 " ROAST two quintals of iron ore, or of ferrugi 
 nous ear.h : divide the rcafted matter into two equal 
 parts: to each of which add half a quintal of puive- 
 rifed glafs, if the fubftance be fufiblc and contain- 
 .much metal; but if otherwiie, acid ah'o half a quintal 
 of calcined borax. If the reading* has entirely difen- 
 gagcd the fulphur and ;;iienic, an eiglith r art, or even 
 half a quintal, of quick] ime may be added. VviJi the 
 above matters mix twelve pounds of charcoal powder. 
 
 " Take a crucible, and cover the bottom and licks 
 r" its inner iurfuce with a pafte made oi three parts 
 o charco;;l-duft and one part of clay bor.t U Aether. 
 In the hollow left, in this paite put the above mixture ; 
 prefs it lightly clown ; cover i : : with puivcriied glafs ; 
 and put on the lid of the crucible, 
 
 " Place two fuch crucibles at the diftance of about 
 four fingers from the air-pipe, in fuch a manner that 
 the air ihall pafs betwixt them at about the third part 
 of the height from the bottcm ; fill the ibace be 
 twixt the two crucibles with coals of a moderate rl/:e : 
 throw lighted coals upon them, that the fire n,ay clc- 
 fccnd and make them red-hot from top to botroni ; lit 
 tirft let the bellows blov/foftly, and afterwai'd:-. ftiongly 
 during an hour, or anhcur and a quarter: then t^Vo 
 away the crucible, and break it when cold. A regulir^ 
 will be found in the bottcm, and fometimes feme irr.all 
 grains of iron in die fcoria, which muit be ieri.ratcd 
 and weighed along with the regulus : thin try the 
 regulus whether it can be extended under the hammer 
 when hot and when cold. 
 
 " Remarks. To disengage a metal frcrn the ear'hy 
 matters mixed with it by fire, \ve mud chai:gc t]-e,'e 
 
 .matters 
 
L 43> 3 
 
 in.itters into fcoria or glafs. This change may be 
 effected by adding feme iubdance capable of diflblving 
 thefe matters ; that is, of converting them into a fcoria 
 or glafs, from which the metallic matters may, by 
 their weight, feparate and form a regulus lit bottom. 
 Fixed alkali, which is an ingredient of the black and 
 of the \\hite flux, is a powerful folvent of earths and 
 ftones ; but the alkali does alfo diiiblve iron, efpecially 
 when this is in a calcined or earthy flate ; and this 
 folution is fo much more complete, as the hre is longer 
 applied. Hence, in ordinary ell ays, where an alkaline 
 ,lalt is ufed, little or no regulus of iron is obtained. 
 Now, glafs acts upon and diilblves earths and ftones ; 
 but not, or very little, iron : confcquently glafs ib the 
 bed flux for fuch eilays, and experience confirms this 
 affci tion. If the ore contains but little iron we may 
 alfo add to the glafs fome borax ; but borax cannot 
 be employed fmgly, becaufe it very foon fufes and fe- 
 parates from the ore before the metal is revived. Quick 
 lime is added, not only to abforb the fulphur and arfe- 
 nic remaining in the ore, but alfo becaufe it diilblves 
 and vitrifies the ftony and earthy matters of iron ores 
 which are generally argillaceous. For which reafon, 
 in the large operations tor fmelting iron ore, quicklime, 
 and even in certain cafes gvpfuin, are commonly added 
 to facilitate the fufion. 
 
 " The reduction of iron-ore, and even the foilon of 
 iron, requires a violent and long-contkiued heat ; 
 therefore in this operation, we muit not employ an 
 inflammable fubflavjce, as pitch, that is icon confu- 
 med, but charcoal pulverifed, which in clofe veifels is 
 notfeniibly wafted. Too much charcoal mull not be 
 added, elfe it will prevent the action of the glafs upon 
 the earthy matter of the ore, and coniequently the 
 ieparation of the 'metallic pait. Experiments have 
 taught me, that one part of charcoal dull to eight 
 parts ot ore was the bed proportion. 
 
 N n l Whe 
 
C 43* 3 
 
 " When iron is furrounded by charcoal, it is not de- 
 ^ompoied or deftroyed ; hence the iron of the ore, 
 which finks into the hollow made of paile of charcoal, 
 tluit and clay, remains there unhurt. The clay rs 
 -added in this pafte to render it more compact, and to 
 keep the fluid iron collected together. 
 
 " The air is directed betwixt the crucibles ; becaufe 
 if it was thrown directly upon them, they would 
 fcarcely be able to relift the heat. The fpace betwixt 
 the air-pipe and the crucibles ought to be conftantly 
 niled with charcoal, to prevent the cold air from 
 touching the crucibles. Ductile and malleable iron is 
 ieldom obtained in this firil operation. The fulphur 
 and arfenic, and frequently al:'b an earthy matter adhe 
 ring to the iron, prevent thefe qualities." 
 
 SECT. VIIT. Ores of Mercury. 
 
 y. i. MERCURY is fometimes found pure, fluid, and 
 in its proper metallic itatc, only mixed with earths 
 *md flones. Such are the ores of mejcury found near 
 Montpelier, in Tuicany, and in other places. 
 
 But the largeft quantity of the mercury found in 
 the earth is mineralifed by fulphur, and confequently 
 is in the form ot cinnabar. 
 
 Mercury is never mine: alifed by arfenic. The richeii 
 mine of mercury is that ot Almadin, in Spain. 
 
 Linnsus and Cronftedt mention a fingular ore, in 
 which the mercury is mi.ieralifi-d ly fulphur and by cop 
 per. It is laid to be of a blackilh-grey colour, of a 
 glaffy texture, and brittle. When the mercury and 
 iulphur arc expelled by fire, the copper is diibovered 
 by giving an opake red colour to glafs of borax. 
 which, by continuance and increafe of heat, becomes 
 green and tranfparent. 
 
 2. Cramer directs, that ores of mercury Jhould Is 
 ejaycd by tlie following procefies : 
 
 PRO- 
 
C 433 J 
 
 PROCESS I. 
 
 To ftparaie mercury out of an unfuipktireoit; ore ly 
 
 *' TAKE a lump of the pulverifed ore, one common 
 pound, which mult (land for one centner : put it into 
 a glafs retort perfectly clean, well loricated, or coat 
 ed up to half the length of its neck, this muft be very 
 long, and turned backwards with fuch a declivity, 
 that a glafs recipient may be perpendicularly applied 
 to it : but you muft choefe a retort fmall enough, that 
 the belly of it may be filled hardly two-thirds with the 
 ore : this retort muft be placed fo, that nothing of the 
 fluid adherent to the neck of it may fall in the ca 
 vity of the belly, but that the whole may run forward 
 into the 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. 
 
 " Let the retort be furrounded with hot burning 
 coals placed at forne diftanee in form of a circle, left 
 the veflel ihould burft by too fudden a heat : then by 
 degrees bring the burning coals nearer and nearer, and 
 at iaft furround the whole retort with them and with 
 frelh charcoal, that it may grow fiightly red-hot ; this 
 fire having been continued for an hour, let the retort 
 cool of itlelf : then ftrike the neck of it gently, that 
 the large drops which are always adherent to it may 
 fall into the recipient : let the recipient be taken away 
 and the water feparated from the mercury by filtra- 
 tion, and let the mercury be weighed. This opera 
 tion may be more conveniently performed in a land- 
 bath ; in which cafe the pot containing the fand muft 
 be middling red-hot, and the retort be able to touch 
 the bottom of it immediately ; nor is it then neceflary 
 that the retort be loricated." 
 
 N n 2 PRO- 
 
[ 434 ] 
 
 PROCESS II. 
 
 To revhe mercury from a fulpkureous c'tnnalar-orc. 
 
 " BEAT your ore extremely fine, and mix it ex'a<51'- 
 ly with an equal portion of iron-filings, not rully ; 
 proceed to dillil it with the fume apparatus as in 
 the former procefs, but urge it with die , ftrcngeft 
 fire that can be made. . . :. 
 
 "Cinnabar may be feparated from (tones by.fub- 
 limation thus : Beat it to a fine powder, and put k 
 into a fmall narrow glafs or earthen cucurbit, the 
 belly of which it mud not fill more than one-third 
 part: ftop the orifice at top; this muft be very nar 
 row, to hinder the free aclion of the air. Put this 
 fmali cucurbit in an earthen pot above two inches wide 
 in diameter, and gather fand around this pot about as 
 high as the pulverifed ore rifes in the cucurbit. Then 
 put it upon -burning coals in fuch manner that the bot 
 tom of the pot may be middling red-hot. Thus will your 
 cinnabar afcend and form a folid ponderous ring, which 
 irmft be got out by breaking the vefFel. 
 
 SECT. IX. Ore tf ike Regains of Antimony. 
 
 NATIVE regulus of antimony was firft obferved by 
 Mr Swab, in Sweden, in the mine of Salberg, and 
 defcribcd by him in the memoirs of the Swediili Aca 
 demy in 1749. Mr Wallerius mentions it in his JMi- 
 neralogy. 
 
 Regulus, of antimony is generally united with ful- 
 phur, with which it forms antimony, which ought -to 
 be confidercd as a true oie of .the regulus oi ami- 
 niony. 
 
 Another ore of regulus -of antimony is alfo known 
 of a red colour, in which 'the regulus is male rallied 
 both by arfenic and by fulphiu. r i his ore reiemhlc*; 
 icme iron ores; and feme kind cf blciul. it is di- 
 
 itinguiilicd 
 
C 435 ] 
 
 ftinguifhed by its great fufibility, which is fuch, that 
 it may be eafily melted by the flame of a candle. 
 
 The native regains of antimony, by Von Swab, is 
 raid by that author to have differed from the regulus 
 of antimony obtained from ores, in thefe two proper 
 ties, that it was capable of being eafily amalgamated 
 Y7<th mercury, and that its calx Ihot into cryftals during 
 the cooling. 
 
 Befides the ores of regulus of antimony enumerated 
 above, this femimetal is alfo found in ores of other 
 metallic fubftances, as in the plumofejilver-ore, and in 
 the ftibiated lead-ore. 
 
 2. The ores of antimony may be effayad by the fol 
 lowing proceffes defcribed by Mr Cramer. 
 
 PROCESS I. 
 
 70 obtain antimony from ils ore. 
 
 ** CHOOSE a melting crucible, or an earthen pot not 
 glazed, th;> may contain ibme common pounds of 
 the ore of antimony, broken into fmall bits. Bore at. 
 the bottom of the crucible fome fmall holes, two lines 
 in diameter. Let the bottom of the vdlel be recei 
 ved by the orifice 01 a fmaller one, upon which it muft 
 be put ; and when the ore is put into it, let it be 
 covered with a tile, and all the joints be flopped with 
 lute. 
 
 * Put thefe vefl'els upon the pavement of a hearth 
 and put ftones all round them at the diftance of fix 
 inches. Fill this intermediate fpace with afhes, fo 
 high that the inferior pot be covered to the upper 
 brim. Then put frefh and burning ccals upon it, 
 and with a pair of hand-bellows excite the fire, till 
 the upper veffel* grow red-hot: take off the fire a 
 quarter of an hour after ; and when the veffels are 
 grown coldj open them. Yob will find that the 
 N n 3 xneltecji 
 
E 43 3 
 
 me s ed ~nt>mony has run through the holes mad? nt 
 the bottom of the upper veiiei into the inferior oae, 
 wkere it is collected." 
 
 PROCESS II. 
 
 'To roafl crude, antiinGny % or iff //v, with or witfaut ad 
 dition. 
 
 "CHOOSE an earthen, fiat, low difli, not glazed} 
 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, bea 
 ten to a pretty caarfe powder, not exceeding a few 
 ounces at once. Put the ciifh upon a fire-p in, having 
 a few burning coals in it : increafe the fire till it begins 
 to fmoke a little. Meanvrhile you mtift mcefianiily move 
 the powder with a piece of new tobacco-pipe ; for 
 this caufes the fulphur to evapotv.te the fooner. If you 
 increafe the fire a little too foon, the powder imme 
 diately gathers into large clots, or even begins to melt. 
 When this happens, take it immediately <-S the fire 
 before it melts entirely. Then pulverife it again, and 
 finally, make a gentle fire under it. Your black 
 ihining powder will ailume an alii colour almoft like 
 that of earth, and become more refra&ory 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 fmoke. If you add to your crude antimony 
 pulverifed, half or an equal quantity of charcoal-daft, 
 and perform the reft as above, die rcafting will be 
 done more conveniently : for it dc es not gather 10 
 eafily into clots, and melts with much greater difficul 
 ty. When part of die fulphur is evaporated, add ibrne 
 fat to it at feveral times. Thus you will fooner finiflr 
 the operation, and the remaining calx will not be burnt 
 to excefs. However, if it be thus expofed to too vio-, 
 kntand long-lafting a fire, a great quantity of it eva 
 porates ; 
 
C 437 1 
 
 poratss-, nor does k ce;iie entirely to frnokc in a jrrcat' 
 tire. And ic will he enough, if, growing middling 
 red-hot, it does no longer emit the unpleaiant fineil ot 
 the acid of fulphur." 
 
 P R O C E S, S III. 
 
 To reduce a calx of atttlmany into a f.mimitL.lic rcgxks. 
 
 " Mix fome calx of antimony w'th a quarter part 
 of the black flax, which put into the crucible. Cover 
 the vellel with a tile ; make the fire as quickly as the 
 veiiel can hear it, hue no greater than is nece'fury to 
 melt the flux. When the whole has been well in fufiOn 
 for half a quarter cf an hour (which may be tried 
 with a tobacco-pipe, taking' off the tile), pour it into 
 the melting cone, which mufi be warm and done over 
 with tallow. Then immediately ftrike the cone feve- 
 ral times. You will find, when the cone is inverted, a 
 regulus, above which is a (aline fcoria," 
 
 The methods of cclcinirg antimcnyly means of nitre r 
 arc described under CHEMISTRY, n e 1252 1265 5 ant ^" 
 thole of obcaining a regiiltis of antimony without a pre^. 
 vious calci nation or roaiting, by throwing a mixture of 
 powdered antimony, tartar, and nitre, into a red-hot 
 crucible, and by fufrag this mixture, and of obtaining 
 a martial regu'uts of antimony > are defcribed at the ar 
 ticle REGULUS. 
 
 SECT. X. Ores of Bifmuth. 
 
 . i. BISMUTH is found native^ refcinbling the re 
 gulus of bifmuth. 
 
 An cfhre cf bi muth, of a whitifh yellow colour, is 
 wien-ticned by Cronftedt ; and is different from 'he 
 ore imprope-ly called powers of I if muth, which is a 
 calx of cobalt. 
 
 Bifmutli is xnineralifed x. By fulplmr. This ore 
 
 has 
 
C 43* ] 
 
 lias the appearance of galena. 2. With futykurated 
 iron. Bifmuth is found alfo in cobalts, and in fomc 
 ores of fiher. 
 
 2. Ores of b':fmutb may be efayed by the follow 
 ing procefs. 
 
 " Bifmuth ore may be melted with the fame ap 
 paratus as was directed for the fufion of crude anti 
 mony out of its ore. Or you may beat your ore to a 
 very fine powder, with the black flux, fandiver, and 
 common fait, 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 femimetal is dcftru&ible and vo 
 latile, you muft as quick as poffible apply to it that 
 degree of fire, which the flux requires to be melted; 
 and fo foon as it is well melted, the veifol muft be ta 
 ken out of the fire ; and when it is grown quite cold 
 and broken, you will find your regulus." 
 
 Mr Gellert directs that ores of biimuth fliould be 
 effcyed by fufmga quintal of pulverifed ore with half 
 a quintal of calcined borax, and half a quintal of pul- 
 vcrifed glafs, in order to vitrify the adherent earths 
 and ftones which envelope the bifmuth. But probably 
 the heat reqviifite for this vitrification would volatilife 
 part of the bifmuth. 
 
 If the ore be of the kinds above defcribed, minera- 
 lifed by fulphur, or by fulphur and iron, a previous 
 roafting would be expedient, which may be performed 
 in the fame manner as is directed for the roafting 
 of kiitimony. 
 
 SECT. XI. Ores of the Regulus ofColalt. 
 
 COBALT is a grey -coloured mineral, with more or 
 lefs of a metallic appearance. Its grain is clofe ; it is 
 compact and heavy, and frequently covered with ,an 
 efflorefcer.ee of peach-coloured flowers. Of this feve^ 
 ral kinds are known. All the true cobalts contain the 
 
 femimetaJ 
 
C 439 ] : 
 
 femimctal called regulus of cobalt, the calx of which 
 becomes blue by vitrification;- This- regulas is' mine- - 
 rallied in cobalt by fulphur, 'and- efpeciaily by a large- 
 quantity of arienic. Some cobalts alib contain bif- 
 muth and filver. 
 
 Audiors -have given the name of cobalt to many mi 
 nerals, although they do not contain the femimctal 
 ubovementioned,- but only becaufe they externally re- 
 imble:therore of the regulus of cobalt. But thefe 
 minerals can only be coniixlered as falfc cobalts. They 
 are diftin-gir.ihable from true cobalt by trying whe 
 ther they can yield the blue glafs calledywra//, and the. 
 iympathetic ink. The red efTiorefcence is alfo a> 
 mark by which true cobalt is diftinguifhabk from the, 
 falfe : 'but this efflorefcence only happens when the ore 
 has been expofed to a moift ai*. 
 
 The principal m hies of -cobalt are in Saxony, where, 
 they are dug ibr the fake of obtaining zaffre,-a55ivrerf 
 blue or frnalt, and arfenic. Very fine cobalt is alfa 
 found in the Pyrenean mountains. It has been. like- 
 wife found in Ccn-nwall and Scotland. And that it ife 
 in the eaftern parts of Afia, appears from the blue co*. 
 louring on old oriental porcelain: but probably die 
 mines difcorered in thefe -countries are nearly exhauft- 
 ed, as contid'erable. quantities- of zafire and-imalt are: 
 exported from Europe to China, i 
 
 Cobalt is heavier than moil other ores, from the 
 large quantity of arfenic it contains ; and-. in this re-' 
 fipcct- it refembles the. ore of tin. 
 
