260 PROCEEDINGS OF THE AMERICAN ACADEMY 



all the phospho-tungstates and phospho-molybdates as now received 

 should be doubled, we should write the above formula 



16 WO3 . 2 V2O2.O3.V2O5. PA • 5 (NH,)20 . H2O + 36 aq; 

 corresponding to 



16 WO3 . 2 P,A • 5 (NHJ2O . H2O. 



I consider this view of the subject as most probable in the present 

 state of our knowledije. 



60 : 3 : 2 Scries. — When the 20 : 1 : 6 baric phospho-tungstate 

 already described is boiled with vanadic hydrate, V0(0Ii)3, the acid 

 dissolves readily, and a beautiful orange-red solution is formed. On 

 cooling, a salt sejaarates in octahedral crystals, which have a very fine 

 aurora-red color. The crystals dissolve rather easily in hot water, but 

 are at the same time decomposed. A brownish orange salt then sepa- 

 rates in distinct crystals, together with a white powder. The two can 

 be separated mechanically. The mother liquor of the aurora-red salt 

 yields on evaporation large dark-red crystals. Of the aurora-red salt, — 



0.41 65 gr. lost on ignition with WO^Na^ 0.0540 gr. = 12.96% 



1.1550 gr. " " " " 0.1500 gr. = 12.98% 



0.8819 gr. gave of mixed oxides 0.6474 gr. = 73.41% 



1.4699 gr. " " " 1.0784 gr. = 73.37% 



1.5188 gr. « " « 1.1145 gr. = 73.38% 



1.5188 gr. " of P^O-Mg, 0.0508 gr. = 2.14% P2O5 



1.0522 gr. " of mixed oxides 0.7709 gr. = 73.26% 



1.0522 gr. " ofP.A-Mg2 0.0380 gr. = 2.31% P2O5 



1.3324 gr. " of V^ by titrition 0.0258 gr. = 1.93% 



0.2693 gr. " " " 0.0051 gr. = 1.87% 



The analyses correspond to the formula 



60 WO3 . 3 P._,0, . 2 V2O5 . 18 BaO + 144 aq, 



which requires : — 



Calc'd. Mean. 



69.14 



The baric oxide was determined by difference. In all determina- 

 tions of the three acid oxides it was found necessary to ignite finally 



