Am.  Jour.  Pharm, 
Mar.,  1882. 
I        Active  Comtituents  of  Podophyllin.  Ill 
podophyllinic  acid  is  separated  in  a  flocculent  form.  An  insufficient 
amount  of  ether  with  an  excess  of  chloroform  leads  to  the  result 
that  a  portion  of  the  podophyllinic  acid  remains  in  solution,  while 
an  excess  of  ether  on  the  contrary  is  without  injury  but  rather  of 
benefit  in  obtaining  a  proportionately  purer  preparation ;  the  excess  of 
«ther  can  only  in  so  far  be  inconvenient  as  that  larger  amounts  of 
petroleum  ether  will  be  subsequently  required  to  precipitate  the 
podophyllotoxin. 
Ether  containing  alcohol  must  be  absolutely  rejected,  as  then  a  por- 
tion of  the  podophyllinic  acid  which  is  readily  soluble  in  alcohol  will 
remain  in  solution  in  the  mixture  of  ether  and  chloroform,  and  it 
is  not  possible  to  remove  this  acid  by  further  treatment.    By  the  aid 
of  ether  one  can  determine  whether  podophyllinic  acid  is  still  contained 
in  the  respective  liquid ;  to  this  purpose  ether  is  allowed  to  flow  in  a 
thin  stream  on  the  sides  of  the  capsule  containing  the  podophyllo- 
toxin solution,  and  it  is  observed  whether  floccules  are  formed.  The 
podophyllinic  acid  is  deposited  at  the  close  of  the  operation  and  in  the 
course  of  time  in  the  form  of  dense  lumps  on  the  bottom  of  the  cap- 
sule.   The  liquid  decanted  from  the  residue  is  brought  upon  a  filter 
and  allowed  to  flow  directly  into  20  times  the  amount  of  pure  cold 
petroleum  ether.    From  each  drop  falling  into  the  petroleum  ether  a 
white  powder  is  separated,  while  the  fatty  substances  (the  fatty  oil  and 
crystallive  fatty  matter)  remain  in  solution.    If  altogether  too  small 
an  amount  of  petroleum  ether  is  employed  with  an  excess  of  the 
chloroform-ether  mixture,  the  deposited  powder  agglomerates  or  forms 
small  lumps,  which  partially  retain  the  fatty  substances;  with  the  use 
of  a  proportionately  large  excess  of  the  chloroform-ether  a  portion  of 
the  powder  becomes  dissolved.  The  agglomeration  to  small  lumps  occurs 
more  readily  in  proportion  to  the  incompleteness  of  the  removal  of 
the  podopliyllinic  acid ;  the  podophyllotoxin  must  then  be  subjected 
to  additional  purification,  for  which  purpose  to  the  liquid  in  which  in 
part  podophyllotoxin  is  still  contained  dissolved  fresh  portions  of 
petroleum  ether  are  added  until  complete  precipitation  is  effected. 
The  precipitate  is  filtered  from  the  petroleum  ether  and  dried  at  a 
temperature  not  exceeding  35°C.  The  residue  is  again  dissolved  in 
the  smallest  possible  quantity  of  chloroform,  the  solution  brought  upon 
a  filter,  and  again  allowed  to  drop  into  a  sufficient  amount  of  petro- 
leum ether,  whereby  a  few  drops  of  water  are  added  in  order  that 
the  precipitated  powder  may  become  slightly  moisten(Hl  witli  water. 
