OP ARTS AND SCIENCES. 



109 



ing dissolves the pyrophospho-tungstate, but on cooling a pale green 

 crystalline body separates, which does not contain tungsten. The salt, 

 precipitated by amnionic chloride as above, after washing with cold 

 water and drying upon woollen paper, was analyzed : 



0.GG26 gr. lost on ignition 0.1060 gv. = IG.OO XH„ and U^O 

 0.9S66 gr. gave 0.2479 gr. PaO.Mg, = 1G.07 % F.O^ 

 0.5488 gr. " 0.0499 gr. (NIT^),^ = 9.09 % 

 0.8188 gr. " 0.G504 gr. oxides = 79.46 % WO. and P.O^. 



In determining the pliosphoric oxide, the salt was several times in 

 succession evaporated to dryness with nitric acid. 

 The analyses agree with the formula 



22 WO3 . 3 {PANa,} 6 {P20,(NH4),| 2 (KU,%0 -\- 31 aq, 



8040 



100.00 



As already stated, the salt is dissolved by a large excess of hot water 

 to a clear colorless sohition. Cupric sulphate gives in this solution a 

 pale blue crystalline precipitate of a pyrophosphate free from tungstic 

 oxide. Argentic nitrate and baric chloride give white flocky-crystal- 

 liiie precipitates. Either, therefore, the salt is decomposed by solution 

 or by the action of cupric suli)hate. 



22 : 9 : 18 Potassic Pyrophospho-tungstate. — When jiotassic bromide 

 and acetic acid are added to the .saturated solution of tungstic oxide in 

 sodic pyrophosphate, a white granular fine-grained crystalline precipi- 

 tate very slightly soluble in cold water is formed at once. For anal- 

 ysis the salt was washed upon the filter-pump with cold water, and 

 dried on woollen paper. In this salt, 



0.9440 gr. gave 0.6717 gr. oxides =71.15% WO3 and PA 

 1.3G47 gr. " 0.9721 gr. « =71.23% " " 



0.9070 gr. « 0.2015 gr. PA^gz = H.21 % PA 

 0.9817 gr. lost 0.09G0 gr. II^O = 9.78% 



