Tonization Curves of Radium. 139 
obtained in fig. 6, which shows well the first corner, at which 
the ionization due to the second induced activity makes its 
appearance. 
Fig, 6. 
(ep) N ee) 
DISTANCE 4M CM. FROM RADIUM T0 /ON/ISATICN CHAMBER. 
On 
at 
+ 
2 3 
O | 
LEAH OF ELECTROMETER IN MM DOIV/IS/ONS OF SCALE PER SECONO. 
Using a chamber of 4 ems. radius we obtained results 
represented by the curves in fig. 7 (p. 736). For one of 
these the ionization chamber was shallower than for the other. 
These show the two bottom corners, the lowest showing the 
point where the rays from the first break-down make their 
appearance, the upper probably representing the commence- 
ment of the emanation rays. The use of spherical chambers 
somewhat raises the points at which the various sets of rays 
make their appearance, as is to be expected. The higher 
values should be the more correct. 
A very remarkable experiment has been made and described 
by Becquerel, which showed that the trace of fine sheet of 
a rays upon a photographic plate possessed less curvature, 
when deflected by a magnet, at greater distances from the 
source. If we seek an explanation on the basis of the hypo- 
thesis already referred to, we find at once that one side of 
the trace ought to show this effect. : 
3K 2 
