These may be either local or general. In general baths, the whole of the body excepting the head is exposed to the action of various agents. According to the nature of the agent, baths may be divided as follows:-

I.

Water.

A. Sim ple.

Cold.

(1)

Ordinary full bath.

(2)

Affusions.

(3)

Spray.

(4)

Sitz-bath.

(5)

Foot-bath.

(6)

Cold pack.

(7)

Compresses.

(8)

Douches.

Hot.

(1)

Tepid bath.

(2)

Warm bath.

(3)

Hot bath.

(4)

Hot foot-bath.

(5)

Hot sitz-bath.

B. Medicated.

(1)

Sea-bathing.

(2)

Common saline bath. Artificial sea-water made by dissolving bay-salt in water (1 lb. of salt in 30 gals. of water).

(3)

Carbonic acid and saline.

(4)

Acid bath.

(5)

Alkaline bath.

(6)

Sulphurated bath.

(7)

Mustard bath.

(8)

Pine bath (Fichtennadelbad).

II.Vapour. .

A. Aqueous.

(1)

Simple.

Russian.

Simple vapour.

(2)

Medicated.

Vinegar.

B. Volatilised drugs, e.g. Calomel.

III.

Air. .

Turkish bath.

Cold Bath. - The effect of a bath depends very much upon its temperature.

In a cold bath, the temperature of the water is at or below 70° F.

The first effect of immersion in a cold bath is contraction of the vessels of the skin, accompanied by a feeling of chilliness and perhaps even of shivering. When the water reaches the level of the chest, the respiratory centre becomes reflexly affected, and the respiration becomes gasping.

After a few minutes the cutaneous vessels begin to relax, and the blood returning to the surface warms it. If the person now comes out of the bath, dries quickly and rubs vigorously, the brisk circulation in the skin gives rise to a pleasant feeling of warmth.

The feeling of warmth, or at least of lessened coldness, will occur even if the bath be continued, but the increased circulation in the skin allows the blood to be much more rapidly cooled, and thus the temperature of the body is much more quickly reduced. When the blood which has been thus cooled in the skin returns to the nerve-centres, it appears to stimulate the vasomotor centre and produce a second contraction of the cutaneous vessels, accompanied by a greater and more persistent chilliness than before.

The object of cold baths is usually :- 1st, either to have a tonic and bracing influence on the body; or 2ndly, to abstract heat from the body in cases of fever.

As a tonic the cold bath is often very efficacious, and not only gives a feeling of strength and comfort, but tends to prevent those who take it from catching cold so readily as they might otherwise do. The vessels of the skin are, as has already been mentioned, the regulators of temperature, and contract when they are exposed to cold : thus protecting the internal organs from its chilling influence. But Rosenthal has found that when animals are kept for a long time in a warm chamber, their vessels lose to a great extent their contractile power, and thus the animal becomes much more readily chilled when exposed to cold. Cold baths, by training, as it were, the cutaneous vessels to contract, tend to protect the organism from the injurious effects of accidental exposure. Besides this, however, the stimulation to the circulation which comes as an after-effect, tends to increase both the tissue-change in the body, and the excretion of waste-substances from it. In consequence of this, cold bathing is usually followed by an increased appetite, so that the most favourable conditions for the nutrition of the body are supplied by cold baths, viz. increased supply of food, increased tissue-change, increased excretion of waste.

Cold baths may therefore be looked upon as a most powerful tonic.

But while cold baths are of great use to those with whom they agree, they may be productive of great harm when they are indiscreetly used. As a general rule it may be said that when they cause much discomfort during the bath, and especially if they cause chilliness afterwards, not removed by brisk friction, they do harm rather than good. This is more especially the case with children and with persons of feeble circulation.

Rosenthal's experiments, already quoted, show us that there is a scientific basis for the popular notion of 'hardening' by exposure. But this process may be carried much too far, and instead of getting excitement of the circulation with all its attendant advantages, the effect of the bath may be to lower the temperature, depress the circulation, and greatly injure the nutrition. The risk of such injury may be much diminished by proper attention to the mode of giving the bath. In children or delicate persons it is better, as a rule, to avoid immersing the whole body, and especially to avoid putting the feet in cold water at the same time as the body. The best way is to let the person sit down in a sitz-bath with the feet out and quickly to dash the water over the face, chest, back, and arms. Then a large bath sheet is to be thrown around the body so as completely to envelope it, and to prevent its being chilled during the process of drying. For during the exposure of the body while the surface is still wet, the chilling process is going on by evaporation during summer, and by conduction by the cold air in winter. This may be seen markedly in persons of a feeble circulation who rise from the bath with a feeling of slight glow, but lose it completely and begin to feel chilly, if the process of drying is delayed. Instead of a bath sheet, a dressing-gown made of towelling may be used. For very delicate persons the water of the bath should be rendered tepid by the addition of a little hot water, and the face may not be sponged until after the rest of the body has been dried and the clothes put on. In winter the temperature of the room must not be too low; it is best, therefore, for delicate persons to take a slightly tepid bath before a fire. Tolerance to cold is moreover often established by gradually reducing the temperature of the water in successive baths, care being taken that no feeling of chilliness supervenes.

Sometimes the vigorous use of a flesh-brush over the chest tends to assist the reaction, and, if practicable, a short though brisk walk is advisable just after the bath. It must not, however, be long, as otherwise exhaustion might set in, and the appetite instead of being increased would be diminished.

Besides the tonic action which cold baths exert on the circulation and on the body -generally, they appear to have a beneficial action in certain disturbances of the respiration.

The respiratory centre (p. 241) may be strongly affected re-flexly by cold applied to the surface of the chest, as is shown by the gasping breathing, or inspiratory tetanus, observed when the cold water reaches the chest on walking slowly into it. In children suffering from broncho-pneumonia the severe attacks of dyspnoea which sometimes occur are relieved by a momentary immersion in water at a temperature of 60° F.