LIFE IN THE PRIMITIVE OCEAN 25 



existed in a state of cloud or steam in the atmosphere. 

 The earth was still a fiery metal globe, surrounded 

 by a tremendous shell or mantle of steam. That 

 is how we find the planets Jupiter and Saturn to-day. 

 They are so large that they have not cooled down as 

 far as the earth. They are red-hot at the surface, 

 and all that we see of them is the great mantle of 

 cloud or steam that surrounds them. You see, every 

 feature of our solar system is just as we should expect 

 to find it on the theory of evolution which I gave in 

 the last chapter. 



Under a great canopy of moisture like this, the 

 metal surface of the earth might remain molten until 

 it sank to about 800° C. ; but its heat was being 

 discharged into space all the time, and its temperature 

 sank steadily. It was, remember, a block of iron 

 cooling down; or, rather, it was a mass of molten 

 iron, like the liquid, glowing stuff you may have seen 

 in a furnace. As the temperature sank the steam 

 would approach closer to the surface, and at last 

 would be able to settle as water. This would, of 

 course, take a long time. At first the water would 

 boil, and be blown back in the form of steam. This, 

 however, would hasten the cooling of the earth, and 

 the time soon came when the surface of the globe 

 was covered with a boiling ocean. It was not at first 

 salt water. The salts of the sea have been gradually 

 washed out of the rocks. But as the primitive atmos- 

 phere was very far from pure, the waters which settled 



