GAS. inner side of the inverted chamber, round the top of the outer vessel, fits into the inside of the chamber round the bottom of the inner vessel, and enters it when that vessel has nearly ascended to the top of the tank. The water in the chamber retains the gas, and the two vessels then rise together. The inner vessel, it will be observed, ascends first; both then ascend and descend together, till the outer vessel has reached the bottom of the tank, on which it rests, and the inner vessel then also descends into the tank. Three gasholders, or lifts, as they are termed, are occasionally placed in the same tank. Before reaching the main-pipes, the pressure of the gas is regulated by the governor. In small estabfishments, the governor is very frequently dispensed the main; and where this cannot be attained, provision should be made for drawing off water. Gas-fittings.-The small pipes for fitting up the interiors of houses are either of wrought iron or of soft metal. To ensure permanent efficiency, it is of the utmost importance that these pipes should be capacious; they should be laid evenly, with an inclination towards the meter; and where the inclination is materially disturbed, a box should be provided for the collection and removal of water. Gas for street lighting is usually supplied by contract, a specified burner being used, and the lights being lighted and extinguished at stipulated hours. Lights in private establishments were originally charged for on the same system. The uncertainty of such a mode of charge directed the attention of gasengineers to the construction of meters at a very early period. Accordingly, in 1816, Mr Clegg took out his first patent for the wet gasmeter, which, as subsequently improved by Malam, Crosley, and others, came into general use about the year 1822 Dry gasmeters are now extensively manufactured on a principle first patented by Mr A. A. Croll, a gentleman who has also patented various modifications of the apparatus and processes used in the manufacture and purification of gas. The wet gasmeter consists of a hollow circular case, somewhat more than half filled with water. The measurement is made by the cylinder, a hollow drum or wheel, which revolves on a horizontal axis inside the case, the elasticity of the gas supplying the motive-power. The cylinder is divided into four chambers by partitions running in a slanting direction from back to front, and presenting a with, and the pressure adjusted with sufficient nicety by the regulation of the outlet valve. The governor consists of a small gasholder, the inletpipe to which is placed in the centre of the tank, and terminates with a plate having a circular orifice in its centre. In this orifice hangs a cone, which is attached to the crown of the small holder. When the gas is issuing slowly, the holder rises, taking with it the cone, and so restricting the orifice Wet Meter-front box open: the upper end; D, surplus or waste-water box. by which the gas enters. When the gas issues A, entrance pipe; B, valve chamber; C, float, with valve on rapidly, the holder falls, and with it the cone, thereby enlarging the inlet. The gas is conveyed from the works by mainpipes of cast iron, to which branch or service pipes are connected wherever a supply is wanted. The main-pipes require to be skilfully arranged with respect to size, carefully jointed, and laid with as few changes in their inclination as possible; but as such changes are unavoidable, it is necessary to provide for the removal of water, which, flowing along with the gas in the form of vapour, condenses in the pipes, and lodges at low points. For this purpose, a vessel, similar in construction to the tarwell, is connected to the main-pipe, and the water is removed by a pump. When little condensation is anticipated, and when there is no risk of the water affecting the flow of the gas, a small pipe merely is attached to the main, with a stop-cock to run off the water. The service-pipes should incline towards section of a four-threaded Archimedean screw. A convex cover is fixed on one end of the cylinder. This cover has an opening in the centre, which admits the pipe by which the gas enters the cylinder; the opening being below the surface of the water, so as to be sealed by it. The pipe, after entering the opening, is turned up, so that its mouth is above the water. The gas thus admitted within the cover, finds its way through a slit into one of the four chambers into which the cylinder is divided. The chamber which first comes into action is at the moment almost entirely under the water. The gas presses between the water and the partition of the chamber, and, in raising the partition, turns the cylinder on its axis, and brings the chamber above the water, filling it at the same time. The outlet slit of the chamber is on the side of the cylinder 637 GAS. opposite to the inlet slit, and is open to the case of the meter. It is not, however, directly opposite to the inlet