1897.] NATURAL SCIENCES OF PHILADELPHIA. 15 



then held in solution by the heated oceanic waters, which, from their 

 large percentage of foreign constituents, may have been almost jelly- 

 like in consistency. 



It is impossible to estimate the chemical activity of that period. 

 The high temperature of the waters greatly favored such action, and 

 among the dissolved substances were probably many unoxydized 

 materials, now first freely exposed to the assaults of oxygen. The 

 energy of chemism that ensued was probably greater than had ever 

 before or has ever since existed. In addition to simple oxides, many 

 more complex substances were doubtless formed, and it may be that 

 many of the constituents of the primeval rocks then and thus first 

 came into existence. 



The story of chemical activity in the earth is, therefore, very 

 closely connected with that of the ocean. It began, no doubt, in 

 the primeval atmosphere, but reached its culmination in the waters 

 of the ocean. During the early period of the earth chemical 

 inaction must have long prevailed, on account of high temperature 

 and unfavorable physical conditions. Perhaps the principal chem- 

 ical action of the primeval atmosphere was the combination of oxy- 

 gen and hydrogen into water vapor. But, on the formation of an 

 ocean of highly heated waters, holding in solution a considerable 

 variety of elementary substances and simple compounds, chemism 

 probably grew active, and in time became very energetic as the 

 waters increased in depth and in the variety and volume of their 

 contents. Many of the complex minerals were very likely then 

 formed, and, being insoluble, were separated from the water and de- 

 posited as rock formations. Only when the ocean became, in a 

 measure, freed from its abundance of foreign material, did this ac- 

 tivity of inorganic chemistry decrease. It has continued to decrease 

 until the present time, when it has practically ceased to exist, oxida- 

 tion having reduced nearly all substances to a state of chemical 

 fixity. 



It has been succeeded by an era of organic chemical action, which 

 is, at present, in a state of full activity, and promises long to con- 

 tinue so. It began in the early seas, probably after their temperature 

 had diminished to near or below the present boiling point. It grad- 

 ually replaced inorganic chemism, and has long continued active, at 

 first in the water, and later on the land also. It is now, and has 

 long been, at its maximum activity, the quantity of new material 

 produced in the plant and animal world being annually enormous. 



