Gasholder

“ Some of these have arrangements for agitating the gas with a purifying liquid by mechanical means, the motion being supplied by a steam engine.
The gasholder, as it sinks in the water of the cistern, presses with less force on the contained gas, and unless this inequality of pressure were counteracted there would be very unequal velocities in the flow of gas from the burner. The equality of pressure is obtained by making the weight of the chains by which the gasholder is suspended equal to half the weight the gasholder loses in the same length of its motion. ”

“ It is possible to make the gas only as and when it is required, or it is possible in the space of an hour or so, during the most convenient part of the day, to prepare sufficient to last an entire evening, storing it in a gasholder till the moment arrives for its combustion. ”

“ The purified gas now passes to a gasholder (sometimes known as a gasometer) , which may be either single lift, i.e. a simple bell inverted in a tank of water, or may be constructed on the telescopic principle, in which case much ground space is Gasholder. saved, as a holder of much greater capacity can be contained in the same-sized tank. The tank for the gasholder is usually made by excavating a circular reservoir somewhat larger in diameter than the proposed holder. A banking is allowed to remain in the centre, as shown in fig. ”

“ Upon the mains at their exit from the works valves are placed, each valve having a revolving pressure indicator attached, the paper of which is graduated into inches, and tenths, and marked with spaces corresponding to the twenty-four hours of the day. In the meter-house self-regulating governors are used for this purpose. From the gasholders the gas is driven through cast-iron mains or pipes, and from them by wrought iron service pipes to the lamps and burners which help to illuminate our Metropolis. ”

“ This gas is known as carbureted hydrogen, or fire damp. As it is lighter than atmospheric air, it rises to the roof of the mines in which it is found, and is there mixed with the mine atmosphere, by occasional disturbances or by the process of diffusion. Unmixed with other gas, carbureted hydrogen destroys human life. But when the gas is largely diluted by atmospheric air—say, thirty parts by volume of atmospheric air to one part of the gas—the presence of fire damp is made known to the miner by a pale-blue cap with a brownish tinge over the top of the lamp flame. ”

“ It will be remembered that the amount of gas obtained by distillation, from the very best coal, ranged between 10,000 and 16,000 cubic feet. Water-gas contains as a rule 40 to 50 per cent, of hydrogen, 30 to 40 per cent, of carbonic oxide, 10 per cent, of naphtha or petroleum gas, and a few per cent, of carbonic acid. The large proportion of heavy petroleum-gas (sp. gr. 0.600 to 0.700) and carbonic oxide (sp. gr. 0.967) makes its specific gravity much heavier than that of coal gas ”

“ When the carbonic acid is absorbed by lime-water, if the gasses have been properly proportioned, no gazeous residue is left, except accidental impurities. Though carburetted hydrogen gas, is sometimes naturally produced in coal-mines, and occasionally mixes with common air, producing dreadful explosions, yet when coal-gas is mixed with common air, it does not explode unless the gas be to the air as 1 to 10 nearly. Such are the leading chemical habitudes of this gazeous product. The varieties of carburetted hydrogen gas all agree in being inflammable ”

“ They are consequently as far as possible removed as impurities in the process of gas-making. These are nitrogen, carbonic acid gas, and the destructive sulphur compounds, sulphuretted hydrogen and carbon bisulphide vapour. It is to the last two to which are to be attributed the injurious effects which the burning of gas has upon pictures, books, and also the tarnishing which metal fittings suffer where gas is burnt, since they give rise to the formation of oil of vitriol (sulphuric acid) , which is being incessantly poured into the air. ”

“ In addition to the consumption of oxygen and production of carbonic acid by the use of common gas, the gas itself, owing to defectiveness of the burner, is projected into the air. Now, considering the deleterious nature of all illuminating gases, the reasons for perfect ventilation of rooms in which natural gas is used for heating and culinary purposes are self-evident, not alone as a protection against explosions, but for the health of the occupants of the house, remembering that a larger supply of oxygen is said to be necessary for the perfect combustion of natural than of common gas. ”

