412 
PHARMACY  OF  THE  CINCHONAS. 
out  this  paper,  "a  funnel  prepared  for  percolation."  The 
magma  is  scarcely  transferred  to  the  funnel  before  the  dropping 
commences,  and  this  dropping  is  pretty  rapid  at  first;  but  with 
a  constant  and  plentiful  supply  of  menstruum  on  top,  if  the 
powder  be  very  fine,  the  dropping  rate  soon  diminishes  to  about 
20  to  22  drops  per  minute  and  so  continues  to  the  end.  When 
the  prescribed  6 ,  pints  and  10  f^.  of  Alcohol  is  used  on  top  in 
this  way,  it  happens  with  great  uniformity  that  6  pints  and 
about  2  fs  of  alcoholic  percolate  can  be  obtained  before  any  sign 
of  wTater  is  seen  in  the  percolate.  If,  however,  the  funnel  has 
a  very  close  cover,  and  the  point  passes  well  into  the  body  of 
the  flask,  and  especially  if  the  weather  be  cool,  all  of  which  cir- 
cumstances diminish  the  loss  by  evaporation,  6  pints  and  4 
or  even  6  pints  and  6  f 5  may  be  obtained  before  the  water  makes 
its  appearance  at  the  outlet.  Whan  it  does  so  appear  the  per- 
colation is  finished,  and  the  residue  in  the  funnel  will  be  found 
almost  tasteless,  except  the  lowest  strata,  and  there  but  moder- 
ately bitter. 
The  point  of  time  at  which  the  water  makes  its  appearance  is 
very  easily  seen  by  the  muddiness  produced  in  the  percolate. 
This  point  should  be  watched  for,  and  the  receiver  frequently 
changed,  to  avoid  getting  much  water  into  the  percolate. 
In  the  trials  with  these  percolations  to  determine  the  point  of 
practical  exhaustion,  the  percolates  were  assayed  repeatedly  for 
alkaloids  after  4  pints,  after  5  pints,  after  5J  pints,  and  after  6 
pints.  When  the  powder  was  fine,  alkaloids  precipitated  by 
ammonia  were  always  found,  even  after  6  pints,  but  the  propor- 
tion rarely  exceeded  4  grains  to  the  half-pint.  After  5  pints, 
the  6th  pint  usually  gave  about  1  grain  of  impure  alkaloids  to 
each  fluidounce  of  the  pint.  The  5th  pint  gave  a  much  larger 
proportion,  and  varied  more. 
The  percolate  after  the  6th  pint  is,  from  Red  Cinchona,  al- 
most as  dark  as  port  wine,  and  quite  bitter.  From  Yellow  Cin- 
chona it  is  sherry  wine  colored,  and  quite  bitter. 
necessary  to  take  out  from  an  accurately  filled  half  litre  flask,  27  cubic 
centimetres,  and  mark  this  new  level  lower  in  the  neck,  in  order  to  have 
a  standard  for  both  the  new  and  old  measures.  A  single  flask  carefully 
made  serves  to  make  others  by,  and  a  set  of  such  standards  once  estab- 
lished soon  become  indispensable. 
