T1NCTURA  CINCHONJE  FERRATA. 
295 
whose  intention  was  to  have  a  Tincture  of  Cinchona  combined 
with  iron,  in  such  a  form  that  it  should  not  make  a  black,  inky 
mixture.  This  object  was  proposed  to  be  obtained  by  dissolving 
the  ammonio-citrate  of  iron  in  the  compound  tincture  of  cinchona, 
previously  deprived  of  its  tannin  by  means  of  gelatin.  Accord- 
ingly, a  strong  solution  of  gelatin  was  added  to  the  ordinary  Hux- 
ham's tincture,  which  had  the  effect  of  producing  a  copious  pre- 
cipitate, and  as  long  as  a  precipitate  appeared  gelatin  was  added. 
The  tincture  thus  prepared,  possessed  the  taste  and  smell  of  the 
original  tincture,  though  considerably  diluted,  but  was  of  a  much 
lighter  color,  being  very  nearly  the  tint  of  sherry  wine;  on  adding 
eight  grains  of  the  ammonio-citrate  of  iron  to  four  ounces  of  this, 
there  was  still  a  precipitate  made,  showing  either  that  gelatin 
would  not  remove  AJ1  the  tannin,  or  that  the  tincture  contained 
some  other  precipitant  of  iron.  This  preparation  was  set  aside  as 
ineligible. 
A  tincture  was  then  prepared  by  dissolving  eight  grains  of  the 
salt  in  four  ounces  of  Huxham's  tincture  and  filtering  ;  this  gave 
a  handsome  looking  preparation,  rather  darker  than  Huxham's 
tincture,  and  was  prescribed  extensively. 
Suspecting,  from  the  amount  of  precipitate  made  by  the  addition 
of  the  iron,  that  a  considerable  part  of  the  iron  was  separated,  the 
following  experiments  were  instituted  :  The  precipitate  made  by 
dissolving  16  grs.  of  the  ammonio-citrate  of  iron  in  8  oz.  of  Hux- 
ham's tincture,  was  separated  by  filtration  and  ignited,  so  as  to 
destroy  the  vegetable  matter ;  it  was  then  dissolved  in  che- 
mically pure  hydrochloric  acid,  to  which  a  little  nitric  acid  was 
added  ;  the  solution  thus  obtained  was  diluted  and  filtered,  the  fil- 
ter being  well  washed  with  pure  water.  Ammonia  was  then  added 
in  excess,  and  the  precipitate  thus  obtained  being  carefully  washed 
and  dried  at  a  heat  of  212°,  (to  which  heat  all  the  filters  used  in 
weighing  were  subjected  before  being  counterpoised,)  was  found 
to  weigh  3.8  grains. 
16  grains  of  ammonio-citrate  of  iron  were  then  ignited  and 
treated  as  in  the  preceding  experiment;  the  amount  of  sesquioxide 
of  iron  thus  obtained  was  just  six  grains.  From  a  comparison  of 
these  results  it  was  found,  that  of  the  16  grs.  originally  dissolved, 
there  remained  in  the  precipitate  10.13  grains. 
An  experiment  was  then  tried  with  the  clear  tincture  obtained 
