22 SORGHUM. 



CHAPTER II. 



(a.) Chemistry of Sugar. 



(b.) Sources of Su^ar. 



(c. ) Statistics of Sugar. 



{d.) Bibliography of Sorghum. 



CHEMISTRY OF SUGAR. 



Under the name, sugar, the chemist includes a number of different 

 organic compounds, most of them being vegetable in their origin. 

 They are all soluble in water, though in different degrees ; and are all 

 characterized by a sweet taste, though possessing different degrees of 

 sweetness. 



They are neutral in their reactions with vegetable colors; but, in 

 the compounds they form, play the part of acids. They are all 

 remarkable for their effects upon a beam of polarized light, which, 

 when passed through solutions of any one of the sugars, is rotated to 

 the right or the left. The direction and the degree of rotation is con- 

 stant under the same conditions of density of solution and temperature 

 for the several sugars. 



The principal members of this group of sugars, are : 



1. Cane sugar; also known as sucrose and saccharose, C^jHggOn. 

 This sugar is found present in the juices of the sugar-cane, Saccha- 



rum ofRcinarum ; maize, zea mais; sorghum. Sorghum saccharatum ; 

 beets, Beta vulgaris ; sugar maple, Acer saccharinum ; several species 

 of the palm, and many other plants. 



The pure sugar, from either of the above sources, is identical in all 

 its properties — as crystalline form, chemical composition, degree of 

 solubility, sweetness, and rotatory power. 



2. Glucose, CgHjoOg. Under this name is grouped two principal 

 compounds : (a) Dextro-glucose, or Dextrose, which rotates the polar 

 ized beam to the right; and (6) Laevo-glucose, or Laevulose, which 

 rotates the beam to the left. 



Dextro-glucose is known as grape sugar, starch sugar, fruit sugar, 

 honey sugar, diabetic sugar, according to its source. 



Sweet fruits and honey contain this form of glucose, associated with 

 cane sugar and laevo-glucose. 



Laevo-glucose has the same chemical composition as dextro-glucose ; 

 but is distinguished by its left-handed rotatory power. This form of 



