IRON 



967 



them from the furnace till they really are waste, that is, until they have done their 

 work in the furnace. It is obvious that no combustible matter could be removed from 

 the lower regions of the furnace without seriously deranging the operations essential 

 1239 



1240 



to the reduction and smelting of the ore. In order to remove the gases effectually, 

 and without injury to the working of the furnace, and in such a state as will permit 

 their combustion to be effected with most advantage, the height of the furnace must 



