It is generally taken as constant, but its value at moderate pressures is difficult to determine.
The reader will be able to make out the simultaneous motions and pressures at various points.
It was found, however, that when Oxyacetylene using acetylene under low pressures, the burner tip blowpipe.
became so heated as to cause the decomposition of some of the gas before combustion, the jet being choked up by the carbon which deposited in a very dense form; and as the use of acetylene under pressures greater than one hundred inches of water was prohibited, no advance was made in this direction.
But if hinges are introduced at crown and springings, the calculation of the stresses in the arch ring becomes simple, as the line of pressures must pass through the hinges.
follows nearly the parabolic line of pressures.
Further impulsive pressures are required to restart into motion all the molecules which have undergone collision.
With Sydney Young and others he investigated the critical state and properties of liquids and the relationship between their vapour pressures and temperature, and with John Shields he applied measurements of the surface tension of liquids to the determination of their molecular complexity.
It has been found that variations in barometric pressure affect the flash-point and accordingly corrections have to be made in obtaining strictly comparative results at different pressures.
(17) in which c is a small quantity (expressing the defect from the ideal volume V =Re/p due to co-aggregation of the molecules) which varies inversely as the nth power of 0, but is independent of p to a first approximation at moderate pressures.
It appears to be a quantity of the same order as the volume of the liquid, or as the limiting volume of the gas at very high pressures.
As an example of one of the few cases where a complete solution is possible, we may take the comparatively simple case equation (17), already considered, which is approximately true for the majority of vapours at moderate pressures.
The difference in the weights corresponds to the volume of gas at a pressure equal to the difference of the recorded pressures.
The aggregate amount of these pressures is clearly the sum of the momenta, normal to the boundary, of all molecules which have left dS within a time dt, and this will be given by expression (pp), integrated with respect to u from o to and with respect to v and w from - oo to +oo, and then summed for all kinds of molecules in the gas.
by taking advantage of the different rates of diffusion of the two gases; the solubility of air in water corresponds with the "law of partial pressures," each gas being absorbed in amount proportional to its pressure and coefficient of absorption, and oxygen being much more soluble than nitrogen (in the ratio of 04114 to 02035 at o°); air expelled from water by boiling is always richer in oxygen.
occur in storms annually in many localities, and that occasionally higher pressures are recorded in exposed positions.
As to anemometer pressures, it should be observed that the recorded pressure is made up of a positive front and negative (vacuum) back pressure, but in structures the latter must be absent or only partially developed.
The most fundamental experimental confirmation that the theory of the aether has received on the optical side in recent years has been the verification of Maxwell's proposition that radiation exerts mechanical force on a material system, on which it falls, which may be represented in all cases as the resultant of pressures operating along the rays, and of intensity equal at each point of free space to the density of radiant energy.
They will alter the shape of mineral particles by broadening them in a direction at right angles to the principal pressures, while they are thinned in the direction in which the pressure acted.
3) as for a /-' 21: '.; Obserued Pressures.
Pressures Observed In A Closed Vessel With Various Explosives 20 15 s n 05 10 -15 20 25 30 35 40.45 50.
Carbon dioxide dissociates, when strongly heated, into carbon monoxide and oxygen, the reaction being a balanced action; the extent of dissociation for varying temperatures and pressures has been calculated by H.
In air and other gases, at ordinary pressures, the dispersion is very small, because the refractivity is small.
For the investigation of the spectra of gases at reduced pressures the so-called Plucker tubes (more generally but incorrectly called Geissler tubes) are in common use.
(c) Under moderate pressures the lines of hydrogen may be widened by powerful sparks taken from a condenser.
(d) If a spark be taken from an electric condenser through air, both the lines of oxygen and nitrogen are wide compared with what they would be at low pressures.
In the original experiments 2 the pressures could only be increased to 15 atmospheres, but in a more recent work Humphreys,' and independently Duffield, were able to use pressures up to ioo atmospheres.
We have first the Doppler effect, which, according to Michelson's experiment, is the chief cause of the limit at very low pressures, but it is too small to account for the widening which is now under discussion.
pressures felt) from which we infer similar objects beyond sense (e.g.
similar pressures of outside things), but are the actual elements out of which everything known is made; as if sensations were like chemical elements.
Having felt reciprocal pressures in touch, I infer similar pressures between myself and the external world.
There is none in the subsidiary senses, because none of them perceives the pressures exerted on them.
But the primary sense of touch perceives one bodily member causing pressure on another, reciprocally, within the organism, from which we infer similar particular pressures caused between the organism and the external world; but without needing the supposed stupendous belief and assumption of the uniformity of Nature, which is altogether ignored in the inferences of the ordinary man.
In practice the time required to reach these various conditions of equilibrium would be too great for experimental demonstration, but the theoretical consideration of vapour pressures is of fundamental importance.
Now measurements of osmotic properties of these solutions show that their osmotic pressures are abnormally great and that, at extreme dilution, the ratio of their osmotic pressures to that of equivalent solutions of non-electrolytes is equal to the number of ions indicated by the electrolytic properties.
The osmotic pressure (defined as the difference in the hydrostatic pressures of the solution and solvent when their vapour pressures are equal and they are consequently in equilibrium through a perfect semi-permeable membrane) may also depend on the absolute values of the hydrostatic pressures, as may the vapour pressure of the liquids.
The osmotic pressure Po is the difference of the hydrostatic pressures P' and P of the solution and the solvent when their vapour pressures are equal.
The relation between the equilibrium pressures P and P' for solution and solvent corresponding to the same value po of the vapour pressure is obtained by integrating the equation V'dP' = vdp between corresponding limits for solution and solvent.
J p J where p and p' are the vapour pressures of solvent and solution each under its own vapour pressure only.
From this equation the osmotic pressure Po required to keep a solution in equilibrium as regards its vapour and through a semi-permeable membrane with its solvent, when that solvent is under its own vapour pressure, may be calculated from the results of observations on vapour pressure of solvent and solution at ordinary low hydrostatic pressures.
