Lavoisier, Antoine Laurent


Lavoisier, Antoine Laurent (1743-1794), French chemist, who is considered the founder of modern chemistry.

Lavoisier was born on August 26, 1743, in Paris and was educated at the Collège Mazarin. He was elected a member of the Academy of Sciences in 1768. He held many public offices, including those of director of the state gunpowder works in 1776, member of a commission to establish a uniform system of weights and measures in 1790, and commissary of the treasury in 1791. He attempted to introduce reforms in the French monetary and taxation system and in farming methods. As one of the farmers-general, he was arrested and tried by the revolutionary tribunal, and guillotined on May 8, 1794 (see French Revolution).

Lavoisier's experiments were among the first truly quantitative chemical experiments ever performed. He showed that, although matter changes its state in a chemical reaction, the quantity of matter is the same at the end as at the beginning of every chemical reaction. These experiments provided evidence for the law of the conservation of matter. Lavoisier also investigated the composition of water, and he named the components of water oxygen and hydrogen. See Chemistry.

Some of Lavoisier's most important experiments examined the nature of combustion, or burning. Through these experiments, he demonstrated that burning is a process that involves the combination of a substance with oxygen. He also demonstrated the role of oxygen in animal and plant respiration. Lavoisier's explanation of combustion replaced the phlogiston theory, which postulates that materials release a substance called phlogiston when they burn.

With the French chemist Claude Louis Berthollet and others, Lavoisier devised a chemical nomenclature, or a system of names, which serves as the basis of the modern system. He described it in Méthode de nomenclature chimique (Method of Chemical Nomenclature, 1787). In Traité élémentaire de chimie (Treatise on Chemical Elements, 1789), Lavoisier clarified the concept of an element as a simple substance that could not be broken down by any known method of chemical analysis, and he devised a theory of the formation of chemical compounds from elements. He also wrote Sur la combustion en general (On Combustion, 1777) and Considerations sur la nature des acides (Considerations on the Nature of Acids, 1778).

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Lavoisier, Antoine-Laurent


b. Aug. 26, 1743, Paris, France

d. May 8, 1794, Paris

French scientist, usually regarded as the founder of modern chemistry. He was a brilliant experimenter and many-sided genius who was active in public affairs as well as in science.

Lavoisier developed a new theory of combustion that led to the overthrow of the phlogistic doctrine, which had dominated the course of chemistry for more than a century. His fundamental studies on oxidation demonstrated the role of oxygen in chemical processes and showed quantitatively the similarity between oxidation and respiration. He formulated the principle of the conservation of matter in chemical reactions. He clarified the distinction between elements and compounds and was instrumental in devising the modern system of chemical nomenclature. Lavoisier was one of the first scientific workers to introduce quantitative procedures into chemical investigations. His experimental ingenuity, exact methods, and cogent reasoning, no less than his discoveries, revolutionized chemistry. His name is indissolubly linked to the establishment of the foundations upon which modern science rests.

Lavoisier's father, an avocat au parlement (parliamentary counsel), gave him an excellent education at the Collège Mazarin, where, along with a solid classical grounding in language, literature, and philosophy, he received the best available training in the sciences, including mathematics, astronomy, chemistry, and botany. Following his family's tradition, he pursued the study of law, and he received his license to practice in 1764. His inquiring mind, however, continually drew him to science. In 1766 he received a gold medal from the Academy of Sciences for an essay on the best means of lighting a large town. Among his early work were papers on the Aurora Borealis, on thunder, and on the composition of gypsum. Pursuing an early interest in rocks and minerals, he accompanied the geologist J.-E. Guettard on a long geological trip and assisted him in preparing his mineralogical atlas of France. In 1768, after presenting a paper on the analysis of water samples, Lavoisier was admitted to the academy as adjoint-chimiste (associate chemist). He passed through all the grades in the academic structure and was made director in 1785 and treasurer in 1791.

Through his family, Lavoisier became independently wealthy in his early 20s. In 1771 he married Marie Paulze, who would later assist him in his work by illustrating his experiments, recording results, and translating scientific articles from English. In accordance with a common practice among the wealthy bourgeoisie at the time, his father bought him a title of nobility in 1772, and a few years later Lavoisier purchased the country estate of Fréchines, near Blois.

