1 32 COLOUR OF BODIES. 



points as these is among the highest refinements of 

 science, and, when contrasted with the most sublime 

 efforts of the imagination, they must appear immea- 

 surably superior. 



If a body sends back white light unchanged, it appears 

 white; if the surface has the property of altering the 

 vibration to that degree which is calculated to produce 

 redness, the result is a red colour : the annihilation of 

 the undulations produces blackness. By the other view, 

 or the corpuscular hypothesis, the beam of white light 

 is supposed to consist of certain coloured rays, each of 

 which has physical properties peculiar to itself, and thus 

 is capable of producing different physiological effects. 

 These rays falling upon a transparent or an opaque body 

 suffer more or less absorption, and being thus dissevered, 

 we have the effect of colour. A red body absorbs all 

 the rays but the red ; a blue surface, all but the blue : 

 a yellow, all but the yellow ; and a black surface absorbs 

 the whole of the light which falls upon it. 



That natural colours are the result of white light, and 

 not innate properties of the bodies themselves, is most 

 conclusively shown by placing coloured bodies in mono- 

 chromatic light of another kind, when they will appear 

 either of the colour of that light, or, by absorbing it, 

 become black ; whereas, when placed in light of their 

 own character, the intensity of colour is greatly in- 

 creasing. 



Every surface has, therefore, a peculiar constitution, 

 by which it gives rise to the diversified hues of nature. 

 The rich and lively green, which so abundantly over- 

 spreads the surface of the earth, the varied colours of 

 the flowers, and the numberless tints of animals, toge- 

 ther with all those of the productions of the mineral 

 kingdom, and of the artificial combinations of chemical 

 manufacture, result from powers by which the relations 

 of matter to light are rendered permanent, until its phy- 

 sical conditions undergo some change. 





