To
determine the cause of these great discrepancies requires most
painstaking investigation. It used to be believed that the platinum of
the graywacke behaved abnormally while the precious metals were in the
gel form in the rocks. The first one to advance this theory was
Schreiber, the discoverer of platinum in the Siegerland. He has
doubtless some justification for this assumption, because, first, the
gels have the property of appearing in finest division in the rocks,
and, second, colloidal platinum solutions are known. The question
whether a precious metal occurs as a gel can not be answered by a
chemist but rather by a petrographer, because the gel is easily
distinguished optically from crystalline bodies, and this can not be
done chemically. Schreiber was really in error when he assumed
that the difficulty in platinum chemistry had something to do with the
gel form. If platinum is in the gel form, this can work no hardship on
the chemist with the dry method, because gel is converted into the
crystalline form by great heat. As it is possible to distinguish minute
crystal fragments in the black specks, it is probable that in this case
it is not a question of gels but of crystalline structures. * * *
There
must therefore be some other reason for this discrepancy in results. It
is either an error in analytical method or the original distribution of
platinum in the rock. I am loath to admit any possibility of error in
the chemical work. I am inclined to agree with Pufahl that the
irregular distribution of the metal, in spite of the great fineness and
the most careful mixing, is accountable for incorrect averages. We are
already acquainted with similar cases. * * *
It
is, then, impossible to establish the average in this way. The
practical inference from all this is that we can only depend upon
actual production which is capable of being demonstrated on a small
scale for experimental purposes. Only the most exacting tests on
samples of 1 ton and the extraction of the contained platinum can
guard us against error.
RUSSIA.
There
is a dearth of information concerning operations in the Rus-sian
platinum fields during 1914. During ordinary years the London Mining
Journal contains a number of contributions on Russian platinum, but
very little news for 1914. Before the outbreak of the war the feeling
was strong that Russia would produce as much, if not more, platinum in
1914 than for several years, owing in part to new dredging ventures and
in part to the owners permitting more work under the leasing system.
From the published figures of production this expectation was not
realized.
