Worked on the RR for half a century, that's exactly what they are. Sometimes I'd put a 50 cent piece on rail first, stacked with a quarter, then nickel, penny, and dime. Then push them snug up to the engine wheel and a rock in front of them so they wouldn't tumble, then slowly roll over them about a foot, flip them over, back up about a foot. Never did get the results I wanted, just tossed them into the brush. It was fun tossing them to someone else for them to look at, because the temperature of the glob was in the 170 range.