471 



(with positive AJ. Tiiis class of substances could be called (/uasl- 

 paramagnetic : the presence of the molecular field only becomes 



Fig. 3. 



apparent, as far as the susceptibility is concerned, in this that these 

 substances deviate from the law of corresponding- states, which in 

 accordance with the supposition made by Kamerlingh Onnp.s and 

 Perrier^) and found confirmed in Oosterhuis' theory^) is valid for 

 purely paramagnetic substances (without molecular held) with 

 constant magnetic moment. 



V = i\. The substance follows over a large region Curie's law 

 (A, = 0). At low temperatures the x~', 7'-graph is curved, a region 

 with definite A ^) cannot, however, be indicated. 



V = i\. State of excited ferromagnetism, characterised by a posi- 

 tive value of Aj in x{T — AJ = const, for sufficiently high 

 temperatures. The substance has, however, no OuRiE-point. 



V = v^. Also no CuRiE-point. If we abstract from saturation phe- 

 nomena, X would continually increase on approaching 7^=0. It is 

 for such a substance or one which differs little from it (r litlle less 

 than \\) that one should in the first instance expect the appearance 

 of saturation phenomena at low temperatures. 



V = I'j. Ferromagnetic substance with CuRiE-point. 



1) H. Kamerlingh Onnes and Alb. Perkier, Comm. N'J. 124« (Dec. IGll), § 3. 

 Gf. E. Oosterhuis, Suppl. N". 31, These Proceedings p. 440, note 4. 



2) Cf. E. Oosterhuis, 1. c. 



