302 THE SCIENTIFIC PAPERS OF 



produced, and, although we have no precise data from which we 

 could ascertain the latent heat absorbed in liquefaction, we can 

 hardly estimate it at more than 150 units per lb., or at -32 x 150 

 = 48 units, which, with the above 404*25, makes 452'25 units, 

 whereas 900 heat-units are available, as resulting from the cal- 

 culation above given, proving that '32 lb. of pure carbon would, 

 theoretically speaking, amply suffice to produce 1 lb. of puddled 

 bar from ordinary hematite ore, without counting, however, 

 losses of heat by radiation and from other causes. 



In the production of cast steel, three operations are essentially 

 involved, viz., the deoxidation of the iron, the fusion of the slags, 

 and the fusion of the metal itself with such proportion of carbon 

 and manganese as is necessary to constitute steel of the temper 

 required. 



The theoretical quantity of fuel required to accomplish these 

 operations would exceed that of making wrought iron by the 

 fusion of heated metal, which may be estimated at, say, 1000 



units, or at = '125 lb. of carbon per lb. of steel produced. 



8000 



which have to be added to the '32 lb. used in reduction. 

 - In fine, a ton of iron ought to be producible from hematite ore 

 with 6 "4 cwt. of carbonaceous matter, or say 8 cwt. of common 

 coal, and a ton of cast steel with 8'90 cwt. of carbon, or say 11 

 cwt. of coal. In giving these figures, I do not wish to imply that 

 they will ever be completely realised, but I maintain that, in all 

 our operations, we should fix our eyes upon the ultimate result 

 which theory indicates, which, owing to the imperfect means at 

 our command, we shall never completely reach, but should con- 

 stantly endeavour to approach. 



In taking incidental losses by radiation through imperfect com- 

 bustion and through imperfect absorption of heat into account, 

 we find that the actual consumption exceeds the theoretical 

 limits about three times, or that a ton of iron can practically be 

 produced with a consumption of 25 cwt. of coal, and a ton of cast 

 steel with 40 cwt. of coal, which consumption represents a great 

 reduction as compared with other methods of production. 



