'he  thinner  the  coat  of  the  application
the  more  brilliant  ^e  film  of  platiniim.
All  that  is  required  further  is  to  subject
the  articles  for  a  few  minutes  to  a  very
low,  scarcely  perceptible  red  h«fat.
either  in  a  muffle  or  in  the  flame  of
a  Bunsen's  gas-blowpipe  used  with  cau-
tion. The  articles  receive  fit>m  thia
baking  a  beautiful  lustre  as  brilliant
as  silver.  If,  by  an  oversight,  the  coat-
ing of  platinum  upon  the  articles  has
turned  out  fiiulty^,  or  if  breakages
occur  during  the  baking,  every  trace
of  the  metal  can  be  recovered  fifom  the
objects.  Nothing  more  is  reouired
than  to  pour  common  hydrocnlorie
acid  over  them*  and  then  touch  them
with  a  zinc  rod.  In  consequence  of
the  hydrocen  evolved,  botn  at  the
upper  and  Tower  surface  of  the  film  of
platinum  which  acts  as  the  negative
pole,  the  shining  metallic  coating  in-
stantly peels  off  in  the  form  of  ex-
tremely thin  leaves  from  the  base  of
porcelain  or  glass  and,  notwithstanding
the  specific  gravity  of  the  metal,  these
ascend  partially  and  float  on  the  sur-
face of  Hie  acid.  On  separating  the
hydrochloric  acid  by  the  use  of  a  filter
the  whole  of  the  phUinnm  is  recovered.
One  should  prepare  only  as  much  oif
the  platinizing  nuid  as  is  required  for
immediate  use,  as  it  loses  in  efficiency
by  keeping.
Totighened  Olass,  In  this  process
the  red-hot  ^lass  is  dipped  into  a  warm
bath  consisting  of  water  and  starch,  or
gum  kept  at  212°  F.  It  is  taken  out
again  when  the  red  glow  has  almost
gone,  and  is  then  allowed  to  cool  in  an
oven  kept  at  a  slightly  lower  tempera-
ture than  the  glass.  Any  article  of
glass  can  be  treated  by  this  method.
HORN-COMBS.— LUBRICANTS.  BLACKING,  ETC.
