Glass-wort: A genus of the digynia order, belonging to the pentandria clas of plants; and in the natural method ranking under the 12th order, Holaraceae. The calyx is pentaphyllous; there is no corolla; the capsule is monoecious, with a screwed seed.

The species are, 1. The kali, which grows naturally in the salt marshes in divers parts of England. It is an annual plant, which rises above five or six inches high, sending out many side branches, which spread on every side, garnished with short awl-shaped leaves; which are fleathy, and terminate in acute spines. The flowers are produced from the side of the branches, to which they fit close, and are encompassed by short prickly leaves; they are small, and of an herbaceous colour. The seeds are wrapped up in the empalement of the flower, and ripe in autumn; soon after which the plant decays. 2. The tragus grows naturally on the sandy shores of the south of France, Spain, and Italy. This is also an annual plant, which sends out many diffused stalks, garnished with linear leaves an inch long, ending with sharp spines. The flowers come out from the side of the stalks in the same manner as those of the former; their empalements are blunt, and not so closely encompassed with leaves as those of the other. 3. The soda, rises with herbaceous stalks near three feet high, spreading wide. The leaves on the principal stalk, and those on the lower part of the branches, are long, slender, and have no spines; those on the upper part of the stalk and branches are slender, short, and crooked. At the base of the leaves are produced the flowers, which are small, and hardly perceptible; the empalement of the flower afterwards encompasses the capsule, which contains one coiled seed. 4. The vermiculata grows naturally in Spain. This hath shrubby perennial stalks, which rise three or four feet high, sending out many side-branches, garnished with fleathy, oval, acute-pointed leaves, coming out in clutters from the side of the branches; they are hoary, and have stiff prickles. The flowers are produced from between the leaves toward the ends of the branches; they are so small as scarce to be discerned, unless they are closely viewed. The seeds are like those of the other kinds. 5. The rosacea grows naturally in Tartary. This is an annual plant, whose stalks are herbaceous, and seldom rise more than five or six inches high. The leaves are awl-shaped, ending in acute points; the empalements of the flowers spread open: the flowers are small, and of a rose colour, but soon fade: the seeds are like those of the other sorts.

All the sorts of glasswort 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.