Mechanical Devices in the Home

CHAPTER IX

Steam-Heating Systems

70. Equipment for Steam Heat. A steam-heating system consists of a boiler, a fire pot, pipes from the boiler leading to the radiators, and radiators (Fig. 35). On some systems, return pipes are provided to carry condensed steam or water back to the lower part of the boiler. A safety valve (Fig. 36) is attached to steam-heating systems instead of an expansion tank. This keeps the pressure of the steam in the boiler from becoming too great, and thereby prevents an explosion. The pressure gage (B, Fig. 35) must be set, and, when set, should only be changed by a person understanding it. Build and manage the fire for a steam boiler the same as for any stove or furnace. Keep water in the boiler at 212 degrees Fahrenheit, so steam may form, for without it, the radiators will not be heated. Small valves are attached to most steam radiators. Their purpose is to let out air, which accumulates in the radiator. As soon as the steam begins to come into the radiator, it forces the air out of the valve. When it reaches the valve, the heat in the steam causes part of the valve to expand and close the outlet, which is small. When the radiator is hot, steam should not escape, provided the valves are in good working order. There is a gage (Fig. 37) furnished with each boiler which shows how much water is in it.

Keep enough water in the boiler to come within certain lines on the indicator. The top of one of these lines is usually six or eight inches from the top of the boiler. There is always some variation in the amount of water in steam furnaces on account of the formation and condensation of the steam in pipes and radiators. See that the boiler is never empty, but do not put in fresh water except when necessary.

The space above the water in the boiler is left for steam. The loss of water from a boiler in good working order is thru the air valves in the radiators. If the furnace is properly managed, very little water should be lost during the course of a year, so there is little need for adding water.

Some furnaces have two pipes to the radiators. When steam is shut off from a radiator, the valve leading to the pipe which carries off the water from condensed steam must be closed, also, to prevent the pressure of the steam in the boiler from forcing water from the boiler up this pipe. This may happen because the pipe draining the water from the radiators enters the furnace near the bottom of the boiler. The steam being retained in the furnace presses down on the water and so may force water up the drain pipe, if it is not closed, instead of raising the safety valve.

Carelessness of this kind may work much damage, for by this means all the water from the furnace can be forced up into the radiators, leaving the boiler empty. This makes it important that every woman should understand the steam-heating system in her home.

Some steam-heating systems have a check valve in the pipe which returns water to the boiler. This valve permits water to flow thru it in but one direction; that is, toward the boiler. This prevents a rush of water from the boiler to the radiators.

Steam furnaces, also, are often equipped with another safety-valve device, which is a plug of metal which melts at a rather low temperature and is placed in the boiler directly over the fire. If the water line in the boiler falls low, this plug melts and steam from the boiler puts out the fire, thus saving the furnace from damage.

However, melting out the plug makes much work both in replacing the plug and in cleaning the fire box to rebuild the fire, so that it should not be depended upon to regulate the heat in the boiler.

Knocking in steam radiators occurs most often in those systems using the inlet steam pipe for the return of the water which has formed as a result of condensation. It is caused by water accumulating at some point and the steam coming up the pipe, violently forcing it back into the radiator. This only reaches a danger point in systems which do not have pipes of the proper size, or when the pipes do not slope gradually downward, so that all the water may flow back to the furnace. On cold days, there will be some knocking in a steam radiator when it is being heated in the morning. A two-pipe system, while it is somewhat more expensive, is less subject to this trouble.

71. Steam Gages. Steam gages (B, Fig. 35) are devices for indicating the pressure of steam within an inclosure. They are a kind of spring balance. When the pressure of the steam increases, it pushes up on the spring, and this turns the hand of the indicator, which shows the number of pounds of pressure that the steam is exerting on the inside of the boiler or container.

72. Safety Valve. A safety valve (Fig. 36 and A, Fig. 38) consists of a small opening to a boiler over which is a weight. When steam is developed until it makes enough pressure on the inside of the valve to raise this weight, some of the steam escapes, thus lowering the pressure on the inside until the weight falls back into place. Never let anything interfere with the action of safety valves.

