Gasometer

“ The weight of the chains must be equal to the specific gravity of the material of which the gasometer is composed, so as to compensate accurately for the quantity of water which the gasometer displaces, or what is the same, it must be equal to the loss of weight which the gasometer sustains, when immersed in the water ”

“ The water tank, whether sunk in the ground, or raised, must be of equal dimensions with the gasometer, both in breadth and depth. The improved construction which we are about to describe, affords a means of reducing the depth of the tank, dispensing with the bridge of suspension, and of increasing at pleasure the capacity of the gasometer, upon a given base; thus rendering a small apparatus capable, if required, of holding a large quantity of gas, the first cost of which will be considerably less than even a small gasometer constructed upon the ordinary plan. ”

“ The interior vessel which contains the gas is suspended by chains hung over wheels or pullies, to which weights are attached, so as to be just sufficient to balance the weight of the gasometer, all but a small difference, and allowing its slow descent in the manner which is found as nearly adapted as can be to the proper supply of the lamps. ”

“ When the gasometer is quite down, the inside of its top, a, rests on the ground; when the gas enters, it raises it up till the lower edge is but a few inches below the water, and is prevented from rising higher by frames which support it; when some of the weights, d d, are removed, the huge cylinder, a, slowly sinks down and forces the gas through the tubes, c c, to be burnt by thousands of consumers. About four cubic feet of gas is produced from every pound of coal used ”

“ Continuous apparatus, however, other than those that we now propose to occupy ourselves with, are not without some defects, for the gas is produced in them intermittingly and at intervals, and more rapidly than it is used, thus necessitating the use of a gasometer, numerous and large washers, complicated piping, and, besides, of an acid cock. ”

“ Then the gas is carried through the purifier, in which all other impurities are removed.
When thoroughly purified the gas passes into the gasometer. This usually consists of two round iron cylinders of nearly the same size, one inside of the other. The outside cylinder has no roof; the inside has no floor. The sides of the inner one go down into a trench filled with water. Its top is held up by the gas, which comes into it from the purifier. ”

“ The extremities of the pipes have small apertures, out of which the gas issues, and the streams of gas being lighted at those apertures burn with a clear and steady flame as long as the supply of gas continues. All the pipes which come from the gasometer are furnished at their extremities with stop-cocks to regulate the admission of the gas. The burners are formed in various ways, either a tube ending with a simple orifice, at which the gas issues in a stream, and if once lighted will continue to burn with the most steady and regular light imaginable, as long as the gas is supplied ”

“ If it were possible to construct huge gasometers and to draw together and compress within them the whole of the atmosphere, it would have been done long ago, and we should have been compelled to work for them in order to get money to buy air to breathe. ”

“ Before explaining the principle upon which the gas-engine and every other hot-air engine depends, I shall remind you of a few data with which most of you are already familiar. The volume of every gas increases with the temperature; and this increase was the basis of the air thermometer—the first ever used. It is to be regretted that it was not the foundation of all others; for it is based on a physical principle universally applicable. Although the volume increases with the temperature, it does not increase in proportion to the degrees of any ordinary scale, but much more slowly. ”

“ Steam appears to be quite as effective as carbon dioxid and is much more easily employed. That form of apparatus should be used which is the simplest in construction and has the least cubical content.
The measurement of the evolved gas is most simply made by collecting over lye in an azotometer, reading the volume, noting the reading of the barometer and thermometer and then reducing to standard conditions of pressure and temperature by the customary calculations. Where a very strong lye is used the tension of the aqueous vapor may be neglected. ”

“ In the case of the gas thermometer it is necessary to determine the expansion correction separately, as our object is to arrive at the closest approximation possible to the absolute scale. It is a common mistake to imagine that if the rate of expansion' of the bulb were uniform, the scale of the apparent expansion of the gas would be the same as the scale of the real expansion—in other words, that the correction for the expansion of the bulb would affect the value of the coefficient of expansion 1/T0 only, and would be without effect on the value of the temperature t deduced. ”

“ The gas passes through a meter for measuring accurately the quantity per minute which is consumed by the burner, and there is also a gauge for ascertaining the pressure. Another mode of estimating the illuminating power of coal-gas is by determining the quantity of carbon contained in a given volume. For, in general, the richness of the gas in carbon is a fair index of the quantity of its luminiferous constituents. This may be readily effected by exploding the gas with oxygen, and measuring the amount of carbonic acid produced. ”

“ At a central station steam-engines pump air into the pipes and keep up a continuous pressure of from four to five atmospheres. As there are several hundred kilometers of these pipes under the streets of Paris, they form a huge reservoir of compressed air at the ground temperature.
In the cooling room of a café they simply turn a little cock and admit the compressed air into the room. A gas meter measures the amount of air admitted and charges are made accordingly. ”

“ When the temperature and pressure corresponding to meter readings are known, the volume of gas under standard conditions may be obtained by multiplying the meter readings in cubic feet by 33.54 P/T, in which P equals the absolute pressure in pounds per square inch and T equals the absolute temperature of the gas at the meter. In boiler testing work, the evaporation should always be reduced to that per cubic foot of gas under standard conditions.
When natural gas is the only fuel, the burners should be evenly distributed over the lower portion of the boiler front. ”

“ The gauge used to estimate the degree of pressure to which the gas within the condensing tube was subjected was of the same kind as those formerly described, [5] being a small tube of glass closed at one end with a cylinder of mercury moving in it. So the expression of ten or twenty atmospheres, means a force which is able to compress a given portion of air into 110th or 120th of its bulk at the pressure of one atmosphere of thirty inches of mercury. ”

