During frosty weather, let a vessel be half filled with water, cover
it closely, and place it in the open air, in a situation where it will
not experience any commotion: it will thereby frequently acquire a
degree of cold more intense than that of ice, without being frozen.
If the vessel, however, be agitated ever so little, or receive even a
slight blow, the water will immediately freeze with singular rapidity.
The cause of this phenomenon is, that water does not congeal unless
its particles unite together, and assume among themselves a new
arrangement. The colder the water becomes, the nearer its particles
approach each other; and the fluid which keeps it in fusion gradually
escapes; but the shaking of the vessel destroys the equilibrium, and
the particles fall one upon another, uniting in a mass of ice.
Or, provide a glass full of cold water, and let fall on its surface a
few drops of sulphuret of carbon, which will instantly become covered
with icy network: feathery branches will then dart from the sulphuret,
the whole contents of the glass will become solidified, and the
globules will exhibit all the colours of the rainbow.