20         Action  of  Sulphuric  Acid  Upon  Strychnine.    { A  jaSjyfiS™" 
dryness  on  a  porcelain  crucible  cover,  over  a  water  bath,  taking  care 
to  have  all  the  strychnine  deposited  at  one  point  on  the  cover.  This 
residue  was  then  moistened  with  I  drop  of  concentrated  sulphuric 
acid,  and  a  minute  particle  of  potassium  dichromate  was  drawn 
through  the  droplet  with  a  fine  glass  rod.  This  gave  the  character- 
istic color  reaction.  Beginning  with  a  concentrated  solution  of 
strychnine,  the  tests  were  made  in  solutions  of  greater  dilution  till  a 
point  was  reached  at  which  it  was  not  possible  to  detect  the  alkaloid 
by  this  test.  The  microscope  was  not  used  in  the  examination  of 
the  color  test. 
In  the  second  series  of  tests,  after  evaporating  the  solution  to  dry- 
ness on  the  porcelain  cover,  it  was  treated  with  a  drop  of  concen- 
trated sulphuric  acid,  and  heated  for  fifteen  minutes  on  the  water 
bath,  then  the  test  was  made  in  the  usual  manner. 
In  the  third  series  of  tests  the  conditions  were  such  as  would  pre- 
vail in  the  ordinary  course  of  analysis,  when  organic  matter  is  pres- 
ent. To  each  portion,  before  testing,  a  measured  quantity  of  extract 
of  beef  was  added,  25  c.c.  of  alcohol,  and  a  few  drops  of  acetic  acid, 
and  the  whole  was  digested  for  an  hour  on  a  water  bath.  The  mix- 
ture was  then  diluted,  filtered,  and  evaporated  to  dryness  on  a  water 
bath,  allowed  to  cool  and  dissolved  in  water  acidulated  with  a  drop 
of  acetic  acid.  The  solution  was  made  alkaline  with  potassium  hy- 
drate and  shaken  out  twice  with  chloroform,  about  10  c.c.  of  this 
solvent  being  used  each  time.  The  mixed  chloroform  solutions 
were  then  evaporated  to  dryness  at  100°  and  the  residue  was  moist- 
ened with  a  drop  of  sulphuric  acid.  This  was  warmed  for  fifteen 
minutes,  then  dissolved  in  water  made  alkaline  with  potassium  hy- 
drate and  shaken  out  three  times  with  chloroform.  The  mixed 
chloroform  solutions  were  evaporated  to  dryness  on  a  water  bath, 
concentrating  the  residue  to  a  small  point  on  the  porcelain  surface, 
and  the  test  was  applied  as  in  the  preceding  cases. 
The  results  of  these  tests  were  as  follows  : 
DELICACY  OF  THE  ^CHEMICAL  TESTS. 
Fractions  of  a  milligram  present  in  the  solution  (x  =  limit,  t  =  test). 
1-iiceoiootOi-iioeOiOoco-^iOi-irHioeoico 
o  000 
Series  I.   Tests  with  the  plain  solution  : 
tttttttttttttttttttx 
Series  II.   Tests  with  strychnine  and  sulphuric  acid  : 
tttttttttttttttx 
Series  III.   Tests  with  strychnine,  sulphuric  acid  and  organic  matttr  : 
t     t  x 
