﻿Estimation 
  of 
  Chlorates. 
  221 
  

  

  a 
  method 
  for 
  the 
  estimation 
  of 
  chlorates 
  — 
  this 
  to 
  consist 
  in 
  

   heating 
  the 
  chlorate, 
  in 
  acid 
  solution 
  and 
  under 
  conditions 
  

   otherwise 
  appropriate, 
  with 
  a 
  known 
  amount 
  of 
  potassium 
  

   iodide, 
  somewhat 
  in 
  excess 
  of 
  that 
  theoretically 
  equivalent 
  to 
  

   the 
  chlorate, 
  and 
  in 
  presence 
  of 
  an 
  excess 
  of 
  arsenic 
  acid, 
  the 
  

   arsenious 
  oxide 
  produced 
  in 
  the 
  process 
  being 
  determined 
  

   iodometrically 
  and 
  serving 
  to 
  measure 
  the 
  amount 
  of 
  iodide 
  

   left 
  undecomposed 
  by 
  the 
  chlorate. 
  Of 
  course, 
  the 
  difference 
  

   between 
  the 
  amount 
  of 
  iodide 
  left 
  undecomposed 
  and 
  that 
  

   originally 
  introduced 
  should 
  be 
  the 
  measure 
  of 
  the 
  chlorate 
  

   entering 
  into 
  the 
  reaction. 
  That 
  a 
  better 
  form 
  of 
  iodometric 
  

   method 
  than 
  those 
  we 
  have 
  had 
  heretofore 
  for 
  the 
  estimation 
  

   of 
  chlorates 
  is 
  desirable 
  is 
  obvious 
  when 
  it 
  is 
  recognized 
  that 
  

   Bunsen's 
  original 
  process 
  — 
  consisting 
  in 
  heating 
  the 
  chlorate 
  

   with 
  hydrochloric 
  acid 
  and 
  potassium 
  iodide, 
  distilling 
  and 
  

   estimating 
  the 
  iodine 
  collected 
  in 
  the 
  distillate 
  — 
  fails 
  (owing 
  to 
  

   the 
  formation 
  of 
  the 
  comparatively 
  non- 
  volatile 
  iodine 
  chloride 
  

   in 
  the 
  simultaneous 
  action 
  of 
  the 
  oxidizer 
  upon 
  hydrochloric 
  

   and 
  hydriodic 
  acids) 
  to 
  show 
  the 
  entire 
  amount 
  of 
  iodine 
  cor- 
  

   responding 
  to 
  the 
  chlorate 
  ; 
  and 
  that 
  Finkener's 
  substitute 
  for 
  

   this 
  process 
  — 
  which 
  prescribes 
  the 
  heating 
  of 
  the 
  chlorate, 
  

   under 
  pressure 
  in 
  a 
  closed 
  bottle 
  and 
  in 
  an 
  atmosphere 
  of 
  car- 
  

   bon 
  dioxide, 
  with 
  a 
  mixture 
  of 
  hydrochloric 
  acid 
  and 
  potas- 
  

   sium 
  iodide 
  previously 
  prepared 
  by 
  treatment 
  with 
  sulphurous 
  

   acid, 
  boiling 
  and 
  subsequent 
  cooling 
  in 
  an 
  atmosphere 
  of 
  car- 
  

   bon 
  dioxide 
  — 
  though 
  excellent 
  when 
  properly 
  carried 
  out, 
  

   demands 
  careful 
  preparation 
  of 
  materials 
  and 
  skillful 
  handling 
  

   in 
  the 
  execution. 
  

  

  We 
  have 
  studied 
  the 
  applicability 
  of 
  the 
  process 
  outlined 
  

   above 
  and 
  record 
  our 
  experience 
  in 
  the 
  following 
  account. 
  

  

  A 
  solution 
  of 
  potassium 
  iodide, 
  approximately 
  decinormal, 
  

   was 
  standardized 
  according 
  to 
  the 
  method 
  to 
  which 
  reference 
  

   has 
  been 
  made 
  and 
  which 
  may 
  be 
  summarized 
  in 
  brief, 
  as 
  fol- 
  

   lows 
  : 
  Portions 
  of 
  this 
  solution 
  were 
  measured 
  from 
  a 
  burette 
  

   into 
  Erlenmeyer 
  beakers 
  capable 
  of 
  holding 
  300 
  cm. 
  3 
  , 
  2 
  grms., 
  

   approximately, 
  of 
  pure 
  dihydrogen 
  potassium 
  arseniate 
  were 
  

   added 
  in 
  solution, 
  20 
  cm. 
  3 
  of 
  a 
  mixture 
  of 
  sulphuric 
  acid 
  and 
  

   water 
  in 
  equal 
  volumes 
  were 
  introduced 
  with 
  enough 
  water 
  

   beside 
  to 
  increase 
  the 
  entire 
  volume 
  to 
  a 
  little 
  more 
  than 
  100 
  

   cm 
  3 
  . 
  A 
  platinum 
  spiral 
  was 
  introduced 
  to 
  secure 
  quiet 
  boil- 
  

   ing, 
  a 
  trap 
  made 
  of 
  a 
  straight 
  two-bulbed 
  drying 
  tube 
  cut 
  short 
  

   was 
  hung 
  with 
  the 
  larger 
  end 
  in 
  the 
  neck 
  of 
  the 
  flask, 
  and 
  the 
  

   liquid 
  was 
  boiled 
  until 
  the 
  level 
  had 
  reached 
  a 
  mark 
  upon 
  the 
  

   flask 
  indicating 
  a 
  volume 
  of 
  35 
  cm. 
  3 
  , 
  experience 
  having 
  shown 
  

   that 
  this 
  degree 
  of 
  concentration 
  is 
  sufficient 
  and 
  that 
  it 
  is 
  

   best 
  not 
  to 
  exceed 
  it. 
  The 
  liquid 
  remaining 
  was 
  cooled 
  and 
  

   nearly 
  neutralized 
  by 
  sodium 
  hydrate, 
  acid 
  potassium 
  carbonate 
  

  

  