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380 surrounded by water tend to retain their fluid state in both directions at temperatures which are abundantly sufficient to make it equally retain the solid or the vaporous state when either of them is conferred upon it. There is nothing against the assumption that ice has the like kind of power, i. e. the power of retaining its solid state at temperatures higher than the temperature of ice against water. Nevertheless, the fact is more difficult to show; still some experiments may be quoted in favour of the view. If hydrated crystals of sulphate of soda, carbonate of soda, phosphate of soda, &c. , be carefully prepared in clean basins, by spontaneous evaporation of the water they will retain their form unbroken, and their hydrated state undisturbed, through the high temperatures of a whole summer; though if broken or scratched even in winter, they will commence to eifloresce at the place where the cohesion, and with it the balance of force was disturbed, and will from thence change progresively throughout the whole mass. As regelation concerns the condition of water, there is perhaps no occasion to go further. Such facts as the following, however, concern the extension of the principle and illustrate the power of cohesion, especially in cases where it is coming into activity. Camphor in bottles, or iodide of cyanogen in proper glass vessels produce crystals sometimes an inch or two in length, which grow by the deposition of solid matter on them from an atmosphere unable to deposit like solid matter upon the surrounding glass, except at a lower temperature. Crystals in solution grow by the deposition of solid matter on them which does not deposit elsewhere in the solution:—many such like cases may be produced.

Returning to the particular case of reg elation, it is seen that water can remain fluid at temperatures below that at which ice forms, by virtue of the cohesion of its particles, and in so far the change is rendered independent of a given temperature. Next, I rest on the fact that ice has the same property as camphor, sulphur, phosphorus, metals, &c., which cause the