CIS bordered with a parapet, thrown up quite round the beseiger's camp, by way of security against any army that may attempt to relieve the place, as well as See FORTIFICAto prevent desertion. TION. CIRRUS, in botany, a clasper or tendril: that fine spiral string or fibre, put out from the foot-stalks, by which some plants, as the ivy and vine, fasten themselves to walls, pales, or trees, for support. It is ranked by Linnæus among the fulcra, or parts of plants that serve for support, protection and defence. Tendrils are sometimes placed opposite to the leaves, as in the vine; sometimes at the side of the foot-stalk of the leaf, as in the passion-flower; and sometimes, as in the winged-pea, they are emitted from the leaves themselves. CIRSOCELE, or hernia varicosa, in surgery, a preternatural distension or divarication of the spermatic veins in the process of the peritonæum. CISSAMPELOS, in botany, a genus of the Dioecia Monadelphia class and order. Natural order of Sarmentaceæ. Menispernia, Jussieu. Essential character: male, calyx four-leaved; corolla none; nectary wheel-shaped; stamina four, with cornate filaments. Female, calyx oneleafed, ligulate, roundish; corolla none; styles three; berry one-seeded. There are three species. CISSOID, in geometry, a curve of the second order, first invented by Diocles, whence it is called the cissoid of Diocles. Sir Isaac Newton, in his appendix "De Equationum Constructione lineari," gives the following elegant description of this curve, and at the same time shews how, by means of it, to find two mean proportionals, and the roots of a cubic equation, without any previous reduction. Let AG (Plate III. Miscel. fig. 12) be the diameter, and F the centre of the circle belonging to the cissoid; and from F draw FD, FP, at right angles to each other, and let F P be AG; then if the square PED be so moved that one side EP always passes through the point P, and the end D of the other side ED slides along the right line F D, the middle point C of the side ED will describe one leg G C of the cissoid; and by continuing out FD on the other side F, and turning the square about by a like operation, the other leg may be described. Draw the indefinite right line BC CISSOID, properties of the: it follows from genesis, that drawing the right lines PM, KL, perpendicular to AB, the lines A K, PN, AP, PM, as also AP, PN, AK, KL, are continual proportions, and therefore that AKP B, and PNIK. After the same manner it appears that the cissoid A MO bisects the semicircle A OB. Sir Isaac Newton, in his last letter to Mr. Leibnitz, has shewn how to find a right line equal to one of the legs of this curve by means of the hyperbola; but suppressed the investigation, which, however, may be seen in his fluxions. The cissoidal space contained under the diameter A B, the asymptote BC, and the curve A OZ of the cissoid, is triple that of the generating circle A O B. CISSUS, in botany, a genus of the Tetrandria Monogynia class and order. Natural order of Hederacex. Vites, Jus-. sieu. Essential character: berry oneseeded, surrounded by the calyx, and four-parted corolla. There are fifteen species; natives of both Indies. CISTUS, in botany, rock rose, or gum cistus, a genus of the Polyandria Monogynia class and order. Natural order of Rotaceæ. Cisti, Jussieu. Essential character: corolla five-petalled; calyx fiveleaved, with two of the leaflets smaller; capsule. There are sixty-six species, all of which are great ornaments to a garden; their flowers, though of short duration, are succeeded by fresh ones almost every day for about two months successively; the flowers are the size of a middling rose, but single, and of various colours; the plants continue their leaves all the year; they are most of them hardy enouch to live in the open air all the winter, except in very severe ones, which often destroy many of them; so that a plant or two of each sort should be kept in pots, and sheltered, to preserve the kinds. They are natives of warm climates. CITADEL, a place fortified with four, five, or six bastions, built on a convenient ground near a city, that it may command it in case of a rebellion. The city therefore is not fortified on the part opposite to the citadel, though the citadel is against the city. The best form for a ci- CITATION, in ecclesiastical courts, is CITHAREXYLUM, in botany, English fiddle-wood, a genus of the Didynamia Angiospermia class and order. Natural order of Personatæ. Vitices, Jussieu. Essential character: calyx five-toothed, bellform; corolla funnel-wheel-form; segments above, equal; berry two-seeded; seeds two-celled. There are five species; all natives of the West Indies. CITIES, rise of. After the fall of the Roman Empire, the proprietors of land lived principally on their own estates; the towns were inhabited by mechanics and tradesmen, chiefly in the condition of slaves. The people, to whom it was granted as a privilege that they might give away their own daughters in marriage without the consent of their lord, and that upon their death their own children and not their lord should succeed to their goods, must have previously been in entirely or nearly the same state of villanage as the occupiers of land in the country. They seem to have been much on a level with the hawkers and pedlars of modern times. They were generally obliged to pay some tax or toll for the privilege of selling their goods at particular places. As