Colours. 205 



and green ; and green may be made by a mixture 

 of yellow and blue. 



The theory of colours is therefore now un- 

 folded. Those bodies, or those parts of bodies, 

 which have the property of reflecting only the 

 red-making rays, will appear red; those which 

 reflect the violet will be violet, &c. ; and those 

 which reflect some rays of one colour and some 

 of another will be the intermediate shade or colour 

 between both ; and as white is a compound of all 

 the seven primary colours, so black is an entire 

 deprivation of them all; and when an object 

 appears black, the light is completely absorbed, 

 or at least not reflected by it. To prove, however, 

 still more forcibly that colour is not in the objects, 

 but in the light itself; no object whatever can 

 reflect any other kind of light than that which is 

 thrown upon it ; and when any one of the pri- 

 mitive rays has been separated from the rest, 

 nothing can change its colour. Send it through 

 another prism, expose it in the focus of a burning 

 glass, yet still its colour continues unaltered ; the 

 red ray will preserve its crimson, and the violet 

 its purple beauty ; whatever object falls under 

 any of them soon gives up its own colour, 

 though ever so vivid, to assume that of the 

 prismatic ray. Place a thread of scarlet silk 

 under the violet-making ray, the ray continues 

 unaltered, and the silk instantly becomes purple. 

 Place an object that is blue under a yellow ray, 

 the object immediately assumes the radial colour. 



