84  The  U.S. P.  as  a  Legal  Standard.  {A^e^vyPimm' 
the  standards  of  purity  in  water  are  correlated  with  the  class  to 
which  the  water  belongs.  The  tests  for  ammonium  compounds  and 
oxidizable  organic  matter  are  also  under  the  same  spell. 
The  absurdity  of  these  standards  for  purity  becomes  still  more 
glaring  when  the  tests  for  distilled  water  are  examined.  The  editor 
of  this  part  seems  to  have  an  idea  that  the  nitrates,  nitrites  and 
ammonium  compounds  often  found  in  water  are  in  themselves 
objectionable;  whereas  they  are  merely  indexes  of  past  impurity. 
In  the  case  of  distilled  water,  small  amounts  of  the  above  compounds 
can  have  no  significance.  The  application  of  difficult  and  delicate 
tests  will  produce  nothing  but  confusion  and,  perhaps,  the  rejection 
of  a  sample  that  is  entirely  suited  to  pharmaceutic  purposes. 
It  is  certainly  strange  that  those  members  of  the  committee  of 
revision  who  have  been  for  years  in  general  analytic  practice  allowed 
such  absurd  rubrics  to  appear. 
In  a  recent  communication  a  member  of  the  revision  committee 
has  endeavored  to  explain  some  of  the  features  of  the  water-rubric, 
among  others  the  allowance  of  75  parts  per  million  for  fixed  solids 
(in  distilled  water),  for  which  the  absurd  requirement  that  1,000 
c.c.  of  water  should  be  evaporated  is  again  given.  Seventy-five  parts 
per  million  are  equivalent  to  over  4  grains  per  United  States  gallon, 
an  amount  larger  than  that  in  many  spring  and  river  waters  of  the 
United  States.  As  by  further  statement  in  this  rubric,  it  appears 
that  the  water  is  not  permitted  to  contain  anything  that  is  likely  to 
be  present,  the  total  solids  are  more  easily  imagined  than  described. 
It  will  be  interesting  to  know  why  a  small  amount  of  carbonic  acid 
is  objectionable,  and  also  how  the  stock  of  distilled  water,  the  con- 
tainer of  which  must  be  frequently  opened  to  the  air,  can  be  pre- 
vented from  acquiring  some  of  this  substance. 
The  above-mentioned  defense  of  the  water-rubric  stated  that  the 
reason  for  allowing  the  large  margin  for  the  total  solids  is  the  action 
of  water  on  glass.  It  may  be  said,  however,  that  a  sample  which 
has  dissolved  so  much  of  mineral  matter  is  no  longer  pure  water, 
and  should  not  be  approved  as  such.  This  reason  for  the  liberal 
allowance  sounds  a  little  strange  in  comparison  with  a  general 
requirement  in  regard  to  reagents,  namely,  that  they  should  be  kept 
in  bottles  not  subject  to  corrosion  by  acids  or  alkalies.  It  will  be 
found  difficult  to  meet  this  requirement. 
As  an  example  of  excessive  elaboration  of  tests,  I  wish  to  instance 
