Strontium Pyroarsenate, Sr₂As₂O₇

Strontium Pyroarsenate, Sr₂As₂O₇, is formed as colourless transparent crystals by the action of fused potassium metarsenate on strontium oxide and subsequent treatment with anhydrous glycerol. Chloride may be substituted for the oxide provided that the arsenate forms more than 70 per cent, of the mixture. The salt is hydrated by the action of cold water.