(2) A substance that has been melted, then
allowed to solidify.
Borosilicate
(Pyrex) glass used in most laboratory glassware is
manufactured by fusing silica (SiO
2; essentially
highly purified sand), boron trioxide (B
2O
3),
soda ash (sodium
carbonate;
Na
2CO
3), and lime (calcium oxide; CaO)
at high temperature, then allowing this melt to cool and
solidify.