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unceasing in their attentions. By the beginning of 1724 | of Francesca Peretti, a Florentine lady, was born at Paris 1st July 1776. Under the guidance of her father, a man of taste and culture, she received a very careful education. In 1793 she was married to M. Liottier, an exchange broker, but she was divorced from him in 1799, and shortly afterwards was married to M. Gay, receiver-general of the department of the Roër or Ruhr. This union brought her into more intimate relations with many distinguished personages whom she had previously known; and her circle of acquaintanceship gradually extended, until her salon came to be frequented by all the distinguished litterateurs, musicians, actors, and painters of the time, among whom she made herself remarked by her beauty, her vivacity, and her sprightly wit tempered by fine tact and genuine amiability. Her first literary production was a letter written in 1802 to the Journal de Paris, in defence of Madame de Stael's novel Delphin; and in the same year she published anonymously her first novel Laure d'Estell. Léonie de Montbreuse, which appeared in 1813, is considered by Sainte-Beuve her best work; but Anatolie, which appeared in 1815, has perhaps a higher reputation. These and several of her other works, amongst which may be specially named Les Salons célèbres, possess an interest beyond their intrinsic merits-chief of which are purity and elegance of style--for their portraitures of French society especially during the period of the directory and the consulate, and of many of the distinguished personages whose intimacy she enjoyed. Madame Gay wrote several theatrical pieces which had considerable success. She was also an accomplished player on the pianoforte and harp, and composed both the words and music of a number of romances. For an account of her daughter Delphine Gay, Madame de Girardin, see GIRARDIN.

he had a new play ready, a tragedy called the Captives, which was patronized by the Princess (afterward Queen) Caroline and the Prince of Wales. In 1726 he published his famous Fifty-one Fables in Verse. His next work was the Beggar's Opera, performed in 1727, written in ridicule of the Italian Opera, which for a time it drove off the English stage. Swift suggested the subject, and Pope is believed to have added some poignancy to the satirical songs; but Gay's own bonhomie and voluptuous style colour the whole. The play ran to the end of the season, sixtytwo nights, four of which were for the benefit of the author, and produced to him the handsome sum of £693, 13s. 6d. The same year he sold his copyright of the Opera, with that of the Fables, for 90 guineas. The success of The Beggar's Opera induced Gay to attempt a continuation of the operatic style. He wrote another piece, Polly, with no satirical design, as he states; but the lord chamberlain prolüibited its representation. The poet then resorted in 1729 to publication by subscription; his friends were again active -the duchess of Queensberry even bearding royalty in resentment of the refusal of the licence; and Gay must have cleared above £1000 by what was deemned his oppression. The duke of Queensberry received Gay into his house, and the duchess treated him with equal respect for his talents and character. This clever, beautiful, and eccentric woman—the idol of the poets-appears nowhere to more advantage than in her affectionate patronage of Gay, and her long-cherished regret for his loss. The poet died, after a short illness, December 4, 1732, and the duke and duchess of Queensberry honoured his remains with a splendid funeral and monument in Westminster Abbey. A week before his death another opera, Achilles, had been brought out with applause, and this, with a new volume of Fables, was published in 1733, the profits going to his sisters, two widow ladies, who inherited by the poet's death no less than £6000. As late as 1743 appeared the posthumous comedy of The Distrest Wife, and the farce of The Rehearsal at Gotham in 1753. Pope and Swift-always ready to blame the court and courtiers, though far from averse to their society-have censured Mrs Howard, afterwards countess of Suffolk, for not more zealously promoting the interests of Gay by her supposed influence with the king. One offer was made to the poet, the situation of gentleman-usher to the Princess Louisa, a child,-but he declined it on account of his being, as he writes to Swift, so far advanced in life. He was only thirty-nine; but all Gay's frieuds seem to have treated the offer as an indignity. When the queen's establishment was made up in 1727, they expected some more important office for their favourite associate, though it is not easy to discover what appointment about the court could have been better adapted to one so easy, so natural, and helpless. Mrs Howard, it is now known, had very little influence with her royal master. The real power was in the hands of the queen, and the philosophical Caroline was content that his Majesty (who hated bhoetry and bhainting, and looked upon poets as mechanics) should possess what mistresses he pleased, provided that the state power and patronage continued with herself and Walpole. But it may be safely said that no man could have acquired such a body of great and accomplished friends as those which rallied round Gay and mourued his loss, without the possession of many valuable and endearing qualities. His poetry is neither high nor pure; but he had humour, a fine vein of fancy, and powers of observation and local painting which bespeak the close poetical student and the happy literary artist.

