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the immediate consequence of the less energetic caustics. In both cases, suppuration occurs sooner or later, and separates the disorganized from the surrounding parts. Almost all the substances used as caustics have only a local action: some, however, are capable of being absorbed, and of exercising a deleterious action on the economy in general: arsenical preparations are an instance of it. The employment of caustics is now confined to a small number of cases. The actual cautery and the knife are, in general, preferred to them. They are used principally in order to establish issues, particularly in cases in which it is necessary to produce a powerful derivation; to stop the progress of certain gangrenous affections, such as anthrax; to open certain indolent abscesses; to change the mode of vitality of the skin in some cancerous or herpetic ulcers; to destroy the excrescences of wounds or proud flesh; and, finally, to prevent the absorption of the virus deposited at the surface of poisoned wounds.

CAUSTIC POTASSA (potassa fusa; lapis causticus); impure hydrate of protoxyde of potassium; caustic kali with lime; common caustic. This is seen in flat, irregular, brittle pieces, or in round sticks, like the nitrate of silver; of a grayishwhite, sometimes reddish; of a savor extremely caustic, and a slight odor sui generis. This substance is extremely caustic; it decomposes quickly the parts with which it is put in contact, and leaves on the skin a soft, grayish eschar, which comes off slowly. Taken internally, it acts in the same way as all corrosive poisons: it has, nevertheless, been administered, in very dilute solutions, as an antacid, diuretic, and lithontriptic. It has succeeded in the gravel, in nephritic colics, and other affections proceeding from superabundance of uric acid. It has been recommended, likewise, in the treatment of scrofula, and in some diseases of the skin, such as leprosy, &c. This solution, even when very diluted, soon irritates the stomach, and brings on anorexia, which prevents it from being used for any length of time.

CAUSTIC SODA (soda); protoxyde of sodium. Its physical properties are similar to those of potassa, and it may be used with advantage as a succedaneum when employed as a caustic. In fact, the - sub-carbonate, which forms during its action on the skin, is not deliquescent, as that of potassa, and, consequently, is not subject to spread.

CAVALCANTI, Guido ; a Florentine philosopher and poet of the 13th century, the friend of Dante, and, like him, a zealous Ghibelline. When the dissensions of the Guelfs and Ghibellines disturbed the public peace of Florence, the citizens banished the chiefs of both parties. The Ghibellines were exiled to Sarzana. On account of the unhealthy air of that place, they were permitted to return; but Cavalcanti had contracted a disease of which he died (1300) at Florence. In his youth, he made a pilgrimage to St. Jago de Compostella, in Galicia. Returning home through France, he fell in love, at Toulouse, with a young lady of the name of Mandetta. To her most of his verses which we possess are addressed. They are remarkable, considering the period at which they were written, for their beautiful style. His Canzone d'Amore has gained him the most fame. The learned cardinal Egidio Colonna, and some others, have made commentaries on it. His Rime, published by Cicciaporci, appeared at Florence in 1813.

CAVALIER, in fortification, is a work generally raised within the body of the place, 10 or 12 feet higher than the rest of the works. It is most commonly situated within the bastion, and made much in the same form. Sometimes the cavaliers are placed in the gorges, or on the middle of the curtain; they are then made in the form of a horse-shoe. Their use is to command all the adjacent works and surrounding country. They are seldom made except when a rising ground overlooks some of the works. In modern times, it is considered that cavaliers in a bastion occupy too much room, render retrenchments impossible, and, unless a ditch separates the cavalier from the parapet of the bastion, cause the grenades to fall upon the defenders of the latter; for which reasons it is considered best to put them on the curtains or behind the bastions.

