Antoine Laurent Lavoisier
Antoine Laurent Lavoisier
Antoine Laurent Lavoisier
The French chemist Antoine Laurent Lavoisier (1743-1794) was the founder of the modern science of chemistry and the author of the oxygen theory of combustion.
Antoine Laurent Lavoisier was born in Paris on Aug. 26, 1743, the son of an attorney at the Parlement of Paris. Lavoisier began his schooling at the Collège Mazarin in Paris at the age of 11. In his last two years (1760-1761) at the college his scientific interests were aroused. In the philosophy class he came under the tutelage of Abbé Nicolas Louis de Lacaille, a distinguished mathematician and observational astronomer who imbued the young Lavoisier with an interest in meteorological observation, an enthusiasm which never left him.
Lavoisier entered the school of law, where he received a bachelor's degree in 1763 and a licentiate in 1764. However, he continued his scientific education in his spare time. In 1764 he read his first paper to the French Academy of Sciences, on the chemical and physical properties of gypsum (hydrated calcium sulfate), and in 1766 he was awarded a gold medal by the King for an essay on the problems of urban street lighting.
In 1768 Lavoisier received a provisional appointment to the Academy of Sciences. About the same time he bought a share in the Tax Farm, a financial company which advanced the estimated tax revenue to the royal government in return for the right to collect the taxes. It was to prove a fateful step. Lavoisier consolidated his social and economic position when, in 1771, he married Marie Anne Pierrette Paulze, the 14-year-old daughter of a senior member of the Tax Farm. She was to play an important part in Lavoisier's scientific career, translating English chemical works into French for him, assisting in the laboratory, and drawing diagrams for his scientific works.
For 3 years following his entry into the Tax Farm, Lavoisier's scientific activity diminished somewhat, for much of his time was taken up with official Tax Farm business. He did, however, present one important memoir to the Academy of Sciences during this period, on the supposed conversion of water into earth by evaporation. By a very precise quantitative experiment Lavoisier showed that the "earthy" sediment produced after long-continued reflux heating of water in a glass vessel was not due to a conversion of the water into earth but rather to the gradual disintegration of the inside of the glass vessel produced by the boiling water.
Oxygen Theory of Combustion
During the summer and fall of 1772 Lavoisier turned his attention to the phenomenon of combustion, the topic on which he was to make his most significant contribution to science. He reported the results of his first experiments on combustion in a note to the academy on October 20 in which he reported that when phosphorus burned it combined with a large quantity of air to produce acid spirit of phosphorus (phosphoric acid) and that the phosphorus increased in weight on burning. In a second sealed note deposited with the academy a few weeks later (November 1) Lavoisier extended his observations and conclusions to the burning of sulfur and went on to add that "what is observed in the combustion of sulfur and phosphorus may well take place in the case of all substances that gain in weight by combustion and calcination: and I am persuaded that the increase in weight of metallic calces is due to the same cause."
During 1773 Lavoisier determined to review thoroughly the literature on air, particularly "fixed air," and to repeat many of the experiments of other workers in the field. He published an account of this review in 1774 in a book entitled Opuscules physiques et chimiques (Physical and Chemical Essays). In the course of this review he made his first full study of the work of Joseph Black, the Scottish chemist who had carried out a series of classic quantitative experiments on the mild and caustic alkalies. Black had shown that the difference between a mild alkali, for example, chalk (CaCO3), and the caustic form, for example, quicklime (CaO), lay in the fact that the former contained "fixed air," not common air fixed in the chalk, but a distinct chemical species, carbon dioxide (CO2), which was a constituent of the atmosphere. Lavoisier recognized that Black's fixed air was identical with the air evolved when metal calces were reduced with the charcoal and even suggested that the air which combined with metals on calcination and increased the weight might be Black's fixed air, that is, CO2.
