772 
The  Theory  of  Percolation. 
\  Am.  Jour.  Pharm. 
(    November,  1920. 
the  process  practically  in  this  country.  This  memoir  was  followed 
a  year  later  by  "Observations  on  the  Method  of  Displacement"  by 
Augustine  Duhammel  and  William  Procter,  Jr.^  in  which  the  ad- 
vantages of  the  new  process  are  clearly  stated  and  its  adoption  is 
recommended. 
BouUay's  Original  Displacement  Apparatus 
At  C-D  was  placed  a  metallic  diaphragm  pierced  with  holes  and  provided 
with  a  handle  and  fitting  accurately,  designed  to  prevent  the  escape  of  the  drug. 
At  A-B  a  similar  sieve  was  placed,  intended  to  hold  down  the  drug  and  scatter 
the  liquid  over  the  surface. 
Percolation  was  then  made  official  in  two  pharmacopoeias,  the 
Edinboro  pharmacopoeia  of  1838  and  the  U.  S.  P.  of  1840,  published 
in  1842.^ 
Percolation  quickly  became  a  popular  process  in  the  United  States ; 
it  does  not  appear  to  have  attracted  as  much  attention  in  any  other 
country  if  we  can  be  guided  in  judgment  by  the  absence  of  more  than 
scattering  comments  upon  it  in  the  foreign  journals.  American 
pharmacists,  however,  quickly  perceived  its  advantages  and  began 
to  study  and  apply  the  process.  In  1847,  H-  T.-EHis^  and  Wm. 
Procter,  Jr.^  published  formulas  for  the  fluidextracts  of  Valerian, 
and  Rhubarb  and  Valerian,  respectively,  and  these  papers  were  fol- 
lowed by  published  formulas  for  various  other  fluidextracts  by  Proc- 
1  This  Journal,  Vol.  11,  189,  (1839). 
^  This  Journal,  Vol.   14,   125,  (1842). 
^  This  Journal,  Vol.  19,  83,  (1847). 
^  This  Journal,  Vol.  19,  182,  (1847). 