CAVALRY; one of the three great classes of troops, and a formidable power in the hands of a leader who knows how to employ it with effect. This requires a bold and active spirit, able to avail itself, with quickness and decision, of every opportunity. The efficacy of cavalry arises particularly from the moral impression which it produces on the enemy. This is greater in proportion to the size of the mass and the rapidity of its motion. Its adaptation to speedy movements is another great advantage, which enables a commander to avail himself immediately of a decisive moment, when the enemy

exposes a weak point, or when disorder appears in his ranks. It is a very important instrument in completing the defeat of an enemy, in disconcerting him by a sudden attack, or overthrowing him by a powerful shock. The use of cavalry is, it is true, oftentimes limited by the nature of the ground. In forests, in mountainous districts, on a marshy soil, &c., it is of but little avail in large bodies. In modern times, cavalry has been led against intrenchments, but only to its own destruction. In some instances, too, the cavalry has been dismounted, and employed as infantry; which may, on peculiar occasions, be advisable, but, on the whole, is contrary to their nature and purpose, and, if made a part of their duty, like other half measures, is usually disadvantageous. It is also unadvisable to keep large bodies of cavalry united during a campaign. They are to be collected in large masses only for particular objects. To keep them together the whole time would be troublesome, and their maintenance frequently attended with difficulty.—The unequal size of the horse, the very great diversity in his strength and breed, have at all times rendered it necessary to divide the cavalry into light and heavy horse. There is sometimes, also, an intermediate class. These different sorts are employed for different purposes. The heavy cavalry, with defensive armor (cuirassiers), is more frequently employed in mass, where force is requisite; the lighter troops are used singly, and in small detachments, where swiftness and continued effort are required. Nevertheless, cuirassiers and dragoons, lancers and hussars, mounted riflemen and chevaux legers, must, in the main points, be equally exercised in the duties appertaining to cavalry, and must be able to fight in the line as well as singly. The use of cavalry is probably nearly as ancient as war itself; for in those countries where horses thrive most, and man may be said to live on horseback, he has always preferred to fight on horseback. The Egyptians are said to have had cavalry before the time of Moses. The Israelites, when at war with their neighbors, often had to encounter cavalry, but were afraid to mount horses until the time of Solomon. The Greeks appear not to have introduced cavalry into their armies till the second Messenian war, and, even after that time, had comparatively few; but with them it was considered the most respectable class of troops, in which only the wealthy citizens served. 2

VOL. III.

The Persian cavalry, and, at a later period, the Macedonian, were much more numerous. The Romans learnt its use from Pyrrhus and the Carthaginians. At a later period, the cavalry of the Gauls was particularly good. In the middle ages, the knights fought only on horseback, and disdained the foot-service. At this period, however, regular warfare was unknown, and was only gradually restored in the progress of time. After the introduction of artillery, although cavalry was used, yet its manœuvres were awkward and inefficient. The genius of Gustavus Adolphus first perceived the important use which could be made of it. He was without the heavy cavalry, which, since the time of chivalry, had gone out of use; but he found that the advantage of this species of troops did not consist in its weight, but in its quickness of motion. With reference to this, he formed his regiments of horse, and showed their real utility; but it was left to Seidlitz, a general of Frederic the Great, to display this most fully. Napoleon appears to have been well aware of the great value of cavalry in large masses, but he often sacrificed them unsparingly. This, together with certain erroneous dispositions which had crept into some armies, and had caused the cavalry to fail in services on which they ought never to have been put, and which were sometimes performed as well or better by other troops, gave rise, of late years, to doubts concerning their utility, which, however, are now abandoned. The writings of general Bismark, on the subject of cavalry, are valuable ; as are also the Nachrichten und Betrachtungen über die Thaten und Schicksale der Reiterei in den Feldzügen Friederich II und in denen neuerer Zeit (Statements and Observations respecting the Conduct and Fate of the Cavalry in the Campaigns of Frederic II and in those of a later Period). In the north of Europe, lances are now common among the light cavalry, as they have proved a formidable weapon when skilfully used. They will, no doubt, effect a change in the arms, and even in the organization, of the infantry, who can do little against lancers, if rain prevents them from firing. In the Prussian cavalry, which is among the finest in the world, lancers are very numerous. A French author calls the cavalry, very appropriately, l'arme du moment; because they are peculiarly fitted to take advantage of decisive moments. A moment may occur, when a great victory can be decided by the sudden irruption of a body