this source of revenue was thought of some importance by the feudal sovereigns and lords, in order to ensure its regular payment, they were induced in many instances to farm it out for a certain sum to the inhabitants of different towns, who, in order enforce its payment by the traders, were invested with the powers and privileges still possessed by the corporations of cities and boroughs. A town thus became a privileged place, of which traders were not only the inhabi tants, but the governors, at least in all that related to internal management. The turbulent feudal lords were often incited by the riches of the burghs to attempt to plunder their houses and warehouses; hence the owners naturally feared and hated the lords; the sovereigns of the different states of Europe, for other reasons, likewise hated and feared the lords; this served as a bond of union between the sovereigns and the corporate CIT towns, and enabled the towns to gain great privileges from those sovereigns King John in England; and in some inwho most needed their assistance, as stances to become independent, as was the case with the little republics of Italy, and the imperial cities in Germany. CITRATES, in chemistry, salts formed by the combination of the citric acid, and alkalies and earths; thus we have the citrate of potash, the citrate of soda, &c. See CITRIC ACID. CITRIC acid, in chemistry, is found in the juice of lemons and limes, and is that which gives it the sour taste. It is mixed, however, with mucilaginous and could not be obtained pure and crystalextractive matter. Scheele found that it juice, and that even the addition of alcolized by mere evaporation of the lemon hol did not separate completely the foreign matter. The process he followed lemon, by the addition of chalk. The is, to saturate the expressed juice of the citric acid, combining with the lime, forms an insoluble compound, which of course precipitates. This is well washed with warm water, until the water pass off colourless; and in this way the mucilage and extractive matter are abstracted. The citrate of lime is then subjected to the action of as much sulphuric acid, previously diluted, as is sufficient to saturate been employed. The citric acid is disenthe lime of the quantity of chalk that has gaged and dissolved by the water; the mixture is boiled for a few minutes, to facilitate the precipitation of the sulphate liquor is evaporated to the consistence of of lime, and is then filtered. The filtered syrup, and sulphate of lime separated during the evaporation being withdrawn; and, on cooling and standing for some time, the citric acid is obtained in needlelike crystals. Citric acid exists in a number of other fruits, from which it may be extracted, and much, it is said, of what is at present found in the shops is prepared from the juice of the lime. From Vauquelin's analysis of the pulp of the tamarind, it appears to be the chief acid constituent of that fruit; one pound of the common prepared pulp of the shops containing an ounce and a half, with smaller quantities of malic and tartaric acids. This acid is temperature, 100 parts of water dissolve very soluble in water. At a moderate 75 parts, cold being produced during the solution; at 212° it dissolves twice its weight of it. Like the other vegetable acids, its solution undergoes spontaneous CIT decomposition, though not very readily. The more powerful acids decompose it, though with some difficulty. Concentrated sulphuric acid converts it into acetic acid. Scheele remarked, that nitric acid did not convert it, as it did some of the other vegetable acids, into oxalic acid; but Fourcroy and Vauquelin have found that, when acted on by a large quantity of nitric acid for a long time, it affords a small portion of oxalic, with a larger portion of acetic acid. Citric acid combines with the alkalies and earths, forming salts denominated citrates. The citrate of potass is very soluble, and does not crystallize but with difficulty, and is deliquescent: its taste is purely saline, and rather mild. It contains 55.55 of acid, and 44.55 of alkali. Citrate of soda is likewise very soluble, requiring little more than its weight of water for its solution: it crystallizes in six-sided prisms, and the crystals are slightly efflorescent. Their taste is faintly saline; the proportions of the solid salt are 60.7 of acid, and 39.3 of soda. Citrate of ammonia is equally or even more soluble than the others, and does not crystallize but when its solution is much concentrated: the form of its crystals is an elongated prism. It consists of 62 of acid, and 38 of ammonia. The earthy citrates are in general less soluble. When the solution of barytes is poured into the acid, a precipitate, soluble in the liquid by agitation, is formed: when the whole is saturated, the salt is deposited at first in the form of a powder, which is covered afterwards with a kind of crystalline efflorescence, and which a large quantity of water dissolves. It consists of 50 of acid, and 50 of base. When the citric acid is saturated by lime, small crystals are deposited, which are very sparingly soluble: 100 parts contain 62.66 of acid, and 37.34 of lime. When saturated by magnesia, the concentrated solution does not easily crystallize regularly, but rather assumes the state of a white, opaque, and somewhat spongy salt. The proportions of the salt, are 66.66 of acid, and 33.34 of base. Vauquelin has likewise examined the action of citric acid on the metals. It does not dissolve silver; but it combines with its oxide, and forms a salt, insoluble, of a harsh and strong metallic taste, and which, like the other salts of silver, is blackened by light: it is also decomposed by heat, sometimes leaving metallic silver intermixed with charVOL. III. coal. It consists of 36 of acid, and 64 of Citric acid, in its crystallized state, can CITRUS, in botany, a genus of the Polyadelphia Icosandria class and order. Natural order of Bicornes. Aurantia, Jussieu. Essential character: calyx fivecleft; petals five, oblong; anthers twenty; filaments united into various bodies; berry nine-celled. There are five species; of which we shall notice the C. aurantium, orange-tree; of this there are sixty varieties. 