348 GENERAL SCIENCE 



applications already made of these advances in scientific knowledge, 

 suggest that much is yet to be learned about forms of radiant energy. 

 If objects reflected all the light incident upon them their colorings 

 would be wholly dependent upon the kind of light that came to them. 

 However, it is found that varied proportions of the different wave 

 lengths are absorbed into bodies upon which they fall according to the 

 material in the bodies. This phenomenon, known as selective absorp- 

 tion, results in color waves being reflected from a body that may be 

 entirely unlike those which fell upon it. Color then in some cases 

 actually does become a characteristic of bodies, indicating the presence 

 in them of certain kinds of matter. 



Exercises 



1. In the formation of rainbows where must the dispersion occur? Explain 

 how it is that the dispersed sunlight gets back to the observer from the 

 part of the sky where the bow is. 



2. Account for differences in color of the adjacent parts of petals of 

 flowers. 



3. Why are upper cloud masses of an advancing thunderstorm often silvery 



white in appearance, while the under surfaces of the same clouds may be 

 inky black? 



4. Distinguish between reflection, transmission, and absorption of light. 



Since ether waves may be transmitted through bodies, what must be true 

 of the existence of an ether medium within them? 



6. Why are heat and light said to be forms of energy? By what means are 

 both supposed to be sent on (propagated) through space? Distinguish 

 between sight and light. 



