568 
A  New  Percolator. 
j  Am,  Jour.  Pharm. 
t      Nov.,  1881. 
as  to  allow  of  sufficient  resistance  to  the  liquid  to  prevent  its  too  rapid 
floAV,  yet  not  enough  to  stop  it. 
3d.  The  powder  must  be  packed  with  greater  force  toward  the  top 
than  toward  the  bottom,  in  proportion,  to  cause  a  more  even  flow  of 
the  liquid. 
4th.  It  should  be  sufficiently  moistened  with  menstruum  before 
packing  to  cause  an  even  flow  of  liquid,  and  to  partially  soften  or  dis- 
solve the  material  within  the  cells,  so  that  a  more  rapid  osmosis  can 
take  place. 
5th.  Glycerin  is  of  questionable  value  as  a  means  of  penetrating 
cells,  or  in  assisting  in  solution,  compared  mth  water  and  alcohol,, 
since  it  is  not  likely  to  assist  osmosis. 
6th.  The  menstruum  should  be  adjusted  to  the  drug,  keeping  in 
view  the  best  and  cheapest  solvent,  without  wasting  alcohol  or  other 
expensive  menstrua,  except  when  practical  results  are  otherwise  unat- 
tainable. 
Bearing  in  mind  these  objects,  and  knowing  what  difficulties  we 
have  to  encounter,  let  us  seek  a  remedy. 
If  it  is  possible  to  increase  the  downward  pressm^e  of  the  liquid 
sufficiently  to  overcome  the  lateral  pressure  of  the  drug,  we  obtain  a 
means  of  percolating  without  resorting  to  the  necessity  of  employing 
a  stronger  alcohol  or  reducing  the  fineness  of  the  powder.  Also,  as 
the  advantage  of  percolation  is  based  upon  the  ability  of  the  liquid  to 
penetrate  by  absorption  the  interior  of  the  cell  fully  or  nearly  as  rap- 
idly as  to  pass  by  and  around  them,  one  of  the  tests  of  merit  in  con- 
ditions must  be  the  ability  to  reach  the  inteyioi'  while  retarding  the 
flow  hetioeen  the  cells.  A  menstruum  can  reach  the  interior  better 
when  the  drug  is  well  packed  than  when  loosely  packed,  since  then 
each  drop  will  have  its  attraction  of  gravitation  largely  overcome  by 
capillary  and  osmodic  attraction,  and  must,  in  a  comparative  sense,  go 
through  the  cells  and  into  them  at  nearly  the  same  rate  as  it  goes 
around  them  and  by  them. 
It  was  in  endeavoring  to  solve  some  of  these  problems  of  percola- 
tion, more  especially  the  means  of  overcoming  the  swelling  of  the- 
drug,  that  I  have  been  led  to  construct  the  new  percolator  and  process 
described  and  illustrated  below.  How  well  it  is  adapted  to  meet  the 
difficulties  we  encounter  will  be  easily  seen. 
I  have  simply  reversed  the  ordinary  percolator,,  attaching  a  long; 
tube  (rubber  usually  answers)  to  the  nozzle,  and  connected  it  to  the^ 
