Thallous Orthoarsenite, Tl₃NaO₃

Thallous Orthoarsenite, Tl₃NaO₃, is a yellowish-red crystalline solid obtained by boiling a solution of thallous sulphate with potassium orthoarsenite and gradually adding potassium hydroxide solution; or the thallous salt may be boiled with alkali and then treated with aqueous arsenious oxide or potassium orthoarsenite. The crystals are sparingly soluble in water or alcohol, but readily dissolve in acids.