[11]Vegetab. Statics, vol. I.
[11]Vegetab. Statics, vol. I.
In the year 1767, the Bishop of Llandaff[12]examined the nature of the vapour and gazeous products evolved during the distillation of pit-coal. This learned philosopher noticed, thatthe volatile product is not only inflammable as it issues from the distillatory vessel, but that it also retained its inflammability after having been made to pass through water, and suffered to ascend through two high curved tubes. The solid matters obtained by this venerable prelate, were, an aqueous ammoniacal fluid, a tenaceous oil, resembling tar, an ammoniacal liquor, and a spongy coal, or coke.
[12]Watson’s Chemical Essays, vol. II.
[12]Watson’s Chemical Essays, vol. II.
The first discovery and application of the use of coal-gas for the purpose of illumination is claimed by Mr. Murdoch.
Dr. W. Henry of Manchester, has published the following account[13]of this discovery.
[13]Thompson’s System of Chemistry, vol. I. p. 52.
[13]Thompson’s System of Chemistry, vol. I. p. 52.
“In the year 1792, at which time Mr. Murdoch resided at Redruth, in Cornwall, he commenced a series of experiments upon the quantity and quality of the gases contained in different substances. In the course of these he remarked, that the gas obtained by distillation from coal, peat, wood, and other inflammable substances, burnt with great brilliancy upon being set fire to; and it occurred to him, that by confining and conducting itthrough tubes, it might be employed as an economical substitute for lamps and candles. The distillation was performed in iron retorts, and the gas conducted through tinned iron and copper tubes to the distance of 70 feet. At this termination, as well as at intermediate points, the gas was set fire to, as it passed through apertures of different diameters and forms, purposely varied with a view of ascertaining which would answer best. In some the gas issued through a number of small holes like the head of a watering pan; in others it was thrown out in thin long sheets; and again in others in circular ones, upon the principle of Argand’s lamp. Bags of leather and of varnished silk, bladders, and vessels of tinned iron, were filled with the gas, which was set fire to, and carried about from room to room, with a view of ascertaining how far it could be made to answer the purpose of a moveable or transferable light. Trials were likewise made of the different quantities and qualities of gas produced by coals of various descriptions, such as the Swansea, Haverfordwest, Newcastle, Shropshire, Staffordshire, and some kinds of Scotch coals.
“Mr. Murdoch’s constant occupations prevented his giving farther attention to the subject at that time; but he again availed himself of a moment of leisure to repeat his experiments upon coal and peat at Old Cumnock, in Ayrshire, in 1797; and it may be proper to notice that both these, and the former ones, were exhibited to numerous spectators, who, if necessary, can attest them. In 1798, he constructed an apparatus at Soho Foundry, which was applied during many successive nights to the lighting of the building; when the experiments upon different apertures were repeated and extended upon a large scale. Various methods were also practised of washing and purifying the air, to get rid of the smoke and smell. These experiments were continued, with occasional interruptions, until the epoch of the peace in the spring of 1802, when the illumination of the Soho manufactory afforded an opportunity of making a public display of the new lights; and they were made to constitute a principal feature in that exhibition.”
In the year 1803 and 1804, Mr. Winsor exhibited at the Lyceum in London the generalnature of this new mode of illumination though the machinery for procuring, and the manner of purifying the gas, he kept a secret. He exhibited the mode of conducting the gas through the house, and a number of devices for chandeliers, lamps, and burners, by which it might be applied. Among these he proposed long flexible tubes suspended from the ceiling, or wall of the room, and at the end communicating with burners or lamps of different kinds. This gentleman showed also by experiment, that the flame of the gas-light, produced no smoke; that it was not so dangerous as the flame of candles or lamps; that it could not produce sparks; and that it was not so readily extinguished by gusts of wind or torrents of rain.
Mr.Winsor’s display of gas-lights took place more than two years before Mr.Murdoch’s priority of right was heard of.
In stating these facts I do not mean to say that Mr.Murdochderived the hint of applying the coal-gas from the previous exhibition of Mr.Winsor, because it is quite within the bounds of probability that the ideas of Mr.Murdochmay have arisen totally independent of all acquaintance with Mr.Winsor’s.
