168 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Now, as a matter of fiict, -R T\r\ — is always less than L, and this is 



precisely what would be predicted from our theory ; for in i)assiMg from 

 a liquid to a vapor energy must be used not only in overcoming the 



intermolecular attraction I the quantity that would be equal to R Tin — 



but also in providing for the increase in the progressive energy of the 

 molecules, which was shown on page 165 to be a necessary consequence 

 of our theory. 



In concluding this brief treatment of some of the consequences of our 

 theory, we may mention one that is important in the study of homoge- 

 neous equilibrium. The isothermal, according to our present view, is not 

 identical with the line of constant internal energy of progression of the 

 molecules, which might also be called the line of constant molecular 

 velocity ; the latter line must, therefore, be of considerable independent 

 importance ; for if we regard the mass law kiuetically as an expi'essiou 

 of the law of probability, the chance of any two molecules reacting must 

 depend upon their momentum at impact, and this would be constant along 

 the line of constant molecular velocity, and not along the isothermal. 

 The mass law, then, disregarding other disturbing factors, should hold 

 along the former line rather than the latter. On account of an entire 

 lack of data that would give any experimental evidence on this point, this 

 mere suggestion of a possible future modification in the theory of chemical 

 kinetics must sufBce. 



