Only in Silesia is metallic cadmium prepared

The proce there used is based on the superior volatility of cadmium to zinc. Large receivers are adapted to the mouths of the zinc retorts, in which the brown fume coming off during the first part of the distillation is condensed. This fume will contain about 30 per cent of cadmium, and is put into a zinc muffle kept at a moderate red heat in another furnace. In the conical iron condenser attached to this the brown powder condenses in a much purer state. This concentrated brown powder is then mixed with charcoal and heated moderately in small cylindrical cast-iron retorts, fitted with condensers. The heat not being sufficient to reduce and volatilize zinc, the cadmium is distilled off and condensed in the pure metallic state. It is cast into small, cylindrical bars about the size of a lead-pencil. Selling price varies between $1 and $1.50 per pound. The amount produced yearly is not over two tons. Commercial cadmium usually contains five to ten per cent of zinc, and sometimes a little tin and iron. Pure cadmium is a white metal, with a sp. gr. of 8.7, in hardne and strength between tin and gold. Melts at 320° C., volatilizes at 770° C. Its specific heat is 0.0567, conductivity for heat 577 (silver = 1,000), conductivity for electricity 221 (silver = 1,000). Both malle able and ductile.