274 
equations in all sorts of thermodynamical calculations concerning the 
particular substance within the limited range through which the 
equation holds, makes it essential to obtain the best possible agree- 
ment between the equation and the results yielded by experiment. 
As the form VII. 1. was chosen for this equation with a view to its 
relationship to other investigations concerning the equation of state, 
it was fortunate that, for the comparatively small region of tempe- 
rature covered by the argon observations, there were still the same 
number of coefficients available for the equation as had been found 
required to give good average agreement over the whole region 
covered by the equation of state for various different substances. 
In the paper’) which contained the isotherm determinations for 
argon we have already given preliminary valnes for the individual 
virial coefficients A4, b4, ete. of the equation 
Bat GAs Dun WEA 
AP bak epee ee EL ar 
Ca VA UA VA A 
as directly calculated from the observations for each individual isotherm. 
The reduced virial coefficients B, €, ete. have now been calculated 
from the virial coefficients By, C4 ete. as functions of the reduced 
temperature ft, which comes to the same as the evaluation of the 
constants in the equations 
7 
Fa 
Ba 
b b bs 
Dbtt dt tte 
Rigs. 7 
C=—ctt+c EREN EE 
Z 3 t fs uf aetes 
By this the coefficients are adjusted to the observations with respect 
to both temperature and density. 
We may here give a short résumé of the manner in which these 
calculations were carried out. 
As in the present instance the final terms of the polynomial 
B : 
pra = Aa HL + ete. exert but a slight influence and therefore 
vA 
can be calculated only approximately from the observations, it was 
1) Proc. Dec. 1910. Comm. N°. 1185 and C. A. CROMMELIN, Thesis for the 
doctorate, Leiden 1910. 
2) Proc. June 1901, Comm. N° 71 and Arch. néerl. (2) 6. 874 1901, Comm. 
N°, 74. 
As can be seen a 5th term has been added to the equations there given. For 
the formulae connecting B4 and B, Cy and €, etc., reference may be made to the 
former paper. In the present paper we shall use chiefly the reduced virial coeffi- 
cients which are to be preferred for the adjustment of the values of the coefficients. 
