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of water impairs their measuring power, which may also the passage of the necessary quantity of gas to balance the holda. be affected by the meter being lifted off the level.' The On the other hand, if the pressure at the inlet falls below that freezing of the water also frequently occasions trouble, and required to lift the holder, the full opening of the regulating plate

allows all the gas there is to pass through the governor to the the action of the water on the gas passing through it by burners. Where a very perfect controi is desirable, the parts of dissolving out part of the valuable illuminating hydrocar- the governor are made in duplicate, and a double control is thus bons on the one hand, and diffusing watery vapour through Brace Peebles governor (fig. 18) is the same. - The

gas enters at 1,

established. With certain structural differences the action of the it on the other, doubly affects its illuminating

power. The dry meter is free from the defects just mentioned, but does not pass the gas with such steudiness as the wet meter. The ordinary dry meter consists of an oblong box enclosing two measuring cylinders, with leather sides which contract and expand as they are being emptied and filled, on the principle of ordinary bellows. The pressure of the gas entering this meter is sufficient to keep it in operation, and by a system of valves the one cylinder is in process of filling as the other is being emptied through the service pipe. The chambers communicate by means of lever arms with a crank which turns a train of wheels in connexion

Fig. 18.-Consumers' Governor (Poebles). with the indicator dials on the face of the machine. Consumers' Governor.-In order to consume gas in a

and passes ont at 2 into the pipe leading to the burners. To adjust

the governor the brass cap 8 is unscrewed, and the weights 4 taken perfectly uniform and economical manner, it is essential off or put on until the desired pressure, of say, B-tenths, at the that the pressure at the barners should be always in-burners is obtained, when the brass cap is again screwed to its variably the same. That pressure is liable, however, to place. The weights now keep the valve 8 variation from a number of causes, such as Auctuation in open so long as 5-tenths pressure is not ex.

ceeded in the main ; but any variations in the number of lights in use, either in the house or in the the main above that pressure act at once on neighbourhood, or the application or withdrawal of pressure the diaphragm 6, and partly close or opon at the works' governor. And as all good burners are fitted the valve, thus maintaining under all cirwith regard to a fixed standard quality and pressure of gas

cumstances a steady outlet pressure.

Of volumetric governors the best known is to be consumed, if this is not maintained the conditions Girond's glycerin rheometer, which consists of maximum illuminating power are lost. A consumers' of a closed cylindrical casing containing a governor secures uniformity of pressure at all the burners very light metal dome or bait dipping into

& circular channel filled with glycerin. In supplied by the pipe on which it is placed. The prin the upper part of the dome is a small orifice ciple of the governor is identical with that of the station through which the gas passes, and on its top governor already described, increased pressure in both is fixed a conical valve which works in a seat cases causing the orifice through which the gas escapes to at the top of the casing. As the pressure be contracted. The mechanical arrangements by which from the supply side rises or falls, the bell

responsively moves up or down, opening or this contraction of orifice is effected are various.


closing by the conical valve the orifice by some instances they are in direct contact with the separate which the gas passes outward ; and so deliburners, while other governors are applied to the supply cately is this compensation adjusted that the pipes of a whole establishment. They are separable into pas passed is the same in amount however

different the pressure,

Bruce Peebles has pressure governors, which, like the station governors, give a invented a simple and inexpensive form of constant or uniform pressure under all variations of con- volumetric governor (fig. 19), in which the sumption, and volumetric governors which pass a constant use of glycerin is dispensed with. It consists

of a conical dome resting on a needle-pointed volume or amount of gas ander ell variations of pressure.

stud, the cone having an orifice at C, and of pressure governors the forms devised by Sugg, and Bruco there is besides a variable consumption Peebles are in extensive use, the latter especially

being much channel at the side A B A, which can be Fig. 19.- Volumetric applied to street lampe. In Sugg's consumers' governor (tig, 17) controlled by the external screw. . As soon Governor (Peebles).

as the stopcock is opened the gas fills the interior of the cone, and momentarily closes the valve; but, finding its way by the vertical passage, or through the hole C, in the cono, it reaches the chamber above the cone. The cone is therefore now surrounded by gas at the same pressure, and, having nothing to support it, falls, and lets gas pass to the burner. But this only takes place to an extent that allows a differential pressure to be established sufficient to support the cone, which is then equilibriated between two pressures ; and the difference between these two pressures remains constant, however much the initial pressure of the gas may vary, unless, of course, it gets so low as not to be able to raise the cone,

