SPECIFIC HEAT OF GASES. 
1283 
turns, the two extremities of which terminate without a side the of th . e » as t0 a 
maximum. 
vessel, one above, and the other below j and if a regular cur- 
rent of gas, delivered at an uniform and elevated temperature., 
be passed through the pipe, this current may be considered as a 
source of uniform heat, and the cylinder as the body A, con- 
sequently, if the same experiment be repeated upon each of 
the gases, each current will raise the temperature to a fixed 
point, where it will remain stationary ; and, upon arrival at 
this point, it will follow, from the principles laid down, that 
the quantity of heat communicated to the cylinder, in a given 
time, by each current, will be proportional to the excess of 
that stationary temperature beyond that of the surrounding 
medium. 
We shall, therefore, obtain, with great precision, by this Reference of 
means, the comparative specific heat of each of the gases, effe^to^L 
which can be subjected to this mode of examination. There ter as the stan« 
will be two methods of afterwards comparing with them that of 
water. The first consists in submitting the cylinder we have 
here described, and shall distinguish by the name of calo- 
rimeter, to the action of a current of water, regularly trans- 
mitted w'ith a velocity so low, that it shall scarcely exceed, in 
its effect, that of the gases $ and the second method consists in 
determining, by calculation, the real quantity of heat which 
the calorimeter arrived at, its stationary temperature loses in a 
given time. For we have shewm, that, when arrived at this 
point, the heat which it loses in a given time, is equal to that 
which it receives from the current of gas in the same time. 
It may be conceived, that, a long time would have been Means of pre- 
consdmed in raising the temperature of the calorimeter through J^in^th? 
the whole interval up to the stationary point, by the mere effect maximum, 
of current of heated gas ; and that the observation of its heat- 
ing, during this time, would have been of no value. We, 
therefore, preferred to elevate its temperature, in the first 
instance, by a spirit lamp to a term which previous trials had 
shewn us to be near that at which the temperature would be 
stationary. It was then left without the lamp, and exposed to 
the current of heated gas, and its augmentation of temperature 
observed 
