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appears to be the great desideratum in its manufacture and application. Were this realized, war might be carried on as in the days of Homer, and other chieftains raise the brazen spear. The Egyptians unquestionably possessed this lost art, and worked with copper tools upon granite.

To steel the attention of the French has long been directed with considerable effect in articles of ornament, and also others. The tempering of it is treated with considerable power by Jobard, and we shall state all we consider important in his paper on this subject. With respect to what passes in the mysterious process of tempering steel, the facts are as follow :—A bar of steel after having been tempered to its hardest pitch, being placed on redhot iron or burning coals, undergoes chromatic changes, into straw colour, gold colour, purple, violet, dark blue, light blue, gray or watery hue. If we dip this bar in cold water while its surface undergoes one of these changes, the steel acquires different degrees of hardness corresponding to the hues above described. Skilful workmen judge by the eye of the degree of heat which their steel ought to receive before plunging it into water. They raise it to cherry-red heat, which gives it its highest hardness, and then withdraw it. It is not necessary that it receive its second hardenivg on coals, or in liquified metals, but in oil; for there is no hardening which requires a higher teniperature than we obtain from boiling oil. Oil in a state of ebullition contains more heat than melting lead. Oil does not boil under 521 centigrade degrees, but lead melts at 312°, and pewter at 227o. M. Themar, of Brussels, tempers all his needles by burning oil. It is curious, but yet true, that a treatise on the tempering of steel is not to be found either in France or England. Electricity is involved in this process as in the formation of magnets, but the hardness acquired by steel at the instant of its cooling down, M. Jobard thinks, favours the crystalization of carbon, which would become diamond itself, were it pure from the interposition of iron. Taking water, however, at mean temperature, and steel at cherry-red, for our starting-point, we shall obtain a temper harder or softer in proportion to the cold or heat. The immersion of steel at red heat in snow and ice is attended with excellent success, but very cold acidulated water has given greater bardness and stiff temper. Pure nitric acid renders steel brittle when we carry up the temperature to cherry-red, but if we dip as the steel reddens, the effect is excellent, according to Reaumur. And this principle of tempering at the lowest possible heat at which steel bardens is now getting greatly into use. Passing from the anvil to the hardening process, is completely disappearing in practice. If steel is immersed in mucous or

VOL. XXVII. NO. LIII.

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soapy bodies, the temper is too tender, by reason of the steel surrounding itself with a mucous covering, which preserves the metal from immediate contact with water and softens the affection. In Switzerland they temper their hatchets by passing them through grease before they plunge them into water. The joiners of this country temper their gouges and scissars by plunging them in mutton-fat; others place oil over the water in which they plunge their steel. All this has no other effect than getting rid of harsh temper, as they call it. The scythes are heated at the forge, and in charcoal, to a white heat; they then dip them in a mixture of beef, mutton, and veal fat; then clean them afterwards and pass them in the flame until they trace the bluish hue. This is a soft or retarding tempering. Workmen understand well that on surrounding a bit of steel with fat, and placing it on burning coals until it ignites, that they obtain a good result generally. Practice has proved to them the degree of heat when oil takes fire, and also that which gives the retardening requisite for certain springs and steels. Cutlers do not wait so long; they only stay until the oil smokes. A workman of Liege, Brisart, is in possession of a superior temper for files. He sells them dearer, but they last four times as long as the others, and their remains, shortened as knives, are capable of cutting iron and copper without blunting their edge. The triangular files, for saws, of Raoul, are also capable of marking even the best English files. These workmen ought to be nationally recompensed and their secrets diffused. The trial to which the files of Raoul were submitted, appears to have been extremely fair. The English files wbitened in seven distinct instances, while Raoul's were unchanged. It is affirmed, on the authority of Mr. Gill, that their manufacture is as follows, which we give, though M. Jobard does not mention it :-Two pounds of mutton suet, not rendered, but only chopped small, two pounds of hog's-lard, two ounces of white arsenic, powdered. These being put into an iron vessel with a cover to it, must be boiled until a handful of mouse ear, Hieracium pilocella, fresh gathered, and which had been put into the mixture at first, shall become crisp and float on the surface of the liquor, a proof that all moisture is driven off. This operation, as well as quenching any article in it, in order to harden it, must be performed under the hood of a smith's forge-hearth, so as to carry off, as much as possible, the noxious arsenical fumes which arise, and the operator ought to close his mouth and nostrils to prevent his inhaling them. It is somewhat singular, but an air tempering is all that the celebrated Damascus, and we believe we might also add the Delhi, blades receive. The wonderful hangs over all Eastern actions, but here the assertion, that these celebrated sabres are tempered by cleaving the north wind with them, is not untrue. In the former, the sabre is simply brought to a red heat, and presented to an opening through which the air streams with great velocity, and the wondrous temper of these blades will enable them to cut into most European sabres without turning their edge. The Indians prepare a steel of admirable temper from the old iron hoops of barrels from Europe, which they bury to increase the oxydation, and to purge the metal, as they say. Their kreese or national poignard, as well as their sabres, are fashioned with much skill, and do not yield in hardness and elasticity to the Damascus blade. An ancient Turkish legend relates, that one day a warrior being without arms for an ensuing combat, snatched from the forge a yatagan, red hot, and urged his horse to a gallop, flourishing the blade around his head, which air cleaving gave it an excellent temper. The material of the Damascus blade, now much used by our own cutlers, the celebrated Wootz has conferred on our language the term damusk, from the wavy character of this celebrated steel. The meteoric iron presents, when wrought, the same appearance. Tavernier states, that the steel susceptible of being damasked came from Golconda, obviously alluding to Delhi blades. Professor Crevelli has succeeded in an excellent imitation of these celebrated oriental sabres. We extract from the Allgemeine Militar-Zeitung his method.

