even more, the quantity varying according to the quality of the gas. By this combination, which in fact constiutes combustion, watery vapour and carbonic acid are formed, the former being composed of all the hydrogen of the gas, with 8 times its weight of oxygen, the latter consisting of all the charcoal, united with oxygen, in the proportion of 6 to 16 by weight. These products, which are similar to those from a candle or lamp, mingle with the air of the apartment, and are removed with it in the course of ordinary ventilation. In some circumstances, the watery vapour is condensed on the windows; and in street lamps it may be seen, when the weather is cold, bedewing the inside of the globes, and even collecting in considerable quantity at the bottom.

The carbonic acid is not removed in the same manner by condensation, and it may accumulate to a hurtful extent; this can only happen, however, where ventilation is peculiarly defective, and the remedy is sufficiently apparent. When the carbon is not all consumed, it flies off in smoke-an occurrence which should be guarded against, not only on account of its offensive qualities, but also from the great loss of light in proportion to the gas expended, which it invariably indicates.

prove this burner by heating the air with which it is supplied by means of a double chimney, the outer glass being so constructed that the air must descend between it and the inner glass before it arrives at the burner; and it has been stated that a saving of gas to the extent of 20 per cent. may be effected in this manner. This as sertion has, however, been contradicted by other experimenters; and certainly the plan has not been adopted into common use.

The proper size of the holes for an argand burner, and the length of the flame which gives the greatest proportion of light, have been experimentally determined by various individuals. Drs. Christison and Turner state that the diameter which appeared to answer best for coalgas of the specific gravity 6, when the holes are ten in a circle of three-tenths of an inch radius, was a thirtysecond of an inch; the distance between the holes should be about one-seventh of an inch. A series of experiments by the same individuals on the relative amount of light from flames of different lengths in an argand burner, show that the light is increased about six times for the same expenditure by raising the flame from half an inch to three or four inches; but beyond this height, the gain was comparatively little in the burners experimented on.

shape to a fish's tail), and bat-wing. The relative quantity of light which they yield from the combustion of similar quantities of gas is thus given by Dr. Fyfe: namely, single jet, 100; fish-tail, 140; bat-wing, 160; argand, 180.

These burners are commonly used in street-lamps, and they are convenient in some circumstances; for instance, in small apartments where less light is required than is given by an argand, burning at its full height, namely,

that the greatest amount of light is only obtained from any given quantity of gas by burning it in this manner.

The presence of charcoal in a free state can be detected in a gas or candle flame by the very simple experiment of introducing the edge of a white plate into it; at the lowest part of the flame where it is still blue, the plate is not affected—the charcoal is not yet deposited; the same happens at the top of the flame, the charcoal being now burnt; but in the middle, at that part from whence the light is seen to be chiefly emitted, the plate is instantly coated with pure charcoal.

It will now be understood that the manner in which gas is burnt may actually have an effect upon the amount of light derivable from a given quantity, the condition for obtaining the largest amount being, that the charcoal deposited in the flame shall be heated to the greatest possible intensity. This condition is very differently attained by the different burners in common use. It is found by experiment, that when an argand burner is constructed with holes of a proper size, and of a proper distance from each other, with an internal tube so proportioned as to admit the exact quantity of air necessary for the perfect consumption of the gas, it gives more light than can be obtained from the same quantity of gas by any other method of burning.

In the argand, the flame is steadied and the current of air increased by the use of a glass chimney, which sensibly diminishes the size of the flame, at the same time increasing its brilliancy It has been proposed to im

The single jet burners, with an aperture from a twentyeighth to a thirty-sixth of an inch, gives most light in proportion to the gas burnt, when the flame is five inches in height. In the experiments of Drs. Christison and Turner, they found that in the case of coal-gas of specific gravity 602, while the lights emitted from a twoinch and five-inch flame were as 556 to 1978, the corresponding expenditures were to each other as 605 to 1437. Hence the ratio of the lights, in reference to the expenditure, was as 100 to 150.

