40 THE CHEMISTRY OF THE PRIMEVAL EARTH. [IV. 



the solid nucleus. It is to the composition of this crust that 

 we must direct our attention, since therein would be found all 

 the elements (with the exception of such as were still in the 

 gaseous form) now met with in the known rocks of the earth. 

 This crust is now everywhere buried beneath its own ruins, 

 and we can only from chemical considerations attempt to re- 

 construct it. If we consider the conditions through which it 

 has passed, and the chemical affinities which must have come 

 into play, we shall see that they are just what would now result 

 if the solid land, sea, and air were made to react upon each 

 other under the influence of intense heat. To the chemist it is 

 at once evident that from this would result the conversion of 

 all carbonates, chlorides, and sulphates into silicates, and the 

 separation of the carbon, chlorine, and sulphur in the form of 

 acid gases, which, with nitrogen, watery vapor, and a probable 

 excess of oxygen, would form the dense primeval atmosphere. 

 The resulting fused mass would contain all the bases as silicates, 

 and must have much resembled in composition certain furnace- 

 slags or volcanic glasses. The atmosphere, charged with acid 

 gases, which surrounded this primitive rock, must have been of 

 immense density. Under the pressure of such a high baromet- 

 ric column, condensation would ' take place at a temperature 

 much above the present boiling point of water, and the de- 

 pressed portions of the half-cooled crust would be flooded with 

 a highly heated solution of hydrochloric and sulphuric ari.ls, 

 whose action in decomposing the silicates is easily intelligible 

 to the chemist. The formation of chlorides and sulphates of the 

 various bases, and the separation of silica, would go on until 

 the affinities of the acids were satisfied, and there would be a 

 separation of silica, taking the form of quartz, and the produc- 

 ti"ii of a sea-water holding in solution, besides the chlorides and 

 sulphates of sodium, calcium, and magnesium, salts of alumi- 

 num and other metallic bases. The atmosphere, being thus 

 deprived of its volatile chlorine and sulphur compounds, would 

 approximate to that of our own time, but differ in its greater 

 amount of carbonic acid. 



We next enter into the second phase in the action of the 



