of two justices. By 9 George III. c. 37. §7. they are to forfeit 108. or 20s. for paying the poor in bad money.

OVERT act. In the case of treason, is compassing or imagining the death of the king; this imagining must be manifested by some open act; otherwise, being only an act of the mind, it cannot fall under any judicial cognisance. Bare words are held not to amount to an overt act, unless put into writing; in which case they are then held to be an overt act, as arguing a more diliberate intention. No evidence is to be admitted of any overt act, that is not expressly laid in the indictment, 7 Will. c. 3.

OVIPAROUS, a term applied to such animals as bring forth their young, ab ovæ, from eggs; as birds, insects, &c.

OVIS, the sheep, in natural history, a genus of mammalia of the order Pecora. Generic character: the horns hollow, wrinkled, turning backwards and outwards into a spiral form; lower front teeth eight; no canine teeth. There are nine species mentioned by Shaw. The following are most worthy of attention.

O. ammon, or the Siberian sheep, or the argali. The argali, or wild sheep, is the presumed origin of all the domestic sheep. It is found on the immense chain of mountains reaching through the middle of Asia to the Eastern Ocean. In Barbary, Corsica, Sardinia, Greece, and Kamtschatka, it is also to be met with, and in some of these places in great abundance. Its size is that of a fallow deer. In Siberia, the Argali is fond of ranging the highest elevations, and is generally seen in small flocks. As winter approaches, they move downwards into the plains, and instead of the shoots of the mountain plants, which were before their food, eat grass and other vegetables. They are extremely fond of salt, and will often remove the earth which covers this substance, in considerable quantities, in order to obtain it. Their horns grow to a vast size and weight. These animals are timid in a very great degree; but the males will occasionally engage in fierce conflicts with each other, and, it is said, endeavour to precipitate each other down the steeps of the mountains which they inhabit. They move over these rugged eminences with great agility, and the chase of them is difficult and fatiguing. They are supposed to live to the age of fourteen years.

O. aries, the common sheep.

This

animal, in its state of complete domesti cation, appears equally stupid as it is harmless, and seems nearly to justify the observations of Buffon, who describes it as one of the most timid, imbecile, and contemptible of quadrupeds. When sheep, however, have an extensive range of pasture, and are left in a considerable degree to depend upon themselves for food and protection, they exhibit more respectability of character. A ram has been seen in these circumstances to attack and beat off a large and formidable dog, and even a bull has been felled by a stroke received between his eyes, as he was lowering his head to receive his adversary on his horns, and toss him into the air. When individual efforts are unequal to the danger, sheep will unite their exertions; placing the females and their young in the middle of an irregular square, the rams will station themselves so as to present an armed front on every side to the enemy, and will support their ranks in the crisis of attack, harrassing the foe by the most formidable and sometimes fatal blows. Sheep display considerable sagacity in the selection of their food, and in the approach of storms they perceive the indications with accurate precision, and retire for shelter always to the spot which is best able to afford it. The domestic sheep are scarcely ever found, (excepting in temperate latitudes) in a state approaching to perfection. In hot regions its wool degenerates into a species of hair, and in rigid climates, though the wool is fine at the roots, it is coarse towards the surface. The flesh of the animal, when it passes to great degrees, whether of heat or cold, appears also proportionably deteriorated. The wool of sheep in no country of the world attains greater excellence for the purpose of manufacture, without the assistance of any mixture, than in England. That of the Spanish breed is finer, but too short for manufacture by itself, and comparatively trifling in weight. Since England attained any considerable advance in civilization, its breed of sheep has been admired for the excellence of their fleeces, which constituted the grand material of national industry, wealth, and revenue. At present, the worth of the wool annually shorn in that country is considerably upwards of two millions, and when wrought produces an amount of nearly seven millions sterling; facts which exhibit the importance of the cultivation of that animal, which is the