The osmotic pressures of strong sugar solutions were measured successfully by a direct method with semi-permeable membranes of copper ferrocyanide by Lord Berkeley and E.
Hartley, who also determined the vapour pressures by passing a current of air successively through weighed vessels containing solution and water respectively.
Their table of comparison published in 1906 shows the following agreement: - It seems likely that measurements of vapour pressure and compressibility may eventually enable us to determine accurately osmotic pressures in cases where direct measurement is impossible.
The difference in the lowering of vapour pressures dp - dp' may be put equal to VdP/v, where P is the osmotic pressure, and V the specific volume of the solvent.
Let us assume that the ratio p/p' of the vapour pressures of the solvent and solution is equal to the ratio of the number of free molecules of solvent to the whole number of molecules in the solution.
If there are n molecules of solute to N of solvent originally, and each molecule of solute combines with a molecule of solvent, we get for the ratio of vapour pressures p/p'=(N - an)/(N - an+n), while the relative lowering of vapour pressure is (p - p')/p=n/(N - an).
The second of these essays opens with the striking remark, "There can scarcely be a doubt entertained respecting the reducibility of all elastic fluids of whatever kind, into liquids; and we ought not to despair of effecting it in low temperatures and by strong pressures exerted upon the unmixed gases"; further, after describing experiments to ascertain the tension of aqueous vapour at different points between 32° and 212° F., he concludes, from observations on the vapour of six different liquids, "that the variation of the force of vapour from all liquids is the same for the same variation of temperature, reckoning from vapour of any given force."
He thus enunciated the law of the expansion of gases, stated some months later by Gay-Lussac. In the two or three years following the reading of these essays, he published several papers on similar topics, that on the "Absorption of gases by water and other liquids" (1803), containing his "Law of partial pressures."
Within the crust of the earth, whether by the contraction of the interior or in any other way, tangential pressures were set up. Since the crust is not of uniform strength throughout, only the weaker portions yielded to the pressure; and these were crumpled up against the more resisting portions and sometimes were pushed over them.
Even hard steel is treated in this way to form tubes for the highest hydraulic and steam pressures.
The ice was however much heavier, and in the terrific pressures which occurred the " Endurance " was crushed on Oct.
In Consequence Of The Small Thermal Capacity Of Gases And Vapours Per Unit Volume At Ordinary Pressures, The Difficulties Of Direct Measurement Are Almost Insuperable Except In Case (2).
Employing Pressures Between 7 And 27 Atmospheres, He Found That The Specific Heat Of Air Between 10 And Ioo C. Increased Very Slightly With Increase Of Density, But That Of Co 2 Increased Nearly 3% Between 7 And 21 Atmospheres.
For Such Gases, Assuming A Constant Ratio Of Rotation To Translation, The Specific Heat At Low Pressures Would Be Very Nearly Constant.
When from the sensible pressures between the parts of my mouth, which I feel and remember and judge that they exist and have existed, I infer another similar pressure (e.g.
the pressure of food without as well as the sensible pressures within).
P. Pfeffer (Osmotische Untersuchungen, Leipzig, 1877) was the first to obtain satisfactory measurements of osmotic pressures of cane-sugar solutions up to nearly I atmosphere by means of semi-permeable membranes of copper ferrocyanide.
1906, p. 481) succeeded in measuring osmotic pressures of cane-sugar, dextrose, &c., up to 135 atmospheres.
The highest pressures recorded for cane-sugar are nearly three times as great as those given by van't Hoff's formula for the gas-pressure, but agree very well with the vapour-pressure theory, as modified by Callendar, provided that we substitute for V in Arrhenius's formula the actual specific volume of the solvent in the solution, and if we also assume that each molecule of sugar in solution combines with 5 molecules of water, as required by the observations on the depression of the freezing-point and the rise of the boiling-point.
It was applied in the most perfect manner by Regnault to determine the latent heats of steam and several other vapours at high pressures.
It is evident that this is a very delicate method of determining the wetness z, but, since with dry saturated steam at low pressures this formula always gives negative values of the wetness, it is clear that Regnault's numerical coefficients must be wrong.
The method of deducing the specific heat from Regnault's formula for the variation of the total heat is evidently liable in a greater degree to the objections which have been urged against his method of determining the specific heat, since it makes the value of the specific heat depend on small differences of total heat observed under conditions of greater difficulty at various pressures.
37, p. 504, 1889) to give values of the total heat to to 6 calories too large between o° and 40° C. At low pressures and temperatures it is probable that saturated steam behaves very nearly as an ideal gas, and that the variation of the total heat is closely represented by Rankine's equation with the ideal value of S.
In order to correct this equation for the deviations of the vapour from the ideal state at higher temperatures and pressures, the simplest method is to assume a modified equation of the Joule-Thomson type (Thermodynamics, equation (17)), which has been shown to represent satisfactorily the behaviour of other gases and vapours at moderate pressures.
Regnault's formula for the total heat is here again seen to be inadmissible, as it would make the latent heat of steam vanish at about 870° C. instead of at 365° C. It should be observed, however, that the assumptions made in deducing the above formulae apply only for moderate pressures, and that the formulae cannot be employed up to the critical point owing to the uncertainty of the variation of the specific heats and the cooling effect Q at high pressures beyond the experimental range.
The rate of variation of the latent heat at low pressures is equal to S-s, where s is the specific heat of the liquid.
It was employed as a purely empirical formula by Bertrand and Barus, who calculated the values of the coefficients for several substances, so as to obtain the best general agreement with the results of observation over a wide range, at high as well as low pressures.
The true application of the formula is to low pressures, at which it is very accurate.
The close agreement found under these conditions is a very strong confirmation of the correctness of the assumption that a vapour at low pressures does really behave as an ideal gas of constant specific heat.
This case has important practical applications; for instance we may use the method to find the pressures on the supports of a beam loaded in any given manner.
