Strontium Aluminates

By the action of cold strontium hydroxide solution on metallic aluminium, or of excess of caustic potash on a hot solution of strontium chloride and potassium aluminate, a comparatively stable, crystalline tristrontium aluminate, Sr₃(AlO₃)₂.6H₂O, is obtained. There is probably also a gelatinous compound of approximate composition, Sr(AlO₂)₂.5H₂O.