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e chief commercial source of bismuth. The oxide, bismuth ochre, Bi2O3, and the sulphide, bismuth glance or bismuthite, are also of commercial importance. The former is found, generally mixed with iron, copper and arsenic oxides, in Bohemia, Siberia, Cornwall, France (Meymac) and other localities; it also occurs admixed with bismuth carbonate and hydrate. The hydrated carbonate, bismutite, is of less importance; it occurs in Cornwall, Bolivia, Arizona and elsewhere. Of the rarer bismuth minerals we may notice the following:--the complex sulphides, copper bismuth glance or wittichenite, BiCu3S3, silver bismuth glance, bismuth cobalt pyrites, bismuth nickel pyrites or saynite, needle ore (patrinite or aikinite), BiCuPbS3, emplectite, CuBiS2, and kobellite, BiAsPb3S6; the sulphotelluride tetradymite; the selenide guanajuatite, Bi2Se3, the basic tellurate montanite, Bi2(OH)4TeOe; the silicates eulytite and agricolite, Bi4(SiO2)3; and the urnayl arsenate walpurgite, Bi(UO2),(OH)24(A3O4)4. _Metallurgy._--Bismuth is extracted from its ores by dry, wet, or electro-matallurgical methods, the choice depending upon the composition of the ore and economic conditions. The dry process is more frequently practised, for the easy reducibility of the oxide and sulphide, together with the low melting-point of the metal, renders it possible to effect a ready separation of the metal from the gangue and impurities. The extraction from ores in which the bismuth is present in the metallic condition may be accomplished by a simple liquation, or melting, in which the temperature is just sufficient to melt the bismuth, or by a complete fusion of the ore. The first process never extracts all the bisbuth, as much as one-third being retained in the matte or speiss; the second is more satisfactory, since the extraction is more complete, and also allows the addition of reducing agents to decompose any admixed bismuth oxide or sulphide. In the liquidation process the ore is heated in inclined cylindrical retorts, and the molten metal is tapped at the lower end; the residues being removed from the upper end. The fusion process is preferably carried out in crucible furnaces; shaft furnaces are unsatisfactory on account of the disintegrating action of the molten bismuth on the furnace linings. Sulphuretted ores are smelted, either with or without a preliminary calcination, with metallic iron; calcined ores m
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