128 
PLATINIZING  METALS. 
plunged  beneath  the  surface  of  the  platinizing  liquid.  One  im- 
mersion for  a  single  minute  generally  suffices ;  but  the  process 
may  be  repeated  if  necessary,  care  being  taken  to  wash  and  dry 
the  pieces  operated  upon  before  re-heating  them.  The  composi- 
tion of  the  solution  may  vary  considerably,  and  yet  good  results 
be  obtained.  Sometimes  the  addition  of  more  honey  improves 
it ;  sometimes  the  proportion  of  bichloride  of  platinum  may  be 
increased  or  diminished  with  advantage.  Indeed,  it  will  be  found 
that  the  appearance  of  the  platinum  film  deposited  upon  the  ob- 
jects may  be  altered  by  changing  the  proportion  of  the  bichloride 
present.  The  solution  may  be  used  several  times  ;  gradually, 
however,  it  loses  all  its  platinum,  the  place  of  this  element  being 
taken  by  the  iron  or  copper  dissolved  off  the  immersed  objects. 
We  may  now  appropriately  mention  a  few  examples  where  this 
platinizing  process  seems  to  furnish  desirable  results.  Articles 
made  of  iron  or  steel — watch-chains,  steels,  sword-handles,  keys, 
and  similar  useful  or  ornamental  objects — are  greatly  improved 
in  appearance,  and,  moreover,  preserved  from  all  chance  of  rust- 
ing, by  this  treatment.  The  color  of  the  platinum  film  is  of  a 
neutral  greyish  black,  and  it  often  shows  at  the  same  time  a  faint 
iridescence.  Iron  or  steel  which  has  been  inlaid  with  gold  or 
silver,  forming  what  is  known  as  damascened  work,  is  greatly 
improved  by  platinizing.  Neither  the  gold  nor  the  silver  are  in 
the  least  degree  affected,  and  they  will  be  found  to  afford  a  better 
contrast  with  the  color  of  the  platinized  than  with  that  of  the 
original  iron.  Other  artistic  applications  of  this  process  will 
readily  suggest  themselves  :  coins,  medals,  chains,  and  ornaments 
of  brass  and  copper  may  be  instanced  as  excellent  subjects  for 
experiment.  If  they  have  been  partially  gilt  or  silvered  before 
treatment  with  the  platinizing  liquid,  those  parts  only  of  the 
specimen  which  show  the  original  metal  will  change  in  color.  In 
this  way  very  beautiful  and  effective  designs  of  gold  on  platinum, 
or  silver  on  platinum,  may  be  formed,  while  in  the  case  of  gold, 
at  all  events,  the  groundwork  metal  of  copper  or  brass  would 
scarcely  have  shown  an  appreciable  contrast  of  color. — London 
Chemist  and  Druggist,  May  15,  1867,  from  the  Intellectual  Ob- 
server of  April. 
