nature, and of the greatest variety, have been in use from the earliest ages. The best known media are the various mineral waters and sea-water. These, and baths impreg nated with their gases, cannot here be considered in detail ; we can do little more than enumerate a few of the artificial baths. Of baths of mineral substances, those of sand are the oldest and best known ; the practice of arenation or of burying the body in the sand of the sea shore, or in heated sand near some hot spring, is very ancient, as also that of applying heated sand to various parts of the body. Within the last few years establish ments have been introduced into various European cities where hot dry sand is methodically applied. Baths of peat earth are of comparatively recent origin, and are little used out of Germany. The peat earth is carefully pre pared and pulverized, and then worked up with water into a pasty consistence, of which the temperature can be regulated before the patient immerses himself in it.|1}}
There are various baths that may be termed chemical, in which chlorine or nitromuriatic acid is added to the water of the bath, or where fumes of sulphur are made to rise and envelop the body.
Of vegetable baths the number is very large. Leys of wine, in a state of fermentation, have been employed. An immense variety of aromatic herbs have been used to impregnate water with. Of late years fuci or sea-weed have been added to baths, under the idea of conveying into the system the iodine which they contain ; but by far the most popular of all vegetable baths are those made with an extract got by distilling certain varieties of pine leaves. They are pleasant and stimulating.
The strangeness of the baths of animal substances, that have been at various times in use, is such that their employment seems scarcely credible. That baths of milk or of whey might be not unpopular is not surprising, but baths of blood, in some cases even of human blood, have been used ; and baths of horse dung were for many ages in high favour, and were even succeeded for a short time by baths of guano.
Electrical or galvanic baths have been popular of late years, in which galvanic action is communicated to the patient while in baths.
Baths also of compressed air, in which the patient is subjected to the pressure of two or three atmospheres, have been in use at certain places for some years.
A sun bath (insolatio or heliosis), exposing the body to the sun, the head being covered, was a favourite practice among the Greeks and Romans. This list of artificial baths might be readily increased.
We have hitherto spoken of general baths, but there are many varieties of local ones, the use of which has become somewhat more definite than it used to be, before the principles of hydropathy were understood. Some of these are affusion, half-baths, full baths, sitz baths, wave baths, local baths, shower and spray baths, douches, fomentations, injections, wrapping up in the wet sheet. Some of these processes, though by no means of novel origin, require a few words of explanation.
Douches were used by the ancients, and have always been an important mode of applying water to a circum scribed portion of the body. They are, in fact, spouts of water, varying in size and temperature, applied with more or less force for a longer or shorter time against particular parts A douche exercises a certain amount of friction, and a continued impulse on the spot to which it is applied, which stimulate the skin and the parts beneath it, quicken the circulation of the capillaries, and thus favour the absorption of abnormal deposits. It wakes up the slumbering activity of the tissues and helps to remove congestions from the deeper seated organs. The effects of the douche are so powerful that it cannot be applied for a long time continuously. After every two or three minutes there should be an interval in its use. It is obvious that a douche is capable of many local applica tions, on the description of which it is here impossible to enter. Nor need we say that the douche must be used with great care in the case of nervous and excitable people, and better not at all when any irritation or inflammation is present. Douches are invaluable in old neuralgias, in the sequelae of rheumatism, and in thickened joints.
The alternation of hot and cold douches, which for some unknown reason has got the name of Ecossaise, is a very powerful remedy from the strong action and reaction which it produces, and is one of very great value. The shower bath may be regarded as a union of an immense number of fine douches projected on the head and shoulders. It has been long in use in England, and produces a strong effect on the nervous system. An ingenious contrivance for giving circular spray baths, by which water is pro pelled laterally in fine streams against every portion of the surface of the body, is now found in most establishments.
Action of Baths on the Human System.—We shall now inquire shortly into the theory of the operation of the baths and of the bathing processes, of which we have briefly traced the history.
The primary operation of baths is the action of heat and cold on the cutaneous surfaces through the medium of water.
The first purpose of baths is simply that of abstersion and cleanliness, to remove any foreign impurity from the surface, and to prevent the pores from being clogged by their own secretions or by desquamaticns of cuticle. It need scarcely be said that such objects are greatly promoted by the action of the alkali of soaps and by friction ; that the use of warm water, owing to its immediate stimulation of the skin, promotes the separation of sordes; and that the vapour of wafer is still more efficient than water itself.
It has been supposed that water acts on the system by being absorbed through the skin. The question has been frequently discussed; but the great majority of observers believe that, under ordinary circumstances, no water is absorbed, or if any, so minute a quantity that it is not worth considering. And further, as we have alluded to medicated baths, it is proper to say that, according to the latest authorities, no foreign bodies, under the ordinary circumstances of a bath, are absorbed into the system ; although when a portion of skin has been entirely cleared of its sebaceous secretion, it is possible that a strong solution of salts may be partially absorbed. In the case of medicated baths we therefore only look (in addition to the action of heat and cold, or more properly to the abstrac tion or communication and retention of heat) to any stimulant action on the skin which the ingredients of the bath may possess.
The powerful influence of water on the capillaries of the skin, and the mode and extent of that operation, depend primarily on the temperature of the fluid ; for the influence of the mechanical pressure on the body of the water of a bath, which has been calculated at nearly one pound on each square inch of the surface, has never been accurately determined. Baths have therefore to be considered according to their temperature ; and the effects of cold and of hot baths have to be studied. But we may as well first point out one or two general facts. The human system bears changes of temperature of the air much better than changes of the temperature of water. While the temperature of the