326    SYRUP  PHOSPHATES  OF  IRON,  QUINIA  AND  STRYCHNIA. 
Accordingly,  a  solution  of  superphosphate  of  iron,  represent- 
ing 1000  gr.  of  protosulphate  of  iron,  as  above  described,  con- 
verted into  a  syrup  of  the  phosphates,  to  represent  the  propor- 
tional quantities  of  quinia  and  strychnia  of  the  preceding 
formula,  would  produce  80  f 5  or  5  pints  of  syrup,  with  the  fol- 
lowing requisitions  : 
Sulphate  of  Quinia,         ....       640  gr. 
Strychnia,      ......         20  gr. 
Sugar  (as  Syrup  U.  S.  P.  f$  57*04),         .         46ft  I 
Water,  sufficient. 
All  that  remains  now  to  complete  the  syrup  is  the  conversion 
of  the  alkaloids  into  phosphates,  and  their  incorporation  with 
the  iron  solution  and  the  syrup.  To  prepare  the  strychnia  phos- 
phate requires  simply  mixture  with  the  iron  solution,  in  which  it 
readily  dissolves.  But  in  case  of  the  quinia  salt,  as  the  formula 
precludes  the  combined  sulphuric  acid,  this  must  first  be  removed, 
which  is  easily  effected  by  conversion  into  sulphate  of  lime  by 
double  decomposition  with  a  solution  of  superphosphate  of  lime. 
To  accomplish  this  75*84  gr.  of  tribasic  phosphate  of  lime,  in  the 
state  of  superphosphate,  is  necessary. 
3(N2C40H24  0„  SO38HO)  :  3  CaO  P05  :  :  640  : 
1308  :       155       :  :  640  :  75-84 
The  tribasic  phosphate  of  lime  may  now  be  dissolved  in  a 
sufficient  quantity  of  a  hot  solution  of  metaphosphoric  acid,  the 
sulphate  of  quinia  added  and,  after  complete  decomposition,  filter- 
ing, and  the  filtrate  mixed  with  the  iron  solution  and  the  syrup. 
This  operation  of  separately  preparing  the  phosphate  of  quinia 
may  be  advantageously  dispensed  with,  and  the  whole  process 
much  abridged  by  transforming  the  sulphate  of  quinia  simul- 
taneously along  with  the  protosulphate  of  iron  into  phosphate, 
employing  the  necessary  amount  of  tribasic  phosphate  of  lime,  in 
the  condition  of  superphosphate,  to  render  the  decomposition  of 
the  two  sulphates  complete.  This  process  is  executed  as  pre- 
sented below : 
Protosulphate  of  Iron,         .        .       1000  gr. 
Tribasic  Phosphate  of  Lime,        .         423*57  gr. 
Metaphosphoric  Acid,         .        .         781*32  gr. 
Sulphate  of  Quinia,  .        .         640  gr. 
