Previous
to my continuing to report on these and kindred matters, I would
respectfully request our mining managers, or experts in mining matters,
firstlyto draw their own conclusions ; and, secondly, to determine
whether or notany similarly severe and elaborate treatment of our
quartz has been carried out in this colony. And also whether, with our
simple and crude treatment on Bendigo—which produces, as a type for
Australia in general, according to the above table, the lowest loss in
gold-mining countries— we could not, allowing that table to be correct,
which is open to considerable doubt, reduce that loss considerably by
adopting some portions or the whole of the more elaborate and effective
Oalifornian method, and thus render reefs payable that cannot now,
owing to their low yield of gold, be worked remuneratively. It should
be remembered that the Californians control their processes step by
step by average assays ; that they have a full knowledge of what their
ore ought to turn out; and that they have added and are still inventing
machinery, by means of which they purpose to reduce the loss they
suffer, whilst we are altogether too cautious to introduce anything
out of the common, or what would require at its initiation a greater
amount of skill and care to work successfully for the benefit of the
district. Some general idea of loss of gold on working may be obtained
at regular intervals during each day by sampling the residues. This can
be done by simply placing a bucket, to receive at various stages during
the process, under the launders, shoots, &c, and by doing so every
two hours, the contents of such buckets should be emptied into a larger
vessel, well stirred and allowed to stand for a while, in order to
cause the deposition of the suspended matter at the bottom. The water
should then be carefully decanted, by means of a syphon, and the slimes
and sands dried, thoroughly mixed, and average samples of each
submitted to both wet and dry assay. To illustrate the specific gravity
of various particles of gold, of either a round, flattened, porous, or
float kind of form, take a glass tube 2 feet 6 inches long, and fill it
with pure rain-water, then add these particles of gold, and it will be
seen, on closing the open end by a stopper and turning it downwards,
that the falling speed of the gold varies considerably; the round
particles reaching the bottom of the tube first, whereas the float-gold
will swim for a considerable while ere it also descends downwards. If
this result takes place in " still" water, what a displacement must
take place in water violently agitated by the stampers, and flowing
over planes constructed at considerable grades or inclines! In my
opinion, I submit we have the ore or quartz sufficiently auriferous in
large quantities throughout Victoria, and this supply will doubtless be
augmented by the deep-ground discoveries; therefore the general
introduction of approved methods of treatment,- even if such treatment
should be surrounded by the difficulties attending "refractory" and
"rebellious" substances impregnating such ores, cannot be undertaken
too soon. And I may also state that during the whole of my
peregrinations in the Californian quartz-mining districts, I have not
observed any quartz that would compare unfavorably in that respect with
that of our Victorian mines; and I specially took notice of the great
scarcity of arsenical pyrites and galena so frequently associated with
rich quartz on Bendigo. As it is well known that our gold is both
heavier and purer than that of California, any more perfect treatment
should, in our case, add proportionally to the yield hitherto obtained,
because the Pacific treatment is so superior to that in vogue at most
of our crushing machines.
