128 
Journal of the Mitchell Society [. November 
are 4 feet deep and 20 feet in diameter with the usual 
cocoa matting- filter in the bottom. When filled to conveni- 
ent height, they hold 40 tons of sand. A solution containing 
1.4 pounds of potassium cyanide per ton of water is pumped 
upon this and drained off through the filter; this solution is 
kept circulating as rapidly as possible, keeping the sand 
always covered, for three or four days until the sand must be 
removed to make room for another batch. Then the solution 
is allowed to drain off, after which a little water is added to 
displace what solution remains in the damp sand. The sand 
is then washed out by a stream of water from a hose throug-h 
an opening in the bottom of the tank into a troug-h or 
launder, to a settling pond where the sand settles out and the 
water collects to be pumped back again. 
The slimes flow from the sand boats to one of the three 
agitation tanks 10 feet deep and 20 feet in diameter. Near 
the bottom of each of these is a slowly revolving paddle consist- 
ing of four well braced oak arms carrying pins. Some of the 
surplus water is drained off and a solution carrying 1 pound 
of potassium cyanide per ton of water (0.05%) is added. 
The agitation continues while the solution and slimes are 
drawn off at the bottom to a 4-inch centrifugal pump, thus 
thoroughly aerating and mixing it. This process continues 
until the tank is needed for more slimes. The solution is 
then pumped into one of the settling tanks 14x18 feet at a 
little lower level. Here the solid matter slowly settles out 
and the clear solution is drawn off. Sometimes the slimes 
are returned for a treatment with a second solution until 
they are finally sluiced out to waste. The solution from the 
sand tank, which now contains the gold, is passed directly to 
the zinc boxes; these have six compartments, 2x2x2 feet, with 
a side trough and a diaphragm for circulating the solution. 
This arrangement allows any one box to be emptied and 
cleaned while the solution circulates through the others. 
From the zinc boxes the solution flows to the sump tank, 
10x20 feet. Here more potassium cyanide is added to replace 
what has been consumed until the solution reaches the right 
