112 
Assay  of  Belladonna  Leaves. 
( Am.  .Tour.  Pharm. 
t      March,  1899. 
It  is  this  particular  drawback — the  emulsification  of  the  alkaline 
solution  when  agitated  with  the  alkaloidal  solvent — that  has  done 
more  than  any  other  single  factor  to  prevent  alkaloidal  assaying 
from  being  more  generally  applied ;  it  has  also  given  rise  in  certain 
assay  processes  to  the  direction  "  to  mix  the  alkaline  solution 
and  alkaloidal  solvent  by  a  rotary  motion,  or  by  gentle  agitation," 
as  distinguished  from  shaking  "  to  prevent  emulsification."  Such 
directions  may  be  suitable  for  extracting  alkaloids  which  are  practi- 
cally insoluble  in  the  alkaline  solution,  and  where  one  can  see  the 
alkaloid  dissolving  in  the  solvent,  but  I  cannot  believe  that  total  ex- 
traction results  in  case  the  alkaloid  remains  soluble  in  the  alkaline 
solution,  as  is  the  case  with  the  belladonna  alkaloids.  This  same 
view  has  been  expressed  by  Dr.  E.  R.  Squibb,  in  a  recent  article  on 
the  assay  of  ipecac,  Am.  Jour.  Pharm.,  1899,  p.  11. 
After  numerous  failures  it  was  found  that  the  addition  of  a  small 
quantity  of  stearic  acid  was  effectual  in  separating  the  emulsified 
alkaloidal  solvent,  and  that  it  could  be  used  after  emulsification  had 
taken  place,  or  by  adding  it  before  agitating  the  alkaline  solution  with 
the  solvent,  it  would  prevent  serious  emulsification.  (Other  fat  acids 
while  not  tried,  will  very  likely  produce  the  same  result.)  A  small 
quantity,  weighing  10  to  15  milligrammes,  or  even  less  in  many 
cases,  is  sufficient,  and  is  best  added  in  several  small  fragments ;  if 
these  be  shaken  vigorously  with  an  emulsified  mixture,  and  then 
allowed  to  stand  for  a  few  minutes,  separation  will  begin,  or  can  be 
made  to  begin  by  a  twirling  motion  imparted  to  the  stem  of  the 
separator ;  it  may  not  be  possible  to  obtain  the  entire  quantity  of 
the  solvent  at  once,  but  by  running  off  the  clear  portion  to  the 
smaller  separator,  a  portion  again  of  the  remaining  emulsion  will 
respond  to  this  same  coaxing  twirling  motion,  and  can  be  transferred 
to  the  previously  removed  portion,  and  the  operation  repeated  until 
only  about  1  c.c.  emulsion  remains.  In  this  way  it  was  found  possible 
to  complete,  in  about  two  hours,  the  several  extractions  in  the  assay 
of  a  plaster,  the  first  extraction  of  which  had  remained  emulsified 
for  two  days.  It  may  happen  that  a  little  more  stearic  acid  is 
needed  after  the  first  extraction. 
This  same  separation  may  be  effected  by  fusing  a  little  stearic 
acid  on  the  end  of  a  piece  of  iron  wire  and  stirring  the  emulsified 
portion  with  this,  running  off  the  clear  solution  and  repeating  the 
operation  ;  this  method,  however,  involves  the  taking  up  of  more 
stearic  acid  by  the  solvent. 
