545 
Essential  Oil  of  Orange, 
J  Am.  Jour.  Phabm. 
\     Dec.  1, 1873. 
cent.)  distils  below  180°  ;  a  small  quantity  of  an  oxidized  constituent 
boiling  near  220°  is  contained,  possessing  the  composition  C10H16O  ; 
'and  a  non-volatile  soft  resin  is  also  contained  giving  numbers  on 
analysis  agreeing  with  the  empirical  formula  C20H30O3,  together  with 
another  oxidized  substance  of  high  boiling  point,  a  portion  distilling 
at  240° — 250°,  agreeing  with  the  empirical  formula  C40H64O5. 
The  oxidized  constituent  C10H16O  is  possessed  of  the  property  of 
becoming  altered  by  heat  forming  an  isomeric  liquid  of  higher  boil- 
ing point,  and  finally  becoming  a  non-volatile  resin,  no  change  in  its 
composition  being  thereby  produced  :  in  this  respect  it  resembles  an 
analogous  (or  identical  ?)  substance  contained  in  oil  of  nutmegs. 
The  portion  boiling  below  180°  yields,  on  distillation  over  sodium, 
a  hydrocarbon,  C10H16,  boiling  constantly  at  178°,  and  apparently 
consisting  of  one  homogeneous  substance,  no  trace  of  cymene  being 
apparently  present.  Many  other  natural  terpenes  (e.  g.,  the  terpene 
of  turpentine  oil  and  that  of  nutmeg  oil)  are  not  pure  terpenes,  having 
been  found  to  contain  cymene,  C10HU,  as  well  as  a  C10H16  hydrocar- 
bon. 
When  two  equivalents  of*  bromine  are' cautiously  added  to  the  ter- 
pene of  orange  oil  (hesperidene)  combination  takes  place  with  evolu- 
tion of  heat  ;  the  product  breaks  up  on  distillation,  forming  hydro- 
bromic  acid  and  cymene,  thus — 
C10H16Br2  =  2  HBr  +  C10HU. 
The  cymene'^thus  formed  is  identical  with  that  contained  in  cumin 
oil  and  with  that  obtainable  from  camphor,  yielding  on  oxidation  tere- 
phthalic  acid  and  acetic  acids  without  admixture  with  isophthalic  acid 
or  higher  homologues  of  acetic  acid  ;  the  original  hydrocarbon  hesperi- 
dene, when  similarly  oxidized,  gives  acetic  acid,  but  no  trace  of  tere- 
phthalic  acid. 
If  the  oxidation  be  not  carried  to  its  limit,  the  action  of  chromic 
acid  on  hesperidene  gives  rise  to  a  small  quantity  of  a  substance, 
C10H16O,  which  resembles  in  all  respects  save  odor  the  body  of  that 
composition  contained  in  the  original  oil ;  probably  therefore  that 
body  is  formed  by  the  spontaneous  oxidation  of  the  hydrocarbon ;  or 
possibly  the  hydrocarbon  is  produced  by  the  natural  deoxidation  of 
this  oxidized  substance. 
Action  of  Nitric  Acid  on  Hesperidene. — This  action  is  very  ener- 
getic, the  resulting  substances  being  carbon  di-oxide  and  nitrous  red 
fumes,  oxalic  acid  and  a  new  body,  hesperisic  acid,  being  formed: 
