Am.  Jour.  Pharm. ) 
January,  1901.  J 
Assay  of  Belladonna  Root. 
27 
With  a  little  practice  on  alkaline  solutions  this  point  can  usually 
be  read  to  a  drop,  but  it  is  well  to  note  the  neutral  point  and  then 
N 
run  over  it  and  titrate  back  with  —  alkali  to  the  first  indication  of 
20 
any  tint,  thus  confirming  the  former  reading.   The  number  of  cubic 
N 
centimetres  acid  used  multiplied  by  '0145,  the  — .  factor  for  atropine, 
20 
gives  the  weight  of  alkaloid  present  in  the  20  grammes  root. 
It  seems  to  have  been  the  practice  among  some  chemists  to  dis- 
solve the  alkaloidal  residue  in  a  measured  excess  of  the  standard 
acid  and  titrate  back  with  alkali,  but  solution  in  alcohol  is  very 
much  easier  and  quicker  and  also  gives  more  accurate  results,  for 
the  writer  has  found  that  the  acid  dissolves  the  thick  gummy  resi- 
due very  slowly  and  leaves  a  quantity  of  flocculent  insoluble  matter 
floating  in  the  solution,  rendering  a  close  color-observation  practi- 
cally impossible.  By  dissolving  in  alcohol  this  does  not  take  place 
until  an  excess  of  the  acid  has  been  added  and  by  that  time  the 
operation  is  finished. 
The  accuracy  of  this  method  compared  to  the  direct  acid  solution 
was  tested  by  taking  a  chloroform  solution  from  an  assay  and  divid- 
ing it  in  half,  each  half  being  evaporated  down  in  a  separate  flask, 
N 
one  dissolved  in       HC1  and  the  other  in  alcohol.  The  results  were 
20 
exactly  alike,  except  that  the  correct  neutral  point  was  much  more 
easily  seen  in  the  alcohol  solution.  The  presence  of  the  small 
amount  of  alcohol,  therefore,  has  no  influence  on  the  result  and  its 
use  is  very  beneficial  both  in  regard  to  time  and  accuracy. 
For  some  reason  which  has  not  been  ascertained,  the  alkaloidal 
solution  colored  with  hematoxylin  will  sometimes  turn  a  greenish 
or  purplish  color  as  the  acid  is  added  to  it,  but  this  apparently  does 
not  influence  the  result,  as  the  point  of  disappearance  of  the  color  is 
as  clearly  defined  as  though  the  color  were  a  clean  red,  the  final 
yellow  being  the  same  as  usual. 
ASSAY  OF  THE  SOLID  EXTRACT. 
The  best  method  of  procedure  in  assaying  the  solid  extract  has 
proved  to  be  as  follows : 
Weigh  out  in  a  tared  beaker  4  or  5  grammes  extract  and  with  a 
glass  rod  rub  it  up  smooth  with  10  c.c.  or  15  c.c.-J^  per  cent.  H2S04, 
