spread over their lower riffles, with tendency to discharge over their ends.
When
it is decided to " clean up," the bed-rock and cuts are piped clean. No
material is turned into the sluices, clear water alone being run until
the sluices are free of dirt.
When
thus prepared only a small head of water, such as men can conveniently
work in, is turned through the sluice, and the blocks are taken out by
means of crowbars, washed to free them from amalgam, and laid at the
side of the sluice. This is done in sections approximating ioo feet.
Between each section one row of blocks is left in the sluice. These
rows serve as riffles to prevent the gold and quicksilver from passing
down the sluice. After the first section of blocks is taken up men
follow the gravel and dirt as these are slowly washed down the sluices,
and pick up the quicksilver and amalgam with iron scoops, with which
they are put into sheet-iron buckets.
As
each riffle is reached the amalgam and quicksilver are collected, the
block riffles removed, and the residue is washed down to the next
riffle, and so on down the entire line of sluice. When this operation
is completed the water is turned off and the workmen attend to the
nail-holes and cracks in the sluices, "creviceing" with silver spoons
to obtain the amalgam contained in them. After this the side-lagging is
overhauled and the blocks are replaced. Where the sluices are of great
length the lower portions are usually lined with heavy rock, which can
be used for longer periods without cleaning up.
It
is customary in mines which have very long sluices, and which are run
at night, to clean up during the day as long- a section as can be
cleaned and put in order for further work, and to resume washing at
night, until the whole line is cleaned up. At the end of the water
season the entire works are cleaned up and put in order for the next
season's run.
