Some have supposed that _iron_, probably nearly in a metallic state, constitutes the nucleus of our earth. This idea seems to have been suggested to account for the influence of the earth on a magnetic needle. But the most splendid, and very probable conjecture is founded on the experiments of Berzelius, and Sir H. Davy, on the earths, which experiments prove them to have _metallic bases_ universally: hence all our earths are _metallic oxides_. From these circumstances it is conjectured, that the nucleus of our globe is constituted of the metals in a pure, or nearly pure state, which are the bases of our earths, alkalis, and alkaline earths. It would almost seem a legitimate conjecture to suppose the substances of our globe were, at _first, metals_ and _gases_: that the oxygen, combining with the metals formed earths, and alkalis; and the gases combining among themselves formed air, water, &c. This would be a chemical process, and necessarily _fuse_ and soften the earth, and introduce the process of cooling, which would proceed from the surface towards the centre. Hence some eminent philosophers have conjectured that there is a great degree of heat in the interior of the earth yet: probably the central parts are in a state of igneous fusion. Some recent researches of Cordier tend to establish this opinion. The amount of evidence in favor of this conjecture is increasing annually, and probably will prevail. See the _additional_ paper on _volcanos_ in this volume.] * * * * * _Section_ II.--_Fire._ Omnific word -- Moving principles in Nature -- Criticism on the original word אור aur -- Creation of fire -- Its nature -- Friction exciting the action of fire -- Fire attracted by bodies -- Fire conducted -- Fire in a state of combination -- Fire elastic -- Expansive force of fire -- Subterraneous fires -- Earthquakes and Volcanic Eruptions -- Air a storehouse of fire -- General and final Dissolution of Nature by fire -- Fire a symbol of the Deity, in his gracious presence, vital influence, transforming energy, and destructive operation.