HOW AND WHY COLORS CHANGE 137 



reach the eye, and there is an absence of any color sensation. 

 Coal and tar and soot are good illustrations of objects which 

 absorb all the light which falls upon them. 



131. How and Why Colors Change. Matching Colors. 

 Most women prefer to shop in the morning and early after- 

 noon when the sunlight illuminates shops and factories, and 

 when gas and electricity do not throw their spell over colors. 

 Practically all people know that ribbons and ties, trimmings 

 and dresses, frequently look different at night from what they 

 do in the daytime. It is not safe to match colors by artificial 

 light ; cloth which looks red by night may be almost purple 

 by day. Indeed, the color of an object depends upon the 

 color of the light which falls upon it. Strange sights are 

 seen on the Fourth of July when variously colored fireworks 

 are blazing. The child with a white blouse appears first red, 

 then blue, then green, according as his powders burn red, blue, 

 or green. The face of the child changes from its normal 

 healthy hue to a brilliant red and then to ghastly shades. 



Suppose, for example, that a white hat is held at the red 

 end of the spectrum or in any red light. The characteristics 

 of white objects is their ability to reflect all the vario.us rays 

 that fall upon them. Here, however, the only light which 

 falls upon the white hat is red light, hence the only light 

 which the hat has to reflect is red light and the hat conse- 

 quently appears red. Similarly, if a white hat is placed in a 

 blue light, it will reflect all the light which falls upon it, namely, 

 blue light, and will appear blue. If a red hat is held in a red 

 light, it is seen in its proper color. If a red hat is held in a blue 

 light, it appears black ; it cannot reflect any of the blue light 

 because that is all absorbed and there is no red light to reflect. 



A child wearing a green frock on Independence Day seems 

 at night to be wearing a black frock, if standing near powders 

 burning with red, blue, or violet light. 



