gaseous by caloric, in which form only it is in a state of purity, though the word is commonly applied to a solution of the gas in water, with which it readily combines, forming the liquid ammonia of the shops.

AMMONIAC. The plant producing this concrete, gummy, resinous juice, is said to grow in Nubia, Abyssinia, and the interior parts of Egypt. It has been supposed a species of the ferula, from another species of which asafoetida is obtained.

AMMONIAC, SAL, a volatile salt, of which vast quantities are thrown out by Mount Etna. The salammoniac now used in the shops, is artificial. When pure, this salt promotes perspiration.

AMPHIBIA. Amphibious animals or those which are capable of existing in two distinct elements as air and water. In zoology, the third class in the Linnæan system. The following is its classical character: heart, one auricle, one ventricle; blood, cold and red: jaws incumbent; organs of sense, tongue, nostrils, eyes, ears; covering, a naked skin; supporters various, in some none: creep in warm places and hiss.

They were formerly divided into four orders, nantes, and meantes, constituting the third and fourth these have since been removed into the first two orders, which now embrace the entire class, and are denominated; 1. reptilia, reptiles: 2. serpentes, serpents: of which the first have feet, and flat naked ears without auricles; the last have no feet; eggs connected in a chain.

These last are cast upon the earth naked, without limbs, exposed to every injury; but frequently armed with a mortal venom, contained in tubular fangs, resembling teeth, placed without the upper

jaw, protruded, or retracted at pleasure, and surrounded with a glandular vesicle, by which this fatal fluid is secreted. But lest this tribe should too much encroach upon the limits of other animal life, the benevolent author of nature has armed about a fifth part only of it in this deadly manner; while in order to inspire other animals with a suspicion sufficiently extensive, he has ordained that all of them should cast their skins, as a mark of the class to which they belong. The jaws are dilatable and not articulate; and the oesophagus so lax, that they can swallow, without mastication, an animal twice or thrice as large as the neck of the deglutient serpent; the colour is variable, and changes according to season, age, or mode of living; and is frequently converted to another in the dead body; tongue filiform, bifid: skin reticulate. The term amphibious is sometimes also extended to men, who have the faculty of living a long time under water.

We have divers instances of such amphibious men; the most remarkable is of a Sicilian, named the Fish-Colas. Kircher relates, that by a long habitude from his youth, he had so accustomed himself to live in water, that his nature seemed to be quite altered; so that he lived rather after the manner of a fish than a man, A Calabrian monk at Madrid laid claim to this kind of amphibious capacity, making an offer to the king of Spain to continue twice twenty-four hours under water, without ever coming up to take breath,

AMPHICTYONS, in Grecian antiquity, an assembly composed of deputies from the different states of Greece; and resembling, in some measure, the

diet of the German empire. They decided all pub lic differences, and disputes between any of the cities of Greece; but before they entered on business, they jointly sacrificed an ox cut into small pieces, as a symbol of their union. Their determinations were received with the greatest veneration, and even held sacred and inviolable.

AMPHITHEATRE, among the remains of antiquity, a building, in which all the spectators, by being ranged in a circular form, had equally open view of the show. These shows were generally of a barbarous nature, like the modern bull-fights in Spain, cock-fighting in England, and leopard-baiting at Calcutta, or Bengal.

AMPHION, in fabulous history, the son of Jupiter and Antiope: he played so well on the lyre, that the rocks were said to follow him, and the stones moved by his harmony, ranged themselves in order, and formed the walls of Thebes. He married Niobe, whose insult to Diana occasioned the loss of their children; when the unhappy father, filled with despair, attempted to destroy the temple of Apollo, but was punished by the loss of his sight and skill, and cast into the infernal regions.

The fable of Amphion's moving stones and raising the walls of Thebes by his harmony, has been explained by supposing that he persuaded, by his eloquence, a wild and uncivilized people to unite together and build a town to protect themselves against the attacks of their enemies.

AMPLIFICATION, in rhetoric, part of a discourse or speech, wherein a crime is aggravated, a praise or commendation heightened, or a narration enlarged, by an enumeration of circumstances, so as to ex

cite the proper emotions in the souls of the auditors. Such is the passage in Virgil, where instead of saying merely that Turnus died, he amplifies the circumstances of his death.~

-Ast illi solvuntur frigore membra,

Vitaque cum gemitu fugit indignata sub umbras. The masters of eloquence make amplification to be the soul of discourse.

"

AMPLITUDE, in astronomy, an arch of the horizon intercepted between the east or west point and the centre of the sun, or a planet, at its rising or setting; and so is either north and south, or ortive and occasive. The amplitude of a heavenly body may be found trigonometrically by saying, as the cosine of the latitude, to radius, so is the sine of the declination of the body, to the sine of its amplitude.

Amplitude Magnetical, is an arch of the horizon contained between the centre of the celestial body when rising or setting, and the east or west point of the compass. It is always equal to the difference between the true amplitude and the variation of the compass.

AMULET, a charm, or preservative against diseases or inchantment. Amulets were made of stone, metal, vegetables, animals, or any thing that the imagination suggested. In some cases, they consisted of words or letters, ranged in a particular order, engraved upon wood, and fixed on some part of the body; in others, they were neither written nor engraved, but prepared with many superstitious ceremonies, and particular regard to the influence of the stars: among the Arabians, this latter species of amulet is called a talisman. It need not be added, that amulets have fallen into discredit.

ANABAPTISTS, see BAPTISTS.

ANACHRONISM, an error with respect to chronology whereby an event is placed earlier than it really happened.

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ANAGRAM, a happy transposition of the letters of a word or sentence, in such a manner as to form another. Various examples might be adduced; but a modern one may be most acceptable. Of the letters which compose the words "Revolution Française," after taking away those which make the word veto, the following sentence has been formed: "Un Corse la finira ;" i. e. "A Corsican shall finish it."

ANALYSIS, in chemistry, is the separation of any substance into its constituent parts, to ascertain their nature, relative proportions, and their mode of union. Thus, water by chemical analysis is found to consist of certain proportions of hydrogen and oxygen. Again, nitrate of ammonia is a salt composed of nitric acid, ammonia, and water, but each of these are compounds; nitric acid consists of azote and oxygen; ammonia, of azote and hydrogen; and water; of hydrogen and oxygen, so that the three simple substances which enter into nitrate of ammonia are azote, hydrogen, and oxygen.

ANAMORPHOSIS, in perspective and painting, a representation of an image either on a plane or carved surface, deformed, or distorted, which in a certain point of view appears regular and in just proportion.

ANALEMMA, a planisphere, or projection of the sphere, orthographically made on the plane of the meridian, by perpendiculars, from every point of that plane, the eye supposed to be at an infinite distance, and in the east or west point of the horizon. In this