170 
Ferric  Multiple  Citrates. 
( Am.  Jour.  Pharm 
\      April,  1887. 
lution  of  ferric  citrate  supersaturated  with  ammonia,  on  evaporation  to 
a  syrupy  residue  will  have  parted  with  the  excess  of  base,  but  if  the 
supply  be  maintained  till  utter  dryness  two  equivalents  of  it  will  be 
retained. 
In  the  process  for  preparing  the  official  ammonio-citrate  of  iron  all 
excess  of  ammonia  above  one  equivalent,  if  present,  is  consequently 
evolved.  Hence  it  follows  that  the  official  salt  is  the  hydro-citrate  first 
mentioned.    Its  empirical  formula  is  therefore 
FeCiNH4OH 
and  its  molecular  weight  280. 
When  mixed  with  elixir  of  cinchona  it  occasions  no  precipi- 
tate. 
Owing  to  the  proneness  of  green  ferrated  elixirs  to  deteriorate  in 
color  the  writer  would  suggest  the  use  of  hydro-citrates  which  impart 
a  more  permanent  and  uniform  red-brown  tint. 
For  a  simply  ferrated  elixir  of  cinchona  the  official  ammonio-ferric 
citrate  (symbol  8)  is  readily  applicable.  When  a  phosphated  iron  is 
deemed  more  desirable  the  hydro-citrophosphate  of  symbol  5  is  sug- 
gestive. In  such  cases  where  a  green  phosphated  elixir  is  preferred 
the  compound  of  symbol  6  would  be  more  suitable  than  pyrophos- 
phate of  iron. 
In  preparing  the  ammonio-citrate  of  iron  of  the  Pharmacopoeia  the 
writer  would  recommend  that  272  parts  of  ferric  citrate  be  dissolved 
in  three  or  four  times  its  weight  of  water  with  heat,  79  parts  of  am- 
monium bicarbonate  be  then  added  and  the  solution  concentrated  and 
the  salt  be  obtained  in  scales  by  the  usual  method. 
For  preparing  the  red  phosphated  compound  for  use  in  elixirs  (sym- 
bol 5)  816  parts  of  ferric  citrate  is  dissolved  in  three  or  four  times  its 
weight  of  water  with  heat,  237  parts  of  ammonium  bicarbonate  is 
then  added  and,  when  effervescence  has  ceased,  followed  by  358  parts 
of  disodic  phosphate.  The  solution  will  be  ready  for  use  when  all  the 
phosphate  is  dissolved.  This  compound  is  more  conveniently  pre- 
pared by  dissolving  840  parts  of  the  official  ammonio-ferric  citrate  in 
twice  its  weight  of  water  and  then  adding  358  parts  of  sodium  phos- 
phate. 
The  green  phosphated  compound  (symbol  6)  may  be  prepared  by 
dissolving  544  parts  of  ferric  citrate  in  three  or  four  times  its  weight 
of  water,  adding  79  parts  of  ammonium  bicarbonate  and  then  358 
parts  of  sodium  phosphate. 
