and that further wheels of this kind will be sent over for trial under English rolling stock. We have samples of the iron from which these wheels are cast, and it is of magnificent quality. The fracture is a rich dark gray, medium-grained, and shows great toughness, the particles appearing to have been irregularly torn, rather than broken short off. The specific gravity ranges from 7.25 to 7.3185, and the tensile strength from 32,000 to 35,102 lbs., or, say, fourteen and one-half to sixteen tons per square inch. The iron is that known as the Salisbury cold-blast charcoal iron, and is worth about £10 per ton in New York. - Engineering, 1866.

STEEL LOCOMOTIVE WHEELS.

Railway companies in England have for some time largely employed steel as a substitute for ordinary iron, for the working parts of locomotives, with most satisfactory results. On heavy freight-lines it has been found that with the ordinary iron tires, or the engine-wheels, the distance run was not more than 90,000 miles, - in many cases not more than 60,000 miles, - and the wheels require to be taken from under the engine for every 20,000 or 30,000 miles run, for repairs and "turning up." In the case of steel tires, however, the wheels will run 100,000 miles, before they require "turning up " or repairing. The " Railway News" states that the result of a very careful examination of the effects of wear, lead to the opinion that these wheels will run from 350,000 to 500,000 miles, or equal to some twelve or fifteen years' work of a daily average of about one hundred miles. The difference of cost between the two metals is not great; in the one case it ranges from £40 to £45 per ton, while the steel is about £55; the cost of labor in placing the tires being about the same in each case. It is confidently stated that a similar saving in point of wear may be made by substituting steel for iron in boilers, axles, cranks, eccentrics, and other portions of locomotives. Mechanics' Magazine, April, 1865.

HIGH TEMPERATURES PRODUCED BY GAS.

There is no reason why the very highest temperatures should not be produced by the combustion of gas; and in reality it has been found that by regulating the supply of air and gas, and preventing the caloric evolved from being dissipated, a very great heat may be obtained. For this purpose, it is only necessary to combine a number of flames produced by Bunsen burners, but without permitting them to completely penetrate one another, and causing a draught by means of a sheet-iron tube about two metres high. The heat, by a proper management of the flame, and by the products of combustion being made to act on both sides of the refractory envelope within which the substance to be operated on is placed, becomes extremely powerful. With such an arrangement it was found that two square metres of gas, burned under a pressure of five or six centimetres of water, fused six hundred and seventy grammes of silver in fifteen minutes; and

five hundred grammes of very infusible cast-iron in thirty minutes. Intellectual Observer, March, 1866.

PETROLEUM AS A FUEL.

Mr. C. J. Richardson has so far succeeded in utilizing petroleum as a steam fuel for marine engines, that at a recent trial of his improved petroleum boiler, at Woolwich Dockyard, the most favorable results are said to have accrued. It is reported that the boiler vaporized about three thousand pounds of water, at the rate of thirteen and a half pounds to one pound of fuel, in about three hours, the lowest class of English coal being used. Petroleum is the exact opposite of coal; it is slow burning, permitting little waste, requiring a small fire-box and no ash-pit. An ash, the petroleum coke, forms itself on the surface of the grate, and is of great service to the combustion. After a few tons of the oil are burned, this would become several inches in thickness, and form a porous grate better than any that could be manufactured for the purpose. ·Mechanics' Magazine, Jan., 1866.

SIEMENS' REGENERATIVE GAS FURNACES.