The segments DE, nA then represent ~he upward pressures of the two supports on the beam, which pressures together with the given loads constitute a system of forces in equilibrium.
The pressures of the beam on the supports are of course represented by ED, AE.
If we wish to study the effects of a movable load or system of loads, in different positions on the beam, it is only neces sary to shift the lines of action of the pressures of the support~ relatively to the funicular, keeping them at the same distanci apart; the only change is then in the position of the closing line of the funicular.
It is evident, in the first place, that in any displacement common to the two surfaces, the work of the two equal and opposite normal pressures will cancel; moreover if, one of the surfaces being fixed, an infinitely small displacement shifts the point of contact from A to B, and if A be the new position of that point of the sliding body which was at A, the pro jectior of AA on the normal at A is of the second order.
The statement may be extended to a system of rigid bodies, provided the mutual reactions consist of the stresses in inextensible links, or the pressures between smooth surfaces, or the reactions at rolling contacts (~ 9).
A compound pendulum is a body of any form which is free to rotate about a fixed horizontal axis, the only extraneous force (other than the pressures of the axis) being that of gravity.
Stability, Stiffness and Strength.A structure may be damaged or destroyed in three ways:first, by displacement of its pieces from their proper positions relatively to each other or to the earth; secondly by disfigurement of one or more of those pieces, owing to their being unable to preserve their proper shapes under the pressures to which they are subjected; thirdly, by breaking of one or more o~ those pieces.
Considering, in the first place, the case in which the load and the two resistances by which each piece is balanced meet in one point, which may be called the centre of load, there will be as many such points of intersection, or centres of load, as there are pieces in the structure; and the directions and positions of the resistances or mutual pressures exerted between the pieces will be represented by the sides of a polygon joining Pi h2 ~, ~ those points, as in fig.
According to a well-known principle of statics, because the loads or external pressures P1L~, &c., balance each other, they must be proportional to the sides of a closed polygon drawn respectively parallel to their directions.
But in other cases the earth is to be treated as one of the pieces of the structure, loaded with a force equal and opposite in direction and position to the resultant of the weight of the structure and of the other pressures applied to it.
Line of PressuresCentres and Line of Resistance.The line of pressures is a line to which the directions of all the resistances in one polygon are tangents.
The difference between the line of resistance and the line of pressures was first pointed out by Moseley.
Re- d peating this process for each d block in succession there will be found the centres of pres sure C2, C3, &c., and also the resultant pressures R2, R3, FIG.
A curve tangential to all the sides of the polygon is the line of pressures.
For in the second structure the weights, external pressures, and resistances will balance each other as in the first structure; the weights of the pieces and all other parallel systems of forces will have the same ratios as in the first structure; and the severa] centres of resistance will divide the depths of the joints in the same proportions as in the first structure.
The effect of the pressures applied to a piece, consisting of the load and the sispporting resistances, is to force the piece into a state of strain or disfigurement, which increases until the elasticity, or resistance to strain, of the material causes it to exert a stress, or effort to recover its figure, equal and opposite to the system of applied pressures.
The foi-m and arrangement of the pieces of the frame depend upon the arrangement and the motions of the mechanism; the dimensions of the pieces of the frame required in order to give it stability and strength are determined from the pressures applied to it by means of the mechanism.
It is shown that a machine may at any instant be represented by a frame of links the stresses in which are identical with the pressures at the joints of the mechanism.
Incidentally the method gives the pressures at every joint of the mechanism.
Klein, New Constructions of the Force of Inertia of Connecting Rods and Couplers and Constructions of the Pressures on their Pins, Journ.
The tangential pressures which are known to be set up in the earth's crust - either by the contraction of the interior or in some other way - caused the deposits of this sea to be crushed up against the rigid granites and other old rocks of the peninsula and finally led to the whole mass being pushed forward over the edge of the part which did not crumple.
The pressure at any point of the liquid which is above this level is negative T unless another fluid as, for instance, the air, presses on the upper surface, but it is only the difference of pressures with which we have to do, because two equal pressures on opposite sides of the surface produce no effect.
Hence the film in the form of the catenoid which is nearest the axis is in unstable equilibrium under the condition that it is exposed to equal pressures within and without.
In calculations for wind pressures, the working stresses set forth in the code may be increased by fifty per centum.
It forms a colourless syrup, of specific gravity 1.2485 (1 5°/4°), and decomposes on distillation under ordinary atmospheric pressure; but at very low pressures (about i mm.) it distils at about 85° C., and then sets to a crystalline solid, which melts at about 18° C. It possesses the properties both of an acid and of an alcohol.
Recent experiments on arc spectra at pressures up to 100 atmospheres by W.
Thus they not only penetrate all cavities in an exceedingly intrusive manner, but exert pressures in all directions, which, owing to the density of the asphalt, are more than 40 greater than would be produced by a corresponding depth of water.
Hence it follows that on the assumption of uniformly varying stress the line of pressures, when the reservoir is full, should not at any horizontal plane fall outside the middle third of the width of that plane.
Rankine in his report adopted the prudent course of taking as the safe limits certain pressures to which, at that time, such structures were known to be subject.
The late Sir Benjamin Baker, F.R.S., suggested that the stresses might be measured by experiments with elastic models, and among others, experiments were carried out by Messrs Wilson and Gore a with indiarubber models of plane sections of dams (including the foundations) who applied forces to represent the gravity and water pressures in such a manner that the virtual density of the rubber was increased many times without interfering with the proper ratio between gravity and water pressure, and by this means the strains produced were of sufficient magnitude to be easily measured.
It is notorious among engineers that retaining walls designed in accordance with the well-known theory of conjugate pressures in earth are unnecessarily strong, and this arises mainly from the assumption that the earth is merely a loose granular mass without any such adhesion.
As a result of this theory, in the case of a retaining wall supporting a vertical face of earth beneath an extended horizontal plane level with the top of the wall, we get p _ wx 2 1 - sin ii 2 I +sin P' [[Reservoir Empty Reservoir Full Ellipses Of Vertical Pressures On Horizontal Joints]].