(R. CA.)

GAY, MARIE FRANÇOISE SOPHIE, MADAME (1776-1852), daughter of M. Nichault de Lavalette (who was attached to the household of Monsieur, afterwards Louis XVIII.), and

Besides the works already mentioned, she is the author of Les Malheurs d'un amant heureux, 1818; Théobald, épisode de la guerre de Russie, 1828; Le Moqueur amoureux, 1830; Un Mariage sous Empire, 1832; Scènes du jeune âge, 1833; Physiologie du ridicule, 1833; La Duchesse de Châteauroux, 1834; Souvenirs d'une vieille femme, 1834; La Comtesse d'Egmont, 1836; Marie de Mancini, 1840; Marie-Louise d'Orléans, 1842; Ellénore, 1844-46; Le Faux Frère, 1845; Le Comte de Guiche, 1845; and Le Mari confident, 1849. See Theophile Gautier, Portraits Contemporains; and SainteBeuve, Causeries du Lundi, vol. vi.

GAYA, a district of British India in the Patná division, under the lieutenant-governor of Bengal, situated between 24° 17′ and 25° 19′ N. lat., and between 84° 4′ and 86° 5' E. long. It is bounded on the N. by Patná, on the E. by Monghyr, on the S. E. and S. by Hazaribagh, and on the W. by Shahábád districts. Generally speaking, Gayá consists of a level plain, with a ridge of prettily wooded hills along the southern boundary, whence the country falls with a gentle slope towards the Ganges. Rocky hills occasionally occur, either detached or in groups, the loftiest being Maher hill about 12 miles S.E. of Gaya town, with an elevation of 1620 feet above sea-level. The eastern part of the district is highly cultivated; the portions to the north and west are less fertile; while in the south, the country is thinly peopled, and consists of hills, the jungles on which are full of wild animals. The principal river is the Son, which marks the boundary between Gayá and Sháhábád, navigable by small boats throughout the year, and by craft of 20 tous burden in the rainy season. The other rivers are the Pímpún, Phálgú, and Jamná, and a number of smaller streams. Two branches of the Son canal system, the eastern main canal and the Patná canal, intersect the district.

The census of 1872 takes the area of Gayá district at 4718 square miles, and returns the population at 954,129 males and 995,621 females,—total, 1,949,750, residing in 6530 villages or towns, and 327,845 houses. Classified according to religion, there are 1,729,890 Hindus, 219,332

Mahometans, 203 Christians, and 316 "others." Amongst the higher castes there is an unusually large proportion of Brahmans, a circumstance due to the number of sacred places which the district contains. The Gayáwáls, or priests in charge of the holy places, are held in high esteem by the pilgrims; but they are not pure Bráhmans, and are looked down upon by those who are. They live an idle and dissolute life, but are very wealthy, from contributions extorted from the pilgrims. The ruined city of Buddh Gayá, about 6 miles south of Gayá town, marks the residence of Sakya Sinha, the founder of the Buddhist religion, who flourished in the 6th century B.C., and an ancient tree is pointed out as the identical fig tree under which the sage sat in abstraction for five years, until he attained to the state of Buddha. Another place of religious interest is a temple of great antiquity, which crowns the highest peak of the Baraber hills, and at which a religious fair is held each September, attended by from 10,000 to 20,000 pilgrims. At the foot of the hill are numerous rock caves excavated about 200 B.C.

