Origin

Ammoniac is the concrete juice of an umbelliferous plant, denominated Dorema Ammoniacum, six or seven feet in height, growing in Persia and Afghanistan. All parts of the plant contain a milky juice. At certain seasons, this exudes through punctures made in the stem, and hardens in the shape of tears, which are collected for use. But the drug is said also to be obtained by cutting off the top of the root, in the same manner as assafetida. it is exported from Bushire, and usually reaches Europe and this country through the ports of Hindostan.

Properties

Two varieties of the drug are found in commerce; one in tears, the other in mass. The tears are irregularly globular, from the size of a pin's head to that of a large chestnut, yellowish externally, hard and brittle when cold, and breaking with a smooth, shining, whitish fracture. The masses are irregular in form and size, presenting in their broken surface a mottled appearance, owing to the presence of the whitish tears, embedded in a substance of a darker colour and less homogeneous texture, and often full of impurities. Sometimes the masses are composed of agglutinated tears, with little or none of the solid pasty matter.

The smell of ammoniac is faint, but peculiar and disagreeable; the taste is bitterish, subacrid, slightly sweetish, and nauseous. When heated, it softens and becomes adhesive, but does not melt. it is inflammable.

Composition

Ammoniac is a gum-resin, consisting essentially of gum and resin, with a little volatile oil, to which it owes its odour. As its virtues reside in the oil and resin, they are extracted by alcohol. Rubbed up with water, the gum-resin forms a white milky emulsion, in which the resin and oil are held in suspension by the dissolved gum.

Medical Properties and Uses

Ammoniac was employed by the ancients. its properties and applications as a nervous stimulant and external irritant have been already considered (i. 604). With a very moderate excitant influence over the circulation and nervous system, it has the property of stimulating the secretions, and will occasionally act as an expectorant, diaphoretic, and diuretic, though in none of these respects is its action very decided. it has been said to possess emmenagogue properties, but these are very uncertain. in large doses, it often occasions a feeling of heat, weight, or uneasiness of the stomach, and not unfrequently acts on the bowels.

As an expectorant, it is employed chiefly in chronic cases of bronchitis, in which the secretion is either defective or in excess; and in which it probably operates also as a gentle stimulant and alterative. it has been thought to be specially useful in cases of this kind associated with asthmatic phenomena; and, from its properties as a nervous stimulant, it may do good in the obstinate coughs of hysterical patients. in consequence of its locally stimulant and somewhat laxative property, it may be used in cases of habitual constipation, with colicky pains and flatulence, connected with a feeble and torpid or insusceptible state of the alimentary mucous membrane; and, when this condition happens to be conjoined with a chronic cough, there is a double indication for its use.

Administration

The dose of ammoniac is from ten to thirty grains, to be repeated as other expectorants. it may be given in pill, or emulsion; but the latter form is preferable. it is often administered in conjunction with other expectorants, especially with squill, with which it is combined in the Compound Pills of Squill (Pilulae Scillae Compositae) of the Pharmacopoeias. (Seepage 678.)

Ammoniac mixture (Mistura Ammoniaci, U. S., Br.), sometimes called milk of ammoniac or lac ammoniaci, is made by simply rubbing two drachms of ammoniac with eight fluidounces of water. A tablespoonful is the medium dose.