284 
SPECIFIC HEAT OF GASES. 
The vessel observed for every ten minutes. But notwithstanding this 
was heated . . , , , , . , , 
tin its rate of precaution a very long time would have been required to produce 
change was tb e maximum, and it would have been extremely difficult to 
the same as 
well above as ascertain when it had been really attained. We found it more 
maximum convenient to stop the proceeding as soon as, by the progress of 
heating, we judged that only two or three tenths of a degree 
were wanting to arrive at that maximum ; and then we elevated 
the temperature of the calorimeter by the approach of an 
heated body, by a quantity rather greater than the maximum, 
at which period the calorimeter being left to itself, lost some of 
its temperature, notwithstanding the current of gas was con- 
tinued to be passed through it. We observed also the progress 
of this refrigeration for every ten minutes, and we stopped the 
experiment as soon as the retardation of the cooling indicated 
that the calorimeter was at the same distance from the term, at 
which its temperature would have been stationary, as it was in 
the preceding experiment. Taking, therefore, the mean 
between the final observations, we obtain with accuracy the 
' term at which the temperature of our calorimeter would have 
been stationary, if the heating action of the gas had been con- 
tinued for a sufficient length of time. 
The temperature of the calorimeter was determined by means 
of a thermometer, with a cy lindrical reservoir, nearly of the same 
obtained, &c. length as that of the calorimeter itself, in order to shew the 
mean temperature of all the strata of the w T ater. This instru- 
ment was sufficiently sensible to indicate clearly 0 02 of a 
degree (centigrade.) We shall now proceed to shew, what 
methods we pursued to produce a constant current of gas, to 
give it an invariable temperature, to determine the temperature 
of this current, on its entering and issuing out from the calori- 
meter, and to appreciate the causes which are independently of 
this current, might raise the temperature of the calorimeter. 
Temperature, 
of the calori- 
( To he Continued.) 
SCIENTIFIC 
