Lroj-herford] properties OF THE a R.IYS FROM RADIUM 7 



The following table shows the results obtained for values of d^ of 

 2, 3, and 4 cms. respectively; ^2 =1-0 cm. in all cases: — 



The values of p are thus in as good agreement as could be expected, 

 since the magnet was excited by 110 volt power circuit, whose E.M.F. 

 occasionally fluctuated. These results show that over the whole range 

 examined, the path of the rays is a circle of mean radius of curvature 

 of 42.0 cms. 



The strength of the magnetic field H was constant in all the experi- 

 ments and was equal to 9470 C.G.S. units. Thus the value of 

 Hp = 3.98 X 10\ 



The ex rays from radium C are the most penetrating of all those 

 emitted from the various products of radium and, presumably therefore, 

 are expelled with the greatest velocity. In a previous paper (loc. cit.), 

 I deduced that the maximum value of Hp for radium rays was 

 390,000. This result was obtained by means of the electric method, 

 using radium in radioactive equilibrium as a source of rays. Becquerel 

 has shown that the value of H/3 was not a constant, if measured by 

 means of the trace obtained on a photographic plate when the rays 

 from radium passed through air at atmospheric pressure. The value 

 of Hp varied between 291,000 and 341,000. This result is clear in 

 light of the experiments discussed later. The pencil of rays was not 

 homogeneous, as Becquerel thought, but included a particles projected 

 with different velocities, which consequently were deflected to different 

 extents. An explanation of the results of Becquerel along these lines 

 has been given by Bragg (loc. cit.). 



We know from the action of a magnetic field on a moving charged 



m 



body that lip = - V where m is the mass of the particle, V its velocity 



and e its charcre. 



Thus - V = 3.98 X 10\ 

 e 



The experiments on the deflection of the oc rays in passing through 

 an electric field are not yet completed; they are complicated by the fact 

 that a vacuum, sufficiently high to allow of a large difference of potential 



