Barium Sulphite, BaSO₃

Barium Sulphite, BaSO₃, is precipitated by the action of an alkali sulphite on a solution of a soluble barium salt. It is also formed by the action of sulphur dioxide on a suspension of barium hydroxide or carbonate, or of sulphur dioxide on barium oxide at 200°-230° C. It dissolves in sulphurous acid, from which it may be recrystallised in colourless hexagonal prisms. By heating the anhydrous salt it is decomposed into the sulphide and sulphate.

The solubility in water is very small and diminishes with rise of temperature, 0.01974 grm. dissolving in 100 grm. of water at 20° C., and 0.00177 at 80° C. The solubility is decreased by cane sugar at the lower temperature, but at the higher temperature it is at first increased, and then, with increasing concentration of sugar, it is decreased.

Barium sulphite is soluble in most acids.