54 FRAGMENTS OF SCIENCE. 



various degrees of darkness and incandescence, with 

 the following results : 



Appearance Energy of 



of spiral obscure rays 



Dark ."..'.'. . . 1 



Dark . . . . . . 6 



Faint red 10 



Dull red 13 



Eed 18 



Full red 27 



Orange 60 



Yellow 93 



White 122 



Here, as in the former case, the dark and bright 

 radiations reached their maximum together; as the 

 one augmented, the other augmented, until at last the 

 energy of the obscure rays of the particular refrangi- 

 bility here chosen, became 122 times what it was at 

 first. To reach a white heat the wire has to pass 

 through all the stages of invisible radiation, but in its 

 most brilliant condition it embraces, in an intensified 

 form, the rays of all those stages. 



And thus it is with all other kinds of matter, as far 

 as they have hitherto been examined. Coke, whether 

 brought to a white heat by the electric current, or by 

 the oxyhydrogen jet, pours out invisible rays with 

 augmented energy, as its light is increased. The same 

 is true of lime, bricks, and other substances. It is 

 true of all metals which are capable of being heated to 

 incandescence. It also holds good for phosphorus 

 burning in oxygen. Every gush of dazzling light has 

 associated with it a gush of invisible radiant heat, 

 which far transcends the light in energy. This con- 

 dition of things applies to all bodies capable of being 

 raised to a white heat, either in the solid or the molten 

 condition. It would doubtless also apply to the 



