252 



METALS, 



and also a certain proportion of some flux, usually limestone. The 

 lime forms a glass with the silicious impurities of the ore, while the 

 carbon (first becoming carbonic oxyd) takes the oxygen which is in 

 combination with the metal. A small proportion of the carbon also en 

 ters into the metal after it is reduced, giving it the fusibility it has aa 

 cast iron. 



Before describing the process, a brief description may be given of a 

 blast furnace.* The following figure (excluding the structure on the 

 right, to be afterwards explained,) represents the essential features of 

 furnace, in an exterior side view. 



1 



It is essentially a broad truncated four-sided pyramid of brick and 

 stone, containing within a cavity where the ore is heated and reduced 



* I am indebted to Mr. S. S. Haldeman for the following figures an 

 their descriptions. They are l-20th of an inch to a foot. The furnaco 

 was built for anthracite, as is explained beyond. It is a model of the 

 fine works near Columbia, Pa., owned bv the Messrs. Haldeman. 

 20* 



