The impediments may restrain the accomplishment of the arrangement of the particles for a time, but the disposing power will overcome them, if the reduction of temperature go on; and when they are overcome _suddenly_, the crystallization will take place _instantly_. Hence the sudden rending of vessels, trees, mountain rocks, &c, upon the sudden congelation of water. Even when there is no cause to impede crystallization, it is well known that the _preparation_ to crystallize, or freeze, may be observed in the liquid; the particles seeming to be _preparing_ to arrange themselves; and then, at a given stage of the preparation, they take their places _suddenly_, and thus we have ice. This consummation may be retarded, or hastened by _artificial_ means. Water may be reduced to a lower temperature by being kept _still_, than when _agitated_. And if it be cooled down to the lowest possible temperature, _without congealing_, it may remain fluid at that temperature for a long time. But if the vessel be _suddenly struck_; or the surface of the water _touched with a piece of ice_; or _a large piece of cold metal be brought in contact with the outside of the vessel; the water will instantly crystallize or freeze in beautiful crystals_. These facts establish the above theory. Because, 1. there is no increased reduction of temperature effected, by striking the vessel, touching the surface of the water with ice, or the outside of the vessel with cold metal. 2. There is every reason to conclude these things _commence the motion_ in the water, which is at rest, balanced between an inclination to be at rest, and an inclination to move in arranging the particles; the motion communicated overcomes this balance in favor of the disposition to crystallize, and hence the water freezes instantly, with an expansion of volume.] It is owing to the _expansion_ of water in freezing, that rocks and trees are often split during intense frosts. According to the calculations of the Florentine academicians, a spherule of water, only one inch in diameter, expands in freezing with a force superior to the resistance of 13½ tons weight. Major Williams also attempted to prevent this expansion; but during the operation the iron plug which stopped the orifice of the bomb-shell containing the freezing water, and which was more than two pounds weight, was projected several hundred feet with great velocity; and in another experiment the shell burst. This property of water is taken advantage of in splitting slate. At Colly Western, the slate is dug from the quarries in large blocks: these are placed in an opposite direction to what they had in the quarry, and the rain is allowed to fall on them: it penetrates their fissures, and the sharp frost freezes the water, which, expanding with its usual force, splits the slate into thin layers.[84]