Main pipe, leading from the Gas-light station or apparatus,situated in Brick Lane, near Old St.[34]Main pipe, leading from the gaslight apparatus, or station, at Norton Falgate.[35]Main pipe, leading from the gaslight apparatus, or station,in Westminster.[36][34]The gasometer at this place is equal in capacity to 22000 cubic feet.[35]The capacity of the gasometer here is equal to 15928 cubic feet.[36]At this station the gasometer is equal in capacity to 14808 cubic feet.
Main pipe, leading from the Gas-light station or apparatus,situated in Brick Lane, near Old St.[34]Main pipe, leading from the gaslight apparatus, or station, at Norton Falgate.[35]Main pipe, leading from the gaslight apparatus, or station,in Westminster.[36]
Main pipe, leading from the Gas-light station or apparatus,situated in Brick Lane, near Old St.[34]
Main pipe, leading from the gaslight apparatus, or station, at Norton Falgate.[35]
Main pipe, leading from the gaslight apparatus, or station,in Westminster.[36]
[34]The gasometer at this place is equal in capacity to 22000 cubic feet.[35]The capacity of the gasometer here is equal to 15928 cubic feet.[36]At this station the gasometer is equal in capacity to 14808 cubic feet.
[34]The gasometer at this place is equal in capacity to 22000 cubic feet.
[35]The capacity of the gasometer here is equal to 15928 cubic feet.
[36]At this station the gasometer is equal in capacity to 14808 cubic feet.
Pipe network*The gasometer at this place is equal in capacity to 22000 cubic feet.†The capacity of the gasometer here is equal to 15928 cubic feet.‡At this station the gasometer is equal in capacity to 14808 cubic feet.
Pipe network
*The gasometer at this place is equal in capacity to 22000 cubic feet.†The capacity of the gasometer here is equal to 15928 cubic feet.‡At this station the gasometer is equal in capacity to 14808 cubic feet.
*The gasometer at this place is equal in capacity to 22000 cubic feet.
†The capacity of the gasometer here is equal to 15928 cubic feet.
‡At this station the gasometer is equal in capacity to 14808 cubic feet.
Theblack linesrepresent the gas-light mains, or largest pipes, from which the smaller pipes branch off: they are connected with each other at the places marked A B C; and the dotted lines represent the smaller mains, or collateral branches before-mentioned. The main pipes are all furnished with valves, or cocks, placed at about 100 feet distant from each other. Now let us suppose that a main pipe, in any part of the street marked in the sketch,Pall Mall, should break, it is evident, on mere inspection, that the gas which ispassing through the main in theStrand, and which is also connected with the main in theHaymarket,Piccadilly, andCoventry Street, would continue to supply the broken pipe, and the valve nearest to the fracture being shut, would prevent the loss of any considerable quantity of gas, and the few lamps situated between the two valves and the fracture would therefore only become extinguished.
Further, let us suppose a main pipe should break inPiccadilly; in that case, the valve being shut on each side of the fracture, the gas would be supplied from the mains in theHaymarketandSt. James’s Street. And the same effect would be produced in any part of the town, supplied with gas-pipes. Besides all this, in the statement thus far given, we have assumed that all the gas-light mains are supplied with gas from one manufacturing station only, but which in reality is not the case. The range of pipes that convey the gas is connected with three gas-light establishments, situated at different parts of the town; and the gas which is supplied from these stations is connected with the whole system of pipes in thestreets.[37]If, therefore, one of the manufactories should be annihilated, it would make no difference, because the lights would be amply supplied from the other two manufacturing stations. Hence it is obvious, that the fracture of any of the gas-light mains, or even the total destruction of one or more of the manufactories themselves, would be attended with no serious consequence; and as the system of lighting with gas becomes more extended, the manufactories, or stations for supplying it, will also be multiplied, to give effect and security to the whole.
[37]As shown in thesketch.
[37]As shown in thesketch.
