﻿Browning 
  — 
  Volumetric 
  Edimation 
  of 
  Cerium. 
  

  

  453 
  

  

  In 
  order 
  to 
  obtain 
  a 
  further 
  check 
  upon 
  the 
  accuracy 
  of 
  the 
  

   method, 
  portions 
  of 
  the 
  cerium 
  dioxide 
  were 
  weiglied 
  out 
  and 
  

   placed 
  in 
  a 
  distillation 
  apparatus 
  previously 
  employed 
  for 
  

   similar 
  purposes 
  and 
  described 
  in 
  former 
  articles 
  from 
  this 
  

   laboratory, 
  viz 
  : 
  a 
  Yoit 
  flask, 
  serving 
  as 
  a 
  retort, 
  sealed 
  to 
  the 
  

   inlet 
  tube 
  of 
  a 
  Drexel 
  wash-bottle, 
  used 
  as 
  a 
  receiver, 
  the 
  out- 
  

   let 
  tube 
  of 
  which 
  was 
  trapped 
  by 
  sealing 
  on 
  Will 
  and 
  Yarren- 
  

   trapp 
  absorption 
  bulbs. 
  In 
  the 
  retort 
  the 
  cerium 
  dioxide 
  

   together 
  with 
  15'^°''' 
  of 
  water, 
  1 
  gram 
  of 
  potassium 
  iodide 
  and 
  

   2Qcm3 
  ^£ 
  p^j,Q 
  strong 
  hydrochloric 
  acid 
  were 
  placed. 
  In 
  the 
  

   receiver 
  were 
  100'=°'^ 
  of 
  water 
  and 
  2 
  to 
  3 
  grams 
  of 
  potassium 
  

   iodide, 
  and 
  in 
  the 
  bulbs 
  a 
  dilute 
  solution 
  of 
  potassium 
  iodide. 
  

   Before 
  adding 
  the 
  hydrochloric 
  acid 
  a 
  current 
  of 
  carbon 
  

   dioxide 
  was 
  passed 
  through 
  the 
  apparatus 
  for 
  some 
  minutes. 
  

   After 
  adding 
  the 
  acid, 
  the 
  liquid 
  was 
  boiled 
  in 
  the 
  current 
  of 
  

   carbon 
  dioxide"^ 
  to 
  a 
  volume 
  of 
  15°'"'', 
  when 
  the 
  free 
  iodine 
  had 
  

   almost 
  completely 
  left 
  the 
  retort 
  and 
  passed 
  into 
  the 
  receiver, 
  

   and 
  the 
  apparatus 
  was 
  allowed 
  to 
  cool. 
  

  

  The 
  iodine 
  in 
  the 
  receiver 
  was 
  titrated 
  directly 
  with 
  sodium 
  

   thiosulphate, 
  and 
  that 
  in 
  the 
  retort 
  after 
  dilution 
  of 
  the 
  residue 
  

   to 
  about 
  400^=°^^, 
  the 
  later 
  amount 
  seldom 
  exceeding 
  the 
  equiva- 
  

   lent 
  of 
  a 
  few 
  drops 
  of 
  jL- 
  N 
  iodine 
  solution. 
  

  

  The 
  results 
  follow 
  in 
  Table 
  II. 
  

  

  Here 
  also 
  blank 
  determinations 
  were 
  made 
  but 
  no 
  correction 
  

   was 
  found 
  to 
  be 
  necessary. 
  

  

  An 
  attempt 
  early 
  in 
  the 
  work 
  to 
  titrate 
  by 
  an 
  alkaline 
  arse- 
  

   nite 
  the 
  iodine 
  liberated, 
  after 
  neutralizing 
  the 
  hydrochloric 
  

   acid, 
  brought 
  out 
  some 
  curious 
  results 
  which 
  seem 
  worthy 
  of 
  

   mention. 
  

  

  

  

  Table 
  II. 
  

  

  

  

  CeOs 
  taken. 
  

  

  CeOs 
  found. 
  

  

  Error. 
  

  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  (0 
  

  

  0-1028 
  

  

  0-1013 
  

  

  0-0015 
  

  

  (2) 
  

  

  0-2060 
  

  

  0-2055 
  

  

  0-0005 
  

  

  (3) 
  

  

  0-2014 
  

  

  0-2012 
  

  

  0-0002 
  

  

  (4) 
  

  

  0-1716 
  

  

  0-1711 
  

  

  0-0005 
  

  

  (5) 
  

  

  0-0974 
  

  

  0-0972 
  

  

  0-0002 
  

  

  (6) 
  

  

  0-1600 
  

  

  0-1587 
  

  

  0-0013 
  

  

  (7) 
  

  

  0-1268 
  

  

  0-1254 
  

  

  0-0014 
  

  

  (8) 
  

  

  0-1276 
  

  

  0-1268 
  

  

  0-0008 
  

  

  (9) 
  

  

  0-1620 
  

  

  0-1612 
  

  

  0-0008 
  

  

  (10) 
  

  

  0-1016 
  

  

  0-1011 
  

  

  0-0005 
  

  

  (11) 
  

  

  0-1548 
  

  

  0-1543 
  

  

  0-0005 
  

  

  (12) 
  

  

  01352 
  

  

  0-1342 
  

  

  0-0010 
  

  

  * 
  The 
  carbon 
  dioxide 
  gas 
  was 
  furnished 
  by 
  a 
  Kipp 
  generator 
  from 
  marble 
  and 
  

   hydrochloric 
  acid 
  of 
  one-half 
  strength, 
  both 
  of 
  which 
  had 
  been 
  boiled 
  previously 
  

   to 
  remove 
  all 
  air. 
  

  

  