﻿Broioning 
  — 
  VohimetriG 
  Esthnation 
  of 
  Cerium. 
  451 
  

  

  Art. 
  LII. 
  — 
  On 
  the 
  Volumetric 
  Estimation 
  of 
  Cerium 
  ; 
  by 
  

   Philip 
  E. 
  Browning. 
  

  

  [Contributions 
  from 
  the 
  Kent 
  Chemical 
  Laboratory 
  of 
  Yale 
  University 
  — 
  XC] 
  

  

  Some 
  forty 
  years 
  ago 
  Bimsen* 
  showed 
  tliat 
  the 
  oxide 
  

   obtained 
  by 
  the 
  ignition 
  of 
  cerium 
  oxalate 
  might 
  be 
  estimated 
  

   vohimetrically 
  by 
  bringing 
  it 
  in 
  contact 
  with 
  potassium 
  iodide 
  

   and 
  strong 
  hydrochloric 
  acid 
  and 
  determining 
  the 
  iodine 
  set 
  

   free. 
  This 
  method 
  may 
  be 
  briefly 
  described 
  by 
  a 
  translation 
  

   of 
  part 
  of 
  the 
  original 
  article 
  : 
  '' 
  The 
  substance 
  to 
  be 
  deter- 
  

   mined 
  is 
  weighed 
  out 
  in 
  a 
  glass 
  flask 
  of 
  from 
  ten 
  to 
  fifteen 
  

   cubic 
  centimeters 
  capacity, 
  a 
  few 
  crystals 
  of 
  potassium 
  iodide 
  

   are 
  added, 
  and 
  the 
  neck 
  of 
  the 
  flask 
  is 
  drawn 
  out 
  by 
  the 
  aid 
  of 
  

   a 
  blowpipe 
  to 
  a 
  narrow 
  opening. 
  The 
  flask 
  is 
  filled 
  almost 
  to 
  

   the 
  narrowing 
  of 
  the 
  neck 
  with 
  hydrochloric 
  acid 
  which 
  is 
  free 
  

   from 
  chlorine 
  or 
  iron 
  chloride, 
  and 
  a 
  little 
  sodium 
  carbonate 
  is 
  

   added 
  in 
  order 
  to 
  displace 
  the 
  last 
  trace 
  of 
  air 
  by 
  carbon 
  

   dioxide. 
  The 
  flask 
  is 
  then 
  closed 
  by 
  sealing 
  off 
  the 
  neck 
  in 
  

   the 
  blowpipe 
  and 
  warmed 
  in 
  a 
  water 
  bath 
  until 
  the 
  cerium 
  

   compound 
  is 
  completely 
  dissolved, 
  and 
  the 
  quantity 
  of 
  iodine 
  

   set 
  free 
  is 
  determined 
  by 
  iodometric 
  analysis." 
  

  

  The 
  anhydrous 
  dioxide 
  prepared 
  by 
  the 
  ignition 
  of 
  the 
  

   oxalate 
  or 
  hydroxide 
  is 
  very 
  slowly 
  acted 
  on 
  by 
  acids, 
  espe- 
  

   cially 
  when 
  pure.f 
  For 
  this 
  reason 
  the 
  method 
  which 
  Bunsen 
  

   described 
  has 
  remained 
  the 
  only 
  one 
  adapted 
  to 
  the 
  satisfactory 
  

   volumetric 
  estimation 
  of 
  the 
  ignited 
  dioxide. 
  

  

  Two 
  portions 
  of 
  the 
  dioxide 
  were 
  prepared 
  by 
  treating 
  the 
  

   crude 
  cerium 
  chloride 
  in 
  concentrated 
  solution 
  with 
  gaseous 
  

   hydrochloric 
  acid:}; 
  to 
  saturation 
  to 
  remove 
  the 
  iron. 
  The 
  

   cerium 
  chloride 
  was 
  then 
  dissolved 
  in 
  water, 
  potassium 
  

   hydroxide 
  added 
  in 
  excess 
  and 
  chlorine 
  gas 
  passed 
  until 
  the 
  

   precipitate 
  became 
  distinctly 
  orange 
  in 
  color 
  and 
  the 
  solution 
  

   gave 
  a 
  strong 
  odor 
  of 
  chlorine. 
  § 
  This 
  operation 
  was 
  repeated 
  

   until 
  a 
  portion 
  of 
  the 
  precipitate 
  dissolved 
  in 
  acid 
  showed 
  no 
  

   didymium 
  absorption 
  bands 
  when 
  examined 
  before 
  the 
  spectro- 
  

   scope. 
  The 
  whole 
  precipitate 
  of 
  the 
  dioxide 
  was 
  then 
  dis- 
  

   solved 
  in 
  hydrochloric 
  acid 
  and 
  the 
  oxalate 
  precipitated 
  by 
  

   ammonium 
  oxalate 
  in 
  large 
  excess. 
  The 
  precipitated 
  oxalate 
  

   was 
  then 
  washed 
  thoroughly 
  with 
  hot 
  water 
  until 
  the 
  washings 
  

   gave 
  no 
  test 
  for 
  hydrochloric 
  or 
  oxalic 
  acids 
  and 
  ignited 
  to 
  the 
  

   dioxide. 
  Another 
  portion 
  of 
  the 
  dioxide 
  was 
  later 
  prepared 
  

   by 
  precipitating 
  a 
  solution 
  of 
  pure 
  cerium 
  chloride 
  by 
  means 
  

  

  * 
  Annalen 
  d. 
  Chem. 
  u. 
  Phar., 
  cv, 
  49. 
  

  

  \ 
  Rose: 
  Handbuch 
  der 
  Analytischen 
  Chcmie, 
  Band 
  i, 
  219. 
  

   X 
  Dennis 
  and 
  Magee 
  : 
  Zeitschr. 
  f. 
  Anorgan 
  Chem 
  , 
  iii, 
  260. 
  

   §Mosander: 
  Phil. 
  Mag., 
  xxviii, 
  241; 
  Dennis: 
  Zeit. 
  f. 
  Anorgan. 
  Chem., 
  vii, 
  

   252. 
  

  

  