THE WORLD BEFORE LIFE. 



521 



The Cherzolite, a volcanic aggregate of peridote, enstatite, and py- 

 roxene, from the Pyrenees, in Spain, presented, after fusion, specimens 

 the most like the meteorites. These experiments suggest that the 

 meteors had once been fused, as is commonly believed, and that the 

 slight differences existing between thenx and the peridotic rocks may- 

 be explained by supposing the latter to have cooled in the presence of 

 oxygen (or air), while the former may have solidified where the supply 

 of oxygen was limited. When melted, the two mixtures are precisely 

 alike, and we may conceive of the existence beneath us, in the great 

 caldron whence the volcanoes derive their lava, of a zone of meteor-like 

 mixtures, both the peridotes which are now melted and occasionally 

 brought to the surface, and the heavier metallic masses, too deeply 

 seated to be ejected by any convulsive throb of our planet. For aught 

 we can say, the heavier meteors may indicate the exact character of 

 the interior nucleus, just as those black stones falling from the sky 

 have revealed the composition of other worlds. Their weight would 

 correspond well with that of the interior mass. The specific gravity of 

 granite is from 2.64 to 2.76 ; of basalt, 2.9 to 3.1 ; the peridotes, 3.3 to 

 -3.44 ; and the heavy meteors from 7 to 8. Hence, while the granitic 



Fig. 5. 



Zones in the Earth and Atmosphere. 



A. Solid Nucleus of Heavy Metals or Meteors; B. Region of Stony Meteors; C. Region of Lava; 

 D. Region of Basalt and Pophyry; E. Region of Granite, and Surface of the Solid Crust; 

 P. Region of Acid Gases; G. Region of Carbonic Acid; H. Region of Nitrogen and Oxygen; 

 I. Steam. 



materials may have cooled near the surface, and the basalts lower 

 down, the stony meteors would form a zone beneath the second, and 

 the metallic masses, if present, may constitute the central nucleus. 

 We must not forget the trachytes, and most modern lavas, which 

 would underlie the basalts. It would be easy to calculate the thick- 

 ness required for these different zones, whose general average should 

 be the density of the earth. When water is added to the peridotes 

 and stone-meteorites, the rock is analogous to serpentine. We may 



