GIBBS. — COMPLEX INORGANIC ACIDS, 281 



5222 100.00 



The only 20 : 1 phospho-tungstate which I have hitherto described * 

 contained 6 molecules of base (BaO), and perhaps the new salt 

 should be written 20 WO3 . P2O5 . Na^O . 5 H2O + 16 aq. With re- 

 spect to its formation with the propoitions given, I may remark that 

 1 have in repeated trials failed to obtain the salt 



24 WO3 . P2O5 . 2 NaoO + 27 aq. 



by mixing sodic tungstate and phosphate in the exact theoretical pro- 

 portions and adding chlorhydric acid to the mixed solutions. The 

 quantity of phosphate necessary to be added is much more than one 

 molecule for twelve molecules of the tungstate. This remark appears 

 to have been made by other chemists also. 



Kehrmann t has recently described phospho-tungstates which come 

 under the general formula 18 WO3 . P2O5 . 3 RO, the salts being 



18 WO3 . P2O5 . 3 K2O + 14 aq., and 18 WO^ . PA • 3 (NHJO -f 14 aq. 



He gives to the acid the name " Phospholuteo-wolframsaure " ; but 

 though there is little doubt that there is here a hitherto undescribed 

 series, the analyses are not satisfactory. 



In another part of this paper I have described three salts of a 

 phosphotungstic acid which would have the formula, 



18 WO3 . P2O5 . 6 H2O, 



the salts themselves having respectively the formulas, 



18 WO3 , P2O5 . 6 K3O + 23 aq. ; 18 WO. . P2O5 . 6 K^O -F 30 aq. ; 



and 18 WO3 . P2O5 . K2O . 5 H.^O + 14 aq. 



These salts are however colorless, and if we admit the accuracy of 

 Kehrmann's formulas, there must be two isomeric series. Kehrmann 

 appears to have been wholly unacquainted with my work. 



Experiments to determine the relations of WS4K2. M0S4K2, and 

 WS2O2K2, to phosphates and arsenates have not led to definite results, 



* Proceedings of the American Academy, XVI. 127, and Am. Chemical 

 Journal, II. 282. 



t Zeitschrift fiir anorganische Chemie, IV. 138, 386. 



