276 Notice of some Recent [April 



of osmium, which acts upon the eyes. It is found in the 

 platiniferous sand of Nischne Tagil. It is never associated 

 with gold. 



These two combinations of osmium and iridium, possessing 

 the same shape, G. Rose considers that the idea of the 

 isomorphism of the two metals is confirmed. The Nischne 

 Tagil variety, which contains more osmium than that of 

 Newiansk, having a higher specific gravity, it follows that 

 osmium is heavier than iridium. Osmium ought then to 

 have a higher specific gravity than 21*118. Hence, it is 

 obvious that Berzelius' sp. gr. 10 is quite erroneous. 

 ( Poggendorff Ann. xxix. 452.) 



30. Native iridium has been found at Nischne Tagil, ac- 

 companied with gold and platinum. It is in grains of the 

 colour of silver, verging towards yellow, possessing a strong 

 metallic lustre, and is extremely hard. Sp. gr. 23*5— 23*6. 

 Insoluble in acids. It is combined with some osmium, and 

 may be easily fused. ( Breithaupt in Schweigg Journ. 1833.J 



31. Chemical composition of Native Gold, particularly 

 Uralian Gold. — Gold is never found in the earth in a pure 

 state, but is always combined with more or less silver. 



Fordyce examined a specimen from Konsberg, in Norway, 

 which consisted of 28 gold, 72 silver in the 100 parts. 

 Klaproth obtained gold from Schlangenberg in the Altai, 

 64 gold, 36 silver ; and Lampadius, from an unknown lo- 

 cality, procured 96*6 gold, the remainder being silver and 

 iron. Boussingault analyzed gold from different places in 

 Colombia, and found it combined with silver in variable 

 quantities, but always in definite proportions, viz. : one 

 atom of silver with 2, 3, 4, 5, 6, 8, and 12 atoms gold. 

 (Ann. de Chimie, xxiv. and xlv.) G. Rose, while travelling 

 in Siberia with Baron Homboldt, made a collection of gold 

 ores for the purpose of determining the truth of the French 

 chemist's position. 



In the Uralian Mountains, gold is found in rocks and 

 distributed among sand. Previous to 1819, it was extracted 

 from rock veins, but after this period, the discovery of sand 

 containing it occasioned the abandonment of working the 

 rock mines. Gold in rocks is found always in quartzose 

 veins ; at Beresow, occurring in the form of crystals, and at 

 Newiansk, in plates, while at Czarewo Alexandrowsk, pieces 

 are met with which weigh from 13 to 24 livres, (18 lbs. to 



