ALKALOIDS  IN  THE  CINCHONA  BARKS. 
421 
regular  well-formed  dense  rhomboidal  octahedra,  (like  nitrate  of 
quinine,)  whilst  all  other  hydrochlorates  of  the  cinchona  bases 
crystallize  in  long  prismatic  needles,  often  combined  in  fibrous 
masses,  having  the  appearance  of  asbestos.  By  saturating  cin- 
chonidine  with  sulphuric  acid,  and  comparatively  little  water, 
the  solution  solidifies  on  cooling,  and  after  some  standing  leaves 
a  curdy  gelatinous  magma.  Commercial  sulphate  of  cinchoni- 
dine  is  thus  frequently  found  in  coherent  masses,  resembling 
commercial  carbonate  of  magnesia.  The^solubility  of  this  com- 
pound in  water  of  15°  C.  lies  between  J_  and  JL 
r  100  95 
3.  It  appears  that  there  are  modifications  of  cinchonidine, 
similar  to  those  of  the  bases  of  Group  I.,  which  might  be  char- 
acterized as  separate  isomerides  of  cinchonine.  A  short  time 
ago  I  obtained  an  alkaloid,  crystallizing  in  brilliant  little  scales 
or  small  shining  needles,  from  an  amorphous  sulphate  of  cin- 
chonidine, which  came  from  France  and  was  sold  under  the 
name  of  Sulphate  de  Quinidine.  It  dissolved  in  108  parts  of 
water  of  15°  C,  and  gave  with  hydrochloric  acid  long  hard 
rhombic  prisms  and  no  rhomboidal  octahedra. 
In  my  endeavor  to  find  out  a  qualitative  quinine  test,  I  thought 
first  of  employing  the  peculiar  iodide  of  potassium  reaction,  des- 
cribed under  (S  quinidine,  with  cold  saturated  solutions  of  the 
sulphates  of  the  alkaloids,  and  succeeded  in  distinctly  tracing, 
by  means  of  this  reagent,  an  adulteration  amounting  to  as  little 
as  0-3  per  cent,  of  the  sulphate  of  quinine  with  quinidine  (es- 
pecially with  0  quinidine ;)  at  the  same  time  I  perceived  that  a 
qualitative  test,  based  upon  the  iodide  reaction,  could  not  be 
recommended  as  a  mode  of  commercial  analysis,  because  the 
precautions  which  have  to  be  observed  are  manifold  and  difficult, 
and  likely  to  give  rise  to  erroneous  observations.  For,  the  hy- 
driodate  and  the  sulphate  of  quinine  are  almost  equally  soluble 
in  cold  water,  and  it  is  therefore  possible  that  an  aqueous  solu- 
tion of  the  sulphate  saturated  in  the  cold,  of  a  perfectly  pure 
quinine,  is  rendered  slightly  turbid  on  the  addition  of  iodide  of 
potassium,  if  the  latter  be  a  little  too  concentrated,  or  if  one 
or  the  other  of  the  solutions  shows  a  different,  i.  e.  a  lower  tem- 
perature than  15°  C.  Moreover,  the  iodide  of  potassium  of 
commerce  is  rarely  absolutely  free  from  carbonate  of  potassa 
or  caustic  potassa,  which  renders  the  test  troublesome  for  those 
