[lisper]

Almost certainly. Joseph Priestly, the discoverer of oxygen, was a confirmed phlogistonist. He even called oxygen "de-phlogisticated air". The reason oxygen theory wasn't developed sooner was technological limitations, not intellectual ones: scientists simply didn't have any way of preparing pure oxygen to experiment on before Priestly.

(FYI, I just happen to know all this because I'm in the middle of preparing a series of lectures on the history of science, and I just finished the segment on the atomic theory. It's a really fascinating story.)