Mechanics of the Household / A Course of Study Devoted to Domestic Machinery and Household Mechanical Appliances

by E. S. Keene

THE HOLLOW-WIRE SYSTEM OF GASOLINE LIGHTING AND HEATING

The hollow-wire system of gasoline lighting possesses the advantage of simplicity in construction and ease of installation that makes it attractive, particularly for use in small dwellings. The ease with which plants of this character are installed in buildings already constructed and its relatively low cost has made it a popular means of lighting. The same principle as that used in the hollow-wire system is applied to portable gasoline lamps in which a remarkably convenient and brilliant lamp is made to take the place of the customary kerosene lamp. Small portable gasoline lamps are now extensively used for the same purpose as ordinary oil lanterns. These lamps are convenient as a source of light, make a handsome appearance and are relatively inexpensive to operate.

Fig. 186.—Hollow-wire system of gasoline lighting with gravity feed.

The hollow-wire system as commonly employed is illustrated in Figs. 186 and 187. In the gravity type of the system as illustrated in Fig. 186, the supply of gasoline is stored in the upper part of the house in a tank T and conducted to the burners below, through a system of small copper tubes as indicated by the heavy lines in the drawing. The same tank is used to supply the gasoline for the stove R in the kitchen and the lamps L in the different apartments. The gasoline supply in this case, is obtained entirely by gravity. This type of plant is not approved by the National Board of Underwriters but its use is quite generally permitted. The storage of gasoline in this form should be done with caution as carelessness or accident might lead to serious results. With an arrangement of this kind the force of gravity gives the pressure which supplies the burners below but it would not be possible to use the lamps on the same floor with the tank.

Fig. 187.—Hollow-wire system of gasoline lighting with pressure-tank feed.

Where it is desired to use lamps on both floors, a pressure tank is employed for supplying the gasoline to the lamps, as indicated in Fig. 187. In this plant the pressure tanks S, T in the basement, furnish the pressure which forces the supply of gasoline through the small tubes to the lamps L in the different rooms and also to the stove R in the kitchen.

The means of furnishing the pressure for supplying the gasoline to the burners may be a simple tank as that in Fig. 188, or the more elaborate apparatus shown in the double tank of Fig. 189. Either style will give good results but the double tank requires the least attention in operation and is therefore more satisfactory in use.

The tank in Fig. 188 is made of sheet metal of such weight as will safely withstand the pressure necessary in its use. It is arranged with an opening E, for filling with gasoline, a pressure gage for indicating the air pressure to which the gasoline is subjected, and two needle valves; C, for attaching an air pump and D, to which the hollow wire is attached for distributing the gasoline to the places of use. The tank is filled with gasoline to about the line A, and then air pressure is applied with an ordinary air pump to say 20 pounds to the square inch. This pressure will be much more than will be necessary to force the gasoline through the tubes but it is intended to last for a considerable length of time.

Fig. 188. Fig. 189.

Fig. 188.—Simple gasoline pressure-tank.
Fig. 189.—Double-pressure tank for constant pressure service in gasoline lighting systems.

The principle of operation is that known in physics as Boyle’s law, that “the temperature being constant, the pressure of a confined gas will be inversely as its volume.” That is, if the tank is perfectly tight, the pressure above the line A, in the tank, will gradually become less as the gasoline is used and when its level is at the line B, where the volume is twice the original amount, the pressure will be one-half what it was originally, and will still be sufficient to force the gasoline through the tubes to the lamps. It is evident that once the tank is charged and the air pressure applied it will require no further attention until a considerable part of the gasoline is consumed. If at any time the pressure in the tank becomes too low to feed the lamps, a few strokes of the pump will raise it to the required amount.

While the single tank does the required work, its use is not perfect because the pressure is constantly varying. If a lamp is set to burn at a definite pressure, any decrease in the gasoline supply due to falling pressure will change the amount of light given by the lamp; while the variation in the pressure of the single supply tank is not great, a more perfect effect is attained in the double type of tank as that of Fig. 189.

The object attained in the use of two tanks differs with different manufacturers. The tank shown in Fig. 183, being intended to maintain a constant pressure on the gasoline, is quite different from those described in Fig. 197 in use with the central-generator system of lighting, to be described later. In Fig. 189 tank No. 1 is for air supply alone and tank No. 2 is the storage tank for gasoline. Between the two tanks is a pressure-regulating valve 6-7, which keeps a constant pressure on tank No. 2 so long as the air pressure of the tank No. 1 is equal or greater than the other. The gasoline in tank No. 2 will therefore be always under the same pressure and when the lamps are once burning the gasoline supply to each lamp will be a constant amount.

Tank No. 2 is separated by the head 13 into two compartments, marked 18 and 19. The connection between the two compartments is made by the valve 15 and the connection 16. The gasoline supply for the lighting system is taken from the lower chamber at the valve marked 17.