The claims of invention, or the determination of the right of priority, concerns the public only so far as the honour and estimation of any useful discovery conferred on the inventor may induce other individuals to devote their talents to similar pursuits; by means of which, more discoveries may be made, and the subject of human invention become extended, or rendered more useful. For as the mere benefits which mankind may derive from any particular discovery, they are certainly more indebted to the person who first applied the discovery to actual practice, than to him who first made it, and merely illustrated it by barren experiments. Mr.Winsorcertainly pressed on the mind of the public with unremitted perseverance and diligence the extensive application of gas-light in the year 1802, but he made no new discovery with regard to the composition of coal; he did not even invent the mode of conducting the gas through tubes; and if he has pointed out the particulars of the process, he has made a very important, though not the most brilliant improvement in this line of business. Mr.Winsor’s publications are, perhaps, but ill adapted to promote his cause; and the exaggerated calculation which the sanguine mind of a discoverer is naturally disposed to indulge in, have, to superficial observers, thrown an air of ridicule and improbability on the whole scheme of lighting with gas.
It may, however, be safely affirmed, that if the same facts had come forward, under the sanction of some great name in the chemical or philosophical world, the public incredulity would long since have been subdued; and the plan, which for many years has been struggling for existence, would have been eagerly adopted as a national object.
On the 18th of May, 1804, Mr.Frederick Albert Winsor, took out a patent for combining the saving and purifying of the inflammable gas (for producing light and heat), the ammonia, tar, and other products of pit-coal, with the manufacture of a superior kind of coke (see Repertory, 2d Series, v. 172). And, lately, the same gentleman has taken out a second patent, for further improvements in these processes.
In the year 1805, Mr.Northern, of Leeds,also directed the attention of the public to the application of coal-gas, as a substitute for tallow light, as will be seen by the following extract of the Monthly Magazine for April, 1805.
“I distilled in a retort, 50 ounces of pit-coal in a red heat, which gave 6 ounces of a liquid matter covered with oil, more or less fluid as the heat was increased or diminished. About 26 ounces of cinder remained in the retort; the rest came over in the form of air, as it was collected in the pneumatic apparatus. I mixed part of it with atmospherical air, and fired it with the electric spark with a tolerable explosion, which proves it to be hydrogene.—Whether any of the other gases were mixed with it, I did not then determine. In the receiver I found a fluid of an acid taste, with a great quantity of oil, and, at the bottom, a substance resembling tar.
“The apparatus I make use of for producing light is a refiner’s crucible, the top of which (after filling with coal) I close with a metal cover, luted with clay or other luting, so as to prevent the escape of the gas; a metal pipe is soldered into the cover, bent so as tocome under the shelf in the pneumatic trough, over which I place a jar with a stop-cock and a small tube; the jar being previously filled with water, the crucible I place on the common or other fire as is most convenient; and as the heat increases in it, the gas is forced rapidly through the water into the jar, and regularly displaces it. I then open the cock and put fire to the gas, which makes its escape through the small tube, and immediately a most beautiful flame ensues, perfectly free from smoke or smell of any kind. A larger light, but not so vivid or clear, will be produced without passing the gas through water, but attended with a smoke somewhat greater than that of a lamp charged with common oil.
“I have great hopes that some active mechanic or chemist will, in the end, hit on a plan to produce light for large factories, and other purposes, at a much less expence, by the above or similar means, than is at present produced from oil.”
Soon afterwards, Mr.Samuel Clegg[14]of Manchester, Engineer, communicated an account of his method of lighting up manufactorieswith gas-light to the Society of Arts, for which he received the silver medal.
[14]This gentleman is at present engineer to the Gas-Light Company.
[14]This gentleman is at present engineer to the Gas-Light Company.
Since that time, the application of gas-light has spread rapidly, and numerous manufactories and other establishments have been lighted by coal-gas.
In France, the application of gas-lights to economical purposes, was pointed out long before it was publicly introduced into this country. M.Le Bonhad a house fitted up in Paris, in the winter of 1802, so as to be entirely illuminated by gas-lights, which was seen by thousands with admiration; and had abrevet d’invention(patent) granted to him by the French government, for the art of producing light from wood, ignited in close vessels.
Many other attempts have been made to derive advantage from the different ingredients of coal; but they are too obscure to merit particular enumeration.
In the year 1808, Mr.Murdochpresented to the Royal Society his account of the application of gas-light, and was complimented with CountRomford’s medal for the same.
The following statement is taken from Mr.Murdoch’s paper.
“The whole of the rooms of the cotton mill of Mr.Lee, at Manchester, which is I believe the most extensive in the United Kingdom, as well as its counting-houses and store-rooms, and the adjacent dwelling house of Mr.Lee, are lighted with the gas from coal. The total quantity of light used during the hours of burning has been ascertained, by a comparison of shadows, (seepage 23) to be about equal to the light which 2500 mould candles, of six to the pound, would give; each of the candles with which the comparison was made consuming at the rate of 4-10ths of an ounce (175 grains) of tallow per hour.
