OP ARTS AND SCIENCES. 63 



ing Other saline bodies ; but as soon as the crystals are completely- 

 washed, they dissolve readily in hot water with decomposition, a beau- 

 tiful green salt crystallizing from the solution on standing. Of the 

 black crystals, 



0.4978 gr. lost with W0,Na2 0.0716 gr. = 14.38 Hp 



0.1622 gr. gave with KMuO, 0.03177 gr. VO. = 19.59% 



0.1201 gr. « " 0.02384 gr. " =19.84% 



0.1383 gr. " " 0.06032 gr. V2O5 = 43.62% 



0.1360 gr. " " 0.05892 gr. " = 43.32% 



0.5646 gr. gave 0.3035 gr. PgO.Mg, = 34.38% PA 



0.7186 gr. " 0.3876 gr. " =34.49% " 



The analyses lead to the formula 



12 Ffi, . 12 VO., . 6 Yfi, . 5 K.,0 + 40 aq, 



4991 100.00 



The sum of the three oxides FX>^ -f VO^ -|- V2O5 = 76.12, as calcu- 

 lated from the formula, and 76.51 as found from the mean of all the 

 analyses. The analyses are very difficult, partly because no perfectly 

 satisfactory method of separating phosphoric oxide from the other ox- 

 ides has yet been found, and partly because in titrating vanadic dioxide 

 by potassic hypermanganate the end reaction varies with the quantity 

 of phosphoric oxide present. It is true that this variation is usually 

 within narrow limits, but it is sometimes sufficient to affect the result 

 by as much as 0.50%. 



The beautiful crystalline green salt which is formed when the black 

 salt above described is dissolved in hot water was also analyzed. 



0.5918 gr. gave 0.3771 gr. PtClfiK, = 12.37% K.p 



0.4766 gr. lost with WO^Na^ 0.0718 gr. = 15.06% 



0.1617 gr. gave with KMnO^ 0.03405 gr. VO^ = 21.06% 

 0.1274 gr. " " 0.02708 gr. " = 21.26% 



