When poisons or infectious miasmata have been communicated to the animal body, we often find that they lie dormant, till some exciting and generally debilitating cause gives them activity. This renders cold bathing of use during the progress of an epidemic, and it is a valuable part of the prophylaxis. Bathing has been supposed also to prevent hydrophobia; but as few of the animals supposed to be mad are really so, and of those really bitten by mad animals, few are infected, the advantages from bathing are equivocal. If we look into the old authors, we shall find that bathing was employed with considerable severity, and with every circumstance that could agitate the mind and fix the attention. Tulpius, one of the chief advocates for the utility of this remedy, considers the mode of administration to be a very important part of the process; and it may have been so, for modern practitioners have not found it very successful. When narcotic poisons have been swallowed, and tremors, etc. have been produced, cold bathing has been very beneficial. Baccius mentions its efficacy against the poison of the juice of the mandrake. The Indians are recovered from the stupefaction occasioned by the datura, by moistening the soles of their feet with cold water; dogs stupified by the carbonic acid air of the Grotto del Cani, are recovered by being thrown into the neighbouring lake; and sailors recover their intoxicated comrades by a dip in the sea.

The spasmodic and convulsive diseases are relieved by the tonic powers of the cold bath. In chorea, though often used, it is less successful, for reasons hereafter assigned; and in tetanus there is seldom time for the proper action of this remedy, though it has been employed with advantage. That convulsive diseases, when not produced by any direct irritation on a nerve, originate in debility, we trust to be able to prove in another article. See Convulsions.

Sir John Floyer has remarked, that cold bathing is injurious in palsies when the patient is plethoric and feverish. It probably is so whenever any partial plethora or local obstructions exist in any of the more important viscera. Jaundice may perhaps be an exception to this opinion. In the passage of a stone through the gall duct it seems to have been of service; but it was probably in cases where the liver was otherwise sound. In some of the western islands, a patient in the jaundice is laid on his belly, and a pail of cold water unexpectedly thrown on his back, (Smith's Curiosities of Common Water). It is injurious also when the stomach is full, or when the patient has been previously weakened. A ruptured blood vessel, or an incurable obstruction, may be the result of the former error; and in the latter case the constitution may not have sufficient power to restore the determination to the surface. When the body is heated it is also dangerous to bathe, though the young and strong transgress this rule with impunity.

Bathing in the sea is on the whole preferable, as the heat is more uniform. It is, we think, also, perhaps from the agitation of the water, more refreshing. Other causes of preference have been assigned: one is, the greater pressure of the water impregnated with salt; the other, the stimulus of the salt left on the skin. Each may have some effect, and the latter ground of preference is assuredly more certain than the former. We cannot easily conceive how the momentary increase of pressure can have any considerable effect, except by the increase of momentum; and the stay in the sea is too short to expect much advantage from this source. The river water, heated from the vicinity of the shore, is less active than the sea water, whose heat is uniform in summer, and more so in winter; and the sea water, warmed from 75° to 82°, may be an useful bath for invalids preparatory to immersion in the sea. In these baths of a higher temperature the patient should stay a longer time than in the sea or fresh water. It is an observation of Galen, that a more temperate bath is not less useful than a cold one, if the stay be protracted in it.

The shower bath, a modern invention, in which the water falls through numerous apertures on the body, is a remedy much less pleasing, but probably more useful, than the sea or river bath. The cold is greatly increased from the momentum; and, as the water is usu-ally taken from wells, its heat is uniform, about 51° in this climate, the mean of the earth. In winter the river water is much cooler, but generally superior in heat to the air. Bathing, therefore, through the winter is not a practice so severe as may be supposed, except when it is necessary to break the ice. Even then, however, the water below is higher than the freezing point, as its latent heat cannot escape, and the temperature of the air is often far below it.

The time of bathing should be as soon in the spring as settled Weather can be obtained; and, from the long prevalence of easterly winds on the eastern coasts, the southern seem preferable at that time. The most advantageous part of the day is the morning, before breakfast; but, when the weather is not warm, and the patient is much debilitated, it may be proper to begin in the forenoon, after a light and early breakfast. The usual mode of immersion, first plunging the head, is undoubtedly preferable; but if the whole body is very soon immersed, this precision is of little importance. The stay in the bath is of more consequence: many come out after the first immersion, and indeed this is the most common, and often the most advantageous, method. It sometimes happens, however, that the glow is so violent, as to leave in the subsequent part of the day a chilliness; and in such circumstances we have advised a second dipping, which, repressing the too violent determination to the surface, has rendered it more equable and permanent. If any debility arises from staying too long, some warm wine and water, warm tea, or any similar fluid, drunk frequently while the patient is laid between blankets, will relieve it.

It has been supposed that where the fluids are too much attenuated, bathing will be injurious. We have already said that we have scarcely any evidence of this taking place. We know from frequent experience that no such effect is produced by sea water; and if any of the neutral salt were absorbed independent of the fluid, it might produce the effect. Seamen, however, fishermen, and the sea bathers, who are constantly immersed in salt water, never experience any inconvenience from this cause.

One other form of cold bath has been employed, viz. the cold air bath. This consists only in exposing the body for a few minutes to the cold air, partly secured by a loose dressing gown. With prudent precautions this practice may be useful; and even salutary. The effects to be expected must depend on the heat of the atmosphere, and the temperature of the body when exposed to it. Sponging the whole body with cold water is of the greatest consequence, particularly in cases of chronic debility, where the cold bath cannot be obtained, or is from circumstances inadmissible. For the more partial use of cold applications, see 'cold.