In the spring of 1774 Lavoisier carried out experiments on the calcination of tin and lead in sealed vessels which conclusively confirmed that the increase in weight of metals on calcination was due to combination with air. But was it combination with common atmospheric air or with only a part of atmospheric air? In October the English chemist Joseph Priestley visited Paris, where he met Lavoisier and told him of the air which he had produced by heating the red calx of mercury with a burning glass and which had supported combustion with extreme vigor. Priestley at this time was unsure of the nature of this gas, but he felt that it was an especially pure form of common air. Lavoisier carried out his own researches on this peculiar substance. The result was his famous memoir "On the Nature of the Principle Which Combines with Metals during Their Calcination and Increases Their Weight," read to the academy on April 26, 1775 (commonly referred to as the Easter Memoir). In the original memoir Lavoisier showed that the mercury calx was a true metallic calx in that it could be reduced with charcoal, giving off Black's fixed air in the process. When reduced without charcoal, it gave off an air which supported respiration and combustion in an enhanced way. He concluded that this was just a pure form of common air, and that it was the air itself "undivided, without alteration, without decomposition" which combined with metals on calcination.
After returning from Paris, Priestley took up once again his investigation of the air from mercury calx. His results now showed that this air was not just an especially pure form of common air but was "five or six times better than common air, for the purpose of respiration, inflammation, and … every other use of common air." He called the air dephlogisticated air, as he thought it was common air deprived of its phlogiston. Since it was therefore in a state to absorb a much greater quantity of phlogiston given off by burning bodies and respiring animals, the greatly enhanced combustion of substances and the greater ease of breathing in this air were explained.
The "official" version of Lavoisier's Easter Memoir did not appear until 1778. In the intervening period Lavoisier had ample time to repeat some of Priestley's latest experiments and perform some new ones of his own. In addition to studying Priestley's dephlogisticated air, he studied more thoroughly the residual air after metals had been calcined. He showed that this residual air supported neither combustion nor respiration and that approximately five volumes of this air added to one volume of the dephlogisticated air gave common atmospheric air. Common air was then a mixture of two distinct chemical species with quite different properties. Thus when the revised version of the Easter Memoir was published in 1778, Lavoisier no longer stated that the principle which combined with metals on calcination was just common air but "nothing else than the healthiest and purest part of the air" or the "eminently respirable part of the air." In the following year Lavoisier coined the name oxygen for this constituent of the air, from the Greek words meaning "acid former." He was struck by the fact that the combustion products of such nonmetals as sulfur, phosphorus, charcoal, and nitrogen were acidic. He held that all acids contained oxygen and that oxygen was therefore the acidifying principle.
Lavoisier's new theory of combustion was virtually complete. He was now ready to mount a wholesale attack on the current phlogiston theory.
Lavoisier the Public Servant
Lavoisier's researches on combustion were carried out in the midst of a very busy schedule of public and private duties, especially in connection with the Tax Farm. There were also innumerable reports for and committees of the Academy of Sciences to investigate specific problems on order of the royal government. Lavoisier, whose organizing skills were outstanding, frequently landed the task of writing up such official reports. In 1775 he was made one of four commissioners of gunpowder appointed to replace a private company, similar to the Tax Farm, which had proved unsatisfactory in supplying France with its munitions requirements. As a result of his efforts, both the quantity and quality of French gunpowder greatly improved, and it became a source of revenue for the government. His appointment to the Gunpowder Commission brought one great benefit to Lavoisier's scientific career as well. As a commissioner, he enjoyed both a house and a laboratory in the Royal Arsenal. Here he lived and worked between 1775 and 1792.
Consolidation of the New Theory
Lavoisier's chemical research between 1772 and 1778 was largely concerned with developing his own new theory of combustion. In 1783 he read to the academy his famous paper entitled "Reflections of Phlogiston," a full-scale attack on the current phlogiston theory of combustion. That year Lavoisier also began a series of experiments on the composition of water which were to prove an important capstone to his combustion theory and win many converts to it. Many investigators had been experimenting with the combination of inflammable air (hydrogen) with dephlogisticated air (oxygen) by electrically sparking mixtures of the gases. All of the researchers noted the production of water, but all interpreted the reaction in varying ways within the framework of the phlogiston theory. In cooperation with mathematician Pierre Simon de Laplace, Lavoisier synthesized water by burning jets of hydrogen and oxygen in a bell jar over mercury. The quantitative results were good enough to support the contention that water was not an element, as had been thought for over 2,000 years, but a compound of two gases, hydrogen and oxygen.
