into a wall, for the commodious and agreea ble placing a statue.

NICKEL. A white metal, which, when obtained pure, is both ductile and malleable. It may be forged into very thin plates, their thickness not being greater than 0.01 of an inch. Its colour is intermediate between that of silver and tin, and is not altered by the air. It is nearly as hard as iron. Its specific gravity is 8.279, and when forged 8.666.

The species of nickel ores are its alloy with arsenic, and a little sulphur and its oxide.

The first is the most abundant, and the one from which nickel is usually extracted. It is known to mineralogists by the name of kupfer-nickel, or copper-nickel, from its colour and appearance. It occurs generally massive and disseminated; its colour is copper-red of varions shades; its lustre is weakly, shining, and metallic; it is perfectly opaque; its fracture is uneven; it is hard, has no malleability, but is not easily broken; its specific gravity is from 6.6 to 7.5. Urged by the flame of the blow pipe, it gives vapours with a strong arsenical odour, and melts with difficulty. It dissolves in acids, giving a green solution. Bergman found it to be composed of nickel, iron, cobalt, arsenic, and sulphur. Vauquelin regards it as essentially an alloy of nickel and arsenic, the iron, cobalt, and sulphur, being accidental.

The other species, the oxide of nickel, occurs generally as an incrustation, sometimes also disseminated of a friable texture and earthly appearance; of an apple green colour, without lustre. It is not altered by the heat of the blow-pipe; but when mixed with borax, gives to it a yellowish red colour. Its solution in acids is of a green colour. It occurs generally with kupfernickel, or with certain cobalt ores. It is also contained in small quantities in a fossil of the siliceous genus, chrysoprase, to which it communicates an apple-green colour.

Nickel is extracted from the kupfernickel, but it is extremely difficult to free it entirely from the metals with which it is associated. The process given by Chenevix is the most simple. The metal obtained from kupfer-nickel, by roasting and fusion with three times its own weight of black flux, is dissolved in nitric acid, the solution being boiled, so that the arsenic present receiving oxygen from the acid may be converted into arsenie acid; a solution of ni

trate of lead is then dropped in, and the liquor evaporated by a very gentle heat but not quite to dryness. Alcohol poured into this solution precipitates every salt, but the nitrate of nickel, which has been formed by the double decomposition of the arseniate of nickel and the nitrate of lead. The alcohol of the solution of nitrate of nickel being evaporated, the metallic salt is redissolved in water and decomposed by potash. The oxide, well washed and dried, is reduced in an Hessian crucible lined with lamp-black.

By the experiments that have been made on nickel in its pure state, it appears to be proved that it is possessed of magnetic power, and that therefore iron is not the only metal to which it belongs. The magnetic properties of nickel had often been observed; but as in the usual processes by which it is obtained, it is always alloyed with iron; it was concluded, with probability, that the magnetism it exhibited was owing to the presence of that metal. Since methods, however, have since been disco. vered of obtaining nickel in a purer state, the error of this conclusion has been discovered. The effect of the magnet on it is very little inferior to that which it exerts on iron; and the metal itself becomes magnetic itself by friction with a magnet, or even by beating with a hammer. Magnetic needles have even been constructed of it in France, and have been preferred to those of steel, as resisting better the action of the air. The nickel preserves its magnetic property when alloyed with copper, though it is somewhat diminished; by a small portion of arsenic it is completely destroyed.

Nickel is extremely fusible; its fusing point being higher than that of iron.

This metal is oxyded by exposure to the atmospheric air at a high temperature, though with difficulty. Its oxide is more easily obtained by exposure to heat with nitre; it is of an apple green colour, and is obtained likewise of this colour by precipi. tation from some of its saline combinations. It appears to be the oxide at the minimum of oxydement; at least, according to the experiments of Thenard, another oxide can be formed more highly oxyded. It may be obtained by exposing the green oxide to a red heat, or by heating it with oxymuriatic acid. It appears therefore to be too highly oxydized to be capable of directly combining with any of the acids. According to Richter, oxide of nickel is reduced by heat

alone; and the only difficulty experienced is the intensity of the heat required to fuse the metal.

