Moisture content

“ Not all scientific works, however, make this incautious application of the fact that dew results from the condensation of moisture of the air in contact with cooler bodies. Farmers have quite universally accepted the view quoted, and believe that soils gain moisture by night from the air. ”

“ The third element concerned in the climate, namely, moisture, has now to be considered, and it is important from the fact that in a moister climate the percentages both of glucose and of acids in the grape are diminished. It is also important for another reason, namely, that while heat and light are unalterable, moisture may be produced by irrigation. ”

“ The rapidity of the chemical change is chiefly governed by the proportion of moisture, being greatly accelerated by wetting the bruised kernels or leaves, and stopped altogether by drying, while the moisture of the living plant permits only a gradual rate of the transformation. ”

“ We now see that, as a living organism, it tends, on the one hand, to diminish the humidity of the air by sometimes absorbing moisture from it, and, on the other, to increase that humidity by pouring out into the atmosphere, in a vaporous form, the water it draws up through its roots. ”

“ Neither is Water the Principle of Actual moisture, nor the propriety of seeds the Principle of all Virtual moisture; but self-moving Matter is the Principle of all, and makes both actual and virtual moisture, and there is no question but there are many sorts of moistures. ”

“ The rich dryness, or want of fluidity of the juices which occasions flower-buds, is also induced by hot, dry atmosphere, and short supply of moisture from the roots during the preceding summer, both of which disposing causes are increased by a long naked stem. ”

“ Neither can the sun pull the moisture up through the tiny little tubes in the soil if we break those little tubes and crumble the tops into dust. No, you need not look for these tubes, Mary Frances; they are too tiny for you to see, but they act very much like blotting paper to bring the under moisture up to the surface, and unless they are broken and crumbled, the deep earth moisture goes sailing off into the air to meet the sun, as fast as if it ran out of a little spigot running it off, and the poor plant baby dries up for want of deep moisture near its roots. ”

“ The evaporation of the juices of trees and other plants is doubtless their most important thermoscopic function, and as recent observations lead to the conclusion that the quantity of moisture exhaled by vegetables has been hitherto underrated, we must ascribe to this element a higher value than has been usually assigned to it as a meteorological influence. ”

“ The necessary temperature is speedily attained by the heating action of the sun's rays, when the soil is dry; but when it is wet, the heat is expended in evaporating the moisture with which it is saturated ”

“ The object being to expel the moisture in the most gentle manner, and, at the same time, to allow the leaves to remain as soft and pliable as possible. When the sun is clear and powerful the moisture evaporates too rapidly, and the leaves are left crisp, coarse, and not in a proper state to undergo the remaining part of the process. ”

“ A moist genial atmosphere too is essential, a point requiring unremitting attention on account of the necessity of keeping up strong fires. With moisture as with heat, the cultivator must hold his hand somewhat in very severe or very dull weather; but while heat must not drop so as to chill the progressing vegetation, so neither must the lack of moisture parch the plants so as to check their growth. ”

“ The moisture is used up and the fruit makes the heat rise, and so the fruit will be bitter, and the stones in the fruit will be pyramidal in form on account of the upward attraction of the heat and the downward attraction of the cold and moisture which are of the same nature as sour water; and the moisture remains in the trunk of the tree, which consequently thickens, while its extremities are thin. ”

“ It ought to be explained that the reason why the earth is brought to a medium state of moisture before being put into the pots is because it is never afterwards watered to such an extent as to render it really wet, being in fact just kept in that state of moisture in which it was originally placed in the pots, and this uniform and medium state of moisture is more easily retained by the pots being plunged in beds of earth. ”

“ Water, a solid substance, heat, a beginning putrefaction, appear indispensable to the production and propagation of the animalcules; and such conditions are in fact always united. Without moisture, they never live; a solid substance must offer a basis to moisture, and, according to physical laws, the contact of the one with the other generates heat, and only by the simultaneous action of moisture and heat can putrefaction take place. ”

“ Roots seek at once heat and moisture; if the moisture awaits them close to the surface, of course they mainly run there, because the heat is there greatest. If moisture fails there, they must descend to seek it, even at the cost of finding the heat inadequate—though heat increases and descends under the fervid suns which rob the surface of moisture. ”

“ Determination of Moisture.—Heat two to five grams of the air-dried soil in a flat-bottomed, tared platinum dish; heat for five hours in a water-oven kept briskly boiling; cover the dish, cool in a desiccator, and weigh.
Repeat the heating, cooling, and weighing at intervals of two hours till constant weight is found, and estimate the moisture by the loss of weight. Weigh rapidly to avoid absorption of moisture from the air. ”

“ The water in all these rivers, lakes, and oceans is constantly rising into the air in what is called moisture or vapor. We can not see this moisture, neither can we see the air.
If the air is cold, moisture does not rise rapidly; but, as the air becomes heated, it takes up more moisture, so that the more heat there is in the air, the more moisture rises. ”

“ When the drying is done in a dry atmosphere the surface quickly dries and hardens, and the moisture from the interior passes to the surface as vapour, the soluble salts being left distributed through the whole mass, and consequently no “scum” is produced. ”

“ These observations and experiments establish the fact that the drops which first make their appearance on grass on dewy nights are not dew-drops at all, but the exuded watery juices of the plants.
If now we look at dead leaves we shall find a difference of formation of the moisture on a dewy night: the moisture is spread equally over, where equally exposed. The moisture exuded by the healthy grass is always found at a point situated near the tip of the blade, forming a drop of some size ”

“ The heated air over our fields and streams, in Summer, is loaded with moisture as the sun declines. The earth has been cooled by radiation of its heat, and by constant evaporation through the day. By contact with the cooler soil, the air, borne by its thousand currents gently along its surface, is condensed, and yields its moisture to the thirsty earth again, in the form of dew. ”

