A Comprehensive Treatise on Inorganic and Theoretical Chemistry

CHAPTER LXXIV
PLATINUM
§ 1. The History of the Platinum Metals
PLATINUM is one member of a family of six elements called the platinum metals.
They usually occur together so that before the discovery of the companion elements,
the term platinum was applied to an alloy with platinum as the dominant metal.
The same thing is often done to-day. The platinum metals, with their sp. gr.,
are as follow :
Platinum metals
f PLATINITM (21 • 45)
/Heavy ^ IBIDIDM (22-38)
IOSMTIJM (22-47)
[PALLADIUM (11-9O)
(Light ^ RHODIUM (12-10)
\^ RUTHENIUM (12-26)
M. Berthelot * reported that an Egyptian casket, found at Thebes, and dating
from the seventh century B.C., contained platinum, or rather an alloy of platinum,
iridium, and gold. There is, however, no evidence to show that the alloy was to
the Egyptians anything more than a metal. In 1790, A. M. Cortenvois tried to
prove that the electrum—3. 23, 1—of the ancients was platinum, and
J. S. C. Schweigger, that the electrum mentioned by Pausanis, in his
TTcptrjyr)(TLs, written about the second century of our era, was also platinum.
The following passage from Pliny's Histories naturalis (34. 47), written in the first
century of our era, has also been quoted in support of the assumption that cassiteros,
or plumbum candidum, was platinum. Pliny said :
It is now known that it (cassiteros) is a production of Laisitaiiia and Qalljecia. It is a
sand found on the surface of the earth, and of a black colour, and can be detected only
by its weight. It is mingled with small pebbles, particularly in the dried beds of rivers.
The miners wash this sand, and calcine the deposit in a furnace. It is also found in the
gold mines that are known as alutice or tcilutia?, the stream of water which is passed through
them detaches certain black pebbles mottled with small white spots and of the same
weight as gold. Hence it is that they remain with gold in the baskets in which it is collected ;
and being separated in the furnace, are then molted, and become converted into album
plumbum.
F. Hoefer, and C. de Paravey suggested that the " heavy black pebbles "
contained platinum presumably because of their weight, but Pliny's ideas of
specific gravity were very vague, and in one place he even said that lead is heavier
than gold. H. Kopp, and E. IJ. Schubarth very rightly considered that these
far-fetched allusions have no connection at all with platinum. In the sixteenth
century, J. C. Scaliger, 2 writing against G. Cardanus' dictum that all metals are
fusible, said that there is a metallic substance in the mines of Mexico and Darian
(Panama) which cannot be melted in the Spanish furnaces. It is considered that
this metallic substance was probably that which was afterwards called platinum
because platinum is now known to occur in these very districts. A. N. von Scherer
also said that from a reference in B. A. Balbin's Epitome it appears as if platinum
was known to the Bohemian Jesuits at the end of the sixteenth century. Towards
the middle of the eighteenth century, A. de Ulloa accompanied the expedition sent
from France to measure the arc of the meridian at the equator, and in his account
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