﻿G26 
  Messrs. 
  .F. 
  Soddj 
  and 
  A. 
  S. 
  Russell 
  on 
  the 
  

  

  less 
  extent, 
  and 
  this 
  observation 
  suggests 
  a 
  simpler 
  method 
  

   of 
  removing 
  it 
  from 
  uranium 
  X 
  than 
  has 
  yet 
  been 
  

   tried. 
  

  

  For 
  other 
  experiments 
  it 
  was 
  necessary 
  to 
  obtain 
  the 
  

   uranium 
  X 
  as 
  the 
  least 
  possible 
  quantity 
  of 
  material 
  in 
  the 
  

   form 
  of 
  thin 
  films 
  which 
  could 
  be 
  exam.ined 
  in 
  an 
  intense 
  

   magnetic 
  field. 
  In 
  the 
  first 
  and 
  second 
  separations 
  this 
  was 
  

   effected 
  by 
  a 
  long 
  series 
  of 
  chemical 
  operations, 
  in 
  which 
  the 
  

   uranium 
  X 
  was 
  removed 
  from 
  the 
  solution 
  of 
  the 
  precipitates 
  

   in 
  acid 
  by 
  successive 
  additions 
  of 
  barium 
  nitrate 
  and 
  sul- 
  

   phuric 
  acid 
  according 
  to 
  the 
  method 
  employed 
  by 
  Becquerel. 
  

   The 
  barium 
  sulphate 
  was 
  then 
  fused 
  with 
  alkali 
  carbonates, 
  

   and 
  the 
  well-washed 
  barium 
  carbonate, 
  which 
  contained 
  the 
  

   whole 
  of 
  the 
  uranium 
  X, 
  was 
  dissolved 
  in 
  acid. 
  A 
  little 
  iron 
  

   chloride 
  was 
  added 
  and 
  precipitated 
  with 
  ammonium, 
  carbo- 
  

   nate, 
  the 
  precipitate 
  containing 
  the 
  uranium 
  X. 
  In 
  the 
  

   second 
  separation 
  the 
  filter 
  -papers 
  and 
  precipitates 
  were 
  

   ignited, 
  brought 
  on 
  to 
  three 
  strips 
  of 
  micro-cover-glass 
  each 
  

   75 
  mm. 
  long, 
  13 
  mm. 
  wide, 
  and 
  0*12 
  mm. 
  thick. 
  These 
  

   were 
  placed 
  on 
  a 
  hot 
  plate, 
  a 
  drop 
  of 
  hydrochloric 
  acid 
  added, 
  

   and 
  the 
  solution 
  made 
  to 
  cover 
  the 
  whole 
  surface. 
  The 
  films 
  

   w^ere 
  dried 
  and 
  heated 
  till 
  chlorine 
  was 
  given 
  off, 
  and 
  were 
  

   so 
  obtained 
  in 
  a 
  stable 
  and 
  tolerably 
  coherent 
  form. 
  The 
  

   weights 
  of 
  the 
  films 
  were 
  57, 
  211, 
  and 
  11 
  mg. 
  respectively, 
  

   and 
  their 
  relative 
  activity 
  as 
  2 
  : 
  1 
  : 
  0*12. 
  In 
  this 
  work 
  they 
  

   were 
  kept 
  in 
  platinum 
  trays 
  placed 
  side 
  by 
  side 
  on 
  a 
  wood 
  

   block. 
  In 
  the 
  third 
  separation 
  the 
  concentration 
  was 
  not 
  

   pushed 
  further 
  after 
  removing 
  the 
  uranium 
  by 
  ammonium 
  

   carbonate. 
  The 
  burnt 
  filter-papers 
  were 
  placed 
  directly 
  in 
  

   the 
  three 
  platinum 
  trays 
  and 
  treated 
  with 
  nitric 
  acid 
  (in 
  one 
  

   case 
  hydrofluoric 
  acid 
  also 
  to 
  remove 
  silica), 
  the 
  films 
  formed 
  

   being 
  finally 
  ignited 
  at 
  a 
  red 
  heat. 
  They 
  weighed 
  285, 
  200, 
  

   and 
  152 
  milligrams 
  respectively, 
  w^ith 
  relative 
  activities 
  as 
  

   1:1: 
  0*4. 
  The 
  time 
  absorbed 
  in 
  the 
  second 
  separation 
  from 
  

   the 
  start 
  to 
  the 
  preparation 
  of 
  the 
  products 
  in 
  the 
  final 
  form 
  

   was 
  twelve 
  days. 
  In 
  the 
  third 
  separation 
  the 
  first 
  film 
  was 
  

   produced 
  in 
  3*3 
  days, 
  the 
  second 
  in 
  7 
  days, 
  and 
  the 
  last 
  in 
  

   9 
  days 
  from 
  the 
  start. 
  To 
  settle 
  certain 
  points 
  it 
  was 
  desirable 
  

   to 
  reduce 
  the 
  loss 
  of 
  material 
  and 
  time 
  of 
  preparation, 
  rather 
  

   than 
  the 
  weight 
  of 
  the 
  product, 
  to 
  a 
  minimum, 
  and 
  this 
  was 
  

   done 
  by 
  omitting 
  the 
  long 
  process 
  of 
  further 
  concentration 
  

   adopted 
  in 
  the 
  first 
  and 
  second 
  separations. 
  The 
  increasing 
  

   purity 
  of 
  the 
  uranium 
  made 
  this 
  possible. 
  An 
  indefinite 
  loss 
  

   of 
  active 
  material 
  occurs 
  in 
  the 
  numerous 
  operations 
  required 
  

   to 
  remove 
  the 
  unidentified 
  yellow 
  body, 
  whereas 
  it 
  was 
  re- 
  

   quired 
  to 
  deduce 
  for 
  one 
  series 
  the 
  exact 
  percentage 
  of 
  the 
  

  

  