treating enteric fever, which consists in the immersion of the patient in a bath of the temperature of about 70° F. as frequently as the fever reaches 102.5° F. The patient should be gently lifted into the tub, and be rubbed thoroughly while in the water to bring the hot blood to the surface. Immediately on his entrance his head should be cooled by a cold douche or by means of an ice-bag. Sometimes a little whiskey or brandy is given before he enters the bath; but, as a rule, the stimulant is best reserved for the time of exit from the tub. The temperature should not be reduced below 100°, as it may continue to fall and the patient go into collapse. After the bath has accomplished its purpose the patient is lifted back on to the bed, is wrapped in a sheet and then in a light blanket, without being dried or rubbed. If the chill is marked, a hot-water bag may be placed at the feet and a half-ounce or thereabouts of whiskey given to him. Often a peaceful sleep follows the bath. In the hands of Brand, the mortality of typhoid fever under this method has only been about 1 per cent. In the hands of others it has been higher, but in nearly every case less than with other plans of treatment.-ED.]

In diseases of the nervous system recourse is had to diverse forms of hydrotherapeutic treatment, according to the end desired; for the alleviation of pain revulsive procedures are especially indicated. In rheumatism hot or mixed applications, often combined with massage, are of undoubted value. The styptic action of cold or the reflex effects engendered by energetic local applications of heat or cold are an important means of controlling hemorrhage. Finally, in the socalled diseases of nutrition, good results are unquestionably obtained by the use of hydrotherapeutic agents.

There are a number of contraindications to the employment of hydrotherapy. As a general rule, the organic diseases, such as pulmonary tuberculosis, general paralysis, diabetes mellitus, Bright's disease, chronic diseases of the heart and the vessels, preclude the use of cold applications. It is true that in the incipient stages of these maladies such applications, particularly of the gentler variety, may be employed; but as soon as there is a state of general debility or of weakness of the circulatory organs the contraindication becomes absolute.

The existence of disease of the skin contraindicates the use of certain special procedures, among them the use of cold water and the sweating by means of the lamp. Baths, simple or medicated, the vapor-bath and the tepid-bath, or the hot douche, are, on the other hand, very useful in certain forms of skin diseases.

ᏢᎪᎡᎢ Ꮩ.

MINERAL WATERS.'

THE custom of spending the summer at a resort possessing a mineral spring is becoming more popular year by year, especially among the dwellers in large cities. This is due in all probability more to a desire to be fashionable than to a real necessity. We do not wish to imply, however, that mineral springs are of doubtful value; indeed, many of them are powerful agents, but it seems to us that their popularity is not entirely due to their therapeutic usefulness.

It is the sufferers from chronic disease and the semi-invalids which find in such resorts a proper and necessary rest from the pressing cares of modern city life. If the place is rightly selected, such persons will be greatly benefited by the treatment; but a mineral spring is a two-edged sword, and it may do harm if not suited to the patient's state of health. Hence it is exceedingly important to have a knowledge of the properties and actions of mineral waters.

The use of mineral waters dates back to ancient times; it was quite prevalent among the Romans, who founded many establishments in Gaul. Nevertheless our knowledge of their medicinal properties is almost entirely modern; yet it is far from complete, and mineral waters still rank among the quasi-mysterious agents.

The action which they produce depends in general upon four factors: (1) Upon their mineralization, or, rather, upon their chemical and physical properties; (2) upon their temperature; (3) upon their mode of employment; and (4) upon the hygienic and adjuvant conditions (especially the climate) of the resort.

We shall briefly study these factors in detail.

Durand-Fardel defines mineral waters as those natural waters employed in medicine by reason of their chemical composition or their temperature. This definition would include ordinary water raised to a certain temperature. Many authors do not agree to

The parts on Thermic Agents and Hydrotherapeutic Measures should be read with this part.

this, but affirm that mineral waters, no matter what their constitution, exert an action which differs from that of the ordinary potable

water.

The point of emergence of mineral springs is extremely variable; it may be in ancient or in recent strata, in crystalline or in sedimentary rocks. Springs are scattered over the entire surface of the globe-in all zones, in all countries.

Those that have a high temperature are generally in the neighborhood of volcanoes; when found in transitional strata they always. issue from granite rocks.

Mineralization. The mineralization or chemical composition of the spring is usually in accord with the nature of the subterranean strata traversed by the water. Such surface-waters as are counted among mineral springs obtain their properties by lixiviation.

The character of the bed of a spring does not always give a clue to its composition, for the same regions may possess waters differing considerably. The bases are derived from the containing strata, but the dissolved acids may have their origin at a remote distance.

Certain waters-several of great importance-are mineralized to a less extent than drinking-water; their specific gravity is scarcely above that of distilled water.

