Sffi WILLIAM SIEMENS, F.R.S. 135 



beyond 1,000, was based upon a misconception. They showed 

 that each degree of extra heat in the blast produced a diminishing 

 amount of saving in coke per ton of iron ; but they lost sight of 

 this circumstance, that the quantity of blast used per ton of 

 iron was greatly reduced when raised to a high temperature, 

 the quantity of blast used being proportionate to the amount of 

 carbon burnt in the blast furnace. In effecting, therefore, a re- 

 duction of the coke from 24 cwt. to 20 cwt., the amount of blast 

 used per ton of iron was diminished in the same proportion, and 

 1" of temperature added to the blast did not represent the same 

 amount of heat as 1 of heat communicated to blast of a lower 

 temperature, when relatively a larger quantity was used ; but if 

 the effect of 1 unit of heat added to the blast in the stove at 

 various degrees was taken into account, it would be found that as 

 much saving of coke was effected in the blast furnace by adding to 

 the blast above 1,000 as there was by adding 1 unit of heat below 

 that limit. There was the further important saving of fuel and 

 engine-power, in effecting an increased duty with a given amount 

 of blast, which had been neglected in these calculations. 



It would take up too much time to go further into this some- 

 what complex question, as it would be necessary to take into 

 account the increased proportions of the carbonic acid gas and the 

 lower temperature of the waste gases which resulted from high 

 temperature of blast ; but the question resolved itself into a simple 

 one if it was looked at from a general point of view that each 

 unit of heat given to the blast before entering the furnace must 

 save fuel equivalent to between 2 and 3 units of heat in the furnace, 

 and moreover, that a much cheaper fuel was available in the stoves 

 than within the blast furnaces. 



