its safety. One firm sends a mixed gas of good quality in metal bottles to the consumer, the bottles being placed in a metal closet above ground outside the house. The firm claims that an explosion has never occurred.
Gas is measured by the cubic foot, and its price estimated per 1000 cubic feet. The amount is recorded on a meter as the gas passes into the house. See Fig. 13. It is an easy matter to learn to read a meter, and every one should do so who uses gas. Always compare the gas bill with the amount recorded by the meter. If the gas bill becomes larger than usual, and you feel sure that the consumption has been normal, report the matter to the company. A meter may be out of order, and need repair.
Fig. 13.—Reading the gas meter. Courtesy of New York Consolidated Gas Co.
To read the meter.—Figure 13 shows the three dials found on the face of a gas meter. The arrows show the direction. The dial at the right indicates 100 cubic feet between the numbers, the middle dial 1000 and the left-hand dial 10,000. The dials in this figure record 53,250 cubic feet. The price of gas varies from eighty cents to a dollar and a half per thousand cubic feet. “Eighty-cent gas” is the hope of many a consumer. At a dollar and a half it is not a cheap fuel.
Gas does away with the handling of coal and ashes in the kitchen and is thus a clean and labor-saving fuel. It gives an intense heat the moment the flame is lighted and this heat is easily regulated in a well-made stove. The flame should burn with a clear blue or greenish color. With a properly constructed stove only a small percentage of the heat is lost. In all these points it has the advantage over coal. The comparative cost is studied in the problems on page [53].
Natural gas is used in those regions where it occurs, piped to the house from a central source. It is found in limited areas only, and in some places has already been exhausted.
Coal oil, or petroleum, sometimes found oozing from crevices in rocks, or even floating on water, is a natural inflammable oil stored in the earth. It was known in ancient Persia, Greece, and Rome, but did not become of great commercial importance until the middle of the nineteenth century. It is now obtained by boring wells, and is found in great quantities in certain regions of the country. The crude oil yields many products valuable in the arts, medicine, and manufacture. Kerosene is the substance useful as a fuel and for giving light. When of good quality it is nearly colorless, and the flashing point should be 149° F., or 65° C. This flashing point is the temperature at which the vapor from the kerosene explodes or flashes. If the vapor flashes at a point lower than this, it means that the oil has not been sufficiently refined; that is, in the process of manufacture the substances that flash at a low temperature have not been removed, and therefore the oil is less safe.
Kerosene is sold by the gallon or barrel. The price for a good quality is about seventy cents for a five-gallon can. By the barrel a saving is made of several cents a gallon. It is useful as a fuel to those housekeepers who cannot have gas, and who find it a convenient substitute for coal in the