Horizontal Pressures On Vertical Joints.
But like every pure theory the principles of conjugate pressures in earth may lead to danger if not applied with due consideration for the angle of repose of the material, the modifications brought about by the limited width of artificial embankments, the possible contraction away from the masonry, of clayey materials during dry weather for some feet in depth and the tendency of surface waters to produce scour between the wall and the embankment.
The line of pressures as generally given for this dam with the reservoir full, on the hypothesis that the density of the masonry was a little over 2, is shown by long and short dots in fig.
85 when dry and 2.07 when saturated, which would bring the line of pressures even closer to the outer face at the top of the counterfort.
Thus it happened that pipes and joints intended for a low-pressure supply were subjected, not only to high pressure, but to the trying ordeal of suddenly varying pressures.
In another arrangement two similar triangular levers take bearing on opposite sides of an intermediate lever which communicates their pressures to the steelyard; this is a very sound and simple arrangement for ordinary long weighbridges.
The engine is moved on to them, and the pressures of all the wheels are taken simultaneously, each by its own weighbridge.
For many practical purposes these statements are sufficiently accurate, and they do in fact sensibly represent the results of experiment for the pressures and at the velocities most commonly occurring.
Both at very high and very low pressures the coefficient of friction is affected by the intensity of pressure, and, just as with velocity, it can only be regarded as independent of the intensity and proportional simply to the total load within more or less definite limits.
Currents from the ten-thousandth of an ampere to ten thousand amperes, electrical pressures from a minute fraction of a volt to 100,000 volts, come within the range of his instruments, while the private consumer of electric energy is provided with a meter recording Board of Trade units.
If oils and fats are treated with water alone under high pressure (corresponding to a temperature of about 220° C.), or in the presence of water with caustic alkalis or alkaline earths or basic metallic oxides (which bodies act as "catalysers") at lower pressures, they are converted in the first instance into free fatty acids and glycerin.
The boiling point of water varies with pressure; thus at one atmosphere or 14.7 lb per square inch it is 212° F., whereas at a pressure of 085 lb per square inch it is 32°, and at lower pressures there is a still further fall in temperature.
The microbiological system is closed by mesozooplankton grazing pressures taken from observed zooplankton abundance.
Target setting and external pressures for raising pupil achievement.
alveolusmental and clinical studies in the 80's confirmed that high peak airway pressures in ventilated alveoli lead to further lung damage.
Individuals with sickle cell trait, although generally asymptomatic, can develop symptoms of sickling if exposed to very low oxygen pressures.
The Americans were unprepared for the very high pressures encountered in wells at relatively shallow depths and suffered some blowouts as a result.
Transients in pipe flow: wave celerity, slow and rapid valve closure, surge pressures in rigid and elastic pipes.
cesium iodide (CsI) at pressures up to 60 GPa.
Our youngsters are almost coerced into growing up far too fast and far too soon by some of the pressures and policies around them.
company>Pharmaceutical companies are familiar with outside pressures, and know there are concerns about how they frame their priorities.
crystallized at pressures 8 kbar from melts containing 1 -2 wt% water.
The foreign prisoners debacle has led to further pressures.
Equally, one must be conscious of the immense pressures that there are at present on budgets in all church denominations.
disintegrate under the pressures of growing up in the modern world.
dissipation of pore pressures, so tests are much longer than most undrained tests.
The pore water pressures under conditions of rapid drawdown are determined using the following procedure.
evolved to survive under a range of often extreme environmental pressures.
evolvegions also change, their practice and self-understanding evolving in response to internal and external pressures and debate.
These pressures have been largely unnoticed due to stock market exuberance.
Fluid inclusion studies will tell us about the pressures and temperatures of the pore fluid inclusion studies will tell us about the pressures and temperatures of the pore fluids during flow.
This trend has been reinforced by increasing globalization, which pressures states into conforming to the dictates of the international marketplace.
Measurements of the changing water pressures were made using hydrophones.
Typically such pumps are used where higher pressures are required than can be achieved with a single impeller.
inaugurated by the present government is supposed to reflect these pressures.
The root of the problem is intellectual incoherence, even more than constituency pressures.
External pressures, internal temptations so inescapable that we just can't sustain our faith?
krypton at higher pressures?
Did being the first senior black woman manger in the CPS create pressures for you?
Main air duct pressures were monitored using a water gage manometer.
The first advantage is that it does not cause narcosis, even at very high inspired partial pressures.
Section 4: Cuff Pressure Less than Diastolic Pressure At pressures below diastolic, the cuff does not occlude the artery.
occlusion of the artery prevents blood flow from contributing to the measured pressures.
Blood pressure in both arms - unequal blood pressures suggests proximal vascular occlusion.
occlusion alarm pressures.
experimental petrology and mineral stability at high temperatures and pressures.
The markets have been aware of inflationary pressures for some time.
Pencil type pressure gage (high ), for normal type tire pressure gage (high ), for normal type tire pressures.
remorseless pressures of the open market.
resilient enough to cope with the demands and pressures of police work.
The recent re-structuring within the UK retail sector has added to these pressures.
In the context of racially segregated America, the play looks inwards to explore the pressures upon family unity.
Brachial systolic and diastolic pressure and ankle systolic pressures were measured using a Hawksley random zero sphygmomanometer and Doppler probe.
Robson says it's an ideal stepping stone, a big club with small pressures.
subglacial water pressures.
For training needs to be totally subservient to service pressures would be inappropriate.
Plot curves of coating thickness, t versus line speed, v for the three different pressures.
Shorter rotations, earlier winter drilling, lower seed rates and less total inversion tillage inevitably mean growing pressures from the weed.
With this population distribution, increasing human numbers and mounting development pressures are taking a grim toll on coastal and near-shore resources.
tropopause pressures are evident over the same region as for the reported low ozone anomalies.
tyrem fitting low-profile tires to my car - what should the tire pressures be?
