( 799 ) 
Physics. — “Researches on the magnetization 0/ liquid and solid 
oxygen .” By H. Kamerlingh Onnes and Albert Perrier. 
Communication N°. 116 from the Physical Laboratory, Leiden. 
$ 1. Introduction. It is scarcely necessary to remark that the 
investigation of the magnetic properties of oxygen at low tempera¬ 
tures has long occupied a position on the programme of the cryogenic 
laboratory, or that this has been considered one of the most important 
items on the programme sinc^the investigation of both liquid and 
solid oxygen has been made possible by the perfecting of the methods *) 
of obtaining detailed series of measurements at constant temperatures 
in the region of liquid hydrogen. Indeed, while the strongly magnetic 
properties of oxygen of themselves select it from all other substances 
as especially suitable for the study of para-magnetism, we can in the 
meantime for no other substance obtain the magnetic equation of 
state*), which gives a representation of the magnetic properties of a 
substance in the three states of aggregation at as many successive 
temperatures and pressures as possible. 
The investigation of oxygen at very low temperatures and at 
pressures that can easily be realised was expected to give at once 
results of much importance. 
Curie*) found for gaseous oxygen between 20° C. and 450° C. 
that the specific susceptibility (magnetization per gram for H— 1) 
was inversely proportional to the absolute temperature, and Fleming 
and Dewar 1 2 3 4 5 * * ) concluded from their latest measurement of the suscepti¬ 
bility of liquid oxygen at its boiling point that Curie’s law was obeyed 
down to —183° C. 
Does the specific susceptibility continue to increase so strongly at low 
temperatures or does it approach a limiting value? Is oxygen in the 
solid state ferro-magnetic? Does the magnetization finally at extremely 
low temperatures perhaps begin to decrease and disappear completely 
at the absolute zero? 8 ) 
1) H. Kamerlingh Onnes, These Proc. Sept. 1906, Comm, from the Leyden labor, 
no. 94/ (1906i. 
2) H. Kamerlingh Onnes, Commun. from the Leyden labor. Suppl. no. 9 p. 28. 
3) P. Curie. Ann. chim. phys. (7) 5 (1895) p. 289. 
*) Fleming and Dewar Proc. Royal Soc. London 63, p. 311, 1898. 
5) It has since appeared that the magnetization of ferro magnetic substances 
does not yet give any justification when the temperature is lowered to the 
melting point of hydrogen for the assumption that the electrons whose motion 
causes magnetization are frozen fast to the atoms and that therefore this disap¬ 
pearance at the absolute zero may be expected. (P. Weiss and H Kamerlingh 
Onnes, These Proc. Jan./Febr. 1910, Comm, from the Leyden Labor no. 114 p. 9). 
