Maesteg Iron-works, near Neath, in South Wales; obtained from a mixture of clay iron-stone and Cumberland red ore, by means of coke and heated air. It was silvery white, without signs of crystallization : specific gravity, 7.467. The third specimen was a fragment of a razor forged in the author's presence, in the workshop of Mr. Rodgers, of Sheffield, of the specific gravity of 7.92.

Several gentlemen, among whom were some connected with the iron trade, expressed a high sense of the value of this communication; from which it appeared that the peculiarities of Swedish iron, in a great degree, depended on the presence of arsenic, and those of Russian iron on the presence of phosphorus.-Literary Gazette.

SMELTING IRON.

M. TEPLOFF, mining engineer of Russia, states that, in the Uralian mountains, where many iron mines are worked, fourteen pounds of iron are obtained by a consumption of the same quantity of fuel, the quantity and rapidity of the air which enters into the combustion being properly regulated; whereas, only from four to six pounds of iron are obtained when the blowers are badly managed. In an experiment, it was found that 100 cubic feet of air, under a pressure of two inches of mercury, have produced the same effect as 200 cubic inches of air, under a pressure of one inch; but with this difference that, in the latter case, the consumption of fuel was double that required for the former. M. Teploff farther states that a furnace had produced 22,000 pounds of iron in 24 hours, with a consumption of only 16,000 pounds of fuel; whilst, before the proper regulation of the blast, double the quantity was required to produce an equal quantity of iron. According to the same engineer, the results thus obtained are more economical than those by the hot blast. Recueil de la Société Polytechnique.

IMPROVED METHOD OF CASE-HARDENING IRON.

THIS discovery consists of the employment of ferrocyanodide of potash (prussiate of potash), the crystals of which are reduced to a coarse powder; the iron articles being well cleaned off, heat them at the forge to a bright red, take them out and strew some of the prussiate of potash over them, which will immediately fuse and spread upon the surface; return the article to the fire, and restore the heat, when sudden quenching in cold water will give the required hardness. By this means, case-hardening is more effectually completed in two minutes than it could be in two hours by the old method; besides which, part of any iron instrument may be case-hardened, while the remaining portion continues in its original state. - Mr. Baddeley; Mechanics' Magazine; abridged.

TENACITY OF IRON.

MR. TELFORD made an interesting series of experiments on the strength of wire, an account of which is found in Mr. Barlow's treatise on the strength and stress of timber, page 254.

The same gentleman made various experiments on bars and bolts of iron, detailed in the same work.

He also attended to the successive elongations of bars under different weights, and noted the amount of recoil or contraction when relieved from strain.

Captain S. Brown has also furnished to Mr. Barlow a series of highly interesting experiments on the strength and elongations of iron bolts.

The mean result of three experiments by Capt. Brown on cast iron was 18,564 pounds to the square inch.

Mr. Hodgkinson has published, in the third report of the British Association, three results of experiments on the same material, which make its strength 17,136 pounds per square inch, while the three experiments of the committee of the Frank. Inst., which were considered fair, indicated in the bars a strength of 20,834 pounds.

Mr. Brunton and Mr. Brunel, have each engaged in this interesting department of inquiry, and given the results of experiments on a large scale, which will be found in the work of Mr. Barlow already cited.

Mr. E. Martin, formerly of the Polytechnic school, has given in the Annales des Mines, Vol. V., a series of experiments executed in France, under the orders of M. Barbé, on round rods of iron, eighteen or nineteen feet long, and two inches or more in diameter, made with a view, in part, to determine the recoil when released from strain, and the actual amount of elongation under each weight to which it was subjected.

In the same volume of the Annales des Mines, M. Vicat has a paper referring to, and controverting some of the positions of Mr. Martin, but not affecting the statements respecting the experimental operations just referred to.

In the same work, Vol. VI., are contained some interesting statements by M. Payen, respecting the manufacture of wire, in which the relative ductility before and after annealling, is established.