Seven towns in Gayá district contain upwards of 5000 inhabitants, viz., Gayá, 66,843; Jalánábád, 21,022, Dáudnagar, 10,058; Tikárí, 8178; Sherghátí, 7033; Hasúá, 6119; and Rajauli, 5012. About four-fifths of the surface is cultivated. Rice forms the great agricultural staple, the area under cultivation being estimated at about 900,000 acres, yielding an outturn of over 400,000 tons. Wheat occupies about 170,000 acres, producing a crop of 60,000 tons, of which one-half is exported. Oil seeds are grown on about 35,000 acres, and opium on between 60,000 and 70,000 acres. Cotton, sugar-cane, chilies, and vegetables are also grown. Droughts are common, and in the famine of 1866 Gayá suffered severely. The scarcity of 1873-74 did not affect the district to any great extent. Manufactures consist of common brass utensils, black stone ornaments, pottery, tasar silk cloth. Formerly cloth-weaving and paper-making were important manufactures in the district, but these industries have now almost entirely died out. The chief exports are food grains, oil seeds, indigo, crude opium (sent to Patná for manufacture), saltpetre, sugar, blankets, brass utensils, &c. The imports are salt, piece goods, cotton, timber, bamboos, tobacco, lac, iron, spices, and fruits. The principal trade route is along the Patná branch road. The total net revenue of the district in 1876-77 was £188,426, of which £136,692 was derived from the land; the net civil expenditure, £23,878. The district and municipal police of all ranks numbered 923, besides a rural force of 6790 men paid by the landholders and villagers. The number of schools in 1873-74 was 446, attended by 8139 pupils. The climate of Gayá is dry and healthy, the average annual temperature being about 80° F., and average annual rainfall 35 59 inches.

GAYA, the chief town and administrative headquarters of the above district, situated on the bank of the Phálgú river, lat. 2° 47′ 15′′ N., long. 85° 3′ 10′′ E. The population in 1872 numbered 66,843-Hindus, 52,265; Mahometans, 14,414; Christians, 134. The municipal income in 1871 was £2716, and the expenditure £2351. The town consists of two distinct parts, adjoining each other; the part containing the residences of the priests is Gayá proper; and the other, which is the business quarter, is called Sahibganj. The civil offices and residences of the European inhabitants are situated here. Gayá derives its sanctity from incidents in the life of Buddha connected with the adjoining district. But a local legend also exists concerning a pagan monster of great sanctity, named Gaya, who wickedly tried to save sinners from deserved perdition. Brahma in order to get rid of Gayá induced him to lie down in order that a feast might be held on his body; and once down, he placed a large stone on him to keep him there. The tricked demon struggled violently, and, in order to pacify him, Brahma promised that the gods should take up their permanent residence in him, and that any one who made a pilgrimage to the spot were he lay should be delivered from the terrors of the Hindu place of torment. This may possibly be a Brahminic rendering of Buddha's life and work. There are forty-five sacred spots in and around town, which are visited by from 100,000 to 200,000 pilgrims annually.

GAY-LUSSAC, JOSEPH LOUIS (1778-1550), one of the most distinguished of modern physicists and chemists, was born at St Léonard, in the department of Haute Vienne, on the 6th of December 1778. His father, Antoine Gay, who was procureur du roi and judge at Pont-de-Noblac, had added to the common family name the distinctive title Lussac, from a small property he had in the neighbourhood of St Léonard. The family consisted of two sons, of whom Joseph Louis was the elder, and three daughters. Intended for the bar, young Gay-Lussac prosecuted his early studies in Latin and other elementary subjects at home, under the superintendence of the Abbé Bourdeix and other masters, until 1794, when he was sent to Paris, where he worked very hard for three years preparing for admission to the École Polytechnique. After a brilliant examination he was received into this institution on December 27, 1797, whence on the 22d of November 1800 he was transferred to the school Des Ponts et Chaussées. Shortly afterwards be was assigned to Berthollet, who had returned from Napoleon's Egyptian expedition, and, who was desirous of having an able student from the École Polytechnique to aid him in his researches. The results expected by the author of experiments, which seem to have been recorded without any the Statique Chimique were not verified by his assistant's consideration of the theorizer's feelings. It was on this occasion, according to Arago, that Berthollet, at first nettled to find that his ideas were not confirmed, delivered himself as follows: "Young man, it is your destiny to make discoveries. You shall be henceforth my companion. I wish-it is a title of which I am sure I shall have cause some day to be proud-I wish to be your father in science."