Nickel is oxydized and dissolved by a number of acids; its solutions being gene rally of a green colour and crystallizable.

The salts of nickel are decomposed by the alkalies, and the oxide, more or less free from the acid, is thrown down. If the alkalies are added in excess, they re-dissolve it; and with ammonia in particular, soluble triple salts are formed. Potash and soda dissolve even a small quantity of its pure oxide; ammonia dissolves it in a much larger quantity.

Nickel combines with sulphur by fusion. The compound has a yellow colour with some brilliancy. It is brittle and hard, and burns when strongly heated in contact with the air. Nickel is also dissolved by the alkaline sulphurets.

With phosphorus, nickel unites, either by projecting the phosphorus on the nickel at a high temperature, or by heating together phosphoric acid and nickel with a little charcoal. The nickel increases in weight one-fifth. The compound is of a white colour with metallic lustre, and appears composed of a congeries of prisms.

Nickel forms alloys with a number of the metals; but our knowledge of these combinations is very imperfect.

NICOTIANA, in botany, tobacco, a genus of the Pentandria Monogynia class and order. Natural order of Lurida. So laneæ, Jussieu. Essential character: corolla funnel form, with a plaited border; stamina inclined; capsule two-valved, twocelled. There are seven species, of which N. rustica, English tobacco, seldom rises more than three feet in height, having smooth alternate leaves upon short foot stalks; flowers in small loose bunches on the top of the stalks, of a yellow colour, appearing in July, which are succeeded by roundish capsules, ripening in the autumn. Sir Walter Raleigh, on his return from America, is said to have first introduced the smoking of tobacco into England. In the house in which he lived at Islington, are his arms, with a tobacco plant on the top of the shield. It is remarkable that tobacco has prevailed over the original name, petum, in all the European languages with very little variation, and even in Tartary and Japan. Tobacco is derived from the island Tobago. Petum is the Brasilian name.

NICTITATING membrane, in comparative anatomy, a thin membrane, chiefly

found in the bird and fish-kind, which covers the eyes of these animals, sheltering them from the dust or from too much light; yet is so thin and pellucid, that they can see pretty well through it.

NIDUS, among naturalists, signifies a nest, or proper repository for the eggs of birds, insects, &c. wherein the young of these animals are hatched and nursed:

NIEUWENTYT (BERNARD), in biography, a celebrated Dutch philosopher and mathematician, in the seventeenth and early part of the eighteenth century, was the son of a minister of Westgraafdyk, in North Holland, where he was born in the year 1654. He afforded early indications of a good genius, and a love of learning, which his father took care to encourage, by giving him the advantages of an excellent education. He was desirous of becoming acquainted with all the branches of knowledge; but he had the prudence and sagacity to proceed gradually in his acquirements, and to make himself master of one science, before he directed his attention to another. It was his father's wish that he should be educated to his own profession; but when he found that his son was disinclined to such a destination, he very properly suffered him to follow the bent of his own genius. The first science to which young Nieuwentyt particularly directed his study, was logic, in order to fix his imagination, to form his judgment, and to acquire a habit of right reasoning; and in this science he grounded himself upon the principles of Des Cartes, with whose philosophy he was greatly delighted. In the next place, he engaged in the study of the mathematics, with the various departments of which he became intimately conversant.

He then entered upon the study of medicine, and the branches of knowledge more immediately connected with that science; and he afterward went through a course of reading on jurisprudence. In the study of all these sciences he succeeded so well, as deservedly to acquire the character of a good philosopher, a good mathemati cian, and an able just magistrate. From his writings it also appears, that he did not permit his various subjects of inquiry to divert his thoughts from a due attention to the great and fundamental principles of naturai and revealed religion. He was naturally of a grave and serious disposition; but at the same time a very affable and agreeable companion. So engaging were his manners, that they conciliated the

