Physics. — ^'On Whittaker's Quantum mechanism in the atom". 

 Bj Prof. H. A. LoRENTZ. 



(Communicated at the meeting of October 28, 1922). 



§ 1. Some months ago Whittakkr ^) has proposed an interesting 

 model by means of wliich the qaanliim properties of tlie atom can 

 be accounted for to a certain extent, the model showing in the fust 

 place how it may be tliat, in the collision of an electron against 

 an atom, tlie former loses either no energy at all, or just adetinite 

 amount of it. In what follows I shall oflfer some remarks about the 

 action between an atom and an electron, as it would be according 

 to Whittaicer's views. 



Whittakek supposes that, when an electron approaches an atom, 

 a "magnetic current" is set up in this particle, comparable with the 

 electric current that is excited in a diamagnetic particle by the 

 approach of a magnetic pole. In this latter case the induced current 

 makes the particle repel the pole (Lenz's law) and similarly in the 

 former case the magnetic current gives rise to a force tending to 

 stop the motion of the electron. 



The theory takes the simplest form when it is assumed that there 

 are not only "electric charges", but also "magnetic" ones, accumu- 

 lations of positive or negative magnetism. Bj^ the introduction of 

 these into the fundamental equations, the parallelism between the 

 electric and the magnetic quantities can be clearly brought out. 



^ 2. Let 9 be the density of the electric charge, v the velocity of 

 one of its points, and similarly ^ the density of magnetic charge, 

 W its velocity ; further d the electric force or the dielectric displace- 

 ment in the aether, and h the magnetic force or magnetic induction. 

 Then we have the fundamental equations 



div é ^= Q, . ' . . . . . . . (1) 



div)n = (i, (2) 



roth= — {di^Q\l), . (3) 



c 



rotö = (h + ft W) (4) 



c 



^) E. T. Whittaker, On the quantum mechanism in the atom, Proc. Royal 

 Society Edinburgh 42 (1922), p. 129. 



