4 1 4 On the Heat developed in Combustion 



pounds of carbonic acid, which are the product of the 

 combustion of i pound of charcoal, is that of 3811 F. 

 at the moment of its formation, we have only to ascertain 

 how much the temperature of this acid ought to be 

 diminished by the mixture of the nitrogen which must 

 necessarily be there when the oxygen employed in the 

 combustion of the charcoal is furnished by the atmos- 

 pheric air. 



As, in the atmospheric air, every pound of oxygen 

 is mixed with 3.7619 pounds of nitrogen, the 2.5714 

 pounds of oxygen employed in the combustion of i 

 pound of charcoal ought to be mixed with 9.6735 

 pounds of nitrogen ; consequently all the heat devel- 

 oped in the combustion of i pound of charcoal will 

 be found divided between 3.5714 pounds of carbonic 

 acid and 9-6735 pounds of nitrogen. 



And as the specific heat of the carbonic acid is to that 

 of nitrogen as 1.0459 to -73^) tn ^ s heat will be divided 

 between these two substances in the proportion of 

 (3-57!4 X 1.0459 =) 3.7354 to (9 6 735 X 0.7036 ) 

 6.8062, which is in the proportion of i to 6.8221 or of 

 3.5714 to 6.5075 ; and thence we may conclude that 

 the temperature of the mixture of 3.5714 pounds of car- 

 bonic acid and of 9.6735 of nitrogen would be the same 

 as if we had mixed with the 3.5714 pounds of carbonic 

 acid 6.5075 pounds more of this same acid, making to- 

 gether 10.0789 pounds of carbonic acid. 



Now, as the heat developed in the combustion of i 

 pound of charcoal was sufficient to raise the temperature 

 of the 3.5714 pounds of carbonic acid coming from this 

 combustion to that of 3811 F., this same quantity of 

 heat ought to be sufficient to raise the temperature of 

 10.0789 pounds of carbonic acid to the temperature 

 of 1350 F. 