Due to a number of pressures, they often feel unable to talk about this to their parents.
Instruments of this kind have been in use for a long series of years, and have recorded pressures up to and even exceeding 60 lb per sq.
Chem., 1909, 6 9, p. 1 57), in a study of the dissociation isotherms over 300Ã‚°-850Ã‚°, detected molecules of Ss, S6 and S2, whilst S i appears to exist below pressures of 30 mm.
Chem., 1909, 42, p. 1839) obtained it by distilling the product of the interaction of chlorine and S 2 C1 2 at low pressures.
The curve was drawn by calculating the thermal efficiency from the above expression for various values of the initial temperature, keeping the final temperature constant at 673Ã‚°, and then plotting these efficiencies against the corresponding values of the gauge pressures.
In consequence of this increasing demand for power, higher boiler pressures are being used, in some cases 225 lb per sq.
A little vapour is given off at ordinary temperatures and pressures, and when under a few millimetres pressure only it rapidly vaporizes below IooÃ‚° C. The freezing-point is uncertain, owing perhaps to the existence of two modifications, as suggested by Kast (Zeits.
Much light has been thrown upon the variations of arterial and venous blood pressures by Karl Ludwig (1816-1895) and his many followers: by them not only the diseases of the circulatory system itself are elucidated, but also those of other systems - the nervous, for instance - which depend intimately on the mechanical integrity of the circulation of the blood as well as on the chemical integrity of the blood itself.
3754 of 1813) describes the closed vacuum pan and the air pump with condenser for steam by injection, the use of a thermometer immersed in the solution in the pan, and a method of ascertaining the density of the solution with a proof stick, and by observations of the temperature at which, while fluid and not containing grain, it could be kept boiling under different pressures shown by a vacuum gauge.
(iii.) If the vapour of A be readily soluble in liquid B, and the vapour of B sparingly soluble in liquid A, and if the vapour pressure of A be greater than that of B, then the vapour pressures of mixtures of A and B will continually diminish as one passes from 100% A to loo% B.
Experiments by Natanson on CO 2 at 17Ã‚° C. confirm those of Joule and Thomson, but show a slight increase of the ratio do/dp at higher pressures, which is otherwise rendered probable by the form of the isothermals as determined by Andrews and Amagat.
by taking advantage of the different rates of diffusion of the two gases; the solubility of air in water corresponds with the "law of partial pressures," each gas being absorbed in amount proportional to its pressure and coefficient of absorption, and oxygen being much more soluble than nitrogen (in the ratio of 04114 to 02035 at oÃ‚°); air expelled from water by boiling is always richer in oxygen.
In any case the position of the line of pressures is confined at the lead articulations within very narrow limits, and ambiguity as to the stresses is greatly diminished.
Anemometer observations show that pressures of 30 lb per sq.
In tornadoes, such as that at St Louis in 1896, it has been calculated, from the stability of structures overturned, that pressures of 45 to 90 lb per sq.
The planes of cleavage will be approximately perpendicular to the earth pressures which acted in the district; hence the strike of the cleavage (i.e.
from tangible pressures to other similar pressures in the external world.
Gases at high pressures fail to conform to Boyle's law, and solu tions at moderate concentrations give osmotic pressures which increase faster than the concentration.
The second of these essays opens with the striking remark, "There can scarcely be a doubt entertained respecting the reducibility of all elastic fluids of whatever kind, into liquids; and we ought not to despair of effecting it in low temperatures and by strong pressures exerted upon the unmixed gases"; further, after describing experiments to ascertain the tension of aqueous vapour at different points between 32Ã‚° and 212Ã‚° F., he concludes, from observations on the vapour of six different liquids, "that the variation of the force of vapour from all liquids is the same for the same variation of temperature, reckoning from vapour of any given force."
At higher pressures the effect of conduction was masked by convection currents.
His grandson, Loftus Perkins (1834-1891), most of whose life was spent in England, experimented with the application to steam engines of steam at very high pressures, constructing in 1880 a yacht, the "Anthracite," whose engines worked with a pressure of 500 th to the sq.
Thus the judgments " this sensible pressure exists," " that sensible pressure existed," " other similar pressures exist," " a conceivable centaur does not exist but is a figment," are all equally true, because they are in accordance with one or other of these kinds of knowledge.
37, p. 504, 1889) to give values of the total heat to to 6 calories too large between oÃ‚° and 40Ã‚° C. At low pressures and temperatures it is probable that saturated steam behaves very nearly as an ideal gas, and that the variation of the total heat is closely represented by Rankine's equation with the ideal value of S.
Regnault's formula for the total heat is here again seen to be inadmissible, as it would make the latent heat of steam vanish at about 870Ã‚° C. instead of at 365Ã‚° C. It should be observed, however, that the assumptions made in deducing the above formulae apply only for moderate pressures, and that the formulae cannot be employed up to the critical point owing to the uncertainty of the variation of the specific heats and the cooling effect Q at high pressures beyond the experimental range.
The agreement of the values of H with those of Griffiths and Dieterici at low temperatures, and of the values of p with those of Regnault over the whole range, are a confirmation of the accuracy of the foregoing theory, and show that the behaviour of a vapour like steam may be represented by a series of thermodynamically consistent formulae, on the assumption that the limiting value of the specific heat is constant, and that the isothermals are generally similar in form to those of other gases and vapours at moderate pressures.
The forces acting on the portion of liquid P 1 P 2 A 2 A 1 are - first, the horizontal pressures, - pgy i and z pgy 2; second, the surface-tension T acting at P i and P2 in directions inclined 01 and 0 2 to the horizon.
It forms a colourless syrup, of specific gravity 1.2485 (1 5Ã‚°/4Ã‚°), and decomposes on distillation under ordinary atmospheric pressure; but at very low pressures (about i mm.) it distils at about 85Ã‚° C., and then sets to a crystalline solid, which melts at about 18Ã‚° C. It possesses the properties both of an acid and of an alcohol.
