OF ARTS AND SCIENCES. 263 



The analyses correspond, though not very closely, to the formula 

 7W03.VA.PA-3K,0+llaq, 

 which requires : — 



2429 100.00 



According to the view which I have taken as to the function of 

 V^Og in this class of compounds, the 7:1:1 potassic salt helongs to 

 the type 



8 WO3 . P,0, . 3 K,0, 



VgOj . O3 taking the place of one molecule of WO3. A much more 

 extended study will be necessary to test this hypothesis. The vanadio- 

 phospho-tungstates are probably numerous, and from their great beauty, 

 as well as from their theoretic interest, form an attractive subject for 

 investigation. The following notes may serve to furnish fresh points 

 of departure. When the solution of vanadio-tungstate of sodium (ob- 

 tained by boiling 12:5 acid sodic tungstate with the mixed oxides of 

 vanadium and oxidizing completely with bromine) is mixed with a so- 

 lution of hydro-disodic phosphate, no apparent action takes place ; but 

 on boiling, the orange solution takes a deep red color, and soon deposits 

 splendid ruby-red crystals in quantity. These crystals are decomposed 

 in part even by cold water, which appears to separate phosphoric acid 

 or sodic phosphate. An orange-colored sodium salt then separates. 

 Almost exactly the same results are obtained when a solution of 

 vanadio-tungstate of ammonium is boiled with a solution of ammonic 

 phosphate. The liquid takes a beautiful deep red tint, and soon de- 

 posits splendid ruby-red crystals. The solution of the sodium salt, 

 after a day or two, gives with one of trimethjl-ammonium chloride, 

 N(CH3)3HC1, very fine granular ruby-red crystals. Of these crystals, 



0.9752 gr. gave 0.8549 gr. mixed oxides = 87.66^ 

 1.1543 gr. " 0.0631 gr. VA = 5A6% 



1.0061 gr. " 0.0552 gr. p"p^Mg2 = 3.51% 



The loss corresponding to water and trimethyl-ammonium oxide is 

 12.34%. The ratio of the three oxides, WO3, V^O^, and T./)^, is 



