42 
Castor  Oil  Adulteration. 
Am.  Jour.  Pharm, 
Jan.,  1890. 
No.  1  contains  20  cc.  of  pure  castor  oil  and  40  cc.  of  petroleum 
ether. 
No.  2. — 20  cc.  of  castor  oil  containing  10  per  cent,  of  cocoanut  oil 
and  40  cc.  of  petroleum  ether. 
No.  3. — 20  cc.  of  castor  oil  containing  20  per  cent  of  cocoanut  oil 
and  40  cc.  of  petroleum  ether. 
These,  on  being  well  mixed  by  agitation  and  allowed  to  rest,  sep- 
arate into  portions  varying  with  the  amount  of  cocoanut  oil  present  in 
the  samples,  as  shown  in  the  following  table  : — 
Bottom  or  castor 
Petroleum 
ether  Total 
oil  layer. 
layer. 
measurement. 
No.  1 
36  cc. 
24  cc. 
60  cc. 
No.  2 
m " 
26£  " 
60  " 
No.  3 
30J  " 
29£" 
60  " 
I  have  already  referred  to  the  statement  found  in  text-books  to  the 
effect  that  castor  oil  is  insoluble  in  petroleum  ether,  and  promised  to 
demonstrate  that  such  was  not  the  case.  No.  1  sample  proves  my 
contention,  for  I  have  already  shown  that  in  mixing  20  cc.  each  of 
castor  oil  and  petroleum  ether,  37  cc.  of  the  castor  oil  mixture  sepa- 
rates, whilst  in  this  last  experiment  (No.  1  in  table)  only  36  cc.  of  the 
castor  oil  mixture  is  left,  showing  that  the  extra  20  cc.  of  petroleum 
ether  has  taken  up  some  of  the  castor  oil,  and  the  decrease  in  Nos.  2 
and  3  is  undoubtedly  due  to  the  fact  that  the  cocoanut  oil  is  dissolved 
out  by  the  petroleum  ether.  This  can  be  demonstrated  by  drawing 
off  the  upper  layer  and  driving  off  the  petroleum  ether,  when  the 
cocoanut  oil  containing  some  castor  oil  will  be  left. 
It  must  be  remembered  in  reading  this  table  that  the  lower  stratum 
is  a  mixture  of  castor  oil  and  petroleum  ether  in  nearly  equal  portions, 
and  that  the  diminution  in  bulk  in  Nos.  2  and  3  is  due  not  only  to 
the  abstraction  of  the  cocoanut  oil  by  the  petroleum  ether,  but  also  to 
the  fact  that  there  is  that  much  less  castor  oil  in  the  sample  to  com- 
bine with  the  ether,  so  that  the  lower  portion  will  show  a  decrease  in 
volume  from  these  two  causes  and  the  upper  one  a  corresponding 
increase. 
I  have  not  tried  this  experiment  with  a  sample  containing  more 
than  20  per  cent,  of  cocoanut  oil,  because  wTith  this  percentage  of 
adulteration  the  separation  of  the  two  layers  is  very  slow.  This  is 
due  to  the  peculiar  solvent  action  already  referred  to  in  connection 
