Am.  Jour.  Pharm.1 
August,  1887.  J 
Characteristics  of  Olive  Oil. 
421 
The  determination  of  the  non-saturated  fatty  acids  by  treating  the 
non-saponified  oil  with  bromine  or  iodine  gave  no  concordant  results. 
The  following  method  is  satisfactory  : — 5  grams  of  the  oil  are  weighed 
into  a  test-tube  about  15  cm.  long  and  15  mm.  diameter,  mixed  with 
10  cc.  of  a  20  per  cent,  solution  of  potassium  hydroxide  in  alcohol  of 
93°,  and  agitated,  when  the  oil  dissolves.  The  liquid  is  then  heated 
on  a  water-bath  to  a  temperature  sufficient  to  produce  gentle  ebulli- 
tion, and  after  about  15  minutes  saponification  is  complete.  The 
volume  of  the  liquid  is  then  made  up  to  50  cc.  by  adding  alcohol,  and 
5  cc.  of  the  solution  is  placed  in  a  tube  provided  with  a  glass 
stopper,  acidified  with  hydrochloric  acid,  and  then  mixed  with  a  con- 
centrated aqueous  solution  of  bromine  from  a  burette,  with  vigorous 
agitation,  until  the  liquid  acquires  a  persistent  pale-yellow  tint. 
About  0*1  cc.  of  solution  is  required  to  produce  the  end  reaction, 
and  this  should  be  substracted  from  the  total  volume  added.  The 
bromine  is  standardized  by  means  of  a  decinormal  solution  of  arsenious 
acid,  mixed  with  hydrochloric  acid.  Different  samples  of  oil  from 
the  same  species  of  olive  absorbed  from  0*512  to  0*522  gram  of 
bromine  per  gram  of  oil.  The  absorption  by  oil  from  different  species 
of  olive  varied  from  0*500,  to  0*544,  the  last  result  being  obtained  with 
011  from  Blanquetier  which  also  has  an  exceptionally  high  sp.  gr. 
1  he  amount  of  bromine  absorbed  by  1  gram  of  other  oils  is  as  fol- 
lows : — 
Cotton-seed   0-645  |  Colza   0-640 
Sesame   0-695  j  Cam elina   0-817 
Earth-nut   0-530  Linseed   1-000 
Poppy   0  835  i 
The  alcoholic  solution  of  soap  from  oil  of  earth-nut  becomes  solid 
as  soon  as  the  temperature  falls  to  15°,  but  the  corresponding  solution 
of  olive  oil  soap  remains  liquid. 
The  most  constant  characteristic  of  oil  soap  is  its  sp.  gr.,  but  the  de- 
termination of  the  bromine  absorbed  is  also  very  useful. 
T.  Leone  and  A.  Longi  (Gazzetta,  xvi,  393 — 398),  with  a  view  to 
the  recognition  of  the  presence  of  sesame  and  cotton  oils  in  cases  of 
sophistication  of  olive  oil,  have  examined  the  physical  and  chemical 
properties  of  these  oils,  such  as  the  proportion  of  solid  acids  obtained 
on  saponification,  the  quantity  of  alkali  required  to  complete  this 
process,  the  specific  gravities  at  100°  of  the  oils  and  the  resultant  acids, 
the  points  of  fusion  and  solidification  of  the  acids,  and  the  indices  of 
