EXPLANATION OF THE EFFECTS
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sequently the form of ice. Thus, the latent heat of the rest of the
water continues afterwards to be extricated flowly and inperceptibly,
in proportion as we abstract the fensible heat into which it is changed,
until the whole of the water is frozen, or has lost the whole of its la
tent heat.
But, when the water is cooled in the circumstances of the above
mentioned experiment, it retains its latent heat and fluidity longer, or
until its sensible heat be diminished to feven or eight degrees below
frost; and, when it is in this state, if it be agitated, or suddenly disturb
ed by the impulse of the air, or the falling into it of a little bit of ice,
or other such matter, this occasions the extrication of a part of the la
tent heat, which now becomes sensible heat, and that part of the
water which thus loses its latent heat is at the fame time changed in
to ice. But the heat thus extricated at once being in greater quantity
than what is extricated in any one moment in the common process of
congelation, it is more conspicuous, by suddenly increasing very re
markably the sensible heat of the materials, and limiting the quantity
of the ice that is thus suddenly formed.
This furprising experiment, therefore, which formerly appeared so
strange and unaccountable, can thus be explained. When this expe
riment is made with great care, in a vessel inaccessible to the external
air, and in a place where it is not disturbed by the tremulous motion
occasioned by walking on the floor, or the rattling of heavy carriages,
it is possible to cool the water even 10 degrees below 32°. If the
water be now touched, ever so gently, with a slender spicula of ice,
formed by crystallization, or a flake of dry snow, it instantly ſhoots
into beautiful spiculæe, which rapidly form and branch out in all di
rections, and the thermometer, which had been left in it, rises flowly
to the 32d degree.
But farther, by the fame principles I also explained some other re
markable facts relating to cold, of which no explanation had before¬