Gay-Lussac accordingly entered on a long series of researches upon certain physical phenomena, which though of constant recurrence in experimental inquiries, had up to this time been very imperfectly examined. In his first memoir (Ann. de Chimie, t. xliii., 1802) he shows that different gases are dilated in the same proportion when heated from 0° to 80° (Réaumur). He does not seem to have been aware of Dalton's experiments on this subject, which were indeed very far from being accurate; but he states in a footnote that "le cit. Charles 1 avait remarqué depuis 15 ans la même propriété dans ces gaz; mais, n'ayant jamais publié ses résultats, c'est par le plus grand hasard que je les ai connus." In return for his having thus rescued from oblivion the remark which his fellowcitizen, probably wisely, did not think worth recording, some recent authors have changed the title of the law from that of Gay-Lussac to that of Charles. The investigations recorded in this memoir were followed by experiments on the improvements of thermometers and barometers, on the tension of vapours, their mixture with gases, and the determination of their density, evaporation, hygrometry, and capillarity. In course of these researches, which engaged him for a couple of years, he acquired not only dexterity in manipulation and the contrivance of experiments, but a great deal of valuable knowledge of physics. During the interval, in the year 1802, he had been nominated Fourcroy's demonstrator at the Ecole Polytechnique, and as he had in this capacity to lecture frequently for the professor, he was beginning to acquire reputation as a teacher and expounder of chemistry and physics, by the clearness, precision, and care which his lectures evinced. In 1803-4 certain results respecting terrestrial magnetism had been obtained during two balloon ascents, which appeared of so much interest that the French Academy was desirous of having them repeated. Through Berthollet and Chaptal the balloon which had been used in Egypt was obtained, and fitted up with various instruments; the observations were entrusted to Gay-Lussac and Biot,

1 The inventor of the "Charlière," or hydrogen balloon.

who made their first ascent from the garden of the Conservatoire des Arts et Metiers, on August 24, 1804. In this ascent an altitude of 4000 metres was attained, but unexpected difficulties were encountered, and the results were not decisive. Not satisfied with the expedition, Gay-Lussac got a larger balloon provided with every requisite, and made an ascent by himself on September 16 of the same year. On this occasion the balloon rose to a height of 7016 metres, an altitude greater than any which had been formerly reached, and surpassed only by a few later ascents. At this great elevation of nearly 23,000 feet, and with the thermometer at 91° C. below freezing, Gay-Lussac remained for a considerable time making observations on temperature, on the moisture of the air, on magnetism, and other points. He observed particularly that he had considerable difficulty in breathing, that his pulse was quickened, and that by the absence of moisture in the air his mouth and throat became so parched that it was painful to swallow even a piece of bread. The experiments on magnetism for which the ascent was primarily made were imperfect, but they led him to the conclusion that the magnetic effect at all attainable elevations above the earth's surface remains constant. Having collected samples of air at different elevations he, on his return to Paris, proceeded to analyse them; and in conjunction with Alexander von Humboldt, whom he had associated with himself in this investigation, he published several papers on eudiometric analysis and related topics. The memoir, which was read to the Institute on October 1, 1804, contained the germ of what was afterwards Gay-Lussac's most important generalization. The authors observed that when oxygen and hydrogen combine together by volume, it is in the proportion of one volume of the former to two volumes of the latter. Prior to this the numerous experiments on the volume composition of water had always brought out various complicated ratios, though approaching the simple one more or less closely. It was not, however, till 1808, that Gay-Lussac announced the law of combination by volume in its general form. Shortly after these investigations were completed, Gay-Lussac got leave of absence to accompany Von Humboldt on a scientific journey to Switzerland, Italy, and Germany. Provided with physical and meteorological instruments, they left Paris March 12, 1805, and travelled by Lyons, Chambery, and Mont Cenis to Genoa, and thence to Rome, where they arrived on July 5. After a short stay at Rome in the residence of William von Humboldt, during which Gay-Lussac made a few chemical analyses, they departed for Naples in company with Leopold von Buch, afterwards so eminent as a geologist. During this visit Gay-Lussac had the opportunity of study ing on the spot volcanic eruptions and earthquakes. Vesuvius, which was in violent action, he ascended six times. After this the party went back to Rome, and then started for Florence on September 17, 1805. A few days having been spent there, they went on to Bologna and thence to Milan, which they reached on October 1, and there they had the pleasure of meeting Volta. The party crossed the St Gotthard on October 14-15, in the midst of a storm which prevented their seeing anything, and after some delay reached Göttingen, where they were received with much attention by Blumenbach, the famous naturalist. On November 16 they arrived at Berlin, where the winter and the following spring were spent. In this way Gay-Lussac became acquainted with the best society in Berlin, and was especially intimate with Klaproth and Erman. In spring he hurriedly returned to Paris. The death of an Academician had left a vacant place, and he was hopeful that he might be elected to fill it. Arago remarks that it is curious

