What alchemists got right about chemistry

Another interesting question would be what alchemists got right about psychology and religion.

C.G. Jung was heavily influenced by some alchemists. Jung probably isn't a psychologist in any scientific way but I really don't know enough to judge his contribution.

Another interesting place where alchemy comes up is in Valis, Philip K. Dick's semi-autobiographical attempt at making sense of his purported visions. I think he writes about a continuity between christian gnostics and alchemists. I love this book but I haven't the slightest idea how I could find out if anything in there makes any sense.