302 THE REALITIES OF MODERN SCIENCE 



solids the atomic heat is practically 6 calories, that is, 

 Dulong and Petit's law holds for these high tempera- 

 tures. (It might be noted that we should expect the 

 physical behavior of molecules to be alike at " cor- 

 responding states.") An expression may then be 

 written for the frequency in terms of known constants 

 of the substance under examination. The values 

 obtained by this method are not sufficiently accurate, 

 however, to warrant their use in calculations, but 

 they do serve as checks on those obtained by other 

 methods. 



In the matter of electronic oscillators and their 

 ability to absorb energy we have reached a pivotal 

 position of modern science. The earlier idea as to 

 the equipartition of the energy of a molecule is no 

 longer tenable. For the oscillators assumed by Ein- 

 stein we have the evidence that equations derived 

 upon that assumption indicate variations in specific 

 heat in the direction and of the magnitude confirmed 

 by experiment. The further assumption of Einstein's 

 equation, that energy may be absorbed only in quanta, 

 was originally advanced by Planck to explain certain 

 phenomena of radiation. The success of the applica- 

 tion of this concept of quanta to the phenomena of 

 specific heat is at once a confirmation of the " quantum 

 theory" and a promise of an ultimate explanation of 

 these phenomena. At present, however, it is not 

 possible to picture with definiteness the electronic 

 construction or behavior of these oscillators. The 

 quantum theory is in the hands of the future, but its 

 fundamental assumption is completely verified : energy 

 may only be absorbed or transferred in discrete quanta. 



