290  Cotton  Oil  in  Olive  Oil,  {^"'june'S""'- 
METHODS  FOR  DEFIKHTELY  PROVING  THE  PRESENCE  OF 
COTTON  OIL  OR  OF  OIL  OF  SESAME  IN  OLIVE  OIL^ 
By  M.  Milliau. 
The  author  has  applied  Becchi^s  test  {Amer.  Jour.  Phar.,  1887,  p.  280), 
based  upon  the  reducing  action  of  cotton  oil  upon  argentic  nitrate,  but 
he  finds  that  some  varieties  of  the  pure  olive  oil  give  a  slight  reduc- 
tion, owing  to  certain  causes  which  he  points  out.  If,  however,  the 
fatty  acids  be  first  separated  and  the  test  be  then  applied  to  them,  the 
acids  from  pure  olive  oil  giv^e  no  reduction,  while  those  from  cotton 
oil  always  reduce  the  silver.  On  this  assumption  he  has  based  the 
following  process  : — Place  15  cc.  of  the  oil  into  a  porcelain  basin  and 
warm  it  up  to  110°  C.  Make  a  mixture  of  15  cc.  of  a  solution  of 
sodium  hydrate  (40  degrees  Baume)  with  15  cc.  of  alcohol  of  92  de- 
grees, and  add  this  solution  very  gradually  to  the  heated  oil,  taking 
care  that  the  temperature  is  maintained  during  the  process.  AVhen  a 
homogeneous  mass  has  been  obtained,  distilled  water  is  added  drop  by 
drop,  so  as  not  to  cool  the  paste  or  to  form  clots,  and  this  is  continued 
until  500  cc.  of  water  have  been  introduced.  The  whole  having  been 
boiled  for  a  few  minutes,  dilute  sulphuric  acid  (1  in  10)  is  added,  so 
as  to  produce  a  slight  excess  of  acidity  and  the  fatty  acids  are  thus  ob- 
tained floating  on  the  surface.  The  author  does  not  seem  to  consider 
it  necessary  to  wash  these  acids,  but  he  simply  removes  about  5  cc.  by 
means  of  a  silver  spoon,  and  puts  this  amount  of  the  separated  acids 
into  a  test  tube  wath  20  cc.  of  alcohol,  and  warms  until  dissolved.  To 
this  liquid  he  adds  2  cc.  of  a  30  per  cent,  solution  of  argentic  nitrate, 
and  heats  the  whole  on  the  water  bath  until  about  one-third  of  the 
fluid  is  evaporated  off,  when  the  test  is  complete.  If  the  olive  oil  be 
pure,  the  fatty  acids  remain  unaltered,  but  if  cotton  oil  be  present  the 
acids  float  to  the  surface  as  a  black  paste.  By  this  method  the  author 
has  easily  detected  a  one  per  cent,  adulteration. 
For  Sesame  Oil. — To  recognize  the  presence  of  this  oil  in  olive  oil, 
the  author  finds  that  Baudouin's  reagent  is  the  best,  but  here  also  a 
pure  oil  may  be  unjustly  condemned  when  working  on  the  oil  itself. 
If,  however,  the  separation  of  the  fatty  acids  be  first  carried  out,  the 
results  are  accurate.  In  this  case,  after  saponification  and  separation 
of  the  acids,  they  must  be  perfectly  dried  at  110°  C.  They  are  then 
put  into  a  tube  and  shaken  up  with  Baudouin's  reagent  (hydrochloric 
acid  and  sugar),  when  the  characteristic  red  color  will  be  produced. 
1  Arch,  de  Fharm.,  3,  161.   Reprinted  from  The  Analyst,  May,  1888,  p.  95. 
