OLEUM  ^THEEBUM. 
57 
OLEUM  ^THEREUM. 
By  Edward  R.  Squibb,  M.  D.,  of  Brooklyn,  New  York. 
"  What  are  the  changes  which  occur  in  the  officinal  Ethereal  Oil  (U.  S.  P.) 
by  keeping  ;  and  can  these  changes  be  retarded  ?" 
The  above  inquiry  embraces  two  distinct  questions  ;  and  in 
order  to  answer  them  separately  with  a  useful  degree  of  accuracy, 
a  number  of  experiments  were  commenced  soon  after  the  last 
session  of  the  Association.  The  result  of  these  experiments, 
together  with  deductions  from  former  experiments  and  observa- 
tions, lead  the  writer  to  the  conclusions  now  to  be  given. 
"  What  are  the  changes  which  occur  in  the  officinal  Ethereal  Oil  by  keep- 
ing?" 
The  sensible  changes  are  a  separation  into  two  unequal  strata. 
The  upper  one  of  these  is  commonly  the  smaller, — is  of  a  deep 
brownish  straw  color, — of  an  oily  character  and  consistence, — ■ 
much  lighter  than  water,  and  not  miscible  with  water,  having  a 
fragrant  aromatic  odor  resembling  pennyroyal,  and  a  somewhat 
pungent  highly  aromatic  taste  resembling  essential  oil  of  penny- 
royal. It  is  slightly  acid  to  litmus  paper  at  first  contact,  but 
becomes  strongly  acid  after  a  short  exposure  to  air  upon  the 
paper,  and  is  soluble  in  strong  alcohol. 
The  lower  and  commonly  the  largest  stratum  is  of  a  dark 
brown  color,  so  dark  as  to  be  quite  opaque, — is  not  of  an  oily 
character, — is  much  heavier  than  water,  and  when  dropped  into 
water  separates  into  oily  globules  which  sink  to  the  bottom,  and 
a  soluble  portion  which  dissolves  and  renders  the  water  acid.  It 
has  a  fruity  apple-like  odor^  and  a  pungent  acid  taste.  It  is  acid 
to  litmus  paper,  effervesces  with  carbonates,  precipitates  baryta 
and  lime  salts  even  in  the  presence  of  sulphurous  acid,  and  car- 
bonizes organic  matter  when  heated  upon  it.  It  is  insoluble  in 
strong  ether,  but  is  rendered  soluble  by  the  addition  of  a  small 
proportion  of  the  upper  stratum. 
Both  the  upper  and  lower  strata  are  soluble  in  the  spirit  of 
ether  used  for  the  compound  spirit  of  ether,  whether  added  in 
succession  or  together  ;  and  when  both  are  added  they  appear  to 
reunite  and  form  a  compound  spirit  that  is  not  sensibly  different 
from  that  made  from  freshly  prepared  oil,  except  that  it  is  very 
slightly  tinged  with  a  brownish  color,  and  is  slightly  acid  to 
litmus  paper. 
