270 SCIENCE OF COMMON THINGS. 



Color and its cause. Why are some bodies red and others white, black, &c. ? 



In the dark, bodies have no color, and in the light 

 their colors may be altered by subjecting to certain mo- 

 difications the light by which they are rendered visible. 

 Thus a blue piece of cloth in a red light will appear red. 



17*50 Why is it that we find it difficult to distinguish colors ~by candle- 

 light? 



Because we have modified the light upon which the 

 full effect of the color depends. 



17*51 What then is the true definition of color ? 



The color of a substance is the effect of light on a 

 surface adapted to reflect its particular color. 



17*53 Why do some things reflect one color, and some another f 



Because the surface of things is so differently consti- 

 tuted, both physically and chemically. 



17*53 Why is a rose red ? 



Because the surface of a rose absorbs the Hue and 

 yellow rays of light, and reflects only the red. 



17*54 Why are some things black f 



Because they absorb all the rays of light, and reflect 

 none. 



1755 Is black a color f 



It is not / it is the absence of color. 



17*56 Why are some things white f 



Because they absorb none of the rays of light, but 

 reflect them all. 



17*57* Why are clouds, snow, sugar, and salt white f 



Because they reflect 'back unchanged the white light 

 which strikes upon them. 



17*58 Why are not the crystals of frost and snow transparent like icef 



The crystals of frost and snow are not solid, but they 

 contain air ; hence their brilliant whiteness : for the air 

 preventing the ready transmission of light through the 

 crystals, the rays are copiously reflected, from the mass 

 of crystals. 



17*59 Why is the darkness of night diminished by the presence, of snow f 



Because the snow reflects, instead of absorbing, like 



