ore solid
parts of the food, after the lacteals have drawn off the chyle. In
addition to these organs, the skin has a similar duty to perform; and as
it has so much larger a supply of blood, it is the chief organ in
relieving the body of the useless and noxious parts of the materials
which are taken for food.

Various experiments show, that not less than a pound and four ounces of
waste matter is thrown off by the skin every twenty-four hours. This is
according to the lowest calculation. Most of those, who have made
experiments to ascertain the quantity, represent it as much greater; and
all agree, that the skin throws off more redundant matter from the body,
than the whole of the other organs together. In the ordinary state of
the skin, even when there is no apparent perspiration, it is constantly
exhaling waste matter, in a form which is called _insensible
perspiration_, because it cannot be perceived by the senses. A very cool
mirror, brought suddenly near to the skin, will be covered, in that
part, with a moisture, which is this effluvium thus made visible. When
heat or exercise excites the skin, this perspiration is increased, so as
to be apparent to the senses. This shows the reason why it is so
important frequently to wash the entire surface of the body. If this be
neglected, the pores of the skin are closed by the waste matter thrown
from the body, and by small particles of the thin scarfskin, so that it
cannot properly perform its duties. In this way, the other organs are
made to work harder, in order to perform the labor the skin would
otherwise accomplish, and thus the lungs and bowels are often
essentially weakened.

Another office of the skin, is, to regulate the heat of the body. The
action of the internal organs is constantly generating heat; and the
faster the blood circulates, the greater is the heat evolved. The
perspiration of the skin serves to reduce and regulate this heat. For,
whenever any liquid changes to a vapor, it absorbs heat from whatever is
nearest to it. The faster the blood flows, the more perspiration is
evolved. This bedews the skin with a liquid, which the heat of the body
turns to a vapor; and in this change, that heat is absorbed. When a
fever takes place, this perspiration ceases, and the body is afflicted
with heat. Insensible perspiration is most abundant during sleep, after
eating, and when friction is applied to the skin. Perspiration is
performed by the terminations of minut