Am.  Jour.  Pharm.'i 
September,  1894.  J 
The  Opium  Assay  Method. 
433 
THE  OPIUM  ASSAY  METHOD  OF  THE  NEW  PHARMA- 
COPOEIA. 
By  Frank  X.  Moerk,  Ph.G. 
Owing,  no  doubt,  to  the  legal  requirements  that  no  opium  shall 
enter  this  country  having  less  than  9  per  cent,  of  morphine,  this 
drug  stands  at  the  head  of  the  list,  if  we  consider  the  number  of 
methods  of  assay  that  have  been  published  ;  a  large  number  of  the 
methods  are  simply  modifications  of  two  or  three  fundamental  ones 
which,  themselves,  can  be  placed  into  one  of  two  classes  depending 
upon  the  extraction  of  the  opium ;  if  this  is  carried  to  completion, 
and  the  finished  assay  represents  the  whole  quantity  of  opium 
started  with,  we  get  the  process  of  Dr.  Squibb  and  its  numerous 
modifications  ;  if,  on  the  other  hand,  the  opium  is  macerated  with  a 
definite  weight  of  water  and  the  assay  is  finished  by  the  use  of  an 
aliquot  part  of  this  aqueous  solution,  we  get  the  methods  proposed 
by  Professor  Fltickiger,  by  E.  Dieterich  (adopted  by  several  Euro- 
pean pharmacopoeias),  that  adopted  by  the  United  States  Pharma- 
copoeia of  1880  (the  so-called  lime  process),  etc.,  etc. 
Some  of  the  objections  which  Dr.  Squibb  sets  forth  against  the 
trustworthiness  of  this  second  class  of  assays  are  convincing.  His 
determinations  of  the  quantity  of  extractive  matter  in  opium  show 
that  this  is  subject  to  considerable  variation ;  in  one  of  his  publica- 
tions he  quotes  the  figures  obtained  in  the  examination  of  the  last 
eleven  lots  of  opium  in  which  the  dry,  insoluble  residue  amounted 
to  from  25  to  42  per  cent,  (average  32  per  cent.);  this,  of  course, 
means  that  the  substances  extracted  (extractive  matter  and  mois- 
ture) varied  from  58  to  75  per  cent,  (average  68  per  cent.);  the 
methods,  therefore,  like  those  of  Fltickiger  and  Dieterich,  in  which 
is  assumed  that  all  opiums  yield  60  per  cent,  to  water,  cannot  be 
considered  reliable,  because  based  upon  something  which  is  proven 
to  be  variable.  While  this  objection  is  undoubtedly  correct  and  it 
is  believed  that  comparable  figures  would  indicate  the  same  relative 
variation,  it  must  be  remembered  that  in  Squibb's  process  one  part 
opium  is  extracted  with  about  thirty-two  parts  of  water,  while  in 
Dieterich's  process  only  eight  parts  water  are  used  for  one  part 
opium  ;  it  is  evident,  therefore,  that  the  former  must  extract  consid- 
erable more  of  the  difficultly  soluble  opium  constituents  than  the 
latter,  and  hence,  a  partial  extraction  cannot  be  compared  with  an 
