amercement, whether the escape hap. pens by day or night. The statute of Magna Charta ordains, that a freeman is not to be amerced for a small fault, but in proportion to the offence, by his peers and equals. AMERIMNUM, or AMERIMNON, in botany, a genus of the Diadelphia Decandria class and order; of the natural order of Papilionacea or Leguminosa; the characters of which are, that the calyx is a one-leafed perianthium; t be bell shaped, five-toothed, the teeth sharp; the corolla papilionaceous, standard with an oblong claw, roundish, heart-shaped, expanding and convex, wings lanceolate, shorter than the standard, and keel short; the stamina have ten filaments conjoined, anthers roundish; the pistillum has a germ pedicelled, oblong, compressed, leafy, varicose, with lateral veins, within woody, hot gaping; cells disposed longitudinally within: the seeds solitary, kidney-shaped, thicker at the base, appendicted at the top. There are two species, viz. 1. A. Brownei: this shrub rises commonly to the height of ten feet, and supports itself on other shrubs. It is a native of Carthagena, Jamaica, and Domingo. 2. A. ebenus, Jamaica ebony, which is common in Jamaica and several other parts of the West Indies, where the wood is cut, and sent into England under the name of ebony, though the true ebony is a native of the eastern country, and of a different genus. This wood is of a fine greenish brown colour, admits of polishing well, so that it is much valued by the instrument makers, and it is of a very hard durable nature. Dr. Browne says, that the trunk seldom exceeds three or four inches in diameter; that the slender branches, being very tough and flexible, are used for riding switches, and kept at all the wharfs about Kingston, to scourge the refractory slaves. AMETHYST, in mineralogy, is one of the Quartz family; it occurs massive and in rolled pieces, but most frequently crystallized. The crystals are six-sided pyramids; colour violet blue, passing on the one hand to plum blue, brown, brownish black; on the other to pearl and ash grey, greyish white, greenish white, olive green, and in some rare cases pistachio In massive varieties several cogreen. Yours appear together in stripes in this state they are composed of thick prismatic distinct concretions, often shooting into crystals at their extremities. Specific gravity 2.75. It is found in veins, and in the Follow cavities of agate. It is composed of It is found abundantly in different parts of Saxony: also in the Hartz, in the Uralian mountains, and in the East Indies. The most beautiful varieties are found at Catharinaburg in Russia. It is cut into rings, seals, and boxes, but it is not very highly valued. The green is the chrysolite of some authors: the oriental amethyst is the sapphire: it is sometimes covered with capillary crystals of iron mica, and when viewed in certain positions appears red; this variety is named the hair amethyst. AMETHYST, in heraldry, a term for the purple colour in the coat of a nobleman, in use with those who blazon by precious stones instead of metals and colours. This in a gentleman's escutcheon is called purpure, and in those of sovereign princes mercury. AMETHYSTEA, amethyst, so called from the amethystine colours of the flowers, in botany, a genus of the Diandria Monogynia class: the characters are, that the calyx is a perianthium, one-leafed, tube bell-shaped, angular, semiquinquefid, subequal, acuminate, and permanent; the corolla is one-petalled, ringent, little longer than the calyx; border five-parted and subequal: upper lip erect, roundish, concave, two-parted, gaping; lower threeparted; the sides rounded, erect, shorter; the middle quite entire, concave, the length of the upper lip; the stamina have filaments, filiform, approximating, under the upper lip, and longer than it; anthers simple and roundish; the pistillum is a quadrifid germ, style size of the stamens, stigmas two, and acute; no pericarpium, but the calyx becomes more bell-shaped and spreading; the seeds are four, shorter than the calyx; obtuse, and angular within. There is one species, viz. A. cœrulia, mountain upright A. which is a native of the mountains in Siberia, from whence the seeds were sent to the Imperial garden at Petersburgh, and in 1759 to Chelsea garden, where the plants annually produce seeds. It is annual, and hath an upright stalk, which rises about a foot high, and towards the top puts out two or three small lateral branches; these are garnished with small trifid leaves, sawed on their edges, and of a very dark green colour; at the extremity of the branches the flowers are produced in small umbels; these are of a fine blue colour, as are also the upper part of the branches, and the leaves immediately under the umbel; so that though the flowers are small, yet, from their colour, with that of the upper part of the stalks, the plants make a pretty appearance during their continuance in flower. AMIA, in natural history, a genus of fishes of the order Abdominales. Generic character: head bony, naked, rough, with visible sutures. Teeth, both in jaws and palate, close-set, sharp, numerous. Cirri or beards two, near the nostrils. Gill-membrane twelve-rayed: body scaly. There is a single species, Calva, a small fresh water fish, inhabiting some parts of Carolina, of which the tail is rounded, and with a black spot; it is seldom eaten. AMIABLE, or amicable numbers, such as are mutually equal to the sum of one another's aliquot parts, as the numbers 284 and 220. Van Schouten was the