1. Seville orange, which is a handsome tree, and the hardiest of any, as it shoots freely in this country, and yields fruit of excellent quality for domestic uses. 2. The China orange, which does not come to perfection here, but in warm countries it grows in the open ground. 3. The forbidden-fruit tree, which resembles the common orange, but the fruit when ripe is larger and longer than the biggest orange: besides these, there are the horned orange; the hermaphrodite orange; and the dwarf. C. Medica, the citron tree; of this species the lemon tree is accounted a variety; of which there are many sorts. The flowers of all the species appear in May and June, and the fruit continues setting in June and July, and ripens the year following. CIVET, a kind of perfume, bearing the name of the animal whence it is taken. The animal commonly known by the name of the civet, or civet-cat, is the viverra civetta of Linnæus. The civet is an animal of a wild disposition, and lives in the usual manner of others of this genus, preying on birds, the smaller quadrupeds, &c. It is a na tive of several parts of Africa and India: but not of America, as some have erroneously asserted; though it has been transported from the Phillippine Islands, and the coast of Guinea. This animal, as well as the zibet, though originally natives of the warm climates of Africa and Asia, are capable of subsisting in temperate and even in cold countries, provided they are defended from the injuries of Сс the weather, and fed with succulent nourishment. Numbers of them are kept in Holland, for the sake of procuring and selling the perfume which they yield, called civet, and sometimes erroneously confounded with musk. There is a considerable traffic of civet from Bassora, Calicut, and other places, where the animal that produces it is bred; though great part of the civet among us is furnished by the Dutch, who rear a considerable number of the animals. That which is obtained from Amsterdam is preferred to that which comes from the Levant, or India, because the latter is generally less pure. That brought from Guinea would be the best, if the negroes, as well as the Indians and Levanters, did not adulterate it with the juices of plants, or with labdanum, storax, and other balsamic and odoriferous drugs. The tity supplied depends much on the qualiquanty of the nourishment, and the appetite of the animal, which always produces more in proportion to the goodness of its food. See VIVERRA. CIVIL death, any thing that retrenches or cuts off a man from civil society, as a condemnation to the hulks, perpetual banishment, condemnation to death, outlawry, and excommunication. CIVIL law, is that law which every particular nation, commonwealth, or city, has established peculiarly for itself. The civil law is either written or unwritten; and the written law is public or private; public, which immediately regards the state of the commonwealth, as the enacting and execution of laws, consultations about war and peace, establishment of things relating to religion, &c.; private, that more immediately has respect to the concerns of every particular person. The unwritten law, is custom introduced by the tacit consent of the people only, without any particular establishment. The authority of it is great, and it is equal with a written law, if it be wholly uninterrupted, and of a long continu ance. commons. thing that is in the possession of another, CLAIM, a challenge of interest in any or at least out of a man's own; as claim by charter, by descent, &c. CLAIRAULT (ALEXIS CLAUDE), a cedemician, was born at Paris the 13th of lebrated French mathematician and acaMay, 1713. His father, a teacher of mateaching him even the letters of the althematics at Paris, was his sole instructor, phabet on the figures of Euclid's Elements, by which he was able to read and write at four years of age. By a similar stratagem it was that calculations were rendered familiar to him. At nine years Application of Algebra to Geometry; at of age he put into his hands Guisnee's ten he studied l'Hospital's Conic Sections; and between twelve and thirteen iences, concerning four new geometrical he read a memoir to the Academy of Scicurves of his own invention. About the same time he laid the first foundation of his work upon curves that have a double curvature, which he finished in 1729, at joint-Mechanician to the Academy in sixteen years of age. He was named Ad1731, at the age of eighteen, Associate in 1733, and Pensioner in 1738. During his connexion with the Academy, he had a great multitude of learned and ingenimoirs, besides several other works which ous