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  Kreider 
  — 
  Preparation 
  of 
  Perchloric 
  A 
  cid 
  and 
  its 
  

  

  gradually 
  raised 
  to 
  a 
  temperature 
  at 
  which 
  oxygen 
  is 
  freely, 
  

   but 
  not 
  too 
  rapidly 
  evolved, 
  and 
  kept 
  at 
  this 
  temperature 
  till 
  

   the 
  fused 
  mass 
  thickens 
  throughout, 
  which 
  indicates 
  the 
  com- 
  

   plete 
  conversion 
  of 
  the 
  chlorate 
  to 
  the 
  chloride 
  and 
  perchlorate, 
  

   and 
  requires 
  between 
  one 
  and 
  one-half 
  to 
  two 
  hours 
  : 
  or 
  the 
  

   retort 
  may 
  be 
  connected 
  with 
  a 
  gasometer 
  and 
  the 
  end 
  of 
  the 
  

   reaction 
  determined 
  by 
  the 
  volume 
  of 
  oxygen 
  expelled, 
  accord- 
  

   ing 
  to 
  the 
  equation 
  

  

  2NaC10 
  3 
  = 
  NaCl 
  + 
  NaC10 
  4 
  + 
  O 
  g 
  . 
  

  

  The 
  product 
  thus 
  obtained 
  is 
  washed 
  from 
  the 
  retort 
  to 
  a 
  capa- 
  

   cious 
  evaporating 
  dish 
  where 
  it 
  is 
  treated 
  with 
  sufficient 
  hydro- 
  

   chloric 
  acid 
  to 
  effect 
  the 
  complete 
  reduction 
  of 
  the 
  residual 
  

   chlorate, 
  which, 
  if 
  the 
  ignition 
  has 
  been 
  carefully 
  conducted 
  

   with 
  well 
  distributed 
  heat, 
  will 
  be 
  present 
  in 
  but 
  small 
  amount. 
  

   It 
  is 
  then 
  evaporated 
  to 
  dryness 
  on 
  the 
  steam 
  bath, 
  or 
  more 
  

   quickly 
  over 
  a 
  direct 
  flame, 
  and 
  with 
  but 
  little 
  attention 
  until 
  

   a 
  point 
  near 
  to 
  dryness 
  has 
  been 
  reached, 
  when 
  stirring 
  will 
  be 
  

   found 
  of 
  great 
  advantage 
  in 
  facilitating 
  the 
  volatilization 
  of 
  

   the 
  remaining 
  liquid 
  and 
  in 
  breaking 
  up 
  the 
  mass 
  of 
  salt. 
  

   Otherwise 
  the 
  perchlorate 
  seems 
  to 
  solidify 
  with 
  a 
  certain 
  

   amount 
  of 
  water, 
  and 
  removal 
  from 
  the 
  dish, 
  without 
  moisten- 
  

   ing 
  and 
  reheating, 
  is 
  impossible. 
  

  

  After 
  triturating 
  the 
  residue, 
  easily 
  accomplished 
  in 
  a 
  porce- 
  

   lain 
  mortar, 
  an 
  excess 
  of 
  the 
  strongest 
  hydrochloric 
  acid 
  is 
  

   added 
  to 
  the 
  dry 
  salt, 
  preferably 
  in 
  a 
  tall 
  beaker 
  where 
  there 
  

   is 
  less 
  surface 
  for 
  the 
  escape 
  of 
  hydrochloric 
  acid 
  and 
  from 
  

   which 
  the 
  acid 
  can 
  be 
  decanted 
  without 
  disturbing 
  the 
  precipi- 
  

   tated 
  chlorid. 
  If 
  the 
  salt 
  has 
  been 
  reduced 
  to 
  a 
  very 
  fine 
  pow- 
  

   der, 
  by 
  stirring 
  energetically 
  for 
  a 
  minute, 
  the 
  hydrochloric 
  

   acid 
  will 
  set 
  free 
  the 
  perchloric 
  acid 
  and 
  precipitate 
  the 
  sodium 
  

   as 
  chloride, 
  which 
  in 
  a 
  few 
  minutes 
  settles, 
  leaving 
  a 
  clear 
  solu- 
  

   tion 
  of 
  the 
  perchloric 
  acid 
  with 
  the 
  excess 
  of 
  hydrochloric 
  acid. 
  

   The 
  clear 
  supernatant 
  liquid 
  is 
  then 
  decanted 
  upon 
  a 
  Grooch 
  

   filter, 
  through 
  which 
  it 
  may 
  be 
  rapidly 
  drawn 
  with 
  the 
  aid 
  of 
  

   suction, 
  and 
  the 
  residue 
  retreated 
  with 
  the 
  strongest 
  hydro- 
  

   chloric 
  acid, 
  settled, 
  and 
  again 
  decanted, 
  the 
  salt 
  being 
  finally 
  

   brought 
  upon 
  the 
  filter 
  where 
  it 
  is 
  washed 
  with 
  a 
  little 
  strong 
  

   hydrochloric 
  acid. 
  A 
  large 
  platinum 
  cone 
  will 
  be 
  found 
  more 
  

   convenient 
  than 
  the 
  crucible, 
  because 
  of 
  its 
  greater 
  capacity 
  

   and 
  filtering 
  surface. 
  When 
  the 
  filter 
  will 
  not 
  hold 
  all 
  the 
  

   sodium 
  chloride, 
  the 
  latter 
  after 
  being 
  washed 
  may 
  be 
  removed 
  

   by 
  water 
  or 
  by 
  mechanical 
  means, 
  with 
  precautions 
  not 
  to 
  dis- 
  

   turb 
  the 
  felt, 
  which 
  is 
  then 
  ready 
  for 
  the 
  remainder. 
  Of 
  

   course, 
  if 
  water 
  is 
  used, 
  the 
  felt 
  had 
  better 
  be 
  washed 
  with 
  a 
  

   little 
  strong 
  hydrochloric 
  acid 
  before 
  receiving 
  another 
  portion 
  

   of 
  the 
  salt. 
  This 
  residue 
  will 
  be 
  found 
  to 
  contain 
  only 
  an 
  

  

  