Most safety valves have the weight attached to a lever which has a movable weight on it so that the position of the weight on the lever makes a difference in the number of pounds of pressure required to open the valve. By means of this device, the temperature of the inside of the boiler can be kept at one heat or another as desired, since this temperature increases or decreases with the pressure under which the steam is held.

Thus, fifteen pounds pressure means a different temperature from ten pounds pressure. Be sure to adjust the weight for the temperature desired. Pushing the weight toward the valve lessens the amount of pressure needed to open the valve. There is usually a steam gage on boilers to indicate the temperature and pounds of pressure inside. When the indicator reaches the point desired, the safety valve may be set so that all steam in excess of the desired amount will escape. When this is done, the temperature will be held constant in the boiler so long as a good fire under it is maintained.

CHAPTER X

Fireplaces and Heating Stoves

73. Construction of Fireplace. Fireplaces are an enlargement in the base of a chimney where fire is built. The upper part of the fireplace is sloped forward, and, in some cases, a damper is placed in the chimney to regulate the flow of air upward. The damper should not be so constructed that it will close entirely, for if it did, the smoke would come into the room. The fire in the fireplace burns best when the fuel is put in a grate or on andirons so that air can get under it and be drawn thru it by the draft of the chimney. A steady draft makes the combustion of the fuel complete and thus prevents smoking.

The hearth is made of fireproof material and should be wide enough to catch all sparks flying from the fire. A screen is often needed for safety from fire. Do not pile reserved fuel or put rugs on the hearth.

Fireplaces and chimneys should be built of fireproof brick, stone or concrete. Have them examined once a year for cracks, as these make them unsafe. The walls of the chimney and the fireplace should be thick enough to prevent danger from fire.

74. Management of Fireplace. The management of a fireplace is very simple. The draft up the chimney should be properly regulated so that the fire does not smoke. Sparks and bits of fuel should not be drawn up the chimney. The fire should be built so that it is not smothered. Air should circulate thru the fuel. Keep the ashes cleared away.

There are some fireplaces which are intended to heat rooms after the manner of hot-air furnaces. The heat and smoke from the fire pass upward thru a metal heater, encased by an air chamber. Much of the heat passes thru the metal, warming the air in the chamber. This warmed air passes thru pipes and registers into the rooms, while the smoke finds its way to the chimney. To complete the circulation of air, the cold air from the floor passes into the air chamber near the floor at the sides of the fireplace. Sometimes fresh air from the outside of the building is mixed with the air in the chamber.

If there is an opening in the floor of the fireplace, a damper should be put in this opening to regulate the flow of air. The heater in a fireplace must be kept free from soot and ashes. If the metal is covered with soot, heat will not readily pass thru it, and the soot will collect moisture and cause rusting.

One way to keep the heater clean is to regulate the draft up the chimney so that ashes and bits of burning fuel are not drawn into it. Also, the fire should be kept burning with a clear (not smoky) blaze. Soot is unburnt fuel.

75. Operating Heating Stoves. A stove is a device for holding the fuel and for permitting the heat to pass readily into the room. In the stove there is space below the fire for collecting ashes. There is an opening for fresh air to enter below the fuel, to aid combustion, and a damper above to act as a check draft when open, a chimney to carry off smoke, and one or two dampers in the chimney to regulate the draft.

When a fire is being built, close the draft over the fire box and open the one below; open the damper in the chimney—this allows the free passage of the air up the chimney.

76. Care of the Stove. Do not permit a large bed of ashes to accumulate in the bottom of a stove. A thin layer of ashes must be kept in the bottom of some wood stoves to keep the fire away from the metal bottom.

The polish or finish of the stove is a matter of taste. Some stoves are made of iron, which does not need blacking; some must be blacked. Blacking keeps them from rusting. All must be kept free from dust and dirt, as this accumulates moisture and causes the stove to rust.

