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gases

gases Sentence Examples

  • Many of the well-waters contain gases; thus the town of Roma is lighted by natural gas which escapes from its well.

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  • Travers, The Study of Gases (1901).

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  • He also carried out many experiments in magneto-optics, and succeeded in showing, what Faraday had failed to detect, the rotation under the influence of magnetic force of the plane of polarization in certain gases and vapours.

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  • "He'd been dead for at least two days, then, long enough for rigor to set in and the body to start releasing gases," Wynn said.

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  • Stomata are often absent, absorption and excretion of gases in solution being carried on through the epidermal layer.

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  • This phenomenon is connected with the fact that incandescent bodies, especially in rarefied gases, throw off or emit electrons or gaseous negative ions.

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  • 1872), who from 1894 had assisted him at University College, London, and in 1903 was appointed professor of chemistry at University College, Bristol, enabled him to announce the existence in the atmosphere of three new gases, neon, krypton and xenon.

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  • Trans., 18 53, p. 357, 18 54, p. 321, and 1862, p. 579) showed that the statement that no internal work is done when a gas expands or contracts is not quite true, but the amount is very small in the cases of those gases which, like oxygen, hydrogen and nitrogen, can only be liquefied by intense cold and pressure.

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  • They are without stomata on their submerged portions, and the entry of gases can only take place by diffusion from the water through their external cells, which are not cuticularized.

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  • 1610), chefly famous for his Opera Omnia Medicochymica (1595); Jean Baptiste van Helmont (1577-1644), celebrated for his researches on gases; F.

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  • Scholars today are pretty sure that in the case of Delphi, the oracle was inadvertently breathing gases that rose from the cave in which she sat.

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  • equal changes in temperature and pressure occasion equal changes in equal volumes of all gases and vapours - Avogadro deduced the law: Under the same conditions of temperature and pressure, equal volumes of gases contain equal numbers of molecules; and he showed that the relative weights of the molecules are determined as the ratios of the weights of equal volumes, or densities.

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  • Dalton believed that the molecules of the elementary gases consisted each of one atom; his diagram for hydrogen gas makes the point clear.

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  • The following branches have especially felt his influence: - chemical physics, capillarity and viscosity, theory of gases, flow of liquids, photography, optics, colour vision, wave theory, electric and magnetic problems, electrical measurements, elasticity, sound and hydrodynamics.

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  • They have made this observation the basis of a practical method of separating helium from the other inert gases.

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  • The entry of gases into, and exit from, the cells, as well as the actual exhalation of watery vapour from the latter, take place in the intercellular space system of which the stomata are the outlets.

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  • They are impervious to water and gases.

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  • At low temperatures SA predominates, but as the temperature is raised S, increases; the transformation, however, is retarded by some gases, e.g.

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  • Gases formerly considered to be identical came to be clearly distinguished, and many new ones were discovered.

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  • There he continued his researches on the discharge of electricity in rarefied gases, only just missing the discovery of the X-rays described by W.

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  • In the preface he states the position that "whenever, then, two gases are allowed to mix without the performance of work, there is dissipation of energy, and an opportunity of doing work at the expense of low temperature heat has been for ever lost."

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  • During the three years he held this position he carried out researches on the contact of elastic solids, hardness, evaporation and the electric discharge in gases, the last earning him the special commendation of Helmholtz.

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  • Dalton, who was a mathematical physicist even more than a chemist, had given much thought to the study of gases.

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  • necessary to determine the specific gravities of the various gases referred to some one of them, say hydrogen; the numbers so obtained giving the weights of the molecules referred to that of the hydrogen molecule.

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  • At atmospheric pressure the discharge is able to pass through a far greater distance in helium than in the common gases.

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  • 108; see also Liquid Gases).

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  • It also occurs in blast-furnace gases.

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  • Boron fluoride also combines with ammonia gas, equal volumes of the two gases giving a white crystalline solid of composition BF 3 NH 3 i with excess of ammonia gas, colourless liquids BF 3.2NH 3 and BF 3.3NH 3 are produced, which on heating lose ammonia and are converted into the solid form.

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  • In 1875 Lord Rayleigh published an investigation on "the work which may be gained during the mixing of gases."

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  • In the experiment imagined by Lord Rayleigh a porous diaphragm takes the place of the partition and trap-doors imagined by Clerk Maxwell, and the molecules sort themselves automatically on account of the difference in their average velocities for the two gases.

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  • When the pressure on one side of the diaphragm thus becomes greater than that on the other, work may be done at the expense of heat in pushing the diaphragm, and the operation carried on with continual gain of work until the gases are uniformly diffused.

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  • The only pathways for the gases which thus pass between the cells of the mesophyll and the outside air are the stomata.

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  • But these protective layers are in the main impermeable by gases and by either liquid or vapour, and prevent the access of either to the protoplasts which need them.

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  • Investigations carried out by Blackman, and by Brown and Escombe, have shown clearly that the view put forward by Boussingault, that such absorption of gases takes place through the cuticular covering of the younger parts of the plant, is erroneous and can no longer be supported.

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  • This power of varying the area of the apertures by which gases enter the internal reservoirs is not advantageous to the gaseous interchangesindeed it may be directly the reverse.

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  • The procedure consists in most cases in spraying the affected plants with poisonous solutions or emulsions, or in (lusting them with fungicidal or insecticidal powders, or applying the fumes of lethal gases.

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  • Care and intelligence are especially needful with certain insecticides such as poisonous gases, or the operators may suffer.

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  • Submerged leaves are usually filamentous or narrowly ribbonshaped, thus exposing a large amount of surface to the water, some of the dissolved gases of which they must absorb, and into which they must also excrete certain gases.

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  • - One pound of good Welsh coal properly burned in the fire-box of a locomotive yields about 15,000 British thermal units of heat at a temperature high enough to enable from 50 to 80% to flow across the boiler-heating surface to the water, the rest escaping up the chimney with the furnace gases.

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  • The difference of pressure between the outside air and the smoke-box gases may be measured by the difference of the water levels in the limbs of a U tube, one limb being in communication with the smokebox, the other with the atmosphere.

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  • He initiated in 1866 the spectroscopic observation of sunspots; applied Doppler's principle in 1869 to determine the radial velocities of the chromospheric gases; and successfully investigated the chemistry of the sun from 1872 onward.

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  • (3) The effect of change of volume against external pressure (due to production or consumption of mechanical energy) may be neglected in the case of solids, liquids or solutions, but must usually be taken into account when gases are dealt with.

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  • In the newer type (which was first proposed by Andrews for the combustion of gases) the chemical action takes place in a completely closed combustion chamber of sufficient strength to resist the pressure generated by the sudden action, which is often of explosive violence.

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  • To withstand the chemical action of the gases, the " calorimetric bomb " is lined either with platinum, as in Berthelot's apparatus, or with porcelain, as in Mahler's.

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  • There he made the acquaintance of Thomas Andrews, whom he joined in researches on the density of ozone and the action of the electric discharge on oxygen and other gases, and by whom he was introduced to Sir W.

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  • But his theological writings are forgotten, and he is chiefly remembered as a scientific investigator who contributed especially to the chemistry of gases.

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  • Arago, with whom he had already carried out investigations on the refractive properties of different gases, in the measurement of an arc of the meridian in Spain, and in subsequent years he was engaged in various other geodetic determinations.

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  • It may be more conveniently prepared by passing the vapour of sulphur over red hot charcoal, the unccndensed gases so produced being led into a tower containing plates over which a vegetable oil is allowed to flow in order to absorb any carbon bisulphide vapour, and then into a second tower containing lime, which absorbs any sulphuretted hydrogen.

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  • Like most of the other metals of the group, it absorbs gases.

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  • To the physicist matter is presented in three leading forms - solids, liquids and gases; and although further subdivisions have been rendered necessary with the growth of knowledge the same principle is retained, namely, a classification based on properties having no relation to composition.

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  • At all times the air had received attention, especially since van Helmont made his far-reaching investigations on gases.

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  • The first step in this direction was effected by the co-ordination of Gay Lussac's observations on the combining volumes of gases.

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  • He discovered that gases always combined in volumes having simple ratios, and that the volume of the product had a simple ratio to the volumes of the reacting gases.

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  • While successfully investigating the solid elements and their compounds gravimetrically, Berzelius was guilty of several inconsistencies in his views on gases.

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  • He denied that gaseous atoms could have parts, although compound gases could.

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  • A second inconsistency was presented when he was compelled by the researches of Dumas to admit Avogadro's hypothesis; but here he would only accept it for the elementary gases, and denied it for other substances.

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  • The elements are usually divided into two classes, the metallic and the non-metallic elements; the following are classed as non-metals, and the remainder as metals: Of these hydrogen, chlorine, fluorine, oxygen, nitrogen, argon, neon, krypton, xenon and helium are gases, bromine is a liquid, and the remainder are solids.

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  • The molecule of every compound must obviously contain at least two atoms, and generally the molecules of the elements are also polyatomic, the elements with monatomic molecules (at moderate temperatures) being mercury and the gases of the argon group. The laws of chemical combination are as follows: I.

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  • There is a fourth law of chemical combination which only applies to gases.

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  • This law states that: - gases combine with one another in simple proportions by volume, and the volume of the product (if gaseous) has a simple ratio to the volumes of the original mixtures; in other words, the densities of gases are simply related to their combining weights.

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  • One other instance may be given; the equation 2NH3=N2+3H2 represents the decomposition of ammonia gas into nitrogen and hydrogen gases by the electric spark, and it not only conveys the information that a certain relative weight of ammonia, consisting of certain relative weights of hydrogen and nitrogen, is broken up into certain relative weights of hydrogen and nitrogen, but also that the nitrogen will be contained in half the space which contained the ammonia, and that the volume of the hydrogen will be one and a half times as great as that of the original ammonia, so that in the decomposition of ammonia the volume becomes doubled.

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  • The 18th century witnessed striking developments in pneumatic chemistry, or the chemistry of gases, which had been begun by van Helmont, Mayow, Hales and Boyle.

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  • A masterly device, initiated by him, was to collect gases over mercury instead of water; this enabled him to obtain gases previously only known in solution, such as ammonia, hydrochloric acid, silicon fluoride and sulphur dioxide.

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  • 648) burns the substance in oxygen, conducts the gases over platinized sand, and collects the products in suitable receivers.

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  • The limiting law expressing the behaviour of gases under varying temperature and pressure assumes the form pv= RT; so stated, this law is independent of chemical composition and may be regarded as a true physical law, just as much as the law of universal gravitation is a true law of physics.

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  • Of considerable importance, also, are the properties of solids, liquids and gases in solution.

