platina
n . 白金;铂
白金;铂
Platina \
Plat "
i *
na \,
n . [
Sp .
or NL .
See {
Platinum }.] (
Chem .)
Platinum .
[
1913 Webster ]
{
Platina mohr },
platinum black .
{
Platina yellow },
a pigment prepared from platinum .
[
1913 Webster ]
Platinum \
Plat "
i *
num \,
n . [
NL .,
fr .
Sp .
platina ,
from plata silver ,
LL .
plata a thin plate of metal .
See {
Plate },
and cf .
{
Platina }.] (
Chem .)
A metallic element of atomic number 78 ,
one of the noble metals ,
classed with silver and gold as a precious metal ,
occurring native or alloyed with other metals and also as the platinum arsenide (
sperrylite ).
It is a heavy tin -
white metal which is ductile and malleable ,
but very infusible (
melting point 1772 [
deg ]
C ),
and characterized by its resistance to strong chemical reagents .
It is used for crucibles in laboratory operations ,
as a catalyst ,
in jewelry ,
for stills for sulphuric acid ,
rarely for coin ,
and in the form of foil and wire for many purposes .
Specific gravity 21 .
5 .
Atomic weight 195 .
1 .
Symbol Pt .
Formerly called {
platina }.
[
1913 Webster PJC ]
{
Platinum black } (
Chem .),
a soft ,
dull black powder ,
consisting of finely divided metallic platinum obtained by reduction and precipitation from its solutions .
It absorbs oxygen to a high degree ,
and is employed as an oxidizer .
{
Platinum lamp } (
Elec .),
a kind of incandescent lamp of which the luminous medium is platinum .
See under {
Incandescent }.
{
Platinum metals } (
Chem .),
the group of metallic elements which in their chemical and physical properties resemble platinum .
These consist of the light platinum group ,
viz .,
rhodium ,
ruthenium ,
and palladium ,
whose specific gravities are about 12 ;
and the heavy platinum group ,
viz .,
osmium ,
iridium ,
and platinum ,
whose specific gravities are over 21 .
{
Platinum sponge } (
Chem .),
metallic platinum in a gray ,
porous ,
spongy form ,
obtained by reducing the double chloride of platinum and ammonium .
It absorbs oxygen ,
hydrogen ,
and certain other gases ,
to a high degree ,
and is employed as an agent in oxidizing .
[
1913 Webster ]
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