Bismuth Sulphites

Normal bismuth sulphite has not yet been obtained, but a number of basic compounds have been obtained. They are all white, powdery substances obtained by the action of a solution of bismuth nitrate in nitric acid upon a solution of sodium sulphite. The nature of the product depends upon the temperature and concentration of the solutions. Among the sulphites that have been described are: 9(BiO)₂SO₃.(BiOH)SO₃.2H₂O, 4(BiO)₂SO₃.(BiOH)SO₃. 5H₂O, 2(BiO)₂SO₃.3(BiOH)SO₃.2H₂O, 3(BiO)₂SO₃.7(BiOH)SO₃.10H₂O, (BiO)₂SO₃.3(BiOH)SO₃.H₂O. By the action of hot sulphurous acid upon bismuth trioxide, a white, powdery compound has been obtained to which is ascribed the formula (BiO)₂SO₃.2(BiOH)SO₃.4H₂O. It is stable in air, insoluble in water, but slightly soluble in sulphurous acid, from which it may be reprecipitated by dilution.