 Befides the grey -or. afh -coloured cobalt above de-. 
 fcribed, which is the moft frequent, other .cobalts- are. 
 found of various colours and textures, mixed with va 
 rious fubfVanees. .Waller ius. enumerates fix fpecies of 
 cobalts. I . The "afl7-c6l'.'iirc(l ore, which is regulus of 
 cobalt mineniliicd by ari-cnic, coftfvfting of lliining 
 ienderucoioureJ .grains* Some ores of this kind -are; 
 compact refemblmg itcel, and others arc ^f a loofe 
 lexturc- and friable. 2. The/ cu/ar ore isblack, lliining 
 
 like 
 
[ 440 ] 
 
 Hke a mirror, and laminated. This fpecies is very 
 rare ; and is fuppofed by Wallerius to be a foliated 
 ipar, or felenites mixed with cobalt, 3. The vitreous 
 vrjtag-tike orv, is of abluiih, (liming colour, compact, 
 or fpongy. 4. CiyJlaJlized ore, is a grey, deep-colour- 
 ed cobalt, confiding ofclufters of cubical, pyramidal, 
 prifmatic cryftals. 5. Flowers of cobalt, red, yellow, 
 or violet. Thefe flowers feem to be formed from fome 
 of the above-defcribed compact ores, decompofed by 
 cxpofure to moid air. This decompofition is fimilar 
 to that which happens to ferruginous and cupreous py 
 rites. 6. The earthy colah is of a greenijh white, or 
 of a yellow colour, and of a foft and friable texture. 
 This fpecies feems to be an ochre of cobalt ; and is 
 formed .perhaps from the flowers of cobalt further de 
 compofed, in the fame manner as a martial ochre is 
 iormed from the faline efflorefcence of decompofmg 
 pyrites ; when this efflorefcence is further decompo- 
 fed by expofure to moift air ; by which the vitrio 
 lic acid contained in it is expelled, and the effloref- 
 cence is changed from a faline ftate to that ot an 
 ochre or calx. 
 
 Befides thefe proper ores, cobalt is alfo found in 
 a blue clay along with native filver, in ores of bif- 
 iButh, and in the mineral called lupfernrteL See 
 NICKEL. 
 
 The effay of cobalt is defcribedat the article REGW- 
 ofCola/t. 
 
 SECT. XII. OretofZinr. 
 
 I. THE proper ore of z,inc is a fubftance which has 
 rather an earthy or ftony than metallic appearance, and 
 is called caJawy, calamlne, or lapis caiim'maris. This 
 ilone, although metallic, is but moderately heavy, and 
 has not the brilliancy of moll other ores. Its colour 
 is yellow, and like that of ruih It is alfo lefs denfc. 
 than other metallic minerals. It feems to be an ore 
 
 naturally 
 
C 44' 3 
 
 naturally dccompofed. The calamine is not work 
 ed direclly to obtain zinc from it, becaufe this 
 would only fucceed in clofe velfels, and coniequent- 
 ly with fmall quantities, according to Mr Margraaf's 
 procefs. But it is fuccefsfully employed for the con- 
 verlion of copper into bra^s by cementation, by which 
 the exigence of zinc in that ftone is fufficiently 
 proved. 
 
 Mr Wallerius enumerates ulfo amonglt the ores of 
 /.inc a very compounded mineral, confiding of zinc, 
 fulphur, iron, and arfenic. This mineral, called blend> 
 refembles externally the ore of lead, and hence has 
 been called fa /fe ga/;na. Thefe blends have different 
 forms and colours ; but are chiefly red, like the red ore 
 of antimony. 
 
 Zinc is obtained from certain minerals in the Eaft 
 Indies, of which we know little. 
 
 Calciform ores of zinc, according to Cronftedt, are 
 pure or mixed. The pure are indurated, and ibme- 
 times cryitallized, refembling lead-fpar. The mixed 
 ore contains alfo fome calx of iron. This is cala;nine. 
 It is whitilh, yellowiih, reddifn, or brown. 
 
 Zinc is minerattfed, l. ~&y ftilphuraied iron. Ort of 
 ~.itic. Wallerius lays, lead is fometimes contained in 
 th's ore. It is white, blue, or brown. 2. ByyW- 
 phur, arfenicy and iron. Blend, or pfsudo-galena, or 
 faife-gakna, or black-jack. Thefe art of various co 
 lours, white yellowiili, brown, reddifh, greeniih, 
 black. They coniift of fcales, or are teifelateld. Mr 
 Cronftedt thinks, that in the blends the zinc is minerali- 
 ied in the Hate of a calx, and in the ore of zinc in its 
 metallic fta*e. ' 
 
 2. Although the minerals above enumerated have 
 been known, from their property of .converting copper 
 into brafs, to be ores of zinc, yet the method of ef- 
 faying them fo as to obtain the contained zinc was not 
 known, or at lead not pubiiilied, bofore Mr MargraaPs 
 Memoir of the Berlin Academy for the year 1 746, 
 
 upon 
 
[ 44' ] 
 
 upon that fubject. That very able chcmift has fhown, 
 >that zinc may be obtained from its ores, from the 
 fiowers, or fiom any other calx of zinc, by treating 
 thefe with charcoal-dull, in clofe veiiels, to prevent 
 the ccmbufhon of the zinc, which happens immediate 
 ly upon its reduction when expofed to air. For this 
 purpofe, he put a quantity cf finely powdered ca- 
 lamme, or roaited Ulend, or other calx of zinc, well 
 mixed with an eighth part cf charcoal-duft, into a 
 ftrong, luted earthen retort, to which he fitted a recei 
 ver. Having placed his retort in a furnace and rsifcd 
 the fire, he applied a violent heat during two hours. 
 When the veflels were cold and broken, he found the 
 zinc in its metallic form adhering to the neck of the 
 retort. 
 
 . The chief difficulty in this operation is to get an 
 earthen retort fufficiently compact to retain the va 
 pour of the zinc (for it eafily pervades the Heffinn 
 crucibles. Stourbrldge melting pots, and fimilar vef- 
 fels, as may be ieen from the quantity of fiowers 
 which appear upon their cuter furface, when zinc or 
 it:; calxes and any inflammable i::- a tier have been ex 
 pofed to heat within thefe veffcls), and at the fame 
 tme -efficiently ftrong to refill the violent fire which 
 Mr Margraaf requires. 
 
 A i <;-ty exact eiiay cf an ore of zinc may be made 
 in the fallowing manner. 
 
 Mix a quantity of pulverifed roafled ore or calx of zinc 
 n eighth part of charcoal-duft. Put this mixture 
 K ft crucible capable of containing thrice ;.he quan- 
 titj Diil life equally amongft this mixture a quantity 
 ol 'm- 11 grahv or tliin plates of copper equal to that of 
 tLecalamine or ore employed, and npon tlie wliole J<iy 
 another equal quantity of grains or plates of copper ; 
 and laftly, cover tjiis latter portion cf copper with 
 charcoal-duft. Lute a lid upon the crucible, and ap 
 ply a red heat during an hour or two. The copper or 
 part of it will unite with the vapour of the zinc, and 
 2 be 
 
[ - 443 J 
 
 he thereby converted into brafs. By comparing the 
 weight of all the metal alter the operation- with the 
 weight of the copper employed, the weight acquired, 
 and consequently the quantity of y,inc unired with the 
 copper will be known. The copper which has not 
 been converted inio hrafs, or more copper whh freih 
 charcoal-duft, may be again added in the fame man 
 ner to the remaining ore, and the operation repeated 
 with a heat fornewhat more intenfe, that any zinc re 
 maining in the ore may be thus extracted. A curious 
 circumftance is, that a much greater heat is required 
 to obtain /inc from its ore by dirt illation, than in the 
 operation now defcribed of making brais ; in which 
 the feparaticn of the zinc from its ore feerns to be fa 
 cilitated by its dilpo.ition to unite with copper. 
 
 SECT. IV. Ores cf slrjl-nic. 
 
 tf i . T H E minerals which contain the larg eft quantity 
 of arfenic 'are cobalts and white pyrites ; although it is 
 alib contained in other crcs, ir being one of the mine- 
 lalifing fubfiances. But as coba.it muft be roailed to 
 obtain the fulphur it contains, the arfenic alib which 
 riles daring this toneiac'tion is collected, as we lhall 
 i^e i;i part III. (SMELTING oi O:IES), ana the particu 
 lar articles of each of the metallic iubitances nieniion- 
 cJ in this article. 
 
 I. Regulus cf arfenic is found native. It is of a 
 leaden colour ; it barns with a final 1 Mame ; and is- dif- 
 iipa-eJ, leaving generally a very frnall quantity of calx 
 t-.f bifm'ith,or of c; ! k of cobalt, and a very little iilver. 
 Vvhea it is of a ibli-.l r t nd teUaceous texiurc, it has 
 been improperly called tjli-.wtT colalt, in German 
 fcherbewfbalt* II. Calx o, 1 ar ionic isiound in iorm < -f 
 powder*; native rlc vv.r:, of arfenic, or cf indurated fe- 
 nitr;m parent crylfa S ; native cryllalline arfenic. 
 Ill . Galx of arjfe : -axed, i. With f ilphur ; when 
 \cllov.', U is culled Qri-ini*ntj> \vheii red, it is called 
 O o 
 
C 444 ] 
 
 tialiw realgar : the difference of colour dedends o> 
 the proportion of the two component parts. 2. With 
 calx of tin ; tin-grains. 3. With fulphur and iilver, 
 in the red filver ere. 4. With calx of lead, in the lead- 
 fpar. 5. With calx of cobalt, in ' the efflorefcence of 
 cobalt. IV. Arfenic is miner alife'd, j . With fiilphii- 
 xated iron ; arfenical pyrites. 2. With iron only; 
 white pyrites, or mifpickle. 3. With- cobalt, in al- 
 Hicil all cobalt-ores. 4. With filver. 5. With cop 
 per. 6. With antimony. 
 
 2. Arfenic may be feparated from its ore or earthy 
 matter with which it happens to be mixed, by fub- 
 limation, according to the following proceis by Mr 
 Cramer. 
 
 " Do every thing as was fatd about mercury, or 
 fulphur ; but let the veifel which is put into the fire 
 with the ore in it be of earth or ftone, and the reci 
 pient be of glafs, and of a middling capacity. Nor is 
 it necefTary that this fhould be filled with water, fo it 
 be but well luted. The fire mud likewife be ftronger 
 and continued longer than for the extracting or' ful 
 phur. Nevertheless, every kind of arfer.ic cannot be 
 extracted in a conlinedfire : for it adheres to the ma 
 trix more ftrongly th.ui fulphur and mercury. You 
 will find in the part of the veflel which is more re 
 mote from the fire pulverulent and fubtile flowers of 
 ar&.nic ; but there will adhere to the poilerior of the 
 v neck of the retort fmall folid malfes, fnining like frnall 
 cryftals, traniparent, fometimes gathered, into a falid 
 , iliblimate, and perfediy whit?, if the ore of the arfe- 
 t .nic was perfectly pure ; which neverthelefs happens 
 very feldoin. The Mowers are moft commonly thin, 
 and of a grey colour : which proceeds from the phlo- 
 -gi (lion mixed .with the mafs. They are often of a ci- 
 tran or of ii golden colour, which is a fign that there 
 is in the mixture fome mineral fulphur: and if the 
 fablmate be red or yellovV, it is a fign of much ful 
 phur. 
 
 As 
 
t 445 J 
 
 " As all the arfenic contained in the ore is not ex 
 pelled in cloie velTels, you muft weigh the relidaum ; 
 then roatl it in a crucible till it fmokea 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 
 thus to know how much arfenic remained in the dole 
 veffel, unkft the ore contain bifmuth." 
 
 If the arfenic be .fulphurated, it may be purified bf 
 triturating it with mercury or with fixed alkali, and 
 by fubliming the arfenic from the remaining fulphu- 
 rated mercury or alkali. The method of abtaining a 
 regulus of arfenic is defcribed at the article RSGVLUS tf 
 jlrfnlc. 
 
 P A R T. III. 
 SMELTING OF ORES. 
 
 HAviNG fliown the nature of the principal metalli^, 
 minerals, and the fubftances of which they are 
 compofed ; and alfo explained the procefles by which 
 an exacl: analyfis of thefe compound minerals may be 
 made, and the nature and quantity of the contained 
 metals may be known ; in order to complete what re- 
 lates to this important fubj eft, we fhall defcribe in this 
 Part the principal operations by which metals, &c. 
 are obtained " in the great/' as it is called, or for 
 commercial purpofes. What we (hall fay upon this 
 fubjeft will chiefly be extracted from a 7ra?/// on tie 
 Smelting of Ores, by Scbluttcr> tran-flated from the 
 O o 2 German 
 
C 44<5 3 
 
 German into French by M. Hellot ; becaufe this, of 
 "all the modern works upon that fubjec~r, appears to be 
 the moft exact. We faall flrft ckfcribe the opera 
 tions upon pyritous matters for the extraction of fu.l- 
 pliur, &c. and afterwards the operations by which me 
 tallic fubilances are extracted from ores properly fo cal 
 led. 
 
 SECT. I. Extrafihn of fulplur from Pyrites and 
 other Minerals* 
 
 IN order to obtain fulphur from pyrites, this mine 
 ral ought to be expofed to a heat fuHicient to fublime 
 the fulphur or to make it diitil in vcffels, which mult 
 be clofe, to prevent its burning. 
 
 Sulphur Is extracted from pyrites at a work at 
 Schwart/ember, in Saxony, in the high country ot* 
 the mines ; and in Bohemia at a place called Alien- 
 SditeL 
 
 The furnaces employed for this operation are ob- 
 Jong, like vaulted galleries ; and in the vaulted roofs 
 are made feveral openings. Thefe are czMedfurjuues 
 for extraftingfiilphur. 
 
 In thefe furnaces are placed earthen-ware tubes, fill 
 ed with pyrites broken into pieces of the fr/e of iinall 
 nuts. Each of thefe tubes contains about 50 pounds 
 of pyrites. They are placed in the furnace iilmofl ho- 
 ri/cntally, and have icareely more than an inch of tie- 
 icent. The ends, which come out of the furnace five 
 or fix, inches, become gradually narrower. Withm 
 each tube is fixed a piece of baked earth, in form of it 
 itar, at the place where it begins to become r.arrow- 
 tr, in order to prevent the pyrites from failing our, 
 or choakir.'g the mouth of the tube. To each tube is 
 fitted a receiver covered with a leaden pipe, pierced 
 with a frnall hole to give air to the fulphur. The 
 other end of the tube is exactly clofed. A moderate 
 jGre is made with wood, and in eight hours the fuj. 
 
 phui 
 
C 447 ] 
 
 pbur of the pyrites is found to have paifed into the rs- 
 ceivers. 
 
 The refiduum of the pyrites, after the diftilLition, 
 is drawn out at the large end, and fre(h pyrites is 
 put in its place. From this refiduum, which is called 
 btfrititigs of fulphur^ vitriol is extracted. 
 
 The 1 1 tubes into which were put, at three feveral 
 di foliations, in all nine quintals, or 900 pounds of 
 pyrites, yield from 100 to 150 pounds of crude ful- 
 phur, which is fo impure as to require to be purified 
 by a fecond di ft illation. 
 
 This purification of crude fulpbuf is alfo done in a 
 furnace in form of a gallery, in which five iron cucur 
 bits are arranged on each fide. Thefe cucurbits are 
 placed in a doping direction, and contain about eight 
 quintals and a half of crude fulphur. To them are 
 kited earthen tubes, fo dilbofed as to anfwer the pur- 
 pofe of capitals. The nofe of each of thefe tubes 
 is inferted into an earthen pot called -&\t fore-runner. 
 
 This pot has three openings ; namely that which 
 receives the nofe of the tube ; a fecond fmaller 
 hole, which is left open to give air ; and a third 
 in its lower part, which is flopped with a wooden 
 peg. 
 
 When the preparations are made, a fire is lighted 
 about feven o'clock in the evening, and is a liitle 
 abated as foon as the fulphur begins to diftil. At 
 three o'clock in the morning, the wooden pegs which 
 flop the lower holes of the fore-runners are for the 
 firll time drawn out, and the fulphur flows out of each 
 of them into an earthen pot with two handles, placed 
 below for its reception. In this diitillation the fire 
 jriuft be moderately and prudently conducted ; other-. 
 wifelefs fulphur would be obtained, and it alfo would 
 .be of a grey colour and not of the fine yellow which. 
 it ought to have when pure. The ordinary lofs in 
 the purification of eight quintals of crude fulphur is 
 at moft, one quintal. 
 
 003 When 
 
t 44* 3 
 
 When all the fulphur has flowed out, -and has coolccf 
 little in the earthen-pots, it is caft into moulds made 
 of beech tree, which have been .previoufly dipt in wa- 
 ter and fet to drain. As foonas the fulphur is cooled 
 in the moulds, they are opened, and the cylinders of 
 fulphur are taken out and put up in cafks. Thefe are 
 called roll-lrhaftons. 
 
 As fulphur is not only in pyrites, but alfo in molt 
 metallic minerals, it is evident that it might be ob 
 tained by works in the great from the different ores 
 \vhichcontainimich of it, and from which it muft be 
 feparated previoufly to their fufion : but as fulphur is 
 of little value, the trouble of collecting it from ores 
 is feldom taken. Smelters are generally iatisfied with 
 freeing their eres from it, by expoiing them to a fire 
 fufficient to expel it. This operation is called torre*^ 
 fafticin, or roajling of ores. 
 
 There are, however, ores which contain fo much 
 fulphur, that part of it is actually collected in the or 
 dinary operation of roafting, without much trouble 
 for that purpofe. Such is the ore of Ramelfberg in 
 the country of Hartz. 
 
 This ore, which is of lead, containing filver, is 
 partly very pure, and partly mixed with cupreous py 
 rites and filver ; hence it is neceffary to roalt it. 
 
 Tluroafthig is performed by laying alternate ftrata 
 of ore and wood upon each other in an open field, 
 taking care to diminiih the fize of the ftrata as they 
 rife higher ; fo that the whole mafs (hall be a qua 
 drangular pyramid truncated above, whofe bafe is 
 about 31 feet fquare. Below, fome, paffages are left 
 open, to give f;ee entrance to the air; and the fides 
 and top of the pyramid are covered over with fmall 
 ore, to concentrate the heat and make it laft longer. 
 In the centre of this pyramid there is a channel which 
 defcends vertically from the to top the bafe. When 
 all is properly . rianged, ladlefuls of red-hot fcoria 
 frcin the imelting furnace are throve dov.-n-the chan 
 nel* 
 
C 449 3. 
 
 nel, by which means the ihrubs and wood placed below 
 for that purpoie are kindled, and the fire is from them, 
 communicated to all the wood of the pile, which con 
 tinues burning till the third day. At that time the 
 fulphur of the mineral becomes capable of burning 
 fpontaneoufly, and of continuing the fire after the 
 wood is confumed. 
 
 When this roatting has been continued 15 days 
 the mineral becomes greaiy; that is, it is covered 
 over with a kind of varnifh ; 20 or 25 holes or hol 
 lows are then made in the upper-part of the pile in 
 which the fulphur is collected. From thefe cavities 
 the fulphur is taken out thrice every day, and thrown 
 into water. This fulphur is not pure, but crude j and 
 is therefore fent to the manufacturers of fulphur, to be 
 purified in the manner above related. 
 
 As this ore of Rameliberg is very fulphureons, the 
 firft roafting, v. hich we are now defcribing, lafts three 
 months; and during this time, if much rain has not 
 fallen, or if the operation has not failed by the pile 
 failing down or cracking, by which the air has fo 
 much free accefs, that the fulphur is burnt and con- 
 fumed, from 10 or 20 quintals of crude fulphur are by 
 this method collected. 
 
