Zinc Hydrosulphite, ZnS₂O₄

Zinc Hydrosulphite, ZnS₂O₄, was first obtained in solution by acting on zinc with sulphurous acid, and subsequently in minute rhombic needles by passing dry sulphur dioxide through a suspension of zinc in absolute alcohol. A stiff paste has been prepared commercially by the former method.

It dissolves readily in water, and forms double salts like Na₂S₂O₄. ZnS₂O₄. A crystalline paste of the double salt, Na₂SO₃.2ZnS₂O₄, has been commercially prepared.