2 1 6  Fluid  Extracts  by  Rep er eolation.      }  Am^°y%?7h8arm- 
exhaustion  becomes  poorer  in  medicinal  efficacy  and  richer  in  inert 
extractive  matter,  and  that  this  divergence  in  value  is  greatest  near  the 
end  of  the  process,  the  quantity  of  dry  extract  yielded  by  each  fraction 
of  the  percolate  is  adopted  as  the  most  convenient  measure  of  the  rate 
and  the  extent  of  the  exhaustion. 
The  want  of  uniformity  introduced  into  this  series  of  percolations 
by  the  variation  in  the  quantity  of  liquid  used  to  moisten  the  several 
portions  of  the  powder,  and  the  variation  in  the  time  of  maceration, 
diminishes  the  value  of  the  series  as  illustrative  of  the  best  results  of 
repercolation ;  and  made  it  advisable  to  add  a  fifth  and  a  sixth  percolation 
to  show  the  true  character  of  the  process  when  fairly  established  in 
actual  practice;  and  thus  these  two  percolations  become  by  far  the  most 
valuable  of  the  series  as  results  of  repercolation  in  actual  practice, 
whilst  the  formula  and  process  merely  show  how  to  begin  to  use 
srepercolation. 
The  formula  and  process  now  to  be  given  embrace  the  experience 
obtained  in  making  the  series  which  it  represents,  and  is  ofFered  as  a 
model  by  which  other  trials  should  be  made  by  other  hands,  with  other 
varieties  of  Cinchona. 
Take  of  Yellow  Cinchona,  in  powder  No.  50,  .  .    32  parts. 
Stronger  Alcohol,1  s.  g.    -819  at  1 5.6°C.=6o°F., 
or  s.  g.    -8 1 1  at  25    °C.=77°F.,  2  parts.  )     For  a  suf- 
Glycerin,  s.  g.  1-250  at  i5'6°C.=6o°F.,  •  flcient  quan- 
or  s.  g.  1 '244  at  25    °C.=77°F.,  1  part.    [        tity  of 
Water,  .  .  .  .2  parts.  J  menstruum. 
Weigh  the  Stronger  Alcohol,  Glycerin  and  water  in  succession,  in 
any  convenient  quantity  at  a  time,  into  a  tared  bottle,  and  mix  them 
thoroughly  for  a  menstruum. 
Moisten  8  parts  or  the  Cinchona  with  8  parts  of  the  menstruum,  by 
thoroughly  mixing  them,  and  allow  the  mixture  to  stand  8  hours  in  a 
closely  covered  vessel.  Then  pass  the  moist  powder  through  a  No.  8 
sieve,  and  pack  it  firmly  in  a  percolator.  Pour  menstruum  on  top  until 
the  mass  is  filled  with  liquid  and  a  stratum  remains  on  top  unabsorbed  ; 
cover  the  percolator  closely  and  macerate  for  48  hours.     Then  arrange 
1  It  is  hoped  that  in  the  next  revision  of  the  Pharmaccepia  the  " Alcohol "  (s.  g. 
'835)  may  be  dropped,  and  the  simple  name  Alcohol  be  applied  to  a  clean  spirit,  of 
about  the  s.  g.  here  given. 