 The fulphur of this ore, like that of 'mod others, 
 was formerly neglected, till in the year 1570, a per- 
 ion employed in the mines called Chrijiop.cr Sander 
 difcovered the method of collecting it, nearly as it is- 
 done at preient. 
 
 Metallic minerals are not the only fubftances from 
 which fulphur is extracted. This matter is diffufed 
 in the earth in fuch quantities, that the metals cannot 
 abforb it all. Some fulphur is found quite pure, and 
 in different forms, principally in the neighbourhood 
 of volcanoes, in caverns, and in mineral waters. Such 
 are the opaque kind called vlrgin-fufykur ; the tranfpa- 
 rcnt kind called fulphur cf ^uiio ; and the native 
 flowers of fulphur, as thoie of the waters of Aix-la- 
 
 Chapelle. 
 
[ 450 ] 
 
 Chapelle. It is alib found mixed with different 
 earths. Here we may obferve, t'.at all thofe kinds of 
 fulphur which are not minerali/ed by metallic fub- 
 ftances, are found near volcanoes, or hot mineral wa 
 ters, and confequently in places where nature ieerns 
 to have formed great fubterranean laboratories ; in 
 which fulphureous minerals may be analysed and de- 
 compofed, and the fulphur feparated, in the manner 
 in which it is done in final! in our works and labora 
 tories. However that be, certainly one of the bed 
 and moft famous fulphur-mines in the world is that 
 called Sofatara. 7"he Abbe Nollet has published, 
 in the Memoirs of the Academy, fonie intereiling ob- 
 fcrvations upon this fubjccl, which we iliall here- 
 abridge. 
 
 Near Puzzoli, in Italy, is that great and famous 
 mine of fulphur and alum called at prefent Solfatara. 
 It is a fmall oval plain, the greater! diameter of which 
 is about 400 yards, railed about 300 yards above the 
 level of the fea. It is Surrounded by high hills and 
 great rocks, which fall to pieces, and whole fragments 
 form very fteep banks. Almoft all the ground is bare 
 and white, like marie, and is every where fenfibly 
 warmer than the atm*>fphere in the greateft heat of 
 furnmer, fo that the feet of perfons walking there are 
 burnt through their fhoes. It is impoilible not to 
 obfcrve the fulphur there; for every- where may be per 
 ceived by the fmell a fulphureous vapour, which rifes 
 to a considerable height, and gives reafon to believe 
 that there is a fubterraneous nre below, from which 
 that vapour proceeds. 
 
 Near the middle of this field there is a kind of ba- 
 fon three or four feet lower than the reft of the plain, 
 in which; a found may be perceived when a perfon 
 walks on it, as if there were under his feet feme great 
 cavity, the root of which was very thin. After that 
 .the lake Agnano is perceived, whofe waters feem to 
 toil. Thefe waters are indeed hot, but not fo hot as 
 
 boiling 
 
[ 4S 3 
 
 boiling water. This kind of ebullition proceeds from 
 vapours which rife from the bottom of the lake, 
 , which being let in motion by the action of fubterra- 
 nean fires, have force enough to raife all that mafs of* 
 water. Near this lake there are pits, not very deep, 
 from which fulphnreous vapours are exhaled. Per- 
 ibns who have the itch come to thefe pits, and receive 
 the vapours in order to be cured. Finally, there are 
 .Ibme deeper excavations, whence a ibft ftone is pro 
 cured which yields fulphur. From thefe cavities va 
 pours exhale, and iiTue out with noife, and which are 
 nothing elfe than fulphur fubliming through the cre 
 vices. This fulphur adheres to the fides of the rock?, 
 where it forms enormous malTes: in calm weather, the 
 vapours may be evidently feen to rife 25 or 30 feet 
 from the iurface of the earth. 
 
 Thefe vapours, attaching themfelves to the fides of 
 rocks, form enormous groups of fulphur, which fome 
 times falls dov/n by their own weight, and render thefe 
 places of dangerous accefs. 
 
 In entering the Solfatara, there are warehonfes and 
 buildings creeled fcr the refining of fulphur. 
 
 Under a great med, or hangar, fupported by a wall 
 behind, and open on the other three fides, the fulphur 
 is procured by diftillation from the foil ft ones we men 
 tioned above. Thefe ftones are dug from under ground ; 
 and thofe which lie en the iurface of the earth are 
 negkcled. Thefe laft are, however, covered with a ful 
 phur ready formed, and of a yellow colour : but the 
 workmen fay they have loft their ftrength, and that the 
 fulphur obtained from them is not of fo good a quality 
 as the fulphur obtained from the ftones \vhicharedug 
 out of the ground. 
 
 Thefe lail mentioned are broken into lumps, and 
 put into pots of earthen ware, containing each about 
 20 pints Paris meafure. The mouths of thele pots are 
 ;is \vide as their bottoms; but their bellies, or middle 
 parts, are wider. They are covered with a lid of the 
 
 iame 
 
C 45^ 1 
 
 fame earth, well luted, and are arranged in two paral 
 lel lines along two brick walls, which form the two 
 fides of a furnace. The pots are placed within thefe 
 walls ; fo that the centre of each pot is in the centre 
 of the thicknefs of the wall, and that one end of the 
 pots overhangs the wall within, while the oiher end 
 overhangs the wall without. In each furnace ten ot 
 thefe pots are placed ; ^that is, five in each of the two 
 walls which form the two fides of the furnace.'* Be 
 twixt thefe walls there is a fpace of 15 or 18 inches ; 
 which fpace is covered by a vault refting on the two 
 walls. The whole forms a furnace feven feet long, two 
 feet and a half high, open at one end, and fhut at the 
 other, excepting a fmall chirnney through which the 
 fmoke pafios. 
 
 Each of thefe pots has a mouth in its upper part 
 without the furnace, in order to admit a tube of 1 8 lines 
 in diameter and a foot in length, which communicates 
 with another pot of the fame fize placed without the 
 building, and pierced with a round hole in its bafe of 
 .15 or 18 lines diameter. Laftly, to each of thefe laft- 
 mentioned pots there is a wooden tub placed below } in 
 a. bench made for that purpofe. 
 
 Four or five of thefe furnaces are built under one 
 hangar, or ftied. Fires are kindled in each of them at 
 the fame time ; and they are thrown down after each 
 diftillation, either that the pots may be renewed, or 
 that the refiduums may be more eafily taken out. 
 
 The fire being kindled in the furnace, heats the firfl 
 pots containing the fiilphureous ftones The fulphur 
 rifes in fumes into the upper part of the pot, w r hence 
 it paffes through the pipe of communication into the 
 external veifel. There the vapours are condenfed, be 
 come liquid and flow through the hole below into the 
 tub, from which the fulphur is eafily turned out, be- 
 caufe the form of the vefiel is that of a truncated cone 
 whofe narrower end is placed below, and becaufe the 
 hoops of the tub are fo fattened that they may be oc- 
 
 cafionally 
 
C 453 ] 
 
 cafionally loofened. The mafs of iulphur is then car 
 ried to the buildings mentioned before, where it is re- 
 melted for its purification, and caft into rolls, fuch as 
 we receive it. 
 
 Extraflicn of FITZIOL from pyritss. See CHEMI 
 STRY, 
 
 Extraction of ALUM from, pyritoiu fubjlances and 
 from aluminous tarths. See CHEMISTRY. 
 
 SECT. II. Smelting 'if Ores in gsncraL 
 
 i. As ores confift of metallic matters combined 
 with fulphur and arfeilic, and are betides intermixed 
 with earthy and (tony fub-tances of ail kinds, the in 
 tention of all the operations up-vii tlicie compound bo 
 dies is to leparate the.'e different fubHancfS fi m eacli 
 otiier. This is --:fl\^c-;d 07 feveral operations founded 
 on the known pr perties of iho/e .ublVm-jes. We now 
 proceed to give a general idea of tlicfe feveral opera 
 tions. 
 
 Firft of all, the ore is to be f.parat' d from the 
 earths and (tones accidentally adherent to it; and when 
 thde foreign fub.uinces are in large m.ifies, and are not 
 very intimately mixed in {mail particles with the ore, 
 this reparation may be accompli, hed by mechanic.:! 
 m 'uns. Tills ought always to be the firil operation, 
 imlefs the adhereat iubitance be capable of isrving as 
 a flux to the ore. If the unmetallic eardis be inti 
 mately mixed with the ore, this mad nj_eifirily be 
 broken and divided into fmall particles. This opera- 
 tivj.i is performed by a machine v/liich moves pe files, 
 caliei//-?^;"^/ or//-7.v^..r/. Af:er this operation, wheii 
 ta? patts of the miaeral are fpecilically heavier than 
 tho;c of the unmetallic earch or Hone, thcfj latter may 
 .b^feparated from the ore by wafhing in canals through 
 which wa'cr flows. With regard to this wafh'iig of 
 ores, it is neeeilary to obfjrve, .that it-canmt. facceed 
 but when the ore is fonfibly heavier than the foreign 
 
 matters. 
 
[ 454 ] 
 
 matters- But tie contrary happens frequently, as well 
 becaufe quarts and fpar are naturally very ponderous, 
 as becaufe the metallic matter is proportionally fo 
 much lighter as it is combined with more fulphur. 
 
 When an ore happens to be of this kind, it is necef- 
 fary to begin by roalting it, in order to deprive it of 
 the greateft part of its fuiphur. 
 
 It happens frequently that the pyritous matters ac 
 companying the ore are fo hard that they can fcarcely 
 be pounded. In this cafe it is neceiTary to road: it en 
 tirely, or partly, and to throw it red hot into cold wa 
 ter ; by which the ftones are fpltt, and rendered much 
 jr.ore capable of being pulveriied. 
 
 Thus it h-.ippens very frequently, that mailing is the 
 firft operation to which an ore is expole-J. 
 
 When 'he iubftanee rf the ore is very iuP.ble, this 
 firft operation may be dilpeiaed \v >h. and die matter 
 may be immediately filled without any previous roaft- 
 ing, or at lea ft with a very {light MK-. For, to effect 
 ihis fufion, it is iKee.Ta.ry thai it retain a great quan 
 tity of its fulphur, which, with the other fluxes added, 
 ferves to deilroy or convert into fcoria a confidcrable 
 part (-{'the fkmy matter of :hc mineral, ai.d to rerhice 
 the rcil into a brittle fubflance, which i? ca;led the matt 
 cf lead or of copper, or rthei metal (ROtitsine'd in tl.-e 
 ore. This matt is theicf^rr: an ir.tr rn',diar - matter be 
 twixt the mineral tnd the meta'i ; icr u c in^-::-l is there 
 concentrated, and irixcd with lei's ftfekft ^natter than 
 it was in the ere. But as this matt is always Inlpliu- 
 reous, the metai whidi ir contains cannot have its me 
 tallic f roperties. Therefore it rrnit be roarled ieveral 
 times to tv.--.perate viie fulphur, before it is remelted, 
 \vhentliepurcineta 1 . is required. This funon cf an ore 
 not r< alted, or but ilightiy icaiied, is called crude fu- 
 Jkn. 
 
 We may here obferve upon the fub'ecl cf wailiing 
 arid reading- oi OILS, f li.it as nrfciiic is heavier than lui- 
 phur, and has nearly the weight t-f niclais, the f res in 
 
 v.i.ich 
 
C 455 J 
 
 which it prevails arc generally very hcav", and ctnle- 
 quently are fuiccpiihlc of being wafhed, 'which is a 
 great advantage. But on the other ride, as artenic is 
 capable of volaliring, fcoriiying, and deitroying many 
 metals, thefe ores have diladvantages in the roaiting 
 and fufion, in both which confiderable lofs is caufed' 
 by the arienic. Some ores contain, belides arienic, 
 other volatile femimetuls, fuch as antimony and /inc.' 
 Thefe are almoit nntraclable, and are therefore neglec 
 ted. They are called miners rap&ces^ *' rapacious 
 ores." 
 
 When the metal has been freed as much as is pof- 
 iible from foreign matters by theie preliminary opera 
 tions, it is to be completely purified by fulions more 
 or lefs frequently repeated ; in which proper additions 
 are made, either to abforb the re 11 of the fulphur and 
 arfenic, or to complete the vitrification or fcorification 
 of the immetallic {tones and eaith. 
 
 Laftly, as ores frequently contain feveral different 
 metals, thefe are to be feparated from each other by 
 proceffes fuited to the properties of thefe metals, of 
 which we {hall fpeak more particularly as we proceed 
 in our examination of the ores of each metal. 
 
 2. To facilitate the extraclion of metallic fnb- 
 ftances from the ores and minerals containing them, 
 fome operations previous to the fufon or fmelting of 
 thefe ores and minerals are generally neceiFary. Thefe 
 operations confift of, i. r hz feparation of the ores and 
 metallic matters frc.m the adhering unmetailic earths 
 and ftones, by hammers and other mechanical inftru- 
 ments, and by \vaihing with water. 2. Their divi- 
 Jwn or reduction into fmaller paits by contufion and 
 trituration, that by another walhing with water they 
 may be more perfectly cleanfed from extraneous mat 
 ters, and rendered fitter for the fubfequent operations, 
 calcination or reading, and fufion. 3. Roafting or cal 
 cination ; the ufes of which operation, are, to expel, the 
 volatile ufelcfs, or noxious fubftances, as water, vitrio- 
 P p lie 
 
He acid, fulphur, and arfenic ; to render the ore mo~e 
 friable, and fitter for the fubfequent contufion and iu- 
 ficn; and, lailly, to calcine and deftroy the viler me 
 tals, for inftance the iron of copper-ores, by means 
 of the fire, and of the fulphur and arfenic. Stones, as 
 quartz, and flints, containing metallic veins or particles 
 are frequently made red-hot, and then extinguiilied in 
 cold water, that they may be rendered fufficiently fri 
 able and pulverable, to allow the feparation of the me 
 tallic particles. 
 
 Roafting is unneceilary for native metals ; for fome 
 of the richer gold and filver ores; for fome lead-ores 
 the fulphur of which may be feparated during the fu- 
 fion; and for many calciform ores, as thefe do not ge 
 nerally contain any fulphur or arfenic. 
 
 In the reading of ores, the following attentions muft 
 be given, i. To reduce the mineral previoufly into 
 fmall lumps, that the furface may be increafed ; but 
 they muft not be fo fmall, nor placed fo compactly, as 
 to prevent the pafiage of the air and flame. 2. The 
 larger pieces muft be placed at the bottom of the pile, 
 where the greateft heat is. 3. The heat muft be gra 
 dually applied, that the fulphur may not be melted, 
 which would greatly retard its expulfion ; and that the 
 fpars, fluors, and ftcnes, intermixed with the ore, may 
 not crack, fly, and be difperied. 4. The ores not 
 thoroughly roailed by one operation muft be expofed 
 to a fecond. 5. The fire may be increafed towards 
 the end, that the noxious matters more ftrongly ad 
 hering may be expelled. 6. Fuel which yields much 
 flame, as wood and foflil coals free from fulphur, is 
 faid to be preferable to charcoal or coaks. Sometimes 
 cold water is thrown on the calcined ore at the end 
 of the operation, while the ore is yet hot, to render 
 it more friable. 
 
 No general rule can be given concerning the dura 
 tion or degree of the fire, thefe being very various ac 
 cording to the difference of the ores. A roafting du 
 ring 
 
iiitg :i tVw hours or days is firfacient for many ores ; 
 while lome, fuch as the ore of Ramelfberg, require 
 thai it fhoukl b. continued during feveral months. 
 
 tSchhit'er enumerates five methods of roafting ores. 
 r. By C'mflrucYm^ a pile of oi-ss and fiul placed in al 
 ternate ilrnia, ii\ thj open air, without any furnace. 
 2. By confining I'uch a pile within walls, hut without: 
 a roof. 3. By jiliu'ln^ the pile under a roof, without 
 Literal walls 4. By placing the pile in a furnace con 
 fiding of wails and a roof. 5. By roafting the ore in 
 a reverfeeratory furnace, in which it mud be continually 
 ilirred with an iron rod. 
 
 Several kinds of fufions of ores may be diftmguifn- 
 ed. i. When a fulphureous ore is mixed with much 
 earthy matter, from which it cannot be eafily fepara 
 ted by mechanical operations, it is frequently melted, 
 in order to difengage it from thefe earthy matters, and 
 to concentrate its metallic contents. By this fufion, 
 ibme of the fulphur is diffipated, and the ore is redu 
 ced to a ftate intermediate betwixt that of ore and of 
 metal. It is then called a malt (lapis fulphureo-metdlU' 
 ens) ; and is to be afterwards treated like a pure ore 
 by the fecond kind of fufion, which is properly the 
 i'melttng, or extraction of the metal by fufion. 2. By 
 this fufion or fmelting, the metal is extracted from the 
 ore previoully prepared by the above operations, if 
 thefe be neceifary. The ores of fome very fufible me 
 tals, as of bifmuth, may be fmelted by applying a heat 
 iufficient only to melt the metals, which are thereby 
 feparated from the adhering extraneous matters. This 
 reparation of metals by fufion, without the vitrification 
 of extraneous matters, may be called eliquatlon. Ge 
 nerally, a complete fufion of the ore and vitrification 
 of the earthy matters are neceflary for the perfect fe- 
 paration of the contained metals. By this method, 
 inetals are obtained from their ores, fometimes pure, 
 and fometimes mixed with other metallic fubdances, 
 from which they maft be afterwards feparated ; as we 
 Pp 2 (halt 
 
[ 458 ] 
 
 fee when we treat of the extraction of particu- 
 lir metals. To procure this reparation of metals from 
 ores, thefe nmft be fo thinly liquefied, that the fmall 
 metallic particles may difeng^ge themlelves fnm the 
 fcoria; but it muft not be fo thin as to allow the me 
 tal to precipitate before it be perfectly difengaged 
 irom any adhering extraneous matter, or to pervade 
 and deitroy the containing veflels and furnace. Some 
 v>res are fufficiently fuiible ; but others require certain 
 additions called faxes, to promote their fufion and the 
 v\\ .rilication of their unmetallic parts ; and alib to ren 
 der the fcoria fufficiently thin to allow the feparation 
 of the metallic particles. 
 
 Different fluxes are fuitable to different ores, accor- 
 ding to the quality of the ore, and of the matrix, or 
 ilone adherent to it. 
 
 The matrixes of two different ores of the fame me 
 tal frequently ferve as fluxes to each other; as, for in- 
 .itance, an argillaceous matrix \vith one that is calca- 
 reous : thefe two earths being difpofed to vitrification 
 when niked, though each of them is fmgly unfuftble. 
 For this reafon, two or more different or^s to be fmelt- 
 cd are frequently mixed together. 
 
 The ores alfo of different metals require different 
 fluxes. Thus calcareous earth is found to be the belt 
 jilted to iron-ores; and fpars and fcoria to fuiible ores 
 of copp:r. 
 
 The fluxes mod frequently employed in the fmelt- 
 ing of ores are, calcareous earths, iluors or vitreous 
 fpars, quartz, and fand, fuiible ftones, as ilates, bafal- 
 tes, thefeveral kinds of fcoria, and pyrites. 
 
