[ 135 1 
IV. The Action of Macjnetimd Electrodes upon EJectricrd Dischareie Phenomena 
in Rarefied Gases. 
By C. E. S. Phillips. 
Communicated hy Sir VfiiAAAM . Crookes, F.R.S. 
Received February 28,—Read March 14, 1901. 
Ik two previous communications which I have had the honoiu’ to lay before the 
Royal Society, reference is made to the action of a magnetic field, either constant or 
changing, upon the distribution of ions within a highly evacuated space.The chief 
result dealt wdth in the first case was the formation of a luminous ring which ajipeared 
to be in rapid rotation about the lines of magnetic induction. The other note 
described a case in which a positively electrified body placed in a rarefied gas became 
diselectrified when a magnetic field was created in its neighbourhood. I now beg to 
submit an account of some further experiments which have been made in this matter, 
with a view to obtaining evidence as to the cause of both these })henomena. 
llie Luminous Ring. 
A detailed account of the apparatus most suitable for the production of the luminous 
ring in rarefied gases has already been given in the first of the papers just referred to ; 
nor has it so far been found possible to materially improve upon the method there 
described. 
The bulb (fig. 1) having been exhausted to a pressure of about ’005 millim. of 
mercury (care being taken to drive off the greater part of the gases held by the 
electrodes), has a strong dischaige passed through it for a few seconds from the 
secondary circuit of an induction coil. 
The discharge is then stopped and the magnetisation of the soft iron electrodes, 
E^Ej, by means of the external electro-magnets, M^M,, gives rise to a luminous ring 
which suddenly apjDears within the bulb, circumscribing the pointed ends of the 
magnetic electrodes, and revolving about the magnetic axis at a considerable 
velocity. 
* ‘Roy. Soc. Proc.,’ vol. 64, p. 172; ‘Roy, Boc. Proc.,’ vol. 65, p. 320. 
3.9.1901. 