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  • This is readily illustrated by considering the properties of gases - the simplest state of aggregation.

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  • According to the law of Avogadro, equal volumes of different gases under the same conditions of temperature and pressure contain equal numbers of molecules; therefore, since the density depends upon the number of molecules present in unit volume, it follows that for a comparison of the densities of gases, the determinations must be made under coincident conditions, or the observations reduced or re-computed for coincident conditions.

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  • This equation, which is mathematically deducible from the kinetic theory of gases, expresses the behaviour of gases, the phenomena of the critical state, and the behaviour of liquids; solids are not accounted for.

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  • It is found that mercury vapour, helium, argon and its associates (neon, krypton, &c.) have the value 1.67; hence we conclude that these gases exist as monatomic molecules.

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  • Oxygen, nitrogen, hydrogen and carbon monoxide have the value 1.4; these gases have diatomic molecules, a fact capable of demonstration by other means.

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  • In the more complex gases the specific heat varies considerably with temperature; only in the case of monatomic gases does it remain constant.

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  • Laplace is due the theoretical proof that this function is independent of temperature and pressure, and apparent experimental confirmation was provided by Biot and Arago's, and by Dulong's observations on gases and vapours.

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  • P. Dale; the more simple formula (n - i)/d, which remained constant for gases and vapours, but exhibited slight discrepancies when liquids were examined over a wide range of temperature, being adopted.

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  • Ramsay and Shields suggested that there exists an equation for the surface energy of liquids, analogous to the volume-energy equation of gases, PV = RT.

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  • The process was developed by Madame Lefebre in 1859; by Meissner in 1863, who found that moist gases gave a better result; and by Prim in 1882, who sparked the gases under pressure; it was also used by Lord Rayleigh in his isolation of argon.

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  • The first product of the reaction is nitric oxide, which on cooling with the residual gases produces nitrogen peroxide.

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  • The cooled gases are then led into towers where they meet a stream of water coming in the contrary direction.

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  • long or more, is formed in a long tube, and the gases are sent round the arc by obliquely injecting them.

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  • In de Lambilly's process air and steam is led over white-hot coke, and carbon dioxide or monoxide removed from the escaping gases according as ammonium formate or carbonate is wanted.

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  • Lord Rayleigh in 1894 found that the density of atmospheric nitrogen was about 2% higher than that of chemically prepared nitrogen, a discovery which led to the isolation of the rare gases of the atmosphere.

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  • The first four oxides are gases, the fifth is a solid.

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  • Sodium nitrite, the most commonly used salt of the acid, is generally obtained by heating the nitrate with metallic lead; by heating sodium nitrate with sulphur and sodium hydroxide, the product then being fractionally crystallized;(Read, Holliday & Sons): 3NaNO 3 +S+2NaOH = Na2S04+3NaN02+H20; by oxidizing atmospheric nitrogen in an electric arc, keeping the gases above 300° C., until absorption in alkaline hydroxide solution is effected (German Pat.

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  • Nitrosyl chloride, NOC1, is obtained by the direct union of nitric oxide with chlorine; or by distilling a mixture of concentrated nitric and hydrochloric acids, passing the resulting gases into concentrated sulphuric acid and heating the so-formed nitrosyl hydrogen sulphate with dry salt: HN03+3HCl=NOC1+C12 +H 2 O; NOC1 + H2S04 = HCl + NO SO 4 H; NO SO 4 H + NaC1 = Noci+NaHS04 (W.

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  • 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.

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  • If the plates be covered with a deposit of platinum black, in which the gases are absorbed as fast as they are produced, the minimum decomposition point is 1.07 volt, and the process is reversible.

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  • Our views of the nature of the ions of electrolytes have been extended by the application of the ideas of the relations between matter and electricity obtained by the study of electric conduction through gases.

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  • 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).

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  • A stick of green wood is forced into it, and the vapours and gases set free expose new surfaces to the air, which at this temperature has only a mildly oxidizing effect.

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  • But it was discovered by Faraday in 1845 that all substances, including even gases, are either attracted or repelled by a sufficiently powerful magnetic pole.

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  • Phys., 1900, 2, 798) observed a well-defined Hall effect in incandescent gases.

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  • Another heat test, that of Will, consists in heating a weighed quantity of the guncotton in a stream of carbon dioxide to 130° C., passing the evolved gases over some red-hot copper, and finally collecting them over a solution of potassium hydroxide which retains the carbon dioxide and allows the nitrogen, arising from the guncotton decomposition, to be measured.

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  • In mining operations explosives are used on a large scale and the powder gases contain large quantities of the very poisonous gas, carbon monoxide, a small percentage of which may cause death, and even a minute percentage of which in the air will seriously affect the health.

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  • The gases produced by such fire-damp or dust explosions contain carbon dioxide and carbon monoxide in large proportion, and the majority of the deaths from such explosions are due to this " after-damp " rather than to the explosion itself.

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  • It did excellent service in the hands of Graham for the extraction of gases occluded in metals.

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  • For the production of high vacua, see Vacuum Tube; Liquid Gases.

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  • The crucibles or pots used for the production of optical glass very closely resemble those used in the manufacture of flint glass for other purposes; they are " covered " and the molten materials are thus protected from the action of the furnace gases by the interposition of a wall of fireclay, but as crucibles for optical glass are used for only one fusion and are then broken up, they are not made so thick and heavy as those used in flint-glass making, since the latter remain in the furnace for many weeks.

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  • "Black damp" consists of accumulations of irrespirable gases, mostly nitrogen, which cause the lights to burn dimly, and the term "white damp" is sometimes applied to carbon monoxide.

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  • The bagasse so used is now commonly taken straight from the cane mill to furnaces specially designed for burning it, in its moist state and without previous drying, and delivering the hot gases from it to suitable boilers, such as those of the multitubular type or of the water-tube type.

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  • of zinc enough sulphur is liberated to produce one ton of strong sulphuric acid, and unless this is collected not only are poisonous gases discharged, but the waste is considerable.

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  • When sulphuric or sulphurous acid is to be collected, it is important to keep the fuel gas from admixture with the sulphur gases, and kilns for this purpose require some modification.

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  • (c) Natural gas is piped to the furnace, where it meets air heated by the chimney gases.

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  • - These compounds possess properties very similar to those of ammonia, the lowest members of the series being combustible gases readily soluble in water.

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  • water free from salts and to some extent of the dissolved gases which are always present in natural waters, is of indispensable value in many operations both of scientific and industrial chemistry.

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  • The first portion of the distillate brings over the gases dissolved in the water, ammonia and other volatile impurities, and is consequently rejected; scarcely two-fifths of the entire quantity of water can be safely used as pure distilled water.

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  • The water, moreover, till it is saturated with gases, readily absorbs noxious vapours to which it may be exposed.

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  • In ancient times meteors were supposed to be generated in the air by inflammable gases.

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  • The first volume, Vegetable Staticks (1727), contains an account of numerous experiments in plant-physiology - the loss of water in plants by evaporation, the rate of growth of shoots and leaves, variations in root-force at different times of the day, &c. Considering it very probable that plants draw "through their leaves some part of their nourishment from the air," he undertook experiments to show in "how great a proportion air is wrought into the composition of animal, vegetable and mineral substances"; though this "analysis of the air" did not lead him to any very clear ideas about the composition of the atmosphere, in the course of his inquiries he collected gases over water in vessels separate from those in which they were generated, and thus used what was to all intents and purposes a "pneumatic trough."

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  • Hydrogen and oxygen may also be produced electrolytically as gases, and their respective reducing and oxidizing powers at the moment of deposition on the electrode are frequently used in the laboratory, and to some extent industrially, chiefly in the field of organic chemistry.

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  • In general, gases dissolve in it more readily than in water; loo volumes of alcohol dissolve 7 volumes of hydrogen, 25 volumes of oxygen and 16 volumes of nitrogen.

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  • For a very complete set of tables of dielectric constants of solids, liquids and gases see A.

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  • They show that the dielectric constant of a liquid generally undergoes great reduction in value when the liquid is frozen and reduced to a low temperature.1 The dielectric constants of gases have been determined by L.

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  • [[Table Iv]].-Dielectric Constants (K) of Gases at '15°' C. and 760 mm.

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  • He also showed that the difference of the specific heats at constant pressure and volume, S - s, must be the same for equal volumes of all gases at the same temperature and pressure, being represented by the expression R/TF'(t).

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  • He remarks that ” the law according to which the motive power of heat varies at different points of the thermometric scale is intimately connected with that of the variations of the specific heats of gases at different temperatures - a law which experiment has not yet made known to us with sufficient exactness."

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  • This most fundamental point was finally settled by a more delicate test, devised by Lord Kelvin, and carried out in conjunction with Joule (1854), which showed that the fundamental assumption W =H in isothermal expansion was very nearly true for permanent gases, and that F'(t) must therefore vary very nearly as J/T.

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  • 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.

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  • If we also assume that they are constant with respect to temperature (which does not necessarily follow from the characteristic equation, but is generally assumed, and appears from Regnault's experiments to be approximately the case for simple gases), the expressions for the change of energy or total heat from 00 to 0 may be written E - Eo = s(0 - 0 0), F - Fo = S(0-00).

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  • Deviations of Actual Gases from the Ideal State.

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  • - Since no gas is ideally perfect, it is most important for practical purposes to discuss the deviations of actual gases from the ideal state, and to consider how their properties may be thermodynamically explained and defined.

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  • - William Thomson (Lord Kelvin), who wars the first to realize the importance of the absolute scale in thermodynamics, and the inadequacy of the test afforded by Boyle's law or by experiments on the constancy of the specific heat of gases, devised a more delicate and practical test, which he carried out successfully in conjunction with Joule.

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  • As the result of their experiments on actual gases (air, hydrogen, and C02), Joule and Thomson (Phil.

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  • 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.

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  • It is probably less than 2 for air and the more perfect gases.

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  • 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.

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  • In the case of imperfect gases, all the available experimental evidence shows that the specific volume tends towards its ideal value, V =Re/p, in the limit, when the pressure is indefinitely reduced and the molecules are widely separated so as to eliminate the effects of their mutual actions.

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  • The action is not properly understood; it may be due to the reducing gases (hydrogen, hydrocarbons, &c.) which are invariably present in wood charcoal.

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  • Condensation of gases >>

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  • Warburg in 1875 on the viscosity of gases; its effects would be corrected for, in general, by a slight effective addition to the thickness of the gaseous layer.

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  • In commerce, however, other expressions are met with, as, for example, "pounds per cubic foot" (used for woods, metals, &c.), "pounds per gallon," &c. The standard substances employed to determine relative densities are: water for liquids and solids, and hydrogen or atmospheric air for gases; oxygen (as 16) is sometimes used in this last case.

