210 
ON  COLCHICIA. 
Bichloride  of  platina, — a  yellow  precipitate. 
Tinct.  ferri  chlorid. — no  precipitate  or  coloration. 
Dissolved  in  dilute  acetic  acid,  and  tincture  of  iodine  added, 
a  brown  precipitate,  dissolving  on  the  application  of  heat  and 
depositing  again  as  a  brownish  fiocculent  precipitate  as  the  liquor 
cools ;  ammonia  added  to  the  liquid  while  hot  prevents  this  de- 
posit. 
When  rubbed  up  in  a  mortar  with  cold  concentrated  sulphuric 
acid  it  dissolves,  forming  a  clear  solution  of  an  intense  yellow 
color ;  a  fragment  of  bichromate  of  potassa  added,  a  purplish 
color  passing  into  dirty  green  is  produced. 
A  fragment  of  nitrate  of  potassa  added  to  the  solution  in 
sulphuric  acid,  causes  a  beautiful  blue  color,  changing  to  green, 
then  greenish  black,  dark  brown  or  purple,  light  brown,  and 
finally  reddish  yellow,  which  last  color  is  permanent  for  at  least 
twelve  hours.  These  colors  merge  into  one  another  rapidly  and 
form  a  very  beautiful  experiment. 
Rubbed  with  ordinary  commercial' nitric  acid,  a  clear  yellow 
solution  is  formed ;  but  if  strong  red  fuming  nitric  acid  be  em- 
ployed, a  change  of  colors  is  produced  very  similar  to  that  caused 
by  sulphuric  acid  and  nitrate  of  potassa. 
The  most  delicate  of  these  appears  to  be  the  sulphuric  acid 
and  nitre  test.  I  have  obtained  a  satisfactory  reaction  with  less 
than  l-5000th  of  a  grain  of  colchicia  in  this  way.  The  most 
delicate  test  for  colchicia  in  solution  that  I  have  tried  is  tannic 
acid,  but  the  delicacy  of  this  reaction  is  much  impaired  where  a 
solution  of  a  salt  of  colchicia  is  employed  instead  of  the  alkaloid 
itself,  for  the  tannate,  although  almost  absolutely  insoluble  in 
pure  water,  is  dissolved  pretty  freely  by  dilute  acids. 
By  these  tests  colchicia  may  readily  be  detected  in  cases  of 
poisoning.  The  stomach  of  a  cat  which  had  been  killed  by  a 
dose  of  colchicia,  was  cut  into  small  pieces  and  macerated  in 
eight  fluid  ounces  of  alcohol,  s.  g.  .835,  for  twelve  hours,  filtered 
and  evaporated  at  a  gentle  heat  to  dryness.  The  extract-like 
matter  thus  obtained  was  treated  with  one  fluid  ounce  of  boiling 
distilled  water  and  the  solution  filtered.  Portions  of  this  liquid 
yielded  the  following  indications  of  the  presence  of  colchicia  : — 
tannin,  a  white  precipitate  ;  chlorine  water,  a  white  cloud ;  and 
ammonio-sulphate  of  copper,  a  green  precipitate  by  standing.  A 
