52 FIELD CROP PRODUCTION 



such importance that the term " by-products " can no longer be 

 accurately applied. Sometimes the entire profit from a starch 

 factory is derived from the utilization of what was formerly 

 waste. 



In the manufacture of starch, the shelled corn is first steeped 

 in water for a time, and then the kernels are cracked by running 

 them through coarse crushers. The ground mass is then trans- 

 ferred to separators and a small amount of water is added, 

 making a milky liquid. Upon stirring, the germs arise to the 

 surface and are removed. The germs thus liberated are thor- 

 oughly washed to remove all the starch and are then placed in 

 a hydraulic press which presses out the oil. That part which re- 

 mains in the press is either sold as corn oil cake or is ground 

 and sold as germ meal. The oil which has been removed by 

 pressure is used in this country in the manufacture of soap, 

 soap powders, and paints, and a large amount is exported in the 

 crude form for similar uses abroad. A substitute for rubber has 

 been made from germ oil and is used after vulcanizing as a sup- 

 plement of, or as a substitute for, rubber in the making of auto- 

 mobile tires, rubber shoes, and other rubber goods. 



That part which is left in the tanks is the glutinous material, 

 bran and starch. This, when run over bolting cloth, allows the 

 starch and glutinous matter to pass through and retains the 

 bran, thus separating it. The bran is washed to remove all the 

 starch and is then dried and ground and sold as cattle feed. 

 The starchy liquid containing the starch and glutinous matter 

 is run over slightly inclined tables, and because of specific gravity 

 the starch is deposited on the tables, while the glutinous material 

 is carried over the end of the tables into receiving tanks. The 

 latter is concentrated by filter presses and dried. When ground 

 it is sold on the market as gluten meal. Sometimes the ground 

 bran is mi.xed with the glutinous matter and with the liquid 

 used in steeping at the beginning of the process. The mixture 

 is dried to 10 per cent of moisture and then ground, bagged, and 

 sold on the market as gluten feed. The water used in steeping 

 the uncracked kernels removes some of the starch and mineral 

 elements, which, when added to the grain and gluten meal, 

 make a more desirable feed for animals. Gluten meal, therefore, 

 differs from gluten feed in that the feed has besides the gluten 



