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Thefe proportions are nearly tliofe that havebeen given above. In Germany , where theworks are carried on on a large fcale, the loavesare ufuaily about 350 lbs. in weight, and arecompofed, when the copper is rich in filver, of3 parts of black copper, (75 lbs.) and 11 partsof lead, (275 lbs). In this cafe where thefilver is f per cent, of the copper, the relativeproportions of thefe metals will be about 1 partof filver, 132 of copper, and 488 of lead.Where the copper is poorer, only 10 parts oflead are ufed to 3 of the copper.

The next procefs is the Liquation, and isperformed in a furnace conftrudted for thepurpofe, which generally holds fix loaves, feton iron bars, feparated from each other bybricks, and having a channel beneath to conveythe lead and filver into a feparate bafon. Themanagement of the heat in this procefs is of thegreateft confequence. If it goes on properly,the lead flows out eafiiy, and the loaves gra-dually fink down and become honey-combed,but without lofing any fenfible portion of thecopper. If the heat is too great, particles ofthe copper are ieen to flow away along with thelead, on which t:re fire muft be immediatelydamped.. When no more lead flows out at thistemperature, the loaves are taken out, andwhen cold they have a dark red colour, andare very crumbly. It takes about four hours toeliquate the fix loaves.

Whatever care is taken in this procefs therealways remains a little filver in the loaves,which however, does not amount to more thanabout half an ounce in xoo lbs. when wellperformed. Some of the lead alfo remains,together with part of the iron, arfenic, fu'phur,and other impurities of the copper. The firltportion of the lead that flows out of the loavesis the richelt in filver, that which remains' inthe loaves is very poor, but ftill is worth ex-tracting, and is performed in the following way.When a futlicient number of the loaves remain-ing after liquation are coliefted they are rangedin a kind of oven fo as entirely to fill it, whichtakes about 1 50 pieces; they are then heated bythe flame of charcoal and green wood, drawingthrough the oven till they are moderately red-hot, at which time a quantity of metal andfcorix fweat out and drop down in the hearth.,confifting of a heterogeneous mafs of leadholding a little filver, of fcoriae, of litharge,arlemc, oxyd of iron and fulphur, and alfo offo me copper if the heat is raifed too high.This mals is wafhed with water, by which thefcorise are got rid of, the filver-holding lead

alone remains. When the droppings from thefurnace begin to be red and compact, it is afign that all the heterogeneous matter is ex-tradfed, and that the copper itfelf begins tomelt, on which the fire is removed. Theloaves are then taken out, and appear varnilbedover with a thick vitrefeent fcoria, which, ondropping them into water, cracks in everydirection, and is then readily knocked off byhammers, and the copper within is found con-fiderably pure. This procefs lafts about 30hours, half of which time is confirmed in bring-ing the loaves to the proper heat.

The fubfequent proceffes of refining thefilver-holding lead on a tell have been alreadydeferibed.

The procefs of eliquation, though highly in-genious, is confiderably expenfive and trouble-fome, and it appears to require no fmall degreeof Ikill to condudl it properly. To be perform-ed economically it is alfo necefiary that thecopper fliould hold a particular portion of filver,(neither more nor lefs within certain limits) thatis from -f- to | per cent, of filver, and hence,where there are quantities of copper of differentrichnefs in filver, much judgment may be{hewn in mixing them fo as to produce a metalwhich may be eliquated with mod profit. Butwhere there are natural or artificial alloys offilver and copper much richer in filver than thofeabove mentioned, the procefs of eliquation muftbe repeated two or three times on the famemetal, which would be extremely expenfive andtroublefome.

Reduction by Amalgamation.

This moft ingenious method of working filverores, was firft pradtifed by the Spaniards inSouth America , and has fince bqen adoptedwith numerous and effential improvements, inSaxony, Bohemia, Hungary , and fome otherparts of Europe . We (hall proceed'to deferibethe moft approved modern method of perform-ing this operation.

Thofe ores alone are amalgamated that comeunder the defeription of hard or meagre ; thatis, which contain none, or at leaf! only an in-confiderable quantity, of lead or copper. It isof importance however, that they fliould con-tain a certain proportion of iron pyrites, and ifa fufliciency of this is not naturally mingledwith the ore, it is a very judicious pradtice toadd it to the drefled ore, fo that its pyriticalcontents fhull always be brought to bear a cer-tain proportion, as nearly as poflible, to the filver,the amount of which latter muft be determined,by a previous afliiy.