444 
ESSENTIAL  OIL  OF  LEMONS. 
and  carbonate  of  potash  remains,  mixed  with  a  potash  salt  of  a 
volatile  fatty  acid.  The  odor  which  the  acid  evolves  when  set 
free  from  the  potash  with  diluted  sulphuric  acid,  leads  to  the  con- 
clusion that  this  acid  is  a  mixture  of  caprylic  and  pelargonic 
acids. 
The  oil  which  passed  over  during  this  reaction,  and  resembles 
the  previously  mentioned  one  (A),  boils  between  347°  and  356°, 
and  has  the  formula  C5H4.  It,  therefore,  belongs  to  the  large  class 
of  camphenes. 
The  portion  B  of  the  crude  oil  was  subjected  to  fractional  dis- 
tillation, and  the  part  which  passed  over  at  410°,  during  which 
the  thermometer  was  constant  for  a  short  time,  consisted  of  C20H18 
02.  This  oxygenated  oil  is  in  the  crude  oil  undergoing  continuous 
oxidation,  and  dries,  when  exposed  in  a  watch  glass  to  the  air,  at 
last  to  a  gummy  mass. 
This  oil  is  isomeric  with  Borneo  camphor,  oils  of  cajeput  and 
bergamot,  and  with  the  aldehyde  of  campholic  acid  C20H18O4. 
I  have  made,  in  conjunction  with  Dr.  Bibra,  researches  on  ani- 
mals, to  ascertain  whether  the  oil  of  hops  has  a  narcotic  action, 
and  find  that  it  has  no  such  action. — Journal  fur  Pracktische 
C/temie,  from  Annals  of  Pharmacy,  June,  1853. 
ON  THE  ESSENTIAL  OIL  OF  LEMONS. 
By  John  S.  Cobb. 
(Read  before  the  Chemical  Discussion  Society.) 
I  have  recently  made  some  experiments  with  oil  of  lemons,  of 
which  the  following  is  a  short  account : — 
Being  constantly  annoyed  by  the  deposit  and  alteration  in  my 
essence  of  lemons,  I  have  tried  various  methods  of  remedying  the 
inconvenience. 
I  first  tried  redistilling  it,  but  besides  the  loss  consequent  on  dis- 
tilling small  quantities,  the  flavor  is  thereby  impaired.  As  the  oil 
became  brighter  when  heated,  I  anticipated  that  all  its  precipita- 
ble  matter  would  be  thrown  down  at  a  low  temperature,  and  I  ap- 
plied a  freezing  mixture,  keeping  the  oil  at  zero  for  some  hours. 
No  such  change,  however,  took  place. 
The  plan  which  I  ultimately  decided  upon  as  the  best  which  I 
had  arrived  at,  was  to  shake  up  the  oil  with  a  little  boiling  water, 
