THE WORLD BEFORE LIFE. 523 



between the crust and solid nucleus has solidified, will eruptions of 

 lava cease to flow from volcanoes. 



As time progressed this congealed crust would increase in thick- 

 ness. Being unyielding, there would be stamped upon it, as plainly 

 as the form of a pitcher by the moulder, the peculiar flattening of the 

 earth, as determined by the rate of rotation. As soon as the internal 

 fires were concealed, the rotation of the earth would give rise to the 

 alternation of day and night — not, certainly, of the same length as 

 now, since the bulk of the sphere was greater, and with a reduction 

 of size the tendency is to an increase in the rate of rotation. But, 

 with the thick atmosphere, the days must have been dark and gloomy. 



At the present day the attraction of the sun and moon produces 

 the phenomena of the tides. As the crust is rigid, only the water 

 upon it can now be moulded into different shapes. But, when the 

 whole earth was pliable, its form must have varied daily, much more 

 symmetrically than at present. As the outer envelope stiffened by 

 cooling, tidal waves would form with great difficulty, and eventually 

 the crust would become too rigid to be affected. Perfect rigidity was 

 not attained during the whole inorganic period. While thin, the crust 

 may have been broken by the attraction, and the liquid oozed out 

 through the crevices, overflowing the surface, and returning at low tide. 

 So great is the power of tidal attraction that a rigid envelope, hundreds 

 of miles in thickness, would be fractured by it. The rents formed were 

 like the faults observed in the strata of the organic periods. More 

 or less fracture probably attended every tidal attraction, until the 

 ocean covered the surface, and presented a material easily modulated. 



Age of Chemical Changes. — Following the age of igneous fluidity 

 there succeeded another of great interest. It opens with the surface dry, 

 rough, and slaggy ; the interior in intense fusion, and the atmosphere 

 containing all the water of the ocean with numerous volatile com- 

 pounds. Before its close an ocean is formed, most of the gases have 

 left the atmosphere, and chemical agencies acted with great intensity, 

 and so universally as to characterize the period. The falling of the 

 primeval rain dissolved acids in the air, and poured upon the elements 

 never exposed to moisture streams of acidulous waters, well fitted to 

 dissolve out large portions of the original crust. 



In order to ascertain the character of this primitive rock, we must 

 adopt the method suggested by Sterry Hunt, in his lecture before the 

 Royal Institution of Great Britain, and consider what changes would 

 result if intense heat should now act upon the crust. The water 

 everywhere would be evaporated, leaving behind its saline impurities. 

 All the carbon in living plants, and the immense supplies of coal 

 stored up in the earth, would become converted into carbonic acid ; 

 the siliceous parts, fused with limestones and other rocks, would make 

 silicates of lime, magnesia, etc., and expel the carbonic acid. The 

 sulphur would form sulphurous acid with oxygen, changing eventual 1}' 



