98 THE ADDRESSES, LECTURES, ETC., OP" 



in excess of the theoretical quantity required for these purposes 

 than is the case with regard to the production of steam power and 

 to domestic consumption. Taking the specific heat of iron at '114 

 and the welding heat at 2,900 Fahrenheit it would require '114 

 x 2900 = 331 heat units to heat 1 Ib. of iron. A pound of pure 

 carbon develops 14,500 heat units, a pound of common coal say 

 12,000, and therefore one ton of coal should bring 36 tons of iron 

 up to the welding point. In an ordinary re-heating furnace a ton 

 of coal heats only If ton of iron, and therefore produces only * T 

 part of the maximum theoretical effect. In melting one ton of 

 steel in pots 2\ tons of coke are consumed, and taking the melting 

 point of steel at 3600 Fahrenheit the specific heat at *119 it 

 takes '119 x 3600 = 428 heat units to melt a pound of steel, and 

 taking the heat producing power of common coke also at 12,000 

 units, one ton of coke ought to be able to melt 28 tons of steel. 

 The Sheffield pot steel melting furnace therefore only utilises ^th 

 part of the theoretical heat developed in the combustion. Here 

 therefore is a very wide margin for improvement, to which I have 

 specially devoted my attention for many years, and not without 

 the attainment of useful results. Since the year 1846, or very 

 shortly after the first announcement of the dynamical theory, I 

 have devoted my attention to a realisation of some of the economic 

 results which that theory rendered feasible, fixing upon the 

 regenerator as the appliance which, without being capable of re- 

 producing heat when once really consumed, is extremely useful for 

 temporarily storing such heat as cannot be immediately utilised, in 

 order to impart it to the fluid or other substance which is employed 

 in continuation of the operation of heating, or of generating 

 force. 



Without troubling you with an account of the gradual progress 

 of these improvements, in which my brother Frederick has taken 

 an important part, I will describe to you shortly the furnace which 

 I now employ for melting steel. It consists of a bed made of very 

 refractory material, such as pure silica sand and silica or Dinas 

 brick under which four regenerators (or chambers filled with 

 checkerwork of brick) are arranged in such a manner, that a 

 current of combustible gas passes upward through one of these re- 

 generators, while a current of air passes upwards through the ad- 

 joining regenerator, in order to meet in combustion at the entrance 



