365 
to the supposition, on which this calculation is founded that the 
molecular attraction only makes itself felt with perfect contact. 
YD 3 v 
At first I had expected to find / instead of a . And 
DJ: Uk 
u ui v 
strictly speaking the given values correspond to a power of 
Vk 
slightly smaller than +, approaching more closely to 4} as we keep 
closer to the eritical temperature. But such a spherical figure for a 
molecule and the vacant space belonging to it presupposes no collisions. 
It gives to every molecule a spherical form and normal to the 
/ 
movement walls of a cubic shape at distances = ; from the centre. 
As we require the collisions to account for the increase of a, we 
may not assume this form, but we must make the molecules come 
in contact, and we must suppose spaces in which the molecules lie 
at the surface. They then are nearly disk-shaped. Perhaps this is 
the reason that will have to give the explanation of the square 
root form. And that our theory requires the square root cannot be 
doubted. Let us pay attention to the form of p. 361: 
eer 
It has appeared from the first form that the points in which 
double contact takes place for given volume or temperature, lie in 
projection on a straight line that lies parallel to the line Of”, halfway 
between A and P. Compare fig. 1 or 2. In fig. 2 a projection lies parallel 
to QQ’ and halfway between A and QQ’. The length of this projection 
is found by tracing lines from A to QQ’ of a length equal to 2r. If 
AQ > Ir, two such lines may be drawn to QQ’. The points D and D’ 
are exceptional points, in which we can put at the same time # and 
l 
rs 
1 — — equal to 0; the point « becanse the thickness of the 
/ 
2 
segment is equal to 0 at that place, and 1 — —— because the quan- 
er 
