If we get very warm, or if we run or work very hard, the skin becomes wet with sweat.

In a little while, if we stop to rest, the sweat is all gone.

What becomes of it?
You say it dries up, which means that it has passed off into the air.

Sweating is going on all the time, but we do not sweat so much when we are quiet and are not too warm, and so the sweat dries up as fast as it is produced, and we do not see it.

Nearly a quart of sweat escapes from the skin daily.
(2) _Breathing through the Skin._--We breathe to a slight extent through the skin.