Manual of qualitative analysis / by Robert Galloway.

  • Galloway, Robert.
Date:
1861
Catalogue details

Licence: Public Domain Mark

Credit: Manual of qualitative analysis / by Robert Galloway. Source: Wellcome Collection.

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    174. If a compound of zinc be moistened with protonitrate of cobalt and exposed on charcoal to the outer blowpipe flame, a mass of a beautiful green colour will be produced ; the colour is best seen when the mass has become cold. 175. Oxtpn or Cospait.—The colour of this oxide is greenish-gray, its hydrate being pale red. Salts of cobalt are red when they contain water of crystallization; in the anhydrous state they are blue. Their solutions are red; yet when concentrated, or when they contain a free acid, they are blue or green, but they become green simply by the addition of water. The solutions of the neutral salts that are soluble in water redden litmus paper, and are decomposed by heat. The principal mineral of this metal is the Brienr Wurre Copatt (Co As,+CoS,). 176. Ammonia produces in solutions of this oxide the same precipitate as the fixed alkalies do; but the precipitate is soluble in an excess of ammonia, the ammoniacal solution having a reddish-brown colour: the fixed alkalies produce no precipitate, or at least a very slight one, in an ammoni- acal solution of protoxide of cobalt. Ammonia fails to preci- pitate oxide of cobalt from its solutions, if chloride of ammo- nium is present. 177. Cyanide of potassium (KC, N=K Cy) precipi- tates from acid solutions of cobalt salts a brownish-white cyanide of cobalt, Co Cy, dissolving easily in an excess of the precipitant: from which solution the cyanide of cobalt cannot be again precipitated by acids, as it exists now in the form of cobalticyanide of potassium, K, Co, Cyg. 2 Co Cy+3 KCy+H Cy = K, Oo, Cy,+H. 178. “Ifthe salt of cobalt contains nickel, the addition of hydrochloric acid to the solution of the cyanides pro- duces a greenish precipitate, which always contains the 4