AMMONIA (NH 3 ), sometimes called the Volatile alkali, or Alkaline air, was known to the alchemists in aqueous solution. Priestley first separated it in the gaseous state in 1774. Scheele in 1777 discovered that it contained nitrogen, and its true composition was ascertained by Berthollet about 1785. Ammonia occurs in the atmosphere as carbonate and nitrate, in sea-water, and in many mineral springs. Iron ores and many clayey soils contain it in small quantity, and sal-ammoniac and •ammonia alum are found as minerals in volcanic districts. Carbonate of ammonia is obtained in large quantity by the putrefaction of the urine of animals, or the dry distillation of animal matter. Ammonia is obtained from its salts by the acting of slaked lime or solutions of potash or soda, and is freed from water by passing over quicklime or solid potash, and finally collected over mercury. It is a colourless gas, of a pungent smell, and alkaline taste and reaction. It does not support combustion or respiration, and is feebly combustible. It is remarkably soluble in water, 1 volume dissolving nearly 700 of the gas. It may by the action of a low temperature and great pressure be changed into the liquid or solid state. The gas is easily decomposed into its elements by a succession of electric sparks, or by passing it over red-hot iron or platinum wire. The aqueous solution in presence of finely divided platinum and atmospheric air is converted into nitrite of ammonia; and conversely, the oxides of nitrogen, mixed with excess of hydrogen and passed over platinised asbestos, are changed into ammonia. Nitrogen and hydrogen have not by any process been induced to combine so as to yield this compound directly, unless in very small quantity. For theoretical relations of ammonia, salts, <fcc., see ...Chemistry.
AMMONIAC, Sal (NH 4 C1), the earliest known salt of ammonia, now named chloride of ammonium, formerly much used in dyeing and metallurgic operations.
The name Hammoniacus sal occurs in Pliny (Nat. Hist, xxxi. 39), who relates that it was applied to a kind of fossil salt found below the sand, in a district of Cyrenaica. It was similar in appearance to the alumen scissile, and had a disagreeable taste, but was useful in medicine. The general opinion is, that the sal-ammoniac of the ancients was the same as that of the moderns; but the imperfect description of Pliny is far from being sufficient to decide the point. The native sal-ammoniac of Bucharia, described by Model and Karsten, and analysed by Klaproth, has no resemblance to the salt described by Pliny. The same remark applies to the sal-ammoniac of volcanoes. Dioscorides (v. 126), in mentioning sal-ammoniac, makes use of a phrase quite irreconcilable with the description of Pliny, and rather applicable to rock-salt than to our salammoniac. Sal-ammoniac, he says, is peculiarly prized if it can be easily split into rectangular fragments. Finally, we have no proof whatever that sal-ammoniac occurs at present, either near the temple of Jupiter Ammon, or in any part of Cyrenaica. These circumstances induce us to conclude that the term sal-ammoniac was applied as indefinitely by the ancients as most of their other chemical terms. It may have been given to the same salt which is known to the moderns by that appellation, but was not confined to it.
Some derive the name sal-ammoniac from Jupiter Ammon, near whose temple it is alleged to have been found; others, from a district of Cyrenaica called Ammonia. Pliny’s derivation is from the sand (α∕qu,os) in which it occurred....
Whether our sal-ammoniac was known to the ancients or not, there can be no doubt that it was well known to the alchemists as early as the 13 th century. Albertus Magnus, in his treatise De Alchymia, informs us that there were two kinds of sal-ammoniac, a natural and an artificial. The natural was sometimes white, and sometimes red; the artificial was more useful to the chemist. He does not tell us how it was prepared, but he describes the method of subliming it, which can leave no doubt that it was real sal-ammoniac. In the Opera Mineralia of Isaac Hollandus the elder, there is likewise a description of the mode of subliming sal-ammoniac. Basil Valentine, in his Currus Triumphalis Antimonii, describes some of the peculiar properties of sal-ammoniac in, if possible, a still less equivocal manner.
Egypt is the country where sal-ammoniac was first manufactured, and from which Europe for many years was supplied with it. This commerce was first carried on by the Venetians, and afterwards by the Dutch. Nothing was known about the method employed by the Egyptians till the year 1719. In 1716 the younger Geoffroy read a paper to the French Academy, showing that sal-ammoniac must be formed by sublimation; but his opinion was opposed so violently by Homberg and Lemery, that the paper was not printed. In 1719 Μ. Lemaire, the French consul at Cairo, sent the Academy an account of the mode of manufacturing sal-ammoniac in Egypt. The salt, it appeared, was obtained by simple sublimation from soot. In the year 1760 Linnaeus communicated to the Royal Society a correct detail of the whole process, which he had received from Dr Hasselquist, who had travelled in that country as a naturalist. This account is published in the 51st volume of the Philosophical Transactions, 1760, p. 504. Almost the only fuel used in Egypt is the dung of cattle. The dung of black cattle, horses, sheep, goats, <tc., which contains the sal-ammoniac ready formed, is collected during the first four months of the year, when the animals feed on the spring grass, a kind of clover. It is dried, and sold to the common people as fuel. The soot from this fuel is carefully collected and sold to the sal-ammoniac makers, who work only during the months of March and April, for it is only at that season of the year that the dung is fit for their purpose.