" A long flat piece of malleable steel, of about one inch and a half in breadth, and one-eighth in thickness, is to be first bound with iron wire at intervals of one-third of an inch. The iron and steel to be then incorporated by welding, and repeated additions (from 10 to 20) of iron wire are made to the first portion, with which they must be finally amalgamated, This compound material is then to be stretched and divided into shorter lengths, to whicb, by the usual process of welding, grinding and tempering, any shape may be given. By filing semicircular grooves into both sides of the blade, and again subjecting it to the hammer, a beautiful roset-shaped Damascus is obtained; the material can also be made to assume any other form. The infusion by which the figures are made visible, is the usual one of aquafortis and vinegar.”

These sabres have been submitted to the following severe tests cutting off hobnails, which had been placed in great numbers behind each other ; cuts upon a strong iron plate and many folds of cloth ; horizontal blows upon a wooden table; and finally, like the celebrated Andrew Ferrara blades, powerful bending upon both sides. Out of two hundred and ten blades, examined by a military commission, and each of which was required to perform thrice on iron and twice against a flat wooden table, not a single one snapped or had its edge indented. In Prussia and Silesia an equally valuable manufacture exists. The process appears similar to the

Andrew Ferrara, which probably obtained its excellence from the welding. Andrew Ferrara is said to have carried one of his blades wrapped in his bonnet. Elasticity and power of edge appear to be the common property of the Andrew Ferrara, the Damascus and Delhi blades, together with those at Milan manufactured under the direction of Professor Crevelli. Interlamination is probably the peculiar and yet unfathomed mystery. Andrew Ferrara is commonly supposed to have welded the blade of alternate layers, about two or three lines thick, of iron and steel, which approaches closely to Professor Crevelli's method.

With regard to air tempering, the rude method of the Asiatics ought certainly to yield to the plan of M. Thillorier, who, by his apparatus for congelation, obtains a degree of cold 100" below zero. What then ought we not to expect from this method, if the quality of temper depends on being submitted to a low degree of cold? Thillorier, for thus discovering congelation of carbonic acid, bas become a Chevalier of the Legion of Honour. He has aunounced his intention of liquifying atmospheric air. * On the whole, however, it is more than probable that the entire secret of tempering consists, as Jobard appears to think, in the establishment of some method to heat equally the masses of steel in all their parts, and in the preparation of an oil bath raised to a temperature correspondent to that previously bestowed upon each mass. The masses might then be withdrawn, or left to cool in the oil. Cutlery, arms, carriage springs, might all be treated in this manner. The skill of some workmen, particularly those of Solingen, is now so expert, that they can temper swords and foils at a single essay. With respect to iron itself, the best comes from Sweden, the next from Belgium, and the third in quality from England.

Lead. France and Belgium are poorly supplied, internally, with this valuable material. Britanny contains a mine of lead, from which Notre Dame was probably sheeted, but it is not worked. Silver was also a product of this mine, and, report says, in considerable quantities. England and Spain supply their wants. Belgium contains only one mine, Vedrin, and this, report says, exhausted. Fifteen millions of kilogrammes of lead are supplied to France, and one million to Belgium, from these sources. The working of either the French or Belgian mines is rendered completely nugatory by the immense quantity poured

* We are not certain that this bas not been achieved already by Mr. Perkins. This gentleman placed a glass tube in the compressing engine under a pressure of 28,000lbs. to the square inch, and when it was taken out there was a small globule of fluid at the bottom of the glass and 110 appearance of air in the tube. Dr. Wollaston and Sir H. Davy considered this the liquefaction of atmospheric air.

in at a lower rate from abroad, far below the price at which they can produce it from their own mines. M. Jobard, who is a man of peace, takes every opportunity of deprecating the use of this material for any other than peaceable objects.

There is a curious calculation in Gassendi, which proves, by contrasting the supply of this material to the Emperor Napoleon with the expenditure, that each man killed in one war, the Austrian campaign, had cost his weight in lead. Amid the curiosities of the Exposition under this material, is the process for soldering lead by lead of the noble plumber Baron Debassyns de Richemont. The remarks made by Jobard on the perpetual fires caused by plumbers, who burn recklessly cathedral after cathedral from their carelessness, are highly judicious. They unquestionably should never be admitted into any building except under a surveillance of a very different character to that exercised at present.

Zinc- is the next material under consideration. The excellence of the zinc de la Vieille Montagne does not escape observation from our author. The thinness in which this material is manufactured meets with just censure. In England, the generality of zinc articles are from this cause totally useless within a few months of erection. In Russia, zinc ornaments in lieu of bronze are very common. Zinc bas not much aided the lithographic artists: zinc plates for engraving, however, our author thinks may be made available. This metal, heated to 210° centigrade, becomes friable, and can be reduced to a fine powder, which, with the aid of oil, gives a colour of extreme utility to protect houses from the variations of the atmosphere, and will supersede the use of white-lead.

The immense apparatus for boring into the surface of the earth comes next under consideration. This apparatus for the acupunction of the globc, as constructed by MM. Degouse and Mulot d' Epinay, costs 80,000 francs. M.Jobard treats this subject with some pleasantness, not being himself a capitalist, and frankly owns, that when a hospital could be constructed at the same cost, that a well, if not the deepest bore in the earth, assuredly the dearest to the paymaster, is not the most cheering of prospects. Champollion states boldly that he was convinced that Moses, before passing into the Desert, had provided himself with instruments for digging wells. The Pacha has recently, at the suggestion of the French, sent for an apparatus of this description, and designs digging wells in the Desert, for the convenience of travellers. In the Oasis of Ammon many pierced wells are extant of high antiquity. That extraordinary nation, the Chinese, has used the sound for this purpose for a very long

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