PLATINUM. 125 



shining. Ductile and malleable. H. =4-4*5. G. = 16-19; 

 17*108, small grains ; 17*608, a mass. Often slightly mag- 

 netic, and some masses will take up iron filings. 



Composition. Platinum is usually combined with more 

 or less of the rare metals iridium, rhodium, palladium, and 

 osmium, besides copper and iron, which give it a darker 

 color than belongs to the pue metal, and increase its hard- 

 ness. A Eussian specimen afforded, Platinum 78*9, iri- 

 dium 5*0, osmium and iridium 1*9, rhodium 0*9, palladium 

 0*3, copper 0*7, iron 11-0 = 98*75. 



Platinum is soluble in heated aqua regia. It is one of the 

 most infusible substances known, being wholly unaltered 

 before the blowpipe. It is very slightly magnetic, and this 

 quality is increased by the iron it may contain. 



Biff. Platinum is at once distinguished by its malleability 

 and extreme infusibility.. 



Obs. Platinum was first detected in 1735 in grains in 

 the alluvial deposits of Choco and Barba^oa in New Granada 

 (now U. States of Colombia), within two miles of the north- 

 west coast of South America, where it received the name 

 platina, derived from the word jjlata, meaning silver. Al- 

 though before known, an account by Ulloa, a Spanish 

 traveler in America in 1735, directed attention in Europe, 

 in 1748, to the metal. It is now obtained in Novita, and 

 at Santa Eita, and Santa Lucia, Brazil. It has been afforded 

 most abundantly by the Urals. It occurs also on Borneo ; in 

 the sands of the Ehine ; in those of the river Jocky, St. 

 Domingo ; in traces in the United States, in North Carolina ; 

 at La Francois Beauce, Canada ; and with gold near Point 

 Orford, on the coast of Northern California (probably de- 

 rived, according to W. P. Blake, from serpentine rocks) ; in 

 British Columbia. 



The Ural localities of Nischne Tagilsk and Goroblagodat 

 have afforded much the larger part of the platinum of com- 

 merce. It occurs, as elsewhere, in alluvial beds ; but the 

 courses of platiniferous alluvium have been traced to a great 

 extent up Mount La Martiane, which consists of crystalline 

 rocks, and is the origin of the detritus. One to three pounds 

 are procured from 3,700 pounds of sand. 



Though commonly in small grains, masses of considerable 

 size have occasionally been found. A mass weighing 1,088 

 grains was brought by Humboldt from South America and 

 deposited in the Berlin Museum. Its specific gravity was 



