﻿y-Baj/s 
  of 
  Uranium 
  and 
  Radium. 
  627 
  

  

  equilibrium 
  amount 
  of 
  uranium 
  X 
  contained 
  in 
  the 
  prepara- 
  

   tions 
  on 
  the 
  date 
  of 
  their 
  comparison 
  with 
  radium. 
  

  

  Between 
  the 
  second 
  and 
  the 
  third 
  separations 
  just 
  described 
  

   appeared 
  the 
  interesting 
  paper 
  by 
  J. 
  Danne, 
  in 
  Le 
  Radium, 
  

   1909, 
  vi. 
  p. 
  ^1:2, 
  on 
  a 
  new 
  product 
  in 
  the 
  uranium 
  series, 
  

   ^^ 
  hich 
  he 
  calls 
  radio-uranium, 
  intermediate 
  between 
  uranium 
  

   and 
  uranium 
  X, 
  and 
  acting 
  as 
  the 
  direct 
  parent 
  of 
  the 
  latter. 
  

   Mr. 
  J. 
  T. 
  Smith 
  kindly 
  undertook 
  for 
  us 
  at 
  this 
  stage 
  a 
  

   careful 
  series 
  of 
  measurements 
  over 
  a 
  considerable 
  period 
  of 
  

   the 
  /3-activities 
  of 
  various 
  products 
  separated 
  in 
  the 
  course 
  

   of 
  this 
  work, 
  and 
  of 
  the 
  whole 
  of 
  the 
  fractions 
  of 
  uranyl 
  

   nitrate 
  resulting 
  from 
  the 
  second 
  separation, 
  with 
  the 
  object 
  

   of 
  ascertaining 
  whether 
  in 
  any 
  of 
  them 
  any 
  concentration 
  or 
  

   impoverishment 
  of 
  the 
  parent 
  of 
  uranium 
  X 
  had 
  occurred. 
  

   The 
  results 
  show, 
  up 
  to 
  the 
  present 
  time, 
  that 
  the 
  whole 
  of 
  

   the 
  preparations 
  lost 
  or 
  regained 
  their 
  yS-activity 
  perfectly 
  

   normally, 
  and 
  no 
  alteration 
  in 
  the 
  normal 
  amount 
  of 
  the 
  

   parent 
  of 
  uranium 
  X 
  had 
  been 
  effected. 
  We 
  may 
  thus 
  con- 
  

   clude 
  that 
  none 
  of 
  the 
  varied 
  chemical 
  operations 
  used 
  in 
  

   the 
  work 
  have 
  affected 
  the 
  power 
  of 
  uranium 
  to 
  produce 
  

   uranium 
  X. 
  

  

  3. 
  Relative 
  Intensity 
  of 
  the 
  y-Rays 
  of 
  Uranium 
  and 
  Radium. 
  

  

  The 
  bare 
  uranium 
  X 
  films, 
  the 
  preparation 
  of 
  which 
  has 
  

   just 
  been 
  described, 
  lit 
  up 
  an 
  X-ray 
  screen 
  brightly 
  in 
  the 
  

   dark-room, 
  and 
  indeed 
  the 
  glow 
  could 
  still 
  be 
  seen 
  in 
  a 
  fully 
  

   lighted 
  room 
  when 
  the 
  screen 
  was 
  held 
  in 
  the 
  shadow 
  of 
  the 
  

   observer. 
  The 
  three 
  bare 
  films 
  from 
  the 
  second 
  separation 
  

   together 
  produced 
  about 
  the 
  same 
  effect 
  when 
  held 
  under 
  

   the 
  screen 
  as 
  6*7 
  mg. 
  of 
  radium 
  bromide 
  in 
  a 
  sealed 
  thin 
  

   glass 
  tube, 
  though 
  on 
  account 
  of 
  the 
  difference 
  in 
  the 
  area 
  

   of 
  the 
  glow, 
  and 
  the 
  absorption 
  that 
  occurred 
  in 
  the 
  glass 
  of 
  

   the 
  tube 
  in 
  the 
  case 
  of 
  radium, 
  this 
  is 
  merely 
  a 
  very 
  rough 
  

   comparison. 
  But 
  the 
  7-rays 
  from 
  these 
  films 
  were 
  accurately 
  

   compared 
  with 
  the 
  7-rays 
  from 
  0'4:7 
  mg. 
  of 
  radium 
  bromide, 
  

   eight 
  days 
  after 
  the 
  last 
  crystallization 
  of 
  the 
  uranyl 
  nitrate 
  

   was 
  started. 
  The 
  substances 
  were 
  placed 
  7*5 
  cm. 
  beneath 
  

   the 
  base 
  of 
  a 
  brass 
  electroscope, 
  to 
  which 
  a 
  thickness 
  of 
  

   2*5 
  cms. 
  of 
  lead 
  was 
  clamped 
  up 
  to 
  form 
  a 
  base. 
  The 
  7- 
  

   activity 
  of 
  the 
  uranium 
  X 
  was 
  only 
  equal 
  to 
  that 
  of 
  0*056 
  mg. 
  

   of 
  radium 
  bromide. 
  Owing 
  to 
  the 
  loss 
  of 
  active 
  material 
  

   during 
  the 
  numerous 
  processes 
  of 
  concentration 
  it 
  was 
  not 
  

   ])Ossible 
  to 
  deduce 
  accurately 
  the 
  amount 
  of 
  uranium 
  X 
  in 
  

   the 
  preparations 
  at 
  the 
  time 
  of 
  experiment, 
  but 
  the 
  experi- 
  

   ment 
  clearly 
  showed 
  the 
  great 
  relative 
  poverty 
  of 
  uranium 
  

   in 
  7-rays 
  as 
  compared 
  with 
  /5-rays. 
  

  

  