S/A WILLIAM SIEMENS, F.R.S. 26 1 



the iron, and generating into a gaseous form the fixed oxygen in 

 the ore and the fixed carbon in the coke, so as to allow of their 

 chemical combination taking place. Considering first the heat 

 n in i red for melting the iron taking the total heat developed in 

 funning carbonic oxide as 4000 Fahr. units, and in forming car- 

 bonic acid 14,000 units the combustion of 1 Ib. of carbon into 

 the mixture of -Jths carbonic oxide and |th carbonic acid would 

 develope 6000 Fahr. units of heat ; and therefore taking the 

 specific heat of iron at 0*12 in comparison with water, and 

 assuming the temperature to which the melted metal was heated 

 (including its latent heat) to amount to 4000 Fahr. it would be 



. . , 20x4000x0-12 



found that to melt 1 ton of iron required 1*60 



6000 



cwts. of carbon. This estimate was evidently on the safe side, as 

 no account was taken in it of the further heat necessary for keep- 

 ing the iron melted in the hearth till casting time, which would 

 have raised the quantity of carbon nearer to the estimate of 

 2*70 cwts. given by Mr. Bell. The 1*60 cwts, received a satis- 

 factory confirmation from actual results which he had obtained in 

 the working of cupolas, showing that the calculation was sub- 

 stantially correct. Next with regard to the cinder, taking its 

 specific heat at 0'20, which he believed was below the mark, and 

 assuming the total heat for melting it to be the same as that for 

 iron, namely 4000 Fahr., it would be found that the melting 

 of 31 cwts. of cinder per ton of iron made would require 



31 x 4000 x 0-20 = 4 . 13 cwtg Qf carbon In re fe r ence to the third 



6000 



supply of heat required in the blast furnace for transforming 

 into a gaseous state the fixed oxygen in the ore and the fixed 

 carbon in the coke it must not be overlooked that in the combi- 

 nation of carbon with oxygen, heat was only evolved in conse- 

 quence of a reduction of volume occurring, and in proportion to 

 the extent of that reduction of volume. But this could only take 

 place when both bodies were already in a gaseous state ; and 

 accordingly by the combination of solid carbon with gaseous 

 oxygen in the proportion of one equivalent of each, producing 

 carbonic oxide, the amount of sensible heat evolved (4000 units) 

 was less than half of that (10,000 units) which was further 

 developed when a second equivalent of oxygen entered into com- 



