The Chemistry of the Primeval Earth. 361 



This notion is supported to a great extent by fallacious reasoning. 

 It is said that in the cooling- of such a fused mass solidification 

 would naturally commence at the surface ; and people have reasoned 

 in that way from a fact which is common to the observation of all 

 of us — the freezing over of our lakes and vessels of water during 

 the winter season. We find that the ice forms at the surface of the 

 water, while the mass below remains liquid ; but modern investi- 

 gation has shown us that water is an exception, differing in this 

 respect from almost all other substances ; and that while ice is 

 lighter than the water upon which it forms and upon which it 

 certainly floats, the solid congealed material of almost all metals, 

 and of all rocks, slags, and such fused substances as might be sup- 

 posed to form this condensed mass of the globe, is very much 

 keavier than the liquid. Without going into the details of these 

 experiments, which have been very carefully made and verified by 

 numerous investigators, we may say in a few words that the process 

 of cooling in a mass like this would be just like the cooling of a 

 great bath of metal or of sulphur ; in other words, the condensation 

 or congelation would commence at the centre and extend outward 

 toward the surface, so that the temperature of the centre would 

 therefore be the temperature of congelation. Matters, too, con- 

 gealing at the surface and going down towards the centre, even if 

 they met a somewhat higher temperature below, would not be 

 exposed to melting, for the beautiful investigations of Messrs. 

 Hopkins and Fairbaim have shown that in such cases pressure 

 actually increases the act of fusion, so that the pressure at the 

 surface actually favours the solidification of the mass, and the 

 temperature at the centre would be actually the temperature of 

 congelation, which is said to increase with the pressure. It has 

 been assumed that this increase was indefinite, so that it was easy in 

 that way to imagine a heat of intense whiteness at a few miles only 

 from the surface ; but you will at once perceive that if these matters 

 had cooled to the solidifying point at the surface and then gone 

 down towards the bottom., it is only the congealing point at the 

 surface which will represent the maximum temperature of the 

 centre of the earth. 



Now comes a very curious question : what is the composition of 

 this fused mass, — or, rather, what is the composition of the largest 

 stratum which remains at the surface ? — for, as I might show you, 

 did time permit, there is no reason to believe that any portion of this 

 great fused mass, with the exception of the very surface, has ever 

 taken any part in the subsequent changes which have gone on in the 

 earth's crust. In other words, we must find in the first few metals 

 of that solid crust, and in the gases and vapors that surround it, the 

 source of all the materials which now make up the solid stratified crust 

 of the earth, the waters of the ocean, and the atmosphere.above us. Let 

 us imagine all these materials to be brought together and fused. Sup- 

 pose all the elements of the visible earth that we know to melt with 

 fervent heat, the chemist, by a knowledge gained in his laboratory, 

 will easily understand the nature of the reactions. All the carbon 



