﻿634 
  Mr. 
  F. 
  Soddy 
  on 
  the 
  Relation 
  

  

  divided 
  into 
  two 
  halves 
  ; 
  the 
  one 
  was 
  purified 
  by 
  means 
  of 
  

   barium 
  sulphate, 
  and 
  the 
  other 
  is 
  still 
  in 
  its 
  initial 
  condition. 
  

   The 
  first 
  now 
  (May 
  1908) 
  contains 
  4-5xl0~ 
  12 
  gram 
  of 
  

   radium, 
  and 
  the 
  second 
  2*7 
  X 
  10 
  -11 
  . 
  Even 
  assuming 
  that 
  

   in 
  both 
  the 
  whole 
  o£ 
  the 
  radium 
  has 
  been 
  formed 
  within 
  the 
  

   last 
  five 
  years 
  the 
  amount 
  of 
  the 
  parent 
  of 
  radium 
  is 
  only 
  

   one-sixtieth 
  per 
  cent, 
  and 
  one-tenth 
  per 
  cent, 
  of 
  the 
  equi- 
  

   librium 
  quantity 
  in 
  the 
  two 
  cases. 
  

  

  The 
  growth 
  of 
  2*6 
  X 
  10 
  -11 
  gram 
  of 
  radium 
  in 
  about 
  a 
  year 
  

   from 
  the 
  residues, 
  probably, 
  of 
  about 
  1500 
  grains 
  of 
  com- 
  

   mercial 
  uranyl 
  nitrate, 
  indicates 
  the 
  presence 
  of 
  about 
  one- 
  

   thirtieth 
  per 
  cent, 
  of 
  the 
  equilibrium 
  quantity 
  of 
  the 
  parent. 
  

   Marckwald 
  and 
  Keetman 
  (Ber. 
  d. 
  D. 
  Chem. 
  Gesell. 
  1908, 
  li. 
  

   p. 
  43) 
  point 
  out 
  that, 
  since 
  the 
  radium-bearing 
  insoluble 
  

   residues 
  of 
  pitchblende 
  are 
  poor 
  in 
  the 
  parent 
  of 
  radium, 
  the 
  

   main 
  quantity 
  of 
  the 
  latter 
  must 
  go 
  into 
  solution 
  with 
  the 
  

   uranium. 
  These 
  results 
  show 
  that 
  it 
  is 
  almost 
  all 
  separated 
  

   before 
  the 
  uranium 
  comes 
  into 
  the 
  market. 
  It 
  is 
  not 
  difficult 
  

   to 
  see 
  therefore 
  that 
  it 
  must 
  be 
  almost 
  wholly 
  contained 
  in 
  

   the 
  mother-liquors 
  from 
  the 
  crystallization 
  of 
  the 
  uranium 
  

   salts, 
  which 
  are 
  probably 
  wasted. 
  The 
  curious 
  preferential 
  

   restrictions 
  woven 
  around 
  the 
  supply 
  of 
  radioactive 
  material 
  

   to 
  scientific 
  workers, 
  which 
  have 
  resulted 
  in 
  many 
  of 
  the 
  

   original 
  investigators 
  being 
  deprived 
  of 
  material 
  for 
  their 
  

   researches 
  (see 
  Zeit. 
  Elektrochemie, 
  1907, 
  xiii. 
  p. 
  369) 
  close 
  

   this 
  avenue 
  of 
  search 
  except 
  to 
  the 
  privileged. 
  

  

  Experiment 
  I. 
  — 
  The 
  solution, 
  containing 
  about 
  255 
  grams 
  

   of 
  uranium, 
  initially 
  contained 
  1*9 
  x 
  10 
  — 
  u 
  gram 
  of 
  radium. 
  

   The 
  last 
  published 
  test 
  (July 
  3rd, 
  1907), 
  617 
  days 
  from 
  the 
  

   start, 
  showed 
  2*7 
  x 
  10 
  _11 
  gram. 
  The 
  last 
  test, 
  performed 
  on 
  

   Aug. 
  7th, 
  1908, 
  1018 
  days 
  from 
  the 
  start, 
  showed 
  2'9 
  x 
  10" 
  11 
  

   gram. 
  This 
  increase, 
  which, 
  though 
  slight, 
  appears 
  to 
  be 
  

   real, 
  is 
  in 
  all 
  probability 
  due 
  to 
  a 
  small 
  fraction 
  of 
  the 
  parent 
  

   of 
  radium, 
  present 
  in 
  commercial 
  uranium 
  salts, 
  escaping 
  

   removal 
  during 
  the 
  purification 
  with 
  ether, 
  and 
  being 
  still 
  

   present 
  with 
  the 
  uranium. 
  In 
  any 
  case, 
  the 
  experiment 
  

   proves 
  that 
  the 
  amount 
  of 
  radium 
  formed 
  per 
  kilogram 
  of 
  

   uranium 
  is 
  less 
  than 
  5 
  x 
  10~ 
  n 
  gram 
  in 
  the 
  first 
  1018 
  days, 
  

   or 
  2J- 
  years. 
  

  

  Experiment 
  II. 
  — 
  408 
  * 
  grams 
  of 
  uranium 
  in 
  the 
  initial 
  test 
  

   showed 
  1*3 
  X 
  10 
  —n 
  gram 
  of 
  radium. 
  In 
  the 
  last 
  published 
  

   test 
  (July 
  9th, 
  1907), 
  208 
  days 
  from 
  the 
  start, 
  the 
  result 
  

  

  * 
  A 
  recent 
  analysis 
  has 
  shown 
  that 
  the 
  solution 
  contains 
  408 
  grams 
  

   of 
  uranium 
  instead 
  of 
  480 
  as 
  previously 
  stated. 
  The 
  analysis 
  of 
  the 
  

   solution 
  of 
  Experiment 
  I. 
  showed 
  the 
  presence 
  of 
  255 
  grams 
  of 
  uranium,, 
  

   confirming- 
  the 
  previous 
  estimate 
  of 
  about 
  250 
  grams. 
  

  

  