NOTE XXV … EVAPORATION.
I. Solution of water in air; in the matter of heat; pulse-glass. 2. Heat is the principal cause of evaporation; thermometer cooled by evaporation of ether; heat given from steam to the worm-tub; warmth accompanying rain. 3. Steam condensed on the eduction of heat; moisture on cold walls; south-west and north-east winds. 4. Solution of salt and of blue vitriol in the matter of heat. II. Other vapours may precipitate steam and form rain. 1. Cold the principal cause of devaporation; hence the steam dissolved in heat is precipitated, but that dissolved in air remains even in frosts; south-west wind. 2. North-east winds mixing with south-west winds produce rain; because the cold particles of air of the north-east acquire some of the matter of heat from the south-west winds. 3. Devaporation from mechanical expansion of air, as in the receiver of an air-pump; summer-clouds appear and vanish; when the barometers sink without change of wind the weather becomes colder. 4. Solution of water in electric fluid dubious. 5. Barometer sinks from the lessened gravity of the air, and from the rain having less pressure as it falls; a mixture of a solution of water in calorique with an aerial solution of water is lighter than dry air; breath of animals in cold weather why condensed into visible vapour and dissolved again.