438 
Hypophosphifcs  confdining  Iron. 
j  Am.  Jour.  Pharm 
(      Sept.,  1882. 
more,  and  by  the  late  Prof.  AVni.  IVocter,  Jr./  I  am  unable  to  decide^ 
but  this  much  is  certain,  that  these  two  formulas  have  been  authorita- 
tive for  American  pharmacists,  though  it  by  no  means  follows  thiit 
they  have  been  uniformly  followed.  The  two  formulas  differ  essen^ 
tially  only  in  that  Mr.  Thompson  directs  the  fen-oits  salt,  while  Prof. 
Procter's  formula  requires  fm'/c  hypophosphite.  The  latter  produces- 
a  permanent  and  generally  acceptable  preparation,  the  only  objection 
being  the  presence  of  free  hypophosphorous  acid.  The  preparation  of 
Mr.  Thompson,  which  also  contains  free  hypophosphorous  acid,  is 
preferred  by  some  because  it  contains  the  iron  in  the  condition  of  fer- 
rous salt ;  but  the  latter  is  easily  changed,  and  the  preparation  is  there- 
fore not  so  satisfactory. 
In  the  preparations  prepared  by  me  the  ferric  salt  is  used,  as  in< 
Prof.  Procter's  formula,  but  instead  of  effecting  its  solution  by  means- 
of  hypophosphorous  acid,  citrate  of  potassium  is  em[)loyed,  a  handsome 
greenish  and  j^erfectly  neutral  solution  being  formed.  The  quantity 
of  the  citrate  necessary  for  this  purpose  is  about  equal  to  that  of  the 
dry  ferric  salt,  but  the  latter  is  preferably  prepared  freshly  and  dis- 
solved while  still  moist.  The  citrates  of  ammonium  or  sodium  would 
answer  the  purpose  of  solvent  as  well  as  the  potassium  salt,  which  was 
selected  only  because  it  is  always  at  hand,  and  because  the  ammonium 
and  sodium  salts  are  not  known  to  possess  any  advantage.  For  the 
})reparation  of  the  ferric  hypophosphite  any  of  the  soluble  salts  of  the 
hypophosphorous  acid  will  answer,  but  I  have  selected  the  hypophos- 
phite of  calcium,  with  ferric  chloride  as  precipitant,  for  the  reason  that 
it  is  the  salt  most  commonly  kept  in  (piantities,  and  because  it  is  the 
cheapest.  Certain  precautions  must,  hoAvever,  be  observed  to  secure 
the  perfect  precipitation  of  ferric  hypophosphite,  for  if  too  much  or  an 
insufficient  quantity  of  ferric  chloride  is  added,  a  portion  of  the  hypo- 
phosphite remains  in  solution  and  is  lost  during  the  washing  of  the 
})recipitate,  which  must  be  done  with  the  smallest  possible  quantity  of" 
water.  It  may  be  well,  therefore,  to  give  particular  consideration  to 
the 
Preparation  of  the  Ferric  Hi/pophospJiite. — Dissolve  150  grains  of" 
the  hypophosphite  of  calcium  in  4  fluidounces  of  distilled  water,  if" 
necessary,  by  the  aid  of  gentle  heat,  and  filter  the  solution.    To  the 
cold  solution  carefully  add  solution  of  ferric  chloride  so  long  as  a  pre- 
cipitate is  produced.    Collect  the  precipitate  upon  a  close  musliu.. 
1  Parrish's  Pharmacy,  tliird  edition,  1864,  pp.  429,450.. 