If the flame smokes in an argand, it is evident that some adjustment is necessary, and the gas should either be lowered or the chimney contracted until it gives a clear cylindrical flame of three or four inches in height. In the fish-tail burner, if the flame flares or makes a noise in burning, the gas should also be lowered; but to diminish either much below these points does not effect a saving of gas in proportion to the diminution of light. Hence the important conclusion, that it is more economical when the light is too strong to procure a smaller kind of burner, or where several lights are used, to put out some of them altogether, than to lower the flame in the whole.

Various calculations of the relative expense of gaslight, compared with other lights, have been made. Thus, when tallow-candles are 9d. per lb., wax-candles three times the price of tallow; train-oil 2s. per gallon, and coal-gas 9s. per 1000 cubic feet, it is computed that the relative expense will be as under, namely,

expense of wax-light of equal quantity will be about 14; sperm-oil, 8; tallow-candles, 74; rectified whale-oil, 5; common train-oil, in an improved description of burner, 2. Many individuals, who complain that the adoption of gas-light has proved no saving to them, will be surprised at the above statements. They will find, however, on examination, that they now light up their houses far more brilliantly than they were accustomed to do when candles or oil-lamps were in use, and that their equal expenditure is thus accounted for.

In addition to its greater economy, gas-light may also he pronounced safer than any other ordinary light. It produces no sparks, it cannot be carelessly placed in contact with bed-curtains or substances easily ignited, and it requires scarcely any attention. It may be turned down in an instant to the most minute speck of flame, ready to be restored when necessary by the simple turning of the stop-cock; and even when it escapes by the carelessness of an attendant or a defect in the fittings, it at once indicates the accident to the whole household by the disagreeable sinell which it occasions. From the large quantity which must be mixed with air before it becomes explosive, it is scarcely possible that this accident could occur in any ordinary apartment, even if the gas were allowed to escape on purpose. And as its smell so well indicates its presence in cellars or other contined situations, where it may have escaped in quantity from the accidental breaking or leakage of a pipe, it is only by the grossest carelessness or ignorance that a light will be approached to it before it has been allowed to escape by the free admission of air. There is no such thing as the bursting of a pipe or the blowing up of a gasometer. A gas pipe may be broken, as any other pipe, by accident; and if a leaky gasometer is covered over by a building, an explosion may then take place; but these are accidents which can very rarely occur, and they do not concern in any way the ordinary consumer of gas.

BUDE LIGHT.

We have now to notice a new method of using coalgas, lately introduced into the House of Commons, an account of which is thus given in «Chambers's Edinburgh Journal No. 445-"The light employed. is the invention of Mr. Goldsworthy Gurney, and is called the Bude Light,' from the name of his residence in Cornwall, where it first became known to him. In 1823, Mr. Gurney published a work on the elements of chemical | science, in which he described the powerful light produced from lime by the action of the mixed gases. This light, about seven years afterwards, was employed by Lieutenant Drummond on the Trigonometrical Survey of Ireland, in consequence of which it took the name of the Drummond Light.' A Committee of the House of Commons on light-houses, in 1834, recommended the lime-light to be experimented on, with a view to remove the practical difficulties connected with the subject, and adapting it for light-house illumination. In consequence of Mr. Gurney having first announced the discovery of the light, he was recommended by the committee to the Trinity House to carry out the experiment. In the course of his engagement in this office, he discovered the present light, which he considered better for lighthouse purposes, and, as already mentioned, called the Bude Light. This light is produced by introducing oxygen gas in the interior of the flame of a lamp. An ordinary flame is hollow, the exterior part being only ignited by the atmosphere; the interior part is unburnt, containing the vapour of oil and carbureted hydrogen; and the burning of this unused interior vapour, as quickly as it is distilled, by the admission of oxygen, forms the principle of the Bude Light. As soon as a small tube, conveying a stream of oxygen, is introduced into the heart of the flame, the light is immediately increased in its intensity. Since this valuable discovery was made,

