﻿Acid 
  in 
  presence 
  of 
  Haloid 
  Salts, 
  123 
  

  

  as 
  are 
  necessary 
  to 
  a 
  correct 
  determination 
  of 
  oxalic 
  acid 
  by 
  

   permanganate 
  in 
  presence 
  of 
  hydrochloric 
  acid 
  ; 
  for, 
  the 
  special 
  

   danger 
  of 
  over-action 
  on 
  the 
  part 
  of 
  the 
  permanganate 
  cannot 
  

   exist 
  while 
  the 
  solution 
  is 
  alkaline, 
  and 
  has 
  passed 
  when 
  the 
  

   tellurite 
  has 
  become 
  a 
  tellurate 
  and 
  before 
  the 
  solution 
  is 
  made 
  

   acid. 
  As 
  to 
  the 
  proper 
  conditions 
  for 
  the 
  titration 
  of 
  oxalic 
  

   acid 
  by 
  permanganate 
  we 
  have 
  shown 
  recently'^ 
  that 
  the 
  pres- 
  

   ence 
  of 
  a 
  manganous 
  salt 
  is 
  necessary 
  and 
  sufficient 
  to 
  secure 
  

   regularity 
  of 
  action 
  when 
  a 
  considerable 
  amount 
  of 
  hydro- 
  

   chloric 
  acid 
  is 
  in 
  the 
  solution 
  ; 
  when 
  the 
  amount 
  is 
  small 
  

   — 
  so 
  much 
  as 
  would 
  be 
  formed 
  in 
  the 
  decomposition 
  of 
  a 
  

   gram 
  or 
  two 
  of 
  halogen 
  salt 
  of 
  tellurium 
  — 
  the 
  disturbing 
  

   effect 
  under 
  ordinary 
  conditions 
  of 
  work 
  is 
  probably 
  inappre- 
  

   ciable, 
  but 
  even 
  in 
  such 
  a 
  case 
  it 
  is 
  better 
  to 
  work 
  in 
  the 
  

   presence 
  of 
  a 
  manganous 
  salt 
  for 
  the 
  reason 
  that 
  the 
  titration 
  

   of 
  the 
  oxalic 
  acid 
  may 
  then 
  be 
  made 
  at 
  the 
  ordinary 
  atmos- 
  

   pheric 
  temperature. 
  

  

  In 
  the 
  following 
  table 
  are 
  gathered 
  the 
  results 
  of 
  experiments 
  

   made 
  with, 
  and 
  without, 
  the 
  addition 
  of 
  the 
  manganous 
  salt. 
  

  

  

  

  

  Table 
  I. 
  

  

  

  

  

  

  = 
  

  

  16, 
  Te=: 
  127-5. 
  

  

  

  

  

  Volume 
  

  

  at 
  beo-inninff, 
  

  

  150'=™^ 
  

  

  

  

  Temperature 
  of 
  titration, 
  

  

  60-80° 
  C. 
  

  

  

  TeO.2 
  taken. 
  

  

  NaCl. 
  

  

  H2SO4 
  

   1 
  • 
  1 
  

  

  MnClo.4H20 
  

  

  TeOa 
  found. 
  

  

  Error. 
  

  

  grm. 
  

  

  grm. 
  

  

  i 
  . 
  1. 
  

   cm-^ 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  0-1000 
  

  

  -4 
  

  

  5 
  

  

  

  

  0-1003 
  

  

  + 
  0-0003 
  

  

  0-1000 
  

  

  •4 
  

  

  5 
  

  

  

  

  0-1000 
  

  

  0-0000 
  

  

  0-1000 
  

  

  -4 
  

  

  5 
  

  

  

  

  0-1004 
  

  

  + 
  0-0004 
  

  

  0-1000 
  

  

  1-0 
  

  

  5 
  

  

  

  

  0-1003 
  

  

  + 
  0-0003 
  

  

  0-0650 
  1-0 
  5 
  0-0653 
  +0-0003 
  

  

  B. 
  

  

  Temperature 
  of 
  titration, 
  20-26° 
  C. 
  

  

  0-0700 
  -4 
  ■ 
  5-7 
  1-0 
  0-0705 
  +0-0005 
  

  

  0-0700 
  -4 
  5-7 
  1-0 
  0-0698 
  —0-0002 
  

  

  0-0700 
  -4 
  5-7 
  -5 
  0-0701 
  +0-0001 
  • 
  

  

  0-1000 
  -4 
  5-7 
  -5 
  0-1008 
  +0-0008 
  

  

  The 
  tellurium 
  dioxide, 
  made 
  by 
  the 
  careful 
  ignition 
  of 
  the 
  

   crystallized 
  basic 
  nitrate 
  obtained 
  by 
  oxidizing 
  tellurium 
  with 
  

   nitric 
  acid, 
  was 
  dissolved 
  in 
  a 
  small 
  amount 
  of 
  sodium 
  hydrox- 
  

   ide, 
  the 
  halogen 
  salt 
  was 
  added 
  to 
  the 
  amount 
  shown, 
  the 
  per- 
  

   manganate 
  standardized 
  against 
  ammonium 
  oxalate 
  was 
  run 
  in 
  

   until 
  its 
  characteristic 
  color 
  appeared, 
  standard 
  ammonium 
  

   oxalate 
  was 
  added 
  in 
  excess 
  of 
  the 
  quantity 
  required 
  to 
  reduce 
  

   the 
  excess 
  of 
  permanganate, 
  manganate, 
  and 
  higher 
  oxides, 
  and 
  

  

  * 
  This 
  Journal. 
  

  

  