68 
PREPARATION  OF  OLEA  COCTA. 
the  fingers  they  may  be  easily  reduced  to  a  coarse  powder,  which 
readily  absorbs  the  oil.  In  the  heat  of  the  water  bath  all  the  oil 
soon  becomes  green,  and  when  after  one  or  two  hours,  according 
to  the  quantity  employed,  the  fat  has  extracted  all  color,  the  ope- 
ration may  be  looked  on  as  finished.  In  this  manner  the  olea 
cocta,  which  ought  to  be  called  now  olea  infusa,  are  prepared  by 
the  Pharm.  Wurttemb.,  and  as  we  understand  the  Pharm.  Ba- 
varia, which  is  to  be  published  in  a  short  time,  will  adopt  the 
same  process. 
Some  pharmaceutists  have  chosen  to  obtain  these  oils  by  dis- 
placements from  the  dry  herbs.  E.  Krause  (Zeitschr.  J.  Pharm. 
1853,  No.  7,)  reduces  the  herb,  previously  dried  in  a  moderate 
heat,  to  a  coarse  powder,  moistens  it  with  strong  alcohol,  in 
sufficient  quantity  to  press  it  down,  and  after  letting  it  stand  full 
a  day,  well  covered,  transfers  it  to  a  percolator,  pouring  upon  it 
the  right  quantity  of  oil.  After  the  oil  has  been  all  absorbed 
by  the  powder,  he  puts  a  layer  of  washed  sand  on  top,  to  dis- 
place by  water  the  last  quantity  of  oil,  taking  care,  however, 
not  to  get  it  mixed  with  the  aqueous  extractive  matter.  Thus 
prepared  the  oil  has  the  odor  of  the  herb  in  a  high  degree,  is  of 
a*  dark  brownish  green  color,  and  keeps  very  long  without  get- 
ting rancid. 
It  is  unnecessary  to  heat  the  oil,  to  drive  off  the  alcohol,  as 
after  standing  it  collects  on  the  bottom,  and  serves  to  keep  the 
oil  from  becoming  rancid.  Small  quantities,  such  as  oleum 
cantharides  for  ung.  canthar.  may  be  prepared  in  the  same  way 
in  a  suitable  funnel.  Oil  of  cantharides  is  said  to  become 
stronger  and  better  if  ether  or  chloroform  be  used  for  moisten- 
ing in  place  of  alcohol. 
A  similar  formula  was  published  by  H.  Gerste  (Zeitschr  J. 
Pharm.  1854,  No.  8).  One  pound  troy  he  moistens  with  6  oz. 
spir.  vini  rect.,  and  then  gradually  pours  on  the  necessary  quan- 
tity of  oleum  olivarum  ;  the  obtained  oil  is  to  be  heated  for  a 
short  time  in  the  steam  apparatus,  till  all  the  alcohol  has  evapo- 
rated and  the  oil  is  clear. — Buchners  N.  Repert.  1854,  223-225. 
