26 



RATIO OF SPECIFIC HEATS. 



and a wad of absorbent cotton w (fig. 1). Two series of experiments were made: 

 one consisting of 5 determinations in June, 1893; a second series of 6 determina- 

 tions in February and March, 1894. In the first of these the pressure measure- 

 ments at the mercui-y manometer were read off on a cathetometer of only moderate 

 accuracy. The fine cathetometei- of Mr. Hauseraaun was not available until we 

 leached the second series. 



In the following tables 2, and 2.^ are the absolute values of the initial and 

 final temperatures, p, and ^g the corresponding pressures of the gas before and after 

 expansion, in cm. of mereuiy. « denotes the ratio of the two specific heats, and D 

 the variation of each value from the mean. 



Mean : « = 1.4004. 



Mean : « = 1.4004. 



The mean values of « of both series happen exactly to coincide. 



The mean value («) for data obtained with a platinum-blacked bolometer 

 strip was 



" = 1-3703- 



Hence the correction for the radiation discrepancy is 



'4 



The final result for air is therefore 



X = 1.4025. 



