448  Preparation  and  Composition  of  Colchicin.  { '"^^  sept'^issr™' 
Avas  also  examined  by  the  author.  It  forms  a  brownish-yellow,  readily 
pulverizable  mass,  readily  soluble  in  water ;  it  is  permanent  in  the  air, 
and  is  not  decomposed  at  a  temperature  of  200°C.  It  feebly  reddens 
litmus,  and,  like  all  the  other  decomposition  products  of  colchicin,  is 
not  precipitated  by  tannic  acid. 
The  reaction  with  potassium  nitrate  and  sulphuric  acid,  or  with 
solution  of  potassa,  appears  with  this  substance  still  finer  than  with 
colchicoresin  and  beta-colchicoresin,  and  the  reaction  with  ferric  chlo- 
ride is  also  of  a  finer  color.  It  is  remarkable  that,  with  the  exception 
of  tannic  acid,  it  is  much  more  sensitive  toward  all  the  precipitants  of 
colchicin  than  the  latter,  and  is  also  affected  by  the  following  reagents,, 
which,  in  neutral  solutions  of  colchicin,  produce  no  reaction,  and  only 
afford  precipitates  in  strongly  acidulated  solutions.  Picric  acid  gives 
a  yellow,  and  potassio-cadmic  and  potassio-mercuric  iodides  a  yellow- 
ish-Avhite  precipitate.  Upon  ignition,  the  substance  left  2*502  per 
cent,  of  ash.  After  drying  at  115°C.,  the  substance  afforded  upon 
analysis  numbers  from  which  is  calculated  the  empirical  formula 
C5iH7gN2032.  This  analysis,  however,  has  naturally  but  little  value  as 
long  as  it  cannot  be  proven  that  the  substance  is  a  simple  and  definite 
body. 
A  number  of  physiological  experiments,  instituted  and  detailed  by 
the  author  for  the  purpose  of  deciding  the  question  wdiether  the  decom- 
position products  of  colchicin  still  retain  the  poisonous  properties  of 
the  latter,  or  whether  they  differ  therefrom  in  their  action,  have 
resulted  in  demonstrating  that  colchicein,  colchicoresin  and  beta-col- 
chicoresin retain  the  poisonous  properties  of  colchicin,  while  the  resi- 
due from  the  mother-liquid,  above  referred  to,  shows  in  doses  of  0*6' 
gram  no  toxic  action. 
Relations  between  Colchicin,  Colchicein,  etc. — In  order  to  determine 
the  proportions  in  which  beta-colchicoresin  and  colchicein  are  formed 
from  colchicin  by  heating  with  acids,  several  quantitative  experiments 
were  made,  which  have  led  to  the  result  that  the  formation  of  colchi- 
cein and  beta-colchicoresin  does  not  take  place  in  constant  proportions. 
As  a  rule  it  was  observed  that  the  less  colored  the  colchicin,  and  there- 
fore the  less  colchicoresin  it  contains,  the  yield  of  colchicein  is  larger, 
and  that  of  beta-colchicoresin  smaller.  This  circumstance,  as  well  as 
that  colchicoresin  upon  heating  with  acids  furnishes  only  beta-colchico- 
resin, induced  the  author  to  experiment  upon  the  decomposition  of  the 
purest  possible  colchicin.    For  this  purpose  colchicin  was  dissolved  ia 
/ 
