50 PROCEEDINGS OF THE AMERICAN ACADEMY 



III. 



RESEARCHES ON THE COMPLEX INORGANIC ACIDS. 

 By Wolcott Gibbs, M. D., 



Eumford Professor in Harvard University. 

 (Continued from Vol. XVIII. p. 274.) 



Communicated June 10, 1885. 



PHO SPHO- VANADATES. 



The existence of a compound of phosphoric and vanadic pentoxides 

 appears to have been first recognized by Berzelius, who regarded it 

 simply as a phosphate of vanadic oxide and ascribed to it the formula 

 V2O3 . 3 P.,0- , vanadium being then sujjposed to have the atomic 

 weight 61.5, so that its highest oxide would have the formula YJd^. 

 Berzelius describes the supposed salt as lemon-yellow, crystalline, and 

 slowly soluble in water. By dissolving together sodic phosphate and 

 vanadate, adding nitric acid and evaporating at a gentle heat, he obtained 

 a colorless solution which yielded a lemon-yellow salt in large grains 

 made up of fine crystalline needles. For this compound, which he 

 called phosphate of sodium and vanadic acid, he gave no formula. I 

 shall endeavor to show that phosphoric and vanadic oxides unite in 

 various proportions to form well-defined complex inorganic acids, 

 strictly comparable with those which contain phosphoric and molybdic 

 or tungstic oxides. 



Phospho-vanadates are formed Avhen alkaline vanadates are heated 

 in contact with free phosphoric acid ; when solutions of an alkaline 

 phosphate are digested with vanadic acid or an acid vanadate ; and 

 when alkaline phosphates and vanadates are mixed in presence of a 

 free acid, the conditions being, so far as I have observed, perfectly 

 analogous to those which determine the formation of phospho-tungstates 

 and phospho-molybdates. Phospho-vanadates of the heavy metallic 

 oxides are formed when the divanadates of these oxides are boiled with 

 solutions of alkaline phosphates or with phosphoric acid, and also when 



