Chapter VII: Part II: Gas-Light (3)

If the coal-tar is wanted to be converted into pitch, without obtaining the oil which it is capable of furnishing, the evaporation of it may be performed in a common boiler; but as it is extremely liable to boil over, the greatest precaution is necessary in conducting the evaporation. A boiler constructed on the following plan is very convenient for the conversion of coal-tar into pitch. The contrivance consists in adding a spout, or rim, to the common boiler, into which the tar spreads itself as it rises, and by this means becomes cooled, and the boiling over is checked.

1000lb. of coal-tar produce, upon an average, from 460 to 480lb. of pitch. A subsequent fusion, with a gentle heat, converts the coal-pitch into a substance possessing all the characters of _asphaltum_.

_Ammoniacal Fluid._--The properties of the ammoniacal liquor, which accompanies the tar, and which is deposited in the tar-cistern, has not yet been fully investigated. It is employed already in the manufacture of muriate of ammonia (sal ammoniac). One chaldron of coal affords from 220 to 240lb. of this ammoniacal fluid, which is composed chiefly of sulphate, and carbonate of ammonia.--Such are the products obtainable from coal.

However certain the practicability of extending the new lights to the dwelling houses of every town and village is, it cannot be expected that such an event should take place speedily and generally. To eradicate prejudice, and to alter established habits, is a work which nothing but time can effect; because prejudice is the effect of habit, and can seldom be eradicated from the minds of such individuals as consider the ready occurrence of a proposition as a test of its truth. To establish a new philosophical theory has, in every instance, required time sufficient to educate an entire generation of men. The rejection of the Aristotelian philosophy--the adoption of experimental research--the substitution of the doctrine of gravitation instead of that of vortices, and the rejection of phlogiston by modern chemists, are sufficiently illustrative of this assertion. New arts, and new practices, are still more difficult to be introduced. The new art of bleaching need merely be mentioned to prove this assertion. The new grammar--the new rudiments of science--the new stile--or the new instrument, however superior to the old in simplicity, facility, and truth, must be less valuable to the ordinary teacher or artisan, whose memory is familiarized with the precepts of the latter, and whose only ambition is to earn his subsistence with the least possible exertion.

The slowness with which improvements of every kind, make their way into common use, and especially such discoveries as are most calculated to be of an extended or general utility is very remarkable, and forms a striking contrast to the extreme avidity with which those unmeaning changes are adopted, which folly and caprice are continually sending forth into the world under the auspices of _fashion_.

On the first view of the subject it appears very extraordinary, that any person should neglect, or refuse to avail himself of a proposed invention, or improvement, which is evidently calculated to economise his labour, and to encrease his comforts; but when we reflect on the power of habit, and consider how difficult it is for a person even to perceive the disadvantages or imperfections of former modes to which he has been accustomed from his early youth, our surprize will be diminished, or vanish altogether.

Many other circumstances, besides prejudice, are unfavourable to the introduction of new and useful discoveries. Among these jealousy, malice, envy, and revenge, have too often their share in obstructing the progress of real improvement, and in preventing the adoption of plans evidently calculated to promote the public good.

A plan like the present, which proposes not only to trench upon domestic habits, but to give an entire new direction to a portion of the skill and capital of the country, must necessarily encounter the most strenuous opposition. It is thus that some individuals have mustered all their strength against the introduction of this new art. An endeavour has been made to move the public opinion by dismal forebodings of the Greenland trade, and the subsequent loss of a nursery of British seamen. This objection is nothing more than the common clamour that is always set up against every new means of abridging labour, to which had the public listened, an interdict would have been laid upon the spinning and threshing machines, the steam engine, and a thousand other improvements in machinery.

Indeed such clamour scarcely ever fails to be made when the extension of machinery and the abridgement of labour or the application of inanimate powers are considered. On such occasions, it is stated by certain humane but mistaken objectors, that the scheme of mechanical and chemical improvement is pointed against the human species--that it tends to drive them out of the system of beneficial employment--that the introduction of machinery is injurious to the labouring class of society, by abridging their work. Two creatures offer themselves for employment and support--a man and a horse. I must invariably prefer the latter, and leave the former to starve. Two other beings--a horse and a steam-engine, are candidates for my favour. My preference to the latter tends to exterminate the species of the former. In both cases it is stated, that the number of intelligent creatures capable of the enjoyment of happiness must be diminished for want of support; and that, on the whole, the sum of the proposed improvement is not only a less proportion of good to society, but a positive accession of misery to the unemployed poor.

