Water vapor

“ Vapor is always going up. Most of it goes up from the ocean, the lakes and rivers. Three fourths of our big world is covered with water, you know. The sun warms the top layer of water and turns it into vapor. Every leaf and blade of grass on the land has water in it. The sun steals this water, too. Sometimes it takes so much and gives so little back again that the grass turns brown, and the leaves wilt. Every animal and plant drinks water and breathes it out again from the lungs, or gives it to the air through little holes in the skin called pores. ”

“ Water, flowing over a bed of this mineral, liberates the gas in the form of an almost invisible vapor. It is swept forward in a cloud by the wind, some of it is carried along above the course of the underground stream, and as soon as it reaches an opening in the earth, like a fissure crack in the rock or ground, the gas rises and whoever breathes it dies or is rendered unconscious for a time, according to the strength of the vapor. ”

“ Perhaps you may ask how it is that the vapor so universally present gets into the atmosphere, and where it comes from. If you pour a little water into a plate, and set it down in the open air, you will note in the course of a day or two, that the water has sensibly diminished. The air has drunk up part of it, and will drink up the whole, if the water is allowed to stand long enough. What takes place from a small quantity of water goes on from every surface of water on the face of the earth, from every brook and river and lake, and from the great sea itself. ”

“ Whenever water is left freely exposed to the air, it evaporates; that is, it passes into the gaseous state and mixes with the gases of the air. Even snow and ice give off water vapor, though in very small quantities. The quantity of water vapor which can enter a given volume of air is definitely limited. ”

“ Vapor is perpetually rising from the ocean, and is condensed by cold in the hills and high lands, as is easily recognized by the mists and rains, which are frequent in such regions; whence it descends through their pores and crevices, till it is deflected, collected and conducted out to the sea, by some stratum or channel which is water-tight, thus keeping up a perpetual and compound circulation. ”

“ Water in the condensed state is heavier than the air and will seek the lowest places, but when vaporized, as in the process of evaporation, it is lighter than air and floats upward. In the vapor state it is transparent like steam. If you study a steam jet you will notice that for a short distance after it issues from the boiler it is transparent, but soon it condenses into cloud. ”

“ When in every vessel of heated water mankind had always seen a vapor arise, who could have supposed that in this simple fact, nature had furnished an agent, which by skilfully managing, he could multiply his natural strength a thousand fold, and move from place to place with the swiftness of a bird? By the alternate production and condensation of this vapor, which he is able to do by the very common agents of fire and water, he is able to extract the ponderous minerals from the bowels of the earth, having made it previously drain off the water which put them out of his reach. ”

“ Water, when taken up by the atmosphere, is not in an aqueous state, but is converted into vapor by the efficiency of heat, and then combines with more than five times the quantity of caloric than is required to bring ice-cold water to a boiling heat, and occupies a space 800 times greater than it does when in the form of water. ”

“ The atmosphere contains also a variable quantity of vapor of water, invisible as long as it is in the state of vapor, but it may be rendered obvious by bringing any very cold body into warm air, when the vapor will condense on the cold body in the form of small drops of water. A tumbler of fresh-pumped water brought into a crowded room is almost immediately covered with moisture, and it may also be seen on bottles of wine which have been put into ice before coming to table. Fogs are occasioned by the condensation of vapor produced by mixing a current of warm air with a colder air. ”

“ The expansive force of this vapor increases rapidly as the heat increases, but yet in all cases the surface of water is covered with an atmosphere of aqueous vapor, the pressure, or tension of which is limited by the temperature of the water. ”

“ However long we boil a fluid, in an open vessel, we cannot make it in the smallest degree hotter than the boiling point.93 When arrived at this point, the vapor absorbs the heat, and carries it off as fast as it is generated. When water is received into the atmosphere, if the air be warm, it becomes so far changed by its union with the matter of heat as to be perfectly invisible. ”

“ A large portion of the matter of heat combining chemically with water, renders it specifically lighter; which is the cause of its rising and mixing with the atmosphere. The waters on the face of the earth would be dissipated in vapor by a small degree of heat, if we had no atmosphere. Under the pressure of the atmosphere water boils at 212°, but in vacuo it boils when heated only to 67°. ”

“ A glance at this table shows that for the pressures and temperatures prevailing in our atmosphere most of the constituents are permanent gases. The conspicuous exception is water which, when in the gaseous state, always exists as a vapor, and never as a permanent gas, since it never even approaches the critical temperature. Fortunately for all life on earth the aqueous vapor condenses at very ordinary temperatures and pressures, else there would be no rainfall for irrigation and drinking. ”

“ Exposing next the globe to the temperature of boiling water, the liquid will evaporate, and we shall have our vessel filled with ordinary steam. If, now, that cubic foot of space is really packed close with the material which we call water—if there is no break in the continuity of the aqueous mass, we should expect that the vapor would fill the space to the exclusion of everything else, or at least would fill it with a certain degree of energy which must he overcome before any other vapor could be forced in. ”

