NEWTON AND COMPOSITION OF LIGHT 



discoveries which, it may be added, involved still 

 givuter controversies. 



In commenting on Newton's discovery of the com- 

 position of light, Voltaire said: "Sir Isaac Newton has 

 demonstrated to the eye, by the bare assistance of a 

 prism, that light is a composition of colored rays, 

 which, being united, form white color. A single ray is 

 by him divided into seven, which all fall upon a piece of 

 linen or a sheet of white paper, in their order one above 

 the other, and at equal distances. The first is red, the 

 second orange, the third yellow, the fourth green, the 

 fifth blue, the sixth indigo, the seventh a violet purple. 

 Each of these rays transmitted afterwards by a hun- 

 dred other prisms will never change the color it bears ; 

 in like manner as gold, when completely purged from 

 its dross, will never change afterwards in the crucible." 3 



