Am'ju°iu^Sarm-}        Assay  of  Belladonna  Leaves.  321 
loidal  residue,  which  occasionally  interfered  with  the  titration  ;  the 
advantage  of  the  process,  the  accuracy  of  the  assay,  were  considered 
sufficient  to  make  the  first  objection,  practically  the  only  one  which 
at  that  time  could  not  be  corrected,  appear  insignificant. 
Since  the  publication  of  the  above  paper,  experiments  have  been 
in  progress  which  tend  to  improve  this  assay  process  in  several 
directions.  In  the  first  place,  it  was  found  that  a  menstruum  made 
up  of  90  parts  by  weight  of  95  per  cent,  alcohol,  and  10  parts  by 
weight  of  10  per  cent,  water  of  ammonia  constituted  a  superior 
solvent ;  200  c.c,  by  immediate  percolation,  extracting  20  grammes 
drug  better  than  300  c.c.  of  the  menstruum  previously  used  with 
frequent  periods  of  maceration.  The  extract  obtained  from  this 
percolate  can  be  perfectly  removed  from  the  capsule  and  transferred 
to  the  separator  by  using  0-5  c.c.  water  of.  ammonia  and  10  c.c. 
water  in  portions  of  1  and  2*  c.c.  The  presence  of  chlorophyl 
in  the  alkaloidal  residue  can  be  prevented  by  filtering  the  acid  ex- 
tractions, as  was  proved  by  the  fact  that  in  the  twenty-two  assays 
made  in  connection  with  this  paper  not  a  single  instance  was  noted 
in  which  there  was  any  difficulty  in  the  final  titration.  The  pul- 
verulent precipitate  mentioned  in  the  previous  article  was  not  met 
with  in  these  assays.  What  at  first  appeared  to  be  an  objection  to 
the  use  of  this  solvent  was  the  tendency  to  form  persistent  emul- 
sions in  the  alkaline  extractions  which  did  not  break  upon  the  ad- 
dition of  stearic  acid  and  agitation ;  this  was  remedied  by  stirring 
the  emulsified  layer  with  a  piece  of  iron  wire,  upon  the  end  of 
which  a  little  stearic  acid  had  been  fused  and  allowed  to  cool ;  by- 
drawing  off  the  clear  portion  and  repeating  the  operation  several 
times,  if  necessary,  almost  the  entire  quantity  of  solvent  can  be 
separated ;  it  may  happen  that  the  last  portions  of  the  emulsioni 
will  be  so  thick  that  further  separation  will  not  take  place ;  in  this 
case,  by  gentle  agitation,  mix  the  emulsion  with  the  aqueous  solu- 
tion and,  after  allowing  to  separate,  it  will  be  found  that  the  stearic 
acid  will  again  perform  its  function.  These  various  improvements 
give  an  assay  process  as  follows: 
Moisture. — Determined  in  2  grammes  at  ioo°  C. 
Assay  proper.— A  small,  slightly  conical  percolator,  about  8  inches 
long  and  1  to  1 1/2  inches  diameter,  is  connected  with  a  small  piece 
of  rubber  tubing  having  a  small  piece  of  glass  tubing  attached;  into 
this  percolator  introduce  a  plug  of  absorbent  cotton  of  such  size  as 
