Am.  Jour.  Pharm.  | 
^gg3     J-  Commercial  Nitrite  of  Soda.  513 
of  twelve  of  these,  which  I  take  to  represent  fairly  the  commercial 
article : — 
Characters. 
Large  transparent  crystals,  very  moist 
"Old  stock,"  small  crystals,  brownish.. 
Large  transparent  crystals,  very  moist. 
Fused  mass,  white  
White  and  granular,  very  moist  
White  and  granular,  dry  
Small  crystals,  white,  moist  
Small  crystals,  brownish,  moist  
Small  crystals,  white,  moist  
Small  crystals,  brownish,  moist  
Small  crystals,  white,  dry  
Small  crystals,  white,  dry  
NaNOg. 
Per  cent. 
0-011 
0-028 
0-945 
9-6 
28-4 
84-14 
92  -5 
93-65 
95-1 
95-83 
97-21 
98  -5 
NaaCOg. 
Per  cent. 
35  -5 
29-66 
32-6 
27-34 
Nos  1  to  3  are  evidently  the  first  crop  of  crystals  from  a  solution  of 
such  a  specimen  as  No.  4,  which,  itself,  answers  the  description  of  the 
1864  Pharmacopoeia  preparation.  Nos.  5  and  6  contained  undecom- 
posed  nitrate  and  the  former  much  water.  The  others  contained 
water  in  varying  proportions  and  but  mere  traces  of  other  impurity, 
the  higher  percentages  of  Nos.  11  and  12  being  accounted  for  by  the 
fact  that  they  were  examined  as  received  from  the  makers,  while  the 
others  had  been  in  stock  for  a  few  months. 
The  percentages  in  this  case  were  determined  by  decinormal  per- 
manganate of  potash  solution,  which  gives  good  results  with  care  and 
some  practice.  A  very  good  plan  is  to  fill  a  burette  with  a  solution 
of  the  salt  under  examination  (1  gram  in  100  cc.  distilled  water  is  a 
convenient  strength)  and  drop  carefully  into  a  flask  containing  10  cc. 
permanganate  and  an  equal  volume  of  sulphuric  acid  (1  in  4)  until  a  pale 
pink  color  is  struck,  which  should  not  disappear  within  thirty  seconds. 
The  quantity  of  nitrite  solution  being  noted,  the  titration  is  repeated 
twice,  it  being  merely  necessary  to  add  10  cc.  of  permanganate  to  the 
contents  of  the  flask  each  time.  The  mean  of  the  three  estimations  is 
taken  for  calculation,  10  cc.  of  the  permanganate  solution  being 
equivalent  to  '0345  gram  NaN02.  Old  stock  of  this  article  should  be 
looked  over.   The  fused  "nitrite  of  soda"  of  the  1864  Pharmacopoeia 
33 