“ READING A GAS METER.--To register the quantity of gas that is consumed, a gas meter, as is shown in Fig. 1, is provided with three large dials, each of which has ten spaces over which the hand, or indicator, passes to indicate the amount of gas consumed, and with one small dial, around which the hand makes one revolution every time 2 cubic feet of gas is consumed. This small dial serves to tell whether gas is leaking when the stoves and lights are not turned on. ”

“ The bulb of a thermometer is kept well immersed beneath the surface of the oil, draughts are to be avoided, and the heat very slowly raised. From time to time, as the flashing-point is approached, the temperature is noted, and a very small flame, as a gas-jet issuing from a glass tube drawn to a fine point, is quickly passed across its surface, taking care not to touch the oil. A faint blue flame will flash across the oil when it reaches a temperature at which explosive gases are given off. ”

“ The 'manometer' is generally known as a pressure gauge.—TRANS.
[2] Ruhmkorff's apparatus consists of a Bunsen pile worked with bichromate of potash, which makes no smell; an induction coil carries the electricity generated by the pile into communication with a lantern of peculiar construction; in this lantern there is a spiral glass tube from which the air has been excluded, and in which remains only a residuum of carbonic acid gas or of nitrogen. When the apparatus is put in action this gas becomes luminous, producing a white steady light. ”

“ Radiation pyrometers of this type are generally calibrated by the method of sighting on the interior of an electric furnace containing a thermocouple or gas-thermometer by which the temperature is measured. The gas-thermometer has been employed for verifying the law of radiation up to 1500° C. but the difficulties of obtaining accurate results with the gas-thermometer increase so rapidly above 1200° C. that it is questionable whether any advantage is gained by using it beyond this point. ”

“ The density of the gasoline in Beaumé degrees is an index to the volatility, for the higher the degree as indicated on the hydrometer, the higher is the volatility at a given temperature, consequently a high degree gasoline will give a better mixture at a low temperature than one of a low degree. In cold weather all gasoline should be tested with a hydrometer when purchased to insure a grade that will be volatile enough for easy starting when the engine is cold. ”

“ We also saw that when molecules strike a heated surface they rebound with increased velocity, and hence produce an increased pressure against the surface, the greater the higher the temperature. According to this theory, then, we should expect to find the same atmosphere pressing unequally on equal surfaces if at different temperatures; and the difference in the pressure on the lampblack and mica surfaces of the vanes, which the motion of the radiometer-wheel necessarily implies, is therefore simply the normal effect of the mechanical condition of every gas medium. ”

“ While the calorific values of the different gases given in the accompanying table are approximately correct for gases burning in the open air at atmospheric pressure they develop widely different values in the cylinder of an engine because of the effects of compression and preheating. The table serves, however, as an index to the relative values of the fuels under ordinary conditions without compression. While natural gas has nearly eight times the calorific value of producer gas in the open air, its actual heat value in the cylinder is only about 45 per cent greater. ”

“ A gas fills any space within which it is confined. A cubic inch of a gas whose density has been measured, if set free in a space whose dimensions are a cubic foot, or a cubic yard, will fill the space. [5] Manifestly its density and tension will be lessened in proportion. It is the custom to say, therefore, that a gas has no specific volume of its own; its volume is that of the container.
Equal volumes of a gas, temperature and density remaining the same, contain an equal number of molecules. ”

“ In such an apparatus the fuel is completely burned and the heat generated by such combustion is absorbed by water, the amount of heat being calculated from the elevation in the temperature of the water. A calorimeter which has been accepted as the best for such work is one in which the fuel is burned in a steel bomb filled with compressed oxygen. The function of the oxygen, which is ordinarily under a pressure of about 25 atmospheres, is to cause the rapid and complete combustion of the fuel sample. ”

“ If cylinder standards are not available for a compound, the analyst may prepare reference gases based on gravimetric, barometric, or dynamic methods. In any case, the related mass, pressure, and flow measurements should be made with NIST-traceable equipment whenever possible. In general, methods which provide a stream of standard gas (dynamic methods) provide more reliable results than static methods, since the concentrations of static gases are more prone to change when reactions between the standards and the sampling system or absorption cell surface can occur. ”

“ If the gas be enclosed in a tube in which a liquid stands above the level of the mercury, the height of the column of the liquid being = H and its density = D, then the gas will be under a pressure which is equal to the barometric pressure less HD / 13·59 , where 13·59 is the density of mercury. By these methods the quantity of a gas is determined, and its observed volume reduced to normal conditions or to parts by weight. The physical data concerning vapours and gases must be continually kept in sight in dealing with and measuring gases. ”

“ The luminous source employed is a gas burner with reflector. This is placed in a walnut box in order to prevent any projection of heat upon the balance. This burner, thus isolated, is lighted for but one or two minutes at a maximum, at the end of each weighing. So, on fixing a thermometer in the cage, we find that no variation, ever so slight, occurs in the temperature. In order to effect a weighing, the gas being turned down to a taper, we proceed as with an ordinary balance until the extremity of the needle no longer emerges from the lower dial. ”

“ That is, equal volumes of gases expand equally with the same increase of temperature.
If a given volume of gas—say 1 cubic foot of oxygen—be introduced within a container, its pressure or tension noted, the same volume of another gas having the same tension may be introduced without an increase of tension of the mixture. Thus 1 volume of oxygen added to I volume of nitrogen will make but 1 volume of the mixture, having the same tension as each of the two gases. That is, one gas is practically a vacuum for another. This property has its limitations ”

“ It is necessary, in every gas light establishment, in order to know whether as much gas is obtained as might and ought to be produced, that it be previously ascertained by a series of experiments how much gas the species of coal used at the works is capable, on an average, of producing, and such data it is obvious, can only be obtained by means of an apparatus, which, like this gas metre, shall take measure of the quantities of gas supplied by the manufactory at all times, and under all circumstances. ”