184 THE PEmCIPLES INVOLVED IN BOCK-WEATHEEING 



moting decomposition than water alone. Plence under certain 

 conditions the process of decomposition once set in opei'ation 

 augments itself, and goes on with increasing vigor nntil such a 

 depth is reached that the percolating solutions become neutralized 

 and further action, aside from hydration, practically ceases. 



