CHAPTER XV 



ACTION OF CHEMICAL AFFINITY GALVANIC AC- 

 TION MAGNETISM ELECTRICITY KATHODE 

 AND RONTGEN RAYS PERSISTENCE OF ENERGY 

 SOLAR HEAT, THE SOURCE OF ALL ENERGY 

 ORIGIN OF SOLAR HEAT ACTION OF THE ETHER 

 DISSIPATION OF ENERGY ENTROPY. 



THE phenomena of chemical affinities may mani- 

 fest themselves in different ways. Apart from the 

 effect produced upon a single elementary substance 

 by the action of heat, light, or electricity, such as the 

 fusion of a metal, the development of magnetism in 

 iron by an electric current, or the phosphorescence of 

 certain substances after exposure to light which are 

 rather physical than chemical phenomena nearly 

 all chemical changes of combination are caused by 

 variations in the action of the above-named forces. 

 These alterations in affinities may be : 



1st. Simple disruption of the molecules, as when 

 oxide of mercury is resolved by heat into mercury 

 and oxygen. 



2d. The simple union of the atoms or molecules of 

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