9th.—The beautiful hoar-frost at first gave to every twig and blade of grass the modest, quiet appearance of a wreath of pearls; but last night there was a slight shower of rain, and now every thing is glittering like diamonds. We observed, also, another peculiarly pretty circumstance: the wet being immediately frozen, every thing was enveloped with thin transparent ice, through which the leaves, and berries, and branches, were distinctly seen. Mary immediately repeated these lines:
Every shrub, and every blade of grass,
And every pointed thorn seem’d wrought in glass;
In pearls and rubies rich the hawthorns show,
While through the ice the crimson berries glow.
Already the birds are become tame, and many venture courageously to take crumbs off the window-stones. Poor little birds, this bright clear air, and sunshine, make every body else look gay, while they sit shivering or sadly chirping on the trees; even the hens and ducks look swelled and melancholy.
We walked to-day to Franklin’s farm, and found him taking advantage of the hardened ground, to put out manure; he had two carts employed, and all the people seemed trying to keep themselves warm by hard work.
The field which had been left to remain fallow, will be much improved by this frost, he says. It was a coarse, wet soil, full of lumps of heavy clay; and he shewed us how much these lumps were already broken. My uncle said that the soil being thus divided, and pulverised, would be greatly meliorated; so, as we walked home, I asked him why the lumps of wet clay were broken by frost, which I thought would only have hardened them the more, like the road on which we were walking.
“The reason why the clods of wet earth are burst by the frost, is, that the water which they contain becomes ice; and, in doing so, it swells, and therefore requires greater space than while it was water. In the process of freezing, water crystallizes, and every crystal drives away the adjacent particles which interfere with its exact formation. This does not happen to hard roads, such as we are now walking upon, because they are closely bound, and do not admit the previous entrance of the moisture; but if the road was soft and spongy, you would then probably see, in its rough and uneven face, the effect of the frozen water. When we return home, if you look at the piece of gravel walk which was lately made, and is not, therefore, yet bound, you will observe what a curious appearance the frost gives it; the larger stones, which by their weight prevented the water from spreading under them, will appear sunk; while the sandy, spongy part which imbibed the rain, is swelled by the frost, and raises the surface of the walk. All crystals have a regular form, and in assuming it, they are obliged to recede a little from each other; each crystal, it is true, has but little power, but as their number is almost infinite, their combined power is so great, that what is called in military language a shell, that is, a hollow ball of strong cast iron, if filled with water and the aperture well secured, will burst when the water freezes. When such is the expansive power excited by water as it passes into the state of ice, we cannot be surprised that jugs and bottles of water are frequently broken in a frosty night—and that water pipes constantly burst when the frost penetrates to them.”
10th.—The frost was so great last night, that it caused sad mischief. The thermometer sunk to 24°. Mary had two nice hyacinths in bottles; unfortunately, she placed them yesterday in a window where there was a bright sunshine; Frederick having promised to put them back safely in the latter part of the day. He forgot them; but, as soon as he woke this morning, he went to repair his error—when, to his great dismay, he found the glasses burst, and the water lumps of ice.
He went to Mary, but he was so sorry for his negligence, that she could not reproach him. The only thing to be done, she said, is now to consider how to relieve the bulbs from the ice that surrounds them. Frederick proposed placing them near the fire, that the heat might thaw the ice; but Mary told him that she was afraid the sudden change from cold to heat would make the bulbs decay—and that the best plan, she thought, was to put them into cold water. Mary had called me to look at the glasses on the first discovery of the misfortune; and we carried them and the bulbs inclosed in ice, to my uncle, who had just come down to the library, to consult him on what was best to be done. He approved of Mary’s proposal, and said, “That is a practical instance of the advantage of acquiring different kinds of knowledge.” Mary had concluded, that the sudden change of temperature would produce immediate decay in the roots—on the same principle that heat applied to people who have been frost bitten, causes mortification in the frozen part. My uncle afterwards told me, that the same thing happens to the frozen buds of tender plants, which are exposed to the rays of a hot sun before the frost has been dispersed; while those which are gradually thawed receive no injury.
I reminded him of his having spoken of crystals of ice, and asked how that term could be applied to any thing but mineral bodies.
“The term crystal,” he replied, “came from the Greek word for ice—it was afterwards applied to rock crystal, which the ancients imagined to be water converted into stone; but it now signifies the regular figure in which the particles of any substance arrange themselves in passing from the liquid to the solid state.—Each of those substances has a figure for its crystal peculiar to itself, and from which it never varies. Common salt, for instance, dissolved in water, and slowly evaporated, always forms regular cubic crystals of about an eighth of an inch in diameter, and quite transparent; sugar candy is nothing but sugar crystallized into six-sided prisms; and alum forms itself into beautiful crystals of eight sides. All this you may easily ascertain for yourself by experiment; and when I have an opportunity of taking you to a smelting house, you will see that in the cooling of melted metals, each metal assumes a crystalline shape belonging to itself.”