Description of the Process of Manufacturing Coal Gas, for the Lighting of Streets Houses, and Public Buildings / With Elevations, Sections, and Plans of the Most Improved Sorts of Apparatus Now Employed at the Gas Works in London and the Principal Provincial Towns of Great Britain; Accompanied With Comparative Estimates, Exhibiting the Most Economical Mode of Procuring This Species of Light

by Friedrich Christian Accum

The quantity of gas obtained from any given quantity of coal, varies so much with the degree of heat applied, and the circumstances under which the decomposition of the coal is effected, that the solitary product of any one period of time can afford no positive criterion for the product of any other period. A correct general conclusion, in short, can only be drawn from the result of experiments carried on uninterruptedly through a succession of days and nights, and such a continuity of experiments could, previous to the invention of the gas metre, only be affected by means of two separate gas holders, one for measuring the gas as it is produced, and the other for receiving the gas after it is thus measured, in order to its being transferred into the mains. By the aid of a single gas holder, an admeasurement could obviously be effected only during the time the valves which transmit the gas into the street mains are shut, and this, when the days are short, as in the winter season, the most productive period of the whole year, is only about eight hours out of the twenty-four, leaving nearly two-thirds of each day, during which, no account could be taken of the quantity of gas produced at the works.

It deserves further to be observed, that when two gas holders are employed, the utmost that can be effected by them, is the admeasurement of the gas produced, while the distinguishing feature of the metre is, that it not only measures, but by its own action registers the quantity of gas produced, or expended, in any given time.

Nor does the whole merit of this machine, in an economical point of view, consist in its thus furnishing the manufacturer with an infallible criterion of the quantity of gas which ought at all times to be produced; for, in the second place, it enables him by the several experiments which have supplied that criterion, to ascertain at what least possible expenditure of fuel, and in what space of time the greatest possible quantity of gas can be produced.

The advantage of the gas metre, in these additional respects, will be sufficiently demonstrated by attending for a moment to the situation of the manufacturer of coal gas, when without any such protecting register. Suppose, for example, that the manufacturer desires to know whether his workmen have made during a given time, (say during the night), the quantity of gas which they ought to have produced from a given quantity of coal, or whether they have consumed no greater proportion of fuel for its production than was absolutely necessary. He may, upon examination, find all the retorts in an excellent working state, but whether they have been so during the whole of the night, or whether the requisite quantity of gas has been really produced during the time that the valves which convey the gas into the mains have been open, is to him a matter of uncertainty. The workman may, as has been too often the case, have neglected the fire during the night, and on every such occasion, in order to bring back again the retorts to a proper working state, as well as to redeem the time lost, he may have urged the heat to a degree of intensity much exceeding the temperature best suited for the most economical production of the gas. And however injurious such irregular modes of operating may be for the master’s interest they are altogether shrouded from his observation. It deserves also to be noticed that the loss occasioned by this irregularity of operating is not merely a loss of fuel, for in consequence of it the retorts, (particularly if cast-iron retorts of the usual forms,) are liable to more injury in one day than they would be during a whole week, if properly attended.

When the proprietor of the establishment, on the contrary, has recourse to the gas metre, not one of all these evils can occur without being liable to certain and instant detection. From the data which preceding experiments on the productiveness of the species of coal used at the establishment have furnished, the overseer of the works is always enabled to determine, from the portion of coal he finds used, how much gas ought to have been manufactured during any space of time that has elapsed, and also the portion of carbonizing fuel which was necessary for the production of that quantity of gas; and comparing these data with the quantity of gas which the index of the gas metre announces has been produced, he is enabled to determine by mere inspection, in an unerring manner, whether the workman has acted with that sedulous attention to his duty which the economy of the establishment demands.

The many important advantages in short which the manufacturer of coal gas derives from this machine, considered as a standard or check on the conduct of the workmen, may be summed up in this—that while, without the aid of the gas metre, no establishment can be possibly more exposed to suffer from the ignorance of managers or the want of fidelity in servants, than a gas manufactory, there is none which is more independent of either than a gas manufactory, possessed of this important apparatus. Nor can the amount of that possible loss be regarded as otherwise than extremely serious, when attention is paid to the difference in profit and loss between conducting the process of manufacturing coal gas on a system founded on the deductions of experience, and an assiduous attention to keeping up a regularly sustained temperature; and conducting the process on a system of random calculation and irregular working,—a difference, which as appears from the details already laid before the reader, amounts in respect to the quantity of gas produced, to from fifty to one hundred per cent.; in respect to the waste of machinery, to upwards of eighty per cent.; and in respect to the consumption of fuel and time to a sum in the ratio of the loss experienced under both these other heads.

