e gout and rheumatism, the application of cold air must be of
great service by decreasing the action of the inflamed skin, though the
contrary is too frequently the practice in those diseases. It must be
observed, that for all these purposes the application of it should be
continued a long time, otherwise an increased exertion follows the
temporary torpor, before the disease is destroyed.

3. After immersion in cold water or in cold air the whole system becomes
more exciteable by the natural degree of stimulus, as appears from the
subsequent glow on the skin of people otherwise pale; and even by a degree
of stimulus less than natural, as appears by their becoming warm in a short
time during their continuance in a bath, of about 80 degrees of heat, as in
Buxton bath. See Sect XII. 2. 1. XXXII. 3. 3.

This increased exertion happens to the absorbent vessels more particularly,
as they are first and most affected by these temporary diminutions of heat;
and hence like the medicines, which promote absorption, the cold-bath
contributes to strengthen the constitution, that is to increase its
irritability; for the diseases attended with weakness, as nervous fevers
and hysteric diseases, are shewn in Section XXXII. 2. 1. to proceed from a
want of irritability, not from an excess of it. Hence the digestion is
greater in frosty weather, and the quantity of perspiration. For these
purposes the application of cold must not be continued too long. For in
riding a journey in cold weather, when the feet are long kept too cold, the
digestion is impaired, and cardialgia produced.

4. If the diminution of external heat be too great, produced too hastily,
or continued too long, the torpor of the system either becomes so great,
that the animal ceases to live; or so great an energy of motion or orgasm
of the vessels succeeds, as to produce fever or inflammation. This most
frequently happens after the body has been temporarily heated by exercise,
warm rooms, anger, or intemperance. Hence colds are produced in the
external air by resting after exercise, or by drinking cold water. See
Class I. 2. 2. 1.

Frequent cold immersions harden or invigorate the constitution, which they
effect by habituating the body to bear a diminution of heat on its surface
without being thrown into such extensive torpor or quiescence by the
consent of the vessels of the skin with the pulmonary and glandular system;
as those experience, who frequently use the cold-bat