128 VEGETABLE COLOURS. 



of the plants, and also forms the acid juice of un- 

 ripe fruits ; while when they decay, and the oxy- 

 dation ceases, they give out the yellow or the red 

 rays, or the russetty and brown tints, which are 

 various mixtures of red, yellow, and green. Fruits 

 too, which are almost all green in their growing 

 states, receive the yellows and reds, and some- 

 times pass into black, or absorb the entire light, 

 get very sweet and mellow, and soon decay. 

 Coe's golden drop, or any of the plums which 

 ripen to a golden orange, spotted with red, are so 

 far instances of the progress of , this action of light 

 upon fruits or of fruits upon light. While green 

 they are very austere ; but as the green fades into 

 yellow, the austerity diminishes ; and when they 

 begin to be spotted with red, they have little or 

 no austerity. These changes are not, however, 

 universal, or even general ; for many of the .sweet- 

 est fruits that we have are green when they are 

 ripe, and red vegetables are often the sourest of 

 their class : so that, though the light may be the 

 agent in these cases, its action is modified by the 

 nature of the plant ; and it may return the red 

 rays from being already saturated with, and as 

 well as from ceasing to elaborate acid juice. 



The philosophy of light is, however, a very 

 obscure and imperfect philosophy ; and there are 

 not many parts of knowledge in which theories 

 are more likely to lead us wrong. The observa- 

 tion of it has the advantage of being, perhaps, the 

 most pleasing, and certainly the easiest of all 

 observation : and thus, with a knowledge of some 

 of the best known and most obvious principles, 

 any man who chooses may derive his full measure 

 of enjoyment from it. Cloud or no cloud, the 

 light on the scene changes its appearance every 



