76 FRAGMENTS OF SCIENCE 



added to show that the bright and the dark rays of a solid 

 body, raised gradually to incandescence, are strengthened 

 together; intense dark heat being an invariable accompani- 

 ment of intense white heat. A sun could not be formed, 

 or a meteorite rendered luminous, on any other condition. 

 The light-giving rays constituting only a small fraction of 

 the total radiation, their unspeakable importance to us is 

 due to the fact that their periods are attuned to the special 

 requirements of the eye. 



Among the vapors of volatile liquids vast differences 

 were also found to exist, as regards their powers of ab- 

 sorption. We followed various molecules from a state of 

 liquid to a state of gas, and found, in both states of aggre- 

 gation, the power of the individual molecules equally as- 

 serted. The position of a vapor as an absorber of radiant 

 heat was shown to be determined by that of the liquid 

 from which it is derived. Eeversing our conceptions, and 

 regarding the molecules of gases and vapors not as the re- 

 cipients, but as the originators of wave-motion; not as ab- 

 sorbers, but as radiators; it was proved that the powers 

 of absorption and radiation went hand in hand, the self 

 same chemical act which rendered a body competent to in- 

 tercept the waves of ether rendering it competent, in the 

 same degree, to generate them. Perfumes were next sub- 

 jected to examination, and, notwithstanding their extraor- 

 dinary tenuity, they were found vastly superior, in point 

 of absorptive power, to the body of the air in which they 

 were diffused. We were led thus slowly up to the exami- 

 nation of the most widely diffused and most important of 

 all vapors the aqueous vapor of our atmosphere, and we 

 found in it a potent absorber of the purely calorific rays. 

 The power of this substance to influence climate, and its 



