﻿I). 
  A. 
  Kr 
  eider 
  — 
  Preparation 
  of 
  Perchloric 
  Acid, 
  etc. 
  443 
  

  

  Art. 
  XXX 
  VI. 
  — 
  The 
  Preparation 
  of 
  Perchloric 
  Acid 
  and 
  its 
  

   Application 
  to 
  the 
  Determination 
  of 
  Potassium 
  ; 
  by 
  D. 
  

   Albert 
  Kreider. 
  

  

  [Contributions 
  from 
  the 
  Kent 
  Chemical 
  Laboratory 
  of 
  Yale 
  College. 
  — 
  XXXVIII.] 
  

  

  Various 
  methods 
  for 
  the 
  preparation 
  of 
  perchloric 
  acid 
  

   have 
  been 
  developed 
  through 
  the 
  long 
  felt 
  want 
  of 
  a 
  process 
  

   in 
  which 
  the 
  elements 
  of 
  time 
  and 
  danger 
  would 
  be 
  reduced 
  to 
  

   a 
  minimum 
  and 
  the 
  product 
  increased 
  to 
  quantities 
  commen- 
  

   surate 
  with 
  the 
  growing 
  use 
  of 
  the 
  acid 
  in 
  analytical 
  chemistry. 
  

   Most 
  of 
  these 
  methods 
  have 
  been 
  found 
  impracticable 
  because 
  

   of 
  the 
  incidental 
  formation 
  of 
  the 
  dangerously 
  explosive 
  oxides 
  

   of 
  chlorine, 
  or 
  the 
  time 
  required 
  in 
  refining 
  the 
  product 
  from 
  

   the 
  impurities 
  introduced 
  with 
  the 
  reagents 
  employed. 
  

  

  Doubtless 
  the 
  best 
  process 
  thus 
  far 
  offered 
  is 
  that 
  of 
  Caspari,* 
  

   which, 
  however, 
  is 
  to 
  an 
  objectionable 
  degree 
  exacting 
  of 
  time 
  

   and 
  labor. 
  The 
  product 
  has 
  to 
  be 
  treated 
  and 
  retreated 
  for 
  

   the 
  removal 
  of 
  potassium 
  and 
  then 
  for 
  the 
  extraction 
  of 
  the 
  

   hydro-fluo-silicic-acid 
  and 
  at 
  several 
  stages 
  is 
  for 
  this 
  purpose 
  

   to 
  be 
  left 
  standing 
  for 
  from 
  twenty-four 
  to 
  forty 
  -eight 
  hours. 
  

   Under 
  the 
  most 
  favorable 
  circumstances 
  it 
  could 
  not 
  be 
  pre- 
  

   pared 
  in 
  less 
  than 
  five 
  or 
  six 
  days, 
  and 
  during 
  a 
  great 
  many 
  

   hours 
  of 
  that 
  time 
  it 
  requires 
  close 
  attention. 
  

  

  The 
  great 
  difficulty 
  has 
  always 
  been 
  with 
  the 
  necessity 
  of 
  a 
  

   perfect 
  sejDaration 
  of 
  jDotassium 
  from 
  the 
  perchloric 
  acid, 
  which 
  

   has 
  been 
  prepared 
  by 
  the 
  ignition 
  of 
  the 
  potassium 
  chlorate. 
  

   If, 
  for 
  the 
  manufacture 
  of 
  the 
  perchlorate, 
  the 
  chlorate 
  of 
  

   sodium 
  — 
  which, 
  if 
  not 
  upon 
  the 
  shelves 
  of 
  every 
  laboratory, 
  is 
  

   nevertheless 
  in 
  the 
  market, 
  almost, 
  if 
  not 
  entirely 
  free 
  of 
  potas- 
  

   sium 
  — 
  be 
  used 
  instead 
  of 
  the 
  potassium 
  salt, 
  the 
  complete 
  

   removal 
  of 
  the 
  base 
  will 
  be 
  unessential 
  ; 
  since 
  its 
  presence 
  in 
  

   the 
  determination 
  of 
  potassium 
  will 
  exert 
  no 
  influence 
  other 
  

   than 
  that 
  which 
  is 
  beneficial. 
  It 
  is 
  well 
  known 
  that 
  because 
  

   of 
  its 
  deliquescence 
  and 
  the 
  almost 
  equal 
  solubility 
  of 
  sodium 
  

   perchlorate 
  with 
  that 
  of 
  the 
  chloride, 
  its 
  separation 
  from 
  the 
  

   latter 
  by 
  recrystallization 
  from 
  an 
  aqueous 
  solution, 
  as 
  in 
  the 
  

   case 
  of 
  potassium, 
  is 
  impossible. 
  But 
  the 
  insolubility 
  of 
  the 
  

   chloride 
  of 
  sodium 
  in 
  strong 
  hydrochloric 
  acid, 
  with 
  the 
  aid 
  of 
  

   the 
  acid-proof 
  Gooch 
  crucible, 
  affords 
  a 
  means 
  for 
  the 
  libera- 
  

   tion 
  of 
  the 
  perchloric 
  acid 
  and 
  the 
  removal 
  of 
  the 
  greater 
  part 
  

   of 
  the 
  sodium 
  in 
  one 
  operation. 
  * 
  Upon 
  this 
  basis, 
  therefore, 
  

   the 
  following 
  simple 
  method 
  was 
  elaborated. 
  

  

  A 
  convenient 
  quantity 
  of 
  sodium 
  chlorate, 
  from 
  100 
  to 
  300 
  

   grms., 
  is 
  melted 
  in 
  a 
  glass 
  retort 
  or 
  round-bottomed 
  flask 
  and 
  

  

  * 
  Zeitschr. 
  fur 
  Ang. 
  Chem., 
  1893, 
  p. 
  68. 
  

  

  