THE COMPOSITION OF PLANTS. 



29 



54. When plants are burned with free access of 

 air, the sulphur and phosphorus are oxidized, and 

 remain in the ash with the metals. Chlorine and 

 silicon are also found in the ash. This ash, or inor- 

 ganic matter, varies in quantity from about one-half 

 to one per cent, in some kinds of wood to from 

 15 to 18 per cent, in tobacco. The following table 

 shows about the average percentage of ash in a 

 number of vegetable products : 



Percentage of Ash in Dried Products. 

 Cotton, lint i.o Red clover 6.8 



" seed 8.9 Cabbage 8.0 



Wheat, grain 1.9 Irish potatoes 4.3 



Turnips 10.0 



Tobacco 15-18 



straw 5.0 



Indian corn 1.5 



The elements that enter into the composition of 

 the ash are given in the following table : 



Percentage Composition of the Ash of Plants. 



* Average of several analyses of Kentucky tobacco made in 

 the laboratory of Vanderbilt University by Messrs. Hobbs and 

 Wooldridge. 



