﻿Electron Theory of Metallic Conduction. 425 



a wave-form. This is possibly due to ununiform contraction 

 of* the gelatin film in the vicinity o£ the pierced point as 

 it dried from the wet state in development process, and 

 therefore cannot he interpreted as the effect of deflexions. 



In a series of experiments, a photographic plate was placed 

 in contact with a flat piece o£ glass coated with the active 

 deposit of radium in the usual way, and thus exposed to the 

 a rays coming out of the source of large area. On 

 examining the plate under a microscope, a considerable 

 proportion of the tracks seemed to have suffered large 

 deflexions. Moreover, in these cases, it seemed that there 

 were as many tracks showing large deflexions as those 

 showing small deflexions. Consequently, further investi- 

 gations will be necessary to settle the question, whether these 

 tracks are actually due to single a particles or to two 

 particles passing through the film in different directions. 



In conclusion, we wish to thank Professor Nagaoka for 

 his kind interest in this experiment. We must also thank 

 Professor Tawara of the Metallurgical Department for his 

 kindness in allowing us to use the microphotographic 

 apparatus. 



September, 1914. 



XLVI. On the Electron Theory of Metallic Conduction. — II. 

 By G. H. Livens *. 



THE modern theory of electrical conduction in metals is 

 based on the assumption that every metallic body con- 

 tains a large number of electrons moving about quite freely 

 in the space between the atoms. Both electrons and atoms 

 are presumed to be perfectly elastic spheresf, the latter being 

 of such comparatively large mass that their energy and 

 motion may be neglected. In the absence of an external 

 field it is presumed that the electrons are moving with the 

 velocities assigned to them by Maxwell's law, according to 

 which there are 



T$\/t d e-* r2 d%d v dS 



electrons per unit volume with the components of velocity 



* Communicated by the Author. 



f It is easy to generalize the procedure here suggested to the more 

 general type of theory which disposes of this arbitrary assumption. 



