Ammoniacum (U. S. P.)—Ammoniac.

"A gum resin obtained from Dorema Ammoniacum, Don"—(U. S. P.).
Nat. Ord.—Umbelliferae.
COMMON NAMES: Gum ammoniac, Gummi-resina ammoniacum.

Botanical Source.—The Dorema Ammoniacum is a glaucous green plant resembling opopanax. Its root is perennial and large, from which arise smooth stems, 8 or 10 feet high, and over 1 inch in diameter at the base, having petiolate, somewhat bi-pinnate leaves, about 2 feet long; the pinnae are in 3 pairs, the leaflets are inciso-pinnatifid, with oblong, mucronulate, entire, or straightly-lobed segments, from 1 to 5 inches long, and ½ inch to 2 inches broad. The petiole is downy, very large, and sheathing at the base. The umbels are proliferous and racemose, being composed of partial, globose umbels, on short stalks, often arranged in a spiked manner. The flowers are white, sessile, and immersed in wool. The fruit, which is elliptical and compressed, is also buried in wool, and surrounded by a broad, flat edge (L).

History.—From a want of correct knowledge of the plant furnishing this gum-resin, it was formerly considered a Ferula, but specimens of the Persian plant having been investigated by Don, he ascertained that, although it was somewhat related to this genus, yet it differed from it in several characters; he therefore gave to it its present name. The plant grows on arid, exposed situations in several parts of Persia, and in the course of the summer it is replete with a lacteous, gelatinous juice, which is readily obtained. It prefers a soil abounding in silica. Mr. Jackson says: "It is remarkable that neither bird nor beast is seen where this plant grows, the vulture only excepted. It is, however, attacked by a beetle, having a long horn proceeding from its nose, with which it perforates the plant and makes the incisions whence the gum oozes out." Colonel Johnson states that "in the month of May, while the plant is soft, an insect of the beetle kind begins to puncture the stem in every direction with his proboscis," etc. Captain Hart gives a similar account. But Fontanier asserts that it flows naturally, and is gathered in June. It is still supposed, however, to be sometimes furnished by other and dissimilar plants of Asiatic as well as African growth. It is asserted that in some places it is collected after the manner of obtaining asafoetida. Around the plant, imbedded in the soil, are often formed tears of the gum which have either exuded into the ground from the root, or have dropped from the punctured stems. From the fibrous root-crown an inferior quality of gum is made to exude, which is dark in color. Gum ammoniac is mostly gathered by the peasantry in July. Cake ammoniac consists of tears of the gum admixed with the inferior brown exudation from the stem-base.

Description.—Gum ammoniac is not a gum proper, but a gum-resin; it is met with in tears and in lump. The tears vary in size from that of a small pea to that of a walnut. The lump ammoniac varies in appearance according to its quality. The best kind is composed chiefly of tears agglutinated together, though foreign impurities are frequently present. Ammoniac does not melt, but softens by heat, even the warmth of the hand; at a red heat it burns with a white flame. It may be partly dissolved by water, forming a white emulsion, which, upon standing, precipitates a resinous portion, leaving the supernatant liquid clear. Alcohol dissolves more than one-half, the remainder being a resin, insoluble in this liquor; and the soluble white resin is precipitated by the addition of water to the alcoholic solution. Ether dissolves resin and volatile oil, leaving the gum. Vinegar forms a smooth, uniform emulsion with it, but does not dissolve it. Mr. Hatchett found it soluble in alkalies. The U. S. Pharmacopoeia thus describes ammoniacum: "In roundish tears, from 2 to 6 Mm. (1/12 to ¼ inch) or more in diameter; externally pale yellowish-brown, internally milk-white, brittle when cold, and breaking with a flat, conchoidal, and waxy fracture; or the tears are superficially united into irregular masses without any intervening, dark-colored substance. It has a peculiar odor, and a bitter, acrid, and nauseous taste. When triturated with water, it readily yields a milk-white emulsion"—(U. S. P.).

