[RUTHERFORD] EXISTENCE OF BODIES SMALLER THAN ATOMS 83 
From the data of the experiment the values of the velocity and 
aa were found to be about the same as those determined by the first 
method. 
J. J. Thomson also found that the ratio © Was independent 
MA 
of the gas in the vacuum tube, showing that, possibly, particles of 
the same size were produced from different kinds of matter. It is, 
however, possible to explain this result by supposing that the dis- 
charge is in all cases carried by the trace of water vapour which is 
always present in the vacuum tube. 
A complete confirmation had thus been given to the projection 
theory of cathode rays, and the importance of the work was at once 
recognized by Continental physicists. 
A series of experiments were performed by Des Coudres, Lenard 
Kauffmann and others, which verified and extended Thomson’s results. 
There was always present, however, a doubt that possibly the 
theory from which the results were deduced might be inapplicable, 
and that the enormous velocity of the particles did not exist in fact. 
This last doubt was completely removed by Weichert, who showed, 
by actually measuring the time taken by the rays to pass from one 
point to another, that the velocity was of the same order as that 
obtained by previous observers by the methods already explained. 
Townsend showed by considerations based on the Kinetic theory 
that the charge on a gaseous ion was the same as on an ion in elec- 
trolysis. By a beautiful method, J. J. Thomson succeeded in deter- 
mining the actual value of the charge, and this charge was found 
to be the same from whatever gas the ion is produced. 
el 
J. J. Thomson also made determinations of the ratio Fa for 
electrons produced in two other distinct ways. Since the work of 
Hertz on electrical waves, it has been known that a clean surface of 
metal discharges negative electricity when ultra violet light falls upon 
it. The ultra violet light, in some way, produces negatively charged 
ions at the surface of the metal plate. At atmospheric pressure these 
ions are equal in size to the ions produced out of the gas by Rontgen 
or Becquerel rays, but at low pressures they have been shown to be 
similar to cathode rays. By observing the deviation of these ions 
by a magnetic field when they were made to move rapidly in a strong 
electric field, J. J. Thomson showed that the ratio of © for the 
nt 
carriers was the same as for the cathode ray produced in a vacuum 
tube. 
