l84 BOTANY OF CROP PLANTS 



Corn oil is obtained from the embryo. When freshly 

 prepared, it is pale yellow in color. It is employed in the 

 manufacture of soap, and paints, and when mixed with lin- 

 seed oil, it has some value as a grinding oil. Corn oil is also 

 sometimes vulcanized into a cheap grade of rubber. 



Corn Starch. — About 50,000,000 bushels of corn are used 

 annually in the United States in the manufacture of com- 

 mercial starches, and products derived from them. In the 

 manufacture of corn starch, the corn is steeped from two to 

 four days in warm water containing about 0.2 per cent, of 

 sulphurous acid. Steeping is instituted in large wooden vats 

 holding about 2,000 bushels of corn. When the grains are 

 softened sufi&ciently, they are lead through a Fuss mill which 

 thoroughly breaks up the grain. The embryos are separated 

 from the rest of the grain material, and removed to another 

 receptacle. The disintegrated grains are freed from the 

 embryos, mixed with water, more finely ground and then 

 shaken through bolting-cloth sieves. Starch and gluten pass 

 through the sieves, while the courser materials, such as frag- 

 ments of the pericarp, are caught by the sieve. The liquor 

 containing starch and gluten is passed over tables, very 

 slightly inclined, and as the liquid slowly flows down these 

 tables, the starch granules settle, while the lighter particles 

 of gluten are carried off the lower end. The starch is re- 

 moved from the tables, washed, and kiln-dried. 



Glucose. — The commercial "glucose" is a thick syrup — a 

 product of the partial hydrolysis of starch. The manufac- 

 ture of corn starch has been described. The "green 

 starch" from the tables is made into a thick cream by mix- 

 ing with water. This is then passed to converters where 

 the starch is treated with hydrochloric acid to bring about 

 its partial hydrolysis. The converted liquor is blown out 

 of the converters into the neutralizer, where it is treated 



