14 PROCEEDINGS OF THE ACADEMY OF [1897. 



upon the surface conditions of the earth. There may have been 

 then a very active tendency to volcanic or earthquake disturbances, 

 but this tendency must have been held greatly in check by the pres- 

 sure. This great pressure must also have exerted a vigorous influ- 

 ence in condensing surface and aerial materials, converting vapors 

 into liquids and liquids into solids, and thus have played its part in 

 the formation of a solid crust. Again, the abundant aqueous vapor 

 must have been active in the process of surface cooling, rising in 

 heated winds and conveying heat to the upper air. Finally, as the 

 temperature fell, the pressure of the vapor condensed some of its own 

 material into water. The escape of heat then grew still more rapid, 

 through the aid of evaporating water and falling rain, processes 

 which may have long been incessant. 



As the surface cooled, through these and other influences, the 

 conversion of vapor into water went on more rapidly, and the atmos- 

 pheric pressure steadily decreased. This was probably attended 

 with an increase in surface disturbances, the wave of disturbance 

 growing in height as the pressure diminished. As the solid crust 

 grew thicker and the rocks more rigid from progressive cooling, 

 these seismic disturbances again diminished. There was thus prob- 

 ably a cycle of change, from an originally level and quiescent sur- 

 face to one of ridges and depressions with great disturbance, and 

 again to one of growing quiescence and gradual reduction of ine- 

 qualities. 



Of the chemical activity of water at a temperature of over 600° 

 we have no knowledge, as water of this temperature has not been 

 produced in laboratories under circumstances suitable for experi- 

 ment. Its solvent powers would probably be very great, and many 

 substances may have been held in solution in the waters of the 

 primeval ocean which are insoluble at present temperatures. These 

 substances were, probably, in part washed down from the air into 

 the gathering ocean, in part dissolved from the surface. The bring- 

 ing together of numerous elementary substances or simple compounds 

 in a common menstruum was undoubtedly followed by great chemical 

 activity, and numerous compounds of more or less intricacy were 

 formed in the heated waters. Of these, some were insoluble and 

 settled to the bottom ; others were soluble and continued in solution. 

 The salts of the present ocean are doubtless, in great measure, the 

 final outcome of these ancient solutions and chemical actions. They, 

 in all probability, represent but a small fraction of the substances 



