PREPARATION  OF  ARTIFICIAL  COLORING  MATTERS,  ETC.  133 
which  characterise  aniline.  The  operations  may  be  executed 
very  rapidly,  and  without  any  difficulty. 
Properties  op  Benzole. — At  the  ordinary  temperature  ben 
zole  is  seen  in  the  form  of  a  colorless  very  fluid  liquid,  of  an  agree- 
able (?)  odor,  and  having  the  speciflo  gravity  -85°  at  15^  C. 
At  a  very  low  temperature  it  crystallises  or  forms  a  mass  like 
camphor,  which  melts  at  5'^  Its  boiling-point  is  between  80^ 
and  81^,  and  it  distils  without  undergoing  any  change.  It  is 
nearly  insoluble  in  water,  to  which,  however,  it  imparts  its 
peculiar  odor;  it  is  very  soluble  in  wood-spirit,  ether,  alcohol, 
the  essential  and  the  fatty  oils  ;  and  it  easily  dissolves  camphor, 
wax,  fatty  matters,  india-rubber,  gutta-percha,  and  a  great 
number  of  resins.  Among  the  last,  those  which  are  least  solu- 
ble in  it  are  shellac,  copal,  and  animi.  It  is  very  inflammable, 
and  burns  with  a  brilliant  smoky  flame.  Hydrogen  gas  passed 
through  it,  and  charged  with  its  vapor,  burns  with  a  very  clear, 
luminous  flame. 
Chlorine  and  bromine  convert  benzole  into  the  terchloride 
and  terbromide  of  benzole.  In  direct  solar  light  the  change 
takes  place  very  quickly.  Concentrated  sulphuric  acid  dissolves 
benzole,  and  when  the  mixture  is  gently  heated,  a  copulated 
acid,  sulpho-benzylic  acid,  is  formed,  C^2^^6^2^6'  hydrogen 
of  which  may  be  replaced  by  metals.  As  this  acid  is  soluble 
in  water,  we  see  that  in  purifying  rough  benzole  with  sulphuric 
acid  it  is  necessary  to  avoid  using  an  excess  of  the  acid,  and 
also  heating  the  mixture.  A  solution  of  chromic  acid  does  not 
act  on  benzole,  and  is  therefore  a  good  agent  for  the  purifica- 
tion. Concentrated  nitric  acid  converts  benzole  into  nitro-ben- 
zole,  to  the  manufacture  of  which  we  next  proceed. 
Preparation  of  Nitro-Benzole. — The  prepartion  of  nitro- 
benzole  is  accomplished,  on  the  large  scale,  by  allowing  a  fine 
stream  of  benzole,  and  another  of  the  strongest  nitric  acid  to 
run  together  in  a  worm  or  long  glass  tube  kept  well  cooled. 
The  two  liquids  react  on  each  other  on  coming  in  contact,  heat 
is  disengaged,  and  nitro-benzole  is  formed.  Commercial  nitric 
acid  mixed  with  half  its  volume  of  sulphuric  acid  may  be  sub- 
stituted for  the  concentrated  nitric  acid.    The  nitro-benzole 