slit, but is so arranged that it remains sealed under water till the chamber is completely filled with gas, by which time the revolution of the cylinder has brought the inlet slit of the next chamber above the water, and it is ready to receive the gas. The filling of the next chamber carries round the one already filled, causes its descent into the water as it revolves, and completely expels the gas by the outlet slit. Two chambers only can be in action at one time. These chambers are made with great accuracy, and are liable to no variation but the enlargement caused by the evaporation of the water and the consequent depression of the water-line. On the front of the case of the meter is placed a box, into which the axis of the cylinder extends, having a spiral worm-wheel on its end. The worm-wheel communicates motion to an upright spindle, which again moves the train of wheels by which the handles of the index are worked. The front box also contains the filling and overflow pipes for the supply and adjustment of the water, the entrancechamber by which the gas is admitted, and in which the float-valve is placed. This valve is supported and kept open by a float which descends, closes the valve, and shuts off the gas when the water is depressed too much. Wet Meter-side section. An act of the British legislature has recently been passed, according to which all gasmeters must be so constructed as not to register more than 2 per cent. in favour of the seller, and 3 per cent. in favour of the purchaser of gas. Thus allowing 5 per cent. for variation caused by the depression of the water-line on wet gasmeters. All meters fixed since the act came into operation must bear the seal of an inspector appointed under the act. Previous to the passing of this act, wet gasmeters were made so that when the water-line was properly adjusted, they could not measure more than 24 per cent. in favour of the seller, but they would register from 8 to 12 per cent. in favour of the purchaser before the water-line was sufficiently depressed to close the float-valve. In the arrangement adopted by Crosley, there was a defect which was unfortunately adhered to by many meter-makers in England, though it was abandoned by most of the makers in Scotland. This defect, known as the high spout,' arose from the pipe or spout which receives the gas in the front box, and conveys it into the cylinder, being made to project considerably above the water-line. This was intended to prevent the consumers of gas from being subjected to the inconvenience of their lights being rendered unsteady, or being extinguished by water coming over the edge of the spout and lodging in the bend which enters the cylinder; but if, in supplying water to the meter, the overflow-pipe which adjusts the water-line were closed, by the replacing of the plug before all the surplus water had run off, too much water would be contained in the meter, and its measuring capacity would consequently be restricted to the prejudice of the purchaser; and this having been ascertained to have occurred in various instances, much dissatisfaction was the natural result. The provisions of the act regulating measures used in sales of gas enforce the making of wet gasmeters with the low spout,' and consequently remove this objection entirely. Much skill and ingenuity have, since the passing of the act, been brought to bear on the construction and arrangement of wet gasmeters, in order to lessen, and, if possible, remove the risk of the float-valve closing more frequently than formerly, which it will be apt to do owing to the limitation of the descent of the water by the restriction of the variation of the measurement to 3 per cent. instead of from 8 to 12 per cent. against the seller. The dry gasmeter possesses some advantages, Dry Meter-front view open. which, were it in other respects equally esteemed with the wet meter, would give it the preference. Once adjusted, it gives no further trouble; it is not liable to derangement in frosty weather; and, in passing through it, the gas takes up no additional moisture to increase the risk of annoy. ance from deposit of water in the pipes. But doubts are entertained by many of the durability of the machine as an efficient and correct measure. The meter is made in various forms, and consists of chambers separated from each other by partitions; generally there are two, but some makers use three chambers. Each chamber is divided into two parts by a flexible partition which moves backwards and forwards, its motion being regulated by valves beautifully contrived for the purpose. The meter bears Dry Meter-side view open some resemblance to a double or triple steam-engine. Following out this resemblance, Mr Croll thus describes bis meter. 