ADULTERATION  OF  ESSENTIAL  OILS. 
327 
of  oil  of  turpentine  entirely  prevented  the  decomposition,  but  it 
must  not  be  boiled  too  long,  as  oil  of  turpentine  is  more  volatile 
than  the  other  essential  oils. 
The  oil  from  the  stalks,  which  is  of  a  less  agreeable  odor, 
behaved  when  pure  exactly  like  the  oil  of  the  seeds.  Nearly  all 
the  samples  obtained  from  different  manufactories  contained  oil 
of  turpentine. 
2.  Oleum  Foeniculi. — The  reagent  became  first  dark  green 
and  then  black  ;  with  a  very  small  quantity  of  the  reagent  the 
oil  became  brownish-yellow,  with  a  larger  quantity  reddish-brown. 
In  this  case  the  author  believes  that  20  to  22  parts  of  oil  decom- 
pose 1  part  of  the  reagent.  The  addition  of  oil  of  turpentine 
prevented  the  decomposition. 
3.  Oleum  Anethi,  and  4.  Oleum  Anisi  semin.  exhibit  the 
reaction  very  rapidly  ;  weaker  when  1  part  of  the  nitroprusside 
of  copper  is  acted  upon  by  1000  parts  than  by  100  parts  of  the 
oil :  the  deposit  is  black. 
5.  Oleum  Qumini  semin.  became  brownish-yellow  with  the 
first,  and  dark  yellowish-brown  with  the  second  proportion  :  the 
deposit  was  only  ashy-grey. 
Of  the  oils  of  the  Labiates,  the  author  examined, — 
6.  Oleum  Lavandulae. — It  furnished  a  slate-grey  deposit. 
The  color  of  the  oil  became  darker  according  to  the  quantity  of 
the  reagent. 
Also  7.  Oleum  3Ienih.ce  pip.  ;  8.  Oleum  Menihce  crisp,  ;  9. 
Oleum  Melissce ;  10.  Oleum  Majorance ;  11.  Oleum  Salvice ; 
12.  Oleum  Serpylli.  They  behaved  in  general  like  Oleum  lav- 
andulce.  With  some  the  deposit  was  quite  black ;  with  others 
brown  or  greyish-black.  An  addition  of  oil  of  turpentine  pre- 
vented the  change  of  color. 
Of  the  oils  of  the  Composite,  there  were  tested,— 
13.  Oleum  Ahsinihii ;  14.  Oleum  Cynce  ;  15.  Oleum  MiUefolit 
flor. ;  and  16.  Oleum  Tanaceti.  With  these  the  deposit  was 
rather  brownish-black,  and  only  pure  black  with  Oleum  Cynce. 
The  beautiful  blue  color  of  the  Oleum  Absinthii  became  first 
pale  blue,  and  then  dark  green. 
The  author  also  examined  the  following  oils  from  the  Myr- 
tacece : — 
