412  Examination  of  Quinine  Salts.  {^"''InZ'im^'''^' 
filtered,  the  precipitate  washed  with  distilled  water  and  the  thalleio- 
quin  reaction^  carried  out  with  the  precipitate.  If  the  intense  green 
color  is  produced  there  is  quinidine  present ;  if  the  green  color  is  not 
produced  quinidine  is  absent.    Proceed  E. 
D.  Detection  of  Cinchonine.  The  liquid  after  addition  of  KI  is 
filtered  and  one  drop  water  of  ammonia  added ;  set  aside  for  a  few 
minutes  ;  there  results  : 
1.  Perfectly  clear  solution,  in  absence  of  cinchonine.    Proceed  E. 
2.  Turbid  solution,  if  cinchonine  is  present.    Proceed  E. 
E.  Detection  of  Cinchonidine.  If  in  the  foregoing  examination 
cinchonine  or  quinidine  is  found,  the  precipitate  of  tartrates  (see  A)  is 
carefully  washed  with  15-20  cc.  Rochelle  salt  solution  (1-20);  were 
these  alkaloids  not  found  this  washing  is  superfluous.  The  precipi- 
tate is  dissolved  ofP  the  filter  by  use  of  3  cc.  dilute  HgSO^  (1-20) ;  to 
the  solution  2  cc.  ether  and  1  cc.  water  of  ammonia  are  added,  the 
mixture  is  well  shaken  for  one  minute  and  allowed  to  stand  at  rest 
for  five  minutes.  This  shaking  and  allowing  to  stand  is  repeated 
several  times  (the  time  allowed  not  to  exceed  a  half-hour).    Notice ; 
1.  The  ethereal  layer  and  the  sides  of  the  test  tube  remain  per- 
fectly clear  in  absence  of  cinchonidine. 
2.  The  ethereal  layer  and  the  sides  of  the  test  tube  become  cloudy, 
if  cinchonidine  is  present. 
Remarks  referring  to  Quinine  containing  Quinidine.  By  this 
method  one-fourth  or  one-half  per  cent,  quinidine  cannot  be  detected. 
Often  one  or  two  per  cent,  quinidine  will  give  no  reaction  with  KI, 
but  the  presence  can  be  ascertained  by  the  addition  of  water  of 
ammonia,  which  is  a  more  delicate  test.  In  the  examination  of 
quinine  with  ten  per  cent,  quinidine  nothing  extraordinary  is  noticed, 
but  in  presence  of  fifteen  per  cent,  and  more  of  this  alkaloid  it  is 
noticed  on  addition  of  Rochelle  salt  that  the  tartrates  are  not  precipi- 
tated ;  this  does  not,  hoAvever,  interfere  with  the  further  detection  of 
quinidine.  Should  more  than  fifteen  per  cent,  quinidine  be  suspected^ 
more  KI  must  be  used,  otherwise  it  must  be  feared  that  the  quini- 
dine is  not  thoroughly  precipitated  and  later  may  be  mistaken  for 
cinchonine.  As  a  large  percentage  of  quinidine  prevents  the  separa- 
tion of  the  tartrates  and,  as  was  found  by  special  experiments,  quinine 
sulphate  mixed  with  quinidine  sulphate  is  more  difficultly  soluble 
^  Excess  of  chlorine  water  prevents  the  thalleioquin  reaction,  while  excess  of 
ammonia  favors  it. 