“ Fig. 3.—Spores of Algæ and Molds in the Atmosphere.
the development of molds is dependent upon both heat and moisture. The effect of moisture, however, varies according to the season, and with changes in temperature. Dry weather diminishes the number of germs in summer, and increases it in winter, while moist weather operates in an inverse manner. ”

“ When air holds all the moisture it can sustain, its moisture is said to be at 100 per cent.; when it holds only one-half as much as its temperature demands, it is said to be at 50 per cent.; and when it holds three-fourths of what its temperature requires, it is at 75 per cent. ”

“ Coefficient of Evaporation.—At an ordinary room temperature in the shade, samples of soil, if they are subjected to experiment in tolerably thin layers have nearly an equal coefficient of evaporation. That is, the absolute quantity of water evaporated in a given time is almost entirely conditioned upon the magnitude of the surface exposed and the temperature of the surrounding air. Only when exposed in conditions as nearly as possible natural in thin layers to the action of the sunlight and shade do the soils show their peculiarities in respect of the evaporation of moisture. ”

“ If the temperature of the confined space be increased, opportunity will thereby be provided for the vaporization of more water, but if it be decreased, its capacity for moisture will be reduced and visible water will be deposited. ”

“ When the earth becomes compact and hard the water can not so freely move through it; if the weather is dry, then follows another important result—the air, which always bears with it more or less moisture, especially in hot weather, can not pass through the soil and bring to the roots its gift of nutrition. ”

“ There is no doubt that considerable moisture in the air favors the growth of minute organisms, and decomposition of matter takes place rapidly under the influence of heat and moisture. On the other hand, a dry air retards decomposition, and, if sufficiently dry, prevents it entirely, no matter how hot it may be. ”

“ We always give air when the temperature is 65°, but always avoid cold draughts. We usually moisten our houses twice a day, morning and evening, if the weather is at all fine and the house dry; but the application of moisture should depend upon the weather; during the dull months of autumn and winter a little will suffice, but in summer, of course, a considerable amount of moisture spread over the tables and paths will be required. ”

“ For that purpose it is necessary to avoid the application of moisture beyond what is necessary to prevent a decided check in the growth of the plants, to expose them to the influence of light, by not suffering them to crowd or overhang each other, and to prevent from what cause soever the too sudden declension of the average temperature to which they are exposed. ”

“ To succeed in the culture of the Carnation, we must advert to the situation in which it is found wild, and this is observed to be dry and elevated; hence excessive moisture is found to be one of the greatest enemies this plant has to encounter ”

“ If it be subjected to the influence of an atmosphere containing a greater amount of moisture it increases in bulk, or, as it is popularly termed, it swells; in a drier atmosphere it shrinks and is apt to crack. ”

“ Hales, in his Vegetable Statics, advances, from experiment, that ‘the moister the earth is the more dew falls on it in a night: and more than a double quantity of dew falls on a surface of water than there does on an equal surface of moist earth.’ Hence we see that water, by its coolness, is enabled to assimilate to itself a large quantity of moisture nightly by condensation; and that the air, when loaded with fogs and vapours, and even with copious dews, can alone advance a considerable and never-failing resource. ”

“ But after any number of days and nights of rain, and in all places exposed to returning sunshine and breezes, the distribution of the moisture tells. So soon as the rain has ceased, all water that can run off is of course gone from the steep hill-sides; there remains only the thin adherent film of moisture to be dried; but that film is spread over a complex texture—all manner of crannies, and bosses, and projections, and filaments of moss and lichen, exposing a vast extent of drying surface to the air. ”

“ The kind of vegetation growing on a particular plot and its density have even more to do with soil moisture loss than temperature or humidity or wind speed. And, surprising as it might seem, bare soil may not lose much moisture at all. ”

“ Within the ordinary limits of solar temperatures it may be said that, other things being equal, the higher the temperature the more intense will be chemical action in soil formation. Since, however, water is a potent factor in the majority of these processes, the presence or absence of moisture at the same time with heat will cause material differences in the kind and intensity of chemical action. ”

“ When the air is allowed to circulate among its lower and cooler particles, they receive moisture from the same process of condensation. Therefore, when, by the aid of under-drains, the lower soil becomes sufficiently open to admit of a circulation of air, the deposit of atmospheric moisture will keep the soil supplied with water at a point easily accessible to the roots of plants. ”

“ The qualities hitherto sought in a hygrometer, or instrument to discover the degrees of moisture and dryness [136] in the air, seem to have been, an aptitude to receive humidity readily from a moist air, and to part with it is as readily to a dry air. ”

“ In other cases, from injudicioua husbandry, or the diversion or choking up of natural water-courses, it may become more highly charged with humidity. An increase or diminution of the moisture of a soil almost necessarily supposes an elevation or a depression of its winter or its summer heat, and of its extreme if not of its mean annual temperature, though such elevation or depression may be so slight as not sensibly to raise or lower the mercury in a thermometer exposed to the open air. ”

“ From this: dry air, when coming in contact with wet objects, absorbs the moisture, and by this dries the object somewhat. If there be no wind, the moistened air will remain around the wet object, and the drying goes on very slowly. But so soon as a little wind arises, the moist air is moved away, new dry air constantly takes its place, and coming into contact with the wet article, effects in a very short time the desired result. ”

“ When cold air is admitted to any position where it can unite with caloric, and not in an equal ratio with moisture, it necessarily becomes arid, and in that state it eagerly combines with moisture in any form with which it can come in contact therewith; and consequently if cold air is admitted to a plant structure, where it can have the means of combining with heat, faster than with moisture, it would be brought into this arid state, and would supply its voracious appetite, by abstracting the juices of the plant. ”