Cobalt, Ox′ides of

Of these there are two, the protoxide and the sesquioxide; besides an acid compound of cobalt and oxygen, to which the name cobaltic acid has been given. 1. Cobalt, Protox′ide of. CoO. Syn. Oxide of cobalt , Grey o. of c. , Black o. of c. , Cobalt black . Prep. 1. By precipitating a solution of sulphate of chloride of cobalt with carbonate of sodium, and washing, drying, and igniting the powder which subsides. 2. By boiling powdered bright-white cobalt ore (from Cornwall) in dilute nitric acid, and adding a solution of carbonate of pota ium, very gradually, until the clear liquor, after the impurities have settled, becomes of a rose colour; and then as long as a precipitate falls; wash and dry it as before. Prop., . A grey powder, turning black on exposure to the air; strongly basic; and forming salts with the acids, having a fine red tint. It is remarkable for the magnificent blue colour it communicates to gla , and by this character its presence may be readily detected before the blowpipe; the substance to be examined being fused with borax on a loop of platinum wire. Used to make blue colours for painters, stains and glazes for enamellers, gla -melters, potters, . In medicine it has occasionally been given as a remedy for rheumatism. 2. Cobalt, Sesquiox′ide of. Co 2 O 3 . Syn. Perox′ide of Cobalt . A black, insoluble, neutral powder, obtained by mixing solutions of cobalt and of chloride of lime; or, by heating the protoxide to redne in an open ve el.