98 Modern Improvements in Gorn-Milling Machinery. 
smooth rollers, possess a kind of adherence and plasticity which 
causes them to be compressed into cakes or flakes instead of 
cracking freely into flour. These flakes will not pass the meshes 
of the " dressing " or sifting apparatus, and, instead of being 
removed from the system at the proper points as flour, pass from 
machine to machine as flattened particles, and thus, by appear- 
ing in unlooked-for quantities in unexpected places, overload 
the machines and interfere with their correct operation. 
J\Ioreover, as the reduction or grinding is gradual, and ac- 
complished by a series of rollers, at each passage through the 
rollers more pressure than usual is applied in a vain attempt 
to disintegrate the material. The result of this is greater fric- 
tion, and consequently a higher temperature both of the rollers 
and of the stufi" p^ing through them. This higher temperature 
causes the excessive moisture present in the meal to evaporate, 
and this moisture is condensed upon coming in contact with 
the cool framing of the machines and with the surfaces of the 
conduits, pipes, elevators, and conveyors through which the 
ground material passes. The condensed moisture combines 
with the flour-dust, with which all the internal spaces of the 
machines and conveying apparatus is charged, and together 
they form an adherent paste. If the hot moist air be not 
drawn away from the roller-mills and dressing-machines, the 
gauze with which the latter are covered is liable to be clogged, 
and the machines become inoperative. The paste which forms 
on the internal surfaces either ferments and becomes putrid 
and stinking, or falls off" and gathers into balls or lumps, which 
stop up passages, and thus by closing an outlet, it may be, from 
a machine or conveyor, cause a " choke-up," one of the terrors 
of the miller, and possibly a break-down and stoppage of the 
whole mill. Again, it is easy to conceive that a material that 
is merely flattened and will not break up into flour and pass 
the meshes of the sifting apparatus, must be carried onward 
through the system until eventually it finds its way to the offals, 
and thus the yield of flour from such wheat is pro f.anto reduced. 
These are but instances out of the many troubles which the 
use of damp soft wheats occasion in roller-milling. And it is 
because of these troubles that owners of mills on a lai'ge scale 
will not employ native wheats in damp seasons. No concession 
in price is sufficient inducement to them to risk the disorgani- 
sation of the mill, and pi'obable loss of reputation, by turning 
out inferior or irregular flour, and neither good quality nor 
regularity can be attained if it be attempted to use damp wheats 
in roller-milling. 
There are, however, two modes in which these wheats may be 
used. First, by submitting them to an artificial drying process 
