o^\) WELLS'S NATURAL PHILOSOPHY. 



mingled that the eye only notices the combined effect, which is green. If we 

 now examine the same mixture with a microscope, the blue and yellow par- 

 ticles will be seen separately, and the green color will disappear. 



„^ ^ , 690. The natural color which an obiect 



Why do nat- i -i • i 



""■J-u. """f "'^o exhibits when exposed to the light, depends 



exhibit colors ? ■■■ o 7 r 



upon the nature and arrangement of the par- 

 ticles of matter of which it is composed, and is not the re- 

 sult of any quality inherent in the object itself 



Bodies which naturally exhibit color have, by reason of 

 a certain peculiar arrangement of their surfaces, or mole- 

 cular structure, a greater preference for some qualities of 

 light than for others. If the body is not transparent, it 

 will reflect certain rays of light from its surface, and ap- 

 pear of the color of the light it reflects *, if the body is 

 transparent, it will allow only certain rays to pass through 

 its structure, and will consequently appear of the color of 

 the light it transmits. 



Thus a red body appears red because it reflects or transmits the red ray of 

 solar light to the eye ; and a yellow bod}' appears yellow because yellow 

 light is reflected or transmitted by its surface or structure more powerfully 

 than light of any other color; and so on through all the colors. 



It is not, however, to be understood that colored bodies reflect or transmit 



only pure rays of one color, and perfectly absorb all others ; on the contrary, 



it has been found that a colored body reflects, in great abundance, those rays 



of liglit which determine its particular color, and also the other rays which 



make up white light in a greater or less degree, in proportion as they more 



or less resemble its color in the order of their refrangibility. 



_,„... Some substances have no preference for any one quality of 



When IS a body '■ \ 



colorless, when light more than another, but reflect or absorb them all 



whin' black?'^ equally ; such are called neutral, or colorless bodies. Those 



substances wliich reflect all the rays of liglit which fall upon 



them appear white ; those which absorb all the rays appear black. 



In the dark there is no color, because there is no hght to be absorbed or 

 reflected, and therefore none to be decomposed. 



A glass is called red because it allows the red rays of light to penetrc':o 

 through a greater thickness of its substance than tlie other rays ; but at a cer- 

 tain thickness, even the red rays would be absorbed like the rest, and wo 

 Bhould call the glass black. 



No body, unless self-luminous, can appecr of a color not existing in the 

 light which it receives. This may be proved by holding a colored body in a 

 ray of light which has been refracted by a prism, when the body will appear 

 of the color of the ray in which it is placed ; for since it receives but one col- 

 ored ray, it can reflect no other. 



