Aj^uTy,Pi9oirm-}         Assay  of  Belladonna  Root.  25 
reseparated  next  time,  so  that  the  loss  will  not  be  appreciated  if 
the  operation  is  carried  out  with  care. 
If  in  the  third  separation  there  is  so  much  dirt  present  that  there 
is  danger  of  a  very  incomplete  separation,  then  it  is  well  to  make  a 
fourth  extraction,  using  10  c.c.  acid  again,  but  three  extractions  are 
usually  amply  sufficient. 
This  procedure  leaves  the  acid  solutions  clear  of  insoluble  matter,, 
and  thereby  the  alkaline  extraction  next  carried  out  will  be  uncom- 
plicated by  its  presence. 
The  three  mixed  acid  solutions  are  now  put  into  a  clean  separator, 
20  c.c.  10  per  cent,  ammonia  and  20  c.c.  chloroform  added,  the 
whole  violently  shaken  for  several  minutes  and  then  allowed  to 
stand. 
The  chloroform  layer  should  fall  down  in  five  or  ten  minutes', 
leaving  a  clean-cut  line  between  the  two  strata.  The  chloroform 
solution  is  then  drawn  off  and  set  aside  and  the  extraction  repeated 
with  15  c.c.  and  again  with  10  ex.  chloroform.  Twirling  and  rock- 
ing the  separator  will  greatly  assist  the  rapid  separation  of  the  two 
liquids  and  sometimes  the  separation  takes  place  almost  instantly. 
Sometimes  an  emulsion  is  formed  and  great  difficulty  is  experi- 
enced in  causing  a  separation,  in  which  case  an  easy  remedy  is  at 
hand  in  the  very  valuable  suggestion  of  Moerk  (Am.  Jour.  Phar., 
March,  1899),  to  put  a  few  small  flakes  of  stearic  acid  in  the  sepa- 
rator and  shake  up  violently  again.  It  is  remarkable  to  witness  the 
immediate  separation  of  the  two  fluids,  and  as  Moerk  has  proved 
that  the  stearic  acid  does  not  influence  the  result,  this  method  has 
been  used  many  times  with  great  satisfaction,  more  especially,  how- 
ever, in  extract  assays,  as  it  is  seldom  needed  in  direct  root  assays 
made  as  above. 
In  these  alkaline  extractions  any  sediment  that  collects  at  the 
line  of  separation  should  not  be  drawn  off,  but  must  be  left  in  the 
upper  aqueous  stratum,  and,  after  the  third  extraction,  washed  by 
adding  a  small  amount  of  chloroform  and  running  it  out  without 
shaking,  but  leaving  the  dirt  behind,  the  chloroform  being  added  to 
the  rest.  Care  must  be  taken  to  draw  off  only  the  clear  solution. 
This  also  rinses  out  the  stem  and  should  not  be  omitted. 
The  chloroform  solutions  are  now  all  filtered  through  absorbent 
cotton  into  an  Ehrlenmeyer  flask  of  about  300  c.c.  capacity  and 
evaporated  on  a  water-bath  to  a  brown  varnish-like  residue,  finally 
