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XL VI. Examination of the Platina found in Russia. By' 

 M. Laugier*. 



A NOTE translated from the German Gazette of Peters- 

 -^^ burg (October 1823), relative to the voyage made by 

 M. Soimonof the senator and Dr. Fuchs to the Oural moun- 

 tains, to examine the gold mines which have been discovered 

 there, states that platina has also been found in them. 



" 1 had made two years ago," says M. de Humboldt, in a 

 letter which accompanied the specimens of which we are speak- 

 ing, " fruitless attempts to procure tliis Russian platina : I have 

 succeeded at last through the goodness of M. the Baron de Schil- 

 ling. It is curious to see that the platina of the Oural is found in 

 the midst of fragments of diorite(grunstein, or an intimate mix- 

 ture of feldspar and amphibole), like the platina of Choco. The 

 grains, which are rich in osmium and iridium, appear to me geo- 

 logically interesting. At Choco each grain contains all the me- 

 tals ; in the Brazils alone, grains of palladium are found mixed 

 with grains of platina, with grains of gold, and with diamonds," 

 &c. 



Two specimens of the ores of })latina from Russia were 

 transmitted to me by M. de Humboldt : one, of platina found 

 in the auriferous sands of Kuschwa, 250 wersts from Eka- 

 terinebourg ; the other, in larger grains, considered as a com- 

 bination of iridium and osmium, taken from the estate of the 

 merchant Rastorgujers, in the Oural, near Ekaterinebourg. 



The first, formed of very small laminae of a grayish white, has 

 the appearance of the platina of Choco, but is less bright, and 

 more of the colour of lead. 



The specimen weighed but 9 decigrammes : the magnet 

 does not act on any one of the grains which compose it. 

 Four decigrammes were perfectly dissolved in hot aqua-regia: 

 there only remained some small white brilliant laminae, hardly 

 forming half a centigranmie, or the 80th of the quantity sub- 

 mitted to the trial. The solution, eva})orated nearly to dry- 

 ness to drive away the excess of acid, was diluted with water and 

 mixed with a quantity of hydrochlorate of ammonia sufficient 

 to precipitate all the jilatina. The precipitate, of a fine dark- 

 yellow, left, after washing and calcining, 0'27 of platina in the 

 spongy state. The supernatant liquor not having yielded a 

 trijjle salt of platina by evaporation, I diluted it with water 

 and poured an excess of ammonia into it. The precipitate 

 which resulted from it, washed and calcincil, weighed 9 })arts. 



It easily dissolved in hydrochloric acid, exccpling a very 

 small quantity (jf a black powdei', which would not dissolve 



* I'Vitin Anmihs ilc C7iiiiiit , torn. xxix. p- ~89. 



even 



