Am.  Jour.  Pharai.  ) 
May,  1910.  J 
Anhydrous  Sodium  Sulphite. 
211 
antidiphtheric  serum  of  the  U.S. P.,  it  would  seem  that  by  adopting 
pure  metallic  silver  as  the  ultimate  standard  in  volumetric  analysis 
we  would  pave  the  way  for  finally  having  such  standard  supplied 
from  one  source,  thus  making  the  uniformity  absolutely  complete. 
It  would  seem  advisable,  therefore,  that  in  the  next  revision  of  the 
U.  S.  Pharmacopoeia  pure  metallic  silver  be  adopted  as  the  ultimate 
standard  for  the  required  volumetric  solutions. 
Public  Health  and 'Marine-Hospital  Service, 
Hygienic  Laboratory,  Washington,  D.  C. 
A  NOTE  ON  THE  SUBSTITUTION  OF  ANHYDROUS 
SODIUM  SULPHITE  FOR  THE  HYDRATED 
VARIETY  GIVEN  IN  THE  U.  S. 
PHARMACOPOEIA. 
By  Elias  Elvove. 
According  to  the  present  U.  S.  Pharmacopoeia  sodium  sulphite 
(Na2S03.7H20)  should  contain  not  less  than  94  per  cent,  of  this 
salt.  The  experience  in  this  laboratory,  however,  has  been  that 
when  this  salt  is  obtained  commercially  it  frequently  contains  sul- 
phate as  an  impurity  which  is  about  as  large  in  amount  as  the 
remaining  sulphite.  An  idea  as  to  the  amount  of  sulphate  which 
may  be  present  in  such  samples  of  sulphite  may  be  obtained  from 
the  results  of  an  analysis 1  carried  out  in  this  laboratory  on  a 
sample  of  this  salt  which  was  obtained  from  one  of  the  most  careful 
and  reliable  firms  in  the  country.    This  analysis  resulted  as  follows : 
Found 
(Per  cent.) 
Sodium  sulphite   22.05 
Sodium  sulphate   25.00 
Water  (loss  on  drying  in  vacuo  at  ioo°  C.)   52-5o 
99-55 
That  this  sample  of.  sodium  sulphite  probably  was  up  to  the 
required  standard  when  first  prepared,  but  had  been  thus  reduced 
in  its  sulphite  content  as  the  result  of  the  lapse  of  time  between  its 
preparation  and  analysis,  is  indicated  by  the  fact  that  a  sample  of  this 
salt  (Na2S03.7H20)  which  was  prepared  in  this  laboratory  and 
1  Kastle  and  Elvove:  Jour.  Infectious  Diseases,  6,  619—629  (1909). 
