THE 
AMERICAN  JOURNAL  OF  PHARMACY. 
MAY,    1  8  6  2. 
ON  FERRI  SUBCARBONAS. 
By  T.  A.  Rex. 
(An  Inaugural  Essay  presented  to  the  Philadelphia  College  of  Pharmacy,  1862.") 
This  is  one  of  the  most  important  of  the  numerous  iron 
preparations,  and  its  use  as  a  remedial  agent  is  very  general. 
The  U.  S.  Pharmacopoeia  directs  it  to  be  employed  in  making 
the  Tinctura  Ferri  Chloridi,  which  is  now  extensively  used  in 
medicine. 
That  authority  orders  in  preparing  this  tincture,  that  6  oz.  of 
subcarbonate  of  iron,  one  pint  of  muriatic  acid,  and  three  pints 
of  alcohol,  be  taken.  The  subcarbonate  is  directed  to  be  dis- 
solved in  the  acid,  and  when  effervescence  has  ceased,  the  action 
is  to  be  aided  with  a  gentle  heat  until  all  the  salt  is  dissolved. 
The  tincture  is  then  completed  by  filtration  and  the  addition  of 
the  alcohol. 
As  a  large  proportion  of  the  subcarbonate  of  iron  found  in 
commerce  will  not  dissolve  freely  when  so  treated,  thus  causing 
the  tincture  of  the  shops  in  many  cases  to  be  a  very  uncertain 
preparation,  the  following  experiments  were  instituted  to  find 
which  mode  of  conducting  the  precipitation  and  drying  would 
render  the  precipitated  powder  freely  soluble  in  muriatic  acid. 
The  results  of  these  experiments  having  been  inspected  by  my 
preceptor,  Mr.  Edward  Parrish,  they  are  the  more  freely 
offered  in  a  thesis. 
Experiment  1st.  A  saturated  solution  of  sulphate  of  iron,  con- 
taining one  part  by  weight  of  iron  to  two  parts  of  cold  water, 
was  mixed  with  a  saturated  solution  of  carbonate  of  soda  of 
the  same  proportions,  both  solutions  being  cold.  The  resulting 
precipitate  of  protocarbonate  of  iron  was  thoroughly  washed 
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