376 



WOOD-ASHES. 



ashes left by pure guano are white, or nearly so ; 

 while, if soil or brickdust has been added, the oxide 

 of iron, which they always contain, will give the 

 ashes more or less a red-brown color. 



1006. The composition of wood-ashes varies very 

 considerably, according to the wood from which it is 

 obtained. The composition of three kinds of wood- 

 ashes, as given by Sprengel, is : — 



1000 



1000 



1000 



1007. In the process for making potash or pearl- 

 ash (199), the greater part of the soluble salts con- 

 tained in the wood-ashes is washed out ; the remainder 

 is a valuable manure, and often contains a consider- 

 able quantity of phosphoric acid. The refuse ashes 

 from soap factories consist of the same matters. The 

 following table exhibits the composition of three 

 kinds of ** lixiviated ashes," according to Berthier : — 



