a term frequently met with in the writings of physicians, chemists, &c. for certain medicines, or menstruums, in a liquid form, distinguished from each other by peculiar epithets; as,

Aqua alexiteria, a water distilled from mint, sea-wormwood, and angelica; and said to be good in malignant and pestilential cases.

Aqua alumina, alum-water, a solution of water and white vitriol; esteemed good in ulcers and cutaneous eruptions.

Aqua fortis, a corrosive liquor, made by distilling purified nitre with calcined vitriol, or rectified oil of vitriol, in a strong heat; the liquor, which rises in fumes red as blood, being collected, is the spirit of nitre or aqua fortis; which serves as a menstruum for dissolving of silver, and all other metals, except gold. But if sea-salt, or sal ammoniac be added to aqua fortis, it commences aqua regia. Aqua fortis is commonly held to have been invented about the year 1300; though others will have it to have been known in the time of Moses. It is serviceable to refiners, in separating silver from gold and copper; to the workers in mosaic, for staining and colouring their woods; to dyers, in their colours, particularly scarlet; and to other artists, for colouring bone and ivory. With aqua fortis bookbinders marble the covers of books, and diamond-cutters separate diamonds from metallic powders. It is also used in etching copper or brass plates. See Chemistry, Of the nitrous acid.

Aqua marina, a name by which the jewellers call the beryl, on account of its sea-green colour. See Beryl.

Aqua mercurialis, a solution of sublimate of mercury, and a little mercury, in aqua regia.

Aqua mirabilis, the wonderful water, is prepared of cloves, galangals, cubeb, mace, cardamoms, nutmegs, ginger, and spirit of wine, digested 24 hours, then distilled. It is a good and agreeable cordial.

Aqua omnium florum, in pharmacy, the water distilled from the dung of cows, when they go to graze; in English, All-flower-water.

Aqua regia, an acid corrosive spirit, so called, because it serves as a menstruum to dissolve gold, commonly esteemed the king of metals. Its basis, or essential ingredient, is common sea-salt, the only salt in nature which will operate on gold. It is commonly prepared by mixing common sea-salt, or sal ammoniac, or the spirit of them, with spirit of nitre, or common aqua fortis. See Chemistry, title, Of aqua regia.

Aqua secunda, denotes aqua fortis, which has been used to dissolve some metal.

Aqua sulphurata, the same with gas sulphuris. See Gas.

Aqua vitae, the water of life, a name given to malt spirits in contradistinction from brandy.

Aqua vitriolica caerulea, a solution of blue vitriol and alum, with some spirit of vitriol, in water; recommended in inflammatory and putrid cases.

Aquæ pavor, in medicine. See Hydrophobia.

Aqueduct, in hydraulics and architecture, a conveyance made for carrying water from one place to another. Those of the ancient Romans were surprisingly magnificent. That which Lewis XIV. built near Maintenon, for carrying the Bucq to Versailles, is perhaps the greatest now in the world: It is seven thousand fathoms long, with two thousand five hundred and sixty fathoms of elevation, and contains two hundred and forty-two arcades.

Aqua-negra, a small town of the Mantuan, in Italy, situated upon the Chiese, in 9° E. long. and 45° 10' N. lat.

Aquapendente, a city of the ecclesiastical state, in Italy, situated upon the river Paglia, abounding in waters.

Aquarians, in church-history, an ancient sect of heretics, who, under pretence of abstinence, made use of water instead of wine in the eucharist.

Aquarius, in astronomy, a constellation which makes the eleventh sign in the zodiac, marked thus ♍. See Astronomy.

Aquartia, in botany, a genus of the tetrandra monogynia class. There is only one species, called aculeata, a native of Europe.

Aquatic, in natural history, an appellation given to such things as live or grow in the water.

Aquaviva, a town of the kingdom of Naples, and province of Barri.

Aqueduct. See Aqueduct.

Aqueleia, a patriarchal city of Italy, near the end of the gulf of Venice, situated in 15° 30' E. long. and 46° 20' N. lat.

Aqueous, in a general sense, something partaking of the nature of water, or that abounds with it. Aqueous humour, in anatomy. See p. 289.

Aquifolium, in botany, the trivial name of a species of ilex. See Ilex.

Aquila, in ornithology, a synonyme of the falco, or eagle. See Falco.

Aquila, in astronomy, a constellation of the northern hemisphere. See Astronomy.

Aquila, in geography, a large city of Abruzzo, in the kingdom of Naples, situated in $14^\circ 20'$ E. long. and $42^\circ 40'$ N. lat.

