Am,  Jour.  Pharm, 
Aug.,  1880. 
Determination  of  ^inia. 
395 
becomes  clear  and  slightly  yellow  colored.  This  liquor  is  poured 
ofF^  and  the  resinous  substance  is  washed  by  heating  it  on  a  water-bath 
with  distilled  water.  After  washing,  it  is  heated  on  the  water-bath  till 
all  the  water  has  been  evaporated.  It  is  then  soft  and  tenacious  at  the 
temperature  of  the  water-bath,  but  becomes  hard  and  brittle  after  cool- 
ing. One  part  of  this  substance  is  now  heated  with  6  parts  of  alcohol 
of  92  or  94  per  cent,  on  a  water-bath,  and  is  thus  dissolved,  and  the 
solution  allowed  to  cool.  In  cooling,  a  part  of  the  dissolved  substance 
is  separated.  The  clear,  dark-colored  solution  is  evaporated  on  a 
water-bath  and  the  residue  dissolved  in  5  parts  of  cold  alcohol.  This 
second  solution  leaves  a  small  part  of  insoluble  substance.  The  clear 
solution  obtained  by  the  separation  of  this  insoluble  matter,  either  by 
decantation  or  filtration,  constitutes  the  reagent  which  I  have  used 
since  the  beginning  of  1875  under  the  name  of  "  iodosulphate  of 
chinioidin,"  both  for  the  qualitative  and  quantitative  determination  of 
crystallizahle  quinia. 
application  of  the  Reagent  to  the  Quantitative  Estimation  of  ^inia.  — 
The  mixed  alkaloids  obtained  from  any  species  of  cinchona  bark  are 
treated  with  ether,  the  quantity  of  which  depends  on  the  amount  of 
quinia  contained  in  the  mixture  ;  10  to  20  parts  of  ether  will  be  found 
sufficient  for  the  treatment  of  one  part  of  mixed  alkaloids.  By  this 
treatment  the  mixed  alkaloids  are  divided  [into  two  parts,  viz.  :  In  a 
part  soluble  in  ether  and  in  a  part  insoluble  in  this  liquid.  The  part 
soluble  in  ether  contains  chiefly  quinia  and  amorphous  alkaloid  (chinioi- 
din), besides  traces  of  the  other  crystalline  alkaloids.  To  estimate  the 
quantity  of  quinia,  one  gram  of  the  part  soluble  in  ether  is  dissolved  in 
40  grams  of  acidulated  alcohol  of  92  or  94  per  cent.,  containing  0755 
per  cent.^  of  HgSO^,  to  obtain  an  alcoholic  solution  of  the  acid  sul- 
phate of  quinia.  From  this  solution  the  quinia  is  separated  by  adding 
carefully,  by  means  of  a  pipette,  the  before-mentioned  reagent  as  long 
as  a  dark  brown-red  precipitate  of  iodosulphate  of  quinia  (herapathite) 
is  formed.    As  soon  as  all  the  quinia  has  been  precipitated  and  a  slight 
^  To  prevent  the  use  of  an  excess  of  iodine  I  have  prescribed  on  purpose  not 
enough  iodine  to  precipitate  all  the  chinioidin  in  the  form  of  iodosulphate.  There- 
fore the  liquor  contains  still  chinioidin  which  can  be  obtained  in  a  very  pure  state  if 
a  little  sulphurous  acid  is  added  before  precipitating  the  alkaloid  by  caustic  soda. 
'■'This  quantity  is  quite  sufficient  to  transform  the  alkaloids  into  acid  sulphates, 
and  ought  not  to  be  increased,  for  an  excess  of  acid  would  increase  the  solubility  of 
the  herapathite  in  alcohol. 