of cavalry, and the next moment it may be too late. A commander of cavalry must therefore be possessed of the rare courage which shrinks not from responsibility. Many battles in the late wars prove the truth of these remarks. Napoleon won the battle of Marengo chiefly by Kellermann's daring charge, at the head of 500 horse, on an enemy almost sure of victory. The campaigns in Russia, and the following war in Germany, showed the great disadvantage under which an army labors from the want of cavalry. Napoleon failed to follow up his advantages after the victories of Lützen and Dresden, chiefly because his cavalry were raw and inexperienced. The training of cavalry is much slower than that of infantry. The best cavalry is now generally considered to be the Prussian and some species of the Russian. The French never were good horsemen, and the English have not kept pace with the numerous improvements introduced by the wars on the continent. It is a fact of interest, that the more civilization takes root among a nation, the more importance is given to infantry. All savage nations begin with cavalry, if they have horses. At present, infantry is the most numerous class of troops, though, before the time of Charles V, they were little esteemed.

CAVANILLES, Antonio Joseph; a clergyman and botanist; born 1745, at Valencia; died in Madrid, 1804; studied with the Jesuits and at the university of Valen

cia.

In 1777, he went to Paris with the children of the duke of Infantado, and remained there 12 years, occupied with the study of several sciences, but chiefly with botany. He published there, in 1784, Observations on the Article Spain in the New Encyclopedia, written with as much patriotism as profound reasoning. In the following year, he commenced his great botanical work, Monadelphie Classis Dissertationes decem (Paris, 1785-89, Madrid, 1790, 4to., with engravings). After his return to Spain, he wrote another beautiful work, Icones et Descriptiones Plantarum, quæ aut Sponte in Hispania crescunt aut in Hortis hospitantur (Madrid, 1791-99, 6 vols., folio, with 601 engravings). It contains a number of new genera and species, natives of Spain, America, India and New Holland. In pursuance of a commission from the king, Cavanilles travelled in Valencia, and collected the materials for his Observaciones sobre la Historia Natural, Geografia, Agricultura, Poblacion, etc., del Reyno de Valencia (Madrid, 1795-97, 2 vols., folio,

with copperplates, from the drawings of the author). The work was published at the expense of the king, and intended as the first part of a similar work to embrace the whole of Spain. Thunberg has named a family of plants Cavanilla. Cavanilles died in 1804.

CAVATINA; a short air without a return or second part, and which is sometimes relieved with recitative.

In

CAVE, or GROTTO; an opening produced by nature in the solid crust of the earth. Caves are principally met with in limestone of the transition and flotz period, in gypsum, sometimes in sandstone, and in volcanic rocks (basalt, lava, tufa, &c.); sometimes they are the effect of crystallization. The form of the caves depends partly upon the nature of the substance in which they exist; but it is frequently altered by external causes. reference to their internal construction, the hollows in the earth may be divided into three classes: those of the first are wide clefts; those of the second admit the day-light at both ends, and form natural passages, which sometimes serve the rivers as beds; the third and most common class consists of those which form a line of grottoes, about of an equal height, running in the same direction, and connected by passages more or less narrow. Out of some grottoes, rivers take their course; others, again, admit rivers, or may be said to swallow them for a space, till they again emerge. There are many and various causes for the formation of caves. Those in limestone and gypsum are unquestionably the results of the dissolving power of water; in fact, the almost perfectly uniform direction, the gentle and equable declivity of most caves, appear to be the effect of the long continuance of water in them, the action of which has widened the existing crevices. In trachyt and lava, caves appear to have been produced by the effects of gas. The caves of gypsum often contain foul air; the caves of limestone, various figures of stalactites, produced by the deposit of the lime dissolved in the water. The most of these lime caves contain remnants of bones of animals, viz., of hyænas, elephants, bears. Many caves are remarkable only on account of their great size, or sublime from the awful gloom which pervades them, and the echoes which roll like thunder through their vaulted passages. Some are of great depth, as that of Fredericshall, in Norway, which is calculated to be 11,000 feet in depth. One of the grandest natural caverns known is