Scientific achievements

Lavoisier's name gained wide recognition when, in 1770, he refuted the then prevalent belief that water is converted into earth by repeated distillation. By carefully weighing both the earthy residue and the distilling apparatus, he demonstrated that the solid matter came from the glass vessels and not from the water.

Speculating on the nature of the traditional four elements--earth, water, air, and fire--Lavoisier began to investigate the role of air in combustion. On November 1, 1772, he deposited with the Academy of Sciences a note stating that sulfur and phosphorus when burned increased in weight because they absorbed "air," while the metallic lead formed when litharge was heated with charcoal weighed less than the original litharge because it had lost "air." The exact nature of the airs concerned in the processes he could not yet explain, and he proceeded to study the question extensively. In 1774 he published his first book, Opuscules physiques et chimiques, in which he presented the results of both his reading and his experimentation. That year Joseph Priestley prepared "dephlogisticated air" (oxygen) by heating "red precipitate of mercury." Lavoisier confirmed and extended Priestley's work. Perceiving that in combustion and the calcination of metals only a portion of a given volume of common air was used up, he concluded that the active agent was Priestley's new "air," which was absorbed by burning, and that "nonvital air," or azote (nitrogen), remained behind. He observed that birds lived longer in the new "eminently respirable air," as he described it, and he showed that this air combined with carbon to produce the "fixed air" (carbon dioxide) obtained by Joseph Black in 1754.

Recognition that the atmosphere is composed of different gases that take part in chemical reactions made it possible to identify the composition of many substances, particularly the acids. In a memoir presented to the academy in 1777, read in 1779 but not published until 1781, Lavoisier assigned to dephlogisticated air the name oxygen, or "acid producer," on the erroneous supposition that all acids were formed by its union with a simple, usually nonmetallic body. He explained combustion not as the result of the liberation of a hypothetical fire principle, phlogiston, but as the result of the combination of the burning substance with oxygen. On June 25, 1783, he announced to the academy that water was the product formed by the combination of hydrogen and oxygen; in this, however, he had been anticipated by the English chemist Henry Cavendish. As a member of a committee for finding ways to improve lighter-than-air flight with the newly invented balloons, he produced quantities of hydrogen, called "inflammable air," by decomposing water into its constituent gases. From his knowledge of the composition of water, Lavoisier was led to the beginnings of quantitative organic analysis. He burned alcohol and other combustible organic compounds in oxygen, and from the weight of water and carbon dioxide produced he calculated their composition.

Lavoisier published a brilliant attack on the phlogistic theory in 1786. Despite the opposition of Priestley and others, a growing number of scientists began to adopt his views. In 1787 a group of French chemists published the Méthode de nomenclature chimique, which classified and renamed the known elements and compounds. Reflecting Lavoisier's new discoveries and theories, the Nomenclature exerted a wide influence. Also influential was the revision in 1788 of Antoine-François de Fourcroy's popular Élémens d'histoire naturelle et de chimie, which was completely recast in terms of Lavoisier's views and according to the new chemical nomenclature. The following year Lavoisier and others established the Annales de chimie, a journal devoted to the new chemistry. Gradually the older approach based on the phlogistic theory lost adherents, and eventually Lavoisier's ideas were adopted universally.

The spread of Lavoisier's doctrines was greatly facilitated by the defined and logical form in which he presented them in his Traité élémentaire de chimie (1789). This classic book provided a concise exposition of his work and that of his followers and offered an introduction to the new approach to chemistry. In the prefatory "Discours préliminaire" Lavoisier set forth his views on the proper methods of scientific inquiry and scientific teaching, and he defended the new nomenclature. Those substances that could not be decomposed he termed substances simples, the elements out of which other matter was made. To a large extent the modern concept of an element, as against the ancient Greek idea, stems from Lavoisier. In the Traité he furnished a clear statement of his principle of the conservation of matter in chemical reactions. Nothing, he said, is created or destroyed; there are only alterations and modifications, and there is an equal quantity--an equation--of matter before and after the operation.

