﻿2S6 
  

  

  Dr. 
  A. 
  S. 
  Eve 
  on 
  Primary 
  

  

  Gamma 
  Rays 
  from 
  Uranium 
  X, 
  

  

  About 
  1^ 
  kilograms 
  of 
  iiranyl 
  nitrate 
  were 
  placed 
  in 
  a 
  

   cylindrical 
  glass 
  vessel 
  so 
  as 
  to 
  form 
  a 
  layer 
  about 
  6 
  cm. 
  

   thick. 
  This 
  was 
  placed 
  beneath 
  the 
  vertical 
  cylindrical 
  

   electroscope 
  described 
  earlier 
  in 
  the 
  paper, 
  plates 
  were 
  fixed 
  

   close 
  to 
  the 
  electroscope 
  and 
  the 
  emergent 
  secondary 
  radiation 
  

   was 
  observed 
  by 
  the 
  reversal 
  method. 
  The 
  7 
  rays 
  from 
  

   uranium 
  X 
  are 
  feeble, 
  and 
  the 
  measurements 
  were 
  difficult 
  

   and 
  uncertain 
  ; 
  but 
  the 
  results 
  obtained 
  were 
  : 
  — 
  

  

  U: 
  

  

  raniu] 
  

   Pb 
  

  

  m, 
  7 
  ra 
  

  

  ys. 
  ± 
  

   .. 
  100 
  

  

  Sn 
  

  

  

  76 
  

  

  Cu 
  

  

  

  . 
  70 
  

  

  Zn.. 
  

  

  

  . 
  70 
  

  

  Emergent 
  secondary 
  radiation. 
  

  

  Fe 
  

   Al 
  

  

  C. 
  

  

  72 
  

   77 
  

   90 
  

  

  The 
  curve 
  is 
  given 
  in 
  fig. 
  5, 
  and 
  it 
  shows 
  that 
  the 
  7 
  rays 
  

   from 
  uranium 
  X 
  resemble 
  those 
  of 
  Ra 
  C 
  more 
  nearly 
  than 
  

   they 
  resemble 
  the 
  secondary 
  7 
  rays 
  due 
  to 
  Ra 
  C. 
  It 
  would 
  

   be 
  interesting 
  to 
  obtain 
  the 
  curve 
  more 
  correctly 
  with 
  uranium 
  

   X 
  concentrated 
  in 
  the 
  manner 
  recently 
  described 
  by 
  Soddy 
  *. 
  

  

  The 
  five 
  curves 
  seen 
  in 
  figs. 
  3 
  and 
  5 
  show 
  the 
  gradual 
  

   changes 
  in 
  the 
  emergent 
  secondary 
  radiation 
  from 
  very 
  soft 
  

   to 
  very 
  hard 
  7 
  rays. 
  

  

  Reversals 
  ivith 
  Four 
  Plates. 
  

  

  It 
  is 
  now 
  possible 
  to 
  explain 
  the 
  results 
  obtained 
  by 
  

   reversing 
  the 
  order 
  of 
  plates 
  at 
  the 
  front 
  and 
  back 
  of 
  the 
  

   electroscope. 
  Let 
  the 
  plates 
  A, 
  B, 
  C, 
  D 
  consist 
  two 
  of 
  

   aluminium, 
  two 
  of 
  lead 
  ; 
  then 
  the 
  ionization 
  currents 
  in 
  the 
  

   electroscopes 
  for 
  the 
  arrangements 
  stated 
  have 
  the 
  following 
  

   relative 
  values, 
  when 
  the 
  7 
  rays 
  have 
  passed 
  through 
  a 
  screen 
  

   of 
  lead 
  0*6 
  cm. 
  thick. 
  

  

  

  A. 
  

  

  B. 
  

  

  C. 
  

  

  D. 
  

  

  Eve. 
  

  

  Bragg. 
  

  

  I 
  

  

  Al 
  

  

  Pb 
  

  

  Pb 
  

  

  Al 
  

  

  100 
  

  

  100 
  

  

  II 
  

  

  Pb 
  

  

  Al 
  

  

  Pb 
  

  

  Al 
  

  

  98-5 
  

  

  99-5 
  

  

  Ill 
  

  

  Al 
  

  

  Pb 
  

  

  Al 
  

  

  Pb 
  

  

  83-5 
  

  

  81-0 
  

  

  IV 
  

  

  Pb 
  

  

  Al 
  

  

  Al 
  

  

  - 
  

  

  81-1 
  

  

  82-5 
  

  

  Nature/ 
  28 
  Jan. 
  1909. 
  

  

  