the termination of the arteries in the various glands. After this secretion
the blood loses its florid colour, which it regains in its passage through
the lungs; which evinces that something besides water is secreted on the
skins of animals.

No statical experiments can ascertain the quantity of our perspiration; as
a continued absorption of the moisture of the atmosphere exists at the same
time both by the cutaneous and pulmonary lymphatics.

3. Every gland is capable of being excited into greater exertions by an
appropriated stimulus applied either by its mixture with the blood
immediately to the secerning vessel, or applied externally to its excretory
duct. Thus mercury internally promotes an increased salivation, and
pyrethrum externally applied to the excretory ducts of the salival glands.
Aloes stimulate the rectum internally mixed with the circulating blood; and
sea-salt by injection externally. Now as the capillaries, which secrete the
perspirable matter, lie near the surface of the body, the application of
external heat acts immediately on their excretory ducts, and promotes
perspiration; internally those drugs which possess a fragrant essential
oil, or spiritus rector, produce this effect, as the aromatic vegetables,
of which the number is very great.

4. It must be remembered, that a due quantity of some aqueous vehicle must
be given to support this evacuation; otherwise a burning heat without much
visible sweat must be the consequence. When the skin acquires a degree of
heat much above 108, as appears by Dr. Alexander's experiments, no visible
sweat is produced; which is owing to the great heat of the skin evaporating
it as hastily, as it is secreted; and, where the sweat is secreted in
abundance, its evaporation cannot carry off the exuberant heat, like the
vapour of boiling water; because a great part of it is wiped off, or
absorbed by the bed-clothes; or the air about the patient is not changed
sufficiently often, as it becomes saturated with the perspirable matter.
And hence it is probable, that the waste of perspirable matter is as great,
or greater, when the skin is hot and dry, as when it stands in drops on the
skin; as appears from the inextinguishable thirst.

Hence Dr. Alexander found, that when the heat of the body was greater than
108, nothing produced sweats but repeated draughts of cold water; and of
warm fluids, when the heat was much below that degree. And that cold water
which procured sw