276 The Sugar-Beet in America 



given because these compounds are made up of carbon 

 combined with hydrogen and oxygen in the ratio in which 

 these elements are found in water. This makes the carbo- 

 hydrates in reality carbon-water compounds. The sugars 

 are as a rule crystalline, soluble in water, less soluble or 

 insoluble in alcohol, and insoluble in ether and other sol- 

 vents that are immiscible with water. They all have a 

 more or less sweet taste, but vary considerably in sweet- 

 ness. Most sugars have the property of rotating the 

 plane of polarized light. This property is of great aid to 

 the chemist in making rapid determinations of the quantity 

 of sugar present in any substance. 



The commercial sugars are divided chemically into two 

 classes : monosaccharids and disaccharids. The mono- 

 saccharids have the formula CeH^Oe and include dex- 

 trose, or grape-sugar, and levulose, or fruit-sugar. The 

 disaccharids have the formula C^H^On and include su- 

 crose, or cane-sugar, lactose, or milk-sugar, and malt- 

 ose, or malt-sugar. They may be considered as con- 

 densation products of the monosaccharids and derived 

 from two molecules by the elimination of water thus : 

 2C 6 H 12 O6-H 2 O = Ci2H 2 2Oii. The sugars of the disac- 

 charid group are hydrolyzed when heated in solution with 

 dilute acid ; in the case of sucrose a mixture of dextrose 

 and levulose results, the change consisting of the addition 

 of a molecule of water and a bisection of the sucrose 

 molecule. This action is called "inversion." 



Sucrose, or cane-sugar, is the most important of the 

 sugars ; it is the ordinary sugar of commerce. It is about 

 two and one-half times as sweet as grape-sugar. The 

 name cane-sugar was given because it was first obtained 



