MOLECULAR AGGREGATION 253 



Hence, if the number into molecules with a par- 

 ticular free period is increased, the absorption is 

 increased, and if the number is diminished the 

 absorption for this particular period is also 

 diminished, whereas if the number of molecules 

 executing vibrations of a particular period remains 

 constant, the absorption for that particular period 

 likewise remains constant at all temperatures, irre- 

 spective of the intensity of the radiation. 



The problem, however, is not quite so simple 

 as this ; at first sight the number of molecules 

 executing a particular vibration does not remain 

 constant, as the temperature rises even if there 

 be no association or dissociation ; for as the tem- 

 perature rises and the translational velocity in- 

 creases, as in the case of billiard balls, the 

 vibrations become converted into shriller and 

 shriller ones. And this would increase according 

 to some definite law connecting the frequency 

 with the temperature. Various attempts have 

 been made to determine the law connecting the 

 radiation in any particular part of the spectrum 

 with the temperature. The assumptions, however, 

 which must be made to get the right result are 

 not altogether satisfactory ; and it is desirable 

 that the relation between emission and absorption 

 should be more clearly understood. Thus, for 

 any particular molecule as the temperature is 

 raised, if the frequency of its vibration is also 

 increased, the energy of translation must ulti- 

 mately be frittered away in the conversion of these 