It is possible to refill this tank with gasoline while the system is working. To accomplish this, the air supply is cut off from tank No. 1, by closing valve 9 and the valve 15 is closed to retain the pressure on the lower chamber of tank No. 2. The screw-plug is then taken from the tube 12 and the tank refilled. The screw-plug is then returned to its place, the valves 9 and 15 are again opened and the regulating valve immediately restores the desired pressure.

The amount of pressure required on the system will depend on the height to which the gasoline is carried within the building. The pressure is generally 1 pound to each foot in height and to do the best work the pressure must be constant.

These plants may serve as a fuel supply for gasoline stove as indicated at R or any other source of domestic heating. The usual gravity supply tank is replaced by the hollow wire through which is the gasoline from the tank in the basement.

Mantle Gas Lamps.

—Mantle lamps that are intended for using city gas are much the same in construction as those using the cold-process gasoline gas; the styles of mechanism differ somewhat with manufacturers but all lamps of this kind possess the essential features that are common to all. Either of these gases may be used with open-flame burners, such as Fig. 193, but since the introduction of mantle lamps, the open-flame burners are rarely used for household illumination.

In the incandescent-mantle lamp, the light is produced by heating to incandescence a filmy mantle of highly refractory material. The higher the temperature to which the mantle of a lamp is raised, the greater is the quantity of light produced. The office of the burner is to produce a uniform heat throughout the mantle with the use of the least amount of gas. As ordinarily furnished from the mains, coal gas or gasoline gas is too rich in carbon to be used in mantle lamps without dilution. When gas is burned in a mantle lamp, it must contain sufficient oxygen—which is supplied by the air—to combine completely with the contained carbon and reduce it to carbon dioxide. If insufficient air is supplied, the lamp will smoke and the mantle will soon be filled with soot.

In the use of the various gases—made from coal, gasoline, kerosene, alcohol, etc.—as a fuel for the production of either heat or light, the form of the burner in which the gas is consumed is the most important factor of the system. Without burners in which to generate a satisfactory supply of heat for the desired purposes, mantle gas lamps would never have come into common use. An understanding of the mechanism of the burners of a system is of first importance because of the possibility of the failure of the entire plant through an improper adjustment of the lamps.

If complete combustion of the gas is attained in the burner, the greatest amount of heat will be evolved and the residue will be an odorless gas, carbon dioxide (CO₂). If the gas is not completely burned the odor of the gas is noticeable in the air. Incomplete combustion may be caused by an insufficient air supply, which causes a smoky flame; or if a larger flame is used than the burner is designed to carry, some of the gas will escape unburned. In either case the greatest amount of heat is not developed by the burner.

In most burners, whether for heating or lighting—in which gas, gasoline or alcohol is used as a fuel—the principle of operation is that of the Bunsen tube. One noticeable exception to this rule is the burners used with the central-generating systems where the Bunsen tube is a part of the generator.

The gas generated from any hydrocarbon will burn completely, only after being mixed with air or other incombustible gas, in proportions such as will completely oxidize the carbon contained in the fuel.

In Fig. 190 the familiar laboratory Bunsen burner affords an excellent illustration of the Bunsen principle which forms a part of all burners using gas as a fuel. The gas from the supply pipe issues from a small opening A into a tube B and by the force of its velocity the entering gas carries into the tube above it a quantity of air that may be regulated by the size of the opening. If the gas is burned without being first mixed with air, the flame will be dull and smoky but if air is admitted to mix with the gas, an entirely different flame is produced, the characteristic shape of which is shown in the figure.

Fig. 190.—Cross-section of Bunsen burner showing characteristic Bunsen flame.

The upper part of the flame C is known as the reducing flame; it is blue in color and intensely hot. The portion D is the oxidizing flame; it is pale blue, sometimes light green in color. The lower part E is the gas before it begins to burn. When burning in air, the Bunsen flame gives scarcely any light, all of the energy being expended in heat. In the gas stove where the burners are made up of a great number of small jets, it will be seen that each jet shows the characteristic features of the Bunsen flame.

The incandescent-mantle gaslight takes advantage of the heat generated by the Bunsen flame and produces an incandescent light that has revolutionized gas lighting. The flame of the Bunsen tube is burned inside a mantle which is rendered incandescent by the heat.

The incandescent mantle was invented by Dr. Auer von Welsbach and was known for a long time as the Welsbach light; but improvements in the process of making the mantles, brought other lamps of the same type on the market, when it became known as the mantle lamp. The first serviceable mantles were made in 1891 and from that time there has been a steady development in the gas-lighting industry.