1 The numerous observations made in both ascents are recorded in the Journal de Physique for 1804, vol. 59.

that Gay-Lussac should have found it necessary to be on the spot to ensure success. What he had already done for science might have been considered sufficient, apart from personal considerations, but there were prejudices which might have acted unfavourably, if he had not been present to meet them. These were, however, successfully overcome, and he entered the Academy in 1806. In the following year was inaugurated the Société d'Arcueil, a small group of scientific men who used to assmble at Berthollet's house. Gay-Lussac was an original member of this society, which is of interest chiefly on account of its having been the means of publishing some papers which have since proved of great historical interest. The results of his magnetic observations made along with Humboldt were published in vol. i. of its Mémoires (1807); and vol. ii. (1809) contains the important memoir on gaseous combination, in which he pointed out that, when gases combine with one another by volume or by measure, they do so in the very simplest proportions, 1 to 1, 1 to 2, 2 to 3, and so on, and that the volume of the product in the gaseous state bears a very simple ratio to that of the constituents. This law, which, along with Humboldt, he had shown to be true. of water, he extended to several other gases, and he even deduced from the vapour density of compounds that of certain elements, more particularly, carbon, mercury, and iodine, which had not been ascertained by direct experiment. It would take too much space to give in detail the criticism which the enunciation of the principle evoked, more particularly from Dalton, who would not accept GayLussac's position, and affirmed his belief that "gases do not unite in equal or exact measures in any one instance; when they appear to do so, it is owing to the inaccuracy of our experiments." There was at that time the difficulty that the specific gravity of gases and vapours had been imperfectly determined, and the necessary consequence of GayLussac's law, that the specific gravity and combining weight of elements should be expressed by the same number, could not be experimentally confirmed. Moreover, Dalton rested combination on atomic and not on combining weights, and the numbers he employed were in almost every instance very different from those which more accurate analysis has since determined. But the imperfect character of the then available data, and the amount of seemingly adverse experimental evidence, only throw a stronger light on the genius of Gay-Lussac in divining a law which, as science has progressed, has been duly confirmed, and which not only forms the most important control of the combining weight of chemical substances, but, when interpreted by the kinetic theory of gases, shows that the physical molecules (that is to say, the portions of the substance which are not broken up into smaller parts during the motion which we call heat) exist in equal numbers in equal volumes of different gases at the same temperature and pressure. This law, which has as high a claim as the other to bear the name of Gay-Lussac, is also sometimes deprived of that honour, and called the law of Avogadro, who, long afterwards, by his more extended researches, caused the importance of the law to be recognized by chemists.

The next events in Gay-Lussac's scientific career are connected with what may be called his rivalry with Davy, who in matter of age (b. December 17, 1778) was almost exactly his contemporary. In 1808 when Davy, having isolated potassium and sodium, was awarded Napoleon's prize for the most important discovery in voltaic electricity, the emperor is said to have asked how it was that these discoveries were made abroad and French prizes were carried away. Having

