62 
The  Assay  of  Drugs. 
f  Am.  Jour.  Pkarm. 
1    February,  1909. 
referee,  and  since  the  law  became  operative  the  scope  of  the  in- 
vestigations has  been  considerably  extended.  The  method  of  pro- 
cedure, which  has  been  found  quite  valuable  in  increasing  the 
accuracy  and  efficiency  of  other  branches  of  chemical  analysis,  is  to 
distribute  suitable  uniform  samples  of  the  drugs,  with  detailed  in- 
structions in  the  methods  of  analysis  to  be  tried,  to  a  number  of 
competent  volunteer  analysts,  who  report  their  results,  with  observa- 
tions and  constructive  criticisms  on  the  utility  of  the  methods.  A 
compilation  of  these  returns  is  reported  to  the  Convention  of  the 
Association,  communicated  to  the  collaborators,  and  made  the  basis 
of  recommendations  for  the  adoption  of  official  methods  for  the  use 
of  the  Association,  or  provisional  methods  for  further  study. 
In  this  manner  since  1903  methods  have  been  studied  for  the 
assaying  of  opium,  cinchona,  ipecac,  mix  vomica,  aconite  leaves  and 
root,  belladonna  leaves  and  root,  coca  and  eolchicum  corm  and  seed. 
In  every  case  the  Pharmacopceial  method  has  been  compared  with 
one  or  more  other  methods  selected  from  the  best  available,  the 
choice  being  influenced  by  the  desirability  of  contrasting  the  aliquot 
and  total  extraction  methods  of  obtaining  the  active  principle,  and 
the  gravimetric  and  volumetric  methods  of  determination.  The 
Pharmacopceial  method  for  assaying  opium  has  been  adopted  as 
official  by  the  Association.  In  regard  to  the  results  obtained  by  the 
Pharmacopceial  methods  for  other  drugs,  it  may  be  said  that  they 
can  scarcely  be  called  "  fairly  uniform,"  as  they  sometimes  scatter 
widely,  differences  amounting  to  30  or  40  per  cent,  of  the  average 
occurring.  Other  branches  of  analysis  have  made  a  similar  show- 
ing when  first  made  the  subject  of  cooperative  study. 
Though  drug  assaying  does  not  involve  the  application  of  any 
analytical  principles  peculiar  to  itself,  it  is  attended  by  some  special 
difficulties,  so  that  even  the  competent  chemist  who  is  trained  in 
other  branches  of  analysis  does  not  usually  succeed  in  this  without  a 
certain  amount  of  experience,  and  the  amateur  surely  cannot  expect 
to  get  very  accurate  results. 
The  Pharmacopceial  methods  are  formulated  in  simple  terms, 
and  on  carrying  out  the  manipulations  it  will  usually  be  found  that 
more  or  less  of  the  details  are  left  to  the  judgment  of  the  analyst, 
and  there  is  small  probability  that  any  two  attempting  to  follow 
the  instructions  exactly  will  perform  the  assays  in  an  absolutely 
identical  manner.  If  these  differences  are  material  it  will  be  neces- 
sary to  fill  in  the  gaps  with  explicit  instructions. 
