IRON 



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as 12 kilogrammes of coke have, it is stated, been saved for every 100 kilogrammes of 

 limestone, which was replaced by 63 of burnt lime. 



Mr. Lowthian Bell considers that the economy in the use of caustic lime in blast- 

 furnaces depends chiefly upon the difference in price in the fuel used, as the lime is 

 burnt with small coal in kilns, saving an equivalent of coke, a more expensive fuel in 

 the furnace. He has, however, found that when caustic lime is exposed to carbonic 

 acid at a red heat, there is a re-formation of carbonate of lime to some extent, which 

 is decomposed again at a higher temperature, and that therefore the fuel saved in the 

 furnace is less than the calorific equivalent of that required for burning the lime. 



The greatest development in blast-furnace economy has taken place in the Cleve- 

 land district, where the amount of fuel required for the production of a ton of pig-iron 

 has been reduced from 35 to 40 cwts. of coke to 20 cwts. and even in some cases as low 

 as 17 cwts. This saving has been produced by increasing both the dimensions of the 

 furnaces and the temperature of the blast, the waste gases being in all cases econo- 



3K 