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  • In expressing the absolute or relative density of any substance, it is necessary to specify the conditions for which the relation holds: in the case of gases, the temperature and pressure of the experimental gas (and of the standard, in the case of relative density); and in the case of solids and liquids, the temperature.

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  • It is customary to reduce gases to the so-called "normal temperature and pressure," abbreviated to N.T.P., which is o° C. and 769 mm.

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  • The relative densities of gases are usually expressed in terms of the standard gas under the same conditions.

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  • The density gives very important information as to the molecular weight, since by the law of Avogadro it is seen that the relative density is the ratio of the molecular weights of the experimental and standard gases.

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  • The determination of the absolute densities of gases can only be effected with any high degree of accuracy by a development of this method.

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  • Travers, The Study of Gases.

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  • Lord Rayleigh has made many investigations of the absolute densities of gases, one of which, namely on atmospheric and artificial nitrogen, undertaken in conjunction with Sir William Ramsay, culminated in the discovery of argon.

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  • The density of gases is treated in M.

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  • Travers, The Experimental Study of Gases (1901); and vapour density determinations in Lassar-Cohn's Arbeitsmethoden fur organisch-chemische Laboratorien (1901), and Manual of Organic Chemistry (1896), and in H.

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  • The water of the ocean, like any other liquid, absorbs a certain amount of the gases with which it is in contact, and thus sea-water contains dissolved oxygen, nitrogen and carbonic acid absorbed from the atmosphere.

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  • As Gay-Lussac and Humboldt showed in 1805, gases are absorbed in less amount by a saline solution than by pure water.

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  • The first useful determinations of the dissolved gases of sea-water were made by Oskar Jacobsen in 1872.

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  • The former determination is made by driving out the dissolved gases from solution and collecting them in a Torricellian vacuum, where the volume is measured after the carbonic acid has been removed.

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  • Fox, of the Central Laboratory of the International Council at Christiania, has investigated the relation of the atmospheric gases to sea-water by very exact experimental methods and arrived at the following expressions for the absorption of oxygen and nitrogen by sea-water of different degrees of concentration.

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  • 4282 t +0 0074527 t20.0000-5494 t3 Cl(o 2149 - o o07117 / 2 +0.0000931 13) In the case of ocean water with a salinity of 35 per mille, this gives for saturation with atmospheric gases in cc. per litre: The reduction of the absorption of gas by rise of temperature is thus seen to be considerable.

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  • As a rule the amount of both gases dissolved in sea-water is found to be that which is indicated by the temperature of the water in situ.

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  • Gases, consisting principally of light carburetted hydrogen or marsh gas, are of ten present in considerable quantity in coal, in a dissolved or occluded state, and the evolution of these upon exposure to the air, especially when a sudden diminution of atmospheric pressure takes place, constitutes one of the most formidable dangers that the coal miner has to encounter.

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  • Underground boilers placed near the up-cast pit so that the smoke and gases help the ventilating furnace have been largely used but are now less favourably regarded than formerly.

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  • One of the most important branches of colliery work is the management of the ventilation, involving as it does the supply of fresh air to the men working in the pit, as well as the removal of inflammable gases that may be given off by the coal.

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  • The return air from fiery workings is never allowed to approach the furnace, but is carried into the upcast by a special channel, called a dumb drift, some distance above the furnace drift, so as not to come in contact with the products of combustion until they have been cooled below the igniting point of fire-damp. Where the upcast pit is used for drawing coal, it is usual to discharge the smoke and gases through a short lateral drift near the surface into a tall chimney, so as to keep the pit-top as clear as possible for working.

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    0
  • generally in South Staffordshire, the coals are suffi ciently free from gas, or rather the gases are not liable to become explosive when mixed with air, to allow the use of naked lights, candles being generally used.

    0
    0
  • Where the gases are fiery, the use of protected lights or safety lamps (q.v.) becomes a necessity.

    0
    0
  • The nature of the gases evolved by coal when freshly exposed to the atmosphere has been investigated by several chemists, more particularly by Lyon Playfair and Ernst von Composi- Meyer.

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    0
  • The latter observer found the gases given off tion of gas by coal from the district of Newcastle and Durham evolved by to contain carbonic acid, marsh gas or light carburetted coal.

    0
    0
  • Thomas, of the gases dissolved or occluded in coals from South Wales basin shows them to vary considerably with the class of coal.

    0
    0
  • The gases from the bituminous house coals of South Wales are comparatively free from marsh gas, as compared with those from the steam coal and anthracite pits.

    0
    0
  • The gases evolved from the sudden outbursts or blowers in coal, which are often given off at a considerable tension, are the most dangerous enemy that the collier has to contend with.

    0
    0
  • Clowes has shown that it has a wider range of explosive proportions when mixed with air than any of the other combustible gases, the limiting percentages being as follows: - Acetylene .

    0
    0
  • Before the commercial production of calcium carbide made it one of the most easily obtainable gases, the processes which were most largely adopted for its preparation in laboratories were: - first, the decomposition of ethylene bromide by dropping it slowly into a boiling solution of alcoholic potash, and purifying the evolved gas from the volatile bromethylene by washing it through a second flask containing a boiling solution of alcoholic potash, or by passing it over moderately heated soda lime; and, second, the more ordinarily adopted process of passing the products of incomplete combustion from a Bunsen burner, the flame of which had struck back, through an ammoniacal solution of cuprous chloride, when the red copper acetylide was produced.

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  • In point of fact it is found that the properties which are most easily explained are those connected with the gaseous state; the explanation of these properties in terms of the molecular structure of matter is the aim of the " Kinetic Theory of Gases."

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    0
  • The best estimates which we now possess of the sizes of molecules are provided by calculations based upon the kinetic theory of gases.

    0
    0
  • The agreement of the values obtained for the same quantity by different methods provides valuable confirmation of the truth of the molecular theory and of the validity of the methods of the kinetic theory of gases.

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    0
  • The kinetic theory of gases attempts to give a mathematical account, in terms of the molecular structure of matter, of all the non-chemical and non-electrical properties of gases.

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    0
  • The Kinetic Theory of Gases.

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    0
  • The determination of the series of configurations developing out of given initial conditions is not, however, the problem of the kinetic theory: the object of this theory is to explain the general properties of all gases in terms only of their molecular structure.

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    0
  • These properties are found to account for the physical properties of gases.

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    0
  • are very large, then, for all states except an infinitesimal fraction of the whole number, the values of u, v, w lie within ranges such that (i) the values of u (and similarly of v, w) are distributed among the s molecules of the first kind according to the law of trial and error; and similarly of course for the molecules of other kinds: (ii) E2mu2 E2mv 2 E2mw2 ?2aie12 s S s s s s - s E s' S' s' - - s' ' See Jeans, Dynamical Theory of Gases (1904), ch.

    0
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  • It will now be found that the various properties of gases follow from the supposition that the gas is in the normal state.

    0
    0
  • Let a mixture of gases contain per unit volume v molecules of the first kind, v' of the second kind, and so on.

    0
    0
  • For molecules of known gases the calculation is still easier.

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  • If p is the density corresponding to pressure p, we find that,}, formula (Ii) assumes the form P = 3PC2, where C is a velocity such that the gas would have its actual translational energy if each molecule moved with the same velocity C. By substituting experimentally determined pairs of values of p and p we can calculate C for different gases, and so obtain a knowledge of the magnitudes of the molecular velocities.

    0
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  • sures which would be exerted separately by the several The pressure of a mixture of gases is the sum of the pres- Avogadro's Law.

    0
    0
  • Hence we have Avogadro's law: Different gases, at the same temperature and pressure, contain equal numbers of molecules per unit volume.

    0
    0
  • Since the volume at constant pressure is exactly proportional to the absolute temperature, it follows that the coefficients of expansion of all gases ought, to within the limits of error introduced by the assumptions on which we are working, to have the same value 1/273.

    0
    0
  • - The laws which have just been stated are obeyed very approximately, but not with perfect accuracy, by all gases of which the density is not too great or the temperature too low.

    0
    0
  • The following are the values of y for gases for which y can be observed with some accuracy: Mercury..

    0
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  • 1.39 It is clear that for the first four gases n = o, while for the remainder n=2.

    0
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  • The molecules of gases for which n = o must accordingly be spherical in shape and in internal structure, or at least must behave at collisions as though they were spherical, for they would otherwise be set into rotation by the forces experienced at collisions.

    0
    0
  • In the light of these results it is of extreme significance that the four gases for which n = o are all believed to be monatomic: the molecules of these gases consist of single atoms. Moreover, these four are the only monatomic gases for which the value of y is known, so that the only atoms of which the shape can be determined are found to be spherical.

    0
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  • The kinetic energy of the molecules of these gases must contain two terms in addition to those representing translational energy.

    0
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  • We must accordingly suppose that the molecules of gases for which n =2 are of this shape.

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    0
  • Now this is exactly the shape which we should expect to find in molecules composed of two spherical atoms distorting one another by their mutual forces, and all gases for which n=2 are diatomic.

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  • The theory therefore passes a crucial test when it is discovered that no gases exist for which n is either negative or unity.

    0
    0
  • Alcohol is produced by fermentation from vegetable substances containing starch or sugar, from fermentable sugars produced by the hydrolysis of cellulosic bodies, and synthetically from calcium carbide and from the ethylene contained in coal and coke-oven gases.

    0
    0
  • It becomes less when the "oxyhydrogen" is mixed with excess of one or the other of the two reacting gases, or an inert gas such as nitrogen, because in any such case the same amount of heat spreads over a larger quantity of matter.

    0
    0
  • The study of calcination and combustion during the 17th and 18th centuries culminated in the discovery that air consists chiefly of a mixture of two gases, oxygen and nitrogen.

    0
    0
  • Thus, the gases are not present in simple multiples of their combining weights; atmospheric air results when oxygen and nitrogen are mixed in the prescribed ratio, the mixing being unattended by any manifestation of energy, such as is invariably associated with a chemical action; the gases may be mechanically separated by atmolysis, i.e.

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  • 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.

    0
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  • In addition to nitrogen and oxygen, there are a number of other gases and vapours generally present in the atmosphere.

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    0
  • It is convenient to give this calculation before proceeding to describe the experimental determination of the velocity in air, in other gases and in water, since the calculation serves to some extent as a guide in conducting and interpreting the observations.

    0
    0
  • For two different gases with the same value of y, but with densities at the same pressure and temperature respectively p i and p2, we should have U1/U2 =1 1 (P2/P1), (Io) another result confirmed by observation.

