Cadmium

( Chem.) A metal found in small quantities in the ores of zinc, its presence being indicated, during the extraction of this metal, by the appearance of a brown flame (brown blaze) at the commencement of the distillation, before the characteristic zinc flame (blue blaze) is seen at the orifice of the iron tube. more easily vaporized than zinc (boiling at 158°), so that the bulk of it is found in the first portions of the distilled metal. If the mixture of C. and zinc be di olved in diluted sulphuric acid, and the solution treated with hydrosulphuric acid gas, a bright yellow precipitate of sulphide of C. (CdS) is obtained, which is employed in painting, under the name of cadmia. By di olving this in strong hydrochloric acid and adding carbonate of ammonia, the carbonate of C. (CdO,CO2) is precipitated, from which metallic C. may be extracted by distillation with charcoal. Although resembling zinc in its volatility and its chemical relations, in appearance it is much more similar to tin, and emits a crackling sound like that metal when bent. Like tin, also, it is malleable and ductile at the ordinary temperature, and becomes brittle at about 180°. It is even more fusible than tin, becoming liquid at 242°, so that it is useful for making fusible alloys. In its behavior with acids and alkalies, C. is similar to zinc, but the metal is easily distinguished from all others by its yielding a characteristic chestnut-brown oxide when heated in air. This oxide (CDO) is the only oxide of C. The iodide of C. (CdI), obtained by the action of iodine upon the metal in the presence of water, is employed in photography. Being a very stable salt, it is not decomposed when added to collodion. For this reason, collodion iodized with it preserves its sensitivene undiminished during many months. For photographic purposes it should be purchased at a respectable chemist's, as it is a salt that is very difficult to prepare for one's self. The equivalent of C. is 112; sp. gr., 86; symbol, Cd. Cad'mus. According to ancient Greek tradition, C. was the leader of a colony of Phoenicians, who settled at a very early date in Bœotia, and founded the city of Thebes, B. C. about 1450. The Greeks attributed to him the introduction into their country of the sixteen simple alphabetical characters; and the close anal in form between the Greek and Phoenician alphabets renders this account extremely probable. His personal history is almost entirely fabulous. Cado's ia Valley, in New York, a post-office of Dela ware co. Cadott's, or Cadotte Pa , in Montana, a pa through the Rocky Mountains, about 47° N. Lat., and 112° 10 W. Lon.