Am  Jodb.  Pharm.  > 
Feb.  1, 1874.  j 
Arnmonio- Citrate  of  Iron. 
75 
Pharm.  Lond.,    1851     .  .  34  per  cent.  Fe203. 
Brit.  Pharm.,     1864  .  .      26-5  " 
1867     .  .  27-0 
U.  S.     "         1873  ? 
French  Codex,  .  .  ?  " 
Pharm.  Germ.,  1872  ? 
Most  of  the  recent  formulae  have  one  feature  in  common,  viz.,  the 
complete  saturation  of  the  acid  by  the  oxide  of  iron,  but  the  quanti- 
ties ordered  by  each  work  with  this  object  in  view  are  very  dispro- 
portionate. 
The  British  Pharmacopoeia,  1867,  says,  "  dissolve  the  citric  acid  in 
weight  ounces  of  distilled  water,  and  having  applied  the  heat  of  a  water- 
bath,  add  the  oxide  of  iron,  and  stir  them  together  until  the  whole,  or 
nearly  the  whole,  of  the  oxide  has  dissolved." 
It  is  presumed  that  complete  saturation  is  intended  by  the  expres- 
sion "  until  nearly  the  whole  of  the  oxide  has  been  dissolved"  and  that 
the  amount  of  oxide  produced  by  the  precipitation  of  the  persulphate 
of  iron  ordered  is  in  slight  excess  of  the  quantity  required  for  such 
saturation. 
Be  this  as  it  may,  upon  referring  to  the  Codex  we  find  an  amount 
of  hydrated  oxide  ordered  which  shall  be  equal  to  53  parts  of  anhy- 
drous oxide,  whereas  the  British  Pharmacopoeia,  1867,  orders  an 
equivalent  of  42  parts  only. 
Practically  I  have  found  that  the  French  Codex  formula  is  much 
more  like  the  basis  of  ammonio-citrate  of  iron  of  the  best  makers  than 
is  the  British  Pharm.  formula,  although  fifty  parts  (half  its  weight) 
would  more  accurately  represent  the  amount  of  ferric  oxide  (added  as 
hydrated  oxide)  required  to  saturate  100  parts  of  citric  acid  than 
Would  fifty -three  parts,  as  named  by  the  Codex. 
A  comparison  of  the  formulae  of  the  British  Pharmacopoeias  of 
1864  and  1867,  as  to  the  amount  of  ferric  oxide  added  to  the  acid, 
and  the  amount  stated  to  be  left  by  calcination  is  most  conflicting  ; 
for  instance,  the  1864  Pharmacopoeia  shows  that  for  33*4  parts  ferric 
oxide  to  100  citric  acid,  as  much  as  26-5  per  cent,  is  left  upon  calci- 
nation, whereas  that  of  1867  indicates  that  from  41*8  parts  added  to 
the  same  amount  of  citric  acid,  27  per  cent,  is  left  by  calcination. 
The  mean  of  three  analyses  of  ammonio-citrate  of  iron  (B.  P.  1867) 
gave  ferric  oxide  by  calcination  27*4  per  cent.,  proving  the  accuracy 
of  the  present  officinal  test  and  the  fallacy  of  the  1864  Pharmacopoeia. 
