﻿124 
  Gooch 
  and 
  Peters 
  — 
  Determination 
  of 
  Tellurous 
  

  

  the 
  solution 
  was 
  heated 
  with 
  enough 
  snlphnric 
  acid 
  [1:1] 
  ta 
  

   neutralize 
  the 
  alkaline 
  hydroxide 
  and 
  have 
  an 
  excess 
  of 
  about 
  

   5*'°'^ 
  In 
  the 
  experiments 
  of 
  Section 
  A 
  the 
  liqnid 
  was 
  heated 
  

   to 
  60°-80° 
  C. 
  to 
  dissolve 
  the 
  oxides 
  at 
  the 
  final 
  titration 
  begun 
  

   at 
  that 
  temperature 
  ; 
  in 
  those 
  of 
  Section 
  B, 
  manganous 
  chloride 
  

   (0*5 
  to 
  1 
  gram) 
  was 
  added, 
  so 
  that 
  the 
  reduction 
  of 
  the 
  

   higher 
  oxides 
  of 
  manganese 
  and 
  the 
  final 
  titration 
  of 
  the 
  excess 
  

   of 
  oxalic 
  acid 
  might 
  take 
  place 
  at 
  the 
  ordinary 
  temperature 
  of 
  

   the 
  room. 
  

  

  Plainly 
  the 
  presence 
  of 
  the 
  chloride 
  does 
  not 
  interfere 
  mate- 
  

   rially 
  in 
  the 
  determination 
  of 
  the 
  tellurium 
  by 
  this 
  process 
  

   whether 
  the 
  titration 
  is 
  made 
  at 
  a 
  high 
  or 
  low 
  temperature. 
  • 
  

  

  It 
  appears, 
  also, 
  upon 
  putting 
  the 
  matter 
  to 
  the 
  test, 
  that 
  

   fairly 
  good 
  determinations 
  of 
  tellurous 
  acid 
  may 
  be 
  made 
  

   similarly 
  in 
  the 
  presence 
  of 
  a 
  bromide, 
  provided 
  the 
  titration 
  

   is 
  made 
  at 
  the 
  atmospheric 
  temperature 
  in 
  the 
  presence 
  of 
  a 
  

   sufiiciency 
  (0*5 
  gram 
  to 
  1 
  gram) 
  of 
  a 
  manganous 
  salt 
  and 
  of 
  an 
  

   excess 
  of 
  sulphuric 
  acid 
  limited 
  to 
  about 
  b^^^ 
  or 
  less 
  of 
  the 
  

   12'5 
  per 
  cent 
  mixture. 
  At 
  the 
  higher 
  temperatures 
  bromine 
  

   is 
  liberated 
  at 
  once 
  from 
  the 
  acid 
  solution 
  by 
  the 
  permanganate. 
  

   The 
  experimental 
  results 
  are 
  given 
  in 
  Table 
  II. 
  

  

  

  

  

  Table 
  II 
  

  

  

  

  

  

  

  = 
  

  

  = 
  16, 
  Te 
  = 
  

  

  12'7-5. 
  

  

  

  

  

  

  Yolume 
  

  

  at 
  beginning, 
  150<>'«3. 
  

  

  

  

  

  

  Temperature 
  of 
  titration, 
  24°-26° 
  

  

  C. 
  

  

  

  TeOa 
  

  

  

  

  H2SO4 
  

  

  MnCU 
  . 
  

  

  TeOa 
  

  

  

  taken. 
  

  

  NaCl. 
  

  

  KBr. 
  

  

  12 
  5 
  %. 
  

  

  4H2O. 
  

  

  found. 
  

  

  Error. 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  cm'^. 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  "o-iooo 
  

  

  

  

  0-5 
  

  

  20 
  

  

  1-0 
  

  

  0-1022 
  

  

  + 
  0-0022" 
  

  

  _0 
  3000 
  

  

  

  

  1-5 
  

  

  25 
  

  

  1-0 
  

  

  0-3030 
  

  

  + 
  0-0030_ 
  

  

  0-0650 
  

  

  

  0-5 
  

  

  1 
  

  

  1-0 
  

  

  0-0661 
  

  

  + 
  0-0011 
  

  

  0-0650 
  

  

  

  0-5 
  

  

  1 
  

  

  1-0 
  

  

  0-0647 
  

  

  — 
  0-0003 
  

  

  0-1000 
  

  

  

  0-5 
  

  

  1 
  

  

  1-0 
  

  

  0-1002 
  

  

  + 
  00002 
  

  

  0-3000 
  

  

  

  

  0-5 
  

  

  5 
  

  

  0-5 
  

  

  0-3010 
  

  

  + 
  0-0010 
  

  

  0-0650 
  

  

  0-5 
  

  

  0-5 
  

  

  1 
  

  

  1-0 
  

  

  0-0661 
  

  

  + 
  0-0011 
  

  

  It 
  is 
  obvious, 
  therefore, 
  that 
  tellurous 
  acid 
  may 
  be 
  deter- 
  

   mined 
  with 
  a 
  fair 
  degree 
  of 
  accuracy 
  by 
  the 
  permanganate 
  

   method 
  in 
  the 
  presence 
  of 
  chlorides 
  and 
  bromides, 
  provided 
  

   the 
  first 
  oxidation 
  is 
  made 
  in 
  alkaline 
  solution 
  and 
  the 
  final 
  

   titration 
  of 
  the 
  residual 
  oxalic 
  acid 
  is 
  made 
  at 
  ordinary 
  tem- 
  

   peratures 
  in 
  the 
  presence 
  of 
  a 
  manganous 
  salt 
  and 
  restricted 
  

   amounts 
  of 
  free 
  sulphuric 
  acid. 
  

  

  In 
  the 
  presence 
  of 
  an 
  iodide, 
  however, 
  the 
  case 
  is 
  different. 
  

   Upon 
  acidifying 
  the 
  mixture 
  of 
  iodide 
  and 
  the 
  higher 
  oxygen 
  

   compounds 
  of 
  manganese, 
  produced 
  in 
  the 
  action 
  of 
  the 
  per- 
  

   manganate 
  upon 
  the 
  solution, 
  iodine 
  is 
  at 
  once 
  set 
  free, 
  and 
  

  

  