Chemical Composition.—Ammoniac has been analyzed by Braconnot; Bucholz, Hagen, Hirschsohn, Plugge, and others, and appears to consist of a large proportion of resin, with gum, bassorin, volatile oil, and water. The resin of ammoniac, amounting to 70 per cent, or less, is reddish or yellow, transparent, tasteless, but having the odor of the gum-resin; is brittle, softens in the hand, melts at 54.4° C. (130° F.), and is soluble in alcohol, and in excess of carbon disulphide. Ether separates it into an insoluble resin, and a resin soluble in sulphuric acid, and fixed and volatile oils. Alkalies form a cloudy solution. Nitric acid converts it into a yellow bitter matter, soluble in hot alcohol and water, and which will dye silk a fine yellow color, without being affected by chlorine. The gum is reddish-yellow, transparent, brittle, somewhat bitter, soluble in water, from which it is precipitated by subacetate of lead, and is converted into mucic, malic, oxalic, etc., acids, by the action of nitric acid. The oil, which may be obtained by distillation of the gum-resin with water, is transparent, colorless, and lighter than water. It is yielded to the extent of ¼ to ⅓ per cent, has a specific gravity of 0.891 at 15° C. (59° F.), and boils between 250° and 290° C. (482° and 554° F.), (Schimmel & Co., Semi-Annual Report, Oct., 1893). The oil has dextrogyrate properties (Pharmacographia). Hlasiwetz and Barth (1864), obtained oxalic acid, resorcin, and a fatty acid of a volatile nature by fusing the gum-resin with caustic potash. It differs chemically from most of the allied gum-resins, in not yielding umbelliferon upon dry distillation. Neither does the drug contain sulphur.

Action, Medical Uses, and Dosage.—Gum ammoniac possesses stimulant, antispasmodic, and expectorant properties, and is said to purge in inordinate doses, as well as to produce vomiting, colic, and cutaneous eruptions. It has been found especially useful in chronic affections of the respiratory organs, especially among the aged, or those in whom the expectoration is scanty, as in cough, asthma, etc., and has likewise been found advantageous in profuse mucous discharges, the result of weakness of the parts involved, as in bronchitis or laryngitis, catarrh, leucorrhoea, etc. It has also been advised in hysteria, but is inferior to some other of the fetid gum-resins, as asafoetida. Ammoniacum may be of service in small doses, in the headache resulting from disease of the frontal sinuses, in affections of the optic nerve, in catarrhal affections of the throat, nasal passages, eyes, ears and stomach, mucous diarrhoea, and in pains in the limbs accompanying disease of more or less of the mucous tissues generally. Applied externally in the form of plaster, it irritates the skin, frequently producing a papular eruption; and has been employed beneficially in this way, as a resolvent, to indolent buboes, white swelling, tumor of the joints, chronic glandular enlargement, and other indolent swellings. The dose is from 1 to 30 grains, in pill or in emulsion.

Related Species and Gum-Resins.Dorema Aucheri, Boissier. Western Persia. This species is thought to furnish a portion of the gum ammoniac of commerce. The plant is known in the Kurdish vernacular as Zuh.

Dorema robustum, Loftus. Western Persia. Yields a gum unlike that from Dorema Ammoniacum, Don (Pharmacographia).

Ferula tingitana, Linné. North Africa and extreme West Asia. It is known in Morocco as Kelth, and its gum by the name Fasay. The latter is generally known, however, as African ammoniac. The gum differs from true gum ammoniac in having a comparatively weak odor, and in yielding umbelliferon (Hirschsohn). A peculiar acid, having the formula C10H10O6, not present in the true gum, was obtained by fusing the Moroccan gum with caustic potash (Goldschmiedt). As with the true gum, resorcin was obtained by fusion with caustic potash. African ammoniacum occurs in dense, large, dark masses, formed by the agglutination of whitish, fawn-colored, or light-greenish tears, some specimens containing a considerable amount of foreign admixtures. It has a persistent, faintly-acrid taste, and is principally used by the Mahometans as incense.

Opopanax Chironium, Koch. Southern Europe, along the Mediterranean Sea. This plant is supposed to be the source of a rare and costly gum-resin known as Opopanax (see Opopanax).

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.