26 
Adulteration  of  Olive  Oil 
(  Am.  Jour.  Pharm. 
X      Jan.,  1883. 
mixture  is  then  agitated  with  a  silver  spatula  which  becoming  black 
indicates  the  presence  of  an  oil  from  one  of  the  cruciferous  plants,  con- 
taining sulphur. 
2.  Sesame  Oil. — To  the  oil  which  is  to  be  examined  there  is  added 
equal  parts  of  hydrochloric  acid  of  23°,  then  strongly  agitated.  The 
presence  of  the  sesame  oil  is  shown,  no  matter  how  small  the  quantity 
is,  by  a  red  coloration  which  is  produced  and  remains,  when  allowed 
to  rest,  at  the  bottom  of  the  liquid. 
3.  Cottonseed  Oil. — To  the  suspected  sample  of  oil  there  is  added 
an  equal  volume  of  nitric  acid  of  40°.  When  the  mixture  is  strongly 
agitated  it  assumes  a  cafe  au  lait  color,  more  or  less  dark. 
4.  Peanut  Oil. — The  presence  of  this  adulterant  is  difficult  of  detec- 
tion, but  if  the  operation  is  slightly  complicated  the  fraud  is  not  of 
frequent  occurrence  on  account  of  the  disagreeable  taste  of  the  product. 
In  this  case  the  oil  to  be  examined  is  treated  by  an  alcoholic  solution 
of  j)otassium  hydrate.  The  saponified  mass  thus  obtained  is  heated  in 
order  to  drive  off  the  alcohol,  then  it  is  treated  with  a  quantity  of 
hydrochloric  acid  sufficient  to  neutralize  the  potash.  The  fatty  body 
which  floats  on  the  surface  is  arachic  acid.  This  is  collected  and  dis- 
solved in  boiling  alcohol  from  which,  when  cooled,  the  arachic  acid  is 
thrown  down  as  a  white  mother-of-pearl  precipitate,  which  is  readily 
recognized. 
Such  are  the  ordinary  tests  that  are  used  in  the  municipal  laboratory 
at  Marseilles  for  the  detection  of  adulterations  in  olive  oil.  To  the 
above  we  add  a  few  other  adulterants  giving  the  ordinary  and  easiest 
methods  for  their  detection.- 
The  adulteration  by  poppy  oil  is  of  quite  frequent  occurrence  in  the 
north  of  France,  on  account  of  the  cheapness  of  this  article ;  its  neutral 
and  soft  taste  makes  its  presence  almost  unnoticeable  in  a  fraudulent 
mixture. 
A  good  test,  based  on  the  difference  of  the  viscosity  of  the  two  oils, 
consists  of  the  introduction  with  rapid  agitation  of  bubbles  of  air  into 
the  suspected  oil.  If  it  is  pure,  the  bubbles  will  quickly  pass  off.  In 
ihe  contrary  case,  they  go  to  the  surface,  and  there  they  remain  during 
a  greater  or  shorter  period,  forming  a  wreath. 
If  the  mixture  is  heated  to  boiling,  the  poppy  oil  becomes  covered 
with  an  abundance  of  froth,  a  circumstance  which  does  not  happen 
to  pure  olive  oil.  The  freezing  by  means  of  a  refrigerating  mixture 
likewise  offers  a  method  of  testing.    The  pure  olive  oil  freezes  between 
