The foundation of all those fluids that are to be taken into consideration for our purpose is formed by-one of the most universal elements on our globe - the water.

It is a conditio sine qua non both for building up and preserving the whole organic world. A cell, the most primitive of all living beings, e. g. a bathybius, as well as the most highly developed ones, as we see them in the higher organisms of the vegetable and animal kingdoms, contains water as a fundamental basis. Although there are cells, and groups of them, that may retain vitality for thousands of years, even when in dried-up condition, yet this does not affect the relatively higher developed beings in the least. "Corpora non agunt nisi fluida " is an old chemical rule, and, indeed, stoppage of all functions, or even death, would occur as soon as the necessary water should not be supplied.

Water is indispensable for fulfilling the physical and chemical processes, among which ranks highest the process of diffusion, or the Endosmosis and Exosmosis.

We feel the lack of water involuntarily, and call this feeling "thirst." The inclination of satisfying this feeling by drinking water, or water-containing liquids, is forced upon us by nature. Thus, thirst compels us to drink, and is, therefore, one of these instinctive impulses that, because being life-preserving, are physiologically of the greatest importance.

How we ought to drink, and what, has already been treated upon; it is only left to show what we must not drink. This task will be solved as soon as we have demonstrated what beverages are composed of, and how they are eventually adulterated.

Although such a treatise ought to be of a strictly chemical character, it will still be interesting, both to the public in general and to manufacturers especially. Therefore we add here, in short but distinct outlines, a description of the composition of fluids, their chemical characteristics when pure, and their possible adulterations.