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 usuaily 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 pure metal, and increase its hard- 
ness. A Russian 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. 
Diff. Platinum is at once distinguished by its malleability 
and extreme infusibility. 
Ovs. Platinum was first detected in 1735 in grains in 
the alluvial deposits of Choco and Barbacoa 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 plata, 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 Rita, and Santa Lucia, Brazil. It has been afforded 
most abundantly by the Urals. It occurs also on Borneo ; in 
the sands of the Rhine; in those of the river Jocky, St. 
Domingo; in traces in the United States, in North Carolina ; 
at La Frangois 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 lecalities 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 