source of all this opulence, in a point of view particularly striking. There are several breeds or races in that country which have their respective admirers, and each of which will probably thrive better than others in certain soils and situations. The sheep of Lincolnshire af. ford the largest quantity of wool, but their flesh is more coarse and lean, and less pleasantly flavoured than that of some others. The sheep of the largest size are found in the rich district between Yorkshire and Durham, one of which was fed so highly as to weigh sixty-two pounds per quarter. These are reported to be equally prolific as they are large, and an ewe of this breed produced, at the age of two years, four young ones at a birth, and at the end of eleven months after, five more. The Dorsetshire breed is also considerably celebrated for fecundity: these are likewise highly admired for the delicacy and fine flavour of their flesh, but their wool is little in amount, though of excellent quality. In the north there is a hardy race of these animals, marked by their shaggy wool and black faces, which are admirably adapted to the bleak and mountainous tracts where they are produced, and sustain the rigour of winter in these cold situations without any inconvenience. Their eyes are wild, their movements nimble and rapid, and their flesh peculiarly excellent. Towards the extreme points of the north of Scotland, there is a race of sheep particularly small, not exceeding six pounds per quarter in weight. The attention of noblemen and gentlemen of the first distinction has now long been directed to the cultivation of the sheep, with respect to every point of its economy, its breed, its food, and the nature and degree of those attentions which will best promote its excellence, both as an article for subsistence and manufacture. These efforts, not many years since, it must be acknowledged, took a somewhat singular direction, and it appeared to be the grand object of agricultural ingenuity, to raise the animal to that superlative degree of fatness, which, in all but the most robust appetites, was calculated to excite disgust. In one instance, particularly, it was considered as an exploit of transcendent merit to have carried this process so far, that the fat of the animal, cut, without any slope, directly through the ribs, measured upwards of seven inches. This ludicrous, as well as pernicious and wasteful folly, has, however, now, for some years, ceased. The sheep is more sub

ject to disorders than any of the domesticated animals; giddiness, consumption, scab, dropsy, and worms, frequently seizing upon and destroying it. The last are met with in vast numbers in the liver and gall-bladder of these animals. These worms belong to the genus fasciola, are flat, oval, and pointed at the extremities. The Ay is another formidable enemy, and is often fatal in the course of twenty-four hours, breeding within the skull of the animal. To extricate the sheep from this danger, the French shepherds apply the trephine without the slightest hesitation, and with the greatest dispatch and success. For the common ram, see Mammalia, Plate XVII. fig. 4.

The Cretan sheep is remarkable for long and large horns, twisted in the shape of a screw.

The many horned sheep is found most commonly in the north of Europe, and most frequently in Iceland. Three, four, and even five horns, are occasionally seen on these animals in considerably different forms, sizes, and situations. See Mammalia, Plate XVII. fig. 6.

The Cape sheep is remarkable for its emaciated appearance, long neck, and pendulous ears, and for having a pair of wattles under the neck like goats.

The broad-tailed sheep occurs in vaextremely similar to the European breed rious countries of Asia and Africa, and is in almost all respects, but that its tail is of an immense weight, varying from fifteen to fifty pounds, under which the shepherds are reported to place a board movements. These tails are stated to with wheels, to facilitate the animal's constitute the most marrowy and luxuri

ous food.

The Tibetian sheep yield wool of admirable length and fineness, and are said to produce the material from which are fabricated the Indian shawls, which are sometimes sold in this country for between thirty and fifty pounds.

O. montana. This species is remarkable for the fineness of its wool, being in this respect superior to any sheep hitherto known; and for the singular form of its horns, which are short, conical, slightly recurved, and acute at their tips. It is described in the Journal of the Academy of Natural Sciences of Philadelphia, Vol. I. No. 1. by Mr. Geo. Ord. A portion of the skin, with the horn attached, to it, is in Peale's Museum. It is a native of North America.

For a species of sheep called the dwarf sheep, see Mammalia, Plate XVII. fig. 5. OUNCE, a little weight, the sixteenth part of a pound avoirdupois, and the twelfth part of a pound troy: the ounce avoirdupois is divided into eight drachms, and the ounce troy into twenty penny. weights. The avoirdupois ounce is less than the troy ounce, but the avoirdupois pound is greater than the troy pound. One hundred and seventy-five troy ounces are equal to one hundred and ninety-two avoirdupois ounces; but one hundred and forty four pounds avoirdupois are equal to one hundred and seventy-five pounds troy. Therefore one pound avoirdupois is equal to one pound, two ounces, eleven pennyweights,sixteen grains, troy. See WEIGHT.

OVOLO, or Ovuм, in architecture, a convex conic section, consisting of the elliptical, hyperbolical, or parabolical curves. It is generally used as a crowning member in the Grecian Doric, and when carved with the egg and dart, is termed Echinus.

OUSTED, in law, means put out, or removed, as ouster of possession as to lands.

OUTLAWRY, is being put out of the law, or out of the king's protection. It is a punishment inflicted for a contempt, in refusing to be amenable to the process of the higher courts. By outlawry, in civil actions, a person is so put out of the protection of the law, that he is not only incapable of suing for the redress of injuries, but may be imprisoned, and forfeits all his goods and chattels, and the profits of his land; his personal chattels immediately upon the outlawry, and his chattels real and the profits of his lands when found by inquisition. Proceeding to outlawry is usually had in civil suits where an action is brought against two partners, and one is abroad; it is then necessary to outlaw him before the other can be proceeded against.

