254  Quantitative  Estimation  of  Strychnine.  {Amjune?i9osfrm 
The  ferrocyanide  method  of  Dunston  and  Short,  as  adopted  by 
the  British  Pharmacopoeia,  is  very  tedious,  and  has  been  shown  not 
to  be  particularly  accurate,  as  the  strychnine  ferrocyanide  is  stated 
to  carry  down  with  it  some  of  the  brucine  ferrocyanide,  so  that  the 
results  are  too  high. 
Lyons's  method  of  washing  away  the  brucine  by  means  of  a  satu- 
rated solution  of  strychnine  in  40  per  cent,  alcohol  is  also  stated  by 
Gordin  to  be  inaccurate. 
He  says  that  "  most  of  the  strychnine  is  washed  away  along  with 
the  brucine,"  and  that  the  reason  may  be  that,  in  the  amorphous 
condition,  strychnine  must  be  more  soluble  in  40  per  cent,  alcohol 
than  when  in  the  crystalline  form. 
Keller's  method  of  destroying  the  brucine  by  oxidation  with 
HNO3  and  shaking  out  the  strychnine  with  chloroform  after  making 
the  solution  alkaline,  appears  to  give  good  results;  but  Gordin, 
working  on  a  mixture  of  pure  alkaloids,  failed  to  get  more  than  96 
per  cent,  strychnine  by  this  method.  In  a  series  of  experiments, 
conducted  with  the  object  of  avoiding,  if  possible,  this  loss  of  4  per 
cent.,  Gordin  found  that,  by  modifying  Keller's  method  in  certain  par- 
ticulars, much  more  accurate  results  were  obtained.  He  reduced  the 
time  of  digestion  with  HN03  from  one  hour  and  a  half  to  ten  min- 
utes, finding  this  was  quite  long  enough  to  effect  the  destruction  of 
the  brucine.  and  that  the  longer  period  of  digestion  resulted  in  the 
partial  decomposition  of  the  strychnine,  as  evinced  by  the  yellow 
color  of  the  solution,  due  to  the  formation  of  trinitrophenol. 
He  also  found  that  a  weaker  acid  could  be  used  with  better 
results,  as  by  it  the  brucine  was  completely  destroyed,  whilst  the 
strychnine  was  not  affected. 
By  substituting  a  fixed  alkali  for  ammonia,  and  pure  chloroform 
for  ether-chloroform,  a  much  whiter  alkaloid  .vas  obtained,  and  suf- 
ficiently pure  to  be  weighed.  The  details  of  the  improved  method 
are  as  follows : 
The  mixed  alkaloids,  which  may  be  the  residue  from  8  or  10 
grammes  of  drug,  are  dissolved  in  15  c.c.  of  3  per  cent.  H2S04  by 
the  aid  of  a  water-bath  heat.  The  solution  is  cooled  to  ordinary 
temperature,  and  3  c.c.  of  a  previously  prepared  and  cooled  mixture 
of  equal  parts  of  strong  HNOs  (s.  g.  1-42)  and  water  are  added  to 
the  alkaloidal  solution. 
The  liquid  is  set  aside  for  exactly  ten  minutes,  shaking  it  gently. 
