CAD'MIUM (Neo-Lat., from Lat. cadmia; see A metallic element discovered in 1817 by Stromever. It is not found native, but occurs as the sulphide in the mineral greenoekite, and in association with zinc ores. Greenockite is found in Bohemia and in Hungary; also in Le high County. Pa., but in too small quantities to be of commercial importance.
Cadmium is a constituent of most zinc ores, and as it is more volatile than zinc it passes over first, in the reduction of such ores, as cad mium oxide. This is collected, mixed with char coal, and the mixture heated in iron tubes, from which the cadmium distills over in a more or less impure state. In order to purify it, the metal is redistilled and the product dissolved in hydro chloric acid, from which solution metallic cad mium is precipitated with zinc.
Cadmium ( symbol, Cd ; atomic weight, 112.38) is a bluish-white lustrous metal with a fibrous fracture, and capable of taking a high polish. Its specific gravity is 8.65. It melts at :320° C.
1608° F.) and boils at 763° C. (1405.4° F.). It finds some use in the manufacture of alloys, as it generally increases the fusibility of metals with out destroying their malleability. An amalgam of cadmium and tin is need in dentistry.
Cadmium forms a regular series of salts, of which the iodide, obtained by digesting one part of the metal with two parts of iodine in water and evaporating the solution, is used in medicine, and also for iodizing collodion. The most im portant compound of cadmium is the sulphide, which is precipitated from a solution of cadmium ea It by hydrogen sulphide. Cadmium sulphide is an orange or lemon-yellow powder that is of great permanency, and is used as a pigment under the name of cadmium yellow. It is also used for coloring toilet soaps, for the pro duction of blue flames in pyrotcchny, and in calico-print ing.