743. The earth-like metals, as iron, manganese, &c. which occur constantly oxydized, are usually found upon the surface of the planet; the hydroid or water-like, as lead, tin, lie usually deeper; the aeroid or air-like, as arsenic, zinc, exhibit pretty nearly the same relations as the sulphur metals; lastly, the pyroid or fire-like, e. g. the noble metals such as gold and silver occur frequently in great depths and not unfrequently in granite; the two preceding metals generally occur in gneiss, but the first even in younger or more recently formed rocks. 744. As a certain regularity prevails in the arrangements of ores and of metals in the veins, so also does this hold good in respect to their distribution over the planet. 745. The more the polar earths are separated and deposited in the broad valleys exposed to light, by so much the more in quantity and of greater purity is the ore produced in its own valleys of darkness. The first effect, however, happens through the power of the sun; the more powerful therefore its influence, although indirect, so much the greater in quantity and purity is ore produced in the depths. The greatest quantity of ore and that of the noblest kind was inevitably generated beneath the equator. There also more lime as well as more salt are probably found upon the surface of the water; towards the north the oxydized metals, or the whole series of iron-metals, were produced. In the Temperate Zones we find more lead, zinc, bismuth and arsenic. 746. Thus the theory itself of ores furnishes us with a proof, such as the theory of the earth that has been hitherto entertained could not afford, that the equator forsooth has since the formation of the metals not been displaced. The metals formed themselves cotemporaneously with the gneiss, and have thus begun to form prior to the existence of the organic world. It is therefore a vague opinion, devoid also of foundation, that since the earth has been inhabited by animals, even by the higher or hair-clothed vertebrata, its axis has been changed. 747. No earthly phenomenon speaks so clearly and loudly against the mechanical theories in the natural sciences as ore. Not only has the whole planet been included in the ore, but also the whole of science, the whole of philosophy. 748. The first transition of the Earthy into the metallic character is indicated by iron. Iron ranks next to earth, especially to the argillaceous earth, is everywhere associated with it and is most generally distributed, being mixed with almost every earth and even all organic bodies, to their very elements. 749. The whole series of metals has but _one_ root. What the primary earth is for the metamorphosis of earths, that is iron for the metals: it is their silicious earth. 750. The iron as being the first transition from the Earthy into the Metallic has the highest grade of fusion, and all metals which approximate to this, belong to the retinue of iron. This grade may be set down as 20,000F.