How
is
glass
made
?
COOL
TURN
HEAT
MAKE
REFFER
Glass
is
1
____________________
from
liquid
sand
.
Ordinary
sand
is
2
____________________
at
a
temperature
of
1700
°C
.
After
it
is
molten
and
3
____________________
it
gains
a
different
structure
.
But
it
doesn't
matter
how
much
you
cool
the
sand
,
it
is
never
4
____________________
into
a
solid
.
Instead
,
it
becomes
a
kind
of
frozen
liquid
5
____________________
by
scientists
as
amorphous
solid
.
MIX
BE
HEAT
In
a
commercial
glass
plant
,
sand
6
____________________
7
____________________
with
waste
glass
(
from
recycling
collections
)
,
soda
ash
(
sodium
carbonate
)
,
and
limestone
(
calcium
carbonate
)
and
8
____________________
in
a
furnace
.
CALL
ADD
The
soda
reduces
the
sand's
melting
point
,
which
helps
to
save
energy
during
manufacture
,
but
it
has
an
unfortunate
drawback
:
it
produces
a
kind
of
glass
that
would
dissolve
in
water
!
The
limestone
is
9
____________________
to
stop
that
happening
.
The
end
-
product
is
10
____________________
soda
-
lime
-
silica
glass
.
It's
the
ordinary
glass
we
can
see
all
around
us
.
