﻿Absorption 
  of 
  the 
  7 
  Rays 
  of 
  Radium. 
  617 
  

  

  than 
  through 
  other 
  angles, 
  and 
  as 
  i£ 
  very 
  little 
  more 
  radia- 
  

   tion 
  was 
  scattered 
  in 
  the 
  emergent 
  direction 
  than 
  in 
  the 
  

   incident. 
  The 
  similarity 
  to 
  the 
  scattering 
  of 
  X 
  rays 
  will 
  be 
  

   noted, 
  and 
  although 
  the 
  experiments 
  are 
  only 
  approximate. 
  

  

  Fi*. 
  2. 
  

  

  4 
  3 
  

  

  we 
  can 
  say 
  that 
  the 
  scattering 
  of 
  a 
  beam 
  of 
  7 
  rays 
  is 
  not 
  at 
  

   all 
  similar 
  to 
  that 
  of 
  a 
  pencil 
  of 
  a 
  or 
  /3 
  rays. 
  There 
  is 
  little 
  

   doubt 
  that 
  the 
  scattering 
  of 
  X 
  and 
  7 
  rays 
  is 
  the 
  same 
  in 
  

   character, 
  there 
  being 
  probably 
  gradual 
  changes 
  in 
  the 
  

   quality 
  and 
  distribution 
  of 
  the 
  scattered 
  radiation 
  as 
  the 
  X 
  

   or 
  7 
  radiation 
  increases 
  in 
  penetrating 
  power. 
  With 
  the 
  

   different 
  types 
  of 
  7 
  rays 
  at 
  our 
  disposal 
  there 
  is 
  probably 
  

   very 
  little 
  change 
  in 
  the 
  distribution 
  of 
  the 
  scattered 
  radia- 
  

   tion 
  as 
  the 
  penetrating 
  power 
  varies, 
  although 
  the 
  softer 
  the 
  

   rays 
  the 
  more 
  they 
  are 
  scattered 
  per 
  unit 
  mass. 
  

  

  The 
  primary 
  rays 
  in 
  the 
  present 
  case 
  are 
  always 
  hetero- 
  

   geneous, 
  and 
  if 
  we 
  suppose 
  there 
  is 
  no 
  change 
  in 
  quality 
  pro- 
  

   duced 
  by 
  scattering 
  and 
  neglect 
  absorption 
  in 
  the 
  radiator, 
  the 
  

   scattered 
  rays 
  would 
  be 
  softer 
  on 
  the 
  whole, 
  but 
  there 
  would 
  

   be 
  no 
  change 
  in 
  quality 
  as 
  the 
  angle 
  of 
  scattering 
  increased. 
  

   Further, 
  after 
  passing 
  through 
  a 
  few 
  millimetres 
  of 
  lead, 
  the 
  

   scattered 
  rays 
  would 
  be 
  of 
  about 
  the 
  same 
  penetrating 
  power 
  

   as 
  the 
  primary. 
  We 
  are 
  therefore 
  forced 
  to 
  the 
  second 
  

   explanation, 
  and 
  this 
  is 
  quite 
  sufficient. 
  The 
  change 
  in 
  

   quality 
  is 
  probably 
  very 
  small 
  when 
  the 
  angle 
  of 
  scattering- 
  

   is 
  small, 
  as 
  experiment 
  shows 
  that 
  in 
  this 
  case 
  the 
  scattered 
  

  

  