Letting the stove get red hot warps it. It should not be permitted to get so hot.

The grate (Fig. 3) in stoves holds the fuel so that air can flow up thru it. If the grate is clogged with ashes, this cannot happen. The grate should be shaken to make the ashes drop thru. A clean grate is important to the complete combustion of the fuel. Shaking after glowing coals begin to fall is a waste of fuel.

When an attempt to shake the grate is made, it may suddenly refuse to move. In this case, something may have lodged between its parts, or it may have been shaken from its proper position. Shaking the stove too hard may displace the grate. The common remedy for a displaced grate is to let the fire go out, remove all ashes and cinders, and readjust the grate.

Some kinds of soft coal form "clinkers," and these catch in the grate. In burning fuel that makes clinkers, shake the ashes from the fire several times a day. Remove all accumulations in the fire box daily. Clinkers are made from substances which melt and recombine, forming a different material which is quite hard and does not burn. Constant attention to the fire prevents clinkers from forming in large masses.

CHAPTER XI

Gas, Electric and Kerosene Heaters

77. Kinds of Gas Heaters. There are several types of gas heaters—those using an illuminating flame and reflector, those fitted with a Bunsen burner and an asbestos back, and those heating water in a device like a radiator. The last two burn with a blue flame. All gas stoves ought to be fitted with a flue for discharging the products of combustion.

78. Bunsen Burner and Asbestos-Back Heater. The burner is a long pipe punctured with holes extending across the stove. There is an opening for mixing of air with the gas at the point where this pipe enters the stove, and a valve to regulate the flow of gas (Fig. 39).

79. Lighting Gas Stoves. To light the stove, open the valve, count three, and apply a lighted match to the burner. Counting three gives time for the pipe to fill with gas, so that the fire will not flash back and burn in the air mixer.

80. Care of Gas Stoves. The only care that this stove needs is to keep it polished so that it will not rust. Keep the burner clean of dust and soot. Be sure that the valve is entirely closed when the gas is turned off, and that the pipes fit tight at all connections so that gas cannot leak into the room.

81. Illuminating Flame and Bright Metal Reflector Heaters. These heaters are used with manufactured gas. They burn with an illuminating flame since there is no device for mixing air with the gas as it enters the stove. The bright metal reflector not only makes an attractive stove, but reflects the heat out into the room. Some stoves are made with tips of aluminum or other non-corrosive metal over the openings in the burner (Fig. 40). Gas logs are a type of gas heaters used in fireplaces (Fig. 41).

82. Gas Radiator Heaters. Gas radiators (Fig. 42) are another type of gas heater. The radiator is a coil of pipe. The heating unit is below the coil and works like any other Bunsen burner. A small amount of water is kept in the pipes. There is a device attached to the radiator to automatically adjust the height of the gas fire (A, Fig. 42).

83. Management of Gas Radiator. Put enough water in the radiator or coil of pipe to fill it to the depth of one inch. Keep this amount of water in it at all times.

Light a match, turn on the valve which lets gas flow into the burner, wait for it to fill with gas, and touch the match to the burner.

Most of these heaters are fitted with thermostats.

In about thirty minutes after lighting the gas, the water will have formed enough steam inside the radiator to automatically turn the valve lowering the gas flame. If the steam pressure falls low, the thermostat will permit more gas to flow into the radiator by automatically opening the valve.

There is a safety valve attached to the side of the radiator which opens if the automatic device fails to close off the gas before the steam pressure inside becomes too great.

84. Kerosene Heaters. Kerosene heating stoves have burners like those used on kerosene cook stoves. (See Chapter III.) Surrounding, or about, the burner is a jacketed air space. Here air is heated and rises to the upper part of the room while fresh air from the lower part of the room is drawn thru the jacket. Some heat is also given off by radiation. Fig. 43 shows a picture of an oil heater.

