=102. Care of Burners of Acetylene Lamps.= Keep the two holes open. Clean them with a large needle. See that there are no leaks about the burners or pipes. If these are found, fill with white lead or some similar substance, and tighten connections. If this does not suffice, the trouble should be referred to a plumber. Fig. 50-_a_ shows an acetylene burner. Acetylene lamp mantles can be used only with acetylene which is under high pressure. Therefore, they cannot be used with all plants. The special burner for mixing air with the acetylene to make it burn with a blue flame must be used with the mantle. CHAPTER XIV KEROSENE LAMPS =103. Construction of Kerosene Lamps.= A kerosene lamp consists of a bowl, a burner, a wick and a chimney. In the ordinary lamp, the bowl for holding the oil is placed below the burner (Fig. 51). The wick carries the oil from the bowl into the burner by capillary attraction--one end being in the oil and the other in the burner. [Illustration: FIG. 51. Lamps and lamp chimneys.] The burner, which has holes in it to let in air, holds the wick so that only the oil reaching the top burns. The area and shape of the flame depends upon the form of the top surface of the wick. The glass chimney is used to cause an air current thru the burner and to protect the flame from outside drafts. A screw moves the wick thru the burner. If the wick is too small, the fire may burn back thru the burner and ignite the oil in the bowl. It is important that a wick fit the burner. If the chimney is too short or broken, the lamp will smoke _(A_, _B_, Fig. 51). =104. Management of Kerosene Lamps.= When the lamp smokes, it is wasting fuel. Smoke is incompletely burnt fuel. The oil in the lamp should be clean. It should never be mixed with gasoline or other more explosive oils. Fill the bowl each day the lamp is used to within one-half inch of the top. A full bowl helps to make a safe lamp. Put the chimney on the lamp so that it fits in its holder. Keep it clean and bright. Keep the wick clean and trimmed evenly. See that it entirely fills the opening thru the burner. This prevents the fire from burning back down the burner and igniting the oil in the bowl. Oil will not pass up a wick which fits too tight. Do not cut a wick to trim it, but keep the charred part scraped or brushed off even with the top of the slit in the burner. A burnt match is useful for this purpose. [Illustration: FIG. 52. Mantle for kerosene lamp.]