... quite by accident - same way I found out that it satisfied a craving for something but didn't know just what it was i craved. Just happened to pass a coal scuttle one day and instinctively took a piece of coal and started chewing it. I got a lovely sense of calm and well being from it and realized that coal (or something in it) was what was missing. Later, when I had heartburn, I noticed that it disappeared when I was eating coal and continued to use it for that purpose too. As children my brother and I both loved it when we were near a steam-roller because then we could get our hands on lumps of a hard, but chewy, black, material which we called pitch. I've no idea if that's the right name but it's the stuff they melt and mix with gravel for road resurfacing. It could be chewed for ages without losing its taste. Strange things we did as kids.