1134 
the only new thought about the influence of the dimensions of the 
molecule (Chapter VI) was this that the volume inside which the 
motion of the molecules takes place, must be considered as in reality 
smaller than it seems at first sight. 
If in case the molecules should be material points, the consequence 
RT 
of the collisions is that they resist an external pressure + Tag the 
consequence of their own dimensions is that they resist a pressure 
U . F . . . . . 
——— times as great. And we cannot dispense with this consideration. 
v—D 
We may introduce this thought immediately; and without having 
N / ed ne re 
to speak of repulsive forces, write directiz: » Jr a or if it 
(Dii Od 
is preferred first continue the course of the calculation with the aid 
of the theorem of the virial further than I have done. But finally 
to arrive at the true formula it is again necessary to follow the 
course taken by me. I showed this long ago. When I wanted to 
determine the value of this new quantity 4, however, I soon per- 
ceived that this would be attended with great difficulties. 
It was not so difficult to determine the value of 6,, and I could 
at onee conclude that 4, is equal to 4 times the volume of the 
molecules. And it was also easy to see that / would have to decrease 
with the volume. Already the consideration that for infinitely large 
pressure the volume would have to be smaller than 4 times the 
volume of the molecules, and would have to depend on the grouping 
in that smallest volume, and that therefore bj; would have to be 
< by, was sufficient for this. In reference to this I say what follows 
in Chapter VI (p. 52), after I had reduced the way to determine 
the quantity to the abbreviation of the mean length of path, and 
had therefore put: 
“but this formula cannot be applied up to the extreme limit of con- 
densation of the substance’, ete. as far as the word “verwachten”. 
It appears from the cited passage that I felt already then that the 
quantity 5 in a definite volume would have to be determined by 
the determination of the distance, at which during the impact the 
centre of the colliding molecule must remain from the central plane 
at right angles to the direction of motion, in consequence of the 
dimension of the two colliding molecules. This appears among others 
when I say that when v << 46, not only the double-central shocks, 
