420  ALKALOIDS  IN  THE  CINCHONA  BABKS. 
ences  in  form  and  solubility,  and  in  the  proportions  in  which 
they  dissolve. 
4.  0  Quinidine. — Crystallizes  from  spirit  of  wine  in  fine 
needles,  which  effloresce  very  rapidly,  and  is  far  more  soluble 
in  ether  than  the  previous  alkaloid.  Its  sulphate  forms  small 
brittle  needles,  and  is  more  soluble  in  water  than  the  sulphate 
of  a  quinidine  (1  part  in  110  to  1  in  98.)  It  possesses  the 
characteristic  property  of  producing  an  amorphous  precipitate 
with  a  concentrated  solution  of  iodide  of  potassium  (1  part  in 
4)  in  an  aqueous  solution  saturated  in  the  cold,  whilst  the  same 
reagent  produces  oily  or  resinous  deposits  in  aqueous  solutions, 
saturated  in  the  cold  of  all  other  cinchona  bases,  except  that 
of  sulphate  of  quinine.  The  other  salts  of  p  quinidine  are  more 
allied  to  the  salts  of  quinine  than  those  of  «  quinidine. 
5.  y  Quinidine  is  even  more  soluble  in  ether  than  the£  quini- 
dine ;  the  solubility  of  its  sulphate  is  on  a  par  with  that  of  the 
sulphate  of  «  quinidine.  From  its  appearance  and  specific 
gravity  it  cannot  be  distinguished  from  the  pure  sulphate  of 
quinine,  and  iodide  of  potassium  acts  upon  an  aqueous  solution 
saturated  in  the  cold,  in  the  same  manner  as  it  acts  upon  all 
other  sulphates  of  the  cinchona  alkaloids,  with  the  exception  of 
sulphate  of  P  quinidine. 
The  alkaloids  of  3,  4,  and  5  of  Group  I.  are  only  sparingly 
soluble  in  alcohol  of  20°  B. 
II.  Group. — Solutions  of  salts  of  this  group  of  bases  exhibit 
no  change  of  color  on  the  addition  of  chlorine  water  and  ammo- 
nia. The  pure  alkaloids  form  no  hydrates,  but  beautiful  an- 
hydrous crystals,  insoluble  in  ether,  (or  at  all  events  far  less 
soluble  than  the  *  quinidine,)  and  equally  insoluble  in  alcohol  of 
20°  B. 
1.  Cinchonine  is  easily  distinguished  from  all  the  other  cin- 
chona bases  by  the  crystalline  form  and  properties  of  almost  all 
its  salts.  Its  bisulphate  is  the  only  cinchona  substance  which 
possesses  distinct  dichroism. 
2.  Cinchonidine  (the  ordinary)  crystallizes  from  alcohol  in 
hard  prisms  of  a  strikingly  vitreous  lustre.  Its  salts  are  gene- 
rally less  crystallizable  than  those  of  the  bases  of  the  first  group 
and  of  cinchonine  ;  with  hydrochloric  acid,  however,  it  forms  a 
very  characteristic  compound,  crystallizing  invariably  in  almost 
