LOSS OF GOLD AND QUICKSILVER. 267
While
the knowledge of the quantity of gold in gravel banks remains as
imperfect as it is at present, the simple and well-known appliances now
in use are the most convenient and economical, and the excuse so often
given for small yields—viz., loss of microscopic gold, and bad
sluices—can be set down as one of the preliminary indications of a bad
investment.
The
loss of quicksilver in sluices would seem to involve the loss of gold,
but it is practically impossible to determine to what extent this is
the case. There are many conflicting opinions as to the amount of fine,
floured, and "rust" gold which escapes, but in properly constructed
sluices the appliances already known save all that can be economically
or profitably caught.
In
substantiation of this can be cited the work done in 1872-6 at
Gardner's Point. The number of inches of water used at the claim during
this period is not known. The number of cubic 3'ards of gravel moved
has been approximated from the best obtainable data and an inspection
of the property. From 1872 to 1874, inclusive, about 148,000 cubic
yards of dirt were mined. In 1875 the claim was run full time only
fourteen days. In 1876, 40,-000 cubic yards of gravel and 260,000 cubic
yards of lava ashes were washed. The gross yield from 1872 to 1876 was
$140,000.
The
tailings from all these washings were caught and confined in a ravine
situated a short distance below the claim. The length of the sluices
through which the gravel passed was 1,378 feet, with three
undercurrents. In 1876 the ravine, supposed by many to be exceedingly
rich, was cleaned up, and its gross yield was $1,168, not one per cent,
of the total receipts from the washings.
