﻿456 
  Browning 
  — 
  Yolumeiric 
  Estimation 
  of 
  Cerium. 
  

  

  The 
  dark 
  brown 
  powder 
  obtained 
  by 
  igniting 
  the 
  carefully 
  

   washed 
  oxalates, 
  precipitated 
  in 
  acid 
  solution 
  by 
  treating 
  a 
  

   solution 
  of 
  crude 
  cerium 
  chloride 
  with 
  ammonium 
  oxalate 
  or 
  

   oxalate 
  acid, 
  is 
  very 
  fairly 
  soluble 
  in 
  acids. 
  Mengel" 
  has 
  

   recently 
  shown 
  that 
  this 
  product 
  contains 
  a 
  dioxide 
  of 
  praseo- 
  

   didymium 
  which 
  acts 
  as 
  does 
  cerium 
  dioxide 
  toward 
  reducing 
  

   agents. 
  This 
  fact 
  makes 
  the 
  results 
  recorded 
  in 
  the 
  treatment 
  

   of 
  this 
  ignited 
  mixture 
  of 
  oxides 
  of 
  no 
  value 
  analytically, 
  but 
  

   of 
  interest 
  in 
  the 
  comparative 
  study 
  of 
  the 
  two 
  reducing 
  agents, 
  

   arsenious 
  oxide 
  and 
  hydriodic 
  acid 
  Two 
  portions 
  of 
  this 
  mix- 
  

   ture 
  of 
  oxides 
  gave 
  the 
  following 
  results, 
  which 
  agree 
  fairly 
  

   well 
  with 
  those 
  of 
  Men 
  gel. 
  

  

  Amt. 
  of 
  substance 
  taken. 
  Ce02 
  + 
  (Pd02?) 
  found. 
  Calculated 
  on 
  -1000 
  grm. 
  

   grm. 
  grm. 
  grm. 
  

  

  (1) 
  0-1037 
  0-0530 
  0-0511 
  

  

  (2) 
  0-1034 
  0-0538 
  0-0520 
  

  

  The 
  average 
  of 
  these 
  results 
  was 
  taken 
  as 
  a 
  standard 
  

   — 
  0-0515 
  grm. 
  CeOj, 
  etc., 
  to 
  every 
  0-1000 
  grm. 
  of 
  material. 
  

   Three 
  carefully 
  weighed 
  portions 
  of 
  this 
  same 
  material 
  were 
  

   placed 
  in 
  Erlenmeyer 
  beakers 
  with 
  lO^'''^ 
  of 
  Jg- 
  N 
  arsenious 
  

   oxide 
  solution 
  and 
  10^™^ 
  of 
  dilute 
  (1—4) 
  sulphuric 
  acid 
  and 
  

   boiled 
  until 
  complete 
  solution 
  had 
  taken 
  place. 
  The 
  liquid 
  

   was 
  then 
  cooled, 
  neutralized 
  with 
  potassium 
  bicarbonate 
  and 
  

   titrated 
  with 
  standardizing 
  iodine 
  to 
  determine 
  the 
  amount 
  of 
  

   arsenious 
  oxide 
  remaining, 
  and 
  from 
  it 
  the 
  amount 
  used 
  in 
  the 
  

   reduction 
  of 
  the 
  dioxide 
  according 
  to 
  the 
  reaction 
  given 
  ab(»ve. 
  

   The 
  results 
  obtained 
  follow. 
  

  

  

  

  Amt. 
  CeOa 
  

  

  CeOs 
  calculated 
  

  

  

  Amt. 
  taken. 
  

  

  found. 
  

  

  for 
  0-1000 
  grm. 
  

  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  (1) 
  

  

  0-1005 
  

  

  0-0493 
  

  

  00491 
  

  

  (2) 
  

  

  0-1015 
  

  

  0-0494 
  

  

  0-0487 
  

  

  (3) 
  

  

  0-1005 
  

  

  0-0486 
  

  

  0-0484 
  

  

  As 
  w^ill 
  be 
  seen, 
  the 
  results 
  obtained 
  by 
  this 
  method 
  fall 
  

   about 
  0*0030 
  grm. 
  below 
  the 
  standard 
  as 
  obtained 
  by 
  the 
  dis- 
  

   tillation 
  method, 
  which 
  seems 
  to 
  show 
  that 
  the 
  arsenious 
  oxide 
  

   does 
  not 
  effect 
  the 
  complete 
  reduction 
  of 
  the 
  cerium 
  dioxide 
  

   from 
  CeO, 
  to 
  Ce,03. 
  

  

  In 
  order 
  to 
  study 
  this 
  point 
  a 
  little 
  more 
  fully 
  and 
  upon 
  the 
  

   pure 
  dioxide, 
  definite 
  portions 
  of 
  a 
  standard 
  solution 
  of 
  pure 
  

   cerium 
  chloride 
  were 
  precipitated 
  by 
  ammonia 
  in 
  the 
  presence 
  

   of 
  hydrogen 
  dioxide 
  and 
  boiled 
  to 
  reduce 
  the 
  CeOg 
  formed 
  to 
  

   the 
  conditions 
  of 
  CeO^. 
  The 
  precipitated 
  hydrated 
  dioxide 
  was 
  

   filtered 
  off 
  and 
  carefully 
  washed 
  until 
  the 
  washings 
  gave 
  no 
  

  

  * 
  Zeitscbr. 
  fur 
  Ano^gau. 
  Cbem., 
  xix, 
  G7. 
  

  

  