296 
PHARMACY  OF  THE  CINCHONAS. 
plenish  the  supply  of  menstruum  may  be  conveniently  saved  by 
placing  8  or  10  fluidounces  of  the  alcohol  in  a  vial  and  fitting 
the  vial  with  a  cork  perforated  with  a  glass  tube  two  or  three 
inches  long  and  not  less  than  a  quarter  of  an  inch  in  diameter, 
and  broken  off  obliquely  or  raggedly  at  the  outer  end.  This  vial 
and  tube  held  inverted  over  the  funnel,  in  any  convenient  way, 
with  the  end  of  the  tube  about  a  quarter  of  an  inch  above  the 
paper,  will  supply  the  little  percolator  so  long  as  it  contains  any 
alcohol,  and  may  be  relied  upon  to  keep  the  surface  always  cov- 
ered with  a  stratum  of  the  menstruum,  a  matter  of  some  impor- 
tance to  the  successful  exhaustion.  This  percolation  takes  the 
place  of  the  repeated  boilings  and  strainings  of  Winckler's  pro- 
cess, and  is  much  less  troublesome,  involves  less  loss,  and  re- 
quires far  less  skill  and  dexterity,  while  it  is  quite  as  effectual 
and  requires  less  menstruum  but  far  more  time  and  patience. 
Two  entire  days  is  generally  necessary  to  obtain  the  12  fluid- 
ounces  of  percolate,  which  secures  the  practical  exhaustion  of  the 
bark.  If  this  quantity  should  be  obtained  in  less  than  24  hours 
the  exhaustion  is  scarcely  to  be  relied  upon,  and  the  results  will 
proportionately  undervalue  the  bark.  If  the  percolation  be  con- 
tinued farther  than  the  prescribed  quantity  the  percolate  in  the 
case  of  Red  Cinchona  will  be  as  dark  as  new  port  wine,  and  from 
Yellow  Cinchona  as  dark  as  dark  brandy,  and  both  will  be  very 
bitter,  yet  if  subjected  to  a  careful  accurate  process,  they  yield 
a  proportion  of  alkaloids  which  increases  the  results  but  one  or 
two  tenths  of  a  per  cent.,  an  accuracy  not  aimed  at,  and  hardly 
useful  in  such  a  process  as  this.  When  the  12  fluidounces  shall 
have  been  received  within  not  less  than  24  hours'  time,  let  the 
funnel  be  removed  and  the  exhausted  bark  be  thrown  away. 
Then  add  to  the  12  fluidounces  of  percolate  in  the  flask  2  fluid- 
ounces  of  water,  and  shake  the  contents  together.  The  powdered 
Cinchona  is  more  easily  percolated  and  better  exhausted  by 
alcohol  (s.  g.  -835),  but  the  reactions  of  the  next  step  of  the  pro- 
cess occur  more  quickly  and  more  certainly  and  more  accurately 
when  the  alcoholic  percolate  is  a  little  diluted :  hence  this  addi- 
tion of  water  before  the  animal  charcoal  and  lime.  It  it  be  Red 
Cinchona  that  is  under  examination,  add  to  the  percolate  in  the 
flask  250  grains  each  of  powdered  bone  black  (crude)  and  slaked 
