PHARMACY  OF  THE  CINCHONAS. 
295 
perly  adjusted,  transfer  the  bark  magma  to  the  funnel  with  the 
end  of  a  spatula,  depositing  the  first  portions  very  carefully 
within  the  little  filters,  so  that  these  may  be  pressed  uniformly 
out  against  the  glass.  Each  successive  portion  should  be  placed 
in  the  centre,  so  as  to  maintain  a  conical  pile  of  the  magma, 
which  tends  to  press  equably  downward  and  outward.  When 
the  funnel  is  filled  above  the  edge  of  the  filters  less  care  is  neces- 
sary, and  the  remainder  may  be  transferred  mOre  rapidly. 
When  the  entire  contents  of  the  basin  are  thus  collected  in  the 
funnel  a  little  tapping  on  the  surface  with  the  spatula  serves  to 
level  it  down,  and  the  funnel,  when  of  the  size  indicated,  is  found 
about  half  full.  The  portions  adhering  to  the  spatula 'having 
been  brushed  oiT  into  the  funnel,  a  four-inch  round  filter  is  cut 
in  toward  its  centre  for  about  a  quarter  of  an  inch,  at  intervals 
of  a  quarter  of  an  inch  or  so,  all  round  the  edge,  by  means  of  a 
scissors,  and  then  laid  with  some  care  upon  the  magma,  and 
gently  pressed  into  accurate  contact  over  the  whole  surface. 
The  cutting  round  the  edge  enables  the  edge  to  apply  itself 
smoothly  to  the  funnel  above  the  surface  of  the  magma,  and  a 
shallow  porous  cup  is  thus  formed  for  the  reception  and  equable 
distribution  of  the  menstruum.  The  funnel  is  then  filled  half 
way  up  to  the  edge  with  alcohol,  and  covered  with  a  round  filter 
or  piece  of  flat  paper,  a  little  larger  than  the  funnel,  and  is  set 
away  out  of  reach  of  accident.  The  dropping  commences  at 
once,  at  a  rate  at  first  proportionate  to  the  quantity  of  alcohol 
used  in  wetting  the  powder,  but  if  properly  arranged  as  described, 
it  soon  settles  down  to  a  rate  of  from  4  to  6  drops  per  minute 
and  thus  continues  to  the  end.  The  slower  the  percolation  the 
better  will  be  the  exhaustion  by  any  given  measure  of  men- 
struum ;  and  as  the  exhaustion  of  the  bark  is  the  prime  object 
and  the  most  difficult  part  of  the  whole  process,  a  slow  percola- 
tion must  be  attained  in  order  for  any  practical  degree  of  success. 
Under  the  prescribed  management  this  part  of  the  process  will 
take  care  of  itself,  and  ensure  its  own  success ;  for  it  will  be 
found  impossible  to  hasten  it  if  the  powder  be  fine,  and  there- 
fore all  that  is  necessary  for  the  operator  is  to  replenish  the 
menstruum  in  the  funnel  once  or  twice  in  each  24  hours,  and 
patiently  wait  for  the  proper  result.    Even  this  attention  to  re- 
