5G2 Number of Ions produced by Beta Rays from Radium C. 



It seems, then, correct to speak of a 7 ray in the sense of 

 a definite entity carrying energy in a linear path, unless, 

 indeed, most of the energy of ionization comes from the 

 molecule ionized, a view which is generally rejected. 



Summary. 



1. The value of the constant K / for y rays, which may he 

 given the theoretical definition of the number of ions produced 

 per cm. 3 per second at a distance of 1 cm. from a curie of. 

 radium C, in air at atmospheric pressure, is 3*74 x 10°. 

 The total number of ions per second which the 7 rays from a 

 curie of radium C could produce in air at atmospheric pressure 

 isN' = l-lxl0 15 . 



2. Corresponding values for the ft rays have been found 

 approximately, namely, K = l/3 x 10 11 , and N = 4'0x 10 u . 



3. Hence, the total number of ions made by one ft particle 

 in an average flight from radium C in the atmosphere is 

 1*2 X 10 4 , equivalent to about 48 ions per cm. Hence, the 

 ft particle must pass through about 180 molecules for every 

 one which it ionizes, if the radius of a molecule is 10 " 8 cm. 

 The values in (2) and (3) are only approximations. 



4. If the 7 ray is an entity with a linear path, the total 

 ions per entity are 3 X 10 4 for an average flight, and 1*2 ions 

 per cm. of path. 



5. The heating effect of the ft and y rays may be calculated 

 on the assumption that ionization is a measure of the energy 

 expsnded. If a gramme of radium, and its four succeeding 

 products, have a heating effect of 110 calories per hour, then 

 the distribution is somewhat as follows : — 



a rays 103*5 calories. 



£ ,, 2-0 „ 



7 » 4'5 



6. The energy expended in making an ion is calculated as 

 5'2 x 10~ n erg, and the radius of the molecule as '46 x 10~ 8 , 

 a result which is of the right order, but probablj r too small. 



Montreal, 

 April, 1911. 