'It consists of a cylinder divided by plate ir GAS. the centre, into two separate cylindrical compartments, which are closed at the opposite ends by metal discs; these metal discs serve the purpose of pistons, and they are kept in their places by a kind of universal-joint adapted to each; the space through which the discs move, and, consequently, the means of measurement, is governed by metal arms and rods, which space, when once adjusted, cannot vary. To avoid the friction attending a piston working in a cylinder, a band of leather is attached, which acts as a hinge, and folds with the motion of the disc; this band is not instrumental in the measuring, so that if it were to contract or expand, the registering of the meter would not be affected, inasmuch as it would only decrease or increase the capacity of the hinge, the disc still being at liberty to move through the required space; the leather is also distributed in such a manner, being curved, and bending only in one direction, that it prevents any wrinkles or creases forming, and renders it therefore much more durable. The arrangement of the valves and arms are somewhat different to that of a steamengine, although similar in principle.' Consumers of gas should bear in mind, that the purpose of the meter is to inform them how much gas they are expending; and that while the seller of gas cannot visit it but at long intervals, the purchaser may from day to day, if he pleases, ascertain the quantity which has passed through the meter, and so detect irregularity or waste, which, if allowed to go on, would no doubt be put down to error on the part of the seller of gas. Gas-burners.-The burner made on the argand principle is still the best when carefully used, but it is expensive, somewhat troublesome to keep clean, and involves outlay for glasses from time to time. Jets and batwings have, consequently, almost supplanted it. These burners are now made by machinery at very low prices, so that to change them when out of order costs little, and is easily done. They are also very easily cleaned. Jets are of two kinds -cockspurs and union-jets. The cockspurs are pierced with one or more straight holes; the unionjets are pierced with two holes at an angle to each other, so that the streams of gas issuing from them impinge on each other, and produce a flat flame. Batwings are made with a clean slit across the head of the burner. Gas containing a great quantity of carbon requires burners with smaller apertures than gas containing little carbon, because when emitted too freely, the carbon does not come into contact with a sufficient quantity of oxygen, and the flame smokes again, when the gas is emitted in too small a quantity, the flame becomes blue, and its illuminating power is diminished, because the carbon comes too rapidly into contact with oxygen. The light is emitted by the carbon when suspended for an instant in the flame in an incandescent state, and the flame which is capable of suspending the largest proportion of carbon in a state of incandescence, ultimately consuming the whole of it, will give the most powerful light from the smallest quantity of gas. Accordingly, an opaque yellowish flame, which is just at the smoking point, is more economical than a bluish-white flame for lighting purposes. There are many contrivances for improved burners and improved modes of using gas. Of these it is enough to mention the sun-lights introduced by Mr King of Liverpool. These consist of a ring of unionjets, placed horizontally and set on the base of a cone which is passed through the ceiling, and conveys away the products of combustion through a flue, thus serving both for lighting and ventilating the apartments in which they are used. Regulators.-The object of these instruments is to restrict the supply of gas when superabundant, and it should be noticed that the supply requires to be so before any advantage can result from the use of them. A conical valve, operating by the pressure of the gas in a manner similar to the governor at the gas-works, is in general the acting part of the apparatus. The impurities which should be removed in the manufacture of coal-gas are sulphuretted hydrogen, ammonia, and carbonic acid. The presence of sulphuretted hydrogen is detected by allowing a stream of the gas to play on a paper wetted with a solution of acetate of lead, the test-paper is blackened if the deleterious gas be present. Ammonia is detected by allowing the gas to play on paper stained yellow with turmeric. Ammonia changes the yellow to brown. The presence of carbonic acid can be ascertained by causing the gas to bubble through limewater. If carbonic acid be present, it combines with the lime, and the water becomes milky. The value of gas for lighting depends on its illuminating power, which again mainly depends on the proportion of olefiant gas and heavy hydrocarbons contained in the mixture. The specific gravity of the gas would be a complete test of the illuminating power, were it first ascertained that no deleterious gases were contained in the mixture. The chlorine and bromine tests, which are applied by bringing the gas into contact with either of these substances in a graduated tube, also