56 THE EARTH. 



gases into liquids, and of liquids into solids, causes a very 

 large portion of latent caloric to become sensible, for example, 

 any quantity of a gas at 60 deg. suddenly reduced to a 

 smaller bulk, would have a temperature higher than 60 deg. 

 A little contrivance has long been in use for obtaining fire 

 by this process, consisting of a cylinder and piston, the rod 

 of which if struck down sets fire to a piece of G-erman- tinder. 

 It is probable that all fire, and every alteration of tempera- 

 ture, are due to this one cause alone. 



Now assuming it as a fact that the earth was once in a 

 gaseous state, and that the atoms of this gas or vapour 

 exerted (as they must have done) an attraction towards 

 each other, the result would be that they would press 

 immensely upon those parts towards the centre and cause 

 them to solidify. This act of solidification would produce 

 such an intense heat that the solid would be expanded and 

 fused into a liquid, this continuing until all the more con- 

 densible matters had become liquid, the earth would assume 

 its spheroidal form from its rotation, be surrounded by 

 an atmosphere of the least easily condensible substance, 

 nitrogen, together with all the oxygen not wanted to combine 

 with the metallic vapour and form earth. This globe with 

 its atmosphere continuing to roll through the cold regions 

 of space, would gradually lose the heat from its outer part 

 by radiation. A film of cooled and condensed earthy matter 

 would begin to form on the surface by crystallisation, and 

 then would commence all those grand phenomena which it 

 is the province of the geologist to study and explain. This 

 crust consisted of the first-formed granite which (from 

 inequality of contraction in the bulk of the earth) was 

 broken up into fragments and perhaps partly re-dissolved 

 again and, again in some places, as it chanced that these 

 contractions were more or less irregular. The result of this 

 crushing and crumbling-up is seen in the coarser parts of 

 the gneiss, called " Grauwacke," which consist of angular 

 fragments of granite more or less imbedded in a cement of 

 the same substance. This could not have been produced by 

 water, as the surface must have been too hot for it to have 

 existed on the earth in any other form than the most highly 



