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   XCVIII. 
  Intelligence 
  and 
  Miscellaneous 
  Articles, 
  

  

  ON 
  THE 
  EXISTENCE 
  OF 
  URANIUM 
  Y. 
  

   To 
  the 
  Editors 
  of 
  the 
  Philosophical 
  Magazine. 
  

  

  Gentlemen, 
  — 
  

   'TWO 
  .years 
  ago 
  I 
  gave 
  an 
  account 
  in 
  this 
  Journal 
  (Phil. 
  Mag. 
  xxii. 
  

   -*- 
  p. 
  419, 
  1911) 
  of 
  experiments 
  which 
  indicated 
  the 
  presence 
  of 
  

   a 
  new 
  product 
  in 
  uranium 
  of 
  half 
  period 
  of 
  transformation 
  1'5 
  

   days, 
  which 
  1 
  called 
  uranium 
  Y. 
  Evidence 
  was 
  given 
  that 
  this 
  

   new 
  radioactive 
  substance 
  must 
  be 
  regarded 
  as 
  a 
  branch 
  product 
  

   of 
  the 
  main 
  uranium 
  series. 
  In 
  the 
  May 
  number 
  of 
  this 
  Journal 
  

   Mr. 
  A. 
  Meek 
  described 
  some 
  experiments 
  in 
  which 
  he 
  was 
  unable 
  

   to 
  separate 
  this 
  new 
  product, 
  and 
  concluded 
  that 
  the 
  results 
  

   obtained 
  by 
  me 
  were 
  possibly 
  to 
  be 
  ascribed 
  not 
  to 
  a 
  new 
  product 
  

   but 
  to 
  the 
  presence 
  of 
  thorium 
  in 
  my 
  uranium 
  preparations. 
  In 
  my 
  

   reply 
  (Phil. 
  Mag. 
  Aug. 
  1913) 
  I 
  gave 
  reasons 
  for 
  doubting 
  the 
  cor- 
  

   rectness 
  of 
  Mr. 
  Fleck's 
  conclusions, 
  and 
  expressed 
  the 
  view 
  that 
  

   it 
  w 
  T 
  as 
  impossible 
  to 
  explain 
  my 
  results 
  by 
  the 
  presence 
  of 
  thorium 
  

   products, 
  as 
  the 
  radionctive 
  constants 
  of 
  uranium 
  T 
  Avere 
  quite 
  

   different 
  from 
  those 
  to 
  be 
  expected 
  for 
  the 
  products 
  of 
  thorium. 
  

  

  In 
  his 
  experiments 
  Mr. 
  Fleck 
  employed 
  a 
  highly 
  purified 
  

   uranium 
  salt 
  which 
  had 
  been 
  prepared 
  some 
  years 
  before 
  by 
  Mr. 
  

   F. 
  Soddy, 
  F.E.S. 
  It 
  seems 
  possible 
  that 
  the 
  inability 
  of 
  Mr. 
  Fleck 
  

   to 
  find 
  evidence 
  of 
  uranium 
  T 
  might 
  be 
  due 
  to 
  the 
  removal 
  of 
  its 
  

   parent 
  substance 
  in 
  the 
  methods 
  of 
  purification. 
  In 
  order 
  to 
  throw 
  

   light 
  on 
  this 
  point, 
  Mr. 
  Soddy 
  kindly 
  loaned 
  to 
  me 
  about 
  60 
  

   grammes 
  of 
  his 
  pure 
  uranium 
  nitrate. 
  I 
  repeated 
  my 
  original 
  

   experiments 
  with 
  this 
  material, 
  and 
  was 
  at 
  once 
  able 
  to 
  separate 
  

   uranium 
  T 
  from 
  it. 
  

  

  Since' 
  Mr. 
  Fleck 
  was 
  unable 
  to 
  repeat 
  my 
  work, 
  I 
  am 
  intending 
  

   to 
  publish 
  shortly 
  a 
  paper 
  giving 
  a 
  more 
  detailed 
  account 
  of 
  my 
  

   experimental, 
  methods. 
  I 
  trust 
  that 
  other 
  investigators 
  will 
  then 
  

   find 
  no 
  difficulty 
  in 
  repeating 
  my 
  original 
  experiments. 
  

  

  I 
  am 
  at 
  present 
  making 
  further 
  investigations 
  to 
  determine 
  more 
  

   accurately 
  the 
  ratios 
  of 
  the 
  activities 
  of 
  uranium 
  X 
  and 
  uranium 
  

   Y, 
  comparing 
  the 
  penetrating 
  rays 
  of 
  uranium 
  X 
  with 
  the 
  most 
  

   penetrating 
  rays 
  from 
  uranium 
  Y. 
  I 
  have 
  found 
  that 
  the 
  activity 
  

   of 
  the 
  latter 
  must 
  be 
  more 
  than 
  2 
  per 
  cent, 
  of 
  the 
  former. 
  This 
  

   ratio 
  is 
  of 
  the 
  order 
  of 
  magnitude 
  to 
  be 
  expected 
  if 
  the 
  actinium 
  

   series 
  branched 
  off 
  at 
  this 
  point. 
  Gr. 
  N. 
  Antonoef. 
  

  

  Chemical 
  Laboratory 
  of 
  the 
  Academy 
  of 
  Sciences, 
  

   St. 
  Petersburg. 
  

  

  