Am.  Jour.  Pharm. 
April,  1887. 
Acid  Morphine  Meconate, 
189 
the  same  function.  In  the  case  of  an  organic  oxyacid  such  as  meconic 
this  infers  the  presence  of  three  carboxyl  radicals  in  the  molecule.  By 
the  researches  of  Dittmar  and  Dewar,3  Mennel,4  Hilsebein,5  and 
others,  it  is  now  established  that  meconic  acid  is  only  dibasic  though 
triatomic.  In  other  words,  while  it  contains  three  hydroxyl  radicals 
it  only  contains  two  carboxyls.  Whence  it  appears  that  the  existence 
of  two  morphine  meconates  is  theoretically  possible.  The  normal  or 
neutral  meconate  has  been  described  as  above  referred  to,  and  it  now 
remains  to  consider  whether  there  is  sufficient  evidence  to  prove  the 
existence  of  an  acid  meconate  of  morphine. 
In  the  identification  of  a  substance,  there  is  no  property  of  so  much 
importance  as  crystalline  form.  If  a  salt  having  the  composition  of 
acid  morphine  meconate,  and  possessing  a  particular  crystalline  form- 
ation, could  be  prepared,  the  evidence  for  the  existence  of  the  acid 
meconate  would  be  complete.  No  such  salt,  however,  has  been  pre- 
pared, and  we  have  therefore  to  rely  entirely  on  less  satisfactory  and 
perhaps  merely  negative  evidence. 
As  it  is  an  almost  invariable,  if  not  quite  invariable,  rule,  that  the 
neutral  and  acid  salts  of  a  base  differ  widely  in  their  solubility  in  a 
given  menstruum ;  it  seemed  likely  that  light  would  be  thrown  on 
the  subject  under  discussion  by  the  following  experiments  : — A  satu- 
rated solution  in  water  of  neutral  morphine  meconate  was  prepared  at 
the  ordinary  temperature,  and  then  divided  into  two  portions  of  50 
cc.  introduced  into  separate  flasks.  To  one  (a)  0*2  gram  of  morphine 
meconate  was  added,  which  after  diligent  shaking  did  not  perceptibly 
diminish  in  bulk,  showing  the  solution  to  be  saturated.  03  gram  of 
meconic  acid  was  then  added,  and  the  solution  well  shaken.  The  salt 
did  not  disappear,  and  even  after  the  lapse  of  twelve  hours,  and  with 
frequent  agitation,  there  was  no  appreciable  diminution  in  the  bulk  of 
the  salt.  To  the  other  flask  (6),  0*2  gram  of  meconic  acid  was  added. 
On  standing  several  hours  with  occasional  shaking,  the  acid  was 
slowly  dissolved.  Now,  if  acid  morphine  meconate  were  more  solu- 
ble than  the  normal  salt  the  meconate  added  to  (a)  ought  to  have  dis- 
solved ;  while  if  less  soluble  than  the  normal  salt  the  acid  added  to 
(b)  should  have  caused  a  precipitation.    These  experiments,  therefore, 
3 '  Proc.  E.  S.  E., '  1869, 129. 
4  Journ.pr.  Chem.,  [2],  xxvi.,  449. 
6  Ibid.,  [2],  xxxii.,  129. 
