This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
The so-called mineral waters are really medicines, largely diluted and complex, containing various salts and gases derived from the soils through which they pass, and administered at varying temperatures, generally warm.
Applied externally in the various forms of bath, they act like the plain water-baths already described, with special powers of stimulating the skin, and indirectly the visceral circulation, or of quickening absorption and lessening pain.
Given internally, they act by promoting tissue-change, secretion, and excretion, thus diluting and depurating the blood, and increasing the bile and other organic liquids. "Critical eruptions and discharges may occur during their administration, but are not advantageous."
Their action is not to be explained solely by the proportion of ingredients recognized by an analysis - e.g., 1 1/2 dr. of magnesia sulphate has far more purgative effect when taken in the form of a natural water than when dispensed by a chemist, and hence, although imitated, they cannot be quite replaced by artificial combinations.
Mineral waters are mainly used in chronic functional disorders, and in conditions of debility and convalescence, but are suitable also for early stages of organic disease. In estimating their effects, allowance must be made for the change of climate and surroundings, and the more regular, simple, and quiet life of a Spa. Hence the drinking of imported waters at home will not give the same result as taking them at their source.
The usual season for drinking the mineral waters includes summer and autumn, i.e., extends from May or June to September or October, and the duration of a course is from three to six weeks. Too prolonged continuance of the treatment is liable to do harm.
It must be recognized that benefit is not derived in proportion to the quantity of water taken: at first only small quantities daily are desirable. Bathing and drinking should not be commenced on the same day. When the strength permits, early rising is advisable, so that the water may be taken before breakfast; it should be sipped slowly, and an interval allowed for a gentle walk between each glass. The diet should be carefully regulated - it is usually less generous abroad than in this country. As a rule, some physician resident at the Spa should be consulted.