Am.  Jour.  Pharm.  \ 
March,  1887.  J 
Kernels  Quinine  Test. 
143 
in  constant  proportion  to  that  of  the  anhydrous  sulphates,  even  when 
the  bases  of  those  salts  were  not  isomeric,  the  molecular  weight  of  cin- 
chonidine  sulphate  being  718  and  that  of  quinicline  sulphate  746. 
Another  error  would  result  from  the  identification,  from  the  point  of  view 
of  foreign  material,  of  cinchoniue  sulphate  with  two  molecules  of  water 
of  crystallization  (molecular  weight  754),  with  cinchonidine  sulphate 
containing  six  molecules  of  water  (molecular  weight  794). 
Some  time  ago  Dr.  Hesse  pointed  out  a  method  of  testing,  which 
differed  in  principle  from  that  of  Kerner  as  applied  in  the  cold  only, 
in  using  another  solvent  for  the  alkaloids,  ether  being  substituted  for 
ammonia  for  this  purpose.  This  mode  of  testing  has  been  slightly 
modified  by  Schaefer  and  recommended  by  him  in  the  following  form : — 
A  gram  of  the  quinine  sulphate  to  be  tested  is  heated  with  20  cc.  of 
distilled  water  to  the  boiling  point,  and,  after  being  allowed  to  cool, 
5  cc.  of  the  clear  filtered  liquid  is  placed  in  a  well-corked  tube  with 
1  cc.  of  ether  and  five  drops  of  ammonia  and  then  well  shaken.  If 
after  the  lapse  of  twenty- four  hours  there  is  no  separation  of  crystals 
from  the  ether  solution  of  the  alkaloid,  the  quinine  sulphate  is  con- 
sidered to  be  acceptable  for  use  as  pure.  But  even  with  this  modifica- 
tion, the  test  in  question,  although  possessing  some  delicacy  for  detec- 
ting cinchonidine,  has  not  this  advantage  in  regard  to  quinidine,  which 
is  somewhat  freely  soluble  in  ether.  It  must  not,  therefore,  be  for- 
gotten that  although  cinchonidine  is  at  the  present  time  the  most  ordi- 
nary impurity  of  quinine  sulphate,  the  salt  prepared  from  cuprea  bark 
does  not  contain  any  cinchonidine,  but  a  very  considerable  proportion 
of  quinidine. 
The  testing  of  quinine  sulphate  by  means  of  the  polarimeter  having 
many  partisans,  I  venture  to  state  here  the  reasons  for  which  I  con- 
sider that  this  method  of  testing  is  a  bad  one.  I  shall  show  that  it  is 
very  much  wanting  in  delicacy,  and  besides  this,  that  it  may  give  rise 
to  very  considerable  errors. 
There  is  no  doubt  that  quinine  sulphate  possesses  a  specific  rotatorv 
power  peculiar  to  it,  Avhich  is  susceptible  of  being  applied  for  ascer- 
taining the  purity  of  the  salt.  This  rotatory  power  being  the  highest 
among  those  of  the  Isevogyrate  sulphates  of  the  cinchona  alkaloids, 
being,  in  fact,  a  maximum  quantity,  its  application  for  the  purpose 
presents  an  especial  advantage.  If,  therefore,  the  quinine  sulphate 
employed  in  pharmacy  were  to  be  perfectly  pure,  that  method  of  testing, 
with  more  or  less  delicacy,  would  be  applicable  for  the  purpose  in  view. 
