.SILVER. 



its fpirting out, which it does when the refrigeration is gra- 

 dual, owing probably to its tendency to cryltallize. In 

 England the filver is left to cool in the cupel, and fome in- 

 convenience is caufed by the fpirting, which might be avoided 

 by the former mode. 



The filver thus extrafted is not fufEciently pure ; it is 

 again refined in a reverberatory furnace, being placed in a 

 cupel lined with bone-a(hes and expofed to a greater heat : 

 the lead which had efcaped oxydation by the firft procefs is 

 converted into litharge, and abforbed by the afhes of the 

 cupel. 



The lad portions of litharge in the firft procefs are again 

 refined for filver, of which it contains a part that was driven 

 off with it. The litharge is converted into lead again, by 

 heating it with charcoal ; part is fometimes fold for a pig- 

 ment, or converted into red lead. The lofs of lead by this 

 procefs differs confidcrably, according to the quality of the 

 lead. The litharge commonly obtained from three tons of 

 lead amounts to 58 hundred weight ; but when it is again 

 reduced to a metallic ftate it fcldom contains more than 52 

 hundred weight of lead, the lofs on three tons being about 

 eight hundred weight. The Dutch are faid to extraft the 

 filver from the fame quantity of lead, with a lofs of only fix 

 hundred weight. 



Silver- Mines of France — The mine of AUemont, ten leagues 

 from Grenoble, in the department of I fere, is fituated near 

 the fummit of a mountain, compofed of thin beds of mica- 

 Hate and hornblende, curioufly contorted and broken. Its 

 elevation is about 3000 yards above the level of the fea. 

 The veins are numerous, and run in all direftions: the mine- 

 ral appears to have filled alfo numerous fiii'ure?; in the rock. 

 The ores are native filver, vitreous filver, red lilver-ore, and 

 horn-filver. Silver appears alfo dilieminated m a kind of 

 ferruginous clay, and is accompanied with various ores of 

 cobalt, antimony, arfenic, and nickel. The matrix was 

 ferruginous clay and carbonate of lime, mixed with afbeftus, 

 epidote, and calcareous fpar. The veins were much richer 

 near the furface than at a great depth, and the working of 

 this remarkable mine is at prefent nearly abandoned. Red 

 filver-ore has alfo been found in the Vofges, in the depart- 

 ment of the Upper Rhine, in a vein of argentiferous copper- 

 ore. Indications of filver have been traced in other diftricts 

 of France. The lead-ores of fome parts of France are alfo 

 fufficiently rich in filver to repay the expence of extradtion. 



The Jlhvr-mines of Spain are the moft ancient known in 

 Europe. It appears, as well from the accounts of hiftorians, 

 as from the numerous veftiges of ancient workings, that the 

 operations were carried on to a confiderable extent. The 

 molt remarkable mine was that at Guadalianel, in Andalufia, 

 in the Sierra Morena, five leagues to the north of Seville ; 

 the ore which it contains is the red or ruby filver, in a matrix 

 of compaft galena. Smce the difcovery of South America 

 no attention has been paid to the mines of Spain, though 

 formerly fo productive both of filver and gold. 



Germany. — The minmg diftrift of Freyberg, in Saxony, 

 contains numerous veins that yield filver. The veins that 

 traverfe rocks of gneifs are generally compoled of quartz, 

 calcareous fpar, and fluor fpar ; they inclofe argentiferous 

 lead, vitreous filver-ores, ruby filver, and grey argentiferous 

 copper-ore. The mine at Annaberg, according to Klaproth, 

 contains muriate of filver (horn-ore) mixed with much clay, 

 which is imbedded in compaft lime-ftone. The mines of 

 Schneeberg, in Mifnia, and of Hartz, in Hanover, contain 

 argentiferous lead, accompanied with proper filver-ores. 



