98  Liquor  Ferri,  Peroxy chloride  of  Iron,  etc.  {^jfe!}^ 
the  quantity  needed  for  saturation,  all  iron  was  precipitated,  while  the 
clear,  colorless  liquid  above  the  precipitate  showed  acid  reaction. 
The  same  experiment  was  repeated,  but  to  the  mixture  obtained 
after  the  addition  of  respectively  81*3  and  1*7  cc.  of  ammonia,  am- 
monia was  added  to  perfect  neutralization  of  the  supernatant  liquid, 
6  cc.  being  required,  making  the  total  of  ammonia  89  cc.  Although 
the  liquid  is  perfectly  neutral,  the  precipitate  is  not  pure  ferric  oxide, 
but  contains  still  a  considerable  quantity  of  chlorine.1 
The  precipitate  of  washed  several  times  by  decantation,  until  on 
addition  of  fresh  water  it  settles  slowly  and  remains  suspended  for  a 
long  time,  is  then  collected  on  a  filter  and  after  thorough  draining 
washed  carefully  with  small  quantities  of  water  at  a  time.  The  liquid 
passes  through  very  slow  and  assumes,  after  a  time,  a  yellowish  color, 
which  becomes  deeper  yellow  by  continued  washing  ;  the  precipitate 
on  the  filter  changes  thereby  its  appearance,  shrinks  considerably,  and 
obtains  at  last  a  darker  brown,  almost  black,  color,  and  has  the  consis- 
tence of  a  jelly.  When  all  the  precipitate  is  converted  into  a  black 
jelly,  which  in  thin  layers  is  transparent  and  of  a  deep  garnet-red  color, 
the  wash  water  no  longer  passes  through  the  filter  unless  a  very  large 
quantity  is  above  the  precipitate,  when  it  may  happen  that  it  dissolves 
at  once,  forming  a  black-red  liquid.  If  the  jelly  is  taken  from  the 
filter,  a  small  quantity  of  water  added  to  it  is  sufficient  to  dissolve  it 
entirely  after  some  time.  The  solution  has,  in  reflected  light,  a  pure 
black  color,  dissolves  in  more  water  to  a  transparent  deep  red  solution, 
is  neutral,  but  still  contains  ammonium  chloride,  as  the  jelly  forms 
before  it  is  all  washed  out. 
A  second  precipitate,  obtained  in  the  same  way,  was,  after  draining 
ofF  the  supernatant  acid  liquid,  subjected  to  dialysis.  In  the  same 
degree  as  the  acid  and  ammonium  chloride  is  removed,  the  precipitate 
in  the  dialyzer  changes  at  first  into  a  jelly-like  black  mass  and  after- 
wards into  a  turbid  thick  liquid  of  the  consistence  of  cream.  Taken 
then  (after  three  weeks)  from  the  dialyzer,  it  dissolves  on  the  addition 
of  a  little  water,  after  a  few  days,  to  a  perfectly  clear,  thin  liquid,  of  a 
brownish-black  color. 
By  using  more  ammonia  than  is  necessary  to  precipitate  the  iron, 
1  By  calculation  it  was  found  that  92*6  cc.  of  the  ammonia  were  necessary  to  bind 
all  the  hydrochloric  acid  in  150  cc.  of  this  dilute  ferric  chloride  solution. 
