﻿PRODUCTS 
  OF 
  DECOMPOSITION 
  OF 
  COMENIC 
  ACID. 
  227 
  

  

  of 
  the 
  acid 
  in 
  a 
  slight 
  excess 
  of 
  ammonia, 
  and 
  subsequent 
  concentration 
  in 
  vacuo 
  

   over 
  sulphuric 
  acid. 
  He 
  describes 
  it 
  as 
  " 
  partly 
  amorphous, 
  partly 
  crystalline 
  ;" 
  

   he 
  found 
  that 
  it 
  lost 
  two 
  equivalents 
  of 
  water 
  on 
  drying 
  at 
  212°. 
  As 
  obtained 
  by 
  

   the 
  process 
  above 
  given, 
  it 
  is 
  in 
  the 
  form 
  of 
  square 
  prismatic 
  crystals, 
  white 
  and 
  

   of 
  great 
  brilliancy, 
  presenting 
  when 
  in 
  mass 
  a 
  beautiful 
  appearance. 
  It 
  is 
  very 
  

   soluble 
  in 
  boiling 
  water, 
  very 
  little 
  soluble 
  in 
  alcohol. 
  It 
  has 
  a 
  strong 
  acid 
  re- 
  

   action, 
  and 
  is 
  deposited 
  even 
  from 
  a 
  solution 
  of 
  the 
  acid 
  in 
  an 
  excess 
  of 
  hot 
  caustic 
  

   ammonia, 
  if 
  the 
  boiling 
  has 
  not 
  been 
  continued. 
  It 
  is 
  represented 
  by 
  the 
  formula 
  

  

  NH 
  4 
  0, 
  HO, 
  C 
  12 
  H 
  2 
  8 
  + 
  2 
  aq. 
  

  

  My 
  own 
  analyses 
  agree 
  with 
  this, 
  which 
  is 
  the 
  result 
  of 
  the 
  analyses 
  of 
  Dr 
  

   Stenhouse 
  ; 
  but 
  a 
  salt 
  containing 
  an 
  additional 
  single 
  atom 
  of 
  water 
  is 
  obtained 
  

   when 
  strong 
  alcohol 
  is 
  added 
  to 
  cold 
  saturated 
  alkaline 
  solution 
  of 
  comenic 
  acid 
  

   in 
  ammonia. 
  It 
  falls 
  in 
  groups 
  of 
  radiated 
  prisms. 
  

  

  j" 
  5-193 
  grains 
  of 
  the 
  air-dried 
  salt 
  lost 
  at 
  212° 
  Fahr. 
  

   \ 
  0-713 
  ... 
  water. 
  

  

  The 
  per-centage 
  calculated 
  from 
  the 
  number 
  is 
  13-73, 
  while 
  13*50 
  is 
  that 
  corre- 
  

   sponding 
  to 
  the 
  formula 
  

  

  NH 
  4 
  0, 
  HO, 
  C 
  12 
  H 
  2 
  8 
  + 
  3 
  aq. 
  

  

  Bicomenate 
  of 
  ammonia, 
  in 
  the 
  dry 
  state, 
  sustains 
  a 
  temperature 
  of 
  350 
  Fahr. 
  

   without 
  decomposition 
  or 
  loss 
  of 
  weight. 
  When 
  heated 
  to 
  390° 
  Fahr. 
  in 
  a 
  closed 
  

   tube, 
  it 
  blackens 
  and 
  fuses, 
  and 
  on 
  examination 
  it 
  is 
  found 
  to 
  have 
  undergone 
  a 
  

   change, 
  an 
  acid 
  substance 
  being 
  produced, 
  which 
  I 
  shall 
  describe 
  fully 
  hereafter. 
  

  

  Bicomenate 
  of 
  Potass. 
  

  

  When 
  comenic 
  acid 
  is 
  boiled 
  with 
  a 
  slight 
  excess 
  of 
  caustic 
  potass, 
  it 
  dissolves 
  

   readily, 
  and 
  the 
  fluid 
  on 
  cooling 
  deposits 
  a 
  salt, 
  which, 
  when 
  washed 
  with 
  cold 
  

   water, 
  and 
  subsequently 
  recrystallized 
  from 
  the 
  same 
  menstruum 
  boiling, 
  presents 
  

   itself 
  in 
  groups 
  of 
  short, 
  square, 
  prismatic 
  needles. 
  They 
  are 
  not 
  very 
  readily 
  

   deprived 
  entirely 
  of 
  colour. 
  They 
  have 
  a 
  strongly 
  acid 
  reaction, 
  and 
  are 
  the 
  an- 
  

   hydrous 
  bicomenate 
  of 
  potass. 
  They 
  gave 
  the 
  following 
  results 
  on 
  analysis 
  ; 
  the 
  

   potass 
  was 
  determined 
  by 
  ignition 
  with 
  a 
  few 
  drops 
  of 
  strong 
  sulphuric 
  acid. 
  

  

  {6-250 
  grains 
  air-dry 
  salt 
  gave 
  

   8-497 
  ... 
  carbonic 
  acid, 
  and 
  

   0-987 
  ... 
  water. 
  

  

  f 
  5-291 
  grains 
  gave 
  

  

  \ 
  2-335 
  ... 
  sulphate 
  of 
  potass. 
  

  

  

  Experiment. 
  

  

  37-07 
  

   1-75 
  

  

  23-88 
  

  

  

  Calculation. 
  

  

  

  Carbon, 
  

   Hydrogen, 
  

   Oxygen, 
  

   Potass, 
  

  

  37-07 
  

  

  1-54 
  

  

  37-09 
  

  

  24-30 
  

  

  c 
  12 
  

  

  Ko 
  

  

  72 
  

   3 
  

   72 
  

   47-2 
  

  

  The 
  formula 
  of 
  the 
  above 
  salt 
  

  

  100-00 
  

  

  is 
  therefore 
  

   KO, 
  HO, 
  C 
  12 
  

  

  100-00 
  

   H 
  2 
  8 
  . 
  

  

  194-2 
  

  

  