Emily Dickinson Lexicon

VOL'A-TILE, a. [Fr. from L. volatilis, from volo, to fly.]

1. Flying; passing through the air on wings, or by the buoyant force of the atmosphere.
2. Having the power to fly; as, birds are volatile animals. – Ray. Bacon.
3. Capable of wasting away, or of easily passing into the aeriform state. Thus substances which affect the smell with pungent or fragrant odors, as musk, hartshorn, and essential oils, are called volatile substances, because they waste away on exposure to the atmosphere. Alcohol and ether are called volatile liquids for a similar reason, and because they easily pass into the state of vapor on the application of heat. On the contrary, gold is a fixed substance because it does not suffer waste, even when exposed to the heat of a furnace; and oils are called fixed, when they do not evaporate on simple exposure to the atmosphere.
4. Lively; gay full of spirit; airy; hence, fickle; apt to change; as, a volatile temper. – Watts. You are as giddy and volatile as ever. – Swift. Volatile alkali, an old name of ammonia.