Although this furnace has been described in the "Annual of Scientific Discovery" for 1864, the facts elicited are so important and suggestive, that attention may be called to them again. The points of special interest are, 1st, the extremely high temperature which can be obtained, and which, in fact, is limited only by the nature of the materials employed in the construction of the furnace; and 2d, the possibility of employing at will either an oxydizing or a reducing atmosphere. The furnaces have been applied to puddling and re-heating, and, no doubt, will soon be extensively used in metallurgical processes. It is well worth while to determine by direct experiment, on a large scale, whether the rich iron ores of Lake Champlain, Lake Superior, and Missouri, cannot be directly reduced to the metallic state by heating them to a sufficiently high temperature in the chamber of a Siemens' furnace, and then changing the gaseous mixture in the furnace to a reducing condition. This would, in fact, be blooming upon a large scale, and would perhaps avoid the inconvenience and expense of blooming in the small way, which, in spite of the superior quality of the iron produced, has been almost wholly superseded by the cheaper process of puddling. Experiment only can determine whether fluxes can be used with advantage in blooming in this manner, when poorer ores are employed. Ores of copper could doubtless be roasted and reduced in furnaces of this construction, and, with some additions to the original plan, the sulphurous acid formed during the roasting might be directly converted into sulphuric acid in leaden chambers. But it is for the metallurgy of iron that the new furnaces will probably be found most advantageous. As the temperature attainable is extremely high, it may even be found practicable to melt the malleable iron formed by the direct reduction of the ore,

the walls of the fire-chamber being lined with lime, as more refractory than fire-clay. But even if this should not be realized, it is at least probable that the earthy impurities of the ore would be reduced to a peculiarly fluid condition, so that the blooms could be easily treated under the hammer and brought into the form of malleable iron. There is hardly a branch of manufacture in which heat is employed upon the large scale in which furnaces on the regenerative principle would not find an application. Small gas furnaces could be made upon the same principle, for laboratory use and for various processes in the arts, using ordinary city gas as fuel, instead of gas produced by a special furnace. The high temperature obtained in Gore's gas furnaces appears to be due to the heating of the air and gas before they mix in combustion. — American Journal of Science, May, 1865.

SMOKE-CONSUMING APPARATUS.

M. Emile Martin, in a work published in London, in 1865, describes his improved steam-generating apparatus. The leading idea is the use of two fire-places, and, therefore, double firing. From the upper part of each fire-place tubular flues rise up to a chamber within the boiler; from this chamber descend one or more flues, at whose lower portion is a perforated grating of fireclay, on which there is constantly kept a quantity of glowing fuel; below this is a space communicating with a chimney into which the products of combustion are exhausted by means of a fan or other contrivance for producing a draught. In order to try the plan, the Great Eastern Railway Company applied it to an old locomotive, working as a stationary engine at the Stratford station. This old boiler, with M. Martin's apparatus, was able to provide with steam an engine of a hundred horse-power, and with an economy of thirty-three to forty per cent. over the fiftyhorse boilers close by. These boilers are still in good condition, and the advantage over them, obtained by the old locomotiveboiler furnished with this apparatus, seems mainly due to the consumption of smoke obtained by the latter. The work also contains a report from two engineers, showing that, by means of this arrangement, ten pounds of water were evaporated by the use of only one pound of fuel, exclusive of the fuel used for getting up steam. A new locomotive on this plan was in process of construction. - London Mechanics' Magazine, Feb., 1865.

AMORY'S SMOKE-CONSUMING FURNACE.

Mr. Jonathan Amory, of Boston, Mass., who has devoted many years to the perfection of a smoke-consuming furnace, has recently issued a pamphlet on the subject, from which the following

are extracts:

"The subject of the economical application of heat for the production of steam may be said, without exaggeration, to be the most important for the consideration of every large manufacturing, agricultural, and mercantile community; and one, too, the

most neglected, as far as practice is concerned. The cost of fuel annually required in the United States for mechanical and manufacturing purposes, and principally for the generation of steam (leaving out of the calculation the immense amount used in domestic economy), has been estimated at $60,000,000. Estimating it at only $50,000,000, any improvement which would save even one-quarter of this sum (or $12,500,000) would add so much tơ the national wealth, by largely extending many branches of productive industry, and rendering profitable many enterprises now languishing and poorly remunerative. The many different kinds of furnaces and boilers now in use, in this country and in Europe, like the many infallible cures for dangerous diseases, only show that all are imperfect, and that no one is entitled to the full confidence of the public.

"No one can deny that the prevention and consumption of smoke are very desirable, both from a sanitary and an economical point of view. The principles of chemistry, and practical experience, show that the prevention of smoke and the perfect combustion of fuel are synonymous; or, in other words, that smoke is carbon escaping unconsumed from the chimney, and so much lost fuel. Hundreds of thousands of dollars are thus annually thrown away, at a time, too, when strict economy ought to be the rule. It is not exaggerating to say that one-half of the fuel used for generating steam in this country would, with the use of proper furnaces, perform the same service now derived from the whole, as at present used.

