﻿296 
  Gooch 
  and 
  Walker 
  — 
  Analysis 
  of 
  Iodides. 
  

  

  being 
  not 
  greater 
  than 
  250 
  cm3 
  . 
  The 
  results 
  show 
  plainly 
  that 
  

   while 
  the 
  loss, 
  mechanical 
  or 
  otherwise, 
  in 
  the 
  treatment 
  of 
  

   reasonably 
  large 
  amounts 
  of 
  fairly 
  concentrated 
  iodine 
  is 
  per- 
  

   ceptible, 
  it 
  is 
  still 
  well 
  within 
  permissible 
  limits 
  (amounting 
  to 
  a 
  

   little 
  less 
  than 
  0*0005 
  grin, 
  in 
  the 
  mean), 
  and 
  obviously 
  inde- 
  

   pendent 
  of 
  the 
  excess 
  of 
  the 
  carbonate 
  in 
  the 
  solution, 
  and 
  

   of 
  the 
  amount 
  of 
  free 
  iodine 
  present. 
  

  

  In 
  the 
  experiments 
  of 
  Table 
  II 
  the 
  proposed 
  process 
  of 
  

   analysis 
  was 
  tested 
  upon 
  potassium 
  iodide 
  taken 
  by 
  itself 
  in 
  

   varying 
  amounts 
  of 
  a 
  ^ 
  normal 
  solution 
  and 
  carefully 
  stand- 
  

   ardized 
  by 
  the 
  method 
  formerly 
  elaborated 
  in 
  this 
  laboratory.* 
  

   The 
  apparatus 
  employed 
  was 
  a 
  Drexel 
  washing-bottle 
  of 
  500 
  cm3 
  

   or 
  1000 
  cm:; 
  capacity, 
  according 
  to 
  requirements, 
  with 
  stop-cock 
  

   and 
  thistle-tube 
  fused 
  to 
  the 
  inlet 
  tube 
  and 
  a 
  Will 
  and 
  Varren- 
  

   trapp 
  absorption 
  trap 
  sealed 
  to 
  the 
  outlet, 
  as 
  shown 
  in 
  the 
  

   accompanying 
  figure. 
  The 
  iodide 
  for 
  the 
  test 
  

   was 
  drawn 
  from 
  a 
  burette 
  into 
  the 
  bottle 
  and 
  

   carefully 
  washed 
  down, 
  and 
  potassium 
  iodate 
  in 
  

   excess 
  of 
  the 
  amount 
  theoretically 
  necessary 
  

   (namely, 
  5 
  cm3 
  of 
  a 
  0*5 
  per 
  cent 
  solution 
  for 
  every 
  

   portion 
  of 
  20 
  cm3 
  of 
  the 
  iodide 
  solution), 
  was 
  added 
  

   and 
  the 
  volume 
  of 
  the 
  liquid 
  was 
  adjusted 
  to 
  the 
  

   volume 
  at 
  which 
  it 
  was 
  desired 
  that 
  the 
  iodic 
  

   and 
  hydriodic 
  acids 
  should 
  react. 
  The 
  stopper 
  

   with 
  the 
  thistle-tube 
  and 
  trap 
  was 
  now 
  placed 
  

   on 
  the 
  bottle 
  and 
  the 
  trap 
  was 
  half 
  filled 
  by 
  

   means 
  of 
  a 
  pipette 
  with 
  a 
  5 
  per 
  cent 
  solution 
  of 
  

   potassium 
  iodide. 
  Five 
  centimeters 
  of 
  dilute 
  (1:3) 
  sulphuric 
  

   acid 
  were 
  added 
  through 
  the 
  thistle-tube 
  and 
  washed 
  down 
  ; 
  

   the 
  stop-cock 
  was 
  closed, 
  and 
  the 
  solution 
  gently 
  agitated, 
  if 
  

   necessary, 
  to 
  insure 
  a 
  complete 
  separation 
  of 
  iodine. 
  Potas- 
  

   sium 
  bicarbonate 
  in 
  saturated 
  solution 
  to 
  an 
  amount 
  about 
  

   10 
  cm 
  in 
  excess 
  of 
  that 
  required 
  to 
  neutralize 
  5 
  cmS 
  of 
  dilute 
  (1:3) 
  

   sulphuric 
  acid, 
  was 
  poured 
  into 
  the 
  thistle-tube, 
  and 
  allowed 
  

   to 
  flow 
  into 
  the 
  bottle 
  slowly 
  enough 
  to 
  avoid 
  a 
  too 
  violent 
  

   evolution 
  of 
  gas. 
  The 
  stop-cock 
  was 
  closed 
  and 
  the 
  solution 
  

   agitated 
  by 
  giving 
  to 
  the 
  bottle 
  a 
  rotary 
  motion, 
  at 
  the 
  same 
  

   time 
  keeping 
  the 
  bottom 
  pressed 
  down 
  upon 
  the 
  work-table, 
  to 
  

   prevent 
  a 
  possible 
  splashing 
  of 
  the 
  iodide 
  out 
  of 
  the 
  trap 
  into 
  

   the 
  yet 
  acid 
  solution. 
  When 
  the 
  neutralization 
  of 
  the 
  solution 
  

   had 
  been 
  completed, 
  the 
  bottle 
  was 
  shaken 
  until 
  the 
  last 
  trace 
  

   of 
  violet 
  vapor 
  was 
  absorbed 
  in 
  the 
  liquid. 
  The 
  greater 
  part 
  

   of 
  the 
  solution 
  in 
  the 
  trap 
  was 
  then 
  run 
  back 
  into 
  the 
  bottle, 
  

   the 
  stopper 
  removed, 
  and 
  the 
  tube 
  and 
  trap 
  carefully 
  washed, 
  

   the 
  washings 
  being 
  added 
  to 
  the 
  bulk 
  of 
  the 
  solution. 
  Deci- 
  

  

  * 
  Gooch 
  and 
  Browning: 
  This 
  Journal, 
  xxxix, 
  188. 
  

  

  

  