The burners of these stoves should be cared for the same way as the ones on cooking stoves. The stove should be kept polished and free from dust. This prevents it from rusting. Wipe off any kerosene which may accumulate on the outside, for it makes an unpleasant odor.

Take care in moving kerosene stoves not to jar the chimney or other parts of the burner out of place; otherwise the stove will smoke.

When the stove is lighted, turn the burner quite low. The flame will become higher as the parts of the stove become heated.

85. Electric Heaters. The electric heaters (Fig. 44) are composed of one or more coils of wire thru which the electric current flows with difficulty. This heats the coils so hot that they glow. A reflector throws the heat out into the room. The coil and reflector are attached to a pedestal. They are desirable for use in rooms which are not quite warm enough. Care must be taken to avoid getting an electric shock from electric heaters, as from any other electrical appliances. If the stove seems to be out of order, have it put in order before using. Take care not to touch a water pipe or gas pipe at the same time when touching the heater in the bathroom, as there is a possibility of getting a shock.

86. Acetylene Heaters. Acetylene heaters are similar to the Bunsen burner and asbestos-back gas heaters. They are provided also with copper side reflectors. They are used only in localities where gas or electricity cannot be had.

Questions for Part II

PART III

Lighting Devices

CHAPTER XII

Electric Lights

87. Kinds of Electric Lamps in Use. The electric lamps on the market now are either tungsten (also called Mazda) or metallized carbon (called gem carbon) lamps. Of all lighting appliances, electric lamps and systems are most easily cared for. If properly selected, they make an excellent light from the standpoint of hygiene. It is important for every one to know enough about lighting to be able to select proper kinds and sizes of lamps.

88. Electrical Measurements. A volt is the unit of electric pressure which compares with the pound as the unit of water pressure.

An ampere is the unit of electricity flowing thru a wire which compares to the gallon as the unit of water per minute flowing thru a pipe.

A watt is the unit of electrical power. It is determined by multiplying the volts by the amperes.

A kilowatt equals 1000 watts.

A kilowatt hour equals 1000 watt-hours.

A watt-hour is the amount of energy needed by a device which uses one watt and is operated for one hour. For example, a 25-watt lamp uses 25 watts, and if it is operated one hour, it uses 25-watt hours of electricity.

The cost of burning an electric lamp is the number of watts marked on the lamp multiplied by the hours the lamp is burned, and then translated into kilowatt hours and multiplied by the price per kilowatt hour.

89. Carbon Lamps. Few carbon lamps are being made now, but they may still be obtained in some stores. The carbon lamp can be distinguished from Mazda lamps (Fig. 45) by the appearance of the filament. The carbon lamp gives about 0.40 candles of light per watt of electricity consumed. Carbon lamps burn, making a yellow or reddish light, and consume fully twice as much current as Mazda lamps of the same candle power.

90. Mazda or Tungsten Lamps. Tungsten lamps are the ones in common use. They give 0.80 to 1.00 candle of light to one watt of electricity used. They have a filament of tungsten and may now be used in any position. Less electricity is required to bring tungsten to a glowing white heat than other materials used in lamps.

To compare the brightness of two lamps, do not look at the filament, but hold pieces of white material like paper at an equal distance from each lamp and compare the brightness of the surfaces; or put an opaque object in front of the light and let a shadow be cast on another object. The brighter light will cast a heavier shadow.

When substituting a new tungsten lamp for a carbon lamp, select one about one-half the number of watts, unless more light is wanted. In houses, it is a common practice to substitute a 40-watt Mazda for a 50-watt gem carbon lamp, thus saving ten watts per hour and getting more light.

91. Selecting Lamps for a Room. There are so many possibilities for the use of electricity in lighting a house, that it becomes a fine art. When buying lights for a room, consider (1) the size of the room, (2) the use of the room, and (3) the color of walls, floors, ceilings, furnishings and decorations. For lighting purposes, lamps may be obtained ranging from 10 or less to more than 100-candle power.

