214  Contributions  from  H.  M.  Got  din.  {^m'^;^Tax' 
time,  and  the  ether  completely  distilled  off.    The  residue  of  the 
ether  soluble  alkaloids  was  now  taken  up  with  a  little  chloroform 
N 
and  40  c.c  sulphuric  acid,  the  chloroform  removed  by  a  current 
40 
of  air  from  foot  bellows  and  the  alkaloids  estimated  alkalimetrically, 
N 
using  —  alkali  for  residual  titration,  and  a  2  per  cent,  solution  of 
40 
iodine  in  potassium  iodide  as  precipitant.  The  completeness  of  ex- 
haustion was  proved  by  testing  the  dregs  in  the  percolator,  as 
described  above. 
Using  this  method  as  a  standard,  several  other  more  expedient 
methods  were  tried.  None  gave  as  good  results  when  compared 
with  the  standard  as  method  B.  Two  assays  were  then  made  by 
method  B,  using  10  grammes1  of  the  same  bark  reduced  to  a  very 
fine  powder  for  each  assay,  digesting  with  100  c.c.  modified  Prol- 
lius'  fluid,  drawing  off  25  c.c.  (=  2-5  grammes  of  drug)  and  shaking 
out  with  acid  water.  The  acid  solution  was  then  shaken  out  with 
light  ether-chloroform  and  the  assay  finished  exactly  as  in  the 
standard  method.    The  results  were  as  follows: 
Total  Alkaloids  To  AcId  Coasumed  P™™*^  , 
Method  Used.         from  2-5  Grammes.  by  2-5  Grammes.  Total.       Kther  Soluble. 
Standard  .  .  .    0*1702  gramme  23*2  c.c.  6*8i  3*57 
B  0*1682  gramme  23-4  c.c.  6*73  3*60 
B  (duplicate)  .    0*1693  gramme  23*3  c.c.  6*76  3*58 
As  method  B  gives  practically  the  same  results  as  the  standard 
method,  this  method  B  should  be  adopted  for  the  assay  of  cinchona 
bark. 
IPECAC. 
This  is  another  drug  which  is  extremely  difficult  of  exhaustion. 
The  following  method  was  found  to  give  the  best  results: 
Ten  grammes  of  drug  in  No.  60  powder  were  shaken  two  days  in  a 
shaker  with  100  c.c.  of  a  menstruum  containing  50  per  cent,  alcohol 
and  2  per  cent,  acetic  acid,  the  whole  was  then  thrown  into  a  perco- 
lator, returning  the  first  parts  to  the  percolator  till  the  percolate 
came  out  clear,  and  the  percolation  continued  with  50  per  cent, 
alcohol  containing  about  one-quarter  of  1  per  cent,  of  acetic  acid,  till 
exactly  600  c.c.  were  obtained.    150  c.c.  of  the  percolate  (=2*5 
1  If  the  drug  is  of  a  poor  quality,  20  grammes  should  be  taken  for  the  assay 
and  both  the  menstruum  and  the  aliquot  part  doubled. 
t 
