168 
Ferric  Multiple  Citrates. 
( Am.  Jour.  Pharm. 
1      April,  1887. 
compound  gives  a  scant  product  of  distinct  crystals  with  elixir  of 
cinchona  only  after  several  hours  standing. 
By  reacting  on  three  ms.  of  ferric  citrate  with  three  ms.  of  ammo- 
nium bicarbonate  and  one  m.  of  disodic  phosphate  a  red-brown, 
readily  scaling  salt  is  obtained  which  may  be  structurally  symbolized 
by: 
NH4 
I 
OH — Fe — Ci — Fe — OH 
I  I  (5) 
NH-  Ci— Fe— Ci— NH4 
Na— PO— Na 
It  is  anhydrous  and  its  molecular  weight  is  964.  During  its  course 
of  preparation  no  ammonia  is  abandoned  as  in  the  preceding  case. 
When  mixed  with  elixir  of  cinchona  no  precipitate  occurs  even  after 
long  standing.  The  structural  and  chemical  possibilities  point  to  an 
isomeric  salt  but  its  production  was  not  attempted. 
This  statement  has  reference  only  to  the  distribution  of  the  acidic 
radicles  in  the  main  group.  But  when  regard  is  also  had  to  the  ar- 
rangement of  the  monad  basic  radicles  a  greater  number  would  be  pos- 
sible. In  the  structural  form  last  given  the  writer  has  assumed  the 
retention  of  all  the  sodium  originally  combined  with  the  phosphoric 
radicle.  Yet  there  is  no  evident  reason  for  the  contrary  that  half  or 
all  is  replaced  by  ammonia  radicles. 
Elsewhere  (Amer.  Jour.  Phar.,  April  1883)  the  writer  recom- 
mended a  salt  derived  from  two  ms.  of  ferric  citrate,  one  m.  of  sodium 
bicarbonate  and  one  m.  of  disodic  phosphate.  On  recently  substitut- 
ing ammonium  bicarbonate  for  the  corresponding  sodium  salt  a  pro- 
duct was  found  having  the  empirical  formula 
Fe2Na2NH4Ci2P04.  Aq. 
and  the  molecular  weight  667. 
The  constitutional  symbol  as  deduced  from  the  order  of  uniting  the 
constituents  might  be  written 
Na 
Fe— PO— Fe  (6) 
II  II 
Na— Ci  Ci — NH4 
There  are  a  number  more  of  well  characterized  symbolic  forms  that 
could  be  assigned  to  this  compound  independent  of  the  order  of  mixture. 
