106 
ON  COLCHICIN. 
alkalies,  color  it  yellow.  If  dropped  into  strong  sulphuric  acid 
and  agitated,  each  particle  is  surrounded  by  a  green  tint  passing 
slowly  to  yellow ;  if  now  a  drop  of  nitric  acid  is  added,  it  is 
surrounded  by  a  zone  of  blue  which,  by  agitation,  becomes 
violet,  brown,  and,  finally,  yellow.  If  now  ammonia  is  added,  a 
beautiful  color  of  onion  peel  is  produced,  which  is  changed  to 
yellow  by  acids,  but  restored  by  alkalies. 
At  about  284°  F.,  colchicin  swells  up  like  a  resin,  but  it  fuses 
without  change,  except  in  color,  which  becomes  brow».  It 
burns  with  a  smoky  flame  and  residue  of  charcoal.  Potassa  dis- 
engages ammonia.  Its  composition  is  expressed  by  the  formula 
C34H19ITO10,  which  approaches  that  of  Atropia  C34H23N06,  from 
which  it  differs  but  by  -f-H4 — 04. 
M.  Huber,  like  M.  Oberlin,  considers  it  is  wrong  to  range 
colchicin  among  the  alkaloids  ;  it  is  indifferent  to  the  acids,  and, 
if  it  gives  with  them  a  crystallizable  compound,  the  latter  con- 
tains only  the  elements  of  colchicin.  M.  Oberlin  has  given  the 
name  of  coldiicein  to  this  crystallizable  principle,  to  which  M. 
Hubler  gives  the  per-centage  composition  of  colchicin. 
Colchicin  and  colchicein  are,  therefore,  isomeric.  The  latter 
acting  as  a  weak  acid,  displacing  carbonic  acid  from  carbonates. 
Alkaline  solutions  of  colchicein  cause  white  precipitates  with 
all  the  metals  which  give  colorless  salts,  green  with  ferric  salts, 
red  with  those  of  cobalt ;  yellowish  green  with  sulphate  of  cop- 
per. This  precipitate  is  formed  gradually,  becomes  crystalline, 
and  contains  colchicin  and  oxide  of  copper  in  equal  equivalents. 
All  these  compounds  are  soluble  in  alcohol. 
M.  Hubler  does  not  admit  the  pre-existence  of  colchicein,  but 
thinks  it  is  produced  by  the  action  of  acids,  and  perhaps  by 
bases  upon  colchicin. 
We  already  know  that  both  colchicin  and  colchicein  are  poi- 
sonous. M.  Hubler  believes  his  researches  enable  him  to  con- 
clude that  colchicin  is  only  poisonous  to  carnivorous  animals, 
and  that,  in  a  dose  in  which  it  would  poison  these,  it  appears 
without  action  on  herbivorous  animals.* 
*  This  conclusion  is  in  contradiction  to  the  observations  of  Schroffand 
others.  We  should  not  lose  sight  of  the  fact  that  these  experiments 
have  been  made  with  a  colchicin  very  different  from  that  employed  by 
Schroff,  which  was  made  by  the  process  of  Geiger. 
