﻿298 
  Dr. 
  H. 
  L. 
  Bronson 
  : 
  Relative 
  Activity 
  of 
  Emanation 
  

  

  are 
  of 
  very 
  little 
  value 
  in 
  the 
  case 
  of 
  thorium. 
  However, 
  in 
  

   this 
  case 
  the 
  differences 
  between 
  columns 
  V. 
  and 
  VI. 
  are 
  

   comparatively 
  small. 
  

  

  The 
  following 
  calculation 
  of 
  the 
  ratio 
  at 
  the 
  bottom 
  of 
  

   column 
  VI. 
  shows 
  the 
  method 
  used. 
  The 
  values 
  of 
  the 
  

   ionizations 
  are 
  taken 
  from 
  an 
  extrapolation 
  of 
  the 
  above 
  

   figure. 
  

  

  Activity 
  of 
  tlie 
  actinium 
  emanation. 
  

  

  Total 
  ionization 
  over 
  the 
  last 
  5*8 
  cms. 
  of 
  path 
  = 
  870 
  

  

  3-07 
  „ 
  „ 
  = 
  545 
  

  

  „ 
  ., 
  for 
  average 
  range 
  of 
  273 
  cms. 
  = 
  325 
  

  

  Activity 
  of 
  the 
  active 
  deposit. 
  

  

  Total 
  ionization 
  over 
  the 
  last 
  5*5 
  cms. 
  of 
  path 
  = 
  838 
  

  

  1-63 
  „ 
  „ 
  = 
  308 
  

  

  for 
  average 
  range 
  of 
  3*87 
  cms. 
  = 
  530 
  

  

  3-87 
  

   » 
  2 
  

  

  Ionization 
  due 
  to 
  active 
  deposit 
  265 
  

   Ionization 
  due 
  to 
  emanation 
  ~ 
  325 
  

  

  = 
  265 
  

   = 
  •81 
  

  

  Discussion 
  of 
  Results. 
  

  

  The 
  agreement 
  between 
  the 
  figures 
  in 
  columns 
  VI. 
  and 
  

   VIII. 
  is 
  surprising 
  considering 
  the 
  nature 
  of 
  the 
  assumptions 
  

   and 
  calculations. 
  These 
  results 
  could 
  be 
  explained 
  by 
  

   assuming 
  that 
  there 
  were 
  present 
  other 
  active 
  substances 
  of 
  

   very 
  short 
  transformation 
  periods. 
  It 
  would 
  require 
  three 
  

   such 
  products 
  in 
  the 
  case 
  of 
  thorium 
  and 
  one 
  in 
  the 
  case 
  of 
  

   actinium. 
  Hahn's 
  measurements 
  on 
  the 
  ionization 
  ranges 
  

   of 
  the 
  products 
  of 
  thorium 
  and 
  actinium 
  give 
  no 
  evidence 
  of 
  

   this, 
  and 
  it 
  seems 
  very 
  unlikely. 
  A 
  simpler 
  and 
  more 
  satis- 
  

   factory 
  explanation 
  would 
  seem 
  to 
  be 
  — 
  that 
  an 
  atom 
  of 
  

   thorium 
  0, 
  in 
  breaking 
  up, 
  gives 
  of 
  the 
  same 
  number 
  of 
  

   a 
  particles 
  as 
  an 
  atom 
  of 
  thorium 
  B 
  and 
  that 
  an 
  atom 
  of 
  

   thorium 
  emanation 
  gives 
  off 
  four 
  times 
  this 
  number 
  • 
  also 
  that 
  

   an 
  atom 
  of 
  actinium 
  emanation, 
  in 
  breaking 
  up, 
  gives 
  off 
  twice 
  

   as 
  many 
  a. 
  particles 
  as 
  an 
  atom 
  of 
  its 
  active 
  deposit. 
  

  

  These 
  results 
  raise 
  the 
  very 
  interesting 
  question 
  as 
  to 
  the 
  

   number 
  of 
  a 
  particles 
  given 
  off 
  when 
  an 
  atom 
  of 
  any 
  radio- 
  

   active 
  substance 
  breaks 
  up. 
  If 
  the 
  above 
  conclusions 
  are 
  

   correct, 
  it 
  has 
  been 
  shown 
  that 
  this 
  number 
  is 
  not 
  the 
  same 
  

   for 
  every 
  active 
  substance. 
  As 
  the 
  measurements 
  in 
  this 
  

  

  