4h 31min, feb 15, 1803 y - Dalton’s Atomic Theory: all matter is made of atoms that are indivisible and indestructible, all atoms of a given element are identical in mass and property, compounds are formed by the combination of two or more atoms of different kinds, and a chemical reaction is a rearrangement of atoms.
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4h 31min, feb 15, 1803 y
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~ 222 years ago