When did john Dalton start working with atoms?

John Dalton began his work on atoms in the early 1800s, with his significant contributions starting around 1803. He is best known for developing the atomic theory, which proposed that matter is composed of indivisible atoms and that each element has its own unique type of atom. Dalton published his findings in a book titled "A New System of Chemical Philosophy" in 1808, which laid the foundation for modern chemistry.