Interesting, I did wonder if the different alloy after 1920 would have different electrical properties that might be measured. If I could find my multi meter I'd give it a try... Regarding the scrap value, I assumed that at 1.4 grams per coin it would be 20 3d's to an ounce, making each pre 1920 coin worth about £1 and post 1920 50% coins half that. Any comments appreciated. Regards Andrew