Antoine Lavoisier

How to use this course

Antoine Lavoisier is called the founder of modern chemistry. His method was a physicist’s: he weighed everything that entered and left a reaction, gases included, and insisted that the totals balance. With that rule he overturned the phlogiston theory, identified oxygen’s role in combustion, showed that water is a compound, and reorganized the names of substances. With Pierre-Simon Laplace he turned heat into a measurable quantity and showed that breathing is a slow combustion.

Each technical lesson opens with a paragraph for the general reader, then states the key results precisely, reconstructs Lavoisier’s numbers in modern units and ends with exercises whose solutions are folded. Old French units appear because his data were recorded in them: 1 livre (pound) = 16 onces (ounces) = 489.5 g, 1 once = 8 gros = 576 grains, so 1 grain ≈ 53.1 mg; 1 pouce (inch) ≈ 2.707 cm, so 1 cubic inch ≈ 19.84 cm³.

Timeline

Paris, 1743–1764

Antoine-Laurent Lavoisier was born in Paris on 26 August 1743. His father was an attorney at the Parlement of Paris, and the family was prosperous. His mother died when he was five, leaving him a substantial inheritance.

In 1754 he entered the Collège des Quatre-Nations, known as the Collège Mazarin, one of the best schools of the University of Paris. Besides the classics he studied mathematics and astronomy with the abbé Nicolas-Louis de Lacaille, an astronomer who had mapped the southern sky from the Cape of Good Hope. From Lacaille he learned the habits of careful measurement that later shaped his chemistry.

Family tradition pointed to the law. He took a bachelor’s degree in law in 1763 and the licence in 1764 and was admitted to the bar, but never practised. At the same time he attended the public chemistry lectures of Guillaume-François Rouelle at the Jardin du Roi. Rouelle taught chemistry in the tradition of Georg Ernst Stahl, in which burning releases a principle called phlogiston. Lavoisier’s first paper read to the Academy of Sciences analysed gypsum and the water it takes up when plaster sets.

Geology, the Academy and the tax farm, 1763–1771

The naturalist Jean-Étienne Guettard, a friend of the family, took Lavoisier on field trips from 1763 and enlisted him in a project for a mineralogical atlas of France. In 1767 they surveyed Alsace and Lorraine together. Lavoisier recorded rock layers in sequence and with numbers, and his notes on the alternation of marine and shore deposits are now read as an early contribution to stratigraphy.

In 1766 the Academy’s competition on the best way to light the streets of Paris earned him a gold medal from the king. In 1768, at 25, he was elected to the Academy of Sciences. The same year he bought a share in the Ferme générale, the company of financiers who collected the indirect taxes on salt, tobacco and goods entering Paris on the crown’s behalf. The investment gave him an income large enough to pay for his laboratory. It also tied him to the most hated institution of the old regime, a fact that would cost him his life.

Marriage, the Arsenal and the turn to air, 1771–1775

In December 1771 Lavoisier married Marie-Anne Pierrette Paulze, the thirteen-year-old daughter of a senior tax farmer. She became his scientific partner. She learned English to translate British chemistry for him, studied drawing with Jacques-Louis David and made the engravings of apparatus in the Traité, kept laboratory records, and hosted the gatherings where his ideas were argued over. In 1788 she published a French translation of Richard Kirwan’s Essay on Phlogiston with critical notes by the new school.

The sealed note

In 1772 Lavoisier turned to combustion. In November he deposited a sealed note with the Academy, a standard way of establishing priority: sulfur and phosphorus gain weight when burned, because they absorb air, and the same is probably true of metals when they are calcined. In February 1773 he wrote in his notebook that he expected his work to produce a revolution in physics and chemistry.

In 1774 he heated tin in sealed glass vessels and showed that the total weight did not change; when the vessel was opened air rushed in, and the gain in weight matched the weight of the calx formed. In the autumn of that year the English chemist Joseph Priestley, visiting Paris, told him of a new air obtained by heating the red calx of mercury, in which a candle burned brilliantly. Carl Wilhelm Scheele in Sweden had prepared the same gas independently. Lavoisier took up the experiment and, on 26 April 1775, read his “Easter memoir” on the principle that combines with metals during calcination.

In 1775 he became one of four commissioners of the royal Gunpowder Administration and moved into the Arsenal in Paris, where he lived and kept his laboratory until 1792.

