Cobalt Cobalti-cyanide, Co₃[Co(CN)₆]₂

Cobalt Cobalti-cyanide, Co₃[Co(CN)₆]₂.xH₂O, is formed as a rose-coloured, amorphous, and somewhat gelatinous precipitate on adding potassium cobalti-cyanide to cobaltous chloride solution. At 100° C. it loses water, becoming blue 3 in colour; at higher temperatures it becomes anhydrous. On exposure to moist air the blue salt readily absorbs water, becoming pink. Zwenger ascribes 14 molecules of water to the pink salt. It is completely soluble in ammonia. Potassium hydroxide yields blue basic salts which on standing or boiling are converted into rose-coloured cobaltous hydroxide.