For the sections of masonry dams actually used in practice, if designed on the condition that the centre of all vertical pressures when the reservoir is full shall be, as hereafter provided, at two-thirds the width of the base from the inner toe, the least sectional area for a density of 2 also has a vertical water face.
If now we assume the water to have a depth d above the base, the total water pressure represented by the triangle kbh will have its centre at d/3 from the base, and by the parallelogram of forces, assuming the density of the masonry to be 2.5, we find that the centre of pressure upon the base bc is shifted from the centre of the base to a point i nearer to the outer toe c, and adopting our assumption of uniformly varying intensity of stress, the rectangular diagram of pressures will thus be distorted from the figure bfgc to the figure of equal area bjlc, having its centre o vertically under the point at which the resultant of all the forces cuts the base bc. For any lower level the same treatment may, step by step, be adopted, until the maximum intensity of pressure cl exceeds the assumed permissible maximum, or the centre of pressure reaches an assigned distance from the outer toe c, when the base must be widened until the maximum intensity of pressure or the centre of pressure, as the case may be, is brought within the prescribed limit.
If oils and fats are treated with water alone under high pressure (corresponding to a temperature of about 220Ã‚° C.), or in the presence of water with caustic alkalis or alkaline earths or basic metallic oxides (which bodies act as "catalysers") at lower pressures, they are converted in the first instance into free fatty acids and glycerin.
The boiling point of water varies with pressure; thus at one atmosphere or 14.7 lb per square inch it is 212Ã‚° F., whereas at a pressure of 085 lb per square inch it is 32Ã‚°, and at lower pressures there is a still further fall in temperature.
Natural causes played their part, but so did the remorseless pressures of the open market.
You need to be resilient enough to cope with the demands and pressures of police work.
Robson says it 's an ideal stepping stone, a big club with small pressures.
Results suggest that the position of the terminus stream is sensitively dependent on subglacial water pressures.
Low tropopause pressures are evident over the same region as for the reported low ozone anomalies.
I'm fitting low-profile tires to my car - what should the tire pressures be?
Trends Much of the pressures on these vale landscapes are centered along the coast.
Sometimes even just having the rare opportunity to spend time away from the everyday pressures of running a business can catalyze more visionary thinking.
Young healthy cats may cope more easily with the pressures of the great outdoors.
Although these pressures were there growing up in a Greek family, they were relatively minor struggles.
Those conflicted individuals, in some cases have had their marriages end because of those cultural pressures.
If someone pressures you for personal information before you are ready to give it up you should quit communicating with them.
For young people, managing Sims as they go to work every day, clean up after themselves and achieve their goals is an experience in how to apply themselves to their own real life goals and pressures.
You'll have a chance to enjoy scrapbooking away from the pressures of everyday life.
Often pressures build throughout the day as you cope with the stress of family, work, finances and more.
Commuting in rush hour traffic, pressures of work, family life and mounting bills are common situations for many people today.
Find ways to measure stress and attitudes in employees and improve workplace conditions and pressures.
Coping with the responsibilities of family and work combined with the pressures of tight schedules and mounting bills just touches the surface of the many stressors in people's lives.
During the holidays, people are dealing with many expectations, pressures, monetary expenses, and long to-do lists.
He is feeling pressures at home to succeed, falling short and acting out behaviorally because of his disappointment in himself.
However, there are healthy ways of coping with the increased academic and social pressures that come with this big change in schools.
Just as the academic pressures mount for high school students, social issues tend to become more serious as students move into the teenage years.
They key, as always, is never to give in when someone pressures you to do something you aren't comfortable with.
Other sources of stress may include divorce, school pressures, or breaking up with a longtime boyfriend or girlfriend.
With all of the pressures of adolescence, many teenagers find it difficult to cope.
From classes to social pressures, some kids have difficulty making it through and decide to drop out.
A youth group is a safe haven for personal growth and making friendships without the pressures of drinking, drugs, or other hazardous behavior.
This makes it hard for students to escape the pressures of a difficult school life with cyber-bullying so rampant.
You drink to get relief from your personal life or professional pressures.
Social Pressures: Drinking with friends or loved ones can lead to alcohol abuse.
Met with the pressures of fame and fortune, Spears' life quickly became tabloid fodder.
In an attempt to remove him from the peer pressures of public school, his parents transferred him to Poseidon School, a private high school.
The public thrives on that type of gossip and loves to cluck their tongues at celebrities who fall to the pressures of daily living, proving they're no different than anyone else.
The pressures of Armstrong's cycling career coupled with his rising celebrity status tore the couple apart.
Even if you only have a small balcony, you can create a special get-away where you can hide from the pressures of everyday life.
With daily stress and pressures creeping up among all of us from time to time, it's great to find a company that believes in the power of positive thinking.
Vintage fabric and thread will have weakened over the decades and does not hold up long to the pressures of modern life.
The pressures of the industry triggered a health crisis caused by anorexia.
Freed from the pressures of daily work and child-rearing, people can focus on the needs of their bodies and find that keeping the body fit is good for the brain as well.
When stressed, your blood pressures goes up and when you eat salty foods it can have the same effect.
Giving a spa gift basket full of relaxing essentials is a great way to pamper the retiree as he or she enters a time of their life that is free from the stress of everyday work-related pressures.
Some mask designs only work with lower air pressures and they may leak when used with pressure settings of 15 or more.
If sleep apnea is diagnosed during the sleep study, the patient will have a second overnight sleep study during which a technician will try alternative pressures to determine the best pressure to stop the patient's apneas.
But the pressures bearing down on traditional toys are many.
Siblings may need to talk about the pressures they face, such as accepting the extra time and attention their parents must devote to a retarded brother or sister.
Eisenmenger's syndrome-A condition in which high pressures in the pulmonary arteries cause them to thicken.
Parents who listen attentively and provide support during difficult times give their children invaluable aid in coping with pressures.
Stepfamilies, increasingly referred to as "blended families," experience unique pressures within each new family unit.
