500 
Titration  of  Ammonium  Carbonate. 
Am.  Jour.  Pharm. 
Oct.,  1889. 
From  Acetyl-a-naphthylethyl  ether. — The  carbon  acid  had  also  been 
prepared  by  Gattermann  &  Hess  (I.  c.) 
From  Acetyl- ft-naphthylethy i  ether. — The  glyoxylic  acid  melts  at  131- 
136°C.  under  decomposition.  The  corresponding  carbon  acid  could 
not  be  obtained. 
A  NOTE  ON  THE  TITRATION  OF  AMMONIUM 
CARBONATE. 
By  George  M.  Beringer,  Ph.  G. 
The  U.  S.  Pharmacopoeia  states  that  uTo  neutralize  2.616  gm.  of 
Carbonate  of  Ammonium  should  require  50  cc.  of  the  volumetric  so- 
lution of  oxalic  acid."  In  the  Digest  of  Criticisms  on  the  U.  S. 
Pharmacopoeia,  page  26,  occurs  the  following  statement:  "In  the  vol- 
umetric test  an  error  has  crept  in,  50  cc.  of  the  oxalic  acid  solution 
require  1 2*95'  Gm.  of  the  salt  (Nat.  Disp.  178).  According  to  Squibb, 
2'616  gm.  require  between  39  and  40°Cc.  of  the  acid  solution 
(Ephemeris  698)." 
Having  occasion  recently  to  examine  a  number  of  samples  of  com- 
mercial carbonate  of  ammonium,  my  attention  was  attracted  by  the 
discrepancy  of  these  statements. 
The  Pharmacopoeia  states  the  formula  of  ammonium  carbonate  as 
NH4HC03NH4NH2C02.  This  formula,  based  upon  the  classical  re- 
searches of  Edward  Divers,  M.  D.,  the  combinations  of  carbonic 
anhydride  with  ammonia  and  water  (Journ.  London  Chem.  Soc, 
1870,  page  171),  considers  the  commercial  carbonate  as  a  mixture  of 
one  molecule  each  of  acid  carbonate  and  carbamate,  and  is,  I  believe, 
the  formula  recognized  by  all  the  more  recent  text-books.  Upon  dis- 
solving this  salt  in  water,  the  carbamate  is  changed  to  normal  carbo- 
nate ;  the  reaction  being  represented  by  the  equation 
(NH4)HCO3(NH4)NH2CO2+H2O=(NH4)HCO3(NH4)2C03. 
Neutralizing  this  by  oxalic  acid  as  in  the  officinal  volumetric  test,  the 
reaction  would  be  represented  by  the  equation 
2(NH4HC03(NH4)2CH3)+3H2C2042H20=3(NH4)2 
C2O4+4CO2+10H2O, 
or  accepting  the  officinal  formula  and  molecular  weight  (157),  and  cal- 
culating the  weights,  378  grms.  of  oxalic  requires  314  grms.  of 
carbonate  of  ammonium  for  saturation.    Consequently  3*15  grm. 
oxalic  acid,  the  amount  contained  in  50  cc.  of  the  normal  oxalic  solu- 
