I can understand the unknown.
Although I didnt have the nails, my parents will told to use ginseng and dad would take me to Tauranga where we would go to a place and be connected to a battery. I hated that as it scared the hell out of me. I think it was called electrophe therapy.
The idea was that the electricity from the battery caused a current that supposed to push out the iron. I was only 6 and cant quite remember why. Just the room with 6 to 9 people around this battery with lines connected to our wrists.
I am much happier with technology now but I appreciate what my parents were trying to do even if I hated it.
And yes it still is not well known today