PRODUCTION AND UTILIZATION OF FATS AND OILS 5 
the variety of the plant and {he climatic conditions under which 
it is grown, the average oil content is about 20 per cent. The pro- 
duction of cottonseed oil in the United States exceeds that of any- 
other single vegetable oil. 
Preparation 
As it comes from the gins, cottonseed is almost always heavily 
coated with short lint and mixed with broken bolls, stems, sand, 
nails, and other trash. Before it can be pressed it must be cleaned 
and delinted. To remove the trash, the seed is run through revolving 
screens, which separate the larger pieces of debris, over shaking 
screens and magnets and through cyclone cleaners, to remove sand, 
nails, and dust. The clean seed is then fed into the delinters, which 
consist of a series of fine-tooth circular saws set close together on a 
rapidly revolving shaft. At the back of each delinter a long cylin- 
drical brush runs so close to the saws that it catches the cut fibers 
or linters and passes them to a reel on the back of the brush. The 
linters collect on the reel into a compact felt that looks like cotton 
batting. This is baled for use in the manufacture of mattresses, 
paper, guncotton, and artificial silk. 
The seed, now nearly free from lint, is sent through the hullers 
and passed over shaking screens, which separate the kernels from 
the hulls. The hulls are passed through hullers and separators 
once or twice more until they are practically free from the oil-bearing 
kernels or meats. The separated meats or decorticated seeds are 
passed through a series of three or more heavy steel rolls and 
delivered above the press room. 
In the United States it is customary to press cottonseed once only. 
When hydraulic presses are used the seed is always heated or cooked 
before being pressed. Cooking is a most important step in the ex- 
pression of oil by the hot process. Experience and judgment are 
necessary for the maximum yield of oil of the best possible grade. 
A steam- jacketed cooker, equipped with a mechanical stirrer, which 
mixes the meats thoroughly and prevents uneven cooking, is used for 
the cooking. Xear its top the cooker is fitted with a perforated 
steam pipe, through which steam may be admitted to moisten the 
meats should they become too dry. A subheater, placed just below 
the cooker, is often used to keep the cooked batch hot until the 
presses are ready for it. 
PRESSING 
The steel box frame hydraulic press, operating under a pressure 
of from about 3,000 to 4,000 pounds per square inch, is the type most 
commonly used for the production of American cottonseed oil. It 
consists of a series of horizontal steel plates, approximately 14 
inches wide by 34 inches long, set one above the other, about 5 inches 
apart when the press is wide open. These perforated or channeled 
plates are provided with close-fitting steel sides or frames, so that 
the whole machine is really a series of boxes without ends, piled 
one upon the other, the lowest resting on the hydraulic piston. 
Above the top frame a heavy iron plate is fastened to the hydraulic 
piston cylinder by four heavy vertical rods, which serve as guides 
for the sliding frames. 