Burners.—The question of the arrangements by which the maximum illoiminating power may be developed in

the consumption of gas, being one which principally affects FIG. 17.-Sugg's Consumers' Governor.

individual consumers, has not received the attention which the gas enters at the inlet, and, following the course indicated by their importance merits. As a rule, gas-fitters are ignorant the arrows, passes through the regulating plate of the governor into of the principles involved in the economical use of gas, the gas-holder, and thence, by the opening provided for it

, it and are often prejudiced by the assertions of certain reaches the ontlet. The gas-holder has suspended from a disc in the crown a half-ball valve, which closes or opens the opening in inventors; and thus it happens that, owing to defective the regulating plate & the gas-holder rises or falls. A weight placed fittings, unregulated pressure, and imperfect burners, an on the top of the holder fixes the pressure required to raise it

. As enormous loss of illuminating power is suffered. In their & consequence, if the pressure of the gas on the inlet is greater than that required to lift the holder, then the latter rises, carrying the report to the Board of Trade in 1869, the referees under

the half-ball valve with it, till such time as the

opening left between City of London Gas Act state, of a large number of burners the sides of the valve of the regulating plate is sufficient to allow examined by them, that

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“The diversity as to illuminating power was surprisingly great, | adopted in the United States, in Canada, and in various and such as will appear incredible to any one who has not ascer. European states. At the time it was made, the Sugg No. tained the facts by careful experiment. They also found the kinds of burners in common use are extremely defective, thereby en tailing 1 was esteemed the best known barner, but since that time upon the public a heavy pecuniary loss, as well as other dis. Mr Sugg has perfected his London Argand, whereby with advantages. In order to examine this important matter more fully, London gas results equal to about 2 candles better then the referees, with the ready permission of the proprietors, inspected the standard are obtained. several large establishments in the city, where, owing to the preval.

Fig. 20 is a sectional view of ence of night work, an unusually large amount of gas was consumed. Sugg's London Argand with the latest improvements. The inspection in every case confirmed the apprehensions which the At the point at which the gas enters is a brass nose-piece A, referees had formed from their examination of the burners which screwed to fit the usual three-eighth thread, intended by the maaithey had procured from the leading gas-fitting establishments. In faeturers of all kinds of gas the offices of two of the leading daily newspapers (establishments fittings to receive the burner. which consume more gas than any other), they found that the This is drilled through its burners principally in use gave only 55 per cent. of light compared length, and slightly trumpeted with the Sugg-Letheby burner, or with Leoni's Albert Crutch at the top so as to fit the coneburner, and yet the price of the last-named burner is alınost identical shaped piece of metal projecting with that of the very bad burners employed in these offices. Tested from the roof of the inlet chamby the Bengel burner, or by Sugg's new burner, the amount of ber B. The outside of the upper light given by these imperfect burners is only between 47 and 49 portion of the nose-piece A is per cent. of what is obtainable from the gas.'

serewed to fit the inside of the In a communication to the Philosophical Society of Glasgow inlet chamber B, and thus, by in 1874 Dr Wallace, the official gas examiner of that city, an adjustment of this screw by dealing with the rich cannel gas of a minimum illuminating the shoulder at AB, it is possible

means of paper washers put on power of 25 candles there supplied, estimated that there is to enlarge or decrease the area of in ordinary consumption a loss of 40 per cent. of illuminat- the passage through which the ing power which, under favourable circumstances, might gas has to pass in order to capply be obtained, and thpt in practice, while not more than 16. D, only are shown in the draw

three tubes (two of which, Cand candle power is procured, from 20 to 23-candle illumination ing), by which it is further conought to be readily obtainable.

ducted to the combustion chamThis viniversal wasteful misuse of gas is not merely a ber E... This chamber is made question of economy, although the aggregate pecuniary capable of resisting the corroding

of steatite, a material which is loss must be very great. It affects in no small degree the action of heat or damp, and is a health and comfort of the consumers of gas; the products good non-conductor of heat. It AB of combustion of the purest gas vitiate the atmosphere, is pierced with a number of holes, and overheat the apartments in which it is burned. So arranged as regards size and Fig. 20.-Sugg's London Argan

number that Moreover, the light from gas properly burned is much gas the burner is required to

