324    SYRUP  PHOSPHATES  OF  IRON,  QUINIA  AND  STRYCHNIA. 
A  quantity  of  the  syrup,  later  obtained  from  Mr.  Aitken 
himself,  and  which  was  contained  in  dark  bottles,  exhibited  the 
same  bulky  gelatinous  deposit,  the  supernatant  liquid  being 
transparent  and  of  a  reddish-brown  tinge.  This  comparison 
conclusively  demonstrates  that  the  ill  success  attending  its  pre- 
paration is  the  consequence  of  a  fallacious  formula,  and  not  the 
result  of  unskilful  manipulation. 
Being  recently  called  upon  to  prepare  the  syrup  again,  I  pro- 
ceeded in  a  somewhat  different  manner  than  the  formula  implies, 
although  aiming  at  a  result  to  be  identical  with  that  of  the  re- 
quirements. The  first  attempt  was  to  procure  an  aqueous  solu- 
tion of  the  phosphates  in  a  sufficiently  concentrated  state  with- 
out heat — at  the  same  time  avoiding  the  unnecessary  excess  of 
phosphoric  acid  of  the  formula — that  would  admit  of  admixture 
with  a  sufficient  quantity  of  syrup  previously  prepared,  and  form 
a  syrup  of  greater  density  than  that  of  the  formula,  and  at  the 
same  time  evading  the  formation  of  that  persistent  foam.  The 
operations  in  view  were  to  prepare  the  phosphates  of  iron  and 
quinia  without  precipitation,  thereby  avoiding  the  oxidation  of 
the  protoxide  of  iron,  and  the  unnecessary  bulk  of  the  solution 
consequent  upon  precipitation  and  re-solution.  The  phosphoric 
acid  here  employed  is  the  monobasic  or  metaphosphoric  (P05HO). 
278  gr.  of  protosulphate  of  iron  (FeO,  S03  7  HO)  will  pro- 
duce, with  358  gr.  of  phosphate  of  soda  (2  NaOHO,  P05  24  HO), 
152  gr.  of  phosphate  of  iron  (2  FeO,  HO,  P05),  which  contains 
80  gr.  of  metaphosphoric  acid  ;  but  to  dissolve  this  198  gr.  more 
of  metaphosphoric  acid  must  be  added,  that  is  278  gr.  of  meta- 
phosphoric acid  must  be  present  to  effect  complete  solution  (Par- 
rish,  Roberts'  Formula). 
Therefore  1000  gr.  of  protosulphate  of  iron  converted  into 
phosphate  of  iron  (546*76  gr.) 
2(FeO,  S03  7  HO)  :    2  FeO  HO  P05  :  :    1000  :    (  ) 
278  :       152  :  :    1000  :  546-76 
requires  the  presence  of  1000  gr.  of  metaphosphoric  acid  to  re- 
tain it  in  solution.  The  iron  in  this  solution  is  assumed  to  be  in 
the  state  of  superphosphate  (FeO  2  HO  P05).  But  the  quanti- 
ty of  superphosphate  of  iron,  899*28  gr., 
FeO  S03  7  HO  :  FeO  2  HO  P05  :  :  1000  :  (  ) 
139  :         *125         :  :  1000  :  899-28 
