CAPACITY FOR HEAT OF METALS AT LOW TEMPERATURES. 355 
represented by a single parameter (frequency or characteristic temperature) as in Debye’s 
theory, even with the assistance of the correction from constant volume to constant 
pressure. In a special class, like the metals, the variations of type are not so great, 
but there is here endless room for speculation with regard to the appropriate 
frequencies, and if these fail, the magnetons and electrons can be invoked. There 
are, no doubt, relations between the specific heats and the optical, electrical, and 
mechanical properties of substances, but qualitative agreement may be obtained on so 
many different and mutually contradictory hypotheses that very little stress can be 
laid on such agreement as a verification of any particular hypothesis unless every 
step in the argument can be proved and tested by independent experimental 
evidence.” 
Walker,* in a note to a paper entitled “ A Suggestion as to the Origin of Black 
Body Radiation,” states that, by similar reasoning to that of Einstein and Nernst, 
he found that if the radiation function varied as 
J ™ Y 
\\ 2 e 2 + a 2 ) 
* ‘Roy. Soc. Proc.,’ A, vol. 89, p. 398, 1914. 
2 Z 2 
