GULFS, in heraldry, signifies the co lour red, which is expressed in engraving by perpendicular lines falling from the top of the escutcheon to the bottom.
GUM, a thick transparent tasteless fluid, which exudes occasionally from certain species of trees.. It is adhesive, and gradually hardens without losing its transparency. Gum is chiefly obtained from different species of the mimosa, par ticularly from M. nilotica,a native of Egypt and Arabia, which is known by the name of gum arable. The specific gravity of gum is about 1.4. It is not changed by expo sure to the air, but is deprived of its co lour by the action of the sun. zly heat it becomes soft, and is speedily reduced to the state of charcoal, which enters large ly into its composition. The constituent parts of gum are, carbon, hydrogen, and oxygen, with smaller proportions of ni trogen and lime. The oxygen Is much less in quantity than the saccharine mat ter. See SUGAR. The existence of lime and nitrogen in gum renders it essentially different from fecula and sugar, to which, in other respects, it bears a near relation; they, however, are able to undergo the vinous fermentation, which is not the case with gum. Gum readily dissolves in wa ter, and the solution, which is thick and adhesive, is known by the name of muci lage. It is soluble also in the vegetable acids. Sulphuric acid decomposes it, and converts it into water, acetic acid, and charcoal. With the assistance of heat, muriatic acid, and nitric acid, pro duce a similar effect. It is insoluble in alcohol and ether. Such are the chief properties of gum arabic. There are, besides phis, other gums, of which the principal is denominated tragacanth, from the astragalus tragacantha, a native of the island of Crete, which is in the form of vermicular masses ; it is less transparent and more adhesive than gum arabic, but by distillation it yields similar products. In our gardens and orchards we find, in good quantities, gum exuding from the cherry and plumb trees, which differs chiefly from gum arabic in being softer and more soluble. Gum, in a state of mucilage, exists in a number of plants, especially in the roots and leaves. It is most abundant in bulbous roots, and of these the hyacinth seems to contain the largest quantity. A pound of the bulbs of this root, when dried, yields four ounces of a powder, which, when mace rated in water, give a mucilage that acts well as a mordant for fixing the colours in calico-printing. Gum is used in medi cine, and is considered as a specific a gainst the strangury occasioned by blis ters; it constitutes, under particular forms, a nutritious food, and it is well known as an important article in the manufacture of our ink.
Gum resins, are certain substances that have long been used in medicine. They are all solid, generally brittle and opaque, have a strong smell, and a pungent and bitter taste. They consist chiefly of gum and resin, the proportions varying with the particular substance. They are never obtained by means of spontaneous exu dation, but are procured by wounding the •plants which contain them. The principal of the gum-resins are, 1. Ammo xi AC, which see. 2. Assafcetida, obtained from the fertila assafcetida, a plant found in Persia. The gum resin is extracted from the roots by cutting off the extre mities ; a milky juice flows out, which is dried in the sun. It is brought to Eu rope in masses ; its smell is very fcetict, and its taste acrid. It is partially soluble in water and alcohol. 3. Euphorbium, obtained from the euphorbia officinalis, a native of Ethiopia, by making incisions in the plant. It is brought from Africa in the form of tears, is soluble in alcohol. It has no smell ; after a time it communi cates a burning taste to the tongue. It is regarded as poisonous. 4. Getiserrox, which see. 5. GAMBOGE, which see. 6. Alyrrh, which is brought from the East Indies, in the form of tears, is light, brit tle, of a reddish colour, and has an unc tuous feel ; it is bitter and aromatic ; it is soluble in water and alcohol in slight de grees 7. Opoponax, obtained from the pastenaca opoponax, a perennial plant, which grows wild in the south of Europe. This is extracted by wounding the stock or root, and is known here in the form of round drops or tears, or in irregular masses of a reddish colour. It is bitter and acrid to the taste, and with a peculiar smell. It forms a milky solution with water, and yields an essential oil by dis tillation. 8. Sapagenum, supposed to be had from the ferula persica, and brought in large masses, or distinct tears, from Alexandria. It has a hot taste and disa greeable smell. It is moderately soluble in alcohol, but much more so in water.- By distillation it yields a foetid volatile oil. From some experiments made upon ipe cacuanha, it is thought to contain a gum resin. All the gum resins that have been analysed have been found to contain am monia.
GUN, a fire arm or weapon of offence, which forcibly discharges a ball, shot, or other offensive matter, through a cylin drical barrel, by means of gunpowder.— Gun is a general name, under which are included divers, or even most species of fire arms. They may be divided into great and small.
Great guns, called also by the general name cannons, make what we also call ordnance or artillery ; under which come the several sorts of cannon. See