Ammia´nus Marcelli´nus, a Roman historian, born at Antioch in Syria about 320, died about 390. He wrote in 31 books (of which the first 13 are lost) a history of the Cæsars, from Nerva to Valens, which was highly thought of by Gibbon for its fidelity. His MS. was printed for the first time at Rome in 1474.
Am´mon (often called Ammon-Ra, i.e. Ammon-Sun), an ancient Egyptian deity, one of the chief gods of the country, identified by the Greeks with their supreme god Zeus, while the Romans regarded him as the representative of Jupiter; represented as a ram, as a human being with a ram's head, ornamented with the solar disc, or simply with the horns of a ram. There was a celebrated temple of Ammon in the Oasis of Siwah in the Libyan desert.
Ammon, Oasis of. See Siwah.
Ammo´nia, an alkaline substance, which differs from the other alkalies by being gaseous, and is hence sometimes called the volatile alkali. It is a colourless pungent gas, composed of nitrogen and hydrogen; formula, NH3. It was first prepared by Priestley, who termed it alkaline air. He obtained it from sal-ammoniac by the action of lime, by which method it is yet generally prepared. It is used for many purposes, both in medicine and scientific chemistry; not, however, in the gaseous state, but frequently in solution in water, under the names of liquid ammonia, aqueous ammonia, or spirits of hartshorn. It is generally prepared from the ammoniacal liquor obtained as a by-product on distilling coal. Combined with acids, ammonia forms salts which are of immense value to agriculture. The well-known odour of farmyard manure is very largely due to the formation of ammonia during the rotting of the dung. Many animal substances, such as bones, clippings and shavings of horn, hoof, &c., and certain vegetable matters yield ammonia when heated. Sal-ammoniac is ammonium chloride.
Ammoni´ăcum, a gum-resinous exudation from an umbelliferous plant, the Dorēma ammoniăcum. It has a fetid smell, is inflammable, soluble in water and spirit of wine; used as an antispasmodic, stimulant, and expectorant in chronic catarrh, bronchitic affections, and asthma; also used for plasters.
Ammo´niaphone, an instrument, consisting of a metallic tube containing some substance saturated with ammonia, peroxide of hydrogen, and a few flavouring compounds, fitted with a mouthpiece to breathe through, which is said to render the voice strong, clear, rich, and ringing by the inhalation of the ammoniacal vapour. It was invented by Dr. Carter Moffat, and was suggested by the presence of ammonia in some quantity in the atmosphere of Italy—the country of fine singers.
Am´monites, a group of fossil cephalopods, now divided into a large number of genera, ranging from the Coal Measures (Texas) to the uppermost cretaceous strata. The ammonites differ from the nautili in having the tube connecting the chambers placed on the outer margin of the coiled shell, while the calcareous neck where it passes through the partitions is directed forwards. The partitions are much folded, producing markings like the fronds of ferns where they meet the inner wall of the shell. The name arises from confusion with a coiled gastropod, which was held to resemble the horns of the Egyptian deity Jupiter Ammon.
Am´monites, a Semitic race frequently mentioned in Scripture, descended from Ben-Ammi, the son of Lot (Gen. xix, 38), often spoken of in conjunction with the Moabites. A predatory and Bedouin race, they inhabited the desert country east of Gad, their chief city being Rabbath-Ammon (Philadelphia). Wars between the Israelites and the Ammonites were frequent; they were overcome by Jephthah, Saul, David, Uzziah, Jotham, &c. They appear to have existed as a distinct people in the time of Justin Martyr, but have subsequently become merged in the aggregate of nameless Arab tribes.