404 SCIENTIFIC WRITINGS. 



tion of these facts resting on a physico - mechanical 

 basis, which satisfies my own desire to get at the 

 cause of things, but which frequently runs counter to 

 the traditional geological views, and therefore has re- 

 mained almost unnoticed. Of these traditional views I 

 am compelled to declare untenable the one underlying 

 all the rest, that there has been a period, when the 

 earth was in a molten state and surrounded by an 

 atmosphere, which contained the permanent gases and 

 all the water in the form of glowing vapour. The 

 reasons which influence me will become clear, if we 

 go a step further back to the period, when the ter- 

 restrial mass assumed the globular form. Its elements 

 must then have been uniformily commingled, and thus 

 been condensed into a magma by mutual attraction in 

 the gaseous state. A segregation of the more volatile 

 bodies could only occur at the point of solidification, 

 when the gaseous state passed into the fluid and 

 solid. A separation of the more volatile bodies in 

 the gaseous state could then take place according to 

 the progress of this solidifying zone. This separation 

 from the molten interior could however only proceed 

 very slowly, as inferior specific gravity was the only 

 existing force, which could drive to the periphery 

 conglomerations of specifically lighter masses. How 

 great such a difference of density is in the earth's 

 interior cannot be determined, since our knowledge of 

 the behaviour of bodies subjected to such high tempe- 

 ratures and pressures, as prevail in the interior of the 

 earth, is still too slight. It appears however clear 



