THE  PROCESS  OP  PERCOLATION. 
101 
the  reservoir  may  be  of  India-rubber  tubing,  and  as  it  is  only 
this  portion  of  the  air  tube  that  need  be  so  large,  it  is  very  con- 
venient to  arrange  it  thus  :  slipping  the  larger  India-rubber 
portion  over  the  smaller  glass  portion. 
With  a  four  gallon  reservoir  of  menstruum,  and  a  receiver  of 
corresponding  size,  this  apparatus  will  take  care  of  itself  until 
the  process  is  finished ;  and  the  writer,  in  a  slow  percolation,  for 
saturated  tinctures,  for  instance,  has  often  had,  it  to  run  on  eight 
or  nine  days  untouched. 
Another  convenient  form  of  percolator,  which  the  writer  con- 
trived, and  has  often  used  on  various  scales  from  a  quart  specie 
jar  up  to  a  hogshead,  has  some  advantages,  particularly  on  the 
large  scale,  as  where  a  barrel  of  menstruum  is  to  be  used  as  in 
exhausting  sarsaparilla,  &c,  for  compound  syrup.  Figure  2, 
represents  this  arrange- 
ment of  apparatus,  except 
that  it  is  not  necessary  to 
represent  the  feeding  re- 
servoir. Where  the  sup- 
plying arrangement  of  the 
last  drawing  is  used,  it  is 
done  simply  by  mounting 
the  barrel  of  menstruum 
upon  a  proper  stand  above 
the  level  of  the  cover  of 
the  percolator,  and  then 
adapting  the  large  India 
rubber  air  tube  to  the 
bung  hole,  and  putting  an 
ordinary  faucet  in  any  low  portion  of  the  barrel ;  or,  more  simply, 
as  the  writer  has  done,  by  using  a  small  India-rubber  tube  for  a 
feeding  syphon,  inside  of  the  large  one  for  air,  allowing  the 
small  one  to  project  two  inches  below  the  larger  one,  where  they 
pass  through  the  funnel  opening  at  g  ;  and  ensuring,  by  a  weight 
attached,  that  the  other  end  of  the  small  tube  goes  to  the  bottom 
of  the  barrel.  By  this  simple,  easy  arrangement,  any  operation 
of  percolation  or  washing  may  be  performed  at  any  rate  of  speed 
or  to  any  desirable  extent. 
a  is  a  simple  stool  upon  which  stands  the  tub  or  other  perco- 
