158        .  Chemical  Examination  of  Cincho-^inine.{^'^-2^^l^I^l^'^' 
O.  Hesse^  who  has  proposed  that  quinidia  be  called  cinchonia^  states, 
in  "  Jahresbericht  der  Pharmacie,"  1873,  p.  94,  that  quinidia  of 
Leers  is  really  cinchonidia.  Dr.  Wood,  in  the  "  United  States  Dispensa- 
tory," remarks  that  quinidia  must  always  vary  in  its  solubility,  according 
to  the  amount  of  cinchonidia  it  contains.  We  have  therefore  paid  na 
regard  to  the  authority  giving  its  solubility  in  2580  parts  of  water,  and 
have  adopted  as  the  standard  for  our  experiments  the  authority  of  Van 
Heiningen  and  De  /^r/}*,  giving  the  solubility  of  quinidia  in,  1500  parts 
of  water,  at  ordinary  temperature.  For  quinia  we  have  adopted  the 
authority  of  the  "  United  States  Dispensatory  "  and  "  Pereira's  Materia 
Medica,"  according  to  which  quinia  is  soluble  in  400  parts  of  water,  at 
ordinary  temperature. 
E  2. — The  ethereal  residue  from  sample  No.  i  was  digested,  in 
the  beaker  in  which  it  had  been  evaporated,  with  70  grams  of  water^ 
on  the  water-bath,  for  twelve  hours,  the  weight  being  kept  up  to  70 
grams,  as  near  as  possible,  by  the  occasional  addition  of  water.  The 
beaker  was  then  removed  from  the  water-bath,  the  original  weight  care- 
fully adjusted,  and  was  allowed  to  cool  and  to  stand  over  night.  The 
cold  saturated  solution  was  filtered,  evaporated  to  complete  dryness, 
and  the  residue  weighed.     It  weighed  o*o6oo  grams. 
1500  grams  of  water  dissolving  I'O  gram  of  quinidia,  70  grams  of 
water  will  dissolve  0*0466  grams  of  quinidia,  which,  deducted  from 
o*o6oo  grams,  leaves  0*0134  grams,  the  amount  of  quinia  contained  in 
the  ethereal  residue,  or  0*670  per  cent,  of  the  cincho-quinine.  Sample 
No.  I. 
E  3. — The  ethereal  residue  from  Sample  No.  4  was  treated  with  40 
grams  of  water,  precisely  as  that  of  Sample  No.  i  had  been  treated 
with  70  grams,  with  the  following  result : 
The  residue  weighed  0*0370  grams  ;  40  grams  of  water  had  dis- 
solved 0*0266  grams  of  quinidia,  which,  deducted  from  the  gross  res- 
idue, leave  0*0104  grams  of  quinia,  or  0*52  per  cent,  of  the  cincho- 
quinine.  Sample  No.  4. 
E  4. — It  remained  now  only  to  prove  the  presence  of  quinidia  in  the 
aqueous  extractions  of  the  ethereal  residues.  We  accordingly  dis- 
solved these  residues  in  small  quantities  of  acidulated  water,  and  applied 
to  them  the  following  tests  : 
I.  Chlorine  water,  followed  by  ammonia,  produced  a  decided  green 
precipitate,  which,  according  to  Herapath  (vide  "  Gmelin's  Handbuch 
