284 PHENOMENA DEPENDENT ON MOLECULAK PATHS 105 



the value of the coefficient K as exactly as possible. This 

 calculation, in which the mean values have been taken with 

 due regard to Maxwell's law of distribution of speeds, 

 has given 



f = 1-6027 yc. 



If we compare the mathematical calculation which has 

 led to this larger value of the coefficient * with that here 

 deduced in an elementary way, the difference will perhaps 

 astonish us, and give rise to the objection that in laying 

 down the mathematical formula we have taken into account 

 the kinetic energy of the molecular motion only, while at 

 the end we have substituted for this kinetic energy simply 

 the specific heat at constant volume c multiplied by the 

 absolute temperature. This procedure seems to contradict 

 the view as to the ratio of the molecular energy to the total 

 energy which is put forward in 53 ; for it is there proved 

 that the kinetic energy of the rectilinear motion of the 

 molecules of a gas forms only a part of the whole energy 

 contained in the gas. We might therefore be inclined to 

 assume that the calculation in which account is taken only 

 of the energy of the molecular motion will give a result, the 

 validity of which should be limited to the propagation of 

 that energy only ; and that we should therefore consider the 

 value 1'6027 of the coefficient K to apply only to the propa- 

 gation of the molecular energy ; and we might consider it 

 possible that the remainder of the energy forming the heat 

 of the gas, and therefore the energy of the motions which 

 the individual particles execute within the molecules and the 

 whole potential energy, may be propagated with a different 

 speed, either smaller or larger, than that of the kinetic 

 energy. 



In fact, the assumption has many times been made, 

 especially by Stefan 1 and Boltzmann, 2 that the kinetic 

 energy of the molecular motion is passed on from place to 

 place with greater speed than the remaining energy, which 

 in Chapter V. we have termed the atomic energy. We 



1 Wien. Sitzungsber. 1875, Ixxii. Abth. 2, pp. 74, 75. 

 - Ibid. p. 458 ; Pogg. Ann. 1876, clvii. p. 457. 



