Am.  Jour.  Pharm.  1 
March,  1909.  j 
U.  S.  P.  Assay  Methods. 
119 
While  discussing  the  assay  methods  of  the  Pharmacopoeia,  it 
would  not  be  out  of  place  to  mention  two  methods  which  we  have 
found  very  effective  in  breaking  up  emulsions.  These  are  not 
offered  for  insertion  in  the  Pharmacopoeia,  as  the  methods  given 
there  are  satisfactory,  but  are  recommended  as  being  superior  to 
the  U.  S.  P.  methods. 
The  first  of  these,  which  has  been  used  to  break  up  the  most 
stubborn  emulsions  in  a  very  short  time,  consists  in  treating  the 
emulsified  solution,  if  acid,  with  an  alkali  (preferably  ammonia), 
or  if  the  emulsified  solution  is  alkaline,  by  treating  it  with  dilute 
sulphuric  acid.  The  reason  for  the  disintegration  of  the  emulsion 
is  that  the  acid  and  alkali  combine,  or  vice  versa,  thus  forming  a 
salt  and  liberating  the  solvent.  When  this  is  accomplished,  it  is 
brought  to  its  original  condition  and  again  shaken  out. 
The  other  method  is  merely  a  mechanical  one,  and  is  not  quite 
so  effective,  but  may  be  used  in  less  compact  emulsions.  It  is  per- 
formed by  placing  a  dozen  or  so  of  small  pieces  of  glass  rod,  about 
one-quarter  inch  in  length,  in  the  separator  containing  the  emulsion, 
then  holding-  the  separator  in  a  horizontal  position  and  rotating 
slowly.  By  this  means  the  emulsion  is  broken  by  coming  in  contact 
with  the  glass  rods.  The  clear  solution  may  then  be  drawn  off  and 
the  operation  repeated  until  the  emulsion  is  completely  broken  up. 
A  decided  improvement  could  be  made  in  the  assay  methods  of 
drugs  like  belladonna,  hyoscyamus  and  stramonium,  which  require 
maceration  and  percolation,  if  both  operations  were  conducted  in 
one  vessel.  This  would  eliminate  loss  in  transferring  and  would  save 
time.    A  suitable  apparatus  should  be  described  and  recommended. 
The  question  of  economy  in  the  assay  of  tinctures,  fluidextracts, 
etc.,  must  be  considered.  While  this  is  not  of  much  importance  to 
the  large  manufacturer,  it  is  to  the  small  manufacturer,  who  would, 
perhaps,  make  only  a  pint  of  fluidextract  and  two  or  three  pints  of 
tincture.  In  practically  all  cases  in  the  assay  of  tinctures,  the 
U.  S.  P.  instructions  are  to  use  100  c.c.  This  is  done  regardless 
of  the  alkaloidal  content.  There  is  no  necessity,  in  most  cases,  for 
using  such  a  large  quantity,  as  half  the  amount  would  be  ample. 
Besides  the  waste  of  50  c.c.  of  tincture,  there  is  a  loss  of  time  in  the 
evaporation  which  most  of  them  require.  If  a  duplicate  assay  is 
made  (which  should  be  made,  in  order  to  be  reasonably  sure  of 
results),  the  loss  would  amount  to  100  c.c.  The  reason  for  using 
such  a  large  quantity  is  not  because  a  smaller  quantity  would  not 
