( 1014 ) 
$ 2. Comparison of argon tsotherms’) with those of isopentane 
(Young) °), ether (RAMSAY and Youne)*) and carbon dioxide (AMAGAT) *) 
between the reduced temperatures 1.0000 and 1.1323. 
In order to obtain a systematic comparison from the point of view 
of the law of corresponding states between the results obtained for 
argon and those for other substances, we have in the manner 
indicated in $ 1, calculated the differences between the observed 
data for the various substances and the values obtained from VII. 1°). 
To begin with, the critical temperature and pressure already published *) 
were used in the calculation of the virial coefficients for argon 
according to VII.4, and. from these coefficients, deviations from 
VII. 1 were obtained. It appeared to be most suitable to work with 
percentage deviations of pr from values of pr given by equation VII. 17). 
The virial coefficients are given in table I and the differences in 
table II. 
The deviations for isopentane, ether and carbon dioxide from 
VII. 1. were calculated a considerable time ago; they form part of 
an extensive research upon the differences between the empirical 
equations of state for these substances as expressed by their deviations 
from the general mean reduced equation, of which only a very 
small part has yet been published. From amongst these, deviations 
are taken which can be compared with the argon isotherms between 
—100° C. and the eritical point, that is, those which lie in the same 
region of reduced temperature as the argon isotherms. The deviations 
for all four substances were then united in one diagram in which the 
lek . f DU kk 
deviations were plotted as functions of log àv in which 1= 
k 
and 
Ek 
Hence, the critical volume does not appear in the expression 
1) Proc. Dec. 1910, Comm. No. 118) and C. A. CROMMELIN, Thesis for the 
doctorate, Leiden, 1910. 
2) S. Young, Proc. phys. soc. London, 1894/95, p. 602. 
3) W. Ramsay and S. Youne Phil. Trans, 178. 57. 1887. 
4) E.H. Amacatr, Ann. de chim. e. d. phys. (6) 29, June and Aug. 1893. 
5) For a critical examination of the observations it is also very desirable to 
substitute deviations from VII. 1. for the actual observations so as lo eliminate 
experimental error, and to reduce to one common substance the results obtained by 
different observers. Our results for argon were treated in this fashion before bemg 
placed upon the diagram. 
6) Proc. May 1910, Comm. NO. 115. 
7) For the method by which these calculations are made, e.f. Proc. June 1901, 
comm. No. 71. 
