It took Antoine Lavoisier, the French chemist who had earlier identified
oxygen as an element, to disprove the phlogiston theory, proving instead that what plants were in fact doing was emitting oxygen into the air.
However, there's some debate amongst the scientific community about whether Davy was truly the first person to make this leap, because 30 years prior in 1778, the French chemist,
Antoine Lavoisier, posited in his landmark book“Elements of Chemistry” that what he called“argilla”(aluminium oxide)
could exist as a solid metal in theory, but that the technology of the day couldn't separate the strongly bound oxygen atoms.