CHEMICAL  COMPOSITION  OF  GELSEMIUM  SEMPERVIRENS.  13 
4.  Iodine  in  a  solution  of  iodide  of  potassium  throws  down  from 
solutions  of  salts  of  the  alkaloid  a  brown  precipitate,  which  is 
only  sparingly  soluble  in  acetic  acid,  1400th  of  a  grain  yields 
a  very  copious  precipitate ;  1-lOOOth  of  a  grain,  a  good  choco- 
late-colored deposit ;  1-10,000  of  a  grain,  a  very  distinct  deposit. 
5.  Bromine  in  hromohydric  acid  precipitates  the  alkaloid  from 
solutions  of  its  salts  in  the  form  of  a  yellowish  amorphous  de- 
posit. 1-lOOth  of  a  grain  in  one  grain  of  water  yields  a  copious 
flesh-colored  precipitate,  which  becomes  yellow.  1-lOOOth  grain 
yields  a  very  good  yellow  flocculent  deposit ;  1-5000  grain,  a 
very  distinct  precipitate. 
6.  Chloride  of  gold  ipYoduces  a  yellow  amorphous  precipitate, 
which  dissolves  with  difficulty  in  acetic  acid.  1-lOOth  of  a  grain 
yields  a  very  copious  precipitate  ;  1-lOOOth  grain  yields  a  good 
flocculent  deposit. 
7.  Bichloride  of  platinum,  occasions  a  light  yellow  precipitate, 
which  still  manifests  itself  in  one  grain  of  a  1-lOOOth  solution. 
8.  Sulphocyanide  of  potassium  produces,  in  tolerably  strong 
solutions  of  the  chloride  of  the  alkaloid,  a  dirty-white  precipitate, 
in  which,  after  a  time,  brownish  or  chocolate-colored  flakes 
usually  appear. 
9.  Ferricyanide  of  potassium  throws  down  from  concentrated 
solutions  of  the  chloride  a  dirty-greenish  or  bluish-green  precipi- 
tate, the  green  color  of  which  after  a  time  becomes  more  marked. 
10.  Corrosive  sublimate  occasions  a  white  precipitate,  which  is 
only  sparingly  soluble  in  large  excess  of  hydrochloric  acid. 
1-lOOth  of  a  grain  yields  a  very  copious  precipitate ;  l-500th 
grain,  a  quite  distinct  turbidity. 
Concentrated  solutions  of  the  salts  of  the  alkaloid  also  yield 
precipitates,  of  a  dirty-white  color,  with  iodide  of  potassium  and 
with  ferrocyanide  of  potassium. 
From  the  above  it  will  be  observed  that  the  reactions  of 
gelseminine  are  by  no  means  so  characteristic  nor  delicate  as 
those  of  gelseminic  acid.  In  poisoning  by  the  fluid  extract  of 
gelsemium  it  might  therefore  happen  that  the  acid  would  be  dis- 
covered, whilst  there  would  be  a  failure  to  satisfactorily  prove 
the  presence  of  the  base. 
