squire's business to carry the shield of the knight whom he served. The third and highest rank of chivalry was that of knighthood, which was not conferred before the 21st year, except in the case of distinguished birth or great achievements. The individual prepared himself by confessing, fasting, &c.; religious rites were performed; and then, after promising to be faithful, to protect ladies and orphans, never to lie, nor utter slander, to live in harmony with his equals, &c. (in France, there were 20 vows of knighthood) he received the accolade (q. v.), a slight blow on the neck with the flat of the sword, from the person who dubbed him a knight, who, at the same time, pronounced a formula to this effect: "I dub thee knight, in the name of God and St. Michael (or in the name of the Father, Son and Holy Ghost). Be faithful, bold and fortunate." This was often done on the eve of battle, to stimulate the new knight to deeds of valor, or, after the combat, to reward signal bravery.

Though no man of any reflection would wish for the return of the age of chivalry, yet we must remember that chivalry exercised, in some respects, a salutary influence at a time when governments were unsettled and laws little regarded. Though chivalry often carried the feelings of love and honor to a fanatical excess, yet it did much good by elevating them to the rank of deities; for the reverence paid to them principally prevented mankind, at this period of barbarous violence, from relapsing into barbarism; and, as the feudal system was unavoidable, it is well that its evils were somewhat alleviated by the spirit of chivalry. The influence which chivalry had on poetry was very great. The troubadours in the south of France, the trouveres in the north of the same country, the minstrels in England, the Minnesänger in Germany, sung the achievements of the knights who received them hospitably. (See Ballad.) In Provence arose the cours d'amour (q. v.), which decided the poetical contests of the knights. Amorous songs (chansons), duets (tensons), pastoral songs (pastourelles) and poetical colloquies (sirventes) were performed. In Germany, the chivalric spirit produced one of the most splendid and sublime epics, the Nibelungenlied. (q. v.) By the intercourse with the East, which grew up during the crusades, fairies, and all the wonders of enchantment, were introduced into the romantic or chivalric poetry. It is probable, however, that there existed

something of the same kind before the influence of the East was felt; for instance, the stories of the enchanter Merlin. Chivalric poetry, in our opinion, begins, as Schlegel has shown, with the mythological cyclus of king Arthur's round table. The second cyclus is that of Charlemagne and his paladins, his 12 peers, which remained the poetical foundation of chivalric poetry for many centuries. The cyclus of Amadis (q. v.), which belongs, perhaps, exclusively to Spain, does not rest on any historical ground. (For further information, see the article Chivalry, in the supplement to the Encyclopædia Britannica, written by sir Walter Scott, which contains many interesting facts, though the writer does not investigate very deeply the spirit of the institution. The article Chevalerie, in the Encyclopédie Moderne, is full of valuable information. The preface to lord Byron's Childe Harold should not be forgotten. See also Heeren's Essay on the Influence of the Crusades, translated into French from the German ; Büsching's Vorlesungen über Ritterzeit und Ritterwesen, Leipsic, 1823, 2 vols.; Mémoires sur l'ancienne Chevalerie, par Lacurne de Sainte-Palaye, Paris, 1826, 2 vols., with engravings; and last, but not least, Don Quixote. See also the article Tournament, and the other articles in this work connected with this subject.) We have dwelt so long on chivalry, as we think a correct view of it important to the understanding of many other subjects, and as some of our views may be new to our readers.

CHLADNI, Ernest Florence Frederic, one of the most distinguished proficients in the science of acoustics, born at Wittenberg, 1756, son of E. M. Chladenius, professor in the faculty of law at that place, received his first education in the royal school at Grimma, devoted himself afterwards at Wittenberg and Leipsic to law, and in the latter university was made doctor of philosophy in 1781, and, in 1782, doctor of law. After the death of his father, he abandoned the law, and devoted himself entirely to the study of nature, in which he had hitherto employed all his leisure hours. As an amateur of music, in which he received his first instruction at the age of 19 years, he observed that the theory of sound was much more neglected than the other branches of physics, and determined to supply this deficiency. The study of mathematics and physics, with reference to music, enabled him to present new views relative to the theory and practice of the art. Since 1787, he

