CADMIUM
The element. This element occurs in small quantities in some zinc ores. In the course of the metallurgy of zinc the cadmium compounds undergo chemical changes quite similar to those of the zinc compounds, and the cadmium distills along with the zinc. Being more volatile, it comes over with the first of the zinc and is prepared from the first portions of the distillate by special methods of purification. The element very closely resembles zinc in most respects. Some of its alloys are characterized by having low melting points.
Compounds of cadmium. Among the compounds of cadmium may be mentioned the chloride (CdCl2·2H2O), the sulphate (3CdSO4·8H2O), and the nitrate (Cd(NO3)2·4H2O). These are white solids soluble in water. The sulphide (CdS) is a bright yellow substance which is insoluble in water and in dilute acids. It is valuable as a pigment in fine paints.