ON  COLOCYNTH. 
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ON  COLOCYNTH. 
By  Dr.  G.  F.  Walz. 
As  a  continuation  of  his  former  investigations  on  the  various 
constituents  of  colocynth,  the  author  now  gives  directions  for 
their  isolation  ;  we  extract  the  following  from  his  paper  : 
Bruised  colocynth  is  exhausted  by  alcohol  of  -84  spec,  grav., 
the  tincture  distilled  and  evaporated  to  dryness,  the  extract 
treated  with  cold  water,  the  solution  precipitated  by  sugar  of  lead, 
afterwards  by  subacetate  of  lead,  and  then  by  sulphuretted  hy- 
drogen; the  yellow  filtrate  is  precipitated  by  tannin  and  heated. 
The  resinous  mass  is  well  washed  with  water,  dissolved  in  alco- 
hol, precipitated  by  subacetate  of  lead,  the  filtrate  is  freed  from 
lead,  digested  with  animal  charcoal,  evaporated  and  well  washed 
with  anhydrous  ether  ;  the  golden  yellow  insoluble  part  is  colo- 
cynthin. 
That  part  of  the  alcoholic  extract  which  is  insoluble  in  water 
yields  to  ether  colocynthitin,  to  be  purified  by  treating  its  solution 
in  absolute  alcohol  with  animal  charcoal,  when  it  crystallizes  in 
brilliant  white  oblique  rhomboidal  prisms.  It  is  almost  insoluble 
in  cold  absolute  alcohol,  crystallizes  partly  from  the  hot  solution, 
another  part  gelatinizing  in  combination  with  alcohol  and  losing 
it  but  slowly.  Colocynth  contains  but  a  very  small  proportion  of 
colocynthitin. 
The  above  precipitate  with  sugar  of  lead,  after  decomposition 
with  hydrosulphuric  acid,  contains  a  reddish-brown  body,  with 
traces  of  colocynthitin  soluble  in  ether,  colocynthin  and  red 
brown  coloring  matter  soluble  in  water,  and  another  body  solu- 
ble in  alcohol.  The  sulphuret  of  lead  yields  to  hot  alcohol  colo- 
cynthitin, the  above  body  soluble  in  ether  and  alcohol,  and  the 
other  substance  soluble  in  alcohol. 
The  above  precipitate  with  subacetate  of  lead,  after  decompo- 
sition, furnishes  considerable  colocynthin,  very  little  matter 
soluble  in  ether,  but  principally  two  brown  coloring  matters,  one 
soluble  in  water,  one  in  alcohol.  The  sulphuret  of  lead  contains  a 
yellow  substance  soluble  in  ether,  a  little  colocynthitin  and  color- 
ing matter  soluble  in  alcohol. 
The  above  precipitate  of  sulphuret  of  lead  imparts  to  alcohols 
a  yellowish-red  color,  a  strongly  bitter  taste,  and  contains  the 
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