Campbell's  method  of  percolation. 
525 
so  different  in  origin,  and  it  would  probably  be  conducive  of  a 
better  understanding  and  of  clear  ideas,  if  they  were  defined  in 
accordance  with  their  chemical  composition  as  gums,  gum-resins, 
oleoresins  and  resins  ;  and  as  juice  and  milk-juice  in  those  few 
instances  only  in  vfhich  the  composition  is  more  complex,  and 
the  drags  are  really  the  unaltered,  the  solidified  or  inspissated 
physiological  liquid. 
ON  CAMPBELL'S  METHOD  OP  PERCOLATION. 
Editor  American  Journal  of  Pharmacy. 
Dear  Sir : — Having  for  some  time  been  in  the  habit  of  pre- 
paring my  own  fluid  extracts,  and  having  with  some  success  ex- 
perimented outside  the  strict  requirements  of  the  Pharmacopoeia, 
I  was  favorably  impressed  with  the  theory  set  forth  in  the  Jour- 
nal for  Sept.,  by  Mr.  Samuel  Campbell.  But  while  my  experi- 
ments have  not  been  extended  enough  to  justify  me  fully  in 
opposing  a  theory  advanced  by  so  competent  an  authority  and 
apparently  based  on  thorough  trial,  yet  I  am  induced,  consider- 
ing the  importance  of  the  subject,  to  question  the  correctness  of 
some  of  Mr.  Campbell's  conclusions. 
My  first  experiment  was  with  the  bark  of  Prun.  Virg.,  where- 
in I  followed  Mr.  C's  formula,  using  equal  parts  of  pure  gly- 
cerin and  water,  reducing  the  bark  to  a  powder  "  moderately 
coarse."  I  found,  however,  that  16  ounces  of  the  menstruum 
were  required  simply  to  dampen  the  drug,  leaving  no  ''remain- 
der "  to  pour  into  the  percolator.  Thus  dampened,  the  drug 
was  packed  firmly  in  a  conical  percolator  and  allowed  to  macerate 
four  days,  at  the  end  of  which  time  I  commenced  the  displacing 
process,  carefully  arranging  the  displacing  liquid  (dilute  alcohol)* 
by  means  of  an  inverted  bottle  in  the  familiar  way,  so  as  merely 
to  compensate  for  the  percolation,  thereby  almost  totally  ob- 
viating any  admixture  of  menstruum,  and  displacing  liquid  dur- 
ing the  process,  in  my  opinion  a  very  important  precaution.  In 
twenty-four  hours  there  had  passed  16  ounces  of  the  extract,  of 
a  fine  deep  color,  possessing  the  properties  of  the  bark  in  a 
higher  degree  than  any  commercial  preparation  I  had  ever  seen. 
*  This  is  a  misunderstanding  of  Mr.  Campbell,  as  he  does  not  direct  an 
alcoholic  menstruum  for  wild  cherr   fluid  extract. 
