226 



ME. W. F.. G. SWANN ON THE SPECIFIC HEATS OF AIR AND 



watts supplied, corrected for the heating effect of the leads. As is shown above, it 

 is only necessary in the calculations to know the values of 



[dE./M, + C'.EVS^i] [1 + i (<* + &) + '], 



where the symbols have the significance already accorded to them, but, for the sake 

 of clearness, the corrected values of CE are recorded for each run in the table. 



The fourth column gives the mean temperature of the gas over the range ot 

 temperature through which it was heated. The sixth column gives the values of h 

 in watts per degree. The seventh and eighth columns give the values of the specific 

 heat, the numbers in the latter column being reduced to a standard temperature, and 

 the last column gives the deviation of the specific heat from the mean value, the 

 error being reckoned as a percentage on the specific heat. In addition to the runs 

 taken for the determination of the specific heats, runs with intermediate rates of flow 

 were taken for the purpose of testing the linear relationship between CE/S0 and the 

 flow. For the sake of clearness, however, the data for these runs are omitted from 

 the following tables, and are collected together in tables by themselves on p. 229. 



The pressure at which the specific heat was determined, may be taken as that due 

 to 76 cm. of mercury, since there was practically no difference between the pressure 

 in that portion of the calorimeter where the rise in temperature took place and the 

 atmosphere. The value of 3S/3P may be calculated, and it can easily be shown that 

 a change of 1 cm. in the barometric height cannot produce a change in S of more 

 than about I part in 40,000, so that it is unnecessary to take into consideration 

 the fluctuations of the atmospheric pressure during the experiments. 



(21) ABRIDGED Table for the Main Calorimetric Experiments on Air. 

 Table I. Air Temperature. 



Mean value for the specific heat at 20 C. = 0'24137 cal. per gr. degree. 