Lavoisier, together with L. B. Guyton de Morveau, Claude Louis Berthollet, and Antoine François de Fourcroy, submitted a new program for the reforms of chemical nomenclature to the academy in 1787, for there was virtually no rational system of chemical nomenclature at this time. The new system was tied inextricably to Lavoisier's new oxygen theory of chemistry. The Aristotelian elements of earth, air, fire, and water were discarded, and instead some 55 substances which could not be decomposed into simpler substances by any known chemical means were provisionally listed as elements. The elements included light; caloric (matter of heat); the principles of oxygen, hydrogen, and azote (nitrogen); carbon; sulfur; phosphorus; the yet unknown "radicals" of muriatic acid (hydrochloric acid), boracic acid, and "fluoric" acid; 17 metals; 5 earths (mainly oxides of yet unknown metals such as magnesia, barite, and strontia); three alkalies (potash, soda, and ammonia); and the "radicals" of 19 organic acids. The acids, regarded in the new system as compounds of various elements with oxygen, were given names which indicated the element involved together with the degree of oxygenation of that element, for example sulfuric and sulfurous acids, phosphoric and phosphorus acids, nitric and nitrous acids, the "ic" termination indicating acids with a higher proportion of oxygen than those with the "ous" ending. Similarly, salts of the "ic" acids were given the terminal letters "ate," as in copper sulfate, whereas the salts of the"ous" acids terminated with the suffix "ite," as in copper sulfite. The total effect of the new nomenclature can be gauged by comparing the new name "copper sulfate" with the old term "vitriol of Venus."
Lavoisier employed the new nomenclature in his Elements of Chemistry, published in 1789. This work represents the synthesis of Lavoisier's contribution to chemistry and can be considered the first modern text-book on the subject. The core of the Elements of Chemistry was the oxygen theory, and the work became a most effective vehicle for the transmission of the new doctrines. It remains a classic in the history of science.
His Physiological Studies
The relationship between combustion and respiration had long been recognized from the essential role which air played in both processes. Lavoisier was almost obliged, therefore, to extend his new theory of combustion to include the area of respiration physiology. His first memoirs on this topic were read to the Academy of Sciences in 1777, but his most significant contribution to this field was made in the winter of 1782/1783 in association with Laplace. The result of this work was published in a famous memoir, "On Heat." Lavoisier and Laplace designed an ice calorimeter apparatus for measuring the amount of heat given off during combustion or respiration. By measuring the quantity of carbon dioxide and heat produced by confining a live guinea pig in this apparatus, and by comparing the amount of heat produced when sufficient carbon was burned in the ice calorimeter to produce the same amount of carbon dioxide as that which the guinea pig exhaled, they concluded that respiration was in fact a slow combustion process. This continuous slow combustion, which they supposed took place in the lungs, enabled the living animal to maintain its body temperature above that of its surroundings, thus accounting for the puzzling phenomenon of animal heat.
Lavoisier continued these respiration experiments in 1789-1790 in cooperation with Armand Seguin. They designed an ambitious set of experiments to study the whole process of body metabolism and respiration using Seguin as a human guinea pig in the experiments. Their work was only partially completed and published because of the disruption of the Revolution; but Lavoisier's pioneering work in this field served to inspire similar research on physiological processes for generations to come.
As the Revolution gained momentum from 1789 on, Lavoisier's world inexorably collapsed around him. Attacks mounted on the Tax Farm, and it was eventually suppressed in 1791. In 1792 Lavoisier was forced to resign from his post on the Gunpowder Commission and to move from his house and laboratory at the Royal Arsenal. On Aug. 8, 1793, all the learned societies, including the Academy of Sciences, were suppressed.
