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of this modus operandi would be that fuel to be converted into gas is introthe illuminating gas supplied, say in duced through a hopper, and the cinder London, from Newcastle coal, would and ashes work out through the open probably exceed 20-candle power, instead orifice at the bottom. of 16, as at present, whereby the object Instead of a grating for the introducionable results of gas lighting would be tion of atmospheric air a current of greatly diminished, and there would be, heated air is brought in, either through say, an equal volume of · heating gas the hopper or through the orifice at the available, consisting for the most part of bottom, and is discharged into the center marsh gas, which, although greatly in- of the mass of fuel ; the effect is the genferior to olefiant gas in illuminating ef- eration of a very intense heat at that fect, would be actually more suitable for point. The fuel, afterits descent through heating purposes, because less liable to the hopper, arrives gradually at this reproduce soot in its combustion.

gion of intense heat, and when subjected The total cost of production would not to it, parts with its gaseous constituents. be increased by this separation of the At the point of maximum heat coke is gases, and the price might, with advant- consumed, producing carbonic anhydride, age both to the supplier and to the con- which, in passing through the considerasumer, be so adjusted that the latter, ble thickness of fuel surrounding this while paying for his illuminating gas an portion, takes up a second equivalent of increased price proportionate to the in- carbon and becomes changed into carcrease of illuminating power, would be bonic oxide. Here also the earthy confurnished with a heating gas at greatly stituents are for the most part separated reduced cost; for the heating gas would in a fused or semi-fused condition, and be reduced in price in a much larger pro- in descending gradually reach the orifice portion than the illuminating gas would at the bottom, whence they are removed have to be raised, because it would not from time to time. Air enters through require the same purification from sul- the bottom orifice to some extent, causphur which renders illuminating gas ing the entire consumption of the carcomparatively costly. The enormous in- bonaceous matter, which may have got crease of consumption would moreover past the zone of greatest heat; water is enable the gas companies to reduce prices also here introduced in a hollow tray, all round very considerably without in- and after evaporation by the heat of the terfering with their comfortable reve- hot clinkers, passes upwards through the

incandescent mass, and is converted by For large applications of heating gas decomposition into carbonic oxide and to the working of furnaces and boilers, hydrogen gas. The exit orifices for the simpler means than the retort can be gases are placed all round, near the cirfound for its production. I constructed cumference of the chamber, ascending a gas producer many years ago in con- upwards into an annular space, whence nection with my regenerative gas fur- they are taken through pipes to the furnace, which I need not now describe in nace or other destination. The advantdetail

. In it all the carbonaceous matter ages connected with this modus operandi of the coal is converted into combustible consists in the intensity of the heat progas, the solid carbon yielding a supply duced within the center of the mass, of carbonic oxide; the resultant mixture whereby the whole of the fuel is conof combustible gas contains a very large verted into combustible gases, with the proportion, averaging 61.5 per cent., of least amount of nitrogen. The hydronitrogen, which swells its volume with carbons formed in the upper portion of out in any way contributing to its heat- the apparatus have to descend through ing power. It has been my endeavor for the hotter fuel below, and in so doing, some time to construct a gas producer the tar and other vapors mixed up with which, without losing the simplicity of them are decomposed, and furnish comthe first, should be capable of yielding a bustible gases of a permanent character. heating gas of superior calorific power. The orifice at the bottom of the appaThis producer consists of a wrought- ratus may be enlarged and so arranged cylindrical chamber, truncated down that, instead of ashes only being prowards, and lined with brickwork. The duced, coke may be withdrawn, and in

nues.

this way a continuous coke oven may be and myself had to endure. The change constructed, which is at the same time a from the use of solid to gaseous fuel gas producer, or, in other words, an ap- would be the prelude probably to another, paratus in which both the solid and gas- and still more important change, namely, eous constituents of the coal are fully the entire suppression of the steam utilized. The intense heat in the very boiler. We are already in possession of center of a large mass of fuel has for its gas engines working at

