828 THE POPULAR SCIENCE MONTHLY. 



depths of the globe, has absorbed oxygen from the air, has become 

 sulphuric acid, and, acting upon the already formed limestone, has 

 produced gypsum, as in the previous theory. 3. Salts already formed 

 in the interior of the globe have been brought up to the surface partly 

 in solution, partly sublimed. These hypotheses are all wholly gratui- 

 tous ; and, with regard to the first, it is impossible to admit that sul- 

 phuric acid, already formed, coming up from the depths of the globe, 

 should have traversed, without saturating them, the enormous thick- 

 ness of the underlying calcareous beds to make gypsum in the tertiary 

 formation. The second hypothesis is more admissible, especially since 

 M. Dumas has found gypsum that was evidently formed in that way ; 

 but while we may easily suppose a mass of limestone, of which one 

 part has been transformed into gypsum by the action of free sulphuric 

 acid, while the other part remains limestone, we can not admit such 

 an intervention of the acid in a case where the gypsum is interpene- 

 trated in all its parts with carbonate of lime. The third hypothesis, 

 that the saline deposits have been brought up from the depths of the 

 globe, is only a continued appeal to those mysterious actions which 

 figure so prominently in the infancy of all the sciences ; but, besides 

 that it explains nothing, I believe that it is a real error. My studies 

 of chemical geology have led me to the conclusion that the salts now 

 held in solution in the waters of the seas, the salts existing in solid 

 masses in the strata of our globe, and those which furnish the mineral 

 constituents to saline waters, have a common origin, and that that 

 origin is exterior to the first strata that were formed in the consolida- 

 tion of the earth. 



According to the conditions assumed in the nebular hypothesis of 

 the origin of the earth, the rocks forming the first solid envelope of 

 our globe solidified at a temperature of between 2,000 and 2,500 Cent. 

 (3,600 and 4,500 Fahr.). Now, according to the law of dissociation, as 

 discovered by Sainte-Claire Deville, chlorine, sulphur, and their constant 

 compounds, with oxygen and hydrogen, were present in the atmosphere 

 at the former temperature, and even below it, in a state of complete 

 dissociation ; and only at a much later stage than this was it possible 

 for chlorine and sulphur to effect combinations so as to react upon 

 the exterior crust and form sulphates and chlorides. The sulphates 

 and chlorides, in their turn, could have been produced only at succes- 

 sive and extremely distant epochs. Thus, to mention only the two 

 chlorides which constitute the largest part of the saline substances con- 

 tained in marine waters, the chloride of sodium and the chloride of 

 magnesium ; the former has been formed at a high temperature, for it 

 can support a high temperature without suffering decomposition. But 

 the chloride of magnesium can not have been composed until a prodi- 

 giously more advanced epoch that is, one nearer to our own time, 

 when the temperature of the earth had descended to about the 

 boiling-point of water; for the chloride of magnesium can not sup- 



