( 612 ) 
terms of the normal volume; these volumes served along with vapour 
pressures known from Comm. 115 for the construction of the boundary 
curve in the pv-diagam. 
| , | | 
| Series a | d, d 5 a | We Pre 
VI 1.0268 0.1073 5629 60:21 0.001735 | 0.01661 
V 0.9339 1621 524.1 | 9097 1908 | 1099 
| | 
III en IV 8581 2079 | 481.6 116.67 2076 08571 
II 7557 2843 | 424.1 | 159 54 2358 06268 
In the accompanying figure are given curves for the liquid and 
vapour densities and for the diameter constructed from the above 
values of d,, d, and d,, the liquid densities given by Baty and 
Donnan and the critical temperature — 122°.44 C. of Comm. 115. 
The unconstrained manner in which the curves could be drawn 
through the points shewed that in the case of argon there was no 
necessity to expect any great deviation from the diameter law upon 
which the calculations were based. 
Only the points of Series V (— 134°.72) do not appear to fit the 
curve so well, which is no doubt explained by an error of observation. 
§ 4. Representation of the observations by formulae. 
a. The purely empirical formula given by Kexrsom *) is the most 
suitable one for this purpose; it may be written in the form 
l 
Es ren | 
di. 
A gee Te wiped a sate Ratan eee eae en 
Sell 
dj. j 
in which A, B, and 4 are constants, and ¢ represents reduced tem- 
perature. 
By subtracting these equations the following simple relation is 
found for the observed magnitude d,—d, : 
d, = d, = ay: Ba = dee 
With constants 
4= 0.5795 and B = 1.999 
determined by the observed values the following correspondence is 
obtained : 
1) W. H. Kersom, Proc. April 1902, Comm. N°. 79. 
