114 
ON  AMERICAN  PHARMACY. 
and  the  remainder  of  the  phosphate  of  soda  in  the  syrup,  and  add 
it  to  the  first  solution,  and  mix. 
The  result  is  a  syrupy,  acid,  saline  liquid,  holding  a  portion  of 
gelatinous  phosphate  of  lime  in  suspension.  This  may  be  entirely 
dissolved  by  using  more  phosphoric  acid,  or  by  adding  a  little 
hydrochloric  acid,  as  suggested  by  Mr.  Wiegand. 
The  reactions  that  occur  in  the  above  formula  are,  first,  the  pro- 
ductions of  phosphate  of  lime,  phosphate  of  iron,  and  chloride  of 
sodium;  next,  the  immediate  solution  of  the  two  first  through  the 
agency  of  the  free  phosphoric  acid.  When  the  syrup  containing 
the  phosphates  of  soda  and  potassa  is  added,  a  portion  of  the  free 
acid  is  attracted  by  them,  and  a  small  part  of  the  phosphate  of 
lime  is  precipitated  in  a  hydrated  form. 
Sulphate  of  iron  may  be  substituted  for  the  chloride  in  the 
above  formula  by  first  triturating  the  soda  salt  and  chloride  of 
calcium  alone  with  a  little  water,  till  double  decomposition  ensues, 
then  adding  the  sulphate  of  iron  and  again  triturating,  and  lastly 
the  phosphoric  acid.  By  observing  this  order  no  sulphate  of  lime 
is  formed,  and  the  mixed  hydrated  phosphates  of  lime  and  iron 
at  first  formed  are  readily  dissolved  by  the  free  acid.  When  sul- 
phate of  iron  is  used,  of  course  both  sulphate  of  soda  and  chloride 
of  sodium  exist  in  the  preparation. 
The  phosphates  of  iron  and  lime  of  commerce  are  often  so 
granular  and  dense  that  their  solution  and  absorption  in  passing 
along  the  alimentary  canal  must  be  much  interfered  with.  This 
difficulty  may  be  avoided,  wrhen  the  free  phosphoric  acid  is  objec- 
tionable, by  presenting  the  insoluble  phosphates  in  a  hydrated 
form,  thus  : — 
Take  of  Proto-Sulphate  of  Iron,  (cryst.,)  gij. 
Chloride  of  Calcium,  (fused,)  giss. 
Phosphate  of  Soda,  (cryst.,)  ovij. 
Syrup  of  Ginger, . 
Distilled  water,  of  each  four  fluid  ounces. 
Triturate  the  chloride  of  calcium  with  the  phosphate  of  soda  and 
three  fluid  ounces  of  the  water,  till  the  decomposition  is  complete, 
and  a  smooth  mixture  is  obtained  ;  then  add  the  syrup,  and 
finally  the  sulphate  of  iron  previously  dissolved  in  a  fluid  ounce 
of  the  water. 
The  resulting  mixture  consists  of  the  hydrated  phosphates  of 
iron  and  lime,  with  about  two  drachms  of  sulphate  of  soda  and  a 
