AIGUILLON, duke d'; peer of France, and minister of foreign affairs under Louis XV; distinguished, as a courtier, by his ready wit, but destitute of almost all the qualities that constitute the statesman. During his ministry the partition of Poland took place; and till it was actually accomplished, d' A. knew nothing of this profligate project. Even Louis XV exclaimed, when it came to his knowledge, "Had Choiseul been here, this partition would never have taken place." D'A. was born in 1720. When he first appeared at the court of Louis, he struck the fancy of the duchess of Chateauroux, mistress of the king. She obtained him an appointment in the army in Italy. Af ter experiencing many alternations of favor and disgrace, he was admitted, through the influence of the countess du Barry, into the ministry with the abbé Terrai and the chancellor Maupeou, after Choiseul's downfall. His administration of the department of foreign affairs was disgraceful to France, which, under him, degenerated from the high diplomatic character she had hitherto sustained. He boasted of having brought about the revolution of Sweden in 1772, which now is made a matter of reproach to him. At the accession of Louis XVI, he was removed from the ministry. His place was supplied by the count of Vergennes, in 1774. D' A. was hated by the queen, was exiled in 1775, and died in banishment in his 80th year.

AILSA, or ELSA; a small, rocky island in the Frith of Clyde, near the W. coast of Scotland, of a conical form. It is a conspicuous object, 940 feet high, 7 miles from the shore, about 2 miles in circumference; lon. 5° 8′ W., lat. 55° 18′ N. Innumerable sea-fowl, many of which are good for the table or valuable on account of their feathers, frequent it; a few rabbits and goats live on its sterile surface. A ruinous castle stands on its summit, and is useful as a sea-mark. Excellent banks, well stocked with fish, surround it.

AINOS, or AINUS; the aborigines of Jesso and Saghalin, commonly called wild Kuriles, and supposed to be covered with hair in unnatural profusion. They are nearly black, and resemble the Kamtschadales, but have more regular features. The Chinese and Japanese say that they have immense beards; captain Broughton, who anchored at Endermo harbor, in Jesso, in 1797, remarks, that the bodies of the men are covered with long black and Krusenstern, the Russian navi

hair;

gator, mentions that a child of this description was seen in 1805, but that the parents had no such characteristics, and he denies that it is general. Other testimony, e. g. that of the early missionaries at Japan, seems to confirm this peculiarity of the A. The women are very ugly. The A. are of a mild, liberal disposition; their manners, however, are very little known. Polygamy is practised among them. Agriculture they know very little of. They fatten bears for winter provision. The A. were formerly independent, but are now in subjection to the Japanese.

AINSWORTH, Dr. Henry, an Englishman, distinguished himself, about 1590, among the Brownists. His knowledge of Hebrew, and his annotations on the Holy Scriptures, gained him much repu tation. He died about 1629, in Amster dam. He is said to have restored to a Jew a valuable diamond which he had lost. The only compensation which he asked was a conference with some Jewish rabbies on the prophecies of the Old Testament relating to the Messiah. The Jew promised to bring it about, but, failing of success, is said to have poisoned A. through shame and vexation.

AINSWORTH, Robert, born at Wood yale, in Lancashire, 1660, was master of a boarding-school at Bethnal-Green, whence he removed to Hackney and other places in the neighborhood of London. After acquiring a moderate fortune, he lived privately till 1743, when he died. He wrote the well-known Latin and English Dictionary; published in 1736; and in 1752, the fourth edition, under the care of Dr. Ward and William Younge, was enlarged to 2 vols. folio. Many editions with improvements have followed.

Arou; a group of 16 islands in the eastern seas, off the N. coast of Waggiou, and surrounded by a reef 50 miles in compass, which is penetrated by a deep channel on the north-west side. Aiou Baba is the largest, about 5 miles in circuit, 500 feet high, lon. 128° 25′ E., lat. 0° 32′ N. Fish, turtle and tropical fruits abound in these islands. They have some trade with the Chinese.

