362  Development  of  the  Chemical  Arts.  {^"^-^^Z'S^t^"' 
which,  on  a  small  scale,  much  resembled  those  now  in  use  at  gas-works. 
About  the  same  time,  Saron  constructed  two  blowpipes  {chalumeaux)^ 
one  of  which  delivered  oxygen  and  the  other  hydrogen.  By  their 
means,  however,  Lavoisier  did  not  succeed  in  fusing  platinum.*  He 
hoped,  however,  to  construct  an  improved  blowpipe,  in  which  the  ox- 
ygen should  surround  the  hydrogen,  and  thus  was  developed  the  plan  of 
the  oxyhydrogen  blowpipe,  which  has  rendered  such  essential  service  in 
the  metallurgy  of  platinum  and  in  soldering  lead. 
The  application  of  oxygen  for  melting  platinum  remained  dormant 
until,  in  1857  i^SQi  Deville  and  Debray  made  known  their  impor- 
tant investigationsf  on  the  platinum  metals,  and  introduced  the  indus- 
trial fusion  of  platinum.  The  autogenous  soldering  of  platinum,  and 
the  production  of  fused  ingots  on  the  large  scale,  was  first  carried  out 
by  Johnson,  Matthey  &  Co.,  of  London,  and  also  by  Heraeus,  of 
Hanau,  in  Germany. 
Debray's  and  Deville's  experiments  led,  above  all,  to  the  discovery  of 
a  refractory  material  for  crucibles  and  furnaces.  For  this  purpose 
quick-lime  offered  itself,  which  has  the  further  advantage  of  retaining 
the  heat  as  completely  as  possible.  The  chemists  above-named  in- 
creased the  heat  further  bv  leading  the  flame  from  above  directly  upon 
the  surface  of  the  metal,  and  determined  the  amounts  of  oxygen  and 
hydrogen  theoretically  and  practically  necessary  for  melting  2  kilos,  of 
platinum,  /.  bv  calculation,  55  litres  of  oxygen  and  1 10  of  hydrogen. 
The  amount  actually  fused  was  more  than  i  kilo.,  so  that — a  highly 
favorable  result — not  50  per  cent,  of  the  heat  produced  was  wasted. 
These  experiments  had  a  further  bearing  upon  the  industrial  history  of 
oxygen,  as  they  led  to  the  comparison  of  the  cost  of  the  methods  of 
its  production  and  to  the  search  for  a  less  expensive  process.  We  may 
divide  the  known  methods  into  chemical  and  mechanical,  subdividing 
the  former  into  continuous  and  interrupted  procedures. 
Up  to  this  time,  the  following  methods  of  preparation  were  either 
in  use,  or  had  been  proposed  :  The  original  process  of  Priestley,  heat- 
ing oxide  of  mercury,  of  course,  the  most  expensive,  and  the  least 
suited  for  technological  purposes  ;  then  Scheele's  method,  treatment  of 
peroxide  of  manganese  with  sulphuric  acid,  the  result  being  manganous 
sulphate  and  oxygen.     On  the  large  scale,  since  the  investigations  of 
^  Lavoisier,  "  Oeuvres,"  ii,  430. 
t  Deville  and  Debray,  1859,  "Ann.  Chim.  Phys."  Ivi,  385.  "  Dingler's  Polyt. 
Journ,."  civ,  130,  199,  287,  383. 
