CHAPTER VI 



Ashes and Soot 



Ashes. 



These are the waste products left from combus- 

 tion. They contain the mineral matters of the 

 substances burnt and vary in richness, therefore, 

 according to the material from which they are 

 derived. 



Wood Ashes. — Wood ashes are the mineral 

 matter which is left when wood is burnt. 



The quantity of ash varies considerably, according 

 to the vegetable matter from which it is produced. 



Thus, leaves in lOO parts of dry matter give 

 15 per cent, ash ; sapwood in 100 parts of dry 

 matter give 3 per cent, ash ; bark in 100 parts of 

 dry matter give 7 per cent, ash ; heart in 100 

 parts of dry matter give 5 per cent. ash. 



The more herbaceous the matter the higher the 

 proportion of ash. 



The composition of ash varies considerably 

 according to the species of wood from which it is 

 derived — oak, birch, fir, etc. ; according to the part 

 of the wood used — leaves, bark, etc. ; and also 

 according to the age of the material burnt. 



The chlorures being eliminated together with a 



82 



