tNTJt OD UCTION 



attended with the development or the absorption of 

 heat, and also with manifestations of electrical phe- 

 nomena. Heat and electricity themselves induce 

 chemical changes. These relations indicate that 

 chemical affinity, like heat and electricity, is de- 

 pendent upon the properties of the Ether, but what 

 chemical affinity is, or why it acts, it is almost im- 

 possible to conceive. The possible cause of Static 

 electricity and of electro-conductivity the Ions of 

 the Ethereal molecules has been suggested by the 

 Writer. A description of the generation of the 

 Kathode and of the Rontgen rays has also been in- 

 cluded. 



The Geogony of the earth covers too wide a field 

 to be more than merely named. A suggestion is made 

 of the probable origin of carbo-h yd rides from inor- 

 ganic changes. Since writing this M. Moissan has 

 shown the probable production of Petroleum in the 

 earth from metallic Carbides. 



The fleeting view thus taken of the phenomena of 

 the inorganic world shows that all knowledge thereof 

 has only been obtained by the close observation of 

 countless individual facts. By classifying them into 

 groups of more or less general similarity, and noting 

 their accordance with or divergence from some com- 

 mon principle, mode of action or of force, we think 

 we understand their nature and what they are. But 



(XX) 



