Atomic Theory
a theory, first System of Chemical Philosophy," pub- System of Chemical Philosophy," published in 1807. He stated that the atoms of each element were incapable of being drogen as 1; that the composition of a subdivided, and each had a definite reldrogen as 1; that hat the composition of a definite chemical compound is constant; that if two elements, A and B, are caeral proportions, the quantities of B, which unite with a given quantity of A, eral proportions, the quantities of B, usually bear a simple relation to one another. Dalton supposed that one element replaced another atom for atom, another. Dalton supposed that one elebut it has since been found that one atom of an element can replace one or more atoms of another element, according to their respective atomicities.