I know that is a lime, but I figure it would work as well, and it was a chance to show off my T.M. Hunt Leaveit Cleaver. Apparently, this firestarting “hack” is the old potato-clock on steroids. But using a lemon as a firestarter seems to work. I think there was a point in High School where I could have explained the precise physics behind this “hack”, but I probably killed that brain cell in College.
Basically, there is a reaction between the copper, zinc, and acid from the lemon which turns said fruit into a simple battery. Just enough current to ignite the tinder.
I don’t know how often I will be stuck in the woods with copper clips, zinc nails, and a lemon, but if I am I will know what to do.
I have tried the gum-wrapper and AA battery trick. It actually works.