Hydroxylamine Orthoarsenate, (NH₂OH)₃.H₃AsO₄

Hydroxylamine Orthoarsenate, (NH₂OH)₃.H₃AsO₄, is obtained when aqueous arsenic acid is made alkaline with an excess of sodium carbonate and then treated with hydroxylamine hydrochloride until faintly acid. Microscopic rhombic prisms slowly form, which yield an acid solution in hot water, from which they may be recrystallised. The salt readily reduces ammoniacal silver nitrate and Fehling's solution.