Hungary. — The mines of Schemnitz and Cremnitz, in 

 Hungary, have been long celebrated, both for the richnefs 

 of their productions and the immenfe extent of the opera- 



tions. The rocks in which the mining operations are car- 

 ried on, are defcribed as being compofed of an argillaceous 

 grey-ftone, mixed with quartz or fchorl, or particles of cal- 

 careous fpar. To this rock baron Born has given the name 

 of the metalliferous rock, faxum metalliferum : it is defcribed 

 by him as containing three principal veins, running from 

 north to fouth, and parallel with the river Gran, following 

 even the windnigs of the river. From this circumftance we 

 fhould infer, that the river itfelf had originally taken the 

 courfe of a frafture by another vein. The dip or inclina- 

 tion of all the veins is from well to eaft, varying from 30 

 to 70 degrees. In one part of the vein, called the fpitaler 

 vein, it is joined with an argillaceous white vein, which runs 

 along with it on the hanging fide, and from the place of 

 junftion the vein is found to contain filver. In this white 

 clay are occafionally found nodules of fpar and mafies of 

 quartz, which yield from four to five ounces of filver in the 

 hundred weight. The fecond great vein at Schemnitz has 

 nearly the fame charafters as the firft. The third great vein 

 is more irregular in its inclination, and the ores are not fo 

 rich in filver, but in fome parts it contains a confiderable 

 quantity of gold. 



Some notion may be formed of the extent of the mining 

 operations at Schemnitz, from the gallery or level called the 

 Emperor Francis' Gallery, by which the whole of the 

 royal mine is drained and cleared of water. This gallery, 

 which forms a very confiderable excavation, and is carried 

 through hard rock, was a work of immenfe labour and dif- 

 ficulty ; it is five Englifti miles in length : it was befun in 

 1748, and finifhed in 1765. 



The mountains round Kremnitz, according to baron Born, 

 are compofed of the fame metallic rock already defcribed ; 

 but according to Patrin, they confift of primitive trap. At 

 this place very extenfive operations, which were begun at 

 leaft a thoufand years ago, have been eltablilhed on a large 

 and rich gold vein, and fome of its branches. The rock is a 

 white folid quartz, mixed with fine auriferous red and white 

 filver-ore, and with auriferous pyrites. At the depth of 160 

 fathoms, the vein continued rich and produdtive. 



Konigft)erg is another mining-town of Hungary, fome 

 miles to the north-welt of Schemnitz. The valley in which 

 this place is fituated i; bounded on one fide by the fame kind 

 of metallic rock, and on the other, towards the north, by 

 granite mountains. In the royal mine, at the time it was 

 vifited by baron Born, the vein was obferved to run between 

 the metallic rock, which formed its hanging fide, and the gra- 

 nite, which was its hading or lower fide. The vein is grey 

 quartz, mixed with auriterous pvrites. The firft fteam or 

 fire-engine eftabhfiied in the Lower Hungarian mines was 

 erected at Konigfberg, in 1725, by Ifaac Porter, an Eng- 

 lifti engineer, wlio was then in the imperial iervice. 



Bohemia. — The circle of Saatz, in Bohemia, abounds in 

 various metallic ores, among which the ores of filver occa- 

 fionally predominate. The prevailing rocks are gneifs and 

 argillaceous fciiiftus. The veins at Catharineherg traverfe 

 gneifs, and generally run in a north and fouth direction, and 

 parallel to the mountain in which they are fituated. But 

 there are alfo fome powerful veins which crofs the mountain. 

 One of this nature i* defcribed, which feems to be irfenfibly 

 blended with the mountain rock. The vein-ftone is alfo of 

 the fame kind of rock, but occafionally afluming the cha- 

 rafters of a variety of granite. It is obferved, that the 

 vein, which feldom exceeds a foot in width, diminifhes in 

 thicknefs when the containing rocks become harder ; and 

 when the fides are found incrufted with a ferruginous clay, 

 it appears to be richer in ores. Fiflures from the fides of 

 the vein are found to improve it : a fine white clay, with 

 12 quartz 



