118 THE CHEMISTRY OF CREATION. 



rise of temperature is undoubtedly principally 

 ascribable to this cause. But when we reflect 

 how bad a conductor is rock or earth, and how 

 very steadily on the average the temperature is 

 found to rise as we descend, instead of diminish- 

 ing, as it should do the farther we get from the 

 supposed source of the heat, and also how little 

 the influence of climate seems to affect it, we 

 must probably come to the conclusion that the 

 heat of which we speak cannot be by any means 

 altogether explained by referring its source to 

 the sun. 



Sir Charles Lyell, the eminent geologist, 

 and others, appear disposed to believe that this 

 heat is due to great chemical decompositions 

 taking place constantly in the crust of our 

 planet. This forms the second theory in our 

 list. School-boys are in the habit of perform- 

 ing a little chemical experiment, which will 

 illustrate this idea very well. They take certain 

 chemical ingredients, among which are sulphur 

 and iron, and bury them a little way in the 

 earth. The substances act on each other, and 

 become heated, so as even to take fire and burn. 

 We can conceive, then, that chemical decom- 

 positions on a larger scale may produce im- 

 mense supplies of heat in the earth's crust, 

 which may be conducted by it throughout its 

 substance. 