    0
    0
  • Regnault in the years 1862 to 1866 on the velocity of sound in open air, in air in pipes and in various other gases in pipes, he sought to eliminate personal equaticn by dispensing with the human element in the observations, using electric receivers as observers.

    0
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  • in a court at the College de France, and with this length he could use dry air, vary the pressure, and fill with other gases.

    0
    0
  • Comparing the velocities of sound U i and U2 in two different gases with densities and at the same temperature and pressure, and with ratios of specific heats 'yl, 72, theory gives Ui/U2 = 1/ {71 p 2/72 p i }.

    0
    0
  • 54) also measured the refractive indices of various gases, using a prism containing the gas to be experimented on, and he found that the deviation by the prism agreed very closely with the theoretical values of sound in the gas and in air.

    0
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  • The velocities in different gases may be compared by this apparatus by filling the dust-tube with the gases in place of air.

    0
    0
  • If d is measured for two gases in succession for the same frequency N, we have 72 p 2P1 d22 71 p i p s d12' where the suffixes denote the gases to which the quantities relate.

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  • As the current flows it decomposes the liquid and liberates oxygen and hydrogen gases, which escape.

    0
    0
  • The U-shaped electrolytic vessel and the electrodes are made of an alloy of platinum-iridium, the limbs of the tube being closed by stoppers made of fluor-spar, and fitted with two lateral exit tubes for carrying off the gases evolved.

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  • Moissan); it has been liquefied, the liquid also being of a yellow colour and boiling at - 187° C. It is the most active of all the chemical elements; in contact with hydrogen combination takes place between the two gases with explosive violence, even in the dark, and at as low a temperature as - 210 C.; finely divided carbon burns in the gas, forming carbon tetrafluoride; water is decomposed even at ordinary temperatures, with the formation of hydrofluoric acid and "ozonised" oxygen; iodine, sulphur and phosphorus melt and then inflame in the gas; it liberates chlorine from chlorides, and combines with most metals instantaneously to form fluorides; it does not, however, combine with oxygen.

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  • With Dr Hugo Miller as his collaborator he published several papers of a chemical character between the years 1856 and 1862, and investigated, 1868-1883, the discharge of electricity through gases by means of a battery of 14,600 chloride of silver cells.

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    0
  • The following table exhibits the chemical constitution of the kinds of milk most frequently used by man: In addition to these constituents milk contains small proportions of the gases carbonic acid, sulphuretted hydrogen, nitrogen and oxygen, and minute quantities of other principles, the constant presence and essential conditions of which have not been determined.

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  • Zeit., 1906, 30, p. 37) has shown that on passing the monohalogen derivatives of the paraffins through a glass tube containing reduced nickel, copper or cobalt at 250° C., olefines are produced, together with the halogen acids, and recombination is prevented by passing the gases through a solution of potash.

    0
    0
  • In their phy s ical properties, the olefines resemble the normal paraffins, the lower members of the series being inflammable gases, the members from C5 to C14 liquids insoluble in water, and from C16 upwards of solids.

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    0
  • It is characterized by its power of absorbing gases; thus, according to J.

    0
    0
  • Carbon monoxide, CO, is found to some extent in volcanic gases.

    0
    0
  • It is one of the most difficultly liquefiable gases, its critical temperature being - 139'5° C., and its critical pressure 35'5 atmos.

    0
    0
  • It is a regular constituent of the atmosphere, and is found in many spring waters and in volcanic gases; it also occurs in the uncombined condition at the Grotto del Cane (Naples) and in the Poison Valley (Java).

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  • In 1871 he began to turn his attention to experimental physics, his earlier researches bearing upon the polarization of light and his later work upon the electrical discharge in rarefied gases.

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  • One of the chief observations recorded in it is that the atmosphere is composed of two gases - one which supports combustion and the other which prevents it.

    0
    0
  • In air and other gases, at ordinary pressures, the dispersion is very small, because the refractivity is small.

    0
    0
  • The dispersive powers of gases are, however, generally comparable with those of liquids and solids.

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  • In another department of physical chemistry he investigated the expansion of liquids with heat, and devised a formula for its expression similar to Gay-Lussac's law of the uniformity of the expansion of gases, while so far back as 1861 he anticipated T.

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  • Andrews's conception of the critical temperature of gases by defining the absolute boiling-point of a substance as the temperature at which cohesion and heat of vaporization become equal to zero and the liquid changes to vapour, irrespective of the pressure and volume.

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  • Methods of Rendering Gases Luminous.

    0
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  • - The extreme flexibility of the phenomena shown by radiating gases renders it a matter of great importance to examine them under all possible conditions of luminosity.

    0
    0
  • Gases, like atmospheric air, hydrogen or carbon dioxide do not become luminous if they are placed in tubes, even when heated up far beyond white heat as in the electric furnace.

    0
    0
  • This need not necessarily be interpreted as indicating the impossibility of rendering gases luminous by temperature only, for the transparency of the gas for luminous radiations may be such that the emission is too weak to be detected.

    0
    0
  • 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.

    0
    0
  • A variety of methods to render gases luminous should be at the command of the investigator, for nearly all, show some distinctive peculiarity and any new modification generally results in fresh facts being brought to light.

    0
    0
  • For our immediate purpose these considerations are of importance inasmuch as they bear on the question how far the spectra emitted by gases are thermal effects only.

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  • Adopting the definition we should have no difficulty in proving that in a vacuum tube gases may be luminous at very low temperatures, but we are doubtful whether such a conclusion is very helpful towards the elucidation of our problem.

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  • As a first `approximation we may say that gases send out homogeneous 2 Wied.

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    0
  • The conclusion which was originally drawn from this fact that helium is a mixture of two gases has not been confirmed, as one of the spectra of oxygen is similarly constituted.

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  • The fact that the gases with which we are most familiar are not rendered luminous by being heated in a tube to a temperature well above a white heat has often been a stumbling block and raised the not unreasonable doubt whether approximately homogeneous oscillations could ever be obtained by a mere thermal process.

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  • The experiment proves only the transparency of the gases experimented upon, and this is confirmed by the fact that bodies like bromine and iodine give on heating an emission spectrum corresponding to the absorption spectrum seen at ordinary temperatures.

    0
    0
  • With absorbing gases we should expect the degradation to proceed more slowly than with liquids, and hence the discovery of E.

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  • Water is led into the highest basin and by the action of the heated gases is soon brought into a state of ebullition; after remaining in this basin for about a day, it is run off into the second one and is treated there in a similar manner.

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    0
  • It is then run into settling tanks, from which it next passes into the evaporating pans, which are shallow leadlined pans heated by the gases of the soffioni.

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    0
  • His name is most widely known in connexion with his work on the liquefaction of the so-called permanent gases and his researches at temperatures approaching the zero of absolute temperature.

    0
    0
  • His interest in this branch of inquiry dates back at least as far as 1874, when he discussed the "Latent Heat of Liquid Gases" before the British Association.

    0
    0
  • About 1892 the idea occurred to him of using vacuum-jacketed vessels for the storage of liquid gases, and so efficient did this device prove in preventing the influx of external heat that it is found possible not only to preserve the liquids for comparatively long periods, but also to keep them so free from ebullition that examination of their optical properties becomes possible.

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  • He also made the first rough experiments on the diffusion of gases, a phenomenon first pointed out by John Dalton, the physical importance of which was more fully brought to light by Thomas Graham and Joseph Loschmidt.

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  • He succeeded in liquefying several gases; he investigated the alloys of steel, and produced several new kinds of glass intended for optical purposes.

    0
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  • On the 3rd of November a new horseshoe magnet came home, and Faraday immediately began to experiment on the action in the polarized ray through gases, but with no effect.

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  • He developed a great research laboratory of experimental physics, attracting numerous workers from many countries and colonies; advances were made in the investigation of the conduction of electricity through gases, in the determination of the charge and mass of the electron and in the development of analysis by means of positive rays.

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  • 1921); The Discharge of Electricity through Gases (1897); The Conduction of Electricity through Gases (1903); and, with Prof. Poynting, a number of text-books upon physics.

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  • Tyndall's investigations of the transparency and opacity of gases and vapours for radiant heat, which occupied him during many years (1859-1871), are frequently considered his chief scientific work.

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    0
  • Gases too dissolve in liquids, while mixtures of various liquids show similar properties.

    0
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  • Some pairs of liquids are soluble in each other in all proportions, but, in general, when dealing with solutions of solids or gases in liquids, a definite limit is reached to the amount which will go into solution when the liquid is in contact with excess of the solid or gas.

    0
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  • The following may be taken as examples: - When dealing with gases it is usually more convenient to express the solubility as the ratio of the volume of the gas absorbed to the volume of the absorbing liquid.

    0
    0
  • For gases such as oxygen and nitrogen dissolved in water the solubility as thus defined is independent of the pressure, or the mass of gas dissolved is proportional to the pressure.

    0
    0
  • This relation does not hold for very soluble gases, such as ammonia, at low temperatures.

    0
    0
  • As a general rule gases are less soluble at high than at low temperatures - unlike the majority of solids.

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    0
  • The variation of gases from Boyle's law is represented in the equation of Van der Waals by subtracting a constant b from the total volume to represent the effect of the volume of the molecules themselves.

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    0
  • On certain assumptions required for the extension of the methods of the kinetic theory of gases to liquids, L.

    0
    0
  • Observations undertaken mainly in the interest of Prout's law, and extending over many years, had been conducted to determine afresh the densities of the principal gases - hydrogen, oxygen and nitrogen.

    0
    0
  • Further experiment only brought out more clearly the diversity of the gases hitherto assumed to be identical.

    0
    0
  • The gases were contained in a test-tube A (fig.

    0
    0
  • When the mixed gases were in the right proportion, the rate of absorption was about 3 o c.c. per hour, about: thirty times as fast as Cavendish could work with the electrical machine of his day.

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  • in the gases expelled from solution in water.

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  • No sufficient advantage is attained by raising the pressure of the gases above atmosphere, but a capacious vessel is necessary.

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  • The residual argon, derived doubtless from the water used to manipulate the gases, was but a small 43 44 45 46 47 48 49 5°00 Argon Red Zinc Hydrogen Hy F FIG.

    0
    0
  • The volume actually weighed was 163 c.c. Subsequently large-scale operations with the same apparatus as had been used for the principal gases gave an almost identical result (19.940) for argon prepared with oxygen.

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  • We should thus expect to find it in increased proportion in the dissolved gases of rain-water.

    0
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  • The weight of a mixture of argon and nitrogen prepared from the dissolved gases showed an excess of 24 mg.

