FATS 283 



nitrogen in manure made by animals or by green crops plowed 

 under and decayed by Fungi and Bacteria. 



Fats. — Fats, usually as oils, occur in all plants and in nearly 

 all parts. They are a storage form of food. In the kernels of 

 cereals the percentage of fats ranges from about 2 to 8 percent of 

 the dry weight. The percentage of fats ranges between 1 and 3 

 percent in straw and between 2 and 4 percent in hay and green 

 fodder. In nuts, such as the Pecan, Brazil Nut, Butternut, 

 Cocoanut, Filbert, Candle Nut, Hickory Nut, Pine Nut, and 

 Walnut, the fats run as high as 60 percent. Fats occur in most 

 all seeds and ia considerable quantities in cotton seed, flax seed, sun- 

 flower seed, poppy seed, hemp seed, and peanuts, ranging from 

 20 to 30 percent or more. Castor beans contain a high percentage 

 of castor oil. Most fruits contain fats and oHves yield 40 to 60 

 percent of oil. 



The constituents of fats are carbon, hydrogen, and oxygen, 

 but the proportion of oxygen is less than in the carbohydrates. 

 The fats are compounds of glycerine and fatty acids, the fatty 

 acids being chiefly palmitic, oleic, and stearic acids. The fats 

 occur in the cells mostly in the form of oil globules which are in- 

 soluble in the cell sap and must be changed by enzymes to glycer- 

 ine and fatty acids to be transported or used as foods. 



As a source of energy, when used as food, they have more than 

 twice the value that carbohydrates or proteins do, a gram yield- 

 ing about 9 calories of energy. Their yield of heat energy makes 

 them important constituents of foods in cold chmates, but in all 

 climates and seasons the fat content of a ration is an important 

 matter. Aside from their importance in foods, the vegetable 

 fats and oils are important in many other ways. Cotton seeds 

 yield about 45 gallons of oil per ton. In some years more than 

 36 million gallons are produced in the United States. It is used 

 in making compound butter, substitutes for lard, and in the man- 

 ufacture of candles, while that left in the cake after the pressing 

 process adds value to cotton seed meal as a feed for livestock. 

 Linseed oil, of which 17 to 20 pounds per bushel of Flax seed are 

 obtained, is the chief solvent in paints and is used in making 

 linoleum, oilcloth, painters ink, water proof fabrics, enamel for 

 buttons, and soap. Corn oil, expressed from the embryos of corn, 

 is used in making oleomargarine, lard substitutes, artificial rubber, 

 soft soap, etc. Cocoa butter is obtained from cocoa beans and 



