572. The proper organs of the planet are the mineral aggregates or rocks. These are either presented to us as they have originally been precipitated from water by chemical process, or as they have been changed by the co-operation of the other elements. There are thus _genetic_ and _metamorphosed_ kinds of rock. The former were crystallized previous to the current of the water--_Primary rocks_. These rocks are changed either-- 1. By water--Transition-rocks, or 2. By air--Trappean-rocks. 3. By fire--Volcanic-rocks. There are properly four kinds of rock formations-- 1. Earth-formation, masses that have originated through the crystallizing force of the earth-element itself--Primary-rocks. 2. Aqueous-formation--Transition-rocks. 3. Aerial-formation--Trappean-rocks. 4. Igneous-formation--Volcanic-rocks. The stratified rocks, having originated for the most part mechanically, are only the object of Physio-philosophy, in so far as chemical precipitations partly occur amongst them. 573. The earth-formation is represented by the crystallized primary rocks. a. _Earth-Formation._ 574. The earths can only be precipitations from the element that immediately precedes them, and thus from water. They have been enveloped in the water, as this has been in the air, and the latter again in the æther, but not mechanically, as we at present dissolve clay in water, nor chemically either, as lime dissolves by corrosion in water, but dynamically. The water did not exist from the beginning as water in the air, but only its principles, which became for the first time water, when they had combined by electricity. 575. Even so was it the case with the earths. The primary water, which was present prior to the solid nucleus of the earth, is not the water, with which we are at present acquainted; it had still the earthy principles, the basic in itself, which being separated by a differencing act from the oxygenous of the water, was deposited as carbon specially produced. No calcareous, argillaceous, and silicious earth was imbedded in the primary water. How then could they have been dissolved in it? Some say, by a great quantity of acids which prevailed at that time; but from whence then did these acids come? The largest quantity of them resides in lime, gypsum, and common salt; but how could this quantity, which has not so much as acidified all the calcareous earth, have held the rest of the earths in solution? And then again are all the earths soluble by the process of acidification? We cannot reason in geogeny, as we would of a common chemical precipitation, where we precipitate earths that have been dissolved by elective affinities.