434 
Black  and  White  Mustard  Seed. 
/Am.  Jour.  Ptaarm. 
t  September,  1898. 
has  been  found  in  commercial  powdered  mustard3  and  under  con- 
ditions that  preclude  the  idea  of  intentional  admixture.  The  pres- 
ence of  starch-bearing  weed  seeds,  and  of  scattered  grains  of  wheat 
or  of  contaminations  caused  by  using  second-hand  sacks  with  ad- 
hering flour  or  meal,  will  account  for  such  reactions.  It  is  therefore 
desirable  that  a  method  should  be  found  that  will  approximately 
indicate  the  proportion  of  starch. 
Black  Mustard  Seed. — The  ordinary  method  of  detecting  starch 
by  adding  U.S. P.  iodine  test  solution  to  the  aqueous  decoction  fails 
with  black  mustard,  on  account  of  the  ready  absorption  of  iodine 
by  the  oil  of  mustard  that  is  at  once  developed  when  black  mustard 
comes  in  contact  with  water.  This  fact  was  pointed  out4  by  the 
author  in  1895. 
If  iodine  solution  is  added,  and  much  starch  is  present,  a  blue 
coloration  is  developed,  which  remains  for  a  short  time  only,  then 
fades  and  disappears.  A  considerable  excess  of  iodine,  however, 
will  effect  a  more  permanent  blue  coloration,  but  affords  no  test 
concerning  the  proportion  of  starch. 
If  small  amounts  of  starch  are  present,  iodine  will  show  no  blue 
color  at  all.  Hence  the  necessity  of  a  rapid  and  convenient  method 
by  means  of  which  a  permanent  starch  reaction  can  be  obtained, 
even  when  small  quantities  of  starch  are  present. 
Preliminary  Work. — The  idea  of  abstracting  the  disturbing  ele- 
ment sinigrin  by  means  of  solvents  prior  to  the  testing  for  starch 
was  soon  abandoned  as  impracticable  and  hopeless.  Then  it  was 
attempted  to  precipitate  the  sinigrin  by  means  of  the  salts  of  heavy 
metals,  such  as  silver  nitrate,  mercurous  nitrate,  or  lead  acetate 
with  no  satisfaction. 
By  subsequent  and  prolonged  experiments  with  copper  sulphate, 
however,  it  was  shown  that  this  substance  had  the  capacity  of  pre- 
venting the  formation  of  oil  of  mustard,  even  when  employed  in 
as  weak  a  solution  as  o-2  per  cent.  This  reaction,  however,  is 
not  new.6 
Acting  upon  this  fact,  and  carrying  the  principle  further,  we  were 
enabled  to  arrive  at  several  useful  working  methods  for  starch 
3  Bulletin  of  Pharmacy,  Vol.  XI,  1897,  p.  64. 
4  Proc.  Am.  Pharm.  Assoc.,  1895,  p.  194-199. 
6  Dr.  J.  Gadamer,  Ueber  die  Bestandteile  des  schwarzen  und  des  weissen 
Senfsamens.    Archiv  der  Pharmazie,  Vol.  235,  1897,  pp.  44-114. 
,;  P.  Carles,  Pharm.  Jour,  and  Trans.,  4th  series,  Vol.  VI,  1898,  p.  73. 
