﻿PRODUCTS 
  OF 
  DECOMPOSITION 
  OF 
  COMENIC 
  ACID. 
  235 
  

  

  gas 
  be 
  passed 
  through 
  it 
  for 
  some 
  time, 
  the 
  whole 
  of 
  the 
  colour 
  disappears, 
  or 
  the 
  

   liquid 
  only 
  retains 
  the 
  faint 
  yellowish-green 
  characteristic 
  of 
  an 
  aqueous 
  solution 
  

   of 
  chlorine, 
  without 
  the 
  formation 
  of 
  an 
  immediate 
  precipitate. 
  After 
  the 
  lapse 
  

   of 
  some 
  hours, 
  groups 
  of 
  long, 
  colourless, 
  prismatic 
  needles 
  are 
  deposited, 
  the 
  

   quantity 
  of 
  which 
  is 
  increased 
  by 
  the 
  addition 
  of 
  hydrochloric 
  acid. 
  The 
  mother 
  

   liquor, 
  on 
  gentle 
  evaporation, 
  gradually 
  acquires 
  a 
  brownish 
  shade 
  of 
  colour, 
  

   which 
  passes 
  ultimately 
  into 
  a 
  very 
  dark 
  brown, 
  and 
  there 
  deposited 
  a 
  further 
  

   quantity 
  of 
  the 
  new 
  acid 
  in 
  prismatic 
  crystals, 
  separate 
  and 
  in 
  groups, 
  of 
  a 
  brown, 
  

   nearly 
  black, 
  lustrous 
  appearance. 
  In 
  this 
  second 
  mother 
  liquor, 
  in 
  addition 
  to 
  

   the 
  colouring 
  matter, 
  oxalic 
  acid 
  is 
  to 
  be 
  detected. 
  The 
  colourless 
  crystals 
  at 
  first 
  

   obtained, 
  after 
  washing 
  with 
  cold 
  water, 
  were 
  recrystallized 
  from 
  boiling 
  water, 
  in 
  

   which 
  they 
  are 
  readily 
  soluble 
  : 
  they 
  acquired, 
  in 
  this 
  process, 
  a 
  slight 
  shade 
  of 
  

   yellow, 
  and 
  presented 
  themselves 
  in 
  the 
  form 
  of 
  short, 
  thick, 
  square 
  prisms. 
  

   They 
  gave 
  the 
  following 
  results 
  on 
  analysis 
  : 
  — 
  ■ 
  

  

  f 
  5-240 
  

   { 
  7-210 
  

   ^ 
  0-847 
  

  

  f 
  3-877 
  

  

  { 
  2-940 
  

  

  grains 
  dried 
  at 
  212° 
  

   carbonic 
  acid, 
  

   water. 
  

  

  grains 
  dried 
  at 
  212° 
  

   chloride 
  of 
  si' 
  

  

  Experiment. 
  

  

  37-53 
  

  

  1-79 
  

  

  ' 
  18-77 
  

  

  Fahr. 
  gave 
  

   and 
  

  

  Fahr. 
  gave, 
  after 
  burning 
  v 
  

   ver. 
  

  

  Calculation. 
  

  

  Carbon, 
  

   Hydrogen, 
  

   Oxygen, 
  . 
  

   Chlorine, 
  . 
  

  

  37-79 
  

  

  1-57 
  

  

  42-01 
  

  

  18-63 
  

  

  C 
  l2 
  72 
  

   H 
  3 
  3 
  

   O 
  10 
  80 
  

   CI 
  35-5 
  

  

  100-00 
  100-00 
  190-5 
  

  

  The 
  above 
  shews 
  this 
  substance 
  to 
  be 
  an 
  acid, 
  obtained 
  by 
  the 
  substitution 
  of 
  

   an 
  equivalent 
  of 
  hydrogen 
  in 
  comenic 
  acid, 
  by 
  an 
  equivalent 
  of 
  chlorine, 
  accord- 
  

   ing 
  to 
  the 
  following 
  equation 
  : 
  — 
  

  

  2 
  HO, 
  C 
  12 
  H 
  2 
  8 
  + 
  2 
  CI 
  = 
  2 
  HO, 
  C 
  12 
  { 
  q 
  ] 
  °s 
  + 
  HCI 
  - 
  

  

  It 
  crystallizes 
  with 
  three 
  equivalents 
  of 
  water, 
  which 
  are 
  readily 
  expelled 
  at 
  212° 
  

   Fahr., 
  as 
  the 
  following 
  experiment 
  proves 
  : 
  — 
  

  

  J 
  10-528 
  grains 
  air-dried 
  substance 
  lost 
  at 
  212° 
  Fahr. 
  

   { 
  1-313 
  ... 
  water, 
  

  

  giving 
  for 
  per-centage 
  1247, 
  the 
  number 
  12*41 
  being 
  that 
  corresponding 
  to 
  the 
  

   formula 
  

  

  2HO, 
  C 
  12 
  {^ 
  }0 
  8 
  + 
  3aq. 
  

  

  This 
  acid, 
  as 
  before 
  mentioned, 
  is 
  readily 
  soluble 
  in 
  hot 
  water, 
  less 
  so 
  in 
  cold, 
  

   but 
  under 
  both 
  circumstances 
  its 
  solubility 
  is 
  much 
  greater 
  than 
  that 
  of 
  the 
  parent 
  

   acid 
  ; 
  it 
  is 
  very 
  soluble 
  in 
  alcohol 
  when 
  warm. 
  It 
  imparts 
  to 
  persalts 
  of 
  iron 
  the 
  

   same 
  deep 
  red 
  colour 
  as 
  meconic 
  and 
  comenic 
  acids. 
  When 
  a 
  piece 
  of 
  granulated 
  

   zinc 
  is 
  placed 
  in 
  its 
  aqueous 
  solution, 
  hydrogen 
  is 
  slowly 
  evolved, 
  and 
  both 
  zinc 
  

  

  