F?Ju°aTyPih92itn";       Identification  of  Soy-Bean  Oil.  147 
THE  DIRECT  IDENTIFICATION  OF  SOY-BEAN  OIL.* 
By  Charles  A.  Newhall, 
SEATTLE,  WASHINGTON. 
Oil  chemists  seem  to  have  overlooked  a  valuble  test  for  the 
direct  identification  of  soy-bean  oil.  Two  color  tests  attributed 
to  L.  Settini  1  have  been  found  of  value  in  detecting  admixtures  of 
soy-bean  oil  with  other  commercial  oils. 
For  some  three  years  the  writer  has  been  using  a  modification 
of  the  second  test,  as  follows :  Five  c.  c.  of  chloroform  are  added 
to  5  c.  c.  of  the  oil,  mixed  in  a  small  test  tube  with  a  few  drops  of 
gum  arabic  solution  and  5  c.  c.  of  a  2  per  cent,  solution  of  uranium 
nitrate  or  uranium  acetate,  and  shaken  to  form  a  thorough  emul- 
sion. All  samples  of  crude  and  refined  soy-bean  oil  so  far  exam- 
ined give  a  characteristic  lemon-yellow  emulsion;  whereas,  no  other 
oil  so  far  tested  gives  this  color. 
The  most  valuable  use  for  the  test  has  been  in  detecting  admix- 
tures of  the  cheap  bean  oil  with  high-priced  wood  oil  or  with 
linseed  oil.  With  the  former  the  test  is  sharp,  it  being  possible 
to  detect  as  low  as  5  per  cent,  of  bean  oil. 
With  linseed  oil  the  test  is  not  so  sharp,  as  linseed  oil  mix- 
tures always  give  a  slightly  brownish  color.  It  has  never  been 
absolutely  certain  that  the  linseed  oil  samples  used  for  comparison 
were  pure,  and  further  work  is  in  progress. 
With  such  oils  as  peanut,  cotton  seed,  sesame,  rape,  and  cocoa- 
nut,  the  test  is  very  sharp,  and  these  oils  give  white  or  slightly 
colored  emulsions  with  the  uranium  salt. 
The  yellow  emulsion  is  not  formed  with  bleached  and  de- 
odorized bean  oil,  hydrogenated  oil,  or  bean  oil  fatty  acid. 
This  Settini  test  for  bean  oil  is  not  as  sharp  as  some  of  the 
direct  color  tests  characteristic  of  sesame  or  cotton  seed  oils,  but 
nevertheless  it  has  been  of  great  value  in  the  commercial  testing 
of  oils,  arriving  from  the  Orient.  This  is  no  indication  that  it 
will  work  equally  well  with  domestic  soy-bean  oil.  Since  the 
yellow  emulsion  seems  to  be  due  to  the  presence  of  coloring  matter 
*From  Jour.  Ind.  &  Engr.  Chemistry,  Dec,  1920. 
1Chem.  Abstr.  7  (1913),  9°& 