There are colored, transparent and frosted globes. There are reflectors and shades of various colors and patterns. To obtain the same degree of illumination, smaller lamps are needed in small rooms than in large ones.

92. Effect of Color Schemes Upon Illumination. The color of the walls and furnishings makes a difference in the candle power required to give a certain amount of light. Those colors which absorb the most light require the higher candle power, and those reflecting the highest per cent of light require the lower candle power.

The frosted globes absorb some light, they diffuse the rest of it. They dispense with the annoyance of glare from lamps, and are useful in places where the full intensity of the lamps is not required.

The light absorbed by different colors varies considerably, as shown by the accompanying table:

TABLE SHOWING ABSORPTION OF LIGHT

93. Distribution of Light. Light in rooms for general use should be distributed as evenly as possible thruout the entire room. Avoid excessive contrasts of brightness and darkness. Have the lamps shaded to diffuse the light so that no one need look directly at the filament. When working by a light, do not put the lamp very close to the material, as this produces too strong contrasts of light and dark, or, when reading, it produces too much reflection from the white parts of the paper, which is trying on the eyes.

Direct lighting means that the rays from the lamp go directly into the room (Fig. 45). Indirect lighting means that the rays are all directed toward a reflecting surface such as the ceiling (Fig. 46). From here they are reflected, giving an even amount of light to other parts of the room. When directed toward the ceiling, they make it the brightest part of the room.

A semi-indirect light avoids this difficulty (Fig. 47).

In diffused lighting, the lamp is covered, as by frosting, so that the rays of light are broken up and so scattered that no direct ray shines into the eyes, and there is no bright spot of light in the room.

When costs must be limited, certain decorative effects must be weighed for their value, some being more expensive than others.

City lighting plants can provide current for any number of lamps in a house if it is properly wired. If more lamps are attached than the wiring will carry, and all are turned on, the fuses will burn out.

Electric plants for private homes (see Sec. 271) usually furnish current of a different voltage from city electric plants, so special equipment and lamps must be used with small plants.

Inquire of the company who installed the wiring or electric system, how many lights and other devices can be attached and for what voltage they should be made.

CHAPTER XIII

Gas Light

94. Construction of Mantles. A mantle is a device made of thread saturated with some fireproof material like a mixture of thorium and cerium which will glow, giving off a white light when heated hot. The mantle (A and B, Fig. 48) is placed over the burners of lamps using liquid or gaseous fuel. The gas is mixed with air so that it burns with a blue flame. The blue flame gives off little light, but it does not smoke and is much hotter than a yellow flame. When a mantle is placed over the blue flame, it is heated with less fuel consumption than is required to make a yellow illuminating flame. The light from the glow of the mantle is steadier and whiter than the light from an open flame, so that it is more hygienic.

Mantles are made in different patterns so that they may be used on upright and inverted burners. The inverted mantle throws more light downward than an upright mantle. This is advantageous in lighting a room, for most of the light is wanted in the lower part of the room. Mantles can be used on lamps burning gas, kerosene, gasoline, alcohol and acetylene if the burners are made to produce a blue flame. (See Figs. 48 and 52.)

95. Care of Mantles. Strong jars and drafts will break mantles, for they are very fragile. The explosion caused by burning back when the lamp is being lighted is most destructive to mantles. To save mantles, wait until the lamp has filled with gas before touching the lighted match to it.

96. Fixtures for Burning Gas. Gas will burn just as it escapes from a pipe. The flame of burning gas is yellow and makes considerable light. In order to secure more light for the amount of gas burned, put a tip on the end of the pipe, with a long, narrow slit in the top to spread the flame. These are usually lava tips. Natural gas gives very little light when burned in an open flame. Always burn it in mantle lamps. Its heating value is 1000 B.T.U. per cubic foot. When burned in a well-adjusted mantle lamp, natural gas will give about 15 candle hours per cubic foot. The heating value of manufactured gas is rated at 600 B.T.U. per cubic foot. It makes a fair light when used in an open flame burner. The yellow flame of burning gas makes considerable smoke, even when carefully adjusted. It gives four times as much light and no smoke when it is burned in a good mantle lamp.

