300 
TINCTURE  OF  CHLORIDE  OF  IRON. 
I  have  found  from  experiment  with  two  samples  of  subcarbonate 
of  iron  made  by  different  manufacturers,  that  it  loses  20  per  cent, 
in  weight  upon  being  carefully  heated  to  redness  ;  and  the  residue 
is  nearly  pure,  dry  sesquioxide.  Three  drachms  of  this  oxide 
were  mixed  with  one  fluid  ounce  of  muriatic  acid  of  the  sp.  gr. 
1.16,  digested  at  a  moderate  heat,  on  a  sand  bath,  filtered,  when 
cold,  (through  a  paper  which  had  been  previously  weighed,)  and 
washed  with  three  fluid  ounces  of  alcohol.  The  resulting  tincture 
was  of  a  reddish  brown  color,  without  a  trace  of  protochloride, 
and  contains,  theoretically,  34  grains  of  sesquioxide  to  the  fluid 
ounce  ;  or  rather  yields  that  quantity  upon  precipitation  with 
ammonia.  The  residue  on  the  filter  having  been  carefully  dried 
was  found  to  weigh  45  grains. 
For  preparing  tincture  of  the  sesquichloride  of  iron  with  ordi- 
nary muriatic  acid,  without  reference  to  the  strength  of  the  acid 
employed,  I  propose  the  following  formula : 
Take  of  Sesquioxide  of  Iron,  prepared  from  sub- 
carbonate,  heated  to  redness,  6  oz.  Troy. 
"  Muriatic  Acid,  a  sufficient  quantity. 
"  Alcohol,  3  pints  or  a  sufficient  quantity. 
The  sesquioxide  having  been  placed  in  a  flask  or  other  convenient 
vessel,  one  pint  of  the  acid  is  then  added,  and  the  whole  left  for 
five  or  six  hours,  during  which  interval  it  must  be  occasionally 
stirred  or  shaken.  It  is  then  gently  heated  by  a  sand  bath, 
further  additions  of  acid  being  made  from  time  to  time  until  all 
the  oxide  has  been  dissolved.  When  the  solution  is  cool,  then 
add  a  sufficient  quantity  of  alcohol  to  make  the  whole  measure 
four  pints,  and  filter.  The  filtrate  is  a  clear  tincture,  which  con- 
tains, theoretically,  45  grains  of  sesquioxide  to  the  fluid  ounce. 
This,  I  believe  to  be  the  most  simple  and  effectual  plan  for  pre- 
paring tincture  of  the  sesquichloride,  so  as  to  insure  invariable 
strength,  maximum  therapeutic  power  and  insensibility  to  change. 
My  first  experiment  in  making  a  tincture  of  pure  sesquichlo- 
ride of  iron  was  based  upon  the  proportion  of  sesquioxide  ob- 
tained from  a  given  quantity  of  pure  crystallized  protosulphate, 
and  though  forming  a  more  elegant  and  exact  compound,  involves 
much  care  and  labor  in  the  practical  details  of  its  preparation. 
I,  however,  give  the  formula,  which  is  as  follows  : 
