EXHALATION

, a fume or steam Exhaling, or issuing, from a body, and diffusing itself in the atmosphere.

The terms Exhalation and Vapour are often used indifferently; but the more accurate writers distinguish them, appropriating the term Vapour to the moist fumes raised from water and other liquid bodies; and the term Exhalation to the dry ones emitted from solid bodies; as earth, sire, minerals, &c. In this sense, Exhalations are dry and subtle corpuscles, or effluvia, loosened from hard terrestrial bodies, either by the heat of the sun, or the action of the air, or some other cause: being emitted upwards to a certain height in the atmosphere, where, mixing with the vapours, they help to constitute clouds, and return back in dews, mists, rains, &c.

Sir Isaac Newton thinks, that true and permanent air is formed from the Exhalations raised from the hardest and most compact bodies.

EXHAUSTED Receiver, is a glass, or other vessel, applied on the plate of an air-pump, to have the air extracted out of it by the working of the pump.— Things placed in such an Exhausted Receiver, are said to be in vacuo.