COBALT (Ger. Kobalt; possibly the same as Kobolcl, goblin). A metallic element discovered by Brandt in 1735. The word cobalt is found in the works of Paracelsus and other early writers, and was used to designate minerals that suggest ed the appearance of metallic ores, but when smelted failed to yield any metal; hence, the name 'cobalt,' signifying sprite, was given to such minerals on account of the illusive character of their metallic constituents. It was also applied to certain blue pigments containing cobalt as far back as the times of the Greeks, but it was not until Brandt investigated the blue coloring of smalt that the elementary character of the metal was established. The element is found free only in meteorites, but it usually occurs in nature with arsenic or sulphur, and with nickel and other metals. as smaltite, a cobalt diarsenide; as skattcruditc, a cobalt triarsen ide; as eobaltite, a cobalt sulpharsenide; as asbolite, a wad containing oxide of cobalt: and as the earthy minerals noumcite from New Cale donia, and garnicrite from Oregon. The metal itself may he prepared by igniting the oxalate. when the carbon and oxygen pass off, leaving the cobalt behind.
Cobalt (symbol Co, atomic weight 59) is a steel-gray lustrous crystalline metal that is nearly white when polished, somewhat malleable, ductile at a red heat. and highly magnetic, with a specific gravity of S.5 to 8.9. It melts at C. The metal has no uses by itself. although it forms alloys with copper, iron, and manganese, and it may be deposited on metals by electro plating as a fine, lustrous coating, which is said to he harder, more tenacious, and of greater beauty than that obtained with nickel. Cobalt
combines with oxygen to form a monoxide or cobaltous oxide, and a sesquioxide or cobaltic oxide. Its principal commercial salts are pig ments. Of these the most important is the cobalto-eobaltie oxide, which is a mixture of both oxides, corresponding in character to the magnetic oxide of iron. This is obtained com mercially from the ores of cobalt and from speiss in the separation of nickel ; in the latter case the speiss is fused with fluor-spar and chalk so as to yield a richer matt containing less iron; the matt is ground and oxidized by thorough roasting, which also serves to expel arsenic and sulphur; it is then dissolved in hydrochloric acid and diluted with water. From this solution cobalt oxide is precipitated by the addition of bleaching-powder. This oxide is used for the preparation of various salts of cobalt and for making the smalt employed by enamelers and potters for the production of the finest blue glaze on porcelain. When heated with alumina it yields a fine blue pigment which is called vari ously cobalt blue, cobalt ultramarine, and The blue: and when heated with zinc oxide it yields the pigment called cobalt green or Rin mann's green. Smalt is a permanent blue pig ment consisting essentially of cobalt silicate and potash; it is also called bleu d'azur and bleu de sasc. Zaffre is an impure oxide obtained by roasting cobalt ore and mixing with several parts of coarse sand. During 1899, 10.230 pounds of cobalt oxide were mined in the United States, having a value of $18,512.