require that the absence of deleterious gases be ascertained. Chlorine and bromine condense the olefiant gas and heavy hydrocarbons, and the proportion of them present is ascertained by the proportion of the gas which is condensed. CANDLE DISC CAS-BURNER & METER Gas-photometer. The most practical mode of determining the illuminating power is by the use of the Bunsen photometer, introduced into this country by Dr Lyon Playfair, and adapted by Mr King of Liver pool. At one end of a straight bar of wood, a gasburner is mounted; on the other end, a candlestick. These are so placed, that when lighted, there are exactly 100 inches between the centres of the lights. GAS GASCOIGNE The bar is correctly graduated to shew how many times the one light exceeds the other. A circular disc of paper made semi-transparent, excepting a spot in the centre, which is left opaque, is placed at right angles across the graduated bar on a stand which slides along the bar. When the disc is moved into a position where the opaque spot is invisible, the lights are equal-the disappearance of the spot being caused by the light transmitted by the semitransparent part of the disc being equal to that reflected by the opaque part. The figures immediately below the disc indicate the power of the light. It is usual to compare a burner consuming five feet per hour with a sperm candle consuming 120 grains per hour, and when the quantities consumed during an experiment are not exactly in these proportions, the results are rectified by calculation. As has been stated, the illuminating power of coal-gas may vary from ten sperm candles up to nearly forty, though it is more than probable that either extreme is unknown to consumers; the cost of production, however, does not vary in the same ratio with the value of the gas, it being affected by totally independent causes, and these causes are so various, that the cost can hardly be the same in any two places. Another difficulty in contrasting the price of gas in different places, arises from the unavoidable variation in the quantity accounted for, the loss sustained under the head of condensation, leakage, bad debts, and waste, varies from 10 up to 30 per cent. on the whole quantity made; and though when this loss is excessive, the remedy should, to a certain extent, be in the power of the manufacturer, yet there is a considerable range within which the loss may vary owing to local and peculiar circumstances which the manufacturer cannot control. The price of gas being dependent on the cost of production and distribution, rather than on the illuminating power, and the changes in the former being less than the variations in the latter, gases of high illuminating power are more economical than gases of low illuminating power. The economy of gas for lighting purposes will be apparent when it is considered that 50 feet of gas, consumed in a burner at 5 feet per hour, will last 10 hours; while a sperm candle of six to the pound, and burning 120 grains per hour, will only last 9.722 hours. Assuming, however, that both will last 10 hours-a view which is in favour of the candle 1000 cubic feet will last as long as 20 candles; therefore, with an illuminating power of 15 candles, it will give an amount of light equal to 300 candles, or 50 lbs., which at 28. per pound would cost £5; at 20 candles it would equal 400, or 663 lbs., costing £6, 138. 4d.; at 25 candles it would equal 500, or 833 lbs., costing £8, 6s. 8d.; at 30 candles, it would equal 600, or 100 lbs., costing £10. Mr Rutter, author of a useful pamphlet titled Advantages of Gas in Private Houses (Parker and Son, West Strand), gives the following table, the experiments from which it is deduced having apparently been made with 12 or 14 candle-gas at 6s. per 1000 feet. for equal quantities of light, which, however, is not the measure of economy, just because no one is contented to take no more light from gas than from other modes of lighting; and second, because the gas-lights being fixed, more light is requisite in order to compensate the loss of the convenience afforded by a movable light. Five feet per hour of 15 candle-gas will fully supply the place of a pair of sperm candles, costing 8d. for 10 hours' light; while the gas at 58. per 1000 feet would only cost 3d. for the same time, and would yield a light 74 times as great. The use of gas for heating and cooking is becoming extensive. Its great recommendations are facility of regulation, readiness of application, and perfect cleanliness. In roasting by gas, the juices are retained in the meat to a greater extent than by the ordinary process; while in all the operations, the heat can be regulated with so much nicety, as greatly to aid the cook in presenting the food in the most wholesome and agreeable condition. Besides brilliancy of light, safety and cleanliness attend the use of gas. Explosions under ordinary circumstances are hardly possible the escape of gas is quite disagreeably perceptible