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TESTS  FOR.  THE   CINCHONA- ALKALOIDS.  345 
In  order  to  determine  the  proportion  of  kinovic  acid,  dilute 
solution  of  ammonia  is  to  be  added  to  the  yellowish,  glutinous 
matter  which  adheres  to  the  filter,  and  which  is,  for  the  most  part, 
greasy  to  the  touch.  This  takes  up  the  kinovic  acid  but  not  the 
fat.  The  solution  is  to  be  filtered,  and  to  it  a  slight  excess  of 
muriatic  acid  added  to  precipitate  the  kinovic  acid,  which  is  then 
to  be  collected  on  a  filter.  The  well  washed  glutinous  precipitate 
is  to  be  removed  whilst  moist  from  the  filter,  and  dried  on  a  watch- 
glass  or  porcelain  capsule,  and  the  weight  of  the  thus  obtained 
kinovic  acid  marked  down.  This,  however,  is  only  the  larger 
portion  of  the  quantity  of  the  kinovic  acid  actually  obtained  from 
the  bark.  A  smaller  portion  of  it  is  still  contained,  combined 
with  lime,  in  the  lime  residue  which  has  been  digested  with  the 
alcoholic  tincture  of  bark.  This  kinovate  of  lime  is  very  diffi- 
cultly soluble  in  spirit  of  wine. 
In  order  to  obtain  this  smaller  portion,  the  lime-residue,  ex- 
hausted by  alcohol,  is  to  be  dried  and  powdered,  and  then  digested 
with  cold  distilled  water.  From  the  filtered  liquid,  which  is 
almost  as  clear  as  water,  the  white  and  nearly  pure  kinovic  acid 
is  thrown  down  by  a  very  slight  excess  of  muriatic  acid.  It  is 
then  to  be  weighed  and  the  sum  added  to  that  before  obtained. 
By  the  direct  treatment  of  powdered  bark  with  milk  of  lime,  the 
whole  quantity  of  kinovic  acid  can  be  extracted  from  the  bark. 
Also  for  the  quantitative  determination  of  the  acid  it  is  advisa- 
ble to  weigh  it  in  the  imperfectly  pure  condition,  the  loss  ac- 
companying the  purification  being  very  considerable. 
If  the  qualitative  examination  of  the  bark  has  shown  that  this 
substance  contains  none  or  only  a  small  proportion  of  alkaloid, 
but  a  large  quantity  of  kinovic  acid,  or  the  latter  only,  the  bark  is 
more  appropriately  first  treated  with  diluted  milk  of  lime,  and  the 
kinovic  acid  precipitated  by  muriatic  acid,  by  which  method  the 
testing  of  the  residue  for  a  possibly  slight  proportion  of  alkaloid 
is  considerably  facilitated.  The  dry  residue  of  lime  is  then  ex- 
hausted by  alcohol,  like  the  powdered  bark,  &c.  In  this  manner  I 
obtained  from  sixteen  ounces  of  bark,  containing  kinovic  acid,  one 
grain  of  cinchonine,  besides  a  large  quantity  of  kinovic  acid.  The 
last  more  important  constituent  of  the  bark,  the  kinic  acid,  is  now 
easily  obtained  by  exhausting  the  residue  of  the  bark,  which  has 
been  treated  by  alcohol,  with  cold  distilled  water,  evaporating 
