24 PROCEEDINGS OF THE AMERICAN ACADEMY 



The salt is readily decomposed by boiling with reduction of metallic 

 gold. 



Platinum Salt. — Platinic chloride in solution precipitates the chloro- 

 nitrate almost immediately in the form of wine-yellow needles. After 

 recrystallization the salt was analyzed with the following results : — 



0-6405 gr. fused with potassio-sodic carbonate gave O-ooGl gr. silvers 

 28-00 per cent chlorine, 0-1986 gr. platinum = 31-00 per cent and 

 0-0597 gr. cobalt = 9-33 per cent. 



The platinum and cobalt were weighed together as metals after re- 

 duction by hydrogen, and the cobalt was then dissolved by long boiling 

 with nitric acid. 



The formula, Co2(NH3),o(N02)2(N03)2Cl2 + 2PtCl„ requires: — 



Bromo-nitrate of Xanthocohalt. — One molecule of bromide of 

 xanthocobalt was mixed with one of the nitrate of the same base, 

 both salts being in solution in hot water. A dark, sherry-wine col- 

 ored salt separated, after some hours, in well-defined crystals. In 

 tliis salt 



0-8925 gr. gave 0-4190 gr. SO^Co^ 17-86 per cent cobalt. 



0-7116 gr. gave 0-1244 gr. silver = 12-94 per cent bromine. 



The formula Qo.,{^^,),,{1^0.;),,{^O.^^^r^ requires 17-77 per cent 

 cobidt, and 24-09 per cent bromine. The salt was re-dissolved, and 

 allowed to crystallize a second time. In the salt thus obtained 



0-8538 gr. gave 0-3984 gr. SO^Co = 17-76 per cent cobalt. 

 0-8474 gr. gave 0-2672 gr. silver =23-62 per cent bromine. 



These results leave no doubt that a definite bromo-nitrate, analogous 

 to the chloro-nitrate, is found by direct union of the nitrate and 

 bromide. The salt appears to be, however, much less stable than the 

 corresponding chlorine salt. A portion of it was crystallized a third 

 time, and then gave 23-04 per cent of bromine, indicating the com- 

 mencement of a separation into bi'omide and nitrate. The facility with 

 which the chloro-nitrate is formed by the direct union of its constitu- 

 ents, led me to attempt the formation of other new salts by a similar 



