By porosity is understood the freedom with which air can pass through the interstices of a fabric.
The conclusion follows that porosity does not injure the powers of preventing radiation (it even increases it) for flannel, admittedly the warmest clothing, permits the freest circulation of air.
By greatest porosity best provision is made for the evaporation of perspiration, the quantity of which varies greatly under different conditions.
The colouring matter is absorbed by the porosity of the stone, but different stones and even different layers in the same stone exhibit great variation in absorptive power.
The material of these cells is usually cement, mixed with certain soluble salts which impart sufficient porosity to the material.
These characters are dependent principally, though not entirely, on theporosity of the soil.
On the other hand, it diminishes the porosity of light sandy soils, causes them to retain moisture, and generally makes their texture more suitable to the plant.
Boussingault says, is not due toporosity in the native gold, as he has observed it in the granular and fine varieties, but a peculiar character of the metal in this state.
The causes of inflammation are to be regarded as those which produce an increased porosity of the vessel wall without causing its death, for no exudation escapes from a dead vessel, its contents becoming clotted.
Such exceptional mortality over so wide a territory has been ascribed to the extreme porosity and humidity of the soil, which is nearly all below the level of the sea.
The character of the site is mainly determined by its dryness, by the presence or absence of organic matter in the soil, and by its porosity taken in connection with the character of the vicinity.
They may likewise, in connection with their colonization in various parts of the body, act more immediately upon the walls of the blood-vessels, and produce that increased porosity which is so essential a factor in inflammation.
The results obtained from these tests correspond to those of the former tests, and led to the conclusion that the porosity of linseed oil films varied when different pigments were used in the oil.
After this operation it presents the appearance of ordinary sheet lead, but though the physical porosity has disappeared, the chemical porosity is intact, and this alone comes into play in accumulators.
The length of time required for steeping depends upon the thickness of the rust and the porosity or existence of cracks in it, and if the objects are of considerable size, it may extend over several weeks.
The length of the steeping must depend upon the size andporosity of the limestone.
The porosity of the basis is in some degree variable in B.
To overcome these defects, the very natural process was adopted of diluting the bleaching-powder, such diluent also serving to increase the porosity of the material.
The porosity and physical attraction of the soil lead to the oxidation of the organic matter contained in the sewage, as instanced in the discovery of nitrates and nitrites in the effluent water, which did not exist previous to filtration.
The residuary mass should not be heated red hot, so as not to impair its porosity or its ready affinity for carbonic acid.
To give you an idea of the extreme porosity of bodies, sir Isaac Newton conjectured that if the earth were so compressed as to be absolutely without pores, its dimensions might possibly not be more than a cubic inch.
What conjecture was made by sir Isaac Newton, respecting the porosityof bodies in general?
I have not been able to detect any relative porosity in the "internal icy structure," nor am I able to find in the writings of Professor Forbes a description of the experiments whereby he satisfied himself that this assumed difference exists.
The water is not at rest, but has a slow and well-defined motion, the rate of which depends upon the porosity of the soil and also upon the inclination or gradient of the water table.
Except in the hardest granite rocks and in soil completely filled with water the interstices of the soil are filled with a continuation of atmospheric air, the amount depending on the degree of porosity of the soil.
Water thus deposited on the soil is absorbed more or less completely, in proportion to the porosity of the ground.
On rich land, which is maintained in this condition of porosityand mellowness, agriculture will produce its best results, and will encounter the fewest possible chances of failure.
They are porous, to the extent of absorbing a certain amount of water, but their porosity has nothing to do with their use for drainage,—for this purpose they might as well be of glass.
If this is really the case it would explain the porosity and large surface of some clays and might account for their adsorptive power.
Porosity may thus be regarded as the opposite of vitrification; porous goods being relatively light and soft whilst vitrified ones are dense and hard.
The porosity of raw clay is usually of small importance, but the porosity of fired clay or ware is often a serious factor in determining the suitability of certain articles for their intended purposes.
For some purposes, porosity is an important characteristic: for example, building bricks which are moderately porous are preferable to those which are vitrified.
Any kind of sand will produce porosity but the effect differs with the condition of the sand.
The small pieces should be tested for porosity or absorption of water but this is rather a delicate operation and needs a particularly sensitive balance.
Like flint it aids in the porosity of the unburned clay but unlike flint it produces density in the firing.
In order to secure the necessary porosity a fine "grog" must be used.
Porosity is therefore the reverse of plasticity and these two properties must be adjusted so as to balance each other.
It aids in the porosity of the clay and enables the mixture to be adjusted to fit a special glaze.
The porosity of wood-charcoal explains why it floats on the surface of water, although it is actually denser, its specific gravity being about 1.
Permanganate of potash is supposed to dye a mouse-grey colour, but it is most uncertain in its action, as it depends entirely on the porosity of the leather.
With certain soft leathers, if the colour has not sunk in deeply, rubbing with the finger alone will give it great brilliancy; with other leathers the rubbing will produce an effect in proportion to the degree of porosity of the skin.
The difference in height or the "head" between the point of entrance and the point of escape, together with the porosity of the rock and other factors, determine the general speed of its movement (see p.
Series of strata with disconformities may also be petroliferous, because beneath former erosional surfaces the top strata have induced porosity and therefore are possible reservoir rocks.
Between the point of entrance and the point of escape from the water table, the water follows various courses, depending upon the porosity and the openings in the rocks.
The porosity of the rocks, and therefore the flow of an artesian circulation, may in some cases be artificially increased by blasting and shattering.
With equalporosity the flow is at a maximum along a line directly connecting the two points, and on more devious courses the flow is less.
A less reliable method is to calculate from geologic data the volume and porosity of the oil-bearing reservoirs, and to estimate the percentage of recovery on the basis of current practices and conditions.
A certain degree ofporosity in the original rock is also known to favor the alteration.
Favorable conditions may also be merely differences in porosity of beds in irregular zones, determined by differences either in original deposition or in later cementation.
In drying it shrinks, loses its porosity and requires long soaking to saturate it again.
The cloth, covering the rolls, must have great strength, sufficient porosity to allow water to pass it freely, and such closeness of texture as to retain the fine particles of peat.
Many of the properties of charcoal which depend exclusively on its porosity are shared by many other porous substances, and vary with the density of the charcoal and depend on the way it was prepared.
The degree of porosity of charcoal varies considerably, and has a technical significance, in different kinds of charcoal.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "porosity" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: colander; honeycomb; net; riddle; screen; sieve; sponge; strainer
