| The paratungstate, Cr2O3.7WO3.H2O, is prepared by mixing solutions of ammonium paratungstate and chromic chloride, and drying at 100° C. the resulting greyish-green precipitate; or by treating a cold solution of sodium paratungstate with violet chromic chloride. The green chromic chloride produces a basic salt. The following compounds have been described: Cr2O3.5WO3, Cr2O3.5WO3.5H2O, Cr2O3.4WO3.6H2O, Cr2O3.3WO3.3H2O, Cr2O3. 2WO3.5H2O, but these appear to be either identical with the paratungstate, or mixtures of the para- and meta-salts. |