esteem of all his acquaintance; by which means he frequently drew over to his opinion those who differed widely from him in sentiment. With such a character, he acquired great credit and influence in the council of the town of Puremerende, where he resided; and also in the states of that province, who respected him the more, because he never engaged in any cabals or factions, but recommended himself only by an open, manly, and upright behaviour. Had he aspired after some of the higher offices of government, there is no doubt but that his merits would have secured to him the suffrages of his countrymen; yet he preferred to such honours the cultivation of the sciences, contenting himself with being counsellor and burgomaster, without courting or accepting any other posts, which might interfere with his studies. He died in 1718, at the age of sixty-three, having been twice married. He was the author of various works, among which are, "Considerationes circa Analyseos ad quantitates Infinite parvas applicatæ Principia, &c." 1694, octavo; in which he proposed some difficulties on the subject of the analysis of infinitesimals. "Anylysis Infinitorum, seu Carvilineorum proprietates, ex Polygonorum deducta," 1656, quarto; which is a se quel to the former, with attempts to remove those difficulties. "Considerationes Secundæ circa Calculi Differentialis Principia, et Responsio ad Virum nobilissum G. G. Leibnitium, &c." 1696, quarto; occasioned by an attack of Leibnitz on the author's "Analysis," in the Leipsic Journal for 1695. "A Treatise on the new Use of the Tables of Sines and Tangents, " 1714. "The proper Use of the Contemplation of the Universe, for the Conviction of Atheists and Unbelievers," 1715, quarto; of which a French translation was published at Paris, in 1725, quarto, entitled, "L'Existence de Dieu demontrée par les Merveilles de la Nature;" and also an English one at London, in 1716, in three volumes, octavo, under the title of "The Religious Philosopher, or, the right Use of contemplating the Works of the Creator." A Memoir inserted in a Dutch Journal, entitled, "Bibliothèque de l'Europe," for the year 1716, in defence of the preceding work against a criticism of M. Bernard, in the "Nouvelles de la Republique des Lettres." "A Letter to M. Bothnia de Burmania, on his Article concerning Meteors," inserted in the "Nonvelles litter. du 22 Avril, 1719:” and about a month before his death, he put the finishing hand to an excellent refutation of Spi

noza, which was published in Dutch at Amsterdam, in 1720, quarto."

NIGELLA, in botany, fennel flower, a genus of the Polyandria Pentagynia class and order. Natural order of Multisilique. Ranunculacea, Jussieu. Essential character: calyx none; petals five; nectary five, two-lipped, within the corolla; capsule as many, connected. There are five species; these are annual herbaceous plants, with pinnate or bipinnate leaves, and linear leaflets; flowers terminating, in some species. surrounded with a five-leaved calyx like multifid involucre.

NIGHT, that part of the natural day during which the sun is underneath the horizon; or that space wherein it is dusky. Night was originally divided by the Hebrews, and other eastern nations, into three parts, or watchings. The Romans, and afterwards the Jews from them, divided the night into four parts, or watches, the first of which began at sun-set and lasted till nine at night, according to our way of reckoning; the second lasted till midnight; the third till three in the morning; and the fourth ended at sun-rise. The ancient Gauls and Germans divided their time not by days but by nights; and the people of Iceland and the Arabs do the same at this day. The like is also observed of our Saxon ancestors.

NIGHTINGALE. See MOTACILLA.

NIGRINE, in mineralogy, a species of the Menachine genus. Colour dark brownish-black, passing to velvet black; it occurs in larger and smaller angular grains; specific gravity 4.5. It is not attracted by the magnet; it is infusible per se, but with borax it melts to a transparent hyacinth-red globule; it yields its menachine to acid of sugar. This species is found in Transylvania, consisting of yellow sand, intermixed with fragments of granite, gneiss, and mica-slate, and from which gold is obtained by washing. It comes to us commonly intermixed with grains of precious garnet, cyanite, and common sand. Its name is derived from its black colour; it is distinguished from menachanite by its stronger lustre, superior hardness, the colour of the streak, as well as by its not being in the smallest degree affected by the magnet, which also distinguishes it from iron-sand. Its constituent parts are,

Oxide of menachine..........
Oxide of iron.........
Oxide of manganese

84

14

2

100

NILOMETER, sometimes called Niloscope, an instrument used among the ancients to measure the height of the water in the river Nile, in its periodical overflowings. It was first set up, it has been asserted, by Joseph, during his government in Egypt. The measure of it was sixteen cubits, this being the height, to which it must rise in order to insure the fruitfulness of the country.

