Keep the tank filled. As soon as the indicator, which is attached to a cork which floats on top of the gasoline, shows that the oil is low, turn out the fire and refill the tank. Do not fill the tank to overflowing. Gases from the stove can only get into the tank when it is empty and while there is gasoline in the pipe to feed the stove. Gasoline gas is very inflammable and will cause an explosion if it becomes ignited. The tanks from gasoline stoves cannot be removed, as all the joints must be tight to prevent the escape of gasoline fumes as well as the oil itself. The opening to the tank must never be left uncovered, except for the few minutes while the tank is being filled. The greatest care is required in using a gasoline stove; in fact, they are so dangerous, that they should not be highly recommended for household use. The description and care of them are given here because some persons persist in using them when they desire a quick, hot fire in cases where fuel gas is not available. =33. When a Burner Blazes and Cannot Be Controlled.= When a gasoline stove burner blazes and cannot be controlled, first close the valve leading from the tank into the pipe. There will then be little gasoline to burn, and no gases can get back into the tank. _Keep clothing and water away from the blaze._ Remember that the stove is set on a metal frame which is not inflammable. Shield walls and other objects so that the burner may blaze high without doing damage. Clothing catches fire easily, but the metal stove will not be consumed. If the valves are shut, the blaze will cease when the gasoline has burnt out of the burner and pipe. If the gasoline continues to flow out of the burner in spite of turning the valve and there is a danger of its spreading to the floor or table, set a shallow pan under the stove to catch the gasoline. It can burn in this way with considerable safety. Do not attempt to carry a burning stove. Simply protect floor, walls and furniture from catching fire, and let the gasoline burn. =34. Changing Fuel in Vapor Stoves.= There are some stoves which are interchangeable, in that they may be adjusted to burn kerosene, gasoline or distillate. These are of the type called "vapor" because they change the oil to gas before it is ignited. A change from one kind of fuel to another should never be made without thoroly cleaning the stove and adjusting it to the fuel that is to be used. =35. Operation of Vapor Stoves.= It is safest to use kerosene in these stoves. Distillate is a name given to a different mineral oil product from kerosene or gasoline. To work well, these burners must be kept clean. (Fig. 17-_a_.) The operation of the stove is simple. Put enough fuel, such as alcohol, into a burner to heat it hot enough to change the oil to be used to gas and ignite it.