COMPOUND PRODUCTS. CHAP. i. 



SECTION XXV. 

 Ashes. 



WHEN vegetables are burnt in the open air the 

 greatest part of their substance is evaporated during 

 the process of combustion ; but ultimately there re- 

 mains behind, a portion which is altogether incom- 

 bustible, and incapable of being volatilized by the 

 action of fire. This residuum is known by the 

 name of ashes. 



They exhibit a sort of flaky appearance, of a 



whitish colour, soft to the touch, and crumbling 



between the fingers into an impalpable powder. 



They are without taste and without smell. 



Quantity They may be obtained from all parts of the plant, 



obtained , . ... . . r . . , 



from dif- but in different quantities from any given weight, 

 [flants not on ty m different plants but in different parts of 

 the same plant. Herbaceous plants, after being dried, 

 yield more ashes than woody plants ;* the leaves 

 more than the branches ; and the branches more 

 than the trunk.~f~ The alburnum yields also more 

 ashes than the wood ; and putrefied vegetables yield 

 more ashes than the same vegetables in a fresh 

 state, if the putrefaction has not taken place in a 

 current of water. + The result of Saussure's experi- 

 ments on this subject was the following : 



* Kirwan, Irish Trans, vol. v. p. 104. 

 t Ann. de Chim. vol. xix. p. 178. 

 J Sausswe, chap. ix. 



