BATH, Balneum, a convenient receptacle of water for persons to wash or plunge in, either for health or pleasure.—Baths are distinguished into hot and cold; and these again are either natural or artificial. The natural hot baths are formed of the water of hot springs, of which there are many in different parts of the world; especially in those countries where there are or have evidently been volcanoes. The artificial hot baths consist either of water or of some other fluid made hot by art. The cold bath consists of water, either fresh or salt, in its natural degree of heat; or it may be made colder by art, as by a mixture of nitre, sal-ammoniac, &c. The chief hot baths in our country are those of Bath and Bristol, in Somersetshire; and those others of Buxton and Matlock, in Derbyshire; which latter, however, are rather warm or tepid than hot. The use of these baths is found beneficial in diseases of the head, as palsies, &c. in cuticular diseases, as leprosy, &c. obstructions and constipation of the bowels, the scurvy and stone, and in most diseases of women and children. The baths have performed many cures, and are commonly used as a last remedy in obstinate chronic diseases; where they succeed well, if they agree with the constitution of the patient: but whether they will agree or not, cannot be known without trial.
As to the origin of those hot waters, of which the natural hot baths are formed, we are very much in the dark. All that can be affirmed with certainty is, that where there are volcanoes, there also there are hot springs in great abundance; but how the heat of the volcano should be constantly communicated to the waters of a spring for many ages, during a great part of which the volcano itself has lain in a dormant state, seems almost beyond the reach of investigation. Another thing that creates a great difficulty is, that the fire of a volcano must certainly lie very deep in the earth, and most probably shifts from place to place; but the waters of a spring must always issue from a place situated lower than the origin of the spring itself. Besides, though we should suppose the water to come from the top of a volcano itself, and consequently boiling hot, it could not be supposed to percolate far through cold earth, without losing all the heat it acquired from the volcano. From some observations, however,
however, it certainly does appear, that there are some spots on the earth which have a power of producing heat within themselves, independent of any thing foreign; and that water is so far from being able to destroy this power, that it seems rather to promote and continue it. We know that water bath this effect upon a mixture of iron filings and sulphur; but whatever quantities of similar substances we may suppose to be contained in the earth, we must also suppose to be destroyed by one great conflagration soon after they have begun to act upon each other, so that by their means no lasting heat in waters could be produced. Dr Stukeley indeed would solve this, and several other phenomena, by making the fire and smoke of volcanoes the effects of electricity: but here sufficient proof is wanting; for electricity, even in its most powerful state, is not very apt to set bodies on fire. The thought, however, deserves attention; for if electricity is capable of setting a volcano on fire, it is undoubtedly capable of producing solfataras where it meets with proper materials, and from them springs of any degree of heat.
The cold bath is found one of the most universal and innocent remedies yet discovered, though still its use is not to be adopted without precautions.