CHEMISTRY OF THE EARTH. 189 



broken up, thus causing the extravasation of the ;vet unsolidified portion, 

 which would contribute to the vast amount of mineral matter brou.iiht 

 within the chemical influences of the surrounding atmosphere. Further 

 contraction from cooling would render this material more or less porous 

 and ])ermeable, ])reparing it for that process of combined mechanical 

 and chemical disintegration which would result from the action of the 

 acid li(piids afterwards to be precipitated from the atmosphere. 



§ 10, We have next to consider the chemical constitution of this irregu- 

 lar surfaced and broken-up crust of anhydrous and ]>rimitive igneous 

 rock, which is now every where buried beneath the products of its disin- 

 tegration. It is evident that, with the exception of those which were 

 still in a gaseous form, it must have contained all the elements which 

 now make up the known rocks of tbe eartli's cnist. If we conceive these, 

 together with the air, the ocean, and its dissolved salts, now to react 

 upon each other under tbe influence of an intense heat, it will enable us 

 to form some notion of the chemical relations of the elements of the 

 globe at the time when they were cooling down from that condition of 

 Igneous vapor which we sujjpose to have been that of our planet at an 

 early stage in its history. To the chemist it is evident that from such 

 a process applied to our globe would result the oxidation of all carbona- 

 ceous matter, the conversion of all carbonates, chlorides, and sulphates, 

 into silicates, and the se]>aration of the carbon, chlorine and sulphur in 

 the form of acid gases, which, with nitrogen, watery vapor, and an excess 

 of oxygen, would form an exceedingly dense atmosphere. The resulting 

 fused mass would contain all the bases as silicates, and would probably 

 nearly resemble in composition certam furnace-slags or basic volcanic 

 glasses. Such we may conceive to have been the nature of the primitive 

 igneous rock, and such the composition of the primeval atmosphere, which 

 must have been one of very great density. Under the jiressure of a high 

 barometric column condensation would take place at a temperature 

 much above the present boiling jjoiut of water, and the lower levels of 

 the half-cooled crust would be drenched with a highly heated solution 

 of hydrochloric acid, whose decomposing action would be powerfully 

 aided by the temperature. The formation of chlorides of the various 

 bases, and the separation of silica, would go on until the af&nities of the 

 acid were satisfied, while there would result a sea-water holding in the 

 solution, besides the chlorides of sodium, calcium, and magnesium, salts 

 of aluminum and other metallic bases. At a later period the gradual 

 combination of oxygen with sulphurous acid would eliminate this from 

 the atmosphere in the form of sulphuric acid. The atmosphere being thus 

 deprived of its volatile compounds of chlorine and sulphur, would ap- 

 proach to that of our own time, but difter in its much greater amount 

 of carbonic acid. It will be remarked that from the aflinities which 

 would come into play in the conditions above supposed, all the elements, 

 with the exception of the noble metals, nitrogen, chlorine, the related 

 haloids, and the hydrogen combined with these, would be united with 

 oxygen. The volatility of gold, silver, and platinum, would keep them 

 still in a gaseous condition at temperatures where silicon, and with it 

 the baser metals, were precipitated in the form of oxides. 



§ 17. The process just described ceased with the separation from the 

 air of the compounds of sulphur and chlorine, and then commenced 

 the second stage in the action of the atmosphere on the earth's crust, 

 by which, under the influence of carbonic acid and moisture, its com- 

 plex aluminous silicates are converted into a hydrated silicate of alum- 

 ina or clay ; while the separated lime, magnesia, and alkalies, being 

 changed into bicarbonates, are conveyed to the sea in a state of solution. 