On this wide and extended argument, which can in fact be maintained against all improvements whatever in no other way than by insisting that the savage state of man, with all its wants, its ignorance, its ferocity, and its privations, is preferable to the social intercourse of effort and division of labour we are habituated to prefer, it may be sufficient to observe that it includes matter not only for reasoning and induction, but also for experiment. By reference to the matter of fact, though it must be allowed that new improvements, which change the habits of the poor, must at first expose them to a temporary inconvenience and distress, against which, in fairness, it is the duty of society to defend them; yet the invariable result of such improvements is always to better the condition of mankind. A temporary inconvenience to individuals must often be incurred for the sake of general national benefit.

It is to manufactories carried on by machinery and to the abridgment of labour, that this country is indebted for her riches, her independence and pre-eminent station among the nations of the world.

But let us return to the subject.--The progress of the new mode of lighting with coal-gas can never wholly supersede the use of candles and moveable lights. The objection with regard to the Greenland trade is equally futile. This traffic, might with more propriety be called a drain, than a nursery, of the naval force. The nature of the Greenland service requires that the crew should consist chiefly of able-bodied sailors; and being protected men, not subject to the impress law, they are thus rendered useless for national defence. The nursery of British seamen is the coasting trade; and if the gas-light illumination be put in practice to a large extent, it will increase that trade as much as it will diminish the Greenland fishery.

Even on the extreme supposition that it would annihilate the Greenland fisheries altogether, we should have no reason to regret the event. The soundest principles of political economy must condemn the practice of fitting out vessels to navigate the polar seas for oil, if we can extract a superior material for procuring light at a cheaper rate from the produce of our own soil.

Indeed the fisheries will find ample encouragement, and the consequence of lighting our streets with gas can prove injurious only to our continental friends, one of whose staple commodities, tallow, we shall then have less occasion to purchase.

There will be less waste indeed, but a greater consumption of coal. The lower classes of the community are at present very scantily supplied with firing; and nothing but a reduction of price is necessary to increase to a very large amount the whole average quantity of fuel consumed in the country. The lightness of the coke produced in the gas-light manufacture diminishing the expence of land carriage, will facilitate its general diffusion--the comforts of the poor will be materially augmented, and a number of useful operations in agriculture and the arts be carried on, which are now checked and impeded by the price of fuel.

If any additional want were wanted for the coke it will readily be found in the continental market; coke being much better suited than coal to the habits of most European nations.

The gas-light illumination cannot tend to diminish the coal-trade; on the contrary it will prove beneficial to it; it will contribute to lower the price of the superior kinds of coal, and keep a level which cannot be shaken under any circumstances; it will contribute to prevent combinations which do certainly operate to the prejudice of the public, and do sometimes put this great town at the mercy of particular proprietors in the north, who deal out coal in the way they please. The competition thus produced, it is impossible not to consider as an advantage, which would prevent in future such combinations, and put those in London out of the reach of them.

It is worthy observation, that the annual importation of coal into this Metropolis, is above one million and eighty-eight thousand chaldrons.[31]

[31] To give an idea how long there is a probability of Great Britain
being applied with coal from the rivers Tyne and Wear only, it must be
observed,

_1st_. That the Seams of coal which are now worked at Newcastle and
Sunderland, are equal to a seam or bed of 15 miles by 20 miles.

_2dly_. That this seam, on an average, is at least four feet and a
half thick.

_3dly_, That 1-6th part of the above extent is sufficient for pillars
to support the roofs of the mines, &c.

And, _4thly_, It appears, by experiments, that a cubic yard of coal
weighs 1 ton, or 20 cwt.

London Chaldrons

The total consumption of coal from the rivers Tyne
and Wear known from the register to be 2,300,000

The number of tons in the above quantity taking the
London chaldron at 27 cwt. is 3,100,000

Now a ton weight of coal is estimated to occupy in
the earth the space of one cubic yard.

