John; Are you talking about specific gravity tests when you referred to "displacement"? Haven't done that, but it's a good idea. Hell, I could probably discover many more new varieties to sell. Instead of catalog numbers, I could assign specific gravity values to each variety of the same chip? Holy cow! A whole new book to publish!!!! I'll get to work on it immediately ... that's after I return from the NJ Token & Medal Show that begins today in Somerset. <g>