VEGETABLE SUBSTANCES. 127 



Gum consists of carbon, oxygen, and hydrogen. 



Sugar. — The sugar in common use is extracted 

 from a cane that grows only in warm climates, called 

 the sugar-cane ; but it may also be procured from 

 all sweet vegetables. The American maple-tree 

 affords a great deal of sugar, and this useful sub- 

 stance has been made from the beet-root, car- 

 rots, &c. 



All sugars consist of carbon, oxygen, and hydro- 

 gen ; but it appears that sugar from the cane 

 contains more carbon than other sugars. That 

 obtained from some vegetables will not crystallize. 

 Sugar is first prepared in the countries where it is 

 grown, by boiling the juice and evaporating ; one 

 part of the juice crystallizes, and forms the raw or 

 muscovado sugar ; the other part, the molasses or 

 treacle, will not crystallize. The raw sugar when 

 brought to this country is re-dissolved and crystal- 

 lized again, which is called refining, by which the 

 loaf-sugar is made. To whiten it completely, clay 

 is put upon the tops of the conical pots in which 

 the sugar has granulated, which allows water to 

 percolate through, and thus drain off the last re- 

 mains of the molasses. This is called claying the 

 sugars. 



Fecula, or starch. — This substance is contained 

 in many seeds and roots. It is separated by bruising 

 the vegetables containing it in water, and stirring 

 them together. The fecula separates in the water, 

 making it appear turbid. The white fluid is pour- 

 ed off and suffered to settle ; the starch subsides 

 to the bottom. Starch is made mostly from wheat; 

 it is also made form potatoes. Starch is a white 

 substance, insoluble in cold water, but soluble 

 in warm. Its solution is gelatinous, and when 

 solid it resembles gum : this, when dry, is a com- 



