22  Silver  in  Subnitrate  of  Bismuth.  {AnjaJnOUMP873Rlfe- 
was  considered  sufficiently  proved  by  the  residue  on  the  filter  being: 
blackened  by  exposure  to  light,  by  its  being  soluble  in  ammonia,  and 
giving  in  its  ammoniacal  solution  a  light  lemon  colored  precipitate* 
with  iodide  of  potassium.  The  chloride  was  precipitated  from  the  ni- 
tric acid  solution  and  weighed  as  chloride  of  silver  in  the  usual  way. 
In  no  case  did  diluted  sulphuric  acid  give  any  precipitate,  thus  show- 
ing the  absence  of  lead. 
Sample  1.  The  one  first  mentioned  above.  A  very  short  exposure 
to  light  blackened  it.  Was  not  examined  further,  as  the  manufac- 
turers acknowledged  the  contamination  of  silver. 
2.  The  second  sample  mentioned  above  contained  much  less  silver 
than  sample  1,  but  sufficient  to  give  a  distinct  bluish  tint  when  ex- 
posed to  light  for  two  or  three  days. 
3.  Not  a  subnitrate  at  all,  but  a  basic  subchloride,  containing  chlo- 
rine equal  to  90  per  cent,  of  BiOCl ;  not  completely  soluble  in  nitric; 
acid,  and  contained  silver. 
4.  Contained  silver  and  3*9  per  eent.  of  subchloride. 
5.  Contained  traces  of  subchloride,  but  no  silver. 
6.  Traces  both  of  subchloride  and  silver. 
7.  Neither  silver  nor  subchloride. 
8.  Contained  silver  and  4*9  per  cent,  subchloride. 
9.  Neither  silver  nor  subchloride. 
10.  Silver  and  traces  of  subchloride. 
11.  Neither  silver  nor  subchloride. 
12.  No  silver,  but  6*5  per  cent,  subchloride. 
13.  No  silver  ;  traces  of  subchloride. 
14.  No  silver ;  about  one  per  cent,  subchloride. 
15.  Neither  silver  nor  subchloride. 
The  samples  showed  great  diversity  in  density  and  appearance* 
Sample  No.  1  was  a  damp  powder,  having  a  strongly  acid  smell  and 
reaction.  I  am  assured  by  manufacturers  that  subnitrate  prepared 
strictly  according  to  the  Pharmacopoeia,  after  having  been  kept  for 
about  two  months,  developes  so  much  acid  as  actually  to  effervesce 
with  carbonates.  After  rewashing,  however,  it  becomes  more  basic 
and  more  stable. 
In  sample  No.  3,  obtained  from  a  London  dispensing  house,  the 
substitution  by  the  manufacturer  of  a  subchloride  for  a  subnitrate  is 
of  course  unpardonable.  I  have  understood  that,  owing  to  its  being 
prepared  at  a  less  cost,  there  is  a  great  deal  of  subchloride  sold  as 
subnitrate,  but  this  is  the  first  sample  I  have  ever  met  with. 
