248     PREPARATION  OP  ARTIFICIAL  COLORING  MATTERS,  ETC. 
immediately  ;  but  after  some  time  nitrate  of  aniline  crystallizes 
in  the  form  of  concentric  needles,  the  mother  liquor  turns  red 
colored,  and  the  sides  of  the  capsule  become  covered  with  a 
beautiful  blue  efflorescence.  When  a  few  drops  of  strong  fuming 
nitric  acid  are  poured  upon  aniline  it  is  immediately  colored  a 
deep  blue;  on  applying  heat  the  blue  tint  quickly  passes  to  yel- 
low, a  lively  reaction  is  manifested,  which  results  in  the  forma- 
tion of  picric  or  trinitrophenisic  acid. 
Potassium  dissolves  in  aniline,  disengaging  hydrogen,  whilst 
the  whole  becomes  a  violet  colored  pap. 
The  other  reactions  of  aniline,  which  are  characterised  by  the 
formation  of  anileine,  fuchsine  and  azaleine,  will  be  related  in  a 
future  number,  when  describing  the  processes  for  the  prepara- 
tion of  these  substances.  But  before  commencing  these  we  may 
just  glance  at  some  of  the  properties  and  derivatives  of  binitro- 
benzole. 
Binitrobenzole,  as  before  stated,  is  formed  when  nitrobenzole 
is  added  drop  by  drop  to  a  mixture  of  equal  parts  of  fuming 
nitric  acid  and  sulphuric  acid  as  long  as  the  liquids  will  mix. 
If  such  a  mixture  be  boiled  for  a  few  minutes  it  becomes  on 
cooling  a  thick  magna  of  binitrobenzole,  which  is  easily  purified 
by  repeated  washings  with  water.  A  single  crystallization  from 
alcohol  will  furnish  the  body  in  long  brilliant  prisms  which  melt 
at  a  temperature  above  100"^,  and  crystallize  again  on  cooling, 
in  a  radiated  mass. 
Binitrobenzole  is  very  soluble  in  warm  alcohol.  When  a 
plate  of  zinc  well  cleaned  is  placed  in  a  cold  alcoholic  solution 
of  binitrobenzole  and  hydrochloric  acid  is  added  by  degrees, 
we  observe  that  the  disengagement  of  hydrogen,  which  at  first 
takes  place,  soon  ceases,  and  at  the  same  time  the  liquid  gradu- 
ally takes  a  crimson-red  tint.*  The  reaction  being  completed, 
the  excess  of  zinc  is  removed  and  the  liquor  is  saturated  by  an 
alkali,  which  precipitates  the  oxide  of  zinc  colored  a  deep  pur- 
ple. The  precipitate  is  collected  on  a  filter  and  washed  with 
alcohol.  By  distilling  the  highly  colored  alcoholic  washings, 
washing  the  residue  with  cold  water,  then  redissolving  it  in 
alcohol  and  evaporating  it  afresh  to  dryness,  the  new  matter  is 
obtained  perfectly  pure.    The  authors  have  given  it  the  name 
*Church  and  Perkin,  Quart,  Journ.  Chem.  Soc.  ix.  p.  1. 
