﻿THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES] 



SEPTEMBER 1922. 



XLIL The Disintegration of Elements by a. Particles. By 

 Sir E. Rutherford. F.R.S., Cavendish Professor oj 

 Experimental Physics, and J. Chadwick, Ph.D., Clerk 

 Maxwell Scholar, University of Cambridge *. 



IN a former paper f we have shown that long-range 

 particles, which can be detected by their scintillations 

 on a zinc-sulphide screen, are liberated from the elements 

 boron, nitrogen, fluorine, sodium, aluminium, and phos- 

 phorus under the bombardment of a rays. The range of 

 these particles in air was greater than that of free hydrogen 

 nuclei set in motion by u particles. Using radium G as a 

 source of a rays, the range of the particles varied from 

 40 cm. for nitrogen to 90 cm. for aluminium, while the 

 range of free hydrogen nuclei under similar conditions 

 was about 29 cm. 



Previous experiments J by one of us had indicated that 

 the long-range particles from nitrogen were deflected in 

 a magnetic field to the extent to be expected if they were 

 swift hydrogen nuclei ejected from the nitrogen nucleus by 

 the impinging a particle. The nature of the particles from 

 the other five elements was not tested, but it seemed very 

 probable that the particles were in all cases H nuclei which 

 were released at different speeds depending on the nature of: 



* Communicated by the Authors. 



t Rutherford and Chad wick, Phil. Mag. vol. xlii. p. 809 (1921). 

 X Rutherford, Bakerian Lecture, Proc. Roy. Soc. A, vol. xcvii. p. 374 

 (1920). 



P/u7.J/a^.Ser.6.Vol.44.No.261.&?p*.1922. 2E 



