tungstate

— PARATUNGSTATES. A number of acid tungstates have been isolated, the composition of which is expressed by one of the formulæ 3RO.7WO₃ or 5RO.12WO₃. The former formula was given by Lotz (A. 91, 49) and Scheibler (J. pr. 83, 273) ; the latter formula by Laurent (A. Ch. [3] 21, 54) and Marignac (A. Ch. [3] 69, 5). The two formulæ represent salts of almost identical composition, and no way has been found of deciding which formula is the better (cf. Knorre, J. pr. [2] 27, 83). The acid tungstates of this series are more easily formed and crystallise better than the other acid salts ; they are generally called paratungstates, following the suggestion made by Marignac.