In fact, no danger can arise from the application of gas-lights in any way, but what is common to candle-light, and lamps of all kinds, and is the fault of none of them. Even in this case the gas-lights are less hazardous. There is no risk of those accidents which often happen from the guttering or burning down of candles, or from carelessly snuffing them. The gas-light lamps and burners must necessarily be fixed to one place, and therefore cannot fall, or otherwise becomederanged, without being immediately extinguished. Besides, the gas-light flames emit no sparks, nor are any embers detached from them. As a proof of the comparative safety of the gas-lights, it need only be stated, that the Fire-offices engage themselves to insure cotton-mills, and other public works, at a less premium, where gas-lights are used, than in the case of any other lights.[38]The excessive expence of insurance arising from the numerous candles employed in most of the first rate manufactories, and the combustible nature of the structure of the buildings; the great difficulty of retrieving the injury resulting to a well-organised business, from the accidental destruction of the machinery, are objects alone sufficient to furnish the strongest economical,as well as political recommendations, for the adoption of the new lights in all manufactories where work is done by candle-light.
[38]Since the preceding pages have been printed, I have seen aself-extinguishing gas-lamp, invented by Mr.Clegg. This lamp is so constructed, that the gas cannot flow to the burner, when the flame becomes extinguished. If, therefore, the lamp should be blown out, and the stop-cock which supplies the gas be left open, the extinction of the flame will effectually shut the valve. The action of this lamp depends upon the expansibility of a metallic rod, heated by the flame of the lamp, and thus keeping open the valve, whereas, when the lamp is extinguished, and the rod becomes cold, it contracts to its natural dimensions, and, by that means, effectually closes the valve. The same engineer has invented a machine, which both measures and registers, in the absence of the observer, the quantity of gas delivered by any pipe communicating with a gas-light main. The machine occupies a space of about two feet by one foot, and, if put up in a room, house, or other place, where gas is burnt, will, at any time, by mere inspection, give an account of the quantity of gas consumed in that place during any given time. On the present occasion, it would not become me to say more on these subjects, which, no doubt, Mr.Cleggwill make known to the public; I shall only remark, that these contrivances do signal honour to the talents and abilities of the inventor; and that they will render the greatest services to those who are engaged in the gas-light illumination.
[38]Since the preceding pages have been printed, I have seen aself-extinguishing gas-lamp, invented by Mr.Clegg. This lamp is so constructed, that the gas cannot flow to the burner, when the flame becomes extinguished. If, therefore, the lamp should be blown out, and the stop-cock which supplies the gas be left open, the extinction of the flame will effectually shut the valve. The action of this lamp depends upon the expansibility of a metallic rod, heated by the flame of the lamp, and thus keeping open the valve, whereas, when the lamp is extinguished, and the rod becomes cold, it contracts to its natural dimensions, and, by that means, effectually closes the valve. The same engineer has invented a machine, which both measures and registers, in the absence of the observer, the quantity of gas delivered by any pipe communicating with a gas-light main. The machine occupies a space of about two feet by one foot, and, if put up in a room, house, or other place, where gas is burnt, will, at any time, by mere inspection, give an account of the quantity of gas consumed in that place during any given time. On the present occasion, it would not become me to say more on these subjects, which, no doubt, Mr.Cleggwill make known to the public; I shall only remark, that these contrivances do signal honour to the talents and abilities of the inventor; and that they will render the greatest services to those who are engaged in the gas-light illumination.
After considering the facts so far detailed, many other advantages, connected with the gas-light illumination, will naturally suggest themselves to the reader. I have endeavoured merely to point out the leading characters of the new lights, as they are at present. Ingenious men may speculate from what has been done to what remains to be effected, which, no doubt, will embrace objects of the greatest utility and most extended national importance. The public attention is awakened to the new properties of coal, and will not rest till they are extensively applied to economical purposes. The consequence will be, a considerabledefalcation in the revenue. For, in proportion as the gas-lights are more or less generally adopted in all towns of the country, the consumption of oil and tallow will be diminished, and the impost on those articles become less productive; and when this takes place, Government, no doubt, will share in the profits, by levying a tax on the new lights. The Exchequer will thus have nothing to fear; as one branch of the revenue fails, another, and a more productive one, will supply its place.