It is difficult to assess Lavoisier's own attitude to the political turmoil. Like so many intellectual liberals, he felt that the Old Regime could be reformed from the inside if only reason and moderation prevailed. Characteristically, one of his last major works was a proposal to the National Convention for the reform of French education. He tried to remain aloof from the political cockpit, no doubt fearful and uncomprehending of the violence he saw therein. However, on Nov. 24, 1793, the arrest of all the former tax gatherers was ordered. They were formally brought to trial on May 8, 1794, and convicted with summary justice of having plundered the people and the treasury of France, of having adulterated the nation's tobacco with water, and of having supplied the enemies of France with huge sums of money from the national treasury. Lavoisier, along with 27 of his former colleagues, was guillotined on the same day.
The best source for a study of Lavoisier is the translation of his Traité elémentaire de chimie, printed as Elements of Chemistry with an introduction by Douglas McKie, in 1965. The most comprehensive biography of Lavoisier in English is Douglas McKie, Antoine Lavoisier: Scientist, Economist, Social Reformer (1952). Henry Guerlac, Lavoisier: The Crucial Years (1961), deals with the factors which led Lavoisier to study the combustion problem. See also Sidney J. French, Torch and Crucible: The Life and Death of Antoine Lavoisier (1941). James Bryant Conant, ed., The Overthrow of the Phlogiston Theory (1955), is a clear and valuable study of this aspect of the chemical revolution. □
FRENCH CHEMIST 1743–1794
Antoine-Laurent Lavoisier, born in Paris, France, is considered the father of modern chemistry. During the course of his career, Lavoisier managed to transform just about every aspect of chemistry. But Lavoisier was not just a scientist. He was involved in French taxation politics during a turbulent time in the country's history—the French Revolution (the first major social revolution proclaiming the liberty of the individual [ca. 1789–1799]). Because of his involvement with the ruling class, he was executed during the revolutionary days known as the Terror, at the height of his scientific career.
Just before and during the French Revolution, another revolution was taking place. In any study of the history of chemistry, the period between 1770 and 1790 is commonly regarded as the "Chemical Revolution." This revolution, which marked the beginnings of modern chemistry, occurred in large part as a result of Lavoisier's scientific excellence and brilliant experimental capabilities. He played a role in many aspects of the Chemical Revolution, including the abandonment of the phlogiston theory of combustion , the evolution of the concept of an element, and the development of a new chemical nomenclature.
Perhaps Lavoisier's most important accomplishment was his role in the dismantling of the phlogiston theory of combustion. Phlogiston was a substance believed to be emitted during combustion and the calcination of metals . Earlier chemists, such as the Germans Johann Becher (1635–1682) and George Stahl (1660–1734), supposed that a metal was composed of calx and phlogiston, and that burning resulted from the loss of phlogiston. The fact that metals actually gained weight during combustion was usually explained away by the theory that phlogiston had negative weight. Lavoisier, like some others, saw that it was illogical for anything to have negative weight.
To prove his supposition that phlogiston did not exist, Lavoisier introduced quantitative measurement to the laboratory. Using precise weighing, he showed that in all cases of combustion where an increase in weight was observed, air was absorbed, and that when a calx was burned with charcoal, air was liberated. In addition to showing by precise measurement that phlogiston did not exist, Lavoisier's findings also implied that the total weight of the substances taking part in a chemical reaction remains the same before and after the reaction—an early statement of the law of conservation of mass. By ridding the chemical world of the phlogiston theory of combustion using quantitative analysis, Lavoisier was able to push chemistry toward its modern state. No longer would counterintuitive notions such as a substance having negative weight occupy the minds of chemists.
Likewise, Lavoisier's work was also able to refute the theory that the world was composed of either one, two, three, or four elements. Lavoisier defined an element as the "last point which analysis is capable of reaching," or in modern terms, a substance that cannot be broken down any further into its components. This break from the theories of the ancient world allowed chemists to pursue the study of chemistry with a different outlook of the world. By defining elements as the last points of analysis, Lavoisier opened up new investigative possibilities. In his classic textbook Elements of Chemistry (generally acknowledged to be the first modern chemistry textbook), he compiled a list of all the substances he could not break down into simpler substances, that is, he created the first table of elements (although not the Periodic Table of later years). By acknowledging that there could be more elements than his preliminary list provided, Lavoisier left the search for more elements to his successors.
