644 
is true that without further evidence one is rather disinclined to 
regard such a distance law tor the attraction potential as a funda- 
mental property of the monatomic atom, and, should agreement with 
experiment be obtained with any detinite value of g, one would 
like to obtain a deeper insight into the structure of the atom which 
would lead to the same law of distance for the resultant of the 
probable electric forces originating at various points of the atom; 
yet it is still clear that the results eventually obtained in the present 
paper for the index q can give important indications of the direction 
in which one must look for the development of the correct atomic 
model. 
§ 2. A comparison was first made between the experimental data 
and the hypothesis of rigid spheres of central structure exerting 
central attractive forees upon one anotber proportional to r—@+) 
where q is a constant (potential energy proportional to —r—‘). This 
was done, following § 2 of Suppl. No. 25, by moving the log by, 
log 7-diagram for the experimental substance over the /,, log hv- 
diagram, where, following equation (42) of Suppl. No. 246, 
1 3 
(Av)? — — —— (Av)’...};. (B 
3! 3q—3 
For the meaning of / and v reference may be made to $ 5 of 
Suppl. No. 244. The scale was again 0.005 to the mm. and log hv 
was again drawn increasing in the direction opposite to that in 
which log 7 increases. 
In this connection it is to be noted that when q is just slightly 
greater than 3, and then v must be taken small in comparison, the 
terms of equation (1) involving the square and higher powers of 
hv are small in comparison with the preceding term. The variation 
of B with temperature then becomes the same as in the case of the 
assumption of constant ay and 5. Hence comparison of experiment 
with the hypothesis of constant values of ay and by, can be made 
the same as comparison with the present assumption concerning the 
attraction potential with a value for g which is but slightiy greater 
than 3. 
a 3 
F, = log (1 — — 5 hv — 
§ 3. Argon, and hydrogen below the Borur-point. 
a. In the case ot argon‘) the deviations of the experimental points 
1) As in Suppl. No. 25 § 3d the individual virial coefficients of Comm. No. 1180 
have been used. In Comm. No. 128, June 1912, KAMERLINGH ONNES and 
CROMMELIN gave values of Ba(71) adjusted according to the temperature polyno- 
mial of the empirical equation of state; in these were included the lowest three 
temperatures, for which only a few points of the isotherms were observed and 
for which, individually, no sufficiently reliable values for the coefficients could be 
calculated; these, therefore, must be regarded as known with less certainty than 