“The gas-burners are of two kinds: the one is upon the principle of the Argand lamp, and resembles it in appearance; the other is a small curved tube with a conical end, having three circular apertures or perforations, of about a thirtieth of an inch in diameter, one at the point of the cone, and two lateral ones, through which the gas issues, forming three divergent jets of flame, somewhat like a fleur-de-lis. The shape and general appearance of this tube has procured it, among the workmen, the name of the cockspur burner.
“The number of burners employed in all the buildings amounts to 271 Argand, and 653 cockspurs, each of the former giving a light equal to that of four candles of the description above-mentioned; and each of the latter a light equal to two and a quarter of the same candles; making therefore the total of the gas-light a little more than equal to that of 2500 candles, six to the pound. When thus regulated, the whole of the above burners require an hourly supply of 1250 cubic feet of the gas produced from cannel-coal; the superior quality and quantity of the gas produced from that material having given it a decided preference in this situation over every other coal, notwithstanding its higher price.
“The time during which the gas-light is used may, upon an average of the whole year, be stated at least at two hours per day of 24 hours. In some mills, where there is over work, it will be three hours; and in the few where night work is still continued nearly 12 hours. But taking two hours per day as the common average throughout the year, the consumption in Messrs. Philips and Lee’s mill will be 1250 × 2 = 2500 cubic feet of gas per day; to produce which 700 weight ofcannel-coal is required in the retort. The price of the best Wiggan cannel-coal (the sort used) is 131⁄2d.per cwt. (22s.6d.per ton) delivered at the mill, or say about eight shillings for the seven hundred weight. Multiplying by the number of working days in the year (313,) the annual consumption of coal will be 110 tons, and its cost 125l.
“About one-third of the above quantity, or say forty tons of good common coal, value ten shillings per ton, is required for fuel to heat the retorts, the annual amount of which is 20l.
“The 110 tons of cannel-coal, when distilled, produce about 70 tons of good coke, which is sold upon the spot at 1s.4d.per cwt. and will therefore amount annually to the sum of 93l.
“The quantity of tar produced from each ton of cannel-coal is from 11 to 12 ale gallons, making a total annual produce of about 1250 ale gallons, which not having been yet sold, it cannot yet be determined its value.
“The interest of the capital expended in the necessary apparatus and buildings, together with what is considered as an ample allowance for wear and tear, is stated by Mr.Leeat about 550l.per annum, in which some allowance ismade for this apparatus being made upon a scale adequate to the supply of a still greater quantity of light, than he has occasion to make use of.
“Mr.Leeis of opinion that the cost of attendance upon candles would be as much, if not more, than upon the gas apparatus; so that, in forming the comparison, nothing need be stated upon that score, on either side.
“The economical statement for one year, then, stands thus:
“That of candles, to give the same light,would be about 2000l.For each candle, consuming at the rate of 4-10ths of an ounce of tallow per hour, the 2500 candles burning, upon an average of the year, two hours per day, would, at one shilling per pound, the present price, amount to nearly the sum of money above-mentioned.
“If the comparison were made upon an average of three hours per day, as in most cases, would perhaps be nearer to the truth, and the tear and wear remaining nearly the same as on the former case, the whole cost would not exceed 650l.while that of the tallow would be 3000l.”
Mr.Ackermanin this metropolis, has shown that the art of gas-light illumination is not confined to great manufactories, but that its advantages are equally applicable to those on a moderate scale. The whole of Mr.Ackerman’s establishment, his public library, warehouse, printing-offices and work-shops, together with his dwelling house, from the kitchen to the drawing-room, has, for these four years past, been lighted with gas, to the total exclusion of all other lights. The result of the whole of this proceeding will be obvious from the following letter:
ToMr.ACCUM.Sir,“In answer to your request with regard to my gas-lights, which I now have in my house, I take this mode of informing you, that I charge two retorts with 240lbs. of coal, half cannel and half Newcastle, from which I extract 1000 cubic feet of gas. To obtain this quantity of gas, when the retorts are cold, I use from 100 to 110lb. of common coals; but when they are in a working state, that is to say, when they are once red hot, the carbonising fuel amounts to about 25lb. per retort. The bulk of gas thus obtained supplies 40 Argand’s lamps, of the large size, for four hours per night, during the long winter evenings, together with eight Argand’s lamps and about 22 single cockspur burners, for three hours per night: in addition to which my printers employ 16 cockspur burners for ten hours per day to heat their plates instead of charcoal fire. In the depth of winter we charge two retorts per day: but, upon an average, we work 365 retorts in 365 days.Now 365 retorts containing 120lb. of coal each, make 43800lb. which is equal to ten chaldrons of Newcastle and eight tons of cannel coal.10chaldrons of Newcastle coals, at 65s. make£ 321008tons of cannel coal,[15](this coal is sold by weight) at 100s. per ton40007chaldrons of common coals for carbonising, at 55s.1950To wages paid the servant for attending the gas apparatus3000Interest of money sunk3000The wear and tear of the gas-light apparatus I consider to be equal to the wear and tear of lamps, candlesticks, &c. employed for oil, tallow, &c.Total expence of the gas lights151150DEDUCT23chaldrons of coke, at 60s. per chaldron69Ammoniacal liquor5Tar6Charcoal employed by the copper-plate printers to heat their plates, which is now done with the gas-light flame, cost, annually25Two chaldrons of coalsminusused as fuel, for warming the house, since the adoption of the gas-lights, at 65s. per chaldron610111100Nett expences of the gas-lights£ 4050The lights used in my Establishment, prior to the gas-lights, amounted annually to16000My present system of lighting with gas costs, per ann.4050Balance in favor of the gas for one year£ 119150
ToMr.ACCUM.