In the special burner of the mantle lamp, the gas is mixed with air so that it will burn with a blue flame (Fig. 49). A blue flame is not good for lighting, but when a mantle is placed over the flame, it becomes heated, glowing hot. Since the mantle is made of a material which gives off a white glow, it lights the room with a steady light which is far better than the flickering light of the open flame (Fig. 48-a).

97. Adjustment. See that the ports thru which air is drawn into the lamp are open as wide as needed to give a clear, smokeless flame without firing back. Some lamps are fitted with a screw beside the cocks to regulate the amount of gas flowing into the lamp. It should be adjusted so that no more gas flows into the lamp than is needed to get as bright a glow as possible from the mantle. Regulate the gas flow by closing the valve attached to this screw until the mantle decreases perceptibly in brightness, and then slowly opening it until the mantle becomes bright. Gas companies often adjust lamps for their customers.

98. Care of Lamps. Clean the burners if they become sooted. Replace mantles if they are broken.

99. Lighting a Gas Light. When lighting a lamp, turn on the gas, count three, and then light the lamp. Counting three gives time for the burner to fill with gas and prevents burning back with an explosion. Mantles are very delicate and easily broken by jars or strong drafts. Burning back may break the mantle.

Burning back means that the gas ignites at the opening where it should be mixing with the air instead of at the tip of the burner. This happens when the lamp is lighted before it becomes filled with gas, or when there is too much air mixed with the gas.

100. Cold-Process Gasoline Gas. It is more economical to use cold-process gasoline gas with a mantle lamp than an open-flame burner for lighting. Be sure to use the burners made especially for this kind of gas. The lamps are managed like all others.

101. Acetylene Lamps. Open-flame burners are used for acetylene gas because no mantle burner has been constructed which will operate reliably with this rich gas.

Acetylene gas gives about ten times as much light per cubic foot as manufactured gas burned in an open flame. The burners require little care. Sometimes the holes in burners become stopped, and they should be cleaned out with a fine pointed instrument like a needle. When they do not work well, it pays to replace the old tips with new ones.

Acetylene gas burners are constructed so that a very fine spray of gas strikes another fine spray, which, when ignited, makes a broad flame. This flame, which is almost white, gives off light. The burners appear as illustrated in Fig. 50.

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.

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.

105. Lighting a Kerosene Lamp. When lighting a lamp, be sure it is in order and that any openings to the bowl are closed. Lift the chimney, turn the screw to raise the wick about one-eighth inch above the slit. Touch a lighted match to the wick, adjust the chimney, and, lastly, move the wick up or down until it burns clear and bright without smoking. After the burner becomes warm, the flame may grow higher and smoke. Do not leave a newly-lighted lamp unwatched. After the lamp is heated and adjusted, it should burn with a flame of even height.

106. To Extinguish a Lamp. Turn the wick down until it is slightly below the top of the slit. Do not turn too far. It will then go out of itself, or a slight puff of air will extinguish it. This is safer and will smoke the chimney less than attempting to blow out the full flame.

107. Care of Lamps. Keep the inside and outside of bowl and chimney clean. Wipe all soot from the burners. Trim the wick each day the lamp is used. Fill the bowl with oil to within one-half inch of the top. Get new wicks when the old ones become dirty.

108. Kerosene Mantle Lamps. Kerosene mantle lamps (Fig. 52) give three to four times as much light per unit of oil as the ordinary kerosene lamp. Many mantle lamps on the market are unreliable. Care, therefore, should be taken to give the lamp a trial before investing so as to be sure to get a good one.

The care and lighting of mantle lamps differ so much that the directions must be furnished by the manufacturer and should be followed with exactness.

