■538 Distribution of Energy in Different Types of 7 Rays. 



This shows that only about 2 per cent, of the total 7 energy 

 of radium B is concentrated in the soft type. At the same 

 time radium C emits 13*9 times more energy in form of 

 7 radiation than radium B. Robinson and Moseley in a 

 recent research by a different method obtained 13 5 for this 

 ratio. 



C<j 









I 



rig. 4. 











B 



A 



1 



^V 





















*" — — _ 



-^5 



'~^5 





£Z**»c 









N 



1 









































3 4 5- 6 



Cms. of Alum/n/um. 



The heating effect of the 7 radiation of radium B -f- radium 

 in equilibrium with one gr. of radium was found to be 

 6*4 gr. cal. per hour, or 7*92 x 10 4 erg sec. -1 *. If we have 

 one gram of radium in equilibrium with its products, then 



0*01 x 10" erg sec. -1 will be liberated in form of soft 7 ray s 



/x = 40 cm." 1 Al, 



0*49 x 10 4 erg sec." 1 in form of rays yu, = 0'51 cm." 1 Al, and 

 6*92 x 10* erg sec." 1 in form of the very hard rays of 



radium 0. 



Summary. 



(1) The absorption of the soft 7 rays from radium D in 

 gases is the same as the absorption of X rays from a " K " 

 radiator with a corresponding atomic weight. 



(2) The absorption of the soft 7 rays from radium 1) 

 follows an additive law. 



(3) The ionization produced by the soft 7 rays from 

 radium D in sulphur dioxide, carbon dioxide, and air is pro- 

 portional to the absorption of the same rays in these gases ; 

 this does not hold for sulphuretted hydrogen. 



(4) For the hard 7 rays from radium B and radium C 

 ionization is proportional to absorption. 



* Rutherford and Robinson, Phil. Mag. xxv. p. 312 (1913). 