The composition of this salt seems to have been first discovered by Tournefort in 1700. The experiments of the younger Geoffroy in 1716 and 1723 were still more decisive, and those of Duhamel, in 1735, left no doubt upon the subject. Dr Thomson first pointed out a process by synthesis, which has the advantage of being very simple, and at the same time rigidly accurate, resulting from his observation that when muriatic gas and ammoniacal gas, both as dry as possible, are brought in contact with each other, they always combine in equal volumes.
The first attempt to manufacture sal-ammoniac in Europe was made, about the beginning of the 18th century, by Mr Goodwin, a chemist of London, who appears to have used the mother ley of common salt and putrid urine as ingredients. The first successful manufacture of salammoniac in this country was established in Edinburgh by Dr Hutton and Mr Davy, about the year 1760. It was first manufactured in France about the same time by Baumé. Manufactories of it were afterwards established in Germany, Holland, and Flanders.
Chloride of ammonia is now manufactured in large quantity from the crude carbonate of ammonia obtained in gasworks, or from the destructive distillation of animal matter. This salt is changed into chloride by the addition of hydrochloric acid or the mother liquor of salt-works, called bittern, containing the chlorides of calcium and magnesium. When hydrochloric acid is not easily got for neutralisation, the crude gas liquor is transformed into sulphate, and this is mixed with an equivalent quantity of common salt. During the subsequent evaporation the sulphate of soda separates in hard granular crystals, which are apt to adhere to the sides of the boiler. The liquor is agitated to prevent this adhesion taking place, and assist in the separation of the sulphate of soda. The sulphate of soda is removed by drainers as it is formed, and the mother liquor boiled up to the crystallising point, and run off into coolers. The crystals of impure muriate of ammonia are dried carefully and subsequently sublimed.
Sal-ammoniac occurs usually in the form of a hard, white cake, opaque, or only slightly translucent. Its taste is cooling, saline, and rather disagreeable. It dissolves in 2∙72 parts of water at 18° *7 C. with great reduction of temperature, and in about an equal weight of water at the boiling-point. The feathery crystals it forms are found on microscopic examination > to be masses of cubes or octahedrons; their specific gravity is about 1’5. When exposed to a moist atmosphere, the salt gradually absorbs water, and deliquesces, though very slowly, becoming slightly acid. When heated, it sublimes unaltered in a white smoke, having a peculiar smell, very characteristic of sal-ammoniac. If a cold body be presented to this smoke, the sal-ammoniac condenses on it, and forms a white crust. When thus sublimed, it has the property of carrying along with it various bodies, which, when heated by themselves, are perfectly fixed.
Tor the other ammoniacal salts see Chemistry.
AMMONIACUM, or Ammoniac, a gum-resinous exuda∙ tion from the stem of a perennial herb (I)orema ammonia· cum) belonging to the natural order Ùmbelliferae. The plant grows to the height of 8 or 9 feet, and its whole stem is pervaded with a milky juice, which oozes out on an incision being made at any part. This juice quickly hardens into round tears, forming the “tear ammonia-cum” of commerce. Lump ammoniacum, the other form, in which the substance is imported, consists of aggregations of tears, frequently incorporating large quantities of the fruits of the plant itself, as well as other foreign bodies. In order to free lump ammoniacum from these impurities, it has to be melted and strained, operations which depreciate its therapeutical value. Ammoniacum has a faintly foetid unpleasant odour, which becomes more distinct on heating; externally it possesses a reddish yellow appearance, and when the tears or lumps are freshly fractured they exhibit an opalescent lustre. It is chiefly collected in the province of Irak in Persia; but some quantity is also produced in the Punjab, and comes to the European market by way of Bombay. Its composition, according to Hagen, is—resin, 68'6; gum, 19’3; gluten, 5'4; volatile oil and water, 2 , 8; extractive, &c., 3 ’ 9. Ammoniacum is closely related to assafoetida, not only in the plant yielding it, but also in its therapeutical effects. It may be used as a substitute for assafoetida, although, containing a much smaller proportion of volatile oil, its effect is less powerful. Internally it is used in conjunction with squills in bronchial affections; and in asthma and chronic colds it is found useful It is, however, more used externally in the form of plasters, as a discutient or resolvent application in indolent tumours, ...affections of the joints, &c.
African ammoniacum is a totally different substance, though often confounded with the real gum-resin, which is produced only in the East. It is the product of an unknown plant growing in North Africa, and occasionally shipped to our markets from Marocco. It is a dark-coloured gum-resin, possessed of a very weak odour and a persistent acrid taste. A considerable commerce in it is carried on between Mogador and Alexandria, where it is in demand for purposes of fumigation.
the disciples of Ammonius Saccas, of the Alexandrian school. His character was so equivocal, that it is disputed whether he was a Heathen or a Christian. Mr. Milner calls him “a Pagan Christian,” who imagined “that all religions, vulgar and philosophical, Grecian and barbarous, Jewish and Gentile, meant the same thing in substance. He undertook, by allegorizing and subtilizing various fables and systems, to make up a coalition of all sects and religions; and from his labours, continued by his disciples,--some of whose works still remain,--his followers were taught to look on Jew, philosopher, vulgar, Pagan, and Christian, as all of the same creed,” and worshippers of the same God, whether denominated “Jehovah, Jove, or Lord.”
