420 
29 
3 55125 
is now plotted as a function of log dv, where again log hu is taken 
increasing in the direction opposite to that in which log 7 increases 
in the log By, log 7-graph. Where necessary in (5) terms up to and 
including (/v)'* were used in the calculation. 
As in Suppl. N°. 25 Nr. 88 (cf. note 399 of that Suppl.) where 
the argument of the logarithm is negative, the absolute value of the 
logarithm is plotted, and the corresponding portion of the curve is 
marked by (7). 
To ascertain if the experimental values of By correspond to one 
or other of the equations (3) and (4), is now the same as trying if the 
corresponding log Ly, log 7-curve can be made to caincide as a whole 
or in part with the corresponding 7,, logt, or F,, log hv-curve by 
(hv)®....) … (5) 
i == log i 
il 
(Av)? — Ti (hv)? — 
moving it over the other, keeping the coordinate axes of the two 
graphs constantly parallel *). 
§ 8. Hydrogen. a. The individual virial coefficients for hydrogen 
were taken from Comm. N°. 100a (Dec. ’07) table XXII and 
from Comm. N°. 1005 (Dec. °07) by KaAMERLINGH Onnes and BRAAK 
‘ef. Comm. N°. 1014 (Dec. 07) table XXV for the reduction of the 
temperatures to the Avocapro scale), and from Comm. N°. 127c (these 
Proceedings) table IV by KaMERLINGH Onnes and W. J. pr Haas ?). 
4. On moving the log By, log 7-diagram for hydrogen over the 
log £,, log t-diagram, which I shall call in what follows the diagram 
for ay and /w constant, it was evident that it was not possible to 
get them to coincide over any extensive temperature region (see 
tig. 1). From this it is again (cf. Suppl. N°. 23 Nr. 44 for the 
general case) evident that constant values of aw and dy cannot be 
used to represent even the planetary gas state (which, ef. Comm. 
N°. 127c, these Proceedings, § 1 by KAMERLINGH Onnes and W.J. DE 
Haas, can be more closely defined as that state in which only the 
B-term is still of influence in the equation of state) for hydrogen, 
over a temperature region of any appreciable extent. 
One could now try to determine values of ay and Zw which on 
the assumption that ay and bw are constant over any limited region 
') This method corresponds to the log B, dlog B/dlog T-method of Suppl. N°. 23 
note 399. 
2) The individual virial coefficients for hydrogen calculated from the observations 
of AMAGAT, and given in Comm. N'. 71, June 'Ol, p. 143, do not agree sufficiently 
with those given by the Leiden measurements and are therefore unsuitable for 
extending the temperature variation of By to higher temperatures. 