first who gave this name to such numbers, of which there are but very few at least to be set down and manageable by us. For 284 and 220 are the two least. The aliquot parts of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, and the sum of these is equal 284. The aliquot parts of 284 are 1, 2, 4, 71, 142, and the sum of these is 220. The second pair of applicable numbers are 17296 and 18416. The third pair are 9363584 and 9437056. AMIANTHUS. See ASBESTOS. AMICUS curia, in law, if a judge be doubtful or mistaken, in a matter of law, a bystander may inform the court as amicus curia. AMMANNIA, named by Houstoun in honour of J. Amman, in botany, a genus of the Tetrandria Monogynia class and order. Its characters are, that the calyx is a perianthium, bell-shaped, oblong, erect, with eight streaks and folds, quadrangular, eight-toothed, teeth alternate, bent in, and permanent; corolla none, or four-petalled, petals vertically ovate, spreading, inverted into the calyx; the stamina have filaments, (four or eight) bristly, the length of the calyx into which they are inserted, anthers twin; the pistillum is a germ, subovate, large and superior, style simple, very short, and stigma headed; the pericarpium is a roundish, four-celled capsule (bury) covered with the calyx; the seeds are numerous and small. AMMI, bishop's weed, in botany, a dis tinct genus of umbelliferous plants, belonging to the Pentandria Digynia class of Linnæus; the flower of which is rosaceous, and composed of heart-like petals; and its fruit is a small roundish and striated capsule, containing two striated seeds, convex on one side, and plane on the other. There are four species. AMMODYTES, in natural history, the launce, a genus of fishes, of the order Apodes: head compressed, narrower than the body: upper lip doubled: lower jaw narrow, pointed: teeth small and sharp. Gill-membrane seven-rayed: body long, roundish, with very small scales: tail distinct. A. tobianus, or sand launce, so named from its shape. It inhabits the northern seas; and is from 9 to 12 inches long. It buries itself on the recess of the tides a foot deep in the sand, and in fine weather rolls itself up, and lifts its nose just above the sand; it is the prey of other rapacious fish; the flesh is tolerably good, but it is used in most cases as baits. The launce lives on worms, water-insects, and small fishes, and even occasionally on those of its own species. The mackarel is very partial to this fish as its own food. The launce spawns in May, depositing its eggs in the mud near the edges of the coast. AMMONIA, in chemistry. Volatile alkali, in its purest form, subsists in a state of gas, and was thought, till the late experiments of Mr. Davy, to be composed of azote and hydrogen. It may be obtained in the following manner: put into a retort a mixture of three parts of quick-lime and one part of sal ammoniac in powder. Plunge the beak of the retort below the mouth of a glass jar filled with mercury, and standing inverted in a basin of mercury. Apply the heat of a lamp to the retort: a gas comes over, which displaces the mercury and fills the jar. This gas is ammonia. It was known by the name of volatile alkali; it was also called hartshorn, because it was often obtained by distilling the horn of the hart; spirit of urine, because it may be obtained by the same process from urine; and spirit of sal ammoniac, because it may be obtained from that salt. Dr. Black first pointed out the difference between ammonia and carbonate of ammonia, or ammonia combined with carbonic acid; and Dr. Priestley discovered the method obtaining it in a state of purity, by the process already described. Ammonia, in a state of gas, is transparent and colourless like air; its taste is acrid and caustic, like that of the fixed alkalies, but not nearly so strong, nor does it like them corrode those animal bodies to which it is applied; its smell is remarkably pungent, though not unpleasant when sufficiently diluted. Its use as a stimulant to prevent fainting is well known. Animals cannot breathe it without death. When a lighted candle is let down into this gas, it goes out three or four times successively; but at each time the flame is considerably enlarged by the addition of another flame of a pale yellow colour, and at last this flame descends from the top of the vessel to the bottom. Its specific gravity, according to the experiments of Kirwan, is 0.60, that of air being 1.00; while Mr. Davy, whose gas was probably purer, found it 0.55. At the temperature of 60°, a hundred cubic inches of this gas weigh, according to Kirwan, 18.16 grains, according to Davy, 17.068. Hence it is to common air nearly as 3 to 5. When exposed to a cold of -45° it is condensed into a liquid, which again assumes the gaseous form when the temperature is raised. When passed through a red hot tube of porcelain or glass, it is totally decomposed, and converted into hydrogen and azotic gas. It combines very rapidly with water. When a bit of ice is brought into contact with this gas, it melts, and absorbs the ammonia, while at the same time its temperature is diminished. Cold water absorbs this gas almost instantaneously, and at the same time heat is evolved, and the specific gravity of the water is diminished. Water is capable of absorbing and condensing more than a third of its weight of ammoniacal gas. It is in this state that ammonia is usually employed by chemists. The term ammonia almost always means this liquid solution of ammonia in water. When heated to the temperature of about 130°, the ammonia separates under the form of gas. When exposed to the temperature of -46°, it crystallizes; and when suddenly cooled down to-68°, it assumes the appearance of a thick jelly, and has scarcely any smell. It follows, from the experiments of Mr. Davy, that a saturated solution of ammonia is composed of 74.63 water. 