OP ARTS AND SCIENCES. 101 



The arsenous oxide is too low. but the sum of the arseuous and 

 tuiigstic oxides, as well as the percentages of the other coustitueuts of 

 the suits, agree well with the foruiula. 



60 : 1 : 4 : 7 Potassic Arsenuso-vhqspho-tutigstate. — When a solu- 

 tion of potassic phosphate is poured into one of sodic arsenoso-tungstate 

 as prepared by boiling arsenous oxide with 12:5 sodic tungstate, no 

 precipitate is formed ; but on adding chlorhydric acid the liquid be- 

 comes yellow, and, after standing, deposits beautiful pale yellow crys- 

 tals. For analysis these were washed with cold water and dried on 

 woollen paper. The salt is soluble in hot water, but appears to be 

 decomposed by solution. In this salt, 



1.2498 gr. gave 0.0671 gr. l^O.Mg^ = 3.43% P2O5 



1.2587 gr. " 0.0151 gr. AsaO^ by iodine = 1.20% 

 1.0348 gr. " 0.9192 gr. WO3 + P.O, = 88.81% 

 1.3143 gr. lost over a radiator 0.0787 gr. = 5.99% water. 



The analyses correspond closely to the formula 



60 WO3 . AS2O3 . 4 P0O5 . 7 K2O + 55 aq, 



which may also be written 



16337 100.00 



It is of course very possible that this may be a double salt, but there 

 are at present no data ui)on which we can base a rational distiibution 

 of the components. 



ARSENOSO-ARSENIO-TUNGSTATES. 



The salts whicli belong to this group are formed under the same 

 conditions as the corresponding arsenoso-phospho-tungstates. They 

 are in many cases highly crystalline and well defined, and appear to 

 be very numerous. 



