﻿Absorption 
  of 
  'the 
  7 
  Rays 
  of 
  Radium. 
  613 
  

  

  radium 
  bromide 
  was 
  used. 
  This 
  was 
  enclosed 
  in 
  a 
  sealed 
  

   glass 
  tube, 
  the 
  latter 
  being 
  placed 
  in 
  a 
  lead 
  cylinder, 
  the 
  

   lead 
  being 
  1*7 
  mm. 
  thick. 
  A 
  ]5 
  A 
  2 
  represent 
  different 
  posi- 
  

   tions 
  of 
  the 
  active 
  material, 
  R 
  l5 
  R 
  2 
  corresponding 
  positions 
  

   of 
  the 
  radiators, 
  S 
  1? 
  S 
  2 
  blocks 
  of 
  lead 
  to 
  screen 
  the 
  electro- 
  

   scope 
  E 
  from 
  direct 
  7 
  radiation, 
  Lj, 
  L 
  2 
  lead 
  plates 
  to 
  cut 
  

   down 
  the 
  intensity 
  of 
  the 
  primary 
  radiation, 
  and 
  M 
  a 
  lead 
  

   plate 
  to 
  test 
  the 
  penetrating 
  power 
  of 
  the 
  scattered 
  radiation 
  

   from 
  the 
  radiator. 
  The 
  electroscope 
  E 
  was 
  a 
  14 
  cm. 
  cube, 
  

   and 
  all 
  sides 
  except 
  the 
  vertical 
  sides 
  BC 
  and 
  DF 
  were 
  of 
  

   iron 
  1 
  mm. 
  thick 
  covered 
  by 
  lead 
  2 
  mm. 
  thick. 
  The 
  scattered 
  

   rays 
  entered 
  the 
  electroscope 
  through 
  the 
  side 
  BC, 
  and 
  this 
  

   was 
  closed 
  by 
  aluminium 
  1/60 
  mm. 
  thick, 
  and 
  in 
  front 
  of 
  

   this 
  was 
  placed 
  a 
  carbon 
  plate 
  P 
  2*7 
  cm. 
  thick. 
  The 
  carbon 
  

   cut 
  off 
  j3 
  rays 
  from 
  the 
  radiators 
  and 
  only 
  a 
  small 
  percentage 
  

   of 
  7 
  rays. 
  The 
  side 
  DF 
  was 
  closed 
  by 
  aluminium 
  1/60 
  mm. 
  

   thick, 
  and 
  behind 
  this 
  was 
  placed 
  a 
  plate 
  of 
  carbon 
  1 
  cm. 
  

   thick 
  and 
  a 
  lead 
  plate 
  2 
  mm. 
  thick. 
  The 
  electroscope 
  and 
  

   radiators 
  were 
  supported 
  by 
  as 
  little 
  material 
  as 
  possible, 
  all 
  

   supports 
  being 
  covered 
  by 
  lead 
  to 
  reduce 
  the 
  effect 
  of 
  any 
  

   secondary 
  radiation 
  from 
  them. 
  

  

  In 
  the 
  position 
  A 
  1? 
  R 
  x 
  the 
  angle 
  of 
  scattering 
  was 
  about 
  

   50°. 
  Three 
  radiators 
  were 
  used, 
  viz.: 
  — 
  

  

  A 
  carbon 
  radiator 
  12'5 
  cm. 
  high, 
  7*5 
  cm. 
  broad, 
  and 
  

  

  5'84 
  cm. 
  deep, 
  mass 
  923 
  grammes; 
  

   an 
  iron 
  radiator 
  12*9 
  cm. 
  high, 
  8 
  cm. 
  broad, 
  and 
  1*28 
  cm. 
  

  

  deep, 
  mass 
  1020 
  grammes; 
  

   a 
  lead 
  radiator 
  11cm. 
  high, 
  7*6 
  cm. 
  broad, 
  and 
  '88 
  cm. 
  

  

  deep, 
  mass 
  840 
  grammes. 
  

  

  In 
  the 
  position 
  A 
  2 
  , 
  R 
  2 
  the 
  angle 
  of 
  scattering 
  was 
  about 
  

   110°, 
  and 
  the 
  following 
  radiators 
  were 
  used 
  : 
  — 
  

  

  A 
  carbon 
  radiator 
  15 
  cm. 
  high, 
  15 
  cm. 
  broad, 
  and 
  6*4 
  cm. 
  

   deep; 
  

  

  an 
  iron 
  radiator 
  15 
  cm. 
  high, 
  15 
  cm. 
  broad, 
  and 
  1*7 
  cm. 
  

  

  deep; 
  

   a 
  lead 
  radiator 
  15 
  cm. 
  high, 
  15 
  cm. 
  broad, 
  and 
  03 
  cm. 
  

  

  deep. 
  

  

  Readings 
  were 
  taken 
  with 
  and 
  without 
  the 
  radiator, 
  the 
  

   difference 
  being 
  due 
  to 
  the 
  scattered 
  radiation. 
  The 
  intensity 
  

   of 
  the 
  primary 
  rays 
  was 
  measured 
  directly. 
  The 
  readings 
  

   are 
  given 
  in 
  Tables 
  I. 
  and 
  II. 
  in 
  divisions 
  per 
  minute. 
  The 
  

   reading 
  without 
  a 
  radiator 
  varied 
  between 
  3'5and 
  7 
  divisions 
  

   per 
  minute. 
  

  

  Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  2G. 
  No. 
  154. 
  Oct. 
  1913. 
  2 
  T 
  

  

  