The uses of water in health and disease

by John Harvey Kellogg

Effect of Cold upon Temperature.—It was also shown by the same experimenters that the temperature of the body is reduced proportionately with the action of the heart. The natural temperature, as shown by a thermometer placed in the axilla, is 98° F. During and after a cold bath, the thermometer applied to the same part, indicates from one-half a degree to five or six, or even more, degrees, diminution of temperature. In some cases the temperature continues to fall after the bath. The real temperature is lessened even though the skin may glow, and may seem to possess increased warmth. Cold and heat are, within certain limits, wholly relative terms to the nerves of sensibility. What is warm at one time may be cold at another, though the temperature remains the same. The same temperature may be warm to one hand and cool to the other. Temperature can only be accurately determined by the thermometer.

Rationale of Effects of the Cold Bath.—The manner in which the cold bath produces the sedative effects noted, is apparently simple. When applied locally, to a single organ or part, it diminishes the circulation in the part by occasioning contraction of the muscular coats of the arterioles, or small arteries. Their caliber being thus lessened, they of course allow the passage of less blood, and the circulation in the part is diminished. There are, then, three causes for the decrease of heat; viz.,—

1. A portion of the heat of any part is brought to it by the blood; the supply of blood being lessened, the heat is diminished;

2. Heat is produced by vital or chemical changes which occur in the capillaries or their immediate vicinity. These depend chiefly upon the supply of oxygen, which, again, is largely regulated by the blood supply; and it being lessened with the blood, the amount of heat produced is diminished.

3. The water in contact with the part, being of a lower temperature, abstracts heat from it as it would from any other body of a higher temperature than itself.

When the application of cold water is more general, being made to the whole body, or to a considerable portion of it, the same effects are produced on a larger scale. A large proportion of the small arteries of the body, being brought under the influence of cold, are made to contract, thus directly lessening the circulation, and so diminishing, also, the production of heat. Through the sympathetic system, the same effect produced upon the small arteries is produced also upon the heart, lessening the rapidity of its contractions. Again, it has been satisfactorily shown that the action of the heart is largely controlled by the action of the small arteries; so that we have abundant explanation of the decrease in the rate of pulsation. Finally, we have a cold fluid in contact with a large portion of the body, abstracting heat by conduction, as well as lessening its production.

Thus we see that water, when applied at a proper temperature, is one of the most powerful means of depressing the vital activities of the body, diminishing circulation and animal heat as will no other agent. The several modes for applying it are considered in another portion of this work.

The Hot Bath.—We shall include under this head applications of a temperature above 98° F., the mean temperature of the body. As with the cold bath, the effects differ greatly according as the application is brief or prolonged. Local and general applications also differ in their effects.

A brief local application causes an increase in the circulation of a part which very closely resembles, perhaps is identical with, active congestion. The small arteries are distended, and the vital activities and heat of the part are increased. The several effects seem to be little different from those resulting from the application of a mild sinapism. The action of the vital instincts is defensive in both cases.

When applied to special organs, special effects are produced. For instance, a hot fomentation applied to the head for a few minutes will usually produce drowsiness by diversion of a portion of the blood supply of the brain to the skull and scalp. Prolonged applications produce a more or less permanent relaxation of the blood-vessels, and consequent congestion.