AIR (Greek, g; Latin, aër), in natural philosophy, is that fluid, transparent substance which surrounds our globe, reaching to a considerable height above its surface, perhaps 40 miles; and this ocean of air is the great laboratory in which md of the actions of life go on, and on the composition of which they depend. Though invisible, except in large masses, without smell or taste, yet it is a sub

stance possessing all the principal attributes of matter; it is impenetrable, ponderable, compressible, dilatable, perfectly elastic, and its particles are operated on like those of other bodies, by chemical action. To prove the impenetrability of the air, a very simple experiment is sufficient. Plunge a glass receiver perpendicularly into water, after having put under the receiver a piece of cork. However deep you may plunge the vessel, the water never reaches the top of it, though it diminishes the volume of the air; the liquid, therefore, cannot penetrate the air. The cork serves to show how high the water rises. In fact, the most common occurrences give constant proofs of the impenetrability of the air, and the theory of sailing, of windmills, &c. is based on that property of this fluid. (See Wind.) To prove that the air is ponderable, it is only necessary to weigh a large balloon, first empty, and afterwards filled with air. It has been found, that 100 cubic inches of air, very dry, taken at the temperature of 60°, and under the barometrical pressure of 30 inches, weighs 30.5 grains; and this weight is to that of water as 1 to 770. Galileo first discovered that air is ponderable, though several preceding philosophers seem to have had some suspicion of the fact. (See Galileo, Torricelli, Barometer.) In consequence of this quality of air, the atmosphere which surrounds us exerts a pressure on all points of the globe proportionate to its weight; this is the cause of the rise of liquids in sucking-pumps, siphons and the barometer. To show this pressure, plunge the orifice of an exhausted tube, closed at the other end, into a liquid. The liquid, yielding to the pressure of the external air, rises in the tube till the weight of its column is equal to that of the atmospheric column. In this experiment water will rise 33 feet, and mercury 29 inches, provided the place where the experiment is tried is nearly on a level with the sea; for the height varies with the weight of the column of air, which diminishes in proportion as we ascend above the level of the sea. The height of the column of mercury in the barometer, therefore, affords a good means of determining the elevation of any given place. The weight of the column of air, which presses constantly on a man of middle stature, is equal to 32,3434 pounds. But this weight does no injury, because it is counterbalanced by the reaction of the fluids, Which fill the interior cavities of the body. (See Air-pump.) That air is compressible, and

It

that the space which it occupies corresponds always to the pressure on it, has been shown by Mariotte. He took a bent glass tube, with legs of unequal length, exactly graduated; after having sealed the orifice of the shorter leg, he introduced a small quantity of mercury, sufficient to rise to an equal height in both legs. The air enclosed in the shorter leg then counterbalanced the atmospheric column. By raising the mercury in the longer leg to the height of 29 inches, the air in the shorter leg was compressed into half the space which it occupied at first. In other words, the weight of two atmospheres (the column of mercury being equal to one) compressed the air to this degree. Mariotte continued to pour mercury into the long leg, and found that the weight of 2, 3, 4, &c. atmospheres reduced the air confined in the shorter leg to 2, 3, 4, &c. of its primitive volume. In repeating this experiment, it is necessary to give time to the caloric which is disengaged to pass off. seems as if the compression of air would be indefinite, if we had sufficiently powerful means; but as yet we have only been able to reduce its volume to one eighth. (See Compression, Air-gun.) The dilatability of air consists in the tendency of a volume of confined air to occupy a greater space. In consequence, it presses equally in all directions on the sides of the vessel containing it, and this pressure increases or diminishes in proportion as the enclosed air is condensed or rarefied, provided the temperature remains the same. The dilatability of air has, according to the preceding experiment, no limits. A bladder, almost empty, will become inflated if placed in an exhausted receiver. Elasticity being the property of a body to resume its original form as soon as the force which changes it ceases, it is evident, from what we have said, that it is a property of air. The different applications made of air in the different branches of art are so various and numerous, that we cannot possibly enumerate them. Of the chemical properties of air, it will be sufficient to mention the following: the ancients believed it a simple body, one of the four elements; modern cheinists have discovered that it is composed of two bodies, apparently elementary,-oxygen and azote. most accurate experiments have shown that this fluid, taken from different parts of the globe, and even at a great height, is composed of 21 parts of oxygen, 78 of azote, 1 part of carbonic acid, and some

