262 THE SCIENTIFIC PAPERS OF 



bination with the gaseous carbonic oxide so as to form carbonic 

 acid ; because more than half of the total heat developed in the 

 formation of the carbonic oxide (6000 out of 10,000 units) was 

 rendered latent by the solid carbon having first to be volatilised 

 before it could combine with the oxygen. The absorption of 

 latent heat was necessarily still greater when the fixed oxygen in 

 the ore had to be made to enter into combination with the fixed 

 carbon in the coke, because a supply of heat had first to be 

 absorbed sufficient for volatilising both the fixed oxygen and the 

 solid carbon ; and he had found practically that, where a mixture 

 of ore and carbon was exposed in a close retort to the heat of a 

 furnace, it was necessary to supply a large amount of heat in 

 order to bring about a combination of the elements. In the com- 

 bination of the 8'50 cwts. of oxygen of the ore in the blast furnace 

 with the 5'31 cwts. of carbon of the fuel, two processes of opposite 

 effect had to take place : on the one hand, the combustion of the 

 carbon into the final mixture of |-ths carbonic oxide and ^th car- 

 bonic acid, developing 6000 Fahr. units of heat per Ib. of carbon, 

 would give a total of 5'31 x 112 x 6000 = 3,568,320 units of heat 

 developed ; but on the other hand, the volatilisation and separation 

 from the iron of the fixed oxygen of the ore required the absorp- 

 tion as latent heat of, he believed, not less than 6000 Fahr. units 

 of heat per Ib. of oxygen, and the total absorption of heat thus 

 occasioned would amount to 8'50 x 112 x 6000 = 5,712,000 units 

 of heat absorbed. The difference 2,143,680 units, being an excess 

 of heat absorbed, required therefore to be compensated by an extra 



consumption of 2 ' 143 ' 68Q = 357 Ibs. or 3'19 cwts. of carbon. 

 6000 



These three amounts added together gave 1'60 + 4'13 + 3'19 = 

 8'92 cwts. of carbon, to which had to be added the 7 '43 cwts. 

 required for chemical combination with the oxygen in the ore and 

 for carbonising the pig metal, making 16'35 cwts. of pure carbon. 

 A further addition was required of 10 per cent, or 1'63 cwts. for 

 ashes and water in the coke actually employed in the blast fur- 

 naces ; and also another 10 per cent, or T63 cwts. for effecting 

 the calcination of the limestone and completing that of the ore, 

 and to allow for vaporising the moisture in the materials and for 

 loss by radiation. The total amount was thus brought up to 

 19' 61 cwts. as the theoretical minimum consumption of coke 