Burner. steadier and purer, and less trying to the eyesight, than consume shall pass out at an inappreciable or the least possible that wastefully consumed.

pressure. This is in order that the oxygen of the atmosphere, The principal circumstances which demand attention in formed by the edge of the air cane

G, and the outside of the com,

slowly, ascending through the centre opening F, the annulus the fitting of burners are the average pressure and illumia- | bustion chamber E, shall combine with the burning gas by natural ating power of the gas to be consumed. How pressure affinity only, leaving the nitrogen to pass freely out at the top of may be controlled has already been shown in connexion with the flame. H is one of the three springs which are intended to governors. The quality or illuminating power of gas has keep the chimney giaas eteady

in its place. JJ are two of three

stubs or rests for a screen, globe, or moon; and K is a peg to à most important hearing on the nature of burners proper steady the current of air which passes up the centre opening F. for use, so that a clear distinction must be drawn between

With the view of competing in illuminating power with common coal-gas and cannel-gas, the burners for the one

the electric light, Mr Sugg has recently devised a modified kind being quite unsuited for the other variety. The

form of Argand burner calculated to yield a large illuminatmaximum amount of light is obtained from any gas just at that point where the flame is on the verge of smoking, and ing power by, increased

but still economical consumption of

gas. These burners are made of two or more concentric the conditions under which 14-candle gas would be per: Argand rings, the outer being of large diameter, and in fectly consumed would, with 26 or 30-candle gas, produce operation they give out a large solid, white

, steady flame. a large amount of smoke. Indeed, the richer gas is, the

With London gas, a two-ring burner consuming 19 feet greater is the difficulty in developing its fall illuminating per hour yields 80-candle light; 3-ring burners which all times


consume 23 feet give 100 candles; 4-ring burners fed sheet or stream than is proper in the case of poor gas,

with 45 feet of gas gave an illumination equal to 200 which requires legs access of air for its complete lumini

candles. ferous combustion. The opening or slit in burners used for common gas is therefore much larger than in those devoted burners, a self-acting governor is frequently fitted to them.

As regular pressure is essential for the proper use of these to the consumption of cannel-gas.

There are two principal kinds of burners in use—Argand London gas is about •7 inch. In a series of experiments

pressure at which the best results are obtained with
and flat-flame burners. The Argand burner in its usual form
is useful only for common or low
illuminating power gas, and Newcastle-on-Tyne the following results were obtained:-

with Argand_burners made by Mr John Pattinson of it has, in the hands of various inventors, especially by Mr William Sugg of London, been so improved that for amount


Illuminating and steadiness of light it leaves little further improvement to be hoped for. The common Argand consists of an annular tube with a circle of small holes pierced in the end of the

Sugg-Letheby Standard 5.9 14.10

14.10 ring. It thus produces a circular or tubular flame, which

Sugg's London Argand 5.0


15.90 requires to be protected with a glass chimney, by which the

Sugg's Improved Lon


16.08 don Argand

17.86 admission of air is regulated. The burner made by Sugg

Silber's Argand

17-80 17.80 in 1869, known as the Sugg-Letheby, or Sugg's No. 1, is

Common Argand

11.20 the standard burner adopted for the United Kingdom in



12-70 Acts of Parliament, and the same standard has been



Cubic feet per


power per 5

power in


cubic feet per


50 5.0



per hour.


per hour.



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Flat-iame burners, or burners which spread their flame the series of experiments by Mr Pattinson of Newcastle already in a broad thin sheet, are of two principal kinds known quoted. The experiments were made with 14·10-candle gas, from respectively as " fishtail” (fig. 21) and batwing”. (fig. Sugg's improved London Argand

which it must be remembered 1786-candle power was developed in 22) barners. The fishtail or union burner has two orifices drilled in its surface,

Cubic feet.niuminating power at 0 it.

Illuminating which are inclined towards each other at 10 42147 an angle of 90°, so

Fishtail, No. 3, steatite top


3.75 metal top

3.5 4.10 5.85 that the issuing cur

No4, steatite top..

5.20 5:31 rents impinge and

No. 5,

50 7.80 7.80 spread the flame in

Batwing, metal top...


9-26 a broad sheet. The

Fishtail, Bray's, No. 4... 40

6.02 6-28 No. 8.

5.0 11.80 1180 ges in the batwing

7.0 14.21 10:15 issues from a narrow

Batwing, Brönner's. No. 4 4.0 10.10 12.62 slit cut right across

50 11.60 11.60 the surface. In the Fros. 21, 22.- Flat-flame Burners.



