340 
ON  FRACTIONAL  PERCOLATION. 
In  reserve  for  1  f.  ounce  of  fluid  extract,  96  grains 
In  additional  percolate  for  24  f.  ounces  of  fluid 
extract  886  grains. 
In  additional  percolate  for  1  f.  ounce  of  fluid  extract  37  grains. 
In  1  fluid  ounce  of  finished  fluid  extract  133  grains. 
Ill  exhaust  percolate  for  24  f.  ounces  of  fluid  ex- 
tract, 168  grains. 
In  exhaust  percolate,  for  1  f.  ounce  of  fluid  extract  7  grains. 
From  1  troy  ounce  of  Alexandria  senna  140  grains. 
Summing  up  the  results  of  the  foregoing  experiments  it  will 
be  found  that  the  fluid  extract  made  by  fractional  percolation 
contains  thirteen  grains  less  of  solid  matter,  in  a  fluidounce, 
than  the  oflScinal  fluid  extract,  but  on  the  other  hand  it  contains 
one  hundred  and  twenty  grains  of  solid  matter,  that  is  not 
heated,  while  the  officinal  fluid  extract  contains  but  ninety-six 
grains. 
Experiment  3. — Twenty-four  troy  ounces  of  India  senna,  in  moderately 
fine  powder,  was  treated  by  fractional  percolation  in  precisely  the  same 
manner  as  indicated  in  Experiment  1,  with  the  following  result: 
Amount  of  solid  extract — 
In  24  f.  ounces  of  fluid  extract  3,072  grains. 
In  1  f.  ounce         "       "  128  grains. 
In  exhaust  percolate  for  24  f.  ounces  of  fluid 
extract  520  grains. 
In  exhaust  percolate  for  1  f.  ounce  of  fluid  extract  21*5  grains. 
From  1  troy  ounce  of  India  senna  149*5 
Experiment  4. — A  repetition  of  Experiment  2,  substituting  India  for 
Alexandria  senna,  gave  the  following  result : 
Amount  of  solid  extract — 
In  reserve  for  24  f.  ounces  of  fluid  extract        2,400  grains. 
In       "     "    1  f.  ounce  "       "  100  grains. 
In  additional  percolate  for  24  f.  ounces  of  fluid 
extract  1,044  grains. 
In  additional  percolate  for  1  f.  ounce  of  fluid  extract  43*5  grains 
In  1  fluid  ounce  of  finished  fluid  extract  14*35  grains. 
In  exhaust  percolate  for  24  f.  ounces  of  fluid 
extract  174  grains. 
In  exhaust  percolate  for  1  f.  ounce  of  fluid  extract  7  25  grains. 
From  1  troy  ounce  of  India  senna  150*75  grains. 
The  results  of  the  last  two  experiments  correspond  practically 
with  Experiments  1  and  2.    While  the  fluid  extract,  made  by 
