ORIGIN OF THE EAETH AND ITS CRUST 117 



Potassium 1.6 



Carbon 



Iron .... 



Sulphur 



Chlorine 



Other elements 



2.4 



100 



Chemical History of the Earth 



In whatever manner our earth came into being, every known 

 fact indicates that in the beginning it must have been intensely 

 heated and in a gaseous condition. In obedience to the laws of 

 matter such a mass would constantly lose heat, and with this loss 

 of heat would come a gain in density, first at the surface only, but 

 gradually progressing toward the center till at that point its con- 

 stituent matter had reached at least a fluid condition. This may 

 be the present condition of the earth's interior. As an eminent 

 chemist has observed, here commences the chemistry of the earth, 

 and the probable course of events can best be stated by quoting 

 from the words of the late T. Sterry Hunt. As long as the earth's 

 component matter remained in a gaseous condition and its tem- 

 perature was sufficiently high to prevent the elements from com- 

 bining, these elements remained separate, but as the temperature 

 was reduced, chemical combinations of these elements became 

 possible, and those would be first formed which were stable at the 

 higher temperature. The oxides of silicon, aluminum, calcium, 

 magnesium and iron were probably among the first substances 

 formed. At some early stage of the earth's existence the bases 

 alumina, lime, magnesia and oxide of iron were probably all com- 

 bined with silica and that which represented the earth's crust 

 was a fluid mass similar to a lava. The carbon, chlorine, sulphur 

 and water vapor only existed in the primeval atmosphere, which 

 must then have been too acid to permit the existence of any form 

 of life, as it would probably have destroyed animal or vegetable 



a Chemical and Geological Essays, pp. 37 et seq. 



