Never thought about this before! On a related note, NEVER put a battery into a bonfire! This past summer while everyone was gathered around the fire-pit, my grandson had a dead AA battery in his hand and asked if he could throw it into the fire....I didn't think anything of it, and said "sure". Not long after it exploded, and came flying out of the fire. Luckily no one was hurt. Obviously I had no idea that would happen!! Learning new things every day!!