PHOSPHORESCENT ACTIVITY 293 



minutes, if this process actually takes place. It 

 is a matter of experience that the internal energy- 

 is not thus dissipated away. Why, then, does it 

 not take place ? The Boltzmann-Maxwell Law, 

 which states that the partition of energy is equally 

 divided between various degrees of freedom in the 

 molecule, does not permit us to assume that a 

 molecule has more than a very small number of 

 degrees of freedom. If very complex aggregates of 

 molecules exist, as in the case of phosphorescence, 

 this transference of energy may to some extent 

 take place until the aggregates are broken up. 

 In the case of non-phosphorescent but luminous 

 gases these may, and probably do, neverthe- 

 less exist, but only for a brief period, during 

 which they radiate some of their energy to the 

 aether. In this manner a number of degrees of 

 freedom of luminous molecules would be very 

 different from those of non-luminous molecules, and 

 if there are a large number of luminous molecules 

 in a gas, the ratio of the specific heats in a 

 luminous gas would be quite diiferent from that 

 in a gas in a non-luminous state. 



The existence of such large, more or less per- 

 manent, molecular groups, as in the case of phos- 

 phorescent bodies, will enable them to transform 

 their energy of translation to the aether, whilst 

 their small number prevents their temperature 

 from falling below that of surrounding objects. 



If, then, the duration of the phosphorescence is 

 very great, it would result from the fact that such 



