Getting Gold: A Practical Treatise for Prospectors, Miners and StudentsJohnson, J. C. F. (Joseph Colin Francis)
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Getting Gold: A Practical Treatise for Prospectors, Miners and Students
Johnson, J. C. F. (Joseph Colin Francis)
Gold mines and mining
To make an amalgamating assay that will prove the amount of gold which
can be got from a ton of your lode, take a number of samples from
different parts, both length and breadth. The drillings from the
blasting bore-holes collected make the best test. When finely triturated
weigh off one or two pounds, place in a black iron pan (it must not be
tinned), with 4 ozs. of mercury, 4 ozs. salt, 4 ozs. soda, and about
half a gallon of boiling water; then, with a stick, stir the pulp
constantly, occasionally swirling the dish as in panning off, till you
feel certain that every particle of the gangue has come in contact with
the mercury; then carefully pan off into another dish so as to lose no
mercury. Having got your amalgam clean squeeze it through a piece of
chamois leather, though a good quality of new calico previously wetted
will do as well. The resulting pill of hard amalgam can then be wrapped
in a piece of brown paper, placed on an old shovel, and the mercury
driven off over a hot fire; or a clay tobacco pipe, the mouth being
stopped with clay, makes a good retort (see "Rules of Thumb," pipe and
potato retorting). The residue will be retorted gold, which, on being
weighed and the result multiplied by 2240 for a 1 lb. assay, or by
1120 for 2 lb., will give the amount of gold per ton which an ordinary
battery might be expected to save. Thus 1 grain to the pound, 2240 lbs.
to the ton, would show that the stuff contained 4 oz. 13 dwt. 8 gr. per
ton.
If there should be much base metal in your sample such as say
stibnite (sulphide of antimony), a most troublesome combination to the
amalgamator--instead of the formula mentioned above add to your
mercury about one dwt. of zinc shavings or clippings, and to your water
sufficient sulphuric acid to bring it to about the strength of vinegar
(weaker, if anything, not stronger), place your material preferably in
an earthenware or enamelled basin if procurable, but iron will do, and
intimately mix by stirring and shaking till all particles have had an
opportunity to combine with the mercury. Retort as before described.
This device is my own invention.
The only genuine test after all is the battery, and that, owing to
various causes, is often by no means satisfactory. First, there is a
strong, almost unconquerable temptation to select the stone, thus making
the testing of a few tons give an unduly high average; but more often
the trouble is the other way. The stuff is sent to be treated at some
inefficient battery with worn-out boxes, shaky foundations, and uneven
tables, sometimes with the plates not half amalgamated, or coated with
impurities, the whole concern superintended by a man who knows as little
about the treatment of auriferous quartz by the amalgamating or any
other processes as a dingo does of the differential calculus. Result:
3 dwt. to the ton in the retort, 30 dwt. in the tailings, and a payable
claim declared a "duffer."
Public-domain text, read in full here on John Shaqi.
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