﻿PRODUCTS 
  OF 
  DECOMPOSITION 
  OF 
  COMENIC 
  ACID. 
  241 
  

  

  dried, 
  but 
  soon 
  commence 
  to 
  lose 
  ammonia 
  in 
  a 
  dry 
  atmosphere. 
  A 
  portion 
  of 
  

   the 
  substance 
  which 
  had 
  been 
  exposed 
  one 
  night 
  was 
  placed 
  in 
  ^acuo 
  over 
  sul- 
  

   phuric 
  acid 
  ; 
  it 
  was 
  found 
  to 
  lose 
  less 
  weight 
  by 
  about 
  half 
  a 
  per 
  cent, 
  than 
  would 
  

   correspond 
  to 
  the 
  ammonia 
  in 
  a 
  salt 
  of 
  the 
  composition. 
  

  

  NH 
  4 
  0, 
  C 
  4 
  H 
  5 
  O, 
  C 
  12 
  H 
  2 
  8 
  . 
  

   As 
  the 
  residue 
  was 
  found 
  to 
  consist 
  of 
  pure 
  comenovinic 
  acid, 
  there 
  can 
  be 
  little 
  

   doubt 
  that 
  the 
  above 
  is 
  a 
  true 
  ammonia 
  salt. 
  

  

  Its 
  other 
  salts, 
  with 
  the 
  alkalies 
  and 
  alkaline 
  earths, 
  are 
  very 
  soluble. 
  Its 
  

   silver 
  salt 
  is 
  gelatinous, 
  and 
  rapidly 
  decomposable 
  even 
  in 
  the 
  dark. 
  

  

  Decomposition 
  of 
  Comenate 
  of 
  Ammonia. 
  

  

  Comenamic 
  Acid. 
  — 
  I 
  mentioned, 
  in 
  a 
  former 
  part 
  of 
  this 
  paper, 
  that 
  bicomenate 
  

   of 
  ammonia 
  is 
  decomposed, 
  when 
  subjected 
  to 
  a 
  temperature 
  of 
  390° 
  Fahr. 
  in 
  a 
  

   sealed 
  tube. 
  The 
  contents 
  of 
  the 
  tube 
  were 
  a 
  black 
  coaly 
  mass, 
  which 
  partially 
  

   dissolved 
  in 
  boiling 
  water. 
  The 
  filtered 
  solution 
  gave, 
  with 
  hydrochloric 
  acid, 
  a 
  

   white 
  scaly 
  precipitate, 
  separating 
  on 
  cooling. 
  I 
  did 
  not 
  endeavour 
  to 
  procure 
  

   more 
  of 
  this 
  substance 
  in 
  this 
  manner, 
  as 
  I 
  considered 
  it 
  to 
  be 
  the 
  comenamic 
  

   acid, 
  which 
  a 
  more 
  convenient 
  process 
  enabled 
  me 
  to 
  obtain 
  in 
  sufficient 
  quantity. 
  

  

  When 
  a 
  solution 
  of 
  comenate 
  of 
  ammonia, 
  containing 
  an 
  excess 
  of 
  the 
  alkali, 
  

   is 
  boiled, 
  it 
  soon 
  becomes 
  coloured, 
  and 
  after 
  some 
  little 
  time 
  a 
  black-red 
  fluid 
  is 
  

   obtained 
  ; 
  if 
  the 
  boiling 
  be 
  continued 
  till 
  the 
  whole 
  or 
  the 
  greater 
  part 
  of 
  the 
  

   excess 
  of 
  ammonia 
  is 
  expelled, 
  and 
  the 
  fluid 
  be 
  then 
  allowed 
  to 
  cool, 
  a 
  grey 
  sedi- 
  

   ment 
  falls 
  to 
  the 
  bottom 
  of 
  the 
  vessel. 
  This, 
  when 
  thrown 
  upon 
  a 
  filter, 
  is 
  found 
  

   to 
  have 
  a 
  most 
  peculiar, 
  clayey, 
  tenacious 
  character 
  ; 
  it 
  is 
  the 
  ammonia 
  salt 
  of 
  co- 
  

   menamic 
  acid, 
  very 
  impure, 
  from 
  adhering 
  colouring 
  matter. 
  It 
  dissolves, 
  though 
  

   spariDgly, 
  in 
  boiling 
  water 
  ; 
  and 
  hydrochloric 
  acid 
  added 
  in 
  just 
  sufficient 
  quan- 
  

   tity 
  to 
  decompose 
  it, 
  precipitates 
  very 
  dark 
  bronze-coloured 
  scales 
  of 
  comenamic 
  

   acid, 
  which 
  separate 
  completely 
  when 
  the 
  liquid 
  cools. 
  Excess 
  of 
  hydrochloric 
  

   acid 
  is 
  to 
  be 
  avoided, 
  as 
  the 
  new 
  acid 
  is 
  extremely 
  soluble 
  in 
  this 
  reagent. 
  The 
  

   dark 
  crystals 
  are 
  readily 
  deprived 
  of 
  their 
  colour 
  by 
  two 
  or 
  three 
  crystallizations 
  

   from 
  boiling 
  water, 
  and 
  very 
  easily 
  by 
  the 
  aid 
  of 
  animal 
  charcoal, 
  which 
  must, 
  

   however, 
  for 
  this 
  purpose 
  be 
  entirely 
  free 
  from 
  iron, 
  as 
  the 
  least 
  quantity 
  of 
  this 
  

   substance 
  imparts 
  a 
  purple 
  colour 
  to 
  solutions 
  containing 
  the 
  acid. 
  

  

  When 
  pure, 
  comenamic 
  acid 
  presents 
  itself 
  in 
  the 
  form 
  of 
  brilliant 
  colourless 
  

   plates, 
  the 
  following 
  is 
  its 
  analysis 
  : 
  — 
  

  

  {5-540 
  grains 
  dried 
  at 
  212° 
  gave 
  

   9-345 
  ... 
  carbonic 
  acid, 
  and 
  

   1-685 
  ... 
  water. 
  

  

  ! 
  5-585 
  grains 
  dried 
  at 
  212° 
  gave 
  

   9-487 
  ... 
  carbonic 
  acid, 
  and 
  

   1-715 
  ... 
  water. 
  

  

  {6-505 
  grains 
  dried 
  at 
  212° 
  gave 
  

   9-500 
  ... 
  platinum 
  salt 
  of 
  ammonia. 
  

  

  VOL. 
  XX. 
  PART 
  II. 
  3 
  T 
  

  

  