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 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



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JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



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XV. The Magnetic and Electric Deviabion<^-hke~~easily 

 absorbed Rays from Radium. By E. Rutherford, M.A., 

 D.Sc, Macdonald Professor of Physics, Me Gill University, 

 Montreal* . 



ADIUM gives out three distinct types of radiation: — 

 1 (1) The a. rays, which are very easily absorbed by thin 

 layers o£ matter, and which give rise to the greater portion 

 of the ionization of the gas observed under the usual 

 experimental conditions. 



(2) The ft rays, which consist of negatively charged par- 

 ticles projected with high velocity, and which are similar in 

 all respects to cathode rays produced in a vacuum-tube. 



(3) The y rays, which are non-deviable by a magnetic field, 

 and which are of a very penetrating character. 



These rays differ very widely in their power of penetratiug 

 matter. The following approximate numbers, which show 

 the thickness of aluminium traversed before the intensity is 

 reduced to one-half, illustrate this difference. 



Radiation. Thickness of Aluminium. 



ol rays '0005 cm. 



,6 rays '...,,. '05 cm. 



y rays 8 cms. 



In this paper an account will be given of some experiments 

 which show that the oc rays are (leviable by a strong magnetic 

 and electric field. The deviation is in the opposite sense to 



* Communicated by the Author. 

 Phil. Mag. iS. 6. Vol. 5. No. 26. Feb, L90& N 



