| 1. Earth-earths | Silica; Quartz, &c. |
| 2. Haloid-earths | Clays; Felspar, &c. |
| 3. Inflammable-earths | Talcs; Mica, &c. |
| 4. Metallic-earths or Ores | Calx. |
519. Nature does not produce any so-called pure calcareous earth, but only this earth in an oxydated condition. Carbonic acid is the oxygen of the earth that has become free, and the corroding calx is the Metallic, the other constituent part of the Earthy, which has obtained some oxygen, but lost the Aqueous by the carbonic acid and thereby has become corrosive.
520. The carbonate calcareous earth is the whole earth, not the corrosive. This is only the half of the earth-element, only its basic or phlogistic principle. What has been called pure calcareous earth is a half earth; the perfect or naturo-historical earth is just that which is chemically impure.
521. The calcareous earth is not, however, perfected with one position. It still exhibits several stages of development which appear to be approximations to the salt, e. g. Strontian and Baryta.
522. The silicious earth, which principally represents the Earthy, holds its principles more firmly together. No separation occurs there in the carbonic acid and the basic or corroding body of earth; no association with water, no great activity, no direct participation in the highest evolutions of the planet; but it continues to lie in an extreme state of contraction, and in a state of indifference in the non-differencing darkness.
523. This pure earth is the basis, the pedestal of all the other earths, and the foundation of the planet; for it alone is the earth proper, the earth-abiding earth-element, while the other masses of earth, divided in their principles, have pitched themselves in outward opposition to the sun and other elements. The silicious earth is in every respect the centre of all earthy productions, these being only digressions from it. The Zircon earth is only a removal or displacement of the silicious toward the argillaceous earth.
524. The argillaceous earth also is not dissevered into its principles; it is not found as a carbonate. On the contrary, it is at once shown to be far more pliable by its capacity for being kneaded and moulded in water, and by its hardening when exposed to air and fire. It is also seized upon and dissolved, i. e. reduced to the aqueous condition, by all acids. Its kindred earths are the Glucine and Yttria, verging towards the talcose earths.
525. The first dismemberment of principles is shown by the talcose earth. Where it appears uncombined with the former earths it is carbonate, yet still feebly corrosive.
526. These three principal earths together make up the body of the earth, while the calcareous earth is only spread over them like a mantle or crust.
527. As no earth is in its totality corrosive, and none such occurs in nature or has at least not been originally produced from it, so may the insolubility of the earths in water be set up as an essential and thoroughly valid characteristic of the earths. Their distinctive characters have been sedulously rendered fluctuating, by having been drawn not from nature, but the products of art. That the corrosive chalk is soluble in water, and may therefore be a salt is true; but it has not issued thus out of the womb of nature. Mineralogy knows nothing of a corrosive calcareous earth. The earths are sufficiently separated from the salts by their insolubility in water. They are separated from the ores by their incombustibleness, or, if they have been already burnt, by their incapacity for reduction. As both of these qualities are imparted by fire, so the earths are distinguished by their immutability in fire, whereby is naturally understood not the scoriation, but change of the earthy character. They differ also in the same manner from the Inflammables. Nature does not undertake the artificial reductions of earths to Metalloids, at least not so, that they may become again of themselves earths. The metals are permanent reductions.