NINTH, in music, an interval contain *ing an octave and a tone; also a name given to the chord consisting of a common chord with the eighth advanced one note. NIPA, in botany, a genus of the Appendix Palmæ class. Natural order of Palmæ or Palms. Essential character: male, spathe; corolla six-petalled: female, spathe; corolla none; drupes angular. There is but one species, viz. N. fruticans, the young palm, is without the trunk; but in the adult state, it is some feet in height; leaves pinnate; pinnas striated, margined, and smooth; flowers male and female on the same palm; but distinct on different peduncles; males several, lateral, inferior, on dichotomous peduncles, in spikes: females terminating, aggregate in a globular head, sessile. It is a native of Java and other islands in the East Indies, where the leaves are used for covering houses and making mats. The fruit is eaten both raw and preserved.

NIPPLES, in anatomy. See MAMMARY gland.

NISI PRIUS, a commission directed to the judges of assize, empowering them to try all questions of fact issuing out of the courts at Westminster, that are then ready for trial by jury. The original of which name is this: all causes commenced in the courts of Westminster-hall, are, by course of the courts, appointed to be tried on a day fixed in some Easter or Michaelmas term, by a jury returned from the county where the cause of action arises; but with this proviso, nisi prius justiciarii ad assisas capiendus venerint: that is, unless before the day prefixed, the judges of assize came into the county in question, which they always do in the vacation preceding each Easter and Michaelmas term, and there try the cause; and then, upon the return of the verdict given by the jury, to the court above, the judges there give judgment for the party for whom the verdict is found. All trials at law, in the civil courts and at the assizes, are tried by this process, and are called trials at nisi prius.

NISSOLIA, in botany, so named in ho

nour of Guill. Nissole, M. D., of Montpellier; a genus of the Diadelphia Decandria class and order. Natural order of Papilionacea, or Leguminosa. Essential character: calyx five-toothed; capsule oneseeded, ending in a ligulate wing. There are two species, viz. N. arborea, tree nissolia; and N. fruticosa, shrubby nissolia, both natives of Carthagena, in woods and coppices.

NITIDULA, in natural history, a genus of insects of the order Coleoptera. Anten næ clavate, the club solid; shell margined; head prominent; thorax a little flattened, margined. There are about forty-two spe cies enumerated by Gmelin, separated into sections according to the form of the lip. A. Lip cylindrical. B. Lip square. N. bipustulata, is oval, black; shells with a red dot. It inhabits Europe, and lives on carcases, meat, bacon, &c.

NITRARIA, in botany, a genus of the Dodecandria Monogynia class and order. Natural order of Ficoideæ, Jussieu. Es sential character: calyx five-cleft; corolla five-petalled, with the petals arched at top; stamina fifteen or more; drape one-seeded. There is but one species, viz. N. schoberi. Thick-leaved Nitraría.

NITRATES, in chemistry, salts formed of the nitric acid, and alkalies, earths, &c. They possess the following properties: soluble in water, and capable of crystallizing by cooling; when heated to redness with combustible bodies, a violent combustion and detonation is produced: sulphuric acid disengages from them fumes which have the odour of nitric acid: when heated with muriatic acid, oxymuriatic acid is driven off: they are decomposed by heat, and yield at first oxygen gas. There are twelve nitrates, of which the most important is the nitrate of potash, or nitre: this salt, known also by the name of salt-petre, is produced naturally in considerable quantities, particularly in Egpyt, and has been known from time immemorial. Roger Bacon mentions it under the name of nitre, in the thirteenth century. The importance of this substance for the purposes of war, has led chemists to seek the best means of preparing it, espe cially as nature has not laid up large magazines of it, as she has of other salts. It is now ascertained, that nothing more is necessary for the production of nitre than a basis of lime, heat, and an open, but not too free communication with dry atmospheric air.. When these circumstances combine, the acid is first formed, and afterwards the alkali. See NITRIC acid.