CHAPTER XV

Alcohol and Gasoline Lamps

109. Classification of Lamps. Since the principle of operation is the same for most alcohol and gasoline lamps, they will be considered together.

These lamps may be divided into two classes—gravity lamps and pneumatic, or pressure, lamps.

110. Gravity Lamps. Gravity lamps have the tank elevated above the burner so that the force of gravity brings the fluid to the burner. It is usually a little to one side of the burner so that it cannot become heated by it. A pipe from the tank leads downward and either over the chimney or under the burner, where it will be heated by the flame of the lamp. When heated, it changes the gasoline or the alcohol to gas. The pipe carries the gas on to a point where it is mixed with air before it flows into the burner (Fig. 53).

111. Lighting the Gravity Lamp. In order to light these lamps, the generator must first be heated so as to make the gas. After this has once been done, the heat of the lamp keeps the generator hot. As soon as the gas is formed, light the lamp.

These lamps are furnished with mantles. The flame is blue and, consequently, gives out very little light, but much heat. The mantle covering the flame is heated to glowing white heat and gives off much light of a white color.

112. Pressure Lamps. Pressure lamps (Figs. 54 and 55) have a strong tank which holds air and fuel, whether alcohol or gasoline. Air is pumped into the tank so that it presses on the fuel with force enough to push the fuel up the pipe leading from the bottom of the tank to the generator. The air cannot get into the pipe so long as there is fuel which is heavier than air in the tank, because the pipe which leads to the burner starts from the bottom of the tank.

————

The generator for changing the liquid fuel to gas is placed between the burners of the lamp, of which there are usually two. After the generator has been heated, the lighted lamps keep the generator hot. The gas being very light, continues to rise. It passes thru a place where it is mixed with air, and goes on into the burner, where it is ignited. If the lamp burns low, more air must be pumped into the tank to force up the gasoline or alcohol. When all the fluid has been burned, the lamp will go out, since, then, only the air which is under pressure in the tank will be coming into the burner.

Extinguish the lamp by turning off the supply of fuel to the generator. To light these lamps, first heat the generator, as directed for the particular lamp in use, and then light the burners. Detailed directions cannot be given here, as they differ with different lamps.

113. Gasoline Lamps with Wicks. There are some gasoline lamps made with wicks which help conduct the oil into the burner, where it is changed to gas by the heat from the lamp, mixed with air and burned in a mantle. The flame, from a mixture of alcohol or gasoline and air, is blue and gives off little light, but much heat. It is used with a mantle.

114. Alcohol Lamps with Wicks. The wick of one type of alcohol lamp conducts the alcohol up thru a round tube which it completely fills. The tube prevents the fire from burning down into the bowl of the lamp. Alcohol makes a very hot and almost smokeless flame, even when little air is present. The mantle is put over the flame, and, when heated, gives a good light. Other ordinary fuels cannot be used on so simple a lamp because they would smoke the mantle.

115. Lighting Alcohol or Gasoline Lamps. Heat the conducting pipe at the point where the fuel is to be changed to gas. (Directions for this come with each lamp, and they differ considerably.) After being heated sufficiently, the valve leading to the burner is opened and the burner lighted with a match or torch. Use clean gasoline for these lamps, unmixed with water or other substances.

Questions for Part III

PART IV

Cooling Devices

CHAPTER XVI

Refrigerators

116. Principles of Refrigeration. Refrigerators (Fig. 56) are designed to prevent the rapid spoiling of food by keeping it too cool for the rapid growth of bacteria. They vary considerably in their efficiency, according to their construction and to the way in which they are managed. To preserve food and to save ice, the housewife must understand her refrigerator, and she must choose a good one. There is as much difference in the efficiency with which housewives manage their refrigerators as there are differences in refrigerators.

A series of experiments were conducted with a number of different makes of refrigerators. When the outside temperature was between 80 and 90 degrees Fahrenheit, and when the refrigerators were kept full of ice, it was found that the temperatures in different refrigerators varied between 45 and 60 degrees Fahrenheit. When the refrigerators were only partly full of ice, their temperatures rose several degrees.