moderate expense result a very rapid distillation, and thus as compared with small steam engines, one gas producer does the work of two even when supplied with the comparaor three gas producers of the type hith- tively expensive gas from our town gas erto employed; this more concentrated mains, and all that will be required is an action will moreover allow of the intro- extension of the principle of operation duction of gaseous fuel, where want of already established. The realization of space and considerations of economy such a plan would, of course, involve have militated hitherto against it, and in many important considerations, and may favor of the ordinary coal furnace. It be looked upon as one of those subjects has been already proved that steam the accomplishment of which may be left boilers can be worked economically on for the energy and inventive power of land with gaseous fuel, and there is no the rising generation of engineers. reason that I know of why the same Before leaving this branch of the submode of working should not also be ap- ject, I wish to call attention to a favorite plied to marine boilers. The marine suggestion which I had occasion to engine has within the last fifteen years make some years ago. It consists in been improved to an extent which is placing gas producers at the bottom of truly surprising; the consumption of the coal mines themselves, so that incoal, which at the commencement of that stead of having to raise the coal by meperiod was never less than 8 lbs. per chanical power, the combustible gases horse power, has been reduced by ex-; ascending from the depth of the mine to pansive working in compound cylinders the surface would acquire by virtue of to 2 lbs. or even less per actual horse their low specific gravity such an onpower. The mode of firing marine boilers ward pressure that they could be conhas, however, remained the same as it ducted in tubes to distances of many was in the days of Watt and Fulton. In miles, thus saving the cost of raising crossing the Atlantic one may see a con- and transporting the solid fuel. Glassiderable number of men incessantly em- gow, with its adjoining coal fields, ap. ployed in the close stoke hole of the ves- pears to me a particularly favorable losel opening the fire doors and throwing cality for putting such a plan to a pracin fuel. Each charge gives rise to the tical trial, and the well-known enterprise development of great clouds of black of its inhabitants makes me sanguine of smoke issuing from the chimney, to the its accomplishment. When thus supgreat annoyance and discomfort of the plied with gaseous fuel, the town would passengers on deck. If, instead of this, not only be able to boast of a clear atthe fuel could be discharged mechani- mosphere, but the streets would be recally into one or more gas producers, the lieved of the most objectionable portion gaseous fuel produced would maintain of the daily traffic. the boilers at a very uniform heat, with I now approach another and the last out necessitating the almost superhuman portion of my address, the attainment toil of the firemen ; no smoke or dust of very intense degrees of heat either would be emitted from the chimney, and for effecting fusion or chemical decona large saving of fuel would be effected. position. Although by means of the

This change would be specially appre- combustion of either solid or gaseous ciated by the numerous tourists visiting fuel heats are produced which suffice for the Western Highlands. Speaking from all ordinary purposes, there is a limit my own experience on one occasion, I imposed upon the degree of temperamay say that the pleasure of a trip on ture attainable by any furnace dependthe beautiful Loch Lomond was very se- ing upon combustion. It has en riously marred in consequence of the shown by Bunsen and by St. Claire De fumigation which my fellow-passengers ville, that at certain temperatures the

chemical affinity between oxygen on the pounded charcoal or other bad conductone hand and carbon and hydrogen on or of heat. A hole is pierced through the other absolutely ceases, and that if the bottom of the crucible for the adthe products of combustion C0, and H.O mission of a rod of iron, platinum, or be exposed to such a degree of tempera- dense carbon, such as is used in electric ture they would fall to pieces into their illumination. The cover of the crucible constituent elements. This point of dis- is also pierced for the reception of the sociation, as it is called, is influenced by negative electrode, by preference a cylinpressure, but has been found for co, der of compressed carbon of comparaunder atmospheric pressure to be 2600* tively large dimensions. At one end of C, (or 47000 Fahr.). But long before a beam supported at its center is susthis extreme point has been arrived at, pended the negative electrode by means combustion is greatly retarded, and the of a strip of copper, or other good conlimit is reached when the losses of heat ductor of electricity, the other end of by radiation from the furnace balance its the beam being attached to a hollow cyproduction by combustion. To electrici. linder of soft iron free to move vertity we must look for the attainment of a cally within a solenoid coil of wire, pretemperature above that of dissociation, senting a total resistance of about 50 and we have evidence of the early appli- units or ohms. By means of a sliding cation of the electric arc to such a pur- weight the preponderence of the beam pose. In 1807 Sir Humphrey Davy suc- in the direction of the solenoid can be ceeded in decomposing potash by means varied so as to balance the magnetic of an electric current from a Wollaston force with which the hollow iron cylinder battery of 400 elements, and in 1810 he is drawn into the coil. One end of the surprised the members of the Royal In- solenoid coil is connected with the posistitution by the brilliant electric arc pro- tive, and the other with the negative pole duced between carbon points through of the electric arc, and, being a coil of the same agency. Magneto-electric and high resistance, its attractive force on dynamo-electric currents allor of the the iron cylinder is proportional to the production of the electric arc much electro-motive force between the two more · readily and economically than by electrodes, or, in other words, to the the use of Sir Humphrey Davy's gigan- electrical resistance of the arc itself. tic battery, and Messrs. Huggins, Lock The resistance of the arc was determyer and Liveing, and other physicists, ined and fixed at will within the limits have taken advantage of the compara- of the source of power, by sliding the tively new method to advance astronomi- weight upon the beam. If the resistcal and chemical research with the aid of ance of the arc should increase from any spectrum analysis.

