COLORING  PRINCIPLE  OF  VOLATILE  OILS,  ETC.  87 
of  potash.*  On  the  20th,  an  entire  worm  was  expelled  with  the 
head.  Four  days  after  taking  the  medicine,  the  patient  present- 
ed a  jaundiced  appearance. — Dublin  Med.  Press,  May  27,  1863, 
from  Archiv  fur  Pathol.  Anal,  und  Phys. 
ON  THE  COLORING  PRINCIPLE  OF  VOLATILE  OILS  AND  A 
NEW  BODY,  AZULENE. 
Br  Septimus  Piesse,  F.  C.  S. 
It  is  generally  known  that  essential  oils  or  ottoes  of  plants 
have  peculiar  and  characteristic  colors,  they  are  either  yellow, 
blue,  green,  brown,  or  white,  i.  e.  colorless. 
Having  made  some  progress  towards  the  discovery  of  the 
nature  of  the  matters  which  impart  these  several  colors,  I  now 
record  the  facts  ascertained. 
The  principal  interest  rests  with  the  blue  substance  which 
gives  color  to  the  otto  of  chamomile,  because  the  same  body  is 
present  in  other  volatile  oils,  and  imparts  to  them  a  green  color, 
being  at  the  time  under  disguise  by  a  yellow  resin,  which  is  also 
present  in  volatile  oils  of  a  green  tint. 
When  blue  otto  of  chamomile  is  subjected  to  fractional  distil- 
lation, the  white  hydrocarbon  anthemidine  is  easily  separated 
from  the  blue  coloring,  because  the  latter  requires  a  much  higher 
temperature  to  vaporize  it  than  the  former. 
By  the  fractional  distillation  of  otto  of  wormwood,  Absinthii, 
I  obtain  first  a  nearly  colorless  hydrocarbon,  then  at  the  third 
fractioning  an  oil  having  a  brilliant  green  color,  which  at  the 
fifth  fractioning  divides  into  a  blue  oil  and  a  residuary  yellow 
resin. 
When  otto  of  Patchouly,  obtained  by  distilling  with  water 
the  Indian  herb  Pogostemon  Patchouly,  is  subjected  to  fractional 
distillation,  I  obtain  in  like  manner,  first  a  colorless  hydrocar- 
bon, then,  but  not  till  the  eleventh  fractioning,  a  beautiful  blue 
oil  and  a  brown-yellow  residue  ;  the  great  number  of  fraction- 
ings  required  to  separate  the  blue  oil  in  this  case  is  caused  by 
the  closer  boiling-points  between  the  patchouly  hydrocarbon,  the 
blue  oil,  and  the  resin,  all  of  which  are  exceedingly  high.  The 
[This  is  also  known  as  picrate,  nitropicrate  and  carbazotate  of  potassa. 
The  acid  is  made  from  coal  tar  creosote,  from  Australian  gum,  and  from 
oil  of  wine  wintergreen.  A  short  notice  of  it  will  be  found  in  the  appendix 
of  the  U.  S.  Disp.  11th  Edition.— Ed.  Am.  J.  Ph.] 
