A  August  wS™1' }     Economy  of  Time  in  Percolation.  537 
menstruum  was  added  and  after  thirty-two  minutes  the  liquid  began 
to  drop  from  the  lower  orifice  of  the  percolator,  but  percolation  pro- 
ceeded so  slowly  that  suction  was  applied,  and  250  cc.  of  percolate 
were  obtained  in  fifteen  hours — the  last  64  cc.  of  this  in  twenty-one 
minutes — and  this  portion  was  set  aside.  Percolation  was  continued 
and  the  second  portion,  measuring  750  cc.  was  obtained  in  the  next 
period  of  about  seventy-two  hours.  Menstruum  was  added  to  the 
marc  and  250  cc.  of  weak  percolate  were  obtained. 
The  activity  of  the  several  portions  of  the  percolate  were  esti- 
mated by  determining  the  amounts  required  by  intravenous  injec- 
tion to  kill  a  given  weight  of  cats.  The  test  showed  that  the  first 
portion  of  250  cc.  of  percolate  would  suffice  to  kill  about  2000  kilos! 
of  cats,  that  the  second  portion  of  750  cc.  would  suffice  to  kill  about 
1300  kilos,  and  that  the  weak  percolate  would  suffice  to  kill  only  about 
20  kilos,  or  less  than  1  per  cent,  of  the  total  of  the  first  and  second 
portions. 
DISCUSSION. 
The  results  obtained  with  tincture  of  nux  vomica  and  tincture 
of  aconite  speak  for  themselves  and  do  not  require  detailed*  discus- 
sion, but  it  is  interesting  to  observe  that  the  first  portion  of  250 
cc.  of  percolate  obtained  from  the  aconite  in  a  period  of  fifteen 
hours — without  previous  maceration,  except  for  the  two  hours  during 
which  the  moistened  drug  was  allowed  to  stand  before  being  packed 
— was  about  eighteen  times  as  active  as  an  equal  volume  of  the  last 
portion  of  750  cc.  which  was  obtained  by  percolation  during  a 
period  of  seventy-two  hours. 
One  may  be  disposed  to  argue  that  the  failure  to  exhaust  the 
powdered  strophanthus  completely  affords  evidence  for  the  need  of 
the  preliminary  maceration  directed  by  the  Pharmacopoeia.  Against 
this  is  the  fact  that  a  given  volume  of  the  first  portion  of  the  per- 
colate was  about  three  times  as  active  as  an  equal  volume  of  the 
second  portion.  The  explanation  of  the  failure  to  exhaust  the  drug 
completely  in  this  case  is  to  be  sought  in  the  physical  properties  of 
the  drug  and  its  active  principle.3 
The  cells  of  vegetable  drugs  afford  extensive  surface  areas 
which,  by  virtue  of  their  capacity  for  adsorption,  retain  traces  of 
many  active  principles  with  extraordinary  tenacity,  and  in  such 
cases  the  exhaustion  of  the  drug  is  dependent  upon  the  character  of 
the  solvent  and  the  volume  employed  to  a  much  greater  degree  than 
