Sal Ammoniacus Pharm. Lond. & Edinb. Sal ammoniac: a neutral salt; volatile in a moderate heat, but not in that of boiling water; formed by the coalition of volatile alkaline salt with marine acid. On mixing it with a fixt alkaline salt or calcareous earth, and exposing the mixture to the fire, its ingredients are disunited: the volatile alkali exhales, and may be collected in proper vessels (see the foregoing article): and the acid remains combined with the fixt alkali or earth, forming therewith the same compounds as if the pure marine acid had been poured upon them. Hence, in the preceding operations, where the volatile alkali of the sal ammoniac is separated by the intervention of fixt alkalies, the residuum, dissolved and crystallized, is found to be the same with regenerated sea salt; and when chalk or lime is used for the intermedium, the residuum affords calcareous marine salt: see Sal communis.

The other mineral acids form likewise am-moniacal salts with volatile alkali; and it is said, that one made with the vitriolic acid is often substituted to the true officinal one with the marine. - The most obvious character of ammoniacal salts in general is, their yielding a pungent urinous odour on being ground with a little quicklime. The marine sal ammoniac may be distinguished from those made with the other acids, by its emitting white fumes on dropping upon it some oil of vitriol; and by a solution of it in purified aquafortis being able to dissolve gold leaf or a mark made with gold on a touchstone. The nitrous sal ammoniac is distinguished, by its deflagrating or flaming when thrown into a red-hot vessel, dissolving in spirit of wine, and yielding red fumes with oil of vitriol. The vitriolic is distinguished by a solution of it rendering solution of chalk in aquafortis milky; and by its not being acted upon by oil of vitriol.

(a J Malouin, Chimie medcinale, i. 202. ii. 431.

Sal ammoniac has been hitherto prepared chiefly in Egypt: it is said, that the earth abounds there with marine salt; that grass and other vegetables are sensibly impregnated with this salt; that the dung of graminivorous quadrupeds is used as fuel, and the foot carefully collected; and that from this foot, sal ammoniac is extracted, by sublimation without addition. The salt is brought to us, sometimes in conical loaves, most commonly in large round cakes, convex on one side and concave on the other, appearing when broken of a needled texture, or composed of striae. running transversely and parallel to one another: the internal part is generally pure, and of an almost transparent whiteness; the outside for the most part foul and of a yellowish grey or blackish hue. It is purified, either by sublimation, with a gradual fire, in an earthen cucurbit having a blindhead adapted to it; or, perhaps more perfectly, by solution in water, filtration, and crystallization. It dissolves, in temperately warm weather, in about thrice its weight of water, and by the assistance of heat in a much smaller quantity; and crystallizes into long shining spicula, or thin fibrous plates like feathers. In sublimation, especially if the fire js hastily raised, it remarkably volatilizes many kinds of bodies, perhaps all those that are soluble by the marine acid.

This salt has a very sharp penetrating taste. It is a powerful attenuant and deobstruent, seeming to liquefy the animal juices almost like alkaline salts: Boerhaave observes that its liberal and continued use renders the blood so thin as to burst through the vessels, particularly those of the lungs and the urinary organs. In doses of half a dram or a dram, dissolved in water, if the patient is kept warm, it generally proves fudorific: by moderate exercise, or walking in the open air, its action is determined to the kidneys: in larger doses it loosens the belly. It has by some been held a secret for the cure of intermittents; and is undoubtedly, in many cases, as an aperient, an excellent assistant to the Peruvian bark, where that astringent drug by itself would produce dangerous obstruclions, or aggravate those already formed. This salt is employed likewise externally as an antiseptic, and in lotions and fomentations for cedematous tumours; as also in gargarifms, for inflammations of the tonsils, and for attenuating and dissolving thick mucus in the mouth and fauces. Saturated solutions of it are said to consume warts.