The Optical Magic Lantern Journal (February 1896)

The Optical Magic Lantern Journal and Photographic Enlarger. 19 People Photographed as Skeletons. A Srartuine Discovery IN CoNNECTION WITH PHOTOGRAPHY. WHEN the subject of psychic photography had been publically commented upon, certain wiseacres who admitted that they had had no experience whatever upon the subject, did not hesitate to give their decided opinion that it was fraud of some kind or other, and when certain people who had made a special study of the subject under the strictest of conditions gave their views as to obtaining certain images upon plates under test conditions, the aforesaid wiseacres solemnly shook their heads and said ‘“‘ Some trick.” Upon this subject, however, we may at a future time have a good deal to say. It might be interesting to hear what the same ‘‘ wise men” who have had no experience, but who can offer a definite opinion, have to say as to the latest discovery in connection with photography. It appears that a very important. scientific re-discovery has been made by Professor Routgen, of Wurzberg University. Professor Routgen uses the light emitted from one of Crookes’ vacuum tubes, through which an electric current is passed, which acts upon an ordinary photographic plate. The invisible light rays show that to them wood and various other substances are transparent. In the course of an interview on this subject in our Editorial sanctum, a few days ago, with Mr. G. Lindsay Johnson, F.R.C.S., he stated that the essence of the whole thing depended upon the action of the waves of light at the ultra-violet end of the spectrum beyond the visual rays. These waves are of exceedingly short length, and move with great rapidity, and | though invisible to the eye, are not so to a photographic plate. To get light waves short enough, it is necessary to have an electrical discharge of great potentiality, and to obtain this a current of at least 100 volts is passed. through an induction coil, the secondary wires of which are connected with ten or more Leyden jars which are charged with the current; from these, wires lead to another induction coil, connected with a Crooke’s radiant tube. This is a flask-shaped bulb (exhausted), into which two electrodes are passed, terminating in flat metal plates inside the flask, and it is between these two plates the discharge passes which illu minates the interior. The object of the induction coils and Leyden jars is to increase the potentiality of the current to the highest degree. | The light inside the tube is visible to the eye, but these visible rays do not effect the photographic plate through a barrier of wood. The extreme ultra-violet rays invisible to the eye strongly affect photographic plates, and will penetrate wood, vulcanite, aluminium, and other substances opaque to the eye in proportion to the degree of potentiality of the electric current. * If a sensitive dry plate be placed in an ordinary double back or slide, with the sensitised surface directed towards the operator, and he places his hand in contact at the outside of the slide, and the Crooke’s tube be placed afew inches behind the hand, the light waves will penetrate the flesh of the hand and every part of the slide, the bones only forming an obstruction to the light. The bones do not form a complete but a partial obstruction, because they are more or less porous. If the plate be developed in a dark room with pyro and alkali, the outlines of the hand will appear faintly, and the bones will appear well defined with the utmost nicety and precision. The semi-bony prominences into which the ligaments are inserted are as clearly seen as a dried preparation of the bone, and even the marrow cavities of the bones are produced with perfect definition. The rationale, Mr. Johnson believes, of this peculiar action of light is as follows :—These light waves, of which all light is composed, and which vary in length according to the part of the spectrum formed, are so short at the extreme ultra-violet end, that they are able to penetrate between the molecules of all organic bodies which, as is known, are mainly composed of carbon, oxygen, hydrogen, and nitrogen, but are arrested by all metalloids and metals of greater density. Bone is largely composed of phosphate of lime, and it is the lime or calcium of the bones which forms the opposition to these short light waves, but as these bones are not entirely solid or homogeneous, certain portions of the waves pass right through, so that the bones in a print from a negative do not appear as silhouettes on a white ground, but resemble a thin transparent object when viewed through the microscope, and illuminated by the mirror from below, and in consequence they have a roundness which greatly adds to their realistic appearance. In fact, portions of the bone seem in the print, so to speak, to be projected throughout their entire thickness.