2 New System of Chemical Philosophy, Manchester, 1810, part ii, p. 559.

been informed that there was no battery of power equal to that used by Davy, he caused a very large one to be made, and presented it to the École Polytechnique. While waiting for it, Gay-Lussac and Thénard succeeded in preparing potassium by a direct chemical action, in which fused potash was brought in contact with red-hot iron. This method enabled chemists to prepare the alkali metals in quantity, and Gay-Lussac and Thénard availed themselves of it to examine the properties of potassium very completely, and not only so, but also to use it as a means of decomposing other substances. It was in this way that they separated boron from boracic acid, an element which was also prepared by Davy with the same materials. It is worth notice that Davy admitted the advantage of the method of Gay-Lussac and Thénard, though he seems to have subsequently regarded their appropriation of the newly-discovered metal as not altogether warranted. The researches with the great battery after it was made did not come up to their expectations; the power fell far short of what had been anticipated, and they confined themselves rather to an examination of the phenomena presented by the apparatus itself, than to using it as an engine for effecting important decompositions. In 1809 was published the second investigation parallel to one by Davy, namely, upon hydrochloric (or, as it was then called, muriatic) acid, and chlorine, then called oxymuriatic acid. This memoir was read to the Institute, and was also published in the second volume of the Mémoires d'Arcueil. Gay-Lussac and Thénard describe a crowd of reactions they had tried for determining the characters of these bodies. They pointed out differences between the muriatic and other acids, and indicated that the anomalies which it presented were explicable either on the hypothesis of water being an essential constituent of the acid, or on that of the oxymuriatic acid being a simple gas. At the end of their memoir, however, they decided in favour of oxymuriatic acid being compound, although they had failed to get oxygen from it by heating it with carbon. planation of this decision seems to be that, while they themselves were influenced to some extent by Lavoisier's oxygen theory of acids, some of the other members of the Arcueil Society, such as Laplace and Berthollet, were keen Lavoisierians, and were prepared to oppose any criticism which might lead to a modification of the great Frenchman's opinion on so vital a point. To admit the existence of an acid without oxygen might have led to a loss of the whole scientific position which France had gained by Lavoisier's defeat of phlogiston. Davy, who was not under the same influence, declared, as the result of his inquiries, that oxymuriatic acid gas was simple, and that therefore there may be acids without oxgyen. Sometime after, Gay-Lussac and Thénard agreed with this view, which they could do with less hesitation, as they had themselves indicated it in their own memoir.

The ex

Among the investigations which Gay-Lussac undertook with Thénard in the years 1810-1811, and which ultimately yielded most valuable results, must be mentioned those upon organic chemistry, and especially upon the analysis of fixed organic compounds. Before this time

1

Gay-Lussac and Thénard made no claim, of course, to the discovery of potassium and sodium, though several important discoveries followed from their experiments. Thus, in addition to boron, they got also the fluoride of boron ; and by the rapid combustion of the alkali metals in dry oxygen they got their peroxides, by means of which Thénard subsequently prepared the peroxide of hydrogen. At first, however, they seem to have thought that the alkali metals contained hydrogen, and it was not for a couple of years that they accepted Davy's view of their simplicity. Indeed, about this time there appears to have been considerable uncertainty about the elemental character of

the only way of determining the composition of organic substances was to explode them with oxygen, and as this method was practicable only in the case of bodies which were gaseous, or could be readily volatilized, the great majority of fixed organic substances still remained unexamined. Gay-Lussac and Thénard introduced the plan of adding some oxidizing agent to the substance and burning it in a tube. They used chlorate of potassium, and the products of combustion were collected over mercury. The results obtained were in some cases very accurate, but the process was difficult of execution, and it is singular that the authors should have preferred it to combustion with oxide of copper, which they also tried. In 1815, however, GayLussac employed the latter agent for the examination of cyanogen, and the other method was abandoned. The final improvements were made some years later by Liebig, when working in Gay-Lussac's laboratory. By their original method Gay-Lussac and Thénard determined the composition of fifteen organic substances, including sugar, starch, gum, wax, oil, various woods, resin; mucic, oxalic, tartaric, citric, and acetic acids; and albumen, fibrin, gelatin, and casein. Gay-Lussac succeeded also, in 1811, in obtaining pure hydrocyanic acid. He described its pliysical properties, but did not announce anything about its composition till 1815, when he published his celebrated memoir in which he described cyanogen as a compound radical, prussic acid as a compound of this radical with hydrogen alone, and the prussiates as compounds of the radical with metals. He also showed how to prepare free cyanogen, and explained Berthollet's oxyprussic acid to be really chloride of cyanogen. The proof that prussic acid contains hydrogen and no oxygen was a most important support to the hydrogen acid theory, while the isolation of the radical cyanogen was of equal importance for the subsequent epoch of compound radicals in organic chemistry.

