OF ARTS AND SCIENCES. 97 



cipitate is thrown clown at once. The salt is very insoluble in water. 

 It was washed upon the filter-pump and dried on woollen paper for 

 analysis. In this salt, 



1.0222 gr. lost with WOiNaa 0.0975 gr. = 9.54^ 

 0.8936 gr. gave 0.0354 gr. (NH4)20 = 3.96% 

 1.1348 gr. " 0.0646 gr. PoO-Mgo =3.63% 

 1.2439 gr. " 0.0696 gr. " = 3.58% 



The determination of phosphoric oxide was made after oxidation 

 by bromine. 



The analyses agree very well with the formula 



72 M0O3 • 2 PO3H3 . 3 P2O. . 9 (NH,)20 + 38 aq, 



which requires : 



12110 100.00 



The formation of this salt may be represented by the equation 



3 {24 M0O3 . P2O5 . 3 (NH,)„0} + 2 PO.H, = 



72 M0O3 . 3 P2O, . 2 PO3H3 . 9 (NFI,)20. 



PHOSPHO-IIYPOPIIOSPIIO-TUNGSTATES. 



26 : 4 : 2 Potassic PhospJw-hypophospJw-tungstate. — "When the 

 24 : 1 phospho-tungstate of sodium is boiled with an excess of a solu- 

 tion of hypophosphorous acid and a solution of potassic bromide is 

 added to the clear pale blue filtrate, a white crystalline precipitate is 

 after a time thrown down. The salt dissolves readily in hot water to 

 a clear solution. This gives a white flocky crystalline precipitate with 

 baric chloride, a pale yellow precipitate with mercurous nitrate, and a 

 white precipitate with argentic nitrate, which on boiling becomes first 

 yellow, then brown, and finally takes a brownish color, and deposits a 

 precipitate closely resembling ferric hydrate. Cuprous sulphate is 

 without action on the solution. For analysis the fresjily formed salt 



VOL. XXI. (n. S. XIII.) 7 