The number of cubic yards in the square mile is 3,097,600

The beds or seams of coal are, on an average, 4
feet and a half in thickness, which increases the
above number of cubic yards in the square mile by
half the number of square yards to 1,548,800

And hence the square mile of the beds or seams of
coal we are describing contains, of cubic yards
and tons of coal 4,645,000

A deduction of 1-6th for pillars to support the
mine, &c. 800,000

The number of tons per square mile 5,445,000

We have already mentioned the length and breadth of the seams of coal
to be equal to 20 miles by 15, making an area of 300 square miles, and
consequently a source of consumption for 375 years.

It may be objected to the universality of our conclusion, that the price of coals, differing very much in different places, will occasion a variation in the expence of the new mode of illumination. But there are two reasons why this should have less place, because we find, in Mr. Murdoch’s statement, page 69, that of 600l. the estimated yearly expence of lighting the cotton mill, 550l. consist of interest of capital, and tear and wear of apparatus, leaving the cost of coal only 50l. a sum so trifling, when we reflect that it replaces 2000l. worth of candles, that the price of coal, even where it is highest, can but slightly affect the general profits.[32]

[32] See, also, Mr. Ackermann’s statement, page 71.

_2dly_, The coal, by yielding the gas and other products,--namely, tar, pitch, ammoniacal liquor, &c. of which we have treated already, is converted into a substance, increased in bulk, and in the power of producing heat, namely, coke; and as a manufactory generally requires heating as well as lighting, there will be a gain both ways. The manufacturer, by distilling his coal, instead of burning it as it comes from the pit, will save his candles and improve his fuel. One effort at the outset, in erecting a proper apparatus, will reduce his annual disbursement, for these two articles of prime necessity, much in the same manner, (though in a far greater degree) as the farmer gains by building a thrashing machine and laying aside the use of the flail.

The principal expence in the pursuit of this branch of civil and domestic economy is therefore the dead capital employed in erecting the machinery destined for preparing and conveying the gas; the floating or live capital is comparatively small. At the same time, were we to offer an advice to the public on this subject, it would be, that no private individual resident in London should attempt to light his premises for the sake of economy with coal-gas by means of his own apparatus, whose annual expence for light does not exceed 60l. because the expence of erecting and attending a small apparatus is almost as great as one constructed on a larger scale would be. For if the quantity of gas wanted is not sufficient to keep the retorts continually in a red-hot or working state, the cost of the gas will be considerably enhanced; because either the empty retorts must be continued red-hot, or the fire must be suffered to go out; and the retorts, when cold, cannot be brought to a working state, that is to say, be made red hot again, but at a considerable expence of fuel, which must be wasted to no purpose. Whereas, if the retorts are constantly kept red hot and in action, one half of the coal necessary to produce a given quantity of gas will then be saved. But when a street, or a small neighbourhood is wanted to be lighted, and the retorts can always be kept in a working state, that is to say, red hot, the operation may be commenced with safety; because the sum required for erecting the apparatus, and the labour attending it, together with the interest of money sunk, will then soon be liquidated by the light which it will afford.

Individuals, therefore, may engage in the distillation of coal, and trade with advantage in the articles produced by that process, and the lighting of cities may be accomplished without the aid of incorporated bodies; and parishes may be lighted by almost as many individuals as there are streets in a parish.

From experiments, made by Mr. CLEGG, on the effects produced by a number of gas-lights, of a certain intensity, there is reason to believe that the streets of small towns might be illuminated at a cheaper rate, by means of a tower, or pagoda, furnished with gas-lamps, than can be done in the ordinary way by street lamps: the gas being conducted to the top of the building from the apparatus below, and the light directed down again, upon the objects to be illuminated, by means of reflectors placed at a certain angle. By this contrivance, all the main pipes which convey the gas through the streets, as well as those collateral ones that branch out from them to the street lamps, would be saved, and thus compensate for the expense of the tower.

The most beneficial application of gas-lights unquestionably is in all those situations where a great quantity of light is wanted in a small place: and where light is required to be most diffused, the advantages of this mode of illumination are the least.--Hence, as already stated, the lighting of the parish, or street-lamps only, without lighting shops or houses, can never be accomplished with economy.

