148 MR. C. E. 8. PHILLIPS ON THE ACTION OF MAGNETISED ELECTRODES 
strength of the magnetic held played an important part both in the formation of the 
luminous ring and also in the diselectrihcation process. 
Conclusion. 
The preceding experiments show that the principal effect of the magnets is to 
produce a concentration of negative ions at the strongest portion of the magnetic 
held, and centrally within the bulb. There is also experimental evidence to j^rove 
that this concentration of negatively electrihed gas is responsible for the diselectrih¬ 
cation of a positively electrihed body placed in its neighbourhood. The experiment 
with the metal cones (hg. 9) and also that with the electrostatic screen (hg. 10) 
demonstrated that, either when the concentration of negative ions occurred between 
the points of the electrodes or when an earth-connected metallic screen came 
l^etween the negative cloud of gaseous particles and the electrihed body, no diselec¬ 
trihcation took place. I consider that this concentration of negative ions is due to 
two main causes. In tlie hrst place, it is partly produced by the action of the 
magnetic held upon ions already in motion within the bullj. The pause of about two 
seconds sometimes found to occur between the excitation of the magnets and the 
appearance of a luminous ring or diselectrihcation of a })ositively charged body 
supjiorts this vie\\\ And secondly, owing to the reaction resulting from the sudden 
excitation of the magnets,"^" the comparatively dense clouds of ions situated at the 
ends of the l)ulh (hg. 8) would, in rapidly turning about the magnetic axis, tend to 
move towards the pointed ends of the electrodes and so concentrate as observed. 
Owing to the viscosityt of the gas, however, it is not to be expected that such a 
rotation of the ions would be other than momentarv. But tliat the rate of change 
of the magnetic lines affects the distribution of the electrihed particles within the 
l)ulb is clear from the results of the experiments already given. 
[Professor S. P. Thompson| has already pointed out that the prelimiimry experi¬ 
ments seemed to indicate the existence of some such action taking place within the 
l)ull ).]—Jniy 1, 1901. 
llefei'i'ing again to hg. 8, we see the distriljution of ions at the moment prior to 
exciting the magnets. The negative ions in concentrating as ex])lained give rise to 
an increase in the potential difference Ijetween the electrihed gas upon the inner 
surface of the glass and that at the central portion of the bulb. At a gas pressure 
just too high to give the luminous ring, the effect of creating a magnetic held was 
found to 1)6 an Increase in the positive electrihcation upon the outer surface of the 
bulb (hg. 5), and this is now seen to he consistent. That state of things is repre¬ 
sented in hg. 11, vdiere the })ositive ions are supposed to accumulate o])posite to the 
* ‘ Elcctilcian,’ vol. 25, j). 35. 
t ‘I’hiL Tniiis.,’ vol. 172, p. 387. 
1 ‘Electrician,’ vol. 43, 1899, p. 412. 
