Significance of the Chemical Constant. 25 



evaDoratino- in a wave-length cube residing in the oas is 



equal to 4 — =1*246 times the energy residing in a 



cube of radiation of corresponding wave-length. One may 

 conclude therefore, since the chemical constant can be re- 

 placed by radiation pressure, that its physical significance 

 may perhaps be sought rather in the interaction of radiation 

 and matter than in the subdivision of Gribbs's N dimensional 

 space into finite elements of equal probability. 



If these finite cells of equal probability really exist it would 

 seem difficult to escape the conclusion that the atomic heat 

 disappears near the absolute zero. The evidence appears to 

 be against this as was shown above, and one of the strongest 

 arguments in favour of such a revolutionary assumption 

 would seem to have been removed if the value of the chemical 

 constant can be derived from the radiation pressure. The 

 law of complete radiation cannot be deduced without some 

 quantum assumption of course, but it would be a considerable 

 simplification if it could be avoided in gases. 



Summary. 



It is shown that the chemical constant has the dimensions 

 of the logarithm of a pressure if the atomic heat of monatomic 

 gases becomes zero at the absolute zero. In this case it 

 should be of the form K + 3/2 log A + 5/2 log #, where 6 is a 

 characteristic constant of the substance. 



It is shown that it has the dimensions of the logarithm of 

 a pressure divided by a temperature to the power 5/2 if the 

 atomic heat of a monatomic gas remains 5/2 R down to 

 the absolute zero. In this case it should be of the form 

 K + 3/2 log A. 



Experimental determinations show that the latter form is 

 true within the limits of error. It follows either that is 

 very nearly equal to 1° for all substances, which seems im- 

 probable, or that the atomic heat remains constant down to 

 the loAvest temperatures. 



It is further shown that the chemical constant may be 

 eliminated and the vapour pressure expressed in terms of the 

 pressure of complete radiation. It is therefore suggested 

 that the cHemical constant may express the interaction of 

 matter and complete radiation rather than requiring that a 

 gas can assume only a finite number of possible microphases 

 at given temperature, pressure, and volume. 



Clarendon Laboratory, Oxford. 

 21st September, 1919. 



