THE CONQUEST OF NATURE 



OPEN-HEARTH METHOD 



In the open-hearth method the metal from the blast- 

 furnaces is not sent to the converter, but is poured 

 into oven-like structures built of fire brick, and in these 

 heated to a terrific temperature. This heat has the 

 same effect upon the metal as the blast of air in 

 the Bessemer converter, and this open-hearth process 

 has become very popular for manufacturing certain 

 kinds of steel. While in the method of application this 

 process differs greatly from that of Bessemer, it differs 

 largely in the fact that the oxygen necessary to burn off 

 the carbonic oxide, silicon, etc., is made to play over 

 the molten mass instead of passing through it. 



It has been noted that the old type of blast-furnace 

 gave off great quantities of combustible gases which 

 became waste products. Even gases containing 

 something like 20 or 25 per cent, of carbonic acid may 

 be highly inflammable, and thus an enormous quan- 

 tity of valuable fuel was constantly wasted. In some 

 furnaces, to be sure, they were put to practical use for 

 heating the blast, but as the quantities given off were 

 greatly in excess of the amount necessary for this pur- 

 pose, there was a constant loss even with such furnaces. 



Quite recently it has been found that the gases can 

 be used directly in gas engines, developing three or 

 four times as much energy in this way as if they were 

 used as fuel under ordinary steam boilers. These 

 engines are now used for operating the rolling-mill 

 machinery, and the machinery of shops adjoining the 



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