Leucippus and Democritus where the first ones proposing that matter was composed by smaller and undestructible particles. They stated that matter was composed of small, indivisible particles called atoms. When modern science started to emerge, by XIX century, with the introduction of the scientific method, the british chemist John Dalton began to look for evidence supporting the observations of Leucippus and Democritus. The three most important laws which led to the development and aceptance of the Atomic Theory were the law of conservation of mass, the law of definite proportions, and the law of multiple proportions. He used this laws to explain the Atomic Theory.