    0
    0
  • Argon is contained in the gases liberated by many thermal springs, but not in special quantity.

    0
    0
  • The ratio of specific heats of the principal gases is I.

    0
    0
  • 21, referred to air, somewhat higher than for oxygen, which stands at the head of the list of the principal gases ("On some Physical Properties of Argon and Helium," Proc. Roy.

    0
    0
  • Travers have obtained evidence of the existence in the atmosphere of three new gases, besides helium, to which have been assigned the names of neon, krypton and xenon.

    0
    0
  • These gases agree with argon in respect of the ratio of the specific heats and in being non-oxidizable under the electric spark.

    0
    0
  • As originally defined, argon included small proportions of these gases, but it is now preferable to limit the name to the principal constituent and to regard the newer gases as "companions of argon."

    0
    0
  • The physical properties of these gases are given in the following table (Proc. Roy.

    0
    0
  • In 1800 he became a secretary of the society, and in the following year he presented the important paper or series of papers, entitled "Experimental Essays on the constitution of mixed gases; on the force of steam or vapour of water and other liquids in different temperatures, both in Torricellian vacuum and in air; on evaporation; and on the expansion of gases by heat."

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  • 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."

    0
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  • 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."

    0
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  • But from a study of Dalton's own MS. laboratory notebooks, discovered in the rooms of the Manchester society, Roscoe and Harden (A New View of the Origin of Dalton's Atomic Theor y, 1896) conclude that so far from Dalton being led to the idea that chemical combination consists in the approximation of atoms of definite and characteristic weight by his search for an explanation of the law of combination in multiple proportions, the idea of atomic structure arose in his mind as a purely physical conception, forced upon him by study of the physical properties of the atmosphere and other gases.

    0
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  • The first published indications of this idea are to be found at the end of his paper on the "Absorption of gases" already mentioned, which was read on the 21st of October 1803 though not published till 1805.

    0
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  • This question I have duly considered, and though I am not able to satisfy myself completely I am nearly persuaded that the circumstance depends on the weight and number of the ultimate particles of the several gases."

    0
    0
  • It appears, then, that, confronted with the "problem of ascertaining the relative diameter of the particles of which, he was convinced, all gases were made up, he had recourse to the results of chemical analysis.

    0
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  • It may be noted that in a paper on the "Proportion of the gases or elastic fluids constituting the atmosphere," read by him in November 1802, the law of multiple proportions appears to be anticipated in the words - "The elements of oxygen may combine with a certain portion of nitrous gas or with twice that portion, but with no intermediate quantity," but there is reason to suspect that this sentence was added some time after the reading of the paper, which was not published till 1805.

    0
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  • Thus he distrusted, and probably never fully accepted, Gay-Lussac's conclusions as to the combining volumes of gases; he held peculiar and quite unfounded views about chlorine, even after its elementary character had been settled by Davy; he persisted in using the atomic weights he himself had adopted, even when they had been superseded by the more accurate determinations of other chemists; and he always objected to the chemical notation devised by J.

    0
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  • de Phys., 1811), in which he enunciated the hypothesis known by his name (Avogadro's rule) that under the same conditions of temperature and pressure equal volumes of all gases contain the same number of smallest particles or molecules, whether those particles consist of single atoms or are composed of two or more atoms of the same or different kinds.

    0
    0
  • Tudsbury that if an influence machine is enclosed in a metallic chamber containing compressed air, or better, carbon dioxide, the insulating properties of compressed gases enable a greatly improved effect to be obtained owing to the diminution of the leakage across the plates and from the supports.

    0
    0
  • in diameter, found that the current given by it could only electrolyse acidulated water in 40 hours sufficient to liberate one cubic centimetre of mixed gases.

    0
    0
  • The next great improvement in blast-furnace practice came in 1811, when Aubertot in France used for heating steel the furnace gases rich in carbonic oxide which till then had been allowed to burn uselessly at the top of the blast furnace.

    0
    0
  • Very soon after this, in 1832, the work of heating the blast was done by means of the waste gases, at Wasseralfingen in Bavaria.

    0
    0
  • Interpenetrating this descending column of solid ore, limestone and coke, there is an upward rushing column of hot gases, the atmospheric nitrogen of the blast from the tuyeres, and the FIG.

    0
    0
  • The upward ascent of the column of gases is as swift as the descent of the solid charge is slow.

    0
    0
  • But the transfer of heat from the rising gases to the sinking solids, which has been going on in the upper part of the furnace, continues as the solid column gradually sinks downward to the hearth, till at the " fusion level " (A in fig.

    0
    0
  • The reason why the frictional resistance would be further increased is the very simple one that the increase in the rate of production implies directly a corresponding increase in the quantity of blast forced through, and hence in the velocity of the rising gases, because the chemical work of the blast furnace needs a certain quantity of blast for each ton of iron made.

    0
    0
  • In short, to increase the rate of production by lengthening the furnace increases the frictional resistance of the rising gases, both by increasing their quantity and hence their velocity and by lengthening their path.

    0
    0
  • We see how powerful must be the lifting effect of the rising gases when we reflect that their velocity in a too ft.

    0
    0
  • Conceive these gases passing at this great velocity through the narrow openings between the adjoining lumps of coke and ore.

    0
    0
  • After the ascending column of gases has done its work of heating and deoxidizing the ore,.

    0
    0
  • This heating was formerly done by burning part of the gases, after their escape from the furnace top, in a large combustion chamber, around a series of cast iron pipes through which the blast passed on its way from the blowing engine to the tuyeres.

    0
    0
  • First, if the skeleton which it forms is continuous, then its planes of junction with the metallic matrix offer a path of low resistance to the passage of liquids or gases, or in short they make the metal so porous as to unfit it for objects like the cylinders of hydraulic presses, which ought to be gas-tight and water-tight.

    0
    0
  • has a higher solvent power for gases, such as hydrogen and nitrogen,.

    0
    0
  • Cavendish called it "inflammable air," and for some time it was confused with other inflammable gases, all of which were supposed to contain the same inflammable principle, "phlogiston," in combination with varying amounts of other substances.

    0
    0
  • In combination it is found as a constituent of water, of the gases from certain mineral springs, in many minerals, and in most animal and vegetable tissues.

    0
    0
  • News, 1901, 84, p. 49; see also Liquid Gases).

    0
    0
  • Perhaps a satisfactory point of view may be here obtained by applying the van der Waals' equation A(P-{-a/V2)(V-b)=2T, which connects volume V, pressure P and temperature T (see Condensation Of Gases).

    0
    0
  • Like the X rays, the Becquerel rays are invisible; they both traverse thin sheets of glass or metal, and cannot be refracted; moreover, they both ionize gases, i.e.

    0
    0
  • In addition, radium evolves an "emanation" which is an extraordinarily inert gas, recalling the "inactive" gases of the atmosphere.

    0
    0
  • This is termed convection, and is most important in the case of liquids and gases owing to their mobility.

    0
    0
  • Conduction in Gases and Liquids.

    0
    0
  • - The theory of conduction of heat by diffusion in gases has a particular interest, since it is possible to predict the value on certain assumptions, if the viscosity is known.

    0
    0
  • If the effects depended merely on the velocity of translation of the molecules, both conductivity and viscosity should increase directly as the square root of the absolute temperature; but the mean free path also varies in a manner which cannot be predicted by theory and which appears to be different for different gases (Rayleigh, Proc. R.S., January 1896).

    0
    0
  • If, as is now generally believed, aurora represents some form of electrical discharge, it is only reasonable to suppose that the auroral lines arise from atmospheric gases.

    0
    0
  • Some salt decrepitates on solution (Knistersalz), the phenomenon being due to the escape of condensed gases.

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  • At this middle portion and in the upper part of the lower shaft the burning proper proceeds; the upper shaft is full of unburnt raw material which is heated by the hot gases coming from the burning zone, and the lower shaft contains clinker already burned and hot enough to heat the incoming air which supplies that necessary for combustion at the clinkering zone.

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  • In each case the clinker which has just been burned and is fully hot serves to heat the air-supply to the compart ment where combustion is actu ally proceeding; in like manner the raw materials about to be burned are well heated by the waste gases from the compartment in full activity before they them selves are burned.

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  • For the properties of liquid oxygen see Liquid Gases.

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  • Regarding heat (matiere de feu or fluide igne) as a peculiar kind of imponderable matter, Lavoisier held that the three states of aggregation - solid, liquid and gas - were modes of matter, each depending on the amount of matiere de feu with which the ponderable substances concerned were interpenetrated and combined; and this view enabled him correctly to anticipate that gases would be reduced to liquids and solids by the influence of cold and pressure.

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  • In consequence the fire-gases, when arriving there by the chimney shaft (a), have already a good upward draught, and when circulatung round the muffle are at a lower pressure than the gases within the muffle, so that in case of any cracks being formed, no hydrochloric acid escapes into the fire-flues, but vice versa.

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  • �, �, ?,, ,, O passes through a gap in the arch in such a manner that the gases cannot escape outwards.

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  • L I subjected in a series of large cast-iron cylinders to the action of pyrites-burner gases and steam at a low red heat.

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  • This means that the previous manufacture of sulphuric acid in the vitriol-chambers is done away with, but this apparently great simplification is balanced by the great cost of the Hargreaves plant, and by the fact that the whole of the hydrochloric acid is mixed with nine or ten times its volume of inert gases.

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  • The hydrochloric acid gas, which is always diluted with air, sometimes to a very great extent, must be brought into the most intimate contact possible with water, which greedily absorbs it, forming ordinary hydrochloric acid, and this process must be carried so far that scarcely any hydrochloric acid remains in the escaping gases.

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  • heat retained by the gases on their escape from the decom posing apparatus, and by the heat given off through the reaction of hydrochloric acid upon water.

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  • The movement of the gases through all this complicated set of apparatus is produced by a Root's blower placed at the end of it all.

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  • The hydrochloric acid from the calcining-furnaces or "roasters" cannot be employed immediately for the Deacon process, as the sulphuric acid always contained in the roaster gases soon " poisons " the contact-substance and renders it inoperative.

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  • This is at first colourless carbon dioxide, but later on inflammable gases come out of the mass, which at this stage has turned into a thicker, pasty condition, showing that the end of the reaction is near.

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  • The sulphides can be removed by " oxidizing " them into thiosulphates by means of atmospheric air, with or without the assistance of other agents, such as manganese peroxide; or by " carbonating " them with lime-kiln or other gases containing carbon dioxide; or by precipitating them with lead or zinc oxide.

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  • This is usually effected either by forcing lime-kiln gas through the liquor, contained in a closed iron vessel, or by passing the gases through an iron tower filled with coke or other materials, suitable for subdividing the stream of the gases and that of the vat-liquor which trickles down in the tower.