 Ca j careous earth is tiled to facilitate the fufion rf 
 ores of iron, and of fome of the poorer ores of copper, 
 and, in general, of ores mixed with argillaceous earths, 
 or with felt fpar. This earth has been fometiines add 
 ed with a view of feparating the fulphur, to which it 
 very readily unites : but by this union the fulphur is 
 detained, and a hepar is formed, which readily diffolves 
 
 iron 
 
C ' 4J9 ] 
 
 Iron and other metals, and fo firmly adheres to them,, 
 thatthey cannot be feparated without more difficulty 
 than they could from the original ore. This addition 
 is therefore not to be made till the fulphur be previ- 
 oufly well expelled. 
 
 Filters QIC fujibk fpars facilitate the fufion of moft 
 metallic minerals, and aiib of calcareous and argilla 
 ceous earths, of ileatites, afbeftus, and fome other un. 
 fufible ftones, but not of fiiiceous earths without a* 
 mixture of calcareous earth. 
 
 Quartz is fometimes added in the fufion of ferrugi 
 nous copper ores, the ufe of which is faid chiefly to be, 
 to enable the ore to receive a greater heat, and to give 
 a more perfect vitrification to the ferruginous fcoria.. 
 
 Thc-fvfiMe-Jhn&i zsJJates, bafaltes, are fo tenacious 
 and thick when fufed, that they cannot be confidered 
 properly as fluxes, but as matters added to lefien the 
 too great liquidity of fome very fufible minerals. 
 
 The fcoria obtained in the 'fufion of an ore is fre 
 quently ufeful to facilitate the fafion of an ore of the 
 lame metal, and fometincs even ores of other metals. 
 
 Sitbbnraied pyrites greatly promote the fufibility of 
 the fcoria of metals, from the falphur it contains. It 
 is chiefly added to diincultly-fufible copper-ores, to 
 form the fulphureous compounds called matts, that the 
 ores thus brought into firilon may be feparated from 
 the adhering earthy matters, and that the ferruginous 
 mutter contained in them may be deitroyed, during 
 the fubfequent calcination and fufion, by means of the 
 fulphur. 
 
 A* in the ores called calciform, the metallic matter 
 exifts in a calcined ftate ; and as calcination reduces 
 the metals of mineralifed ores (excepting the perfect 
 metals ) to that ftate alfo ; therefore all calciform and 
 calcined ores require the addition of fome inflammable 
 fubftance to reduce them to a metallic ftate. In great 
 works, the charcoal or other fuel ufed to maintain the 
 fire produces alfo this effect. 
 
 P p 3 Mttal* 
 
C 460 ] 
 
 Metals are fometimes added in the fufion of ores of 
 ether more valuable metals, to abforb from thefe ful- 
 phur cr arfenic. Thus iron is added to fulphurated, 
 cupreous, and filver ores. Metals are alfo added in the 
 tulion of ores of other more valuable metals, to unite 
 with and collect the fmall particles cf thefe difperfed 
 through much earthy matter, and thus to affift their 
 precipitation. With thefe intentions lead is frequently 
 added to ores and minerals containing gold, filver, or 
 copper. 
 
 Ores of metals are alfo fometimes added to alTift the 
 precipitation of more valuable metals. Thus antimony 
 is frequently added to affift the precipitation of gold 
 intermixed with other metallic matters. Thus far of 
 fmelting of ures in general. 
 
 SECT. III. Smelting of Ores of Silver. 
 
 I. As fiver, even' its proper ores, as always al 
 layed with fame ether metals from which it is intend 
 ed to be fe para ted alter the filver-ors has been -well 
 roaited, it muit be mixed with a greater or lefs quan 
 tity of le id previous to its fufion. 
 
 Lead has the fame effect in fufion of gold and filver 
 as mercury has upon thefe metals by its natural fluidi 
 ty ; that is to fay, it unites with them, and feparates 
 them from immetallic matters, which, being lighter, 
 rife always to the furface. But lead has the further 
 advantage of procuring, by its own vitriiication, that 
 of all metallic fubftances, excepting gold and filver. 
 Hence it fellows, that when gold and filver are ob 
 tained by means of mercury, they ftill remain allayed 
 with other metallic fubftances ; whereas when they are 
 obtained by fufion and fcormcation with lead, they are 
 then pure, and not allayed with any metals but with, 
 each other. 
 
 In proportion as the lead, which has been united to 
 $he geld and filver of the oiv, is fcoriiicd by the. 
 
C 46' ] 
 
 aftion of the lire, and promotes the fcorincation of 
 the other metallic matters, it feparates the perfect 
 metals, and 'carries with it all the others to the fur- 
 face. There it meets the unmetallic fubftances, which 
 it likewife vitrifies, and which it changes into a per 
 fect fcoria, fluid, and fuch as a icoria ought to be to 
 admit all the perfect metal contained in it to precipi 
 tate. 
 
 When all heterogeneous matters have been thus 
 difengnged by fcorification with lead, the perfect 
 metals, to which fome lead ftill remains united, are 
 to he funher purified by the ordinary operation of 
 the cupel. 
 
 The common rule for the fufion and fcorification of 
 filver-ore with lead, is to add to the ore a quantity of 
 lea J. fo much greater as there is more matter to be fco- 
 ritied, and as thefe matters are more refractory and of 
 more difficult fufion. Silver ores, or thofe treated as 
 fuch, are often rendered refractory by ferruginous 
 earths, pyritoiis matters, or cobalts, containing al 
 ways a confiderable quantity of an earth which is un 
 metallic, very fubde, and very refractory, and which 
 renders a confiderable augmentation cf the quantity of 
 lead necelfary. 
 
 The quantity of lead which is commonly added to 
 fufible iilver ore?, that do not contain lead, is eight 
 times the quantity of the ore. But when the ore is 
 refractory, it is neceffary to add twelve times the 
 quantity of lead, and even more ; alfo glafs of lead, 
 and fluxes, fuch as the w r hite and black fluxes ; ta 
 which however borax and powder of charcoal are pre 
 ferable, on account of the liver of fulphur formed by 
 thefe alkaline fluxes. 
 
 It is necellary to obferve, that faline fluxes are only 
 ufed in fmall operations, on account of their dearnefs. 
 To thefe are fubftituted, in the great operations, of 
 which we now treat, fandiver, fafible fcoria, and other 
 matters of little value. 
 
 Tlie 
 
The greateft part of filver now employed in com 
 merce is not obtained from the proper ores of lilver, 
 which are very fcarce; but from lead and even copper 
 ores, which are moreorlefs rich in filver. To give an 
 idea of the manner of treating thefe kinds of ores, from 
 which filver is extracted in the great works, we (hall 
 briefly defcribe here, after Schlutter, the fm si ting of 
 the ore of Rarnelfberg, which contains, as we have 
 already faid, feveral different kinds of mctkls, but 
 particularly lead and filver. 
 
 When this mineral has been difengaged from its 
 fnlphur as much as poffible by three very long read 
 ings, it is melted, in the Lower Hartz in Saxony, in 
 a particular kind of furnace, called a furnace for 
 fmelting upon a holhiu or caj/e. The mafonry of this 
 furnace is compofed of large thick Hates, capable of 
 fuftaming great heat, and cemented together by clay. 
 The interior part of the furnace is three feet and a 
 half long, and two feet broad at the back part, and 
 one foot only in the front. Its height is nine feet 
 eight inches. It has a foundation of mafonry in the 
 ground ; and in this foundation channels are made 
 for the evaporation of the moifture. Thefe channels 
 are covered over with ftones called covering fonts. 
 The hollow or caffe, which is made above thefe, is 
 formed of bricks, upon which are placed, firlr, a bed 
 of clay ; then a bed of fmall ore and fined vitriols ; 
 and, laftly, a bed of charcoal powder be.tt down, 
 called light Irafque. The anterior wall of the furnace 
 is thinner than the others, and is called the cLemife. 
 The back wall, which is pierced to give pailage to the 
 pipes cf two large wooden bellows, is called the middle 
 wall. When the furnace is thus prepared, charcoal 
 is thrown into the hollow, or caiTe ; which being 
 kindled, the fire is to be continued during three hours, 
 before the matters to be fufed are added. Then 
 thefe matters are thrown in, which are not the pure 
 ore, but a mixture of feveral fubftanccs, all of which, 
 
 are 
 
C 463 J 
 
 are fomewhat profitable. The quantity of theie mat 
 ters is furncient ior one day's work ; that is, for a 
 fufion of eighteen hours; and it confi'.ts of, i. Twelve 
 fchorbens or meafures of well roafted Ramelfoerg 
 ore (the fchorben is a meaiure whole contents are 
 two feet five inches long, one foot feven inches broad, 
 and a little, more than a foot deep : it is equal to 32 
 quintals of that country. C( logn weight, at 123 
 p unds er.ch quintal). 2. Six measures of icoria pro 
 duced by the fmelting of the ore of Upper Hartz, 
 which is rcfra&ory, and what workmen call cold. 
 3. Two meafures of knobben, -which is an impure 
 fcoria containing fome lead and filver, which has been 
 formerly thrown away as ufelefs, and is now collected 
 by women and children. Befides thefe other mat 
 ters are added, containing lead and filver, as the tells 
 employed in refining, the drofs of lead, impure litharge, 
 and any rubbifh containing metal, which was left in 
 the furnace after the foregoing fuficn. All thefe 
 matters being mixed together, are thrown into the 
 furnace: and to each meafure of this mixture a mea- 
 fure of charcoal is added. The fufion is then begun 
 by help of bellows ; and as it proceed-, the lead falls 
 through the light brafque or charcoal-bed into the 
 hollow, or caile, where it is prefer ved from burning 
 under the powder of charcoal. The fcoria, on the 
 other hand, being lighter and lefs fluid, is fkimmed 
 off from time to time by means of ladles, that it may 
 not prevent the reft of the lead from falling down in 
 to the hollow. Thus, while the fufion lafts, frefli mat 
 ters and freih charcoal are alternately added, till the 
 whole quantity intended for one fufion, cr as they call 
 it, one dr.y-t be thrown in. 
 
 There are feveral eflential things to be remarked in 
 this operation which is very well contrived. Firft, 
 The mixture of matters from which a little lead and 
 filver is procured, which would otherwife be loft ; and 
 which have a]fo this advantage, that they retard the, 
 
 fufioa 
 
t 464 3 
 
 fufion of the RanicKberg ore, which, however "well 
 roafted it has been, retains always enough of the inl- 
 phur and iron of the pyrites mixed with it, to rercU.r 
 it too fufible or too fluid ; fo that without the addi 
 tion of thofe matters nothing would be obtained but 
 a matt. It is even nccetfary, Hotwithftanding thefe 
 additions, not to hatten the fufion too much, but to 
 give time for the ore to mix \vLh other matters, elfe 
 it would melt and flow of itfelf before the reft. Se 
 condly, The fufion of the ore through charcoal which 
 is practifed in moft fmelting-houfes, and for almoft all 
 ores, is an excellent method, the principal advantage 
 of which is the faving of fuel. The action of the burn 
 ing charcoal dii ecled immediately upon the mineral, 
 at the fame time that it melts it more readily and ern- 
 cacioufly, alfo fupplies it with the phlogiftion necef- 
 faiy to bring it to a perfect (late. 
 
 From the Ramelfberg ore after its fir ft rowing a 
 white vitriol is obtained and prepared at Goilar, whole 
 bafis was zinc : which proves that this ore contains 
 alfo a certain quantity of this femimetal. As this ore 
 is fmelted in a country where the art is well understood 
 of extracting every thing which a mineral contains, fo 
 in this fufion zinc and cadmia are obtained in the fol 
 lowing manner : When the furnace is prepared for the 
 fufion, it is neceflary to clofe it up in the fore-part be 
 fore the fufion is begun. 
 
 " Firft of all, a gritt-ftone is to be placed, fupport- 
 ed at the height of three inches. This (lone is as long 
 as the furnace is broad, and the height of it is level 
 with the hole where the bellows-pipe enters. It is 
 fattened to each fide of the furnace, externally and in 
 ternally with clay. Upon this (lone a kind of re 
 ceptacle, or, as it is called, \htfeat of lie tine, is made 
 in the following manner : A flat flaty ftone is chofen 
 as long as the furnace is broad, and eight inches in 
 breadth. This is placed on the gritt-ftone aboverncn- 
 tioned, in fuch a manner that it inclines conMerably 
 
 r toward* 
 
towards the front of the furnace, and that its bottom 
 touches clofely the gritt ilone. It is fattened with 
 clay, which is alfo laid upon the feat of the zinc. 
 Upon this feat, which is to receive the zinc, two round 
 pieces of charcoal are placed, and alfo a ilone called 
 the Kincjlon ) which is about a foot and an a half in 
 length, and clofes one part of the front of the fur 
 nace. This ttone alfo is fattened on each of its fides 
 with clay. Clay is likewife put under the ftone be 
 twixt the two pieces of charcoal, which hinder it from 
 touching the ieat of the zinc. The m-ider-part of this, 
 itone is but (lightly luted, that the workmen may 
 make an opening for the zinc to flow out. This is 
 made the feat or receptacle of the zinc to detain this 
 metallic fubttance, which would otherwife fall into the 
 hotteft part of the fire, called by the workmen the 
 mating place, and would be there burnt, whereas it is 
 collected upon this receptacle during the fufion, where 
 it is Iheltered from the action of the bellows, and con- 
 iequcntly from too great heat. 
 
 " When all the matter to be fufed in one day is 
 put into the furnace, the blaft of air is continued till 
 that matter has funk down. When it is half way 
 down the furnace, they draw out the fcoria, that more 
 of the ore and other matters may be e \pofed to the 
 greatett heat. As foon as the fcoria is cooled aad 
 fixed a little, two (hovel-fulls of fmall wet fcoria or 
 land is thrown clofe to the furnace, and beat down 
 with the lhovei ; then the workmen open the feat or 
 receptacle of zinc, and ftrike upon the zinc-ftone to 
 make the femimetal flow out As foon as the pure'tt 
 part of it has flowed out, it is fprinkled with water 
 aud carried away. Then the workmen feparate en 
 tirely the zinc-ftone from the wall of the furnace, and 
 they continue to give it little ftrokes, that the fmail 
 particles of zinc difpcrfed among^the charcoal by an iron 
 fall down. This being done, the ftone is removed ; 
 and the zinc is feparated from the charcoal by an iron 
 
 inftruxnent, 
 
inftrument, is cleaned, and remelted along with the 
 zinc that flowed out at fir ft, and is call into round 
 cakes. The reafon why the zinc is withdrawn before 
 the bellows ceafe to blow, is, that if it was left till the 
 charcoal on the feat or receptacle was confirmed, it 
 would be rnoflly burnt, and little would be obtained. 
 Thus after the vine is withdrawn, the fufion is finiihcd 
 by blowing the bellows till the end." 
 
 Thus the zinc is feparated frcm the ore of Ra- 
 melfberg, and is not confounded in the hollow or 
 caiTe with the lead and filver, becaufe, being a volatile 
 femimetal, it cannot fupport the activity of the fire 
 without rifmg into vapours, which are condenfed in 
 the place leail hot, that is to fay, upon the (rones ex- 
 prefsly prepared for that purpofe ; and which, being 
 much thinner than the other walls of the furnace, are 
 continually cooled by the external air. 
 
 It is alfo in this furnace, and after the fufion of 
 the Ramellberg ore, that the cadmia of zinc, or the 
 cadmia of furnaces , is obtained. -This ore is com- 
 pofed of fulphureous and ferruginous pyrites of true 
 lead-ore containing filver, and a very hard and com- 
 pacl matter of a dark brownifh-grey colour, which is 
 probably a lapis calammaris, or an ore of /inc. Thefe 
 feveral matters of the Ramelfberg ore are not fepa 
 rated from each other, either for the roafting or for 
 the fufion. Thus there is zinc in all the parts of the 
 roafted ore ; and much more of it would be obtained^ 
 if it was not fo ealily infl ammable. All the zinc 
 which is obtained is preferved from burning by falling, 
 while in fufion, behind the chcmife or fore-part of the 
 furnace, which is, as has been faid, a kind of fchiftus 
 or (late, called by the workmen feel-fans. But the 
 part of this femimetal which falls in the middle of the 
 furnace, near the middle-wall, or towards the fides, 
 being expofed to the greateft heat of the fire, is there 
 burnt ; and its fmoke or flowers attaching itfelf on all 
 fides to the walls of the furnace, undergo there afemi- 
 
 fufion, 
 
 2 
 
I 4<57 ] 
 
 fuiion, which renders this matter fo hard and fo thick, 
 that it mud be taken away after every fourth fufion, 
 or, at moil, after every fixth fuiion. That which is 
 found attached to the higheit part of the furnace is 
 the bed and pureft. The reft is altered by a mixtare 
 of a portion of lead which it ha? carried up with it ; 
 and which, from its great weight and fixity, h.is hin 
 dered the zinc from riling fo high as it would have 
 done alone. Therefore, with this kind of impure 
 cadmia, ductile biafs cannot be made. 
 
 Almoft all the zinc we have, as well as the cadmia 
 of the furnaces, is obtained from the RameKberg ore 
 by the procefs defcribed, and coniequently is nut the 
 produce of a pure ore of zinc or -lapis ca'amniaris^ 
 which is never fufed for that purpofe. Belore Mr 
 Margraaf, although it "was well known that this ore 
 contained zinc, and that it was employed for the 
 making of brafs, a convenient proc'jfs fur extracting 
 zinc from it was not known ; becaufe, when treated 
 by fuiion with fluxes, like other ores, it does not 
 yield any zinc : which proceeds partly from the re 
 fractory quality of the earth contained in the calamine, 
 that cannot be fufed without a very violent fire ; 
 and alfo from the volatility and comlmfubility of the 
 zinc, which for this reafon cannot be collected at the 
 bottom of a crucible, as a regulus under a fcoria, like 
 moil metals. 
 
 M. Margraaf has remedied thefe inconveniences by 
 di frilling /#&> calam'marh^ mixed with charcoal, in are- 
 tort, to which is joined a receiver containing ibme wa 
 ter, and coniequently in clofe vcilels, where the zinc, 
 by the help of a very ftiong fire indeed, is fublimcd in 
 its metallic form without burning. lie alfo by the fame 
 method reduced into zinc the flowers of z'nc, o>r pom- 
 phol'ix, cadmia of th.' furnace ; tuily> which is alfo a 
 kind of cadmia ; in a word, all matters capable of 
 producing zinc by combination with phlogifton. 
 But it is evident that i\n.h operations as thefe are ra- 
 
 ther 
 
[ 463 ] 
 
 tlier tit to fupply proofs for chemical theory, than to 
 be put in pra&ice for works in great. M. Margraaf 
 kas obferved, that the zinc which he obtained by this 
 procefs was leis brittle than what is obtained from the 
 fufion of ores; which may proceed from its greater pu 
 rity, or from its better combination with phlogillon. 
 
