368 PRINCIPLES OF AGRICULTURAL CHEMISTRY 



Like the monosacchosides, the polysaccharides are neutral, 

 sweet, colorless compounds, easily soluble in water, and they are 

 readily crystallizable. They are easily converted into mono- 

 saccharides by the action of warm dilute acids, or certain un- 

 organized ferments. The ease with which this action takes place 

 depends upon the nature of the sugar; simply warming for a 

 short time with a dilute acid is sufficient to split cane sugar 

 (sucrose) into glucose and fructose, while maltose requires to be 

 boiled for some hours with the acid for complete inversion. 



Sucrose, CnH^On, is prepared from sugar cane, sugar beets, 

 and maple sap. The impurities which accompany the sugar 

 are different when prepared from these three sources, but no 

 differences can be detected in the sugar when it has been thor- 

 oughly purified. 



Sucrose is widely distributed. The juice of sugar cane, sweet 

 sorghums, and sugar beets contains 10 to 20 per cent. 

 Peanuts contain 4-6 per cent., sweet potatoes 1-3 per cent., the 

 seeds of beans, peas, vetch, soja beans, hemp, and sunflower seeds 

 contain 4-6 per cent. Some fruits contain 5 per cent, or more. 

 Green corn, before the ears are formed, is quite rich in sucrose. 



Sucrose crystallizes in regular crystals belonging to the 

 monocline system. It is easily soluble in water and has a high 

 dextro-rotatory power. It melts at 160 C. and solidifies on cool- 

 ing to an amorphorous glassy mass. A high temperature con- 

 verts it into a substance known as caramel, which is used for 

 coloring some food materials. A still higher temperature car- 

 bonizes it with evolution of gases and vapors. 



Sucrose does not reduce Fehling's solution, but can easily be 

 converted into invert sugar, which has reducing power. This is 

 a method for its estimation. The polariscope is also used for the 

 estimation of sugar. The inversion of sugar takes places in the 

 ripening of some fruits, the curing of fodders, and in the cooking 

 and preparation of human foods. 



Manufacture of Sugar. The processes of manufacture from 

 sugar cane and sugar beets vary somewhat in details. The beets 

 are first sliced, and the sugar extracted with warm water or sugar 



