CONSTITUENTS OF PLANTS, ETC. 333 



sugar, or lactose, an important constituent of milk, having 

 the composition Ci 2 H 22 O n .H 2 O, which differs from cane- 

 sugar only by one molecule of water; 3. Grape-sugar, or 

 glucose C 6 H 12 O 6 which is especially abundant in fruits, 

 as grapes, prunes, figs, etc., and occurs solid and crystal- 

 lized in dried fruits raisins, for instance ; 4. Fruit-sugar, 

 or cellulose, which occurs in honey and many fruits, togeth- 

 er with glucose, and possesses the same composition, but 

 differs in its optical properties. The last kind can not be 

 crystallized. 



458. Cane-Sugar. This kind of sugar is obtained more 

 largely from the sugar-cane than from other plants, and 

 hence comes its name. The amount of sugar extracted an- 

 nually from the sugar-cane in all parts of the world is many 

 millions of pounds, the largest portion coming from the 

 East and West Indies. Cane-sugar is obtained largely 

 from the sugar-beet on the continent of Europe, and from 

 the sugar-maple in the northern parts of this country. In 

 obtaining sugar from the cane the juice is first pressed out 

 by passing the cane between large iron rollers. The juice 

 is then clarified, and boiled down to such a point that it 

 will crystallize as it cools. The raw sugar is thus formed, 

 and the drainings which come from this make the common 

 molasses. The sugar thus obtained is refined by various 

 means and processes, by which it is pre- 

 pared in different forms for the market. 



The crystals which sugar is disposed to 



form are of the shape seen in Fig. 114, an 



oblique six-sided prism, as you may ob- Fig. 114. 



serve in what is called rock-candy. 



459. Milk-Sugar. The sweetness of milk depends upon 

 a peculiar kind of sugar. When the curd is separated from 

 milk in the making of cheese, the sugar remains dissolved 

 in the whey. It can be obtained from this by boiling it 