8.40 10.50 best forms of all kinds of burners now in use steatite or

50 10.90 10.90 adamus (pottery) tops are employed. In Sugg's Christiania burner the slit is circular, and the light issues in two thin mon use which, consuming the same amount of gas, differ in light

From these experiments it appears that there are burners in com. sheets which coalesce in their upper luminiferous part, pro- giving effect from 3.75 to 12:62-candles, one giving more than three ducing a most beneficial result

when common gas is con- times as much light as the other; and if we take the best-Argand sumed. The common metal and steatite-tipped burners in burner into account, the range of variation is from 3-75 to 17-80,

or as one to five nearly. Another important deduction from these use permit the current of gas to strike against their orifices observations is that large-sized burners as a rule give much more without any control or regulation, but in the numerous illuminating power than the smaller sizes. Thus å burner passing patented forms of both fishtail and batwing jets certain 7 feet of gas per hour will almost invariably distribute more light mechanical obstructions, or small governors, are inserted, than two each burning 3-5 feet. which break or retard the current. Screws, wire gauze, Gas Testing.-The universally recognized and practised calico, cotton wool, iron filings, and constriction of the method of valuing gas is by comparing its light with that lower part of the burner are all devices in use. Of all these ytelded by a standard light, which can be obtained as nearly one of the simplest and most effective is the plan on which as possible of an unvarying intensity: In making such a the Brönner burner is constructed, which is simply to have | photometric comparison it is essential that the conditions the opening at the lower part of the burner smaller than under which the lights to be compared are burned shall be the upper orifice. For different qualities and pressures of uniform, and that the materials be consumed at a definite gas the Brönner burner presents a great variety of combina- rate. The standard recognized by legislative authority in tions by having several distinet sizes of lower constriction Great Britain and America is the burning of a sperm candle wbich can be adjusted to a large number of tip orifices. 6 to the fb. consuming at the rate of 120 grains of sperm Thus, with six distinct openings at each end, 36 combina- per hour, compared with gas burning at the rate of 5 cubic tions can be made. As Argand burners are not suited for feet per hour. The burner prescribed for common gas is measuring the illuminating power of rich cannel-gas, flat the Sugg-Lecheby-Argand, in Acts of Parliament defined as flame-burners have to be employed ; and in the Act of a 15-holed Argand with a 7-inch glass chimney; and for rich Parliament under which the Glasgow Corporation supplies cannel.gas a union or fishtail jet passing 5 feet per hour is gas, it is provided that “all the gas supplied by the corpora- employed. The apparatus employed for making the comtion shall be at least of such quality as to produce from a parison is generally the Bunsen photometer, or some modi. union jet burner, capable of consuming 5 cubic feet of gas fication of that instrument; and the ratio of comparative per hour under a pressure equal to a column of water ·5 of illumination is established by the well-known principle that an inch in height, a light equal in intensity to the light the intensity of light diminishes in inverse proportion to the produced by 25 sperm candles of 6 in the pound, burning square of the distance from its source. The Bunsen photo 120 grains per hour."

meter consists of a bar of wood 98 inches long, with a Dr Wallace, in a communication on the “ Economical Combus- candle holder at one end and at the other the standard gas tion of Coal-Gas" (Proc. Phil. Soc. Glasgow, vol. ix.), tabulates an burner. A balance for weighing the candle as it burns, an extensive series of experiments made with flat-flame burners of indexed meter for the gas, and a clock are also provided. various sizes with about 28-candle gas at different degrees of pressure. The bar is graduated from the centre to each end, and on The general result of these experiments shows that, to obtain the highest luministrous effect with burners of small aperture, a low it is set a sliding holder into which a screen of prepared pressure of gas (not more than ·5 inch) must

be maintained, although, paper is placed. The screen is so prepared that a spot or as the size of the jet increases within certain limits, the pressure disc is more opaque than the remainder of the paper, so that may be incrcased with favourable results. With 9 sizes of Bray's when light passes through it from one side, that particular regulator fishtail (a burner having an obstruction consisting of a double fold of cotton cloth) Dr Wallace obtained the following spot is seen distinctly darker than the rest. When, howa results, caleylated to 5 cubic feet per hour :

ever, equal amounts of light fall on it from both sides the

spot disappears, and the whole surface presents & uniform 8

appearance. Therefore, with both candle and gas burning At hinch pressure...

