Lead Pyrophosphate, Pb₂P₂O₇

Lead Pyrophosphate, Pb₂P₂O₇, is precipitated as a white, amorphous powder when a solution of a pyrophosphate is added to a lead salt solution; and is also obtained when lead oxide is fused with potassium metaphosphate and the melt is extracted with water. Water-vapour at 280°-300° C. converts it into orthophosphate. Various hydrates and double salts of lead pyrophosphate have been described. It is noteworthy that this salt shows so little tendency to pass into orthophosphate. A hydrate of sodium pyrophosphate would probably be impossible.