﻿298 
  

  

  Gooch 
  and 
  Walker 
  — 
  Analysis 
  of 
  Iodides. 
  

  

  , 
  The 
  number 
  of 
  centimeters 
  of 
  decinormal 
  arsenious 
  acid 
  

   required 
  to 
  bleach 
  the 
  free 
  iodine, 
  multiplied 
  by 
  0*01383 
  (log. 
  

   2*140822) 
  gives 
  the 
  number 
  of 
  grams 
  of 
  potassium 
  iodide 
  taken 
  

   for 
  analysis, 
  being 
  equivalent 
  to 
  five-sixths 
  of 
  the 
  iodine 
  lib- 
  

   erated 
  in 
  the 
  solution. 
  

  

  From 
  these 
  results 
  it 
  appears 
  that 
  the 
  degree 
  of 
  dilution 
  of 
  

   the 
  solution 
  at 
  the 
  time 
  when 
  the 
  mixed 
  iodide 
  and 
  iodate 
  are 
  

   acidified 
  has 
  an 
  important 
  influence 
  on 
  the 
  completeness 
  of 
  

   the 
  reaction. 
  Thus, 
  the 
  mean 
  error 
  of 
  the 
  determinations 
  in 
  

   which 
  the 
  volume 
  at 
  the 
  time 
  of 
  the 
  reaction 
  did 
  not 
  exceed 
  

   150 
  cmS 
  was 
  practically 
  nothing, 
  while 
  the 
  errors 
  at 
  volumes 
  of 
  

   300 
  cm3 
  and 
  500 
  cm3 
  amounted 
  to 
  0*0016 
  grm. 
  and 
  0*0028 
  grm. 
  

   respectively. 
  It 
  is 
  obvious 
  that 
  the 
  doubling 
  of 
  the 
  amount 
  of 
  

   sulphuric 
  acid 
  used 
  in 
  acidifying 
  does 
  not 
  increase 
  the 
  amount 
  

   of 
  iodine 
  liberated 
  at 
  the 
  highest 
  dilution. 
  The 
  plain 
  infer- 
  

   ence 
  is 
  that 
  the 
  interaction 
  between 
  the 
  iodide 
  and 
  iodate 
  

   should 
  be 
  brought 
  about 
  in 
  a 
  volume 
  of 
  liquid 
  not 
  much 
  ex- 
  

   ceeding 
  150 
  cm3 
  . 
  

  

  In 
  the 
  following 
  series 
  of 
  experiments, 
  recorded 
  in 
  Table 
  III, 
  

   the 
  effect 
  of 
  the 
  introduction 
  of 
  a 
  chloride 
  or 
  bromide 
  into 
  the 
  

   iodide 
  (before 
  the 
  iodate 
  is 
  added) 
  was 
  studied. 
  The 
  volume 
  

   of 
  the 
  liquid 
  at 
  the 
  time 
  of 
  acidifying 
  was 
  fixed 
  at 
  150 
  cm3 
  , 
  

   approximately, 
  and 
  5 
  cmS 
  of 
  the 
  dilute 
  sulphuric 
  acid 
  (1 
  : 
  3) 
  

   were 
  used. 
  The 
  mode 
  of 
  procedure 
  was 
  otherwise 
  similar 
  to 
  

   that 
  of 
  the 
  foregoing 
  series. 
  

  

  

  Table 
  

  

  III. 
  

  

  

  

  

  JEJffect 
  of 
  Chloride 
  and 
  Bron 
  

  

  dde. 
  

  

  

  

  KI 
  taken. 
  KI 
  found. 
  

  

  Error. 
  

  

  NaCl 
  taken. 
  

  

  KBr 
  taken 
  

  

  

  grm. 
  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  grm. 
  

  

  (1) 
  

  

  0-0772 
  0-0795 
  

  

  0-0023 
  + 
  

  

  0*2 
  

  

  

  (2) 
  

  

  0*0772 
  0-0784 
  

  

  0*0012 
  + 
  

  

  0-2 
  

  

  

  (3) 
  

  

  0*0771 
  0*0823 
  

  

  0*0052 
  + 
  

  

  0*5 
  

  

  . 
  _ 
  

  

  (4) 
  

  

  0*0773 
  0*0819 
  

  

  0*0046 
  + 
  

  

  0*5 
  

  

  

  

  (5) 
  

  

  0*1544 
  01588 
  

  

  0*0044 
  + 
  

  

  0*5 
  

  

  

  (6) 
  

  

  0*1544 
  0*1590 
  

  

  0*0046 
  + 
  

  

  0*5 
  

  

  

  (V) 
  

  

  0*0772 
  0-0802 
  

  

  0*0030 
  + 
  

  

  

  0*2 
  

  

  (8) 
  

  

  0*0773 
  0*0853 
  

  

  0*0080 
  + 
  

  

  

  0*2 
  

  

  (9) 
  

  

  0-0772 
  0*0873 
  

  

  0*0101 
  + 
  

  

  

  0*5 
  

  

  (10) 
  

  

  0*0772 
  0-0861 
  

  

  0*0089 
  + 
  

  

  

  0*5 
  , 
  

  

  (") 
  

  

  0*1544 
  0*1646 
  

  

  0*0102 
  + 
  

  

  

  0*5 
  

  

  (12) 
  

  

  0-1543 
  0*1626 
  

  

  0*0083 
  + 
  

  

  .. 
  

  

  0*5 
  

  

  The 
  influence 
  of 
  sodium 
  chloride 
  and 
  potassium 
  bromide 
  in 
  

   increasing 
  the 
  amount 
  of 
  iodine 
  liberated 
  is 
  plain. 
  The 
  

   increase 
  comes 
  without 
  doubt 
  from 
  the 
  iodate, 
  and 
  is 
  doubtless 
  

   due 
  to 
  the 
  formation 
  of 
  iodine 
  chloride 
  or 
  bromide, 
  during 
  the 
  

  

  