There are several other reasons why all the supernatural happenings of the 1800s (spontaneous human combustion in particular) tapered off.
People stopped wallpapering their homes with stuff that exuded mild hallucinogenics.
People got a lot better about realizing black mold existed, black mold probably shouldn't exist in their house, and preventing black mold from existing in their house.
People stopped lighting their homes with gas flames, which meant they no longer had sprawling conduits of leaky gas tubing throughout every room of their house that tended to outgas even when not lit.
People stopped (and I am being very serious, this is just what (some?) people did) filling washing tubs full of gasoline and using the gasoline to scrub out persistent stains from their clothes they'd then put on and wear while smoking cigarettes by the giant open hearth that provided most of the heat of their parlor room.
(Honestly, between ghost photography, "Sherlock Holmes and The Case of the Dancing Faeries", and inadvertent double-exposures, it took a few years before cameras started reducing the amount of strange happenings instead of increasing them.)