Note 20 — MINERALS.
Reading edition
Fluids are of two kinds: one of these, called liquids, have, when at rest, a smooth and distinct surface, and are distinguishable both by the sight and touch; the other, denominated gas, or gaseous fluids, have the appearance of air, and are not perceptible either to the sight or touch, except under certain circumstances. The latter are principally oxygen (21), azote or nitrogen, and hydrogen (45). We shall at present have occasion to speak only of the first.