“ The third step in the manufacture is purification, which removes from the gas the noxious elements, chiefly carbonic acid and sulphuretted hydrogen. The first lowers the illuminating power very greatly: one per cent, being sufficient, it is said, to diminish it five per cent. The sulphuretted hydrogen and other sulphurous compounds give rise in burning to sulphurous and sulphuric acids which may injure, by their corrosive action, delicate structures, such as books, gilding, silks, etc., that are exposed to the air of the room in which the gas is burned. ”

“ It would certainly be esteemed one of the greatest discoveries of the age if any one could succeed in condensing coal gas into a white, dry, solid, odourless substance, portable, and capable of being placed upon a candlestick, or burned in a lamp. Wax, tallow, and oil, are combustible gases in a solid or fluid form, which offer many advantages for lighting, not possessed by gas: they furnish, in well-constructed lamps, as much light, without requiring the expensive apparatus necessary for the combustion of gas, and they are generally more economical. ”

“ Some mines are cursed with firedamp, that light thin gas which, floating on the heavier air, steals along the splintered roof of coal seams and gradually displaces the pure fresh current from the surface fans. But the bane of Neddrie No. 2 was carbonic acid gas, which, heavier than air, crawled along its floors and slowly rose, ankle-high, knee-high, breast-high, face-high, till it choked the life out of those who might be caught in its deadly embrace. ”

“ There is no escape of combustible matter unconsumed, which is so great a nuisance [101] in all our common lights. The products of the combustion are water and carbonic acid gas [21] . The accurate and elegant experiments of Dr. W. Henry have shewn in the most satisfactory manner, that considerably less carbonic acid is produced by the flame of coal-gas, than by that of oil, tallow, or wax [22] , which [102] sufficiently refutes the absurd notions that have been circulated respecting the pernicious effects of gas-lights. ”

“ At this point let us note how a gas, suitable for an engine, is manufactured at least cost, the outlay being much less than in the case of illuminating gas which represents but one third of the coal placed in the distilling retorts. Instead of this process of distillation, “producer” gas is due to a modified combustion which gasifies all the fuel. In a producer of standard type, atmospheric oxygen comes into contact with the glowing carbon of the coal or wood, forming carbon dioxide, CO2. The heat generated by this union is taken up by the carbon dioxide and the nitrogen of the supplied air. ”

“ When we see the process which is necessary in order to obtain pure gas, we begin to appreciate to what an extent the atmosphere is fouled when many of the products of distillation, which, as far as the production of gas is concerned, may be called impurities, are allowed to escape free without let or hindrance. In these days of strict sanitary inspection it seems strange that the air in the neighbourhood of gas-works is still allowed to become contaminated by the escape of impure compounds from the various portions of the gas-making apparatus. ”

“ In some processes for the manufacture of this gas, the petroleum or naphtha gas is not mixed with the water-gas until the latter has been purified; in others the petroleum is added directly to the coal. Anthracite coal, only, is used in the manufacture of water-gas, and great care is necessary to keep the temperature up to a white heat, since, if it falls too low, a large proportion of carbonic acid will be formed, and will injure the illuminating power of the gas unless it is removed by purification. ”

“ Oxygen gas will not burn of itself, but it aids the decomposition by fire of bodies that are combustible. It is therefore called a supporter of combustion. But hydrogen gas, though it burns of itself [Pg 35] will extinguish a flame immersed in it. It is therefore said to be a body which will burn, but will not support combustion.
"As coals are to burning coals, and wood to fire; so is a contentious man to kindle strife."—Proverbs xxvi.
46. What becomes of the nitrogen that is inhaled with the air? ”

“ Neither he nor I opened the windows, because of the rain, as you know. Somehow, just how I cannot say, a slow stream of carbonic-acid gas finds its way into this room. It is the product of combustion, as you of course know, and is produced in large quantities by burning coal. It may come through the register from the furnace, or from some peculiar action of partially slacked lime in the plaster [292] of the walls. Wherever it comes from, being heavier than air, it slowly settles to the floor, where it collects, becoming deeper and deeper, just as water collects and rises in a tank. ”