 Zinc is obtained, not only in the method ufed at 
 Collar above defcribed ; but is alfo extracted in great 
 works, from lapis caLmlnarh and calcine,! blend, by a 
 di filiation fimilar to that by which M. Margraaf has 
 elfayed ores of zinc. The firit work of that kind 
 was erected in Sweden by Mr Von Swab, in the year 
 1738. The ore employed was a kind of blend ; this 
 ore, when calcined, powdered, and mixed with char 
 coal, was put into iron or Hone retorts, and the zinc 
 was obtained by diftillation. In Briitol a work is 
 eftabliihed in which zinc is obtained by diftiilation ly 
 *jhrt 
 
 Alter this digreffion which we have now made con 
 cerning the operation in th- great by which zinc and 
 cadmia. are obtained, and which we could not infert 
 olfewhere, becaufe of the neceifary relation it has with 
 the fmelting of the Ivameliberg ore, we proceed to 
 The other operations of the fame ore ; that is to fay, 
 to thtj&WRry, by which the iilver is fcpa rated from the 
 lead, which are mixed together, forming what is called 
 
 This operation differs from tl\Q faing of ejay^ or in 
 i/, principally in this circtim fiance, that in the latter 
 method of lining all the litharge is ab.'orbed into the 
 cupel, whereas in the former method the grcateit part 
 of this litharge is withdrawn. 
 
 The fining in great of the work of Rame!il>erg is 
 performed in a iurnaco called a rev:rle.'atvry furnace. 
 This furnace is fo contlnifted that the ilamc of wood 
 burning in a cavity caUcd tliej^Y-^/,//-, is determined 
 by a current of air (which is introduced through the 
 afb-holc, and wliicli goes (.ait at an opening on one fide 
 
of that part of the furnace where the work is, that is, 
 where the lead and liiverare) to circulate above, and 
 to give the convenient degree of heat, when the fire is 
 properly managed._ In this furnace a great cupel, call- 
 ed a teft, is difpofed. This teft is made of the aihes of 
 beech-wood, well lixivated in the ufual manner. In 
 fame founderies different matters arc added, as fand, 
 fp.rr, calcined gypfum, quicklime, cluy. When thj 
 teft is well prep. ired and dried, all the work is put at 
 once upon the cold telt, to the quantity of 64 quin 
 tals for one operation. Then the fire is lighted in the 
 fire -place with faggots j but the fufion is not urged too 
 faft, i. That the teft may have time to dry; 2.-Y>c- 
 caufe the work of the Ramelfberg ore is allayed by the 
 mixture of feveral metallic matters, which it is proper 
 to feparate from if, otherwife they would fpoil the li 
 tharge and the lead procured from it. Thefe metallic 
 matters are, copper, iron, zinc, and matt. As thsfe 
 heterogeneous fubftances are hard and refractory, they 
 do not melt fo foon as the work, that is, as the lead 
 and filver : and when the work is melted, they fwim 
 upon its furface like a fkin, which is to be taken off. 
 Thefe impurities are called the fcum or the jfirft-nuafc. 
 What remains forms a fecond fcum, which appears 
 when the work is at its greateft degree of heat, but 
 b -fore the litharge begins to form itfelf. It is a fcoria 
 which is to be carefully taken oiF. It is called the 
 fecond ivajle. 
 
 When ths operation is at this point, it is continued 
 by the help of bellows, the wind of which is directed, 
 not upon the wood or fuel, but upon the very furface 
 of the metal, by means of iron-plates put for that pur- 
 pofe before the blaft-hole, which are called papilkm. 
 This blafl does not fo much increafe the intsnfity of 
 the fire, as it facilitates the combuftion of the lead, 
 and throws the litharge that is not imbibed by the tefl > 
 towards a channel, called the litharge-way^ through 
 which it flows. The litharge becomes fixed out of the 
 
 2 furnace :, 
 
L 47 J 
 
 furnace : the matter which is found in the middle of 
 the largeit pieces, and which amounts to about a half 
 or a third of the whole, is friable, and falls into pow 
 der like fand. This is put into barrels containing each 
 five quintals of it ; and is called faleallt litharge, be- 
 t a ule it is fold in that ftate. The other part, which 
 remains folid, is called cold litharge, and is again melted 
 arid reduced into lead, The fuiion is called cold fu- 
 J:oi, and the lead obtained from it cold bad, which is 
 good and fal cable when the work has been well clear 
 ed from the hetercgenous matters mentioned above. 
 The tefts and cupels impregnated with litharge are 
 added in the fufion cf the ore, as we have already re 
 lated. 
 
 When two-thirds, cr nearly that quantity, of the 
 lead are converted! into litharge, no more of it is 
 i'oimed. The filver then appears covered with a white 
 ikin, which the finers call lighlenm^ and the metal 
 i'ght:nc'd or fined Jifaer. 
 
 The iilver obtained by this procefs of fining is not 
 yet altogether pure. It ftill contains feme lead, fre 
 quently to the quantity of four drams in each marc 
 or eight cunces. It is delivered to the workmen, who 
 complete its purification by the ordinary method. 
 This laft operation is the refining-, and the workmen 
 employed to do it are called n-fners. A fining of 64 
 quintals of work, yields from 8 to 10 merks cf fined 
 Iilver, and from 35 to 40 quintals of litharge ; that is 
 from 12 to 1 8 of faleable .litharge, firm 22 to 23 of 
 cold litharge, from 20 to 22 quintals of impregnated 
 teft, and from 6 to 7 quintals of lead-drois. The ope 
 ration lafts from i^ to 18 hours. 
 
 2. Ores containing iilver may be divided into four 
 kinds, i. Pure, or thofe which are rot much com 
 pounded with other metalf. 2. Galenical, in which 
 the filver is mixed with much galena, or ore of lead 
 rr ineralifed by fulphur. 3. Pyritous, in which the 
 fijver is mixed with the martial pyrites. 4. Cupreous, 
 
 In 
 
C 471 1 
 
 in which the filler is contained in copper ores. To- 
 extract the filver from thefe feveral kinds of ores, diffe 
 rent operations are neceffary. 
 
 Native filver is feparated from its adhering earths 
 and f tones, by amalgamation with mercury in the man 
 ner directed for the reparation of gold; or by fufion 
 "with lead, from which it may be afterwards feparated 
 by cupeiiation. 
 
 Pure oresfeldom require a previous calcination ; but 
 when bruiied and cleanfed from extraneous matters,, 
 may be fufed directly, and incorporated with a quan 
 tity of lead ; unlefs they contain a large proportion, 
 of fulphur and arfenic, in which cafe a calcination 
 may be ufeful. The lead employed mud be in a cal 
 cined or vitrified ftate, which being mixed with the 
 ore, and gradually reduced by the phlcgiftion of the 
 charcoal added to it, may be more effectually united , 
 with the fiver of the ore, than if lead itfelf had been 
 added, which would too quickly precipitate to the 
 bottom of the containing velfel or furnace. The fil 
 ver is to be aiterwards feparated from the lead by cu- 
 peJiUtion* 
 
 Galenical ores, especially thofe in which pyrites is 
 intermixed, require a calcination, which ought to be 
 performed in an oven, orreverberatoiy furnace. They 
 are then to be fufed together v/ith feme inflammable 
 matter, as charcoal, by which the lead is revived, and 
 together with the filver is precipitated. 
 
 Pyritous ores muit be firft melted, fo as to form a 
 matt. If the fulphur is not furncient for this kind of 
 fufion, more fulphurated pyrites may be added. This 
 matt contains, befides filver and fulphur, alfo various 
 metals, PS lead, iron, and fomettrnes cobalt. The 
 matt mull be expofed to repeated calcination till ilu- 
 fulphur h diffipated. By thefe calcinations moft of 
 the iron is destroyed. The calcined matt is to be fu 
 fed with litharge, and the filver incorporated with the 
 revived le^d ; with which, and from the ether imper*. 
 Qjq 3, feel: 
 
C 47* ]: 
 
 f<5l metals with which it may be mixed, it mutt after 
 wards be feparated by cupellaticn. 
 
 The filver contained in cupreous ores may be ob 
 tained, either, i. By feparating it from the copper 
 itfelf, after this has been extracted along with the filver 
 in the uiual manner, from the ore; or, 2. By pre 
 cipitating it immediately from the other matters of 
 the ore. 
 
 1. It may be feparated from the copper by two me 
 thods. One of thefe is by adding lead, and fcorifying 
 the imperfect metals. By this method much of the 
 copper \vould be deftroyed, and it is therefore not to 
 be.ufed unleis the quantity of filver relatively to the 
 copper be considerable. Another method by which 
 Jilver may be feparated from copper is by eliquation ;. 
 that is, by mixing the mafs of copper and filver wi<h 
 a quantity of lead, and applying inch a heat as ftiall 
 be juft fufticient to make the lead eliquate from the 
 copper, together with the I'ilver, which being more 
 iirongly dilpofed to unite with the lead than with the 
 copper, is thus incorporated with the former metal, 
 und feparated from the latter. 
 
 2. Silver may alfo be extracted from thefe cupreous 
 ores by precipitation. For this purpofe, let the ore, 
 previouily bruifed and cleanfed, be formed into a matt 
 that the earthy mater may be well feparated. Let 
 the matt be then fufed with a flrongheat ; and when 
 the fcoria has been removed, and the heat is dimi- 
 niilied, add to it feme clean galena, litharge, and 
 granulated lead. When the fire has been railed, and 
 the additions well incorporated with the matt, let fome 
 caft or filed iron be thrown into the liquid rnafs, which 
 being more difpofed than lead is to unite with ful- 
 phur will feparate and precipitate the latter metal, 
 and along with it the filver or gold contained in the 
 matt. This method w r as introduced by Scheffer, and 
 is pracYiied at Adelfors in Smrland. In this work the 
 proportion of the feveral materials is, four quintals.of 
 
 matt* 
 
[ 473 ] 
 
 matt, two quintals of black copper containing ibme 
 lead with the perfect rneta 1 , one quintal of galena, 
 one quintal of lidiarge, a fifth part of a quintal of gra 
 nulated lead, and an equal quantity of caft iron. 
 
 The filver in this, and in all other inftances where it 
 is united with lead, is to be afterwards feparated from 
 the lead by cupellation : which procefs is defcribed 
 at the articles ESSAY of t'm Value of Silver, and RE 
 FINING. 
 
 S E c T . I V. Sine king of Ores of Copper. 
 
 i. THE fmelting in great of copper ores, and even 
 of feveral ores of filver and lead, excepting that of Ra- 
 rnelfberg, is performed in furnaces not eiientially dif 
 ferent from that already defcribed ; but in this refpeft 
 oniy, that the fccria and metal are not drawn out of 
 the furnace, but flow fpontaneouily, as foon as they 
 are melted, into receiving bafons, where the metal is 
 freed from the fcoria. Thefe furnaces are generally 
 called p':erced furnaces. 
 
 Infte ul of a light brafque, or bed cf charcoal pow 
 der, under which the metal lies hid, the bottom of 
 thefe furnaces is covered with a baion compofed of 
 heavy brafque, which is a mixture of charcoal-powder 
 and clay. In the front of the furnace, and at the 
 bottom of the chemife, there is a hole, called the eye, 
 through which the melted matter flows and runs 
 along a trench or furrow, called the trace, into one 
 or more receiving ba'ons made of earth, fcoria, fand, 
 &c. There the metal is feparated from the fcoria, 
 by making it flow from theie bafons into another la 
 teral one. Thefe furnaces alfo are called crooked 
 furnaces. 
 
 Different names are given to them according to feme 
 difference in their conllruclion. For inftance, thole 
 which have two eyes, and two traces, through which 
 the melted matter flows alternately into two bafons,. 
 
 are 
 
C 474 ] 
 
 nre called fpecla de-furnaces. Their greater or lefs 
 height gives occafion alib to the diftinction of high fur 
 naces and middle furnaces. 
 
 The high furnaces are of modern invention. They 
 were firft introduced at Mansfield in the year 1727 ; 
 and the} 7 " are now ufed in almoit all countries where 
 ores are fmelted, as in Saxony, Bohemia, Hungary, 
 ccc. Their chief advantage confilts in fimplirying 
 and diminiihing the labour. This advantage is effec 
 ted by the great height of the furnace, which allows 
 the ore to remain there a long time before it falls down 
 into the hotteft part of the rlie and is melted. Con- 
 fequently, it flitters fucceilively different degrees of 
 heat; and, before it is melted, it undergoes a road- 
 ing which cofts nothing ; therefore the high furnaces 
 are chiefly employed for crude fufions ; and particu 
 larly for the flate copper ore. Thefe furnaces are 
 above 18 feet high. A too great height is attended 
 with an inconvenience, befides the trouble of fuppiy- 
 ing it with ore and fuel, which is, that the charcoal is 
 moilly confumed before it gets down where the greatett 
 ' heat is required, and is then rendered incapable of 
 maintaining a fire fufficiently intenfe. 
 
 All the furnaces which we have mentioned are 
 fnpplied with large bellows, moved by the arbor of 
 a wheel, which is turned round by a current of 
 water. 
 
 The only kind of furnace for fm citing ores where 
 bellows are not employed, is what is called a rever- 
 bratory furnace. The Germans call it a wind fin 
 nace. it is alfo diftinguifhed by the name of Englijb 
 furnace, becaufe the invention of it is attributed to an 
 Englifh phyfician of the name of Wright , who was 
 well verfed in chemiftry ; and becaufe the ufe of it 
 was firft introduced in England about the end of 
 the Lift century, where it is much employed, as well 
 \s in feveral other countries, as at Konigfberg, in 
 Norway, The 
 
L 475 3 
 
 . The length of thefe furnaces is about 18 feet, com- 
 prehending the mafonry : their breadth is i 2 feet, and 
 their height nine feet and a half. The hearth is raifed 
 three fe^t above the level of the found cry ; on one fide 
 is the fire place, under which is an ain-hole hollowed 
 in the earth ; on the ether fide is a bafon made, which 
 i? kept covered with fire when there is occafion : on 
 the anterior fide of this furnace there is a chimney, 
 \vhich receives the flame after -it lias pailed over the 
 mineral that is laid upon the hearth. This hearth, 
 which is in the interior part of the furnace, is made of 
 a clay capable of fuftaining the fire. The advantage 
 of this furnace is, that bellows are not neceflary ; and 
 confequen'ly it may be conftiucled where there is no 
 current of water, and wherever the mine happens to 
 be. This furnace has a hole in its front, through 
 which the fcoria is drawn out ; and a bafon, as we 
 have faid, on one fide, made \\i;h find, in which 
 are oblong traces for the reception of the matt, and 
 of the black copper, when they flow out of the fur 
 nace. 
 
 Copper is generally m'neralifed, not only by ful- 
 pliur and arfenic, but alfo by fjmimetals and nyiitous 
 matters, and is frequently mixed with ether motals. 
 As this metal has great affir.ity with fulphur and ar- 
 fenicj it is a! moil impoffible to difengagc it from them 
 entirely by roafting: hence, in the fmelting in great 
 nothing is obtained by the firil operation but a copper, 
 matt, which contains all the principles of the ore, .ex 
 cepting the earthy and irony parts, particularly when 
 the ore is irnelted crude and unroafted. Afterwards 
 this matt mull be again rcafted and fufed. The pro 
 duce of this fdcond fufion begins Hill more to refemble 
 copper^ but is not malleable. It continues mixed 
 with almoft all the minerals, particularly with the me- 
 tivs. As it is frequently of a black colour, it is always 
 called Hack cc-pper y when it is unmalleable, whatever 
 its cokur happens- really to bs. 
 
 As. 
 
C 476 ] 
 
 As, of all the imperfect metals, copper is mod 
 ficultly burnt and fcorified, it is again remelted fcveral 
 times, in order to burn and fcorify the metallic fab- 
 ftances mixed with it; and this is done till the cop 
 per is perfectly pure, which is then called red or rc- 
 fned copper ) and thefe laft fufions are called ihzfnir.g 
 arid refining of it : red copper contains no metals but 
 gold and filver, if any of thefe happened to be in 
 the ore. 
 
 In order to avoid all thefe fufioi-.s, it has b:en pro- 
 pofed to treat in the humid way certain copper ores, 
 particularly thofe which are very pyritous. This method 
 confifts in making the blue vitriol from the ore, by 
 roafling and lixiviating it, and in precipitating pure 
 copper from this lixivium, which is called cement- 
 wafer, by means of iron : but it is not much prac- 
 t'fed, becaufe it has been obferved, that all the cop 
 per contained in the ore was not procured by this 
 means. 
 
 As expence is not much regarded in fmall eflays 
 and experiments, thefe fufions are much abridged and 
 facilitated by adding at firft faline and glaffy fluxes ; 
 and then by refining the black copper with lead in 
 the cupel, as gold and filver are done. In this me 
 thod of refining, it is to be moft carefully obferved, 
 that the metal be fufed as quickly as podible, and 
 expofed to no more heat than is neceiTary, left it be 
 calcined. 
 
 When the black copper contains forne iron, but not 
 a great deal, the lead prefently feparates the iron from 
 it, and makes it rife to the furface of the copper : but 
 if the iron be in too large a proportion, it prevents the 
 lead from uniting with the copper. Thefe two phe 
 nomena depend on the fame caufe, which is, that 
 lead and iron unite. 
 
 Frequently copper ores contain alfo a quantity of 
 filver fufficient to make its extraction by particular 
 proceifes profitable. It was long before any prc- 
 
 cefs 
 
[ 477 3 
 
 ccis could be thought of for this purpofe which was 
 not too expeniive and troublefome : but at length 
 it is accompiilhed by the excellent operation called 
 e "iquation* 
 
 The copper from which filver has been feparated by 
 eliquatien muft be refined after this operation, as it is 
 generally black copper from which filver is extracted : 
 but even if it had not been black copper which was 
 employed for this operation, it would require to be 
 refilled on account of a little lead it always retains. It 
 is therefore carried to the refiner's furnace, when this 
 operation is performeed by help of bellows, the blall of 
 which is thrown upon the furface of the melted me 
 tal. As in this refining of copper the precife time 
 when it becomes pure cannot be known, b;:caufe fcoria 
 is always formed on its furvace, it js ncceilary to ufe 
 an eif.iy-ircn, the poliihed end of. which .being dipt in 
 melted cof>perlhows that this met.il i> pare when the 
 copper adhei ing to the iron falls oiFas foon as it is dipt 
 ia cold wacer. 
 
 Wlicn this mark of the purity of the copper has 
 been obferved, its furface ought to b2 well cleaned ; 
 and as loon as k begins to lix, it mufi be fprinkkd 
 with a broom or befom dipped in cold water. The fur- 
 face of the copper which is then fixing, being iuddqn- 
 ly cooled by the water, detaches itfelf from the reft of 
 the metal, is taken hold of by tongs, and is thrown 
 red hot into cold water. By again fprinkling water 
 on the m.ifs of copper, it is all of it reduced into plates 
 which are called rcfe&eti and thsfe plates are what is 
 culled rofette-copp:r. 
 
