AQUA - WATER, H1O,=18.

Pure natural water is a limpid, colorless fluid, free from taste or odor. When evaporated, it should leave no residue. In the Pharmacopoeia it occurs as "aqua destillata - distilled water," but ordinary water is much more extensively used in practice.

Absorption And Elimination

Water is readily absorbed into the blood, and especially so if the normal systemic amount has been temporarily lessened by excessive excretion of urine, perspiration, hemorrhage, etc. When the system already contains a normal amount, then an extra quantity is less readily taken up. Elimination occurs by the kidneys, the intestines, the skin, and the lungs, and of any given portion it is commonly completed within six hours, though during strong exercise the muscles retain liquid for a longer time. Of that taken, the greater part passes out by the kidneys, augmenting their functional activity and carrying off a proportionately increased amount of urea, phosphoric acid, and sodium chloride. If the extra quantity of water taken be within moderate limits the increased elimination is accompanied or soon followed by increased absorption.

Physiological Action (External)

This varies much according to the form of application, whether in large or small quantity, by douching, immersion, or wet sheets, etc.; and again according to the temperature, cold, tepid, or warm, and according to the shorter or longer time during which the patient is exposed to it. It is desirable, therefore, to consider, in some detail, the different modes of its application.