In 1813-14 Gay-Lussac published his memoirs on iodine. This was the third investigation which involved a rivalry with Davy, and it was also that about which there was most feeling. Courtois had discovered the substance in 1811, and had given some of it for examination to Clément-Désormes. He had only published a brief notice of it when Davy arrived in Paris, having obtained express permission of Napoleon to pass through France on his way to Italy. Davy got a few fragments of this curious substance, and after a brief examination with a very limited portable laboratory which he had with him, perceived its analogy to chlorine, and drew the conclusion that it must be a simple body of similar character. Gay-Lussac, it is said, having heard of Davy's making experiments with it, went off to Courtois, got a specimen, and proceeded to examine it. He also saw its likeness to chlorine, but his previous decision respecting that body hampered him, and it was with some hesitation that he ultimately acknowledged its elemental character. Whether or not Gay-Lussac was actuated by the motive ascribed to him by Arago-that it would be a reflexion on French science were the settlement of the characters of this substance to be left to a foreigner visiting Paris-it is not necessary to enquire; but Davy seems to have felt that GayLussac was competing, and not altogether fairly, with him. In a letter to Clément he gives a brief account of his work, and lays claim to the first revelation of the elemental character of iodine, and again in a subsequent letter to his brother, which contains a short review of the Parisian chemists and their reception of him, the only complaint he makes is that Gay-Lussac had played him a trick in trying to appropriate the discovery of the character of iodine and of hydriodic acid. Quite apart, however, from this claim on Gay-Lussac's part, the memoirs remain models of inves

the metals, it being thought that they contained hydrogen, an idea tigation and description. Davy quite freely admitted that which, on account of its retrograde nature, was criticized by Davy as a kind of phlogistic revival.

full light might be expected on the subject from its

having been taken in hand by so able and accurate a chemist as Gay-Lussac.

burette, which still bears his name, all bear witness to his ingenuity and practical skill. He devised new analytical methods; he discovered new substances, such as fluoride of boron, and iodic, hydrosulphocyanic, dithionic, and hyposulphurous acids; he enlarged and corrected the knowledge of those already discovered; he examined the physical conditions of chemical action; he searched into the causes of chemical combination and chemical change. That he had the power of grasping the law underlying a few facts is nowhere more evident than in the memoir on gaseous combination, his most important contribution to science. That he missed the opportunity of assigning the chief limit to Lavoisier's hypothesis, must be ascribed partly at least to the influence of others. Authority decided it, perhaps against his secret convictions.

From Arago's and other notices one gathers that GayLussac was reticent, patient, persevering, accurate to punctiliousness, perhaps a little cold and reserved, and not unaware of his great ability. But he was also bold and energetic, not only in his work, but equally so in defence and support of his friends. His earliest childish adventures, as told by Arago, herald the fearless aeronaut and undaunted investigator of volcanic eruptions. The endurance he exhibited under the laboratory accidents which befell him shows the power of will with which he could face the prospect of becoming blind and useless for the prosecution of the science which was his very life, and of which he is one of the most distinguished ornaments. It was only at the very end, when the disease from which he suffered left him no hope, that he complained with some bitterness of the hardship of leaving this world when so many discoveries were making, and when so many more were likely to be made.

The year 1815 saw the completion of the research on cyanogen already referred to, and with it concludes the period of Gay-Lussac's most important discoveries. Having now attained a leading if not the foremost place among the scientific men in the French capital, his advice was often required on important questions. His attention was thus turned in part from purely scientific subjects to points of practical interest. In these new fields, however, he displayed the same powers which he had exercised so sedulously in the pursuit of scientific truth; in fact he was now to introduce and establish scientific accuracy where there had been previously only practical approximations. The most important of these later discoveries were the method of estimating the amount of real alkali in potash and soda by the volume of standard acid required for neutralization; the method of estimating the amount of available chlorine in bleaching powder by a solution of arsenious acid; directions for the use of the centesimal alcoholometer, published in 1824, and specially commeuded by the commission of the Institute appointed to report on it, as displaying all the accuracy and exhaustive treatment of the author; and lastly, the perfecting of the method of assaying silver by a standard solution of common salt, a volume on which was published in 1833. This last has superseded the old method of assaying silver by cupellation, as being more rapid, more accurate, and easier of execution; and indeed all these processes are so complete and satisfactory, and are besides so identified with their author's name, that his reputation is secured by them, quite independently of his earlier work. In what has been said above, only the rore important of Gay-Lussac's discoveries have been alluded to. To enter into an account, however brief, of all his labours, would occupy more space than can be allowed here. Indeed the list of his papers in the Royal Society's catalogue amounts to 148, besides those of which he was joint-author with Von Humboldt, Thénard, Welter, and Liebig; and they embrace every department of the science as cultivated fifty years ago. Among his later researches may be mentioned those on fermentation, and those executed by Liebig in conjunction with him, after the young German chemist had gained the coveted admission to Gay-Lussac's private laboratory during the years 1823-1869; Forbes, A Review of the Progress of Mathematical and 24. The latter include improvements on organic analysis, and the examination of fulminic acid. Gay-Lussac continued his work, and published the results in the Annales de Chimie, of which he had been joint-editor for some thirty years, up till almost his death, which took place at Paris on May 9, 1850.

