SUGAR. 67 



but it is evidently a reserve material, intended for the nutrition of the 

 infant, and not for consumption in the body of the parent. 



Saccharose, 12 H 22 U , or Cane Sugar. 



This variety, the oldest known species of sugar, is derived from the 

 juices of the sugar cane, where it exists in great abundance. It 

 solidifies on cooling from a hot concentrated solution in the well- 

 known white granular crystalline masses, the form in which it is 

 generally used for culinary purposes. If crystallized more slowly, it 

 furnishes large, colorless, prismatic crystals, in which form it is known 

 as " rock candy" or ki sugar candy." This sugar is also manufactured 

 from the juices of the beet-root, and, imperfectly purified, from those of 

 the sorghum and the sugar-maple. It exists to some extent in the 

 green stems of Indian corn, in sweet potatoes, in parsnips, turnips, and 

 carrots, and in the spring juices of the birch and walnut trees. Honey 

 is a mixture. of glucose and saccharose, together with various other 

 substances. 



Cane sugar originates from glucose, in the process of vegetation, by 

 a change the reverse of that by which glucose itself is formed from 

 starch, that is, by the loss of oxygen and hydrogen in the proportions 

 to form water. A comparison of the chemical composition of the two 

 substances will show the manner in which the transformation takes 

 place, namely : 



Glucose. "Water. Cane sugar. 



2(C 6 H 12 6 ) - H 2 = C 12 H 22 O n . 



Saccharose is the most soluble of all the sugars, and has the strongest 

 sweet taste. It rotates the plane of polarization to the right 73. 8 4. 

 It differs in its reactions from glucose by the fact that it is not turned 

 brown by boiling with an alkali, and does not reduce the copper-oxide 

 in Trommer's test, or does so very slowly and imperfectly. It may be 

 converted into glucose, however, by a few seconds' boiling with a trace 

 of dilute mineral acid, and will then react promptly both with boiling 

 alkalies and with Trommer's test. Cane sugar is not immediately 

 fermentable, but by contact with yeast it is after a time changed into 

 glucose, and finally enters into fermentation. As it occurs in the 

 tissues of the living vegetable, it is regarded as a reserve material, 

 which is subsequently reconverted into glucose for the purposes of 

 nutrition. 1 When taken as food, it is transformed into glucose by the 

 intestinal fluids in the digestive process. 



Sugar and starch, accordingly, in all their varieties, are closely allied 

 to each other, both in their chemical and physiological relations. Their 

 proportions of hydrogen and oxygen are such as to have given them, as 

 a class, a distinct name, and their mutual convertibility in the process 

 of vegetation has been shown by abundant investigations. Starch and 

 sugar, in the living plant, represent the same nutritive material under 



1 Mayer, Agrikultur-Chemie, Band i. p. 122. 



