Joseph-Louis Proust

Table of Contents

References & Edit History Quick Facts & Related Topics

Images

Joseph-Louis Proust, medallion by Pierre-Jean David

Read Next

Chemical equations Chemical reactions chemistry

How Do You Balance a Chemical Equation?

Illustration of molecules. (molecular, chemistry, science)

Why Is a Group of Molecules Called a Mole?

Battle of Fleurus (June 16, 1794), the most significant battle in the First Coalition phase of the French Revolutionary Wars; by Jean-Baptiste Mauzaisse, 19th century.

What Led to France’s Reign of Terror?

Above the clouds 130 nautical miles below, astronaut Mark C. Lee floats freely without tethers as he tests the new Simplified Aid for Extravehicular Activity (EVA) Spacewalk Rescue (SAFER) system, Sept. 16, 1994. Space Shuttle Discovery, STS-64

Gravity: From Apples to the Universe

Discover

Aphrodite. Greek mythology. Sculpture. Aphrodite is the Greek goddess of love and beauty.

12 Greek Gods and Goddesses

Two chicks near an egg with a white background (poultry, chick, chickens, birds).

What Do Eggs Have to Do with Easter?

Pluto. The Changing Faces of Pluto. Most detailed view to date of the entire surface of the dwarf planet Pluto, as constructed from multiple NASA Hubble Space Telescope photographs taken from 2002 to 2003.

10 Important Dates in Pluto History

Artist interpretation of a Space meteoroid impact. Meteor impact. Asteroid, End of the world, danger, destruction, dinosaur extinct, Judgement Day, Planet Earth, Doomsday Predictions, comet

10 Failed Doomsday Predictions

Mona Lisa, oil on wood panel by Leonardo da Vinci, c. 1503-06; in the Louvre, Paris, France. 77 x 53 cm.

Why Is the Mona Lisa So Famous?

Periodical Cicada, Adult, Magicicada spp. Requires 17 years to complete development. Nymph splits its skin, and transforms into an adult. Feeds on sap of tree roots. Northern Illinois Brood. This brood is the largest emergence of cicadas anywhere

Why Do Some Cicadas Appear Only Every 17 Years?

earthquake. Heavily damaged school in the town of Yingxiu after a major earthquake struck China's Sichuan Province on May 12, 2008.

The 6 Deadliest Earthquakes Since 1950

Science & Tech

Joseph-Louis Proust

French chemist

Written by Seymour H. Mauskopf

Fact-checked by The Editors of Encyclopaedia Britannica

Last Updated: Apr 3, 2024 • Article History

Joseph-Louis Proust

See all media

Category: Science & Tech

Also known as:: Luis Proust

Born:: Sept. 26, 1754, Angers, France

Died:: July 5, 1826, Angers (aged 71)

Subjects Of Study:: law of definite proportions; quantitative chemical analysis

See all related content →

Joseph-Louis Proust (born Sept. 26, 1754, Angers, France—died July 5, 1826, Angers) was a French chemist who proved that the relative quantities of any given pure chemical compound’s constituent elements remain invariant, regardless of the compound’s source. This is known as Proust’s law, or the law of definite proportions (1793), and it is the fundamental principle of analytical chemistry. Proust also carried out important applied research in metallurgy, explosives, and nutritional chemistry. The son of an apothecary, Proust prepared for the same occupation, first with his father in Angers and then in Paris, where he also studied chemistry with Hilaire-Martin ...(100 of 985 words)

Access the full article

Help support true facts by becoming a member.