Upon the whole, when we reflect that the object of the gas-light illumination is to open a source of national wealth, of which nothing can deprive us, to create, we may almost say, new articles of value, its friends cannot be thought guilty of great presumption, if they look forward with confidence to the successful extension of this new art of civil economy; and if, contrary to all expectations, the effects of jealousy and prejudice should, in some respect or other, continue here and there its influence against this new art of procuring light, a firm perseverance of its application must at length remove that ignorance which alone can give them birth.
EXHIBITING
The quantity ofGas,Coke,Tar,Pitch,Essential Oil, andAmmoniacal Liquor, obtainable from a given quantity ofCoal; together with an Estimate of the quantity of Coal necessary to produce a quantity of Gas, capable of yielding a Light equal in duration of time and intensity to that produced by Tallow Candles of different kinds.
[39]1000lb. of Coal-Tar afford by distillation, from 260 to 265lb. of Essential Oil, or Naphtha. 1000lb. of Coal-Tar produce by mere evaporation, from 460 to 480lb. of Pitch.
[39]1000lb. of Coal-Tar afford by distillation, from 260 to 265lb. of Essential Oil, or Naphtha. 1000lb. of Coal-Tar produce by mere evaporation, from 460 to 480lb. of Pitch.
Tabular View, exhibiting the illuminating power of Coal-Gas, compared with the illuminating power of Tallow Candles of different sizes.
N. B. If it be required to know, for how many hours one pound, or one peck, or one bushel, or one sack, of coal will produce Gas Light equal to that of a certain number of well-snuffed Tallow Candles, the proportion of each of the average weights of a pound, peck, bushel, or sack, to that of the average weight of a chaldron of coal, is as follows:
Rule.—Divide with either of the above parts of weight, the number of lights opposite to their hours, and the product will be the number of lights burning for the same number of hours.
Example.—To know how many lights one peck of coal will give for six hours, divide the 148th part in 3,500, opposite to the number of six hours, the product is almost 24 lights. The same rule holds good for any given quantity or number of pounds of coal, in a chaldron, to find how many lights, or candles, 12 to the lb. or 6 to the lb. they will give for a given number of hours.
Exhibits a perspective view of a gas-light apparatus,[40]for lighting factories, or small districts of houses. It consists of the following parts: which may be considered separately.
[40]This apparatus was erected by Mr.Clegg, and is now in action at Mr.Ackerman’s establishment, in this metropolis.
[40]This apparatus was erected by Mr.Clegg, and is now in action at Mr.Ackerman’s establishment, in this metropolis.
Fig.1.TheRetort Furnace, for distilling the coals. It is built of brick-work. The bricks which are exposed to the immediate action of the fire, areWelch tumps, or fire-bricks; they are bedded in clay, or Windsor loam.
Fig.2.TheTar Cistern, to collect the coal-tar, and other condensible products obtained during the distillation of the coals. It is a cast-iron hollow cylinder, closed at the top with a cast-iron cover, which has a very small hole to allow the air to escape as the liquid enters into the vessel.
Fig.3.TheLime Machine, for purifying the crude coal-gas, and to render it fit for use. The construction of this machine will be explained inplateVII. It is put together of cast-iron plates.
Fig.4.TheGasometer, for collecting and preserving the purified gas, and for distributing and applying it as occasion may require. It consists of two principal parts—namely, a large interior vessel closed at the top and open at the bottom, made of sheet iron, designed to contain the gas, and an outer cistern or vessel, of rather greater capacity, constructed of cast-iron plates, in which the former vessel is suspended. The latter contains the water by which the gas is confined. The interior vessel which contains the gas is suspended by chains hung over wheels or pullies, to which weights are attached, so as to be just sufficient to balance the weight of the gasometer, all but a small difference, and allowing its slow descent in the manner which is found as nearly adapted as can be to the proper supply of the lamps. The weight of the chains must be equal to the specific gravity of the material of which the gasometer is composed, so as to compensate accurately for the quantity of water which the gasometer displaces, or what is the same, it must be equal to the loss of weight which the gasometer sustains, when immersed in the water; and the counterpoise weight must be equal (or nearly so) to the absolute weight of the gasometer.
