340  Constituents  of  Gelsemium  Sempervirens.    |  ji?y'"i882*™* 
substance  is  pure)  undergoes  little  or  no  change,  ^lllsculin  readily  dis- 
solves in  the  acid,  but  on  warming  the  solution  it  quickly  acquires  a 
brownish  or  chocolate  color  and  becomes  charred. 
If  a  drop  of  aqueous  ammonia  be  allowed  to  flow  into  a  drop  of  the 
sulphuric  acid  solution  of  the  gelsemium  compound,  a  dirty  white 
deposit  or  cloud  of  very  minute  crystalline  needles  separates  at  the 
margin  of  contact  of  the  liquids. 
If  only  a  minute  drop  of  the  acid  be  employed  and  excess  of  ammo- 
nia be  avoided,  even  the  1-1 0,000th  grain  of  the  substance  will  in  this 
manner  yield  a  very  satisfactory  deposit  of  needles.  If  the  drop  of 
liquid  be  allowed  to  evaporate,  these  crystals  may  be  re-examined,  even 
several  times,  by  moistening  the  residue  with  a  minute  drop  of  water, 
which  will  quickly  dissolve  the  ammonium  salt,  whilst  the  needles 
will  remain,  they  being  apparently  insoluble  under  these  conditions. 
This  reaction  is  highly  characteristic  of  the  gelsemium  principle. 
A  sulphuric  acid  solution  of  cesculin  under  like  conditions  fails  to 
yield  any  crystals,  unless  a  comparatively  large  quantity  is  present  and 
the  mixture  be  evaporated  to  about  dryness,  when  transparent  nodular 
masses  with  some  groups  of  prisms  may  appear. 
4.  Hydrochloric  acid  fails  to  dissolve  or  act  upon  the  gelsemium 
compound,  even  under  the  heat  of  a  water  bath,  ^sculin  is  readily 
soluble  in  this  acid. 
In  the  following  liquid  reactions  the  results  refer  to  the  behavior  of 
a  few  drops  of  1-1 00th  solutions  of  both  principles. 
5.  Nitrate  of  silver  produces  in  a  solution  of  the  gelsemium  prin- 
ciple a  copious  brownish-yellow  precipitate,  which  soon  darkens  in 
color,  and  finally  the  mixture  becomes  deep  blue-black,  due  to  the 
reduction  of  the  silver  salt.  This  reaction  will  manifest  itself,  after  a 
time,  even  in  a  l-50,000th  solution. 
^sculin  yields  from  a  1-1 00th  solution,  a  slight  dirty  yellow  pre- 
cipitate, which  remains  unchanged  for  several  minutes;  it  then  slowly 
darkens. 
6.  Corrosive  sublimate  throws  down  a  copious  yellowish  precipitate, 
from  which  the  organic  acid  quickly  separates  as  large  tufts  of  needles. 
JEsculin  fails  to  yield  a  precipitate  or  crystals. 
7.  Bromine  in  hromohydric  acid  produces  a  copious  green  deposit, 
which  quickly  acquires  a  blueish  and  finally  a  brownish  color. 
^sculin  yields  a  slight  yellow  precipitate,  which  becomes  yellowish- 
gray. 
