AmM°aUyr;i9oh3?rm-}       Some  Notes  on  Essential  Oils.  221 
citroptene  and  a  resin.  The  principal  odoriferous  agent  is  probably 
citral,  while  octyl  and  nonyl  aldehydes,  though  present  in  only 
small  quantities,  play  a  very  important  part  in  the  aroma. 
For  a  satisfactory  examination  of  lemon  oil  the  same  authors  con- 
sider the  following  data  important: 
(1)  Specific  gravity  at  150  C,  from  0-856  to  o-86o. 
(2)  Optical  rotation  power  in  a  100  mm.  tube  fluctuates  from 
plus  58  to  plus  63. 
(3)  Index  of  refraction  at  200  C.  by  means  of  Abbe's  refracto- 
meter ;  this  fluctuates  from  1-4733  to  1-4830;  normal  about 
1*4755- 
(4)  The  determination  ol  the  citral  content,  or  the  total  content 
of  aldehydes  in  25  c.c.  of  the  oil:  Citral  content  from  4  to  7  per 
cent. 
(5)  Submit  the  oil  to  fractional  distillation. 
The  principal  adulterants  of  oil  of  lemon  are  lemon  oil  terpenes, 
turpentine,  lemon  grass  citral,  and  occasionally  distilled  lemon  oil. 
Oil  of  Limes. — This*oil,  according  to  the  reports  of  the  Treasury 
Department,  is  becoming  quite  an  important  commercial  article. 
There  are  two  distinct  varieties  of  oil  of  lime  ;  the  one  from  the 
West  India  Islands,  consisting  largely  of  limonene  and  citral,  has  a 
specific  gravity  of  from  o-88o  to  0  88 5.  This  oil  is  obtained  from 
the  fruit  of  citrus  medica,  var.  acida  Brandes. 
Italian  oil  of  limes,  according  to  Hoffmann  and  Gildemeister,  is 
obtained  from  the  fruit  of  citrus  limetta,  Risso,  and  is  an  oil  of  brown, 
ish-yellow  color,  having  an  odor  somewhat  resembling  oil  of  berga- 
mot.  The  composition  of  this  oil  also  resembles  oil  of  bergamot, 
in  that  it  contains  linalyl  acetate  (about  25  per  cent.),  linalool 
and  limonene.  Italian  oil  of  limes  has  a  specific  gravity  of  about 
0-872. 
Oil  of  Orange  Flowers. — According  to  Gildemeister  and  Hoff- 
mann, the  specific  gravity  of  this  oil  should  be  between  0-870  and 
o  880.  The  natural  oil  contains  linalyl  acetate,  linalool,  limonene, 
methyl  ester  of  anthranilic  acid,  geraniol  and  paraffin.  In  order  to 
obtain  an  oil  of  neroli  that  is  at  all  normal,  it  is  necessary  to  distil 
the  flowers  for  the  oil  alone,  and  not,  as  is  often  the  practice,  collect 
the  oil  as  a  by-product  in  the  manufacture  of  orange-flower  water. 
According  to  recent  reports  of  Schimmel  &  Co.,  the  quality  of  the 
natural  oil  is  of  much  less  importance  now  than  formerly.  They  also 
