﻿Investigation 
  of 
  the 
  Nature 
  of 
  7 
  Rays. 
  919 
  

  

  readily 
  explained 
  i£ 
  the 
  7 
  rays 
  are 
  supposed 
  to 
  be 
  material, 
  

   but 
  are 
  not 
  easily 
  to 
  be 
  reconciled 
  with 
  the 
  aether-pulse 
  

   hypothesis. 
  

  

  §1. 
  

  

  In 
  the 
  former 
  paper 
  we 
  showed 
  that 
  on 
  the 
  neutral-pair 
  

   hypothesis 
  the 
  connexion 
  between 
  the 
  amount 
  of 
  secondary 
  

   /3 
  radiation 
  emitted 
  from 
  the 
  front 
  side 
  of 
  a 
  plate 
  struck 
  by 
  

   y 
  rays 
  and 
  the 
  atomic 
  weight 
  of 
  the 
  material 
  of 
  the 
  plate 
  

   should 
  be 
  approximately 
  the 
  same 
  as 
  for 
  the 
  /3 
  rays. 
  It 
  is, 
  

   of 
  course, 
  known 
  that 
  this 
  is 
  actually 
  the 
  case. 
  Also, 
  we 
  

   showed 
  that 
  the 
  ft 
  radiation 
  emitted 
  from 
  the 
  other 
  side 
  of 
  

   the 
  plate, 
  the 
  side 
  from 
  which 
  the 
  7 
  rays 
  emerge, 
  should 
  be 
  

   the 
  same 
  for 
  all 
  substances, 
  provided 
  three 
  things 
  were 
  true, 
  

   viz. 
  : 
  — 
  

  

  (1) 
  The 
  7 
  rays 
  were 
  homogeneous 
  ; 
  

  

  (2) 
  The 
  7 
  rays 
  were 
  absorbed 
  according 
  to 
  a 
  simple 
  density 
  

  

  law 
  ; 
  

  

  (3) 
  The 
  /3 
  rays 
  were 
  also 
  absorbed 
  according 
  to 
  such 
  a 
  

  

  law. 
  

  

  If 
  these 
  laws 
  did 
  not 
  hold, 
  and 
  to 
  the 
  extent 
  to 
  which 
  they 
  

   did 
  not 
  hold, 
  the 
  " 
  emergence 
  " 
  radiation 
  would 
  not 
  be 
  the 
  

   same 
  for 
  all 
  substances. 
  

  

  The 
  experimental 
  evidence 
  which 
  we 
  submitted 
  showed 
  

   that 
  the 
  emergence 
  radiation 
  was 
  not 
  connected 
  with 
  the 
  

   atomic 
  weight 
  of 
  the 
  material 
  by 
  the 
  same 
  law 
  as 
  that 
  which 
  

   held 
  for 
  the 
  incidence 
  radiation 
  and 
  for 
  /3 
  rays 
  ; 
  that 
  it 
  was 
  

   much 
  more 
  nearly 
  the 
  same 
  for 
  all 
  substances, 
  and 
  that 
  such 
  

   differences 
  as 
  existed 
  (e. 
  g., 
  carbon 
  generally 
  gave 
  more 
  than 
  

   lead) 
  appeared 
  to 
  be 
  proper, 
  in 
  view 
  of 
  the 
  conditions 
  stated 
  

   above. 
  As 
  the 
  results 
  we 
  had 
  obtained 
  seemed 
  to 
  be 
  sufficient 
  

   to 
  give 
  a 
  criterion 
  between 
  the 
  material 
  and 
  the 
  sether-pulse 
  

   theories, 
  we 
  thought 
  it 
  right 
  to 
  publish 
  the 
  details 
  of 
  the 
  

   work 
  as 
  far 
  as 
  we 
  had 
  carried 
  it. 
  

  

  We 
  have 
  now 
  made 
  a 
  more 
  thorough 
  investigation 
  of 
  the 
  

   nature 
  and 
  amount 
  of 
  emergence 
  radiation. 
  We 
  believe 
  that 
  

   we 
  are 
  in 
  a 
  position 
  to 
  connect 
  together 
  all 
  the 
  effects 
  atten- 
  

   dant 
  on 
  the 
  absorption 
  of 
  the 
  7 
  rays, 
  and 
  the 
  consequent 
  

   production 
  of 
  ft 
  rays, 
  to 
  a 
  first 
  approximation 
  at 
  least. 
  In- 
  

   cluded 
  in 
  these 
  effects 
  are 
  some 
  which 
  have 
  come 
  to 
  light 
  

   during 
  this 
  work, 
  the 
  neutral-pair 
  theory 
  having 
  led 
  us 
  to 
  

   their 
  discovery. 
  

  

  It 
  is 
  not 
  a 
  very 
  easy 
  thing 
  to 
  obtain 
  an 
  exact 
  measure 
  of 
  

   the 
  emergence 
  radiation. 
  When 
  a 
  stream 
  of 
  7 
  rays 
  is 
  shot 
  

   into 
  an 
  ionization-chamber 
  through 
  a 
  plate 
  forming 
  one 
  of 
  

  

  