Pes 1804 
XVII. On the Relation of the Electric Charges transported by 
Cathode and Canal Rays to the Exciting Current. By 
Franz LEININGER*. - - 
INCE the time when W. Wien, in the course of his 
research on electric discharge in rarefied gases t, showed 
that a splitting off of positive and negative particles took 
place at both electrodes, the anode as well as the cathode, 
the particles being projected in opposite directions by the 
two electrodes, it has been a problem of outstanding interest 
to determine the dependence of these showers of positive 
and negative particles, the so-called canal and cathode rays, 
on the intensity of the corresponding exciting current. 
Stimulated by a problem propounded in this sense by the 
philosophical faculty of Wiirzburg University, I have en- 
deavoured to offer some small contributions towards it. 
The phenomena of cathode and canal rays take place most 
readily at perforated cathodes. Hence the main attention 
was to be given to the occurrences at the cathode, the anode 
being always earthed. I set myself the problem of deter- 
mining the ratio of the electric convection-currents due to 
the cathode and canal rays to the exciting current. At first 
the currents corresponding to the rays and the main current 
were measured by means of galvanometers of the Kohlrausch 
and Wiedemann types, and later by moving-coil galvano- 
meters of the Siemens & Halske and Hartmann & Braun 
patterns. 
In making the arrangements, [ asked myself whether it 
might be a matter of indifference whether the galvanometer 
was connected on the high- or low-potential side of the 
tube. In order to clear up this point, I made use of a 
differentially-connected Wiedemann’s reflecting galvanometer 
for the current measurement. If, then, the currents flowing 
towards and leaving the tube were the same, no deflexion 
could be obtained on the galvanometer so connected. Now 
I found the following characteristic result in the case of ‘all 
the tubes employed :— 
1. The galvanometer gave no deflexion when the collecting 
electrode AE was in connexion with the neighbouring 
discharge electrode. 
2. The galvanometer gave a deflexion when the collecting 
electrode AB was connected to earth. 
This result I interpreted as follows :—The current supplies 
the electric charges for the cathode and canal rays, and that 
* Communicated by the Author. 
+ W. Wien, Wied, Ann. lxv. pp. 440-452 (1899). 

