392  Forensic-chcmicat  Determination  of  GeUemine.  {"'^"i;^^;^?  is?""' 
condition  tlie  cherry-red  color  of  gelsemine  clianges  to  an  intense  green 
or  bluish-green. 
On  substituting  manganese  binoxide  for  the  bichromate,  almost 
identical  results  are  obtained  ;  but  using  concentrated  sulphuric  acid, 
the  colorations  of  gelsemine,  and  particularly  of  quebracliine,  are  much 
darker  and  handsomer.  With  the  bihydrated  acid,  quebrachine  gives 
only  a  slight  violet  color;  in  the  presence  of  trihydrate the  dark  green 
color  of  gelsemine  appears  slowly,  and,  with  a  greater  dilution  of  the 
acid,  the  blue-violet  color  of  strychnine  in  the  beginning  is  more  and 
more  replaced  by  cherry-red. 
The  same  reactions,  made  with  eerie  oxide,  yield  lighter  and  less 
intense  colorations,  the  green  from  gelsemine  having  a  bluish  tint. 
The  Aveakest  colorations  are  produced  by  lead  peroxide  only  in  pre- 
sence of  a  trace  of  nitric  acid;  the  tint  from  gelsemine  is  grass-green. 
The  reaction  best  adapted  for  gelsemine  is  sulphuric  trihydrate  and 
one  of  the  four  reagents,  when  the  final  color  by  gelsemine  is  green, 
and  by  strychnine,  brick-red. 
Concentrated  sulphuric  acid  dissolves  gelsemine  with  a  yellow-brown 
color ;  quebrachine,  similar ;  strychnine,  colorless. 
Sulphuric  acid  containing  iron  shows  no  reaction  with  gelsemine  and 
strychnine ;  a  blue-violet  color  with  quebrachine. 
Froehde's  reagent :  AVith  gelsemine,  roe-brown  to  red-brown,  gradu- 
ally yellowish-green  (a  very  similar  reaction  was  observed  by  Graebner 
with  ptomaines) ;  strychnine,  no  change ;  geissospermine  and  que- 
brachine, blue. 
Selen-sulphuric  acid,  with  gelsemine,  no  reaction. 
Sugar  and  sulphuric  acid  :  Gelsemine,  cherry-red ;  but  fats,  biliary 
acids,  aconitine,  codeine,  and  delphinidine  give  the  same  color ; 
strychnine,  no  red  color ;  quebrachine,  intense  cherry-red. 
Brouardel-Boutmy's  reagent  (potassium  ferridcyanide  and  ferric 
chloride) :  Gelsemine  and  quebrachine,  intensely  green  ;  strychnine  and 
aspidospermine,  no  reaction.  Ptomaines  obtained  from  the  stomach 
and  intestines,  no  reaction  ;  but  if  isolated  from  the  liver,  kidneys,  etc., 
by  agitation  of  the  alkaline  liquid  with  benzol  or  chloroform,  a  slight 
green  color  is  produced,  and  the  older  the  corpse  the  more  frequently 
are  such  ptomaines  obtained. 
Chlorine  water  to  acid  solution  :  Gelsemine  yields  yellowish  tur- 
bidity and  slight  fluorescence;  after  a  while  a  yellowish -white  precij^i- 
tate,  which  is  produced  yet  in  solutions  of  1  in  1,000  and  is  dark- 