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  • The wet alkali-waste as it comes from the lixiviating vats, is transferred into upright iron cylinders in which it is systematically treated with lime-kiln gases until the whole of the calcium sulphide has been converted into calcium carbonate, the carbon dioxide of the lime-kiln gases being entirely exhausted.

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  • Unfortunately it has been hitherto found impossible to deal with these gases in any profitable way.

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  • / structed in such a way that the gases are over and over again subdivided into many smaller streams and are thus thoroughly brought into contact with the ammoniacal salt solution with which the tower is about two-thirds filled.

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  • This is employed in the shape of lime-kiln gases, obtained in a comparatively pure and strong form (up to 33% CO 2), in very large kilns, charged with limestone and coke.

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  • The kilns are closed at the top, and the gases are drawn out by powerful air-pumps, washers being interposed be,, veen the kilns and the pumps for the purpose of purifying and cooling the gas.

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  • An application of these results to solar physics in conjunction with Sir Norman Lockyer led to the view that at least the external layers of the sun cannot consist of matter in the liquid or solid forms, but must be composed of gases or vapours.

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  • Regnault executed a careful redetermination of the specific heats of all the elements obtainable, and of many compounds - solids, liquids and gases.

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  • He investigated the expansibility of gases by heat, determining the coefficient for air as 0.003665, and showed that, contrary to previous opinion, no two gases had precisely the same rate of expansion.

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  • By numerous delicate experiments he proved that Boyle's law is only approximately true, and that those gases which are most readily liquefied diverge most widely from obedience to it.

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  • He carried on his great research on the expansion of gases in the laboratory at Sevres, but all the results of his latest work were destroyed during the Franco-German War, in which also his son Henri (noticed above) was killed.

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  • In The Case Of Solids And Liquids Under Ordinary Conditions Of Pressure, The External Work Of Expansion Is So Small That It May Generally Be Neglected; But With Gases Or Vapours, Or With Liquids Near The Critical Point, The External Work Becomes So Large That It Is Essential To Specify The Conditions Under Which The Specific Heat Is Measured.

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  • 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).

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  • Thus The Direct Experimental Evidence Is Somewhat Meagre And Conflicting, But The Question Of The Relation Of The Specific Heats Of Gases Is One Of Great Interest In Connexion With The Kinetic Theory And The Constitution Of The Molecule.

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  • The Well Known Experiments Of Regnault And Wiedemann On The Specific Heat Of Gases At Constant Pressure Agree In Showing That The Molecular Specific Heat, Or The Thermal Capacity Of The Molecular Weight In Grammes, Is Approximately Independent Of The Temperature And Pressure In Case Of The More Stable Diatomic Gases, Such As 112,02, N2, Co, &C., And Has Nearly The Same Value For Each Gas.

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  • This Appears To Be Actually The Case For Monatomic Gases Such As Mercury Vapour (Kundt And Warburg, 1876), Argon And Helium (Ramsay, 1896).

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  • For Diatomic Or Compound Gases Clerk Maxwell Supposed That The Molecule Would Also Possess Energy Of Rotation, And Endeavoured To Prove That In This Case The Energy Would Be Equally Divided Between The Six Degrees Of Freedom, Three Of Translation And Three Of Rotation, If The Molecule Were Regarded As A Rigid Body Incapable Of Vibration Energy.

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  • In 1879 Maxwell Considered It One Of The Greatest Difficulties Which The Kinetic Theory Had Yet Encountered, That In Spite Of The Many Other Degrees Of Freedom Of Vibration Revealed By The Spectroscope, The Experimental Value Of The Ratio S/S Was 1.40 For So Many Gases, Instead Of Being Less Than 4/3.

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  • For The Simpler Gases, Which Are Highly Diathermanous And Radiate Badly Even At High Temperature, The Energy Of Vibration Is Probably Very Small, Except Under The Special Conditions Which Produce Luminosity In Flames And Electric Discharges.

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    0
  • For Such Gases, Assuming A Constant Ratio Of Rotation To Translation, The Specific Heat At Low Pressures Would Be Very Nearly Constant.

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  • per second in the gases of the atmosphere of the nova; but the velocity implied by this expansion of the nebula was unprecedented and comparable only with the velocity of light.

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  • the case of the sun, this indicates an incandescent body which might be solid, liquid, or a not too rare gas, surrounded by and seen through an atmosphere of somewhat cooler gases and vapours; it is this cooler envelope whose nature the spectroscope reveals to us, and in it the presence of many terrestrial elements has been detected by identifying in the spectrum their characteristic absorption lines.

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  • As the first condensation takes place, the resulting development of heat causes the hydrogen, helium and light gases to be expelled.

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  • As the nuclei grow by the attraction of matter they begin to be capable of retaining the lighter gases, and atmospheres of hydrogen and helium are formed.

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  • Gay-Lussac's earlier researches were mostly physical in character and referred mainly to the properties of gases, vapourtensions, hygrometry, capillarity, &c. In his first memoir (Ann.

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  • de Chimie, 1802) he showed that different gases are dilated in the same proportion when heated from o° to ioo° C. Apparently he did not know of Dalton's experiments on the same point, which indeed were far from accurate; but in a note he explained that "le cit.

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  • In 1807 an account of the magnetic observations made during the tour with Humboldt was published in the first volume of the Memoires d'Arcueil, and the second volume, published in 1809, contained the important memoir on gaseous combination (read to the Societe Philomathique on the last day of 1808), in which he pointed out that gases combining with each other in volume do so in the simplest proportions-1 to 1, 1 to 2, 1 to 3 - and that the volume of the compound formed bears a simple ratio to that of the constituents.

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  • For example, the inference from the similarity between solar spectra and the spectra of various gases on the earth to the existence of similar gases in the sun, is called by him an induction; but it really is an analytical deduction from effect to cause, thus: Such and such spectra are effects of various gases.

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  • Solar spectra are effects of those gases.

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  • The waste of heat in the chimney gases is accordingly greater; and further, the metallic shell is liable to be quickly burned away as a result of its contact at a high temperature with free oxygen.

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    0
  • They differ from it, however, in the fact that their working substance is not air, but a mixture of gases - a necessary consequence of internal combustion.

    0
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  • 0' and 0", we see that Rankine's result follows immediately, provided that p(v-b) is equal to (S-s)0 or Rolm, which is approximately true for gases and vapours when v is very large compared with b.

    0
    0
  • The first accurate calculations of the specific heats of air and gases were made by Rankine in a continuation of the paper already quoted.

    0
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  • Assuming this result to hold generally, we should have S=0.306 at o° C., which agrees with Rankine's view; but increasing very rapidly at higher temperatures to S =1.043 at 200° C., and 1.315 at 220° C. The characteristic equation, if SQ = constant, would be of the form (v+SQ) = Roil ', which does not agree with the well-known behaviour of other gases and vapours.

    0
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  • 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.

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  • It is found by these methods that the behaviour of superheated vapours closely resembles that of noncondensible gases, and it is a fair inference that similar behaviour would be observed up to the saturation-point if surface condensation could be avoided.

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  • Metallic products represent about three-fourths of the total, but the feature of recent years has been the rising importance of hydrocarbons and gases, and of structural materials, and indeed of non-metallic products generally.

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  • Thus the declaration of Paris, 1856 (to which, however, the United States, Venezuela and Bolivia have not yet formally acceded), prohibits the use of privateers and protects the commerce of neutrals; the Geneva conventions, 1864 and 1906, give protection to the wounded and to those in attendance upon them; the St Petersburg declaration, 1868, prohibits the employment of explosive bullets weighing less than 400 grammes; and the three Hague declarations of 1899 prohibit respectively (I) the launching of projectiles from balloons, (2) the use of projectiles for spreading harmful gases, and (3) the use of expanding bullets.

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  • The hydrides of the halogens are all colourless, strongly fuming gases, readily soluble in water and possessing a strong acid reaction; they react readily with basic oxides, forming in most cases well defined crystalline salts which resemble one another very strongly.

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  • In the form of alkaline chlorides it is found in sea-water and various spring waters, and in the tissues of animals and plants; while, as hydrochloric acid it is found in volcanic gases.

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  • The first published research (1816) dealt with the dilatation of solids, liquids and gases and with the exact measurement of temperature, and it was followed by another in 1818 on the measurement of temperature and the communication of heat, which was crowned by the French Academy.

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  • Subsequent papers by Dulong were concerned with " New determinations of the proportions of water and the density of certain elastic fluids " (1820, with Berzelius); the property possessed by certain metals of facilitating the combination of gases (1823 with Thenard); the refracting powers of gases (1826); and the specific heats of gases (1829).

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  • Arsenic formed the subject of his first recorded investigation, on which he was engaged at least as early as 1764, and in 1766 he began those communications to the Royal Society on the chemistry of gases, which are among his chief titles to fame.

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  • He determined the specific gravity of these gases with reference to common air, investigated the extent to which they are absorbed by various liquids, and noted that common air containing one part in nine by volume of fixed air is no longer able to support combustion, and that the air produced by fermentation and putrefaction has properties identical with those of fixed air obtained from marble.

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  • The phenomena attendant on the passage of electricity through solids, through liquids and through gases, are described in the article Electric conduction, and also Electrolysis, and the propagation of electrical vibrations in Electric Waves.

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  • These two gases, as Cavendish and James Watt had shown in 1784, were actually the constituents of water.

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  • Experimental methods were devised for the further exact measurements of the electromagnetic velocity and numerous determinations of the dielectric constants of various solids, liquids and gases, and comparisons of these with the corresponding optical refractive indices were conducted.

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  • Boltzmann (1844-1907) made a large number of determinations for solids and for gases, and the dielectric constants of many solid and liquid substances were determined by N.

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  • de C. du Fay on the conductivity of some bodies for the electric agency and the dual character of electrification gave rise to the first notions of ., electricity as an imponderable fluid, or non-gravitative subtile matter, of a more refined and penetrating kind than ordinary liquids and gases.

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  • Discharge through Gases.-Many eminent physicists had an instinctive feeling that the study of the passage of electricity through gases would shed much light on the intrinsic nature of electricity.

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  • It has long been known that air and other gases at the pressure of the atmosphere were very perfect insulators, but that when they were rarefied and contained in glass tubes with platinum electrodes sealed through the glass, electricity could be passed through them under sufficient electromotive force and produced a luminous appearance known as the electric glow discharge.

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  • Hittorf examined the phenomena exhibited in so-called high vacua, that is, in exceedingly rarefied gases.

