﻿402 
  MR 
  HENRY 
  HOW 
  ON 
  MECONIC 
  ACID, 
  

  

  out 
  by 
  strong 
  pressure, 
  and 
  the 
  cake 
  of 
  salt 
  redissolved 
  twice 
  or 
  thrice 
  in 
  as 
  small 
  

   a 
  quantity 
  of 
  boiling 
  water 
  as 
  is 
  found 
  sufficient, 
  the 
  mother 
  liquors 
  being 
  always 
  

   pressed 
  from 
  the 
  crystallised 
  salt. 
  By 
  proceeding 
  in 
  this 
  manner 
  a 
  perfectly 
  

   white 
  salt 
  is 
  obtained, 
  from 
  whose 
  solution 
  in 
  hot 
  water 
  an 
  excess 
  of 
  strong 
  hy- 
  

   drochloric 
  acid 
  throws 
  down 
  the 
  meconic 
  acid 
  in 
  colourless 
  brilliant 
  scales 
  ; 
  these 
  

   require 
  but 
  a 
  little 
  washing 
  with 
  cold 
  water, 
  and 
  one 
  resolution 
  in 
  the 
  smallest 
  pos- 
  

   sible 
  quantity 
  of 
  hot 
  water, 
  to 
  be 
  obtained 
  on 
  cooling 
  of 
  the 
  fluid 
  absolutely 
  pure. 
  

   This 
  is 
  another 
  advantage 
  in 
  the 
  use 
  of 
  ammonia, 
  for 
  the 
  potass 
  salt 
  requires, 
  at 
  

   the 
  least, 
  three 
  treatments 
  with 
  acid 
  to 
  abstract 
  the 
  alkaline 
  base 
  entirely. 
  

  

  Bibasic 
  Meconate 
  of 
  Ammonia. 
  — 
  The 
  ammonia 
  salt 
  obtained 
  in 
  the 
  above 
  given 
  

   process, 
  crystallises 
  from 
  tolerably 
  dilute 
  fluids 
  left 
  at 
  rest, 
  in 
  groups 
  of 
  radiated 
  

   fine 
  silky 
  needles 
  : 
  they 
  have 
  an 
  acid 
  reaction. 
  In 
  the 
  following 
  analysis 
  the 
  

   nitrogen 
  was 
  determined 
  by 
  adding 
  hydrochloric 
  acid 
  to 
  a 
  solution 
  of 
  the 
  salt, 
  

   evaporating 
  the 
  filtrate 
  with 
  some 
  bichloride 
  of 
  platinum, 
  collecting 
  the 
  residue 
  

   on 
  a 
  filter, 
  and 
  washing 
  with 
  alcohol 
  and 
  ether 
  ; 
  the 
  per-centage 
  of 
  nitrogen 
  was 
  

   calculated 
  from 
  the 
  platinum 
  remaining 
  on 
  ignition 
  of 
  the 
  undissolved 
  ammonia 
  

   salt. 
  This 
  method 
  was 
  preferred 
  in 
  one 
  or 
  two 
  other 
  cases 
  of 
  ammonia 
  salts, 
  as 
  

   more 
  convenient 
  than 
  a 
  combustion 
  with 
  soda 
  lime, 
  and 
  less 
  liable 
  to 
  loss 
  ; 
  for 
  it 
  

   is 
  not 
  easy 
  always 
  to 
  mix 
  these 
  salts 
  with 
  soda 
  lime 
  so 
  quickly 
  as 
  to 
  avoid 
  the 
  

   escape 
  of 
  ammonia. 
  

  

  {5-170 
  grains, 
  dried 
  at 
  212°, 
  gave 
  

   6-732 
  ... 
  carbonic 
  acid, 
  and 
  

   2-201 
  ... 
  water. 
  

  

  {5-285 
  grains, 
  dried 
  at 
  212°, 
  gave 
  

   4-505 
  . 
  . 
  . 
  metallic 
  platinum. 
  

  

  Calculation. 
  

  

  Carbon, 
  

   Hydrogen, 
  

   Oxygen, 
  

   Nitrogen, 
  

  

  35-51 
  

   4-73 
  

  

  12-09 
  

  

  35-89 
  

  

  4-27 
  

   47-88 
  

   11-96 
  

  

  H 
  10 
  

  

  N 
  2 
  

  

  84 
  

  

  10 
  

  

  112 
  

  

  28 
  

  

  100-00 
  100-00 
  234 
  

  

  The 
  hydrogen 
  is 
  rather 
  above 
  the 
  calculated 
  result, 
  but 
  the 
  substance, 
  when 
  

   dried 
  at 
  212°, 
  is 
  extremely 
  hygroscopic 
  : 
  the 
  numbers 
  lead 
  to 
  the 
  formula 
  

  

  HO, 
  2 
  NH 
  4 
  0, 
  C 
  u 
  HO 
  n 
  

  

  as 
  representing 
  the 
  constitution 
  of 
  bimeconate 
  of 
  ammonia 
  in 
  the 
  dry 
  state 
  ; 
  the 
  

   crystals 
  appear 
  to 
  contain 
  varying 
  amounts 
  of 
  water 
  of 
  crystallisation, 
  as 
  num- 
  

   bers 
  were 
  obtained 
  in 
  drying 
  different 
  specimens 
  indicating 
  a 
  loss 
  of 
  between 
  six 
  

   and 
  sixteen 
  per 
  cent, 
  of 
  water. 
  An 
  aqueous 
  solution 
  of 
  this 
  salt 
  may 
  be 
  boiled 
  

   without 
  any 
  change 
  ; 
  but 
  when 
  kept 
  for 
  a 
  considerable 
  time 
  boiling 
  with 
  an 
  ex- 
  

   cess 
  of 
  ammonia, 
  it 
  becomes 
  altered. 
  

  

  