226 
Olive  Oil. 
Am.  Jour.  Pharra. 
May,  1889. 
shortly  after  its  reception  did  not  give  any  reaction,  but  recently  exam- 
ined gave  a  purple  color. 
Elaidin  reaction.  10  cc.  oil  agitated  every  ten  minutes  for  two 
hours  with  0*4  cc.  of  a  solution  of  1  cc.  mercury  in  12  cc.  cold  nitric 
acid,  sp.  gr.  1*42. 
Temperature  turbidity.  3  cc.  oil  and  3  cc.  glacial  acetic  acid  (99.5 
per  cent.)  were  heated  until  perfect  solution  ensued,  when  a  thermome- 
ter was  introduced  and  the  temperature  noted  at  which  the  lower 
portions  became  distinctly  turbid.  The  higher  temperature  obtained 
for  olive  oil  by  E.  Yalenta  and  quoted  in  Allen's  Organic  Analysis 
may  be  due  to  the  use  of  a  weaker  acid ;  in  this  country,  it  is  stated, 
an  eighty  per  cent,  acid  is  very  often  sold  as  "  glacial. "  This  test  is 
especially  important  as  a  means  of  detecting  cruciferous  oils  which  are 
not  soluble  in  the  acid  even  at  its  boiling  point. 
Free  acid  and  saponification  equivalent  determined  in  the  same  test 
by  first  adding  to  a  weighed  portion,  2  to  3  gni.  in  a  flask,  10  cc. 
neutral  alcohol,  boiling  and  titrating  with  approximately  semi-normal 
alcoholic  potassium  hydrate,  using  phenolphthalein  as  indicator,  until 
a  permanent  red  color  after  agitation  is  obtained ;  the  acidity  is  calcu- 
lated as  oleic  acid.  An  excess  of  the  alkaline  solution  is  now  added 
(the  balance  of  25  cc),  the  flask  connected  with  an  inverted  condenser 
and  heated  in  a  water- bath  for  one-half  hour,  after  addition  of  a  little 
snore  indicator  the  excess  of  KOH  is  determined  with  oxalic  acid 
{12.6  gm.  per  litre) ;  the  difference  between  the  oxalic  acid  required  in 
this  experiment  and  that  required  in  a  blank  experiment  (carried  out 
without  the  oil)  represents  the  acid,  as  oxalic  acid,  necessary  to  decom- 
pose the  oil ;  to  obtain  the  saponification  equivalent,  which  is  the 
amount  of  oil  decomposed  by  56.1  parts  KOH  or  63  parts  oxalic  acid, 
the  weight  of  oil  taken  is  multiplied  by  500  and  the  product  divided 
by  the  number  of  cc.  of  oxalic  acid  of  above  strength  gotten  as 
the  difference  between  the  actual  and  blank  experiments.  Oxalic 
acid  was  used  because  it  can  be  obtained  of  such  purity  that  it  does 
not  require  the  repeated  trials  in  standardizing ;  there  is  a  precipi- 
tate of  oxalate  of  potassium  formed  at  the  beginning  of  the  titra- 
tion, but  as  the  alcohol  becomes  more  dilute,  by  the  addition  of  the 
aqueous  oxalic  acid,  this  redissolves  and  there  is  no  trouble  in  as- 
certaining the  end  of  the  titration,  the  yellow  color  succeeding  the  red 
sharply. 
Iodine- absorption  represents  the  percentage  of  iodine  absorbed  by 
