410  PHARMACY  OF  THE  CINCHONAS. 
sirable  to  adopt  a  plan  which  required  the  least  skill,  and  would 
give  uniform  results  without  so  much  education  and  practice. 
The  plan  of  wetting  the  powder  into  a  uniform  fluid  magma  was 
found,  in  the  process  for  assay,  to  facilitate  the  perfect  exhaus- 
tion of  the  powder,  while  it  at  once  did  away  with  all  possible 
irregularity  in  rubbing  up  the  moist  powder  and  in  packing  it — 
the  two  points  so  essential  to  success — -and  those  which  require 
most  education  and  skill  in  their  proper  performance.  Beside 
this,  when  the  powder  is  wetted  into  a  uniform  liquid  magma  the 
air  in  great  measure  escapes  to  the  surface,  thus  diminishing  a 
troublesome  interference  with  uniformity  in  percolation,  and,  as 
the  writer  believes,  diminishing  the  oxidizing  effect  by  which 
this  interstitial  air  changes  a  part  of  the  alkaloids.  To  say  the 
least,  and  without  theorizing  upon  oxidation,  the  largest  pro- 
portion of  alkaloids  were  almost  invariably  obtained,  both  in  the 
assaying  and  in  the  practical  percolations,  when  the  powder  had 
been  wetted  to  a  uniform  magma  which  could  be  poured  into  the 
funnel,  or  on  the  small  scale,  could  be  slowly  transferred  on 
the  end  of  a  spatula,  to  avoid  smearing  and  loss.  By  allowing 
the  wetted  powder  to  stand  for  half  an  hour,  covered  to  prevent 
unnecessary  loss  of  Alcohol,  before  being  transferred  to  the 
funnel,  it  swells  and  absorbs  much  of  the  menstruum,  becoming 
much  less  fluid  than  when  first  mixed.  This  somewhat  facilitates 
the  exhaustion.  The  preparation  or  mounting  of  a  funnel  for 
percolation  requires  much  care  and  some  skill,  and  is  so  import- 
ant that  it  will,  even  at  this  late  day  in  the  career  of  percolation, 
warrant  a  detailed  description.  The  funnel  should  be  of  glass 
where  any  form  of  tannin  is  present  as  in  the  Cinchonas,  and  of 
a  size  not  less  than  8J  to  9  inches  across — the  larger  the  better, 
within  reasonable  limits,  since  it  holds  more  menstruum  on  top, 
and  thus  requires  less  attention  and  diminishes  loss  by  evapora- 
tion. This  should  have  as  close  a  cover  as  practicable,  and  an 
ordinary  breakfast  or  dinner  plate — not  turned  upside  down, 
but  set  into  the  funnel  with  the  rim  of  the  plate  on  the  edge  of 
the  funnel,  and  with  a  piece  of  oiled  muslin  or  oiled  silk 
under  it — serves  an  excellent  purpose.  The  funnel  should  be 
supported  in  a  funnel  board,  the  hole  being  of  such  a  size  as  to 
allow  the  funnel  to  pass  more  than  half  way  through,  and  the 
