r twice in the day, mix an ounce of sulphuric acid in a
quart of water and slowly pour it into the launder above the saver).
Underneath the "saver" you require a few riffles, or troughs, to catch
any waste mercury, but if not overfed there should be no waste. This
simple appliance, which is automatic and requires little attention, will
sometimes arrest a considerable quantity of gold.

We now come to the subsidiary processes of battery work, the "cleaning"
of plates, and "scaling" same when it is desired to get all the gold
off them, the cleaning and retorting of amalgam, and of the mercury,
smelting gold, etc.

Plates should be tenderly treated, kept as smooth as possible, and when
cleaning up after crushing, in your own battery, the amalgam--except,
say, at half-yearly intervals--should be removed with a rubber only; the
rubber is simply a square of black indiarubber or soft pine wood.

When crushing rich ore, and you want to get nearly all the gold off your
plates, the scraper may be resorted to. This is usually made by the mine
blacksmith from an old flat file which is cut in half, the top turned
over, beaten out to a sharp blade, and kept sharp by touching it up on
the grinding-stone. This, if carefully used, will remove the bulk of the
amalgam without injury to the plate.

Various methods of "scaling" plates will be found among "Rules of
Thumb."

Where base metals are present in the lode stuff frequent retortings of
the mercury, say not less than once a month, will be found to have a
good effect in keeping it pure and active. For this purpose, and
in order to prevent stoppage of the machinery, a double quantity is
necessary, so that half may be used alternately. Less care is required
in retorting the mercury than in treating the amalgam, as the object
in the one case is more to cleanse the metal of impurities than to save
gold, which will for the most part have been extracted by squeezing
through the chamois leather or calico. A good strong heat may therefore
at once be applied to the retort and continued, the effect being to
oxidise the arsenic, antimony, lead, etc., which, in the form of oxides,
will not again amalgamate with the mercury, but will either lie on
its surface under the water, into which the nozzle of the retort is
inserted, or will float away on the surface of the water. I have also
found that covering the top of the mercury with a few inches of broken
charcoal when retorting has an excellent