Lithium sulphite, Li₂SO₃

Evaporation of the solution obtained by the action of sulphur dioxide on lithium carbonate suspended in water yields the monohydrate, Li₂SO₃,H₂O; addition of alcohol or ether precipitates the dihydrate, Li₂SO₃,2H₂O. The sulphite is readily soluble in water, and is susceptible to atmospheric oxidation. Heat expels the water of crystallization, and causes partial decomposition into sulphate and sulphide. Double sulphites of lithium with potassium and sodium have been prepared.