in the materia medica. Opopbalsam, or balm of Gilead; a resinous juice, obtained from an evergreen tree, or shrub, growing spontaneously in Arabia. The best sort, which naturally exudes from the plant, is scarce known to Europe; and the inferior kinds, said to be extracted by lightly boiling the leaves and branches in water, are very rarely seen among us. The true opobalsam, according to Alpinus, is at first turbid and white; of a very strong, pungent smell, like that of turpentine, but much sweeter; and of a bitter, acrid, astringent taste; upon being kept for some times it becomes thin, limpid, light, of a greenish hue; then of a gold yellow; and at length of the colour of honey: after this it grows thick like turpentine, and loses much of its fragrance. This balsam is of great esteem in the eastern countries, both as a medicine, and as an odoriferous unguent and cosmetic. Its great scarcity has prevented its coming into use among us; in the mithridate and theriaca, which it is directed as an ingredient in, the London college allows the expressed oil of nutmegs as a succedaneum to it.