﻿DESTRUCTIVE 
  DISTILLATION 
  OF 
  ANIMAL 
  SUBSTANCES. 
  253 
  

  

  I 
  have 
  thus 
  then 
  established 
  the 
  existence, 
  among 
  the 
  products 
  of 
  destructive 
  

   distillation, 
  of 
  ammonia, 
  and 
  the 
  first 
  four 
  members 
  of 
  the 
  series 
  of 
  bases 
  homo- 
  

   logous 
  with 
  it. 
  I 
  have 
  every 
  reason, 
  however, 
  to 
  believe 
  that 
  the 
  series 
  does 
  not 
  

   end 
  with 
  petinine, 
  for 
  the 
  fraction 
  boiling 
  about 
  200° 
  yields 
  a 
  platinum 
  salt 
  in 
  fine 
  

   scales, 
  and 
  having 
  all 
  the 
  characters 
  of 
  the 
  salts 
  of 
  the 
  same 
  series 
  of 
  bases, 
  and 
  

   in 
  all 
  probability 
  contains 
  valeramine. 
  I 
  am 
  not 
  without 
  hope 
  also 
  of 
  obtaining 
  

   caprylamine 
  ; 
  but 
  this 
  I 
  expect 
  will 
  be 
  the 
  last 
  of 
  the 
  series, 
  for 
  when 
  we 
  reach 
  

   the 
  temperature 
  of 
  about 
  240°, 
  the 
  character 
  of 
  the 
  bases 
  changes, 
  and 
  we 
  enter 
  

   upon 
  an 
  entirely 
  different 
  series. 
  

  

  In 
  the 
  separation 
  of 
  the 
  bases 
  boiling 
  above 
  240°, 
  I 
  have 
  encountered 
  very 
  great 
  

   difficulties. 
  After 
  the 
  trial 
  of 
  many 
  different 
  processes, 
  such 
  as 
  converting 
  them 
  

   into 
  salts, 
  exposing 
  them 
  to 
  cold, 
  partial 
  saturation, 
  and 
  every 
  other 
  plan 
  which 
  

   appeared 
  likely 
  to 
  answer, 
  I 
  have 
  been 
  compelled 
  to 
  return 
  to 
  fractionated 
  distil- 
  

   lation, 
  as 
  the 
  method 
  most 
  likely 
  to 
  answer 
  the 
  end 
  I 
  had 
  in 
  view. 
  But 
  even 
  with 
  

   this 
  process 
  the 
  difficulties 
  are 
  great, 
  and 
  I 
  have 
  been 
  by 
  no 
  means 
  so 
  successful 
  in 
  

   obtaining 
  fixed 
  boiling 
  points 
  as 
  I 
  was 
  when 
  operating 
  on 
  a 
  smaller 
  scale 
  in 
  my 
  

   former 
  preparations. 
  I 
  subjected 
  the 
  whole 
  of 
  the 
  oils 
  boiling 
  above 
  212° 
  to 
  a 
  sys- 
  

   tematic 
  course 
  of 
  fractionation, 
  each 
  fraction 
  being 
  distilled 
  alone, 
  and 
  the 
  product 
  

   collected 
  in 
  a 
  fresh 
  series 
  of 
  bottles, 
  and 
  the 
  receivers 
  changed 
  at 
  every 
  ten 
  de- 
  

   grees. 
  In 
  the 
  earlier 
  rectifications 
  each 
  fraction 
  spread 
  itself 
  over 
  a 
  very 
  large 
  num- 
  

   ber 
  of 
  degrees, 
  and 
  shewed 
  little 
  tendency 
  towards 
  concentration 
  to 
  fixed 
  points. 
  

   The 
  distillations 
  were 
  repeated 
  no 
  less 
  than 
  fourteen 
  times, 
  but 
  even 
  after 
  all 
  this 
  

   the 
  indications 
  of 
  boiling 
  points 
  were 
  extremely 
  indistinct^ 
  Sometimes 
  in 
  one 
  dis- 
  

   tillation 
  certain 
  fractions 
  appeared 
  larger 
  than 
  others, 
  but 
  their 
  pre-eminence 
  disap- 
  

   peared 
  again 
  in 
  succeeding 
  rectifications. 
  Still 
  a 
  certain 
  improvement 
  was 
  manifest, 
  

   some 
  of 
  the 
  fractions 
  being 
  confined 
  more 
  nearly 
  to 
  the 
  range 
  of 
  degrees 
  within 
  

   which 
  they 
  had 
  boiled 
  at 
  the 
  previous 
  rectification. 
  It 
  was 
  obvious, 
  from 
  the 
  whole 
  

   phenomena 
  of 
  the 
  distillation, 
  that 
  the 
  separation 
  of 
  the 
  different 
  bases 
  was 
  going 
  

   on, 
  although 
  with 
  extreme 
  slowness 
  ; 
  and 
  at 
  this 
  point 
  I 
  endeavoured, 
  by 
  the 
  

   examination 
  of 
  the 
  platinum 
  salts 
  obtained 
  at 
  different 
  temperatures, 
  to 
  deter- 
  

   mine 
  the 
  constitution 
  of 
  the 
  bases 
  which 
  these 
  fractions 
  contained 
  ; 
  and 
  as 
  I 
  knew 
  

   from 
  previous 
  experiment, 
  that 
  the 
  quantity 
  boiling 
  between 
  270° 
  and 
  280° 
  con- 
  

   sisted 
  of 
  picoline, 
  I 
  had 
  from 
  this 
  fact 
  indications 
  of 
  the 
  temperatures 
  at 
  which 
  

   bases 
  were 
  likely 
  to 
  be 
  found, 
  and 
  I 
  have 
  thus 
  been 
  enabled 
  to 
  determine 
  the 
  

   existence 
  of 
  two 
  substances 
  belonging 
  to 
  the 
  same 
  homologous 
  series 
  with 
  that 
  

  

  substance. 
  

  

  Pyridine. 
  

  

  The 
  first 
  of 
  these 
  bases, 
  to 
  which 
  I 
  give 
  the 
  name 
  of 
  pyridine, 
  occurs 
  in 
  the 
  

   fraction 
  boiling 
  about 
  240°. 
  This 
  fraction 
  has 
  an 
  odour 
  precisely 
  similar 
  to 
  that 
  of 
  

   picoline, 
  but 
  more 
  powerful 
  and 
  pungent. 
  It 
  is 
  perfectly 
  transparent 
  and 
  colour- 
  

  

  