Am.  Jour.  Pharm.  ) 
December,  1920.  i 
The  Theory  of  Percolation. 
875 
maceration.  This  is  a  very  convenient  form  of  percolator  and  is 
worthy  of  extended  trial.  In  the  writer's  experience  it  has  proved 
well  adapted  for  percolation  and  especially  for  interrupted  processes. 
With  this  apparatus  it  is  impossible  to  leave  the  drug  accidentally 
without  maceration  as  the  level  of  the  percolate  is  always  as  high 
as  the  inner  tube. 
Lloyd's  stilP  is  an  apparatus  designed  for  the  extraction  of 
drugs  and  the  concentration  of  the  percolate  without  the  risk  of 
alteration  due  to  heat.  The  apparatus  is  complex  and  the  reader 
must  be  referred  to  the  treatise  issued  by  Lloyd  Bros,  for  an  ex- 
tended description  of  it. 
A  simpler  form  of  apparatus  for  the  preparation  of  extracts  under 
reduced  pressure  was  suggested  by  Beard"  who  uses  a  percolator 
fitted  with  a  side  tube  like  the  larger  tube  of  a  Soxhlet  extractor  and 
conducts  the  percolation  in  a  partial  v^acuum. 
PERCOivATiON  versus  maceration. 
Maceration  as  a  process  for  the  extraction  of  drugs  has  ever  been 
a  rival  of  the  more  popular  process  which  supplanted  it  in  1833. 
From  time  to  time  advocates  of  maceration  rise  and  attempt  to  do 
away  with  percolation  as  the  official  process.  Weber, ^  Schmitt,'^ 
and  a  writer  in  the  Repertoire  de  Pharmacie-'  have  marshalled  argu- 
ments in  favor  of  the  older  method.  EdeP  has  answered  some  of 
these. 
It  is  claimed  that  the  products  made  by  maceration  are  more 
uniform  and  produce  less  precipitation  than  those  made  by  per- 
colation, that  the  process  is  very  much  simpler  and  not  so  liable  to 
accident  in  inexpert  hands,  and  that  it  takes  less  time. 
The  advocates  of  maceration  forget  that  the  process  of  per- 
colation was  designed  originally  to  remedy  a  serious  defect  in  the 
earlier  procedure,  namely  the  fact  that  a  certain  proportion  of  the 
extract  was  always  retained  in  the  drug  and  that,  therefore,  the 
liquid  extract  obtained  by  maceration  did  not  represent  100  per 
cent,  of  the  drug  but  only  a  fraction  of  that  figure.  Remaceration, 
'  U.  vS.  Patent  No.  777,115.    The  treatise  is  known  as  "The  Development 
of  the  Pharmaceutical  Still,"  1905. 
-  Jour.  Am.  Pharm.  Assn.  7,  964,  (191 8). 
3  Drug.  Circ.  1898,  216;  Pror.  A.  Ph.  A.  1899,  381. 
Pharm.  Ztg.  49,  102,  291,  (1904);  Proc.  A  .  Ph.  A.  1904,  283. 
■'  Proc.  A.  Ph.  A.  1882,  31- 
West.   Prufi.    1899,  57. 
