40 
Castor  Oil  Adulteration. 
Am.  Jour.  Pharm. 
Jan.,  1890. 
way  into  pharmacy,  I  have  thought  it  worth  while  to  bring  these 
facts  forward,  and  to  give  the  results  of  my  experience  as  to  the 
best  means  of  detecting  and  estimating  the  adulterant. 
The  test  given  in  the  British  Pharmacopceia  is  that  it  is  "en- 
tirely soluble  in  one  volume  of  absolute  alcohol  and  in  two  vol- 
umes of  rectified  spirit,"  Now  this  test  is  quite  useless  for  the  de- 
tection of  cocoanut  oil  or  any  other  possible  adulterant,  because 
oils  that  are  insoluble  in  both  absolute  alcohol  .and  rectified  spirit 
are  soluble  in  a  mixture  of  either  with  castor  oil,  and  I  have  pre- 
pared samples  of  castor  oil  containing  10  to  20  per  cent,  of  cocoa- 
nut  oil  which  are  as  freely  soluble  in  these  solvents  as  is  castor  oil 
itself.  On  the  other  hand,  I  have  never  yet  met  with  a  sample  of 
castor  oil,  one  volume  of  which  would  dissolve  in  two  volumes  of 
rectified  spirit  of  the  Pharmacopceia  strength,  viz,,  specific  gravity 
•838  at  60°  F.  With  the  thermometer  at  70°  to  80°  F.,  solution 
does  take  place,  but  not  at  60°  F.  With  spirit  of  specific  gravity  '830, 
one  volume  of  castor  oil  dissolves  perfectly  in  two  volumes  at  60°  F., 
so  that  it  will  be  seen  that  by  either  increasing  the  temperature,  or  by 
using  spirit  a  few  degrees  stronger,  solution  does  take  place  ;  but  even 
with  this  alteration  the  test  will  only  serve,  as  has  already  been  shown, 
to  detect  adulterants  outside  of  certain  limits.  Castor  oil  is  also  soluble 
in  glacial  acetic  acid,  while  all  other  fixed  oils,  with  the  exception  of 
croton  oil,  are  insoluble.  This  test  is  given  in  some  works,  but  I  find 
the  same  objection  to  it  that  I  have  previously  mentioned  in  connec- 
tion with  the  Pharmacopceia  test,  for  notwithstanding  the  fact  that 
other  oils  per  se  are  insoluble,  they  are  rendered  soluble  when  mixed 
with  castor  oil  within  certain  limits. 
The  chief  distinguishing  features  of  castor  oil  are  undoubtedly  its 
high  density  and  its  insolubility  in  petroleum  ether  (benzolene)  when 
compared  with  other  fixed  oils.  We  find  it  stated  in  text  books  that 
castor  oil  is  insoluble  in  petroleum  ether,  of  which,  however,  it  has  the 
peculiarity  of  dissolving  its  own  volume.  This  statement  is  not  cor- 
rect, for  I  shall  show  you  that  castor  oil  is  to  a  certain  extent  soluble ; 
also,  that  under  a  certain  temperature  castor  oil  will  not  dissolve 
its  own  volume  of  petroleum  ether. 
This  latter  feature,  I  find,  affords  trustworthy  proof  of  the  presence 
or  absence  of  any  other  fixed  oils. 
The  following  experiment  was  made  with  samples  of  East  Indian, 
French  and  Italian  castor  oil,  each  giving  practically  the  same  result. 
