of the Plat'ina found in Russia. 287 



The three masses obtained, steeped in water, disengaged a 

 ilecided smell of osmium, and deposited a black powderfxhe 

 alkaline solution, filtered and saturated by nitric acid, gave a 

 smell of osmium ; and there were formed light greenish "flakes, 

 which M.Vauquelin, in his excellent researches, ascertained to 

 be a mixture of iridium and of titanium : the same solution be- 

 coming yellow as the saturation took place, indicated some 

 traces of chrome. This solution, supersaturated with nitric 

 acid and distilled, gave a white liquor having a strono- smell 

 ot osmium, and acquiring a blue colour by the addition of 

 some drops of tincture of galls. It is not to be doubted then 

 that it was osmium ; the black powder dissolved in the cold 

 m weak hydrochloric acid, giving it a greenish colour which 

 became red by heat. This solution lost its colour by the ad- 

 dition of some drops of protosulphate of iron. From these 

 properties the presence of iridium cannot be mistaken. 



Thus the portion insoluble in acids forms a quarter of the 

 rough ore not attracted by the magnet ; and I consider that it 

 IS composed (in five parts) of three parts of iridium and of 

 one part and a half of osmium. 



After the examination of the residuum insoluble in aqua-regia, 

 I occupied myself in investigating the nature of the substances 

 which this mixture of acids had dissolved. I evaporated the 

 solution to dryness and dissolved the residuum in water, adding 

 as much hydrochloric acid as was necessary to render the so- 

 lution complete. I poured hydrochlorate of ammonia into 

 the solution until it no longer formed a precipitate there. The 

 precipitate havhig subsided, I decanted the supernatant liquor, 

 which contained but a little iron, and which' did not show any 

 trace of palladium. The precipitate formed by the liydro- 

 chlorate of ammonia was of a chamois colour, which indicates 

 a mixture in the platina of a small quantity of iridium. I 

 dried and calcined it to obtain the platina from it ; but in- 

 stead of having it in the form of sponge or of metallic powder, 

 there only remained a red-brown oxide similar to the oxide 

 of iron. This residuum, of the weight of 15 centigrammes, 

 dissolved indeed in the hydrochloric acid like this metallic 

 oxide, and only left four parts of jwwder of platina soluble in 

 aqua-regia, which was now precipitated wholly, and in a yellow 

 triple salt, by solution of hydrochlorate of ammonia. The 

 muriatic solution contained only iron, for the precipitate which 

 the triple prussiate of potash formed in it was of the purest 

 blue. The precipitation of this iron took place in the same 

 time with that of a less quantity of platina by sal ammoniac, 

 leaving me in some doul)t of its purity. ' I precipitated 

 it by an excess of iunnionia, which preserved a very sensible 



blueish 



