Augusri92S:  1       U.  S.  Pharmacopoeial  Revision.  55 1 
It  is  quite  safe  to  say  that  the  average  user  of  the  Pharmacopoeia 
knows  better  what  the  sources  of  quinine  or  sugar  are  then  those  of 
acetic  acid  or  ammonium  chloride.  The  U.  S.  P.  does  not  give  the 
derivation  of  the  latter  two  substances,  yet  apparently  nobody 
missed  it  and  it  did  not  detract  from  the  prestige  and  value  of  the 
book.  For  the  purpose  of  the  Pharmacopoeia,  the  derivation  of  a 
definite  chemical  substance,  like  the  method  of  its  manufacture, 
does  not  at  all  matter,  provided,  of  course,  it  measures  up  to  the 
U.  S.  P.  specifications. 
The  definition  of  quinine  sulphate  as  "The  sulphate  of  the  al- 
kaloid quinine,"  and  similar  other  definitions  are  tautologies.  So- 
dium sulphate  is  not  defined  in  the  U.  S.  P.  as  the  sulphate  of  the 
metal  sodium.  Why? 
It  is  therefore  recommended  that  in  the  next  revision  of  the 
Pharmacopoeia  derivations  of  definite  chemical  compounds  and 
definitions  of  organic  chemicals,  of  the  character  cited  above,  be 
omitted  except  when  the  definition  is  necessary  for  purposes  of  iden- 
tification. 
Purity  Rubrics. — -The  object  of  purity  rubrics  and  assays  is  to 
secure  preparations  and  drugs  of  standard  quality.  If  the  same 
ends  can  be  attained  by  the  use  of  simpler  tests,  there  is  obviously 
no  reason  for  employing  difficult  and  laborious  tests.  This  being 
granted,  as  a  matter  of  course,  several  purity  rubrics  and  assays 
could  be  advantageously  omitted.  No  purity  rubric  of  99.5  per 
cent,  or  an  assay  is  needed  for  mercury.  If  the  mercury  is  of  the 
proper  appearance,  it  is  necessarily  more  than  99.5  per  cent,  pure; 
in  fact,  it  is  nearly  100  per  cent.  pure.  The  assay  of  sulphur  is  a 
difficult  one  and  not  infrequently  runs  amuck.  Is  this  assay  really 
necessary  to  insure  a  product  of  the  desired  purity?  The  good  ap- 
pearance of  the  sulphur  in  connection  with  a  limit  for  non-volatile 
matter,  and  a  few  more  simple  tests  if  needed,  will  insure  as  pure  a 
product  as  is  afforded  by  an  assay.  Why  then  burden  the  users  of 
the  Pharmacopoeia  with  unnecessary  work?  Most  probably  the 
assay  of  sulphur  and  a  few  other  similar  official  assays  are  very  little 
used  and  then  only  as  a  matter  of  formality. 
Tests  for  Impurities. — In  the  ^  Ninth  Revision  of  the  U.  S.  P. 
greater  definiteness  has  been  achieved  in  the  description  of  chemical 
tests  than  in  former  revisions,  but  perfection  has  not  been  reached 
— if  it  ever  will  be.  Because  of  the  extensive  and  growing  use  of 
Pharmacopoeial  standards  and  methods  of  testing,  the  tests  for 