 2. The copper of pyritous cupreous ore cannot be 
 obtained without feverul operations, which vary accord 
 ing to the nature of the ores. Thefe operations are 
 ( hiefly readings and fufions. By the firlt luiion a matt 
 ij produced, which is afterwards to be roalled ; and 
 1'iitis the fu'ioTss 'iiid r>a Rings :re to be alternately ap 
 plied, till by the kill fufion copper is obtained. Thefe 
 
 methods 
 
t 478 j 
 
 methods of treating pyritous copper ores depend 
 on the two following facts: i. Sulphur is more dif- 
 pofed to unite with iron than with copper. 2. The 
 iron of thefe ores is deductible by the burning 
 fulphur during the reading of the fuiion of the ores, 
 while the copper is not injured. This fact appears 
 from experiments mentioned by Scheffer and by 
 Wallerius, and fiom the daily practice of fmelting cu- 
 perous ores. 
 
 From thefe facts we learn, i. That fulphur maybe 
 employed to feparate and deilroy iron mixed with cop 
 per. 2. That iron may be employed to feparate the 
 fulphur from copper, as is fometimes done in the ef- 
 fay of fulphurated copper ores. 3. That by adjuft- 
 ing the proportion of the iron and fulphur to each 
 other in the fm citing of copper-ores, thefe two fub- 
 ftancesmaybe made to deftroy each other, and to pro 
 cure a feparation ot the copper : and this acljuftmcnt 
 may be effected, by adding fulphur or fulphureous py 
 rites to the copper-ore, when the quantity of fulphur 
 contained in this ore relatively to the iron is too 
 fmall ; or by adding iron when the fulphur predo 
 minates ; or by roaiting by which the Superfluous 
 fulphur may be expelled, and no more left than is 
 fufEcient for the deftructi -n of the iron contained in 
 the ore. We mail apply thefe principles to the follow 
 ing cafes. 
 
 i. When the quantity of fulphur and of iron in a 
 copper ore is fmall, and efpecially when the iruii does 
 not too much abound, a previous roafting will at once 
 calcine the iron, and expel moft of the fulphur; fo that 
 by one fufion the calcined iron may be fcoriiied and 
 black copper may be obtained. If the fulphur has not 
 been furliciently expelled, a fecond roafting and fufion 
 aic requiike ; for the whole quantity cf fulphur ought 
 not to be expelled during the firil roafting : but as 
 much ought to be left is as fufEcient for the fcorifica- 
 tion of the calcined iron ; other wife this mij^t, during 
 
C 479 ] 
 
 the fufian, be again revived and united with the cop 
 per. 
 
 2. If, in a copper ore, the quantity of iron be 
 too great, relatively to the fulphur, fome fulphurated 
 pyrites, efpecially that kind which contains copper 
 ought to be added, that a matt may be obtained, and 
 that the iron may be calcined and fcorified. 
 
 3. When the quantity of fulphur and iron is very 
 great, that is, when the ore is very pyritous and poor, 
 it ought to be fir ft formed into a matt ; by which it 
 is feparated from the adherent earths and ftones, 
 and the bulk is diminifhed ; then by repeated and 
 alternate readings and fuiions, the copper may be ob 
 tained. 
 
 4. When the quantity of fulphur in an ore is great 
 er than is fufficient for the forming a matt, the fuper- 
 fluous quantity ought to be previoufly expelled by 
 roafting. 
 
 The copper thus at firft obtained is never pure, but 
 is generally mixed with fulphur or with iron. It is 
 called Hack copper. This may be refined in furnaces, 
 or on hearths. 
 
 In the former methods, to the copper when melted a 
 fmall quantity of lead is added, which unites with the 
 fulphur, and is fcoriiied together with the iron, and 
 floats upon the furface of the melted copper, This pu 
 rification of copper by means of lead is fimilar to the 
 refining of filver by cupellation ; and is founded on the 
 property of lead, by which it is more difpofed to unite 
 with fulphur than copper is ; and on a property of 
 copper, by which it is lefs liable than any other 
 imperfect metal to be, fcorified by lead. But as c p- 
 per is alfo capaple of being fcoriiied by lead, this 
 operation mull be longer continued, a: id r.o jr.oie 
 lead mil ft be employed, than is iufiicient for the fe- 
 paration of the fulphur, and for the iccriricciticn of the 
 iron. 
 
 R r The' 
 
The copper might alfo be purified iro:n rr.v 
 ing fulphur by adding a fufficient quantity of iron to 
 engage the fulphur. Thus Mr ScheiTer found, that by 
 adding to fclplmrated copper from ,' w th to v ' o .th of old 
 caft iron, he rendered the copper pure and ductile. See 
 his Difiertation on the Parting of Metals amongft the 
 SwcdiJJj Memoirs for the year 1752. In this purifi 
 cation, the quantity ef iron added ought not to be too 
 little, elfe all the fulpliur will not be feparated ; 
 and it ought not to be too great, elfe the fuperfluous 
 quantity will unite and injure the purity of the cop 
 per. The fufion and fcorification, with additirn of 
 lead, feems to be the beft method for the lad purifica 
 tion of copper. 
 
 SECT. V. Smelling, &c. of Ores of Iron. 
 
 NOTWITHSTANDING the great importance of this 
 fubject, and the labours of Reaurner, Swedenborgius 
 and of feme authors, we have ft ill a very im 
 perfect knowledge of the caules of the differences of 
 the feveral kinds of ores, of the methods of fmclting 
 beft adapted to thefe differences, of the caufcs cf the 
 good and bad qualities of ditferent kinds of iron, 
 and of th? means of fo meliorating this metal, that 
 we may obtain tough and ductile iron from any of 
 its ores. 
 
 Swedenborgius has very mduflrioufly and exactly 
 defcribed the different proceifes now uied in moft parts 
 of Europe for the fmclting of ores cf iron, for the 
 forging of that metal, and for the convcrfion of it into 
 out we do not find that he or any other anther 
 have, by experiments and difcoveries', contributed 
 much to. the iiluftration or to the improvement cf this 
 part cf metallurgy, unlcfs, perhaps, we except thoi'e 
 of Mr Reaumer, concerning the loftening cfcafl iron 
 by cementation with earthy fubftances. 
 
 The 
 
The ores of iron are known to vsiy much in their 
 appearance, in their contents, in their ck", : ;rees oi iu- 
 iibiiitv, in the methods neceflfary i^rth- e.UTaclion of 
 their contained metal, and in the qualities of the mct.il 
 when extracted. 
 
 Molt ores rcq : : ;:- to be roamed previ.v:f;y to their 
 fufion ; fome m '^y, and < ; . > more 
 
 violent an.', fire; Thoi'j v 
 
 ta'n much Of vitriolic 
 
 long c 
 
 . ; kind ii 
 
 iruttovc, L'oai \ Swodiin iron is laid to be ob 
 
 tained, 
 
 Som? ores require a very flight reading only, 
 that they may be dried and rendered friable. 
 Such are the ores called log ores, and others, which 
 being in a calcined ftate, and containing little ful- 
 phureous matter, would, by a farther calcination, be 
 rendered lels capable of being reduced to a metallic 
 ftate, 
 
 The roafting of ores of iron is performed by kind 
 ling piles, confuting offtrata of fuel an ... placed 
 alternately upon one another, or in furnaces iimiiar to 
 thofe commonly employed for the calcination of limc- 
 ftonei 
 
 Some authors advife the addition of a calcareous 
 earth to fulpluueous ores during the roafting, that the 
 falphur may be abforbsd by this earth wlun con 
 verted r.ito quicklime. But we may obferve that 
 tho quicklime cannot abforb the fulphur or fulphu- 
 reous acid, till thefe be iiric extricated from the ore, 
 and does therefore only prevent the diffipation of 
 thefe volatile matters ; and, fecondly, that the ful 
 phur thus united with the quicklime forms a hepar 
 cf fulphur, which will unite w T ith and diMblve the 
 ore during its fuiion, and prevent the precipitation of 
 the metal. 
 
 " The next operation is \htfujion or fmelting of the 
 ore. This is generally performed in furnaces or 
 
 towers, 
 
lowers, from 20 to 30 feet high in the bottom of 
 which is a bafon for the reception of the fluid metal. 
 Vv 7 hen the furnace is fufficiently heated, which mtift he 
 done at fir ft very gradually, to prevent the crack- 
 ing of the walls ; a quantity of the ore is to he thrown 
 in, from time to time, at the top of the furnace along 
 with a certain quantity of fuel and of lime-dene, or 
 whatever other flux is employed. When the fuel be- 
 iow is ccnfumed by the tire excited by the wind of 
 lle belknvs, the ore, together with its proportionable 
 quantity of fuel and of flux, fink gradually down, till 
 :y are expofed to the greateft heat in the furnace. 
 There the ore and the flux are fufed, the metallic 
 particles are revived by the fuel, are precipitated 
 by means of th-::ir weight through the fcoria formed 
 of the lighter earthy parts of the fiux and of the 
 ITC, and unite in the bafon at the bottom of the 
 furnace, forming a mafs of fluid metal covered 
 by a glal'fy fcoria. When a furricient quantity of 
 liiis fluid metal is collected, which is generally twice 
 cr thrice in 24 hours, an apertuie is made, through 
 Avhich the metal flows into a channel or groove made 
 in a bed of land ; and from thence into fmaller lateral 
 cr connected channels, or other moulds. There it is 
 cooled, becomes folid, and retains the forms of the 
 channels cr moulds into which it flows. The piece 
 of iron fc .imed in the large channel is called a fiw 
 and thofe i'bimed in the fmaller channels are called 
 figs. Sometimes Lhe flu : d iron is taken out of the furnace 
 by means of ladles, and poured into moulds ready pre 
 pared, of fand or of clay, and is thus formed into the 
 various utenfils and inftruments for which caft ircn is a 
 proper material. 
 
 The fcoria mutt be, from tirre to time, allowed to 
 flow cut, when a conilderr.bic quantity of it is formed 
 through an aperture made in the front of the furnace 
 for that purpof j. A fufficient quantity of it mint, 
 however, be always left to cover the furface of thq 
 nielted iron, elfe the ore which would fall upon it, 
 
 before 
 
before the feparation of its metallic from its unmo 
 tallic parts, would leffen the fluidity and injure the 
 purity of the melted metal . This fcoria ought to 
 have a certain degree of fluidity ; for if it be too 
 thick, the revived metallic particles will not be able 
 to -overcome its tenacity, and collect together into 
 drops, nor be precipitated. Accordingly, a fcoria 
 not fufficiently fluid, is always found to contain much 
 metal. If the fcoria be too thin, the metallic par 
 ticles of the ore will be precipitated before they arc 
 fufficiently metallifed, and feparated from the earthy 
 and unmetallic -parts. A due degree of fluidity is 
 given to the fcoria by applying a proper heat and by 
 adding fluxes fuited to the ore. 
 
 Some ores are fufible without addition, and others 
 cannot be fmelted without the addition of fubftances 
 capable of facilitating their fufion. 
 
 The fufible ores are thofe which contain fulphur, 
 arfenic, or are mixed with fome fuuble earth. 
 
 The ores difficultly fujible are thofe which contain 
 no mixture of other fubftance. Such are molt of the 
 ores which contain iron in a Hate nearly metallic. As 
 iron itielf, when purified from all heterogeneous 
 matters, is fcarcely fufib'e without addition, fo the 
 metal contained in thefe purer kinds of ores cannot 
 be eaiily extracted without the addition of fome 
 fufibk iubftance. I. Thofe which are mixed with 
 fome very refractory fubftance. Some of thefe re- 
 fraftory ores contain arfenic ; but us this fubftance 
 facilitates the fuiion of ores, we may prefume that 
 their refractory quality depends upon a mixture of 
 fome unmetallic earth or other infufible fubftance. 
 The earth which is mixed with the common calciform 
 ores is in confiderable quantity ; and is fometimes cal 
 careous, fometimes filiceous, and fometimes argilla 
 ceous. 
 
 Perhaps the fufibility of different ores depends 
 
 greatly oil the degree of calcination to which the 
 
 R r 3 metal 
 
C 484 1 
 
 metal contained in them has been reduced ; fince we 
 have reafon to believe, that by a very perfect calcina 
 tion, fome metals at leaft rruy be reduced to the lia:e 
 cf an eartk alrnoil unfuiible, and incapable of m:talii- 
 fation ; and fince we know, that in every calcination 
 and iubfequent reduction of a given quantity of any 
 imperfect metal, a fenfible part of that quantity is 
 always loil.or cleftroyed, however carefully thefe ope 
 rations may have been performed- That fome of 
 thefe ores are already too much calcined, appears 
 from the inilance abovementioned of the bo^ ores, 
 \vhich are injured by reading ; and even the great 
 height of the common {melting furnaces, although 
 advantageous to many ores that require much roail- 
 ing, is faid to be injurious to thofe which are ;; 
 too much calcined, by expoiing them to a further cal 
 cination, during their very gradual deicent, before 
 they arrive at the hotteit part of the. furnace, where 
 they are fufed. 
 
 But as too violent calcination renders feme ores 
 difficultly fufible, ib too flight calcination of other 
 ores injures the purky of the metal, by leaving much 
 of the fulphureous or other volatile matter, which 
 ought to have been e\ 1 , 
 
 Various fukjiancts are a:'d <.;' '' :frfi,,n of ores 
 
 difficultly fuli'.k* Thefe are, i. Ores of a fuiible qua 
 lity, or which, being mixed with others of a different 
 quality, become fufible : accordingly, in the great 
 works for fmelting ores of iron, two or more cfefterent 
 kinds of ore are commonly mixed, to facilitate the lu- 
 fion, and alfo to meliorate the quality of the iron. Thus 
 an ore yielding an iron which is brittle when, hot, 
 which quality is called rcd-Jkort, and another ore which 
 produces iron brittle when col,!, or told-Jheftt are oi> 
 ten mixed together; not, as fometirnes fuppofed, that 
 thefe qualities are mutually deftruciive of each other, 
 but that of each of them is climiniihcd in the mixed 
 xnafs of iron, as much as this mafs is larger than the 
 
 part 
 
C 485 ] 
 
 part of the mafs originally pouefTed of that quality. 
 Thus, if from two ftich ores the mafs of iron obtained 
 confiils of equal parts of coki-iliurt, and of red {hort 
 iron, it will have both th --.it will be only 
 
 half as cold Jksrt <\s iron obtained illely from one of die 
 ere-:., and half as red-jlort as iron obtained only from 
 the <uher ore. i.Latils andjic es are all 6 generally 
 ad Jed to facilitate the fufion of iron ores. Thefe are 
 fuch as are fuilble, or become fuiible \\iien mixed with 
 the ore, or with the earth adhering to it. Authors 
 direcl: that, if th's earth be of an argillaceous nature, 
 limeftone or fome calcareous earth fhould be added ; 
 and that, if the adherent earth be calcareous, an ar 
 gillaceous or filiceous earth fnould be added ; becaufe 
 thefe two earths, though fingly unfulible, yet, when 
 mixed, mutually promote the fulion of each other; 
 but as limeftone is almoft always added in the fmelting 
 of iron ores, and as in fome of thefe, at IcaiVno ar - 
 gillaceous earth appears to be contained, we are in 
 clined to believe that it u ,es the fu- 
 iion, not merely by ui/V- oarths, but 
 by uniting with that part c which is mofl 
 perfectly calcined, and leuft di/po ed to metallifation ; 
 iince we kr.ow, that by mixing a calciibrm or roailed 
 ere of iron with calcareous earth, without any inflam 
 mable m;;t;;er, theie two ; may be totally vi- 
 triried. See Expfnmmtt ;. ,::kllme and upon 
 iron, by Mr Brandt, in the Sive ijb Mcw/trs for the years 
 1749 and 1751. Calcareous earth does indeed fo 
 powerfully facilitate the fufion of iron ores, that it 
 defervcs to be conlidered whether workmen do not 
 generally ufe too great a quantity of it, in order to 
 haften the operation. For when the fcoria is render 
 ed too thin, much earthy or unmetallized matter is 
 precipitated, and the call iron produced is of too vi 
 treous a quality, and net fufficiently approximated to 
 its true metallic date 
 
 Some 
 
Some authors pretend, that a principal ufe of ths 
 addition of limeftone in the fmelting of iron ores is to 
 abfc rb the fulphur, or vi trie-lie acid, of thefe ores : 
 but, as we have already obferved, a hepar of fulphur 
 is formed by that mixture of calcareous earth and ful 
 phur, which is capable of diiTolving iron in a metallic 
 ftate ; and thus the quantity cf metal obtained from 
 an ore not fufficiently diverted of its fulphur, or vi 
 triolic acid, (which, by uniting with the fuel, is 
 formed into a fulphur during the fmelting), muft be 
 considerably diminiihed, though rendered purer, by 
 addition of calcareous earth : hence the utility ap 
 pears of previoufly expelling the fulphur and vi 
 triolic acid from the ore by a fuiricient roalVing. 
 3. Tliefcoria of former {meltings is frequently added 
 to affift. the fufion of die ore ; and, when the fcoria 
 contains much iron, as fometimes happens in ill-con 
 ducted operations, it alfo increafes the quantity of 
 metal obtained. 
 
 The quantity of thefe fufible matters to be added 
 varies according to the nature of the ore ; but ought 
 in general to be fuch, that the fcoria fhall have its re- 
 quifite degree of thinneis,as is mentioned above. 
 
 The fuel ufed in mod parts of Europe for the 
 fmelting of ores of iron is charcoal. Lately, in feveial 
 works in England and Scotland, iron ore has been 
 frnelted by means of pit-coal, previoufly reduced to 
 cinders or coaks, by a kind of calcination fimilar to 
 the operation for converting wood into charcoal, by 
 which the aqueous* and fulphurens parts of the coal 
 are expelled, while only the more fixed bituminous parts 
 are left behind. In France, pit coal not calcined has 
 been tried for this purpofe, but unfuccefsfully. The 
 life of peat has alfo been introduced in fome parts of 
 England. 
 
 The quality of the iron depends confiderably upon 
 the quality and alfo upon the quantity of the fuel 
 
 employed. 
 
