Where did stoichiometry originate?

Answer 1

It could be argued that the concept of stoichiometry was first formally stated by John Dalton, who stated as part of his Atomic Theory that:

• Atoms of different elements combine in simple whole-number ratios to form chemical compounds
• In chemical reactions, atoms are combined, separated, or rearranged

Taken together, these statements pretty much describe the concept of stoichiometry.