Lond. Edin. Ammoniacum GUMMI,Dub.

Ammoniac.

Syn. Gomme Ammoniaque (F.), Ammoniak (G.), Gomma Ammoniaco (I.), Goma Amoniaco (S.), Ushokor Feshook (Arab.), Semughbilshereen (Pers.).

The plant which yields this gum-resin is a native of Persia; it has at length been brought home by Colonel Wright, and described by Mr. David Don, under the name Dorema ammoniacum. The Dorema is now admitted as the true source of the drug.

1 The Hottentots employ a decoction of the fresh leaves as a vulnerary,- Burckell's Travels in Africa,

Mr. Jackson, in his account of Morocco, informs us, that the ammoniacum plant, which in the Arabic is named feshook, resembles the fennel1, is ten feet in height, and one inch thick in the thickest part of the stem; and Colonel Johnson describes a plant as that yielding the ammoniacum, which appears to be the same as the feshook. The feshook grows at El-araiche and M'Sharrah Rumellah; and neither bird nor beast is seen near the spot; but it is attacked by a horned beetle, which perforates the stem with its horn, and the juice runs out at the wound. It rises about six feet in height; some of the stems are dark coloured, others of a light green, and tinged with lake-colour near the joints. The flowers are extremely minute, and congregated in small capitals : each flower, when examined by the microscope, is found to consist of five petals, curled inwards, with a kidney-shaped anther. The Dorema, says Mr. Don, is not unlike opoponax;. but it is distinguished from opoponax, and also from ferula, by a large, cup-shaped, epigynous disk, completely sessile flowers, and solitary resiniferous canals. It is a robust plant, upwards of seven feet in height, and four inches in circumference at the lower part of the stem, of a glaucous colour, with a perennial root, and clothed with glandular pubescence.

The leaves are large, petiolate, sub-bipinnate, with subtrijugate pinnae: the lower leaflets are distinct, the superior confluent, incisopinnatifid, with oblong, mucronate, entire segments, rarely sublobate, coriaceous and veined on the under disk, supported on ribbed pubescent petioles, with the base greatly dilated, subvaginant, and stipulaceous. The flowers are produced on proliferous racemose umbels, supported on globose umbellules, with round, woolly peduncles. There is neither involucrum nor involucel. The flowers are sessile. The calyx is five-toothed at the margin, the teeth being small, ovate, acute, membranaceous. The petals are five, ovate, and acuminately inflex. The stamens are five, quickly cadu-cuous; the filaments are flattened, and dilated at the base: the anthers are incumbent and bilocular, with loculi longitudinally dehiscent. The ovaria are roundish, with full, fleshy, cyathiform, plaited sublobulate segments. The styles are flattened, slightly channelled, with a dilated base. The stigmata are trunketed. The fruit is elliptical, greatly compressed at the back, with a flattened margin, and a broad cincture.2 The plant is called Oshac by the Persians: it is perennial, and grows wild between Yerdekaust and Kumisha, in the province of Irauk, exposed to an ardent sun.

When the plant has attained perfection, it is pierced by innumerable beetles; the ammoniacum exudes, and when dry it is picked off. The ammoniacum, besides exuding from these punctures, is procured by incisions also, and allowed to drop on the ground, where it hardens by the air and sun; on which account that from Barbary is mixed with a red earth, and is not saleable in the London market. The best ammoniacum is brought from the East Indies, packed in cases and chests. It is in large masses, composed of small round fragments or tears; or in separate dry tears, which is generally considered a sign of its goodness.

1 Both Dioscorides and Pliny describe ammoniacum as the juice of a species of ferula growing in Libya Dioscor. 1. iii. c. 98. Plin. 1. xii. c. 23.

2 Linn. Trans, vol. xvi. p. 605. Merat and De Lens have published some notices of the plant, in the Dict. Universel de Matiere Medicate, 1829 : and an account of it is also contained in Trans, of the Med. Soc. of Calcutta, vol. i.

Qualities.-Ammoniacum has a peculiar faint but not ungrateful smell; and a bitter, nauseous, sweet taste. The tears are yellow on the outside, and white within; brittle, and break with a vitreous fracture. Their specific gravity is 1.207. Ammoniacum is adhesive in the warm hand, softens by heat, but does not melt; and is partially soluble in water, alcohol, ether, solutions of alkalies, and vinegar. When triturated with water the solution is milky, but after some time it lets fall a resinous matter, which is the part of the ammoniacum that is taken up by ether and alcohol. Water or alcohol, when distilled off ammoniacum, brings over nothing from it. According to the analysis of Braconnot, it is composed of 70.0 parts of resin, 18.4 gum, 4.4 glutinous matter, and 6.0 water, in 100.0 parts; 1.2 parts being lost in the analysis.1 I find that sulphuric ether takes up six grains in ten of ammoniacum, and, when evaporated, leaves a yellowish white resin 2, which is long of hardening, and is insipid, although it possesses the odour of the gum-resin: the taste resides in the gum, which in other respects possesses the properties of acacia gum.

Water, therefore, is the proper menstruum for ammoniacum.

Medical properties and uses.-Ammoniacum is a stimulating-expectorant, deobstruent, and antispasmodic; and is in large doses purgative. Externally it is discutient and resolvent. It is prescribed with advantage in asthma, chronic catarrh, and some other pulmonary affections; but, on account of its stimulating properties, its use must be avoided where any inflammatory action of the chest is going forward. As a deobstruent it is useful in visceral obstructions, hysteria, and chlorosis; and in that peculiar state of the bowels often accompanying hypochondriasis and dyspepsia, in which there is an almost constant degree of colic, particularly after taking food, and which appears to arise from a viscid mucus lodged in the intestines, a combination of ammoniacum and rhubarb is singularly efficacious. As an antispasmodic, Cullen properly considers it the least powerful of the foetid gum resins. It may be combined with tartarized antimony, squills, assafoetida, and ipecacuanha, to promote its expectorant powers; and with myrrh, iron, and bitters, when its deobstruent properties are required. It is given either in substance, or diffused in water in the form of emulsion.

Externally, it is applied under the form of plaster to scirrhous tumours and white swellings of the joints. (See Preparations and Compositions.)

1 Annates de Chim. lxviii. 69. Thomson's Chymistry, v. 143.

2 Nitric acid converts this resin into a yellow resino-bitter, which imparts a permanent yellow colour to silk.

The dose of ammoniacum is from grs. x. to grs. xxx.

Officinal preparations.-Mistura Ammoniaca, L .D. Emplastrum Ammoniaci, L. Emplastrum Ammoniaci cum Hydrargyro, L. Emplastrum Gummosum, E. Piluke Scillae compositae, L. E.