under the stipulated conditions in a darkened chamber, by At 11-inch

gas blows. moving the screen on the graduated bar from the one light

and towards the other till the dark spot on the paper disThe gas used in the f-inch experiments was 2772-candle standard, for the 1-inch series it was 29-05, and for the 14-inch appears, the comparative illuminating power of the light is set it was 28.61-candie. With 30 combinations of Brönner burners ascertained by the position of the screen on the graduated Dr Wallace obtained from 28-2-candle gas at 1 inch pressure an bar, or by a simple arithmetical calculation. Thus, the average of 25-7, and at 14-inch 25-8-candle power, most of the lights being 100 inches apart, if at the conclusion of the combinations giving fairly equal results.

Of all burners the ordinary fishtails, ana they are the most fre experiment the screen is 20 inches from the candle and 80 quently used, give the most inferior results when used for burning from the gas jet, since 802 is 16 times 20%, the gas is 16cote mon coal-gas. The results tabuiated below are derived from candle power..


0 1 2

5 6 7 145 174 20-023 25-0 26.15 27.0 2916 11 7 13 3 17.620 623-626-2 28 7 30-2 8-8 9.8 13.9 17.5 19-423-7 25.9

8 29-08 82-0

At 1-Inch

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Comparisons of the quality of gas are also made by the septic, is the basis of many valuable dyes; anthracene jet photometer, an apparatus which depends on the prin- forms the source of the now most important dye, artificial ciple that gas of uniform quality burned at invariable alizarin; and most of the substances have other applicapressure, through a small orifice, yields a flame of uniform tions of minor importance. height. If the fame is to be maintained at a uniform height The relative position and value of the various products the pressure in the pipes must increase as the quality of of the gas manufacture is exhibited by the following con the gas decreases. The jet photometer forms a ready and densed statement of the position and operations of the convenient means of ascertaining any variations in the various London gas companies during the year 1875 :quality of gas supply; but it is not available for purposes Total capital of the companies

£12,516,009 of comparison

Capital called up..

11,005,589 Analysis of gas does not yield so satisfactory evidence total gas rentál....


1,466,407 of its illuminating value as photometric comparisons, but Cost of coal....

492,927 varlous methods of ascertaining the proportion of lumini | Receipts for coke and breeze..

162,151 ferous olefines contained in any gas are occasionally prac

'for ammonia.

111,951 tised. The absorption of the heavy hydrocarbons by Gas produced ........

.14,888,133 thousand feet. chlorine or by bromine, and Dr Fyfe's durability test, are Gas sold

..13,622,639 of theoretical rather than practical importance.

Coal carbonized (4 per cent. cannel) 1,505,000 tons Residual Products.-Under this term are embraced coke, Coke used as fuel in retorts, 31 per cent., 440,685

Coke produced, 34 bushels per ton 1,417,654 chaldrons. ammoniacal liquor, and gas-tar, all of which are sources of Coke sold, 69.per cent.

976,989 income in the gas manufacture. Indeed the value of these Average yield of gas per ton of coal 9,892 cubic feet products has increased so rapidly of late years, and they now form the basis of manufactures of such consequence,

GAS FROM SOURCES OTHER THAN COAL. that the residual products can scarcely be regarded as of secondary importance, and they will certainly play no small Petroleum-Gas.-Petroleum being a substance obtained part in determining the future maintenance of gas-lighting in great abundance, notably in America, is used, not only in the face of other competing systems. The change in the directly as an illuminating agent, but also for the production valantion of ammonia and tar liquors is well illụstrated hy of gas; and as an enricher of common coal-gas it is applied the circumstance that, during the year 1878, the corporar at several works in New York and Brooklyn. Its preparation of Bradford was offered £10,000 per annum for these tion is effected by distilling it first at a low temperature products, which about eight years previously had been into a rich vapour, which, when passed into bighly heated disposed of for a yearly payment of £800.

