876 
The  Theory  of  Percolation. 
Am.  Jour.  Pharm. 
December,  1920. 
to  be  sure,  would  recover  a  large  part  of  this  retained  extract  but 
this  would  involve  other  difficulties  which  would  rob  the  method  of 
all  advantages. 
It  is  admitted  that  many  tinctures  may  successfully  be  prepared 
by  maceration  and  that  maceration  is  more  practicable  for  tinctures 
of  certain  resinous  drugs  than  percolation,  but  for  concentrated 
preparations  like  fiuidextracts  where  the  exhaustion  of  the  drug  is 
to  be  accomplished  with  as  little  menstruum  as  possible  maceration 
is  distinctly  a  failure.  This  seems  to  be  the  concensus  of  opinion 
among  American  pharmacists.^ 
The  following  figures^  show  plainly  that  maceration  does  not 
equal  simple  percolation.  750  Gms.  of  gentian  root  were  treated 
with  1950  Gm^i  of  dilute  alcohol.  One  such  batch  was  macerated 
for  four  days  and  pressed  out;  another  was  percolated. 
That  tinctures  made  by  maceration  precipitate  less  than  those 
made  by  percolation  is  hardly  true  for  the  majority  of  causes  for 
precipitation  exist  equally  in  both  cases.  With  fiuidextracts  where 
factors  which  induce  precipitation  are  introduced  by  the  evapora- 
tion of  weak  percolate  we  should  expect  more  of  this  feature.  It  is 
true,  however,  that  in  maceration  the  bulk  of  the  precipitation 
takes  place  in  the  macerating  vessel  and,  therefore,  is  not  as  ap- 
parent as  it  is  in  percolation  but  it  is,  nevertheless,  as  real. 
Percolation  is  unquestionably  a  more  complicated  and  difficult 
process  than  maceration  and  demands  more  knowledge  of  the  art 
of  pharmacy  from  the  operator  but  this  cannot  be  considered  a  valid 
argument  against  the  process.  We  have  a  right  to  demand  that  a 
pharmacist  be  familiar  with  and  expert  in  the  processes  of  his  art. 
Consequently  any  sacrifice  of  product  quality  for  the  sake  of  simpli- 
fying a  method  is  unjustifiable.  The  experience  of  a  century  has 
led  to  the  retaining  of  the  process  of  simple  percolation  as  the  best 
general  method  for  the  extraction  of  drugs. 
^  This  Journal,  Vol.  61,  187,  (1909). 
2  Herzog,  Ber.  d.  d.  Pharm.  Ges.  15,  107,  (1905). 
3  These  figures  added  by  the  writer. 
Percolated. 
Macerated. 
Volume  of  product, 
Specific  gravity, 
Dry  extract, 
Gm.  extract  per  100  Mils.^ 
1005  Mils. 
0.958 
185  Gms. 
18 .40  Gms. 
1530  Mils. 
0.931 
174  Gms. 
11.37  Gms. 
