647 
Comparison of the second and third columns would lead one to 
desire a smaller value for v, and this in turn would lead one to 
fix') the index g more closely as lying between 3 and 4, but nearer 
4 than 37). (Reference should be made, however, to the reserve of 
§ G of Suppl. N°. 25 qualifying the validity of these conclusions 
drawn from the influence of molecular attraction upon viscosity). 
d. The log B, log T-diagram for argon could not be made to 
coincide with the curve for constant doublets (Suppl. No. 25 § 3c); 
this is in agreement with $ 3d and ¢ of Suppl. No. 25 (and in 
particular with Figs. 2 and 3 of that paper) and also with the known 
caloric behaviour of this substance. 
§ 4. Heltum*). Helium shows, at the higher temperatures, a 
deviation from all the hypotheses introduced in Suppl. No. 24 and 
tested in Suppl. No. 25 and in the present paper, for the maximum 
exhibited by B at these temperatures (cf. Figs. 15 and 16 of Suppl. 
No. 23, Math. Ene. V 10) is not given by any of these assumptions. 
It can well be that the peculiarity ascribed by KAMERLINGH ONNEs 
to the helium atom at low temperatures is also present at these 
higher temperatures, so that one would have to assume the helium 
atom to be compressible, or to assume a relatively large increase in 
the attraction (ef. also note 4 on this page). 
Moreover, the points for the lowest three temperatures cannot be 
regarded as known with the same degree of certainty as the others. 
From both these circumstances it follows that the moving of the 
helium diagram over that for rigid spheres with an attraction potential 
TT (q = const.) can be made to take place in a manner toa very 
large extent quite arbitrary. Fig. 2 shows a superposition for the 
case g=4. In, this the point-log 7= 1,3, log By = 6,5 — 10 
coincides with the point log hv = 9,478 — 19, 4, == 9,688 — 10. 
With the exception of the highest temperatures *) the coincidence is 
1) The data given in note 1 p. 645 for the superposition in Fig. 1 would yield 
v = 268.101 for q =5. 
2) Cf. also CG. BRAAK, loc. cit. p. 645 note 2. 
3) The individual virial coefficients for He are taken from Table JL of Comm. 
No. 102a by KAMERLINGH ONNuS; these are supplemented by the virial coefficients 
for — 252.072 and — 258.°82 C., which have not yet been published but have 
kindly been placed at my disposal by Prof. KAMERLINGH ONNES (they have already 
been used for the construction of Figs. 15 and 16 of Suppl. No. 23) and also by 
the value for 4.929 K. taken from Comm. No. 119 §-50. 
4) At these temperatures Prof. KAMERLINGH ONNES tells me there is some uncer- 
tainty ; improved values are being obtained. 
