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TRANSPARENCY  OF  MOLTEN  METALS. 
TRANSPARENCY  OF  MOLTEN  METALS. 
The  assertion  of  Secchi,  a  few  months  ago,  regarding  the 
transparency  of  heated  iron,  has  given  rise  to  much  talk  ;  but 
we  have  not  yet  seen  it  confirmed  by  the  statement  of  any  other 
competent  eye-witness.  Meanwhile,  however,  many  assertions 
have  been  made  as  to  the  transparency  of  metals  when  melted ; 
and  the  evidence  on  this  point  begins  to  stagger  the  savans.  It 
so  happens,  that,  so  far  as  we  are  aware,  no  professional  chemist 
or  educated  physicist  has  yet  testified  to  the  phenomenon  as 
actually  observed  by  him.  It  is  merely  said  in  various  quarters 
to  be  a  fact,  well  known  to  the  workmen  employed  in  melting 
and  moulding  certain  metals.  We  deem  it,  therefore,  important 
to  mention  the  first  authentic  endorsement  which  has  come  to 
our  notice.  M.  Paul  Morin,  the  accomplished  chemist  in  charge 
of  the  Aluminium  Bronze  Works  near  Paris,  asserts  that  the 
melted  alloy,  when  poured  into  the  mould,  is  transparent ;  and 
Mr.  T.  Sterry  Hunt,  to  whom  the  assertion  was  made,  and  who 
saw  the  operation  performed,  assures  us  that  the  appearance  of 
the  molten  stream  seemed  to  corroborate  the  statement.  There 
is  a  possibility  of  optical  illusion  in  the  inspection  of  a  body 
which  is  itself  intensely  luminous,  to  discover  whether  it  is 
transparent.  We  suggest  that  the  question  may  be  easily  settled 
by  the  means  employed  to  show  the  transparency  of  ordinary 
flame,  namely,  by  burning  magnesium,  or  in  some  other  way 
producing  a  more  brilliant  light,  behind  it.  The  aluminium 
bronze  is  remarkable  for  two"  things,  among  other  qualities,  which 
distinguish  it  from  ordinary  alloys.  One  is  the  intense  tempera- 
ture developed  by  the  union  of  the  two  metals,  and  the  other  is 
the  extreme  fluidity  of  the  molten  compound.  Perhaps  these 
qualities  may  be  connected  with  the  alledged  phenomenon  of 
transparency.  Copper  may  also  be  transparent  in  the  liquid 
state  ;  but,  in  pouring  it  into  moulds,  it  often  oxidizes  very 
rapidly  ;  and  the  whole  liquid  mass  is  believed  to  be  filled  with 
disseminated  particles  of  the  red  oxide  of  copper,  which  is 
opaque.  Whether  from  this  cause  or  not,  we  cannot  say,  but 
the  evidence  as  to  the  transparency  of  molten  copper,  as  likewise 
in  the  case  of  other  metals,  is  still  conflicting  and  inconclusive. 
Chem.  News,  Nov.  22,  1867,  from  Amer.  Jour.  Min. 
