266 THE SCIENTIFIC PAPERS OP 



affects the economy in a very slight degree. My view is, that ifc 

 would affect it very nearly in the same degree as an increase from 

 60 to 000 would affect it. I come to this conclusion for this 

 reason. I view the general result of combustion in the blast fur- 

 nace, and compare it with the general result of combustion in the 

 heating stove. In the heating stove, you burn fuel into carbonic 

 acid, and for every pound you burn, 13000 Fahr. units are evolved. 

 This amount of heat absorbed by the air is carried into the blast 

 furnace. Now, the action of the blast furnace the combustion 

 carried on there is accomplished in a very different way. The 

 quantity of heat imported into the blast furnace counts for more 

 than double that expended in the heating stove. Considering 

 that the capacity and the specific heat of the air at the higher 

 and lower temperature is the same within a fractional amount, 

 for every degree Fahr. by which the temperature of blast is 

 increased, a proportionate amount of stone ought to be taken 

 into the blast furnace. As Mr. Bell admits that by increasing 

 the temperature of the blast he gets a higher proportion of carbonic 

 acid at the top of his blast furnace, he admits that the effect will 

 be an increase in ratio. In the measure in which you increase the 

 temperature of the blast, the amount of carbonic acid at the top 

 of the blast furnace will augment, and the gas at the top of the 

 blast furnace will diminish in volume. I am satisfied that an 

 increase in the temperature of the blast must be highly economical 

 in the results of the furnace. 



In the adjourned discussion of tJie same Paper 



MR. C. W. SIEMENS said : With regard to the question raised 

 by Mr. Cochrane, I think I may be able to throw some light upon 

 it by putting it in this way. If Mr. Cochrane finds the gases 

 escape at 700 at the top, and if he was then to throw in a load of 

 ironstone, he would, no doubt, effect a temporary reduction of that 

 temperature ; but long before a corresponding amount of ore was 

 smelted to make room for a further charge, the temperature of 

 the escaping gases would have risen again to 700 or rather more. 

 In order to arrive at real temperature of issue, the ore should 

 be fed, or supposed to be fed, in a continuous manner ; although, 

 for the purpose of experiment, you can put in a heavy charge 



