﻿y-Rays 
  of 
  Uranium 
  and 
  Radium, 
  639 
  

  

  considerably 
  less 
  than 
  if 
  all 
  the 
  metal 
  was 
  clamped 
  up 
  to 
  the 
  

   base 
  and 
  the 
  radium 
  tube 
  left 
  bare. 
  The 
  difference 
  in 
  the 
  

   leaks 
  due 
  to 
  the 
  two 
  dispositions 
  it 
  would 
  seem 
  natural 
  to 
  

   ascribe 
  to 
  the 
  generation 
  of 
  secondary 
  rays 
  in 
  the 
  slate 
  bench 
  

   and 
  elsewhere 
  sufficiently 
  penetrating 
  to 
  get 
  through 
  the 
  walls 
  

   of 
  the 
  electroscope, 
  which 
  are 
  produced 
  in 
  greater 
  intensity 
  

   in 
  the 
  first 
  case 
  than 
  in 
  the 
  second. 
  In 
  consequence 
  the 
  lead, 
  

   all 
  except 
  the 
  2'%-^ 
  cm. 
  forming 
  the 
  base, 
  was 
  placed 
  directly 
  

  

  Fig. 
  2. 
  

  

  y-Rays. 
  Variation 
  of 
  Absorption 
  -with 
  Distance 
  of 
  Radium 
  from 
  

   the 
  Electroscope. 
  

  

  over 
  the 
  radium. 
  The 
  radium 
  was 
  placed 
  below 
  the 
  electro- 
  

   scope 
  at 
  distances 
  varying 
  from 
  15*1 
  cm. 
  to 
  114-6 
  cm. 
  The 
  

   absorption-curves 
  obtained 
  are 
  shown 
  in 
  fig. 
  2. 
  For 
  the 
  

  

  