The

Mr. Gurney has effected various alterations and improvements on the light. Formerly he used oil, but now he employs common street gas. This gas, however, is made to pass through a box containing naphtha, which naphthalizes it, and renders it equal to the best oil without the trouble of wicks. The London street gas, it is necessary to explain, is of bad quality, and is improved by the va pour of naphtha. The Edinburgh gas, being much superior to it, would not require any such assistance. apparatus for supplying the oxygen is placed in a vault adjacent to Dr. Reid's ventilating process. It consists of two iron retorts built over a furnace, and in these is put a certain quantity of oxide of manganese (a metallic substance which resembles brayed coal in appearance), from which oxygen is evolved, and led away in pipes to a gasometer; from the gasometer small pipes proceed to the burners in the House, each conducting a stream of oxygen into the heart of the flame. The light so produced is most intense in brilliancy, but is softened by the intervention of ground glass, and illuminates, with a powerful effect, the whole interior of the apartment. A more perfect substitute, in every respect, for day-light, could not, I believe, be found. The flame being sup plied freely with oxygen, a comparatively small quantity of atmospheric air is abstracted or consumed, and all offensive heated air from the combustion is carried away in a small tube into Dr. Reid's ventilating gallery above. Before the introduction of this beautiful light, the House of Commons was illumined with 240 wax candles dispersed about in different parts-a method of lighting which Sir David Brewster has described as most absurd, and such as no person at all acquainted with the physiological action of light on the retina, and the principles of its distribution, could have adopted.'* Dr. Ure, on being examined by the committee of members respecting the power of the Bude Light, previous to the substitution of gas for oil, observed-I made experiments upon it very carefully in my own house last night, and compared its relative illuminative powers with argand lamps and candles with great pains, both by the method of shadows and also by Mr. Wheatstone's photometer. Mr. Gurney's larger Bude lamp, furnished with a wick of fiveeighths of an inch, but emitting a white flame of only three-eighths in diameter, was found to afford thirty times more light than a wax candle, and nearly three times more light than the standard flame of the mechanical lamp, which was equal to from ten to eleven candles. Secondly, Mr. Gurney's smaller Bude burner, with a flame one quarter of an inch, was found, by the same methods, to afford a light eighteen to twenty times greater than a wax candle.'

"The adoption of the Bude Light in the House of Commons, as now improved and simplified by the substitution of gas for oil, has completely set at rest all theoretic speculations on the subject. The light is not only by far the most brilliant, without distress to the eye, but is cheaper by two-thirds than the old wax candle plan of illumination. If I recollect properly, Mr. Gurney told me that the expense of using the Bude Light, in which naphtha is required, is about twelve times greater than that of common London gas, sizes of flame being equal; but that as the Bude flame gave twelve times more light, the expense was in reality the same, without the inconvenience of many burners, and a great consumption of air. The property of giving little heat, in comparison to what is produced by common gas, is in itself of great importance. Another useful property is, that the light may be varied in tone, from the most perfect white down to the red ray, by increasing or diminishing the quantity of oxygen."

INCONVENIENCES FROM ARTIFICIAL LIGHT.

We have now briefly to notice certain inconveniences * Report of Committee on Lighung the House,