The unit of measurement for this calculation is called a Montevideo unit, and ideally the sum total of the pressures should be between 150 and 250 Montevideo units to achieve cervical dilation.
Dissatisfied with the pressures and sacrifices of combining mothering with full-time work, many women have sought alternatives that allow them to relax the hectic pace of their lives but still maintain jobs and careers.
At normal atmospheric pressures, but breathing 100 percent oxygen, the half-life for the elimination of CO from the body is 50 to 70 minutes.
Children who have high self-esteem have an easier time handling conflicts, resisting negative pressures, and making friends.
Increases in family strains such as economic pressures or divorce may prompt teenagers to depend more on peers for emotional support.
The left ventricle operates at pressures about four times as high as the right ventricle.
One of the pressures of slow dancing is knowing how to be engaging.
When choosing a hair style for the wedding, brides must consider not only the regular aspects of hair care - length, texture, color, etc. - but also how the style will hold up under the pressures and excitement of that one special day.
The pressures of the life of a real estate agent vary based on the real estate and lending markets.
His theory is that the added financial pressures, child care duties, and scheduling dilemmas can overwhelm mothers with larger families.
According to Jennie, her marriage is the force that has helped her cope with the pressures of acting.
In addition to societal pressures and prejudices, interracial couples still face other challenges associated with their union.
There are many benefits to online dating including allowing people to meet someone without the pressures that come from meeting in person.
Lately, I am beginning to feel the pressures of sustaining a long-distance relationship.
Every girl has an idea of what makes a good boyfriend and you are no exception; he is sweet, never pressures me and calls everyday to talk and hear my voice.
Nobody is perfect, and dating is full of lots of pressures.
If you love to write, but are intimidated by the daily deadline pressures associated with major newspapers, you may be wondering how to become a magazine journalist.
The lunch bag can also double as a "Mommy Item," with its compartments for baby bottles, as well as withstand the pressures of bus, bicycle, and foot travel.
Between dealing with work pressures, stresses at home, and the rigors of parenting, even the best parents lose their cool sometimes.
Kids love to fit in and find it easier to make friends when the pressures to look a certain way are set aside.
The pressures can be relentless, and finding a silver lining in the clouds of worry that fill your days can be difficult.
How else are you able to navigate the challenges and pressures of school, family, friends and dating?
The kids are far more media savvy than their parents, but still face the same pressures and temptations of being a teenager.
Dream a Little Dream of Me - The season opened with new arrivals and new pressures as Seattle Grace falls in national rankings.
Engineered with high performance stainless steel, this dynamic diver's watch withstands pressures of 150 atmospheres under water, corresponding to a depth of 1,500 meters or 5,000 feet.
This watch withstands pressures of up to 300 atmospheres underwater, corresponding to a depth of 3,000 meters or 10,000 feet.
Three years later, a professional diver from Hiroshima contacted Seiko requesting a watch that could withstand the tremendous pressures and stresses of saturation dives to 350 meters.
Often, in the rush to get necessary services, the pressures felt by their family members go unnoticed.
As the economic pressures build, there is a greater tendency for employers to fall into the pitfalls of discrimination, especially towards certain ethnic groups and backgrounds.
Teens often skimp on sleep due to pressures from school and social life.
The pressures of Hollywood can be severe.
As body image becomes more of an issue for everybody and men are under similar pressures as women to maintain a certain look, men's shapewear has become more mainstream and less something only a fetishist might use.
Frischmann also broke up with Albarn, adding personal pressures to the band's eminent breakup.
Frusicante briefly quit the band as they rose to prominence in the late 1980s and early 1990s, unwilling to deal with the pressures of fame.
The pressures of deadlines and budget constraints contribute to what is often a tense atmosphere, but there are also many celebrations and feel-good moments when things are going well.
After delivering a shaky performance that others have blamed on her nerves and the building pressures from the media, she came back and sang a flawless and moving version of the same song she did for her audition.
Through this reality show, viewers were supposed to get a look at the pressures women face around the world to feel beautiful while Simpson herself confronted her own issues.
Simpson and friends take a look at the pressures facing high fashion models during fashion week in Paris.
In Morocco, the cast explores the competing pressures of fashion and religion.
During season two, Farrah also deals with financial pressures and faces the reality of Sophia's father's death.
At the time our story starts, there has been peace between humans and Kzin for some time, and societal pressures are building among the Kzinti, yet some radicals wonder if war is worth the cost.
At lower pressures the green line 4922 becomes more conspicuous.
Compound working permits of a greater range of expansion than is possible with a simple engine, and incidentally there is less range of pressure per cylinder, so that the pressures and temperatures per cylinder have not such a wide range of variation.
It is often taught that gneisses are the further stages of the crystallization of schists and belong to a deeper zone where the pressures and the temperatures were greater.
It should be pointed out that no measurements on osmotic pressures or freezing points can do more than tell us that an excess of particles is present; such experiments can throw no light on the question whether or not those particles are electrically charged.
Among other subjects at which he subsequently worked were the absorption of gases in blood (1837-1845), the expansion of gases by heat (1841-1844), the vapour pressures of water and various solutions (1844-1854), thermo-electricity (1851), electrolysis (1856), induction of currents (1858-1861), conduction of heat in gases (1860), and polarization of heat (1866-1868).
Important experiments on the susceptibility of oxygen at different pressures and temperatures were carried out by P. Curie (C.R.
Whether the necessary forces are due to aerial pressures acting on the rear, or to forces directly impressed from without, is a matter of indifference.
Under different pressures the relative amounts of the combustion products vary considerably.
Under very great pressures carbon monoxide, steam and nitrogen are the main products, but nitric oxide never quite disappears.
A little vapour is given off at ordinary temperatures and pressures, and when under a few millimetres pressure only it rapidly vaporizes below Ioo° C. The freezing-point is uncertain, owing perhaps to the existence of two modifications, as suggested by Kast (Zeits.