The refrigerators which held a temperature of 45 degrees when filled with ice, or with 100 pounds, used 25 pounds of ice each in three days, while in the same three days, the ones which could maintain only a temperature as low as 65 degrees, used 50 pounds each. The warmer the inside of a refrigerator, the faster the ice melts.

In general, a refrigerator which maintains a low temperature is cheapest to operate. The refrigerator should be kept full of ice exposed so that it comes in contact with the air circulating within the refrigerator. The refrigerator which does not hold a low temperature will not only use more ice, but be less efficient in keeping food.

117. The Construction of Refrigerators. The construction of a refrigerator should be such that it may be kept clean. There should be no cracks and corners to catch dirt and make breeding places for molds and bacteria.

118. Lining Refrigerators. The best linings for refrigerators are porcelain, porcelain enamel, or glass for the more expensive ones, and galvanized iron or zinc for the less expensive ones. The shelves are usually made of heavy wire or of bent metal. The latter should be constructed so that they can be thoroly cleaned.

119. Insulation of Refrigerators. The more complete the insulation of a refrigerator, the more efficient it will be. Different kinds of material, as well as dead-air spaces, are used for this purpose. The top, as well as the bottom, must be insulated. Materials which are likely to crack or settle down and leave uninsulated spaces should not be used. Because sawdust settles, it is not satisfactory. There are felts, papers and other materials which are good. If the refrigerator is not water-tight and the insulating material absorbs water, it will lose its efficiency for insulation.

120. Circulation in Refrigerators. The better the circulation in a refrigerator, the more efficient it will be. The air in the refrigerator must be free to circulate over the ice. As it cools, it should drop to the bottom of the ice box. When it warms, it will rise and be displaced by fresh falling cold air. It should be free to rise to the top of the refrigerator and from there pass into the ice chamber and over the ice to be cooled again (Fig. 57). When the ice always melts unevenly and in the same relative place—that is, more on the side or bottom—it indicates poor circulation in the refrigerator.

121. Drip from Melting Ice. There should be a pan under the ice to catch the drip from the melting ice, and a drip pipe to carry it out of the refrigerator (Fig. 57). If the drip pipe passes into a pan set under the refrigerator, the pan should be emptied so that it will not overflow. The water in the pan should not be allowed to become stagnant.

If this pipe passes to a drain, it should not be attached to the drain, but drip into it. The small amount of fresh air passing up the drip pipe from the room is advantageous. Because some air does flow thru here, the drip pipe and the drain pipe must be clean and free from gases and odors.

The drip pipe should be straight and free from places in which dirt may collect. It must be removable, so that it can be cleaned. The doors of the refrigerator must shut so tightly that frost or dew will not form about their edges on a hot day.

122. Arrangement of Food in the Ice Box. Ice boxes are usually cooler at the bottom than at the top. Do not put food in the ice chamber because this necessitates opening the door and wastes ice. Do not put papers or flat boxes on the shelves which will interfere with the circulation of air in the refrigerator.

123. Filling and Care of the Ice Box. The housewife must open the doors of the ice box as seldom as possible, and close them quickly. Do not cut off the circulation of air from the ice by wrapping it in a blanket or newspapers. It cannot do its work then. The ice box is kept cold by the gradual melting of the ice. The ice melts fastest as the temperature of the ice box rises. Covering the ice may keep it from melting, but it will also allow the refrigerator to get warm, and so, whatever is gained in saving ice at first, will be lost at the higher temperature and in cooling the box again. Steady melting does the most good.

The shelves and drain pipe should be removable, and these and the refrigerator should be washed and thoroly scalded once in every two weeks.

There is a saving in planning to open the refrigerator as little as possible. The filling of the ice box with a large piece of ice two or three times a week, rather than with a small piece every day, is more economical.