﻿between 
  Uranium 
  and 
  Radium. 
  637 
  

  

  of 
  uranium 
  is 
  considered, 
  since 
  

   X 
  1 
  U 
  = 
  l'2xlO- 
  7 
  , 
  

   R 
  = 
  (1/n 
  !) 
  \ 
  2 
  X 
  3 
  . 
  . 
  . 
  \r 
  x 
  1*2 
  x 
  10" 
  7 
  . 
  

  

  It 
  is 
  interesting 
  to 
  note 
  that 
  the 
  experimental 
  results, 
  when 
  

   they 
  have 
  been 
  obtained, 
  will 
  enable 
  the 
  number 
  of 
  inter- 
  

   mediate 
  changes 
  to 
  be 
  at 
  once 
  determined, 
  this 
  number 
  being 
  

   the 
  power 
  of 
  the 
  time 
  to 
  which 
  the 
  initial 
  rate 
  of 
  production 
  

   is 
  proportional. 
  Of 
  the 
  intermediate 
  bodies, 
  the 
  products 
  of 
  

   their 
  periods 
  may 
  be 
  deduced, 
  and 
  the 
  geometrical 
  mean 
  

   period, 
  but 
  not 
  the 
  individual 
  periods. 
  

  

  For 
  the 
  case 
  of 
  two 
  intermediate 
  bodies, 
  ?z 
  = 
  3, 
  and 
  the 
  

   expression 
  becomes 
  

  

  R 
  = 
  i\ 
  2 
  V 
  :3 
  Xl-2xlO- 
  7 
  . 
  

   From 
  Experiment 
  L, 
  

  

  5 
  X 
  10- 
  11 
  > 
  £\ 
  2 
  \ 
  3 
  x 
  (U-y 
  x 
  1-2 
  x 
  10- 
  7 
  . 
  

   \ 
  2 
  \,<l-2xl0- 
  4 
  . 
  

   From 
  Experiment 
  II., 
  

  

  10- 
  11 
  >iX 
  2 
  X 
  3 
  x(|) 
  3 
  xl-2xl0- 
  7 
  7 
  

   \ 
  2 
  \ 
  3 
  <:l-lxl0- 
  4 
  . 
  

  

  On 
  the 
  assumption 
  of 
  the 
  existence 
  of 
  two 
  intermediate 
  

   bodies, 
  therefore, 
  both 
  experiments 
  indicate 
  that 
  the 
  products 
  

   of 
  the 
  two 
  periods 
  is 
  at 
  least 
  10,000 
  years, 
  so 
  that 
  if 
  the 
  two 
  

   periods 
  are 
  similar 
  each 
  is 
  above 
  100 
  years. 
  It 
  is 
  probable 
  

   that 
  several 
  intermediate 
  bodies 
  will 
  ultimately 
  be 
  found 
  to 
  

   intervene. 
  

  

  With 
  regard 
  to 
  Experiment 
  IV., 
  which 
  was 
  an 
  attempt 
  to 
  

   detect 
  a 
  production 
  of 
  actinium 
  from 
  uranium, 
  no 
  further 
  

   tests 
  have 
  yet 
  been 
  done. 
  In 
  Experiment 
  V., 
  the 
  wire 
  made 
  

   active 
  by 
  exposure 
  to 
  an 
  actinium 
  preparation 
  for 
  five 
  months 
  

   now 
  shows 
  no 
  detectable 
  activity, 
  and 
  no 
  detectable 
  amount 
  

   of 
  radium 
  emanation 
  was 
  obtained 
  from 
  it 
  on 
  heating 
  to 
  

   redness 
  in 
  a 
  recent 
  test, 
  though 
  2 
  x 
  10~ 
  12 
  gram 
  could 
  have 
  

   been 
  detected. 
  

  

  Summary 
  of 
  Results. 
  

  

  (I) 
  The 
  results 
  of 
  the 
  second 
  series 
  of 
  experiments 
  have 
  

   confirmed 
  the 
  original 
  experiment, 
  started 
  in 
  1903, 
  in 
  showing 
  

   the 
  existence 
  of 
  a 
  radium-producing 
  substance 
  in 
  minute 
  

   amount 
  in 
  commercial 
  uranyl 
  salts. 
  The 
  amount 
  is, 
  in 
  the 
  

  

  