An^Jour  Pharm.|       FerHc  Citrate  and  its  Double  Salts.  119 
M  ar.,  lobo.  ) 
to  53  grains  of  citric  acid  in  the  presence  of  water,  and  after  efferves- 
cence ceased,  nnited  with  68  grains  of  ferric  citrate  as  before.  The 
result  being  exactly  identical  with  the  first  one,  the  writer  concluded 
that  this  remarkable  compound  is  not  amorphous,  but  crystalline  or 
transitionally  crystalline.  The  product  of  138  grains  shows  that  the 
salt  is  anhydrous,  and  that  its  formula  is  FeK3Ci2,  or 
Fe  =  Ci 
I        I    and  its  molecular  weight  551. 
Ci  =  K3 
The  construction  of  the  secondary  formula  is  necessitated  by  the 
conditions  of  the  reaction  which  being  distinctly  chemical  and  taking 
place  between  two  fully  saturated  molecules  or  chemically  neutral  salts, 
indicates  a  re-arrangement  or  subdivision  of  the  atomic  bonds. 
The  analogous  sodio  ferric  citrate  is  generated  by  mixing  63  grains 
of  hydro-sodic  carbonate  with  53  grains  of  citric  acid  and  68  grains  of 
ferric  citrate  in  the  presence  of  water  and  evaporating  to  dryness.  The 
result  is  139  grains  of  a  green,  transparent  scaled  salt.  In  respect  to 
its  physical  appearance,  it  thus  differs  radically  from  the  preceding, 
and  also  in  that  it  contains  three  molecules  of  water,  ils  formula  being 
reNa3Ci2.3(OH2)  with  a  molecular  weight  of  557. 
However,  the  most  interesting  and  unexpected  product  results  from 
the  union  of  ferric  citrate  with  quinium  citrate.  The  compound  ob- 
tained is  strictly  analogous  to  the  just  preceding  salts,  and  judging 
from  an  incomplete  observation,  is  perhaps  also  anhydrous  with  a  pro- 
bable formula  of  Fe(QuH)3Ci2.  This  salt  has  the  characteristic  green 
color  and  is  scaly  transparent.  It  is,  however,  nearly  insoluble  in  cold 
water,  quite  soluble  in  hot  water,  more  soluble  in  hot,  weak  alcohol,  but 
soluble  in  all  proportions  in  strong  alcohol,  from  which  solution  it  is 
readily  obtained  in  scales.  It  is  unacted  upon  by  potassic  citrate,  but 
in  the  additional  presence  of  potassic  sulphate,  especially  in  the  cold, 
with  but  little  water,  retrograde  decomposition  sets  in  and  quinium  and 
potassio  ferric  citrate  results.  Yet  when  ferric  citrate,  quinium  sul- 
phate, and  potassic  citrate  in  equivalent  proportion,  that  is  272,  1308, 
and  324  parts  respectively,  are  heated  together  with  considerable  water, 
nearly  all  the  quinine  is  absorbed  into  the  double  salt  which  then  pre- 
cipitates as  a  green  resinous  mass  that  quickly  hardens  on  cooling. 
This  compound  bears  no  analogy  to  the  ordinary  citrate  of  iron  and 
quinium.  This  latter  substance  is  an  analogue  of  the  one  molecule 
double  salts  in  which  the  alkaloid  is  absorbed  only  to  the  amount  of 
about  a  tenth  of  a  quinic  molecule. 
