[Illustration: Fig. 44.--The Cage Opened.]
I believe a few words in regard to spirit photography will not be amiss. These are made or produced in various ways: First, a glass with an image on it of the desired spirit form could be placed in the plate holder, in front of the sensitive plate, so that the image on the glass would act on the sensitive plate. The size and distinctness of the resulting spirit form would vary according to the distance between the two plates. Second, a figure clothed in white can be introduced for a moment behind the sitter and then be withdrawn before the sitting is over, leaving a shadowy image on the plate. Third, a microscopic picture of the spirit form can be inserted in the camera box alongside of the lens, and by a small magnifying lens its image can be thrown on the sensitive plate with that of the sitter. This is the trick used when the skeptic brings his own plate for the negative. Fourth, a glass with the spirit image can be placed behind the sensitive plate after the sitting is completed, and afterward, by a feeble light, the image can be impressed upon the plate with that of the sitter. Fifth, the silver nitrate bath could have a glass side, and the image impressed by a secret light while the glass plate apparently was being coated with the sensitive film. Sixth, the spirit form can be printed first on the negative and then the living sitter by a second printing, or the spirit can be printed on the paper and the sitter’s portrait printed over it. Seventh, a sensitive plate can be prepared by what is known as the dry process, the spirit form being impressed on it; and then, at a subsequent time, the portrait of the living sitter can be taken on this same plate, so that the two will develop together. Eighth, take a solution of sulphate of quinine and paint on the background screen a picture of any one; when it dries it is invisible to the naked eye. Still, when the picture is taken, the painted picture is very plainly seen on the glass negative. Ninth, small pictures are taken on thin, transparent celluloid and fastened against the front lens of the camera, and when the photograph is taken the picture appears. Of course, the above are by no means all the methods, but enough to illustrate the possibilities of obtaining two pictures on the same plate or at one sitting.