E 4*7 J 
 
 employed. Charcoal is fitter than coaks for produ 
 cing an iron capable of being rendered malleable by 
 forging- 
 
 The quantity of fuel, or the intenfity of the heat, 
 iriuft be fuited to the greater or lefs fufibility of the 
 ore. Sulphureous, and other ores eafily fufible, re 
 quire lefs fuel than ores difficultly fufible. In general, 
 if the quantity of fu?l h too fwaJt t and the heat not 
 fufficiently intenfe, all the iron will not be reduced, 
 and much. of it will remain in the fcoria, which will 
 not be fufficiently thin. This defect of fuel may be 
 known by the blackncfs and compaclnefs of the fco 
 ria ; by the qualities of the iron obtained, which in 
 this cafe is hard, white, light, intermixed with fcoria, 
 fmcoth in its texture, without fcales or grains, rough 
 and convex in its furface, and liable to great loljj of 
 weight by being forged ; and, laftly, it may be known 
 by obferving the colour and appearance of the drops 
 of metal falling down from the fmeltecl ore, and of 
 the fccria upon the furnace of the fluid metal, both 
 which are darker coloured than when more fuel is 
 ufed. When the quaniityoftbefuelisfiifficltntlylargffi 
 and the heat is intenfe enough, the iron is darker co 
 loured, derfer, more tenacious, contains lefs fccria, 
 and is therefore hfs fufible, and lofes lei's of its weight 
 by beirg forged. Its furface is alfo fmocther and 
 fomewh;t concave; and its texture is generally gra- 
 nulr:ttd. The fcj-ria, in this cafe, is cf a lighter co 
 lour, and lefs denfe. The drops falling down from- 
 the iihelted ore and the liquid fr.oria in the furnace 
 nppcur hotter and of a brighter colour. When the 
 quantity ( f fuel is too great, and the heat too intenfe, 
 the iron will appear to have a {till darker colour, and 
 more ccnfpicuous grains or plates, and the fcoria will 
 be lighter, whiter, and more fpongy. The drops*' 
 tailing from this fmelted ore, and the fluid fcoria will 
 appear to a perfon looking into the furnace through 
 
 the 
 
E 
 
 the blafl-hc-le to be very white and filming hot. The 
 quantity of charcoal necellUry to produce five hun 
 dred weight of iron, when the ore is rich, the furnace 
 well contrived, and the operation ikilf Lilly condud-jd, 
 is computed f o be about 40 cubic feet ; but is much 
 more in contrary circumftances. 
 
 The time during which tie Jla'ul rustnl ought to Ic 
 kept in j'ufon before it is allowed to nV>w out of the 
 furnace, mull alfo be ;. to* H;.'W long that 
 
 time is, and \vho-Jicr it t t > vary according 
 
 to the qu. other circumftances, we 
 
 cannot determine, in ; ,he metal is al 
 
 lowed to flow out of the furnacj every fix or c 
 'ind i ry 10 or 12 hours. Some 
 
 works i hut a considerable time is nccef- 
 
 fary.for the concoction of the mural. This is cer 
 tain, that the iron undergoes feme change by being 
 I:ept in a fluid (late; and that if its full on be pro 
 longed much beyond the ufual time, it is rendered 
 lefs fluid, and alfo its cohefion, when it becomes cold, 
 is thereby greatly dinnniilu-d. The marquis de Cour- 
 tivron fays, that the ,1 may be reiiored to iron 
 
 in this ftate by adding to it forrie vitreicible eartli, 
 which he confiders as one of the conilituent parts of 
 iion, and which he thinks is deftroyed by the fufion 
 too long continued. That the fuftbility of caft-irou 
 does depend on an admixture of ionic vitrefcibleeanh, 
 appears probable from the great quantity of fcoria 
 forced out of iron during its convention into malleable 
 or forged iron, and from the lofs of fufi'oility which it 
 fuffers nearly in proportion to its lofs of fcoria. The , 
 quantity ofirrn daily obtained from fuch a furnace us 
 is above defcribed, is from two to live tons in 24 hours, 
 according to the richnefs and fuiibility of the ore, to 
 the construction of the furnace, to the adjuftnr. 
 the due quantity of flu:: and of fuel, and to the (kill 
 emplovsd in conducting the operation. 
 
 The 
 
'ron is judged of by obferving the 
 ; its flowing from the furnace, and 
 v.-he.i it is fixed and cold. If the fluid iron, while it 
 flows, emits many and large fparkles ; if rnany brown 
 fpots appear on it while it is yet red hot; if, when it 
 is fixed and cold, its corners and edges are thick and 
 rough, and its iurface is fpotted ; it is known to have 
 a red-ihort quality. If, in flowing, the iron feems 
 covered with a thin glaify craft, and if, when cold, 
 its texture be whitifh, it is believed to be cold-fhort. 
 Mr Reaumer fays, that dark-coloured caft iron is 
 more impure than that which is white. The marquis 
 de Courtivron is of a contrary opinion. But no cer 
 tain rules for judging of the quality of iron before it 
 be Forged can be given. From brittle call iron, fome- 
 times ductile f rged iron is produced. Cad-iron with 
 brilH.mt plates and points, when forged, becomes 
 fomctimes red-fliort and Ibmetimes cold-lhort. Large 
 ;; plates, large cavities called ejes, want of fuf- 
 jficient clenfity, are aimed certain marks of bad iron; 
 . hcth:r it will be -cold or red fhort cannot be 
 be forged. Whitenefs of colour, brit- 
 leis cf texture, and hardnefs, are given 
 any cart iron by fiidden cooling; and we 
 may obferve, that in general the whiter the metal is, 
 the harder it is alio, whether th^fe properties proceed 
 from the r or,, or from fudden cooling; 
 
 and that, ; dai'ker-coloured iron is fitter 
 
 for being caft inM i^ouljs. bccau.e it is capable in 
 ic-iTse me.iRire of bciii:^ L 
 
 after it has been expofed during 1 
 red-heatii] 
 cooled. This oper 
 
 nettling, chcMicvcs the. ti . ; 
 
 fofter and more capable of being- filed than 1 
 and al/b cofflfide^ably left bnttle.. 
 
 Mr Reu by cementing caft iron 
 
 with i i a red-heat, the metal may 
 
 2 be 
 
r 490 ] 
 
 be rendered fofter, tougher, and confequently a. fit 
 material for many utenfils formerly made of forged 
 iron. Whether cementation with abforbent earths 
 gives to caft iron a greater degree of thefe properties 
 than the annealing commonly practifed, has not been 
 yet determined. 
 
 In Navarre, and in fome of the foothern parts of 
 France, iron-ore is fmelted in furnaces much fmaller, 
 and of a very different conftrucHon from thofe above 
 defcribed. A furnace of this kind confids of a wide- 
 mouthed copper-caldron, the inner furface of which 
 is lined with mafonry a foot thick. The mouth of 
 this caldron is nearly of an oval or elliptic form. The 
 fpace or cavity contained by the mafonry is the furnace 
 in which the ore is fmelted. The depth of this cavity- 
 is equal to two feet and a half: the larger diameter 
 of the oval mouth of the cavity is about eight feet, 
 and its fmaller diameter is about fix feet: the fpace 
 of the furnace is gradually contracled towards the 
 bottom, the greateft diameter of which does not ex 
 ceed fix feet : eighteen inches above the bottom is a 
 cylindrical channel in cne of the longer fides of the 
 caldron and mafcnry, through which the nozzle of 
 the bellows paries. This channel, and alfo the bel 
 lows pipe, are fo inclined, that the wind is directed 
 towards the lowed point of the oppoiite fide of the 
 furnace. Another cylindrical channel is in one of the 
 fnorter fides of the furnace, at the height of a few 
 inches from the bottom, which is generally kept 
 clofed, and is opened cccafionally to give pailage to 
 the fcoria : and above this is a third channel in the 
 tme fide of the furnace, through which an iron in- 
 itrument is occafionally introduced to ftir the fluid 
 metal, and to affift, as is faid, the reparation of the 
 Scoria from it. The greateft height of this channel is 
 at its external aperture en the outfide of the furnace, 
 and its fmaller height is at its internal aperture ; fo 
 that the inflrument may be directed towards the bou 
 
 torn 
 
C 49* ] 
 
 torn of the furnace; but the feccncl channel belotr it 
 has a contrary inclin:*iion, that, when an opening is 
 made, the fcoria may flow out of the furnace into a 
 baibn placed for its reception. When the furnace is 
 heated fufficiently, the workmen begin to threw into 
 it alternate changes of charcoal and of ore previously 
 roafted. They lake care to throw the charcoal chiefly 
 on that fide at which the wind enters, and tlv; ore at 
 the oppofite fide. At the end of about four hours, a 
 inafs of iron is collected at the bottom of the furnace, 
 which is generally about 600 weight; the bellows are 
 then ftopt ; and when the mafs of iron is become folid, 
 the workmen raife it from the bottom of the furnace, 
 and place it, while y.-t foft, under a large hammer, 
 where it is forged. The iron produced in thefe fur- 
 nances is of the bed quality ; the quantity is alfovery 
 considerable, in proportion to the quantity of ore, and 
 to the quantity of fuel employed. In thefe furnaces 
 no limeftone or other lubftance is ufed to facilitate the 
 fufion of the ore. We iliould receive much inflriicliori 
 concerning the fmelting *of iron-ore, if we knew up 
 on what part of the procels, or circumstance, the ex 
 cellence of the iron obtained in thefe furnaces depends ; 
 v/hethcr on the quality of the ore ; on the difufe of 
 any kind of flux, by which the proportion of vitreous 
 or earthy matter, intermixed with the metallic par 
 ticles, is diminished ; on the forging while the iron is 
 yet foft and hot, as the Marquis de Ccurtivron thinks ; 
 or on fome other caufe, not obferved. 
 
 The iron th'u> produced by fmelting ores is very far 
 from being a pure rnetal ; and though its fuiibility 
 renders it very ufeful for the formation r.f cannon, 
 pots, and a great variety of utenlils, yet i ; want; the 
 itrength, toughnefs, and malleability, which it is ca 
 pable of receiving by further operations. 
 
 Call- iron fcems to contain a large quantity ofvitre- 
 earthy matter mixed with the pure iron ; which 
 is probably the chief caufe oi its fufibiiity, 
 S f brittlenefsj 
 
 
C 49* ] 
 
 brittlenefs, hardnefs, and other properties by which it 
 differs from forged iron. The fulphur, arfenic, and 
 other impurities of the ore, which are fometimes 
 contained in caft-iron, are probably only accidental, 
 and may be the caufes of the red-fhort quality, raid of 
 other properties of certain kinds of iroa : but the 
 earthy matter abovementioned fcems principally to 
 diftinguiih cafl iron from forged or malleable iron ; 
 for, firft, by depriving the former of this earthy mat 
 ter, it is rendered malleable, as in the common pro- 
 cefs hereafter to be defcribed ; And, fecondly, by fu- 
 fmg malleabk iron with earthy and vitrefcible matters, 
 it lofes its malleability, and is reilored to the ftate and 
 properties of caft-iron. 
 
 The earthy vitreous matter contained in caft iron 
 confifts probably 'of fomc of the ferruginous earth or 
 calx of the ore not fufficiently metaliifed, and alfo of 
 fome immetallic earth. Perhaps it is only a part of 
 the fcoria which adheres to, and is precipitated with, 
 the metallic particles, from which it is more and more 
 feparated, as the heat applied is more intenfe, and as 
 the fution is longer continued. 
 
 To fep^arate thefe impurities from cad-iron, and to 
 unite the metallic parrs more clofely and compactly, 
 and thus to give it the ductility and tenacity which 
 render this metal more ufcful thin any other, are the 
 effects produced by the following operations. 
 
 The fir it of thefe operations is a fution of the iron, 
 by which much of its impurities is ieparated in form 
 of fcoria ; and by the fecond operation, a further and 
 more complete feparation of thefe impurities, and alfo 
 a. clofcr compaction of the metallic particles, are ef 
 fected by the application of mechanical force or pref- 
 lure, by means of large hammers. 
 
 Some differences in ihe construction of the frrge or 
 furnace, in which the fujinn or refin':n^ ofcaf.-'non'v'. 
 performed, in the method of conducting the opera 
 tion, and in oilier circumftancesj are obferved to oc 
 cur 
 
C 493 J 
 
 ciir in different places. We iliall Jefcribe from Swc^ 
 denborgius the German me thud. 
 
 The fatten of the. c ail: -iron, which is to be render 
 ed malleable, is perfornie d upon tlu hearth of a forge 
 iimilar to that ufed by blackfmiths : at one fide of 
 this hearth is formed a cavity or fire-place, which is 
 intended to contain the fuel and the iron to be melt 
 ed : this fire-place .is 20 inches long, 18 inches broad, 
 and 12 or 14 inches deep: it ia bounded on three fides 
 by three plates of caft-iron placed upright ; and cr. tlr; 
 fourth fide, which is the front, or that part nearelh 
 to which the workmen (land, by a large forge-ham 
 mer, through the eye of which the fcoria is at certain 
 times allowed to flow. The floor alfo of the fire-placs 
 is another caft iron plate. The thicknefs of thefe 
 plates is from two to four inches. One of the upright 
 fide-plates refts againft a wall, in. an aperUire through 
 which a copper-tube, called the tuyere, is luted with 
 clay. This tube is a kind of cafe or covering for the 
 pipe of a pair of bellows placed behind the wall, and 
 its direction is therefore parallel to that of the bel 
 lows-pipe ; but it advances about half a foot further 
 than this pipe into the fire-place ; and thus gives great 
 er force to. the air, which it keeps concentrated, or 
 prevents the divergency of the air till it is required to 
 act. The tube refts upon the edge of the fide -plate 
 which leans againft the wall, nearer to the back-part 
 than to. the front of the fireplace; and i^i fuch an 
 oblique direction, that the wind mall be impelled to 
 wards the fur the ft part of the floor of the fire-place, 
 or where this floor is interfered by the oppofite fide- 
 plate. The obliquity of the tuyere ought to vary ac 
 cording to the quality of the iron ; and therefore, in 
 every operation, it may be fnifted till its proper pcfl- 
 tion is found. The more nearly its direction ap 
 proaches to a hori/ontal plane, the more intenfe is the 
 heat; but a larger quantity of fuel is confumed than 
 is even proportional to the increafe of heat, becaufe 
 S f 2 tllQ 
 
L 494 J 
 
 llie runnels not tile nib well confined. When the rrcfc 
 Is eafily fumble, great heat .is not required : the tuyere 
 rr:,iy then decline considerably from the horizontal 
 plane, and thus fuel may be faved. This tuyere, tho' 
 made of copper, a metal more eafily fufible than iron, 
 is preferved frcm fufion by the ccriftant paffage of cold, 
 air through it. It muft be carefully kept open, and 
 clcanfed from the fcoria, which would be apt to block 
 up its cavity, 'by which not only the heat would be; 
 too much diniiniihcd for the fuccefs of the operation, 
 but the tube itfclf would be melted, 
 
 To prepare for the fufion, a quantity of fcoria of a 
 former operation is thrown into the fire-place, till one 
 third-part of this be full ; and the remaining two 
 thirds of the fire-place are to be filled with fmaller 
 fcoT la, coal-duil, and fparks ejected from hot iron. 
 Thefe matters, being fufible, form a bath for the re 
 ception of the iron when melted. Upon this bed of, 
 iccriu, the mafs of carl iron to be melted is placed ; 
 lo that one end of it fhali be within the fire-place , cp- 
 pofite to the tuyere, and -at the durance of about four 
 or five mclies from its aperture; and the other end 
 fuall flancl without the fire-place, to be pufhed in, as 
 the former is melted. The iijr.per fide of the mafs of 
 iron ou.|;ht to be in the fame horizontal plane as the 
 upper p-rt of the orifice of the tuyere, that the wind 
 may, by means of the obliquity of its courfj, (Irike 
 upon and pafs along tlie under-fide of the mafs ; but if 
 the Iron be difhcultly fufible, the tuyere is to be dif, 
 pofed more horizontally, fo that the wind iliall ilrike 
 iiirecily upon the mafs of iron ; and that one part of 
 the blaft ihall graze along the upper furface, and the 
 olher part along the under furface of the iron. The 
 riiiifs of iron \vcighs generar.y from 200 to 400 
 pounds. Sometimes two or three fmaller mafTcs a>e 
 put one above another, fo as not to touch. When 
 thefe are of different qualities, the coid-fhoi t piece is 
 placed undcrmoflj that being more unfuiiblc than the 
 
 red 
 
L 4V5 J 
 
 red-iliort. The iron being placed, charcoal-powder :* 
 thrown on both fides, and coals are accumulated a- 
 bove, fo as to cover entirely the iron. 
 
 The coals are then to be kindled, and the bellows- 
 are made to blow, at fir (I ilowly, and afterwards with 
 more and more force. The iron is gradually liquefied, 
 and flows down in drops through the malted fcoria to 
 the bottom of the fire-place ; during which the work 
 men frequently turn the iron, fo that the en 1 oppofed 
 to the blaft of wind may be equally expofed to heat, 
 and uniformly fufed. While the coals are confumed, 
 more are thrown on, fo that the whole may be kept 
 quite covered. During the operation, a workman 
 frequently founds the bottoms and corners of the fire 
 place by means of a bar or p:>ker, raifes up any mi's 
 of metal which he finds adhering to thefe, and expofes. 
 them to the greateil heat, that they m.iy be more per- 
 fetfly fufed. 
 
 When all the iron is fufcd, no more coa's are to be' 
 added ; but the melted m.ifs is to remain half unco 
 vered for fome time ; during which the iron boils and 
 bubbles and its ftirfice fw. 11s and rites higher and 
 higher. When the iron has rifen as high as the up 
 per edge of the fire-place, the coals upoa its farface 
 mull be removed ; and by thiisexpoiing it to cold air, 
 its ebullidoa and fwelling iubfiJe. In this ftate, or 
 cocti n, the iron is kept during half an hour or more, 
 by adding occasionally pieces of good coal, which 
 maintain a fufficient heat, without covering entirely 
 the furface of the mafs. During this codion, the 
 workmen allow the oriiice of the tuyere to be ha f 
 flopped up by th- fcoria, th :t the air may not blow 
 upon the iron with all ic- force by which it would be 
 too much coded. Accordingly, when they thhktha*: 
 the coclion has continued fuflicic;i.ly long, th . cl.ar 
 the paflage of the tuyere, and the mils is fo , 4 
 
 by the cold air. At the fame time aifo they p 
 pa/Tige in the eye of the hammer placed in the fr< 
 
C 
 
 of the fire-place, through which forne of the fcoria i.i 
 allowed to flow out. When the iron has become 
 iblid, the bellows are ftcpt, the coals are removed, and 
 the mafs is left during an hour ; and then the work 
 men raife it from the fire-place, turn it upfide down, 
 and proceed to the fecond ccction or fufioa of the 
 iron. 
 
 From this fecond operation, the mafs is to be fo 
 placed, that one part of it (hall red upon the tuyere, 
 and the other upon the fcoria remaining in the fire- 
 place. This fccria is to be dijpofed in an oblique di 
 rection parallel to the tuyere, by which means the 
 vhid of the bellows is obliged to pafs alung the under 
 fide of the mafs of iron. About the fides of the mafs, 
 charcoal-powder and burnt allies are thrown ; but to 
 wards the tuyere, dry and entire pieces of coals are 
 placed, to maintain the fire. When thefe are kindled, 
 more coals are added, and the lire is gradually excited. 
 The workmen at'. end to the direction of the flame, 
 .that it pafs equally along the under furface of the iron, 
 quite to the further extremity, .and that it do not 
 efcape at the ildes, nor be reverberated buck towards 
 the tuyere, by which this copper tube might be melt 
 ed. During this fuiion, pieces of iron are apt to be 
 feparatecl from the mafs, and to fall down unfufed to 
 the bottom and corners of the fire-place. Thefe are 
 carefully to be fearched for, and expofed to the great- 
 eft heat till they are melted. When the whole mafs 
 is thus brought into perfect fuiion, the coals are re 
 moved ; and the wind blowing en its furface, whirls 
 and diffipates the fmall remaining pieces of fcoria and 
 fpurks thrown cut from the fluid iron. This jet of fire 
 continues about leven or eight minutes, and the whole 
 operation about two hours. In this fecoed fufion the 
 fcoria is to be thrice removed, by opening a paifage 
 through the eye of the hammer. The firft time of re 
 moving the fcoria is about 20 minutes from the kind 
 ling of the fire* the fecond time is about 40 minutes 
 
 after 
 
C 497 3 
 
 after the firft, ai>d the third time is near the end of 
 the operation. 
 
