198       The  Reaction  of  Atropine  with  Mercurous  Salts.  {AmAprif  S™1, 
THE  REACTION  OF  ATROPINE  WITH  MERCUROUS 
SALTS. 
By  Alfred  W.  Gerhard,  F.C.S. 
The  Pharmaceutical  Journal  of  January  16  (see  Amer.  Jour. 
Phaem.,  1886,  p.  129),  contains  a  communication  by  Professor 
Fliickiger  which  confirms  a  previous  observation  of  mine  that  atropine 
and  other  mydriatic  alkaloids  throw  out  mercuric  oxide  from  mercuric 
chloride.  In  the  same  communication  Professor  Fliickiger  also  states 
"mercurous  chloride,  however,  is  not  blackened  by  atropine;"  this 
being  contrary  to  fact  I  have  placed  on  record  the  experiments  on 
which  my  assertion  is  based. 
When  pure  atropine  in  powder  is  shaken  with  mercurous  chloride 
and  cold  water  no  reaction  is  apparent,  but  as  soon  as  the  mixture  is 
warmed  the  white  mercurous  salt  becomes  almost  black.  The  devel- 
opment of  the  reaction  is  physically  aided  by  adding  to  the  mixture 
one-fourth  its  volume  of  alcohol,  which  by  its  solvent  action  on  the 
atropine  promotes  contact  with  the  mercurous  salt.  I  find  that  when 
atropine  is  added  to  a  soluble  mercurous  salt,  as  the  nitrate  or  acetate, 
the  black  precipitate  is  immediately  formed  in  the  cold. 
Being  uncertain  as  to  the  exact  nature  of  the  decompositions,  I 
made  the  following  experiments  to  determine  this  point : — 
First  Experiment — 0*471  gm.  of  mercurous  chloride,  and  1*156 
gms.  of  atropine  were  weighed,  the  atropine  being,  from  a  cal- 
culation, double  the  molecular  quantity  required  to  convert  the 
mercurous  chloride  into  its  oxide.  The  atropine  was  dissolved 
in  a  mixture  of  5  volumes  water  and  3  volumes  alcohol,  the 
mercurous  salt  was  added  and  the  mixture  warmed  and  shaken 
for  some  minutes;  the  black  powder  which  formed  was  trans- 
ferred to  a  weighed  filter,  then  well  washed  with  alcohol  and  water, 
and  dried  over  sulphuric  acid;  the  precipitate  weighed  0*452  gm. 
This  was  evidence  that  the  powder  was  not  mercurous  oxide  alone,  or 
its  weight  would  have  approximated  to  0*416  gm.  Suspecting  the 
powder  to  contain  either  atropine,  or  unchanged  mercurous  chloride, 
it  was  divided  into  two  parts  and  examined  as  follows : — The  first 
part  was  treated  with  nitric  acid,  which  dissolved  the  black  powder, 
but  left  a  white  insoluble  residue  containing  chlorine  and  mercury. 
The  second  portion  of  the  powder,  to  test  it  for  atropine,  was  shaken 
with  potassium  hydrate  and  ether;  the  ether  when  decanted  and  eva- 