Lavoisier's dismantling of the phlogiston theory and his systematic definition of an element caused many chemists to view basic concepts differently and to embrace the principles of Lavoisier's new chemistry. One of the methods Lavoisier used to spread his ideas was to construct a new and logical system for naming chemicals. Working with Claude Berthollet and Antoine Fourcroy, Lavoisier developed a new nomenclature based on three general principles: (1) Substances should have one fixed name, (2) names ought to reflect composition when known, and (3) names should generally be chosen from Greek or Latin roots. This new nomenclature was published in 1787, and it swayed even more chemists to adopt the new chemistry.
Nevertheless, Lavoisier did not always hit on the right theories for the right reasons. For example, he believed that acidity was caused by the presence of oxygen in a compound. Lavoisier concluded in 1776 that oxygen was the part of a compound that was responsible for the property of acidity because he had isolated it from so many acids. In fact, oxygen means "acid former." According to Lavoisier, the other portion of the compound combined with the oxygen was called an "acidifiable base" and it was responsible for the specific properties of the compound. Although these concepts turned out to be wrong, the thinking behind them is important since it represented the first systematic attempt to chemically characterize acids and bases.
Lavoisier was not only interested in the theoretical aspects of chemistry. He also devoted much of his time to studying more practical topics, such as the best ways of lighting streets in a large town. In addition, Lavoisier took part in the development of what was to become the metric system and he was involved in improving the manufacture of gunpowder.
Although Lavoisier was independently wealthy, thanks to a considerable fortune inherited from his mother, he sought to increase his wealth in order to pursue his scientific career on a larger scale. For this reason, he entered the Ferme, a private company whose members purchased the privilege of collecting national taxes. During the French Revolution, the tax collectors of the Ferme were the subject of popular hatred. Although he carried out his duties honestly, Lavoisier was associated with the perceived corruption of the tax collection system. At the height of the Revolution, Lavoisier was arrested and executed by beheading in 1794.
Lavoisier's untimely death ended an era in the history of chemistry. With his contributions to chemistry ranging from developing the modern concept of combustion to establishing the language of chemistry, Lavoisier provided the foundation for the study of chemistry as a modern science.
see also Berthollet, Claude-Louis.
Lydia S. Scratch
Donovan, Arthur (1993). Antoine Lavoisier: Science, Administration and Revolution. Oxford, U.K.: Blackwell.
Yount, Lisa (1997). Antoine Lavoisier: Founder of Modern Chemistry. Springfield, NJ: Enslow Publishers.
Beretta, Marco, ed. "Panopticon Lavoisier." Available from <http://moro.imss.fi.it/lavoisier>.
Poirier, Jean-Pierre. "Lavoisier's Friends." Available from <http://historyofscience.free.fr>.
LAVOISIER, ANTOINE (1743–1794), French scientist, commonly considered the founder of modern chemistry.
Antoine Laurent Lavoisier was born in Paris, France on 26 August 1743. A child of privilege (his father was a wealthy lawyer and his mother was the daughter of a well-to-do attorney), Antoine was educated, from the age of eleven, at the Collège Mazarin, from which he received a baccalaureate in law in 1763. By this time his passion for science had already eclipsed his interest in law, and he participated in the expeditions of geologist Jean-Étienne Guettard (1715–1786) to prepare the first mineralogical atlas of France. To enhance his knowledge of the chemical nature of minerals, Lavoisier attended the lectures of the chemist Guillaume-François Rouelle (1703–1770) and began doing research on gypsum in a laboratory that he set up in his Parisian home. To support his scientific activities, Lavoisier supplemented the inheritance he received from his father with a 1768 investment in the Ferme générale, a private agency used by the French government to collect taxes on tobacco, salt, and imported goods. During this period Lavoisier was elected to the Academy of Sciences on the basis of some work he had done with Guettard.