25.37 ammonia. 100.00 Charcoal absorbs ammoniacal gas, but does not alter its properties while cold. But when the gas is made to pass through red hot charcoal, part of the charcoal combines with it, and forms a substance known by the name of Prussic acid. Ammonia is not acted on by azote; but it combines rapidly with muriatic acid; the two gases concreting into the solid salt called muriate of ammonia. Ammonia does not combine with the metals; but it changes some of them into oxydes, and then dissolves them. Liquid ammonia is capable of dissolving the oxydes of silver, copper, iron, tin, nickel, zinc, bismuth, and cobalt. When digested upon the oxydes of mercury, lead, or manganese, it is decomposed, water is formed by the union of the hydrogen of the ammonia with the oxygen of oxydes, and azotic gas is emitted. If a considerable heat be applied, nitric acid is formed at the same time with water. Several other oxydes are also partly deoxidized, when ammonia is poured into their solutions in acids. See ALKALI, CHEMISTRY, &c. AMMONIAC, in chemistry, a gum resin brought from the East Indies. It is supposed to be a species of the Ferula It is in small pieces agglutinated together, and has a yellowish white colour. Its smell is like that of the galbanum, but more pleasant. Its taste is a nauseous sweet, mixed with bitter. It does not melt. Water dissolves a portion of it; the solution is milky, but gradually lets fall a resinous portion. One-half is soluble in alcohol. Its specific gravity is 1.2. Neither alcohol nor water, distilled off it, brings over any thing. AMMONITRUM. See GLASS. AMMOPHILA, in natural history, the sand-wasp, a genus of insects of the order Hymenoptera: gen. char. snout conic, inflected, concealing a bifid retractile tubular tongue: jaws forcipated, three-toothed at the tip; antennæ filiform in each sex, with about 14 articulations: eyes oval: wings plain: sting pungent, concealed in the abdomen. This genus is separated from that of the sphex, on the authority of the Rev. Mr. Kirby: in their manners and economy they resemble each other; and it is probable that many more of the spheges might with propriety be removed into this genus. There are four species: A. vulgaris inhabits Europe, in sandy, sunny banks, where it digs a hole with its fore-feet, and buries the carcase of the larva of a moth or half dead spider, in the body of which it has deposited its eggs, and then covers up the orifice. AMMUNITION, a general term for all warlike provisions, but more especially powder, ball, &c. Ammunition, arms, utensils of war, AMN gun-powder, imported without licence And again, such licence obtained, ex- AMNESTY, in matters of policy, an act by which two parties at variance promise to pardon and bury in oblivion all that is past. Amnesty is either general and unlimited, or particular and restrained, though most commonly universal, without conditions or exceptions; such as that which passed in Germany at the peace of Osnaburg, in the year 1648. Amnesty, in a more limited sense, denotes a pardon granted by a prince to his rebellious subjects, usually with some exceptions: such was that granted by Charles II. at his restoration. AMNIOS, in anatomy, a thin pellucid membrane, which surrounds the fœtus. The fœtus in the uterus is enveloped in a peculiar membranaceous covering, to which anatomists have given the name of amnios. Within this there is a liquid, distinguished by the name of the liquor of the amnios, which surrounds the fœtus on every part. This liquid, as might have been expected, is very different in different animals; at least the liquor amnii in women and in cows, which alone have hitherto been analysed, have not the smallest resemblance to each other. The liquor of the amnios of women is a fluid of a slightly milky colour, a weak pleasant odour, and a saltish taste. The white colour is owing to a curdy matter suspended in it, for it may be obtained quite transparent by filtration. Its specific gravity is 1.005. It gives a green colour to the tincture of violets, and yet it reddens very decidedly the tincture of turnsole. These two properties would indicate at once the presence of an acid and of an alkali. It froths considerably when agitated. On the application of heat it becomes opaque, and has then a great resemblance to milk diluted with a large quantity of water. At the same time it exhales the odour of boiled white of egg. Acids render it more transparent. Alkalies precipitate an animal matter in small flakes Alcohol likewise produces a flaky precipitate, which, when collected and dried, becomes transparent, and very The infusion of nut galls proEike glue. duces a very copious brown coloured precipitate. Nitrate of silver occasions a AMO white precipitate, which is insoluble in possesses the following properties: It : AMOMUM, in botany, a genus of the Monandria Monogynia class and order, the characters of which are, that the calyx is a perianthium, one leafed, cylindraceous, and unequally trifid: the corolla is monopetalous and funnel-shaped, tube cylindraceous, border three-parted, parts oblong and spreading the nectary two-leaved or two-lipped, lower lip inserted