170 
NOTE  ON  ARSENIC  IN  TRINITRATE  OF  BISMUTH. 
metallic  bismuth  was  first  roasted  at  its  fusing  pointy  during 
which  process  the  arsenic,  which  volatilizes  at  about  S67°,  was 
driven  off.  The  purified  bismuth  was  then  dissolved  in  nitric 
acid,  and  the  nitrate  obtained  in  crystals.  These  crystals  were 
afterwards  decomposed  by  the  addition  of  water,  and  the  sub- 
nitrate  was  thus  obtained,  while  any  arsenic  that  might  have 
escaped  volatilization  in  the  roasting  would  be  left  in  the  mother 
liquor  from  which  the  subnitrate  was  precipitated. 
Dr.  Redwood  thought  the  process  described  by  Mr.  Huskisson 
was  better  than  that  given  in  the  Pharmacopoeia,  and  he  ap- 
proved of  using  the  crystals  rather  than  the  acid  solution  of 
nitrate  of  bismuth  for  precipitating  with  water,  as  the  product 
would  be  less  liable  to  variation.  He  did  not  think,  however, 
that  the  roasting  of  the  metal  could  be  depended  upon  for  the 
removal  of  the  whole  of  the  arsenic,  nor  did  he  consider  the  sub- 
nitrate,  in  whatever  way  prepared,  a  satisfactory  preparation. 
He  thought,  it  might,  with  advantage  be  replaced  by  the  sub- 
carbonate. 
Mr.  Morland  inquired  of  Mr.  Huskisson  how  he  accounted 
for  the  presence  of  chlorine  in  the  subnitrate  of  bismuth  of  com- 
merce. 
Mr.  Huskisson  said  there  were  two  compounds  of  bismuth 
prepared  by  manufacturers — the  subnitrate  or  trisnitrate,  which 
was  used  in  medicine,  and  the  oxychloride,  for  the  preparation 
of  which  every  manufacturer  had  a  process  of  his  own,  and  of 
which  large  quantities  were  used  in  the  arts,  as  an  ingredient 
in  enamel,  as  a  cosmetic,  and  in  the  preparation  of  sealing-wax. 
As  the  oxychloride  was  more  expensive  than  the  subnitrate,  he 
thought  its  substitution  for  the  latter  must  have  been  the  result 
of  accident,  or  probably  the  person  selling  it  thought,  as  it  was 
not  ordered  for  medicinal  use,  that  it  was  required  as  a  pigment, 
and  therefore  that  the  oxychloride  was  the  sort  wanted. 
The  Chairman  confirmed  what  had  just  been  stated  with 
reference  to  the  oxychloride  of  bismuth,  which  he  said,  with  far 
more  extensively  used  than  the  subnitrate,  especially  in  the 
manufacture  of  white  sealing-wax.  He  thought  the  subcar- 
bonate  of  bismuth  a  better  preparation  than  the  subnitrate,  and 
less  likely  to  be  impure. —  Pharm.  Journ.  and  Trans.  Jan* 
1860. 