OUTWORKS, in fortification, all those works made without side the ditch of a fortified place, to cover and defend it. Outworks, called also advanced and detached works, are those which not only serve to cover the body of the place, but also to keep the enemy at a distance, and prevent his taking advantage of the cavities and elevations usually found in the places about the counterscarp, which might serve them either as lodgments, or as rideaux, to facilitate the carrying on their trenches, and planting their batteries against the place: such are ravelins, teVOL. IX.

nailles, horn-works,velopes, crown-works, &c. It is a general rule in all outworks, that if there be several of them, one before an other, to cover one and the same tenaille, of a place, the nearer ones must, gradually,one after another, command those that are further advanced out into the campaign, that is, must have higher ramparts, that so they may overlook and fire upon the besiegers when they are masters of the more outward works.

OWL. See STRIX. ΟΧ See Bos.

OXALIC acid, in chemistry, is found native in some acid vegetable juices, and rather plentifully in the "oxalis acetocella," or "wood-sorrel," and in other plants of the same genus; it is naturally united with a quantity of potash, not sufficient for complete saturation, forming what has long been known under the name of "Essential salt of sorrel." The oxalic acid is prepared artificially, by boiling a sufficient quantity of nitric acid with a variety of vegetable and animal substances, such as sugar, mucilage, alcohol, animal jelly, &c. Take sugar as an example: one ounce in powder is put into a retort, with three ounces of strong nitric acid. During the solution, great quantities of the nitrous acid escape: heat is to be applied till the nitrous gas is driven off. Three ounces more of nitric acid are to be added, and the boiling continued till the fumes cease, and the colour of the liquor vanishes. Pour out the liquor into a wide shallow vessel, and, when it cools, crystals will be formed, which may be collected and dried on unsized paper. The crystals thus obtained may again be dissolved in distilled water, and evaporated, to obtain new crystals. In this way oxalic acid may be obtained from the substances above enumerated, and many others, as alcohol, gum, honey, &c. Prepared in this way, oxalic acid is, in a concrete state, crystallized in four-sided prisms, terminated in two sided summits. They are white and transparent, and have conside rable lustre. They have a sharp taste, and change vegetable blues into a red colour, and produce the same effect on all vegetables, excepting indigo. The acid properties of this substance are so strong, that one part of concrete oxalic acid gives to 3,600 parts of water the property of reddening paper stained with turnsole. When exposed to heat it is volatilized, partly in a liquid, and also in a crystalline form. It cannot be decomposed but by a very great heat. It is

M

It combines with alkalies, earths, and metallic oxides, and the salts thus formed are denominated oxalates. The great attraction which this acid has for lime renders it of great utility in detecting that substance in every soluble combination. OXALATES, in chemistry, salts formed of the oxalic acid and certain bases, are distinguished by the following properties when exposed to a red heat, the acid is decomposed and driven off, and the base only remains. Lime water precipitates a white powder from their solutions, provided no excess of acid be present the earthy oxalates are, in generai, nearly soluble in water, but they may be rendered soluble by an excess of the more powerful acids. See OXALIC acid

OXALIS, in botany, wood-sorrel, a genus of the Decandria Pentagynia class and order. Natural order of Gruinales. Gerania, Jussieu. Essential character: calyx five-parted: petals five, often connected at the base; capsule five-celled, five-cornered, opening at the corners; seeds arilled. There are ninety-six species, of which the O. acetosella, common wood-sorrel, has a perennial, branched, knobbed, creeping root, having fine fibrils on every side, partly red and partly white, with an ovate, acute, rigid scale, like a tooth, at the knobs; scapes one or two, jointed at the base, the length of the leaves; calycine leaflets, oblong, acute, sometimes bifid, ciliate, purple at the tip, upright. Linnæus remarks, that the leaflets in wet weather are erected, but hang down in dry weather. It has been observed, that this elegant little plant has the leaves of trefoil, the taste of sorrel, and the flower of geranium; from which last genus this is distinct, in the number of styles, the form of the capsule and manner of its opening, its straight corcle,

or heart, without any perisperm or albumen: it is common all over Europe.

OXGANG, or OXGATE, is generally taken, in our old law books, for fifteen acres, or as much ground as a single ox can plow in a a year.

OXIDE, in chemistry. Metallic substances are not only of vast importance in the arts of civilized life, on account of the properties which belong to them in the metallic state; but many of them are not less valuable in those changes which they undergo by new combinations, and the new properties they acquire, in consequence of these changes. One of the first and most ordinary changes to which metallic substances are subject, is their combination with oxygen. This is called, in chemical language, oxydation. If a metal, as, for instance, a piece of iron, is exposed to the air when it is moist, it soon undergoes a remarkable change. It loses its metallic lustre, and the surface is covered with a brownish powder, well known by the name of rust. This change is owing to the combination of oxygen with the metal, and the rust of the metal in this state is known in chemistry by the name of oxide. The process by which the compound of oxygen and a metallic substance is formed, is called oxydation, and the product is denominated an oxide. The process of oxydation is effected more rapidly when metals are exposed to the action of heat; and, indeed, many metals require a very high temperature to produce the combination, while it cannot be accomplished in others by the greatest degree of heat that can be produced. This process was formerly called calcination, or calcining the metal; and the product now denominated an oxide, was distinguished by the name of calx or calces, from its being reduced to the state of powder, in the same way as limestone by burning. Metals differ very much from each other in the circumstances in which this oxydation takes place, as in the temperature which is necessary, the facility of the combination, the proportions of oxygen which combine, and the force of affinity between the constituent parts of the oxide. Some metals are oxydated in the lowest temperature, as, for instance, iron and manganese; while others require the greatest degree of heat that can be applied. Such are silver, gold, and platina.