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  • The operation called an electric current consists in a diffusion or movement of these electrons through matter, and this is controlled by laws of diffusion which are similar to those of the diffusion of liquids or gases.

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  • Thomson, Recent Researches in Electricity and Magnetism (Oxford, 1893); id., Conduction of Electricity through Gases (Cambridge, 1903); id., Electricity and Matter (London, 1904); O.

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  • during the whole time the flax is in steep. In a short time a brisk fermentation is set up, gases at first of pleasant odour, but subsequently becoming very repulsive, being evolved, and producing a frothy scum over the surface of the water.

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  • To the northeast of the town is the Solfatura, a half extinct volcano crater, in which sulphurous gases are exhaled.

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  • These occluded gases are all liberated when the copper cools, and so give rise to porous castings, unless special precautions are taken.

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  • The gases are also expelled from the molten metal by lead, carbon dioxide, or water vapour.

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  • Shaft furnaces are in use for ores rich in sulphur, and where it is desirable to convert the waste gases into sulphuric acid.

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  • Reverberatory roasting does not admit of the utilization of the waste gases, and requires fine ores and much labour and fuel; it has, however, the advantage of being rapid.

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  • They involve high cost in fuel and labour, but permit the utilization of the waste gases.

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  • high, fed mechanically, and provided with stoves to heat the blast by the furnace gases.

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  • The low percentage of sulphur in the roasted ore is little more than enough to produce a matte of 40 to 45%, and therefore the escaping gases are better fitted than those of most copper cupola furnaces for burning in a stove.

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  • This view is confirmed by experiments in which other gases are substituted for air as the environment of colliding jets.

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  • On the other hand, the more soluble gases, carbon dioxide, nitrous oxide, sulphur dioxide, and steam, at once caused union.] Stability of the Catenoid.

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  • W.) to liquefy gelatine, to secrete coloured pigments, to ferment certain media with evolution of carbon dioxide or other gases, or to induce pathological conditions in animals.

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  • We have thus an explanation of the occurrence of marsh gas and sulphuretted hydrogen in bogs, and it is highly probable that the existence of these gases in the intestines of herbivorous animals is due to similar putrefactive changes in the undigested cellulose remains.

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  • Beyerinck and Jegunow have shown that some partially anaerobic sulphur bacteria can only exist in strata at a certain depth below the level of quiet waters where SH 2 is being set free below by the bacterial decompositions of vegetable mud and rises to meet the atmospheric oxygen coming down from above, and that this zone of physiological activity rises and falls with the variations of partial pressure of the gases due to the rate of evolution of the SH 2.

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  • Not only so, the isolation of the cells facilitates the exchange of liquids and gases, the passage in of food materials and out of enzymes and products of metabolism, and thus each unit of protoplasm obtains opportunities of immediate action, the results of which are removed with equal.

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  • He concluded that the gases are due to the decomposition of an organic colouring matter, which has, however, no connexion with the fluorescence or thermo-luminescence of the mineral.

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  • important engineering work was planned not only to afford a more convenient waterway between the upper Spree and the Havel (and thus to the Elbe), but was to remove from the city to its banks and vicinity those factories of which the noxious, gases and other poisonous emanations were regarded as dangerous to the health of the community.

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  • An early observation of the diffusion of gases was recorded by him in 1823 when he noticed the escape of hydrogen from a cracked jar, attributing it to the capillary action of fissures.

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  • By the latter he was recommended to Dr Thomas Beddoes, who was in 1798 establishing his Medical Pneumatic Institution at Bristol for investigating the medicinal properties of various gases.

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  • In 1823, when Faraday liquefied chlorine, he read a paper which suggested the application of liquids formed by the condensation of gases as mechanical agents.

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  • On the other hand, if a gas be sufficiently cooled and compressed, it liquefies; this transition is treated theoretically in the article Condensation Of Gases, and experimentally in the article Liquid Gases.

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  • ciii.) he published the first of his classical researches on the action of the magnet on the electric discharge in rarefied gases.

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  • Hittorf, made many important discoveries in the spectroscopy of gases.

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  • Preyer's view, however, enlarges the conception of life until it can be applied to the phenomena of incandescent gases and has no relation to ideas of life derived from observation of the living matter we know.

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  • With the development of analytical and especially of pneumatic chemistry, the air was recognized not to be one homogeneous substance, as was long supposed, and different "airs," or gases, came to be distinguished.

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  • For some years after his appointment he devoted himself specially, with Francois Marcet (1803-1883), to the investigation of the specific heat of gases, and to observations for determining the temperature of the earth's crust.

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  • Electrical studies, however, engaged most of his attention, especially in connexion with the theory of the voltaic cell and the electric discharge in rarefied gases.

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  • The law of absorption expressed by the formula (2) has been verified by experiments for various solids, liquids and gases.

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  • This is not strictly the case, however, for such gases and vapours as exhibit well-defined bands of absorption in the spectrum, as these bands are altered in character by compression.

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  • It is also remarkable that many gases and vapours, e.g.

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  • These gases were considered to be distinct until Le Verrier (Ann.

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  • The body of the sun must consist of uncombined gases; at the surface the temperature is some 2000° C. above the boiling point of carbon, and a little way within the body it may probably exceed the critical point at which increase of pressure can produce the liquid state in any substance.

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  • But as the mean density exceeds that of water, and probably falls but little from the centre to the surface, these gases are gases only in the sense that if the pressure of neighbouring and outward parts gravitating towards the centre were relaxed, they would expand explosively, as we see happening in the eruptive prominences.

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  • The chromosphere, which surrounds the photosphere, is a cloak of gases of an average depth of 5000 m., in a state of luminescence less intense than that of the photosphere.

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  • In the higher chromosphere on occasions metallic gases are carried up to such a level that without an eclipse a bright line spectrum of many elements may be seen, but it is always possible to see those of hydrogen and helium, and by opening the slit of the spectroscope so as to weaken still further the continuous spectrum from the photosphere (now a mere reflection) the actual forms of the gaseous structures called prominences round the sun's rim may be seen.

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  • The pressure which produces a continuous spectrum in gases at a temperature of 6000 0 must be very great.

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  • The burner gas is introduced at one end, the waste gases issue from the other, the movement of the gases being impelled partly by their own chemical reactions, partly by the draught produced by a chimney (or tower), or by mechanical means.

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  • It is evident that the "nitrous gases" present in the vitriol chamber consist essentially of a mixture of NO and N02, the latter being formed from NO by the excess of oxygen present.

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  • Since the reactions occur among gases and liquids in the nebulous state, vast spaces have to be provided in which the process may be carried out as completely as possible before the waste gases are allowed to escape into the outer air.

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  • These spaces cannot be constructed in any other way than is actually done in the shape of the lead chambers; neither iron nor brickwork can be employed for this purpose, as they would be quickly destroyed by the acid liquids and gases.

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  • When issuing from the chambers, the gases still contain the whole of the free nitrogen contained in the air which had entered into the burners, together with about a third, or at least a fourth, of the oxygen originally present therein, such excess of oxygen being required in order to carry out the conversion of the sulphur dioxide into sulphuric acid as completely as possible.

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  • The first step towards securing this requirement was taken as early as 1827 by Gay-Lussac, who discovered that the nitrous fumes, otherwise carried away from the lead chambers by the waste atmospheric nitrogen and oxygen, could be retained by bringing the gases into contact with moderately strong sulphuric acid, the result being the formation of nitroso-sulphuric acid: 2H 2 SO 4 + N203 = 2S0 2 (OH) (ONO) + H 2 O, and the latter remaining dissolved in sulphuric acid as "nitrous vitriol."

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  • The gases now pass on to the lead chambers, described above, where they meet with more nitrous vapours, and with steam, or with water, converted into a fine dust or spray.

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  • Here the reactions sketched above take place, so that "chamber-acid" as already described is formed, while a mixture of gases escapes containing all the atmospheric nitrogen, some oxygen in excess, about 0.5% of the total S02, and some oxides of nitrogen.

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  • By judiciously watching all stages of the process, by observing the draught, the strength of the acid produced, the temperature, and especially by frequent analyses of the gases, the yield of acid has been brought up to 98% of the theoretical maximum, with a loss of nitre sometimes as low as two parts to loo of sulphur burned.

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  • Many attempts have been made to reduce the chamber space by apparatus intended to bring about a better mixture of the gases, and to facilitate the interaction of the misty particles of nitrous vitriol and dilute acid floating in the chamber with each other and with the chamber atmosphere.

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  • - Matter is studied under three physical phases - solids, liquids and gases, the latter two being sometimes grouped as "fluids."

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  • The study of the physical properties of fluids in general constitutes the science of hydromechanics, and their applications in the arts is termed hydraulics; the special science dealing with the physical properties of gases is named pneumatics.

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  • But here we distinguish between fluids according as they are gases or liquids.

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  • The study of the effects of pressure and temperature on many gases led to the introduction of the term "permanent gases" to denote gases which were apparently not liquefiable.

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  • Until the end of the 18th century the word "air," qualified by certain adjectives, was in common use for most of the gases known - a custom due in considerable measure to the important part which common air played in chemical and physical investigations.

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  • The study of gases may be divided into two main branches: the physical and the chemical.

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  • These subjects are discussed in the articles Density; Thermometry; Calorimetry; Diffusion; Conduction Of Heat; and Condensation Of Gases.

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  • The latter has for its province the preparation, collection and identification of gases, and the volume relations in which they combine; in general it deals with specific properties.

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  • The historical development of the chemistry of gases - pneumatic chemistry - is treated in the article Chemistry; the technical analysis of gaseous mixtures is treated below under Gas Analysis.

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  • Connecting the experimental study of the physical and chemical properties is the immense theoretical edifice termed the kinetic theory of gases.

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  • The chief applications are found in the analysis of flue gases (in which much information is gained as to the completeness and efficiency of combustion), and of coal gas (where it is necessary to have a product of a definite composition within certain limits).

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  • The choice of absorbents and the order in which the gases are to be estimated is strictly limited.

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  • Gases soluble in water, such as ammonia, hydrochloric acid, sulphuretted hydrogen, sulphur dioxide, &c., are estimated by passing a known volume of the gas through water and titrating the solution with a standard solution.

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  • paraffins, under the influence of heat, split up into simpler members of the same series and into olefines; and if we imagine the action in its simplest form, we should have the gases, as they were evolved, consisting of (say) ethane and ethylene.

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  • is probably heated to only 600° C. Moreover, the gases and vapours in the retort are subjected to a period of heating which varies widely with the distance from the mouth of the retort of the coal that is undergoing carbonization.

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  • They may be divided into - (a) Solids, such as the coke and retort carbon; (b) liquids, consisting of the tar and ammoniacal liquor; and (c) gases, consisting of the unpurified `coal gas.

