114  Active  Constituents  of  Po(lophyllii\.  {^"'MaT'issr™" 
acid.  The  properly  waslicd  picropodopliylliii  crystals  aggregate  to  a 
felt-like  mass ;  after  drying  at  a  moderate  temperature  on  the  filter 
they  are  finally  obtained  in  the  form  of  a  snow-white  mass,  having 
a  silky  lustre.  The  alcoholic  picropodophyllin  solutions  have  an 
intensely  bitter  taste.  The  alcoholic  filtrate  and  wash  liquids  are 
concentrated  on  the  water-bath  to  a  small  volume,  and  the  picropodo- 
phyllin still  contained  therein  allowed  to  crystallize  out. 
Preparation  of  the  Remaining  Constituents  of  the  Officinal  Podo- 
phyllin. — The  picropodophyllinic  acid  can  be  isolated  from  the  podo- 
phyllotoxin  by  treating  the  latter  with  ammonia  water.  It  is,  how- 
ever, very  difficult  to  obtain  the  pure  acid  in  an  amount  sufficient  for 
chemical  examination,  as  ammonia  water,  which  is  the  only  substance 
which  can  be  employed  for  its  isolation,  causes  its  decomposition.  The 
resinous  podophyllinic  acid  is  separated  in  the  process  for  podo- 
phyllotoxin,  when  to  the  chloroform  solution  of  the  impure  principle 
ether  is  added.  Absolutely  pure  podophyllinic  acid  is  obtained 
when  the  precipitate  produced  by  ether  is  further  carefully  washed 
with  ether  for  the  purpose  of  removing  the  podopliyllotoxin ;  this 
operation,  however,  is  wearisome,  as  the  precipitate  must  be  treated 
several  times  with  chloroform  and  ether. 
The  fatty  matters  may  both  be  obtained  from  the  petroleum  ether 
solutions  which  remain  from  the  preparation  of  the  podophyllotoxin. 
The  petroleum  ether  is  either  distilled  off  or  expelled  by  evaporation, 
whereby  the  crystalline  fatty  matter  crystallizes  out  from  the  residue 
upon  long  standing.  It  is  pressed  between  bibulous  paper  and  purified 
by  repeated  solution  and  recrystallization. 
Podopkylloquercetin  can  be  best  obtained  from  such  varieties  of 
podophyllin  as  have  been  prepared  without  the  employment  of  alum 
water.  From  the  podophyllin  all  the  constituents  which  are  soluble 
in  chloroform  and  petroleum  ether  are  first  removed,  the  residue  dried, 
and  then  treated  with  ether,  whereby  the  podophylloquercetin  is  chiefly 
dissolved,  with  only  small  admixtures  of  foreign  products.  The 
ether  is  then  dissipated  by  evaporation  at  the  lowest  possible  tempera- 
ture, and  the  residual  yellowish  body  treated  with  acetate  of  lead, 
with  which  the  podophylloquercetin  forms  a  compound  of  a  yellow 
color,  soluble  in  acetic  acid.  This  compound  is  decomposed  in  the 
usual  way,  the  podophylloquercetin  taken  up  with  ether,  which  becomes 
thereby  of  a  yellow  color,  and  the  podophylloquercetin  finally 
obtained  in  the  form  of  a  yellow  powder  which,  by  exposure  to  the 
