164 
THE  ZIRCONIA  LIGHT. 
the  same  to  develope  the  light  of  oxyhydrogen  flame.  The 
specification  is  as  follows  : — 
Zirconia,  or  oxide  of  zirconium,  in  whatever  manner  it  may 
be  extracted  from  its  ores,  can  be  agglomerated  by  compression  ; 
for  example,  into  sticks,  discs,  cylinders,  or  other  forms  suita- 
ble for  being  exposed  to  the  flame  of  mixtures  of  oxygen  and 
hydrogen,  without  undergoing  fusion  or  other  alteration.  Of 
all  the  known  terrous  oxides  it  is  the  only  one  which  remains 
entirely  unaltered  when  submitted  to  the  action  of  a  blowpipe 
fed  by  oxygen  and  hydrogen,  or  mixture  of  oxygen  with  gase- 
ous or  liquid  carbonated  hydrogens.  Zirconia  is  also,  of  all  the 
terrous  oxides,  that  which,  when  introduced  into  an  oxyhydrogen 
flame,  develops  the  most  intense  and  the  most  fixed  light. 
To  obtain  zirconia  in  a  commercial  state  I  extract  it  from  its 
native  ores  by  transforming  by  the  action  of  chlorine  in  the 
presence  of  coal  or  charcoal  the  silicate  of  zirconium  into  double 
chloride  of  zirconium  and  of  silicium.  The  chloride  of  silicium, 
which  is  more  volatile  than  the  chloride  of  zirconium,  is  sepa- 
rated from  the  latter  by  the  action  of  heat ;  the  chloride  of  zirco- 
nium remaining  is  afterwards  converted  to  the  state  of  oxide  by 
any  of  the  methods  now  used  in  chemistry.  The  zirconia  thus 
obtained  is  first  calcined,  then  moistened,  and  submitted  in 
moulds  to  the  action  of  a  press  with  or  without  the  intervention 
of  agglutinant  substances,  such  as  borax,  boracic  acid,  or  clay. 
The  sticks,  cylinders,  discs,  or  other  forms  thus  agglomerated, 
are  brought  to  a  high  temperature,  and  thus  receive  a  kind  of 
tempering  or  preparing,  the  eff'ect  of  which  is  to  increase  their 
density  and  molecular  compactness. 
I  can  also  compress  in  moulds  shaped  for  the  purpose  a  small 
quantity  of  zirconium  capable  of  forming  a  cylinder  or  piece  of 
little  thickness,  which  may  be  united  by  compression  in  the 
same  mould  to  other  refractory  earths,  such  as  magnesia  and 
clay.  In  _^this  manner  I  obtain  sticks  or  pieces  of  which  only 
the  part  exposed  to  the  action  of  the  flame  is  of  pure  zirconia, 
while  the  remaining  portion  which  serves  as  a  support  to  it  is 
composed  of  a  cheap  material. 
The  property  composed  by  zirconia  of  being  at  once  the  most 
infusible,  the  most  unalterable,  and  the  most  luminous  of  all  the 
