. The cold bath is that which possesses the ordinary temperature of the atmosphere in the temperate cli mates, varying from 32° to about G5° of Fahrenheit's thermometer. Between these degrees we may estimate the temperature of most of the natural waters em ployed for bathing. The -water-of pools-and small rivers, indeed, sometimes exceeds 6.5• ; while that of the sea in this climate seldom falls below 90°, an i that of most springs in this country has generally a tem perature of about •5°. It has been affirmed, that the water of springs that are inclosed' for the purposes cf private bathing iscolder than that of open springs. We doubt whether this he a fact ascertained by actual ex periment, and suspect the observation to have aris'n from the fallacious circumstance of relative sensation. The principal natural springs employed for cold hi thing in 'this country, are those of the Malvern hills in Worcestershire.
The tepid or temperate bath, is variously. defined ' by authors. Dr Saunderst fixes the medium temper ature of what he calls the tepid bath, at 90° ; • while Marcard t denominates a bath cool, when its tem perature lies between 65° and-85° ; and some of his commentators chuse to denominate baths within this range tepid.. Perhaps they may more properly be called temperate; and the term tepid, which can chiefly apply only to the highest extreme of this range, might be omitted altogether. The temperate bath is usually but there are several natural springs of celebrity, which possess a temperature be tween 65° and 85°, and are employed as temperate, or tepid baths. Such are the springs at Matlock:, Buxton, and Bristol hot wells in England. Of these, the coolest is Matlock, whose temperature does not exceed G6°; while that of Bristol is 71-°, and Buxton is as high as 82°.
The warm bath, according to Marcard, is that whose temperature varies from 85° to 97° ; while Dr Saunders ranks under this denomination all baths whose temperature exceeds 90°. We prefer the former definition ; for, as we shall show immediately, the effects of a bath below 98° are so very different from those of baths above that temperature, as to re quire an accurate discrimination. We do not know any mineral spring in this. country that can be said to come under the present variety, though Bristol hot well has been remarked as high as 81°, and the Cross-bath at Bath is sometimes as low as 9.1°, or even 92°. On the continent there are several baths of this description, but the most celebrated is that of Pyrmont.
When baths exceed the ordinary temperature of the human body, or 98°, they are denominated hot baths. It is 'scarcely possible to assign the utmost
limit of these baths in point of heat, as this must de pend much on the sensations of the patients. An ar tificial hot•bath seldom exceeds 105°, but the heat of some natural springs used for hot bathing is very considerable. Thus the waters of the King's bath at Bath are, at a medium, 116° ; those of Vichy 120° ; of Barege 1'22°; of Borset; in Germany, 132°; of Aix-la-Chapelle about 1.10° ; while those of the Ca roline baths at Carlsbad, in Bohemia, are as high as 165'. The. heat.of the baths at Baden, in Switzer land, is also very great ; but those of Pisa, in Italy, do not exceed and are, we believe, the coolest of the natural hut baths.
The vapour bath is a modification of the hot bath, and will be considered presently.
According to the mode in which baths are em ployed, they are usually distinguished into general and partial; and of these there are several varieties. The term bathing is most strictly applicable to those cases where the whole body is plunged or immersed in the water. This is the ordinary mode of employ ing both the cold and warm baths ; but frequently the water is thrown over the body, either from a bucket, or by means of an apparatus which causes it to descend on the head in a shower, constituting what is called the shower-bath. This method is by medi cal writers termed eitsion, and is practised both with cold and tepid water with the best effects. See AFFUsION and MEDICINE.
When the feet are immersed in warm, or tepid wa ter, the bath employed is professionally called pedi luvium ; and when the lower half of the body is im mersed in a similar bath, this is denominated semicu pium.
The vapour bath may be employed either-univer sally or partially. It consists in the application of steam, brought by pipes from a vessel of boiling water, and either admitted to the whole body, placed in a chamber for that purpose, or to any particular limb, inclosed within a proper apparatus. Sometimes this consists of a close box, made of tin-plate, com municating with a common boiler, or kettle, by means of a tin tube, proceeding from a head resem bling that of a still ; but, in particular cases, the box has adapted to it an air-pump, for the purpose of ex hausting or rarefying the air of the vessel before or after admitting the steam. See Blegborough's Ac count of the Air•unip Vapour Bath ; and Edinburgh Medical and Surgical Journal, vol. vi. p. 313.