The original mantles were made of knitted cotton yarn, impregnated with rare earths and are still so made; but the most durable mantles are now constructed from ramie or china grass. After being knitted, the mantles are impregnated with thorium nitrate, with the addition of a small quantity of cerium nitrate, and occasionally other nitrates. The mantles are then shaped and mounted; the fiber is burned out and the mantles are dipped in collodion to give them stability for transportation. When placed in the lamp for use, the collodion is first burned off and the remaining oxide of thorium forms the incandescent mantle. One style of mantle is now being made in which the fiber is not burned out until it is placed in the lamp. They are commonly used with gasoline lamps and give very good results.

Fig. 191.—Gas lamp with upright mantle.

The first incandescent-mantle gas lamps to be used were of the upright type, such as is shown in Fig. 191, and for a long time they were the only mantle lamps in use. While the upright mantle was a great improvement over the open-flame gas jet, the lamp was not satisfactory because of the shadows cast by the fixture and from the fact that a large amount of the light was lost by being directed upward from the incandescent mantle.

With the development of the inverted type, the mantle lamp was greatly improved. In the use of lamps of any kind, the desired position of the illumination is that in which the light is directed downward. In the inverted type of mantle lamp this feature is accomplished and adds materially to the efficiency of the light, because the rays are sent in the direction of greatest service. The upright mantle lamps are still sold but by far the greater number offered for sale are of the inverted type.

The essential features of all gas lamps used under these conditions are shown in Fig. 192, which represents the common bracket type of lamp. The gas-cock C, connects the lamp with the gas supply G. The gas escapes into the Bunsen tube, through an opening in the tip P, which is so constructed that the amount of gas may be varied to suit the required conditions. The brass screw nut N may be raised or lowered and thus increase or diminish the amount of escaping gas by reason of the position of the pin P. If the nut is screwed completely down the pin closes the opening and the gas is entirely shut off. When the lamp is put in place, the burner is adjusted to admit the proper amount of gas and so long as the quality of the gas remains the same, no further adjustment will be necessary. Any change to a richer or poorer gas will, however, require an adjustment of the burner to suit the mantle. The amount of gas admitted is only that which will produce complete combustion in the mantle when combined with the required amount of air. Each burner must, therefore, be designed for the mantle in use.

Fig. 192.—Mantle gas lamp showing details of Bunsen tube.

As the gas leaves the opening above the pin P, it enters the mixing chamber of the Bunsen tube and air is drawn at the openings A-A. The mixture of the gas and air is accomplished in the tube leading to the mantle M, where it is burned. In all lamps of this kind, there is a wire screen placed relatively as S, the object of which is to prevent the mixture in the tube from exploding—in case of low pressure—and thus cause the gas to ignite and burn at the point of entrance to the tube.

At any time the pressure is insufficient to send a steady flow of gas into the tube, the flame may “flash back” and ignite the gas at the point of entrance where it will continue to burn. If, however, the screen is interposed between the gas supply and the burner, the flame of explosion will not pass the screen.

In lighting the lamp, the gas is turned on and a lighted match is held under the mantle, the explosive mixture of gas and air fills the mantle and escapes into the globe, in which it is usually inclosed. As soon as ignition takes place the gas outside the mantle explodes with the effect that is startling but not necessarily dangerous. The escaping gas continues to burn and heats the mantle to incandescence.

The amount of escaping gas is regulated by turning the gas-cock to produce the greatest brilliance with the least flame outside the mantle. When used for household illumination, the intensity of the light is such as to be objectionable, when used directly; but when surrounded by an opal glass globe to diffuse the light, this is a highly satisfactory and economical means of lighting.

Open-flame Gas Burners.

—Gas jets of the open-flame type continue to be used to some extent but the more efficient mantle lamp has very largely supplanted lights of this kind. In the past, these gas lights were made in a great many styles and were known under a variety of trade names—the fish-tail burner, the bats-wing burner and the Argand burner—and were at times very generally used for gas lighting.

Fig. 193.—Swing-bracket gas lamp with open-flame burner.

The common gas jet is illustrated in Fig. 193. The figure shows a bracket fixture which is generally fastened to a pipe in the wall. A swing-joint at A permits the flame F to be moved into different positions. The annular opening A permits the gas to pass to the jet in any position to which the light is moved. The gas-cock C is a cone-shaped plug, which has been ground to perfectly fit its socket. It should move with perfect freedom, and yet prevent the escape of the gas. A slotted screw N permits the joint to be readjusted, should the plug become loose in the socket.

The gas-tips T are made of a number of different kinds of materials and are commonly termed lava-tips but tips for gas and gasoline are frequently made of metal. The bottom of the tip is cone-shaped, which permits it to be forced into place in the end of the tube with a pair of pliers. In size the tips are graded by the amount of gas which they will allow to escape in cubic feet per hour. For example—a 4-foot tip will use approximately 4 cubic feet of gas per hour. They are made in a number of sizes to suit the varying requirements.

