20 THE ROYAL SOCIETY OF CANADA 
exceedingly small in comparison with that of the walls of the chamber 
the deposits obtained on it at different pressures could not be taken 
as measures of the number of active deposit particles present which 
carried a positive charge. 
Some information might also be obtained regarding 4 and q 
separately by arranging suitable experiments with an active emanation 
possessing a longer life than that from actinium, for example, that from 
radium. ; 
If a quantity of radium salt were confined in a chamber to which 
a second was attached which could be cooled down with liquid air, 
the emanation expelled by the salt in a given time could be collected 
in the second chamber. This could be done for a series of different 
pressures, care being taken to see that the condensation was carried 
on for periods sufficiently long to eliminate differences in the rate of 
diffusion of the emanation from the first chamber to the second. Measure- 
ments made on the amount of emanation obtained in a second chamber, 
would then give information directly about q, the rate at which the 
emanation from radium left the salt at different pressures. 
To obtain information about the factor a it would suffice to make 
repeated exposures of a negatively charged electrode of small surface 
to equal quantities of radium emanation at a number of different 
pressures. The experimental arrangements outlined in the preceding 
paragraph would probably suffice to enable one to repeatedly obtain 
in the second chamber a definite amount of emanation. These repeated 
condensations could be made at a very low air pressure and then, if 
the second or condensation chamber were cut off from the first and 
air afterwards admitted into it to any selected pressure it could be used 
as the exposure chamber as well. This would enable one to find how 
the number of positively charged active deposit particles from a given 
amount of radium emanation varied with the pressure of the air in which 
the emanation was diffusing. 
If a and q were found separately in this way with the emanation 
from radium, one could see whether or not their product varied in 
accordance with such a law as that represented by (5), and from the 
resulting agreement or lack of it one could come to some definite con- 
clusion regarding the validity of the explanation offered in the present 
communication of the results obtained by Kennedy. 
If the law enunciated in (5) were confirmed by the experiments 
just described the result would go to show that active deposit particles 
at the instant of their creation are uncharged, and that the positive 
charge usually found on them when diffusing in gases at ordinary 
pressures is acquired at a stage later than that of their creation from 
the surrounding ionised gas. 
