COMBINATION OF SPECIFIC LIGHT WITH OTHER BODIES. 77 



be, is exhibited, and it LS still the same let any of the other rays 

 be applied to it. Now this circumstance is a contradiction to 

 the combination of specific light with other bodies, and, the dis- 

 charge of the same identical light in a state unchanged; in such 

 case the light should be blue when exposed to blue rays. The 

 explanation given to this phenomenon by Sir H. Davy is, that 

 vibratory motion is communicated to the particles of the sub- 

 stance by the rays, in consequence of which, some of its own 

 particles are slowly sent off, or that the particles have been 

 formed into new aggregates, in consequence of the attraction of 

 the substance. 



The latter seems to accord better, but corresponding with the 

 present views submitted in these pages, it would appear pro- 

 bable that an impetus is only required ; nor is it material 

 whether it is given by the entire, or perfect light, in a body of 

 rays, or by any one ray distinct from the rest, the phosphorus 

 containing in an occult state, the matter of all the essential rays, 

 those deficient in the application are supplied by it, and the 

 light is given out a pale yellow in all cases. 



On the existence of a specific imponderable substance capable 

 of producing light, and supposed to be contained in oxygen 

 gas, and of a similar substance in inflammable bodies, it is 

 the opinion of Sir H. Davy that the facts are contradictory to 

 the hypothesis. He states that iron when heated to whiteness 

 burns with amazing brilliancy in oxygen gas, throwing off 

 sparks intensely luminous, but when heated to 600 Fahr. 

 it combines slowly with the oxygen without producing light ; 

 that the chemical changes are of the same nature in both cases, 

 and that the only difference is, in their rapidity and energy. 



It appears, however, only necessary to raise the heat of iron 

 to about 800 or 900 of Fahr., or a red heat, when it imme- 

 diately assumes a white heat in oxygen gas, and the production 

 of radiant matter proceeds with the most splendid combustion. 

 Now, from analogy, we should conclude that iron contains 

 hydrogen, carbon, and azote in its composition. 