The

atoms of hydrogen. The air refracts the rays of light, and its power of refraction is in the ratio of its density. (See Refraction.) It is capable of acquiring electricity, and it refuses, when very dry, a free passage to the electricity which tends to escape from electrified bodies. (See Electricity.) When subjected to great heat or cold, it is dilated or condensed, but undergoes no change of properties. If it is suddenly compressed, much heat is disengaged, with a bright light. It enters bodies through the most minute pores, and adheres to them strongly; coal, particularly, absorbs a great quantity of air. (See Carbon.) Water and all liquids always contain it, and it can only be expelled by a strong heat. Almost all combustible bodies decompose it at a high temperature, which varies with the different substances. They absorb its oxygen with the disengagement of more or less caloric and light, and form acids or oxydes: phosphorus, however, combines at a low temperature with the oxygen and azote of the air, and produces, with the former, phosphorous acid; with the latter, phosphureted nitrogen: the moisture of the air and the melting of the phosphorus favor these combinations. When the air is brought into contact with animal and vegetable substances, it changes them immediately, particularly if it is moist, and gives to some of them acid properties; it bleaches flax, hemp, silk, and increases the brilliancy of many colors. It is indispensable to the life of all organic beings; animals respire it incessantly, and decompose it; a part of its oxygen is transformed into carbonic acid, and this combination produces caloric, which contributes principally to the preservation of animal heat. (See Respiration.) Vegetables imbibe the carbon, which the carbonic acid, diffused through the air, contains. The air is the agent of combustion; the particles of bodies combine with its oxygen, and evolve heat and light. (See Combustion.) Finally, the air is the principal medium of sound. (See Acoustics.) For further information, see the articles Atmosphere, Gas and Contagion.

AIR, in painting, deserves the most accurate study of the artist, particularly of the landscape painter, as it is the medium through which all objects are seen, and its density or transparency determines their appearance, both in respect to size and color. It softens the local colors, and renders them more or less decided or characterized, producing what

is technically called tone. The appearances produced by the interposition of the air differ with the climate, the season, and the time of the day; and landscape painters, who, in other respects, are not masters, have given the greatest charm to their pictures by a happy imitation of these appearances, even where the objects painted possessed in themselves very little attraction. Hackert, a German, who was a long time painter to the late king of Naples, excels, perhaps, in this branch of art, all modern painters. His views on this subject are given in his life by Göthe.

AIR, fixed. (See Gas.)

AIR, in music (in Italian, aria), at the present day, means a continuous melody, in which some lyric subject or passion is expressed. It was originally opposed to the irregular declamation of recitative, or the more staid action of choral music. Saumaise regards the term as derived from the Latin aëra. The air appertained, consequently, to measured music, and, whether constituted of one or of more voices, this measured style (if not choral) was denominated air. But in modern days, by way of distinction, the lyric melody of a single voice, accompanied by instruments, is its proper form of composition. Thus we find it in the higher order of musical works; as in cantatas, oratorios, operas, and also independently, in concertos. It should be constituted of euphonic simple lyric strains. An air formerly supposed as its ground-work a particular state of feeling or emotion, of a certain duration, expression and interest, to which the recitative is generally preparatory. Formerly, too, as essential to an air, a symphony, expressing the burden of the stanzas or couplets of the song (ritornello, or refrain), was introduced as tributary to the leading melody, which was followed by another and less elaborate part, forming the antithesis, to which was subsequently added a repetition of the first part. Since the days of Gluck and Mozart, these have declined, and other forms have been adopted, particularly by Mozart, more conformable to poetry, and more expressive of the sentiments and situation of the singer. Still Mozart could not entirely withstand the prevailing taste, with reference to which he produced numerous bravura airs, not always in character, yet not wanting in expression and effect. Another form of airs are the cavatinos (or single strains), lately introduced by the Italians, and calculated to add grace and embellishment

receives and holds substances on which experiments are to be made. If a little unctuous matter be rubbed upon the edge of the receiver R, and it be pressed with a slight circular motion upon the plate S S, it will be brought into such close contact as to be air-tight. In the middle is an opening A, which communicates by a tube A B with a hollow eylinder or barrel, in which a solid piston P is moved. The piston-rod C moves in an air-tight collar D, and at the bottom of the cylinder a valve V is placed, opening freely outward, but immediately closed by any pressure from without. There is thus a free communication between the receiver R, the tube A B and the exhausting barrel BV. This communication extends in the same manner to a second similar barrel X V. When the piston C P is pressed down, and has passed the opening at B, the air in the barrel B V will be enclosed, and will be compressed by the piston. As it will thus be made to occupy a smaller space than before, its density, and consequently its elasticity, will be increased. It will therefore press downwards upon the valve V with a greater force than that by which the valve is pressed upwards by the external air. This superior elastic force will open the valve, through which, as the piston descends, the air in the bar

