152  ON  THE  PKEPARATION  OF  FLUID  EXTRACTS. 
The  first  ounce  of  percolate,  after  half  an  hour's 
maceration,  yielded  of  extract,  94  grs. 
The  first  ounce,  after  2  days  maceration,  yielded       185  " 
u       u         u         a    4     a             i(.                 u  200  " 
The  first  4  oz.  of  percolate,  after  one  day's  mace- 
ration, yielded  of  extract,  279  grs. 
The  first  four  oz.,  after  2  days  maceration,  yielded  385 
a       u       u       u       u     4     a  u  it  a 
Or  upon  comparing  the  first  and  third  experiments,  the  first 
three  ounces  of  percolate,  after  long  maceration,  yielded  as  much 
solid  extract  as  three  ounces  and  two  pints  additional  after  a 
short  maceration.  It  will  also  be  observed  that,  after  four  ounces 
of  percolate  had  been  obtained,  eight  ounces  of  menstruum  ex- 
hausted the  drug  that  had  been  macerated  four  days,  more 
thoroughly  than  six  pints,  where  it  had  been  macerated  for  half 
an  hour. 
If,  upon  further  investigation,  it  should  be  found  that  the  ex- 
haustion of  some  particular  articles  is  not  complete,  the  passage 
of  a  small  additional  amount  of  menstruum,  and  the  reduction 
of  the  product  by  spontaneous  evaporation  to  the  required  mea- 
sure, would  no  doubt  successfully  accomplish  the  desired  end. 
The  longest  time  allowed  for  maceration  in  any  of  the  experi- 
ments made  by  Mr.  Campbell,  or  myself,  was  four  days.  It  is 
possible  that  in  some  cases  even  a  longer  maceration  might  be 
found  desirable,  but  since  the  results  of  all  the  experiments 
tried  were  satisfactory,  no  further  experiment  as  to  time  was 
tried. 
From  the  results  of  the  preceding  experiments,  it  might  be 
thought  that  the  use  of  glycerin  is  superfluous,  since  diluted 
alcohol  appears  to  be  sufficient  to  exhaust  the  drug ;  yet  1 
believe  that  in  this  and  in  many  other  cases,  it  is  a  valuable 
part  of  the  menstruum  ;  not  only  from  its  solvent,  but  also 
from  its  preservative  power  ;  but  whether  the  proportion  adopted 
is  the  best  one,  can  be  determined  only  by  experiment.  It  is  not 
probable  that  the  same  proportions  would  be  desirable  for  all 
drugs. 
In  regard  to  fineness  of  powder  for  making  fluid  extracts,  I 
believe  that  for  all  of  the  fluid  extracts  at  present  officinal  in 