The Inverted-mantle Gasoline Lamp.

—The inverted-mantle gasoline-gas lamp shown in Fig. 194, furnishes a good example of mechanism and principle of operation, when used with the hollow-wire system. This is the bracket style of lamp but the same mechanism is used in other forms of fixtures. Lamps of similar construction are suspended from the ceiling, either singly or in clusters; they are also used in portable form.

Fig. 194.—Sectional view of hollow-wire mantle gasoline lamp.

In Fig. 194 the lamp consists of a bracket H, which is secured to the wall and through the stem of which the gasoline is conducted to the generator by the pipe W. The arrows show the course of the gasoline and its vapor as it passes through the lamp. On entering the generator the gasoline first passes, the percolation, through an asbestos wick B, the object of which is to prevent the vapor pressure from acting directly on the gasoline in the supply tube. The gasoline passes through the wick B, largely by capillary action, as it must enter the generator against a pressure greater than that afforded by the pressure tank. The vaporization of the gasoline takes place in the tube above the mantle T, from the flame of which it receives the necessary heat.

In lighting the lamp an asbestos torch saturated with alcohol is ignited and hung on the frame, so that the flame may heat the generating casting N. This process usually requires less than a minute, generally about 40 or 50 seconds. The torch supplies heat sufficient to generate the vapor for lighting the lamp, but as soon as lighted the heat from the glowing mantle keeps the generator at the required temperature for continuous supply of vapor.

When the generator is sufficiently heated by the generating torch, the needle valve N is opened by pulling the chain P. This allows the gasoline vapor from the generating tube to escape at G into the induction tube R. As the vapor enters the induction tube at a high velocity, it carries with it the atmospheric air in quantity sufficient to render it completely combustible. The opening G and the tube together form a Bunsen burner. The lamp is so proportioned as to give a mixture of gasoline vapor and air that will produce complete combustion in the mantle T. The portion of the burner Z, through which the gas enters the mantle, is a brass tip, filled with a fluted strip of German silver, so arranged that the gas on entering the mantle will be uniformly distributed and that the heat generated will render the entire mantle uniformly brilliant.

One feature of the lamp that requires special attention is the opening G, through which the vapor from the generator is discharged into the induction tube. This is a very small opening and occasionally becomes stopped or partly closed. When this occurs the lamp fails to receive the necessary amount of gas, and the light is unsatisfactory. In this lamp, the cleaning needle Q is provided for removing the stoppage. The needle is simply screwed into the opening and forces out the obstruction; when it is withdrawn, the opening is left free. A more convenient device for accomplishing the same purpose is described in the portable lamp, Figs. 195 and 196.

Portable Gasoline Lamps.

—The portable form of desk and reading lamps for the use of gasoline is made in a great variety of styles. They are sometimes constructed to feed by gravity, but by far the greater number are operated by the pressure method. The portable lamp must be a complete gas plant, with storage tank for the gasoline, pipe system for conducting the gasoline to the lamp, generator and burner. To give satisfactory results, the lamp must be capable of being lighted with the least degree of trouble and operated with the least amount of care. The immense number of lamps of this kind that are sold shows that they meet all of these requirements and have proven satisfactory in operation. Their greatest attractiveness is their capability of giving a very large amount of light at relatively low cost.

Fig. 195 illustrates a portable gasoline lamp in which a convenient and efficient form of generating mechanism is combined with an attractively proportioned exterior. The lamp works on the principle of the hollow-wire system, the base serving as a storage and pressure tank, the frame of the lamp acting as the tube for supplying the lamp with gasoline, and the canopy containing the generating mechanism.

Fig. 195.—Portable gasoline mantle lamp.

The tank in the base is filled with gasoline at the opening E, which is made air-tight by a screw-plug. The plug also contains an attachment piece for the air pump, which furnishes the pressure to the gasoline. The hollow standard reaches to the bottom of the tank and through it the gasoline is forced to the point marked A, where the gasoline enters the generating mechanism. This part of the lamp, which is entirely concealed by the lamp canopy, is shown in detail in Fig. 196. The reference letters in Fig. 195 apply to the same parts in the detail drawing.

The gasoline enters an asbestos-packed tube F at the point A, and after percolating through the tube, reaches the regulating valve at the point G. The hand-wheel B opens and closes the valve, and thus controls the entrance of the gasoline to the generating tube H, where it is converted into the vapor. The vapor now needs only the addition of air to make it the desired gas for illuminating the mantle.

The vapor from the generating tube escapes at the small hole K, located directly under the mixing chamber M. The supply of air is received through the tube C, provided with a regulator, which is readily accessible from the outside of the lamp. The mixture of gasoline vapor and air is accomplished as in the other lamps described, through the Bunsen tube N. In this case, the Bunsen tube is extended and increased in size to produce a mixing chamber of considerable volume. The mantle is attached to the tip O. The tip, like the one already described, is made of German silver and constructed to produce a flame that will entirely fill the mantle.

