Lead Tungstates

The normal salt occurs native as stolzite and raspite. It may be obtained, by the addition of a lead salt to a solution of an alkali tungstate, as a white flocculent precipitate slightly soluble in water. On heating, it melts at 1130° C. and forms crystals on cooling. Octahedral crystals of lead tungstate are prepared by fusing together sodium tungstate and lead chloride or lead sulphate. The crystals are transparent, of density 8.24, insoluble in water and nitric acid, but soluble in alkalies.

Lead paratungstate, 3PbO.7WO₃.10H₂O, is obtained as a white precipitate on adding a solution of lead nitrate to a solution of ammonium paratungstate. The double salt, 4Na₂O.PbO.12WO₃.28H₂O, corresponding to the copper salt described above, yields slender white needles.

Lead tritungstate is described by Lefort.