Through his participation in the Ferme générale, Lavoisier met Marie Anne Paulze, the thirteen-year-old daughter of a fellow member, and married her in 1771. A talented linguist and artist, she translated English scientific publications into French for her husband and drew the illustrations for his papers and books. During the 1770s this research centered on combustion and calcination (the formation of a powdery substance, or calx, from roasting a metal or mineral). In the spring of 1772, Lavoisier served as a member of a committee formed by the Academy of Sciences to study the disappearance of diamonds when they were intensely heated. He was eventually able to establish that the diamonds' destruction was due to combustion, with fixed air (which he would later name "carbon dioxide") as the product.
Some scholars have proposed that Lavoisier's important work on combustion originated in his research on chemical effervescence, a process in which certain substances, when heated, release a gas. In the summer of 1772 he found that litharge, a lead ore, when heated with charcoal produced both lead and a gas. He also knew that metals absorbed air to form calxes. Further studies in the fall showed that phosphorus combined with a large quantity of air when it burned, as did sulfur. At this time Lavoisier mistakenly believed that this weight gain accompanying combustion and calcination was due to fixed air. His confusion was not resolved until the English chemist Joseph Priestley (1733–1804), on his 1774 visit to Paris, informed him of his discovery of a new gas that he had called "dephlogisticated air." Though Lavoisier, in his writings, downplayed the significance of Priestley's influence, many modern scholars see this discovery of an "air" that facilitated burning as crucial in the evolution of his understanding of chemistry.
With apparatus and techniques superior to Priestley's, Lavoisier was able to confirm and extend the English chemist's work on this "eminently respirable air." By 1777 he was convinced that the elemental atmospheric air of past natural philosophers was actually a mixture of two gases, one aiding combustion, the other frustrating it. Because the vital air aiding combustion formed acids when it combined with such nonmetals as sulfur and phosphorus, Lavoisier called it oxygen from the Greek roots signifying "acid producer." Eventually he became convinced of the elemental nature of oxygen, and he used it in his new theory of combustion: burning was simply oxidation. He also criticized the phlogiston theory, which interpreted combustion as the liberation of a constituent (called phlogiston) from burnable substances.
During the 1780s, Lavoisier extended his oxygen theory to include respiration and the composition of water. He and Pierre-Simon de Laplace (1749–1827) did a series of experiments on living things in which they found that a guinea pig, like a candle flame, generated both heat and carbon dioxide. Influenced by the experiments of English chemist Henry Cavendish (1731–1810) on "inflammable air," whose combustion produced water, Lavoisier argued that water is actually a compound of two gases, hydrogen (his name for "inflammable air") and oxygen. Although Lavoisier denigrated Cavendish's interpretation of his discovery in terms of the phlogiston theory, modern scholars, while admitting the superiority of Lavoisier's explanation, think that he went too far in claiming that he should be credited with the discovery of water's compound nature.
To help establish his new oxygen theory, Lavoisier and his principal French followers published a book on chemical nomenclature that helped establish a new and clearer language for chemistry. Lavoisier used this new terminology in his most important work, Traitéélémentaire de chimie (Elementary treatise of chemistry, 1789). Like Isaac Newton's (1642–1727) Principia, Lavoisier's Traité marked the origin of an important modern science. This first textbook of the new chemistry contained a table of elements and the first clear statement of the law of the conservation of matter.
During the final five years of his life, Lavoisier participated in the development and implementation of the metric system, improved French gunpowder, suggested hospital and prison reforms, and published influential papers on experimental farming and economics. Despite his services to science and the state, he was unfortunate in being a political moderate at a time of extremists. In 1794, during the Reign of Terror, he and many other tax farmers were guillotined. Neither his head nor his body has ever been found.
