THE 
AMERICAN  JOURNAL  OF  PHARMACY, 
JULY,  1857. 
TINCTURA  FERRI  CHLORIDX. 
By  Edward  R.  Squibb,  M.  D.,  U.  S.  Navy. 
Assistant  Director  U.  S.  Naval  Laboratory,  New  York. 
Careful  pharmaceutists  very  often  meet  with  difficulty  in 
making  this  preparation  in  accordance  with  the  officinal  (U.  S.  P.) 
formula,  whilst  those  less  careful  obtain  a  preparation  very  defi- 
cient in  the  iron,  but  containing  an  excess  of  hydrochloric  acid. 
Freshly  made  subcarbonate  of  iron,  if  dried  at  a  temperature 
below  100°  F.,  will  almost  always  dissolve  in  the  prescribed  pro- 
portion of  acid.  If,  however,  the  subcarbonate  be  not  recently 
made,  or  if  it  be  washed  often  with  hot  water  in  the  preparation, 
even  though  dried  "  with  a  gentle  heat,"  a  notable  proportion  of 
it  will  resist  the  action  of  the  acid.  The  common  faults  in  its 
preparation  are  the  washing  with  "  hot  water,"  and  drying  at  a 
temperature  above  the  prescribed  «  gentle  heat." 
The  preparation  of  a  soluble  subcarbonate  has  been  more  uni- 
formly successfully  accomplished  in  the  writer's  hands  by  precipi- 
tating from  warm,  not  hot  solutions,  washing  the  precipitate 
with  cold  water,  by  decantation,  and  drying  at  a  «  gentle  heat," 
or  below  it.  In  practice  with  all  preparations  of  sesquioxide 
of  iron  the  writer's  observations  are  entirely  in  accordance 
with  the  recent  experiments  and  researches  of  M.  P£an  de  Saint 
Gilles,  (Ann.  de  Chem.  et  de  Phys.  1856.  Vol.  xlvi.  p.  47,  et 
seq.)  wherein  he  concludes  "that  the  action  of  heat  upon 
hydrated  sesquioxide  of  iron  determines  first  a  partial  elimination 
of  water  ;  then,  when  the  action  is  prolonged,  it  destroys  little  by 
little  the  basic  affinities  of  the  oxide  and  produces  a  true  allotropic 
transformation." 
In  the  preparation  of  the  tincture  of  the  chloride  from  a  solu- 
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