We have noticed before the reason why the price of coals can have little effect upon the gas-light; because the very refuse, or small coals, called slack, which pass through the screen at the pit’s mouth, and which cannot be brought into the market--nay, even the sweepings of the pit, which are thrown away, may be employed for the production of coal-gas. It makes no difference in what form the coal is used, and this circumstance may contribute to enable the coal-merchant to furnish coals in larger masses, and as they come from the mine, instead of increasing the bulk by breaking them into a smaller size,[33] which is a practice commonly adhered to. This unquestionably reduces the value of coals; because the quantity of radiant heat generated in the combustion of a given quantity of any kind of fuel depends much upon the management of the fire, or upon the manner in which the fuel is consumed. When the fire burns bright, much radiant heat will be sent off from it; but when it is smothered up, very little will be generated: most of the heat produced will then be expended in giving elasticity to a thick dense vapour, or smoke, which is seen rising from the fire; and the combustion being very incomplete, the carburetted hidrogen gas of the coal being driven up the chimney without being inflamed, the fuel is wasted to little purpose.

[33] It is not generally apprehended, how very wasteful the use of
small coals is in the ordinary open fire-grates. Necessity makes us
use the poker very much, particularly, when the coals are small; and
habit prevails even when they are large. By the constant stirring of
the fire almost the whole of the small coal passes through the bars;
and consequently a great deal goes to the dust-hole without being
burnt at all. To prove this, we need only take a shovel full of ashes
and put them into a pail, and then pouring water over them, which
being gently run off, will carry away nearly all the light and burnt
parts: and leave an astonishing quantity of bright unburnt coal, which
has escaped from the fire-place, in consequence of being small.

When the grate of the fire-place is large, and the small coals are
thrown behind; or when we can have patience enough to bear the cold
for an hour or two, or contrive to have the fire lighted a long time
before we want it, the small coal may be of some use, but the fire
made with it is never strong, nor so bright; and does not burn so long
as a fire made with large or round coals: it often requires the help
of the poker, and produces a great quantity of breeze.

The loss in the use of small coals is more considerable to the poor,
who cannot keep large fires. When they want their breakfast or dinner,
the time they can spare is limited; and to have their water sooner
boiling, or their meals quicker ready; they must make use of the
poker, and lose a great deal of coal. This fact is so evident, that
any body who wishes to make the experiment before recommended, will
find that much more bright coal goes to the dust-hole of the poor man,
than to the dust-hole of a rich family, where, the fire-place being
large, the small coal has more chance of burning.

The loss is still greater to the poor, in consequence of the inferior
sorts of coal which are sold to them. If it is the light sort, it
burns too quick, and they consume double the quantity; if the strong
sort, it burns too slow, and is nearly as wasteful; for a great
quantity of it then goes to the dust-hole without having been lighted
at all.

An incorrect opinion is often entertained, that the real quantity of
coal contained in a sack is lessened by separating or screening the
small from the round coals; but we must recollect, that any compact
body occupies less space than is required to contain the same matter,
reduced to smaller irregular pieces, or to powder.--Now the screening
only takes away the finest dusty part of the coals, and admits more
small pieces of round coals to be filled into the sack.

Nothing can be more perfectly devoid of common sense, and wasteful and slovenly at the same time, than the manner in which chimney fires, where coals are burnt, are commonly managed by servants. They throw on a load of (perhaps all small) coals at once, through which the flame is hours in making its way; and frequently it is not without much care and trouble that the fire is prevented from going quite out. During this time no heat is communicated to the room; and, what is still worse, the throat of the chimney being occupied merely by a heavy dense vapour, not possessed of any heating power, and, consequently, not having much elasticity, the warm air of the room finds less difficulty in forcing its way up the chimney and escaping, than when the fire burns bright, and the coal-gas is ignited. And it happens not unfrequently, especially in chimnies and fire-places ill-constructed, that this current of warm air from the room which presses into the chimney, crossing upon the current of heavy smoke and aqueous vapour which escapes slowly from the fire, obstructs it in its ascent, and beats it back into the room. Hence it is that chimnies so often smoke when too large a quantity of fresh coals is put upon the fire. So many coals should never be put on the fire at once as to prevent the free passage of the flame between them, or to prevent them becoming quickly heated, so as to give out the carburetted hidrogen gas which they are capable of furnishing, and to cause it to be inflamed, In short, a fire should never be smothered: and when attention is paid to the quantity of coals put on, there is little use for the poker; and this circumstance will contribute much to cleanliness, and the preservation of furniture.

