its other end the axis communicates with a enerator of carbonic acid gas. The tub is placed so that the plane of its bottom forms an angle of 40° with the horizon, and is made to revolve at the rate of twelve or fourteen times per minute. The granulated lead being placed in the tub, a sufficient quantity of water must be added; being about half as much as the tub will contain in its inclined position; carbonic acid gas being introduced through the hollow axis, the lid or cover is put on, and the tub caused to revolve. In about twenty-four hours a quantity of white lead will have been formed, which is to be drawn off in vats, washed, dried, ground, and packed for use in the ordinary way.

The claim is to the formation of pure carbonate of lead, known to painters as good white lead, by the attrition of lead in water in closed vessels, supplied with carbonic acid gas; and the peculiar adaptation of the means above described.

NOTES AND NOTICES.

Death of the Electrical Eel.-The electrical eel, at the Royal Adelaide Gallery, died a few days ago. The cause of its death was mortification. It was brought to this country from one of the tributary streams of the river of the Amazons, about four years ago, and was the only one of its kind in Europe. Its structure was very singular. The seat of the electric power lay between the shoulder and the tail, and between the head and the shoulder. Its food was small fish, which it could stun and stupify by an electric shock, at two feet distance. The most interesting and beautiful experiment performed by its electricity was in setting fire to a piece of silver paper in a glass cylinder. One end of a conductor was attached to the paper, and the other to the eel, and by this means the paper was burnt. It was necessary that the eel should be irritated before it would send forth electricity.

Ploughing by Steam.-At a late meeting of the new Agricultural Society, which was held in Milwich School-rooms, Staffordshire, Mr. W. Blurton, of Field Hall, Uttoxeter, explained his project of employing steam, instead of animal power, for the important purposes of ploughing. He said:-" In trying an experiment a short time ago, I discovered that ploughing might be as effectually, and quite as easily, performed with the power behind the plough, as by the usual method of dragging the plough after the power; therefore, I conceive that four or five ploughs might be arranged, and be propelled by a locomotive steam-engine, so that poaching the land in wet seasons might be entirely avoided. Steam power equivalent to 694 lbs. would be sufficient either to drag or propel a double plough, at a proper width and depth, 2 miles an hour, leaving an excess of power of 356lbs., which latter power may be applied as will be subsequently shown. It is a well known principle in mechanics, that by decreasing the speed you may thereby increase the power; therefore agreeably to that principle, viz., by reducing the speed to one-fifth of 24 miles, or to half a mile an hour, five double ploughs may be propelled at once, which decrease of speed will render the ploughs much more manageable, and the necessary number of turnings at the extremities of the furrows will consequently be reduced in nearly the same proportion. There are various means by which increased power may be obtained by decrease of speed; and I will instance one familiar to almost all, viz., the common crane, which may be seen in most of the wharf yards in great varieties. An

8-toothed cast-iron pinion working in a 48-toothed wheel, will, by a common windlass and the power of one man, lift from the ground to the height re quired much more than half a ton. I will supposE, for instance, that only four double ploughs are at ranged, and that two of them shall turn the farrows in the usual method towards the right hand and the centre of the land or butt, and the two other plougha with the mould boards reversed turn the furrows to the left hand, also towards the centre; these alto gether propelled forward by the engine would complete what is now called a four-'bout land or butt af once. It will therefore be obvious to every practical farmer, that by such an arrangement the ploughs will leave two open furrows, both of them solid and even at the bottom, which for all the purposes of steam-ploughing will serve as a railroad for the driving wheels of the locomotive engine to move along, and therefore much less propulsion will be required than if the wheels of the engine had to act on a soft or uneven surface. You will perceive that in the arrangement previously made four double ploughs were mentioned, and the consequence of decreasing the number of double ploughs from five to four will amply compensate for, or overcome, any difference in draught caused by the nature of the various tenacities of soil, or other circumstances. The excess of power before mentioned of 356 hs., acting on the foregoing principle of decrease of speed, will, I conceive, be sufficient to overcome the power necessary to move the engine alone. Four double ploughs moving at the slow speed of half a mile an hour, and plowing furrows ten inches wide, would plough an acre in two hours, allowing a reasonable time for turning at each end of the furrow.

