Glass-wort, a genus of plants belonging to the pentandria clas; and in the natural method ranking under the 12th order, Holoraceae. See Botany Index.

All the sorts of glass-wort are sometimes promiscuously used for making the sal kali, but it is the third sort which is esteemed best for this purpose. The manner of making it is as follows: Having dug a trench near the sea, they place laths across it, on which they lay the herb in heaps, and, having made a fire below, the liquor, which runs out of the herbs, drops to the bottom, which at length thickening, becomes sal kali, which is partly of a black, and partly of an ash-colour, very sharp and corrosive, and of a saltish taste. This, when thoroughly hardened, becomes like a stone; and in that state is transported to different countries, for making of glass.