This lamp is provided with a special means of keeping the opening K free from accumulations. The opening K, through which the gasoline vapor escapes from the generator, is very small and a slight stoppage will materially interfere with the flow of the vapor and thus impair the illuminating effect of the light. A lever D operates an eccentric which engages the piece P, to which is attached a pin that readily enters an opening K, when the lever is turned. Any accumulation which may lodge in the opening is instantly removed and the needle returned to its place by a turn of the lever D.

Fig. 196.—Sectional view of the generator for the American hollow-wire gasoline lamp.

Central-generator Plants.

—The central-generator or tube system of lighting with gasoline, differs from the other methods described, in the manner of generating and distributing the supply of gas to the lamps. In the hollow-wire system each lamp generates its own gas supply. With the central-generator system the gas for all of the lamps is generated and properly mixed with air in a central generator, and the finished gas distributed through tubes to the different burners and there burned in incandescent mantles. The gas as it leaves the generator requires no further mixing with air and therefore the burners are not of the Bunsen type.

Central-generator gas machines are made in a number of different forms by different manufacturers, all of which are intended to perform the same work but differ in the mechanism employed. The machines are simple in construction and as in the hollow-wire system are capable of using lower grades of gasoline than can be used with the cold-process plants. The gas from a central generator may be used for all purposes for which gasoline gas is employed, either for lighting or heating. One difficulty in the use of the machine is the lack of flexibility when required for only a few lamps or varying number of lights. Although these plants are sometimes used for lighting and heating dwellings, their use is limited, for the reason that variation of the number of lights requires the generator to be regulated to suit the change in the gas supply. The plants cannot be conveniently cut down to one light. Their most general use is that of lighting churches, stores, halls, auditoriums, etc., where a variable amount of light is not demanded. Plants of this character are quite generally used for street lighting and for other outside illumination.

An efficient and simple plant of the central-generator type is shown in Fig. 197. The supply of gasoline is stored in a tank similar to that used with the hollow-wire system and placed in any convenient location. The gasoline is conducted to the generator G, through a hollow wire marked W. The generator is inclosed in a sheet-iron box, which is located at any convenient place in the building. From the generator the gas is conducted through the tube to the lamps L.

In Fig. 198 is shown a diagram of the generator, cut through the middle lengthwise, in which all of the working parts are shown in their relative positions. The reference figures designate the same parts of the generator in Figs. 197 and 198.

In the process of generation the tank is filled with gasoline and pressure applied with the air pump. The tanks described in Fig. 189 might be used to advantage with this plant but the one shown in Fig. 197 is so constructed that the larger tank is used for storage of gasoline. The gasoline is pumped directly into the smaller tank which alone is kept under pressure. The pump P is enclosed in the large tank; at any time it is desired to replenish the supply of gasoline, it is only necessary to open the valve V and pump the necessary supply into the small tank. This transfer may be done at any time without danger from escaping gasoline vapor.

Fig. 197.—Diagram of central-generator tube system of gasoline lighting.

The process of generating the gas is best understood by reference to Fig. 198, which shows the internal construction of the generator. The liquid gasoline is admitted at the bottom through the small pipe W, and then enters the space 4, where it is vaporized. The initial flow of gas is generated by heating the generator with an alcohol flame from the iron cup 1, which surrounds the generator. When the generator is heated the gasoline admitted to the generator is immediately vaporized; when, by turning the handle 6, the needle valve 5 opens a small orifice through which the heated gasoline vapor escapes into the tube 7, above.

The blast of vapor issuing from the orifice carries with it air of sufficient volume to render the gasoline vapor an explosive mixture that when burned in the mantle will be reduced to CO₂ gas.

When the initial heating by the alcohol flame is exhausted, sufficient gas has been generated so that part of it may be used as a sub-flame in the gas burner 9, to keep the generator heated. The gas is conducted to the burner from the main tube 11, through the pipe 12-14, as indicated by the arrows. The burner 9 surrounds the generator and the size of the flame is regulated by the valve 15, which is opened an amount sufficient to admit the necessary gas to the burner.

To start the generator, the cup 1 is filled with alcohol and ignited. The needle valve 2 is now opened by turning the hand-wheel 3, admitting gasoline into the generator chamber 4, where the vaporization of the gasoline takes place. The flame from the burning alcohol will heat the generator in about a minute. When the generator is hot, the needle valve 5 is opened slightly, by turning the lever 6, and the gasoline vapor under high pressure blows into the tube 7. As the gasoline vapor is blown into the tube 7, air is drawn in through the opening 8, as indicated by the arrows. The generator is practically a large Bunsen tube from which the mixture of gasoline vapor and air is conducted to the burners by a connecting pipe.