The author of a paper in the Plain Dealer asserts, that, of the various perversions of abilities, there is none that makes a human being more ridiculous, than that of attempting to stir a fire without judgment; to prevent which he lays down the following rules:--1. Stirring of a fire is of use, because it makes a hollow where, the air being rarefied by the adjacent heat, the surrounding air rushes into this hollow, and gives life and support to the fire, and carries the flame with it. 2. Never stir a fire when fresh coals are laid on, particularly when they are very small, because they immediately fall into the hollow place, and therefore ruin the fire. 3. Always keep the bottom bars clear. 4. Never begin to stir the fire at the top, unless when the bottom is quite clear, and the top only wants breaking.

There is one subject more on which it is necessary to speak.--In the present instance, the public has been alarmed by representations that the general adoption of gas-lights would expose us to innumerable accidents, from the inflammable nature of the gas, and the explosion of the apparatus in which it is prepared, or the bursting of the pipes by which it is conveyed. But there is no ground for such fears.

Those who are familiar with the subject will readily allow, that there is no more risk in the action of a gas-light machinery, properly constructed, than there is in the action of a steam-engine, built on just principles.

The manufacture of the coal-gas requires nothing more than what the most ignorant person, with a common degree of care and attention, is competent to perform. The heating of the gas-furnace, the charging of the retorts with coal, the closing them up air-tight, the keeping them red-hot, and discharging them again, are the only operations required in this art; and these, surely, demand no more skill than a few practical lessons can teach to the meanest capacity. The workman is not called upon to exercise his own judgment, because, when the fire is properly managed, the evolution of the gas goes on spontaneously, and without further care, till all the gas is extricated from the coal.

No part of the machinery is liable to be out of order,--there are no cocks to be turned, no valves to be regulated; nor can the operator derange the apparatus but by the most violent efforts. And when the stock of gas is prepared, we may depend on its lighting power as much as we depend on the light to be obtained from a certain number of candles or oil-lamps.

The diversified experiments which have been made by different individuals, unconnected with each other, have sufficiently established the perfect safety of the new lights; and numerous manufactories might be named in which the gas-lights have now been in use for upwards of seven years, where nothing like an accident has occurred, though the apparatus in all of them is entrusted to the most ignorant man.

It would be easy to state the causes which have given rise to some of those accidents that have spread alarm amongst the public; but of this it is not my business to speak at length. It is sufficient, on the present occasion, to state, that those melancholy occurrences which have happened at some gas-light establishments which I have had an opportunity of examining, were totally occasioned by egregious failures committed in the construction of the machinery. Thus, an explosion very lately took place in a manufactory lighted with coal-gas, in consequence of a large quantity of gas escaping into a building, where it mingled with common air, and was set on fire by the approach of a lighted candle. That such an accident could happen, is an evident proof that the machinery was erected by a bungler, unacquainted with the most essential principles of this art; because such an accident might have been effectually prevented, by adapting a waste pipe to the gasometer and gasometer house. By this means, if more gas had been prepared than the gasometer would contain, the superfluous quantity could never have accumulated, but would have been transported out of the building into the open air, in as an effectual manner as the waste-pipe of a water cistern conveys away the superfluous quantity of water, when the cistern is full. Such an expedient did not form part of the machinery.

Other instances might be named, where explosions have been occasioned through egregious mistakes having been committed in the erection of the gas-light machinery, were this a subject on which I meant to treat.

