air and suddenly congealed. Snow, the ermine of the earth, is the
crystallized moisture of the air, and is in subjection to unchanging
laws.

Water contracts as it grows colder, until it falls in temperature to
42°. It then expands till it reaches 32°, when it becomes solid,
though its density is actually diminished, and its specific gravity is
reduced to .929, while that of unfrozen water is 1.000. Of course it
is much lighter, and it floats. This admirable arrangement prevents
our rivers being frozen up and our lakes becoming solid. Ice thickens
because it is porous, and allows the heat of the water to pass up and
the cold to descend; but this is happily a slow process, as ice is a
bad conductor. Salt water freezes at the temperature of 7°, 25° below
freezing-point. There are many things to be said about ice, whether as
glaciers, or Arctic bergs, or, as it is found sometimes, contrary to
its general law, at the bottom of rivers and ponds, its geological
movements in the transportation of boulders, and as an article of
luxury;--but we are compelled to leave them for the present.

Snow, which, in its crystallization, surpasses the most perfect gems,
is invariably found arranged in determinate angles, to wit, 60°, and
its double, 120°, and formed of six-sided prisms. More than one
hundred kinds have been described by Dr. Scoresby and others, and all
these are combinations of the six-sided prism. The uses of snow, from
its non-conducting qualities, whether as appreciated by the Esquimaux
as a material for huts, or by the agriculturists of our own climate as
sheltering the seed, are too well known to require any particular
remarks. Strange as it may appear, the proximate cause of the
formation of snow is not yet fully agreed upon by the learned.