Physical Dictionary

or

An Attempt at an Explanation of the Most Important Concepts and Technical Terms of Natural Philosophy, in Alphabetical Order.

A

Evaporation, Abdampfen, steaming off, Abrauchen, smoking off, Evaporatio, Evaporation. A chemical process through which volatile substances are separated from fire-resistant or less volatile ones by means of the air and a certain degree of heat. For instance, one allows excess water to evaporate from salt solutions in warm air in order to retain the salts, which then precipitate as crystals.

Evaporation differs from distillation only in that one collects the volatile substance during distillation, but allows it to escape during evaporation; therefore, evaporation occurs in open and flat vessels that expose a large surface area to the air, for example in bowls, basins, or potsherds. The necessary degree of heat depends on the degrees of volatility and fire-resistance of both substances and on the strength of their cohesion. If the substance that is to remain is less fire-resistant and clings firmly to the volatile one, the heat must act gently and slowly. In the opposite case, a higher degree of heat and a draft of air directed at the surface of the mixture are useful.
Macquer's Chemical Dictionary, Art. Evaporation.

Evening, Abend, Abendgegend, evening region, Occidens, Plaga occidentalis, Occident, Ouest. That region of the world or heaven where the stars set. One has it to the right when one turns one's face toward the south original: "Mittag".