The effect of sealing a blank piece of “sensitized” paper into an envelope and having the photographic image of a selected card appear on it is described under the title of “Spirit Photography” in Ellis Stanyon's New Card Tricks (Fourth Series), No. 21 in his Serial Lessons in Conjuring, 1910, p. 26. The method involves a card force, a double-compartment envelope and a final envelope switch to eliminate the telltale evidence. This trick enjoyed some popularity for a time after its publication. Eventually it was retired in preference for a variation in which the envelope was replaced by a pair of coins, between which a small rectangle of paper developed into a miniature image of a chosen card.
Also see Photographic Coins.