Physics. — “On the deviations of liquid oxygen from the law of 
Curie”. By Prof. W. H. Kexsom. (Communication N°. 8 from 
the Laboratory of Physics and Physical Chemistry of the 
Veterinary College at Utrecht). (Communicated by Prof. H. 
KAMERLINGH ONNES). 
(Communicated at the meeting of February 26, 1921). 
§ 1. Jntroduction. It will be well-known that the magnetic sus- 
ceptibility of gaseous oxygen‘) follows the law of Curie 
fil CF We Wipe Ee, ere cL) 
but that for liquid oxygen *) we have the relation 
Ae Ne ORNL ge AT Webel ars SAM 7) 
where A is a constant viz. A— 71. An explanation of this pheno- 
menon has been sought in different ways. 
We may for this liquid base our considerations on the validity 
of the fundamental idea of LANGeviN’s theory. Then the deviation 
from the law of Curie might be caused by: — 
1. a change of the number of elementary magnets e. g. by poly- 
merisation of the oxygen molecules (KAMERLINGH ONNEs and PERRIER, 
Leiden Comm. N°. 116). More recent experiments baving shown 
that similar deviations also occur in the case of solids, for which 
such a polymerisation, changing with the temperature, can hardly 
be assumed, we should prefer to find another explanation for oxy- 
gen also. | 
2. a decrease of the magnetic moment of the oxygen molecules 
or atoms, either by a slower circulation at lower temperatures of the 
electrons which give rise to the magnetic moment or, in the case 
of liquid oxygen, by the influence of the thermic pressure (KAMER- 
LINGH OnnEs and Prrrizer, Leiden Comm. N°. 116). More recent 
experiments on the susceptibility of gaseous oxygen down to 147° K. 
on the one hand (KAMERLINGH OnNES and OosrerHUIS |. c.) and of 
1) P. Curie. Ann. chim. phys. (7) 5 (1895), p. 289. H. KAMERLINGH ONNES 
and E. OosrerHuis. Leiden Comm. No. 134d. 
*) H. KAMERLINGH ONNES and A. PERRIER. Leiden Comm. No. 116. These 
Proceedings Vol. XII 1910, p. 799. H. KAMERLINGH ONNEs and E. OosTER- 
HUIS. Leiden Comm. No. 132e. These Proceedings Vol. XV 1913, p. 965. 
For liquid mixtures of oxygen and nitrogen comp. A. PERRIER and H. KAMER- 
LINGH ONNES. Leiden Comm. No. 139d. These Proceedings Vol. XVI 1914, p.901. 
