AmNov"ri9Pi8arm' )  Normal  Salt  Solution.  785 
be  interesting  to  know  why  the  pharmacopoeia  requires  aqua  destil- 
lata  sterilisata  to  be  boiled  only  for  a  half  hour  and  normal  salt 
solution  is  required  to  be  boiled  for  one  hour,  (except  for  the  reason 
that  normal  salt  solution  may  be  regarded  as  being  better  fitted 
to  support  bacterial  life).  But  besides  this  slight  error  of  nonunifor- 
mity,  the  greatest  error  perhaps  is  in  not  requiring  a  replacement 
by  recently  freshly  distilled  water  of  that  portion  that  has  been 
lost  during  evaporation.  As  the  formula  now  stands,  the  physician, 
when  using  normal  salt  solution  (sterilized  by  boiling)  does  not  ad- 
minister a  .85  per  cent,  sodium  chloride  solution  but  a  more  concen- 
trated product  or  one  which  really  is  slightly  hypertonic,  and  at  that, 
each  subsequent  solution  prepared  varies  in  strength  depending 
upon  the  degree  of  heat  used  in  boiling.  To  fully  ascertain  the  loss 
by  evaporation  during  sterilization  by  the  various  methods  available, 
the  following  experiments  were  performed. 
Five  gallons  of  normal  salt  solution  were  prepared,  as  directed 
by  the  U.  S.  P.,  which  upon  titration  was  found  to  contain  accu- 
rately .85  per  cent.  NaCl. 
3-  (1,000  Cc.  non  sol.)  flasks, 
3  (    500  Cc.  non  sol.)  flasks, 
3  (  100  Cc.  non  sol.)  flasks, 
were  selected  so  that  the  mouth  of  each  respective  set  of  flasks  were 
of  about  the  same  diameter.  These  were  then  cotton-plugged  and 
sterilized  at  1600  C.  for  one  hour.  The  nine  flasks  were  then  divided 
into  three  sets,  each  set  consisting  of  a  1,000-Cc.  flask,  a  500-Cc. 
flask,  and  a  100-Cc.  (filled  respectively  with  1,000  Cc,  500  Cc.  and 
ico  Cc.  of  salt  solution).  One  set  was  autoclaved  at  15-pound  pres- 
sure for  twenty  minutes,  the  other  set  was  heated  in  a  steam  steri- 
lizer (made  by  generating  steam  in  a  bucket  containing  a  false  bot- 
tom), and  the  third  set  was  heated  by  boiling  moderately  for  one 
hour.  The  same  test  was  repeated  on  two  different  dates.  After 
each  sterilization,  the  flasks  were  allowed  to  stand  for  twenty-four 
hours,  until  cooled  to  room  temperature,  the  content  of  each  flask 
was  noted  to  find  the  loss  in  evaporation  and  10  Cc.  of  each  were 
titrated  to  accurately  determine  the  NaCl  content.  At  the  end  of 
the  experiment,  an  average  of  each  set  (i.  e.,  the  identical  sets  heated 
at  three  different  occasions)  was  taken  and  recorded  in  the  follow- 
ing table.    (See  Table  I.) 
