Joseph Louis Proust

French chemist

• Born: September 26, 1754; Angers, France
• Died: July 5, 1826; Angers, France

French chemist Joseph Louis Proust flourished during the late eighteenth and early nineteenth centuries. He spent more than twenty years teaching and researching at institutions in Spain, where he conducted numerous experiments with various metals that ultimately resulted in the development of a universal principle in analytical chemistry.

Primary field: Chemistry

Specialties: Analytical chemistry; organic chemistry; metallurgy

Early Life

Joseph Louis Proust was born in Angers, an ancient city on the Maine River in western France. He was the second son of Joseph Proust, an apothecary who owned a pharmacy, and his wife Rosalie Sartre Proust. Young Joseph became interested in science as a boy and learned the basics of chemistry and herbal remedies from his father. His older brother Joachim (born 1751) also profited from their father’s knowledge of chemical substances: In the 1790s he worked as a negotiator for local miners of saltpeter, which was used to make gunpowder, and he later had his own pharmacy in Angers. Joseph obtained his early education at the Oratorian Brothers School in Angers, and he supplemented his studies in the laboratory of his father’s pharmacy. As a teen, he helped to create a botanical garden in Angers.

Though his father hoped Joseph would remain in Angers and someday take over the family business, the young man had different ambitions. In 1774, he left for Paris, which was about 150 miles away, and took scientific classes at the University of Paris and also studied in the laboratory of chemist Hilaire Marin Rouelle (1718–1779), one of the discoverers of urea and a popular public demonstrator of chemical principles. Through Rouelle, Joseph met many leaders in the French scientific community, including chemist-biologist Antoine Lavoisier, physicist-balloonist Jean-François Pilâtre de Rozier, physicist-balloonist Jacques Charles, and chemist Claude Louis Berthollet.

In 1776, after passing a qualification test, Joseph was appointed chief apothecary at Paris’s Salpêtrière Hospital. Initially a gunpowder factory (“Salpêtrière” is derived from the French word for “saltpeter”), the facility was converted to a hospital in 1656 and expanded in 1684. During Joseph’s tenure, Salpêtrière—later a psychiatric center and currently a modern medical teaching center—had grown into the largest hospital in the world, with more than ten thousand patients, many of whom were poor, prostitutes, criminals, or mentally disabled. Joseph conducted his first research and published his first scientific papers while employed at Salpêtrière.

Life’s Work

In 1778, Proust left France to accept a post as professor of chemistry at a seminary in Vergara, near Bilbao in northern Spain. One of several facilities established under the auspices of the Basque Society of Friends of their Country, the seminary—part of a national effort to improve education—was the first in Spain geared toward research in chemistry and metallurgy.

Disappointed by the small number of students enrolled in his classes, Proust returned to Paris in 1780. He taught chemistry with his colleague de Rozier, and the two men conducted experiments in aerostatics, the study of stationary gases, as applied to hot-air balloons, a craze in France at the time. In 1783, de Rozier became the first person to take flight in a Montgolfier balloon. The following year, in an event witnessed by the kings of France and Sweden and thousands of spectators, Proust accompanied de Rozier in a hot-air balloon dubbed the Marie Antoinette. Lifting off from the Palace of Versailles, they rose to nearly ten thousand feet and floated for forty-five minutes before landing safely more than thirty miles away, setting ballooning records for altitude and distance. (De Rozier and a companion were later killed in 1785 when their hot-air balloon crashed while attempting to cross the English Channel, making them the first known fatalities in an air crash.)

On the recommendation of Antoine Lavoisier, King Carlos III of Spain hired Proust in 1786 as the first professor of chemistry and metallurgy at the Royal Artillery School, housed in a twelfth-century castle in the ancient city of Segovia. In addition to his teaching duties, Proust was responsible for researching the properties of platinum, a new metal first extracted in the mid-eighteenth century from mines in Spanish colonies that would later become Ecuador and Colombia. Proust taught until the mid-1790s at Segovia before moving on to teach chemistry and continue his metallurgic research at the University of Salamanca, also in Spain. In 1798, he married compatriot Ana Rosa de Chatelain D’Augigné, a member of an aristocratic French family who had taken refuge in Spain during the French Revolution; the couple produced no children.

