Forbes — Chemistry of the Primeval Earth. 439 



silicates, more basic, and of greater density ; the bases being lime, 

 magnesia, alumina, oxide of iron, with soda, and but minor quantities 

 of potash, etc. ; and still deeper a far denser sphere, containing 

 metallic bodies, more or less combined with sulphur, arsenic, etc. 



On the other hand, the atmospheric zone, next the solidified crust 

 of the earth, would be composed of a dense vapour of those cora- 

 ponnds, volatile only at a high temperature, amongst which the 

 chloride of sodium or salt would be probably the most prominent, 

 above this a stratum of carbonic acid gas, and then of water, in the 

 form of steam, whilst the oxygen and nitrogen would be elevated 

 still higher. 



It is imagined that such an arrangement would, on cooling, first 

 condense the lowest atmospheric zone^ (vapour of salt and other 

 chlorides, etc.), on to the already solidified crust of the earth ; cover- 

 ing this with a layer of these substances, in a solid state-; upon a 

 further reduction in temperature the steam in the atmosphere would 

 now be condensed on to this layer, which it would, in great part, 

 dissolve, forming the ocean, which consequently would be salt from 

 the first moment of its appearance on the face of the globe. The 

 atmosphere now surrounding the globe would contain less oxygen 

 and all the carbon, in the form of carbonic acid, (excepting only the 

 amount of that acid already absorbed by and carried down with the 

 rain water), but otherwise it would probably not differ much in com- 

 position from what it is at present. 



From this stage in the earth's history, the author believes that all 

 the changes which have taken place in the globe, up to the present 

 time, have been effected by agencies similar to those going on in it 

 at this present day ; rocks were formed from the wearing down and 

 disintegrating action of the atmosphere or weathering of the primitive 

 crust, ^ and the subsequent stratification of the debris, so formed by the 

 action of the sea ; just as they are at present in the course of formation 

 from the disintegration of pre-existing rocks. Eruptiojis of igneous 

 matter from the still fluid interior* from time to time disturbed and 

 broke through the primitive crust and the rock strata above it, 

 in course of formation from its debris, just as at the present day 

 (though possibly on a somewhat smaller scale), similar outbursts are 

 produced by volcanic action. The products of such older eruptions 

 are almost identical, in chemical composition, with those of the 

 newer period. Thus the result of chemical analysis of the most 

 ancient granite often cannot be distinguished from that of an 



^ The zone of carbonic acid gas would be heavier than that of steam ; 1 cubic foot 

 of the latter weighing at 212° only 265-17 grains, whilst 1 cubic foot of carbonic 

 gas would weigh 642-09 grains, at same temperature. 



2 A rough calculation shows that the layer of sea salt alone would be sufficient to 

 clothe the entire sphere with a crust of salt some 10 feet in thickness. 



3 This action would, no doubt, be much facilitated in the older geological epochs, 

 by the amount of carbonic acid in the atmosphere being so much greater than at 

 present. 



* The contraction, consequent upon the cooling of the original sphere, -would, 

 doubtless, greatly disturb the previously comparatively even surface of the crust, and 

 produce cracks and fissures, the sides of which, from their unequal subsidence or 

 elevation, would often be dislocated and form lines of faults. 



