^6 THE MAMMOTH CAVE OP KENTUCKY. 



M( pamm0th (Kaw 0f §entttclig* 



BY E. WETHERED F.C.S., F.G.S. 



Mead at the General Meeting, December lyth^ 1876. 



THERE are probably few persons who have not wandered 

 among limestone rocks, and been struck with the numerous 

 caves scattered here and there among them. These caves have 

 been formed by three agents : they are, water as a mechanical 

 force, water as a solvent, and carbonic acid, the latter being 

 in the water. Thus we see the agents practically resolve 

 themselves into mechanical and chemical. Rain as it descends 

 from the clouds to the earth, absorbs carbonic acid which has 

 been given off as a dilution to the air from the respiration 

 of animals, and by combustion, and other causes. The rain so 

 charged, falls upon limestone districts, among others, and the 

 limestone is readily dissolved in the presence of the carbonic acid. 

 This is well demonstrated in what we term hard water -, to soften 

 it, we boil it, and a precipitate of lime falls to the bottom of the 

 vessel 3 and why, simply because we have driven off the carbonic 

 acid, and the lime is no longer soluble. 



