VEGETABLES. dS 



contain a little sulphur and a trace of phosphorus 

 (CHONSP). 



175. Sugar, gum, and starch, on the other hand, 

 contain no nitrogen, and are therefore less nutritious 

 as articles of food. The elements are the same in 

 each, and in the same proportion as represented be- 

 low: 



Starch, C'^H^oO^o 



Gum, - - - - - Ci^HioQio 

 Sugar, C'^H'oO'o 



It will be seen that the oxygen and hydrogen in these 

 three substances exist in the same proportion as in 

 water. The same is true of woody fibre and of many 

 uther substances. They consist of carbon and the 

 elements of water. I ought perhaps to state that the 

 sugar before characterized is cane sugar. There are 

 other kinds of sugar. Grape sugar, for instance, is 

 differently constituted ; the sugar of milk is still dif- 

 ferent ; and that of the ash tree (the manna of com- 

 merce) is different from either. 



TRANSFORMATIONS. 



176. The fact that starch, sugar, and gum are the 

 same in chemical constitution, and that they are trans- 

 formable one into the other, is one of the most re- 

 markable discoveries of the last half century. That 

 they are identical in constitution, and that they are 

 transformable, is quite certain. The transformations 

 are actually going on in the operations of nature, as 



