rimentally to agree with that deduced from (59) one could get a 
fair conception of the molecule which would at least give this Jaw 
of dependence upon temperature by calculating v from the tempe- 
rature of the Boye point (if within the specified region) and o from 
the terms in the expression for B which are independent of 7’, and 
then me, the moment of the doublet; from this one could, for in- 
stance, calculate the distance of the electron from the centre in the 
case of the molecular representation indicated at the beginning of this 
section. Further discussion of experimental results, however, must 
be postponed till a later paper. 
Physics. — ILsotherms of monatomic substances and of their binary 
miztures. XIII. The empirical reduced equation of state for 
argon. By Prof. H. KAMERLINGH Onnus and Dr. C. A. CROMMETIN. 
Comm. N°. 128 from the physical laboratory at Leiden. 
In a previous paper’) we indicated the desirability of obtaining 
from the mean reduced empirical equation of state for a number of 
normal substances which we have called VII. 1.7), a mean reduced 
empirical group-equation applicable to the monatomic substances. As 
a first step in that direction we now give a special reduced empi- 
rical equation for argon which we shall call VII. A. 3. and which 
embraces data obtained from observations made in both vapour and 
gaseous states. *) 
In previous communications similar special equations have been 
published, viz. one for carbon dioxide *) in gas, vapour, and liquid 
states, and one for hydrogen ®) which embraced all available obser- 
vations on the gaseous state. The important part as convenient sum- 
maries of all available experimental data played by such special 
increase of temperature undergone by a quantity of gas contained under high 
pressure on the addition of a measured quantity of heat showed that even at 
200°K. y,,4 is for hydrogen considerably below °/. f, while at 60°K. the value 
obtained was */, R. It was mentioned during the discussion at the Conseil SoLvay, 
Nov. 1911, that Professor KAMERLINGH Onnes and myself had undertaken an inves- 
tigation of y,, by Kunpt's method for hydrogen at temperatures down to that of 
liquid hydrogen, but this investigation has not yet been completed. 
1) Proc. March 1911. Comm. N®. 120a. 
2) Suppl. N’. 19 p. 18. 
3) Proc. Dec. 1910, Comm. N°. 1185 and CG. A. CROMMELIN, Thesis for the doc- 
torate, Leiden, 1910. 
4) Arch. néerl. (2). 6. 874. 1901, Comm. NY. 74. 
5) Proc. April 1909, Comm. N’. 1094. 
