858 
The  Theory  of  Percolation. 
{Am.  Jour.  Pharm. 
December,  1920. 
were  extracted  more  rapidly  than  the  inert  compounds  so  that  the 
first  portions  of  the  percolate  contained  a  larger  percentage  of  the 
alkaloids  or  resin  than  the  total  extract.  Squibb' s^  results  are 
plotted  as  Charts  C  and  D  and  plainly  show  the  phenomenon.  Lloyd 
/SlW 
(COO 
s 
0 
f 
s 
6 
Chart  C. 
has  confirmed  this  observation  by  several  experiments,  notably  upon 
cannabis  and  cascara.^ 
A  second  variable  factor  may  arise  if  menstrua  of  certain  types 
are  employed.  These  types  of  menstrua  include  hydro-alcoholic, 
glycerinated,  and  acidulated  menstrua.    It  frequently  happens  that 
1  This  Journal,  Vol.  38,  109,  (1866.)    Vol.  39,  289,  402,  (1867). 
2  Proc.  A.  Ph.  A.  1881,  408. 
