238 
Selected Articles. 
Tagil, belonging to the heirs of Nicholas Nikitisch Demidoff: 
it is found near the surface, under a layer of earth, mixed 
with a greenish sand, which evidently owes its origin to a 
mixture of hornblend, greenstone and serpentine. This sand 
contains .00025 to .00075 of crude platina ; this sometimes is 
in fine grains, sometimes in flat spangles, but it is not rare to 
find large masses. In June, 1827, one was met with that 
weighed 10 pounds 54 solotniks: in March, 1831, another 
was found weighing 19 pounds 52|- solotniks. Since then a 
fragment of 20 pounds, 24 solotniks ; another of 19 pounds 24 
solotniks, and finally, two of upwards of 13 pounds have 
been discovered. 
The crude platina of Ural closely resembles that of Ame- 
rica in its composition ; there are three different kinds, dis- 
tinguished from each other by the quantity of platina they 
contain : it is always accompanied by its usual concomitants 
namely, palladium, iridium, osmium, and rhodium. The pro- 
portions of these metals have been determined by the experi- 
ments of Berzelius. The three kinds of crude platina of Ural 
need not be described, they are designated as 1, crude platina 
from Goro Blagodat: 2d, crude platina from Tagil: 3d, os- 
mium-iridium : this last is the poorest in platina. 
Among the numerous modes proposed to reduce platina to 
a malleable state, that proposed by a French jeweller, Jean- 
netty, was for a long time exclusively made use of ; this as is 
well known, is based on the fusibility of platina when mixed 
with arsenic. Being afterwards wholly abandoned on account 
of the great danger to which it exposed the workmen, when 
used on a large scale, it was replaced by those of Breant and 
Wollaston. These two chemists were very successful for 
many years in reducing platina, but kept their processes se- 
cret, and it was not till 1828, a short time before his death, 
that Wollaston made his public. It is somewhat different 
frqm that pursued in Russia, of which, however, we have 
had no exact account until the publication of the present me- 
moir. 
The whole operation is divided into two distinct series of 
manipulations : the first designed to separate the crude plati- 