Standard Weights and Measures.-A commission was some time ago appointed by government to institute a new inquiry into the present standard weights and measures, consisting of Sir John Herschell, Professor Airy, Mr. Lubbock, and others. The commissioners have reported, 1. That it would be advisable to adopt a decimal computation in all weights, measures, and monies; 2. That troy weight should be abolished, and avoirdupois substituted; and, 3. That proper model standards should be provided.

"The

Royal Mail Company's Steam Ships.-A statement having appeared in the newspapers, that "the great size and general plan of construction of these steamers do not at all answer the expectations of their officers," Captain Chappell, the Secretary of the Royal Mail Steam Packet Company, has published the following strong contradiction. whole of the voyages," says Captain C., "made by this Company's steam-ships have exceeded the estimate which had been originally formed as to their probable speed; and as relates to the Thames, in particular, the only one of the Company's steamers which has yet returned to Europe, the Captain distinctly reports that her size, power, and construction, are admirably adapted for transatlantic navigation. The following abstract from her log will be conclusive, with persons conversant with such long voyages:The Thames was absent from England, altogether, 66 days; of these she was at anchor, in various ports, 20 days; and at sea, 45 days; whole distance run, 10,700 nautical miles-which is equal to a speed, throughout, of 233 miles per day.'" Errata.-In Mr. Heineken's description of the Ancient lock of Combination, No. 963,

Line 3, for "Butens," read "Buteus.

Col. 2, 12 lines from bottom, read "the second ring, VIOA E M; the third, I DLN VA; the fourth, REIAST."

Ibid., 2nd line from bottom, read "OVIR, FIDE, COLI."

Page 54, 1st col., 6 lines from top, read "FIAT. SILE, DIVI."

Ibid., 16th line from top, for "Schweuter," read "Schwenter."

In Table II., the fourth line should be "VIOA EM;" the sixth line, "I DL NUA; the eighth, "REIAST."

Sir, I have found so much reason to be satisfied with the use of a little apparatus I lately made for myself, and have found it so much looked after by artisans in the place where I reside, that I venture to send you a description of it, in order that, if you think it likely to be of more extensive use, you may insert it in the Mechanics' Magazine.

I am, Sir, your most obedient,

K. H.

Description of a Blow-pipe Lamp of a convenient form for many purposes in the useful arts.

Fig. 1 is a front view, fig. 2 a plan, and fig. 3 a side view, of the apparatus, which may be constructed of larger or smaller proportions, according to the purposes to which it is to be applied.

A is a brass tube, closed at the lower end, and suspended in the wooden stand, C, by perforated trunnions having stopcocks, D D, and screwed extremities, to which flexible or other tubes may be attached.

B, a piece of brass tubing, of the same diameter as A, but terminating in a cone, the apex of which is open. It is attached to A by the screwed part G, which requires to be so accurately fitted, that the combined tube may be lengthened or shortened by screwing or unscrewing B or A, without permitting the escape of gas from the inside.

C. The wooden stand.

DD. Stop-cocks for regulating the supplies of the gases.

E. The nosel of the blow-pipe fitting into the socket F, concentric with the axis of A and B; the length of the shifting nosel should be such, that when B is screwed home on A, E should be just outside of the cone of B, and about oneeighth of an inch within it when B is unscrewed.

F is a continuation of the trunnion which leads to the air, or the oxygen gas holder, and is turned up in A by a rightangled knee, so as to bring the socket for E truly in the axis of the cone of B.

