Cleanliness is a very important means of health. Some persons in low life, and some foreigners, are practically great lovers of dirt; and at the same time they have good health and sound constitutions: but they are none the better for their filthiness. Their good health may be the result alone of their plain living; while those in higher life,' with all their cleanliness and ventilation, destroy themselves with their luxuries. But when the cholera and other violent epidemics appear, their most fearful footsteps are traced in those districts and families where filth abounds. Every person ought to be accustomed to periodical bathing, or at least to occasional bathing. The pores of the skin are likely to become choked and impervious without it. Without occasional bathing the surface of the body becomes covered with a dirty and offensive substance, which prevents the action of the cutaneous vessels. Washing the surface from such accumulations is very important both for the flavor and the health of the body: for when the skin is thus coated, the whole system is affected by it: the natural exhalations which are adapted to purify the blood and fluids generally, are thrown back upon the system; and some or all of the internal organs become oppressed. Persons having an obstructed skin are more liable to fevers and pestilential diseases. An obstructed skin is frequently produced by a sudden cold; by which the internal system becomes oppressed, and a fever ensues, unless the obstruction be speedily removed. A bath to meet such an emergency is necessary. A warm bath perhaps when the action of the system is feeble, possessing but little power of reaction; but where the system is more vigorous, promising to react so as to bring up a glow of warmth and a gentle perspiration, a cold bath may be the best.

The kind of bath to be used is of some consequence. Sea water may be the best for those in general who have been unaccustomed to the atmosphere of the sea shore. It may be the best for any whose surface is too cold, lax, and flaccid, throwing off perspiration too profusely, or that which is clammy and morbid. Seabathing, cold or warm, as the individual may be able to bear it, accompanied with dry friction, in such cases, may prove very beneficial, A fresh water bath is unquestionably best where a fever, or a tendency to a fever, exists.

A cold or warm bath should be selected in accordance with circumstances and facts relating to the state of general constitution, present strength, or the nature of an existing morbid affection. As before remarked, as a general rule, a warm bath may be the better one when the general strength is too feeble to admit of a reaction of the system under the influence of cold water; while a cold one may be better where a tolerably vigorous habit exists. A cold bath may also be preferable, as a general thing, when resorted to as a luxury, or for the purpose of preserving health. The cold itself is a tonic to the skin, and through the skin, to the entire system: while the general tendency of warm water upon the surface is weakening. When a limb is inflamed, we bathe it freely in warm water to reduce its action; i.e., to weaken the present excited action of its vessels.

The frequency of bathing is a matter of some interest. This depends much upon the constitution, health, habits, and employment of each individual. Those who live on meats and oily substances have much more occasion for frequent baths than those of different habits. If persons would so regulate their habits of living as to keep the fluids of their systems pure, they would have much less occasion for frequent bathing. Hence no specific rule can be given for bathing, either as a preservative, restorative, or a luxury; common sense and circumstances must determine its frequency.

Too frequent bathing, however, is decidedly injurious. Although hundreds perhaps suffer for want of bathing, while one is injured by its frequency, yet there is such a thing as making too free use of a good thing. A person may bathe so often as to materially weaken himself in the course of time. Any one must be very filthy to need a bath every day. And if a bath be used every day by one who only needs one once or twice a week, and this course is persisted in for a great length of time, much damage to the system must accrue. Very many, doubtless, have been greatly injured in this way, though that injury may not have been attributed to such a cause.

Too frequent bathing does injury by stimulating the pores of the skin too much. When the skin acts naturally, it constantly throws off, by insensible perspiration or exhalation, a substance which it is necessary the system should part with for the continuance of life and health. When, from any cause, that exhalation is impeded, the system suffers by being oppressed with that which should be thrown off. But if the skin be made too active, it throws off too much -- more than is required, and more than the system can afford to spare: hence the system is gradually weakened. And though years may pass before this undue waste be perceived, yet it will sooner or later discover itself. Not unfrequently has the writer been called to prescribe for debilitated, rickety children, when little else could or needed to he done except to proscribe the use of too frequent baths and washings. Some mothers are so excessively afraid of their little ones being dirty, they will bathe and wash them several times a day. Such a course is liable to be very disastrous, especially when warm water is used. When children are washed for cleanliness, cold water should be used; but even that should not be applied to the whole body so often as every day, if the strength and health of the child be an object.

A letter has been recently received from the much honored ex-president, John Quincy Adams, answering some inquiries in relation to his experience on bathing, in which he says he has practised it in a variety of forms and ways, "from first to second childhood" -- an "experience during more than three score years and ten." He says, "I continued it until within the last four or five years, when I found it no longer agreeing with my health, but operating rather unfavorably to it. Medical friends, and particularly my very ancient friend, the late Dr. Waterhouse, advised me to disuse it; and my experience confirming his admonitions, I have, with great reluctance, entirely renounced it." He adds, "and I parted from it as from a dear and deeply regretted friend. Though no longer able to enjoy it myself, I can very cheerfully recommend it, not only the practise of bathing, but of swimming, to all my friends under the age when King David could get no heat."

There can be little doubt but that the fascinating luxury of bathing has sometimes led to such an undue use of it, as gradually to waste the physical energies, and induce premature old age. While the system possesses the vigor of youth and manhood, the too great waste of the body can be supplied by its recreative power so effectually that the debilitating effect is not noticed; but when that power of recreation becomes much diminished, the loss becomes more permanent and apparent. Let the young be admonished lest this useful luxury be used intemperately. Other cases have come under observation, where bathing had been extensively practised for years, but as age came on, the system was not able longer to bear the excessive exhalations by insensible perspiration which the practice occasioned.