Note 45 — MINERALS. (continued 3)

Hydrogen, as its name imports, is a principal constituent part of water; for, singular as it may appear, that well-known fluid is formed by a combination of two species of air or gas, called hydrogen and oxygen (21), and in the proportion of about fifteen parts of the former and eighty-five parts of the latter. This gas had formerly the denomination of inflammable air, and has long been known in mines under the name of fire-damp. It is about twelve times lighter than atmospheric air. When pure it soon destroys such animals, and extinguishes all such flaming substances, as are immersed in it. Mixed with atmospheric air, it explodes with great violence on the application of any ignited body.