ALKALOIDS  IN  THE  CINCHONA  BARKS. 
425 
Liq.  am.  B,  15*9 — 16-2  c.  c,  or  from  12  to  13  times  more 
than  1  c.  c.  of  a  solution  of  sulphate  of  quinine. 
6.  Cinchonine. — Water  of  15o  C.  dissolves  -L  of  its  own 
54 
weight  of  sulphate;  0-5  c.  c.  of  this  solution  remains  turbid 
even  after  the  addition  of  as  much  as  150  c.  c.  of  either  of  the 
ammoniacal  test-solutions.  The  alkaloid  separates  in  large 
flakes,  which  become  finely  divided  when  the  liquid  is  shaken, 
imparting  to  the  solution  a  slight  opalescence,  and  which  are 
slowly  deposited  at  the  bottom  of  the  test-tube  when  allowed  to 
stand  quietly  for  a  short  time,  since  the  alkaloid  had  never  been 
dissolved,  but  merely  suspended  as  a  finely  divided  precipitate 
in  the  liquid. 
By  adding,  however,  from  1  to  6  drops  of  solution  of  cincho- 
nine to  about  30  to  55  c.  c.  of  a  solution  of  sulphate  of  quinine, 
and  treating  5  c.  c.  of  this  mixture  with  5  c.  c.  of  test-liquor  A, 
or  7  c.  c.  of  the  ammonia  solution  B,  the  cinchonine  is  at  first 
dissolved,  because  it  is  precipitated,  together  with  quinine,  in  a 
finely  divided  state,  and  because  ammonia  then  acts  more  readily 
upon  it.  After  the  lapse  of  an  hour,  however,  flakes  of  precipi- 
tated cinchonine  again  make  their  appearance,  even  in  this  mixed 
solution. 
B. — Principle  and  Application  cf  the  Quinine  Test. 
According  to  A.,  ex.  1,  we  may  take  it  as  an  established  fact, 
that  5  c.  c.  of  an  aqueous  solution  of  pure  sulphate  of  quinine, 
saturated  in  the  cold  at  15  c,  do  not  require  more  than  5  c.  c. 
of  the  ammonia  solution  A,  and  7  c.  c.  of  the  ammonia  solution 
B,  in  order  to  become  precipitated  and  redissolved. 
This  quantity  of  ammonia  is  however  insufficient,  as  was 
proved  by  experiments  2,  3,  4,  5  and  6,  whenever  the  sulphate 
of  quinine  contained  larger  or  smaller  quantities  of  the  sulphate 
of  <*,  /?,  and  >,  quinidine,  cinchonidine  and  cinchonine.  The  last 
named  salts  are  dissolved,  first,  by  digesting  with  water  any 
quinine  salt  which  is  suspected  of  having  been  adulterated  by 
these  admixtures.  They  can  be  traced  with  great  accuracy  by 
adding  just  5  c.  c.  of  the  test  fluid  A,  or  7  c.  c.  of  fluid  B,  to  5 
c.  c.  of  an  aqueous  solution  saturated  in  the  cold,  of  a  sample 
of  the  mixed  sulphates  which  has  to  be  tested  for  these  less 
