About four hundred pounds is then put into an arrasira
ten or twelve feet in diameter; a thousand pounds into
the largest size. If the quartz is not very hard it can
be pulverized in four or five hours. The ore is kept
wet all the time, and the grinding is continued until
the mass is like cream. Quicksilver is then put in at
the rate of an ounce or more to each ounce of gold that
is supposed to be in the quartz, and the grinding goes
on for an hour or two longer until the amalgamation
is considered complete. Quite a stream of water is then
allowed to run in through a sluice gate, and the grind-
ing continues half an hour, to let the amalgam settle
in the bottom. Grinding then stops. Another gate
is opened, and the stream of water soon washes out
the fine gray mud to which the rock has been reduced,
leaving the metal on the bed of the arrastra.
