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ON  IMPROVING  THE  CRUDE  ROSIN  OILS. 
ON  IMPROVING  THE  0KU1>2  KOSIN  OILS. 
By  Professor  G.  F.  Melsens,  of  Brussels. 
The  object  of  this  invention  is : 
1.  To  obtain  a  colorless  volatile  oil,  which,  instead  of  the  fetid 
empyreumatic  odor  of  the  crude  oil,  has  an  agreeable  aromatic 
smell,  retains  its  transparency,  and  is  otherwise  unchangeable  in 
the  air. 
2.  As  much  as  possible  to  change  the  fixed  liquid  or  sticky 
oil  into  a  volatile  oil,  preventing  a  decomposition  into  gases. 
3.  To  obtain  a  liquid  fixed  oil  of  an  amber  yellow  color. 
I.  Purification  of  the  Crude  Volatile  Oil. — The  crude  resin 
oil  being  a  mixture  of  fats,  fixed  and  volatile  oils,  is  treated  with 
a  solution  of  caustic  soda  or  its  carbonate  in  excess  ;  the  volatile 
oil  rises  to  the  surface,  is  decanted  and  put  into  a  suitable  iron 
or  copper  vessel  where  it  comes  in  contact  with  a  current  of 
steam  of  100°  C,  (212°  F.)  or  more,  by  which  it  is  carried  over 
into  an  ordinary  worm  where  it  condenses  and  runs  into  a  vessel 
connected  with  a  Florence  receiver ;  this  distillate  may  be 
collected  either  in  fractions  or  in  mass.  In  either  case  it  is 
mixed  with  about  10  per  cent,  of  its  bulk  of  nitric  acid  of  36° 
Beaume  and  beaten  to  a  homogeneous  mass.  The  oil,  which  at 
first  was  of  a  white  or  pale  yellow  color,  turns  to  a  greenish 
brown  when  it  is  decanted  and  distilled  as  above  with  an  excess 
of  milk  of  lime.  The  density  of  the  separated  nitric  acid  has 
fallen  to  from  26  to  30°  B. ;  it  may  be  used  a  second  time, 
together  with  a  small  quantity  of  concentrated  sulphuric  acid. 
Chromic  acid,  deutoxide  of  manganese  or  lead,  a  mixture  of 
muriatic  acid  and  black  manganese,  sulphurous  acid  and  sulphu- 
ret  of  ammonium,  are  inferior  to  nitric  acid  ;  but  a  still  better 
product  is  obtained  by  employing  10  per  cent,  of  a  mixture  of 
equal  parts  of  concentrated  sulphuric  acid  and  black  manganese  ; 
on  mixing  with  the  oil,  a  heat  is  generated,  raising  the  whole  mass 
to  the  boiling  point.  If  the  manufactured  oil  be  chiefly  a  crude 
volatile  oil,  the  first  distillation  of  course  may  be  omitted. 
II.  Production  of  the  Volatile  Oil. — The  oil  obtained  from  the 
distillation  of  resin,  either  by  itself,  or  having  the  residue  of  this 
distillation  or  some  resin  dissolved  in  it,  by  means  of  a  hooked 
