Modem Improvements in Corn-Milling Machinery . 95 
be desired, as wheat can be thoroughly cleaned, with scarcely 
any waste of good wheat. 
The wheat thus freed from other matters will still have dirt 
attached to the skin, some dust among it, and pieces of mud 
that have escaped separation on account of being nearly the 
same size as the wheat, and occasionally stones. These stones 
are present in wheats that have been thrashed either by flail or 
by treading out on a thrashing-floor on the ground, and are 
picked up with the corn. To detach and remove the dirt and 
dust, to remove rough particles of the epidermis, and to break 
up the particles of mud, the wheat is subjected to strong friction. 
It is desirable, so far as possible, to remove the hairy beard and 
the loose skin which covers the germ, and any other wrinkled 
parts of the skin where dust may lodge — in fact, to polish each 
corn. -The variety of machines constructed for these purposes 
is great, as well as the materials and form of the operative parts. 
The great distinction of the machines is in the difference be- 
tween the" application of rough and rasping surfaces and smooth 
surfaces ; and in the latter class of machines, between those 
which accomplish the purpose by a beating action, and those 
which attain the object by causing a friction of the grains among 
themselves. For the purpose of polishing the grain and keeping 
the skin as far as possible unbroken, the latter class is to be 
preferred, and those having a I'asping or grating action ai'e to 
be avoided. The casings of nearly i.11 these machines are con- 
structed of perforated metal or woven wire, and no machine 
is perfect in which the dust produced and the pieces of skin 
detached are not at once separated from the wheat and carried 
away by air currents to the dust-room. When wheats are 
very dirty or the skins very rough, it is sometimes needful to 
pass them through two or even three such machines in succes- 
sion. It must be confessed, however, that there is room for 
improvement in this class of machines, especially for those in- 
tended for use in this country, where wheats of great dissimilarity 
have to be used, requiring means (which do not exist) of regu- 
lating the intensity of the frictional process. Finally the wheat 
is to be passed through a brushing-machine, in which, while the 
wheat is turned over in all directions, it is scrubbed by a brush 
so as to remove any dust or particle of skin that may still be 
lodged in the crevices of the corns. The wheat emerges from 
this series of machines with a smooth polished coat, so that when 
handled it is slippery to the touch and bright and glistening to 
the eye, instead of being in the normal state of roughness and 
dulness. 
But there are varieties of wheat in which the dust and dirt 
are so intermingled with the grain, and the mud is so stubborn, 
