bottle glass

Around, the floor was composed of solid dark green obsidian, as hard and transparent and sharp as bottle-glass.

To make bottle-glass, oxide of iron and alumina is added to the silica, lime, and soda.

A pot of green bottle-glass had been allowed to cool slowly with the result that it had a stony, rather than a vitreous structure.

Flint, plate glass, old bottle glass, onyx--all could be worked with equal facility.

It was guarded by a wall about eight feet high, the top of which bristled with bottle-glass.