Thallium ferrocyanide, Tl₄Fe(CN)₆

Thallium ferrocyanide, Tl₄Fe(CN)₆.2H₂O has been prepared. It is formed as yellow crystals by adding a hot concentrated solution of thallous sulphate to one of potassium ferrocyanide and allowing to cool. It is sparingly soluble in cold water but more readily in hot and in potassium ferrocyanide solution. If dilute solutions of thallous sulphate and potassium ferrocyanide are mixed and alcohol added, a complex potassium thallium ferrocyanide, K₄Fe(CN)₆.K₃TlFe(CN)₆.6H₂O, is obtained.