148 SUGAK. 



340. Sugars are divided into two classes: those 

 which are crystallizable, and those which are uncrys- 

 tallizable : that is to say, those which, when their 

 solution in water is evaporated, are obtained in the 

 form of regular-shaped little grains, like common 

 cane" sugar, and those which under these circum- 

 stances do not form regular grains, but remain thick 

 viscid liquids, like treacle. The crystallizable sugars 

 are divided into two classes — cane sugar, and grape 

 sugar; these two varieties differ slightly in composi- 

 tion, the latter containing rather more hydrogen and 

 oxygen in proportion to its carbon than cane sugar ; 

 they differ very considerably in chemical properties, 

 grape sugar only being capable of undergoing fer- 

 mentation (365). 



341. Sugar exists in a great many vegetables, but 

 it very frequently happens that there are so many 

 other substances present, that the sweet taste of the 

 sugar is quite hidden. It is only in those plants which 

 contain a very large proportion of sugar, or which 

 do not contain any strong-tasted substances, that 

 we are able to recognize sugar by its sweet taste. 

 Most ripe fruits contain a large quantity of sugar ; 

 it is likewise found abundantly in the sap of a good 

 many trees, from some of which, like the sugar maple, 

 it is procured in such quantities as to be extracted as 

 an article of commerce. 



342. The composition of sugar is similar to that of 

 starch : the proportions in which its three elements, 

 oxygen, hydrogen, and carbon, are united together 