“ When vapor obstructs light it is owing to impurities contained in it, to currents of varying densities, or wave motions, or to a mechanical mixture of condensed water and air, whereby multitudes of tiny globular water surfaces are produced. ”

“ Of course the sun when it shines turns some of the water into vapor that rises again to the sky. Sometimes on a cool morning you can see the mist or vapor too heavy to rise out of sight and too light to fall as rain. Wherever there is water, some of it is rising into the air, especially when the sun shines and it is warm and the wind blows. The sea is so big that great quantities of vapor are rising from it all the time and being blown over the land to be cooled, to gather into rain and to fall again where it will refresh the earth and make the plants grow. ”

“ The particles of vapor that form clouds are little bubbles, or hollow spheres filled with air. When a cold wind crushes them, they become solid, unite with one another, and fall as rain-drops. Cold water is much heavier than air; but water made hot by fire or by the sun, and turned into vapor, is lighter. In time of a fog the vapor is just warm enough to have the same weight as the air, so that it neither rises nor falls, but remains quietly near the ground. ”

“ For instance, a cold pitcher in the summer robs the vapor in the air of its heat, and causes it to be deposited on its own surface,—of course the water comes from the atmosphere, not through the wall of the pitcher; if we breathe on a knife blade, it condenses, in the same manner, the moisture of the breath, and becomes covered with a film of-water ”

“ The scientific people tell you that the vapor becomes visible, and chilled, as it expands. Many thanks to them; but can they show us any reason why particles of water should be more opaque when they are separated than when they are close together, or give us any idea of the difference of the state of a particle of water, which won't sink in the air, from that of one that won't rise in it? ”

“ The Sun said “Yes,” and took ever so many other drops, too, so that Aqua might not be lonesome on the way. He did not know this, however, for they all had been changed into fine mist or vapor. Do you know what vapor is? If you breathe into the air, when it is cold enough, you will see it coming out of your mouth like steam, and you may also see very hot steam coming from the nose of a kettle of boiling water. When it is quite near to the earth, where we can see it, we call it “fog.” ”

“ They could also see it throwing up from its air-holes to a great height a cloud of vapor, or of water, for, strange as it may appear, naturalists and whalers are not agreed on this subject. Is it air or is it water which is thus driven out? It is generally admitted to be vapor, which, condensing suddenly by contact with the cold air, falls again as rain. ”

“ The vapor-tension of ether is high even at ordinary temperatures, so that evaporation is rapid. Since the latent heat of the vapor is derived from the heat in the ether, glass and water, the water is quickly frozen. ”

“ The repelling power of intense heat keeps the water from immediate contact with the heated metal, and the particles of the water, collectively, retain their globular form; but, when the vessel cools, the repulsive power diminishes, and the water coming into closer contact with the heated surface its particles can no longer retain their globular form, and eventually expand into a state of vapor. ”

“ Now the sun is continually changing the water of rivers, ponds, lakes, and of the ocean, into vapor. This vapor rises. The air about a mile above the earth, is much colder than it is on the earth; so when the hot vapor from the ocean meets the cold air, it again becomes water, and forms clouds. ”

“ In passing over shallows or rapids, where the current is swift, the water remains open and exposed to the air. At these points in its course it parts with its accumulated air and heat very rapidly, a thin vapor or mist being often perceptible in the air at such places, owing to the rapid radiation. ”

“ The higher the temperature of the air the more water can it retain as vapor; and when air saturated with moisture is cooled, the water is deposited in liquid form in very small globules, forming a mist, fog, or cloud. ”

“ I suppose the thick air, as well as the transparent, is in both cases saturated with aqueous vapor;—but also in both, observe, vapor that floats everywhere, as if you mixed mud with the sea; and it takes no shape anywhere: you may have it with calm, or with wind, it makes no difference to it. You have a nasty haze with a bitter east wind, or a nasty haze with not a leaf stirring, and you may have the clear blue vapor with a fresh rainy breeze, or the clear blue vapor as still as the sky above. ”

“ The aqueous vapor in the air is perpetually falling to the earth as rain or snow, and is renewed by evaporation from the ocean, the lakes and rivers, and the soil itself. The quantity of aqueous vapor in a cubic foot of air varies greatly with temperature and locality on the earth's surface. ”

“ The vapor rising from the earth and the sea by evaporation, promoted by dry air, by wind, by diminished pressure, or by heat, is borne along in vesicles so rare as to float on the bosom of the winds, sometimes a grateful shade of clouds, at other times condensed and gravitating in showers of rain. Thus it enriches the soil, or cools the air, or reflects back to the earth its radiated heat. At times the clouds, freighted with moisture, present the most gorgeous hues, and we have over us a pavilion more magnificent than any ever constructed by the hand of man. ”

“ I. The first difference is, that heat is an expansive motion, by which the body strives to dilate itself, and to [154] occupy a greater space than before. This difference is principally seen in flame, where the smoke or thick vapor is clearly dilated and bursts into flame.
It is also shown in all boiling liquids, which swell, rise, and boil up to the sight, and the process of expansion is urged forward till they are converted into a much more extended and dilated body than the liquid itself, such as steam, smoke, or air. ”