Cobalt

(ko-baull'.) [From Ger. kobold, a devil.] (Chem.) A metallic element first isolated by Brandt in 1733, although compounds of it were known to the ancients. It is a hard, steel-gray metal which takes a good polish, fuses at about the same temperature as iron, is magnetic, although not so powerfully so as iron, and ox1dizes at a red heat. Mineral acids di olve it, forming salts. The impure oxide of C. is called zaffre; but when fused with three parts of silicious sand and an alkali no flux, it is converted into a blue gla , called sm alt. This metal is used principally to give a permanent blue color to gla and enamels. The chloride of C. in solution affords a blue sympathetic ink. Characters written with this ink are invisible until exposed to heat. At. weight, 58-5. Symbol, Co. [s. 200]