The balance and the conservation of mass

For the general reader. Burn a log and the ash weighs much less than the wood. Rust iron and it gets heavier. Lavoisier insisted that matter is neither lost nor gained in such changes: if you also weigh the gases that leave and enter, the totals agree. He used this rule as the foundation of all chemical reasoning.

Earlier chemists had often assumed something like this. Lavoisier made it an explicit axiom and a working tool. In the Traité’s chapter on vinous fermentation he wrote, in effect, an equation: the must of grapes equals carbonic acid plus alcohol, and from the weights of all the products he deduced the composition of sugar. A chemical equation is a balance sheet in this sense, and each element must balance separately.

Limits

In special relativity, the conserved quantity is energy, and a system’s rest mass changes by \(\Delta E/c^2\) when it gives off energy \(\Delta E\). For chemical reactions \(\Delta E\) is a few hundred kilojoules per mole, so the mass change is of order \(10^{-9}\) of the total, far below any balance.

Calcination, combustion and oxygen

For the general reader. The phlogiston theory said that a burning body gives something off. Lavoisier showed that it takes something in: a particular part of the air, which he named oxygen. A metal “calx”, what we call an oxide, is the metal plus oxygen, not the metal minus phlogiston.

Two theories

In Stahl’s theory, metal = calx + phlogiston. Calcination releases phlogiston into the air; heating the calx with charcoal, rich in phlogiston, restores the metal. The theory explained a great deal qualitatively. But calxes weigh more than their metals, so phlogiston would have to weigh less than nothing, or the theory needed further assumptions. Lavoisier’s reading is the reverse:

The mercury experiments

Mercury calx is special: it gives up its oxygen on stronger heating alone, without charcoal. This made a closed cycle possible. In the version described in chapter 3 of the Traité, Lavoisier heated mercury near its boiling point for twelve days in a retort whose neck opened under a bell jar of air over mercury.

The experiment is a full analysis and synthesis: air is separated into two components and recombined, and mercury goes round a cycle, with the balance and the measured volumes accounting for each step. In the late 1770s Lavoisier named the active part oxygène, from Greek for “acid-former”, because he believed it to be a constituent of every acid. The second half of the name was mistaken: hydrochloric acid contains no oxygen, as Humphry Davy showed in 1810.

Measuring gases: the composition of air

For the general reader. To balance a reaction that involves air, you must weigh gases. Since that is hard, you measure volumes and convert. Lavoisier corrected every volume for the pressure and temperature of the day and used gas densities to turn volumes into weights. This made pneumatic chemistry part of quantitative physics.

The Traité reduced gas volumes to a barometric height of 28 French inches (about 758 mm of mercury) and a temperature of 10° on the Réaumur scale (12.5 °C). Boyle’s law, \(pV\) constant at fixed temperature, was known; the linear expansion of gases with temperature was being measured in his time and was established by Joseph-Louis Gay-Lussac in 1802. In modern form:

From the mercury experiment Lavoisier concluded that about one sixth of air was respirable. Elsewhere in the Traité he gave a better estimate of about 27 parts respirable air to 73 of azote (nitrogen) by volume. The modern dry-air value is about 21% oxygen. Slow calcination never removed all the oxygen, so the mercury method underestimated it.

Water is not an element

For the general reader. Since antiquity water had been one of the four elements. In 1783 Lavoisier burned “inflammable air”, our hydrogen, in oxygen and obtained water; the next year he did the reverse, passing steam over red-hot iron to split water into its parts. Both directions, weighed, showed that water is a compound of two gases.

Henry Cavendish had isolated inflammable air in 1766 and found by 1781 that burning it with common air produced water. In June 1783 Charles Blagden, visiting Paris, reported this to Lavoisier, who with Laplace immediately burned the two gases together and collected water. Lavoisier, unlike Cavendish, drew the conclusion that water is a compound of the two airs and named the inflammable one hydrogène, “water-former”. In 1784, with the engineer Jean-Baptiste Meusnier, he decomposed water by passing steam through a red-hot iron gun barrel: the iron gained weight as it oxidized and hydrogen came out at the far end. In 1785 they carried out a large public synthesis and analysis before members of the Academy.

The result removed a central support of the phlogiston theory. Metals dissolving in acids give off inflammable air, which many took to be phlogiston itself. On Lavoisier’s scheme the hydrogen comes from the water in the acid, and the metal takes its oxygen. Every reaction could now be described without phlogiston and with the books balanced.

