﻿452 
  Browning 
  — 
  YoUcmetric 
  Estimation 
  of 
  Cerium. 
  

  

  of 
  ammonium 
  oxalate, 
  washing 
  and 
  igniting 
  as 
  described. 
  The 
  

   dioxide 
  in 
  all 
  three 
  cases 
  was 
  of 
  a 
  light 
  chamois 
  color, 
  and 
  

   uniform 
  results 
  were 
  obtained 
  from 
  the 
  three 
  portions. 
  

  

  A 
  modification 
  of 
  the 
  method 
  of 
  Bunsen 
  — 
  (with 
  G. 
  A. 
  Hanford 
  

   and 
  F. 
  J. 
  Hall). 
  

  

  Weighed 
  portions 
  of 
  the 
  pure 
  cerium 
  dioxide 
  were 
  placed 
  in 
  

   small 
  glass 
  stoppered 
  bottles 
  of 
  about 
  100*^"°' 
  capacity, 
  together 
  

   with 
  a 
  gram 
  of 
  potassium 
  iodide 
  free 
  from 
  iodate 
  and 
  a 
  few 
  

   drops 
  of 
  water 
  to 
  dissolve 
  the 
  iodide. 
  A 
  current 
  of 
  carbon 
  

   dioxide 
  was 
  passed 
  into 
  the 
  bottle 
  for 
  about 
  five 
  minutes 
  to 
  

   expel 
  the 
  air, 
  10^'''^ 
  of 
  pure 
  strong 
  hydrochloric 
  acid 
  were 
  added, 
  

   the 
  stopper 
  inserted 
  and 
  the 
  bottle 
  heated 
  gently 
  upon 
  a 
  steam 
  

   radiator 
  for 
  about 
  one 
  hour 
  until 
  the 
  dioxide 
  dissolved 
  com- 
  

   pletely 
  and 
  the 
  iodine 
  was 
  set 
  free. 
  After 
  cooling 
  the 
  bottle, 
  

   to 
  prevent 
  loss 
  of 
  iodine 
  upon 
  removing 
  the 
  stopper, 
  the 
  con- 
  

   tents 
  were 
  carefully 
  washed 
  into 
  about 
  400'^°'^ 
  of 
  water 
  and 
  

   titrated 
  with 
  standard 
  sodium 
  thiosulphate 
  to 
  determine 
  the 
  

   amount 
  of 
  iodine 
  liberated 
  according 
  to 
  the 
  well 
  known 
  reac- 
  

   tion 
  

  

  2CeO, 
  + 
  8HC1 
  + 
  2KI 
  = 
  2CeC]3 
  + 
  2KCI 
  + 
  4H,0 
  + 
  1,. 
  

  

  A 
  few 
  blank 
  determinations 
  were 
  carried 
  through 
  in 
  the 
  bottles 
  

   without 
  the 
  presence 
  of 
  the 
  cerium 
  dioxide 
  to 
  determine 
  the 
  

   amount 
  of 
  iodine 
  set 
  free 
  under 
  these 
  conditions. 
  The 
  amount 
  

   obtained 
  was 
  uniformly 
  equal 
  to 
  0*04^™' 
  of 
  the 
  y^ 
  IST 
  iodine 
  

   solution 
  which 
  was 
  taken 
  as 
  the 
  correction 
  and 
  applied 
  to 
  all 
  

   the 
  determinations. 
  The 
  results 
  follow 
  in 
  Table 
  I. 
  

  

  

  

  Table 
  I. 
  

  

  

  

  CeOo 
  taken. 
  

  

  CeOo 
  found. 
  

  

  Error. 
  

  

  

  grm. 
  

  

  grm. 
  

  

  grra. 
  

  

  (1) 
  

  

  0-1000 
  

  

  0-0994 
  

  

  0-0006 
  — 
  

  

  (2) 
  

  

  0-1032 
  

  

  0-1034 
  

  

  0-0002 
  + 
  

  

  (•5) 
  

  

  0-1016 
  

  

  0-1017 
  

  

  0-0001 
  + 
  

  

  4) 
  

  

  1054 
  

  

  0-1041 
  

  

  0-0013- 
  

  

  (5) 
  

  

  0-2010 
  

  

  0-2021 
  

  

  0-0011 
  + 
  

  

  (6) 
  

  

  0-1104 
  

  

  0-1109 
  

  

  0-0005 
  + 
  

  

  (7) 
  

  

  0-1914 
  

  

  0-1907 
  

  

  0-0007- 
  

  

  (8) 
  

  

  0-1604 
  

  

  0-1603 
  

  

  0-0001- 
  

  

  (9) 
  

  

  0-2146 
  

  

  0-2145 
  

  

  o-oooi 
  — 
  

  

  (10) 
  

  

  0-1108 
  

  

  0-1099 
  

  

  0-0009- 
  

  

  (11) 
  

  

  0-1346 
  

  

  0-1347 
  

  

  0-0001 
  + 
  

  

  (12) 
  

  

  0-1540 
  

  

  01534 
  

  

  0-0006 
  — 
  

  

  (13) 
  

  

  0-1976 
  

  

  0-1968 
  

  

  0-0008- 
  

  

  (14) 
  

  

  0-1230 
  

  

  0-1240 
  

  

  0-0010 
  + 
  

  

  (15) 
  

  

  01199 
  

  

  0-1201 
  

  

  0-0003 
  + 
  

  

  (16) 
  

  

  1524 
  

  

  0-1528 
  

  

  0-0004 
  + 
  

  

  (17) 
  

  

  0-1212 
  

  

  0-1211 
  

  

  0-0001 
  — 
  

  

  (18) 
  

  

  0-1528 
  

  

  0-1543 
  

  

  0-0015 
  + 
  

  

  