Sir,
“In answer to your request with regard to my gas-lights, which I now have in my house, I take this mode of informing you, that I charge two retorts with 240lbs. of coal, half cannel and half Newcastle, from which I extract 1000 cubic feet of gas. To obtain this quantity of gas, when the retorts are cold, I use from 100 to 110lb. of common coals; but when they are in a working state, that is to say, when they are once red hot, the carbonising fuel amounts to about 25lb. per retort. The bulk of gas thus obtained supplies 40 Argand’s lamps, of the large size, for four hours per night, during the long winter evenings, together with eight Argand’s lamps and about 22 single cockspur burners, for three hours per night: in addition to which my printers employ 16 cockspur burners for ten hours per day to heat their plates instead of charcoal fire. In the depth of winter we charge two retorts per day: but, upon an average, we work 365 retorts in 365 days.
Now 365 retorts containing 120lb. of coal each, make 43800lb. which is equal to ten chaldrons of Newcastle and eight tons of cannel coal.
[15]Although cannel-coal sells at nearly double the price of Newcastle coal, I use it in preference to the latter, because it affords a larger portion of gas, and gives a much more brilliant light.
[15]Although cannel-coal sells at nearly double the price of Newcastle coal, I use it in preference to the latter, because it affords a larger portion of gas, and gives a much more brilliant light.
Such is the simple statement of my present system of lighting, the brilliancy of which, when contrasted with our former lights, bears the same comparison to them as a bright summer sun-shine does to a murky November day: nor are we, as formerly, almost suffocated with the effluvia of charcoal and fumes of candles and lamps. In addition to this, the damage sustained by the spilling of oil and tallow upon prints, drawings, books and paper, &c. amounted annually to upwards of 50l. All the workmen employed in my establishment consider their gas-lights as the greatest blessing; and I have only to add, that the light we now enjoy, were it to be produced by means of Argand’s lamps or candles, would cost at least 350l. per annum.I am, with respect,Yours,Strand, March 13,1815.R. ACKERMAN.”
Such is the simple statement of my present system of lighting, the brilliancy of which, when contrasted with our former lights, bears the same comparison to them as a bright summer sun-shine does to a murky November day: nor are we, as formerly, almost suffocated with the effluvia of charcoal and fumes of candles and lamps. In addition to this, the damage sustained by the spilling of oil and tallow upon prints, drawings, books and paper, &c. amounted annually to upwards of 50l. All the workmen employed in my establishment consider their gas-lights as the greatest blessing; and I have only to add, that the light we now enjoy, were it to be produced by means of Argand’s lamps or candles, would cost at least 350l. per annum.
I am, with respect,Yours,
Strand, March 13,1815.
R. ACKERMAN.”
Another manufacturer who was one of the first that adopted the use of this method of illumination in the small way, and who gave a statement of its advantages to the public, is Mr.Cook, a manufacturer of metal toys, at Birmingham, a clear-headed, prudent man, not apt to be dazzled by a fanciful speculation, but governed in his transactions by a simple balance of profit and loss. There is anaïvetéin his own account of the process which will amuse as well as instruct the reader.
