\" \" The image of a long-dead man peers out from a daguerreotype plate (right) after the tarnish (left) is removed with synchrotron X-rays. What they found was that in some cases, even the images on severely tarnished daguerreotypes can be recovered. Because mercury is the major element that comprises the images, even though the surface of the daguerreotype is tarnished, the image particles remain intact. The XRF method is noninvasive and doesn't touch the fragile surface of the daguerreotype or alter it in any way. And it's a fly in the face of immortality for the 19th-century mercurial ghosts who lie latent on tarnished, silver-coated copper plates, waiting to be unforgotten.