ccasionally attending the employment of gas, as well as every other kind of artificial light in common use. There are, in the first place, headache, giddiness, and other unpleasant symptons, which are sometimes complained of in small or ill-ventilated apartments where gas is burned. They may be justly attributed to the heat and carbonic acid produced during the combustion of the gas, although they also depend to some extent upon similar changes effected on the air of the room by respiration, and would occur even to a greater degree were common oil or candles employed, so as to give an equal amount of light. The remedy for the evil is simply ventilation. The other inconvenience is of a more insidious nature, and may be ultimately attended with even more serious consequences; we allude to the injurious effect of artificial light upon the organ of vision itself. It is well known that, the eyes become fatigued and painful, and they are actually weakened for a time, by exposure to any object strongly illuminated. This may be proved by reading even for a few minutes with one eye tied up, and then comparing the power of vision of this eye with the other. It is so remarkable, that although illumination by artificial means be much less brilliant than daylight, its weakening effect upon the eye is perceived in a greater degree. For example, let the same experiment be repeated by candle or gas-light. The exposed eye will be found now to be more weak than in the former case. The sensibility of its nervous structure in these circumstances is actually impaired for a time, and requires a short period of rest to restore its power. If the eyes be habitually exposed to this stimulus for long periods without rest, as is often the case with literary men, and others, who work to late hours with artificial light, there is no doubt that a permanent weakness of the eyesight may be occasioned, which may even terminate in the destruction of the sensibility of the eye-a disease known by the term amaurosis, or nervous blindness.

The first intimations of these injurious effects are usually a sensation of heat and soreness of the eyelids, and pain of the eye-ball, particularly at night, when artificial light is used; in some cases there is an unusual degree of irritability of the eyes, followed by flashes of light when they are touched, or specks floating before them, and ultimately dimness of vision, so that a stronger and stronger light is required. These symptoms may arise from other causes; but it is certain that they are often produced or augmented by the injudicious use of strong artificial light, when minute objects are contemplated. Happily, they may be obviated to a great degree without difficulty. To effect this, the eyes should in the first place be protected from the direct rays of the light itself, not only by raising it above the object out of the line of the eye, but also by the use of a shade placed upon it, so as to prevent its rays from falling upon the face; a minute object is now seen more distinctly than before, even with a less amount of illumination. There is another method which may be adopted, and it has the advantage of being equally simple, though more philosophical. It is derived from the examination of the nature of light, and of the difference between daylight and that which is obtained from combustion. Sir Isaac Newton made the discovery, that light was not simple, but a compound of seven different coloured rays, such as are seen in the rainbow. More recent discoveries have reduced the number of simple rays to three-red, yellow, and blue-which exist in daylight in the following proportions, namely, red 5, yellow 3, blue 8. In artificial light the proportions are different, yellow and red preponderating to a great degree. Experiment proves that each of these rays can act separately upon the eye. For example, if the red ray only be admitted into it, as by looking at the sun through red glass, the nervous structure of the eye is for a time weakened to the stimulus of red; and when the tncovered eye is now turned

to a white object, the other rays only are seen, namely, the yellow and blue, giving it a greenish tinge. If again, the sun be looked at through a green glass, a white object seen immediately after will appear to be red, the eye being insensible to the complementary colours, yellow and blue. For a similar reason, when the eye, passing suddenly from daylight, views objects by means of a candle or gas, they appear of a yellowish hue; and, on the contrary, passing from artificial light into day, the whole prospect has a blue or purplish aspect.

It is also proved by experiment, that the red and yellow rays have a more weakening effect upon the eye than blue; hence, to a certain extent, the more injurious effect of artificial light, which, as already stated, contains these rays in excess. This fact at once suggests a method of obviating the bad effects of gas or candle light, which is either to make it pass through a blue glass shade, so as to obstruct a portion of the red and yellow rays, or to reflect down blue rays by placing a blue reflector above the light; in this manner the quality of artificial light is made more nearly to approach to that of the sun, and objects are seen by it of a purer white, and agreeably cool and refreshing to the eye.

For further information on this subject, we would strongly recommend a small volume by Dr. James Hunter, entitled, On the Influence of Artificial Light in causing Impaired Vision."

66

PREVENTION OF SMOKE.

The smoke arising from the furnaces employed at factories has, within the last twenty or thirty years, been felt as a great nuisance in most manufacturing towns, polluting, as it does, the pure air of heaven, and begriming every exposed object within the range of its influence. Those employing furnaces have also become generally aware that smoke is only a volatile form of fuel, and that if either less of it were generated, or if, when generated, it could be consumed, there would te a great saving in the expense of raising steam. These circumstances have led to various devices for the combustion and prevention of smoke, the chief of which it is our duty to describe in this place.

