Basic indium sulphite, In₂(SO₃)₃.2In(OH)₃

Basic indium sulphite, In₂(SO₃)₃.2In(OH)₃.5H₂O, is obtained as an insoluble, white precipitate when a solution of an indium salt is boiled with sodium or ammonium sulphite. It dissolves in cold aqueous sulphurous acid, but separates out again as a crystalline powder when the solution is boiled. It loses 3H₂O at 100°, and another 5H₂O at 260°. At 280° sulphur dioxide begins to be evolved, and when further heated a residue of indium sesqui-oxide is ultimately obtained.