“ Hence it has been termed oily carburetted hidrogen, or olifiant gas—it consists of carburetted hydrogen, supersaturated with carbon. The oil generated is heavier than water, whitish, and semi-transparent. By keeping, it becomes yellow and limpid; its smell is highly fragrant and penetrating—its taste somewhat sweet—it is partly soluble in water, imparting to it, its peculiar smell. A portion of this gas always accompanies the common carburetted hidrogen obtained from coal, and those sorts of coal that afford the largest quantity of it are best suited for the production of gas-light. ”

“ Hydrogen is an invisible gas, and the lightest known body in the world, being many times lighter than oxygen. It is combustible and gives out much heat. In our gas establishments it is made in large quantities and combined with carbon for illuminating streets, shops and dwellings. It is the source of all common flame. When united with sulphur in coal mines it becomes explosive. By passing a current of steam through a hot iron tube partly filled with filings, hydrogen gas is given off and burns with a pale yellow flame. ”

“ Emerson Dowson invented an apparatus for manufacturing a gas suitable for power plant, the gas being known as Producer or Poor Gas, the last term referring to its poorness in hydrogen as compared with coal and other gases. While the hydrogen is a desirable ingredient in an explosive charge, it must not form a large proportion, since under compression it renders the mixture in which it takes part dangerously combustible, and liable to spontaneous ignition before the piston has finished the compression stroke. ”

“ Illuminating gas is obtained by the dry distillation of coal. The products of distillation are subjected on the gasworks to several purifying processes, such as condensation in coolers, moist and dry purifying, from which valuable bye-products (such as tar, ammonia, cyanogen compounds) are obtained. The purified gas is stored in gas holders containing on an average 49 per cent. hydrogen, 34 per cent. methane, 8 per cent. carbonic oxide, 1 per cent. carbon dioxide, 4 per cent. nitrogen, and about 4 per cent. ”

“ If carburetted hydrogen be mixed with a sufficient quantity of oxygen gas or common air and fired by the electric spark, or by any other method, an explosion takes place more or less violent according to the quantity of carbonaceous matter condensed in the hydrocarbonat; and the remaining gas consists of carbonic acid, together with any unconsumed gas, or excess of oxygen, whilst the water condenses in drops on the sides of the vessel. A few cubic inches of the mixed airs is as much as can be conveniently managed at a single explosion ”

“ Why, after Sue gets back with the piece of iron, we will go down and set the ball of the pipe in Katie's fire. When it gets hot, we shall see a smoke coming out of the pipe, which will be composed chiefly of hydrogen gas: we will touch a match to it, and there will be a flame at the end of the pipe until all the hydrogen which was in the coal in the ball of the pipe has united with oxygen. That is one way to make gas on a very small scale. ”

“ When heated in close vessels much more gas is obtained than when burnt in the open air. If moistened charcoal be put into an earthen retort and heat be applied till the retort becomes ignited; gas will be evolved, consisting partly of carbonic acid, and partly of carburetted hidrogen. A gas of similar properties is obtained by causing steam to pass through a tube filled with red-hot charcoal; by passing spirit of wine, or camphor, through red-hot tubes; by distilling oils, wood, bones, wax and tallow, or any animal or vegetable body whatever. ”

“ This last assertion requires substantiation; for it is at least a grave theoretical error to add a non-inflammable gas to a combustible one, as is seen in the lower efficiency of all flames when burning in common air in comparison with that which they exhibit in oxygen; while from the practical aspect, so harmful is carbon dioxide in an illuminating gas, that coal-gas and carburetted water-gas are frequently most rigorously freed from it, because a certain gain in illuminating power may often thus be achieved more cheaply than by direct enrichment of the gas by addition of hydrocarbons. ”