Revolutionary Instruments: Lavoisier's Tools as Objets d'Art

When the flame was finally extinguished by the buildup of carbon dioxide in the combustion chamber, Lavoisier closed the stopcock on the oxygen storage tank. Lavoisier had measured the initial weight of the lamp and spirit of wine, as well as the volume of oxygen in the storage tank and the volume of atmospheric air in the combustion vessel. He weighed the water present on the surface of the mercury by withdrawing it with a curved pipette, and after the combustion chamber was dismantled he again weighed the lamp. Before dismantling, Lavoisier measured the volumes of the gases in the system before and after injecting a potassium hydroxide solution into the chamber through the mercury to absorb out the carbon dioxide and by measuring the remaining gas volume, correcting for standard temperature and pressure. The volume of the initial atmospheric air was subtracted, and the gas volumes were converted to weights. The weights of the reactants, alcohol and oxygen, could then be compared with the weights of the products, carbon dioxide and water, to balance the chemical equation.

This and similar procedures with other plant materials led Lavoisier to conclude that “the true constituent elements of vegetables are hydrogen, oxygen, and charcoal [carbon]: These are common to all vegetables, and no vegetable can exist without them.” The door to organic chemistry had been opened. Lavoisier’s experiments showed that the combustion of organic substances resembled animal respiration, consuming oxygen and producing water and carbon dioxide. This bolstered his long-held theory that animal respiration was a form of slow combustion. He would later show that a human being consumes oxygen at a rate proportional to the amount of physical work being done, opening the door to physiological chemistry.

From Portraiture to Politics

At the time the portrait was painted the Chemical Revolution had been firmly established. Now, thanks largely to Lavoisier, balanced chemical equations could be written; heat could be quantified; air and water (considered primordial elements since antiquity) could be broken down into their components; and, as chemical compounds were given compound names, chemistry could be discussed with a new and reasonable nomenclature. Respiration, that mysterious pneuma of the ancients, had become a chemical reaction akin to the burning of an alcohol lamp.

Lavoisier’s instruments are masterfully painted by David, and their realism is astonishing. But as the paint dried, the tools of the Chemical Revolution went back onto laboratory shelves. Lavoisier supervised the government’s gunpowder manufacture and collaborated in collecting taxes for Louis XVI. David, a radical revolutionary, continued his support of the National Convention. The two men went their very separate ways into the political revolution, David as its champion and Lavoisier as its victim.

It would remain for Mme. Lavoisier, the real centerpiece of David’s painting, to promote the contributions that she and her husband had made. After her husband’s death she retrieved the proofs of his unfinished Mémoires de chimie and managed to publish these classic papers, which contained his final interpretations of his work, in 1805. She continued to promote her husband’s discoveries and to be an important figure in the scientific and intellectual life of Paris. But there must have been moments when she longed for those days spent in the laboratory working with her husband, surrounded by the beautiful objets d’art of Nicolas Fortin.

David belonged to a political revolution —Lavoisier to a scientific one. For a brief historical moment these revolutionaries combined their genius to create a work that beautifully captures the brilliance of the social, political, and intellectual upheaval that whirled around them.

For Further Reading

Aykroyd, Wallace R. Three Philosophers. London: William Heinemann, 1935.

Donovan, Arthur. Antoine Lavoisier: Science, Administration, and Revolution. Cambridge: Cambridge University Press, 1996.

Guerlac, Henry. Antoine-Laurent Lavoisier, Chemist and Revolutionary. New York: Charles Scribner’s Sons, 1975.

Holmes, Frederic L. Lavoisier and the Chemistry of Life. Madison: University of Wisconsin Press, 1985.

Lavoisier, Antoine L. Elements of Chemistry. R. Kerr, trans. Edinburgh: Creech, 1790. A facsimile. New York: Dover Publications, 1984.