In addition to his purely chemical work, Lavoisier, mostly in conjunction with the mathematician and astronomer Pierre-Simon Laplace, devoted considerable attention to physical problems, especially those connected with heat. The two carried out some of the earliest thermochemical investigations, devised an apparatus for measuring linear and cubical expansions, and employed a modification of Black's ice calorimeter in a series of determinations of specific heats. Regarding heat (matière du feu) as a peculiar kind of imponderable matter, Lavoisier held that the three states of aggregation--solid, liquid, and gas--were modes of matter, each depending on the amount of matière du feu with which the substances concerned were associated. He also worked at fermentation, respiration, and animal heat, looking upon the processes concerned as essentially chemical in nature. From measurements made in his pioneering biochemical experiments on animal heat and on the gases exchanged during respiration, he concluded that respiration was a type of oxidation reaction similar to the burning of carbon. A paper discovered many years after his death showed that he had anticipated later thinkers in explaining the cyclical process of animal and vegetable life.

Public service

Throughout Lavoisier's extraordinary career as a scientist, he carried on a simultaneous career as a public servant of remarkable versatility, contributing his talents in the areas of finance, economics, agriculture, education, and social welfare, among others. In 1768 he became an assistant in one of the revenue-collecting departments of the government, subsequently becoming a full titular member of the Ferme Générale, the main tax-collecting agency. The financial and organizational abilities he displayed as a farmer-general, along with his undoubted scientific and technical capacity, led in 1775 to his appointment as régisseur des poudres (a director of the gunpowder administration). With his customary energy he set about making improvements in the chaotic powder industry. He abolished the vexatious search for saltpetre in the cellars of private houses, increased the production of the salt, and improved the manufacture of gunpowder. The post enabled Lavoisier to move to the Arsenal of Paris, where he took up residence and equipped a superb laboratory. This establishment soon became a gathering place for the scientists and advanced thinkers of the day, and the dinners presided over by his wife became famous. After dinner the guests often would be escorted to the laboratory to witness or take part in a demonstration of some new experiment. Although an increasing number of public duties claimed Lavoisier's time, he was able to regularly set aside one day a week for scientific investigations. As his influence in the Academy of Sciences grew, so did his responsibilities. He was a member of numerous official committees to look into matters concerning the public. In 1781 the notorious Franz Anton Mesmer arrived in Paris, and Lavoisier (along with Benjamin Franklin) served on a committee to investigate his cures by "animal magnetism," pronouncing them a hoax. With another committee, he explored the hospitals and prisons of Paris and recommended remedies for their deplorable state. At Fréchines he started a model farm, where he demonstrated the advantages of scientific agriculture. In 1785 he was named to the government's committee on agriculture and as its secretary drew up reports and instructions on the cultivation of crops, promulgating various agricultural schemes. As a landowner in the province of Orléans, Lavoisier was chosen a member of the provincial assembly in 1787. There he devised ways to improve local social and economic conditions by means of savings banks, insurance societies, canals, workhouses, and tax reforms. He advanced money without interest to the towns of Blois and Romorantin for the purchase of barley during the famine of 1788. He was associated with committees on hygiene, coinage, the casting of cannon, and public education. He was secretary and treasurer of the commission appointed in 1790 to secure uniformity of weights and measures throughout France, work that led to the establishment of the metric system.

A reformer and political liberal, Lavoisier was active in the French Revolution. When the Estates-General was reconvened in 1789, he became an alternate deputy and drew up the code of instructions for guidance of the deputies. He was elected to the commune of Paris and joined the moderate Society of 1789, a planning group. As an administrator of the national treasury, he published analyses of France's finances and agriculture. But his membership in the unpopular Ferme Générale was alone sufficient to make him an object of suspicion to the authorities, and, despite his many services to the nation and his renown as a scientist, he came under increasing attack from radical pamphleteers. In 1787, at Lavoisier's suggestion, a wall had been erected around Paris to halt the influx of contraband. The extremist revolutionary Jean-Paul Marat accused him of imprisoning Paris and of stopping the circulation of air. In 1791 the Ferme Générale was abolished, and Lavoisier subsequently lost his position in the gunpowder administration and was forced to leave the Arsenal. In 1793 the Reign of Terror commenced. Despite strenuous efforts by Lavoisier, the Academy of Sciences, along with the other learned societies, was suppressed. At year's end the Revolutionary Convention ordered the arrest of the former members of the Ferme Générale, and on May 8, 1794, after a trial that lasted less than a day, a revolutionary tribunal condemned Lavoisier and 27 others to death. That afternoon, he and his companions, including his father-in-law, were guillotined at the Place de la Révolution (now Concorde). His body was thrown into a common grave.