556 GEOLOGY, 



Chemical combination. — The general effect of chemical combination 

 under pressure is greater densit}^ In reversible reactions capable 

 of conditions of chemical or physical equilibrium, pressure invariably 

 favors the formation of the denser of any possible products. 



Sub-atomic forces. — Recent investigation has made it probable that 

 atoms are composite, embracing many exceedingly minute bodies — 

 corpuscles or electrons — in a state of extremely high activity and pos- 

 sessed of marvelous energy notwithstanding their minuteness. This 

 discovery possesses deep interest to the geologist because it seems to 

 reveal sources of energy of almost incalculable potency, some portions 

 of which at least are being constantly freed and added to the previously 

 recognized supplies of energy. Attempts have been made during the 

 past few decades to limit the habitable age of the earth, both retrospec- 

 tively and prospectively, by the smallness of the sum total of energy 

 derivable from gravity. In these estimates slight recognition has been 

 given to the resources of molecular and atomic energy, and none at all 

 to the possibilities of sub-atomic energy. It would be going quite too 

 far to assume that these sub-atomic energies are all available for the 

 perpetuation of habitable conditions on the earth or in the solar system, 

 but we are doubtless justified in appealing to them as an offset to all 

 dicta restricting the period of the earth's habitability by supposed 

 insufficiencies of energy deduced merely from the estimated resources 

 of gravity. The banishment of the idea of the atom as a minute, incom- 

 pressible, undecomposable sphere takes away the theoretical limit of 

 compressibility, and by so doing cuts away the groundwork for assign- 

 ing definite limits even to the resources of gravity, since, as already indi- 

 cated, unlimited condensation gives theoretically unlimited transfor- 

 mation of the potential energy of gravity. 



While we must await with such patience as we can command the 

 development of fuller knowledge concerning the nature and laws of the 

 molecular, atomic, and sub-atomic energies, and their applicability 

 to the activities resident in the interior of the earth, it is permissible 

 even now to assume that, besides the simple compressive action of 

 gravity, there are at work varied forms of molecular aggregation, of 

 atomic combination, and perhaps of sub-atomic change, tending toward 

 increased density, and that the ulterior limit of these processes is quite 

 undetermined. The condensational forces are now restrained at cer- 

 tain temporary limits by the antagonistic resistant forces, some of 



