'^"Ni^CiS'L™''}  ^         Percolator.  571 
This  brings  us  to  a  point  of  the  greatest  importance  in  percolation. 
A  glance  at  the  Pharmaco])aMa  will  show  that  in  making  fluid  extracts, 
particularly  after  pouring  on  the  requisite  quantity  of  strongly  alco- 
holic menstruum  to  make  a  pint  of  finished  pi'oduct,  a  slightly  weaker 
alcoholic  menstruum  is  added  to  force  the  first  through,  the  latter 
being  absorbed  in  the  place  of  tlie  former.    This  is  its  object. 
With  our  new  percolator  this  for(;ing  the  first  liquid  through  is 
equally  as  well  accomplished  with  water.  Using  an  ounce  more  of 
menstruum  than  is  desired  to  be  obtained  in  the  finished  product  to 
insure  against  upward  diffusion,  and,  if  necessary  (according  to  the 
swelling  to  be  expected),  increasing  the  height  of  the  reservoir,  we  can, 
when  the  menstruum  is  all  absorbed  by  pouring  in  water,  collect  the 
full  amount  of  finished  product. 
We  thus  obtain  a  thoroughly  reliable  fluid  extract  without  the  use 
of  a  tincture  })ress  or  still  (to  reclaim  the  alcohol  absorbed  in  the  drug 
or  evaporated  according  to  the  U.  S.  P.),  without  more  waste  than  the 
one  additional  ounce  of  menstruum,  and  without  exposing  the  drug 
and  menstruum  to  the  air  during  the  process.  While,  of  course,  some 
time  is  needed  for  proper  maceration  and  for  regular  and  slow  percola- 
tion, a  far  greater  economy  of  time  is  secured  than  under  ordinary  cir- 
cumstances ;  for,  whereas  it  takes  often  days  and  weeks  for  a  percolation 
as  heretofore  conducted,  by  this  process,  with  some  drugs,  only  a  few 
hours,  or  a  day  at  the  most,  is  needed  for  practical  exhaustion. 
With  a  process  of  repercolation  reduced  to  a  single  reserve  still  less 
time  Avould  be  needed  to  secure  the  best  results. 
Such  drugs  as  rhubarb,  squill,  Colombo,  dandelion  etc.,  have  been 
percolated  with  proof  spirit,  and  percolation  finished  with  water, 
according  to  the  above  plan,  with  excellent  rasults.  1  have  not  found 
it  necessary  to  use  a  longer  tube  than  one  of  five  feet,  including  perco- 
lator and  reservoir,  except  in  working  with  rhubarb  and  squill,  when 
a  tube  eight  feet  long  answerd  very  well. 
The  new  process  of  cold  percolation  for  making  syrups,  for  filtering 
large  quantities  of  liquids,  such  as  oils,  elixirs,  syrups,  etc.,  works  well 
with  this  percolator.  In  making  tinctures  this  process  results  in  rapid 
work  and  economy. 
One  feature  noticeable,  also,  is  the  absence  of  evaporation  from  the 
surface  by  this  method  of  percolation.  In  percolating  on  a  large  scale 
the  economy  of  time  and  material  is  even  more  apparent  when,  after 
each  percolation,  it  is  necessary  to  empty  the  ])ercolator  of  its  contents 
