M E R

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"will take up every thing but the muriat of fiver,from which, when wafhed and dried, theamount of filver in the ore may be readilyafcertained. Now decompofe the nitre-muri-atic folution at a boiling heat by carbonatedalkali, and add the white precipitate thus ob-tained to the other carbonated precipitate ; mixthefe with a little oil or fugar (the latter is thebell) and proceed to diftiliation in a fmallcoated' glafs retort; raife it gradually to ignition,and continue it at that temperature as long asany mercury comes over. What remains be-hind is a little metallic bifmuth and charcoal.

Cinnabar may be analyfed in the followingmanner. After being reduced to a fine powder,let it be digefted repeatedly in a mixture of 3parts muriatic acid and 1 nitric, the wholemoderately diluted; by this every thing will betaken up except the fulphur and the filex.This refidue being waihed, dried, and weighed,is to be ignited, and the remaining filex beingdeducted, the difference of weight indicates theamount of the fulphur. The nitro-muriaticfolution being decompofed by carbonated alkaliat a boiling heat, and the precipitate thus ob-tained being mixed with a little lamp-black, anddiftilled, the mercury will pafs over in the me-tallic ftate: what remains in the retort is mag-netic oxyd of iron, and the cafual earth (excep-ting filex) contained ip the ore, together with alittle charcoal, which may be feparated in theufual way.

The liver-coloured and bituminous ores may betreated exaCt ly in the fame manner as the pre-ceding ; but as thefe ores fometimes contain alittle filver, the matter infoluble in nitro-muri-atic acid may be not merely fulphur and filexbut muriat of filver •, after therefore the fulphuris burnt off, the refidue mixed with twice itsweight of pearlafh is to be ftrongly ignited inan earthen crucible, and then treated withdilute muriatic acid which will take up thealkali and earth leaving behind the filver infmall metallic grains.

The bell way of analyfing the horn mercuryis to digeft it in a little diftilled vinegar,by which the native mercury which is fome-times dilperfed through it will be left behind.To the clear folution add nitrat of barytes,which will feparate the fulphuric acid in theftate of fulphat of barytes : this being taken out,drop in nitrat of filver, which will feparate themuriatic acid in the ftate of muriated filver.T.he mercury, now in the ftate of nitrat, remainsin folution, and may be exhibited in the metal-lic ftate by precipitating it by means of ironand fubfequent waffling in muriatic acid; or

vol. n.

by throwing It down by a carbonated alkali,and diftilling the precipitate with a little lamp-black.

The a flay of mercurial ores in the dry wayis very iimple. The fpecimen being pulverized,and accurately mixed with a of its weight ofquicklime and an equal portion of iron filings,is to be pretty ftrongly ignited in an iron.orearthen retort as long as any mercury comesover into the receiver.

§. 3. ReduBlon of ores.

The modes of extracting the metal from theores of mercury are very Iimple. I lie fit ftthat we fhall mention is the beft and molt feien-tific, and prattifed at the mines of Deux Fonts,and of Idria. The ore being brought out ofthe mine, is forted by hand with confider-able accuracy, rejecting thefe parts that appearto be deftitute of metal. This is an expenfiveand rather tedious procefs, but has fuperfededthe ancient method of feparating the cinnabarby waffling, on account of the prodigious lofsof metal in that operation. The forted orebeing reduced to powder is carefully mingledwith -5- more or lefs, according to the proportionof cinnabar contained in the ore, of quicklimewhich has fallen to powder by expofure to theair. This mixture is then put into iron fetorts,capable of holding about 60 lbs. weight, whichwhen thus charged, are fixed in a long furnace,to the number of 40 or 50 : a glafs receiverbeing then attached to each retort, but notluted, a gentle fire is applied in order to driveout all the moifture ; when this is effected, thejuncture of the veflels is clofely flopped withtempered clay, and a full red heat is applied forfeven or eight hours, at the expiration of whichtime all the mercury will have been volatilizedand condenfed in the receiver. The commonproduce varies between fix and ten ounces- ofmetal from 100 lbs. of the ore.

The method praCtifed at Almaden, in Spain ,differs confiderably from the preceding, and ismuch more rude and inartificial. The piecesof pure cinnabar being firft picked out from theore, in order to be difpofed. of to the painters,and manufacturers of fealing wax, the reft isforted into three parts, the firft is the richeft,and is in pieces of a moderate fize, the fecondis in fmaller pieces, and lefs abounding in metal,the third is the dull and fmalleft fragments ofthe other two, which are kneaded up with clay,and formed into bricks, that are dried carefullyin the fun. The furnace ufied for extractionof the mercury is an oblong mafs of mafonry,divided horizontally into an upper and lowerK