92 FIRESIDE SCIENCE. 



when the action subsides, there remains a black, 

 crispy mass of charcoal, in every respect like that 

 which results from the combustion of wood. From 

 whence comes this charcoal ? It is not derived 

 from the air ; it is not supplied from the heat. It 

 exists in the sugar, and is only developed by the 

 agency of heat. Paradoxical as it may seem, beau- 

 tiful white sugar is largely made up of black carbon ; 

 but its color is hidden so that we cannot see it, and 

 this brings us to consider the chemical nature of a 

 lump of sugar. Sugar is a ternary compound ; that 

 is, one made up of three elements, carbon, hydro- 

 gen, and oxygen. There are two prominent va- 

 rieties, or kinds, which differ not in elementary 

 constitution, but in the proportion of the atoms, or 

 in the method of grouping the atoms : 

 Cane sugar, or sucrose . . . Ci2 H22 On 

 Grape, or starch sugar, glucose . Ce Hi2 Oe (or Cia Hs4 Oia) 



The difference between the sugars will be seen 

 at once from a glance at the symbols and figures. 

 Now this seems very slight, and yet they are quite 

 dissimilar in effects. The two kinds mentioned 

 are not the only ones known, as three or four others 

 have been already distinctly pointed out. One kind 

 of sugar abounds in the sugar-cane, in beet-roots, 

 and parsnips ; this is the sucrose. Another kind 

 constitutes the sweet matter of many fruits, and 

 may also be prepared by acting upon starch with 



