THE CHEMISTRY OF SUGAR. 503 



Honey is composed of left-handed or invert-sugar, some grape- 

 sugar, and more or less cane-sugar. After keeping for some time the 

 cane-sugar is all converted into the invert variety. When cane-sugar 

 is heated to a temperature of about 200 C, it undergoes a transforma- 

 tion, and a part of it is changed into an aromatic substance called 

 caramel. This change consists essentially in the loss of two molecules 

 of water. Caramel is used chiefly in the manufacture of candies, for 

 flavoring: whiskies, brandies, etc. 



A pleasing and instructive experiment which any one can try will 

 show that suorar is made of charcoal and water. A strong solution of 

 sugar is placed in a glass until the bottom is well covered. Strong 

 sulphuric acid (oil of vitriol) is now added, and the whole stirred with 

 a glass rod until it swells up and turns black. The sulphuric acid has 

 a very strong liking for water, which it steals from the sugar mole- 

 cules, leaving only the carbon. 



Another interesting experiment is to burn the carbon in sugar with 

 the oxygen in the chlorate of potassium, the lire being kindled with a 

 drop of sulphuric acid. For this experiment four parts of sugar are 

 carefully mixed in an old saucer with five parts of chlorate of potas- 

 sium, and the mass then touched with a glass rod which has been 

 dipped into strong sulphuric acid. The chemical action produced by 

 the sulphuric acid makes heat enough to ignite the whole mass, and 

 the carbon of the sug-ar is thus burned out. 



O 



Grape-sugar, as its name implies, is found in grapes and some other 

 substances. This name is also sometimes incorrectly given to one, and 

 often all the sugars made from starch or derived from fruits. It is 

 dextro-gyratory, having for the sodium ray a specific rotatory power 

 of about 52*5. It is fermentable, and is not changed by heating with 

 dilute acids. It crystallizes, but with less facility than cane-sugar, and 

 is much less sweet to the taste. There are other varieties of sugar 

 which possess the same properties as grape-sugar. To these the gen- 

 eral name, dextrose or glucose, has been given. Any sugar, whatever 

 be its source, which, in a dry state, has the formula C 6 H ]3 6 , and a 

 specific rotatory power of 52 # 5 to the right, is entitled to the name 

 dextrose. 



Dextrose is also the final product of long-continued boiling of 

 starch with an acid. 



Starch-sugar, or amylose, is a mixture of various products, chief 

 among which are dextrose, dextrine, and maltose. 



For a full discussion of this sugar I refer to my paper in this maga- 

 zine for June, 1881. 



Milk-sugar, or lactose, is found in milk, and is not important com- 

 mercially. It is used mostly as a vehicle for administering- medicines. 



*/ J ZD 



In composition it is identical with cane-sugar, but differs from it 

 greatly in both chemical and physical properties. 



Optically it is nearly related to dextrose, its specific rotatory power 