cause, the current passing through the My object is now to show that the solenoid would gain in strength, and the heat of the electric arc is not only avail- magnetic force overcoming the counterable within a focus, or extremely con- acting weight, would cause the negative tracted space, but that it is capable of pro- electrode to descend deeper into the cruducing such larger effects as will render cible; whereas, if the resistance of the it useful in the arts for fusing platinum, arc should fall below the desired limit, iridium, steel, or iron, or for effecting the weight would drive back the iron such reactions or decompositions as re- cylinder within the coils, and the length quire for their accomplishment an in- of the arc would increase, until the baltense degree of heat, coupled with free- ance between the forces engaged had dom from such disturbing influences as been re-established. Experiments with are inseparable from a furnace worked long solenoid coils have shown that the by the combustion of carbonaceous ma- attractive force exerted upon the iron cy. terial. The apparatus which I employ linder is subject only to slight variation to effect the electro-fusion of such mate- within a range of several inches, which rial as iron or platinum consists of an circumstance allows of a working range ordinary crucible of plumbago, or other to that extent of nearly uniform action highly-refractory material, placed in a on the electric arc. metallic jacket or outer casing, the inter This automatic adjustment of the arc vening space being filled up with is of great importance to the attainment

of advantageous results in the process ble might be interfered with through the of electric fusion ; without it the resist- detachment of particles from the dense ance of the arc would rapidly diminish carbon used for the negative pole, alwith increase of temperature of the though its consumption within a neutral heated atmosphere within the crucible, atmosphere is exceedingly slow. To and heat would be developed in the dy- prevent this I have used, both in this connamo-electric machine to the prejudice nection and also in the construction of of the electric furnace. The sudden electric lamps, a water pole, or tube of sinking or change in electrical resistance copper, through which a current of waof the material undergoing fusion would, ter circulates, so that it yields no subon the other hand, cause sudden increase stance to the arc. It consists simply of in the resistance of the arc, with a like- 'a stout copper cylinder closed at the lihood of its extinction, if such self-ad lower end, having an inner tube penetratjusting action did not take place. ing to near the bottom for the passage Another important element of success of a current of water into the cylinder

, in electric fusion consists in constituting which water enters and is discharged by the material to be fused the positive pole means of flexible india-rubber tubing. of the electric arc. It is well known This tubing being of non-conductive that it is at the positive pole, that the material, and its sectional area small