rel will be driven into the atmosphere. If the piston be pushed quite to the bottom, the whole air in the barrel will be thus expelled. The moment the piston begins to ascend, the pressure of the air from without closes the valve completely. None of the external air can enter; and, as the piston ascends, a vacuum is left beneath it; but, when it rises beyond the opening B, the air in the receiver R and the tube A B expands, by its elasticity, so as to fill the barrel B V. A second depression of the piston will expel the air contained in the barrel, and the process may be continued at pleasure. The communication between the barrels and the receiver may be closed by a stop-cock at G. It is evidently only in consequence of the elasticity of the air that it expands and fills the barrel, diffusing itself equally throughout the cavity in which it is contained. The operation of the machine depends, therefore, on the elasticity of the air, and it is obvious that a perfect vacuum cannot be formed by it in the receiver, as only a part of the air is each time expelled, and a portion must always remain after each depression of the piston. The degree of rarefaction produced by the machine may, however, be easily calculated. Suppose that the barrel contains one third as much as the receiver and tube together, and, therefore, that it contains one fourth of the whole air within the valve V. Upon one depression of the piston, this fourth part will be expelled, and three fourths of the original quantity will remain. One fourth of this remaining quantity will in like manner be expelled by the second depression of the piston, which is equal to three sixteenths of the original quantity. By calculating in this way, it will be found that, after 30 depressions of the piston, only one 3096th part of the original quantity will be left in the receiver. The rarefaction may thus be carried so far that the elasticity of the air pressed down by the piston shall not be sufficient to force open the valve. To show how far the exhaustion has been carried at any particular point of the process, a barometer-gauge is connected with the machine. This is a glass tube, opening at E into the receiver, and at F immersed in a cistern of mercury. As the rarefaction proceeds, the mercury rises from the pressure of the external air, and indicates how far this pressure exceeds that from within the receiver, that is, the degree of exhaustion. Both pistons are worked by the wheel H and

winch Y, by means of the rack or tooth-work on the piston-rods. When one piston is raised, the other is depressed. The winch is then turned in the opposite direction, and the piston which had been raised is depressed, and the other raised. When the rarefaction of the air within the barrels is considerable, the pressure of the atmosphere upon each piston is not resisted from within, and therefore opposes its ascent. But this pressure is not felt by the operator, as the pressure upon one piston counterbalances that upon the other. The elasticity of the air is proved by the action of the machine. Its pressure is proved by the great firmness with which the receiver is pressed upon the plate S S during the rarefaction of the air within. If any animal is placed beneath the receiver, and the air exhausted, he dies almost immediately; a lighted candle under the exhausted receiver immediately goes out. Air is thus shown to be necessary to animal life and to combustion. Ă bell, suspended from a silken thread beneath the exhausted receiver, on being struck, cannot be heard. If the bell be in one receiver, from which the air is not exhausted, but which is within an exhausted receiver, it still cannot be heard. Air is therefore necessary to the production and to the propagation of sound. A shrivelled apple or cranberry, placed beneath an exhausted receiver, becomes as plump as if quite fresh. They are thus shown to be full of elastic air. A great variety of experiments may be made, which are very interesting, but too numerous to be described. The air-pump was invented by Otto de Guericke, burgomaster of Magdeburg, about the year 1654. Modifications and improvements were afterwards made by Boyle, Hawksbee, Morton and many others. It is made in various forms, one of the simplest of which is that already described.

AIR-TRUNK; a contrivance by Dr. Hales to prevent the stagnation of putrid effluvia in jails, or any apartments where many people are collected. It consists of a long, square trunk, open at both ends, one of which is inserted into the ceiling of the room, and the other extends a considerable distance beyond the roof. Through this trunk a continued circulation is carried on, because the putrid effluvia are much lighter than the pure atmosphere. Dr. Keil estimates these effluvia arising from one man in 24 hours at not less than 39 ounces. These