Ammonium Chromicyanide, (NH₄)₃[Cr(CN)₆]

Ammonium Chromicyanide, (NH₄)₃[Cr(CN)₆], has been obtained by digesting the basic lead salt with excess of ammonium carbonate, and evaporating the liquid first by heating and then over sulphuric acid. The crystals, which belong to the mono- clinic system,

a:b:c = 0.806:1:0.66; β = 72° 14',

are isomorphous with the potassium salt and with potassium ferricyanide.