82  The  U.S.P.  as  a  Legal  Standard.  {Ag^™£*^m- 
(strong)  sulphuric  acid."  The  tests,  however,  can  be  applied  as 
well  to  the  dilute  as  to  the  strong  acid ;  indeed,  most  of  them  are 
applied  to  the  latter  by  considerable  dilution,  and  the  pharmacists 
can  control  the  dilute  product  perfectly.  At  the  present  day  any 
pharmacist  can  obtain  at  moderate  cost  pure  strong  acids ;  minute 
tests,  such  as  those  for  nitrous  compounds  in  sulphuric  acid,  are  un- 
necessary. 
Much  attention  has  been  devoted  to  the  tests  for  purity  of  the 
preparations.  This  has  always  been  a  difficult  point  in  the  Pharma- 
copoeia. In  some  former  editions  serious  errors  have  been  made 
and  injustice  has  been  done.  It  is  too  soon  to  determine  how  far 
the  new  edition  has  accomplished  better  work.  The  Pharmaco- 
poeia is  always  issued  under  a  sort  of  star-chamber  control.  Only  a 
few  persons  are  taken  into  confidence,  and  the  bulk  of  the  medical 
and  pharmaceutical  profession  finds  material  for  much  surprise  and 
astonishment  when  the  book  appears. 
On  some  points,  however,  issue  may  be  taken  at  once ;  they  are 
so  obviously  amiss.    I  instance  first  the  tests  for  the  purity  of  water. 
The  work  specifies  "  water  "  and  "  distilled  water."  The  former 
is  defined  to  be  "  potable  water  in  its  purest  attainable  state."  As 
we  are  not  informed  upon  what  basis  the  limitations  as  to  purity  are 
fixed,  this  definition  is  vague  and  ambiguous.  We  turn, -therefore, 
to  the  analytic  notes.  To  any  one  familiar  with  water  analysis,  the 
rubric  seems  to  be  more  a  product  of  the  library  than  of  the 
laboratory. 
In  the  first  place,  the  sample  must  be  a  colorless,  limpid  liquid, 
without  odor  or  taste  at  ordinary  temperatures  and  odorless  when 
heated.  Very  few  potable  waters  will  conform  to  these  require- 
ments, and  many  that  will  not  are  entirely  safe  for  pharmaceutic 
uses.  One  gains  an  idea  from  this  statement  that  the  intention  is 
to  include  under  the  title  only  natural  waters  of  exceptionally  high 
purity,  but  a  few  lines  below  the  limit  of  total  solids  is  given  as  500 
parts  per  million.  This  is  equivalent  to  29  grains  per  gallon,  an 
amount  unusual  in  natural  waters,  except  from  deep  sources.  Yet 
even  with  this  limit  the  water  must  be  neutral  to  litmus  paper,  a 
condition  to  which  high-class  natural  waters  will  not  conform,  and 
yet  for  the  rejection  of  which  no  good  reason  seems  to  be  offered. 
The  total  solids  of  the  water  are  to  be  determined  by  a  method 
that  is  not  in  use  by  analysts  and  is  tedious  and  inconvenient, 
