e, aluminous clay, etc.,
which, under the action of the crushing mill become finely divided and
float off in water as "slimes," carrying with them atoms of gold, often
microscopically small. To save the gold in such matrixes as these is an
operation which even the best of our mechanical appliances have not yet
fully accomplished.

Where there is not too great a proportion of base metals on which the
solvent will act, and when the material is rich enough in gold to pay
for the extra cost of treatment, chlorination or cyanisation are the
best modes of extraction yet practically adopted.

Presuming, however, that we are working by the amalgamation process, and
have crushed our stone and obtained the free gold, the next requirement
is an effective concentrator. Of these there are many before the
public, and some do excellent work, but do not act equally well in
all circumstances. The first and most primitive is the blanket table,
previously mentioned; but it can hardly be said to be very effective,
and requires constant attention and frequent changing and washing of the
strips of blanket.

Instead of blanket tables percussion tables are sometimes used, to which
a jerking motion is given against the flow of the water and pulp, and by
this means the heavier minerals are gathered towards the upper part of
the table, and are from thence removed from time to time as they become
concentrated.

I have seen this appliance doing fairly good work, but it is by no means
a perfect concentrator.

Another form of "shaking table" is one in which the motion is given
sideways, and this, whether amalgamated, or provided with small riffles,
or covered with blanket, keeps the pulp lively and encourages the
retention of the heavier particles, whether of gold or base metals
containing gold. There has also been devised a rocking table the action
of which is analogous to that of the ordinary miner's cradle. This
appliance, working somewhat slowly, swings on rockers from side to side,
and is usually employed in mills where, owing to the complexity of the
ore, difficulties have been met with in amalgamating the gold. Riffles
are provided and even very fine gold is sometimes effectively recovered
by their aid.

The Frue vanner will, as a rule, act well when the pulp is sufficiently
fine. It is really a adaptation of an old and simple apparatus used
in China and India for washing gold dust from the sands of rivers. The
original consisted of an