GIBBS. — COMPLEX INORGANIC ACIDS. 



259 



0.6459 gram lost on ignition with WO^Na^ 0.0447 gram = 6.92% 



O + H2O = 6.61 H2O. 

 1.2241 grams lost on ignition with WO^Na^ 0.0872 gram = 7.12% 

 O + H2O = 6.81 H2O. 

 The analyses lead to the formula, 



60 M0O3 . Pt02 . 10 K2O + 40 aq., 

 which may be written provisionally as 



1 2 M0O3 . PtOs . 2 ICO . 4 HoO + 4 {1 2 M0O3 . 2 Kp . 3 H^O} + 24 aq. 

 The formula requires : 



Calculated. Found. 



60 M0O3 8640 82.04 81.85 



Pto/ 226.5 2.16 2.20 



10 KOo" 994 8.97 9.24 



40 H26 720 6.83 6.61 6.81 



10530.5 100.00 



This salt is readily soluble in hot water without apparent decompo- 

 sition. It gives a very pale yellow crystalline precipitate with argentic 

 nitrate and a pale greenish blue precipitate with cupric sulphate, which 

 is soluble in an excess of this last. 



Rosenheim has recently described * another platind-tungstate with 

 the empirical formula, 



7 WO3 . 2 PtO. . 5 NaoO + 35 aq., 

 and regards it as a double salt, 



7 AVO3 . 3 NaoO + 2 {PtO., . Na^O} + 35 aq. 



This salt was obtained by boiling normal sodic tungstate, WO^Naj, 

 in concentrated solution with platinic hydrate, and presented small 

 yellow needles which could not be recrystallized without decomposition. 

 He did not succeed in obtaining platino-tungstates by boiling platinic 

 hydrate with various meta-tungstates, and suggests that the three salts 

 which I described in my preliminary notice were mixtures of meta- 

 tungstates (para-tungstates) and platinic oxide. They were, on the 

 contrary, perfectly well defined and crystallized, as were also the 

 platino-tungstates and platino-molybdates described in this paper. 

 Further investigation will probably show that a number of other salts 

 can be obtained by the method which I have described in which the 



* Berichte der deutschen chera. Gesellschaft, XXIV. 2397. 



