1484 
R= u! (TO) Go 8 ol oat 0 EL) 
This value introduced into equation (3) gives: 
INE es a EE yf at 
If we now substitute the value (1) for 4 and put the value 2 
for 1+ 0, we get finally : 
> 
te 
| 
tele 
| 
4 
oo 
| 
volo 
| 
4 
= 
— 
Or 
— 
This formula differs from that of von SmoLucuowskt only in nume- 
rical coefficient. Where we find $, v. S. puts $4 or with a somewhat 
different derivation 3. 
Another calculation '), which was not founded on purely kinetic 
considerations led to quite the same expression as equation (5). It 
was asserted there that there was no reason to confine the validity 
of this formula to those cases in which the dimensions of J/ are 
small with respect to the mean free path of the molecules. 
If with Maxwerr *) we now substitute the value 
1 1 Mm N 
come OV On on M+ m RT 
for t, in which 6 represents the sum of the rays of the particle and 
a molecule, and therefore may be replaced by a, the radius of the 
particle, while » denotes the number of molecules per cem., (5) 
reduces to: 
ie 3 1 WA RTm E 6 
2 == ef 0 Oo G oO sa 6 ) 
4V/ 27 0° N ie 
in which ge =n, m==the density of gas. 
A is the projection of the path passed over in an arbitrary direction. 
To find the mean square of the total path passed over we must 
multiply (6) by 3. 
J. D. v. p. Waars JR. and A. Snerutace. These Proc. XVIII, p. 1322. 
J. GQ. Maxwett. 1. c. 
