36 FRAGMENTS OF SCIENCE. 



refer to the excellent researches of Professor Stokes at the 

 opposite end of the spectrum. The above results consti- 

 tute 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 re- 

 frangibility 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, re- 

 molded 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 invisible emission of the 

 primitive source.* 



*0n investigating the calorescence produced by rays transmitted 

 through glasses of various colors, it was found that in the case of 

 certain specimens of blue glass, the platinum foil glowed with a. 

 pink or purplisJi light. The effect was not subjective, and consider- 

 ations of obvious interest are suggested by it. Different kinds of 

 black glass differ notably as to their power of transmitting radiant 

 heat. When thin, some descriptions tint the sun with a greenish 

 hue: others make it appear a glowing red without any trace of green. 

 The latter are far more diathermic than the former. In fact, carbon 

 when perfectly dissolved and incorporated with a good white glass, 

 is highly transparent to the calorific rays, and by employing it as an 

 absorbent the phenomena of "calorescence" may be obtained, 

 though in a less striking form than with the iodine. The black 

 glass chosen for thermometers, and intended to absorb completely 

 the solar heat, may entirely fail in this object, if the glass in which 

 the carbon is incorporated be colorless. To render the bulb of a 

 thermometer a perfect absorbent, the glass ought in the first instance 

 to be green. Soon after the discovery of fluorescence the late Dr. 

 William Allen Miller pointed to the lime-light as an illustration of 

 exalted refrangibility. Direct experiments have since entirely con- 

 firmed the view expressed at page 210 of his work on " Chemistry," 

 published in 1855. 



