Theories

Law of Definite Proportions

Citation Formats

General Reference

Science Atlas. "Law of Definite Proportions." Accessed August 30, 2026. https://science.interactiveatlas.org/theories/law-of-definite-proportions.

APA Style

Science Atlas. (n.d.). Law of Definite Proportions. Retrieved August 30, 2026, from https://science.interactiveatlas.org/theories/law-of-definite-proportions

BibTeX

@misc{scienceatlas-law-of-definite-proportions,
  author = {Science Atlas},
  title = {Law of Definite Proportions},
  year = {2026},
  url = {https://science.interactiveatlas.org/theories/law-of-definite-proportions},
  note = {Accessed August 30, 2026}
}

The law of definite proportions, also called Proust's law or the law of constant composition, states that a given chemical compound contains its constituent elements in a fixed mass ratio regardless of its source or method of preparation.

Facts

Proposed Yearthe subject's own account

1797 1

Proposed Bythe subject's own account

Joseph Proust 1

Cross-Tradition Connections

Proposed By

Joseph Proust

Additional Source Law of Definite Proportions (Wikipedia)History section (edge: proposed-by, Proust)

Sources

1. Law of Definite Proportions (Wikipedia)

WikipediaLead section (entity-description)

Quote, Lead section (entity-description)

In chemistry, the law of definite proportions, sometimes called Proust's law or the law of constant composition, states that a given chemical compound contains its constituent elements in a fixed ratio (by mass) and does not depend on its source or method of preparation.

View the Source

1. Law of Definite Proportions (Wikipedia)

WikipediaLead section (proposed-year)

Quote, Lead section (proposed-year)