Thallic sulphate, Tl₂(SO₄)₃

Thallic sulphate, Tl₂(SO₄)₃, is said by Meyer and Goldschmidt to be obtained by heating acid thallic sulphate to 220°. The heptahydrate, Tl₂(SO₄)₃.7H₂O, has been described by Strecker, but later experimenters have failed to prepare it.

Thallic sulphate is hydrolysed by water with great readiness, brown thallic hydroxide separating out. From a hot solution of thallic hydroxide in moderately concentrated sulphuric acid a basic thallic sulphate, Tl(OH)SO₄.2H₂O, crystallises out, accompanied by the amorphous basic salt Tl(OH)SO₄.H₂O.