Am.  Jour.  Pharm. 
April,  1887. 
Ferric  Multiple  Citrates. 
167 
phosphate  and  evaporating  the  red-brown  solution  to  dryness  at  a 
gentle  heat  a  red-brown  scaled  salt  of  ready  solubility  and  alkaline 
taste  is  obtained.  Its  empirical  formula  is  FeNa3CiP04.Aq.  and 
molecular  weight  427. 
If  the  ferric  citrate  is  first  treated  with  the  sodium  phosphate  and 
then  with  the  bicarbonate  a  green  solution  results  which  on  careful 
evaporation  yields  a  gray -green  scaled  salt  of  ready  solubility  and  al- 
kaline taste.  Its  empirical  expression  is  FeNa3CiP04.  2  Aq.  and 
molecular  weight  445. 
The  first  of  these  two  salts  when  mixed  with  elixir  of  cinchona  pre- 
pared from  the  sulphates  of  the  cinchona  alkaloids  gives  after  some 
time  a  scanty  deposite  of  crystals.  The  second  of  the  salts  when 
treated  in  the  same  way  gives  instantly  a  more  decided  precipitate  of 
minute  crystals  than  the  former  salt. 
As  deduced  from  its  manner  of  generation  the  constitutional  sym- 
bol of  the  red  salt  may  be  written 
Na— Ci=Fe— P04Na2  (2) 
and  that  of  the  green  salt 
Na2Ci--Fe=P04Na  (3) 
When  two  ms.  of  ferric  citrate  is  treated  with  two  ms.  of  sodium  bi- 
carbonate so  as  to  form  the  basic  citrate  already  noted  above  and  if 
this  product  be  then  treated  with  one  m.  of  disodic  phosphate  a  com- 
pound results  whose  empirical  formula  may  be  written 
Fe2Na4Ci2P04OH.  Aq.  and  having  a  molecular  weight  of  712. 
On  first  treating  the  citrate  with  the  sodic  phosphate  and  then  with 
the  carbonate  an  apparently  identical  result  is  obtained.  From  an  in- 
spection of  the  two  rationally  possible  constitutional  symbols  given  by 
the  data  in  these  cases  it  becomes  evident  that  only  one  of  the  struc- 
tures is  chemically  possible,  as  follows : 
Fe=P04— Fe— OH 
I  I  Aq.  (4) 
Ci=Na2  Ci=Na2 
The  compound  has  an  alkaline  taste  and  renders  elixir  of  cinchona 
shortly  turbid  with  a  crystalline  precipitate. 
On  substituting  ammonium  bicarbonate  for  the  corresponding  so- 
dium salt  in  this  instance  evolution  of  ammonia  occurs  after  addition 
of  the  phosphate  on  warming.  As  during  evaporation  ammonia  is 
continually  dissipated  no  determination  of  the  result  was  made.  The 