The facility with which oxydation takes place in some metals is so great, such as in iron, tin, lead, copper, and manganese, that they must be completely defended

This

from the action of oxygen; but in gold and platina, no perceptible change is observed, for whatever length of time they are exposed to the atmosphere. oxydation, and the quantity of oxygen absorbed, is proportionable to the temperature. There are, however, many metals which combine with a determinate proportion of oxygen at certain temperatures, and from this may be estimated the quantity of oxydation from the degree of heat which has been applied. The rapidity of the oxydation is almost always increased by the elevation of temperature. In this way actual combustion or inflammation is produced. Thus filings of metals thrown upon a body in a state of ignition, give out brilliant sparks; and steel, struck upon a flint, burns with a vivid flame in the air, in consequence of the great heat which is communicated to it by percussion. Metallic substances combine with very different proportions of oxygen; and this quantity varies according to the manner in which the process has been conducted, or the temperature to which the metal has been exposed.

In these different states and conditions of oxydation different phenomena are exhibited. Sometimes the metal becomes red-hot, and is inflamed; sometimes the oxydation takes place without fusion, or does not combine with oxygen till after it has been melted; sometimes it is covered with a brittle crust, or with a substance in the form of powder. At other times a pellicle, exhibiting different colours, forms on the surface: but, in all cases, the metal is tarnished, loses its brilliancy and its colour, and assumes another, which announces the change that has taken place. Another difference which takes place among metals is, the different degrees of force with which the oxygen adheres to the metal. The knowledge of this, and the different degrees of affinity between oxygen and metallic substances, is of great importance in many operations and chemical results. During the fixa tion of oxygen in metallic substances, it is absorbed by some in its solid state, and gives out a great deal of caloric. In others it is combined, without giving out the same quantity. This proportion of caloric given out corresponds to the facility with which oxides part with their oxygen, or are reduced to the metallic state. Those which have combined with oxygen, with the greater proportion of caloric, are most easily reduced; but those, on the contrary, in which the oxy

gen has been deprived of its caloric, are reduced to the metallic state by a great addition of caloric, and the greatest number of oxides require the addition of substances, whose affinity for oxygen is greater than that of the metal. Metallic oxides are extremely different in different metals, and even in the same metal, according to the proportion of oxygen. They are, however, possessed of some common properties. They are all in the form of powder or earthy substance, or so brittle as to be easily reduced to this state. They exhibit every shade of colour, from pure white to brown and deep red, and they are heavier than the metals from which they have been obtained. Some oxides are revived, as it is called, or are reduced to the metallic state, merely by being in contact with light or caloric. Some require the addition of a combustible substance, and a high temperature; while others have so strong an affinity for oxygen, that they cannot be deprived of it by the strongest heat, but become fusible in the fire, and afford a glassy matter, more or less coloured, and even serve as a flux to the earths. Some oxides are volatile, but the greatest number are fixed. Some have an acrid and caustic taste, are more or less soluble in water, and even possess an acid quality; others are insoluble and insipid.

OXOPHYLLUM, in botany, a genus of the Monadelphia Pentandria class and order. Natural order of Trihilatæ. Meliæ, Jussieu. Essential character: onestyled; calyx five-toothed; petals five, long; filaments sheathing the style, fivetoothed at top: teeth antheriferous; stigma one; capsule five-celled. There is but one species, viz. O. fœtidum; this is a shrub about ten feet in height, and nearly six inches in diameter; the bark is green and smooth, the wood white, tender, and fragile; the branches twiggy, garnished with alternate leaves, each leaf digitated, having three large lobes growing on a foot-stalk of five or six inches in length; each lobe is divided by a longitudinal nerve, which is prominent beneath; the flowers spring from the bottoms of the leaves, at the extremity of the twigs and branches; their common foot-stalk is about a foot in height, dividing at its summit into several smaller ones, on each of which are placed alternate sessile flowers; the corolla is white, each petal being an inch long, and, as it were, glued to each other, longitudinally, by their borders, so as to form a kind of tubular figure, the upper part spreading; these