236 Intelligence and Miscellaneous Articles. 



and in close contact with it, a plate of iron entirely covering the 

 interior of the frame. The plate thus masked by the metal plate 

 is exposed to the light of a petroleum-lamp for about three hours. 

 An energetic and very prolonged development of the sensitive 

 plate carried on to almost complete blackness will give a very pale 

 image of the photograph, but one which is very marked by trans- 

 mitted light. 



By a slight modification of the preceding experiment, images 

 may be obtained almost as sharp as if no obstacle had been inter- 

 posed between the light and the sensitive plate. Without altering 

 anything in the preceding arrangement, let a plate of lead of any 

 thickness be placed behind the sensitive plate, and its edges bent 

 over until they slightly cover the edges of the iron plate. The 

 sensitive plate is thus enclosed in a sort of metal box, the front 

 part of which consists of an iron plate, the back and the sides being 

 formed of lead. After three hours of exposure to petroleum light, 

 w r e obtain as before a vigorous image after development. 



"What part does the lead plate play in this second experiment. 

 Provisionally I imagine that the contact of two different metals 

 gives rise to very feeble thermoelectric currents, the action of 

 which adds itself to that of the luminous radiations which have 

 passed through the iron plate. 



I hope to be able soon to determine the part of the various 

 factors which come into play in producing the preceding results. 

 I hope thus to determine the properties of light after its passage 

 through opaque bodies. The action which might be exerted on the 

 cliches by heat, or that of light stored up, have been entirely 

 eliminated by my experiments. 



The action of the sun's light gives the same result as that of 

 petroleum, and does not appear to be much more active. 



Cardboard and metals, particularly iron and copper, are easily 

 traversed by light. This passage of light through the bodies is 

 only a question of time. 



If the experiments are repeated in the photographic camera, 

 that is to say, if a metal plate is placed in front of a sensitive 

 plate, and therefore between the latter and the object to be photo- 

 graphed, on exposure for two hours to the sunlight, an intense 

 blackening is obtained on development, proving the passage of light 

 through the opaque plate, but images are only exceptionally ob- 

 tained and in conditions which I have not yet been able to determine. 



As they are invisible to the eye, I give the name of blade light 

 to those radiations of unknown origin which pass in this way 

 through opaque bodies. Considering the divergences between the 

 numbers of vibrations producing various kinds of energy, such as 

 electricity and light, we may imagine that there are intermediate 

 numbers corresponding to natural forces still unknown. The latter 

 must be connected by imperceptible transitions to the forces we 

 know. The possible forms of energy, although we know very little 

 about them at present, must be infinite in number. Blade light 

 perhaps represents one of the forces of which we are ignorant. — 

 Comptes Rendus, Jan. 27, 1896. 



