CRANE. | Theory of Ore Concentration. 339 
mixture of mineral and waste or different minerals, is re- 
treated. 
Adjustable partitions are occasionally made in a jig, by 
means of which the speed of the water currents may be regu- 
lated by increasing or diminishing the cross-sectional area of 
the cells. | 
A 
i 
( 
{ 
{ 
( 
{ 
‘ 
+r 
i 
( 
{ 
i} 
{ 
7 
Fig. 63. Discharge gate for screen-product of power jig. 