“My apparatus is simply a small cast-iron pot, of about eight gallons, with a cast-iron cover, which I lute to it with sand. Into this pot I put my coal. I pass the gas through water into the gasometer or reservoir, which holds about 400 gallons; and, by means of old gun-barrels, convey it all round my shops. Now, from twenty or twenty-five pounds of coal, Imake perhaps six hundred gallons[16]of gas; for, when my reservoir is full, we are forced to burn away the overplus in waste, unless we have work to use it as it is made: but, in general, we go on making and using it, so that I cannot tell to fifty or a hundred gallons;—and, in fact, a great deal depends on the coals, some coals making much more than others. These twenty-five pounds of coal put into the retort, and say twenty-five pounds more to heat the retort, which is more than it does take one time with another, but I am willing to say the utmost, are worth four-pence per day. From this four-pence we burn eighteen or twenty lights during the winter season.”
[16]A wine-gallon is equal to 231 cubic inches.
[16]A wine-gallon is equal to 231 cubic inches.
Thus are the candles which Mr.Cookused to employ, and which cost him three shillings a day, entirely superseded. But, besides his expence in candles, oil and cotton for soldering, used to cost him full 30l.a year; which is entirely saved, as he now does all his soldering by the gas flame only. For “in all trades in which the blow-pipe is used with oiland cotton, or where charcoal is employed to produce a moderate heat, the gas flame will be found much superior, both as to quickness and neatness in the work: the flame is sharper, and is constantly ready for use; while, with oil and cotton or charcoal, the workman is always obliged to wait for his lamp or coal getting up; that is, till it is sufficiently on fire to do his work. Thus, a great quantity of oil is always burned away useless; but, with the gas, the moment the stop-cock is turned, the lamp is ready, and not a moment is lost.” We must refer to Mr.Cook’s letter for the details of expence, which he gives with faithful minuteness, and always leaning to the side unfavourable to the gas. The result of the whole is, that he saves 30l.out of the 50l.which his lights formerly cost him: and, when we consider that his calculation allows the gas-lights to burn the whole year, and the candles only twenty weeks, there can be little doubt, that the savings in this case follow nearly the same proportion as in the former. If the apparatus be erected even on a smaller scale, “the saving,” Mr.Cookassures us, “will still be considerable:for the poor man, who lights only six candles, or uses one lamp, if the apparatus is put up in the cheapest way possible, will find it only cost him 10l.or 12l.which he will nearly, if not quite, save the first year.”
Mr.Ackermanhaving, in this town, set the example of lighting his establishment with gas, several other individuals soon followed the attempt. The following statement will show, that this species of light may be made use of with the greatest advantage, upon a still smaller scale, where no great nicety with regard to the apparatus for procuring gas is required. The following report I have received from Messrs.Lloyd, of Queen Street, Southwark, thimble manufacturers and whitesmiths, who have used the gas-light for soldering and other purposes these five years past.
“The gas-burners made use of in our manufactory produce jets of flame, which in our business, where much soldering with the blow-pipe must be done, have a decided superiority over Argand’s lamps. We are not nice concerning the quality of the gas—a great part of it is burned from the gasometer, without allowing it to purify itself in the gasometer, because our gasometer is not large enough to store up the whole quantity of gas we want for use.”
To obtain carburetted hidrogen, or coal-gas, from common pit-coal, and to apply it for the purposes of illumination, the coal is introduced into large iron cylinders, called retorts, to the apertures of which iron pipes are adapted, terminating in a vessel, or vessels, destined to purify and collect the gas. The retorts charged with coals and made air-tight, are placed upon the fire, the action of which extricates the gazeous products from the coals, together with an aqueous ammoniacal vapour, and a tenaceous bituminous fluid, or tar, &c. The liquid substances are conveyed into proper vessels, and the gazeous products are conducted, by means of pipes, under the gasometer, where thegas is again washed, and remains ready for use. There are also other pipes leading from the gasometer, which branch out into smaller ramifications, until they terminate at the places where the lights are wanted. The extremities of the pipes have small apertures, out of which the gas issues, and the streams of gas being lighted at those apertures burn with a clear and steady flame as long as the supply of gas continues. All the pipes which come from the gasometer are furnished at their extremities with stop-cocks to regulate the admission of the gas. The burners are formed in various ways, either a tube ending with a simple orifice, at which the gas issues in a stream, and if once lighted will continue to burn with the most steady and regular light imaginable, as long as the gas is supplied; or two concentric tubes of brass, or sheet-iron, are placed at a distance of a small fraction of an inch from each other, and closed at the bottom. The gas which enters between these cylinders, when lighted, forms an Argand lamp, which is supplied by an internal and external current of air in the usual manner. Or the two concentric tubes are closed at the top with a ring having small perforations, out ofwhich the gas alone can issue, thus forming small distinct streams of light.
Gas-apparatusLarger image(279 kB)
Larger image(279 kB)
The gas-apparatus,plate 2, will be found very convenient for exhibiting, in the small way, the general nature of this new art of illumination, whilst at the same time it may serve to ascertain, at a trifling expence, the comparative value of different kinds of coals intended to be employed for the production of this species of light, as well as other occasional purposes connected with the gas-light system of illumination.
