Calcium Pyrovanadate, Ca₂V₂O₇

Two hydrates have been described, Ca₂V₂O₇.2.5H₂O, obtained as a white amorphous powder by precipitating calcium chloride with sodium pyrovanadate and drying at 100° C., and Ca₂₂O₇.2H₂O, obtained as colourless needles by precipitating an excess of calcium chloride with ammonium vanadate in ammoniacal solution. The water of crystallisation is easily driven off by heat, leaving a yellow powder. The salt is readily soluble in dilute acids.