Great caution is necessary in the use of any form of illuminating gas, since all produce asphyxiation. Accordingly, all gas fixtures of the house should be regularly inspected to see that there is no escape of the subtile, destructive fluid. The odor of escaping gas which is so unpleasant is really a blessing, in that it informs the householder of his danger. A cock that turns completely around and, after extinguishing the light, permits the escape of the gas, is more dangerous than a poisonous serpent. Yet there may be nothing radically wrong with this fixture, and the use of the screwdriver may make it as good as new. Gas should never be turned low when there is a draught in the room, nor allowed to burn near hanging draperies. Care should always be taken in turning out a gas-stove or a drop-light to do so at the fixture and not at the burner. This is not alone safer, but it keeps the rubber tube from acquiring a disagreeable odor from the gas that has been left in it.
Great economy in the consumption of gas may be secured by the use of Welsbach and other incandescent burners. Where these are not employed, care should be taken to select the most economical kind of gas tips, and to see that when these become impaired by use they are replaced.
In the large cities there is constant complaint of defective gas-meters, so much so that inspectors have been appointed to correct this abuse. It has been found, however, that many complaints have been unfounded because the housewives were not able properly to read the meter. Directions how to do this will therefore be found useful. A gas-meter has three dials marking tip to 100,000 feet, 10,000 feet, and 1,000 feet respectively. The figures on the second dial are arranged in opposite order from those on the first and third dials, and this often leads to an error in reckoning. However, there should be no trouble in setting down the figures indicated by the pointer on each dial. We first set down the figure indicated upon the first dial in the units place of a period of three places, then that indicated upon the second dial in the tens place, and then that indicated upon the third dial in the hundreds place. To these we add two ciphers, to obtain the number of feet of gas that has been burned since the meter was set at zero on the three dials. From this number we subtract the total of feet burned at the time when the preceding gas bill was rendered. This is generally called on the bill "present state of meter." The result of the subtraction will be the amount of gas that has been burned since the last bill was rendered. For example:
95,300, amount indicated on dial.
82,700, amount marked "present state of meter" on preceding gas bill.
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12,600, amount of gas for which current bill is rendered.
Equal care must be exercised when kerosene is used for illumination, since, while it is not so dangerous directly to life, it is the chief source of the destruction of property. Accordingly the nature of kerosene and the way it illuminates is a profitable subject of study if we would prevent destructive fires. Really, we do not burn the oil, but the gas that arises from the oil when liberated by the burning wick and becomes incandescent when fed by the oxygen of the air. While kerosene requires a high temperature for combustion, it is closely related to other products of coal oil, such as naphtha and gasoline, which become inflammable at a low heat and are therefore very dangerous. Since the cheap grades of kerosene approach these products in quality, care should be taken to see that it is of high "proof" in order to prevent explosions. The proof required of kerosene differs in various States; that in some is as low as 100 degrees Fahrenheit, that is, the temperature at which the oil will give off vapors that will ignite. This is too low a proof, for such a degree of temperature is quite common in the household. It is safe only to use that kerosene which is at least 140 degrees proof, for then, even though the oil is spilled, there is little danger that it will ignite except in the immediate presence of flame. There is no danger at all in soaking wood with this kind of oil in a stove or grate wherein the fire has gone out.
To test kerosene, put a thermometer into a cup partially filled with cold water, and add boiling water until the mercury stands at 130 degrees Fahrenheit. Then take out the thermometer and pour two teaspoonfuls of kerosene into the cup and pass over it the flame of a candle. If the oil ignites, it is unsafe.
In order to prevent the flame from running down into the lamp and causing an explosion, the wick should be soft, filling the burner completely. The highest efficiency in the form of illumination is obtained by round burners, especially those in lamps which admit air to the inside of the wick and so induce the largest possible amount of combustion. Such a lamp produces quite a high degree of heat, and will answer the purpose of an oil-stove in a small room.
Contrary to the popular idea, wicks should be carefully trimmed with scissors rather than with a match or other instrument. In extinguishing a lamp one should first turn down the wick and blow across the chimney, never down the chimney.
Owing to the fact that the wick is constantly bringing up oil by capillary attraction, whether it is lighted or unlighted, lamps in which the wicks have not been cared are kept continually greasy. In fact, a lamp that is greasy or that gives out a bad odor is one that has not been properly cared. With due attention, lamps are as clean and handy a means of illumination as any other form.
Candles, that are now used chiefly for decorative purposes, may still be practically employed for carrying light about the house. The danger from a falling candle carried by a child up to bed is not nearly so great as that which may result from either spilt oil from a broken lamp or the cutting glass of its chimney.