G. The adjustible connexion of A and B.

It will be obvious, on inspection, that no mixture of air and gas can take place in this apparatus, until they be outside of it; and also that, however great the pres

The suspension of the apparatus on trunnions, like a howitzer, is not essential, but is convenient, as it affords the means of directing the jet of flame in any way it may be required for the work in hand.

When this apparatus is made on such a scale as to give I inch in diameter, and 3 inches in length, to A B, the tuyere or opening in the apex of B may be from 15 to 2 of an inch in diameter, and the pin-holes of the nosels may range from 01 to 03 of an inch. In these proportions it will be found very serviceable, in many workshops, for soldering silversmiths' work, hardening small steel tools, and a variety of other purposes: in the latter its use is invaluable, as the requisite degree of heat can be so accurately given, that no taking back is required after dipping; and the tenacity of the steel not being injured, tools so hardened last much longer keen than when they have been first made too hard, and then reduced.

When common street gas is used in this lamp with atmospheric air, a foot bellows may be employed to furnish the latter; but the better plan is to have an air-holder under water pressure, with an air-pump (similar to those commonly used for filling shower-baths) attached to it to fill it by. An air vessel 15 inches diameter, and 15 inches deep, will con

ON THE MANAGEMENT OF FURNACES AND BOILERS BY C. W. WILLIAMS, ESQ.

Sir,-In my last communication on this subject, (No. 971,) I dwelt on the absolute necessity for having the means of observing what is going on in the interior of furnaces, and gave a plan of one of my own, which has been in use nearly two years, descriptive of the mode in which I apply sight-holes and thermometers for the purposes of inspection. By these means, and with further aids, which I shall presently describe, the various processes and changes, both in appearance and temperature, which take place as combustion proceeds, and the air is admitted or excluded, may be accurately watched and studied. These are daily witnessed by scientific and practical men, who freely express their conviction of the necessity for such inspection, before one can safely give an opinion on the changes, which they are thus enabled so deliberately to examine and appreciate, and the causes which produce them. For, with what pretensions to accuracy can we theorize on the chemical or practical results arising from the admission of air in different places and modes; or how assert that it will produce a heating or cooling effect, unless, by suitable means, we are enabled to ascertain the fact, and test the correctness of our own theories?

Again, how can we assert, as has been done with more boldness than truth, that when the coal gas (carburetted hydrogen) is all expelled from the coal, and the furnace exhibits what is called a "clear fire," there will be no combustible gas passing over the bridge, and no demand for air in that quarter-an assertion which the eye and the thermometer at once disprove, by the appearance of a flame of considerable length and intensity, whenever the means of internal inspection is afforded? Surely such facts should operate as a caution against deciding rashly on causes and effects, and until the correctness of our inferences can be determined.

259

In the management of furnaces, so as to effect the most perfect combustion and the largest measure of heat, the main considerations are those which concern the admission of air, as to mode and quantity, rather than the relative proportions of fire, flue, and boiler surfaces, or such merely mechanical details-considerations which are but of secondary importance, and essential only as they influence the admission of air, and its operations. As to quantity, and the mode of introduction, it is difficult to determine which requires the greater attention, or in which we have been most at fault in other words, whether more mischief has been done by the admission of a plus or minus, the true chemical equivalent, than by the mismanagement of the quantity actually introduced; for on each will be found equally to depend the generation of smoke with its accompanying nuisance and

waste.

Let us now suppose a sufficient body of clear, ignited, solid fuel, remaining on the bars, preparatory to throwing on a fresh charge of coal. In a furnace in this state, it is supposed that there is no demand for air, except for the combustion of such solid matter, and that the natural approach for it is by the ash-pit. This impression is unquestionably erroneous, and must be disproved before we can duly appreciate the value or necessity for the introduction of air in any other quarter, or for any other purpose.

