118 
Tincture  of  Ferrie  Chloride. 
f  Am.  Jour.  Pharm. 
\      March,  1885. 
cipitated  barium  salt,  in  case  the  precipitant  is  weaker  than  the  Phar- 
macopoeial  strength  demanded,  its  replacement  by  simpler  methods, 
with  safe  and  equally  valuable  results,  will  not  be  long  deferred. 
With  the  submitting  of  the  previously  recorded  statements,  the 
author  would  also  desire  to  present  a  formula  for  the  preparation  of 
the  "  Liquor,^^  which  in  his  hands  has  yielded  safe  and  valuable 
results.  The  change  in  working  involves  no  complicated  methods, 
but  simply  consists,  first  in  the  formation  of  ferrous  chloride  with 
metallic  iron  and  diluted  hydrochloric  acid,  as  heretofore,  and  then  in 
the  valeation  of  this  ferrous  salt,  by  exposing  its  heated,  acidulated 
(HCl)  solution  to  the  oxidizing  action  of  gaseous  chlorine  in  its  pas- 
sage through  the  liquid.  Any  excess  of  the  gaseous  element  may  after- 
wards be  readily  removed  by  the  use  of  heat,  or,  if  so  desired,  by  the 
passage  of  a  current  of  air  through  the  solution.  The  use  of  chlorine 
gas,  in  this  connection,  as  an  oxidizer,  is  only  a  new  application  of  the 
old  and  well-known  method  of  preparing  the  normal  ferric  chloride 
solution  employed  in  chemical  analysis  where  an  excess  of  free  acid 
(HCl)  is  not  wished.  On  this  occasion^  however,  an  excess  of  HCl  is 
desirable,  as  a  means  of  insuring  permanency  of  composition. 
FORMULA. 
Iron,  in  the  form  of  fine  wire,  and  cut  in  small  pieces,  15  parts  (3f 
oz.  av.) ;  hydrochloric  acid,  59  parts  (14f  oz.  av.) ;  chlorine  gas,  dis- 
tilled water,  each  a  sufficient  quantity  to  make  100  parts  (25  oz.  av.). 
Place  the  iron  wire  in  a  capacious  flask,  and  pour  upon  it  54  parts 
(13J  oz.  av.)  of  hydrochloric  acid,  previously  diluted  with  25  parts 
(6J  oz.  av.,  or  6  fluidounces)  of  distilled  water.  Heat  the  liquid, 
slowly,  until  the  reaction  is  ended,  and  effervescence  ceases;  then 
rapidly  heat  to  the  boiling  point,  filter  through  paper,  and,  having 
rinsed  the  flask  and  residue  with  a  little  boiling  distilled  water,  pass 
the  washings  through  the  filter.  To  the  filtrate  add,  immediately,  5 
parts  (IJ  oz.  av.)  of  hydrochloric  acid,  followed  by  the  addition  of  20 
parts  (5  oz.  av.)  of  boiling  distilled  water.  Keep  the  liquid  nearly 
boiling,  and  pass  through  it  a  stream  of  gaseous  chlorine  (generated  in 
the  usual  way),  agitating  occasionally,  until  a  small  portion,  tested 
with  freshly  prepared  test  solution  of  potassium  ferricyanide,  gives  no 
indication  of  the  existence  of  a  ferrous  compound  by  producing  a  blue 
precipitate.    Lastly,  add,  after  any  free  chlorine  present  has  been 