The action of these different parts of the apparatus will be obvious from the following explanation:
A,A, are two iron retorts, placed horizontally, and side by side, in the furnace; the mouth of theretorts where the coals are introduced, projects into an arched chamber, situated in front of the furnace, as shewn in the drawing by the broken down brick-work. The object of suffering the mouth of the retorts to project into a separate chamber, is merely to discharge with convenience the red hot coke from the retorts when the process is at an end; the coke being suffered to fall to the bottom of the chamber, where it cools, without becoming troublesome to the operator. It may be removed from this fire-safe chamber by the door represented at the end view of the furnace.
When the operation commences, the inner vessel of the gasometer,fig. 4is sunk down, to expel the air which it contains to a level with the exterior vessel, or outer cistern, of the gasometer; and, consequently, becomes filled with water. As the distillation of the coal in the retorts proceeds, the liquid and gazeous products evolved from the coals are transmitted by means of the perpendicular syphon pipesB,B, into the horizontal pipe or main condenserC, with which they are connected. The liquid which is distilled, collects in the pipe, or main condenser,C, where it is retained until its quantity has risen so high as to discharge itself into the pipeD, which is connected with the upper part of one of the extremities of the condenser,C. One of the extremities of the pipes,B,B, therefore become immersed into the liquid contained in the main condenser or pipeC, whilst the vaporous or condensible fluid, after having overcome the pressure there opposed to it, is transported into the pipeE, which, after passing in a serpentine direction,E,E,&c. through the exterior vessel or cistern of the gasometer, terminates in the tar-vessel,fig. 2. Thus the vaporous fluids are condensed by passing through the serpentine pipe,E,E, &c. and become deposited in the tar-cistern,fig. 2; whilst the non-condensible or gazeous products are made to proceed by the pipeF, which branches off from the pipeE, into the lime machine,fig. 3. In this apparatus the gas, as it is evolved from the coals, comes into contact with slaked lime and water; the object of which is, to strip it of its sulphuretted hydrogen and carbonic acid gas with which it always abounds, and to render it fit for illumination. This being accomplished, the purified gas is conducted away out of the lime machine by means of the pipeG, into the perpendicular pipeH, which branches up through the bottom of the gasometer cistern. The upper extremity of this pipe is covered, in the manner of a hood, by a cylindrical vesselI, open at bottom, but partially immersed beneath the surface of the water contained in the outer cistern of the gasometer, it is also perforated round near the lower edge with a number of small holes. The gas, as it passes out of the pipeH, displaces the water from the receiverI, and escapes through the small holes, and is thus made to pass through the water in the cistern, in which the hood of the pipeI, is partly immersed, so as to expose a large surface to its action, that it may once more be washed, and deprived of all the foreign gazeous products which might have escaped the action of the lime, whilst it was agitatedwith this substance in the lime machine,fig. 3. After rising through the water in the gasometer cistern, it enters into the gasometer, which then ascends as the gas accumulates in it.