It consists of three distinct apparatus:—namely, a portable furnace,fig. 1, plate 2, by means of which the gas is prepared—fig. 2, a purifyer, or condenser, which separates and purifies the products obtained from the coal, so as to render the gas fit for the purpose of illumination—fig. 3, a gasometer, or reservoir for receiving and preserving the purified stock of gas, and from which it may be transferred and distributed as occasion may require. The following statement will explain more fully the general nature of this portable chamber apparatus:—a, represents a cast iron retort, such as is used for chemical operations in the smallway. This retort rests upon a tripod of hammered iron, placed upon the bars of the grate of the chemical furnace. Into this retort the coals are put for furnishing the gas. It is provided with a solid iron stopper ground air-tight into the mouth of the retort, and the stopper is secured in its place by an iron wedge passing over it in the centre; by means of which the mouth of the retort when charged with coal is readily made air-tight, and the stopper may easily be removed by knocking out the iron wedge.b.is a metal pipe which conveys all the distillatory products from the retort into the purifierfig. 2. This tube is bent at right angles at the extremity where it enters the intermediate vesselfig. 2. The purifierfig. 2, is divided into three compartments markedc.d.e.The first compartment is filled with water, and by means of it an air-tight communication is established with the retort which furnishes the gas. The second compartment,d, contains a solution of caustic pot-ash composed of about 2 parts of caustic pot-ash and 16 of water, or a mixture of quick-lime and water of the consistence of very thin cream. The object of this compartment is to separate the non-inflammablegases and other products evolved during the distillation of the coal, from the carburetted hidrogen or coal-gas, so as to render it fit for use. The third compartmenteis left empty to receive the tar and other liquid products. Into the first compartmentc, all the gazeous and liquid products are delivered, as they become evolved during the distillation, by means of the pipeb. The compartmentd, of the purifier, or alcali vessel, is furnished with a wide perpendicular pipe, which serves to make an air-tight communication with the retort, by allowing the tubeb, to pass readily through it. From the chamberc, the liquid and gazeous products pass to the tar-chamber, or compartmente, by means of the descending pipef. The tar and other condensible substances are therefore deposited ate, whilst the gazeous products alone ascend from the tar-chambere, by the pipeg, and down again the pipeh, (which is closed at the top) into the compartmentd, of the vessel or purifier,fig. 2. The gas being thus made to pass from the compartmente, up into the pipeg, and down the pipeh, (which is closed at the top) into the purifierd, is brought into contact withthe liquor in that vessel, where it is opposed to a pressure in proportion to the perpendicular height of the column of liquid which it contains. The funnel in the compartmentc, is considerably higher than the purifying apparatus, it therefore allows the liquid which it contains, when pressed upon by the gas, to ascend into it, without overflowing the apparatus, and to descend again as the pressure diminishes—iis another wide-mouth funnel, by means of which the chamberd, is filled with the alcaline solution, or mixture of lime and water. The carbonic acid gas and sulphuretted hidrogen, evolved during the distillation of the coal, are thus made to combine with the alcali or lime, in the compartmentd, of the purifier, forming carbonate and hidro-sulphuret of lime. The carburetted hidrogen, being left more or less pure, is conveyed through the pipek, into the gasometer,fig. 3. The communication of the purifier,fig. 2, with the gasometer, is made by means of the well-known water-valvel, placed so that the communicating tubek, may be easily removed at pleasure—m, is a cock for drawing off the tar, &c.n, a gauge-cock for ascertaining the height ofthe liquid in the chamberd. The gasometer,fig. 3, the object of which is to store up the gas, consists of two principal parts—namely, a large interior vessel designed to contain the gas, and an outer cistern or vessel, of rather greater capacity, in which the former is suspended, designed to contain the water by which the gas is confined. The interior vessel which contains the gas is suspended by chains or cords hung over pullies, to which weights are attached, so as to nearly equipoise it.ois a pipe, which communicates with the water-valvel, and by means of which the gas passes from the purifier,fig. 2, into the gasometer. The upper end of this pipe is covered, in the manner of a hood, by a cylindrical vesselp, open at bottom, but partially immersed beneath the surface of the water contained in the outer cistern of the gasometer, and perforated round near the lower edge with a number of small holes. The gas displaces the water from this receiverp, and escapes through the small holes, rising in bubbles through the water, so as to expose a large surface to its action, that it may be properly washed, &c. After rising through the water the gas entersthe gasometer, which is suspended to move up and down by the chains, pullies, and balance-weights,q. From the centre of the gasometer a tube,r, descends, which includes a pipe,s, fixed perpendicular from the bottom of the cistern. The fixed piper, forms a guide to keep the gasometer always perpendicular.tis also an iron pipe made fast in the centre of the inner vessel, and communicates with the upright tube,s, in the outer vessel. This contrivance obliges the gas to pass into the pipet, whilst it also serves to keep the gasometer steady when nearly out of the outer cistern.
