"^"Fer'is^s''"'}   ^^^^^  of  Vegetable  and  Animal  Oils.  77 
a  development  of  upward  of  250°  with  African  fish  oil.  The  spe- 
cific gravity  of  African  fish  oil  is  said  to  be  about  0"866,  and  it  is  a 
very  bad  lubricant.  Other  adulterating  oils  may  also  be  detected  by 
this  test. 
5.  That,  as  the  use  of  sperm  oil  is  dependent  upon  its  viscosity,  an 
accurate  test  thereof,  in  a  suspected  sample,  may  be  useful. 
Class  II  comes  next  in  value  to  sperm  oil,  viz.,  the  oleins  obtained  by 
pressure  from  animal  fats,  known  in  the  market  as  tallow  olein,  lard 
olein  and  neatsfoot  oil.  Lard  and  tallow  oils  should  have  a  specific 
gravity  of  O'gi^.  If  the  oil  is  heavier,  it  may  contain  fish  oils,  seed 
oils,  olive  oils  or  cocoa-nut  olein,  Olive  oil,  cocoa-nut  oil  or  fish  oils 
can  be  detected  by  the  smell,  color,  taste  and  Calvert's  tests,  so  that 
the  real  difficulty  lies  with  seed  oils,  one  of  which,  rape  oil,  is  nearly  of 
the  color,  and  exactly  of  the  specific  gravity,  of  animal  oleins.  If  a 
sample  of  animal  olein  be  too  heavy,  it  probably  contains  some  par- 
tially-drying oils  like  cotton  seed,  which  range  from  -920  to  '930. 
Those  seed  oils  which  cannot  be  detected  by  variations  in  the  specific 
gravity  are  rape,  henbane-seed,  horse-chestnut  and  plum-kernel  oils. 
The  last  three  may  be  disregarded.  The  processes  for  the  detection  of 
rape  are  the  following  : 
1.  Heating  to  400°  F.  and  allowmg  to  cool  to  90°.  Tallow  and  lard 
oils  are  rendered  odorless,  while  the  peculiar  penetrating  smell  of  rape 
oil  is  developed. 
2.  One  part,  by  weight,  of  the  oil  is  mixed  with  3  parts  of  concen- 
trated sulphuric  acid,  and  the  heat  developed  is  compared  with  the  heat 
developed  by  a  similar  experiment  made  with  pure  oil. 
3.  The  nitrate  of  mercury  test  is  said  to  indicate  the  presence  of 
even  10  per  cent. 
Finally,  lard  oil  is  distinguished  from  tallow  olein  by  difference  of 
viscosity. 
Class  III  embraces  the  olive  oils.  The  adulterations  to  be  sought 
are  drying  oils,  fish  oils,  mineral  and  resin  oils.  The  specific  gravity 
of  olive  oil  is  0*917.  Rape  oil  would  make  it  lighter,  and  cotton-seed 
oil  heavier,  but  a  proper  mixture  of  the  two  could  be  adjusted  exactly 
to  the  specific  gravity  of  olive  oil.  Fish  oils  being  proved  absent  by 
Calvert's  tests  or  by  the  smell,  the  following  tests  are  used  for  seed 
oils  : 
1.  The  well-known  nitrous  acid  or  nitrate  of  mercury  test. 
2.  The  characteristics  of  the  amides  produced  by  liquid  ammonia. 
