The  ruby  stain,  however,  was  so  dark  that
glass  of  the  same  thickness  as  the  rest  would
have  been  practically  opaque,  while  if  it  had
been  made  thin  enough  to  give  the  required
shade  it  would  have  been  too  fragile  and
inconvenient  in  every  way.  So  the  craftsman
dipped  the  lump  of  white  glass  at  the  end  of
his  blowing  tube  into  a  pot  of  melted  ruby,
and  then  blew  his  bubble  and  spread  it  out  in
the  form  of  a  plate.  The  glass  so  made  was
white,  coated  with  a  thin  and  inseparable
layer  of  ruby,  or  sometimes  the  glass  was  so
managed  that  the  white  and  ruby  formed
alternate  layers  in  the  finished  material.
Coated  glass  is  often  called  '  flashed  ruby,'
and  this,  as  well  as  flashed  blue  or  yellow
coated  in  the  same  way,  was  in  common  use.
