The applications of water in the treatment of disease are numerous and important.

In tonsillitis, diphtheria, and croup, ice held in the mouth and allowed to come in contact with the fauces is extremely serviceable. The wet-pack to the neck gives great relief in the same diseases. The mode of applying it is as follows: A napkin is wrung out in iced or cold water and wrapped around the neck; and over this is put a dry towel or napkin to prevent evaporation, and also the wetting of the patient's clothes. In spasmodic croup {laryngismus stridulus) the application of iced water in this way will frequently very quickly stop the crowing inspiration and allay the distress of breathing. A cold douche will effect the same result, but this is an unnecessarily harsh remedy in these cases. Sometimes hot applications are more efficacious, when the napkin or towel may be wrung out in water as hot as can be borne. Cold affusion, or, better, sponging of the body with cold water, is an excellent means of preventing laryngismus stridulus when it arises from cold.

Habitual constipation may sometimes be overcome by a glass of cold water taken before breakfast. Haemorrhoids that bleed, especially when attended by constipation, are improved by a daily rectal injection of cold water. When cold or warm water injections are used to cause an evacuation, it must be remembered that, usually in adults, a large amount of water is necessary—about one quart. A small quantity of iced water may be effective, for in this case the impression of the cold on the nerves of the rectum excites a reflex action of the whole intestinal canal.

Pure water or distilled water is an effective diuretic, especially adapted to the relief of acute desquamative nephritis. The action consists in free discharge of the surplus water by the kidneys, and the, consequent washing out of the tubules obstructed by the cast-off epithelium and tube-casts. Large draughts of water, as has already been stated, carry out from the kidneys the products of retrograde metamorphosis, and hence the action is diuretic in the widest sense. The efficiency of many infusions, decoctions, and ptisans, employed in dropsies, is largely due to the amount of water ingested. The internal use of water in kidney-diseases may be supplemented by hot fomentations to the lumbar region. (See article Digitalis.) As irritation of the skin of the back has been shown experimentally to influence the caliber of the renal arterioles, there is sufficient warrant for the practice of applying these fomentations to the lumbar region, when the functional activity of the kidneys is insufficient.

When renal disease is so far advanced that the elimination of urea is seriously hindered, and stupor, somnolence, muscular twitchings, and even convulsions occur, great relief is obtained by exciting free action of the skin by means of the vapor-bath or hot wet-pack, the patient being well enveloped in blankets to favor powerful diaphoresis. The Turkish bath is very serviceable to restore the suppleness of joints and muscles after an attack of acute rheumatism, and chronic muscular rheumatism is benefited by the same means. No permanent good result can be expected from these baths in chronic rheumatic arthritis.

As a means of causing elimination of mineral, poisons, baths are useful. Lead, mercurial, and paludal cachexice, are relieved by the Turkish bath and the wet-pack, and, although these means are insufficient of themselves to effect a cure, they aid very materially the action of other remedies. Increased metamorphosis of tissue and increased excretion are, it will be remembered, constant effects of these baths. If the wet-packing be used, free diaphoresis should be encouraged, by abundant covering and by large draughts of water.

One of the most important recent improvements in therapeutics is the treatment of fevers by cold baths. This is an old expedient, it is true, but it is only within a few years that the treatment of fevers by baths has been placed within the domain of strictly scientific investigation. Various means of applying water in fevers have been resorted to—cold affusion, cold baths, cold wet-pack, ice-bags, etc. Cold affusion consists simply in dashing successive buckets of water over the patient, stripped and lying on a mattress protected by a gum-cloth. The applications are continued until the temperature is reduced. This is a crude method, and wears an aspect of harshness which may prevent its efficient use in private practice. The cold bath is more serviceable, and is free from the objectionable features of cold affusion. As practiced according to the method of Ziemssen, it is grateful to the patient, produces no shock, and exerts a powerful influence over the temperature. The fever-patient is put into a bath about the normal temperature of the body (98° Fahr.), and the water is cooled, by the addition of ice, to 80° Fahr., to 60° Fahr., or even to 40° Fahr., according to the effect produced on the temperature, which, for this purpose, should be taken in the rectum. When a positive reduction of the fever-heat has occurred, at the expiration of five minutes to half an hour usually, or longer if necessary, the patient should be wiped dry, placed in bed, and covered with blankets. The bath may be used, according to the nature of the case, from two to six times each day, but less frequently if the duration be longer than a half-hour. The appliances for administering baths to fever-patients are: A strong sheet for lifting the patient from the bed into the bathtub; a bath-tub provided with an exit-pipe for drawing off the surplus water; a thermometer for ascertaining the temperature of the bath, and a clinical thermometer for noting the variations of temperature of the patient. Hospitals should be provided with such arrangements as have been made at the London Hospital for the use of baths in fever. These consist of a small ward with two beds; a bath-tub supplied with hot and cold water; a tank, with which the cold-water pipe communicates, in which ice may be put if necessary; and a large waste-pipe for disposing quickly of the surplus water.

In the absence of suitable bath appliances, the temperature of fever-patients may be reduced by simpler methods. Iced water may be injected into the rectum frequently; cloths dipped in iced water may be applied to the trunk, and Chapman's ice-bags may be put to the spine. More suitable than these methods is the wet-packing. Although the wet-packing is not so effective as the bath, it is a very powerful means of reducing fever-heat, and it has the merit of simplicity of application, so that in every household it may be used if necessary. The patient may be put into the wet-pack several times each day, according to the state of the temperature, and may remain in it from five minutes to an hour.

If, after the application of water by any of the modes above mentioned, the circulation becomes feeble, the extremities cold, and the lips blue, stimulants should be administered and bottles of hot water applied to the feet. The good effects of baths are these: the temperature declines, the pulse falls and becomes soft and compressible, the skin grows moist, and the patient feels refreshed. The repetition of the bath or of the application of cold water will be determined by the rise of temperature, and of the pulse. Some practitioners employ them regularly, as, for example, Yon Ziemssen and Immerman, who administer them at 6 a. m., 1 to 3 p. m., and 7 p. m. ; but others—and this the author thinks the better plan—give them more or less frequently according to the range of temperature. Not only is the mortality of typhoid greatly less under hydrotherapy than under any other method of treatment, but the complications which belong to it—except haem orrhage—occur less frequently.

The most conspicuous triumph of the water-treatment of the py-rexial state is seen in the management of hyperpyrexia, a condition of things in which a sudden and rapid rise of temperature takes place, the range being in extreme cases from 105° to 112° Fahr. It is now perfectly well known that any temperature above 108° Fahr. is almost necessarily a fatal sign. This condition of hyperpyrexia occurs sometimes in acute rheumatism, delirium tremens, fevers, etc., and has heretofore not been amenable to treatment. A fatal result in these cases may be averted by cold baths, the temperature of the bath being rapidly reduced from 96° to about 60° Fahr., by the addition of ice. It is sometimes necessary in these cases to prolong the stay in the bath to two or three hours, but it must not be forgotten that no absolute rule can be made, the state of the patient's pulse, respiration, and temperature being the guide not only as to the temperature of the bath, but the duration of the stay in it.

Typho-malarial fever is best treated by the same means; but malarial fevers are, of course, so unquestionably remediable by quinine that any other treatment is a waste of time. Baths are, however, extremely grateful in the pyrexial stage of malarial fevers.