L68 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Now, as a matter of feet, /? T In is always less than L, and this is 



precise!; wliat would be predicted from our theory; for in passing from 

 a liquid to a vapor energy must be used ool only in overcoming the 



intermolecular attraction ( the quantity that would be equal to R T^n — ), 



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

 molecules, which was shown on page 105 to be a necessary consequence 

 of our theory. 



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

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

 n< "ii- 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, l>e of considerable independent 

 importance ; for if we regard the mass law kiuetically a- an expression 

 of the law of probability, the chance ol 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 

 _ >tion oi a possible future modification in the theory of chemical 

 kinetics must suflice. 