Some of the appointments he held have been already referred to. After having acted as Fourcroy's demonstrator, he was made professor of chemistry at the École Polytechnique. From 1808 to 1832 he was professor of physics at the Sorbonne, and he on'y resigned that office when he was made professor of chemistry at the Jardin des Plantes. Besides being on the commission of arts and manufactures, and the "administration" of gunpowder and nitre, he was appointed assayer for the mint in 1829. In 1831 he was elected to the chamber of deputies as member for Haute Vienae, and finally, in 1839, entered the chamber of peers.

Gay-Lussac's scientific work is remarkable not only for its range but for its intrinsic worth, its accuracy of detail, its experimental ingenuity, its descriptive clearness, and the soundness of its inferences. He did not hesitate to criticize his own results, and replace them by others more accurate either of his own or of another's discovery; he improved and invented physical and chemical apparatus: the barometer, thermometer, cathetometer, alcoholometer, and the

The more important of Gay-Lussac's papers are scattered through journals difficult of access. The most complete list of them is contained in the Royal Society's catalogue of scientific papers; lists are also given at the end of Hoefer's article in the Biographie Générale, and in Poggendorff's Biographisch-literarisches Hand. vörterbuch, Leipsic, 1863. Accounts of various portions of GayLussac's discoveries and views will be found in such works as Thomson's History of Chemistry, vol. ii., London, 1830; Kopp's Geschichte der Chemie, Brunswick, 1843-47; Kopp's Entwickel Chimique, Paris, 1837, and reprinted Paris, 1878; Ladenburg, ung der Chemie, Munich, 1871; Dumas, Leçons sur la Philosophie Vorträge über die Entwickelungsgeschichte der Chemie, Brunswick,

authorities for the life of Gay-Lussac are Arago (Euvres, Paris,
Physical Science in more recent times, Edinburgh, 1858. The chief
1855, t. iii.); Biot (Abstracts, Royal Society, vol. v., 1843-50, p.
1013); P. A. Cap (Le Muséum d'Histoire Naturelle, Paris, 1854,
pt. 1, p. 137).
(J. F.)

GAZA, an ancient city of Philistia, close to the sea and
to the south boundary of the Holy Land. The Hebrew is
more correctly rendered in English as Azzah (Deut. ii. 23),
and means "strong." The modern Arabic form of the
name is Ghazzeh. The town stands on an isolated hill about
100 feet high, and has now a population of 1800 souls. It
is divided into four quarters, the eastern suburb consisting
entirely of mud houses. A magnificent grove of very
ancient olives forms an avenue 4 miles long north of the
city. On the south-east are a few palms. There are many
lofty minarets in various parts of the town, and a fine
mosque built of ancient materials. A 12th century church
towards the south side of the hill has also been converted
into a mosque. On the east is shown the tomb of Samson
(an erroneous tradition dating back to the Middle Ages).
The ancient walls are now covered up beneath green mounds
of rubbish. The water supply is from wells sunk through
the sandy soil to the rock; of these there are more than
twenty-
-an unusual number for a Syrian town. The land
for the 3 miles between Gaza and the sea consists prin-
cipally of sand dunes. There is no natural harbour, but
traces of ruins near the shore mark the site of the old

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