LAVINIUM. 20 LAVOISIER. that it was founded by .Kiieas and named in honor of his wife, Lavinia, daujihlor of King Latinus. With the growth of population, the town became overstocked, and Ascanius, or lulus, son of .Eneas, led away part of the inhabitants and founded .lba Longa, the traditional mother- city of Home. Lavinium was renowned in very early times for its sanctiuiry of Venus, and for its cult of the tutelary gods of the l,aliii League, of which it became a sort of religious centre. Like other important Latin towns of the earlier fieriod, it gradually lost its prestige with the growth of Rome. The Emjieror Trajan ( a.d. 98- 117) gave it a new lease of life by joining the colonies of Laurentum and Lavinium, tinder the name I.auro-Lavinium. and locating there new colonists. It should be noted that the modern Civita l.avinia is on the site of the ancient Liniiiiiiitn. not Lavinium. LAVISSE, lA'vfs', ER.N-EST (1842-). A French liistorian, born at Xouvion-en-Tliierache, Aisne. He was educated at a classical school in Paris, and at the Superior Normal School, and received a fellowship in history in 18()5. He taught for ten years in the lyceunis at Xancy, Versailles, and at the College of Henry IV.; was then appointed nuister of conferences at the Superior Normal School, and in 1888 became professor of modern history in the Kaculty of Let- ters at Paris. In 1892 he was elected to the French Academy. He is distinguished alike for the clearness and carefulness of his elementary works, and for the authoritative character of his researches. His lectures, the most |)opular at the University of Paris, and his extensive contribu- tions to historical literature, have won for him a high place among French historians. In both he has striven to bring about a better feeling be- tween France and Germany, and his personal popularity has been evidenced by his election as j)resident of the Association of French Students. Among his published works are: La marche de Brandcboiiifi sous la dynastic ascanienne, etude sur I'unc dcs oiigines dc la monarchie prussi- enne (1875): Lemons pri'paratoirrs d'histoire de France {1S7(!) : Etudes sur Vhistoire de Prussc (1879). crowned by the .cadcmy ; Iai premiere annfc d'hisloire dc France ( 1883)': ,S'm//i/ ( 1880) ; Trois cmpcreurs d'.MIemnijne (1888) ; Histoire de France et notions d'histoire gfyUrale (1890, with M. Piiniy) ; Vue generate de Vhistoire poli- tique de I'I'.urope (1890) ; La jcunrsse du grand Frederic (1891). With Raml>aud he edited and contributed largely to the great Histoire generate du l'ime sii'rlr a nos jours (189.3 et seq.). LAVOISIER, la'vwa'syA'. AxTOiXE Lavrent (174.i-94l. The founder of modern chemistry. He was born in Paris, and was educated at the College Mazarin. He showed great aptitude for the mathematical and ])hysical sciences, studying mathematics under .Alibe Lacaille. botany under Jussieu. and cliemistry under Rouelle. He then traveled through France with Ouettard. who was at the time engaged in important geological work. As early as 17liS Lavoisier became a member of the Academy of Sciences, and in the following year he obtained a post as farmer-gen- eral of the revenue, by which he was enabled to devote most of bis time to researcli work. Be- tween 1772 and the year of his death. Lavoisier worked out the principles forming the corner- stone of modern chemistrv. an<l diirina this time held several important positions. In 177G he was niailc director of powder-works and introduced aluable improvements in the manufacture of gunpowder. In 1778 he was appointed one of the trustees of the 13ank of Discount. In 1790. as a member of the Commission of Weights and ileasures, he was engaged in preparing the decimal system. In 1791 he was commissary of the trea-sury, and published an int<'resting paper on the economic condition of France. The farm- ers-general of the revenue were men of eminent social position and considerable wealth, and in the Reign of Terror their wealth became a source of great danger to them. In 1794 Unpin, one of the members of the Convention, accu.sed them of being enemies of their country; Fou- quier-Tinville presented the accusation before the Revolutionary Tribunal, and the twenty-.seven farniers-general were condcmne<l to die. In vain had one of Lavoisier's friends endeavored to produce an impression on the Tribunal by describing his scientific achievements. The answer was, "We need no more scientists in France." At the very foundation of all chemical thought is the law of the conservation of nuiss. Lavoi- sier, although, not the fir>t to divine that matter is everlasting, was the first to understand that that important truth nuist be estal>lished induc-
- tively by the use of the balance. By a series of
quantitative experiments l^ivoisier proved that, whatever the change in kind, the total amount re- mains the same: and as all relations of quantity are mathematical relations. Lavoisier .saw that every chemical change could be expressed by an equation showing that the sum of the masses of the reacting substances is equal to the .sum of the masses of the resulting products. When iron, mercury, tin. and other metals were exposed to the action of the air. their weight increased. The resulting earths contained, besides the matter of the metals, other matter, and could naturally be split up again into their constituents; they were therefore complex, not simple substances. The quantitative method of Lavoisier thus threw light on the nature of various substances and led to a clear definition of the idea of chemical ele- ments. Lavoisier also advanced a general theory of the formation of chemical comjiounds. Ac- cording to this theory, all compounds have a hiniirt) constitution. A binary coniiiound of the first order is one made up of two elements. A binary compound of the second order is formed bv the union of two binary compounds of the first order. The acids formed by the union of sulphur, nitrogen, phosphorus, and similar sub- j stances with oxygen are binary compounds of the first order. .Xcids are neutralized by bases with formation of salts: therefore salts are binary compounds of the second order. In subsequent times the binary theory proved in- adequate and had to be abandoned. It had not lived, however, without giving birth to a series of important results. Since bases were cla.ssed by it as compounds of oxygen with metals, chem- ists were led to search for methods of isolating the latter by decomposing the bases. Thus came the discovery of the alkali and the alkaline earth metals by Davy and the isolation of aluminum by Wiihier. the importance of which for both science and the industries is inestimable. An- other important work, in the perfection of which Lavoisier look an active part, mii.st be men- tioned here. Little progress could be made in
