362 University Geological Survey of Kansas. 
Within the past year, an attempt has been made to divert 
from the crusher such material as is of such a size to allow 
it to pass at once to the first set of rolls, or, better still, to 
the rougher jig. ‘Too much cannot be said in favor of the lat- 
ter method, and when combined with hand picking, whether 
under ground or in the crusher room, will materially change 
the method of the milling of ore in this district. 
“What is needed, then, is a thorough system of sizing of all 
the products of the mine which are brought to the crusher 
room. ‘The minerun dirt, while upon the floor of the crusher 
room, might be thoroughly washed of all fine materials, dirt, 
slime, etc., washed from the pile of ore and borne down 
the sloping floor of the room (the inclination could easily 
be determined) over gratings or wire and perforated metal 
screens, when it could be sized, and each product con- 
ducted by launders or gravity spouts to the apparatus in- 
tended to receive such sizes. In each of the respective 
machines it would-join the material which at the same time 
is fed into the crusher by hand, as is now done, and which 
would have been reduced to the size of the material sent at 
once to the respective apparatus. By this means the slimes 
could be fed at once into the sand jig or to the slime-washing 
apparatus, the next size above that to the rougher, while the 
next above that would go to the first set of rolls, thus saving 
the wear of machinery and waste of mineral by too frequent 
and close crushing, the latter being especially great with fri- 
able ores, as lead and zinc. 
CONCENTRATION. 
Concentration is accomplished by means of both reduction 
machinery and concentrating apparatus proper, such as jigs, 
tables, etc. No special criticism can be made upon the ap- 
paratus employed, except possibly the arrangement, which 
needs to be altered to fit prevailing conditions, as character 
of ore, etc. The main difficulty is that concentration is not 
carried far enough. A vast amount of float or flour mineral 
occurring naturally, also produced by the crushing and re- 
crushing of coarse and fine together, and due to various 
causes, is a source of great loss. No systematic attempt has 
been made to prevent this loss in the mills except by the so- 
