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.

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

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

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

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

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

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

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

Whit to congressional mirror was placed inert gases in.

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

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

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

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.

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.

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

Wet or dry flue gas desulphurisation systems reduce emissions of volatile elements by concentrating the elements from flue gas desulphurisation systems reduce emissions of volatile elements by concentrating the elements from flue gases in solid or liquid streams.

How will the climate change in response to rising levels of greenhouse gases?

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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

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.

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

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.

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.

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.

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

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

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.

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.

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

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

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.

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.

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.

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

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

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.

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.

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.

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

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

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.

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

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.

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.

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.

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).

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.

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.

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.

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.

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

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

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.

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.

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.

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.

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

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

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."

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.

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.

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).

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."

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.

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.

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).

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.

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

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.

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.

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

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.

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

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.

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

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.

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.

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

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

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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

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.

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.

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."

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

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.

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.

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

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

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

For molecules of known gases the calculation is still easier.

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.

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.

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

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

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.

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

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.

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.

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.

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.

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

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.

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.

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.

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 }.

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

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.

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

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.

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.

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.

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

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).

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.

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.

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

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

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.

Methods of Rendering Gases Luminous.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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

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.

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.

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

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

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.

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.

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

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

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.

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

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

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

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

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.

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

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."

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."

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."

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.

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.

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."

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.

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.

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.

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.

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

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.

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

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.

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.

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

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

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

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.

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.

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.

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.

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.

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

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

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).

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.

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

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.

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.

For the properties of liquid oxygen see Liquid Gases.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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

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.

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.

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

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

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.

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.

Solar spectra are effects of those gases.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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).

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.

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.

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.

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

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.

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.

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.

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

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.

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

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

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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

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.

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

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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

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.

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.

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

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).

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

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.

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.

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 .

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.

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

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.

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.

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

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.

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.

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.

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.

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.

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.

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

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.

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.