has proved himself a profound naturalist, by several works, relating, principally, to sound and tone; e. g., his Discoveries in Regard to the Theory of Sound (Leipsic, 1787); Suggestions for promoting a better Explanation of the Theory of Sound, a work dedicated to the society of naturalists at Berlin. His principal composition, which is a classical work in its kind, is his Acoustics (Leipsic, 1802, 4to., with copperplates), preceded by the history of his discoveries in acoustics. (A French translation, revised by himself, appeared in Paris, 1809-Traité d'Acoustique.) He has also written Further Contributions to Acoustics (Leipsic, 1817), and Contributions to Practical Acoustics and the Theory of Constructing Instruments (Leipsic, 1822). Chladni is the inventor of the euphon and the clavicylinder. To make these instruments known, he spent 10 years in visiting the capital cities of Germany, Holland, France, Italy, Russia, Denmark, and everywhere gained the esteem of connoisseurs. He returned, in 1812, to his native place, where he is continually employed in new researches. He also commenced examinations of the bolides, or fiery meteors, the phenomena of which, as the flame, smoke, noise, &c., have little in common with the electrical phenomena with which they have been confounded. He endeavored to prove, in two treatises, On the Origin of the Iron Masses found by Pallas, and other similar Masses (Riga, 1794), and On Fiery Meteors (Vienna, 1819), 1. that the stories which represent masses of stone as having fallen on our earth are worthy of credit; and, 2. that these masses and meteors are not the productions of our earth, and come from beyond the region of our atmosphere. (See Meteoric Stones.)

CHLORIC ACID. (See Chlorine.) CHLORIDE OF NITROGEN. (See Chlorine.)

CHLORINE. The discovery of this gas was made in 1770, by Scheele, and named, by its discoverer, dephlogisticated marine acid. The term dephlogisticated had exactly the same import as that of oxygenated, soon afterwards introduced by Lavoisier. From its peculiar yellowish-green color, the appellation of chlorine (from Aoods, green) has been given to it. Chlorine gas is obtained by the action of muriatic acid on the peroxide of manganese. The most convenient method of preparing it is by mixing concentrated muriatic acid, contained in a glass flask, with half its weight of finely-powdered peroxide of manganese. On the application of a

moderate heat, the gas is evolved, and should be collected in inverted glass bottles, filled with warm water. In order to comprehend the theory of this process, it must be premised that muriatic acid consists of chlorine and hydrogen. The peroxide of manganese is composed of manganese and oxygen. When these compounds react on one another, the peroxide of manganese gives up a portion of its oxygen to the hydrogen of the muriatic acid, in consequence of which water is generated, and chlorine (the other ingredient in muriatic acid) is liberated. The method which is employed in the arts, and which is the most economical, is the following:-Three parts of common salt (muriate of soda) are intimately mingled with one of the peroxide of manganese, and to this mixture two parts of sulphuric acid, diluted with an equal weight of water, are then added. By the action of sulphuric acid on the muriate of soda, muriatic acid is disengaged, which reacts as before explained upon the peroxide of manganese; so that, instead of adding muriatic acid directly to the manganese, the materials for forming it are employed. Chlorine is gaseous under a common atmospheric pressure. It is twice and a half heavier than atmospheric air, or its specific gravity is 2.5. The gas has a yellowish-green color. Of all the gases, it is the most insupportable in its action on the lungs. When pure, it occasions immediate death if an animal is immersed in it; and even when largely diluted with common air, it cannot be respired with safety. It occasions a severe sense of stricture at the breast, which renders it impossible to make a full inspiration. This continues for a considerable time after it has been inspired, and has often produced a permanently injurious effect. When thoroughly dried, by exposure to fused chloride of calcium, it suffers no change, though cooled to 40°. When prepared over water, however, so as to contain a quantity of aqueous vapor, it condenses on the sides of the vessel even at a temperature of 40°; and, if surrounded by snow or ice, it shoots into acicular crystals of a bright-yellow color, and sometimes two inches in length, which remain attached to the sides of the vessel. This solid is a hydrate of chlorine, and, when heated to 50°, it melts into a yellowish oily fluid. Chlorine is absorbed by water, in a quantity which increases as the temperature diminishes. At 50°, the water takes up about twice its volume. The solution has a yellowish-green color, and

