1. Joseph Louis Proust
By Hannah Concepcion

2. Personal Life
Joseph Louis Proust was a great chemist in the 1700s. He was born in Angers, France on September 26, 1754.
He worked as a pharmacist in the earlier years of his life. He worked at a hospital called the Salpêtrière.
In 1778, He went to Spain to work as a Chemistry professor.
On the 30th of June in 1798, He married a French woman named Anne Rose Chêtelain Daubigné.

3. The Law of Definite Proportion
Proust's discovery was The Law of Definite Proportions or The Law of Constant Composition. His law asserts that the ratio of atoms by mass in a molecule is always the same.
He used hydrogen sulfide as a reagent. A reagent is “a substance that is used to test for the presence of another substance by causing a chemical reaction with it” So, he used it to find the elements that made up a compound. He wrote papers based on what he discovered; “consistently giving the results of his analyses in terms of percentage weight”

4. Associations with the Scientific Community
Joseph Proust was associated with John Dalton. Dalton used Proust's idea as a basis of his law in the Atomic theory.
There were scientists who had a similar viewpoint as Proust. They were Robert Dossie, G. F. Venel, L. B. Guyton de Morveau, and Thomas Thompson. These men, even if he didn’t directly interact with most, shared the same mindset as Proust.

5. Disagreements with the Scientific Community
There was major controversy between Proust and another scientist named Berthollet. It wasn’t until John Dalton came up with his law that the people started to realize that Proust was correct. Dalton made sure that Proust was recognized for his law.
Claude Berthollet

6. Works Cited
"Claude Louis Berthollet." Wikipedia. Wikimedia Foundation, n.d. Web. 22 Jan
"Joseph Louis Proust - HowStuffWorks." HowStuffWorks. N.p., 20 July Web. 22 Jan
"Joseph Proust." Wikipedia. Wikimedia Foundation, n.d. Web. 22 Jan
"Law of Definite Proportions." Wikipedia. Wikimedia Foundation, n.d. Web. 22 Jan
"Proust, Joseph Louis." Complete Dictionary of Scientific Biography. Vol. 11. Detroit: Charles Scribner's Sons, Gale Virtual Reference Library. Web. 13 Jan
"Reagent." Merriam-Webster. Merriam-Webster, n.d. Web. 22 Jan

7. The End