Frost, is that state of the atmosphere, which causes water and other liquids to congeal, or freeze.

Frost is supposed to descend from the upper parts of bodies ; but no experiments have hitherto ascertained to what depth it will extend either in earth or water, as its e fects vary, according to the degree of coldness in the air, the longer or shorter duration of the frost, the texture of the earth, the nature of the juices with which it is impregnated, etc.

In cold countries, the frost frequently proves fatal to mankind* not only producing mortification, but even death itself. The hands of those unfortunate persons, who die in consequence of intense cold, are first seized, till they lose the sense of feeling; next a drowsiness pervades the whole body, which, if indulged in, is attended with imperceptible dissolution.

If animation is suspended from severe frost, the following will be the external symptoms : rigidity of the whole body; and inflexibility of the limbs, which continue in the same posture as the frozen person had adopted during the unfortunate accident; the teeth are closed 5 froth sometimes issues from the mouth ; there is a total insensibility to all stimulants, and the extremities are partly mortified, and, in some instances, spontaneously separate.

Notwithstanding these unfa-vourable appearances, every exertion ought to be instantly made to restore life, if possible, by strictly adhering to the following directions ; because there is a greater probability of recovering such persons, than those deprived of life, in consequence of drowning or suspension by the cord.

No external warmth of any kind must be applied to frozen persons, till the internal or vital heat, be excited, when the former also should be carefully and very gradually adapted to the manifest degree of the latter.. Hence the whole process should be performed either in the open air, or in a cold room ; the body cautiously carried in a posture somewhat erect, to the nearest dwelling; the head turned gently towards the right side ; and the clothes carefully taken off, without injuring the skin, or bending the limbs. These precautions are necessary, as a rough treatment may easily occasion dislocations of the joints, or fractures of the bones. Next, the whole naked frame, excepting the face, should be covered with a bed of snow from 12 to 18 inches in thickness; or, if this cannot be procured, co)d water and ice may be substituted, and cloths successively dipped in it may be spread over the whole body, especially the head and breast. After continuing these affusions, gentle frictions with flannel or soft brushes, likewise im-mersed into cold fluids, should be commenced; alternately making use of the shower-bath, and persevering in these attempts for an hour at least, when the body ought to be left undisturbed for some minutes. If no signs of life appear, clysters of cold water with oil and vinegar, or six ounces of brandy, are to be given, and the former process again and again repeated; so that five or six hours sometimes elapse, before any symptoms of animation are perceptible. As soon, however, as there is the least prospect of recovery, warm fomentations must be resorted to; the degree of fric-tion cautiously increased ; or the patient placed in bed between two robust persons ; emollient clysters prepared ; and, when he is able to swallow, a cup of tea with a little vinegar, wine, or brandy, may be allowed. In many desperate instances, however, it will perhaps •be proper to perform venesection, to introduce air into the lungs by means of common bellows, or those described in p. 190 of this volume ; or to have recourse, to the electrifying machine, or the earth bath, etc. but such cases must be submitted to the judgment of the profession.

The power of cold on vegetables is well known; and, though the frosts of severe winters are on the whole more injurious to vegetation than those of the spring, yet, as the former very seldom occur in this climate, the latter are productive of more extensive damage, because their effects are evident almost every year. - Frosts act most powerfully on ground newly cultivated, on account of the vapours continually ascending from such soil. Trees recently cut, also, suffer more than others from the spring frosts; a circumstance which must be attributed to their shooting forth with greater luxuriance. Hence, likewise, light and sandy soils are thus more frequently damaged than firm and tough land, though both may be equally dry.

As the blossoms of fruit-trees are more particularly affected by early frosts, we shall communicate the following easy and simple methods of securing them:

1. A rope is to be interwoven among the branches of the tree, and one end of it immersed in a pail of water. This rope, it is said, will act as a conductor, and convey the effects of the frost from the tree to the water.

2. According to M. Mallet, the early hoar-frost may be rendered harmless in its effects, by pouring fresh spring-water on the trees and vines thus covered, before the sun rises. - When mist or dew attends a frosty nighty but has not preceded it, Dr. Darwin supposes that a hoar-frost may be less injurious than a black-frost ; because the case of ice on the buds of trees, or on young grass, being instantly produced, covers them with a bad conductor of heat, and prevents them from being exposed to so great cold as is occasioned by the continuance of a black frost, without hoar or rime.

3. An anonymous foreign writer suggests the practice of depriving, towards the latter end of autumn, those fruit-trees of their leaves, which are exposed to the injury of winter-frosts ; and adds, that some, precaution is necessary in this operation, to save the buds which are by Nature destined to unfold in the .succeeding spring, from any external injury. Yet such defoliation ought not to be undertaken with all trees, at the same period of time ; as those which possess a greater abundance of sap, should be allowed to keep their leaves to a later season, than others having a less portion of vegetable juices.

