122 
Citrate  of  Iron  and  Quinine. 
f  Am.  Jour.  Pharm. 
1      March,  1885. 
green  colored  double  salts  are  formed  ("  American  Journal  Pharmacy/^ 
March,  1883). 
In  the  paper  referred  to  a  triquinic  substitution  was  noted.  When 
but  two  or  only  one  replacement  is  made  the  resinous  and  insoluble 
nature  becomes  successively  less  pronounced.  The  interposition  of 
sodium  modifies  these  features  still  further,  so  that  when  two  sodic  and 
one  quinic  radicle  are  present  a  compound  of  considerable  infusibility 
and  solubility  results.  AVhen  at  this  stage  the  ferric  citrate  is  doubled 
the  solubility  is  again  greatly  enhanced.  But  the  tripling  of  the  ferric 
citrate  touches  the  climax  in  an  unlimited  capacity  for  solution.  The 
double  salt  thereby  obtained  is  however  perfectly  nondeliquescent.  It 
has  a  fine  apple  green  tint,  and  is  readily  procured  in  magnificent  and 
permanent  scales.  Although  promptly  and  profusely  soluble  in  cold 
or  hot  water,  it  is  but  sparingly  soluble  in  alcohol.  It  is  also  an  invari- 
ably definite  compound.  For  when  in  preparing  it  three  ms.,  or  8*16 
grams  of  ferric  citrate,  one  m.,  or  2*10  grams  of  citric  acid,  two  ms.,  or 
1'68  grams  of  sodium  bicarbonate,  and  one  m.,  or  3*78  grams  of  tri- 
hydrous  quinine  are  united  in  the  presence  of  water,  evaported  and 
then  dried  at  a  gentle  heat,  a  product  Aveighing  14*03  grams  is  obtained. 
This  result  indicates  that  the  molecular  weight  of  this  new  salt  is  1,403, 
and  that  its  empirical  formula  is  3(FeCi).Na2(QuH)Ci.6Aq.,  and  its 
structural  formula 
Na  Ci   Na 
I 
Ci  Fe  Ci  .  6Aq. 
II  II 
Fe  Ci  Fe 
I 
(QuH). 
Contrasted  in  this  expression  the  proportion  of  quinine  seems  insig- 
nificant. Compared  however  by  weight,  it  is  as  378  to  1,403,  that  is 
the  salt  contains  27  per  cent,  of  trihydrous  quinine. 
The  corresponding  potassium  salt  is  equally  elegant  and  soluble. 
When  8-16  grams  of  ferric  citrate,  2*10  grams  of  citric  acid,  2*00 
grams  of  potassium  bicarbonate,  and  3'78  grams  of  trihydrous  quinine 
are  united  as  in  case  of  the  sodium  salt,  the  product  weighs  13*81 
grams.  This  result  shows  that  the  composition  of  the  salt  is  3(FeCi). 
Ko(QuH)Ci.3Aq.,  and  its  molecular  weight  1,381.  i  ccordingly  the 
percentage  of  quinine  trihydrite  is  about  27*4,  which  corresponds  to 
nearly  31  "3  per  cent,  of  quinium  sulphate. 
An  analogous  sodium  salt  is  produced  when  the  quinine  is  replaced 