NITRE. See NITRATES. Nitre is found abundantly on the surface of the earth, in India, South America, South Africa, and even in some parts of Spain. In Germany and France it is obtained by means of artificial nitre-beds. These consist of the refuse of animal and vegetable bodies, undergoing putrefaction, mixed with calcareous and other earths. It has been ascertained, that if oxygen gas be presented to azote at the instant of its disengagement, nitric acid is formed. This seems to explain the origin of the acid in these beds. The azote, ⚫ disengaged from these putrifying animal substances, combines with the oxygen of the air. The potash is probably furnished, partly at least, by the vegetables and the soil. The nitre is extracted from these beds, by lixiviating the earthy matters with water. This water, when sufficiently impregnated, is evaporated, and a brown-coloured salt obtained, known by the name of crude nitre. It consists of nitre, com mon salt, nitrate of lime, and various other salts. The foreign salts are either separated by repeated crystallizations, or by washing the salt repeatedly with small quantities of water; for the foreign salts being more soluble, are taken up first. Nitre, when slowly evaporated, is obtained in six-sided prisms, terminated by six-sided pyramids; but for most purposes, it is preferred in an irregular mass, because in that state it contains less water. The specific gravity of nitre, as ascertained by Dr. Watson, is 1.9. Its taste is sharp, bitterish, and cooling. It is very brittle. It is soluble in seven times its weight of water, at the temperature of 60o, and in rather less than its own weight of boiling water. When exposed to a strong heat it melts, and congeals by cooling into an opaque mass, which has been called mineral crystal. Whenever it melts, it begins to disengage oxygen; and, by keeping it in a red heat, about the third of its weight of that gas may be obtained: towards the end of the process azotic gas is disengaged. If the heat be continued long enough, the salt is completely decomposed, and pure potash remains behind. It detonates more violently with combustible bodies than any of the other nitrates. When mixed with one-third part of its weight of charcoal, and thrown into a red-hot crucible, or when charcoal is thrown into red-hot nitre, detonation takes place, and one of the most brilliant combustions that can be exhibited. The residuum is carbonate of potash. A still more violent detonation takes place, if

Nitre furnishes all the nitric acid in all its states, employed either by chemists or artists: it is obtained by decomposing it by means of the sulphuric acid. When burnt with tartar, it yields a pure carbonate of potash. In the assaying of various ores it is indispensable, and is equally necessary in the analysis of many vegetable and animal substauces. But one of the most important compounds, formed by means of nitre, is gunpowder, which has completely changed the modern art of war. The discoverer of this compound, and the person who first thought of applying it to the purposes of war, are unknown. It is certain, however, that it was used in the fourteenth century. From certain ar chives, quoted by Wiegleb, it appears, that cannons were employed in Germany before the year 1372. No traces of it can be found in any European author, previous to the thirteenth century; but it seems to have been known to the Chinese long before that period. There is reason to believe, that cannons were used in the battle of Cressy, which was fought in 1346. They seem even to have been used three years earlier at the siege of Algesiras; but before this time, they must have been known in Germany, as there is a piece of ordnance at Amberg, on which is inscribed the year 1303. Roger Bacon, who died in 1292, knew the properties of gunpowder; but it does not follow that he was acquainted with its application to fire-armis. See GUNPOWDER. When three parts of nitre, two parts of potash, and one part of sulphur, all previously well dried, are mixed together in a warm mortar, the resulting compound is known by the name of fulminating powder. If a little of this powder be put into an iron spoon, and placed upon burning coals, or held above the flame of a candle, it gradually blackens, and at last melts. At that instant it explodes with a very violent report, and a strong impression is made upon the bottom of the spoon, as if it had been pressed down very violently. This sudden and violent combustion is occasioned by