OF ARTS AND SCIENCES. 2^7 



recrystallized. When heated, the salt swells up very much, and 

 turns black, looking like coke. Of this salt, — 



1.0070 gr. lost on ignition with WO^Naj 0.1310 gr. = 13.00% 

 0.9716 gr. " " " " 0.1280 gr. = 13.17% 



1.2449 gr. " " " " 0.1637 gr. = 13.16% 



0.9682 gr. gave 0.6534 gr. M0O3 + V.O, = 67.48% 



1.0162 gr. " 0.3029 gr. SO.Ba ' = 19.56% 



1.0343 gr. " 0.3072 gr. " = 19.50% 



1.0190 gr. " 0.3023 gr. " * = 19.48% 



1.0937 gr. " 0.0998 gr. V.O^ = 9.12% 



1.4395 gr. " 0.1356 gr. " ^ = 9.37% 



These analyses lead to the formula 



16 M0O3 • 2 Vp, . 5 BaO + 29 aq, 



or. 



8 M0O3 . VA . 3 BaO + 8 M0O3 . V^O^ . 2 BaO . 11,0 -f 28 aq, 

 which requires : — 



3955 100.00 



The salt is therefore to be regarded as the acid salt of the eight- 

 atom series, and belongs to a type of which several examples have 

 been o-iven among the phospho-tungstates and phospho-molybdates. 

 It may also be considered as an acid sixteen-atom salt, upon the view 

 which I have siio-gested in another place as at least possibly correct 

 The 16:2 barium salt is also formed when baric chloride is added to 

 a solution of the 6 : 1 vanadio-molybdate of ammonium already de- 

 scribed. The last-named salt is therefore formed when vanadic 

 pentoxide is dissolved in acid ammonic molybdate, as well as when 

 molybdic oxide is dissolved in ammonic meta-vanadate. In the 

 double decomposition with baric chloride at least three molecules of 

 the 6 : 1 ammonium salt must take part. The barium salt is nearly 

 insoluble in cold water, but is soluble in much hot water, with 

 partial decomposition and deposition of baric molybdate. The solu- 

 tion in cold water reddens litmus strongly : it gives with argentic 



