﻿240 
  MR 
  HENRY 
  HOW 
  ON 
  CERTAIN 
  SALTS 
  AND 
  

  

  dryness, 
  at 
  a 
  heat 
  somewhat 
  below 
  212 
  , 
  a 
  crystalline 
  residue 
  remained, 
  which 
  was 
  

   evidently 
  not 
  comenic 
  acid. 
  This 
  was 
  kept 
  at 
  the 
  same 
  heat 
  till 
  it 
  ceased 
  to 
  smell 
  

   of 
  hydrochloric 
  acid 
  ; 
  it 
  was 
  then 
  dissolved 
  in 
  water 
  under 
  the 
  boiling 
  point 
  ; 
  the 
  

   fluid, 
  on 
  cooling, 
  deposited 
  well-defined, 
  square, 
  prismatic 
  needles 
  of 
  considerable 
  

   size. 
  A 
  portion, 
  dried 
  in 
  vacuo, 
  gave 
  the 
  following 
  results 
  on 
  analysis. 
  

  

  (5-625 
  grains, 
  dried 
  in 
  vacuo, 
  gave 
  

   10-740 
  ... 
  carbonic 
  acid, 
  and 
  

   2-280 
  ... 
  water. 
  

  

  {4-110 
  grains, 
  dried 
  in 
  vacuo, 
  gave 
  

   7-865 
  ... 
  carbonic 
  acid, 
  and 
  

   1-715 
  ... 
  water. 
  

  

  Calculation. 
  

  

  

  I. 
  

  

  II. 
  

  

  

  

  

  Carbon, 
  . 
  

  

  52-07 
  

  

  52-18 
  

  

  52-17 
  

  

  C 
  !6 
  

  

  96 
  

  

  Hydrogen, 
  

  

  4-50 
  

  

  4-63 
  

  

  4-34 
  

  

  H 
  R 
  

  

  8 
  

  

  Oxygen, 
  . 
  

  

  . 
  

  

  

  43-49 
  

  

  o 
  10 
  

  

  80 
  

  

  100-00 
  100-00 
  100-00 
  184 
  

  

  From 
  which 
  it 
  will 
  be 
  seen 
  that 
  this 
  substance 
  has 
  the 
  composition 
  of 
  an 
  acid 
  

   ether, 
  or 
  true 
  vinic 
  acid, 
  and 
  is 
  represented 
  by 
  the 
  formula 
  

  

  HO, 
  C 
  4 
  H 
  5 
  O 
  C 
  12 
  H 
  2 
  8 
  , 
  

  

  and 
  I 
  shall 
  presently 
  shew, 
  that 
  the 
  atom 
  of 
  water 
  is 
  capable 
  of 
  being 
  replaced 
  

   by 
  bases. 
  The 
  acid 
  crystallizes, 
  like 
  the 
  corresponding 
  compound 
  of 
  tartaric 
  

   acid, 
  without 
  water. 
  

  

  Comenovinic 
  acid 
  is 
  readily 
  soluble 
  in 
  hot 
  water, 
  and 
  may 
  be 
  boiled 
  a 
  short 
  

   time 
  without 
  undergoing 
  decomposition 
  ; 
  but 
  if 
  long 
  kept 
  at 
  this 
  temperature, 
  

   comenic 
  acid 
  is 
  reproduced. 
  It 
  is 
  extremely 
  soluble 
  in 
  alcohol. 
  It 
  commences 
  

   to 
  volatilize, 
  when 
  kept 
  in 
  the 
  dry 
  state, 
  at 
  212 
  ; 
  it 
  fuses 
  at 
  275° 
  Fahr. 
  into 
  a 
  

   transparent 
  brownish 
  liquid, 
  which 
  becomes, 
  on 
  cooling, 
  a 
  crystalline 
  striated 
  

   mass. 
  When 
  kept 
  at 
  about 
  its 
  fusing 
  point, 
  it 
  sublimes, 
  unaltered 
  in 
  composi- 
  

   tion, 
  in 
  brilliant, 
  long, 
  flattened 
  prisms, 
  of 
  great 
  beauty; 
  the 
  second 
  analysis 
  above 
  

   given 
  is 
  that 
  of 
  the 
  sublimed 
  product. 
  It 
  gives 
  a 
  strongly 
  acid 
  reaction 
  with 
  test- 
  

   papers 
  ; 
  its 
  aqueous 
  solution 
  readily 
  coagulates 
  the 
  white 
  of 
  eggs 
  ; 
  it 
  imparts 
  to 
  

   persalts 
  of 
  iron 
  a 
  deep 
  red 
  colour. 
  

  

  Though 
  of 
  so 
  stable 
  a 
  nature 
  per 
  se, 
  this 
  substance 
  rapidly 
  decomposes 
  in 
  

   contact 
  with 
  fixed 
  bases 
  ; 
  so 
  that 
  I 
  have 
  been 
  unable 
  to 
  obtain 
  any 
  of 
  its 
  salts 
  in 
  

   the 
  dry 
  state. 
  All 
  those 
  I 
  have 
  attempted 
  to 
  prepare 
  gave, 
  upon 
  analysis, 
  results 
  

   closely 
  agreeing 
  with 
  the 
  composition 
  of 
  salts 
  of 
  comenic 
  acid, 
  with 
  which 
  their 
  

   general 
  properties 
  were 
  also 
  identical, 
  notwithstanding 
  that 
  I 
  carefully 
  avoided 
  

   application 
  of 
  heat. 
  

  

  I 
  obtained 
  a 
  salt 
  of 
  ammonia 
  by 
  passing 
  the 
  dry 
  gas 
  into 
  a 
  solution 
  of 
  the 
  acid 
  

   in 
  absolute 
  alcohol. 
  Under 
  these 
  circumstances 
  a 
  precipitate 
  soon 
  forms, 
  in 
  small 
  

   silky 
  tufts 
  of 
  a 
  yellow 
  colour. 
  They 
  preserve 
  their 
  silky 
  appearance 
  on 
  being 
  

  

  