FROST

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FROST is the name we give to that state of our atmosphere in which water is changed into ice. (See Feezing.) The degree of temperature at which this takes place, is called the freezing point, (See Freezing Point.) The cold air draws from water the portion of caloric which is necessary for its existence in a fluid state. The power of frost is immense ; a freezing liquid will burst the strongest vessels in which it is enclosed. Organic bodies do not suffer so much from it, and many are entirely unhurt by it. Severe frosts are not so injurious to plants, after dry weather, as when they follow immediately after rain or a thaw. The cause of this probably is, that in damp weather, even in winter, the tender vessels of plants are filled with sap, which, expanding into ioe at the time of the frost, breaks them, and thus injures their whole internal organization. From the same cause, the strongest oaks split in a severe frost; which is also dangerous, and sometimes fatal to men and animals. It appears wholly to destroy the irritability of the bodily frame, and to rob it of its internal heat. A person feels an irresistible inclination to sleep ; he yields, though against his will, and, while lost in insensibility, his limbs begin to stiffen. If a man thus asleep be brought into a warm room, the sudden passage from cold to warmth causes his death ; but if he be rubbed in the snow, he may often recover. The same is the case with regard to the frozen limbs of men and animals, which can only be saved by being gradually thawed, especially in snow. Frost is also very injurious to certain kinds of food. All watery fruits are deprived by frost of their pleasant taste and their nourishing properties, and soon grow rotten after being thawed. Even meat, which appears to be preserved from tainting by the frost, corrupts soon after thawing. Liquids, as beer, for instance, lose their good taste. Violent winds always diminish the coldness of the air. Many fluids expand by frost, as water, which expands about one tenth part, for which reason ice floats in water; but others, again, contract, as quicksilver, and thence frozen quicksilver sinks in the fluid metal. Frost, being produced by contact with the atmosphere, naturally proceeds from the external parts of bodies inwards: so, the longer a frost is continued, the thicker the ice becomes upon the water in ponds, and the deeper into the earth is the ground frozen. In about 16 or 17 days' frost, Mr. Boyle found it had penetrated 14 inches into the ground. At Moscow, in a hard season, the frost will penetrate two feet deep into the ground; and captain James found it penetrated 10 feet deep m Charlton island; and the water in the same island was frozen to the depth of six feet. SchefFer assures us, that, in Sweden, the frost pierces two cubits, or Swedish ells, into the earth, and turns what moisture is found there into a whitish substance, like ice, and penetrates standing water to three ells or more. The same author also mentions sudden cracks or rifts in the ice of the lakes of Sweden, nine or ten feet deep, and many leagues VOL. v. 28 long, the rupture being made with a noise not less loud than if many guns were discharged together. By such means, however, the fishes are furnished with air, so that they are rarely found dead. The natural history of frosts furnishes very extraordinary results. The trees are often scorched and burnt up, as with the most excessive heat, in consequence of the separation of water from the air, which is therefore very drying. In the great frost in 1683, the trunks of oak, ash, walnut, &c, were miserably split and cleft, so that they might be seen through, and the cracks were often attended with dreadful noises, like the explosion of firearms. (Philosophical Transactions, No. 165.) The close of the year 1708, and the beginning of 1709, were remarkable, throughout the greatest part of Europe, for a severe frost Doctor Derham says it was the greatest in degree, if not the most universal, in the memory of man ; extending through most parts of Europe, though scarcely felt in Scotland or Ireland. In very cold countries, meat may be preserved by the frost six or seven months, and proves tolerably good eating. (See captain Middleton's observations made in Hudson's bay, in the Philosophical Transactions, No. 465, sect. 2.) In that climate, the frost seems never out of the ground, it having been found hard frozen in the two summer months. Brandy and spirit, set out in the open air, freeze to solid ice in three or four hours. Lakes and standing waters, not above 10 or 12 feet deep, are frozen to the ground in winter, and all their fish perish. But in rivers, where the current is strong, the ice does not reach so deep, and the fish are preserved.Hoar frost is the dew frozen or congealed early in cold mornings; chiefly in autumn.