﻿Analysis 
  of 
  ft 
  Rays 
  from 
  Radium 
  B 
  and 
  Radium 
  C. 
  Ill 
  

  

  It 
  is 
  impossible 
  to 
  discuss 
  here 
  the 
  nature 
  of 
  the 
  structure 
  

   giving 
  rise 
  to 
  the 
  symmetrical 
  patterns 
  until 
  further 
  ex- 
  

   periments 
  have 
  been 
  carried 
  out. 
  A 
  variation 
  in 
  the 
  nature 
  

   of 
  the 
  anti-cathode 
  may 
  throw 
  further 
  light 
  on 
  the 
  matter. 
  

  

  During 
  the 
  writing 
  of 
  this 
  paper 
  a 
  brief 
  announcement 
  

   has 
  appeared 
  by 
  E. 
  Hupka 
  (Rhys. 
  Zeitsclir. 
  xiv. 
  p. 
  623) 
  of 
  

   similar 
  figures 
  obtained 
  with 
  platinum 
  and 
  gold 
  sheets, 
  while 
  

   nothing 
  was 
  obtained 
  with 
  iron 
  and 
  aluminium. 
  The 
  anti- 
  

   cathode 
  of 
  the 
  X-ray 
  tube 
  used 
  in 
  E. 
  Hupka's 
  experiments 
  

   was 
  of 
  platinum. 
  

  

  July 
  27, 
  1913. 
  

  

  LIX. 
  The 
  Analysis 
  of 
  the 
  ft 
  Rays 
  from 
  Radium 
  B 
  and 
  

   Radium 
  C. 
  By 
  Professor 
  E. 
  Rutherford, 
  F.R.S., 
  and 
  

   H. 
  Robinson, 
  M.Sc, 
  Lecturer 
  in 
  the 
  University 
  of 
  

   Manchester 
  *. 
  

  

  [Plate 
  XII.] 
  

  

  I^HE 
  problem 
  of 
  the 
  distribution 
  of 
  the 
  ft 
  rays 
  from 
  

   radioactive 
  substances 
  with 
  regard 
  to 
  velocity 
  has 
  

   been 
  the 
  subject 
  of 
  much 
  experiment 
  and 
  discussion. 
  As 
  

   the 
  history 
  of 
  this 
  subject 
  has 
  been 
  previously 
  treated 
  in 
  

   some 
  detail 
  by 
  one 
  of 
  us 
  f 
  , 
  it 
  is 
  only 
  necessary 
  here 
  to 
  draw 
  

   attention 
  to 
  the 
  more 
  recent 
  and 
  salient 
  facts. 
  A 
  great 
  

   advance 
  in 
  our 
  knowledge 
  was 
  made 
  by 
  the 
  experiments 
  of 
  

   Hahn, 
  Baeyer, 
  and 
  Meitner, 
  who 
  showed 
  that 
  the 
  ft 
  rays 
  

   from 
  the 
  majority 
  of 
  radioactive 
  substances 
  consisted 
  of 
  

   a 
  number 
  of 
  separate 
  groups, 
  each 
  of 
  well-defined 
  velocity. 
  

   If 
  a 
  narrow 
  pencil 
  of 
  ft 
  rays, 
  falling 
  normally 
  on 
  a 
  photo- 
  

   graphic 
  plate, 
  were 
  deflected 
  by 
  a 
  magnetic 
  field, 
  the 
  

   radiation 
  was 
  split 
  up 
  into 
  its 
  component 
  groups 
  and 
  a 
  

   veritable 
  spectrum 
  was 
  observed. 
  This 
  showed 
  that 
  the 
  

   radiation, 
  while 
  heterogeneous 
  in 
  type, 
  was 
  made 
  up 
  of 
  a 
  

   number 
  of 
  distinct 
  groups 
  of 
  ft 
  rays, 
  each 
  of 
  which 
  com- 
  

   prised 
  ft 
  particles, 
  which 
  were 
  expelled 
  from 
  the 
  radioactive 
  

   substance 
  with 
  a 
  definite 
  and 
  characteristic 
  velocity. 
  A 
  

   further 
  advance 
  was 
  made 
  by 
  Danysz 
  J 
  who 
  examined, 
  also 
  

   by 
  a 
  photographic 
  method, 
  the 
  deflexion 
  in 
  a 
  magnetic 
  field 
  

   of 
  the 
  ft 
  rays 
  emitted 
  from 
  an 
  intense 
  source 
  of 
  radium 
  

   emanation 
  enclosed 
  in 
  a 
  thin-walled 
  glass 
  tube. 
  The 
  ft 
  rays 
  

   in 
  this 
  case 
  do 
  not 
  come 
  from 
  the 
  emanation 
  but 
  from 
  its 
  

  

  * 
  Communicated 
  by 
  the 
  Authors. 
  

  

  f 
  Rutherford, 
  ' 
  Kadioactive 
  Substances 
  and 
  their 
  Radiations,' 
  

   pp. 
  209-212 
  (1913). 
  

  

  + 
  Danvsz, 
  Compt. 
  Rend. 
  153, 
  pp. 
  339, 
  106Q 
  (1911) 
  ; 
  Le 
  Radium, 
  ix. 
  

   p. 
  1 
  (1912). 
  

  

  