Fingal's cave, in Staffa, one of the Western islands of Scotland. Its sides are formed of ranges of basaltic columns, which are almost as regular as hewn stone. The grotto of Antiparos, on the island of the same name, in the Archipelago, is celebrated for its magnificence. The passage at the entrance glitters, in the torch-light, as if it were studded with diamonds. The roof is adorned with stalactites, many of them 20 feet long, and hung with festoons of various forms and brilliant appearance. In some parts, immense columns descend to the floor; others present the appearance of trees and brooks turned to marble. The Peak cavern, in Derbyshire, England, is also a celebrated curiosity of this kind. It is nearly half a mile in length, and, at its lowest part, 600 feet below the surface. The caves of Kirkdale, in England, and Gailenreuth, in Germany, are remarkable for the quantities of bones of the elephant, rhinoceros and hyæna, found in them. The mine of fluor spar, in Castleton, Derbyshire, passes through several stalactic caverns. Other caverns in England contain subterraneous cascades. In the rock of Gibraltar, there are a number of stalactic caverns, of which the principal is St. Michael's cave, 1000 feet above the sea. The most famous caves in Germany are those of Baumann and Bielstein, in the Hartz. (See Buckland's Reliquiæ Diluviana, London, 1823.) The most celebrated caves in the U. States are Madison's cave, in Rockingham county, Virginia, extending 300 feet into the earth, and adorned with beautiful incrustations of stalactites; Wier's cave, in the same county, extending 800 yards, but extremely irregular in its course and size. Near Corydon, Indiana, is a cave, which has been explored for the distance of several miles, celebrated for producing Epsom salts. In Kentucky and Tennessee, caves are numerous, which appear to have been used as burial-places. In the north-west part of Georgia is a cave, called Nickojack cave, 50 feet high and 100 wide, which has been explored to the distance of three miles. A stream of considerable size runs through it, which is interrupted by a fall. Caves are sometimes found which exhale poisonous vapors. The most remarkable known is the Grotto del Cane, a small cave near Naples. In Iceland, there are many caves, formed by the lava from its volcanoes. In the volcanic country near Rome, there are many natural cavities of great extent and coolness, which are sometimes resorted to as a refuge from the heat. The grottoes in the Cevennes mountains

in France are both numerous and extensive, and abound in objects of curiosity. In South America is the cavern of Guacharo, which is said to extend for leagues. CAVE, Edward, an English printer, the founder of the Gentleman's Magazine, was born in 1691. His first occupation was that of clerk to a collector of the excise in the country. He then went to London, and put himself apprentice to a printer. When his indentures expired, he obtained a place in the post-office, and employed his leisure in writing for the newspapers. He published, in January, 1731, the first number of the Gentleman's Magazine, which has continued till this day, amid the crowd of magazines which have been established since. Cave was deprived of his place in the post-office on account of his having resisted some abuses relative to the privilege of franking letters. He died January 10, 1754.

CAVENDISH, Thomas; an eminent navigator in the reign of Elizabeth. Having consumed his property by his early extravagances, he collected three small vessels for the purpose of making a predatory voyage to the Spanish colonies. He sailed from Plymouth in 1586, took and destroyed many vessels, ravaged the coasts of Chile, Peru and New Spain, and returned by the cape of Good Hope, having circumnavigated the globe in 2 years and 49 days, the shortest period in which it had then been effected. In 1591, he set sail on a similar expedition, in which his principal success was the capture of the town of Santos, in Brazil. After suffering many hardships, he died, in 1592.

CAVENDISH, William, duke of Newcastle, was born in 1592, and educated by his father, on whose death he was raised to the peerage. On the approach of hostilities between the crown and parliament, he embraced the royal cause, and was invested with a commission, constituting him general of all his majesty's forces raised north of the Trent, with very ample powers. With great exertions, and the expenditure of large sums from his private fortune, he levied a considerable army, with which, for some time, he maintained the king's cause in the north. In military matters, he depended chiefly on his principal officers, whilst he himself indulged in the courtly pleasures and literary society to which he was attached. He obtained a complete victory over lord Fairfax on Adderton-heath, and, on the approach of the Scotch army, and its junction with the parliamentary forces, threw himself into York. Having been relieved by

prince Rupert, he was present at the battle of Marston-moor, after which he left the kingdom. He returned, after an absence of 18 years, and was rewarded for his services and sufferings with the dignity of duke. He died in 1676.

