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GAY-LUSSAC GAZA 653 cal works comprise the Histoire de la Louisiane (2 vols. 8vo, New Orleans, 1847) ; "Romance of the History of Louisiana" (12mo, New York, 1848) ; "Louisiana, its Colonial History and Romance " (8vo, New York, 1851) ; " Lou- isiana, its History as a French Colony " (2 vols. 8vo, New York, 1851-'2) ; and " History of the Spanish Domination in Louisiana, from 1769 to December, 1803 " (New York, 1854). He is the author of " Philip II. of Spain," a biography (JSTew York, 1866), and of a novel, "Fernando de Lernos, Truth and Fiction" (1872), which is to be followed by a sequel en- titled "Aubert Dubayet." He has also pub- lished a drama, " The School for Politics," and several literary and political addresses, among which are two lectures on "The Influence of the Mechanic Arts." GAY-LUSSAC, Joseph Louis, a French chemist, born at St. Leonard, Limousin, Dec. 6, 1778, died in Paris, May 9, 1850. He was educated at the polytechnic school of Paris, then called Vecole centrale des travaux publics, where he attracted the notice of Berthollet, and was employed by him for a short time in the labo- ratory of the government chemical works at Arcueil. He then returned to the polytechnic school as assistant professor. Observations made on balloon ascensions having led to the supposition that the magnetic force diminishes at great elevations above the surface of the earth, Gay-Lussac and Biot were commissioned by the institute to make experiments with ref- erence to it. Two ascensions were made, the first, Aug. 23, 1804, by both, and the second, Sept. 15, by Gay-Lussac alone. In the latter he reached the extraordinary height of about 23,000 feet. These ascensions were the first made for exclusively scientific purposes. Their results were not conclusive, but interesting observations were made upon the decrement of temperature with the increase of elevation, and upon the uniformity in the composition of the atmosphere at all heights. On Oct. 1 of the same year Alexander von Humboldt and Gay-Lussac submitted to the French academy a joint paper upon the combination of gases, especially of oxygen and hydrogen, which at- tracted much attention and marks an era in the progress of chemical science. In 1805-' 6 Gay-Lussac prosecuted in company with Hum- boldt scientific inquiries in France, Switzer- land, Germany, and Italy. They were present at Vesuvius when there was an eruption and an earthquake. Their observations on terres- trial magnetism were published in the Memoires de la societe d' Arcueil. Gay-Lussac began in 1807 to investigate the expansion of the air and gases under increased temperatures, and iished the law that when free from mois- ture they all dilate uniformly and to equal amounts for all equal increments of tempera- ture, at least between zero and 100 C. He -Mowed that the gases combine in simple proportions of their volumes, and that the contraction sometimes experienced when sev- eral of them are compounded is always an exact simple fraction, usually one half, one third, or one quarter of their joint bulk. Sir Humphry Davy having shown by means of the voltaic pile that potassium and sodium are not simple substances, as had previously been supposed, and having decomposed them by the same means, Gay-Lussac and Thenard ob- tained potassium and sodium in greater pro- portions even than they had been obtained by Davy himself. They also developed the com- pound character of boracic and fluoric acids, introduced new methods of analyzing organic substances by their combination with chlorate of potash, and elucidated the composition of many of these compounds. The results of their investigation were given in Recherches physico- chimiques sur la pile, sur les alcools, &c. (2 vols. 8vo, 1811). Gay-Lussac afterward made original researches of great value into the newly discovered elementary substances of io- dine and cyanogen, into Prussian blue, chloric and hydrosulphuric acids, the theory of vapors, capillary attraction, and other subjects. Their results were published in the Annales de chimie et de physique, which he edited with Arago, and in other publications. In 1816 he invented the siphon barometer, since modified by Bunsen, by whose name it is best known. He also invented instruments for estimating the quantities of alcohol, chlorine, and alkali present in solutions, known severally as the alcoholometer, chlorometer, and alkalimeter. In 1832 he gave up the professorship at the Sorbonne, to which he had been appointed in 1809, and accepted that of general chemistry atthejardin des plantes. As an expounder of science he was distinguished for the clear- ness of his explanations. In 1831 he was chosen by the electors of his native town member of the chamber of deputies; and in 1839 he was made a peer of France. GAZA (Arab. Ghazze or Ghuzze), a town of Syria, built partly on a steep hill, partly on the plain below, on the road leading to Egypt, be- tween the Mediterranean and the desert ; pop. about 15,000. It is situated about 3 m. from the sea, in the neighborhood of rich gardens, is not fortified, and consists partly of mud cot- tages, partly of ruinous stone buildings, which are occupied by the government and chief citizens. It is an important entrepot for the caravan traffic between Egypt and Syria. It has few relics of antiquity, and its only inter- esting edifice is a mosque which was originally a Christian church, founded, according to tra- dition, by the empress Helena. The ancient city of Gaza, which some suppose to have stood nearer the sea, is known in the Bible as the most southern of the five confederate cities of the Philistines, and is often mentioned, as in the history of Samson. Its Hebrew name ('Azzah) signifies " strong." On the conquest and division of Palestine by the Isra- elites, it was allotted to the tribe of Judah, which conquered it, but lost it again. It