354 
Testing  of  Olive  Oil. 
f  Am.  Jour.  Pharm. 
1      July,  1883. 
THE  TESTING  OF  OLIVE  OIL. 
By  Dr.  O.  Bach. 
Abstracted  fro7n  C hem.  Zeitung  through  Seliw.  Wochenschrift  filr  Phar7n., 
No.  15  (1883),  pp.  139-142,  by  Dr.  Fred.  B.  Power. 
For  the  purpose  of  a  general  acquaintance  with'a  fixed  oil  the  so-called 
elaidin  test  is  first  applied,  and  with  this  is  connected  the  test  with 
nitric  acid.  The  oil  to  be  tested  (about  5  ccm.)  is  actively  shaken  in 
a  test-tube  for  one  minute  with  an  equal  volume  of  nitric  acid,  spec, 
grav.  1  *30,  when  after  this  time  tlie  oil  will  have  assumed  the  follow- 
ing color :  olive  oil,  pale  green ;  cotton  seed  oil,  yellowish  brown ; 
sesame  oil,  white ;  sunflower  oil,  dirty  white ;  ground  nut  oil,  rape 
seed  oil  and  ricinus  oil,  a  pale  rose  color.  Immediately  after  the 
observation  of  the  color  the  test-tube  is  placed  in  a  water-bath  con- 
taining water  in  active  ebullition,  and  allowed  to  repose  therein  for  5 
minutes.  It  is  hereby  shown  that  the  action  of  the  nitric  acid  is  most 
violent  upon  the  cotton  seed  oil  and  sesame  oil,  occasionally  so  violent 
as  to  cause  the  oil  to  be  thrown  out  of  the  glass.  After  the  expiration  of 
5  minutes,  and  after  the  test-tube  has  been  taken  out  of  the  water-bath, 
the  following  colors  are  shown :  olive  oil  and  rape  seed  oil,  orange- 
yellow ;  ricinus  oil,  golden -yell  ow ;  sunflower  oil,  reddish-yellow; 
sesame  and  ground  nut  oils,  brownish-yellow  ;  cotton  seed  oil,  reddish- 
brown. 
After  standing  for  12  to  18  hours  at  about  15°C.,  olive  oil,  rape 
seed  oil  and  ground  nut  oil  will  have  firmly  solidified,  ricinus  oil  and 
cotton  seed  oil  become  salve-like  (smeary),  whilst  sesame  oil  remains 
perfectly  liquid. 
Mixtures  of  olive  oil  with  small  amounts  of  cotton  seed  oil  and 
sesame  oil  are  thereby  characterized  that  at  first  indeed  the  entire 
mass,  although  more  darkly  colored,  solidifies  like  pure  olive  oil,  but 
after  from  24  to  36  hours  a  brown  oil  separates  upon  the  surface 
of  the  firmly  solidified  mass,  whilst  the  lower  layer  now  shows  the 
yellow  color  of  the  pure  olive  oil.  The  presence  of  oil  of  rosemary, 
as  such  usually  occurs  in  the  sophisticated  oils,  exercises  no  influence 
by  the  agitation  with  cold  nitric  acid,  but  after  heating  it  imparts  to 
the  oil  a  slightly  darker  color.  Oils  which  have  been  treated  with 
alkalies  show  the  same  behavior  as  pure  oils. 
For  the  determination  of  the  melting  point  of  the  fatty  acids,  10 
grams  of  the  oil  are  saponified  on  a  water-bath  with  5  grams  of  potas- 