IVISON'S PLAN FOR CONSUMING SMOKE.

This plan, the invention of Mr. Ivison of the silk factory, Fountainbridge, Edinburgh, and which is covered by a patent, consists in the projection of a stream of steam into the space between the fire and the boiler. It proceeds upon the theory, that, the steam so introduced being decomposed by the heat of the furnace, its oxygen unites with the carbon of the smoke, and causes the combustion of that material, while the hydrogen also burns through its own inflammable quality. The arrangement for the introduction of the steam is simple: a small iron pipe, proceeding from the top of the boiler, bends over and enters the furnace immediately above the door, the termination being fitted with a fan-shaped expansion full of small holes, by which the steam is dispersed throughout the fiery space. By a steam-cock on the pipe at the furnace door, the discharge can be regulated or altogether stopped. The due working of the apparatus depends on admitting into the furnace a certain quantity of hot air, and this is done through two pipes which, opening from the open air, pass into the furnace and out again, the inner terminations being inserted in the door.

With regard to the prevention of smoke, Mr. Ivison's plan seems to have established for itself a certain measure of success; but we have understood that the theory is extensively doubted, and that the plan is not likely to be universally adopted. At the silk factory, Edinburgh, at which it is professedly applied, large volumes of black smoke are still frequently seen, and this affords reason

to doubt its utility in general circumstances. The plan was tried on the furnace of the steam-boiler used in the office where this work is printed, and was found to be defeated, in consequence of the extremity of the steampipe being constantly liable to be destroyed by the fire. This difficulty may be obviated, and the whole benefit of the plan may, we believe, be secured, if the steampipe be introduced below the bars of the furnace, or the bottom ash-pit be kept constantly covered with water.

JUCKES'S PLAN.

Mr. Juckes's plan is designed for consuming smoke and economizing fuel. The following description of it was given by himself at the meeting of the British Association at Manchester, June, 1842. "His gratebars are endless chains passing over rollers, and moved forward about an inch per minute. The coals employed are common siftings or screenings, which are heaped on the bars outside the furnace door, which slides upwards. The door is left a little open, and by passing under it, the small coal is spread uniformly over the bars. The air is constantly supplied through the bars directly to the fuel while burning, and in this way perfect combustion is obtained. The bars, being slowly moved on, carry the ashes to the ash-pit, which lies at the back of the grate. Clinkers are prevented from incrusting the bars, by their passing under a gauge, which effectually removes them; and the burning away of the bars is prevented by their constantly moving away from the hottest place. The bars or chains, with their rollers and driving-wheels, are fixed in a frame which can be completely drawn out froin under the boiler, for the purpose of removing injured bars, or any other purpose. A boiler has been at work for two months at Mr. Baird's saw-mill, Wapping, and given great satisfaction. No smoke is ever seen, and the consumption of coal is only 12 cwt. per day, whereas, with the old boiler, they had used a ton of coal, besides a ton of wood and saw-dust."

tions.

SMITH'S NEW BOILER.

