380 THE FORAGE AND FIBER CROPS IN AMERICA 



The crude oil which is pressed from the meats of the cotton 

 seed goes to the refinery where it is first filtered to remove for- 

 eign matter in suspension, and then treated with caustic soda, 

 which unites with the free fatty acids. This product, called 

 soap stock, is removed by settling, or more rarely by filter 

 presses, and is used in the manufacture of soap. The resulting 

 oil is known as summer yellow oil, which may constitute from 

 80 to 95 per cent, of the original crude oil. 



Summer yellow is next mixed with fuller's earth and the 

 agitated mass passed through a filter press, which removes the 

 yellow color and leaves the oil nearly or quite the color of 

 pure water, when it is known as summer white oil. Summer 

 white oil is used for making lard compounds, in the manufacture 

 of oleomargarine, as a substitute for olive oil, and directly as 

 cotton-seed oil for various culinary purposes for which lard 

 and other fats are used. It is also sold largely under the name 

 of salad oil, although not all salad oil is cotton-seed oil. Al- 

 though a perfectly desirable and healthful article of food, its 

 use is unfortunately somewhat surreptitious. While much of the 

 larger amount of cotton-seed oil in commerce is summer white 

 oil, other kinds or qualities of oil are produced. Summer yel- 

 low oil is sometimes bleached to a white oil by the use of sul- 

 phuric acid, when it is known as miner's oil. 



Winter oils are also produced from summer oils by reducing 

 the temperature to about 30 F., when the stearin solidi- 

 fies and is separated from the liquid olein by filtration under 

 pressure at the temperature named. The stearin is sold to make 

 lard compounds such as cottolene, while winter yellow oil is 

 highly prized for cooking, because olein does not decompose on 

 frying so readily, and hence does not produce the disagreeable 

 odor noticeable with summer oils. 1 Winter white oil is used 

 for the manufacture of medicinal compounds. 



"Cottonseed-oil mills may be divided into two classes: (1) those of large 

 capacity, erected at railway centers, and (2) small cooperative mills, built in 

 1 Tompkins: Cotton and Cotton Oil, p. 359. 