Caloric and the ice calorimeter

For the general reader. How much heat does a burning candle give? In the winter of 1782–83 Lavoisier and the mathematician Pierre-Simon Laplace answered such questions with a vessel packed with ice: whatever heat a body gives off melts ice, and the meltwater is weighed. Their memoir on heat made calorimetry a precise science.

The apparatus

The calorimeter had three nested chambers. The body under study sat in an inner wire cage. Around it a middle chamber packed with ice at 0 °C absorbed its heat; the meltwater drained out and was weighed. An outer jacket of ice kept heat from the room from reaching the middle chamber. Because melting ice stays at 0 °C, the measurement is of heat alone, independent of temperature readings.

The latent heat of fusion had been discovered by Joseph Black around 1761. Lavoisier explained heat by a weightless fluid, caloric, which he listed among the simple substances. The memoir of 1783 is more cautious: it sets out both the caloric hypothesis and the mechanical one, in which heat is the vis viva of the insensible motions of the particles of bodies, and builds its method on a principle valid under either.

In modern terms, the enthalpy \(H\) is a state function: \(\Delta H\) for a reaction depends only on the initial and final states. Germain Henri Hess extended the principle in 1840 to reactions taken by different paths.

Respiration as slow combustion

For the general reader. Why are animals warm? Lavoisier and Laplace put a guinea pig in the ice calorimeter and measured both the ice it melted and the carbon dioxide it breathed out. Burning charcoal to produce the same amount of carbon dioxide melts nearly the same amount of ice. Breathing, they concluded, is a slow combustion, and it is the source of animal heat.

Lavoisier and Laplace judged 10.4 and 13 close enough, given the different conditions of the two experiments, to conclude that respiration is a combustion of carbon, very slow but otherwise like that of charcoal, taking place in the lungs. Later work by Lavoisier showed that respiration also burns hydrogen to water, which accounts for much of the difference; and the oxidation takes place throughout the tissues, not in the lungs. From 1789 he measured human oxygen consumption with Armand Seguin as the subject, at rest, after meals and while working a treadle, and found that it increased with food, work and cold. The Revolution ended these experiments.

Names, elements and the Traité

For the general reader. Before 1787 chemical substances had names like “oil of vitriol” and “flowers of zinc”, which said nothing about composition. Lavoisier and three colleagues proposed names built from the elements a substance contains. Two years later his Traité set out the new chemistry from first principles, with a list of the simple substances that analysis had not yet split.

The nomenclature

The Méthode de nomenclature chimique (1787), by Guyton de Morveau, Lavoisier, Berthollet and Fourcroy, named compounds from their constituents. Oxygen compounds of a base became oxides; acids with more and less oxygen took endings -ic and -ous (sulfuric, sulfurous); their salts took -ate and -ite (sulfate, sulfite). The system survives, with modifications, in modern inorganic nomenclature.

The Traité élémentaire de chimie appeared in 1789; Robert Kerr’s English translation, Elements of Chemistry, followed in Edinburgh in 1790. Its table listed 33 simple substances in four groups: light, caloric, oxygen, azote and hydrogen; non-metallic substances that can be oxidized or acidified (sulfur, phosphorus, carbon and the unknown radicals of muriatic, fluoric and boracic acids); 17 metals; and five salifiable earths (lime, magnesia, baryta, alumina and silica).

Reformer: powder, farming and measures

Lavoisier spent as much time on public administration as on chemistry. At the Gunpowder Administration from 1775 he improved the supply of saltpetre and the quality of French powder, which was exported in quantity during the American War of Independence. Among those he trained at the Arsenal was Éleuthère Irénée du Pont, who later founded a powder works in Delaware.

He ran an experimental farm in the Sologne and served as secretary of the government’s committee on agriculture, reporting in 1788 that the tax system made reform impossible for tenant farmers. He worked on water supply, hospital ventilation and prison conditions, and on a new wall around Paris to stop smuggling, which made the tax farmers still more unpopular. In 1789 he helped found the Annales de chimie, the journal of the new chemistry.

Under the Revolution he served the new regime as a commissioner of the treasury and sat on the Academy’s commission of weights and measures. Its report of March 1791 proposed a unit of length based on the size of the Earth, the start of the metric system, adopted by the National Convention in August 1793. He also wrote on public education and national wealth.