its odor is that of the gas itself. Its taste is rather styptic than sour, and the liquid, like the gas, has the property of destroying the vegetable colors. Hence it may be employed in bleaching. It is not changed by a boiling temperature. Solution of chlorine is decomposed, however, by exposure to the solar light; the chlorine attracts hydrogen from the water, forming muriatic acid, which remains dissolved, and pure oxygen is disengaged. Chlorine gas supports the combustion of a number of inflammable substances. A lighted taper burns in it, though feebly, with a red flame; phosphorus takes fire when immersed in it; and a number of the metals, as antimony, arsenic, copper and others, if introduced into it in leaves or filings, burn spontaneously. Potassium and sodium burn vividly in it. In these cases, the inflammable or metallic substances are believed simply to unite with the chlorine. Chlorine combines with many of these bases in more than one proportion. When in one proportion, the compound is called a chloride; when in two, a bi-chloride, or a deuto-chloride, &c. Whenever a metallic chloride, which is soluble in water, is thrown into that fluid, it is conceived to be instantly converted into a muriate; the water present is decomposed, its oxygen goes to the metallic base, and its hydrogen to the chlorine, and a muriate of an alkali, earth, or metallic oxide, is formed. Thus common salt, when dry, is a chloride of sodium: it is no salt, containing neither acid nor alkali, but, whenever it is dissolved in water, it is immediately transformed into a salt: the sodium attracts oxygen and becomes soda, and the chlorine takes hydrogen and becomes muriatic acid, and muriate of soda exists in the solution. When any of the compounds of chlorine, with inflammable substances or metals, are subjected to the action of a galvanic apparatus sufficiently powerful to decompose them, the chlorine is always evolved at the positive pole of the battery, and the base at the negative pole. In this respect, and in its power of supporting combustion, chlorine is analogous to oxygen. One of the most important chemical properties of chlorine is displayed in its action on the vegetable colors. Many of them it entirely destroys; and even those which are the most deep and permanent, such as the color of indigo, it renders faint, and changes to a light yellow or brown. This agency is exerted by it, both in its gaseous and its liquid form. The presence of water is, however, necessary to this. Hence, when the

gas destroys color, it must, probably, be enabled so to do by the hygrometric water it contains. It is accordingly found, that, when freed from this, it does not destroy the color of dry litmus paper. The destruction of color appears to be owing to the communication of the oxygen of the water present to the coloring matter: the chlorine attracts the hydrogen of the water to form muriatic acid, and the evolved oxygen unites with the coloring matter, and, by changing its constitution, alters its relation to light, so that the tint disappears. Berthollet applied this agency of chlorine to the process of bleaching, and with such success as to have entirely changed the manipulations of that art. The method of using it has been successively improved. It consisted, at first, in subjecting the thread or cloth to the action of the gas itself; but the effect, in this way, was unequally produced, and the strength and texture were sometimes injured. It was then applied, condensed by water, and in a certain state of dilution. The thread, or cloth, was prepared as in the old method of bleaching, by boiling first in water, and then in alkaline lye; it was then immersed in the diluted chlorine: this alternate application of alkali and chlorine was continued until the color was discharged. The offensive, suffocating odor of the gas rendered this mode of using it, however, scarcely practicable; the odor was found to be removed by condensing the chlorine by a weak solution of potash: lime, diffused in water, being more economical, was afterwards substituted. these forms, the chlorine, by decomposing water, and causing oxygen to be imparted to the coloring matter, weakens or discharges the color, and the coloring matter appears to be rendered more soluble in the alkaline solution, alternately applied, and of course more easily extracted by its action. More lately, a compound of chlorine and lime has been employed, prepared by exposing slacked lime to chlorine gas: the gas is quickly absorbed, and the chloride of lime, as it is called, being dissolved in water, forms the bleaching liquor now commonly employed, and which possesses many advantages. In using it, the colored cloth is first steeped in warm water to clean it, and is then repeatedly washed with a solution of caustic potash, so diluted that it cannot injure the texture of the cloth, and which is thrown upon it by a pump; the cloth is then washed and steeped in a very weak solution of chloride of lime, again washed, acted on by a boiling lye as before, and again steeped in

