56 THE CHEMISTRY OF CREATION. 



more rapidly at high than at low temperatures, 

 the heat of the sun is largely concerned in each 

 of the chemical phenomena, which are constantly 

 taking place throughout nature. 



The most remarkable of the three principles 

 hitherto found in the sunbeam is the Actinic 

 ray. The discovery of this most remarkable 

 principle if that is a correct term for it is 

 quite recent, comparatively with that of the 

 two others. Yet its effects have been known 

 for ages. From time immemorial chemists have 

 known that on exposing preparations of silver 

 to the sun they become decomposed, and en- 

 tirely altered in character. -The researches of 

 many philosophers in modern times have now, 

 as we have already shown, proved the existence 

 of these rays of actinism, in the most unques- 

 tionable manner. It is at present impossible 

 to explain the real nature of the actinic force. 

 We must rest satisfied by describing it as that 

 power in the sun's ray which produces the 

 chemical changes taking place in bodies exposed 

 to the light. 



These delicate yet potent rays fall, like the 

 sunlight in which they are found, upon every 

 portion of the surface of the landscape, and 

 together with those of heat and light, they 

 then produce effects of a most important kind. 

 The towering trees of yonder forest, as well as 



