Spirit photography remained popular through the 1880s and on into the early 20th century with many famous proponents such as Arthur Conan Doyle
and William Crookes. William Stainton Moses, another spiritualist, claimed that spirit photography operated by means of a fluid substance called
ectoplasm, which allowed the spirits to take form. Notable mediums at the time wrote books, such as Photographing the Invisible (1911) by James
Coates, and Chronicles of the Photographs of Spiritual Beings and Phenomena Invisible to the Material Eye (1892) by Georgiana Houghton. Authur
Conan Doyle wrote The Case for Spirit Photography (1922).
Psychical researcher Harry Price was determined to revealed to the world that the photographs of a well known spirit photographer, William Hope were frauds. Price secretly marked Hope's photographic plates, also providing him with a packet of additional plates that had been secretly imprinted with the brand logo of the Imperial Dry Plate Co. Ltd. Any photo created with them would bear the logo. Unaware that Price had tampered with his supplies, Hope then attempted to produce a number of Spirit photographs. Although Hope produced several images of spirits, none of his materials contained the Imperial Dry Plate Co. Ltd logo, showing that the prepared plates had been exchanged for pre-prepared plates that Hope already had. Although he had been caught his staunch supporters, including Doyle, continued to support him.