, the heat is principally developed, and fusion escape of current from the pole to the resof the material constituting the positive ervoir is so slight that it may be neglected. pole takes place even before the crucible On the other hand, some loss of heat is itself is heated up to the same degree. incurred through conduction, with the This principal of action is of course ap- use of the water pole, but this loss diplicable only to the melting of metals minishes with the increasing heat of the and other electrical conductors, such as furnace, inasmuch as the arc becomes metallic oxides, which constitute the ma- longer, and the pole is retired more and terials generally operated upon in metal- more into the crucible cover. lurgical processes. In operating upon In the experiments which I shall now non-conductive earth or upon streams of place before you the current which has gases, it becomes necessary to provide a supplied the one electric lamp in the non-destructible positive pole, such as is center of the hall will be diverted by supplied by the use of a pool of fused means of a commutator through the elecplatinum, or iridium, or by a plumbago tric furnace. After it has been active crucible. In working the electric fur- for five minutes to warm the crucible, I nace, some time is taken up in the first shall charge it with 8 lbs.of broken steel instance in raising the temperature of files, which I shall endeavor to melt and the crucible to a considerable degree, pour out into an ingot mould before your but it is surprising how rapidly an accu- eyes. By some obvious modifications mulation of heat takes place. In using of this electric furnace, it can be made a pair of dynamo-machines capable of available for a variety of other purposes producing seventy webers of current where intense heat is required, combined with an expenditure of 7 horse-power, with immunity from disturbing chemiand which, when used for purposes of cal actions. By piercing a number of illumination, produce a light of 12,000 radial holes through the sides of the candles, a crucible of about 8 inches in chamber, and introducing the ends of depth, immersed in a non-conductive wires through the same, an excellent material, has its temperature raised to a means is provided of heating those wire white heat in fifteen minutes, and 4 lbs. ends very rapidly, without burning them, of steel are fused within another fifteen for the purpose of welding them to. minutes, successive fusions being effected gether. The electrical furnace will also in somewhat diminishing intervals of be found useful, I believe, in the hands time. The process can be carried on on of the chemist, to effect those high tema still larger scale by increasing the perature reactions between gaseous bodpower of the dynamo-machines and the ies which require the employment of size of the crucibles.

temperatures far exceeding the hitherto The purely chemical reaction intended available limits, and will thus increase to be carried into effect within the cruci- the area of available reactions at his dis

posal for the attainment cf cithcr scien- neglect the economical and sanitary contific or practical ends.

ditions under which those ends were I have endeavored to compress within accomplished. The exhibition, which the limited space of a single lecture sub. has lately been held in this city, of apject matter that might occupy the close pliances for heating and illuminating by attention of the student for weeks or means of gas and electricity, in which months; and I may, therefore, be par- your President, my esteemed friend, Sir doned if I have failed to convey to you William Thomson, took so prominent a more than a very rough outline of what part—as he does in everything tending may be accomplished by the judicious towards the advancement of human use of gaseous fuel, and of the electric knowledge and well being-proves how current, as heating agents. The one deep is the interest felt amongst you in purpose that has been foremost in my those very questions with which I have mind in preparing this lecture has been had to deal this evening.

And so I to make war upon the smoky chimney- thought you might not be disinclined to which, so far from being a necessity in- give attention once more to a particular der any circumstances whatever, should view of the question, which happens to be regarded only as a remnant of that be the result of the independent labor stage of our industrial and social pro- of one who may claim, at any rate, to gress which, satisfied with the attain- have given a life-long attention to the ment of certain ends could afford to subject.

THE EFFECT OF PUNCHING ON STEEL AND IRON PLATES.

From“

The Engineer."

We referred recently to certain experi- drilled subsequently, or it can be first ments made by the Board of Trade on drilled, and then punched. The value of steel plates for boilers and ships. The all the three first-named systems has most prominent feature in Mr. Trail's been repeatedly tested, but no one has report is the absence of information on tested the fourth, and yet it appears to those points which most perplex en- have much to recommend it. It is well gineers and shipbuilders; and before we known that when a plate is punched the have done we hope to make this fact hole is always a little conical, and this very clear, in the hope that others will conical shape is of much value, because take new ground, and quit the beaten it relieves the rivet head or point to path of experiment, which, it may now some extent of strain, and even though be safely said, cannot lead us to a knowl-, the head should fly off the rivet is still edge of that which we wish to know. It useful. Drilled holes are not conical, will be remembered that all the plates and this is admitted to be a serious tested were pulled asunder by Mr. Kirk-'objection to them, and besides they are aldy, and the results obtained, although expensive. Now, if plates requiring in many respects new to many persons, ' such holes were first drilled to, say, ' in., are just what were anticipated by those and then punched up to the proper who have made steel a special subject of dimensions, say 1 in., the cost of drillstudy. But, although this is true of ing would be reduced, and the conical most of the results obtained it is not punched hole would be obtained. It true of all; and some of them are op- remains to be seen whether under such posed in a small degree to those obtained conditions the plate would or would not by other inquirers. It is of the utmost be weakened by the punching; as on importance that the effect produced on a this point we possess no information we plate by making holes in it should be must content ourselves with suggesting understood very plainly. There are to any one about to test steel the advisfour ways in which a rivet hole may be ability of trying what would be found a made. It can be punched, or it can be very simple experiment. As regards the drilled, or it can be punched first and other three systems, the Board of Trade

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