Gold Arsenites

Solutions of auric salts are reduced to the metal by the addition of aqueous solutions of arsenious oxide. Aurous orthoarsenite, Au₃NaO₃, is obtained by treatment of a solution of auric chloride with potassium tetrarsenite. It is a purple-red powder, which blackens when heated or exposed to light. By adding potassium ortho- arsenite to a solution of auric chloride in 50 per cent, alcohol, auric arsenite, AuNaO₃.2H₂O, is obtained as a pale brown powder, which is unstable in air at ordinary temperatures and on warming rapidly decomposes forming gold arsenide and gold. It is readily soluble in water, dilute acids and aqueous ammonia.