from an Electric Source. 



171 



experimental isotherms 1087 and 1377 degr. absol. gives for 

 « very nearly the value a — '20 cm. x degree. But this 

 only by the way. The essential thing is that a plays the 

 part of an "'universal" constant (as long, of course, as a 

 is large enough), so that T c is ultimately proportional to 

 7?, C =X C _1 . It will be noticed that, w being dimensionless, 

 T c is a certain temperature. If the reader is willing to treat 

 our as the specific heat of a concrete substance, he may 

 call T c "the characteristic temperature" of that substance*. 

 But as a matter of fact, T c is a certain magnitude associated 

 with our electric source, proportional to its actual frequency 

 ti = ?? c , which according to the definition (18) is to be kept 

 constant, and which from case to case can have different 

 numerical values. It is, in short, a fixed parameter of the 

 electric source, just in the same way as T, in general, or, still 

 better, a itself, is a slowly variable parameter of the source. 



We could investigate a number of similar sources with 

 different frequencies of oscillation, say from n = up to a 

 certain fixed value, and find the corresponding average of C 

 in order to identify such an average with the specific heat 

 of a given substance. But before doing so it seemed in- 

 teresting to examine the " specific heat " of a single source 

 as given by (19) or (19 a). Now, having plotted C against 

 T for a set of different values of T c = const., I have been 

 surprised by the fact that the resulting curves, which have 

 C = Co, for their common asymptote, exhibit a very close 

 resemblance with the atomic-heat curves of various elements. 

 At first I had only the ?r-term of (19 a), and correspondingly 

 small pieces of the curves; but with the next two or three 

 proved to bo much closer. Some 

 which needs no 



terms the agreement 

 numerical results are 

 further explanation. 



given in Table IV. 



Table IV. 





o- = C/C„ ; Silver ; T 



= 50-12. 







T 



535 



331 



200 



100 



77 



53-8 



51-4 



455 



0" calc. • • • 



•90,, 



•98, 



■94, 



•80, 



•70, 



■49, 



•47 4 



•45 



(T obs. • • • 



•99 



•96 -94, 



■so. 



•67 a 



•50, 



•47 



•41 



* Although there is nothing- characteristic or peculiar happening just 

 at that temperature. What I wish to say is that the curve (19) has no 

 singularity in that neighbourhood; singularities, which, if undesirable, 

 can be abolished, set in at temperatures much lower than Tc, as will be 

 seen later on. 



