or Volcano, in natural history, a burning mountain, or one that vomits forth fire, flame, ashes, cinders, &c.

As to the cause of volcanos, it is found by experience, that there are several inflammable bodies, which, being mixed together in due proportion, will kindle into flame by fermentation alone, without the help of any fiery particles. Thus M. Lemery having covered up in the earth about fifty pounds of a mixture, composed of equal parts of sulphur and filings of iron, tempered with water; after eight or nine hours time, the earth where it lay vomited up flames. From this experiment we see the true cause of the fire of Ætna, Vesuvius, and other burning mountains, which probably are made up of sulphur and some other matter proper to ferment with it, and take fire.