Thirst (Cause Of). Intense thirst is said to be caused by the extreme dryness of the air when the temperature is low. In this state it abstracts nets a large amount of m ture from the human body. The soft and extensive surface which the lungs expose twenty-fire times or oftener every minute nearly two hundred cubic inches of dry air, must yield a quantity of vapour which one can hardly spare with impunity. The hu-man skin throughout its whole extent, even where it was brought to the hardness of horn, as well as the softest and most delicate parts, is continually exhaling vapour, and this exhalation creates in due proportion a demand for water. Let a person but examine the de of his boots after a walk in the open air at a low temperature, and the accumulation of condensed vapour which he finds there will convince him of the active state of the skin. In cold countries, the stockings have been found adhering to the soles of the boots after a walk of a few hours. The hoar frost and snow which they contained could not have been there by any other means except exhalation from the skin.