438   THE  PHARMACOPOEIA  PROCESS  FOR  CITRATE  OF  IRON,  &C. 
oxide  of  iron,*  made  of  such  a  strength  that  this  quantity  shall 
exactly  represent  six  drachms  of  the  anhydrous  salt. 
To  such  a  solution,  heated  by  the  water-bath,  add  one  drachm 
of  citric  acid  previously  dissolved  in  one  ounce  of  distilled  water, 
and  immediately  afterwards  add  at  once  the  quantity  of  quinia 
freshly  precipitated  by  solution  of  ammonia  from  two  drachms 
of  disulphate  of  quinia.  Continue  the  application  of  heat,  and 
stir  the  mixture  constantly  until  all  the  quinia  is  dissolved. 
Solution  of  ammonia  (P.L.)  is  then  added  drop  by  drop  in  suf- 
*The  saturated  solution  of  citrate  of  peroxide  of  iron  is  made  by  satu- 
rating at  the  heat  of  the  water-bath  a  solution  of  citric  acid  with  freshly- 
prepared  hydrated  sesquioxide  of  iron,  until  no  more  oxide  is  dissolved 
in  the  solution  of  citric  acid.  The  excess  of  oxide  of  iron  is  then  removed 
by  filtration,  and  the  liquid  evaporated  to  such  a  strength  that  every  fluid 
ounce  must  represent  one  drachm  of  anhydrous  citrate  of  iron. 
[Note. — In  order  that  our  readers  may  appreciate  this  paper  we  append 
the  following  condensed  view  of  the  process  of  the  British  Pharmacopoeia 
for  this  salt : — 
Take  of  Solution  of  Persulphate  of  Iron,  3  fluid  ounces  ; 
Sulphate  of  Iron,  an  ounce  ( Av.) ; 
Solution  of  Soda,  36  fluid  ounces  ; 
Citric  Acid,  2\  ounces  ( Av.) ; 
Sulphate  of  Quinia,  380  grains; 
Distilled  Water,  Dilute  Hydrochloric  Acid,  Solution  of  Chlo- 
ride of  Barium  and  Solution  of  Ammonia,  of  each  a  suffi- 
ciency. 
Dissolve  the  sulphate  of  iron  in  10  fluid  ounces  of  the  water,  mix  with  it 
first  the  persulphate  solution  and  then  the  solution  of  soda,  stirring  con- 
stantly j  then  wash  the  precipitates  in  a  muslin  filter  till  tasteless.  Dis- 
solve the  citric  acid  in  20  fluid  ounces  of  distilled  water,  and  dissolve  in 
it  the  precipitated  oxide  of  iron,  by  aid  of  a  water-bath  heat. 
Dissolve  the  sulphate  of  quinia  in  half  a  pint  of  water  by  aid  of  suffi- 
cient muriatic  acid,  and  add  solution  of  chloride  of  barium  till  all  the  sul- 
phuric acid  is  precipitated ;  then  filter,  add  a  slight  excess  of  ammonia, 
collect  the  precipitated  quina  on  a  filter  and  wash  it  thoroughly. 
Lastly,  dissolve  the  quinia  in  the  solution  of  citrate  of  iron  on  a  water- 
bath  and  evaporate  in  thin  layers  on  glass  at  a  temperature  below 
212°  F. 
The  writer  has  adopted  a  process  analogous  to  that  in  the  U.  S.  Phar- 
macopoeia, except  in  quinia  strength  and  in  the  introduction  of  ammonia 
to  give  the  greenish-yellow  appearance  to  the  salt ;  our  salt  being  reddish- 
brown  when  in  thick  scales,  and  yellowish-brown  in  very  thin  scales. — 
Editor  Amer.  Journ.  Pharm.] 