by the smell when there is one three-thousandth part present in the atmosphere; and there can be no explosion unless with, at the least, 200 times that quantity, or 1 part in 15. Such accumulations will, and do undoubtedly, take place in confined situations, but ordinary precaution in avoiding the use of a light will avert the risk of accident. Gas, having a tendency to ascend, escapes near the ceiling of an apartment are more likely to form an explosive mixture than escapes occurring low down. Repeated accidents have happened through forgetfulness of this. It should be remembered that the situation must be considered a confined one when the gas is prevented from ascending freely. The standard work on gaslighting is that by the late Samuel Clegg, Jun, son of the inventor of the gasmeter, published by John Weale, London. There is also a smaller work by the same publisher, written by Samuel Hughes, C.E. After GASCOIGNE, SIR WILLIAM, an eminent English judge, belonging to a noble Norman family, was born at Gaythorpe, Yorkshire, in 1350. studying for the bar, he acquired considerable reputation as a pleader, and in 1398 was made serjeant-at-law. On the accession of Henry IV. in 1399, he was appointed one of the justices of the Court of Common Pleas; and in 1401, was promoted to be chief-justice of the King's Bench. In this high office he distinguished himself both by integrity and ability, and in the older English law reports are many abstracts of his opinions, arguments, and decisions. In July 1403, he was joined with the Earl of Westmoreland in a commission for levying forces against the insurrection of Henry Percy, the celebrated Hotspur. He was also nominated one of the commissioners to treat with the rebels. On this and another memorable occasion, he acted with a courage and rectitude which evinced that he was guided by the true spirit of judicial independence. On the apprehension of Scroop, archbishop of York, he refused, at the command of the king, to sentence that prelate to death as a traitor, because the law gave him no jurisdic tion over the life of an ecclesiastic. Henry respected his uprightness, and knighted him the same year. When one of the dissolute associates of the Prince of Wales was arraigned before him for felony, the prince imperiously demanded his release, and on being ordered to leave the court, he rushed furiously up to the bench, and, it is recorded, struck the It must be remarked, that the above prices are chief-justice on the judgment-seat. G. immediately COMPARATIVE COST OF LIGHT PROM CANDLES, LAMPS, AND GAS. " " Tallow Candles (dips), Composite Candles, " Quantities and Prices of Candles and Oil. d. 0 14 0 14 1 lb. 0 7 21 (moulds), 1 lb. 09 21 0 Common Lamp Oil, Sperm Oil, 1 gall. 10 0 217 1 3 0 12 GASCON GASES. committed him to prison, when the prince, sensible of his misconduct, at once submitted. On being informed of the circumstance, the king thanked God for having given him 'both a judge who knew how to administer the laws, and a son who respected their authority.' G. was called to the first parliament of Henry V., but died the same year, December 17, 1413. He was twice married, and left numerous descendants by both his wives. GASCON, GASCONNADE. The term Gascon is now employed, in the French language, to denote a boaster or braggart, and Gasconnade to signify any extravagant or absurd vaunting-the inhabitants of the district once known as Gascony having long been notorious in this respect. An example may be given: a Gascon, on a visit to Paris, was asked by his city-friend what he thought of the colonnade of the Louvre. His reply was: Ah, it's not bad; it resembles pretty closely the back part of the stables at my father's castle!' There are in French, volumes filled with the original sallies of these humorous boasters. GA'SCONADE, a river of North America, rises in the south of the state of Missouri, and, after flowing north-east for 250 miles, joins the river Missouri about 40 miles below Jefferson City. It flows through a hilly country, covered with forests of pine and other timber, and rich in picturesque scenery. Great rafts of yellow pine lumber are floated down the river annually. GA'SCONY (Lat. Vasconia), formerly a district in the south-west of France, was situated between the Bay of Biscay, the River Garonne, and the Western Pyrenees, and is now included in the departments of Landes, Gers, Hautes Pyrénées, and the southern portions of Haute Garonne, Tarn-et-Garonne, and Lot-et-Garonne. It derived its name from the Basques or Vasques, who, driven by the Visigoths from their own territories on the southern slope of the Western Pyrénées, crossed to the northern side of that mountain-range in the middle of the 6th c., and settled in the former Roman district of Novempopulana. In 602, after an obstinate resistance, the Vasques were forced to submit to the Franks. They now passed under the sovereignty of the Dukes of Aquitania, who for a time were independent of the