﻿Experiments 
  with 
  Active 
  Deposit 
  of 
  Thorium. 
  

  

  355 
  

  

  assuming 
  that, 
  in 
  the 
  presence 
  of 
  stannous 
  chloride, 
  the 
  

   nickel 
  plates 
  remove 
  the 
  product 
  C 
  tt 
  leaving 
  B 
  and 
  C^ 
  in 
  

   solution. 
  The 
  initial 
  a-ray 
  activity 
  would 
  thus 
  be 
  due 
  to 
  C 
  2 
  , 
  

  

  Fie-. 
  1, 
  

  

  50 
  

  

  80 
  

   x 
  70 
  

   | 
  60 
  

  

  kj4G 
  

   o 
  

  

  ^30 
  

  

  *20 
  

  

  10 
  

  

  

  

  

  

  ^^ 
  

  

  

  

  

  -^ 
  

  

  ^ 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  1 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  cJ 
  

  

  r 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  f 
  r 
  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  _ 
  

  

  2 
  3 
  

  

  T/ME 
  HOURS. 
  

  

  which 
  is 
  really 
  part 
  of 
  C 
  p 
  and 
  has 
  only 
  been 
  given 
  the 
  hypo- 
  

   thetical 
  period 
  10 
  " 
  n 
  second 
  to 
  conform 
  to 
  Geiger 
  and 
  

   Nuttall's 
  law 
  connecting 
  the 
  range 
  of 
  an 
  a 
  particle 
  with 
  the 
  

   period 
  o£ 
  its 
  products." 
  The 
  increase 
  o£ 
  activity 
  would 
  on 
  

   this 
  idea 
  he 
  due 
  to 
  the 
  growth 
  of 
  C 
  a 
  and 
  D 
  in 
  both 
  cases. 
  

  

  In 
  the 
  experiments 
  cited 
  above, 
  however, 
  Marsden 
  and 
  

   Darwin 
  showed 
  that 
  if 
  thorium 
  C 
  consists 
  of 
  two 
  separate 
  

   products 
  their 
  periods 
  must 
  be 
  the 
  same 
  to 
  within 
  about 
  2 
  per 
  

   cent. 
  The 
  point 
  of 
  view 
  taken 
  was 
  that 
  for 
  thorium 
  C 
  there 
  

   is 
  a 
  chance 
  X 
  a 
  that 
  an 
  atom 
  should 
  disintegrate 
  in 
  any 
  second 
  

   and 
  give 
  an 
  a 
  particle 
  and 
  a 
  separate 
  chance 
  \ 
  p 
  that 
  the 
  same 
  

   atom 
  should 
  disintegrate 
  and 
  emit 
  a 
  fi 
  particle. 
  This 
  would 
  

   require 
  0*65 
  \=0'35 
  X^ 
  and 
  \ 
  + 
  \ 
  = 
  \; 
  where 
  \ 
  is 
  the 
  

   ordinary 
  transformation 
  constant 
  of 
  thorium 
  C 
  calculated 
  

   from 
  the 
  period 
  605 
  minutes. 
  If 
  C 
  a 
  and 
  C^, 
  or 
  products 
  

   corresponding 
  to 
  them, 
  actually 
  have 
  an 
  independent 
  

   existence 
  as 
  Miss 
  Meitner's 
  experiment 
  suggests, 
  then 
  it 
  

   becomes 
  of 
  importance 
  to 
  ascertain 
  the 
  exact 
  relation 
  between 
  

   their 
  periods. 
  

  

  This 
  was 
  investigated 
  as 
  follows. 
  A 
  dilute 
  hydrochloric 
  

   acid 
  solution 
  of 
  the 
  active 
  deposit 
  was 
  taken 
  and 
  a 
  

   nickel 
  plate 
  dipped 
  in 
  for 
  about 
  one 
  minute. 
  _ 
  In 
  these 
  

   circumstances 
  the 
  experiments 
  of 
  both 
  Miss 
  Meitner 
  and 
  

  

  