Am.  Jour.  Pharm.  | 
July,  1877.  } 
Dialyzed  Iron. 
34t 
The  resulting  preparation  is,  or  should  be,  of  a  deep  dark-red  color, 
and  contains  about  5  per  cent,  of  the  oxide  of  iron.  As  to  the  chemi- 
cal condition  of  the  iron  in  solution,  M.  Bravais,  of  Paris  (who  claims 
to  produce  the  only  genuine),  says,  "  It  consists  of  liquid  peroxide  of 
iron,  i.  iron  merely  united  with  oxygen  and  water  to  the  exclusion 
of  all  acids  but  it  is,  no  doubt,  in  fact  a  neutral  solution  of  an  oxy- 
chloride  of  iron  in  a  concentrated  form,  and  the  theory  of  its  produc- 
tion is  nothing  new,  and  is  very  simple.  The  oxychloride  (which  is  the 
substance  retained  in  solution  in  the  dialyzer)  is  a  colloidal  substance. 
The  chloride  (which  is  the  principal  substance  rejected,  or  washed  out 
as  it  were)  is  a  crystalloidal  substance.  These  two  substances — crys- 
talloid and  colloid — are  separated  by  dialysis,  the  former  from  the  lat- 
ter by  diffusion  through  a  septum,  such  as  parchment  paper. 
Other  formulae  more  recently  have  been  suggested,  differing  some- 
what from  the  above,  and  it  has  been  the  subject  of  no  little  discussion 
abroad  as  to  the  particular  merits  of  the  one  or  the  other  of  these.  By 
some  it  has  been  suggested  to  pursue  the  following  formula  :  Take  a 
given  quantity  of  liq.  ferri  perchlor.  (Br.  Ph.),  and  precipitate  by 
ammonia,  wash  well  the  precipitate,  and  mix  with  sufficient  quantity  of 
the  same  preparation  of  liq.  ferri  perchlor.  to  saturation,  and  dialyze. 
It  is  remarkable  how  large  a  proportion  of  this  freshlv  precipitated  ses- 
quioxide  of  iron  will  be  taken  up  or  dissolved.  For  example,  the  pre- 
cipitate obtained  from  one  pint  of  our  officinal  liquor  ferri  chlor.,  repre- 
senting 3  ounces  and  6  drachms  of  dry  oxide,  is  entirely  taken  up  by 
about  5  fluidounces  of  the  same  liquor.  In  the  magma  this  precipitate 
seems  a  very  great  quantity,  so  bulky  is  it  ;  and,  as  stated  before,  it  is 
quite  surprising  to  see  it  disappear  into  solution  under  the  influence  of 
so  small  a  quantity  of  the  liquor. 
By  following  the  above  method,  we  have  found  that  it  shortened  the 
process  considerably.  It  became  thoroughly  dialyzed  in  one  week, 
while  the  other  takes  about  twice  that  time. 
Still  another  method  has  been  suggested,  namely,  to  take  a  given 
quantity  of  the  liquor  ferri  chlor.,  and  add  aqua  ammonias  almost  enough 
to  produce  the  precipitate  of  the  sesquioxide.  When  the  precipitating 
point  is  reached  the  whole  solution  is  placed  in  the  dialyzer.  The 
chloride  of  ammonium  is  thus  extracted  from  the  solution,  and  the  per- 
oxide of  iron,  or  oxychloride,  retained. 
If  either  of  these  processes  is  pursued  carefully  we  have  found  the 
