﻿454 
  Browning 
  — 
  Volumetric 
  Estimation 
  of 
  Cerium. 
  

  

  In 
  these 
  experiments 
  the 
  contents 
  of 
  the 
  bottles 
  after 
  the 
  

   cerium 
  had 
  dissolved 
  were 
  carefully 
  washed 
  into 
  a 
  Drexel 
  

   wash 
  bottle 
  upon 
  the 
  inlet 
  tube 
  of 
  which 
  was 
  fnsed 
  a 
  thistle 
  

   tube 
  with 
  a 
  stop-cock 
  and 
  to 
  the 
  outlet 
  tube 
  a 
  Will 
  and 
  Yar- 
  

   rentrapp 
  absorption 
  trap. 
  In 
  the 
  trap 
  a 
  solution 
  of 
  potassium 
  

   iodide 
  was 
  placed 
  and 
  through 
  the 
  thistle 
  tube 
  a 
  saturated 
  

   solution 
  of 
  potassium 
  bicarbonate 
  was 
  added 
  to 
  complete 
  neu- 
  

   tralization 
  of 
  the 
  acid. 
  Any 
  iodine 
  carried 
  mechanically 
  by 
  

   the 
  carbon 
  dioxide 
  should 
  be 
  held 
  by 
  the 
  potassium 
  iodide 
  

   solution 
  in 
  the 
  trap. 
  After 
  neutralization 
  the 
  free 
  iodine 
  wa& 
  

   titrated 
  by 
  standard 
  arsenious 
  oxide 
  solution. 
  The 
  results 
  

   appear 
  in 
  Table 
  III. 
  

  

  Error, 
  

   grm. 
  

  

  0-0013— 
  \ 
  

  

  0-0024— 
  ! 
  J 
  

  

  0-0021- 
  [ 
  

  

  0-0025— 
  J 
  

  

  0-0025- 
  \ 
  

  

  

  

  Table 
  III. 
  

  

  

  CeOa 
  taken. 
  

  

  Ce02 
  found 
  

  

  

  grm. 
  

  

  grm. 
  

  

  (1) 
  

  

  o-iooo 
  

  

  0-0987 
  

  

  (2) 
  

  

  0-1005 
  

  

  0-0981 
  

  

  (3) 
  

  

  0-1030 
  

  

  0-1009 
  

  

  (4) 
  

  

  0-1500 
  

  

  0-1475 
  

  

  (5) 
  

  

  0-1030 
  

  

  0-1005 
  

  

  (6) 
  

  

  0-1010 
  

  

  0-0988 
  

  

  (V) 
  

  

  0-1510 
  

  

  0-1508 
  

  

  (8) 
  

  

  0-1530 
  

  

  0-1485 
  

  

  (9) 
  

  

  0-2045 
  

  

  0-2011 
  

  

  (10) 
  

  

  0-2000 
  

  

  0-1958 
  

  

  (") 
  

  

  0-1334 
  

  

  0-1302 
  

  

  (12) 
  

  

  0-1354 
  

  

  0-1330 
  

  

  (13) 
  

  

  0-1312 
  

  

  0-1294 
  

  

  (14) 
  

  

  0-1308 
  

  

  0-1277 
  

  

  (15) 
  

  

  0-1060 
  

  

  0-1042 
  

  

  (16) 
  

  

  0-1602 
  

  

  0-1567 
  

  

  (17) 
  

  

  01504 
  

  

  0-1488 
  

  

  0-0022 
  — 
  

   0-0002 
  — 
  

   0-0045 
  — 
  

   0-0034- 
  

   0042- 
  

   0-0032 
  — 
  

   00024 
  — 
  

   0-0018— 
  

   0-0031- 
  

   0-0018 
  — 
  

   0-0035 
  — 
  

   0-0016 
  — 
  

  

  II 
  

  

  J 
  

  

  V 
  

   I 
  

  

  I 
  

   ^iii 
  

  

  I 
  

   I 
  

   J 
  

  

  As 
  will 
  be 
  seen 
  by 
  the 
  table, 
  an 
  average 
  error 
  of 
  about 
  2 
  per 
  

   cent 
  runs 
  through 
  the 
  entire 
  set. 
  The 
  natural 
  conclusion 
  

   would 
  be 
  that 
  the 
  cerium 
  dioxide 
  contained 
  some 
  impurity 
  ; 
  

   but, 
  as 
  the 
  first, 
  second 
  and 
  third 
  samples, 
  very 
  carefully 
  pre- 
  

   pared, 
  gave 
  the 
  same 
  results, 
  it 
  seemed 
  necessary 
  to 
  look 
  else- 
  

   where 
  for 
  an 
  explanation. 
  Two 
  possible 
  causes 
  suggested 
  

   themselves: 
  first, 
  mechanical 
  loss 
  during 
  the 
  process 
  of 
  neu- 
  

   tralization, 
  and 
  second, 
  the 
  possible 
  formation, 
  under 
  the 
  condi- 
  

   tions, 
  of 
  iodine 
  chloride, 
  which 
  if 
  formed 
  would 
  in 
  the 
  process 
  

   of 
  neutralization 
  probably 
  take 
  the 
  form 
  of 
  potassium 
  chloride, 
  

   iodide, 
  and 
  iodate, 
  and 
  thus 
  some 
  of 
  the 
  originally 
  free 
  iodine 
  

   would 
  be 
  withdrawn 
  from 
  the 
  amount 
  titrated. 
  To 
  test 
  these 
  

   theories, 
  portions 
  of 
  the 
  J^ 
  N 
  iodine 
  solution 
  roughly 
  equiva- 
  

   lent 
  to 
  the 
  amounts 
  of 
  iodine 
  set 
  free 
  by 
  0-1 
  and 
  0-2 
  grms. 
  of 
  

  

  