CAVENDISH, William, first duke of Devonshire, was the son of William, third earl of Devonshire. He was born in 1640, and instructed with great care in classical literature. On various occasions, he distinguished himself by his spirit and valor, and, in 1677, began that opposition to the arbitrary measures of the ministers of Charles II, which caused him to be regarded as one of the most determined friends of the liberties of his country. Intimately connected with lord Russel, he joined him in his efforts for the security of free government and the Protestant religion. On the trial of lord Russel, he appeared as a witness in his favor, and offered to assist him in escaping, after he had been sentenced to death, by changing clothes with him in prison. In 1684, having succeeded to his father's title, and being regarded as one of the most formidable opponents of the arbitrary designs of king James II, attempts were made to intimidate him, but without success. Having been insulted by a minion of the king, he dragged him from the chamber by the nose in the royal presence. He took an active part in promoting the revolution, and was one of the first who declared for the prince of Orange. His services were rewarded with the dignity of duke of Devonshire. He still, however, maintained an independent bearing in parliament. He died in 1707.

CAVENDISH, Henry, born 1731, the son of lord Charles Cavendish, and grandson of the second duke of Devonshire, devoted himself exclusively to the sciences, and acquired a distinguished rank among those learned men who have most contributed to the progress of chemistry. He discovered the peculiar properties of hydrogen, and the qualities by which it is distinguished from atmospheric air. To him we owe the important discovery of the composition of water. Scheele had already observed that, when oxygen is mixed with double the quantity of hydrogen, this mixture burns with an explosion, without any visible residuum. Cavendish repeated this experiment with the accuracy for which he was distinguished. He confined both the gases in dry earthen vessels, to prevent the escape of the product of their combustion, and found that this residuum was water, the weight of

which was equal to the sum of the weights of the two gases. Lavoisier confirmed this conclusion in later times. The same spirit of accuracy in his experiments led Cavendish to another discovery, which had escaped Priestley. The latter had observed that a quantity of atmospheric air, confined in a tube, through which the electric spark was transmitted, lost in volume, and formed an acid, which reddened the tincture of litmus; but he carried this experiment no farther. Cavendish repeated the experiment, by confining in the tube a solution of pure potash, which absorbed the acid, and thus proved it to be nitric acid. The analysis of the air, which remained in the tube after the experiment, showed that the weight of the oxygen and azote, which had disappeared, was equal to the weight of the acid thus formed. He easily determined the proportion of the azote to the oxygen, which was 2:4. It was found, also, that, when both gases, sufficiently pure, were mixed in that proportion, and exposed to the electric spark, the mixture disappeared entirely, by which his discovery was completely confirmed. Cavendish distinguished himself no less in natural philosophy, by the accuracy of his experiments. possessed, also, a profound knowledge of the higher geometry, of which he made a very happy use in determining the mean density of the earth. He found it to be 5 times greater than the density of water -a conclusion which differs but little from that obtained by Maskelyne in another way. He was a member of the royal society at London, and, in 1803, was made one of the eight foreign members of the national institute of France. Cavendish was probably the richest among the learned, and the most learned among the rich, men of his time. An uncle left him a large fortune in 1773. This increase of wealth made no change in his character and habits. Extremely regular and simple in his manner of living, he was liberal in encouraging science, and in his private charities. His large, well-chosen library was open for the use of learned men. He died in London, March, 1810, and left £1,200,000 sterling to his relations. His writings consist of treatises in the Philosophical Transactions, from 1766 to 1792. They are distinguished by acuteness and

accuracy.

He

CAVIARE (ickari) is made in Russia from the roe of sturgeons, belugas, and many other fish. The roe is separated from the skin which encloses it, salted, and, after eight days, pepper and finely

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