^"'■AuSust^Y92o:}      U.  S.  Pkarmacopoeial  Revision.  549 
Atomic  Weights. — ^We  recommend  that  the  Atomic  and  Molecular 
Weights  be  based  upon  the  latest  available  list  of  Atomic  Weights, 
authorized  by  the  International  Committee  on  Atomic  Weights. 
General  Formulae. — The  introduction  of  General  Formulae  into 
the  U.  S.  P.  IX  we  believe  has  been  entirely  satisfactory,  so  far  as 
applied.  We  recommend  that  the  use  of  General  Formulae  be  ex- 
tended to  every  class  of  preparation  where  such  a  general  treatment 
is  possible. 
Physical  Constants. — ^We  recommend  that  official  methods  for 
determining  Physical  Constants  be  given  in  the  U.  S.  P.  X,  and  the 
methods  described  in  the  U.  S.  P.  IX  should  be  extended  and  im- 
proved. 
Solubilities.— -It  is  recommended  that  the  statements  regarding 
Solubilities  be  extended  to  cover  all  of  the  more  commonly  used 
solvents. 
Standard  Temperature. — ^We  recommend  that  the  U.  S.  P.  retain 
in  the  next  revision  25°  C.  as  the  standard  temperature,  except 
in  the  case  of  alcohol. 
Compound  Preparations. — The  introduction  of  formulas  for 
new    Compound  Preparations"  should  be  discouraged. 
Pharmacognostical  Descriptions. — It  is  recommended  by  your 
Committee  that  the  description  of  Crude  Drugs,  with  brief  pharma- 
cognostical descriptions,  both  macroscopic  and  microscopic,  as 
given  in  the  many  monographs  of  the  U.  S.  P.  IX,  be  extended  to 
cover  all  drugs  where  the  knowledge  will  permit  of  such  pharmacog- 
nostical descriptions. 
Powdered  and  Ground  Drugs. — ^Wherever  practicable,  the  ground 
or  powdered  drug  should  be  required  to  represent  the  entire  drug. 
Where  the  data  available  is  sufficient  to  serve  as  a  basis  for  a  standard 
for  allowable  tailings,  gruffs  or  residue,  this  should  be  determined 
and  inserted  in  the  text. 
Date  When  Official. — It  is  recommended  that  the  Committee  of 
Revision  continue  the  practice  of  printing  upon  the  Title  Page  of 
the  Pharmacopoeia  a  definite  date  when  the  revised  Pharmacopoeia 
shall  supersede  the  previous  edition.  Due  consideration  should  be 
given  to  the  time  necessary  to  dispose  of  stocks  on  hand  and  to  pre- 
pare new  formulas  for  the  trade.  The  period  between  the  time 
when  the  book  becomes  available  to  the  trade  and  when  it  becomes 
official  shall  be  not  less  than  six  months. 
