the sluice is therefore full of holes from one to two inches wide, from
three to seven inches deep, and six feet long. These are the places in
which the gold, quicksilver, and amalgam are caught. Quicksilver is
used now in nearly all the sluices, and is the more necessary the
smaller the particles of gold. The large pieces of the metal would all
be caught by their specific gravity without the aid of amalgamation.

The sluice-boxes having been made, and set up with the proper grade,
the water is turned in. The boxes are made of the rough boards as they
come from the saw, and the joints are not waterproof, but the leaks are
soon stopped by the swelling of the wood, or by the dirt. The stream of
water in the sluice is at least two inches deep over the bottom. The
height of the sides of the boxes is from eight inches to two feet. The
sluice usually runs through the claim, and the auriferous dirt is
thrown in with shovels, of which from four to twenty are constantly at
work. A man will throw in from two to five cubic yards of dirt in one
day. The water rushing over the dirt as it lies in the box, rapidly
dissolves the clay and loam, and then sweeps the sand, gravel and
stones down. The first dirt in the box goes to fill the spaces between
the riffle-bars. After the sluicing has been in progress a couple of
hours, some quicksilver is put in at the head of the sluice, and it
gradually finds its way downward, most of it stopping, however, near
where it is put in.

_Amalgamation._--There are a few metals, including gold, silver, copper
and tin, which, with quicksilver, form a peculiar chemical union called
amalgamation, a process of great importance to the gold miner. When a
piece of gold or silver is placed in mercury, the latter metal
gradually penetrates through it, destroys the coherence of its
particles, and form with it a mass like dough. A lump of gold as large
as a bean will be soaked through in three or four days; with silver and
copper the process is slower, but they are affected in the same manner.
Amalgamation, though a union of a solid with a liquid, differs much
from a solution. In the latter the union is mechanical; in the former
it is chemical. In the latter the solid is reduced to particles of
impalpable fineness; in the former it is not. An ounce of salt will be
dissolved in, and nearly equally diffused through, a pint of water; but
if an ounce of gold be thrown into a pint of quicksilver, it will,
after formi