194 AGRICULTURAL CHEMISTRY 



the sugar determined. A given weight of pure sucrose 

 dissolved in a definite amount of water always turns a ray 

 of polarized light a definite number of degrees which are 

 accurately measured by the polariscope. Any decrease 

 in purity influences proportionally the angle of diver- 

 gence of the polarized light. Hence, if the angle of 

 divergence of a commercial sugar is determined, its purity 

 is likewise determined. 



254. Sugar- Beets are usually paid for on the basis 

 of their content of sugar and the purity of the juice. 

 For sugar-making purposes, the higher the content of 

 sugar and the purer the juice, the more valuable the 

 beets. Ordinarily, sugar-beets contain from 12 to 16 per 

 cent, sugar ; occasionally as low as 8 and as high as 20 

 per cent. In addition to sugar, the beet juice contains 

 other solids, as small amounts of organic acids, albumin 

 and pectin . When the content of solid matter is 20 per 

 cent, and 16 of the 20 parts are sugar, the juice has a 

 purity coefficient of 80 ( lft / M X 100). 



255. Food Value of Sugar. When properly combined 

 and used with other foods, sugar is a valuable nutrient 

 for the production of heat and energy. Like starch, it 

 is incapable of sustaining life unless associated with nitroge- 

 nous compounds. One pound of sugar, when burned, 

 yields 1.5 pounds of carbon dioxid and 0.58 pound of 

 water. 



In a ration, sugar is considered as having the same 

 caloric value as starch, viz., i pound yields 1860 

 calories. 





