154  Chemical  Examination  of  Cincho-^inine.l^^l^^'-J^^^'"^- 
alkaloids  in  cincho-quinine  (Sample  No.  2),  and  the  quinia  therein 
contained. 
EXPERIMENTS  C. 
C  I. — A  portion  of  the  residue  remaining  from  the  precipitate  A  2 
after  its  exhaustion  with  stronger  ether,  as  detailed  in  Experiment  B  i, 
was  dissolved  in  water  acidulated  with  hydrochloric  acid,  precipitated 
with  ammonia,  and  the  mixture  was  then  shaken  with  stronger  ether. 
The  ethereal  solution  yielded  on  evaporation  a  small  residue,  which, 
when  dissolved  in  dilute  hydrochloric  acid,  and  treated  with  chlorine 
water  and  ammonia,  gave  no  color-reaction  whatever. 
Result  No.  8. —  The  precipitate  A  2,  after  exhaustion  with  stronger  ether ^ 
.as  detailed  in  B  i,  no  longer  contained  either  quinia  or  quinidia. 
C  2. — 0*640  grams  of  the  same  residue  was  dissolved  in  dilute  sulphu- 
ric acid,  the  solution  was  carefully  neutralized  with  potassa,  and  a  care- 
fully neutralized  solution  of  tartrate  of  potassium  and  sodium  was 
added  (in  the  proportion  of  0*522  parts  to  I'ooo  parts  of  alkaloid  res- 
idue). The  mixture  was  then  evaporated  to  40  times  the  weight  of 
the  alkaloid  residue  employed,  and  allowed  to  stand  four  days.  No 
crystalline  (or  other)  deposit  had  formed. 
Result  No.  9. —  The  residue  remaining  after  the  exhaustion  of  the  precip- 
j.tate  A  2  ivith  ether  contains  no  cinchonid'ia.^  and  is  therefore  composed  of 
.cinchonia  only. 
Reimarks. — The  method  adopted  by  us  for  the  separation  of  cincho- 
nidia  from  cinchonia  is  that  recommended  by  De  Vrij  {vide  "  Jahres- 
bericht  der  Pharmacie,"  1873).  The  fact,  that  we  have  failed  to  obtain 
cinchonidia  in  the  residue  of  the  precipitate  A  2  after  its  exhaustion 
with  ether,  does  not  decide  its  absence  in  cincho-quinine,  as  it  may 
have  been  taken  up  by  the  ether,  and  would  then  be  contained  in  the 
ethereal  residue  B  \.  In  that  event,  however,  it  can  only  be  present 
in  very  small  proportion. 
SERIES  OF  EXPERIMENTS,  III. 
These  experiments  were  made  with  the  four  samples  of  cincho-qui- 
nine, described  in  the  beginning  of  our  paper,  and  were  both  qualitative 
and  quantitative.  The  large  quantity  of  sulphuric  acid  found  in  sample 
No.  2  made  it  evident  to  us,  that  this  acid  existed  mainly  in  alkaloidal 
combination.  If,  therefore,  any  considerable  portion  of  cinchonia  was 
held  in  such  combination,  the  sulphate  of  cinchonia,  being  soluble  in 
about  50  parts  of  cold  water,  would  readily  be  taken  up  by  digesting 
cincho-quinine  in  cold  water,  and  its  presence  as  such  proved.  We 