crown, but were afterwards conquered by King Pepin, and later by Charlemagne. Subsequently it became incorporated with Aquitania (q. v.). exhibit an entire absence of cohesion among their particles, and in this respect they differ essentially from liquids. A vessel may be filled either partially or completely with a liquid, and this liquid will have a definite level surface or limit. With gases, it is otherwise; they always perfectly fill the vessel that contains them, however irregular its form. Instead of cohesion, there is a mutual repulsion among their particles, which have a continual tendency to recede further from each other, and thus exert a pressure in an outward direction upon the sides of the vessel in which the gas is enclosed. This outward pressure is greater or less according as the elasticity of the gas is increased or dimin ished. Experimental proofs of the facts mentioned in this and the preceding paragraph may be found in Miller's Chemical Physics, in the first volume of Jamin's Cours de Physique, or in any standard work on Physics. In his Dalton long ago remarked that '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 at low temperatures and by strong pressure exerted upon the unmixed gases.' Various chemists, amongst whom we must especially mention Faraday, have accomplished all that Dalton foretold, and various but in the solid form. It occurred to Faraday, who gases can now be exhibited not only in the liquid has led the van in these investigations, that the most probable mode of obtaining gases (or rather what, under ordinary circumstances, would be gases) in the liquid state, would be to generate them under strong pressure. When thus produced in strong bent glass tubes, they continued liquid at low temperatures while the pressure was maintained; but on removing the pressure (breaking the tube), they instantly passed into the gaseous state. Memoir, published in the Philosophical Transactions for 1823, he announces that he has succeeded in liquefying chlorine, euchlorine (a yellow explosive gas discovered by Davy, and consisting of a mixture of chlorine and chloro-chloric acid), sulphuretted hydrogen, nitrous oxide, cyanogen, ammonia, and hydrochloric, sulphurous and carbonic acids. Since that time, by the joint action of powerful mechanical pressure (sometimes upwards of 50 atmospheres), and extreme cold, the number of liquefiable gases has. been so far extended as to include all except oxygen, hydrogen, nitrogen, nitric oxide, and coal-gas; and the following gases have been obtained in a solid form-hydriodic acid, hydrobromic acid, sulphurous acid, sulphuretted hydrogen, carbonic acid, cyanogen, ammonia, euchlorine, fluoride of silicon. The ammonia and sulphuretted hydrogen, when solidified, each furnished a white translucent mass, like fused nitrate of ammonia; euchlorine gave a transparent orange-coloured crystalline solid; while the other liquefied gases that were susceptible of solidi fication by the application of intense cold, furnished colourless transparent crystalline masses like ice. GASES, GENERAL PROPERTIES OF. The term gas-which is probably derived from the German word Geist, spirit-was employed by the older chemists to designate any kind of air or vapour. Macquer (q. v.) was the first chemist who limited the term gas to such elastic fluids as had not been rendered liquid or solid by a reduction of temperature. The only substances that gases are liable to be confounded with are vapours; but there is this essential difference between them, that the former are invariably aëriform at ordinary 'Oxygen remained gaseous under a pressure of 27 temperatures and atmospheric pressures, while the atmospheres at a temperature of - 166°, and a pressure latter under these conditions are solid or liquid, of 58-5 atmospheres at -140° was equally ineffectual and only assume a vaporous or apparently gaseous in producing its liquefaction. Nitrogen and binoxide form at relatively high temperatures. Thus oxy- of nitrogen resisted a pressure of 50 atmospheres; gen, hydrogen, nitrogen, chlorine, &c., are true with carbonic oxide, a pressure equivalent to that gases; while water, sulphur, iodine, &c., when of 40 atmospheres, with coal-gas, one of 32, and heated to certain definite points, become trans- with hydrogen, one of 27 atmospheres was applied formed into vapours. without effecting the liquefaction. In all these Their perfect elasticity is one of the most import-experiments, the temperature was maintained at: ant physical peculiarities of gases. Within the limits of all ordinary experiments it is generally true that the volume of a gaseous body is inversely as the compressing force.' See MARIOTTE'S LAW. In consequence of their extreme elasticity, gases 197 166°. Owing to the superior diffusiveness of the lighter gases, such as hydrogen, the apparatus began to leak at comparatively low pressures, and thus a limit was placed to the amount of pressure that could be applied to them.' 641 |