Chilblains consist of a peculiar inflammation of the skin of parts exposed to sudden alternations of temperature. They occur on the nose, ears, hands, but most frequently on the feet. The reason why they occur more frequently on the bands and feet is, because persons are apt, directly they come in from the frosty air, to warm those parts at the fire. The face does not get warmed in the same manner, or its skin would be equally liable to chilblains.

In this inflammation, which constitutes chilblains, the sides of the small bloodvessels become paralyzed, and losing their contractility, are dilated by the pressure of the blood within them. If the inflammation be not abated, that is to say, if the little blood-vessels are not restored to their original size, and to their natural contractility, they burst, and matter will be formed, or mortification may ensue. This contractility depends upon proper nervous action in those small fibres which give life to the sides of the hair-like vessels, or small blood pipes. Any sudden shock of cold or heat deprives, these nerves of their power, and induces a local paralysis. The change from cold to heat oftener produces this shock than that from heat to cold ; but either sudden alternation will produce chilblain. It need hardly be said that the nerves of persons in low states of health, persons of scrofulous habits, and young persons in whom the tissues are delicate, are more liable to be locally paralyzed, in the manner described, than those persons of robust constitution having a large quantity of vitality to resist such attacks. Hence we find such invalids, scrofulous persons, and children, more liable to chilblains than others. The liability to chilblain is often an indication of a low state of health, and want of healthy vital action in the system.

When the nature of chilblain is understood, the mode of prevention will be at once perceived, viz, - 1st, .0 protect the parts most liable to the attack (hands and feet) from sudden alternations, either from cold to heat, or from heat to cold. 2udly. To keep the constitution in such a healthy state as to make all parts possess such vitality as to be able to resist slight alternations in temperature.

1. Protection of the Parts. Those substances which are good non-conductors of heat are the best coverings. Woollen stockings or socks, and warm hoots and shoes, come under this category. Light shoes and stockings should be worn in the house, or the feet will become so accustomed to a high temperature that they will be more sensitive to cold. Warm leather gloves, being impervious to wind, are better for the hands than woollen ones, through which the dry frosty air is apt to pierce and chap the hands. Tight wristbands, tight garters, and boots which lace or button tightly about the ankles, must be avoided, because, by preventing the proper circulation of the blood in the hands or feet, they diminish the vitality of the part, and produce an unnatural pressure on the coats or walls of the small blood-vessels. The most frequent cause of chilblain is the warming of numbed hands or feet at the fire. This habit must, of course, be relinquished entirely. Gutta-percha soles, by preventing the wearers from warming their feet at the fire, have saved hundreds from the attacks of chilblains; but such soles should not be worn in the house. After walking in the snow, or in frosty weather, the coverings of the hands and feet should be removed. Dry stockings should be put on after gently rubbing the feet with the pair which has been taken off. The fresh pair must not be warmed. It is well to wear woollen stockings when out, and cotton stockings when in-doors. The use of excessively hot water when the feet are cold, has produced mortification ; but the frequent washing of the feet in tepid water and soap, restores the powers of the nerves in the parts, and renders them less likely to be affected by those alternations of temperature to which they are liable to be exposed.

2. Constitutional Means of Prevention. Persons in robust health are less liable to take infection, suffer less from injuries, and when wounded, are possessed of greater powers of nature for reparation than partial or confirmed invalids. The cold of winter ought to stimulate us to exertion; and exercise is especially necessary to health in winter. Too warm clothing of the body enervates and debilitates; only sufficient clothing, therefore, should be worn. Rooms in winter are often made hotter than the air of summer ; this, and bad ventilation, is another blow to constitutional strength. Enough, however, has been said on this subject to indicate the necessity of general attention to the health in persons who are excessively liable to chilblains.