134     PREPARATION  OF  ARTIFICIAL  COLORING  MATTERS,  ETC. 
collected  at  the  end  of  the  worm,  is  first  washed  with  water, 
then  with  a  solution  of  carbonate  of  soda,  and  afterwards  once 
again  with  water. 
Nitro-benzole  is  a  yellowish  liquid  which  at  15^  C.  has  the 
sp.  gr.  1.209.  It  boils  at  213^^,  and  cooled  to  3"^  it  crystal. 
Uses  in  needles.  Having  an  odour  closely  resembling  that  of 
the  essential  oil  of  bitter  almonds,  it  has  been  largely  used  in 
perfumery  for  scenting  fancy  soaps,  for  which  purpose  it  has 
one  advantage  over  the  oil  of  bitter  almonds — it  is  less  affected 
by  the  action  of  alkalies.  It  is  almost  insoluble  in  water,  but 
is  very  soluble  in  alcohol,  ether,  and  the  essential  oils.  Con- 
centrated nitric  and  sulphuric  acid  dissolve  it,  but  it  is  pre- 
cipitated on  the  addition  of  water.  It  is  decomposed  by 
continued  boiling  with  concentrated  sulphuric  acid  ;  and  under 
the  same  circumstances  with  concentrated  nitric  acid  it  forms  bi- 
nitro-benzole.  Neither  the  alkalies  in  strong  aqueous  solution, 
nor  quick  lime  act  on  nitro-benzole ;  but  an  alcoholic  solution 
of  the  alkalies  act  energetically  and  form  azoxybenzole  (C^^H^q 
K2O2).  By  the  action  of  nitric  acid  on  this  last  substance  a 
number  of  other  interesting  bodies  are  produced,  which,  how- 
ever, it  is  not  necessary  now  to  describe. 
Transformation  of  Nitro-Benzole  into  Aniline. — 
This  is  effected  by  a  variety  of  processes  which  we  shall  pro- 
ceed to  describe  in  detail. 
1.  By  means  of  sulphide  of  ammonium.  An  alcoholic 
solution  of  nitro-benzole  after  having  been  saturated  with 
ammoniacal  gas  is  treated  with  a  current  of  sulphuretted  hy. 
drogen.  The  liquor  now  becomes  of  a  deep  dirty  green  color, 
and  deposits  a  little  sulphur.  It  is  now  left  for  twenty-four 
hours,  during  which  time  crystals  of  sulphur  are  deposited,  the 
odour  of  sulphuretted  hydrogen  disappears,  and  is  replaced  by 
a  strongly  ammoniacal  smell.  If  distilled  now  to  recover  the 
alcohol,  a  good  deal  of  sulphur  is  deposited,  and  it  is  impossible 
to  continue  the  distillation  long,  because  of  the  violent  bumping 
which  ensues.  It  is  therefore  allowed  to  cool  and  the  sulphur 
is  removed.  On  distilling  the  liquor  again  more  sulphur  is 
deposited,  which  must  also  be  removed.  The  process  must  be 
continued,  re-saturating  the  liquor  with  sulphuretted  hydrogen 