In 1799, King Carlos IV (who had succeeded his father in 1788) appointed Proust to succeed another Frenchman, Pierre Chabaneau, as head of a modern, well-equipped laboratory in Madrid. Proust’s chief responsibility was to develop a commercial method of purifying platinum, which was then only being mined from the Spanish Empire’s colonial holdings. In addition to his metallurgical studies, Proust conducted considerable research into fruit sugars and investigated a wide variety of other subjects of scientific interest.

In 1806, Proust—worn out and possibly ill, perhaps because of his hazardous research—resigned from his position in Madrid. He and his wife left Spain and returned to France to settle in Craon. In 1808, Napoleon’s army captured Madrid after a four-day siege, and the emperor’s soldiers looted Proust’s former lab. Proust never returned to Spain.

In 1810, the French government commissioned Proust to set up a fruit sugar factory, but for most of the decade, despite formal recognition of his scientific accomplishments, he lived in poverty. His wife died in 1817. In 1820, following the death of his brother Joachim, Proust inherited his pharmacy in Angers. The same year, French King Louis XVIII granted Proust an annual pension, which Louis’s successor Charles X kept in effect until Proust died in 1826 at the age of seventy-one.

Impact

Joseph Louis Proust was well known and respected in Europe during his lifetime. He gained a reputation for the breadth of his scientific interests, for the accuracy of his measurements, for his analytical skills, and for his meticulously repeated experiments. Proust began a forty-year period of serious research while working at Salpêtrière Hospital in the late 1770s and published papers that were based on his studies of urea, phosphoric acid, and alum.

In 1780, to provide better lighting for reading and conducting experiments, Proust designed—but never patented—an improved oil lamp that burned whale oil or olive oil and produced a brighter light than a single candle. It featured a reservoir containing flammable fuel that was higher than the wick, so the oil’s own weight fed the flame. Two men in Proust’s circle of acquaintances—both involved in ballooning—copied and improved the lamp and made fortunes from Proust’s invention. Chemist Pierre Argand added a glass chimney and patented the Argand lamp in England in 1784; pharmacist Antoine Quinquet introduced the Quinquet lamp in France in the same year.

Much of Proust’s work in Spain involved the purification of platinum. To this end, he developed a practical and efficient method—still in use in metal refining—of using aqua regia (nitro-hydrochloric acid) to separate platinum from other metals and produce a pure, malleable platinum powder at the rate of between 14,000 and 18,000 troy ounces per year. In the process, Proust isolated (but never identified, thus is not credited as discoverer) several other noble metals, including osmium, palladium, rhodium, and iridium. In the course of his work, Proust developed hydrogen sulfide as a reagent. The poisonous gas, which may have adversely affected his health, became an important tool in analytical chemistry for causing reactions useful in analyzing mixtures and compounds.

Another important contribution was Proust’s 1799 discovery of grape sugar (later called glucose), which he demonstrated was as sweet as sugar derived from honey or cane. This finding was of commercial benefit because grapes were abundant throughout Europe and were cheaper to use in sugar extraction than cane, which was imported from the Caribbean.

Joseph Louis Proust published the results of his research often in Spanish and French scientific journals and wrote several full-length works based on his studies. He was finally recognized for his work late in life and in 1816, he was inducted into the Institut de France and three years later was elected a chevalier (knight) in the French Legion of Honor.

Bibliography

Aldersey-Williams, Hugh. Periodic Tales: A Cultural History of the Elements, from Arsenic to Zinc. New York: Ecco, 2011. Print. Discusses the discovery, characteristics, names, and other facts about the chemical elements, including platinum and the noble metals with which Joseph Louis Proust extensively experimented.

Inkster, Ian, and Angel Calvo, eds. History of Technology, Vol. 30. London: Continuum, 2011. Print. An anthology of essays covering the advance of technology in Spain from the late seventeenth century to the present; several chapters, particularly those on mining and sugar technologies and the chemical industry, relate to the work of Joseph Louis Proust during his time in Spain.

Partington, J. R. A Short History of Chemistry. New York: Dover, 1989. Print. Provides an explanation of the basic principles of physical and organic chemistry, which include an account of the development of Proust’s law, an important component in the formulation of atomic theory.

Schectman, Jonathan. Groundbreaking Scientific Experiments, Inventions and Discoveries of the Eighteenth Century. Westport, CT: Greenwood, 2003. Print. A collection of more than fifty essays detailing the most important advancements—including the work of Proust—during the eighteenth century.