communications inserted in their mehe published separately. In the year posed a prize on the subject of the lunar 1750, the Academy of Petersburg promotions, which Clairault obtained: and in a few years he obtained another prize on the same subject. He was during life a most active and indefatigable man. died in 1765, at the age of 52. His works are numerous, and his papers, inserted found in the year 1727, and also for alin the Memoirs of the Academy, may be variety of subjects, astronomical, mathemost every year till 1762; being upon a matical, optical, &c. He CLAMP in a ship, denotes a piece of timber applied to a mast or yard, to prevent the wood from bursting; and also a thick plank lying fore and aft under the beams of the first orlop, or second deck, and is the same that the rising timbers are to the deck. CLAMP is likewise the term for a pile of unburnt bricks built up for burning. These clamps are built much after the same manner as arches are built in kilns, viz. with a vacuity betwixt each brick's breadth for the fire to ascend by; but with this difference, that instead of arching, they truss over, or over-span; that is, the end of one brick is laid about half way over the end of another, and so till both sides meet within half a brick's length, and then a binding brick at the top finishes the arch. CLAMP nails, such nails as are used to fasten on clamps in the building or repairing of ships. CLAN, a term used in Scotland to denote a number of families of the same name, under a feudal chief, who protected them, and, in return for that protection, commanded their services as his followers, and led them to war, and on military excursions. CLAP net, a device for catching larks. You entice the birds with calls, and when they are within your distance, you pull a cord, and your net flies up and claps over them. CLARIFICATION, is the separation, by chemical means, of any liquid from substances suspended in it,and rendering it turbid. If a difference can be made between clarification and filtration, it is, that the latter is effcted by mere mechanical means, but the former either by heat or by certain additions, the action of which may be considered as chiefly chemical. The liquors subjected to clarifi cation are almost without exception those animal or vegetable juices, in which the matter that renders them turbid is so nearly of the same specific gravity with the liquor itself, that mere rest will not effect a separation. In these too the liquid is generally rendered thicker than usual by holding in solution much mucilage, which further entangles the turbid matter, and prevents it from sinking. Hence it is that vinous fermentation has so powerful an effect as a clarifier, since this process always implies the destruction of a portion of saccharine mucilage, and the consequent production of a thin limpid spirit. Coagulating substances are great clarifiers when mixed with any turbid liquor, the process of coagulation entangling with it all matters merely suspended and not dissolved, and carrying them either to the top in the form of a scum, or to the bottom in the form of a thick sediment, according to circumstances. Thus, to clarify muddy cider, the liquor is beaten up with a small quantity of fresh bullock's blood, and suffered to stand at rest for some hours, after which the liquor above is as clear as water, and almost as colourless, and at the bottom is a thick tough cake, consisting of the coagulated blood which has carried down with it all the opaque matter suspended in the liquor. Albuminous and gelatinous substances act in the same manner. The effect of white of egg in this way is known to every one. It should be first mixed with the turbid liquor without heat, and by agitation. Afterwards, on applying less than a boiling heat, the albumen of the egg coagulates, and carries up with it all the opaque particles, leaving the rest beautifully clear and limpid. Sometimes clarification takes place in a very unaccountable manner. Thus, it is well known that a handful of marl or clay will clarify a large cistern of muddy water, and marl is also used with advantage in clarifying vinous liquors. CLARINET, in music, a wind instrument of the reed kind, the scale of which, though it includes every semitone within its extremes,is virtually defective. Its lowest note is E, below F cliff, from which it is capable, in the hands of good solo performers, of ascending more than three octaves. Its powers through this compass are not every where equal; the player, therefore, has not a free choice in his keys, being generally confined to those of C and F, which are the only keys in which the clarinet is heard to advantage. The music for this instrument is accordingly usually written in those keys. CLARION, a kind of trumpet, whose tube is narrower, and its tone acuter and shriller, than that of the common trumpet. CLARO obscuro, or CLAIR obscure, in painting, the art of distributing to advantage the lights and shadows of a piece, both with regard to the easing of the eye, and the effect of the whole piece. See PAINTING. CLASS, an appellation given to the most general subdivisions of any thing. Thus, in the Linnæan system of natural history, the animal creation is divided into six classes, viz. MAMMALIA, AVES, AMPHIBIA, PISCES, INSECTA, VERMES. CLASS, in botany, denotes the primary division of plants into large groups, each of which is to be subdivided, by a regu |