76 THE ROYAL SOCIETY OF CANADA 
The mean value obtained in this way was K/K’ == 34, and since K’ 
= 3-74 X 10° from (1), it follows that 
K = 1-27 x 10" (3) 
Hence the total number of ions produced by the 8 rays from one 
eurie of radium C in air at atmospheric pressure is 
4 K/u—4TX1:27 x 10"/-004—4-0 x 104 (4) 
The corresponding value for radium B is about 13/75 of this, or 
about 0-7 x 10". (5) 
And, due to the B rays from both, 4-7 x 10". 
4. Instead of assuming the values for u as above, its value was 
actually determined for distances from 40 to 100 cm., and was found 
to be between -012 and -013. This magnitude suggests the joint effect 
of radium C and radium B. The value pf u did not, however, appear 
to decrease with the time as the proportion of radium C to radium B 
increased. There seems to be, therefore, proceeding from radium C a 
large number of low velocity B rays, somewhat similar to those from 
radium B. If the value for K/K’ is determined with a value for u 
intermediate between -004 and -012, namely, -008, I found from several 
an K/K’ =117, whence K— 4-35 x 104, and N — 4 7 x 10" 
/ 008 — 6-8 x 10" ne the rays from ac B. 
It is quite clear that the total number of ions due to the 6 rays 
from a curie of radium C cannot be easily determined with any great 
precision, but the number lies between 4 and 6 times 10". 
The difficulties are :— 
(1) The presence of radium B. 
(2) The complex character of the rays from radium C. 
(3) The uncertainty as to the entire removal of the y rays 
when measuring the 8 ray effect. The work requires repetition 
by those who are fortunate enough to be able to obtain a large 
amount of the active deposit of radium. 
Average Total Ions for One B Particle, and the Ions Per Unit Path. 
It has been found by Makower* that a gramme of radium emits 
about 510" particles per second, and theory suggests that radium B 
and radium C both emit 3-4 x10" 8 particles per second, corresponding 
to the known number of 4 particles. 
* Phil. Mag. Jan. 1909. 