under the upper segment of the corolla, spreading almost erect, entire or three-lobed; the stamina have no fila ment, except the upper lip of the nectary smaller than the lower, and opposite to it, accuminate or three-lobed at the tip; along the middle or at the end of which grows longitudinally a large oblong anther, germinate. or divided by a longitudinal furrow into two, which are one-valved; the pistillum has an inferior, oblong germ, style filiform, drawn through the suture of the anther, stigma turbinate, obtuse and cinate; the pericarpium a fleshy capsule, ovate, three cornered, three-celied, and three-valved; the seeds are several, covered with a sort of berried aril. Gmelin, in his edition of Linnæus, enumerates twenty species. A. zinziber, narrow-leaved ginger, cultivated by Miller, and flowering in September, is a native of the East Indies, and other countries of Asia, and is much used there and in the West Indies. The dried roots furnish a considerable article of commerce from our West-India islands; they are of great use in the kitchen and in medicine, and when preserved green as a sweet-meat are preferable to every other sort. A. zerumbet, cultivated at Hampton-court, in 1690, and flowering with us from September to November, when the stalks perish like those of the true ginger; a native of the East Indies, Chochinchina, &c. and also in Otaheite, and the other Society Isles. This is used externally in the East, in cataplasms and fomentations; but not internally, as spice or medicine; though Garcias says, that it makes a better preserve with sugar than the other. As to the propagation and culture of these plants, it may be observed, that they are tender, and require a warm stove to preserve them in this country. They are easily propagated by parting their roots, which should be done in the spring, before they put out new shoots; in parting the roots, they must not be divided into small pieces, especially if they are designed to have flowers; nor should they be planted in very large pots. They thrive best in a light rich earth, such as that of the kitchen garden; and with this the pots should be filled within two inches of the top, and the roots should be placed in the middle of the pots, with their crowns upwards, and the pots should then be filled with the same earth; they should be plunged into a hot-bed of tanner's bark, and sparingly watered, till their stalks appear above ground, when they will admit of more moisture, especially in the summer months; but in autumn, the waterings must not be frequent nor plentiful, and during winter very sparing. The pots must constantly remain plunged in the tan-bed; for if they are taken out and placed on shelves in the stove, their fibres often shrink, and thus their roots decay. By this management these plants have greatly multiplied, and the common ginger has produced roots weighing five or six ounces; but the others have been nearly a pound weight. In the West In. dies the ginger thrives best in a rich cool soil; in a more clayey soil the root shrinks jess in scalding. The land laid out for the culture of it is first well cleared and hoed, and then slightly trenched, and planted in March or April; it flowers about September; and when the stalks are wholly withered, the roots are fit to be taken up, which is generally done in January and February. AMONTONS, (WILLIAM), in biogra. phy, an ingenious French experimental philosopher, was born in Normandy the 31st of August, 1663. While at the grammar school, he by sickness contracted a deafness that almost excluded him from the conversation of mankind. In this situation he applied himself to the study of geometry and mechanics, with which he was so delighted, that it is said he refused to try any remedy for his dis. order, either because he deemed it incu. rable, or because it increased his attention to his studies. Among other objects of his study were, the arts of drawing, of land-surveying, and of building; and shortly after he acquired some knowledge of those more sublime laws by which the universe is regulated. He studied with great care the nature of barometers and thermometers; and wrote his treatise of "Observations and experiments concerning a new Hour-glass, and concerning Barometers, Thermometers, and Hygroscopes;" as also some pieces in the Journal des Savans. In 1687, he presented a new hygroscope to the Academy of Sci. ences, which was much approved. He found out a method of conveying intelligence to a great distance in a short space of time; this was by making signals from one person to another, placed at as great distances from each other as they could see the signals by means of telescopes: this was unquestionably done upon the principle of modern telegraphs, which were brought into general use in 1794, almost a century after the death of Amontons. Amontons was chosen a member of the Royal Academy in 1699, as an eleve under the third astronomer; and he read there his "New Theory of Frietion," in which he happily cleared up an important object in Mechanics. He had a particular genius for making experi ments; his notions were just and delicate: he knew how to prevent the inconveniences of his new inventions, and had a wonderful skill in executing them. He died of an inflammation in his bowels, the 11th of October, 1705, being only 42 years of age. His pieces are contained in the different volumes of the memoirs of the Academy of Sciences; these are numerous, and upon various subjects: as the air, action of fire, barometers, |