Under all

the solution; and these operations are performed alternately several times. The cloth is lastly immersed in very dilute sulphuric acid, which gives it a pure white color; after which it is washed and dried. Chloride of magnesia has been substituted, with great advantage, for that of lime, in whitening cloth for calico printing; the cloth, when lime is used, retaining a little of it, which, in the subsequent operation of clearing by immersion in weak sulphuric acid, forms sulphate of lime, which remains, and affects the colors when it is dyed; while the sulphate of magnesia is so soluble, that it is entirely removed. Chloride of alumine has been employed to discharge the color of the Turkey-red dye, which resists the action of other chlorides, and is only discharged by chlorine gas, by an operation very injurious to the workmen. Another important application of chlorine gas is that of destroying or neutralizing contagion. Acid vapors, sulphurous acid in particular, under the form of the fumes of burning sulphur, had often been employed for that purpose; but chlorine, from the facility with which it decomposes the different compound gases that contain the elements of vegetable and animal matter, and which may be supposed to constitute noxious effluvia, is superior to any other agent, and is now universally employed for the purposes of fumigation. It is the only agent which can administer relief in cases of asphyxia from sulphureted hydrogen; and it has been found useful, among such persons as are obliged to frequent places where contagious effluvia are constantly developed, to bathe the hands and arms with its solution. Chlorine, united with hydrogen, forms an important compound, called muriatic, or hydrochloric acid gas. (See Muriatic Acid.) With oxygen, it gives rise to four distinct compounds, which are remarkable for the feeble attraction of their constituent elements, notwithstanding the strong affinity of oxygen and chlorine for most elementary substances. These compounds are never met with in nature. Indeed, they cannot be formed by the direct combination of their constituents; and their decomposition is effected by the slightest causes. Notwithstanding this, their union is always regulated by the law of definite proportions, as appears from the following tabular view, illustrative of their composition.

Chlorine forms, along with nitrogen, one of the most explosive compounds yet known, and was the cause of serious accidents to M. Dulong, its discoverer, and afterwards to sir H. Davy. The chloride of nitrogen is formed from the action of chlorine on some salt of ammonia, chlorine and nitrogen being incapable of uniting, when presented to each other in their gaseous form. Its formation is owing to the decomposition of ammonia (a compound of hydrogen and nitrogen) by chlorine. The hydrogen of the ammonia unites with chlorine, and forms muriatic acid; while the nitrogen of the ammonia, being presented in its nascent state to chlorine, dissolved in the solution, enters into combination with it. The chloride of nitrogen has a specific gravity of 1.653; it does not congeal by the intense cold produced by a mixture of snow and salt. At a temperature between 200° and 212°, it explodes; and mere contact with most substances of a combustible nature causes detonation at common temperatures. The products of the explosion are chlorine and nitrogen. Three distinct compounds of chlorine and carbon have of late been made known by Faraday; but for an account of these, as well as of the chlorides of sulphur and of phosphorus, and the chloro-carbonic acid gas, the reader is referred to the larger treatises on chemistry, it being incompatible with the plan of the present work to enter into those details which are not connected with the useful arts, or which are not absolutely necessary in order to afford a correct idea of the mode of reasoning and general theory of the science.*

CHLORITE. (See Talc.)

CHOC (from the French choc, the violent meeting of two bodies), in military language, signifies a violent attack. It is generally applied to a charge of cavalry. To give such an attack its full effect, it is necessary, 1. that the line be preserved unbroken, so that the attack shall take effect at all points at the same time; 2. that the horses be strong and heavy, that their momentum may be great; 3. that the

A letter of M. Dauvergne to M. Gay-Lussac, in the Ann. de Chemie, recently published, states the effect of chlorine as an antidote of hydrocyanic acid. A cat, to which two drops of hydrocyanic acid were given through the lachrymal gland, was affected most violently by the poison. While the animal was in this condition, some chlorine was put into her mouth, and, one hour after, she was able to make a few tottering steps: the next morning the animal was quite well. It has also been lately stated, in the public journals, that the French physicians have found chlorine very effectual in preserving from the plague, if put on the linen, &c.

charge be made as swiftly as possible, not merely for the sake of the physical effect, but also of the moral effect which it has on the enemy. This swiftness, however, must be attained gradually, increasing as the distance diminishes. The charge commences with a short trot; a long trot follows; at the distance of 150 paces, this is increased to a gallop; and 50 paces from the enemy, the horse must be put to his speed. A choc, whether successful or not, is of short duration.

