GIBBS. — COMPLEX INORGANIC ACIDS. 257 



cold, and very readily in hot water. The solution gives with argentic 

 nitrate a pale yellow flocky precipitate which becomes crystalline on 

 standing. With mercurous, mercuric, and thallous nitrates it gives 

 pale yellow flocky precipitates not distinctly crystalline and settling 

 quickly. With nitrate of croceo-cobalt the solution gives a beautiful 

 bright yellow crystalline salt. The formula of the ammonium salt is, 



8 M0O3 . 2 PtOo. 3(NH,)20 + 12 aq., 



as the following analyses show : 



1.7831 grams gave 0.3554 gram Pt = 19.94% = 23.21% Pt02. 



0.5425 gram gave 0.1075 gram Pt = 19.82% = 23.09% PtOg. 



0.4354 gram gave 0.0868 gram Pt = 19.92% = 23.15% PtOg. 



1.0407 grams gave 0.0535 gram NHg =z 5.14%. 



0.5149 gram gave 0.0405 gram NH3 = 5.14%. 



0.5878 gram gave 0.0459 gram NHg = 5.14%. 



1.2015 grams lost on ignition with WO^ Nag 0.2663 gram 22.17% 



H^O + NH3 + O. 

 0.8368 gram lost on ignition with WO^ 0.1876 gram 22.42% HgO + 



Other salts of this series may be prepared from the ammonium salt 

 by precipitating its solution with mercurous nitrate and decomposing 

 the well washed mercurous salt by solutions of the chlorides of other 

 metals. 



4:2:2 Platino-molyhdnte of Ammonium. The solution from 

 which the yellow ammonium salt first described separated by crystalli- 

 zation gave on evaporation a dark colored liquid over a heavy oily 

 deep brown-red substance. This last was washed with a little ice-cold 

 water and gradually dried to a transparent dark brown-red ma§s which 

 broke up into clean sharp brilliant fragments. Of this salt : 



0.4502 gram lost on careful heating 0.1297 gram = 28.81% HoO 



+ NH3 -f O. 

 0.4502 gram gave 0.1226 gram platinum — 31.63% PtOo. 

 0.5398 gram gave 0.0402 gram (NH,).,0 = 4.91 % NHg. 

 0.4917 gram gave 0.0369 gram (NHJ2O = 4.87% NHg. 



VOL. XXX. (n. S. XXII.) 17 



