Tin Arsenites

Stannous Orthoarsenite, Sn₃(NaO₃)₂.H₂O, was obtained by Stavenhagen by adding a solution of arsenious oxide to a solution containing potassium chlorostannite and potassium chloride. It may also be obtained by the action of sodium metarsenite or potassium tetrarsenite on a solution of stannous chloride. It is a white amorphous powder, sparingly soluble in water, but readily dissolved by dilute acids and alkalis with separation of metallic arsenic. It is also soluble in excess of arsenious acid.

Stannic Orthoarsenite, Sn₃(NaO₃)₄.5½H₂O, was obtained by Stavenhagen by adding an aqueous solution of arsenious oxide to one containing stannic and sodium chlorides. Addition of potassium tetrarsenite to a solution of stannic chloride gives a yellowish-white precipitate of a basic salt, 2SnO₂.Sn₃(NaO₃)₄; while with sodium metarsenite the composition of the precipitate corresponds with Sn₇As₂O₁₇. These compounds decompose on heating.