Am.  Jour.  Pharm.  ) 
December,  1920.  1 
The  Theory  of  Percolation. 
857 
uniform  in  its  chemical  and  therapeutical  value  as  obtained  during 
the  different  stages  of  the  percolation,  but  diminishes  in  effective 
value  far  r  iore  rapidly  than  the  extract  does  in  weight."  In  sup- 
port of  th'S  statement  he  reports  experimental  results  showing  the 
5 
O  f/r     e.  0 
Chart  B. 
weight  of  total  extract  obtained  from  fraction  of  a  percolate  and  its 
content  of  some  active  material.  These  results  show  conclusively 
that  there  is  a  great  difference  in  the  rate  at  which  the  various  soluble 
matters  of  a  drug  are  extracted  by  the  menstruum,  and,  in  the  cases 
which  vSquibb  chose,  the  pharmacologically  important  substances 