66

The idea that we cannot have fire without smoke is not true of a well-constructed furnace, after the fire is once well kindled. Many attempts have been made to solve this smoke problem, but all have failed, more or less completely, from inattention to the laws of perfect combustion, the variable products according to the fuel, the want of system in the management of the furnace, and, above all, from the failure to bring the due proportion of air into contact with the combustible gases. Various devices have been employed, both in Europe and this country, to arrest or delay the gases of imperfect combustion in their passage to the chimney, by different kinds of bridges, generally of fire-brick, behind and near the fire; and various imperfect attempts have been made to admit a certain quantity of air behind these bridges, to secure a more perfect combustion, diminishing, however, to a certain extent, the heat by the admission of the cold air. Even with these, in England, there has been secured a saving of thirtythree per cent.

"As a preliminary to perfect combustion, a proper amount of grate-surface, and a boiler of sufficient size, are of the first necessity; as, with too small a fire-surface, and a boiler so small as to require constant forcing, perfect combustion and its resultant economy are out of the question."

After showing the proper proportions of grate-bars to boilersurface, the heating properties of various kinds of fuel, and the proper amount of air to be supplied for perfect combustion, he goes on to say:

"In the best double-flued and double-furnaced English boilers, about one square inch of permanent air-opening, behind the bridge, is necessary for every square foot of grate-bar, air passing as usual through the grate-bars from the ash-pit, and often through holes in the furnace door. In the 'Amory' furnace, a three to six-inch pipe is ample, conveying heated air to the cavity of the curves, the ash-pit door (and the holes in the furnace door, if necessary) being closed, after the fires have been well kindled, a very much less open air-space than in the best English furnaces. With an insufficient amount of air, if bituminous coal or pine wood be used, the too-compact fire being supplied only through the grate-bars, the gases pass quickly and unconsumed through the flues, with a thick volume of dark smoke by the chimney. Enough air only should be admitted to convert the carbon of the fuel into carbonic acid by its oxygen, the hydrogen being converted into water in the shape of vapor. In this condition of a furnace, the products of combustion become invisible, so that we may justly conclude that smoke is the measure and gauge of imperfect combustion.

"Some furnace-makers admitted air through the furnace-doors by a few large, or many small openings; others, behind the bridge; but, in every case, cold air. In the Amory' furnace, at a proper distance from the fire, is placed a combustion, or reverberating charaber of concavo-convex hollow iron curves, concave toward the fire, when a single one is used, and the length of grate-bars is sufficient to admit the loss of so much fire-surface; the curve on the level of and just behind the fire; concave toward each other when two are used, above and at a greater or less distance from the fire. Between the curved iron plates (best made of boiler-plate one-eighth or one-sixth of an inch thick) is a hollow space, communicating underneath with each, into which air is received, heated by passing through a pipe introduced through the boiler, or otherwise, the air communicating with the firechamber by several openings on the concave surfaces. It is also necessary that the anterior curve be lower than the posterior, to insure and facilitate the revolving of the gases in the chamber. "The principles of this furnace have for several years been applied to locomotive, stationary, house, and steamboat furnaces, with the most satisfactory results, as the testimonials appended will show; and it is confidently recommended to engineers, machinists, and builders, as meriting all that is claimed for it in the saving of fuel and the consumption of smoke.

the

"This furnace neither draws the air through the fuel by the production of a partial vacuum behind it from high temperature and rarefaction in the chimney, nor forces air through it by compression, or other mechanical contrivance, before the fuel,first exceedingly wasteful, and the second inconvenient and unnecessary; but it secures a most perfect combustion and freedom from smoke, by the retention and reverberation of the gaseous products in a circular chamber, in which a due amount of heated air is introduced, converting, in this way, much carbonic oxide (usually escaping by the chimney) into carbonic acid gas, and thus saving a great amount of caloric.