252 THE ORIGIN OF LIFE 



results from the intramolecular vibrations resulting 

 from partial chemical combination in two stages, 

 of association first and then of dissociation, during 

 which, as in the case of fluorescence, new molecular 

 aggregations and new free periods are found to 

 exist, the constants in the equations of motion of 

 the vibrating systems being thus altered. 



The radiation from an incandescent body would 

 appear to be due to two more or less independent 

 processes. That resulting from the vibrations 

 roused up by the increased frequency and violence 

 of the molecular collisions on the one hand, and 

 that, on the other, which is due to intramolecular 

 vibrations not directly connected with the transla- 

 tional motion of the molecules themselves. One, 

 as we shall see, seldom or never acquires sufl&cient 

 intensity to become luminous, the other is the 

 immediate source of radiation in all luminous bodies, 

 whether excited by heat or any other means. 



It is undoubtedly possible to decide experiment- 

 ally how far the radiation from a body is due to 

 one cause or the other. 



We have seen that the rate of absorption for 

 harmonic vibrations, since it depends solely upon 

 the constants in the equation of motion, is unaffected 

 by the amplitudes of the vibrations, whilst that due 

 to new free periods undergoes a great change.-^ 



1 Thus in the vibrating system 



mU + Eu + nH = f{t) = E{^t - 8). 



K . E^ . p'^ 

 The rate of absorption is = -7^= — — r-s — „.„., . 



