Cadmium Thiosulphate, CdS₂O₃

Cadmium Thiosulphate, CdS₂O₃.2H₂O, is obtained by double decomposition between cadmium sulphate and barium or strontium thiosulphate. A colourless or yellowish oil separates when the solution, filtered free from insoluble sulphate, is treated with alcohol or alcohol and ether. After some time this oil solidifies into crystals.

The yellow-tinged crystals are monosymmetrical, retain their water in dry air, and decompose, gradually at low temperatures and quickly at high, according to the equation

4CdS₂O₃ = 3CdS+CdSO₄+4SO₂.

The double salts, as follows, have been prepared: Na₂S₂O₃.3CdS₂O₃.9H₂O, Na₂S₂O₃.2CdS₂O₃.7H₂O, and 3Na₂S₂O₃.CdS₂O₃.9H₂O; 3Na₂S₂O₃.CdS₂O₃.16H₂O, 3Na₂S₂O₃.CdS₂O₃.3H₂O; 5K₂S₂O₃.3CdS₂O₃, 3K₂S₂O₃.CdS₂O₃.2H₂O; 3(NH₄)₂S₂O₃.CdS₂O₃.3H₂O, 3(NH₄)₂S₂O₃.CdS₂O₃; 2BaS₂O₃.CdS₂O₃.8H₂O, 3BaS₂O₃.CdS₂O₃.8H₂O; 3SrS₂O₃.CdS₂O₃.10H₂O.