That the coal-gas, when mixed with a certain portion of common air, in close vessels, may be inflamed by the contact of a lighted body, as has been stated, page 98, is a fact sufficiently known. But the means of preventing such an occurrence in the common application of gas-lights, are so simple, easy, and effectual, that it would be ridiculous to dread danger where there is nothing to be apprehended. In speaking thus of the safety of the gas-light illumination, I do not mean to deny that no possible circumstances may occur where the coal-gas may be the cause of accident. It is certain that the gas, when suffered to accumulate in large quantities in close and confined places, where there is no current of air, such as in cellars, vaults, &c. and where it can mix with common air, and remain undisturbed, that it may be liable to take fire when approached by a lighted body; but I do not see how it is probable that such an accumulation of gas should take place in the apartments of dwelling houses. The constant current of air which passes continually through the rooms, is sufficient to prevent the possibility of such an accumulation ever to take place. And with regard to the bursting of the pipes which convey the gas, no accident can possibly happen from that quarter; because the gas which passes through the whole range of pipes sustains a pressure equal to the perpendicular weight of about one inch of water only, and such a weight of course is insufficient to burst iron pipes. Nor could the town when illuminated by gas-lights, be thrown suddenly into darkness, as has been asserted might happen by the fracture of a main pipe, supposing such an event should take place; because the lateral branches, which supply the street-lamps and houses, are supplied by more than one main; and the consequence of a fracture would be only an extinction of the few lamps in the immediate vicinity of the broken pipe, because the rest of the pipes, situated beyond the fracture, would continue to be supplied with gas from the other mains, as will become obvious from the sketch exhibited in the next page.

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._

The black lines represent 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 is passing through the main in the _Strand_, and which is also connected with the main in the _Haymarket_, _Piccadilly_, and _Coventry 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 in _Piccadilly_; in that case, the valve being shut on each side of the fracture, the gas would be supplied from the mains in the _Haymarket_ and _St. 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 the streets.[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 the sketch.

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 become deranged, 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 a
_self-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. CLEGG will 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 considerable defalcation 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.

TABULAR VIEW, EXHIBITING

The quantity of GAS, COKE, TAR, PITCH, ESSENTIAL OIL, and AMMONIACAL
LIQUOR, obtainable from a given quantity of COAL; 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.

-----------+------------------------------------------
| _Cost of Coal._
| Minimum. Maximum. Average.
-----------+------------------------------------------
One Chal. }|
of Coal, }| 40_s_ to 60_s_ -- 50_s_
from 25 to}|
28 cwt. }|
One Ton | 30_s_ to 48_s_ -- 38_s_ 6_d_
One Sack | 3_s_ 4_d_ to 5_s_ -- 4_s_ 2_d_
One Bushel | 1_s_ 2_d_ to 1_s_ 8_d_ -- 1_s_ 5_d_
One Peck | 3½ to 5_d_ -- 4¼
One Pound | ¼
-----------+------------------------------------------

-----------+-----------------------------------
| _Weight of Coal._
| Min. Max. Aver.
-----------+-----------------------------------
One Chal. }|
of Coal, }| 2,800 to 3,136 -- 2,968
from 25 to}|
28 cwt. }|
One Ton | 2,240
One Sack | 233 to 261 -- 247
One Bushel | 78 to 87 -- 82½
One Peck | 19½ to 21¼ -- 20¼
One Pound | 1
-----------+-----------------------------------

-----------+--------------------------------
|_Produce of Gas, in cubic feet._
| Min. Max. Aver.
-----------+--------------------------------
One Chal. }|
of Coal, }| 8,906 to 11,872 10,388[39]
from 25 to}|
28 cwt. }|
One Ton | 6,720 to 8,960 -- 7,840
One Sack | 741 to 988 -- 814
One Bushel | 247 to 330 -- 290
One Peck | 61 to 82 -- 71½
One Pound | 3 to 4 -- 3½
-----------+--------------------------------

-----------+-----------------------------------------
| } |_Candles._
| } |9,516 11 to the pound.
One Chal. }| }[39]Equal to |8,651 10 do.
of Coal, }| }as many tallow |7,786 9 do.
from 25 to}| }candles, 12 in |6,921 8 do.
28 cwt. }| }the pound, |6,556 7 do.
| }burning two |5,194 6 do.
One Ton | }hours; or to |4,325 5 do.
One Sack | } |3,463 4 do.
One Bushel | } |2,595 3 do.
One Peck | } |1,730 2 do.
One Pound | } | 866 1 do.
-----------+-----------------------------------------

COKE.--One chaldron of coal, from 25 to 28 cwt. gives 1¼ to 1½
chaldron of Coke.

