Lond. Ammoniae Murias, Dub. Murias Ammoniae, Edin. Hydrochlorate or Muriate of Ammonia.

Syn. Sel Ammoniac (F.), Salmaik (G.), Salmiaken (Dan. Swed.), Sale Am-moniaco (I), Sal Armoniaco (S.), Nosader (H.), Navacharum (Tarn.), Urmiena (Arab.), Nowshader (Pers.), Vayvagarra Loonoo (Cyng.), Nuosadur (Sans.)

This salt, which is a compound of muriatic acid and ammonia, is found as a product of volcanoesl; but the greater part of that which is employed in medicine and the arts is artificially prepared.

Hydrochlorate of ammonia was originally manufactured in Egypt, by sublimation from the soot of fuel, formed by the dung of phytivorous animals, kneaded with straw into clods, and dried in the sun. From this source all the European states were formerly supplied; but since the manufacture of it in Europe, the importation of Egyptian sal ammoniac has been discontinued. The process differs in different places.9

Bones, chopped into small pieces, and boiled in order to extract the marrow and fat, are distilled from an iron cylindrical still into a leaden receiver, cooled by a refrigeratory, which is its cover, and contains about four inches in depth of water. Six parts of impure alkaline liquor and five of foetid oil are thus procured; the oil is skimmed off, and the alkali mixed with pulverised gypsum. By double decomposition sulphate of ammonia and carbonate of lime are formed; the liquor which contains the former is then mixed with common salt (chloride of sodium); and thus, by a second decomposition, hydrochlorate of ammonia and sulphate of soda are formed in the liquor. This solution is clarified by subsidence and decantation; and by a skilfully managed evaporation in leaden boilers, the two salts are separated as they crystallize. The water of crystallization is then driven off from the hydrochlo-rate of ammonia, by exposing it to heat in a kind of oven; and the spongy, friable, ash-coloured mass, into which it changed, being put, while hot, into globular bottles, or glazed earthen jars furnished with a moveable perforated cover, the hydro-chlorate is sublimed by exposing them to a heat of 320° in iron pots filled with sand.

The cakes of salt produced, after being placed "for a day or two in a damp atmosphere," to soften their surface, and facilitate "the removal of any superficial impurities," are packed in casks for sale.

1 The eruption of Etna in 1811 afforded as much sal ammoniac as supplied all the manufactories and apothecaries' shops in Sicily. Annates de Mines tom. v. p. 135. It is exhaled, also, from the Solfatara of Pozzuola; from one of the great apertures of which it has been extracted for several years.

2 Aiken's Dictionary of Chymistry, art. Sal ammoniac.

The cakes of hydrochlorate of ammonia are hemispherical, about two inches thick; elastic; and when broken, are towards the convex surface white, striated, and opaque; but towards the concave have a more crystallized appearance, and are nearly semitransparent. This salt is also, sometimes, crystallized in conical masses, that are deliquescent, owing to the presence of muriate of lime, which renders it unfit for medicinal purposes.

The greater part of the sal ammoniac in the London market is made in the north of England; but an inferior sort is imported in chests from the East Indies.

Qualities.-This salt is inodorous; has a salt, somewhat bitterish, cool taste; very slightly attracts moisture from the air; and has a specific gravity of 1*450. It is ductile, and therefore not very easily pulverized. It requires 3.25 times its weight of water at 60°, and its own weight at 212°, to dissolve it; and during its solution a great reduction of temperature takes place. It is also soluble in 4 1/2 parts of alcohol. At a high temperature it sublimes without melting, and is unchanged. When dissolved in boiling-water, it forms, as the solution cools, in tetrahedral or in flaky plumose crystals. Its components are 31.5 per cent. of ammonia, and 68.5 of acid, independent of the water of crystallization; or 1 equiv. of acid = 36.42 + 1 ammonia = 17.15, making the equivalent 53.57. It combines unchanged with bichloride of mercury, and increases its solubility in water. The sulphuric and nitric acids unite with its alkali, and set free the muriatic acid. Potassa and its carbonate, carbonates of soda; lime, magnesia; the carbonate of baryta, lime, and carbonate of magnesia, combine with its acid, and set free the ammonia, which is rendered sensible by its odour.

Acetate of lead, when added to a solution of it, throws down a precipitate of muriate of lead: it is decomposed also by nitrate of silver, the base of which forms an insoluble compound with hydrochloric acid, hence these salts are incompatible in prescriptions with hydrochlorate of ammonia; but it may be combined in solution with the sulphate of copper, or of zinc.

Medical properties and uses.-This salt was formerly considered a powerful aperient and attenuant of viscid humours, acting as a diaphoretic, diuretic, purgative, and emetic, according to the mode of exhibition, or the extent of the dose; but it is now scarcely ever ordered as an internal medicine. Externally, it is advantageously employed, when mixed with its weight of nitre, and dissolved in eight parts of water, on account of the cold produced during its solution, to abate the pain and heat of inflammation and to allay violent headach. It is useful, also, in cases of mania, plethoric apoplexy, and injuries of the head, and to assist in the reduction of hernial tumours; but when it is employed for this purpose, the solution should be made immediately before applying it to the affected part. It is also a useful application in dropsy of the thyroid gland.1 Owing to its stimulant qualities, it forms an excellent discutient, when dissolved in the proportion of j. of the salt, in f ix. of water with f j. of alcohol, in indolent tumours, gangrene, scabies, and chilblains: in which cases it is better not to be too recently dissolved; and as a gargle, it is occasionally useful in cynanche. A plaster formed with 3ss. of the muriate, j. of soap, and 3 ij. of lead plaster, is highly recommended by Dr. Paris 2 as a rubefacient in pulmonary affections. Its efficacy depends on the extrication of ammonia by the decomposition of the hydrochlorate, on which account it should be renewed every twenty-four hours.

Officinal preparations.-Ammoniae sesquicarbonas, L. Ammoniae subcarbonas, E. Ammoniae carbonas, D. Liquor Ammoniae For-tior, L. Liquor Ammoniae, L. Aqua Ammoniae, E. D. Hydrarg. Ammonio-chloridum, L. Ferri Ammonio-chloridum, L. Ferrum Ammoniatum, E. Alcohol Ammoniatum, E. Spiritus Ammoniae, L. D. Spiritus Ammoniae aromaticus, L. Aqua cupri ammoniati, D. Hydro-sulphuretum Ammoniae, D. Ammoniae bicarbonas, D.