18  METHOD  OF  PERCOLATION  FOR  FLUID  EXTRACTS. 
his  own  preparations,  to  depend  upon  the  wholesale  dealer,  or 
grinder  of  drugs,  as  to  the  purity  of  his  powders,  it  being  almost 
impossible  for  him  to  powder  them  in  bis  own  laboratory,  as  it 
involves  so  much  time  and  labor  as  to  make  the  products  cost 
him  more  than  he  can  buy  them  of  the  large  manufacturer,  and 
as  a  consequence  he  cannot  compete  with  his  rival  or  neighboring 
store.  Take,  for  instance,  nux  vomica,  or  pareira  brava,  or  gentian 
root,  or  buchu  leaves,  and  what  facilities  are  there  in  any  retail 
drug  store  to  reduce  any  one  of  these  substances  to  a  powder, 
in  accordance  with  the  officinal  grade  of  fineness,  without  he  is 
willing  and  able  to  spend  two  or  three  days  over  a  drug  mill, 
or  pestle  and  mortar.    Another  objection  to  a  fine  or  very  fine 
powder,  is  a  fact  that  I  have  always  observed,  in  dampening  the 
powder  previous  to  packing  in  the  percojator,  which  is  the  for- 
mation of  small  pellets  all  through  the  mass,  caused  by  the  ag- 
glutination of  the  dusty  or  finer  particles  of  the  powder  the  moment 
the  moistening  liquid  reaches  it ;  and  it  is  almost  impossible  to 
avoid  such  a  result,  the  only  method  being  to  use  a  large  amount 
of  liquid,  so  as  to  form  a  pasty  mass,  which  then  becomes  im- 
practicable for  packing  solidly,  and,  in  all  such  cases,  an  im- 
perfect percolation  is  the  consequence.    In  my  method  I  have 
adopted  the  grade  of  powder  known  as  moderately  coarse.  Ar- 
riving at  such  a  conclusion,  after  having  made  a  novel  yet  in- 
teresting series  of  experiments,  which  I  shall  designate  as  the 
analysis  of  moderately  coarse  powders,  I  selected  twenty  dif- 
ferent drugs,  and  after  grinding  twice,  alternately  through  a 
Swift's  drug  mill,  and  sieving,  and  then  contusing  in  a  pestle 
and  mortar  until  the  whole  had  passed  through  a  No.  40  sieve, 
I  found  that  three-fourths  of  the  whole  quantity,  in  almost 
every  instance,  would  pass  through  sieve  No.  50,  known  as 
moderately  fine,  more  than  one-half  through  sieve  No.  60,  known 
as  fine,  and  one-third,  and  in  a  majority  of  cases  nearly  one- 
half,  through  No.  80,  known  as  very  fine,  leaving,  on  an  aggre- 
gate, a  balance  of  only  one-fourth  of  the  whole  quantity  of  the 
grade  No.  40.    Hence,  I  deemed  it  an  absurdity  and  a  waste 
of  time  and  labor  for  any  further  reduction  in  the  fineness  of 
the  powders.    And  the  practicability  of  the  idea  was  evidenced 
by  the  success  in  the  almost  entire  exhaustion  of  upwards  of 