Duveen, Denis I., and Herbert S. Klickstein. A Bibliography of the Works of Antoine Laurent Lavoisier, 1743–1794. London, 1954. This book, whose goal was to gather information on all Lavoisier's publications, had to be supplemented with another work published in 1965, which also included items written about Lavoisier up to 1963.
Lavoisier, Antoine-Laurent. Oeuvres de Lavoisier. Paris, 1965. This reprint of the six volumes originally published from 1862 to 1893 is not perfectly complete, but it allows scholars and other researchers an entreée into Lavoisier's most significant publications.
Donovan, Arthur. Antoine Lavoisier: Science, Administration, and Revolution. Cambridge, U.K., 1996. A comprehensive biography of the scientist and public figure for general readers.
Poirier, Jean-Pierre. Lavoisier: Chemist, Biologist, Economist. Translated by Rebecca Balinski. Philadelphia, 1996. When this biography was published in French in 1993, some reviewers stated that it supplanted all previous biographies and became the standard treatment of Lavoisier's life and work.
Robert J. Paradowski
Antoine Laurent Lavoisier
Antoine Laurent Lavoisier
French Chemist and Economist
Antoine Lavoisier is regarded as the founder of modern chemistry. Although he made few discoveries of new substances or processes, his work in chemical theory provided a synthesis of the discoveries of his contemporaries and a framework upon which subsequent work could be based. He is perhaps best known for his discovery of the role that oxygen plays in combustion, his statement of the conservation of matter in chemical reactions, his clarification of the difference between elements and compounds (molecules), and his part in the development of the modern system of chemical nomenclature.
The son of a prosperous lawyer, Lavoisier was educated at the College Mazarin, where he began his scientific studies after initially studying law. His early scientific publications led to his election to the Royal Academy of Sciences in 1768, at age 25. His father bought a title of nobility for him in 1772, and he became a member of the Farmers-General, a private company that collected taxes for the royal government. His personal wealth and political influence grew, and as a member of the Gunpowder Commission, he lived in the Paris Arsenal, where he set up a private laboratory to test the results of chemical experiments performed by others and to carry out his own. In 1791 he was appointed Secretary of the Treasury.
Even though Lavoisier was involved in social reforms, such as old age pensions, and supported liberal political causes, after the revolution he was regarded with suspicion because of his previous close connection with the royal government. He was arrested and imprisoned in 1793, tried, and executed by guillotine in 1794.
Lavoisier's contribution to the founding of modern chemistry was principally in the area of theory. He confirmed, consolidated, extended, and explained the many new discoveries made by his contemporaries on the European continent and in England, especially those of Joseph Black (1728-1799), Henry Cavendish (1731-1810), and Joseph Priestley (1733-1804). The result was a new theoretical understanding of chemical processes that provided the framework for the development of chemistry as a modern science.
Lavoisier discovered the part that oxygen plays in combustion (burning) and developed a theory that explained combustion, the oxidation of metals, and respiration as all being similar reactions of chemical substances with oxygen gas. Additionally, his theory of combustion discredited the phlogiston theory, which had been a major detriment to scientific progress.
Although not the first to employ careful quantitative methods in the study of chemical processes, his endorsement and use of them was significant in the development of chemistry as a quantitative physical science. The use of a calorimeter by Lavoisier and Pierre Simon Laplace (1749-1827) to measure specific heats and heats of reaction was an important step in the founding of thermochemistry. Lavoisier was also the first to realize that all substances can exist in three states—gas, liquid, and solid. He played a significant part in the development of the metric system and in revolutionizing the nomenclature of chemical substances, both of which are still in use today in much the same form. In this new system of nomenclature, the name of a substance indicates the elements of which it is made.
Despite his brilliance and the enormous contributions he made to the founding of modern chemistry, Lavoisier was far from perfect. He was constantly enmeshed in disputes in which he claimed to be the first to make various discoveries, though his claims of priority had no basis in fact. He used the results of other scientists freely, often without acknowledging their work. Perhaps his contribution would have been even greater had he been more willing to work with his scientific contemporaries with greater cooperation and mutual appreciation.
J. WILLIAM MONCRIEF