AmFJe0bur'J7h6?rm'}        Determination  of  Mixed  Oils.  73 
DETERMINATION  OF  MIXED  OILS. 
The  testing  of  mixed  oils  is  far  from  being  a  certain  operation.  The 
following,  however,  are  the  principal  means  of  determining  the  pres- 
ence of  mixtures  : 
ist.  The  determination 
of  its  specific  g 
ravity  at  150 
C.  and  its 
parison,  with  the  following 
table  : 
Density.  Degrees 
011  alcoholometer. 
Weight  of  1  h< 
Tallow  oil  (olein) 
900*3 
73*0 
88-40 
Colza  (winter  strained) 
915-0 
59*8 
91*50 
Colza  (summer  strained) 
qi6'o 
\y  j 
cq-8 
J  7 
91*67 
Rape-seed  (winter  strained) 
QI  f '1 
CO*  C 
J  y  J 
y    j  t 
Rape-seed  (summer  strained) 
91 5*7 
59*2 
91*57 
Groundnut  (Arachis  oil) 
.917-0 
58*5 
91*70 
Olive 
917-0 
58'5 
91*70 
Almond 
918*0 
58*0 
91*80 
Beechnut 
920*7 
57'5 
92*07 
Sesame 
923"5 
56  O 
92'35 
Whale 
924*0 
55-0 
92*40 
Poppy 
9^5*3 
54'5 
92*53 
Hemp-seed 
927*0 
53'5 
92*70 
Cod-liver 
927*0 
53*5 
92*70 
Cotton-seed 
9306 
52*0 
93*06 
Linseed 
935'° 
50*0 
•93-5o 
2d.  Chlorine  turns  animal  oils  brown  and  vegetable  oils  white.  The 
former  are  soluble,  and  the  latter  insoluble  in  ether. 
3d.  To  discover  an  adulteration  by  oil  of  sesame,  shake  five  grams 
of  sulphuric  acid  with  five  grams  of  nitric,  and  ten  grams  of  the 
suspected  oil  ;  if  mixed,  a  grass-green  color  is  immediately  developed. 
4th.  To  find  if  olive  oil  is  mixed  with  any  unknown  oil,  mix  fifty 
centimetres  of  the  oil  with  ten  centimetres  of  sulphuric  acid.  If  the 
olive  oil  is  pure,  there  will  be  a  rise  of  420  ;  if  mixed,  the  temperature 
will  be  580  for  oil  of  colza,  650  for  beechnut,  68°  for  sesame,  980  for 
hemp-seed,  130  for  linseed. 
5th.  The  production  of  a  black  hue  in  the  lower  part  of  the  test- 
tube,  after  agitating  twenty  drops  of  an  alcoholic  solution  of  nitrate  of 
silver  with  ten  grams  of  oil  and  twenty  grams  of  ether,  the  flask  being 
kept  in  the  dark,  shows  the  presence  of  rape-seed  oil. 
6th.  The  most  difficult  adulteration  to  be  detected  is  that  of  olive 
and  groundnut  oil.  These  oils  have  the  same  density,  congeal  at  the 
same  temperature,  and  are  acted  on  by  sulphuric  acid  in  a  similar  man- 
ner.   They  can,  however,  be  distinguished  as  follows  : 
