spirit photography
the attempt, popular in the late 19th century, to render visible the spirits of deceased individuals by photography. In particular, it was claimed that spirits often left faint imprints on photographs of their loved ones. The first alleged spirit photograph was produced in 1862 by the U.S. engraver William H. Mumler, who was subsequently tried (inconclusively) for fraud. Most of the supposed spirit images produced at this time seem to have been created using a simple process of double exposure or specially prepared plates.