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AFFINITY. AFFINITY,. The force that holds in combination the constituent elements of chemical compounds and causes the reactions taking place between material substances. The nature of chemical affinity is as little understood as the nature of gravitation, and the hypotheses on the subject, which have been advanced since the earliest times, are still confined within the domain of pure speculation. Borelli and Lem- ery imagined that the ultimate particles of matter were supplied with minute hooks, the shape of which determined the capacity of a particle for combining with certain other par- ticles. Bergman, Berthollet, and others, thought that chemical affinity might be identical with the energy of gravitation. Berzelius sought to explain all chemical phenomena on the hy- pothesis that chemical combination was caused by the mutual attraction of electrically different substances. All these hypotheses, however, go no further in explaining the transformations of matter than did the ancient idea, according to which those transformations were due to the mutual love or hatred of the different kinds of atoms. Such ideas are incapable of either theo- retical development or practical application, and science must, at least for the present, discard them as useless hypotheses and confine itself solely to the experimental study of the mode of action of the chemical forces, without reference to their ultimate nature. In this direction the science of chemistry has, in recent years, made considerable progress. The principles of thermo- dynamics have been successfully applied to many transformations, and certain general laws have been established, according to which all chemical reactions seem to take place. The second prin- ciple of thermodynamics proves that when a transformation takes place in a material system while no energy is being supplied to it from without, the system is capable of doing a certain amount of external work. The maximum ex- ternal work which may be obtained through a transformation taking place under ideal condi- tions (that is to say, through a reversible iso- thermal process), may be taken as a measure of the tendency according to which the transforma- tion takes place. In the case of a chemical trans- formation, that tendency is obviously the "affin- ity of the reaction." This maximum external work, done during a chemical reaction, or, as it is usually expressed, the change of free energy involved in a reaction, is ascertained either by studying reacting mixtures after they have reached the state of equilibrium, or, in the ease of galvanic combinations, by determining the electromotive force. See articles, and.

. T. Bergmann, Traité des affinités chymiques ou attractions électives (Paris, 1788); C. L. Berthollet, Researches Into the Laws of Chemical Affinity (translated by M. Farrell, Baltimore, 1809); C. M. Guldberg and P. Waage, Studien über die chemische Affinität (original edition, Christiania, 1864; French translation, Christiania, 1867; German translation, Leipzig, 1879). See also bibliography of theoretical chemistry under.

AFFOREST A'TION (Lat. ad, to + Low Lat. foresta, a wood, forest). The converting of open or partially wooded ground into forest or woodland. See.

'AFFRAY' (Fr. effroi, fright, terror, compare Engl. afraid''). The fighting of two or more persons in a public place in such a manner as will naturally cause terror to other people. It differs from assault (q.v.) in that it must occur in a public place, and from a riot (q.v.) in that only two persons are necessary for the commission of the offense. Two persons engaged, although in a public place, must each be guilty of unlawfully fighting the other or there is no affray. No matter how publicly, or in how terror-breeding a manner, A may attack B, if the latter does not go beyond the limits of self-defense in repelling the attack, the occurrence is not an affray, but an assault. An affray which did not develop into a higher crime, such as homicide or an attack upon a public officer, was punishable at common law by fine and imprisonment. In some of our States it is not recognized as a separate offense from assault and battery (q.v.). Consult: Wharton, Criminal Law (Philadelphia, 1896).

AFFRE, afr', Denis Auguste (1793-1848). An archbishop of Paris. At the time of the Restoration he was professor of theology at the seminary of St. Sulpice, and on account of his prudent and temperate character was made Archbishop of Paris by the government of Louis Philippe in 1840. Though not yield- ing a blind submission to all measures of the Government, he abstained from all of- fensive opposition. During the insurrection in Paris in June, 1848, he climbed upon a barri- cade in the Place de la Bastille, carrying a green bough in his hand as a messenger of peace, and sought to persuade the insurgents to lay down their arms. He had scarcely uttered a few words when the insurgents and the troops commenced firing again, and he fell, mortally wounded by a musket-ball. He was removed to his palace, where he died, June 27. He was the author of several theological writings and of a work on Egyptian hieroglyphics. Consult: Castan, His- toire de la vie et de la mort de Monsignor Affre (Paris, 1855).

AFFREIGHT'MENT (Lat. ad, to + Engl. freight). The contract of a shipowner for the carriage of goods in his ship for compensation, or freight. The shipper is technically known as the freighter. Where the freighter ships his goods in the ordinary way, without acquiring any control over the ship, the contract is a bill of lading (q.v.), and the rights of the parties are mainly determined by the laws relating to common carriers. (See .) Where the freighter charters the ship, the contract is known as a charter-party (q.v.), and has certain features, and is subject to certain rules, peculiar to the law of shipping. A complete treatment of the subject will be found in Scrutton, The Contract of Affreightment, as Expressed in Charter Parties and Bills of Lading (London, 1899).

AFFRONTÉ, affrun-td' (Fr. p.p. "face to face." from Lat. ad frontem, to the face). In heraldry, a term applied to animals represented as facing the spectator directly, as the lion in the royal crest of Scotland.

AFFU'SION, or. See.

AFGHAN', or (North Afghan), or  (South Afghan). A modern Iranian dialect which is spoken by about three million