Evening star. [volume] (Washington, D.C.) 1854-1972, 1903-04-02
SOME PRECIOUS METALS.
The "Noble' Metals-The Formation OF
Platinum.

From Chambers Journal.
On the slopes of the Ural mountains and
in Brazil, California, Australia, Cahaoa
and many other countries a peculiar sup
stance known as native platinum is found
This is an alloy Of the metals platinum
palladium, iridium, osmium, rhodlum ana
ruthen1um together with a little gold and
iron. All Of these except the last mention
ed are the noble metals. They do not
tarnish in the air, and are not soluble IN
any single acid. Their values per ounce
are: Platinum, 95s. palladium. 1905; os-
mi,in, zoos; iridium, 250s.; rhodium, 4OOs. !;
and ruthenium, 450s. The most plenti1ui
metal occurring in native platinum Is that
from which it takes its name. This metal
is of a grayish color, and, with one excep-
ton, is the heaviest substance known. us
fusing point is extremely high, and this
property. together from its freedom from
furnishing, causes it to be largely used for
the manufacture Of crucibleS and other
vessels required by scientists to stand
very high temperature. 1t is also some
times used as a substitute for gold in pho
Biography. and when deposited in a thin film
on the interior of the tubes OF telescopes II
forms a dead-black surface, which prevents
the light from being reflected by the polish
ed sides. The demand for platinum largely
exceeds the supply; hence the metal Is
yearly advancing In price.
Palladium Is of the lustrous white color
It Is the most easily fused OF the metals
found in platinum ore and can even De
yotalized A curious quality which TINS
metal possesses is that when heated to
redness it is porous to hydrogen gas, allow
ing it to pass through somewhat IN the
same manner that blotting paper permits
color of palladium and its freedom from
furnishing render it useful for making
scales and division marks on scientific IN
struments A mixture of this metal with
teeth Osmtum is a metal which possesses
two remarkable properties; 1t is the most
refractory of the metals, resisting 1uslon
al the most intense heat and 1t Is also the
twenty-five and a half times heavier than
water Together with iridium, it occurs
principally in a peculiar variety OF natlVe
platinum called osmiridium. This mineral
differs from ordinary platinum ore IN ina.
it contains a larger proportion of osmlum
and iridium than platinum. Osmlrldlum IS
found in small particles, varying In weight
from one-sixth to oEe-third OF a gram
These particles are extremely marc anu are are
used for pointing non-wearlng pens. For
this purpose as much thirty ounces or
osmiridium are used annually IN the onlted
States This mineral is a source OF much
trouble to the officials Of the Russian mint
who find it extremely difficult to separate
small particles of it from the. gold used for
coinage.
Metallic iridium possesses white steel
like appearance. The knife edges OF dell
cate balances and other bearings which re-
uuire extreme hardness are often made of
It. Ans alloy of 10 per cent iridium and 80
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 interna-
tional metric bureau at Paris, Is made.
Rhodium and ruthenium are metals of little
practical use. The former occurs In platf-
mum ore to the extent OF to per cent
The latter is found only in osmirdium
and averages about 5 per cent of that
mineral These six metals have been treat
ed of together because Of their resemblance
to each other; but the metal Whlch ranks
next to platinum in price is CHROMIUM
which occurs in hyacinth and some other
rare minerals, and is worth about f6 per
ounce Titanum and uranium, whose ores
are found In Cornwall and some other
nlaces. are each worth &c los. per ounce.
Uranium is remarkable for its high atomic
weight the heaviest known.