retorts, is converted into permanent gas of an illuminating Coke is a substance which varios much in value, according power about five times greater than common gas; and which to local circumstances, and the nature of the coal.distilled. | is, moreover, absolutely free from ammonia, sulphur comWhen shale is used, there remains in the retorts an ashy pounds, and carbonic acid. On account of its great richresidue which is absolutely worthless ; and the coke of ness, petroleum-gas must be consumed in special burners cannel coal is also comparatively of little value, owing to of very fine aperture, at a rate varying from 5 tn 2 feet per the amount of ash it yields. Indeed, in Scotch works hour. where ashy cannel alone is distilled, the retorts have to be Oil-Gas.- In the early stages of gas manufacture many partly fired with common coal The coke obtained from attempts were made to substitute' gas distilled from inferior ibe distillation of caking coal, on the other hand, is of oils for coal-gas. The oil was distilled by allowing it to high value, and after a supply is set aside for heating the percolate into highly heated retorts, in which a quantity of retorts there generally remains from 65 to 85 per cent. of coke or a like porous solid was placed, and the distillate the whole amount to be disposed of by sale.

was a richly luminiferous gas free from hurtful impurities. Ammoniacal liquor is more abundantly produced by the Although oil in this form yields a convenient and powerful distillation of cannel than by common coal, from 18 to 22 Do illuminant, its direct combustion is much more economical; of ammonia, as sulphate, being obtained from each ton and as all oils and fats are highly valuable for many of capnel distilled; as against about 16 to derived from purposes besides illumination, they cannot compete with ordinary coal. - Glas liquor is now almost the sole source gas coal as a source of gas. Nevertheless the New York of ammonia, which, among other purposes, is very largely Gas Light Company manufactured oil-gas exclusively from employed as an agricultural fertilizer

1824 till 1828, and sold their product at $10 per 1000 feet. Tar liquor yields by destructive distillation a wide range The dietillation of suint from wool washing, and of reof products possessing a great and increasing industrial covered spent soap, are examples of the application of valuş. The cannel coals, and other varieties rich in volatile oleaginous substances for gas-making. matter, are also the kinds which yield the largest propor Resin-Gas.—In its treatment and results resin, as a tion of tar. In the distillation of coal-tar, after some am. source of gas, is very similar to oil. It yields a pure gas moniacal and watery vapours have been given off, there is of great illuminating power, and for twenty years (1828-18) distilled over a proportion of highly volatile fluid hydro: it was supplied in New York at $7 per 1000 feet. Previous carbons which consist principally of benzol; and afterwards to the civil war of 1861-65 it was a good deal used on a large amount of a light oil, known as coal naphtha (also the European continent. a mixture of various hydrocarbons), is obtained. At this Wood-Gas. The original experiments of Lebon, it will point the residue in the retort is called artificial asphalt, be remembered, were made with wood-gas, but he failed to and as such is a commercial article; but if the heat is forced, obtain from his product an illuminating power that would and the distillation continued, a large amount of heavy" compare with that of coal-gas. Lebon's failure was in later or "dead oils” is obtained, and the mass left in the still is years shown to arise from distilliug at a temperature which hard pitch.” The heavy oils are a mixture of naphthalin, gave off chiefly carbonic acid with non-luminous carbonic phenol (carbolic acid), cresol (cresylic acid), and anthracene, oxide and light carburetted hydrogen, leaving in the retort &c. The berrzol obtained in the first stage of the distilla- å tar which the application of a higher heat would have tion is the basis of aniline and its various dyes ; næphtha resolved into highly luminiferous gases and vapours. is used as a solvent, and for lighting and other purposes ; Pettenkofer, who pointed out the fact, devised a system of carbolic acid, in addition to its employment as an anti-wood-gas making in which the products of the low-heat

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distillatiou were volatilized by passing through a range of the burner flame into the box, has recently been proposed, red-hot pipes; but now it is found that ordinary retorts, and is now being carried into effect with every prospect properly heated and fed with small charges, answer perfectly of great increase of illuminating power, and consequent well for the operation. Wood-gas, owing to its high specific economy, by the Albo-Carbon Light Company. gravity and the proportion of carbonic oxide it contains, The efforts to introduce carburetted water-gas have been must be burned at considerable pressure, in specially con numerous and persistent; and the sanguine statements structed burners with a large orifice. It is largely used in of the various inventors have led to the loss of much Germany, Switzerland, and Russia, where wood is more capital through experiments undertaken on a great scale easily obtained than coal. It was used at Philadelphia gas which have always resulted unfavourably. The whole of works in 1856, where it was affirmed to be cheaper and of the proposed processes depended on the decomposition of greater luminosity than coal-gas.

