SECT. XXV. VARIOUS PHENOMENA EXPLAINED. 237 



ferent on its different parts, and therefore images are 

 formed. Although this explains various phenomena, it 

 does not apply to those already described, as Mr. Hunt 

 had taken the precaution to divest the substances he 

 used of every trace of organic matter. 



It is difficult to see to what cause Mr. Hunt's experi- 

 ments on the reciprocal action of bodies in total darkness 

 can be attributed, unless perhaps to a constant radiation 

 of some peculiar principle from their surfaces, which 

 really seems to exist. 



The impression of an engraving was made by laying 

 it face downwards on a silver plate iodized, and placing 

 an amalgamated copper plate upon it : it was left hi 

 darkness fifteen hours, when an impression of the en- 

 graving had been made on the amalgamated plate, 

 through the paper. 



As the same may be obtained on plates of iron, zinc, 

 or lead, it is evident that this result is not the effect of 

 chemical rays. 



An iodized silver plate was placed in darkness with a 

 coil of string laid on it, and with a polished silver plate 

 suspended one eighth of an inch above it ; after four 

 hours they were exposed to the vapors of mercury, 

 which became uniformly deposited on the iodized plate, 

 but on the silver one there Was a sharp image of the 

 string, so that this image was formed in the dark, and 

 even without contact. Coins or other objects leave 

 their impressions in the same manner with perfect 

 sharpness and accuracy, when brought out by vapor 

 without contact, in darkness, and on simple metals. 



Heat, electricity, and the evaporation of unctuous 

 matter, may account for some of these phenomena, but 

 Qthers clearly point at some unknown influence exerted 

 between the surfaces of solid bodies, and affecting their 

 molecular structure so as to determine the precipitation 

 of vapors, an influence which in all probability will ulti- 

 mately be found to be either the parathermic rays of 

 Sir John Herschel, or ultimately connected with them. 



