220  Some  Notes  on  Essential  Oils.  jAffiM™yr;iP£rm' 
ent  chemical  composition  and  consequently  differs  in  physical  prop- 
erties. It  has  been  observed,  for  instance,  that  with  the  ripening  of 
the  fruit  the  ester  content  or  the  oil  increases  while  the  amount  of 
linalool  decreases.  The  amount  of  terpene  also  increases,  while  the 
relation  of  the  limonene  to  dipentene  remains  about  the  same. 
Charabot  (quoted  by  Kremers  and  Brandel,  Pharm.  Rev.,  1902, 
p.  305)  concludes  that  linalool  is  first  formed  and  converted  by  the 
free  acetic  acid  to  ester  on  the  one  -hand  and  terpene  on  the  other. 
According  to  Schimmel  &  Co.,  the  specific  gravity  of  oil  of  ber- 
gamot  should  be  from  0-883  t0  0-886.  The  requirements  of  the  vari- 
ous national  Pharmacopoeias  vary,  according  to  the  Universal  Phar- 
macopoeia, from  a  minimum  of  0  860  in  the  Austrian  to  a  maximum 
of  0*890  in  the  National  Pharmacopoeia  of  Switzerland,  the  limit  in 
our  own  United  States  Pharmacopoeia  being  from  o-88o  to  0-885. 
Gildemeister  and  Hoffmann  describe  oil  of  bergamot  as  being  a 
brownish  yellow  or  honey-colored  liquid  that  is  often  colored  green 
by  the  presence  of  copper.  It  might  be  stated  here  that  Parry,  on 
the  other  hand,  appears  to  think  that  the  green  color  is  due  to 
dissolved  chlorophyll. 
Oil  of  bergamot  is  said  to  be  frequently  adulterated  with  oil  of 
sweet  orange  or  oil  of  lemon.  Either  of  these  oils  would  have  a 
tendency  to  reduce  the  specific  gravity  and  at  the  same  time 
increase  the  angle  of  optical  rotation.  The  optical  rotation  of  oil  of 
bergamot  is  stated  by  Schimmel  &  Co.  to  be  from  plus  9  to  plus  15. 
An  interesting  possibility  in  this  connection  is  the  marketing  by 
Schimmel  &  Co.  of  an  80  per  cent,  linalyl  acetate.  Oil  of  bergamot 
seldom  contains  more  than  40  per  cent,  of  linalyl  acetate. 
While  the  price  of  the  stronger  product  is  at  the  present  time 
almost  prohibitive,  the  manufacturers  think  that  for  certain  purposes 
it  would  be  of  advantage  on  account  of  the  absence  of  color  and  the 
much  smaller  quantity  that  would  be  required. 
Oil  of  Lemon. — The  specific  gravity  of  oil  of  lemon,  according 
to  Schimmel  &  Co.,  is  from  0-858  to  o*86i;  in  this  the  upper  limit 
of  the  U.S.P.  is  rather  lower,  being  0-859. 
The  optical  rotation  is  given  as  from  plus  59  to  plus  67.  Burgess 
and  Child  (quoted  by  Schimmel  &  Co.)  say  that  up  to  the  present 
time  the  following  constituents  have  been  found  in  oil  of  lemon  : 
pinene,  phellandrene,  limonene,  citral,  octyl  and  nonyl  aldehydes, 
geranyl  acetate,  geraniol,  methyl  ester  of  anthranilic  acid,  citronellol, 