Revolution, death and legacy, 1791–1794

From January 1791 Jean-Paul Marat, who had once failed to win the Academy’s approval for his own theory of fire, denounced Lavoisier in print as a tax farmer and an enemy of the people. In 1792 Lavoisier left the Arsenal. On 8 August 1793 the Convention abolished the Academy of Sciences along with the other royal academies. In November it ordered the arrest of all former tax farmers, and Lavoisier gave himself up. In December he was removed from the commission of weights and measures.

On 8 May 1794 the Revolutionary Tribunal tried the former tax farmers in a single morning on charges of defrauding the people, and that afternoon Lavoisier was guillotined at the Place de la Révolution with 27 others, among them his father-in-law Jacques Paulze. The story that the presiding judge declared that the Republic needed no savants is a legend. The mathematician Joseph-Louis Lagrange remarked the next day that it had taken only a moment to cut off the head, and a century might not produce another like it. About a year and a half later the government acknowledged that he had been wrongly condemned and returned his property to his widow. Marie-Anne Paulze Lavoisier published his collected memoirs and later married Benjamin Thompson, Count Rumford, whose experiments on cannon boring had argued that heat is motion rather than caloric.

Legacy

• Method: the closed mass balance, applied to gases as well as solids and liquids, is the basis of quantitative chemistry and chemical engineering.
• Theory: the oxygen theory of combustion, the compound nature of water and air, and the operational notion of an element, which John Dalton’s atomic theory (1808) turned into a theory of atomic weights.
• Physics: calorimetry and the principle that the heat of a reaction depends only on initial and final states, a forerunner of the first law of thermodynamics.
• Physiology: respiration as oxidation and the measurement of metabolism by gas exchange and heat.
• Language: the systematic nomenclature still taught to every student of chemistry.

Connections

People linked to Antoine Lavoisier across this collection. A name without a link has no page here yet. See Antoine Lavoisier in the network of all 337 lives →

Teachers and advisors

• Guillaume-François Rouelle
• Jean-Étienne Guettard 1763-1767
• Nicolas-Louis de Lacaille 1760-1761

Students

• Éleuthère Irénée du Pont

Influenced by

• Joseph Black
• Robert Boyle

Influenced

• Humphry Davy
• John Dalton
• Joseph Louis Gay-Lussac
• Julius Robert Mayer
• Jöns Jacob Berzelius
• Sadi Carnot

Colleagues and collaborators

• Alessandro Volta 1782
• Benjamin Franklin 1784
• Carl Wilhelm Scheele
• Gaspard Monge
• Joseph-Louis Lagrange
• Pierre-Simon Laplace 1782-1784
• Antoine-François Fourcroy 1787
• Armand Seguin 1789-1791
• Claude-Louis Berthollet 1787
• Jean-Baptiste Meusnier 1784-1785
• Louis-Bernard Guyton de Morveau 1787

Rivals

• Carl Wilhelm Scheele 1774
• Count Rumford
• Henry Cavendish
• Joseph Priestley

Family

• Marie-Anne Paulze Lavoisier

Also mentioned in this life

• Amedeo Avogadro

Fields

• chemistry 21 lives
• physiology 5 lives

Sources and further reading

Biography

1. Antoine Lavoisier, Wikipedia.
2. American Chemical Society, Antoine-Laurent Lavoisier: The Chemical Revolution, International Historic Chemical Landmark booklet.
3. D. McKie, Antoine Lavoisier: Scientist, Economist, Social Reformer, Schuman, 1952.
4. F. L. Holmes, Lavoisier and the Chemistry of Life, University of Wisconsin Press, 1985.
5. J.-P. Poirier, Lavoisier: Chemist, Biologist, Economist, University of Pennsylvania Press, 1996.

Chemistry and physics

1. A. Lavoisier, Traité élémentaire de chimie, Paris, Cuchet, 1789; Elements of Chemistry, trans. R. Kerr, Edinburgh, 1790 (Project Gutenberg).
2. A. Lavoisier and P.-S. Laplace, Mémoire sur la chaleur, Mémoires de l’Académie royale des sciences for 1780 (1784). English excerpt.
3. L. B. Guyton de Morveau, A. Lavoisier, C. L. Berthollet, A. F. Fourcroy, Méthode de nomenclature chimique, Paris, 1787.
4. On the early history of thermochemistry and calorimetry, Pure and Applied Chemistry 59 (1987) 91.
5. Elements of Chemistry, Wikipedia.
6. H. Guerlac, Lavoisier: The Crucial Year, Cornell University Press, 1961.