Aquilegia, or Columbine, in botany, a genus of the polyandria pentagynia clas. It has no calix; the petals are five, and five horn-like nectaria are inserted betwixt each petal; it has also five separate capsules. There are three species of aquilegia, viz. the vulgaris, or common columbine, a native of Britain; the alpina, a native of Switzerland; and the Canadensis, a native of Virginia and Canada. The aquilegia is reckoned to be an aperient, but has long since given way to more powerful medicines.

Aquilicium, or Aquiliciana, in Roman antiquity, sacrifices performed in times of excessive drought, to obtain rain of the gods.

Aquiline, something belonging to, or resembling an eagle: Thus, an aquiline nose is one bent somewhat like an eagle's beak.

Aquino, a ruinous city in the province of Lavoro, in the kingdom of Naples, situated in $14^\circ 30'$ E. long. and $41^\circ 30'$ N. lat.

Ara, in astronomy, a southern constellation, containing eight stars.

Arabet, a town of Turkish Tartary, situated near the Palus Mæotis. It is fortified with two castles; and is the place where the khan keeps his stud of horses, which are reckoned to be about seven thousand in number.

Arabia, a large country of Asia, having Turkey on the north, Persia and the gulf of Persia on the east, the Indian ocean on the south, and the Red sea and isthmus of Suez on the west; and situated between $35^\circ$ and $60^\circ$ E. long. and between $12^\circ$ and $30^\circ$ N. lat.

Arabia, though subject to a great many different princes, is only considered by geographers as subdivided into the three grand divisions of Arabia Felix, Arabia Deserta, and Arabia Petrea.

Arabian, or Arabic, in a general sense, something belonging to Arabia: Thus we say, Arabian characters, Arabian language, &c. See Hebrew.

Gum Arabic, the name of a gum which distills from the Egyptian acacia tree. It is brought to us from Turkey, in small irregular masses or strings of a pale yellow colour. The true gum-arabic is rarely to be met with in the shops, gum-fenega being usually sold in place of it: This resembles the other, but is generally in large rough pieces. The true kind is preferred as a medicine; but the other is cheaper and stronger, and therefore preferred for mechanical uses. It is given, from a scruple to two drams, in hoarseness, a thin acrimonious state of the juices, and where the natural mucus of the intestines is abraded. It is likewise an ingredient in the white decoction, chalk julep, and other compositions.

Arabici, a sect of heretics, who held, that the soul both dies and rises again with the body.

Arabis, in botany, a genus of the tetradynamia filiformis clas. The generic mark is taken from four nectariferous glands which lie on the inside of each leaf of the calyx. There are eight species of arabis, none of which are natives of Britain, except the thaliana, or coded mouse-ear.

Arabism, in language, an idiom peculiar to the Arabian language.

Arable lands, those which are fit for tillage, or which have been formerly tilled.

Arack, Arrack, or Rack, a spirituous liquor imported from the E. Indies, used by way of dram and in punch. The word arack is an Indian name for strong waters of all kinds; for they call our spirits and brandy English arrack. But what we understand by the name arrack, is really no other than a spirit procured by distillation from a vegetable juice called toddy, which flows by incision out of the cocoa-nut tree. There are divers kinds of it; single, double, and treble distilled. The double distilled is commonly sent abroad, and is preferred to all other arracks of India.

Aracan, the capital city of a small kingdom, situated on the north-east part of the gulf of Bengal, in $93^\circ$ E. long. and $20^\circ 30'$ N. lat.

Aracari, in ornithology, the trivial name of a species of ramphastos. See Ramphastos.

Arach, the chief city of Arabia Petrea, situated in $49^\circ$ E. long. and $30^\circ 20'$ N. lat.

Arachis, in botany, a genus of the diadelphia decandra clas. There is only one species, viz. the hypogea, a native of America. The calyx is divided into two parts; and the capsule or pod is cylindrical, and contains two seeds.

Arachnoides, in anatomy, an appellation given to several membranes, as the tunic of the crystalline humour of the eye, the external lamina of the pia mater, and one of the coverings of the spinal marrow.

Aræometer, an instrument to measure the gravity of liquors, which is usually made of a thin glass ball, with a taper neck, sealed at the top, there being first as much mercury put into it as will keep it swimming in an exact posture. The neck is divided into two parts, which are numbered, that so by the depths of its descent into any liquor, its lightness may be known by these divisions.

Aræostyle, in architecture, a term used by Vitruvius, to signify the greatest interval which can be made between columns.

Aræotics, in medicine, remedies which rarefy the humours, and render them easy to be carried off by the pores of the skin.

Araf, among the Mahometans. See Arafat.

Arafat, a mountain of Arabia, near Mecca, where the Mahometans believe that Abraham offered to sacrifice Ishmael.

Aragon, a province of Spain, having Biscay and the Pyrenean mountains on the north, Catalonia on the the east, Valencia on the south, and the two Castiles on the west.