In order to recover and preserve such trees from total decay, as have evidently been injured by severe winter-frost, a correspondent has favoured us with the following easy and expeditious remedy; for the success of which he appeals to his repeated experience : When a tree appears to have suffered from intense cold, he advises to make longitudinal incisions in the bark, extending to the whole length of the trunk, on the north, west, and east sides ; but never in a southern direction. As the east-winds are dry and piercing, very few and super-ficial slits only should be made on that side. This operation ought to be performed in the month of March, before the first sap rises; and repeated in June, while the second sap ascends; but always-so managed, that only the uppermost bark, or epidermis, be di-vided as too deep an incision, though harmless in the spring, might be attended with fatal consequences in the heat of summer. In trees, however, which are thoroughly frozen, it will be useful to make deeper cuts ;. thus to give vent to the stagnant fluids, and promote their circulation. These cuts should be directed against the centre of the tree, drawn in a straight line downwards ; for, in the contrary case, the bark is apt to separate in chinks, afford shelter to vermin, and eventually frustrate the attempt. By a strict adherence to these rules, it will be found that apple-trees, in particular, when slit in every direction (except the south side, retain all their bark ; others, which had undergone one-half of the operation, were but partially preserved ; and such as had received only two cuts, retained only the intermediate portion of the bark, from which they produced new shoots. This simple method is farther attended with the additional benefit that, while contributing to the growth of the tree thus affected, it tends to prevent the decay of those which have in the preceding year been injured by the depredations of caterpillars, and the subsequent stagnation of their fluids.

Although it has been generally believed, that frost meliorates the soil, and especially clay-lands, yet as ice contains no nitrous particles, such improvements can only be of a transitory nature, by enlarging the bulk of some moist soils, and leaving them more porous for some time after the thaw; but, when the water has exhaled, the ground becomes as hard as before, being compressed by the, incumbent weight of the air. - See also Clay, p. 3.

Nor is the salutary influence of frosty seasons, on the health of mankind, in the least confirmed by the annual bills of mortality; as many old and debilitated persons, whose vital heat is insufficient to excite into action their vessels, already too Unsusceptible of irritation, die in consequence of long frosts, during severe winters. Birds, and other wild animals, as well as tender Vegetables, perish benumbed from the same cause. - It deserves, however, to be remarked, that a sharp dry frost does not affect the human skin with that sensation of chilly and piercing cold which we experience, when the air is loaded with moisture, the temperature of which is near the freezing point. This remarkable difference arises from the intense degree of cold produced by the evaporation of fluids (see p. 236), Which continually takes place on the surface of living bodies, where it naturally produces a more perceptible effect, than the simple contact of dry air Would occasion, when it is but a few degrees below freezing. To the young and robust, therefore, frost is more pleasing than moist air ; as, in the former, they are able to keep themselves warm by increased exercise; which, in the latter, only tends to promote and render the evaporation more severely felt on the skin. For the same reason, Dr. Darwin observes, severe and continued frosts "destroy the children of the poor, who want both food, fire, and clothing in this harsh climate."

To preserve vegetable roots, as well as fruit, from the effect of cold, the following directions will be sufficient: Dry sand, and cut straw, are eminently adapted to "that purpose. Potatoes, turnips, onions, etc. should be loosely placed on sand, either under or above ground, and slightly covered with cut straw or chaff; but carrots and parsnips, we are informed, may be kept during the whole winter, by placing them in rows or heaps, so that their tops project at the sides, being the reverse of the method followed with turnips when packed in carts. - See also Apples, vol. i. p. 89.

If, notwithstanding these pre-cautions, vegetables should be injured by the frost, it will be advisable, especially with frozen pota-toes, to immerse them in cold water for a short time, on the approach of a thaw. By this expedient, the frosty particles are gra-dually extracted, and the vegetating principle is preserved, after the severest season.

On the other hand, art intense degree of cold is also attended with some good effects. Thus, aroma-tic spirits possess a weaker flavour when newly distilled, than after they have been kept six or seven months, especially during the win-ter season. Experience has evinced, that this favourable change was produced only by the influence of cold; and M. Baume found, that by immersing quart-bottles filled with liquors, into a mixture of pounded ice and sea-salt, for six or eight hours, the spirit proves as grateful to the palate as that which had been kept for several years.— Geoffroy remarks, that simple waters also acquire a more agreeable flavour, after having been for some time exposed to the effects of cold. - See likewise Vinegar.

Frost. - In the " Giornale Encyclopaedico" of Vicenza, M. De Sax MaRtino recommends the following expedient for preserving trees from the injurious effects of frost. This desirable object is accomplished by depriving those trees, which in cold climates require to be protected, of their leaves, at a period somewhat earlier than their natural decay in autumn. The sap will, consequently, be less copious in .th els, and will circulate more slowly, while it becomes thicker; so that it will not freeze so readily; and, even if it should congeal, its volume will not be so much enlarged as if it were in a more diluted state. In adopting such expedient, however, it ought to be observed, that the leaves must be plucked gradually, at three or four different periods, so that the trees may be divested of their' foliage before the usual time of its falling ; for, if the whole were suddenly removed, the circulation of the sap would be checked, and the tree would probably perish.