 This recording is before and after using iron and reacting it with copper sulfate solution. So there's the copper sulfate solution. There's the iron. I see a clean nail. Okay, so before, this is what you do. This is what it looks like. Okay, so you just have a nail and a blue solution. Okay, like that. And now, this is after a day. You see the difference in solution. The solution is no longer green or blue. It's brown and the nail. It's not very easily seen, but it's got copper all over it now.