( 598 ) 



ength ofpcatli in the same way as van der Waals' quantity h is subjected 

 to a change by tlie forces exerted by the molecules on each other. ') 



The three states of aggregation which we used just now as an 

 illustration of the behaviour of the electrons, might perhaps be 

 considered as referring to the stability of different paths of the elec- 

 trons, and the quasi-elastic force might be connected with the 

 conditions for the electrons moving in these paths. 



If we further note that it is the ratio of the absolute temperatures 

 on which the degree of change of the spectra depends (compare the 

 transition from 7^=20 to r=14 with that from r= 290 to 

 J'=95), we may accept for the present as a heuristic image the 

 idea that we may speak of corresponding states according to different 

 units of temperature caused by mechanic similarity of the motion 

 of the electrons round the centres. 



II. Phenomena depending on thk temperatuke and on the strength 



OF the magnetic field. 



§ 8. Constancy of the change of. the frequency of vibrations 

 under the injiuence of the maynetlc field at all temperatures. 



According to the experiments made by one of us previously 

 (J. B.), when a uniaxial crystal is placed with its axis in the 

 direction of the lines of force and of the ray of light, some absorption 

 bands are resolved into two components, which belong to the absorp- 

 tion of two circularly polarized rays of opposite sense. The difference 

 of frequency of vibration of the two components had then proved 

 to be independent of the temperature. It follows now in a still more 

 convincing way from the comparison of the divergence of the two 

 bands at the temperature of liquid hydrogen with the divergence 

 at the temperature of liquid air, that within the limits of errors of 

 observation, the difference of frecpiency of vibration is entirely inde- 

 pendent of the temperature. According to the theory of Lorentz 

 this constancy of the divergence of the bands, wdiich is observed 

 both for those which behave in the sense of the ZEEMAN-effect as 

 for those which behave in opposite sense, must be considered as 

 proceeding from the invariability of the relation ejm. Accordingly 

 the observations in liquid hydrogen seem to fui-nish a strong support 

 to the argument in favour of the existence of positive electrons 

 derived from the constancy of this quotient. °) 



1) Calculated by Reinc.anum according to the theory of Boltzmann. 



2) Lb Radium lom V. p. 17 1908. 



