Am  jour  Pharm. )  Studies  in  Extraction.  423 
June,  1921.  ) 
same  numerical  increases  or  decreases  observed  in  the  attempt  to 
calculate  a  distribution  r^tio.  The  factors  applied  in  these  formulas 
were  functions  of  the  concentration  of  extracted  matter,  undissolved 
extractive  (this  included  that  in  the  marc,  that  dissolved  in  the  ab- 
sorbed menstruum,  and  that  dissolved  in  the  percolate)  and  time. 
The  lack  of  constancy  in  the  results  indicates  that  there  are  other 
factors  which  influence  the  rate  of  extraction,  and  we  may  here  con- 
sider two  :  ( 1 )  V ariation  in  the  composition  of  the  extract  ;4  the 
more  soluble  matters  are  extracted  first,  leaving  the  more  refractory 
substances  to  the  less  saturated  portions  of  the  menstruum ;  and  (2 ) 
variation  in  the  alcoholic  strength  of  the  menstruum,5  with  a  conse- 
quent change  in  its  solvent  powers.  The  observed  difference  in  alco- 
holic strength  between  the  first  and  the  twentieth  gallons  of  percolate 
in  this  extraction  was  over  7  per  cent.  The  first  few  gallons  were 
diluted  by  the  natural  moisture  of  the  poke  root,  which  amounted  to 
three  or  four  pints,  a  quantity  capable  of  seriously  altering  the  sol- 
vent power  of  the  menstruum.  The  fact  that  the  alcoholic  strength 
of  the  mentsruum  increases  would  lead  to  an  assumption  that  the  sol- 
vent powers  of  the  menstruum  increase  as  percolation  proceeds  and 
it  is  possible  that,  as  the  drug  becomes  more  difficult  to  extract,  the 
menstruum  becomes  more  able  to  dissolve  the  extractive,  but  not 
proportionally.  The  two  factors  will  thus  tend  to  neutralize  one 
another.  With  our  present  knowledge,  however,  it  does  not  seem 
possible  to  characterize  the  rate  of  extraction  of  any  drug  by  a  factor 
which  will  represent  conditions  at  any  point  in  a  percolation. 
EXPERIMENTAL. 
A  quantity  of  phytolacca  was  purchased  on  the  open  market, 
identified,  and  ground  to  a  coarse  powder;  19,876  Gm.  of  this  drug 
were  percolated  according  to  the  directions  of  the  U.  S.  P.  8.  The 
drug  was  mixed  with  five  gallons  of  diluted  alcohol  in  a  mechanical 
mixer,  and  the  whole  was  packed  firmly  in  a  galvanized  iron  perco- 
lator of  about  twenty-five  ^gallons  capacity.  This  particular  weight 
of  drug  was  chosen  so  that  the  experiment  might  furnish  somewhat 
more  than  five  gallons  of .  fluidextract  of  official  strength. 
The  percolator  was  set  in  place,  enough  menstruum  was  added 
to  displace  the  air  and  leave  a  stratum  above  the  drug.   The  appara- 
4Cf.  Squibb,  this  Journal,  38/109  (1866)  ;  39/402  (1867)  ;  40/1  (1868). 
5Cf.  Lloyd,  Proc.  A.  Ph.  A.,  1881/408;  1882/508. 
