268 METALS. 



ter 24*0. Gives arsenical fumes when heated, and fasts ; 

 yields a blue glass with borax. 



The earthy ore is sometimes called peach blossom ore, 

 from its color ; and also red cobalt ochre. 



Dif. Resembles red antimony, but that species wholly 

 volatilizes before the blowpipe. From red copper ore it dif- 

 fers in giving a blue glass with borax ; moreover the color 

 of the copper ore is more sombre. 



Obs. Occurs with ores of lead and silver, and other co- 

 balt ores. Schneeberg, in Saxony, Saalfield in Thuringia. 

 and Riechelsdorf, in Hessia, are noted European localities 

 [t is found also in Dauphiny, Cornwall, and Cumberland 

 Occurs in the U. States, at Mine La Motte, Missouri. 

 Uses. Valuable as an ore of cobalt, when abundant. 



Roselite. A rose-red mineral, related to, if not identical with, co- 

 balt bloom. 



Arsenite of cobalt is a compound of arsenous acid and oxyd of cobalt, 

 and results from the decomposition of other cobalt ores. 



Sulphate of cobalt, or Cobalt vitriol. It has a flesh or rose-red tint, 

 and astringent taste. Consists of sulphuric acid, oxyd of cobalt and 

 water. 



GENERAL REMARKS ON COBALT AND ITS ORES, 



The two arsenical ores of cobalt afford the greater part of the cobalt 

 of commerce. The earthy oxyd is so abundant in the United States, 

 that it promises to be a profitable source of this metal. Cobalt is never 

 employed in the arts in a metallic state, as its alloys are brittle and un- 

 important. It is chiefly used for painting porcelain and pottery, and 

 is required for this purpose in the state of an oxyd, or the silicated oxyd 

 called smalt and azure. 



Cobalt comes from Germany mostly in the silicated condition. The 

 zaffre is prepared by calcining the ores of cobalt in a reverberatory fur- 

 nace ; the sulphur and arsenic are thus volatilized, and an impure oxyd 

 remains, which is next mixed and heated with about twice its weight 

 of finely powdered flints. 



By another process the ore is pulverized and roasted, to expel the 

 greater part of the arsenic ; a sulphate is then formed by heating for 

 an hour with concentrated sulphuric acid The sulphate is dissolved in 

 water, and a solution of carbonate of potash added to separate the iron ; 

 and when the blue color of the cobalt begins to be thrown down, the 

 supernatant liquid is decanted and filtered, and the cobalt is precipitated 

 ]>y means of a solution of silicated potash, (prepared by heating to- 

 gether 10 parts of potash, 15 of finely pulverized quartz, and 1 of char- 

 coal, and afterwards treating the melted mass with boiling water.) The 

 eilicate of cobalt thus prepared is said to be superior to that procured 



How does cobalt bloom differ from red antimony ? From what orea 

 is the cobalt of commerce obtained ? For what is cobalt used 1 In 

 what condition is it imported from Germany ? What is zaffre t 



