Ammonium cuproferrocyanide, (NH₄)₂Cu₂Fe(CN)₆

Ammonium cuproferrocyanide, (NH₄)₂Cu₂Fe(CN)₆, results when cuprous cyanide is boiled with a solution of ammonium ferrocyanide containing ammonium sulphite, and hydrogen passed through the mixture. It may also be obtained by double decomposition of the sodium salt with ammonium nitrate. It crystallises in small, colourless six-sided prisms, which readily decompose both under water and on mere exposure to air or in a vacuum.