In this manner the process proceeds, until the whole of the volatile products of the coal in the retort are disengaged. The use of the gasometer is, partly to equalize the evolution of the gas which comes from the retort more quickly at some time than others. When this happens, the vessel rises up to receive it, and when the stream from the retort diminishes, the weight of the gasometer expels its contents, provided the main-cock be open. When the process is finished, the retort is suffered to cool, and its lid is then removed to replenish it with coal. When the main stop-cock is then opened, the gasometer descends, and the gas passes from the gasometer through the pipeK, to the burners, or main pipe, which communicates with the gas burners or lamps.L, is a wooden tub or barrel, containing the mixture of lime and water, for charging the lime machine; and into which the contents of the barrel,L, may be conveyed by the curved pipeM, without admitting common air.N,N, is a water-pipe, to convey fresh water into the gasometer cistern occasionally; because it is essential that the water used for washing and purifying the gas should be changed for fresh as soon as it becomes dirty; and unless this is done, the gas will not be perfectly purified by washing, but produce a disagreeable odour when burnt; the same holds good with regard to the limemachine, the contents of which should be renewed occasionally. This pipe also conveys the necessary water into the barrel,L.O, is a waste-pipe, to convey the water as it becomes impregnated with the impurities of the gas, out of the gasometer cistern.P, is an agitator, to stir up the contents of the lime machine occasionally,Q,Q, are two iron rods, which serve as stays to guide the motion of the gasometer.R, is an index, connected by means of a shaft and pulley with the axis of one of the gasometer wheels. This index is graduated to the capacity of the cubical contents of the gasometer, so as to indicate, by the rising and falling of the gasometer, its relative contents of gas expressed in cubic feet.S, is the waste pipe of the lime machine, to remove the insoluble parts of the lime.T, represents the iron cover, or lid, which is turned on the lathe, and ground air-tight, to close up the mouth of the retort, so as to make readily an air-tight fitting.Uis an iron wedge to secure the cover of the retort. The left-hand retort in the design shows the retort closed up, and the cover, or lid of the mouth of it secured by means of the wedge, in its place, so as to render the mouth of the retort perfectly air tight.
There is a safety valve attached to this gasometer which could not be represented in the drawing; and the object of which is, to convey away any portion of gas that might happen to be produced by a careless operator, when the gasometer is full, and which is thus prevented from accumulating in the place where the gasometer is erected. It is represented inthe right-hand corner ofplate VII.where fig. 1 shows the edge of the gasometer; 2, the surface of the water in the inside of the gasometer; 3, the surface of the water in the outside of the gasometer, or in the cistern; 4, a pipe issuing from the lower edge of the gasometer, and surrounded at its upper extremity with a cup marked 5; 6, the waste pipe, the mouth of which is immersed in water. It is obvious that, when the gasometer is full, if an additional quantity of gas should be attempted to be put into it, it will be transported by means of the pipe 4, into the waste-pipe 6; the upper extremity of which reaches out of the building, and there communicates with the open air.
Represents a Portable experimental Gas Apparatus for exhibiting, in the small way, the general nature of the gas-light illumination.—It is describedpage 79.
Show designs of various kinds of Gas Lamps, Chandeliers, Candelabras, &c.—Seepages 114,118,140.
Fig.1.Exhibits a design of thegasometer framing, orskeleton, which serves to give stability and strength to the gasometer. It consists of wooden frame work, markedA,A,A, interlacedwith iron rods,B,B,B, &c. The whole framing is so disposed that it will float in the cistern horizontally, and therefore keep the gasometer perfectly steady and level with the surface of the water.
The rest of the sketches represent various kinds of gas pipes employed asmainsfor conveying the gas, and the methods of connecting them.
Fig.2.Represents a longitudinal section of aSpigotandFaucet Pipe. These kinds of pipes are applicable in most cases as mains for conveying gas.A, is called the spigot, andB, the faucet. They are joined together, and made air tight, by iron cement, the composition of which is as follows:
Take two ounces of sal ammoniac, one ounce of flowers of sulphur, and sixteen ounces of cast iron filings or borings. Mix all well together, by rubbing them in a mortar, and keep the powder dry.
When the cement is wanted for use, take one part of the above powder, and twenty parts of clean iron borings or filings, and blend them intimately by grinding them in a mortar. Wet the compound with water, and when brought to a convenient consistence, apply it to the joints with a wooden or blunt iron spatula.
By a play of affinities, which those who are at all acquainted with chemistry will be at no loss to comprehend, a degree of action and re-action takes place among the ingredients, and between them and the iron surfaces, which at last causes the whole to unite as one mass. In fact, after a time, the mixture and the surfaces of the flanches become a species of pyrites (holding a very largeproportion of iron,) all the parts of which cohere strongly together.