The impression here referred to is drawn from the unquestionable fact, that when we open the furnace door to admit the new charge, we see neither gas, nor smoke, nor flame. The cause of this fact, however, as already observed, has been overlooked, namely, that it is the very act of opening the door, and thus admitting a large body of air, which has produced this absence of flame, or gas, in the process of combustion. That this is true, is proved by the other fact, that if we close the door-admit air in a proper manner, and then look in from behind, where I have placed the centre sight-hole, (see engraving in No. 971,) a flame of considerable length and intensity will then be visible, by which we are forced to the conclusion that a considerable quantity of gas, of some description, is then generated in the furnace, and may be consumed if proper means be

adopted. This will hereafter be more fully examined when speaking of the use of coke or anthracite.

Thus we see how mere ocular inspection disproves our previous notions and theories, and establishes this fact, that before we throw on the fresh charge, there is a gaseous, as well as a solid body, available for the generation of sensible heat; and as both are combustible, each must be supplied with its due proportion of air before its combustion can be effected. The gas here referred to is carbonic oxide- always invisible producing visible smoke, and its presence only detected by its assuming the form of visible flame. This is the gas also which M. Faber, by his ingenious and scientific contrivance has now rendered available in many of the processes of manufacturing iron, and even where an intense heat is required.

never

The furnace being in this preparatory state, let us suppose that it is receiving a full charge, which shall cover such previously ignited and glowing mass with a stratum of coal from six to eight inches thick, (according to circumstances and the size of the furnace,) and sufficient to last a considerable time before it is again reduced to the same condition, and ready for another charge. A new state of things is now induced-much combustible gas (carburetted hydrogen) is evolved from the fresh coal, and a commensurate demand is thus created for atmospheric air. How then is such demand to be satisfied? It is manifest that unless such newly evolved gas be supplied with air, it cannot be consumed -yet it is equally manifest that in the very act of charging the furnace we have counteracted our own avowed purpose, by thus thickening the mass on the bars, and consequently obstructing the passage of the air through them, from the ash pit-thereby preventing the possibility of its access at the very moment we have created a demand for an increased supply.

This, which we may well call a practical absurdity of our own creation, has always been admitted, and hence the remedies which have been suggested, the failure of which may, in most cases, be traced to a neglect of the mode in which the air is introduced. It remains however to the objectors of the present day, to deny the principle of admitting air, by a separate channel, and behind the

bridge, on the assumed ground that it creates the evil of not regulating the supply to the demand. Had the old plan of confining the admission of air to the ash-pit and bars been perfect in the way of regulation and adjustment, such objections might have had their weight; we have seen, however, that it is the reverse of regulation and the very antipodes of equalling the supply to the demand.

That there is some self-adjusting principle in the nature of combustion, (when not counteracted,) by which the quantity taken up or absorbed by the gas, shall, to some extent, correspond with the quantity required, we are warranted in believing, seeing how the varying quantities required for the combustion of the same gas in our lamps are supplied. We see, in the argand burner and solar lamp, how, by merely aiding the introduction of the air in a peculiar manner, we effect a more complete combustion, and by a species of self-adjusting appropriation. Why then condemn, against the evidence of our senses, the introduction of air to the furnace, on the same principle which is so successful in the lamp? Would not the inductions of common sense rather suggest an inquiry into the causes of such success, and whether there be not something peculiar-not in the air, or the gas-but in the mode of bringing them together? This consideration, however, belongs to another branch of the subject, and we are now but tracing the practical results in a furnace as they are presented to our view.

It will be admitted that effecting an absolute harmony between the demand for and the supply of air, is a desideratum of the greatest importance. If this, however, be not practicable, can we make no approach towards so desirable an object? At least, can we not correct the evil of the old system, which by diminishing the supply as the demand increases, produces an effect the very opposite of that which we are in search of? To this

then let us direct attention, rather than by unmeaning cavil and theoretic objections, discourage useful investigation, and retard practical improvement.

It is manifest that the increased demand for air, on the new charge being thrown on the furnace, has been caused by the great developement of gas from such charge. It is also manifest that as the increased supply to meet such de