The Second General Point of View in which the gas metre claims our attention, is, its excellence as a standard of fair dealing between the seller and consumer of gas, by enabling the former to supply the gas in whatever quantities it may be required, and serving, at the same time, as a self-acting register of the quantities furnished. It is for this purpose merely necessary to connect the gas metre with the pipe of supply, which conveys the gas to any burner, or number of burners, or lamps, and the index of the instrument will regularly announce the precise quantity of gas which has passed through the machine during any period of time, from one day to a number of years, without requiring any particular sort of care whatever. Every person must have noticed how shamefully many individuals disregard the terms on which they have contracted for a supply of gas, some by means of the excessive flame they keep up, and others suffering the lights to burn hours beyond the time stipulated and contracted with the gas light company which supplies them. The latter have officers, it is true, whose duty it is to check such abuses as far as is in their power, but having no right of access to the premises of individuals, their vigilance can only extend to shops and places open to public view and of general access; and to these, of course, but occasionally. In short in every place where gas is supplied on contracts to pay for burning it a limited time, by means of certain sized burners or lamps, instead of according to the quantity actually furnished, the seller must always be in a greater or less degree, and in some cases wholly dependent on the care and honesty of the purchaser for the protection of his commodity from waste and depredation. But when on the contrary the seller possesses, as he now does, by means of the gas metre, an infallible check of the exact quantity of gas consumed in a certain time, and the purchaser is bound to pay for as much as he uses, the former is relieved from every apprehension or chance of being defrauded, and the latter is furnished with the same motives for economizing gas as he would have for economizing oil and candles.

The manufacturer is certain of obtaining what he has a just right to, value for the whole quantity of gas supplied, and the consumer is assured that if he wastes the gas unnecessarily, he must as he ought, pay the price of his own carelessness or profusion. Equal justice is done both to the consumer and seller, and the public at large are at the same time most materially benefited, in as much as they are saved from paying for the expence of that waste of gas by a few, which from the former impossibility of tracing it to the offending parties, was necessarily added to the whole cost of the gas, and equally partitioned upon all the individuals who made use of it. The waste being now transferred to those who occasioning the waste and ought alone in justice to bear it, the price of the gas to the equitable and honest consumer, is thus reduced to an equitable and correct measure of value.

The benefits of this invention have a yet wider range; not only does it secure full value for the whole of the gas manufactured, but it tends to make the gas a greatly more marketable article. For in the system of charging for the supply of gas by the year, half year, or quarter, and at one common rate, many individuals who are only occasionally in want of gas lights, or whose demand is irregular and uncertain, such as the proprietors of public rooms, theatres, &c. are debarred of availing themselves of this kind of illumination, except at an expence quite disproportioned to what other more regular customers pay, and out of all proportion of the value of the quantity of gas consumed by them. The gas light under such circumstances is not as it ought to be, a light for all. It is not as oil and candle are, a benefit which every one may obtain who is in need of it, and in such quantities as may best suit his means and convenience. One of the capital advantages, of the gas metre, however, is, that it makes gas a substitute for oil and candles, applicable under all circumstances, and that it enables the manufacturer without the least prejudice or chance of prejudice to his interest, to supply gas in whatever quantities it may be demanded, and at a fair proportioned price.

In speaking thus of the influence which the gas metre must have in attending the beneficial application of the new lights, we are not unaware that situations may present itself where the action of the metre might be impeded from the want of a sufficient pressure of the gas in the pipe of supply connected with it. But this can never be the case except where the pressure of the gas in the pipe of supply is so low as three-eighths of an inch of a column of water, and in all such cases it is only necessary to give a greater capacity to the wheel of the machine, than would be necessary under other circumstances, and this will at once make up for the inferiority of pressure. In point of fact, therefore, no situation can occur, where the application of the machine may not be rendered available.[46]