In the Annales de Chimie et de Physique, for Sept. 1833, is a valuable paper by M. Vicat, showing the influence of time on the gradual extension of wires under different weights. Each of his experiments occupied nearly three years.

The quantity by which iron extends under different degrees of tension, and on the recoil when relieved from strain, has been examined by Professor Barlow. See Journal Frank. Inst., Vol. XVI. p. 124, &c. The relation between the effect of straining and elongating a bar by mechanical means, and that of expanding it by heat, is also noticed.Note to the Report of the Franklin Institute on the Strength of Steam Boiler Materials.

STRENGTH OF CAST IRON.

THE Council of the Institution of Civil Engineers have awarded a Telford premium to Mr. Bramah, for his series of experiments, on the strength of cast-iron. These experiments, undertaken with the view of verifying the principles assumed in the work of Tredgold, on cast-iron, surpass every other series in number and accuracy, since two similar specimens of each beam were subjected to trial. The principles sought to be established by these experiments are that, within the elastic limit, the forces of compression and extension are equal; and that, consequently, a triangular beam, provided it be not loaded beyond that limit, will have the same amount of deflection, whether the base or apex be uppermost; and a flanged beam the same deflection, whether the flange be at top or bottom. This communication was accompanied by some observations by Mr. A. H. Renton, pointing out the agreement which subsists between the experiments and results of the formulæ of Tredgold. - Mechanics' Magazine.

PURIFICATION OF COPPER.

MR. L. THOMPSON, of Lambeth, has received a gold medal from the Society of Arts, for a new method of purifying copper, which has long been a desideratum. This method is so simple as to require no particular management on the part of the workmen.

Take of impure copper

Copper scales

100 parts;

10 parts;

Ground bottle glass, or any other flux, 10 parts;

heat the whole together in a covered crucible, and keep the copper in a state of fusion for twenty minutes or half an hour, at the end of which time it will be found at the bottom of the crucible, perfectly pure. The quantity of copper scales must vary in proportion to the supposed impurity of the copper to be operated on; but the proportions here given will be found to answer very well for the average kind of English copper. The explanation of this process is sufficiently simple: the impurities contained in the copper, consisting of iron, lead, arsenic, &c., combine with the oxygen contained in the copper scales, and form oxides or acids, which are dissolved by the flux, or fly off in a gaseous form, leaving the purified copper, together with that reduced from the scales, at the bottom of the crucible; consequently, the copper obtained exceeds that put into the crucible, the gain generally averaging from one to one and a half per cent. In this way, Mr. Thompson obtained perfectly pure copper, from brass, bell-metal, gun-metal, and several other alloys containing from four up to fifty per cent., of iron, lead, antimony, tin, bismuth, arsenic, &c. -Transactions of the Society of Arts.

PRINTERS' METAL.

A TYPE-FOUNDER of Clermont, named Colson, has patented a new material for printing types, which is harder, capable of more resistance, yet less expensive, than the ordinary composition of lead and antimony. Colson asserts that types of his manufacture will serve for punches in striking matrices, and that they will last ten years without being more worn than the usual composition is in one year. - Foreign Monthly

Review.

MINES OF CORNWALL AND DEVON.

If we estimate the value of the metals annually raised in Great Britain and Ireland at about 10,597,000l., and consider that of this sum the iron amounts to 8,000,000l., the value of the remaining metals would be 2,597,000l., of which Cornwall and Devon would furnish about 1,340,000l., or more than one-half, leaving 1,257,000l. for the value of all the metals, with the exception of iron, raised in other parts of the United Kingdom. The two great metallic products of the district are copper and tin: of the former it yields one third, and of the latter, nine-tenths of the whole supply of copper and tin furnished by the British Islands, and all the countries of the continent of Europe.Report of the Geological Society.

NEW LIGHT FOR LIGHTHOUSES.

