952 
For the pressure coefficient E. Lissi.7) gives 
ym 14 Oe a a. 
From our measurements we find 
¥ == -> 2,20, rate elk 
=de (Wine SS gel Adee) Ue gl 
so that the pressure coefficient has become somewhat greater at the 
lower temperatures. The increase obtained between 273° K. and 90° K. 
changes again to a diminution. The accuracy of the measurements 
is still too small to allow us to attribute any significance to this 
diminution at the lowest temperatures. 
If we consider the decrease — Av in the resistance for p = 100 atm., 
we find that it approximates to zero at the lower temperatures. Thus 
we find for Pb}: 
278° K. for p=100atm. —Aw=0,017 2 
and Y 
DO MCA Ren ee i — Aw= 0,008 
OBK Wen -, -— A w== 0,001. 
Physics. — “/sotherms of monatonuc substances and of their binary 
mietures. XIV. Calculation of some thermal quantities for 
argon’. By H. KaAMERLINGH Onnes and CU. A. CROMMELIN. 
Comm. N'. 1833c from the Physical Laboratory at Leiden. 
(Communicated in the meeting of November 30, 1912). 
The empirical reduced equation of state for argon, VII. A. 38, 
published some time ago’), enables us to calculate a number of ther- 
mal quantities which are essential to a knowledge of monatomic 
substances in general and of argon in particular. These quantities 
may also be obtained graphically. Calculation by means of an equa- 
tion which fits the experimental results over the whole region of 
observation allows, however, a much greater accuracy to be attained. 
Op dp 
In the present paper*) we give values of ee : Es ; 
OD Jy = YON oe 
ca as r(; el 5 == ee. — pp, (AMAGAT’s pression inté- 
Ov Jr Ol ys Òv Jr OU ap li 
1) E. Lise : Upsala Univ. Arsskrift 1903. 
*) H. KAMERLINGH ONNEs and C. A. CromMELIN, Proc. June 1912, Comm. 
N?. 128. 
3) Already indicated in Suppl N'. 23, note 492, p. 146. Preliminary values 
obtained by C. A. CROMMELIN for some of the quantities here discussed have 
already been published by E, H. AMacar. C. R. 9 April, 1912. 
