PETRIFACTIONS.
Everywhere in fossiliferous rock may be found organic remains in which the material of which they were originally composed has been replaced by some mineral substance. Some have supposed that these plants and animals have actually been converted into stone by a change of their elements. This is of course absurd. Carbon can never be anything but carbon, nor indeed, can any element ever become anything other than itself. This dream of the alchemist was long since dissipated. No, strange as it may seem, the molecules of these fossilized organisms must actually pass out, and silica, lime, clay, or some such matter pass in and take their places. Beautiful specimens of petrified wood, found especially on the Pacific coast, are often hard as glass. One very handsome variety, called “opalized” wood, clearly indicates that petrifaction was either accompanied or followed by crystallization.
Myriads of shells, bones and plants scattered through the earth’s strata have been transformed in the manner indicated. Although petrifaction is usually a long process, there is reason to believe that it sometimes takes place rapidly. This operation must not be confounded with incrustation, which is often mistaken for it, and takes place where substances, like bending twigs, have deposited upon them layer after layer of lime, salt, sulphur or ice.
The molecules of solids, even, are in intense and ceaseless motion. As has been said, “A continuous and restless, nay, a very complicated activity is the order of Nature throughout all her individuals, whether these be living beings or inanimate particles of matter. Existence is, in truth, one continued fight, and a great battle is always and everywhere raging, although the field in which it is fought is often completely shrouded from our view.”
Ex.—A simple illustration of the convenience of machinery in applying force and changing direction.
The motto of the brave Huguenots in the time of Louis XIV. was “Ever burning, but never consumed.”
Nature’s motto, both for matter and energy is, “Ever changing, but never destroyed.” Let us next notice some instances of the