PREPARATION  OF  ARTIFICIAL  COLORING  MATTERS,  ETC.  247 
precipitates  the  chlorides  of  mercury,  platinum,  gold  and  palla- 
dium ;  but  it  does  not  precipitate  the  nitrates  of  mercury  and 
silver. 
Aniline  easily  oxidizes,  turning  yellow  in  water,  and  in  time 
becoming  resinified. 
When  aniline  dissolved  in  hydrochloric  acid  is  acted  on  by 
chlorine  the  solution  takes  a  violet  color,  and  on  continuing  the 
current  of  chlorine  the  liquid  becomes  turbid,  and  deposits  a 
brown-colored  resinoid  mass.  On  submitting  the  whole  to  dis- 
tillation, vapors  of  trichloraniline  and  trichlorophenic  acid  pass 
over. 
A  solution  of  the  alkaline  hypochlorites  colors  aniline  a  violet 
blue,  which  passes  rapidly  to  a  pale  red,  especially  in  contact 
with  acids. 
A  mixture  of  hydrochloric  acid  and  chlorate  of  potash  act 
on  aniline,  the  final  result  of  the  action  being  chloranile  0^20140^, 
but  in  the  course  of  the  reaction  several  colored  intermediary 
bodies  are  formed.* 
If  a  solution  of  chlorate  of  potash  in  hydrochloric  acid  be 
added  to  a  solution  of  a  salt  of  aniline  mixed  with  an  equal  volume 
of  alcohol,  and  care  is  taken  to  avoid  an  excess  of  the  hydro- 
chloric solution,  a  flocculent  precipitate  is  deposited  after  a 
time  of  a  beautiful  indigo  blue  ;  this  precipitate  filtered  and 
washed  with  alcohol  contracts  strongly,  and  the  blue  color  passes 
to  a  deep  green.  The  filtered  liquid  has  a  brownish-red  color  ; 
on  boiling  it,  adding  fresh  quantities  of  hydrochloric  acid,  and 
chlorate  of  potash,  a  yellow  liquor  is  obtained  which  deposits 
crystallised  scales  of  chloranile. 
An  aqueous  solution  of  chromic  acid  gives  with  solutions  of 
aniline  a  green,  blue  or  black  precipitate  according  to  the  con- 
centration of  the  liquors. 
When  a  small  quantity  of  an  aniline  salt  is  mixed  in  a  porce- 
lain dish,  with  a  few  drops  of  strong  sulphuric  acid,  and  a  drop 
of  a  solution  of  bichromate  of  potash  is  allowed  to  fall  on  the 
mixture,  a  beautiful  blue  color  appears  after  some  minutes, 
which,  however,  soon  disappears. 
Dilute  nitric  acid  combines  with  aniline  without  altering  it 
*See  Chem.  News,  vol.  ii.  p.  195. 
