The star. (Reynoldsville, Pa.) 1892-1946, 1903-10-21
NATIVE PLATINUM.
The "Noble" Metals Extracted From
This Peculiar Substance.

THIS Pecuitnr SuD4tnnce.
On the slopes of the Ural mountains
and In Brazil, California, Australia,
Canada and many other countries q pc
cullar substance known as native plati-
mum IL found. This Is an alloy of the
metals platinum, palladium, iridium,
osmium, rhodum and ruthenium, to-
gether with a little gold and iron. All
Of these except the last mentioned are
the noble" metals. They do not tar.
nish I'm the air and are not soluble In
any single acid. The most plentiful
metal occurring I'm native platinum IL
that from which IL takes It's name.
This metal Is of grayish color and
with one exception Is the heaviest sub
stance known. Its fuslng point Is ex-
tremely high. and this property, to-
gether with its freedom from tnrnish-
Ing. causes Il TO be largely used for the
manufacture of crucibles and other
vessels required by scientists TO stand
a very high temperature. 1t Is also
sometimes used as n substitute for gold
in photography, and when deposited In
n thin film on the interior of the tubes
of telescopes 1t forms a dead black
surface, which prevents the light from
being reflected by the polished sides.
Palladium Is of lustrous white
color. II is the most easily fused of
the metals found in platinum ore. and
can even be volatilized. A curious
quality which this metal possesses is
that when heated TO redness 1t Is
porous to hydrogen gas, allowing 1t to
pass through somewhat In the same
manner that blotting paper permits the
passage of water. The sllvery white
color of palladium and its freedom
from furnishing render II useful for
making scales ana division marks on
scientific instruments. a mixture of
this metal with mercury Is sometimes
used for filling teeth. Osmium Is
metal which possesses two remarkable
properties-it Is the most refractory
of the metals, resisting fusion at the
most intense heat and II Is also the
heaviest substance known, being twen-
ty-two and half times heavier than
water. Together with iridium, 1t oc-
ours principally In Il peculiar variety OF
native platinum called osmiridium.
This mineral differs from ordinary
platinum ore I'm that It contains
larger proportion of osmlum and irid-
ium thnn platinum. Osmiridium Is
found In small particles. varying In
weight from one-slxth to one-third OF
n grain. These particles are extremely
hard and are used for pointing non
wearing pens.
Metallic iridium possesses n white
steel-like appearance. The knife edges
of delicate balances and other bearings
which require extreme hardness are
often made of 1t. An alloy of 10 per
cent iridium and 90 per cent platinum
has been found to be very little affected
In volume by changes of temperature
and Is the substance of which the
standard meter kept In the internation-
nj metric bureau at Paris Is made.
Rhodium and ruthenium are metals OF
little practical use. The former occurs
in platinum ore to the extent of to
per cent The latter Is found only In
osmiridium and averages about per
cent of that mineral. The metal which
ranks next to platinum in price Is zir-
conlum. which occurs In hyacinth and
some other rare minerals. Uranium Is
remarkable for its high atomic weight,
the heaviest known.-Chambers Jour.
nal