water by passing it over highly-heated surfaces in prePeat-Gas is evolved under circumstances the same as sence of glowing charcoal, whereby free hydrogen, carbonic occur in connexion with the wood-gas manufacture, but the oxide, and carbonic acid gases are produced, the carbonic amount of moisture contained in peat is a serious obstacle acid being eliminated by a subsequert process of purifito its successful use in this as in most other directions. cation. The combustible gas so obtained was in earlier Earnest and persistent efforts have been made to use peat experiments charged with luminiferous hydrocarbons by as a source of gas, but these have met but little commercial being passed into a retort in which coal, resin, or oil success. To a limited extent it is used in various German was being distilled, as in Selligue's and other processes; factories which happen to be situated in the immediate or, as in White's hydrocarbon process, both steam and coal neighbourhood of extensive peat deposits:

were treated together in a special form of retort. Since Carburetted Gas.—Under this head may be embraced all the introduction of American petroleum, however, most the methods for impregnating gaseous bodies with vapours methods of carburetting water-gas have been by impregnatof fluid or solid hydrocarbons. The objects aimed at in ing it with the vapour of gasolin, the highly volatile the carburetting processes are—(1) to increase the illuminat portion of petroleum which comes over first in its distillaing power of ordinary coal-gas ; (2) to render non-luminous tion for the preparation of “kerosene" lamp oil. Water-gas combustible gases, such as water-gas, luminiferous; and has been proposed, not only as an illuminating. agent, but (3) so to load non-combustible gases with hydrocarbon at least as much as a source of heat; but the heat expended vapour as to make the combination at once luminiferous and in the decomposition of water is much greater than can in a supporter of combustion. The plans which have been practice be given out by the resulting gases. proposed, and the patents which have been secured for Several of the processes introduced for rendering ordinary processes of carburetting, coming under one or other of atmospheric air at once combustible and luminiferous, by these heads, have been almost endless ; and while the saturating it with the vapour of gasolin, have been so satis greater part of them have failed to obtain commercial suc- factory that this air-gas is now largely used both in America cess, they are sufficient to indicate that there is still a pos- and Europe for lighting mansions, churches, factories, and sibility of doing much to increase the effect and cheapen small rural districts. The general principle of the airthe cost of production of gas. Further, although for ex- machines will be understood from the following description tensive use none of the gas-making plans can compete with of the “sun auto-pneumatic” apparatus (Hearson's patent), coal-gas manufacture, some of them are of much value for which is in extensive use throughout Great Britain. private establishments, country houses, factories, and similar Hearson's machine is cylindrical in form (fig. 23), and is places, where connexion with coal-gas works cannot be obtained.

The carburetting of common coal-gas with the vapour benzol obtained by the distillation of gas-tar was originally suggested by Lowe as early as 1832, and subsequently by the late Charles Mansfield, who showed that by passing gas over sponge saturated with benzol a very great addition was made to the illuminating power; and he introduced an apparatus by which common gas could thus be benzolized at a point very near the burner. The facts, however, that benzol is a highly inflammable liquid, that the benzolized gas varied in richness owing to the gas taking up much more benzol when the carburetter was newly charged than it did afterwards, and consequently that it often produced a smoky flame, and that sulphur compounds accumulated in the carburetter, as well as the trouble connected with charging the apparatus, all combined to prevent the extensive intro duction of the process. In later times the value of benzol for aniline manufacture and other purposes would have been a serious bar to its use. Mr Bowditch introduced the use of a heavier hydrocarbon-a mixture of naphthalin with cymol-which he called carbolin, and which possesses the advantage of giving off no inflammable vapour at ordinary temperatures, and is, moreover, a substance for which no

Fyg. 23.–Sun Auto-Pneumatic Apparatus. commercial demand exists. The carburetting appliance had surmounted by two turrets. Internally the cylinder is to be placed in immediate proximity to the burners, and divided into two compartments by a transverse portion, one either heated by them direct, or by a small subsidiary jet, being occupied by a rotary blower, an apparatus similar in as the vapour of naphthalin solidifies on a very small faŭ of construction to the drum of a water-meter, and the other temperature and chokes up pipes. Carburetting by means by an elevator or dipper wheel, the function of which is to of a solid block of naphthalin introduced into a gas-tight raise gasolin into the blower chamber, where the gasolin boz, and partly volatilized by a strip of copper passing from must be maintained at a constant level. The blower and

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