NOTE  ON  METALLIC  BISMUTH,  ETC. 
405 
attended  with  considerable  difficulty.  Of  the  impurities  most 
commonly  occurring,  aisenic,  lead,  copper  and  silver  are  the 
most  important.  The  bismuth  may  be  freed  from  the  first  two 
of  these,  if  present,  with  comparative  ease,  by  a  simple  metallur- 
gical operation  which  consists  in  fusing  it  with  nitre,  as  directed 
in  the  Pharmacopoeia.  This  is  the  process  usually  adopted,  and 
which  answers  best  for  removing  the  more  oxidizable  metals.  It 
may  be  conveniently  and  successfully  applied  to  quantities  of  the 
metal  varying  from  four  ounces  to  a  pound  by  means  of  a  gas 
furnace.  The  process,  however,  is  insufficient  for  the  removal  of 
copper  and  silver ;  and  it  is  with  reference  especially  to  the  for- 
mer of  these  that  the  principal  difficulty  is  experienced  in  puri- 
fying some  of  the  crude  bismuth  and  bismuth  ores  of  commerce. 
At  the  present  time  large  quantities  of  Australian  ore,  rich  in 
copper,  are  waiting  the  discovery  of  a  method  by  which  the  bis- 
muth it  contains  may  be  economically  separated  in  a  state  of 
sufficient  purity  to  admit  of  its  being  used  for  pharmaceutical 
purposes.  When  this  question  has  been  satisfactorily  solved, 
there  is  every  reason  to  believe  that  a  great  reduction  in  the 
price  of  the  metal  will  take  place.  In  the  meantime  we  shall 
have  much  impure  bismuth,  containing  copper,  which,  although 
applicable  for  one  of  the  purposes  for  which  bismuth  is  required, 
— namely,  the  preparation  of  fusible  metal, — is  not  well  suited 
for  the  production  of  the  compounds  of  bismuth  used  in  medicine. 
Already  the  attention  of  metallurgists  has  been  directed  to  the 
importance  of  providing  a  supply  of  purified  bismuth  for  pharma- 
ceutists, and  I  am  assured  by  houses  extensively  engaged  in  this 
branch  of  metallurgy  that  bismuth,  free  from  arsenic,  copper,  or 
any  material  impurity,  may  now  be  obtained  by  those  who  are 
willing  to  pay  the  price  for  it.*  As  this  purified  bismuth  is  pre- 
pared by  men  accustomed  to  such  operations  from  the  ores  which 
yield  it  most  readily,  it  will  be  found  the  most  economical  and 
best  course  for  those  who  require  pure  bismuth  to  buy  the  metal 
in  the  purified  state,  or  otherwise  it  will  be  necessary,  in  apply- 
ing the  process  of  the  Pharmacopoeia,  to  use  crude  bismuth  which 
is  free  from  copper  and  silver. 
*  I  have  recently  purchased  such  at  20s.  a  pound,  the  price  of  crude 
bismuth  being  at  the  same  time  18s.  a  pound. 
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