JMS Pearce
Hull, England

In the 1780s, a period of rumbling social unrest in France, the lives of two famous men, a scientist and an artist, would interact. Antoine Laurent Lavoisier (1743–1794) is often associated with the discovery of oxygen; Jacques-Louis David (1748–1825) was the preeminent neoclassical artist.

Lavoisier was a French nobleman, justly celebrated for many scientific discoveries which, at the age of twenty-five, gained him admission into France’s foremost natural philosophy society, the Académie des Sciences. He was an aristocrat and wealthy entrepreneur, tax collector for the Ferme Générale, and a commissioner charged with improving the production of gunpowder. He and his wife, Marie Anne (née Pierrette Paulze, 1758–1836) were prominent members of the Parisian intelligentsia and patrons of the arts.

Lavoisier, phlogiston, and oxygen

A German chemist, Georg Ernst Stahl, believed that every combustible substance contained a component of fire, which he named phlogiston (Greek “ϕλογιστός”, “inflammable”).¹ Lavoisier disagreed. Combustible substances such as charcoal lost weight when burned, owing to loss of its phlogiston component to the air. However, when metals such as lead were heated in air, the resulting calx (oxide) weighed more than the original metal, not less, as would be expected if the lead had lost the phlogiston component. Similarly, when Lavoisier ignited phosphorus and sulphur, they too burned and gained weight by combining with air. Crucially, he was able to capture volumes of what he called air liberated when lead calx was heated. Lavoisier thought these results were not explained by phlogiston, but by combining with and then releasing air itself.² However, which component of air caused a gain in weight remained a mystery.

Joseph Priestley (1733–1804), son of a Yorkshire cloth-maker, in August 1774 had heated red mercury calx and collected the emitted gas in which a candle flame burnt intensely, and which kept a mouse alive four times longer than a similar quantity of air. Priestley found that “air is not an elementary substance, but a composition,” or mixture, of gases. He had discovered oxygen, in all but name, a highly reactive gas he called “dephlogisticated air.”³ He believed his “pure air” enhanced respiration and caused candles to burn because they were free of phlogiston.¹

Priestley dined with Lavoisier in Paris and told him about his experiments. Lavoisier repeated them and quickly confirmed Priestley’s findings. He named the gas principe acidifiant and principe oxygine (Greek oxys “sharp or acidic” and genes “forming”).⁴ Oxygenation explained the changes that occurred in combustion, respiration, and calcination: “Stahl’s phlogiston is imaginary.”

Even earlier, in 1766, the aristocrat Henry Cavendish had isolated hydrogen, a gas that he called “inflammable air” because it burned readily in a closed vessel, yielding dew (i.e. water) on its glass walls. In June 1783, Lavoisier’s experiments showed that water consisted of pure air, called oxygène, and inflammable air, called hydrogène.

Lavoisier’s subsequent great distinction rested on his new system of chemistry published in the Traité élémentaire de Chimie in 1789 (the year of the storming of the Bastille), which became the foundation of modern chemistry. He defined the new Law of the Conservation of Mass and produced a Table of Simple Substances, the first table of all known elements.¹

Portrait of Antoine-Laurent Lavoisier and his Wife

Lavoisier commissioned Jacques-Louis David (1748–1825), the successful neoclassical artist, to paint a personal Portrait of Antoine-Laurent Lavoisier and his Wife, 1788. The huge portrait (260 x 195 cm) is in the Metropolitan Museum of Art in New York. David, the professor at the École des Beaux-Arts, shared with Lavoisier both intellectual and political sympathies; he was, however, an ally of Robespierre, and nicknamed “the Robespierre of the brush,” and a member of the notorious Jacobin Club. His life was a curious mixture of devotion to classical art and political intrigue in which he played no small part.

David portrays Lavoisier sitting at a table with an air pump, bell jar, and gasometer, displaying his prowess as a chemist. Marie-Anne stands beside him, in fashionable dress with one hand affectionately on his shoulder, not merely decorative but a clever collaborator who was engaged as his scientific partner. In a style of restraint and elegance, signs of wealth and aristocracy are omitted. David uses layered glazes to achieve a soft, luminous quality in the skin and garments. A subtle light emphasizes their delicate facial features.

However, recent X-ray analysis shows that there was an underlying original painting in which both wore sumptuous, luxuriant clothing; Marie-Anne with an ostentatiously flower-laden, plumed hat. There were ledgers and tax-related objects but no scientific instruments were shown. David had painted over them to conceal their politically provocative wealth, instead displaying their scientific virtues.

This reflected the emerging French Revolution of Republican rejection of the nobility and clergy, the Ancien Régime, and Lavoisier’s association with the widely hated Ferme Générale—the customs, excise, and tax collection for the King. The revolution started with the storming of the Bastille by a starving mob in July 1789, revolting against an outdated estate system of exorbitant wealth and privilege of the monarch and noblemen amidst widespread deprivation and despair. The revolution lasted six years. Unsurprisingly, the painting was excluded from the Salon of 1789 for fear it would incite republican violence. In the same year, David started to paint the Tennis Court Oath to commemorate and support the commoners of the Third Estate, but abandoned it for political reasons.

Lavoisier was a key figure of the feudal Ancien Régime’s nobility and intellectual elite. Despite his estimable scientific contributions, his association with the Ferme Générale, aristocracy, and royal institutions was denounced by Jean-Paul Marat, culminating in his arrest by the Republicans in the Reign of Terror. In May 1794, Lavoisier was tried and guillotined; during the trial, his scientific contributions were ignored. Marie-Anne was spared.

David supported the execution of King Louis XVI in January 1793. It is said he was a powerful member of the National Assembly who stood by and watched. David may appear a quisling. Indeed, some historians interpreted his silence at the guillotine as showing complicity; however, fear for his own life may have suppressed any display of sorrow or remorse. Many thousands of alleged enemies of the Republic were executed in the Reign of Terror under Maximilien Robespierre. Charlotte Corday famously murdered his willing, murderous accomplice Jean-Paul Marat in his bath.⁵ It is both telling and ironic that The Death of Marat, the man responsible for Lavoisier’s execution, was famously painted by Jacques-Louis David in 1793.

Robespierre was sent to the guillotine. David was twice imprisoned in 1794 and 1795, but after release continued painting in the classic Greek style. He painted the celebrated The Intervention of the Sabine Women (1799), which Napoleon admired. He became an ardent follower of Napoleon, a shift from the Jacobin left to the Bonapartist right. As an admirer and painter of historical heroes he painted an idealized, heroic view of Napoleon in five canvasses of Napoleon Crossing the Alps.

David was made a Chevalier de la Légion d’honneur in 1803, Commandant in 1815. After Napoleon’s final defeat at Trafalgar, David continued to paint in exile in Brussels where he died in December 1825.

References

1. American Chemical Society International Historic Chemical Landmarks. Antoine-Laurent Lavoisier: The Chemical Revolution. http://www.acs.org/content/acs/en/education/whatischemistry/landmarks/lavoisier.html
2. Lavoisier, A. Observations on the Air. Journal des Physiques, 3rd Series, 1775. pp. 116-123.
3. Priestley, J. Experiments and Observations on Different Kinds of Air. London: J. Johnson, 1774. pp. 42-56.
4. Smith, LH. The Discovery of Oxygen: A Scientific Biography of Joseph Priestley. New Haven: Yale UP, 1991.
5. Pearce JMS. Jean-Paul Marat, physician and revolutionary. Hektoen Int Spring 2021.