Fig. 198.—Cross-section of the generator for the tube system of gasoline lighting.

Gas machines operated on this principle are made to accommodate a definite number of lamps. After the lamps are lighted, the amount of gas is regulated to suit the number in use. If at any time it is desired to reduce the number of lamps in operation, the gas supply must be regulated to suit the lights left burning.

As an illustration, suppose that a plant of ten lamps had been burning and that it was desired to reduce the number to six; four of the lamps are extinguished by turning the levers C, which control the gas-cocks. The generator which had been supplying sufficient gas for ten lights will continue to produce the same amount until the lever 6 is turned to reduce the supply of gasoline to the required amount for six lamps. This is done by gradually closing the valve 5 until the lamps again burn brightly.

In small plants the least number of lamps that will work satisfactorily at one time is three. Automatic regulators are made for plants of considerable size but do not satisfactorily control the gas when the lamps are reduced below three in number. The gas from these plants may readily be used in kitchen ranges, water heaters and other domestic purposes. Individual plants for operating ranges in restaurants and hotels are in common use. The plants are subject to minor derangements that require correcting as they occur, but as soon as the mechanism and characteristic properties of the plant are known, the correction of any difficulty that may present itself is easily accomplished.

Fig. 199.—Gas lamp for use with the central-generator or tube system of gasoline lighting.

Central-generator Gas Lamps.

—Fig. 199 shows the general construction and arrangement of the parts of the inverted-mantle lamp used with the central-generator system. In outward appearance the lamp is much like any other inverted-mantle gas lamp, but in arrangement of parts it is markedly different. The gas-cock C is larger than that used with the ordinary fixture, because the opening O must carry a larger volume of gas than that for supplying gas to lamps using the Bunsen tube. In the use of lamps with the Bunsen tube, the gas from the mains is mixed with approximately twenty times its volume of air; with a lamp like that of Fig. 199, where the mixture has already been made in the generator, the conducting tubes and the gas-cock must be relatively very large.

The screen S, which corresponds to the screen S in Fig. 192, is quite as necessary as in the other lamp. It not only assures a uniform distribution of the gas in the tube but it prevents the mantle from being broken when the burner is lighted. If this screen is punctured, the explosion which takes place when the burner is lighted will be sufficient to blow out the bottom of the mantle. The burner tip T is practically the same as that used with other mantle lamps.

Boulevard Lamps.

—Gasoline lamps for outside illumination may be constructed to operate with any of the systems described, but the hollow-wire and the generator systems are most conveniently used, because each post may be arranged as an independent plant. For illuminating private grounds or public thoroughfares, lamps such as are illustrated in Figs. 200 and 201 are very generally used.

The lamp shown in Fig. 200 is of the central generator type in which the storage tank and generator mechanism are located in the base of the post. These lamps are also sometimes constructed with a time attachment in the base of the post, arranged with a clock mechanism so that the light may be automatically extinguished at any desired time.

Fig. 200.—Boulevard lamp with generator in the base of the lamp post.

Fig. 201.—Boulevard lamp operated by the hollow-wire method of lighting.

In Fig. 201 the lamp is of the hollow-wire type and as in the case of the other, the supply tank is in the base of the post. With this system it would be possible to supply several lamps from a common supply tank, provided the hollow wire was protected against damage. The lamps arranged to work on either system, require the same amount of attention and are subject to the same derangements as those for inside service.

Burners for gasoline stoves

are made in a great variety of forms, each having some special points of excellence that are used to recommend the sale of the stove. The most essential feature of a gasoline stove is the burner, since on its successful performance will depend the satisfaction given by the stove. Many self-generating burners have been devised which have met with a great deal of favor, but the type of burner most widely used and the first to be devised for the purpose is the generating burner similar in principle to the generating gasoline lamp.

The burner is first heated from an outside source, in order to generate sufficient gas to start the flame, after which the heat from the burner will develop the gas supply. With gasoline stoves of this kind, the supply tank is elevated, in order that the force of gravity may give sufficient pressure to send the gasoline into the generator while the flame is burning. In the hollow-wire system the same type of burner is used, but the gasoline is forced into the burner by the pressure in the tank.

Fig. 202.—Sectional view of the generator and burner of a gasoline stove.

In Fig. 202 is shown a sectional view of the burner as it appears in the stove. The supply tank, or hollow wire from the pressure tank, sends the gasoline into the tube A at the bottom of the stove, to which several burners may be attached. The tube B, through which the gasoline percolates on its way to the generator, is filled with moderately coarse sand, or other material that is intended to prevent the gasoline from being forced out of the pipe by the pressure that is developed in the generator. The pieces C-C are perforated metal plugs that prevent the escape of the particles of which B is composed.

