Am.  Jour.  Pharm.  \ 
August,  1884.  ) 
Ferric  Chlorides. 
411 
sulphate  is  8  parts,  this  being  a  slight  excess  as  will  be  noticed  from 
the  accompanying  proportion : 
Ba(C103)2  Aq.,  321-6  :H2S04,  98  -r-  -96  ::  25:7-94 
Since  the  chlorhydric  acid  resulting  from  the  decomposition  of  the 
generated  barium  chloride  amounts  to  one-eighteenth  of  the  whole,  or 
320  ~  18  =  17-78  parts,  the  total  quantity  will  be  337*78  parts- 
Although  this  represents  a  considerable  excess,  the  amount  is  still 
below  the  official  quantity,  which  is  344  parts. 
In  the  "  Pharmacist"  for  July,  1872,  the  writer  recommends  a  process 
for  making  tincture  of  iron,  in  which  he  proposed  to  use  only  the 
requisite  amount  of  a  practically  pure  metal.  By  avoiding  an  excess, 
a  known  definite  amount  of  iron  was  thus  incorporated.  The  writer 
also  advocated  the  employment  of  all  the  acid  at  once,  thereby  greatly 
expediting  the  solution  of  the  iron.  On  this  occasion  the  acid  was 
used  in  a  diluted  form.  Recently,  however,  it  was  found  unnecessary 
to  dilute  the  acid  when  using  the  whole  of  it  at  the  outset.  The  con- 
tinual presence  of  a  large  excess  acting  upon  a  fine  form  of  iron 
insures  rapid  solution,  with  uniform  energy. 
From  these  various  considerations  the  following  formula  for  a  solu- 
tion if  ferric  chloride  is  devised  : 
Iron,  in  fine  wire   53  parts. 
Chlorhydric  acid   320  " 
Barium  chlorate  ,   25  " 
Sulphuric  acid   8  " 
Water  sufficient  to  make   400  " 
Add  the  iron  gradually  to  the  chlorhydric  acid,  and  when  all  has 
dissolved  add  the  barium  chlorate,  in  small  portions  at  a  time,  during 
constant  stirring  of  the  mixture.  When  the  incorporation,  solution 
and  decomposition  of  this  is  complete,  pour  in  the  sulphuric  acid,  pre- 
viously diluted  with  half  its  weight  of  water,  with  constant  stirring, 
and  set  the  mixture  away,  so  that  the  barium  sulphate  may  subside. 
Now  decant  the  clear  solution,  and  transfer  the  turbid  portion  to  a 
filter,  and  add  water  through  the  filter  until  the  decantate  and  filtrate 
together  weigh  400  parts,  and  mix  them. 
The  so-called  basic  salts  of  iron  are  of  two  kinds,  which  in  mauy 
respects  are  so  similar  that  very  little,  if  any,  distinction  has  been 
made  between  them.  In  many  particulars,  however,  the  difference  is 
so  important  that  for  various  practical  reasons  it  cannot  be  ignored. 
