Notes  on  Patchouli. 
(  Am.  Jour.  Pharm. 
I      Jan.,  1881. 
which  is  also  found  in  the  oils  of  Calamus  aromaticus,  Matricaria 
chamomiila,  Artemisia  absinthium,  Achillea  millefolium,  and  in  small 
quantity  in  the  oils  of  bergamot  and  Ceylon  lemon-grass.  The  analy- 
sis of  this  remarkable  fluid  shows  its  formula  to  be  Q^^^^O  (and  not 
OisHjgO,  as  stated  by  Piesse  at  page  58  of  his  last  edition).  Its  boil- 
ing point  is  576°F.,  and  its  sp.  gr.  -910.  There  are  but  few  liquids 
which  give  a  colored  vapor  when  boiled,  but  azulene  is  one  of  them. 
Like  itself  its  vapor  is  blue.  It  is  soluble  in  and  imparts  its  color 
to  fatty  and  volatile  oils,  alcohol  and  many  other  liquids,  but  not 
water.  It  is  very  permanent,  and  bears  a  temperature  of  700°  to  800° 
F.  in  a  sealed  tube  without  alteration,  and  none  but  the  strongest 
acids  aided  by  heat  will  break  up  its  constitution.  It  is  most  intensely 
blue,  appearing  almost  black  when  in  a  concentrated  state.  It  is  not 
decolorized  by  sulphurous  acid,  sulphuretted  hydrogen,  or  bromine 
water.  It  does  not  attach  itself  to  animal  charcoal,  nor  does  it  dye 
wool,  cotton  or  silk.  It  has  been  found  to  exist  to  the  extent  of  6  per 
cent,  in  the  pure  oil. 
When  left  at  rest  oil  of  patchouli  deposits  a  crystalline  body,  known 
as  camphor  of  patchouli,  in  regular  hexagonal  and  pyramidal  prisms. 
The  composition  of  this  camphor  has  been  stated  as  C30H28O2  by  Gal 
(^'Bul.  de  la  Soc.  Chim.,"  1869,  p.  304),  but  by  Montgolfier  ("Comptes 
Rendus,''  January  8,  1877,  p.  88),  as  C36H26O2,  which  would  consti- 
tute it  an  isomer  of  camphor  of  cubebs  and  of  concrete  essence  of 
cedar.  The  conditions  most  favorable  to  the  formation  of  this  body 
are  little  known,  but  it  has  been  remarked  that  it  forms  more  rapidly 
in  samples  of  oil  which  have  been  desiccated  by  chloride  of  calcium. 
This  camphor  not  having  any  commercial  value  its  formation  is  unde- 
sirable, but  as  it  results  from  a  simple  molecular  change  it  may  be 
difficult  to  prevent  it;  however,  it  is  possible  that  the  presence  of  a 
small  quantity  of  water  in  the  oil  may  at  least  retard  it. 
The  difference  of  the  boiling  point  of  oil  of  patchouli  from  that  of 
oil  of  cedar  and  of  oil  of  cubebs  may  serve  as  a  guide  in  testing  a  sus- 
pected sample;  so  also  may  the  percentage  of  azulene. 
Volatile  oils  exhibit  great  diversity  in  their  action  on  polarized 
light,  some  being  dextro-,  others  Isevorotatory  in  various  degrees.  Ac- 
cording to  Gladstone  ("  Journ.  Chem.  Soc.,''  xvii.,  p.  3)  the  rotatory 
power  (determined  for  a  column  of  liquid  10  inches  long)  of  the  so- 
called  Penang"  oil  of  patchouli  is  — 120°,  the  same  for  cedar  wood 
oil  being  -|-3°.    The  hydrocarbon  of  patchouli  oil — patchoulene — 