With changes of the pressures of the blood in arteries, veins or capillaries, and in the heart itself and its respective chambers, static changes are apt to follow in these parts; such as degeneration of the coats of the arteries, due either to the silent tooth of time, to persistent high blood pressures, or to the action of poisons such as lead or syphilis.
And on the influence of these inconspicuous bodies and of the pituitary body in sustaining arterial blood pressures physiologists have thrown some important light.
For high heads the water cylinders, valves and valve chambers are specially constructed to withstand heavy pressures, water being sometimes raised in a single lift to heights of more than 2000 ft.
At such pressures all but the strongest rocks will be strained beyond their limit of elasticity.
This theorem was published in 1643, at the end of his treatise De motu gravium projectorum, and it was confirmed by the experiments of Raffaello Magiotti on the quantities of water discharged from different ajutages under different pressures (1648).
With uniform temperature, taking h constant in the gas-equation, dp / dz= =p / k, p=poet/ k, (9) so that in ascending in the atmosphere of thermal equilibrium the pressure and density diminish at compound discount, and for pressures p 1 and 1, 2 at heights z 1 and z2 (z1-z2)11?
The mixture consequently distils at the temperature at which the sum of the partial pressures equals that of the atmosphere.
If M 1, M2, and P 1, P 2 be the molecular weights and vapour pressures of the components A and B, then the ratio of A to B in the distillate is M 1 P 1 /M 2 P 2.
The vapour pressure composition curve will be convex to the axis of compositions, the maximum vapour pressures corresponding to pure A and pure B, and the minimum to some mixture of A and B.
It was not till the autumn of 1894 that an efficient launching apparatus was devised, and then the wings were found not to be strong enough to bear the pressures to which they were subjected.
An ideal gas is a substance possessing very simple thermodynamic properties to which actual gases and vapours appear to approximate indefinitely at low pressures and high temperatures.
It is found by experiment that the change of pv with pressure at moderate pressures is nearly proportional to the change of p, in other words that the coefficient d(pv)/dp is to a first approximation a function of the temperature only.
This coefficient is sometimes called the " angular coefficient," and may be regarded as a measure of the deviations from Boyle's law, 'which may be most simply expressed at moderate pressures by formulating the variation of the angular coefficient with temperature.
This equation is practically identical for moderate pressures with that devised by Clausius (Phil.
Experiments by Natanson on CO 2 at 17° C. confirm those of Joule and Thomson, but show a slight increase of the ratio do/dp at higher pressures, which is otherwise rendered probable by the form of the isothermals as determined by Andrews and Amagat.
The simplest assumption which suffices to express the small deviations of gases and vapours from the ideal state at moderate pressures is that the coefficient a in the expression for the capillary pressure varies inversely as some power of the absolute temperature.
The introduction of the covolume, b, into the equation is required in order to enable it to represent the behaviour of hydrogen and other gases at high temperatures and pressures according to the experiments of Amagat.
Zeuner's formula for steam), but they cannot be made to represent with sufficient approximation the deviations from the ideal state at moderate pressures and generally lead to erroneous results.
The general nature of the phenomena is thus easily understood; but it is at a maximum at pressures comparable with a millimetre of mercury, at which the free path is still small, the greater number of molecules operating in intensifying the result.
The influence of wind and tide breaks up the frozen surface of the sea, and sheets yielding to the pressures slide over or under one another and are worked together into a hummocky ice-pack, the irregularities on the surface of which, caused by repeated fractures and collisions, may be from 10 to 20 ft.
They found that if liquid acetylene in a steel bottle be heated at one point by a platinum wire raised to a red heat, the whole mass decomposes and gives rise to such tremendous pressures that no cylinder would be able to withstand them.
These pressures varied from 71,000 to ioo,000 lb.
Continuing these experiments, they found that in acetylene gas under ordinary pressures the decomposition brought about in one portion of the gas, either by heat or the firing in it of a small detonator, did not spread far beyond the point at which the decomposition started, while if the acetylene was compressed to a pressure of more than 30 lb on the square inch, the decomposition travelled throughout the mass and became in reality detonation.
When acetylene is burnt from a 000 union jet burner, at all ordinary pressures a smoky flame is obtained, but on the pressure being increased to 4 inches a magnificent flame results, free from smoke, and developing an illuminating value of 240 candles per 5 cubic feet of gas consumed.
At barometric pressures such as exist between 18 and 36 kilometres above the ground the mobility of the ions varies inversely as the pressure, whilst the coefficient of recombination a varies approximately as the pressure.
From 1879 to 1888 he was engaged on difficult experimental investigations, which began with an inquiry into the corrections required, owing to the great pressures to which the instruments had been subjected, in the readings of the thermometers employed by the "Challenger" expedition for observing deep-sea temperatures, and which were extended to include the compressibility of water, glass and mercury.
Similarly there is a difference of opinion as to the conditions under which the organisms have been mineralized, some holding that the process has taken place at a high temperature and under great pressure; but the lack of practical evidence in nature in support of these views has led many to conclude that petroleum, like coal, has been formed at moderate temperatures, and under pressures varying with the depth of the containing rocks.
Obviously, therefore, liquids are comparable when the pressures, volumes and temperatures are equal fractions of the critical constants.
Rhyolitic lavas frequently are more or less vitreous, and when the glassy matter greatly predominates and the; crystals are few and inconspicuous the rock becomes an obsidian; the chemical composition is essentially the same as that of granite; the difference in the physical condition of the two rocks is due to the fact that one consolidated at the surface, rapidly and under low pressures, while the other cooled slowly at great depths and under such pressures that the escape of the steam and other gases it contained was greatly impeded.
The freezing points and vapour pressures of solutions of sugar are also in conformity with the theoretical numbers.
But when we pass to solutions of mineral salts and acids - to solutions of electrolytes in fact - we find that the observed values of the osmotic pressures and of the allied phenomena are greater than the normal values.
Soc. Proc., 1902, T 1, 49, 39) in oxygen, hydrogen and air at low pressures, and by C. D.
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