lutions in the presence of an alkaline carbonate and a large
excess of carbonic acid, both of which are common constituents of
mineral waters, especially in Victoria. This is true of chloride of
gold, and if the sulphide is required in solution, it is only necessary
to charge the solution with an excess of sulphuretted hydrogen. In this
matter both sulphides may be retained in the same solution, depositing
gradually with the escape of the carbonic acid."
Pyritic lodes usually contain a considerable proportion of calcareous
matter, mostly carbonates, and consequently it appears not improbable
that the gold may remain in some instances as a sulphide, particularly
in samples of pyrites, in which it cannot be detected even by the
microscope until by calcination the iron sulphide is changed to an
oxide, wherein the gold may be seen in minute metallic specks. The whole
subject is full of interest, and careful scientific investigation may
lead to astonishing results.
CHAPTER V
THE GENESIOLOGY OF GOLD--AURIFEROUS DRIFTS
Having considered the origin of auriferous lodes, and the mode by which
in all probability the gold was conveyed to them and deposited as a
metal, it is necessary also to inquire into the derivation of the gold
of our auriferous drifts, and the reasons for its occurrence therein.
When quite a lad on the Victorian alluvial fields, I frequently heard
old diggers assert that gold grew in the drifts where found. At the time
we understood this to mean that it grew like potatoes; and, although not
prepared with a scientific argument to prove that such was not so, the
idea was generally laughed at. I have lived to learn that these old
hard-heads were nearer the truth than possibly they clearly realised,
and that gold does actually grow or agglomerate; and, indeed, is
probably even now thus growing, though it is likely that the chemical
and electric action in the mineral waters flowing through the drifts is
not in this age nearly so active as formerly.
Most boys have tried the experiment of dipping a clean-bladed knife into
sulphate of copper, and so depositing on the steel a film of copper,
which adheres closely until worn away. This is a simple demonstration
of a hydro-metallurgical process, though probably young hopeful is not
aware of the fact; and it is really by an enlargement of this process
that our beautiful and artistic gold-and silver-plated ware is produced.
In the great laboratory of Natur
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