142 
SPECIFIC HEAT OF GASES. 
Influence of 
the tube. 
of gaSj at its entrance into the calorimeter, has induced us to 
allow the least possible length to that part of the intermediate 
conducting tube between the tube tilled with vapour and the 
calorimeter; by this means, notwithstanding the causes which 
might operate to lower* the temperature of the thermon>eter, 
we have, however, sucreeded in keeping it up to a temperature 
nearly equal to that of boiling water, and as we were certain that 
the real temperature of the current of gas could not be belovv 
that of the thermometer placed in the centre cf the tube, nor 
superior to that of boiling water, we could not commit any 
essential error in estimating it as equal to the medium between 
these two temperatures. 
On the other hand we were certain, that the current of gas, 
in passing through the spiral tube of the calorimeter, would lose 
all the excess of its heat, and would go out exactly of the same 
temperature as the water with which it is filled. We there- 
fore concluded, that the heat left by the current of gas, was 
equal to the excess of its temperature at its entrance into the 
calorimeter, over that of the calorimeter itself. 
Section IV. 
Influence of the title employed to re-heat the gas on the tempera- 
ture of the calorimeter. 
There was an inconvenience in shortening the intermediate 
tube, [between the tube filled with vapour and the calorimeter ; 
the latter was heated by direct communication, independent of 
the heat communicated to it by the gas which circulated in its 
interior. To diminish the quantity of heat given by this 
means, we employed for this part of the canal a tube of glass, 
as being formed of a substance no great conductor of caloric. 
• Whatever precaution we could use, we could not, however, 
prevent the calorimeter experiencing some influence from the 
tube employed to heat the gas : but we endeavoured to ascer- 
tain correctly what degree of heat was to be assigned to this 
cause ; and we found it was such as would keep the tempera- 
ture of the thermometer 2° 5' above that of the sui rounding 
air. 
(To le Continued.) 