The inner parts of the faucet ought to be no larger in diameter than just to fit the spigot. This supports the pipe, independently of the cement, and prevents the risk of hurting the joint from any external stress. The inner faucet is commonly made about 21⁄2inches deep, and has the spigot inserted 11⁄2inch into it. The practice of some workmen, is to make the outer faucet, or that which contains the cement, six inches deep, for all pipes above six inches diameter; and to make the faucets of all pipes below six inches, the same depth as the diameter of the pipes. It is usual to make the space for the cement, all round the spigot, from 1 to 11⁄2inch; that width is required, in order that the cement may be firmly driven into the joint. When the space is very narrow, this cannot be done. On the other hand, when too wide, there is a waste of cement, and a risk of injury from unequal expansion.
Fig.3.Exhibits a profile view of these kinds of pipes when joined together. The spigot and faucet pipes are liable to burst from the great expansion of the spigot, and the risk of this accident is increased by increasing the space between the spigot and faucet, which requires to be filled with cement.
Fig.4.Represents a longitudinal section of two flanch pipes, and the modes of connecting them.AandB, show the parts of the pipes; andCandD, the flanches. These pipes are also joined together, and rendered air-tight, by interposing betweenthe flanches rope-yarn, hemp, or some other pliable material, and iron cement, and then screwing up the faces of them by means of the bolts and screw nuts.
Fig.5.Profile view of the same kind of pipes connected together,AandB, the pipes;CandD, the flanches;EandF, the bolts.
Fig.6.Represents the method of joining spigot and faucet pipes when they are to have a turn or angle. This method is convenient when the place where the turn required to be made is previously known, and the pipes cast accordingly.
Fig.7.Exhibits the method of connecting spigot and faucet pipes when they have a round turn.AandB, the junctures of the pipes.
Fig.8.Represents a longitudinal section of the mode of joining pipes by means of what is called athimble joint. The junctures of the pipes to be connected, are made air tight, as mentioned already, by iron cement.A, the thimble or small cylinder, with projecting edges, which unites the pipesB,C.
Fig.9.A thimble joint made in two parts, which is sometimes convenient to join pipes. The parts are joined together by screw bolts, and nuts, in the usual manner.
Fig.10.Section of the same.
Fig.11.Represents a profile view of what is called thesaddle joint. It is employed for taking off a branch-pipe. The branch has a pieceAB, formed on its end, and fits round one-half of the outside of the pipe from which it is to proceed.C, is called the saddle, which fits round the other half of the pipe. The parts are secured togetherby screw bolts, and iron cement. By this method a branch may be formed on any part of a gas-pipe, by cutting a hole there, and applying the branch to that place. Where there is much risk of the inequality of expansion, the joints at certain places, should be secured by a soft stuffing of hemp and tallow; but in most cases the joints may be made with iron cement. Lead is frequently used for making the joints of gas pipes instead of iron cement, though cheaper and more easy of repair. The galvanic action which takes place between the lead and iron, soon renders the joints leaky, and the danger is increased by the unequal expansion of the two metals.
Fig.12.Section of the saddle-joint.
Before the gas is suffered to enter into the pipe, they should be proved to be sound, by the usual process of forcing water into them: The pipes serving as mains, are placed perfectly solid, so that they cannot give way; their course should be rectilinear, having a descent of about 1 inch in 9 or 10 feet, to allow the water of condensation which may be deposited from the gas by a change of temperature to collect readily at the lowermost part.
Fig.13.Shows a reservoir for collecting the water of condensation which might accumulate in the pipes. It consists of a receptacle,A, in which the water may pass;B, a branch-pipe closed at the top, by means of which the water may be removed, by drawing it out with a syringe. This receptacle is placed in those situations where pipes incline towards each other.
Exhibits a perpendicular section of a gas-light apparatus, calculated for lighting towns, or large districts of streets and houses.
