4. Something unsubstantial, fleeting, or transitory; unreal fancy; vain
imagination; idle talk; boasting.
For what is your life? It is even a vapor, that appeareth for a little
time, and then vanisheth away.
James iv. 14.
5. pl. An old name for hypochondria, or melancholy; the blues. "A fit
of vapors." Pope.
6. (Pharm.) A medicinal agent designed for administration in the form
of inhaled vapor. Brit. Pharm.
Vapor bath. (a) A bath in vapor; the application of vapor to the body,
or part of it, in a close place; also, the place itself. (b) (Chem.) A
small metallic drying oven, usually of copper, for drying and heating
filter papers, precipitates, etc.; — called also air bath. A modified
form is provided with a jacket in the outside partition for holding
water, or other volatile liquid, by which the temperature may be
limited exactly to the required degree. — Vapor burner, a burner for
burning a vaporized hydrocarbon. — Vapor density (Chem.), the relative
weight of gases and vapors as compared with some specific standard,
usually hydrogen, but sometimes air. The vapor density of gases and
vaporizable substances as compared with hydrogen, when multiplied by
two, or when compared with air and multiplied by 28.8, gives the
molecular weight. — Vapor engine, an engine worked by the expansive
force of a vapor, esp. a vapor other than steam.
Va"por, v. i. [imp. & p. p. Vapored (?); p. pr. & vb. n. Vaporing.]
[From Vapor, n.: cf. L. vaporare.] [Written also vapour.]
1. To pass off in fumes, or as a moist, floating substance, whether
visible or invisible, to steam; to be exhaled; to evaporate.