A SYSTEM of illumination for lighthouses has been invented by a serjeant-major in the Austrian artillery, named Selckonsky. The apparatus consists of a parabolic mirror, sixty-two by thirty inches, with a twelve-inch focus; the light being produced by a new kind of wax candle. The invention has been tried at Trieste, where it illuminated the whole of the port and neighbourhood equal to the moon at full; and at the distance of six hundred yards, the finest writing could be read.-Mechanics' Magazine; abridyed.

ECONOMY IN GAS LIGHTING.

On March 27, Sir John Robison submitted to the Society of Arts, for Scotland, a paper pointing out the most economical mode of burning gas, by peculiar construction of the burners, and the proper size and fitting of the chimneys, and the disuse of obscured shades. It is found to be more economical, with any burner, to burn the gas to the full height it can attain without smoking. If a small quantity of light be wanted, it is better to use a smaller burner than to reduce the flame of a large one. The best effect of an Argand burner is attained when the holes are all of one size, so that the flame should be of an equal height all round. The paper also describes the method of burning gas in street lamps, pointed out by Sir John Robison, and now very generally used in Edinburgh, so as to prevent the moisture from being condensed on the inside of the globes, and rendering the light obscure.-Jameson's Journal.

DR. URE'S EXPERIMENTS UPON THE COST OF THE LIGHT AFFORDED BY DIFFERENT LAMPS AND CANDLES.

THE author, having instituted a series of experiments to determine the advantages of Mr. Parker's new hot oil lamp, adopts as the standard of comparison the French mechanical lamp, in which the oil is raised by machinery, so as continually to overflow at the bottom of the burning wick. The relative illumination was determined by the well known method of the equal intensity of shadows, and verified by that adopted by Professor Wheatstone; namely, by the relative brightness of the opposite sides of a revolving ball.

One peculiar feature of the new lamp is its bell-mouthed glass chimney, above which is a chimney of iron, with a parted diaphragm for the purpose of causing a certain portion of the heat of the flame to reverberate against the interior cylindric cavity of the oil cistern. The bell mouth is formed in a mould, and is far better suited for producing a steady flame than the rectangularly constructed chimney of the mechanical lamp. The intensity of the shadows from the mechanical lamp, and the hot oil lamp, of a wire a few inches long and of the thickness of a crow quill, was equal at a distance of ten and eleven feet respectively; their relative illuminations being as the squares of these are, as 100 and 121 respectively; and the consumption of the best sperm oil was 15-2 and 11.6 grains per minute: the relative cost of illumination for this oil would thus appear to be fifty per cent. in favour of the new lamp. On trying southern whale oil, the cost of illumination appeared to be about one-third that of the mechanical, and one-half that of the hot oil, lamp with sperm oil. The author tried many other substances, and, comparing the various illuminations, concludes that the hot oil lamp with southern whale oil affords an economy of light nearly 12 times greater than stearine or German wax candles, 71⁄2 times greater than tallow mould, 11 times greater than cocoa nut, 81⁄2 times greater than Palmer's, 171⁄2 times greater than spermaceti, and 18 times greater than wax, candles.

The author had also compared the illumination produced by one of the Fresnel lamps deposited at the Trinity House. The lamp consists of four concentric circular wicks, placed in a horizontal plane; the innermost being ths of an inch, and the outermost 3 inches in diameter. The intensity of the shadows from this and from the mechanical lamp were equal at a distance of 13 feet 3 inches, and 4 feet 6 inches respectively; taking the squares of these, the Fresnel lamp gives about 9 times the light of the mechanical, which latter may be assumed as equal to that of 11 average wax candles. On comparing one of the best Argand lamps with the mechanical, the former was to the latter as 10 to 11; so that the illumination of the Fresnel lamp, instead of being, as has been asserted, equal to 40 Argand lamps is not equal to more than 9.6 of those lamps. In the Bude light, a small stream of oxygen is sent up through a small tube within the burning wick, which is ths of an inch in diameter, and the flame