644. The acid is therefore a half of the earth, which passes over into water, and the corrosive earth is also a half of the earth that has lost its Aqueous. The former is the Aqueous in the earths, the latter the Earthy itself separated from the former. 645. The corrosive force is therefore no peculiar action in nature, but only the effort made by the earths to complete themselves and imbibe water or acid. The corrosive force is no synthesis, but a moiety. 646. A total earth may be therefore regarded as a combination of acid and corrosive body. These two component parts are separable in the calcareous and talcose earths; but in the argillaceous and silicious earths they are so intimately dissolved, that they can not be separated from each other. 647. Carbon, hydrogen and nitrogen, but not oxygen, fall or range upon the corrosive side of the earth in question. 648. Regarded in this general manner the corrosive principle stands opposite to the principle of combustion, and what is combustible, is in idea corrosive. The corrosive power is, however, but feeble in the gaseous nitrogen, stronger in hydrogen and finally strongest in the body of earth. The earthy carbon is the proper corrosive principle. The direct antagonism is not therefore between the corrosive body and oxygen, but between it and the carbonic acid, and therefore between it and all the acids, or acidity generally. The last earthy antagonism is that between the corrosive body and acid. 649. The corrosive body regarded specially as simply a pure earthy body, must stand opposite to the two moveable elements. The corrodent is therefore constantly striving to draw water and air into itself, and upon this depend also the effects produced by the corroding matters. The corrosive calcareous earth acts in a destructive manner, it abstracts water and air from bodies. The action of the corrosive body is a deprivation of water and air, and hence the elevated temperature of burnt lime in water. If again the corrosive lime be full of water and air, it is neutralized. It is now forsooth again a total earth, in a mechanical sense being again provided with water and acid. All earths are an equal or identical mixture. Acids and alkalies are thus to be regarded in this respect as moieties, and thereupon their chemical relation appears to depend. The elemental bodies are desirous to complete themselves. If therefore a base stands in corresponding import with a certain acid, it will thus have a greater affinity for the latter, tending to separate it from some other combination. Upon this principle, which has indeed been hitherto unknown to exist, the grades of affinity appear to depend.