Artificial mineral waters are certainly not the same in effect as natural ones and probably not in composition. The latter contain traces of mineral matter which may help to make them more efficient. Moreover, they are formed under pressure and contain double salts. The difference in their physiologic effect is typified by the fact that more mineral matter is absorbed from them in a given time than from those artificially mineralized and water artificially charged with carbon dioxid gives off the gas much more rapidly than does that which is charged naturally. In the latter the gas is probably in loose combination which causes its slower escape and its less violent ebullition.

Spring waters vary greatly in the degree of concentration of their mineral ingredients and in the relative amounts of them. The analyses of two waters may be alike in their ingredients and not very different in relative proportion of each, but one may contain twice or several times the amount of mineral matter that the other does. Moreover, the analyses of spring-waters vary a little from time to time but chiefly in the degree of concentration of the mineral matter in them.

Spring waters are classified by their predominating ingredients for they often contain other ingredients which, if they occurred in large instead of small quantities, would change the position of these waters in the classification usually adopted. The following is the best classification and is based on their chemical composition:

Class I. - Alkaline: contains alkaline carbonates chiefly.

Class II. - Alkaline-Saline; contains in approximately equal quantities carbonates and chlorides.

Class III. - Saline: contains chlorides in largest quantity.

Class IV. - Chalybeate: contains salts of iron.

A water in either of these may be described as sulphated or muriated according as sulphates or chlorides are next in degree of concentration to the predominant salt. They may also be either hot or cold and gaseous or plain. The gas in them may be carbon dioxid or sulphureted hydrogen. All of these variations change the therapeutic properties of springs. For instance, much of sulphates in an alkaline water may make it purgative. A hot water is more soothing than a cold one. It often lessens peristaltic activity and the rapid formation of gastric secretions. However, these effects are not very marked when water is drunk for it is so quickly reduced to body temperature. But cold water does stimulate the secretion of gastric juice.

Carbon dioxide gas makes a table water more agreeable both to the eye and to the taste. It aids digestion by promoting chemical changes and muscular activity. It is also somewhat more rapidly absorbed than plain water. However, it should not be given to persons who are cyanotic or to those whose stomachs are dilated or to those whose hearts are weak and easily influenced in rate and regularity by gastric distention. Sulphureted hydrogen gas is not usually an active therapeutic factor in mineral water. It may be beneficial in catarrhal and in mild suppurative disorders of mucous membranes. Usually salts in solution in these waters are the most active therapeutic agents.

The alkaline waters neutralize acids in the stomach, stimulate a more liquid and less mucous secretion from various mucous membranes, makes alkaline the urine and increases its amount. They are useful in catarrhal inflammation of the gastrointestinal, biliary, respiratory and urinary tracts. The simple alkaline waters are used almost exclusively to neutralize acids in the stomach and to stimulate diuresis. When the chlorides appear in them in considerable quantity they become better solvents and diluents of mucus, and when the sulphates also occur in them in notable amounts they become mildly laxative. The latter are especially useful in gastro-intestinal catarrhs, gastric ulcer, catarrhal jaundice, congestion of the liver, cholelithiasis, gout and renal lithiasis. The following well-known waters may be regarded as types of the groups of acidulous waters or of those containing carbon dioxide:

In saline spring waters chlorides or sulphates predominate sometimes together though often separately. In the chloride group of waters sodium chloride predominates but many other chlorides are commonly present in varying amounts. Bromine and iodin are sometimes present in these waters, usually in amounts so small as to make their therapeutic value doubtful but, when relatively abundant, the waters containing them have been found beneficial for the scrofulous and the syphilitic.

The chlorides stimulate gastric, hepatic, intestinal and renal secretions. The waters containing them have been found beneficial in chronic gastritis especially of the mild type and often in exacerbation of the alcoholic type. When spring waters contain these ingredients in considerable quantity they are mildly aperient. They are preferred to the bitter waters in the portal congestion of thin people who cannot stand much reduction in weight. They are also often prescribed as an expectorant by those having chronic bronchitis.

The bitter waters contain magnesium sulphate or sodium sulphate or both in large quantity. When these waters are concentrated they are vigorous purgatives. They also stimulate the secretion of bile and urine. Therefore they are beneficial in cases of chronic constipation in which there is enlargement of the liver and often a subicteric staining of the conjunctiva and skin. The presence of chlorides and alkalies make some of this group of waters more beneficial. Sulphureted hydrogen exists in many of these spring waters. When the mineral matter is at all concentrated in them they are bitter and sometimes nauseous. This necessarily limits their usefulness.

The following are among the well-known chlorid saline springs: Eureka Springs, California; Magnetic Mineral Spring,

Indiana; Blue Lick, Kentucky; Mount Clemans, Michigan; Congress, Saratoga; Glenwood, Colorado; Harrowgate, England; Baden Baden, Hamburg and Wiesbaden, Germany; and among the well-known sulphate saline springs are: Crab Orchard, Kentucky; Bedford Springs; Apenta; Hunyadi Janos and Kissingen.

The chalybeate springs contain iron in the form of bicarbonate, oxide, sulphate or chlorid. Of these the first, especially if it is combined with other carbonates and contains carbon dioxid, is the best and most agreeable to take. The fact that only small amounts of iron are contained in these waters does not make them less useful in the treatment of anemias. The springs which contain iron in the form of sulphates often also contain alum and arsenic and are particularly useful in diarrheas and in the anemias due to them. Usually these waters must be drunk in small amounts otherwise they will produce indigestion. Franzenbad, Richfield, Cresson and Rawley, Virginia, are types of the carbonated chalybeate springs. Sharon chalybeate and Bedford alum are types of the sulphated alum group.

As the active ingredients of waters vary in amount in different springs the quantity to be drunk varies at each and also varies with the nature of each patient's disorder. Spring waters to be effective therapeutic agents must be given with the same care and judgment as other medicine.

When properly used and especially when drunk at the spring, mineral waters will be found to be most important remedial agents and ought not to be neglected.