GAYAL, a domesticated ox allied to the Gaur (q.v.) but dis tinguished by the more conical and straighter horns, and the straight line between them. Gayal are kept by the natives of the hill-districts of Assam, Tenasserim, and Upper Burma.
Gay-Lussac's earlier researches were mostly physical in charac ter and referred mainly to the properties of gases, vapour-tensions, hygrometry, capillarity, etc. His first memoir, published in 1802, dealt with the expansion of gases. In 1804 the French Academy, desirous of securing some observations on the force of terrestrial magnetism at great elevations above the earth, obtained the use of a balloon, and entrusted the task to him and J. B. Biot. In their first ascent from the garden of the Conservatoire des Arts on Aug. 24, 1804 an altitude of 4,000 metres was attained; Gay-Lussac made a second ascent by himself on Sept. 16, when the balloon rose 7,016 metres above sea-level. At this height, he made obser vations not only on magnetism, but also on the temperature and humidity of the air, and collected several samples of air at different heights. The magnetic observations led him to the conclusion that the magnetic effect at all attainable elevations above the earth's surface remains constant ; and on analysing the samples of air he could find no difference of composition at different heights. (For an account of both ascents see .Iourn. de plays., 1804 and BALLOON.) In the same year, in conjunction with Alexander von Humboldt, he read a paper on eudiometric analysis (Ann. de Chim., 1805); it contained the germ of his most important gener alization, the law of combination by volumes, which was, however, not enunciated in its general form until after his return from a journey through Switzerland, Italy and Germany.
In 1809 his important memoir on gaseous combination was pub lished; in it he pointed out that when gases combine with one an other they do so in the simplest proportions by volume, and that the volume of the compound formed bears a simple ratio to that of the constituents (see CHEMISTRY : Physical).
About this time Gay-Lussac's work became more purely chem ical. In 1808, he succeeded, with the collaboration of L. J. Thenard, in preparing potassium by the action of red-hot iron on fused potash ; the properties of the element were studied and in 1809 he used it for the reduction of boron from boracic acid in 1809. Gay-Lussac carried out some work on chlorine (1809) and iodine (181 4) which brought him into direct rivalry with Hum phry Davy. He considered "oxymuriatic acid" (chlorine) to be a compound, whereas Davy saw no reason to suppose that it con tained oxygen and regarded it as an element, a view which Gay Lussac was reluctantly compelled to accept.
In 1810 Gay-Lussac published a paper which contains some classic experiments on fermentation, a subject to which he re turned in a second paper published in 1815. At the same time he was working with Thenard at the improvement of the methods of organic analysis, and by combustion with oxidizing agents, first potassium chlorate and subsequently copper oxide, he determined the composition of a number of organic substances. His last great piece of pure research was on prussic acid. In a note pub lished in 1811 he described the physical properties of this acid, but he said nothing about its chemical composition till 1815, when he described cyanogen as a compound radicle, prussic acid as a compound of that radicle with hydrogen alone, and the prus siates (cyanides) as compounds of the radicle with metals. The proof that prussic acid contains hydrogen but no oxygen was a most important support to the hydrogen-acid theory, and com pleted the downfall of Lavoisier's oxygen theory; while the iso lation of cyanogen was of equal importance for the subsequent era of compound radicles in organic chemistry.
As a result of his success as an investigator Gay-Lussac's serv ices as a technical adviser became in great demand. He had been a member of the consultative committee on arts and manufactures since 1805; he was attached to the "administration des poudres et salpetres" in 1818, and in 1829 he received the lucrative post of assayer to the mint. His services to industry included his improvements in the processes for the manufacture of sulphuric acid (1818) and oxalic acid (1829) ; methods of estimating the amount of real alkali in potash and soda and for estimating the available chlorine in bleaching powder by a solution of arsenious acid; directions for the use of the centesimal alcoholometer pub lished in 1824 and specially commended by the Institute; and the elaboration of a method of assaying silver by a standard solution of common salt. Among his research work of this period may be mentioned the improvements in organic analysis and the investi gation of fulminic acid made with the help of Liebig, who gained the privilege of admission to his private laboratory in The most complete list of Gay-Lussac's papers is contained in the Royal Society's Catalogue of Scientific Papers, which enumerates 148, exclusive of others written jointly with Humboldt, Thenard, Welter and Liebig. Many of them were published in the Annales de chimie, which after it changed its title to Annales de chimie et physique he edited, with Arago, up to nearly the end of his life ; but some are to be found in the Memoires d'Arcueil and the Comptes rendus, and in the Recherches physiques et chimiques, published with Thenard in 181I.