212 
Anhydrous  Sodium  Sulphite. 
Am.  Jour.  Pharm. 
May,  1910. 
which  on  analysis  immediately  after  preparation  showed  a  percen- 
tage purity  of  99.69,  was  found  to  have  lost  approximately  one-fifth 
of  its  total  available  sulphite  after  standing  for  six  months  in  a 
glass-stoppered  bottle,  under  ordinary  conditions,  the  bottle  having 
been  opened  only  a  few  times  during  this  interval  in  order  to  re- 
move small  amounts  of  the  salt.  It  appears  also  that  others  have 
met  with  similar  experience  in  the  examination  of  this  salt.  Thus 
table  1 
Showing  the  Degree  of  Purity  of  Samples  of  Anhydrous  Sodium 
Sulphite  Obtained  from  Vario  us  Sources. 
Number  of  sample 
Amount  taken  for 
Xo  Iodine 
Percentage 
analysis  (gramme) 
required  (c.c.) 
purity 
t  (Commercial)  . 
....  O.I260 
18.25 
91.25 
2 
.  .  .  .  0.1260 
18.75 
93-75 
3 
....  O.I260 
I9.20 
96.00 
4 
....  O.I260 
I9.3O 
96.50 
5 
....  O.I26o 
I9.3O 
96.50 
6 
  0.1260 
1945 
97-25 
7  (Prepared  as 
de- 
scribed  by  Kastle 
and  Elvove) 
....  0.1260 
I9.80 
99.00 
8  (Prepared  and 
ana- 
lyzed   by  Hartley 
and  Barrett, 
using 
an  indirect  m 
ethod 
f 
of  analysis)  . 
....  0.1260 
99.87 
Smith,  Kline  and  French  Co.2  report  on  the  examination  of  12 
samples  of  sodium  sulphite  (Na.SO3.7PLO)  several  of  which  con- 
tained only  90  per  cent,  of  this  salt.  Likewise,  Patch  3  has  found  all 
of  the  four  samples  which  he  examined  to  contain  an  excess  of  sul- 
phate ;  his  results  showing  that  100  parts  of  the  dried  sodium  sulphite 
represented  from  137  to  167  of  the  crystallized  salt,  whereas,  if  the 
latter  had  been  of  U.S. P.  purity,  100  parts  of  the  dried  sulphite 
should  have  contained  enough  Na2SO.,  to  represent  about  188  parts 
of  the  crystallized  salt. 
2  Lab.  Rep.,  S.  K.  and  F.,  1906,  p.  20  ;  from  Bull.  No.  58,  Hyg.  Lab.. 
U.  S.  Pub.  Health  and  Mar.  Hosp.  Ser,  Wash.,  p.  481. 
3  Proc.  A.  Ph.  A.,  54,  346  (1906). 