When the operation commences, the gasometer is sunk down nearly to a level with the surface of the water in the outer cistern, and is consequently filled with water; but as the gas enters, it rises up to receive it. It is to be noted, that the balance-weightsqq, should not be quite so heavy as the gasometer, in order that some pressure may be exerted, to force the gas out of the burners with a proper jet. The gas which issues from the retort enters the purifier as stated already, and ascends the pipeo, into the vessel,p, from which it displaces the water, and passes out at the small holes, asbefore described, rising through the water into the gasometer, and raising it up: the gas then passes away to the burners,uu. In this manner the process proceeds until the whole of the volatile products of the coal in the retort is evaporated. The use of the gasometer is, to equalize the emission of the gas which comes from the retort more quickly at some time than others. When this happens, the interior vessel rises up to receive it, and when the stream from the retort diminishes, the weight of the gasometer expels its contents. When the process is finished, the retort is suffered to cool, and its ground stopper is then removed to replenish it with coal. The residue found in the retort is coke.vvare cocks to let off any liquid that may collect in the pipeoort; for if the smallest portion of liquid were to obstruct the free passage of the gas to the burners, the consequence would be, that the lights would not burn steadily—they would, as it is called,dance, or become extinguished.xis the main stop-cock which communicates with the burners—these, of course, may be placed as convenience may require.zzare two projecting parts in the top of the gasometer;they are intended to receive the hoodp, and the upper extremity of the pipet, so as to allow the gasometer to be wholly immersed into the cistern. The wheels or pullies of the gasometer have a groove to allow the links of the chain to pass freely.
In this apparatus there is no provision made for the unequal pressure which the gas suffers, accordingly as the gasometer is more or less immersed in water. It will be observed that, in this apparatus, the weight of the interior vessel is constantly increasing, in proportion as it fills with gas, and rises out of the water, and consequently, if a constant, uniform, counterpoising weight, equal only to that of the gasometer in the first moment of its rise, be employed, the gas becomes gradually more and more compressed by that part of the weight of the gasometer which is not counterpoised, and if its pressure or quantity be then estimated by the bulk which it occupies, without making allowance for the increasing pressure, a material error must arise, and this, in the large way, would give rise to insurmountable difficulties with regard to the regulationof the size of the flames; which could not be rendered uniform.
Suppose the cistern or exterior vessel full of water, and the gasometer partly filled with gas and partly with water, it is evident that the balance-weight may be so adjusted, as to occasion an exact equilibrium, so that the external air shall not tend to enter into the gasometer nor the gas to escape from it; and in this case the water will stand exactly at the same level both within the gasometer and within the outer cistern. On the contrary, if the balance-weights be diminished, the gasometer will then press downwards from its own gravity, and the water will stand lower in the gasometer than it does in the cistern; in this case, the included air or gas will suffer a degree of compression above that experienced by the external air, exactly proportioned to the weight of a column of water, equal to the difference of the external and internal surfaces of the water.
To compensate for this increasing weight of the gasometer, and render a scale of equal graduations accurate, some have ingeniouslyadopted the plan of a spiral pulley to the chain, which has the effect of gradually avoiding the evil, but the best way of accomplishing it will be stated hereafter.
With regard to the philosophy or the production of coal-gas, it proves that pit-coal contains solid hidrogen, carbon, and oxigen. When the intensity of the heat has reached a certain degree, a part of the carbon unites with part of the oxigen and produces carbonic acid, which by means of caloric is melted into the gazeous state and forms carbonic acid gas; at the same time, part of the hidrogen of the coal combines with another portion of carbon and caloric, and forms the carburetted hidrogen gas, which varies considerably in its constitution, according to the circumstances under which it is produced; a portion of olifiant gas, carbonic oxid, hidrogen, and sulphuretted hidrogen, is also produced during the process. The quantities of these products vary according to the nature of the coal employed in the process.
Pit-coal is not the only substance which affords carburetted hydrogen; this gazeous fluidmay be obtained in a great variety of ways, and with very considerable differences in specific gravity and proportion of ingredients.