Fig.1.The Retort Furnace. The retorts are placed over each other in one or more rows; so that a certain number of them may be heated by separate fire-places.A,A,shows two of the retorts placed horizontally above each other;B, the fire-place;C, the flue which causes the fire to circulate round the retorts so as to heat them equally in every part;D, the opening of the flue where the fire passes into the chimney;E, the ash-pit;F, a chamber in front of the retort furnace, into which the orifice or mouth of the retorts project;G,G, the doors of the chamber, to enable the workmen to charge and discharge the retorts;H, a funnel shaped hole at the floor of the chamberF, through which the red hot coke as it is discharged from the retorts passes into the arched vaultI;K, the syphon tube;L, the horizontal condenser[41]—the action of both of these pipes have been already explained,p. 168;M, main pipe, which conveys the liquid substances from the condenser, to the tar cistern,fig. 3, andwhich conducts also the gazeous products into the lime machine,fig. 2;NN, shows that part of the pipe which is interposed between the tar cistern,fig. 3, and the condensing pipeM,—it passes in a serpentine direction along the inner sides of the gasometer cistern, and, like the so-calledwormin a distillatory apparatus, condenses the products which escape in a vaporous state from the condenserL;O, shows the place where the serpentine pipeNN, passes again out of the gasometer cistern, and its communication with the lime machine,fig. 2, and tar chamber,fig. 3. The action of the lime machine is as follows: The liquid products evolved from the coal, having been deposited in the tar cistern,fig. 3, by means of the serpentine pipeN,N, the gazeous products which accompany it, are conveyed by means of the pipeP, which branches out from the pipeO, into the interior receptacle of the lime machine markedQ, which consists of a vessel open at the bottom, and closed at the top, where it communicates with the pipeO. As the gas accumulates in the interior partQ, of the lime machine, it is made to pass through the liquid which it contains, namely, slaked lime and water; and escapes through appertures made in the horizontal partitionsR,R,R,R, into the outer vessel,S, of the lime machine and from thence it is conducted away by the pipeT,T,T, into the additional washing apparatus, of the gasometer;fig. 4, the construction of this apparatus, greatly resembles the lime machine,fig. 2, namely,V, is a water pipe, proceeding from a cisternU, placed 3 or 4 feet above the orifice of the pipeV;T,T, is the gas-pipe,covered with a hood, markedW, and immersed in a small cistern, having horizontal perforated shelves, like those in the lime machine—they fit close to the hood. The gas which enters the hoodW, meets with a shower of water delivered by the pipeV. The gas, as it passes through the holes in the horizontal partitions, is, therefore, again washed and thoroughly purified from foreign gases which may have escaped the action of the lime machine;Y, is a waste pipe, the lower extremity of which is sealed by being immersed in water,—it serves to carry away the water delivered by the pipeV, as it has been acted on by the gas. The summary action of this gas apparatus is, therefore, as follows: The liquid products obtained from the coal during the distillation are first deposited in the main condenserL, by means of the pipeK, and from whence they cannot escape until a quantity of tar has accumulated in it to a certain height, and by this means, one of the extremities of the pipesK,K, becomes immersed and hermetically sealed by the liquid which the condenserL, contains. The liquid products, after having accumulated to a certain height in the condenser, overflow the perpendicular portion which it contains, and discharge themselves into the pipeM, from whence they are transported into the tar cistern,fig. 3, by means of the system of pipesN,N,O, whilst the gazeous products are made to pass by means of the branch pipeP, into the lime machine,fig. 2. From this part of the apparatus the gas passes through the pipeT,T,T, into the additional or smaller washing apparatus placed upon a tressel in the cistern of thegasometer, where it is again exposed a second time to the action of a current of fresh water; and from this vessel the gas ascends into the gasometer. The gasometer is furnished with a pipeA, closed at the top, and fixed in one corner of the gasometer, but open at the bottom; it includes another pipe markedB, which communicates with the main pipe leading to the burners, or place where the gas is wanted. The pipeA, which slides over the pipeB, is perforated at the top, the gas passes through these perforations and is thus made to enter into the pipeB, and disposed of as mentioned.C,C, is a tube of safety adapted to the gasometer; its lower extremity remains sealed by the water in the cistern so long as the gasometer is not overcharged with gas; but, if more gas should be made to enter the gasometer than it is destined to receive, this pipe then delivers the gas into the funnel-shaped tubeD, which reaches through the roof of the gasometer house, and thus the superfluous quantity of gas is conveyed away into the open air.