The chemical composition of mineral waters is remarkably constant, although the true composition must still be considered almost unknown. It is customary to make two kinds of analysis. In the one the component elements, or the simple compounds, such as acids and bases, are determined; this is known as the real analysis. In the other, known as the hypothetic analysis, the combinations in which the elements or the acids and bases are supposed to exist, are reconstructed.

The hypothetic analysis cannot be exact, but is valuable from the standpoint of therapeutics, and constitutes the bases of the classification of mineral springs.

According to the Annuaire des Eaux de France, mineral waters contain a small number of acids and bases, which, as a rule, mutually saturate themselves. When the saturation is not complete the acids are present in excess. The acids that may be found are carbonic dioxide, hydrogen sulphide, sulphuric, hydrochloric, hydrobromic, hydriodic, nitric, phosphoric, and arsenious. The first three are most important. Among bases we have sodium, potassium, calcium, magnesium, lithium, and the protoxides of iron and man

ganese. Sodium is present in nearly all mineral waters, generally as the predominant base; potassium very rarely preponderates.

The principal gases are carbonic dioxide, nitrogen, hydrogen, hydrogen sulphide, different forms of carburetted hydrogen, ammonia, and hydrochloric acid gas. The oxygen and a part of the nitrogen are probably derived from the atmosphere. The origin of the others has not been definitely determined.

Certain gases, by reason of their abundance and their influence upon the organism, form important ingredients of mineral waters. Such gases are hydrogen sulphide, carbonic dioxide, and probably also nitrogen. Many gaseous springs contain carbonic dioxide, both in the free and the combined state.

In addition to the commoner substances mentioned above, there are others of much rarer occurrence in mineral waters, as arsenic, salicylic, boric, hydrofluoric acid, aluminium, barium, strontium, copper, nickel, cobalt, titanium, rubidium, cæsium. Organic matters, generally playing the part of acids, may also be present.

Arsenic was discovered by Tripier, in 1889, in the thermal spring of Hammam-Meskoutine, in Algiers.

Since then it has been found in the water of Bourboule, Vichy, Mont-Dore, and others. According to Le Fort, it is derived from arseniferous ferruginous minerals.

Temperature. The temperature of mineral springs varies-some waters are cold, others tepid, and yet others warm; the latter being the so-called thermal springs. It should be noted at this point that the term thermal has a variety of meanings.

The French Annuaire considers a spring to be thermal when its temperature is appreciably above that of the mean annual temperature of its place of emergence.

Filhol applies the word to all springs having a constant temperature. Durand-Fardel makes the same divisions of springs as are made of baths, terming those having a temperature below 68°, cold; those having a temperature of from 68° to 86°, tepid; those the temperature of which is 87° to 96°, hot; and those having a temperature of 97° to 114°, very hot.

An important and interesting fact is the constancy of the temperature of mineral springs. Carrere, in 1754, determined the temperature of the springs in the Pyrenees, and Le Grand, ninety years later, obtained the identical figure.

Springs that have a deep origin are generally warmer than those

coming from near the surface. Solid strata and a rapid flow are factors that favor the conservation of the heat of a spring, while a porous soil or an intercallated lake or expanse of water tend to produce a variable temperature. As a rule, constancy of temperature is associated with the constancy of mineralization.

Unctuosity. Certain mineral springs particularly rich in organic matter have the peculiar property of unctuosity. In sulphur springs possessing this quality, Fontan and others have found various forms of microscopic algae. The one discovered by Fontan, a delicate, filamentous alga, inhabits only sulphur springs having a temperature of 97° to 114°. It contains a small proportion of iodine.

Electric Condition. A number of springs are endowed with active medicinal properties which seem to be entirely independent of their chemical constitution. Scoutteten has proposed the theory that the effects are due to electricity. Gigot-Sward and Armieux have found that in sulphur springs the tension on the surface is positive, in the deeper parts negative. In their opinion the electric condition is due to the incessant modification of the element sulphur. Paul Benard confirms the results of Scoutteten's researches, but declares that there is not any relation between the electric reactions and the therapeutic properties of mineral waters.

Waltenhofen, of Gastein, has carefully compared the conductivity of medicinal waters with that of various potable waters, and has found that the former possess conductivity in a higher degree than ordinary drinking-water.

The data, however, are as yet insufficient to permit us to form any positive conclusions with respect to the part played by the electric phenomena in the therapeutic action of mineral springs. We may state the present status of the question as follows: Certain mineral waters of an indifferent chemical constitution appear to be in a peculiar electric state, by reason of which their influence upon the organism approaches that of the electric bath. In others the electrical condition is susceptible to change during the course of their employment, a peculiarity which endows such springs with properties differing markedly from those possessed by ordinary water.

The greater number of mineral waters undergo changes on exposure to the air: a part of the contained gases is disengaged and some of the salts are deposited. In the incrusting springs these salts are calcium compounds; in others, silica or iron is deposited.

Mud-springs. Mud-springs, the therapeutic value of which is