Aluminium sodium perborate, Al₂Na₂B₂O₉

Aluminium sodium perborate, Al₂Na₂B₂O₉.5H₂O, containing 7 to 9 per cent, of active oxygen, is prepared by mixing cold solutions of sodium aluminate (6.6 pts.) and boric acid (5 pts.) and adding 10 per cent, hydrogen peroxide solution (30 pts.). It is a colourless powder, sparingly soluble in water.