210  United  States  Pharmacopoeia,  {AmMay'imrm* 
This  is  important.  The  difference  between  the  corrected  and  the 
uncorrected  temperatures  amounts  to  considerable,  especially  at 
high  temperatures,  and  should  be  taken  into  account. 
In  determining  such  common  constants  as  specific  gravities,  melt- 
ing-points or  boiling-points,  etc.,  it  is  surprising  what  varying  re- 
sults are  frequently  reported.  This,  of  course,  is  due  to  the  different 
methods  employed.  It  would  be  an  easy  matter  to  state  that  the 
melting-point  of  acetanilid  should  be  taken  by  means  of  a  capillary 
tube,  giving  rate  of  rise  of  temperature  per  unit  of  time,  or  to  say 
that  the  melting-point  of  beeswax  is  to  be  taken  by  Pohl's  method, 
describing  it. 
Again,  there  would  be  much  satisfaction  when  turning  to  sperma- 
ceti to  find  that  its  specific  gravity  is  so,  or  so,  taken  at  the  boiling- 
point  of  water  compared  with  water  at  150  C,  or  to  find  that  the 
specific  gravity  of  beeswax  is  to  be  determined  by  the  "  suspensory 
method." 
Another  point  in  this  connection  ought  to  be  carefully  considered 
and  that  is,  whether  or  not  it  would  not  be  of  considerable  conve- 
nience to  give  the  specific  gravities  of  fluids  at  not  only  15  0  C,  but 
25 0  C.  also.  The  writer  has  frequently  experienced  much  difficulty 
in  adjusting  the  temperature  to  150  C.  during  warm  weather.  And 
after  it  is  adjusted  there  is  much  danger  of  the  atmospheric  moist- 
ure condensing  on  the  cool  external  surface  of  the  picnometer  and 
thus  vitiating  the  results.  It  is  practically  impossible  to  keep  the 
atmosphere  within  the  balance  sufficiently  dry  to  obviate  this  diffi- 
culty. 
The  writer  does  not  wish  to  find  fault  with  anything  in  the  Phar- 
macopoeia of  a  progressive  nature,  but  it  does  seem  that  it  is  far 
more  important  to  include  in  the  next  Pharmacopoeia  concise 
methods  for  determining  the  melting-points,  specific  gravities,  etc., 
of  certain  substances,  than  to  devote  so  much  space  to  volumetric 
work.  There  is  only  one  way  of  making  up  a  volumetric  solution, 
and  if  it  is  necessary  to  sacrifice  something  to  economize  space,  omit 
that,  concerning  which  there  is  absolutely  no  question  about  its 
uniformity. 
But  is  it  necessary  to  give  up  some  of  the  volumetric  directions? 
The  writer  does  not  think  so.  On  looking  over  the  Pharmacopoeia 
we  frequently  find  repeated  expressions  like  the  following  :  "The 
solution  (5  per  cent.)  should  not  effervesce  on  the  addition  of  an 
