ON  PREPARATIONS  OF  CINCHONA. 
51 
three  months  there  was  no  deposit  from  it,  but  the  experiment 
(being  only  negative  in  its  character)  was  not  considered  con- 
clusive ;  since  it  does  not  follow  that  because  after  two  months 
there  is  no  precipitate,  there  will  be  none  after  a  greater 
lapse  of  time.  Eecourse  was  had  to  another  experiment ;  gly- 
cerin was  added  to  the  fluid  extract  of  cinchona,  prepared  ac- 
cording to  the  U.  S.  Pharmacopoeia,  in  the  proportion  of  one  part 
of  glycerin  to  three  parts  of  extract ;  upon  heating  this  mix- 
ture it  speedily  became  perfectly  clear,  much  sooner  than  where 
the  extract  was  heated  alone ;  but  upon  cooling,  the  cinchonic 
red  was  thrown  down  and  the  mixture  again  became  cloudy 
and  opaque. 
Another  experiment  was  then  tried,  the  quantity  of  glyce- 
rin being  increased,  and  equal  parts  of  glycerin  and  fluid  ex- 
tract being  used.  This  mixture,  after  being  heated  as  before, 
remained  perfectly  clear  upon  cooling.  From  this  experiment 
it  was  thought  that  a  fluid  extract  might  be  prepared  with  gly- 
cerin alone,  which  would  satisfy  the  conditions  of  the  query, 
and  an  extract  was  prepared  by  the  following  formula  : 
Take  of  Yellow  Cinchona,  in  moderately  fine  powder,  eight 
troyounces. 
Glycerin  } 
Alcohol  f ea     eiSn*  nuidounces. 
Diluted  Alcohol  a  sufficient  quantity. 
Mix  the  glycerin  and  the  alcohol,  moisten  the  cinchona  with 
six  fluidounces  of  the  mixture,  allow  it  to  stand  for  half  an 
hour,  pack  it  firmly  in  a  cylindrical  glass  percolator,  and  gra- 
dually pour  upon  it,  first  the  remainder  of  the  mixture  and 
then  diluted  alcohol,  until  two  pints  of  tincture  have  been 
obtained  or  the  bark  is  exhausted ;  evaporate  this  to  a  pint  by 
means  of  a  gentle  heat. 
A  sample  of  the  extract,  as  thus  prepared,  is  herewith  sub- 
mitted. It  is  beautifully  clear,  possesses  all  the  remedial  prop- 
erties of  cinchona  in  perfect  solution,  is  not  liable  to  change 
by  fermentation,  as  is  the  fluid  extract  of  the  U.  S.  Pharmaco- 
poeia, and  is  believed  to  be  in  many  respects  superior  to  that 
preparation. 
