738 
Mr. S. Russ on the Electrical Charge 
While working along similar lines with Actinium an 
exactly opposite effect was observed. Under the conditions 
of these experiments the activity of the negative was only 
twice that of the positive pole at atmospheric pressure, this 
ratio being increased to twenty-two on reducing the pressure 
to a few millimetres. (Phil Slag. May 1908.) 
It was found, however, that by varying the experimental 
arrangements, the activity of the negative electrode could be 
made to vary from twice to more than a hundred times that 
of the positive electrode, without altering the pressure. It 
appears from the observations to be described, that the 
variable which determines the electrical charge of the 
carriers of the active matter, is the distance which they 
travel before reaching the electrode. If this distance be 
very small (a few millimetres) the particles are almost com- 
pletely directed to the negative pole, the ratio mentioned 
above therefore being very large; as the distance of travel is 
increased this ratio shows a marked diminution. 
The experiments indicate that the collisions of the active 
deposit particles with the gas molecules or ions with which 
they are mixed, determine the sign of the electrical charge 
which they exhibit. 
Methods of Experiment. 
The first experiments, which have already been partly 
described in the paper referred to above, were made in the 
following manner. 
Eur. 1. 
Two thin brass wires (A and B. fig. 1) 7*5 cms. long and 
•7 mm. diameter and 4 cms. apart, were made to lie along 
the axis of a brass tube C 3(J cms. long and 4*2 cms. diameter. 
This tube was fitted with a small capsule D into which was 
placed a small quantity of a preparation of actinium. 
The wire A was connected to the positive and B to the 