It is found plentifully native or ready formed on the surface of stagnant waters, marshes, wet ditches, &c. through which, if examined closely, large bubbles will be seen to rise in hot weather, and may be increased at pleasure by stirring the bottom or mud with a stick.
In close still evenings if a lighted candle is held over the surface, flashes of blue lambent flame may sometimes be perceived spreading to a considerable distance. All that is not fabulous concerning theignis fatuusis probably derived from this source. This species of gas is termed for distinction the carburetted hydrogen of marshes. In the purest form in which it can be collected it is mixed with about 20 per cent. of azot or nitrogen.
To procure the gas for the purpose of philosophical amusement, fill a wide-mouthed bottle with the water of the ditch, and keep it inverted therein with a large funnel in its neck, then with a stick stir the mud at the bottom just under the funnel, so as to cause the bubbles of air which rise from the mud to enterinto the bottle; when by thus stirring the mud in various places, the air may be catched in the bottle.
Carburetted hidrogen gas is also given out very abundantly by all kinds of vegetable matter when subjected to a scorching heat sufficient to decompose them. When heated in close vessels much more gas is obtained than when burnt in the open air. If moistened charcoal be put into an earthen retort and heat be applied till the retort becomes ignited; gas will be evolved, consisting partly of carbonic acid, and partly of carburetted hidrogen. A gas of similar properties is obtained by causing steam to pass through a tube filled with red-hot charcoal; by passing spirit of wine, or camphor, through red-hot tubes; by distilling oils, wood, bones, wax and tallow, or any animal or vegetable body whatever.
Indeed it would be endless to enumerate the various sources of this gazeous fluid. A most curious variety of carburetted hidrogen gas has been discovered by the associated Dutch chemists (Van Dieman,Troostwyck, and others) which is procured from ether or alcohol, and has the remarkable property of generating a heavy oil when in contact with chlorine gas.Hence it has been termed oily carburetted hidrogen, or olifiant gas—it consists of carburetted hydrogen, supersaturated with carbon. The oil generated is heavier than water, whitish, and semi-transparent. By keeping, it becomes yellow and limpid; its smell is highly fragrant and penetrating—its taste somewhat sweet—it is partly soluble in water, imparting to it, its peculiar smell. A portion of this gas always accompanies the common carburetted hidrogen obtained from coal, and those sorts of coal that afford the largest quantity of it are best suited for the production of gas-light.
The nature of carburetted hidrogen obtained from coal varies considerably according to the conditions under which it is obtained. The first part is always much heavier than the last, though still lighter than common air, and holds in solution a portion of oil, for on standing for some time over water it becomes lighter, and is found to require less oxygen for saturation than before. The oil which it held suspended, then becomes precipitated. The average specific gravity of the first and last gas mixed, which may be taken as an average of the whole specific gravity is to that of commonair as 2 to 3—112lb. of common cannel coal produce at itsminimum, from 350 to 360 cubic feet of carburetted hidrogen gas; but the same quantity of the best Newcastle coal, that is to say, such as coke, which, when laid on the fire readily undergoes a kind of semi-fusion, and sends out brilliant streams of flame, produces upon an average from 300 to 360 cubic feet of this gazeous fluid, besides a large portion of sulphuretted hidrogen, carbonic oxid and carbonic acid. Half a cubic foot of this carburetted hidrogen, fresh prepared, that is to say, holding in solution or suspension, a portion of the essential oil, which is generated during the evolution of the gas, is equal in illuminating power to from 170 to 180 grains of tallow, (being the quantity consumed by a candle six to the pound in one hour.) Now, one pound avoirdupoise is equal to 7000 grains, and consequently one pound of candles of six in the pound, burning one at a time in succession, would last (if we take 175 grains of tallow to be consumed in an hour)7000175= 40 hours. To produce the same light we must burn one half of a cubic foot of coal-gas per hour; therefore, one-half multiplied by forty hours is equal to twenty cubic feet of gas in 40 hours,consequently equal to one pound of candles, six to the pound, provided they were burnt one after another. One hundred and twelve pounds of cannel-coal, produce, at itsminimum, three hundred and fifty cubic feet of gas; and are equal to three hundred and fifty, divided by twenty, which last is equivalent to one pound of tallow, making one hundred and twelve pounds of cannel-coal, equal to35020= 171⁄2lbs. of tallow. Further, one hundred and twelve pounds of cannel-coal, divided by seventeen and a half of tallow make six and four-tenths of cannel-coal, equal to one pound of tallow.
With regard to Newcastle coals[17], it may be stated that one chaldron of Wall’s-End coal may be made to produce in the large way upwards of 11,000 cubic feet of crude gas; which, when properly purified, diminishes to nearly 10,000 cubic feet.