CHOCOLATE. (See Cacao.)

CHOCTAWS, or FLAT-HEADS; a tribe of Indians, residing between the Mississippi and the Tombigbee, partly in Alabama, but mostly in Mississippi. Their territory is bounded N. and N. E. by that of the Chickasaws. The country has a fertile soil, and is traversed by the upper waters of the Yazoo, Big Black, and Pearl rivers. Their number is estimated at about 20,000 or 25,000. They are a hardy, intrepid and ingenious race, and have made, within the last 20 years, great advances in agriculture and other arts of civilized life. They raise cotton, and manufacture it into cloth for their ordinary use, and often appear well clad in garments of their own making. In 1818, the American board of foreign missions established a mission among the Indians at Elliot, on the Yalo Busha, a branch of the Yazoo; and, since that period, eight other similar establishments have been formed. (See Indians.)

CHOCZIM (Chotschim); an important frontier fortress of Russia, on the right bank of the Dniester, opposite to Kaminiec, in Bessarabia, with 25,000 inhabitants and a considerable trade. The people are entirely employed in furnishing supplies for the army. The Turks caused Choczim to be regularly fortified, in 1718, by French engineers; but it was taken by the Russians in 1730, 1769 and 1788. As the Pruth, in Europe, is, at present, the boundary of the two empires, the situation of Choczim renders it of great importance as an arsenal and place of rendezvous.

CHODOWIECKI, Daniel Nicholas, a painter and engraver, born at Dantzick, 1726, received from his father, in his leisure hours, his first instruction in miniaturepainting, which he practised with great assiduity, in order to support his mother, after the death of his father. His first trials excited the astonishment of connoisseurs. A little engraving, the Play at Dice, in 1756, particularly attracted the attention of the academy of Berlin. Dur

ing the seven years' war, he engraved various subjects connected with it; among others, the Russian Prisoners at Berlin, which is now rare. The history of the unhappy Calas gave him an affecting subject for a picture, which, at the desire of all who saw it, he engraved on copper. The impressions of the year 1767 are particularly esteemed. Almost all the plates to Lavater's Physiognomical Fragments are from his designs. He engraved several of them himself. At last, scarcely a book appeared in Prussia, for which he did not engrave at least a vignette. The number of his engravings is more than 3000; but we must observe, that he was in the habit of making changes in his plates, after a number of copies had been struck off, so that all the copies of the same plate are not entirely alike. He must be considered the founder of a new art in Germany-that of representing modern figures. He died, Feb. 1, 1801, at Berlin, where he was director of the academy of arts. He was universally esteemed for his integrity.

CHOIR; that part of the church where the choristers sing. In some old churches, the seats of the choristers, and other parts of the choir, are ornamented with admirable carved work. (See Architecture, vol. I, page 343, sect. vii., Gothic style.)

CHOISEUL, Etienne François de; duke de Choiseul et d'Amboise; minister of state of Louis XV; born in 1719. When count of Stainville, he displayed a brilliant courage, and was rapidly promoted. His marriage with a rich heiress, sister to the duchess of Gontaut, and his intimate connexion with the marchioness de Pompadour, permitted him to indulge his ambitious hopes, which he never concealed. He went as ambassador to Rome, and, in 1756, in the same capacity, to Vienna. In 1757, he succeeded the cardinal Bernis, then minister of foreign affairs, who, from chagrin at the opposition which he experienced, after the conclusion of the much-contested alliance with Austria, resigned his office. The new minister quickly gained the greatest influence. He was made duke and peer, and administered, at the same time, the department of war. He afterwards resigned the department of foreign affairs to the count Choiseul, who subsequently became duke of Praslin. Without having the name, he was, in fact, prime minister, and conducted alone all the public affairs. From the beginning, he was unfriendly to the Jesuits, and united with the parliaments to