These  samples  were  all  white  powders  or  colorless 
translucent  lumps,  except  a  yellow  tinge  in  No.  5  and 
No.  6;  solutions  of  all  were  neutral  to  litmus,  gave 
distinct  violet  color  to  flame  and  remained  clear  on 
the  addition  of  sulphide  of  ammonium,  carbonate  of 
ammonium,  oxalate  of  ammonium,  and  chloride  of 
barium.    No.  8  was  a  selected  crystal. 
AmjunUe?Sarm'}  Pharmaceutical  Notes  from  Purdue  University.  287 
however,  three  spurious  preparations  sold  under  the  name  of  com- 
mercial saltpetre.  Number  9  is  essentially  nitrate  of  sodium  (sometimes 
called  >Chili  saltpetre) ;  number  1 1  is  chloride  of  sodium  in  angular 
transparent  lumps  (or  "rock  salt");  and  number  10  is  a  mixture  of 
both. 
The  examination  was  conducted  under  my  direction  by  Mr.  E.  G. 
Eberhardt  and  other  students  of  the  School  of  Pharmacy. 
REACTIONS  OBSERVED. 
Reaction  with  Nitrate  of 
Silver. 
Genuine. 
No.  1,  Opalescence. 
No.  2,  Precipitate. 
No.  3,  Slight  Prec. 
No.  4,  Slight  Opal. 
No.  5,  None. 
No.  6,  Slight  Opal. 
No.  7,  Slight  Opal. 
No.  8,  Slight  Preci. 
False  -J      Solutions  of  these  samples  were  neutral  with  litmus, 
gave  bright  yellow  color  to  the  flame,  and  remained 
No.  9,  Opalescence.  j  clear  oa  the  addition  of  sulphide  and  carbonate  of 
ammonium;  but  chloride  of  barium  and  oxalate  of 
calcium  showed  traces  of  sulphate  of  calcium  in  No. 
11,  and  still  more  in  No.  10. 
Remarks  on  Genuine  Saltpetre. — The  eight  samples  of  nitrate  of 
potassium  examined,  conformed  very  closely  to  the  requirements  of 
the  Pharmacopoeia ;  but  two  of  them  had  a  tinge  of  color,  and  four  had 
excess  of  chloride.  Being  uncertain  whether  the  reaction  of  number 
1  with  silver  nitrate  exceeds  the  official  limit  of  "  faint  opalescence/7 
I  had  the  chloride  estimated  with  decinormal  solution  of  silver  nitrate, 
finding  only  0"08  per  cent.  Number  2,  by  the  same  process,  contained 
0*55  per  cent,  and  number  3,  0*25  per  cent.  It  may  be  asked  whether 
so  small  an  amount  of  chloride  as  0*5  per  cent,  can  be  a  practical  ob- 
jection to.  the  use  of  saltpetre,  even  for  the  preparation  of  diluted  ni- 
trate of  silver,  a  considerable  proportion  of  chloride  of  silver  being 
purposely  formed  in  the  preparation  of  moulded  nitrate  of  silver.  The 
complete  purification  of  saltpetre  inevitably  adds  considerably  to  its 
cost  of  manufacture ;  but  it  is  desirable  that  the  pharmaceutical  pro- 
fession should  either  maintain  the  official  standard  as  nearly  as  possible, 
or  should  express  their  desires  for  more  latitude  through  the  Com- 
mittee on  Revision  of  the  Pharmacopoeia. 
No.  10,  Heavy  Prec. 
No.  11,  Heavy  Prec. 
