526 
Campbell's  method  of  percolation. 
But  on  continuing  the  process  I  obtained  4  ounces  more  of 
nearly  as  deep  a  color,  and  from  all  appearances  having  fully 
the  strength  of  the  present  standard  article  of  the  U.  S.  P.  The 
drug  was  now  thoroughly  exhausted  and  tasteless,  but  in  ex- 
haustion had  yielded  20  ounces  of  extract.  The  process  repeated 
with  the  employment  of  some  menstruum  heated  previous  to 
mixing  vnth  the  bark  to  a^bout  200°  F.,  yielded  a  like  result, 
somewhat  richer,  apparently,  in  hydrocyanic  acid,  owing  proba- 
bly to  the  more  intense  reaction  of  the  warm  menstruum  with 
the  amygdalin  of  the  bark.  In  both  cases  I  failed  to  exhaust 
16  ounces  of  the  drug  in  16  ounces  of  the  menstruum. 
My  next  attempt  was  with  ergot,  which  I  treated  with  a  "  hy- 
dro-alcoholic "  menstruum,  obtaining  somewhat  better  results, 
L  e.  after  displacing  16  ounces  of  extract  from  16  ounces  of  the 
powder  (moderately  coarse)  I  obtained  a  further  quantity  of 
about  2  ounces,  certainly,  however,  too  strongly  charged  with 
the  recognizable  principles  of  the  drug  to  be  inert  or  useless. 
During  the  progress  of  these  experiments  and  others  yet  in- 
complete, I  have  been  led  to  think  that  a  quantity  of  any  men- 
struum sufficient  only  to  dampen  is  insufficient  to  dissolve  all  the 
extractive  matter  of  a  drug,  and  consequently  fails  to  exhaust 
it  when  displaced.  It  is  apparent  at  once  that  a  great  difference 
exists  in  the  absorbing  power  of  different  substances  to  be  treated  ; 
that,  for  instance,  the  quantity  of  liquid  that  would  convert  one 
ounce  of  powdered  blood-root  or  opium  into  a  pasty  or  creamy 
consistence,  would  render  an  ounce  of  powdered  digitalis,  senna 
or  cinchona,  only  very  slightly  damp.  I  can  conceive  that  when 
the  menstruum,  thoroughly  saturates  the  drug  so  as  to  cover  it 
when  properly  packed  in  the  percolator,  careful  displacement 
would  result  in  almost  completely  exhausting  it  after  due 
maceration.  But  when  16  ounces  of  a  given  menstruum  fall 
short  of  uniformly  and  completely  moistening  16  ounces  of  the 
drug  by  from  2  to  4  ounces,  it  must  surely  absorb  to  saturation 
from  the  displacing  liquid,  and  the  first  flow  of  16  ounces  must  \ 
leave  behind  much  that  is  useful,  and  therefore  falls  short  of  our 
idea  of  a  fluid  extract. 
That  a  fluid  extract  of  wild  cherry  bark  or  of  cinchona  of 
much  greater  strength  and  better  quality  than  the  officinal 
preparation,  of  which  at  most  one  and  a  quarter  ounces  shall 