TAR.--One chaldron of coal, from 25 to 28 cwt. gives from 150 to
180lb. of Tar,[39] or 15 to 18 ale gallons, 10lb. each.

AMMONIACAL LIQUOR.--One chaldron of coal, gives from 220 to 240lb. of
Ammoniacal Liquor, or 22 to 24 ale gallons.

[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._

One chaldron of Coal produces, according to weight and quality,
Cubic feet of Gas. Average. Burning. Candles. 12 to 1lb. 6 to 1lb.
From 9,000 to 12,000 10,500 1 hour = 21,000 = 10,500
----- ------ ------ 2 hours = 10,500 = 5,250
6,000 8,000 7,000 3 ditto = 7,000 = 3,500
4,500 6,000 5,250 4 ditto = 5,250 = 2,625
3,600 4,800 4,400 5 ditto = 4,400 = 2,200
3,000 4,000 3,500 6 ditto = 3,500 = 1,750
2,571 3,428 3,005 7 ditto = 3,005 = 1,502
2,250 3,000 2,625 8 ditto = 2,625 = 1,312
2,000 2,666 2,333 9 ditto = 2,333 = 1,166
1,800 2,100 2,100 10 ditto = 2,100 = 1,050
1,636 2,191 1,913 11 ditto = 1,913 = 956
1,500 2,000 1,750 12 ditto = 1,750 = 875
1,384 1,846 1,615 13 ditto = 1,615 = 807
1,285 1,714 1,499 14 ditto = 1,499 = 749
1,200 1,600 1,400 15 ditto = 1,400 = 700
1,125 1,500 1,312 16 ditto = 1,312 = 656
1,058 1,111 1,234 17 ditto = 1,234 = 617
1,000 1,333 1,166 18 ditto = 1,166 = 583
947 1,263 1,105 19 ditto = 1,105 = 552
900 1,200 1,050 20 ditto = 1,050 = 525
857 1,143 1,000 21 ditto = 1,000 = 500
818 1,095 956 22 ditto = 956 = 478
783 1,044 913 23 ditto = 913 = 456
750 1,000 875 21 ditto = 875 = 437

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:

1 lb. = 2968th part of a chaldron.
One peck 20 = 148th ditto.
One bushel 82 = 36th ditto.
One sack 248 = 12th ditto.

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.

DESCRIPTION OF THE GAS-LIGHT APPARATUS.

PLATE I.

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.

FIG. 1. The _Retort Furnace_, for distilling the coals. It is built of brick-work. The bricks which are exposed to the immediate action of the fire, are _Welch tumps_, or fire-bricks; they are bedded in clay, or Windsor loam.

FIG. 2. The _Tar 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. The _Lime Machine_, for purifying the crude coal-gas, and to render it fit for use. The construction of this machine will be explained in plate VII. It is put together of cast-iron plates.

FIG. 4. The _Gasometer_, 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 the retorts 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. 4 is 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 pipes B, B, into the horizontal pipe or main condenser C, 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 pipe D, 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 pipe C, whilst the vaporous or condensible fluid, after having overcome the pressure there opposed to it, is transported into the pipe E, 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 pipe F, which branches off from the pipe E, 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 pipe G, into the perpendicular pipe H, 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 vessel I, 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 pipe H, displaces the water from the receiver I, and escapes through the small holes, and is thus made to pass through the water in the cistern, in which the hood of the pipe I, 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 agitated with 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 pipe K, 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 pipe M, 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 lime machine, 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. U is 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 in the right-hand corner of plate 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.

PLATE II.

Represents a Portable experimental Gas Apparatus for exhibiting, in the small way, the general nature of the gas-light illumination.--It is described page 79.

PLATES III. IV. V.

Show designs of various kinds of Gas Lamps, Chandeliers, Candelabras, &c.--See pages 114, 118, 140.

PLATE VI.

FIG. 1. Exhibits a design of the _gasometer framing_, or _skeleton_, which serves to give stability and strength to the gasometer. It consists of wooden frame work, marked A, A, A, interlaced with 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 as _mains_ for conveying the gas, and the methods of connecting them.

FIG. 2. Represents a longitudinal section of a _Spigot_ and _Faucet Pipe_. These kinds of pipes are applicable in most cases as mains for conveying gas. A, is called the spigot, and B, 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.