The generator is a brass casting D-D which is firmly screwed to the top of the tube B. A needle-valve E governs the discharge of the gasoline vapor at G, where the vapor enters the tube H, as indicated at K-K. The gasoline vapor enters the open Bunsen tube H, and with it is carried the air necessary to produce the required gas for complete combustion. The piece N is the generating cup in which is burned the generating fluid—either gasoline or alcohol. The gasoline from the pipe A percolates through the material in B and flows into the generator. The needle-valve being closed, the space D-D fills with gasoline.

To light the burner, the hand-wheel J is turned, opening the needle-valve a sufficient length of time to allow the gasoline to fill the cup N with fuel for generating the initial volume of vapor. A still better way is to fill the cup with alcohol, because the burning alcohol does not fill the air with smoke and odors, as in the case of gasoline, when used for generating purposes. The generating material having been ignited and burned out, the generator is hot and filled with vapor. The heated generator vaporizes a portion of the contained gasoline and forms sufficient pressure to force the remaining gasoline back through B into the supply tank. The material of the tube B permits only a slow movement of the gasoline and prevents the possibility of surging in the generator.

The initial supply of vapor being generated, the needle-valve may be opened and the gas lighted above the burner I-I, where it should burn in little jets at each opening with the characteristic Bunsen flame. It sometimes happens that the generator is not heated sufficiently, by the generating flame, to vaporize the necessary gasoline for starting the burner; in this case liquid gasoline will be forced from the opening G, and the burner will flare up intermittently in a red smoky flame. When this occurs the burners must be regenerated.

Gasoline Sad Irons.

—The use of gaseous or liquid fuel is always attended by an element of danger, because of the possibility of accidental explosion. The use of gasoline, the most highly volatile of all liquid fuels, has, however, come to be very generally used as a source of heat for domestic purposes. The danger of accident in the use of gasoline as a fuel for heating sad irons is largely due to ignorance of the involved mechanism or carelessness in manipulation. A knowledge of the principle included in their operation, together with an observance of the possible cause of accident, will reduce the element of danger to a negligible quantity.

The use of gasoline sad irons has come into favor because of their convenience and economy in operation. These irons, in common with the use of gasoline in its other applications of heating and lighting, are made in a great many forms but the principle of operation is confined to two types.

Fig. 203.—Gasoline flat-iron operated by a heated fuel tank.

Fig. 204.—Gasoline flat-iron showing the position of the cover while initial charge of gas is being generated.

First, those in which the gasoline is forced into the generator by the vapor pressure, from the heated supply tank; and second those in which the pressure is caused by pumping air into the supply tank after the manner of the hollow-wire system of lighting.

The first type of iron is illustrated in Fig. 203. The same iron is shown in Fig. 204, with the top in position for generating vapor pressure necessary to start the burner. The body of the iron A is a hollow casting, designed to receive the generator and burner in such position that the bottom portion of the iron may be uniformly heated. The generator and burner are shown in detail in Fig. 205, in which a sectional view is given of the parts, cut across lengthwise of the iron.

In starting the burner for use, the tank is first filled—not quite full—of strained gasoline. The precaution of straining the gasoline should be taken, to prevent putting into the tank anything that will possibly choke the needle-valve. Alcohol is used for generating the vapor supply, because the flame does not black the iron and fill the room with smoke as in the case when gasoline is used for the purpose. When the alcohol is ignited, the cover is placed in position as shown in Fig. 204, so that the flame may heat not only the generator but also the tank. The object of heating the tank is that the heated gasoline may furnish pressure with which to force the gasoline into the generator. When the alcohol used for generating is almost burned out, the valve F is slightly opened and the burner lighted.

Fig. 205.—Sectional view of gasoline flat-iron generator and burner.

As shown in Fig. 205, the generator G is a brass tube, inclosing the valve-stem G, which terminates in the needle-valve V. This valve regulates the supply of gas admitted to the burner and is operated by the hand-wheel F. When the gasoline in the tank has been heated the necessary amount, the vapor in G is allowed to escape through the valve V. The vapor is discharged into the Bunsen tube, and with it the air is carried in through the openings E, from both sides of the iron. The burner is a brass tube, slotted as shown at H, through which the gas escapes, forming a short flame of large area close to the part of the iron to be heated. The size of the flame is regulated by the hand-wheel F.

The tank is entirely closed, the plug P being provided with a lead washer to insure a tight joint. The plug is further provided with a soft metal center which acts as a “safety-plug” in case of overheating. Should the iron at any time become too hot, the soft metal center will melt and the released pressure in the tank will put out the burner flame. The soft metal center may be renewed with a drop of solder. In case the safety-plug at any time is melted, the hot gasoline will spurt from the opening and immediately vaporize. This of course would, in a short time, produce an explosive atmosphere which if ignited would be dangerous. In case of accident the iron should be carried to the open air and the flame smothered with a cloth.

