THB CHRISTIAN NATURALIST. 51 



immutable colours. When this union is destroyed, as 

 in the case of a ray passing through water and viewed 

 at a certain angle, or through a piece of glass having a 

 certain number of sides and termed a prism, it is said 

 to be refracted, or broken back into its simple state in 

 which its separate colours are rendered visible. The 

 surfaces of bodies, or rather the particles which form 

 their surfaces, being then considered as so many little 

 prisms that break the light, it is obvious that they will 

 reflect a variety of colours.* In bodies, however, 

 whose substance is opaque, one uniform colour will be 

 assumed, which will depend upon its tendency to absorb 

 some of the coloured rays, and to emit, or reflect, 

 others. In plants, for instance, only the green rays 



•Dr. Brewster has well observed, that * If the objects of the 

 material world had been illuminated with white light, all the 

 particles of which possessed the same degree of refrangibility, 

 and were equally acted upon by the bodies on which they fall, all 

 nature would have shone with a leaden hue^ and all the combina- 

 tions of external objects, and all the features of the human 

 countenance would have exhibited no other variety than that 

 which they possess in a pencil sketch, on a china-ink drawing. 

 But he who has exhibited such matchless skill in the organiza- 

 tion of material bodies, and such exquisite taste in the forms 

 upon which they are modelled, has superadded that ethereal 

 beauty which enhances their more permanent qualities, and 

 presents them to us in the ever-varying colours of the spec- 

 trum.' — Life of Sir John Newton, p. 78. 



