Am.  Jouf.  Pharm.  ) 
November,  1920.  ) 
The  Theory  of  Percolation. 
771 
in  manipulation  and  careless  in  detail.  Nor  is  this  lack  of  proper 
appreciation  of  the  principles  which  underlie  the  process  confined  to 
such  men;  one  questions  the  average  pharmaceutical  graduate  in 
vain  along  lines  which  demand  a  broad,  general  survey  of  the  sub- 
ject. 
The  result  of  such  conditions  appears  at  once  in  the  products. 
An  examination  of  fiuidextracts  of  different  manufacture  will  reveal 
astonishing  diversities  in  products  made  from  the  same  drug  and, 
presumably,  by  the  same  process. ^  Even  in  the  case  of  the  assayed 
preparations,  the  standard  quantity  of  alkaloid  or  other  active  com- 
ponent is  usually  the  only  point  of  agreement. 
It  has,  therefore,  appeared  desirable  to  survey  our  whole  published 
knowledge  of  the  process  of  percolation,  widely  scattered  as  it  is 
throughout  the  literature  and  much  of  it  inaccessible  to  the  average 
worker;  to  examine  it  critically,  state  what  facts  appear  definite,  and 
particularly  to  direct  attention  to  those  questions  which  have  not 
been  investigated  or  which  have  been  left  in  vSuch  an  indefinite  con- 
dition that  further  research  is  necesssary  to  answer  them. 
HISTORICAL  DATA. 
The  beginnings  of  percolation  as  a  pharmaceutical  process  have 
been  traced  in  an  earlier  memoir^  and  do  not  need  extended  descrip- 
tion in  this  place.  It  is  there  shown  that  the  credit  for  the  establish- 
ment of  the  process  of  percolation  in  pharmacy  is  due  to  the  Boullays 
of  Paris,  who,  in  1833,  published  their  work  on  the  process  of  displace- 
ment,^ and  detailed  discussion  of  the  previous  work  of  Real,  Cadet, 
Robiquet  and  others  is  included.  The  earliest  American  notice  of  the 
process  is  the  quotation  of  M.  Soubeiran's  memoir  on  "displacement" 
in  this  Journal.*  Augustine  Duhammel,^  was  the  first  American  to 
publish  any  account  of  an  original  examination  of  the  process.  He 
states  that  the  process  had  been  in  extensive  use  in  Germany,  "and 
elsewhere"  for  twenty  years  and  that  E.  Durand  was  the  first  to  use 
*  Haussmann,  Proc.  A.  Ph.  A.  1895,  564;  Lloyd,  This  Journal,  Vol.  80,  p.  39; 
A.  Conrath,  Proc.  A.  Ph.  A.  1882,  545;  Spenzle,  Proc.  A.  Ph.  A.  1882, 
547;  Linde  Ph.  Centr.  1894,  39;  This  Journal,  Vol.  66,  p.  141;  C.  L. 
Diehl,  Proc.  A.  Ph.  A.  1878,  681. 
2  This  Journal,  Vol.  91,  16,  (191 9). 
3  Jour.  de.  Pharm.  19,  2281,  (1833);  19,  393,  (1833). 
4  This  Journal,  Vol.  8,  221,  (1836). 
*  "Boullay's  Filter  and  System  of  Displacement  with  Observations  Drawn 
from  Experience."    This  Journal,  Vol.  10,  i,  (1838). 