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  • The gas which is obtained by the destructive distillation of coal, and which we employ as our chief illuminant, is not a definite com pound, but a mechanical mixture of several gases, some Gaseous .

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  • These gases enter the combustion chamber around the retorts at a high temperature, and are there supplied with sufficient air to complete their combustion, this secondary air supply being heated by the hot products of combustion on their way to the exit flue.

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  • The gases are conducted from the furnace to the combustion chamber E through the nostrils D D, and the secondary air is FIG.

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  • Complete combustion takes place at this point with the production of intense heat, the gases on rising are baffled in order to circulate them in every direction round the retorts, and upon arriving at the top of the setting they are conducted down a hollow chamber communicating with the main flue and shaft.

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  • The amount of draft which is necessary to carry out the circulation of the gases and to draw in the adequate amount of air is regulated by dampers placed in the main flue.

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  • By analysis of the "producer" and "spent" gases this amount can be readily gauged.

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  • Coal gas, being a mixture of gases and vapours of liquids having very varying boiling points, must necessarily undergo physical changes when the temperature is lowered Vapours of liquids of high boiling point will be condensed more quickly than those having lower boiling points, but condensation of each vapour will take place in a definite ratio with the decrease of temperature, the rate being dependent upon the boiling point of the liquid from which it is formed.

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  • A partly successful attempt to make use of certain portions of the liquid products of distillation of coal before condensation by the second method was the Dinsmore process, in which the coal gas and vapours which, if allowed to cool, would form tar, were made to pass through a heated chamber, and a certain proportion of otherwise condensible hydrocarbons was thus converted into permanent gases.

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  • Consequently, to make it carry any further quantity in a condition not easily deposited, the oil would have to be completely decomposed into permanent gases, and the temperature necessary to do this would seriously affect the quality of the gas given off by the coal.

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  • Undoubtedly the best process which has been proposed for the production of oil gas to be used in the enrichment of coal gas is the" Young "or" Peebles "process, which depends on the principle of washing the oil gas retorted at a moderate temperature by means of oil which is afterwards to undergo decomposition, because in this way it is freed from all condensible vapours, and only permanent gases are allowed to escape to the purifiers.

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  • In the course of this treatment considerable quantities of the ethylenes and other fixed gases are also absorbed, but no loss takes place, as these are again driven out by the heat in the subsequent retorting.

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  • The fundamental objections to oil gas for the enrichment of coal gas are, first, that its manufacture is a slow process, requiring as much plant and space for retorting as coal gas; and, secondly, that although on a small scale it can be made to mix perfectly with coal gas and water gas, great difficulties are found in doing this on the large scale, because in spite of the fact that theoretically gases of such widely different specific gravities ought to form a perfect mixture by diffusion, layering of the gas is very apt to take place in the holder, and thus there is an increased liability to wide variations in the illuminating value of the gas sent out.

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  • resultant action may be looked upon as giving a mixture meat by of equal volumes of hydrogen and carbon monoxide, both meatretted of which are inflammable but non-luminous gases.

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  • Enriching the gas by vapours and permanent gases obtained by decomposing the tar formed at the same time as the gas.

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  • Mixing the coal gas with water gas, which has been highly carburetted by passing it with the vapours of various hydrocarbons through superheaters in order to give permanency to the hydrocarbon gases.

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  • Under these conditions producer gas ceases to exist as a by-product, and the gases of the blow consist merely of the incombustible products of com plete combustion, carbon dioxide and nitrogen, the result being that more than three times / the heat is developed for the combustion of the same amount of fuel, and nearly double the quantity of water gas can be made per pound of fuel than was before possible.

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  • The gases formed during this process pass into the upper portion of V and get mixed with the producergas formed in the lower portion.

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  • The spray of water removes the dust and part of the tar and ammonia from the gases, much steam being produced at the same time.

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  • The gases, escaping from W at a temperature of about ioo° C., and containing much steam, pass though g and a into a tower, fed with an acid-absorbing liquid, coming from the tank s, which is spread into many drops by the brick filling of the tower.

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  • This liquid is a strong solution of ammonium sulphate, containing about 2 5% free sulphuric acid which absorbs nearly all the ammonia from the gases, without dissolving much of the tarry substances.

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  • It dissolves in dilute cold nitric acid with the formation of ferrous and ammonium nitrates, no gases being liberated; when heated or with stronger acid ferric nitrate is formed with evolution of nitrogen oxides.

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  • Baker), and when this is not so, indirect methods are available, except with bromine and fluorine (and also with the so-called inert gases - argon, helium, &c.), which so far have yielded no oxides.

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  • He communicated papers to the Philosophical Society of Glasgow before the work of that society was recorded in Transactions, but his first published paper, "On the Absorption of Gases by Liquids," appeared in the Annals of Philosophy for 1826.

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  • The subject with which his name is most prominently associated is the diffusion of gases.

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  • In his first paper on this subject (1829) he thus summarizes the knowledge experiment had afforded as to the laws which regulate the movement of gases.

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  • "Fruitful as the miscibility of gases has been in interesting speculations, the experimental information we possess on the subject amounts to little more than the well-established fact that gases of a different nature when brought into contact do not arrange themselves according to their density, but they spontaneously diffuse through each other so as to remain in an intimate state of mixture for any length of time."

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  • DBbereiner he substituted a glass tube closed by a plug of plaster of Paris, and with this simple appliance he developed the law now known by his name "that the diffusion rate of gases is inversely as the square root of their density."

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  • His early work on the movements of gases led him to examine the spontaneous movements of liquids, and as a result of the experiments he divided bodies into two classes - crystalloids, such as common salt, and colloids, of which gum-arabic is a type - the former having high and the latter low diffusibility.

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  • 7rvevµa, wind, air), the branch of physical science concerned with the properties of gases and vapours (see Gns).

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  • A pneumatic trough is simply a basin containing water or some other liquid used for collecting gases.

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  • - Carbonic acid gas, carbonic oxide (CO) and some other irrespirable gases produce their effects practically by asphyxiation.

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  • The essential difference in construction is that in the first class the substances heated do not come into contact with either the fuel or the furnace gases, whereas in the second they do.

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  • This principle is capable of very wide extension, the blast furnace being mainly limited in height by the strength the column of materials or "burden" has to resist crushing, under the weight due to the head adopted, and the power of the blowing engine to supply blast of sufficient density to overcome the resistance of the closely packed materials to the free passage of the spent gases.

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  • damper G, which may be raised or lowered by a chain reaching to the ground, and serves for regulating the speed of the exhaust gases, and thereby the draught of air through the fire.

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  • Even under the most advantageous application, that of evaporation of water in a steam boiler where the gases of the fire have to travel through a great length of flues bounded by thin iron surfaces of great heat-absorbing capacity, the temperature of the current at the chimney is generally much above that required to maintain an active draught in the fireplace; and other tubes containing water, often in considerable numbers, forming the so-called fuel economizers, may often be interposed between the boiler and the chimney with marked advantage as regards saving of fuel.

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  • In reverberatory and air furnaces used in the different operations of iron manufacture, where an extremely high temperature has to be maintained in spaces of comparatively small extent, such as the beds of puddling, welding and steel-melting furnaces, the temperature of the exhaust gases is exceedingly high, and if allowed to pass directly into the chimney they appear as a great body of flame at the top. It is now general to save a portion of this heat by passing the flame through flues of steam boilers, air-heating apparatus, or both - so that the steam required for the necessary operations of the forge and heated blast for the furnace itself may be obtained without further expenditure of fuel.

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  • 1 2 a In iron-smelting blast furnaces the waste gases are of considerable fuel value, and may render important services if properly applied.

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  • Owing to the conditions of the work, which require the maintenance of a sensibly reducing atmosphere, they contain a very notable proportion of carbonic oxide, and are drawn off by large wrought iron tubes near the top of the furnace and conveyed by branch pipes to the different boilers and air-heating apparatus, which are now entirely heated by the combustion of such gases, or mixed with air and exploded in gas engines.

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  • The lecture explains the greenhouse effect and the percentage of each of the greenhouse gases in the atmosphere.

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  • Acid gases, given off when we generate electricity, mix with sunlight and water in the atmosphere to produce acid rain.

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  • adiabatic compression of gases and (alongside) oscillations in electronic circuits.

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  • adsorbed gases.

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  • This section deals with the adsorption of gases and vapors through solid adsorbents to form adsorbates.

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  • adsorption behavior toward the gases in a state of flow.

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  • Landfills are expensive to operate and require aftercare for many years following closure, in order to monitor leachate and gases such as methane.

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  • On heating strongly, the white solid ammonium chloride, decomposes into a mixture of two colorless gases - ammonia and hydrogen chloride.

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  • anaesthesiao possible to induce anesthesia with anesthetic gases, breathed through a mask.

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  • anaesthesiaence of its work on gases and vapors was to prove seminal in the development of inhalation anesthesia.

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  • antimony trioxide promotes charring of the resin, which reduces the formation of volatile gases.

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  • Plasma gases include argon, hydrogen, nitrogen and mixtures thereof, as well as air and oxygen.

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  • aversive gases.

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  • bifurcated fan in the location of flammable gases.

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  • Engines fuelled by methane biogas or gases from old coal mines normally cease to function if the methane concentration drops below 40 per cent.

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  • carbonic gases combine daily with ocean water.

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  • Flue gases leave the combustion chamber but will be cooled to below 50 ° C by incoming air in the secondary heat exchanger.

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  • compressed gases, Models, and Mechanical rigs to name but a few.

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  • condensation of water vapor from the flue gases.

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  • The properties are important in proportional counters, ionization chambers, drift chambers and in the prediction of the electrical breakdown of gases.

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  • Emissions of other greenhouse gases might also be affected by desertification.

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  • These include dioxins, acid gases, nitrogen oxide, heavy metals and particulates.

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  • Gaseous exchange at the tissues, partial pressure of gases, oxygen dissociation.

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  • dredge spoils, mining tailings and exhaust gases are unlikely to fall significantly.

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  • Elements from group 3 across to the noble gases all have their outer electrons in p orbitals.

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  • It is believed Mr Blair will outline key future policies aimed at curbing the emission of the greenhouse gases that cause global warming.

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  • emitter of climate change gases.

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  • Air Travel is the fastest growing emitter of climate change gases.

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  • Earth condenses from the hot gases of the Solar Nebula... January to early March: Hadean eon.

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  • Our projects also reduce emissions of greenhouse gases other than CO2, and convert these to carbon dioxide equivalents.

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  • exhaled gases many times with no problem, once well practiced.

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