OF ARTS AND SCIENCES. 115 



OKTHOMETAPHOSPHO-TUNGSTATES. 



A single salt of this series will be sufficient to establish the existence 

 of compounds into which two different modifications of phosphoric 

 acid enter, to a certain extent at least preserving their peculiar 

 characteristics. 



22 : 6 : 11 : 7 Potassio-sodie Orthometaplwspho-tungstate. — When 

 24 : 1 sodic phospho-tungstate is boiled with a solution of sodic mono- 

 metaphosphate, FOsNa, the salt dissolves readily to a clear liquid. 

 Potassic bromide gives a white precipitate in this solution. After 

 filtering and washing with cold water, a white gelatinous mass remains 

 upon the filter, but slightly soluble in water. Of this salt, 



1.2008 gr. gave 0.8728 gr. oxides = 72.68% 



1.5959 gr. " 0.1611 gr. " =72.76% 



1.3558 gr. " 0.2220 gr. PaO.Mga = 10.47% P2O5 



0.8822 gr. " 0.5774 gr. Ptcl^Ka = 12.70% \lf> 



1.4517 gr. lost on ignition with WOiNag 0.1349 gr. = 9.29% 



The analyses correspond with the formula 



22 WO3 . 6 P2O5 . 11 K2O . 7 Na^O + 42 aq, 



8184 100.00 



The solution of this salt in chlorhydiic acid gives, with magnesia- 

 mixture and ammonia, a jjrecipitate whicli appears to contain am- 

 monio-magnesic phosphate and magnesic metaphosphate. It is of 

 course possible that a portion of the raetaphosphoric acid may have 

 been converted into orthophosphoric acid by the act of solution in 

 ohlorhydric acid. I know of no method by which really reliable deter- 

 minations, either qualitative or quantitative, can be made in compounds 

 of this kind. In the analysis above, the salt was evaporated several 

 times with strong sulphuric acid, and the phosphoric acid tlien deter- 

 mined with magnesia-mixture. The total quantity of base in the salt 



