246        IODO-SULPHATES  OF  THE  CINCHONA  ALKALOIDS. 
ON  THE  OPTICAL  AND  CHEMICAL  CHARACTERS  OF  THE  IODO- 
SULPHATES  OF  THE  CINCHONA  ALKALOIDS,  TOGETHER  WITH 
•THE  CHEMICAL  ANALYSIS  OF  SOME  OF  THE  SALTS. 
By  W.  Bird  Herapath,  M.  D.,  Lond.,  F>  R.  S.  E. 
In  the  former  paper,  the  author  examined  the  existing  tests 
for  discriminating  between  the  various  cinchona  alkaloids,  and 
pointed  out  their  insufficiency.  In  the  present  paper  he  shows 
that  the  optical  characteristics  of  the  iodo- sulphates  of  the  alka- 
loids quinine  and  quinidin  are  sufficiently  well  marked  to  render 
the  existence  of  either  one  of  these  certain,  and  that  although  the 
iodo-sulphate  of  cinchonidin  is  very  closely  related  optically  and 
chemically  to  the  homologous  salt  of  quinine,  yet  there  are  suf- 
ficient points  of  dissimilarity  to  enable  us  to  diagnose  between 
the  two  ;  and,  moreover,  that  the  production  of  this  salt  is  a 
beautiful  means  of  deciding  readily  whether  cinchonidin  is  pre- 
sent in  specimens  of  cinchonine  or  cinchonicine ;  all  evidence  of 
quinine  or  its  allies  having  been  decided  in  the  negative  by  the 
results  of  the  previous  tests,  as  proposed  by  Brandes,  Vogel, 
Pelletier,  Leers,  or  the  author. 
The  cinchonidin  of  Wittstein  has  also,  by  the  same  method, 
been  proved  by  the  author  to  be  totally  different  from  the  cin- 
chonidin of  Pasteur. 
Acetic  acid  and  chloroform  may  also  be  employed  for  dis- 
criminating between  cinchonine  and  cinchonidin. 
The  chemical  characters  of  all  these  iodo-salts  furnish  no 
means  of  discrimination,  for  as  a  class  they  all  agree  in  being 
more  or  les3  soluble  in  spirit,  giving  a  deep  sherry-brown  solu- 
tion, from  which  water  precipitates  them  in  an  amorphous  form, 
as  dark  brown,  cinnamon-brown,  or  purplish-brown  colored  pre- 
cipitates ;  they  are  only  very  slightly  soluble  in  dilute  spirit, 
and  scarcely  at  all  in  water,  ether,  turpentine,  or  chloroform  : 
acetic,  dilute  sulphuric,  or  hydrochloric  acid  have  but  little  action 
upon  them,  whilst  concentrated  hydrochloric  or  sulphuric  acid 
decomposes  them.  Nitric  acid  rapidly  acts  upon  them,  even  in 
the  cold,  with  violent  evolution  of  nitrous  acid  and  production 
of  heat,  iodine  being  oftentimes  liberated  in  the  crystalline 
form. 
Alkalies  also  decompose  them. 