 The mafs is then removed from the hearth, and put 
 upon the ground of the forge, where it is Gleamed 
 from fcoria, and beat into a mure uniform lhape. It 
 is then placed on an anvil, where, by being forged, it' 
 receives a form nearly cubical. This mais is to be di 
 vided into five, fix, or more pieces, by means of a 
 wedge ; and thefe are to be heated and forged till 
 they are reduced to the form of the bars com 
 monly fold. 
 
 In fome forges, the iron is fufed only once, and in 
 others it fuffers three fufkms, by which it is faid to be 
 rendered very pure. Where only one fufion is prac- 
 tifed, it is called the French method. In this, no great 
 er quantity of iron is filled at once than is iufficient 
 to make one bar. The fire-pla:e is of coniideraby lefs 
 di mentions, and efpecially is lefs deep, than in the Ger 
 man method above defer ibed. The fire is alio m-.re 
 intenfe, and the pioportion of fu.-l confumed to the 
 iron is greater. The iron, when melted, is not kept 
 in a ftate of ebullition as is above defcr;bed ; but this 
 ebullition is prevented by itirrii t the fluid mafs with 
 an iron bar, till it is coagulated, and becomes folid. 
 
 By th^fe operations, fuflon and forging, the iron 
 lojes about 7 ? T parts of its former weight, fometimes 
 more aiid fometimes lefs, according to the quality of 
 the call-iron employed ; it is purified from the vitreous 
 and earthy parts which were intermixed with it, its 
 metallic particles are more clofcly compacted, its tex 
 ture is changed, and it is rendered more denie, foft, 
 and malleable, tough, and dill-cultly fufible. 
 
 The degrees, however, of thefe qualities vary much 
 in different kinds of iron. Thus fome iron is tough 
 and malleable, both when it is hot and when it is cold. 
 This is the belt and moil uieful iron. It m;iy be 
 known generally by the equable furface of the forged 
 bar, which is free from tranfverfe Mures or cracks in 
 
 the 
 
[ 498 ] 
 
 the edges, and by clear, white, fm all-grained, or 
 rather fibrous texture. Another kind is tough when 
 it U heated, but brittle when it is cold. This is called 
 cold-Jbort irr.n: and is generally known by a texture 
 confiding of large, fhining plates, without any librcs. 
 It is leis ILible to ruft than other iron. A third kind 
 of iron, called red JJjort, is brittle when hot, and mal 
 leable when cold. On the furface and edges of the bars 
 of this kind of iron, tranfverle cracks or fiflures may 
 be feen ; and its internal colour is dull and dark. It is 
 very liable to ruft. Laftly, fome iron is brittle both 
 when hot and when cold. 
 
 Moil authors agree, that the red-fliort quality of 
 iron proceeds from fome iulphur or vitriolic acid be- 
 tjig contained in it, becaufe fulphur is known to pro 
 duce this effe<5t when added to iron, and becauTe the 
 iron obtained from pyritous and other fulphur ate d ores 
 has generally this quality. 
 
 The caufe of the cold-fliort quality of iron is not fo 
 well ascertained. Some imagine, that it proceeds 
 from a mixture of arfenic or ol antimony. But this 
 opinion feems to be improbable, when we confider that 
 thefe metallic fubftanj es may in a great meafure be dif- 
 iipated by roafting, whereas the ores which yield a 
 cold-fhort iron are injured by much roafting ; that no 
 arfenic or antimony are obfervable in moft, if in any, 
 of thefe ores ; and laftly, that thefe femimetals would 
 render the iron brittle both when hot and when cold. 
 Cramer and other authors impute this vicious qua'ity 
 to a mixture of unmetallic earth or vitreous matter ; - 
 and affirm, that it may be deftroyed by cementuion 
 with phlogifton, and by f.;rging. And laiily, others 
 afcribe the cold-fhort quality of iron to a defcA of 
 phlo'gifton, or, as Swedenborgius fays, of fulphur. To 
 sifcertain the caufes of the bad qualities of iron, and 
 to difcover practical remedies, are ftill defiderata ia 
 metallurgy. 
 
L 499 ] 
 
 In one bar frequently two or more different kinds of 
 iron may be oblerved, which run all along its whole 
 length ; and fcarcely a bar is ever found of entirely 
 pure and homogeneous iron. This difference pro 
 bably proceeds from the practice we have mentioned 
 of mixing different kinds of ores together, in the fmelt- 
 ing ; -and allb from the practice of mixing two or 
 more pigs, of cafe iron of different qualities in the finery 
 of.thafcj by which means, the red-fliort and cold-iliort 
 qualities of the different kinds are not, as we have al 
 ready remarked, mutually counteracted or ddlroyed 
 by each other, but each of thefe qualities is diminifh- 
 ed in the mixed mafs of iron, as much as tins mafs is 
 larger than the part of the mafs originally poiferTed of 
 that quality : that is, if equal parts of red fhort and 
 of cold-lhot iron be mixed together, .the mixed mafs 
 will be only half as red-fhort us the former part, and 
 half as cold short as the latter. For thefe different 
 kinds of iron feemf as if they were only capable of be 
 ing interwoven and dilfuil'd through each other, but 
 not of being intimately united or combined. 
 
 The quality of forged iron may be known by the 
 texture which appears on breaking- a bar. The beft 
 and tougheft iron is that which has the moft fibrous 
 texture, and is of a clear greyifh colour. This fi 
 brous appearance is given by the refinance which ihs 
 particles of the iron make to their rupture. Ths 
 next be PC iron is that whoie texture con fids of clear, 
 v.-hitifli, fmall grains, inUrrrf xed with fibres. Thefe 
 two kinds are malleable, both when hot and when 
 cold, and h ivi: great tc'iajky. Ciil-fiort irjn is 
 known by a texture confiding of large, Ihining plates, 
 without fibres: and red-fan, iron is diiliiiguiflied by 
 its dark dull colour, and ,b./ the tranfverfe cracks .and 
 iiffures on the furface and edges of the bars. The. 
 quality of iron may ba mu.:ii improved by violent 
 comprefFion, as by forging and rolling ; efpecially 
 when it is not long e;:pofed to tco violent heat, which 
 
 is 
 
C 500 3 
 
 is known to injure, and at length to deftroy, its metal 
 lic properties. 
 
 For the converfion of iron mto Jiee/ 9 fee the article 
 STEEL. 
 
 SECT, VI. Of the Smelting of Tin Ores. 
 
 THE tin-ores commonly fmelted are thofe which 
 confift of calx of tin combined with calx of arfenic 
 and fometimes with calx of iron. Thefe are cither pure, 
 as the tin-grains, or intermixed with fpars, (tones, py 
 rites, ores of copper, iron, or of other metals. 
 
 The impure ores muft be cleanfed as much as is 
 poffible from all heterogeneous matters. This clean- 
 fmg is more neceflVy in ores of tin than of any other 
 metal ; becaufe in the fmelting of tin-ores a lefs intenfe 
 heat muft be given than is fufficien" for the fcoriiica- 
 tion of earthy matters, left the tin be calcined. Tin- 
 ores previoufly bruiied may be cleanfed by wafhing, 
 fpr which operation their great weight and hardnefs 
 render them well adapted. If they be intermixed 
 with very hard ilones or ferruginous ores, a ilight roail- 
 ing will- render thefe impure matters more friable, 
 and confequently filter to be feparated from the tin- 
 ores. Som times thefe operations, the roalting, CKH.U- 
 fion, and lotion, mull be repeated. By roaiting, the 
 ferruginous particles are fo far revived, that they may 
 be feparated by magnets. 
 
 The ore, thus cle mfed from adhering heterogene 
 ous matters, is to be roaftcd in an oven or reverbera- 
 tory furnace, with a fire rather inte ife than long con 
 tinued; during which it mult be frequently itirred to 
 prevent its fuiion. By tht* .operation, the arfenic is 
 expelled, and in feme works is collected in chambers 
 built purpofely above the c-Jcining furnace. 
 Laftly, the ore cleanfed and roamed is to be fated, 
 and reduced to ametall c .ftate. In this fufion, atren- 
 tion muft be given to the f ollpwing particulars, i . No 
 
 more. 
 
[ 5>i J 
 
 more heat is to be applied than is fufficient for the re 
 duction of the ore ; becaufe this metal is fufible with 
 very little heat, and is very eafily calcinable. 2. To 
 prevent this calcination of the reduced metal, a larger 
 quantity of charcoal is ufed in this than in moft other 
 fufions. 3. The fcoria muft be frequently removed, 
 left fome of the tin fhould be involved in it ; and the 
 melted metal mud be covered with charcoal powder, 
 to prevent the calcination of "its lurface. 4. No flux 
 or other fubftance, excepting the fcoria of former 
 fmeltings which contains fome tin, are to be added, to 
 facilitate thi fufion. 
 
 SECT. VII. Smelting, of Ores of Lead. 
 
 ' ORES of lead are either pure, that is > containing 
 no mixture of other metal ; or they are mixed with fil- 
 ver, copper, or pyrites. The me. hods of treating 
 ores of lead containing filver and copper, are de- 
 fcribed in the fec~tior.s of Smelting of Ores- of Silver and 
 of Copper ; and in the former of thefe an inftance is gi 
 ven of the method of fme'ting the ore of Ramelfberg, 
 \vl itch contains all thefe three metal?:. 
 
 Pure ores of lead, and thofe which contain fo fmall 
 a quantity only of filver as not to ccmpenfute for the 
 expence of extracting the' nobler metal, may be fmelt- 
 ed iii furnaces, and by operations fimilar to thofe ufed 
 at Rameliberg, or in the following methods, i. From 
 the lead-ore of Willach in Carinthia, a great part of 
 the lead is obtained by a kind of eliquation, during 
 the roaftir-g of the ore. For this purpofe, the ore is 
 thrown upon feveral ilrata or layers of wood, placed 1 
 in a c-.ilcining or reverberator}" furnace. By kindling 
 this wood, a great part of the lead flows out of the 
 ore, through the layers of fuel, into a bafon placed 
 for its reception. The ore which is thus roalled is 
 beat into fmaller pieces, mid expofed to a fecond opera 
 tion, fimilar to the forrr.er, by which more metal is 
 
 eliquated ; 
 
C 5^2 ] 
 
 eliquated ; and the retraining ore is afterwards ground, 
 wafhed, and (melted, in the o;d"mary nietliod. 
 
 The kad of Willach is the puroil of any known. 
 Schlutter afcr;bes its great purity to the method ufed 
 in extracting it, Ivy wkich the mod fuiible, and confe- 
 quently the pureft part of the contained lead, is fe- 
 parated from any lefs tulible metal which happens to 
 be mixed with it, and which remains in the roafted 
 ore. This method requires a very large quantity of 
 wood. 
 
 2. In England, lead ores are fmeltjd either up 
 on a hearth, or in a" reverberatory furnace called a 
 cupel. 
 
 In the firft of thefe methods, charcoal is employed 
 as fuel, and the fire is excited by bellows. Small 
 quantities of fuel and of ore are thrown alternately 
 and frequently upon the hearth. The fnfion is very 
 quickly effected : and the lead flows from the hearth 
 as faft. as it is feparated from the ore. 
 
 3. In the fecond method praclifed in England, pit- 
 coal is ufed as fuel. The ore is melted by means of 
 the flame pafling over its furface ; its fulphnr is burnt 
 and diflipated, while the metal is feparated from the 
 icoria, and collected at the bottom of the furnace. 
 When the ore is well cleanfed and pure, no addition is 
 requifite ; but when it is mixed with calcareous or 
 earthy matrix, a kind of fluor or fufible ipar found in 
 the mines is generally added to render the icoria more 
 fluid, and thereby to affift the precipitation of the me 
 tal. When the fufion has been continued' about eight 
 hours, a pailage in the fide of the furnace is opened, 
 through which the liquid lead flows into an iron ci- 
 ftern. But immediately before the lead is allowed to 
 rlow out of the furnace, the workmen throw upon the 
 liquid mafs a quandty of flacked qu ck'ime, which 
 renders the fcoria fo thick and tenacious, th ;t it may 
 be drawn out of the furnace by rakes. Schlutter men 
 tions this addition of quicklime in the iineltino- of lead 
 
 o 
 
 ores 
 
[ 503 ] 
 
 ores in England, but thinks that it is intended to fa- 
 cilitate the fa lion of the ores; whereas it really has a 
 contrary erfeci", and is never added till near the end of 
 the operation, when the fcoria is to be raked from the 
 furface of th6 metal. 
 
 SECT. VIII. Of the Smelting cfOres of Semi- 
 mda 1 *. 
 
 ANTIMONY is obtained by a kind of eliquation 
 from the minerals containing it, as is de c.'ibed in the 
 article ANTIMONY ; and the re :,uius of an.imo. y is 
 procured from antimony, by the process defended 
 in the fame article, and in the article R .G zt/i f An- 
 tim-jiiy. 
 
 Arfenlc, faffrs> and 'lijmuth, are obtained general 
 ly from one i.re, namel) , that cai.ed c I < t- The ar- 
 feivc of the ore Is fepara,eJ by roa i ng, and adheres 
 to the internal furfa e of a chimney, wir.ca is ext'.ndid 
 horizontally about 200 or 300 feet in lengt' s, and in 
 the fides of which are leveral do rs, by means of 
 which tiie arienic, \>hjn the operation is fmilheJ, may 
 be .wept *>ut ana c Heeled. Thefe chimneys are ge 
 ne: ally bent in a /,ig-'/ag direction, that they may 
 bcL.er ro arl an 1 Hop ;he arfenical Howers. Thefb 
 flowers are ofvaii.^us co ours, white, grey, red, yel 
 low, accor iir.'>; to tiic q i .nt'ty offulphar or other im- 
 pn :y wi b . . ippen to be mixed. Thjy 
 
 arc .it. .c-i oy repeated inblim,iiions ; while 
 
 foni.- -likame or oth.r ^ab lances arj added to detain 
 the .ulf hnr.: an -J t'< a Tnl the \ uriHcadon. 
 
 In the lame roaftihg ol 5 which t 1 e nrfenic 
 
 is expelcd, the b .f:^i;th or at leail Lhe grcatell j art 
 of this fernimcta' which is conraiucd in the ore, ' 
 very fuiib'e, and having no di p-iition to nni.^ 
 the c.^uius oi crbult, which itinaias in the ore, is fe- 
 paraiea-by eliquation. 
 
 T t The; 
 
[ 504 ] 
 
 The remaining part of die ro.ifbd ore confilts chief 
 ly of calx of regulus of cc bah, which not being vola 
 tile, as the aifenic is, nor fo cafily iufible : 4 s biimuth 
 is, lias been neither vol utilized nor melted. It coutains 
 aiib feme bifmulh, and a fmall Quantity of arfenic, to- 
 r with any filver or o her fixed metal which hap 
 pened to l*e contained in the ore. This rcafted ore be 
 ing reduced to a fine powder, and mixed with three or 
 i'cur times its weight of fme fane 1 , is the powder called 
 faffre or zcffre. Or the malted ore is fometirr.es fufed 
 \\iih about thrice its quantity of pure fand and as 
 much pure pot-nfh, by wliieh a blue giais, called//;/^, 
 is produced : and a metallic maf?, called fpei/s^ is col- 
 Icded at the bottom of the vellel in vhich the matters 
 are.fu niUallic mafs or fpeifs is compoied of 
 
 , according to the ccaitents of 
 
 the ore and the n:ethcv!s cf trejating it. The matters 
 .'..rent times are, nickel, regu- 
 
 liiti cf ccba!t, buh.uJi, urienic, fulphur, copper, and 
 tilvir. 
 
 Eifi. "'.'rm procured from any other ores but 
 
 that ( . might, however be extracted from 
 
 res, if a iuflicicnt quantity of thefe were 
 
 iound. I /a-ie method by which it is obtained 
 
 from . ly, by eliquationu 
 
 .11 nati\e, and invclopcdin much, earthy 
 
 fronj '\'].i;]i it cannot be feparaieci 
 
 it IK cl-ftilled either by afcent orby 
 
 t. When it is mineralifed by fulphur, that is 
 
 ., is contaii:eu in cinnabar, feme intj) mediate iub- 
 
 as quicklime or iron, muft be added in the di- 
 
 Lon, todif ircm the fulphur. 
 
 maden in Sp/ain is a cinnabar, 
 
 v, i h ' it ne happens to be fo blend 
 
 ed, tl . is requ'rcd to difcrgage the mer- 
 
 r. The ( n is there per- 
 
 ibrnitd in : ace c<hl ,v,o cu\itLs y one of 
 
 which 
 
C 5=5 ] 
 
 which is placed above another. The lower cavity is 
 the fire-place, and contains the fuel, refting upon a 
 gratC) through the bars of which-the air enter^, main 
 tains the fire and paffes into a chimney, placed at one 
 iide of the fire-place immediately above the door thro' 
 which fuel is to be introduced. The roof of this fire 
 place, which is vaulted and pLrced with ieveral holes, 
 is alib the floor of the upper cavity. Jnto this upper 
 cavity, the mineral from which mercury is to be ciiltil- 
 led is introduced, through a door in one ot the fides 
 of the furnace. In the oppoiite wall of this cavity are 
 eight openings, all at the fame height. To each of 
 theie openings is adapted a file of aludels connected 
 and luted together, extending 60 feet in length. 
 1'hefe aludels, which are earthen veflels open at each 
 end, and wider in the rniddie than at either extremity, 
 are Supported upon an inclined terras ; and the aludel 
 of each file, tkat is moil diftant from the furnace, ter 
 minates in a chamber built of bricks, which has two 
 doors av; J two chimneys. 
 
 "V\ lien the upper cavity is fi'.led fufficiently with the 
 miner il, a fire is made below, which is continued du 
 ring 12 or 14 hours. The heat is communicated thro* 
 !cs of the vaulted roof of the fire-place to the 
 mineral in the upper cavity, by which means the mer 
 cury is \o"., >nd its vapour paiies into the alu 
 dels, v : :-;h of it is condcufed and the rdt is 
 difcharged into the brick chamber, in which it circu 
 lates till it alfo is condenfed. If any air or fmoke 
 pafTes through the aludels along with the vapour of the 
 mercury, they efcape through the two chimneys of the 
 .-i'. Three days after the operation, when the 
 apparatus is iiifficieritly cooled, the aludels are unluted, 
 the doors of the chamber are opened, and the mercury 
 is collided. 
 
 THE END. 
 

THE UNIVERSITY OF CAUFORNIA LIBRARY