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ESSENTIAL  OIL  OF  VALERIAN.  141 
together,  give  between  200°  and  280°,  a  very  fluid,  transparent, 
slightly  green,  oily  body,  smelling  like  hay  or  the  camphor  of 
the  labiates  :  this  is  the  valerol  of  Gerhardt.  It  contains  still  a 
little  acid.  Redistillation  renders  it  colorless,  and  makes  the 
odor  softer  and  sweeter.  Gerhardt  calls  this  neutral  rectified 
valerol.  It  is  important  to  remark  that  it  can  only  be  really 
rectified  by  distilling  it  in  contact  with  a  strong  base,  which  will 
remove  the  acid  it  always  contains.  In  this  way  only  we  obtain 
a  neutral  product  which  no  influence  will  change  into  valerianic 
acid. 
During  the  last  distillation,  between  200°  and  280°,  there 
condenses  in  the  retort  tube  a  crystalline  volatile  matter  smell- 
ing like  camphor  :  this  is  the  steareoptene  of  valerian  to  which 
we  shall  presently  return. 
Such  are  the  different  bodies  obtained  from  the  oil,  simply  by 
means  of  heat,  and  we  see  that  valerianic  acid  is  always  present, 
and  is  found  even  in  the  last  products  of  decomposition. 
If  now  we  distil  the  freshly  prepared  oil  off  solid  potassa,  in  a 
tubulated  retort  furnished  with  a  thermometer,  gradually  in- 
creasing the  heat  up  to  200°,  there  passes  an  almost  colorless 
oil,  which  smells  something  like  oil  of  turpentine.  At  200°  the 
distillation  stops  spontaneously.  Some  aqueous  vapor  is  disen- 
gaged, and  the  oxygenated  oil  retained  by  the  potassa  concretes, 
and  assumes  an  odor  like  camphor.  The  result  of  this  first  dis- 
tillation is  the  hydrocarbon  (C20H16)  contained  in  the  oil.  In 
this  operation,  which  I  have  often  repeated,  I  have  never  ob- 
served the  crystalline  matter  which  Gerhardt  sometimes  met 
with  ;  it  is  only  above  210°  and  at  the  expense  of  the  oxy- 
genated oil  that  this  body  is  produced,  as  we  shall  see  further 
on,  Gerhardt  gave  the  name  borneene  to  the  hydrocarbon,  but 
I  prefer  to  call  it  valerene.  When  it  is  pure  it  boils  at  160°, 
and  evaporates  without  leaving  a  residue. 
The  valerianic  acid  originally  contained  in  the  oil  is  combined 
with  the  potassa ;  but  the  oxygenated  oil  has  by  no  means  pro- 
duced it,  as  Gerhardt  wishes  to  show. 
If  now,  after  having  changed  the  receiver,  we  continue  to 
heat  the  oil  which  was  solidified  on  the  potassa,  it  gradually 
liquefies,  and  begins  to  distil  at  210°  ;  boiling  directly  that 
temperature  is  reached.    At  280°  the  distillation  stops  again, 
