Gas
Illuminating, gas burned to produce light. Illuminating gas is of two kinds, natural and artificial. A natural gas is found in vast quantities, apparently produced by natural distillation from petroleum oil pools within the earth's crust. When a well is drilled into a cavern of gas, it rushes out with extraordinary force, pressure being sometimes as high as 800 pounds to the square inch. This gas has all the useful properties of kerosene oil. In the states bordering on the Ohio River extensive systems of pipes have been laid from gas wells to the principal cities. In this manner natural gas is introduced into manufactories, stores, hotels, and residences, to furnish power, heat, and light. The only expense is that of first laying the pipes. After a gas well has been used for a time, the pressure diminishes. When the pressure becomes too slight to force gas through the jets in the distant cities, it becomes necessary to seek a new well with which to connect the system of pipes. It is claimed by the experts of the United States geological survey that natural gas to the amount of 1,000,000,000 cubic feet, enough to light and warm a city of 100,000 inhabitants, is allowed to escape daily. Cities of California, Ontario, and China also use natural gas. Gas does away with the nuisance of smoke and ashes.
Artificial illuminating gas may be made from tar or petroleum, but it is obtained chiefly by heating soft coal. The gas rises from the coal and passes through pipes into a huge reservoir or gas receiver. This receiver is curiously constructed. It consists usually of a huge cylinder closed at the upper end, and working up and down, either in several sections like a telescope or else with the lower rim in a tank of water. This cylinder stands in a circular frame. Cords from the cylinder run over pulleys and are weighted at the outer end. The gas is introduced into the cylinder from below, and is driven by weight of this movable dome through street mains and supply pipes to the gas jets in the various street lamps and buildings where it is to be consumed. By changing the weights on the outer ends of the supporting cords, the weight of the movable cylindrical receiver may be varied at will. In cold weather the settling weight of the huge cylinder requires to be much greater than in midsummer. When gas is being manufactured rapidly, the receiver rises; during the hours of rapid consumption, the receiver sinks. This is why the height of a gas house changes so surprisingly. Inasmuch as it is necessary to tear up the streets to put in gas mains it is public policy to give a single company the exclusive right to manufacture and supply gas in a given city or district. In return for this privilege a city council is entitled to fix just prices for which gas must be supplied, to insist that all consumers who desire gas shall be permitted to have it, and to require that the gas supplied be of proper quality. Much difficulty has arisen in adjusting these questions of price and quality, however, owing to the impracticability of securing city councils disposed to protect public interests and at the same time do justice to those who have invested their money in building gas plants.
The amount of gas used by each consumer is determined by a gas meter or system of clockwork set in motion by the gas in passing through the supply pipe. The price is fixed usually at so much per thousand cubic feet. It varies greatly in different parts of the world. Some of the elements which should determine the price of gas are the distance from a supply of suitable coal, the cost of transportation, the nature of streets through which mains must be laid, as to whether they are rocky or sandy, the total amount of gas consumed by the city, also the evenness of consumption. A manufacturing city that uses a great deal of gas in the daytime is entitled to a cheaper rate than the city that consumes the same quantity of gas in a few evening hours. Some cities solve the question by supplying their own gas at cost to consumers. Others are well satisfied with prices charged by private gas owners.
Illuminating gas is poisonous. At least it causes death. People should be careful not to go to sleep in rooms in which gas is escaping from leaky jets. Gas must be turned off by a stopcock or faucet. The light should never be blown out.
The light yielded by gas is expressed in candle power. The light produced by five cubic feet of gas per hour is compared with that produced by a candle burning 120 grains of sperm per hour. Coal gas has a lighting strength of 14 to 18 candles; water gas made from oil runs from 18 to 27; acetylene goes up to 240 candle power.
The first use of coal gas as a means of heating and lighting is ascribed to an inventive Ayrshire Scotchman, William Murdock, who lived in 1754-1839. While in the employ of a mining company in Cornwall in 1792, he distilled gas from coal and lighted his office and workmen's cottages.
See Acetylene; Candle; Heating; Light; Franchise