ill the susceptibility to a fiflii or sixth pari of its value between the 

 li(ini(l state and the solid state at liydrogeii temperatures. It now 

 appears that a sudden ('lianne of this amount i-eally exists, but takes 

 place in two parts, namely, once to '/« ^^tJVeezing, and subsequently, 



10 



SC7i 



Fig, 2. 



after the susceptibility has again increased a second time to { at 

 the transformation |)oinl —240° C, after which the susceptibility 

 further decreases. In the accompanying figure our results are put 

 toiiether. 



Physics. — "MagnnUc researches XI 11. The susceptKnlUi/ of 

 liquid mixtures of oxygen and nitrogen, and the influence of 

 the mutual distance of the molecules upon /)nrania(jn.elisni.'" 

 By A^ AWAIT Pkrrikii and II. Kamkiujnoii Onnks. Communication 

 N". 139^/ from the Physical Laboratory at Leiden. (Com- 

 municated by Prof. H. Kamkiu-ingh Onnes.) 



(Communiciiled in the meeling of Jiinuai'v 31, 1914). 



§ 1. fntroduction . In 1910 aiul 1911 we published experiments 

 upon the susceptibility of oxygen at very low temperatures, l)y 

 which it was demonstrated that the specific susceptibility of this 

 substance, which, in the gaseous form above 0° C. follows Clkik- 

 Langevin's law, deviates considerably from this law in the litpiid 

 state at low temperatures, and even more so in the solid state. 



Subsequently we have observed similar i)henomena in other sul)- 

 stances (paramagnetic salts). The (solid) substances referred to follow 

 CuR[F,'s law at ordinary temperature, and also at temperatures that 

 do not lie too far below it; but wlien the temperatin-e falls to the 



