238 



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



The value of S S may be obtained from the equation S S = n(n+l) cp/0. 

 Assuming n = 2, c = 376, p = 76/75, we have S-S = 0'00113 cal. Hence 

 S = 0'20937 cal. per gr. degree. Adding the gas constant K = 0'0450 for C0 2 to 

 JOLY'S value s = 0'1665, we obtain S = 0'2I15, which differs from the value deduced 

 above by I'O per cent, of the value of S. The agreement is as good as can be 

 expected, for it is hardly legitimate to assume a linear law for the variation of S over 

 the range 20 C. to 100 C. when the variation over that range amounts to 10 per 

 cent, of the value of S. Further, the two values of s a obtained from JOLY'S experi- 

 ments show a lack of agreement amounting to 0'5 per cent, of their values. 



The following table gives the approximate values of the specific heat of carbon 

 dioxide at 50 C., deduced from the observations of various experimentalists: 



The last three are in very good agreement, but the rate of increase given by 

 HOLBORN and HENNING is only 0'0133 for 100 C. in place of 0'0240 by the present 

 method. REGNAULT finds the increase 0'0275, and WIEDEMANN Q'0217. 