Alcohol Sad Irons.

—Irons of the same style are also made in which alcohol is used as a fuel. The alcohol irons differ in construction from those using gasoline only in the amount of air that is mixed with the vapor. In general appearance the two styles look very much alike, but in the alcohol iron one of the intakes E is entirely closed and the other opening is partially closed.

Fig. 206.—Gasoline flat-iron operated by an air-pressure fuel tank.

The operation of these irons is identical to those using gasoline, but they are preferred by those who fear the use of that fuel. In reality there is little difference in the danger attending the use of the two liquids. It is only fair to say, however, that the use of any highly volatile fuel is attended with some danger when used carelessly, but with a reasonable amount of care and a knowledge of the mechanism of the machine in use the danger is of minor consequence.

In Fig. 206 is illustrated another style of gasoline sad iron, the working principle of which is the same as those already described but the supply tank is not heated to give pressure to the gasoline in the tank. In this iron the tank is located at one side of the iron and pressure is applied with an air pump as in the hollow-wire system of lighting. The burner is generated after the manner of the others and operated in exactly the same manner. The chief difference is that the possibility of excessive pressure through overheating is eliminated.

Alcohol Table Stoves.

—In the United States the use of alcohol as a fuel has never been extensively employed because of the duty imposed on its manufacture by the Federal Government. In 1896 this duty was removed from denatured alcohol and the cost was sufficiently reduced to permit a great extension in its use as a fuel.

Fig. 207.—Alcohol vapor stove.

Denatured alcohol is any alcohol to which has been added any of the list of prescribed volatile fluids that will render the alcohol unfit for use in beverages and not materially change its heating value. Denatured alcohol is sold at a price that will permit its use in small flat-irons, table stoves and other forms of burners where small amounts of heat are generated for convenience. At the price of denatured alcohol as generally sold, it cannot compete with gasoline and kerosene as a fuel.

In Fig. 207 is shown a convenient and inexpensive form of table stove, in which the vapor of alcohol is burned in practically the same manner as the vapor of gasoline in the burners already described. The supply of alcohol is stored in a tank A, and fed by gravity to the burner B, the flame from which resembles that of the ordinary gasoline burner.

The generator G with the other essential parts are shown in detail in Fig. 208. The reference letters indicate the same parts in the detail drawing as in Fig. 207.

Fig. 208.—Sectional view of the generator and burner of the alcohol vapor stove.

The alcohol flows from the supply tank through the pipe C to the generator G, which is a brass tube filled with copper wires. The vapor for starting the burner is generated by opening the valve V and allowing a small amount of alcohol to flow through the orifice C into the pan P directly below the generator. The valve is then closed and the alcohol ignited. When the generating flame has burned out, the valve V is again opened and the vapor which has generated in the tube escapes at the orifice C and enters the Bunsen tube T, (Fig. 207) carrying with it the proper amount of air to produce the Bunsen flame at each of the holes of the burner.

As in the case of the gasoline burners the orifice C sometimes becomes clogged and it is necessary to insert a small wire to clear the opening. With the stove is provided a tool for this purpose. With stoves of this kind, the supply tank must not be tightly closed, because any pressure in the tank would cause it to become dangerous. The alcohol is fed to the generator entirely by gravity. The stopper of the tank contains a small hole at the top which should be kept open to avoid the generation of pressure should the tank become accidentally heated.

Stoves of this kind may be conveniently used for a great variety of household purposes, and when intelligently handled are relatively free from danger.

Danger from Gaseous and Liquid Fuels.

—All combustible gases or vapors, when mixed within definite amounts, are explosive. The violence of the explosion will be in proportion to the volumes of the gas and the condition of confinement.

When gasoline or other volatile fuel is vaporized in a closed room, there is danger of an explosion, should the mixture of the vapor and air reach explosive proportions. It is dangerous to enter a room with a lighted match or open-flame lamp, where gaseous odor is markedly noticeable. In case of danger of this kind the windows and doors should be immediately opened to produce the most rapid ventilation.

In the act of igniting the flame in a gas or vapor stove, the lighter should be made ready before the gas is turned on. Explosions in gas and vapor stoves are usually due to carelessness in igniting the fuel. It should be kept constantly in mind that, if a combustible gas is allowed to escape and mix with air in any space and then ignited, an explosion of more or less violence is sure to occur.

Gasoline and kerosene are lighter than water and will float on its surface. The flames from these oils are aggravated when water is used in attempting to extinguish them. The burning oil floating on the surface of the water increases the burning surface.

Burning oil must be either removed to a place where danger will not result or the flames must be smothered. In case of a small blaze, the fire may be extinguished with a cloth, preferably of wool, or if circumstances will permit, with ashes sand or earth.

Alcohol dissolves in water and may, therefore, be diluted to a point where it will no longer burn.