54 FRAGMENTS OF SCIENCE 



upon both the carbon and the metal. Results similar to 

 those obtained with the electric light have also been 

 obtained with the invisible rays of the lime -light and of 

 the sun. 



Before a Cambridge audience it is hardly necessary 

 to refer to the excellent researches of Professor Stokes at 

 the opposite end of the spectrum. The above results con- 

 stitute a kind of complement to his discoveries. Professor 

 Stokes named the phenomena which he has discovered 

 and investigated Fluorescence; for the new phenomena 

 here described I have proposed the term Calorescence. 

 He, by the interposition of a proper medium, so lowered 

 the refrangibility of the ultra-violet rays of the spectrum 

 as to render them visible. Here, by the interposition of 

 the platinum foil, the refrangibility of the ultra-red rays 

 is so exalted as to render them visible. Looking through 

 a prism at the incandescent image of the carbon points, 

 the light of the image is decomposed, and a complete 

 spectrum is obtained. The invisible rays of the electric 

 light, remolded by the atoms of the platinum, shine thus 

 visibly forth; ultra-red rays being converted into red, 

 orange, yellow, green, blue, indigo, violet, and ultra- 

 violet ones. Could we, moreover, raise the original 

 source of rays to a sufficiently high temperature, we might 

 not only obtain from the dark rays of such a source a 

 single incandescent image, but from the dark rays of this 

 image we might obtain a second one, from the dark rays 

 of the second a third, and so on a series of complete 

 images and spectra being thus extracted from the invis- 

 ible emission of the primitive source. 1 



1 On investigating the calorescence produced by rays transmitted through 

 glasses of variouL colors, it was found that in the case of certain specimens of 



