THE CONQUEST OF NATURE 



carbon. In this respect it resembles cast iron, steel 

 having a smaller amount of carbon. Wrought iron, 

 on the other hand, contains no carbon at all, or at 

 least only a trace of it. But whatever the ultimate 

 destiny of iron ore whether it is to become aristo- 

 cratic manganese steel, or plebeian cast iron it must 

 first pass through certain processes before being 

 "converted." 



To extract the pure iron from the iron ore it is nec- 

 essary to heat the ore in a furnace containing a certain 

 quantity of coal, coke, or charcoal, and limestone. 

 The furnaces used in this process are known as blast- 

 furnaces, and in these about one ton of iron is extracted 

 for every two tons of Lake Superior ore, one and a 

 quarter tons of coke, and half a ton of limestone used. 

 These quantities are by no means constant, of course, 

 but they may be taken as representing roughly the 

 relative amounts of material that must be fed into 

 the furnaces. 



Like everything else in the world of iron and steel, 

 these blast-furnaces have undergone revolutionary 

 improvements during the past quarter of a century. 

 From being most dangerous and destructive struc- 

 tures causing frightful loss of life and producing only 

 about one ton of iron a day for every man working 

 about them, as formerly, they have now become rela- 

 tively harmless monsters, capable of turning out six 

 times that quantity of ore for each man employed. 



The older blast-furnace was a huge, chimney-like 

 structure, perhaps a hundred feet high, into which the 

 ore, coal, and limestone were poured. Most of the 



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