Uranous metaphosphate

Uranium Monophosphide, UP. —Uranyl hypophospbite on strongly heating leaves a residue consisting of a mixture of uranous pyrophosphate, uranous metaphosphate, and uranium monophospMde, hydrogen alone escaping. 

All acid uranium phosphate, UH2(P04)2 or UO2.P2O5.H2O, is obtained as a gelatinous 23recipitate when ordinarj " sodium phosphate, or excess of sodium metaphosphate, is added to a solution of uranous chloride. It may be obtained in the crystalline form as UH2(P04)2.oH20. Aloy also describes a uranous chlorophosjihate of composition UH2(P04)2.UCl4 (see p. 295). 

Complex phosphates of uranium and the alkali or alkaline earth metals have been prepared by fusing an intimate mixture of the alkali phosphate with an excess of uranous oxide in a jdatinum Rose crucible through which carbon dioxide was passing. The fusion may be facilitated by the addition of a little alkali chloride. On slowly cooling the crucible, well-defined crystals of the double phosphate are formed. If the alkali metaphosphate is used, salts of the type RgU(P04)2 where R=K, Na R2=Ca, Sr, Ba, are obtained. 

The salt, KU2(P04).j or K3O.4UO2.8P2O5, is obtained by heating the orthophosphate, KgHPOj, with a slight excess of potassium uranium cWoride it forms small dark green crystals. The corresponding sodium salt is prepared by fusion of sodium metaphosphate with excess of uranous oxide. 

---