GIBBS. — COMPLEX INORGANIC ACIDS. 255 



A quantity of this platino-tungstate was precipitated by a solution of 

 mercurous nitrate. The fine yellow mercurous salt was well washed 

 and then decomposed by dilute chlorhydric acid, the platino-tungstate 

 being in very small excess. The clear yellow filtrate on spontaneous 

 evaporation deposited a pale yellow substance which may prove to be 

 the corresponding acid. 



30:2:15 Sodic Platino-tungstate. This salt was obtained under 

 the same conditions as the last, and formed granular efflorescent dull 

 yellowish crystals readily soluble in water. Of this salt : 



1.3231 grams gave 0.9787 gram WO3 + Pt == 73.97 per cent. 

 1.3231 grams gave 0.0510 gram platinum = 4.49 per cent PtOg. 

 1.0144 grams gave 0.0410 gram platinum = 4.70 per cent PtOg. 

 1.5776 grams lost on ignition with WO^Nag 0.2657 gram + HgO 



= 16.71 per cent. 

 1.5776 grams gave 1.1059 grams WO3 = 70.06 per cent. 

 1.3231 grams gave 0.9271 gram WO3 = 70.03 per cent. 



The analyses lead to the formula, 



30 WO3 . 2 PtOa . 15 NaoO + 89 aq., 

 which requires : 



9945 



A solution of this salt also gives white scaly crystals with potassic 

 and ammonic salts. It gives a white flocky precipitate with baric 

 chloride, and a pale yellow flocky crystalline precipitate with mercurous 

 nitrate. The compound is probably, like the last described, a double 

 salt and may have the formula, 



10 WO3 . 3 NaaO . H2O + 2 {10 WO3 . PtOg . 6 NaaO} + 88 aq. 



The solution of the salt is acid to litmus. Analysis by Dr. Morris 

 Loeb. 



30 : 1:12 Sodie Platino-tungstate. I obtained this salt by boiling 

 platinic hydrate with 10:4 sodic tungstate for some time in a plati- 

 num vessel. It formed very large masses of honey-yellow heavy 

 crystals, very easily soluble in water. Of this salt ■ 