The principle of this boiler was suggested to Mr. Smith by a consideration of the upper and under currents in the ocean and in the air, often flowing in opposite direcHe has tried to avail himself of this principle in his furnace, considering that, from the great rapidity with which the gases leave the fire, it is impossible to effect their perfect incorporation with atmospheric air and consequent combustion; and believing that, when these gases are allowed to pass off directly through the flues in nearly straight lines, the gases and air pass along in separate threads or films, sufficient time for their proper mixture not being given under the ordinary systems of combustion. Mr. Smith, therefore, constructs a boiler and furnace in the following manner :-Beyond the bridge of the furnace, he places a chamber within the boiler entirely surrounded by the water; this chamber only leaves room for small water space along the sides and bottom of the boiler; it is arched elliptically, and of course, like all internal flues or fire-boxes, leaves sufficient space above for water and steam. The funnel or chimney is placed on the same side as the fire, and as low as possible. The hot gases and air rush over the bridge gradually, from the size of the chamber, losing their initial velocity. When they impinge against the opposite side of the chamber, the current is directed downwards; and the return current, with diminished velocity, flows back to the chimney under the stratum of gas and air issuing from the fire-bridge. In this way time is given for combustion, and the gases are inflamed or exploded before going up the chimney. From the chamber being quite within the boiler, nearly all the heat is made available. Mr. Smith considers his plan particularly applicable to marine boilers and reverberatory furnaces. He lately had one established at Messrs. Page

and Grantham's, Liverpool, working an engine of ten horse power, the pressure in the boiler being 50 lbs. This did as much work with 8 cwt. of coal as the best tube boiler which these gentlemen ever tried had performed with 12 cwt.

WADDINGTON'S PATENT BOILER.

The chief novelty in this plan is a contrivance for introducing coal in a gradual manner. Put in at the sides of the boiler, it is made to descend inclined planes to the bars, before reaching which it is coked by the fuel burning on the bars, and smoke is prevented.

GREENWAY'S METHOD.

This is a plan of considerable ingenuity, as well as simplicity, for consuming smoke. He employs, in each

case, two boilers and two furnaces. The furnaces are supplied with dampers, so that their communication with their respective flues can be cut off, and a communication opened between the two fires by an intermediate flue. When fresh coals are put on one fire, the damper of that fire is shut, and the intermediate flue opened, so that the smoke is obliged to descend through the bars, and ascend through the burning fuel of the other fireplace. By alternating this, as fresh coals are put on the fires, smoke is said to be prevented.

VARIOUS MINOR PLANS.

We here briefly notice a few plans of inferior note and likelihood, which have been recently brought before the world. Mr. Kurtz's is by hollow bars admitting fresh and heated air to a hollow bridge. Mr. Samuel Hall's is a plan of much the same nature, by air heated in a quantity of pipes in the flue between the boiler and the chimney, passing thence to perforations in or near the bridge. Mr. John Chanter's is by an "auxiliary boiler," the bars under which are inclined, and have below an iron plate termed a "deflector." At the lower end of this furnace a common furnace is constructed, which receives the coke or charred coal in an incandescent state from the upper bars. Mr. R. Rodda's is by a furnace divided into two parts, one for coking the coal, the other for receiving the coke-the gas from the coal passing through lateral openings into the second division, where they are to be destroyed by the bright fire. A stream of fresh air is admitted, joining the smoke in the passage, thus effecting its combustion.

It may here be remarked, that coal may be economized and the escape of its fumes much diminished, without any peculiar contrivances, simply by careful and skilful feeding of the furnace by the firemen. In Cornwall, where no contrivances exist, fuel is managed in such a way by the firemen that the consumption in general is only about 2 pounds per horse power per hour, and smoke is said to be "never seen." The coal is regularly weighed to the firemen, and the "duty" of the engines is reported every week. This excites emulation among the men, and when a falling off in their attention takes place, it is instantly detected. The great object held in view is to keep thin bright fires, coking the coal in front.

MR. C. W. WILLIAMS'S PLAN.

This is the plan most in esteem at present, and which seems most likely to prove generally serviceable. Mr. Williams is one of the oldest managing directors of the City of Dublin Steam Packet Company, and the author of a treatise entitled, "The Combustion of Coal, and the Prevention of Smoke, Chemically and Practically Con sidered." Though not by education and circumstances a man of science, his attention having been powerfully called to the subject, he has prosecuted his inquiries into it to at least scientific results, all of which have been vouched for by eminent practical chemists.

Mr. Williams aims not at burning the smoke, which he holds to be a chemical absurdity, but at preventing its