428 
ALKALOIDS  IN  THE  CINCHONA  BARKS. 
took  place,  however,  for  the  most  part,  in  flakes,  without  any 
previous  opalescence. 
6.  Quantitative  Method. — There  can  be  no  doubt  that  the 
ammonia  test  may  also  be  employed  with  advantage  for  the 
quantitative  estimation  of  foreign  cinchona  salts  contained  in 
sulphate  of  quinine,  for  the  separation  of  which  hitherto  te- 
dious and  uncertain  methods  had  to  be  employed.  It  will  be 
found  the  more  useful  when  an  actual  adulteration  has  to  be 
traced,  or  when  a  so-called  Chinin-sulphuric  naturale, — sulphate 
of  quinine  which  contains  much  quinidine, — such  as  has  been 
frequently  met  with  in  commerce  lately,  has  to  be  examined. 
Such  samples  will  have  to  be  extracted  with  water  by  a  some, 
what  modified  process,  viz.,  by  treating  about  5-0  grm.  repeat- 
edly with  small  quantities  of  water,  till  a  portion  of  the  filtrate 
gives  no  longer  the  ammonia  reaction.  The  extraction  with 
water  must  not  be  interrupted  too  soon,  and  the  qualitative  test 
— for  which  the  least  possible  quantity  of  the  filtrate  only  (J  to 
1  c.  c.)  is  employed — ought  only  to  be  resorted  to  when,  ac- 
cording to  a  preliminary  rough  experiment,  it  may  be  expected 
to  give  a  negative  result.  The  whole  of  the  filtrate  is  then  in- 
troduced into  a  graduated  measure  glass,  and  diluted  to  a  round 
number  of  c.  c.  (varying  probably  from  30  to  100  c.  c.?)  and  a 
measured  quantity  of  the  liquid  (J,  J,  J,  etc.)  mixed  with  the 
standard  ammonia  solution  in  the  proportion  employed  for  the 
qualitative  analysis.  The  precipitated  alkaloid  is  allowed  to 
settle,  and  then  rapidly  thrown  on  a  good  filter,  washed  at  first 
with  a  weak  solution  of  ammonia,  and  lastly  with  water,  and  well 
dried  at  100°  C.  till  its  weight  remains  constant.  The  results 
are  sufficiently  accurate. 
7.  The  following  quantitative  numbers  were  obtained:  (a.)  a 
mixture  of  4-0  grm.  of  pure  sulphate  of  quinine,  and  1-0  grm. 
of  pure  sulphate  of  cinchonine,  were  separated  according  to  B. 
6.    Total  aqueous  extract  =100  c.  c. 
50  c.  c.  treated  with  52  c.  c.  of  ammonia  solution  of  0-92  sp. 
gr.  left  0-405  grm.  of  alkaloid  undissolved.  5  grm.  of  the  pur- 
posely adulterated  quinine  salt  contained  therefore  IggXg^5  
0-810  of  a  foreign  alkaloid  (Ci.)  or  0-810  x  1-217=  0-986  of 
sulphate  of  cinchonine. 
After  having  ascertained  that  the  foreign  admixture  con- 
sisted of  cinchonine  or  cinchonidine,  the  weight  of  the  alkaloid 
