AmMay%87h8arm  }     Fluid  Extracts  by  Rep er eolation.  247 
bottle  in  grammes  and  in  grains  marked  in  ink  at  its  lower  end,  and 
should  then  be  varnished.  Then  the  graduation  marks  may  be  made 
with  pencil,  and  be  rubbed  out  and  replaced  as  different  graduations  may 
be  required  for  different  substances,  the  graduations  merely  indicating 
when  to  try  the  weight  of  the  accumulating  percolate.  A  wooden 
stand,  7w,  is  necessary  for  the  larger  percolator  to  enable  the  receiving 
bottle  to  be  conveniently  removed  and  replaced  without  disturbing  the 
syphon  ;  and  wooden  blocks,  72,  are  necessary  to  support  the  receiving 
bottles  at  various  heights.  As  a  general  indication,  the  rate  of  drop- 
ping from  the  smaller  percolator  should  be  about  6  or  8  drops  to  the 
minute,  and  for  the  larger  one  about  10  to  12  to  the  minute.  But  it 
should  always  be  borne  in  mind  that  the  rate  cannot  be  uniform  with- 
out some  self-feeding  arrangement  that  will  preserve  a  uniform  stratum 
of  liquid  upon  the  surface  of  the  substance,  and  that  with  such  an 
arrangement,  the  slower  the  rate  the  more  perfect,  and  the  more  econ- 
omical the  exhaustion  will  be.  With  a  rate  of  2  or  3  drops  a  minute 
the  results  are  practically  perfect,  when  th  j  conditions  of  fineness  of 
powder,  and  appropriate  menstruum  are  properly  fulfilled. 
The  maceration  for,  at  least,  48  hours  is  useful  for  many  reasons, 
chiefly  that  the  adjustment  of  temperatures  and  solubility  may  take 
place  fully  and  naturally  : — that  the  particles  may  be  thoroughly  per- 
meated by  the  liquid,  and  the  liquid  become  saturated.  And  because 
if  the  maceration  be  omitted,  the  percolate,  in  many  cases,  will  not  be 
entirely  bright  or  clear.  Then  as  a  rule,  the  longer  the  maceration 
within  reasonable  limits,  the  stronger  will  be  the  percolate  that  comes 
next  after  the  maceration, — no  matter  at  what  stage  of  the  repercola- 
tion  the  maceration  be  applied. 
When  the  maceration  is  completed  and  the  percolation  to  be  started 
the  syphon  is  put  in  place  with  about  3  inches— 7*2  centimetres  of  the 
inner  leg  immersed  in  the  liquid  of  the  well-tube.  Then  the  best  way 
to  start  the  syphon  is  by  means  of  a  piece  of  glass  tubing  of  the  same 
size  as  the  syphon  and  any  convenient  length,  armed  at  one  end  with 
a  short  section  of  rubber  tubing  of  such  size  as  to  slip  over  the  end  of 
the  turned  up  part  of  the  syphon  easily,  but  fitting  tightly, — or  being 
tied  onto, — the  end  of  the  piece  of  glass  tubing.  The  syphon  and 
receiving  bottle  being  now  in  position  to  start,  the  rubber  end  of  the 
glass  tube  is  passed  into  the  neck  of  the  receiving  bottle  and  down  till 
the  rubber  slips  over  the  end  of  the  turned  up  portion  of  the  syphon. 
