DEPOKTMENT  OF  ALKALOIDS  WITH  REAGENTS,  ETC.  553 
as  these  reactions  are  common  to  all,  they  are  of  little  impor- 
tance in  an  analytical  point  of  view.f 
Strychnia  may  be  separated  from  brucia  and  veratria  by 
means  of  absolute  alcohol,  since  it  is  insoluble  in  that  men- 
struum, whilst  the  two  latter  alkaloids  readily  dissolve  in  it. 
The  identity  of  strychnia  is  best  established  by  the  reaction  with 
sulphuric  acid  and  the  above-mentioned  oxidizing  agents  ;J  also 
by  the  form  of  its  crystals — when  thrown  down  by  alkaloids — 
viewed  under  the  microscope  ;  and  lastly,  by  the  form  of  the  pre- 
cipitate which  sulphocyanide  of  potassium  and  chloride  of  mer- 
cury produce  in  solutions  of  its  salts.  Brucia  and  veratria  are 
not  readily  separated  from  one  another,  but  may  be  detected  in 
presence  of  each  other.  The  identity  of  brucia  is  best  estab- 
lished by  the  reactions  with  nitric  acid  and  protochloride  of  tin 
or  sulphide  of  ammonium,  or  by  the  form  of  the  crystalline  pre- 
cipitate which  ammonia  produces  in  solutions  of  salts  of  brucia. 
Veratria  is  sufficiently  distinguished  from  brucia  and  the  other 
alkaloids  which  we  have  treated  of,  by  its  characteristic  deport- 
ment at  agentle  heat,  and  also  by  the  form  of  the  precipitate  which 
alkalies  produce  in  solutions  of  its  salts.  To  distinguish  veratria 
in  presence  of  brucia,  the  reaction  with  concentrated  sulphuric 
acid  is  selected. 
To  these  alkaloids  I  will  add  salicine,  though  this  substance 
does  not  properly  belong  to  the  same  class  of  chemical  com- 
pounds. 
it  If  the  precipitate  produced  in  the  solution  of  a  salt  of  strychnia  by 
iodide  of  potassium  containing  iodine,  is  dissolved  in  spirit  of  wine 
mixed  with  some  sulphuric  acid  and  the  solution  is  evaporated,  strongly 
polarizing  prismatic  crystals  of  sulphate  of  iodide  of  strychnia  are  ob- 
tained. De  Vrij  and  Van  der  Burg  (Jahresber  v.  Liebig,  and  Kopp,  1857, 
602.)  Whether  this  reaction  is  characteristic  for  strychnia,  can  be  known 
only  after  the  optical  properties  of  analogous  compounds  of  the  other 
alkaloids  shall  have  been  studied. 
|  The  only  substance  which  shows  somewhat  analogous  reactions  in 
this  respect,  is  aniline.  A.  Guy  has,  however,  called  attention  to  the  fact 
that  aniline,  treated  with  sulphuric  acid  and  oxidizing  agents,  acquires  a 
pale  green  color  at  first,  which  gradually  deepens,  and  only  then  changes 
to  a  magnificent  blue,  which,  after  persisting  some  time,  turns  finally 
black. 
