28 
Cinchona  Bark. 
(  Am.  Jour.  Pharm. 
\    January,  1902. 
50°  C,  distil  and  dry  residue  in  a  water-oven  to  constant  zveight^ 
weigh  and  calculate  to  percentage. 
Experiments  conducted  by  Van  Ketel  proved  that  cinchona  bark 
was  exhausted  of  its  alkaloids  in  half  (j^)  an  hour. 
One  hour  is  therefore  a  sufficient  time  to  finish  an  assay  of  a  cin- 
chona bark  by  this  method,  which  recommends  itself,  too,  for  its 
economy  in  the  use  (recovery)  of  ethyl-sether. 
Fineness  of  Powder  No.  60.  Fineness  of  Powder  No.  80. 
Time  of  Boiling.  Per  Cent,  of  Time  of  Boiling.  Per  Cent,  of 
Total  Alkaloid.  Total  Alkaloid. 
10  minutes 
15  " 
6-o6 
6'i 
6  22 
6*24 
20      "   {e'ts   2omirmtes  \6 
30 
6'47    „r       a  J  6*5 
16-54 
6'54 
6-48 
Results  of  an  experiment  carried  on  with  a  richer  bark  (9-3  per 
cent.). 
Time  of  Boiling.  Per  Cent,  of 
Total  Alkaloid. 
5  minutes 
8-48 
8-40 
j  876 
10  •  .  {8.76 
9'°5 
J5  •  •  •  •  lg.„ 
*>   "   -  {S3 
One  hour 
9-30 
9-32 
Experiments  have  proven  that  the  addition  of  ammonia  water  to 
the  bark-lime  mixture  makes  a  material  difference  in  the  results. 
The  bark  previously  assayed  on  6-5  per  cent,  total  alkaloid,  in 
No.  60  powder,  mixed  with  the  slacked  lime  only,  yielded  to  boil- 
ing aether,  575  and  579  per  cent. 
1 1  recommend  Gordin's  suggestion,  which  he  renewed  in  Archiv  d.  Phar- 
macie,  239,  3,  1901,  page  217,  to  submit  the  marc  to  a  new  assay,  as  best  evi- 
dence for  the  exhaustion  of  a  drug  ;  have  followed  this  method  with  the  best 
satisfaction  already  for  sometime.  Duplicate  analyses  may  have  an  error  in 
common,  and  do  have  one  sometimes. 
