in Combustion, and in the Condensation of Vapours. 305 
It remains to determine the temperature which we might 
hope to attain by burning charcoal with a¢mospheric air. 
As we have found that the temperature of the 3°5714 
pounds of carbonic acid which are the product of the 
combustion of 1 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 dimi- 
nished by the mixture of the azote which must necessarily 
be there when the oxygen employed in the combustion of 
the charcoal is furnished by the atmospheric air. 
As, in the atmospheric air, every pound of oxygen is 
mixed with 3°7619 pounds of azote, the 2°5714 pounds of 
oxygen employed in the combustion of 1 pound of char- 
coal ought to be mixed with 9:6735 pounds of azote’: 
consequently all the heat developed in the combustion of 
1 pound of charcoal will be found divided between 3°5714 
pounds of carbonic acid and 9°6735 pounds of azote. 
And as the specific heat of the carbonic acid is to that of 
azote as 1°0459 to 0°7036; this heat will be divided be- 
tween these two substances in the proportion of (3°5714 x 
1°0459=) 3°7354 to (9°6735 x0°7036=) 6°8062, which 
is in the proportion of 1 to 1°8221 or of 3*5714 to 650753 
and thence we may conclude that the temperature of the 
mixture of 3°5714 pounds of carbonic acid and of 9°6735 
of azote 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 together 10°0789 pounds of carbo- 
nic acid, 
Now as the heat developed in the combustion of one 
pound of charcoal was sufficient to raise the temperature of 
the 3°5714 pounds of carbonic acid coming from this com- 
bustion 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. 
This is, according to the results of this calculation, the 
highest temperature which we ought to expect to find 
amid the strongest charcoal fire fed by atmospheric air. 
But we are very certain that the intensity of the heat of 
the strongest charcoal fire is far superior to the above cal- 
culation: consequently we are authorized to conclude that 
the capacity for heat of the carbonic acid, and that of the 
azotic gas, are much diminished when these elastic fluids are 
exposed to a very high temperature. 
If, in endeavouring to discover the limit of intensity of 
a charcoal fire, 1 have supposed the fire to be very large, 
. Vol. 42. No,186. Oct, 1813. U it 
