306 Mr. Take Sone on the Magnetic Susceptibilities 



and helium, is very important. In spite of this fact, owing 

 to the great difficulty in measuring the susceptibility of 

 gases, only a few cases — oxygen and air — are known, in 

 which the value of susceptibility can be given with fair 

 accuracy. For other gases the values of susceptibility by 

 different observers show large discrepancies not only in 

 magnitude, but sometimes in sign. Hence an exact and 

 more extended determination of the magnetic susceptibility 

 of different gases was thought to be desirable. The present 

 investigation was undertaken at the suggestion of Professor 

 K. Honda about two years ago and is still in progress. 



On the other hand, the theory of magnetization of the 

 gases has been successfully developed by P. Langevin * ;., 

 the conclusions arrived at agree in many points with the 

 observed facts ; but there are many others which cannot be 

 explained by his theory. According to him, the molecules 

 of a paramagnetic gas have each a definite magnetic moment^ 

 which is comparable with that of a ferromagnetic substance, 

 but those of a diamagnetic gas have no magnetic moments, 

 so that there is a fundamental distinction between para- 

 magnetic and diamagnetic substances. The diamagnetism 

 is of an atomic nature and therefore cannot vary with 

 temperature, or by the change of states, or by any mode of 

 chemical combination. These conclusions do not, however, 

 accord with the fact that the susceptibility-atomic weight 

 curve for elements f changes quite continuously in passing 

 from the paramagnetic elements to the diamagnetic, and 

 that the susceptibility of tin J changes its sign at the trans- 

 formation point and during melting. Professor K. Honda § 

 modified Langevin's theory of paramagnetic and diamagnetic 

 gases so as to include the magnetization of liquid and solid 

 states, and gave a different aspect to the distinction between 

 paramagnetic and diamagnetic substances. According to 

 him the observed susceptibility % is the sum of the Langevin 

 paramagnetic and diamagnetic susceptibilities % and % d ;, 

 that is 



which may be paramagnetic or diamagnetic, according as 



Since x p depends on the configuration of the atoms in a 



* P. Langevin, Ann. de cliim. et de phys. viii. p. 70 (1905). 



t K. Honda, Ann. d. Phys. xxxii. p. 1027 (1910). 



X K. Honda, he. tit. 



§ K. Honda, Sci. Rep. iii. p. 171 (1914). 



