i$  Early  History  of  Percolation.       {Al£-  -Tour-  Pharm- 
10  J  J     J  1     January,  19 19. 
when  filled  with  water,  hydrostatic  pressure  upon  the  contents  of  the 
"  press."  For  such  occasions  where  more  pressure  was  required 
than  would  be  furnished  by  the  column,  Real  contrived  a  shorter 
column  of  mercury  arranged  to  exert  its  pressure  indirectly  upon  the 
press.    Cadet  thus  describes  the  operation  of  the  press : 
"  Une  poudre  vegetal,  equisee  de  principes  solubles  et  detemperee 
avec  de  l'alcohol  rectifie,  est  mise  dans  l'appareil ;  on  fait  agir  dessus 
la  colonne  d'eau.  Cette  eau  ne  se  mele  point  avec  l'alcohol :  celui-ci 
passe  au  meme  degre  areometrique  qu'il  avait  avant  l'experience. 
"  Le  filtre-presse  me  parut  done  infinitement  utile  et  meme  in- 
despensable  pour  preparer  les  extraits  des  plantes  dont  les  principes 
immediate  sont  alteres  par  la  caloric." 
The  drug  was  moistened  and  allowed  to  swell  before  being  placed 
in  the  apparatus.  Cadet  reports  good  results  in  using  this  method 
with  cinchona,  belladonna,  aconite,  and  conium.  The  method  was 
not  in  any  sense  a  process  of  percolation;  the  drug  was  not  ex- 
hausted by  the  addition  of  successive  quantities  of  menstruum  but 
was  handled  exactly  as  in  the  old  process  of  maceration  with  the 
exception  that  the  marc  was  freed  from  adhering  tincture  through 
displacement  instead  of  by  pressing  out  in  a  tincture  press.  Cadet, 
far  from  realizing  the  possibilities  which  lay  in  the  apparatus,  pre- 
ferred the  older  process,  saying  of  Real's  press : — "  la  manipulation 
est  longue,  compliquee,  minutieuse." 
During  the  following  year  Johnson5  described  the  preparation  of 
an  infusion  of  cinchona,  for  which  he  used  an  apparatus  and  process 
no  different  from  that  described  by  Rumford,  and  similar  to  one 
which,  he  says,  was  made  by  Edmund  Loyd  &  Co.  "  several  years 
ago." 
In  1825  Donovan6  described  an  apparatus  for  filtering  caustic 
soda  out  of  contact  with  the  atmosphere.  Although  he  did  not  apply 
it  to  the  extraction  of  drugs  it  is,  in  fact,  an  anticipation  of  many 
forms  of  percolators  designed  to  prevent  loss  of  volatile  menstrua. 
The  percolator  is  fitted  tightly  into  a  receiver  furnished  with  a  side 
neck  from  which  a  tube  extends  upward  and  is  bent  to  fir  into  the 
top  of  the  pecolator  through  a  stopper.  Arny7  and  others  have  sug- 
gested similar  arrangements. 
5  Thompson's  Annals  of  Philosophy,  vol.  9,  p.  451,  1817. 
6  Annals  of  Philosophy,  August,  1825,  Jour,  de  Pharm.,  vol.  11,  p.  519,  1825. 
7  Proc.  Am.  Ph.  A.,  vol.  40,  p.  169,  1892. 
