Am.  Jour.  Pharm. ) 
July,  1883.  J 
Testing  of  Olive  Oil 
355 
sium  hydrate  and  the  addition  of  a  little  water  and  alcohol.  After 
the  complete  dissipation  of  the  alcohol  tlie  remaining  soap  is  dissolved 
in  hot  water,  and  from  the  clear  solution  the  fatty  acids  are  separated 
by  the  addition  of  hydrochloric  acid.  When  the  fatty  acids  after  con- 
tinued heating  float  upon  the  saline  solution  as  a  perfectly  clear  oil,  a 
portion  of  the  oily  layer  is  brought  into  a  small,  narrow,  thin-walled 
test-tube  and  allowed  to  solidify  therein.  The  determination  of  the 
melting  or  solidifying  point  is  effected  by  placing  the  small  test-tube 
containing  the  fatty  mass  in  a  beaker  filled  with  water,  which  is 
warmed  by  means  of  a  small  flame,  and  by  the  aid  of  a  thermometer 
dipped  in  the  fatty  acids  and  gently  moved  to  and  fro  during  the 
observation,  the  point  is  precisely  observed  when  the  entire  mass 
becomes  perfectly  clear,  and  that  when  clouds  begin  to  form  about  the 
bulb  containing  the  mercury.  It  is  now  shown  that  the  acids  derived 
from  pure  olive  oil,  without  restriction  as  to  the  origin  of  the  latter, 
melt  between  26*5  and  28-5°C.,  and  solidify  not  lower  than  22°C. 
The  oils  applied  for  the  adulteration  of  olive  oil  show  with  relation  to 
the  melting  point  of  their  fatty  acids  very  considerable  deviations  from 
the  former.  The  melting  and  solidifying  points,  respectively,  of  the 
acids  of  cotton  seed  oil,  sesame  oil  and  ground  nut  oil  are  considerably 
higher,  those  of  sunflower  oil,  rape  seed  oil  and  ricinus  oil  consider- 
ably lower,  than  those  of  the  acids  of  olive  oil. 
The  fatty  acids  of  Cotton  seed  oil  melt  at  38-0°C.,  and  solidify  at  35-0°C. 
Sesame  oil  "  35*0  "  32-5 
Ground  nut  oil  "  33'0  "  Sl'O 
Sunflower  oil  "  23*0  "  .17-0 
Eape  seed  oil  "  20-7  "  15-0 
Ricinus  oil  "  13-0  "  2*0 
The  above  figures  deviate  so  far  from  the  data  obtained  with  pure 
olive  oil  that  by  the  determination  of  the  melting  point  adulterations 
to  such  an  extent  as  occur  in  commerce  may  very  readily  be  detected ; 
for  a  Gallipoli  olive  oil,  mixed  with  20  per  cent,  of  sunflower  oil,  melts 
already  at  24°C.,  and  solidifies  first  at  18°C.^  A  Nizza  oil,  mixed 
with  20  per  cent,  of  cotton  seed  oil,  melts  first  at  31*5°C.,  and  solidifies 
already  at  28°C.  A  Gallipoli  oil,  mixed  with  33 J  per. cent,  of  rape 
seed  oil,  melts  already  at  23*5°C.,  and  solidifies  first  at  16*5°C.;  mixed 
with  50  per  cent,  of  rape  seed  oil,  it  melts  already  at  20°C.,  and  solidi- 
fies first  at  13-5°C.,  etc. 
^  The  fatty  acids  are  always  to  be  understood. 
