ALKALOIDS  IN  THE  CINCHONA  BARKS. 
427 
should  the  liquid  exhibit  only  a  slight  cloudiness, — a  more  con- 
centrated solution  of  the  foreign  alkaloids  with  which  the  qui- 
nine is  contaminated  is  made  by  digesting  a  larger  quantity  of 
the  sulphate  of  quinine  under  examination  in  less  water,  ex.  gr. 
5  grm.  in  30  c.  c.  of  water.  For  commercial  purposes  it  will, 
however,  scarcely  be  required  to  submit  a  sulphate  of  quinine 
which  had  been  dissolved  in  the  former  amount  of  water  and 
showed  no  opalescence,  or  only  a  slight  cloudiness,  with  the 
above  standard  solution  of  ammonia,  to  further  tests  ;  since  a 
slight  cloudiness  which  disappears  on  the  addition  of  a  few  more 
tenths  of  a  c.  c.  of  the  ammonia  solution,  would  scarcely  justify 
one  in  forming  an  unfavorable  opinion  of  a  sample  of  commercial 
sulphate  of  quinine. 
5.  The  following  numbers  were  obtained  in  the  Qualitative 
Analysis  by  means  of  a  Standard  Ammonia  Solution : 
Mixture.  Results. 
5-0  grm.  of  sulphate  of  quinine,  and  \ 
0*25        "       "  0  quinidine.  y  An  immediate  heavy  precipitate. 
(=5  per  cent,  impurities.)  J 
5-0  grm.  of  sulphate  of  qnintae  and  J    gtrong  Mness  .  after  .  few  min. 
(1  per  cent,  impn^ies  )  J  Ut6S  »  heaVy  fl°CCUleDt  ^iUte' 
5-0  grm.  of  sulphate  of  quinine,  and  }  Strong  opalescence  ;  after  half  an 
0-025       "       "  0  quinidine.  V  hour's  standing  a  precipitate  of  (3  qui- 
(J  per  cent,  impurities.)  J  nidine. 
5-0  grm.  of  sulphate  of  quinine,  ana  "]  A  slight  cloudiness,  which  increased 
0-01         "       "  /?  quinidine.  j  in  the  course  of  two  to  three  hours,  and 
(l-5th  per  cent,  impurities.)       f  exhibited  a  slight  but  distinct  precipi- 
J  tate  after  four  hour's  standing. 
5-0  grm.  of  sulphate  of  quinine,  and  ~)  No  reaction  ;  a  more  concentrated 
0-005       "       "  /?  quinidine.  V  solution  (vide  sub.  B.  4)  showed  how- 
(l-10th  per  cent,  impurities.)  J  ever  a  slight  opalescence. 
Five  experiments  made  with  admixtures  of  corresponding 
amounts  of  pure  sulphate  of  cinchonidine  to  a  pure  sulphate  of 
quinine  gave  the  same  results : 
Mixture.  Results. 
5-0  grm.  of  sulphate  of  quinine,  and  1      ^  ,.  ,. 
0-005        «      «       p  cinchonidine.  '      Even  a  m0re  dlstmct  reactl0n  tban 
(1-lOth  per  cent,  impurities.)      *  }  in  tbe  Case  °f  ^  W™*™' 
Five  experiments  of  admixtures  of  5,  1,  J,  J  and  }0  per  cent 
of  sulphate  of  cinchonine  to  pure  sulphate  of  quinine,  gave 
almost  equally  close  results;1  the  separation  of  the  alkaloid 
