110 



Dr. W. Makower and Dr. S. Russ on the 



the particles are radiated in all directions at random seems, 

 however, insufficient to entirely account for the smallness of 

 the fraction of radium C particles which succeed in getting 

 free from the radiating surface. 



Fte. 



too 



Note to Curve 

 Line thus — 



Z 3 4. £ 



represents the Experimental Curve. 



„ „ Inverse Square Law Curve. 



„ „ Cosine Law Curve. 



The Absorption of Radium C by Air. 



When radium B is transformed into radium G, the process 

 is supposed to be accompanied only by the emission of 

 /3 particles of low velocity *. It therefore follows that the 

 energy possessed by a radium G atom after recoil should be 

 exceedingly small compared with that of an atom of radium B 

 when produced from radium A or with that of any atom which 

 recoils as the result of the emission of an cc particle. On this 

 account, the power of penetrating matter possessed by an atom 

 of radium G should be very much smaller than that, say, of an 

 atom of radium A or radium B when projected from a dis- 

 integrating atom. For if we take the mass of an atom of 

 radium A to be 218 and that of an a particle to be 4, and its 



* H. W. Schmidt, Phys. ZeiUchr 

 xxi. p. 609. 



p. 897, and Annalen der Physik, 



