54     DETECTING  THE  ORGANIC  ALKALOIDS  IN  CASES  OF  POISONING. 
maining  in  the  solution  of  potash  or  soda.  In  either  ease,  we 
exhaust  the  matter  with  ether.  Whatever  be  the  agent  which  has 
set  the  alkaloid  free,  whether  it  be  the  bicarbonate  of  soda  or 
potash,  or  caustic  soda  or  potash,  it  remains,  by  the  evaporation 
of  the  ether,  on  the  side  of  the  capsule  as  a  solid  body,  but  more 
commonly  a  colorless  milky  liquid,  holding  solid  matters  in  sus- 
pension. The  odor  of  the  substance  is  animal,  disagreeable,  but 
not  pungent.    It  turns  litmus  paper  permanently  blue. 
When  we  thus  discover  a  solid  alkaloid,  the  first  thing  to  do  is 
to  try  and  obtain  it  in  a  crystalline  state,  so  as  to  be  able  to 
determine  its  form.    Put  some  drops  of  alcohol  in  the  capsule 
which  contains  the  alkaloid,  and  leave  the  solution  to  spontaneous 
evaporation.    It  is,  however,  very  rare  that  the  alkaloid  obtained 
by  the  above  process  is  pure  enough  to  crystallize.    Almost  always 
it  is  soiled  by  foreign  matters.    To  isolate  these  substances,  some 
drops  of  water,  feebly  acidulated  with  sulphuric  acid,  are  poured 
into  the  capsule,  and  then  moved  over  its  surface,  so  as  to  bring  it 
in  contact  with  the  matter  in  the  capsule.    Generally  we  observe 
that  the  acid  water  does  not  moisten  the  sides  of  the  vessel.  The 
matter  which  is  contained  in  it  separates  into  two  parts,  one  formed 
of  greasy  matter,  which  remains  adherent  to  the  sides — the  other 
alkaline,  which  dissolves   and  forms  an  acid  sulphate.  We 
cautiously  decant  the  acid  liquid,  which  ought  to  be  limpid  and 
colorless,  if  the  process  has  been  well  executed  ;  the  capsule  is  wTell 
washed  with  some  drops  of  acidulated  water,  added  to  the  first 
liquid,  and  the  whole  is  evaporated  to  three-fourths  in  vacuo,  or 
under  a  bell-jar  over  sulphuric  acid.    We  put  into  the  residue  a 
very  concentrated  solution  of  pure  carbonate  of  potash,  and  treat 
the  whole  liquid  with  absolute  alcohol.    This  dissolves  the  alkaloid, 
while  it  leaves  untouched  the  sulphate  of  potash  and  excess  of 
carbonate  of  potash.    The  evaporation  of  the  alcoholic  solution 
gives  us  the  alkaloid  in  crystals. 
It  is  now  the  Chemist's  business  to  determine  its  properties,  to 
be  able  to  prove  its  individuality.  I  have  applied  the  principles 
which  I  have  just  expounded  to  the  detection  of  morphine,  iodine, 
strychnine,  brucine,  veratrine,  emetine,  colchicine,  aconitine, 
atropine,  hyoscyamine — and  I  have  succeeded  in  isolating,  without 
the  least  difficulty,  these  different  alkalies,  previously  mixed  with 
foreign  matters. 
