Lanthanum Tungstate

A solution of sodium tungstate yields with lanthanum chloride, in presence of alcohol, a precipitate which on drying has a pale blue colour. By dissolving lanthanum oxide and tungstic acid in fused sodium tungstate, the double tungstate, 4Na₂O.La₂O₃.7WO₃ or Na₈La₂(WO₄)₇, may be obtained after washing with water in which it is insoluble; if excess of sodium chloride is present in the melt, the salt obtained is 3Na₂O.2La₂O₃.9WO₃. The following lanthanitungstates have been prepared: 2(NH₄)₂O.La₂O₃.16WO₃.16H₂O, 5BaO.La₂O₃.16WO₃.16H₂O, and 5Ag₂O.La₂O₃.16WO₃.16H₂O; these are white amorphous powders, insoluble in water.