﻿Disintegration 
  of 
  Uranium 
  A. 
  531 
  

  

  precipitation 
  it 
  is 
  found 
  that 
  at 
  that 
  moment 
  the 
  activity 
  

   would 
  be 
  158*5 
  divs. 
  per 
  min. 
  A 
  small 
  quantity 
  of 
  thorium 
  

   was 
  added 
  to 
  the 
  filtrate 
  from 
  this 
  bismuth 
  oxychloride 
  

   precipitate 
  and 
  precipitated 
  as 
  oxalate. 
  Measured 
  after 
  

  

  Fig. 
  1. 
  

  

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  some 
  hours 
  the 
  activity 
  of 
  this 
  oxalate 
  precipitate 
  was 
  

   167*1 
  divs. 
  per 
  min. 
  Thus 
  it 
  is 
  shown 
  that 
  94*5 
  per 
  cent, 
  of 
  

   the 
  equilibrium 
  amount 
  of 
  the 
  hard 
  {3 
  rays 
  of 
  uranium 
  X 
  

   had 
  been 
  removed. 
  A 
  large 
  number 
  of 
  experiments 
  have 
  

   been 
  made 
  trying 
  to 
  repeat 
  this 
  separation, 
  but 
  it 
  has 
  never 
  

   been 
  effected 
  with 
  the 
  same 
  completeness. 
  Two 
  or 
  three 
  

   times, 
  however, 
  by 
  adding 
  water 
  to 
  a 
  strongly 
  acid 
  solution 
  

   of 
  uranium 
  X 
  a 
  slight 
  precipitate, 
  or 
  sometimes 
  merely 
  a 
  

   cloudiness, 
  has 
  been 
  obtained, 
  and 
  on 
  filtering 
  the 
  liquid 
  the 
  

   paper 
  was 
  found 
  to 
  have 
  an 
  activity 
  which 
  decayed 
  to 
  nearly 
  

   zero 
  in 
  eight 
  minutes. 
  The 
  period 
  of 
  average 
  life 
  of 
  the 
  

   substance 
  when 
  calculated 
  from 
  these 
  curves 
  was 
  found 
  to 
  be 
  

   from 
  1*4 
  to 
  1*7 
  minutes. 
  The 
  period 
  of 
  average 
  life 
  of 
  the 
  

   substance 
  may 
  therefore 
  be 
  taken 
  as 
  1*6 
  minutes. 
  This 
  

   agrees 
  well 
  with 
  Fajans 
  and 
  Gohring's 
  period 
  of 
  half-value 
  

   of 
  1*1 
  minutes. 
  

  

  The 
  form 
  of 
  the 
  difference 
  decay 
  curves 
  is 
  the 
  same 
  

   whether 
  the 
  preparation 
  is 
  measured 
  through 
  O'l 
  mm. 
  or 
  

   0*0034 
  mm. 
  thick 
  aluminium 
  foil, 
  but 
  in 
  the 
  latter 
  case, 
  

  

  