generally speaking, includes all cutting tools made of steel. Various countries and cities have at different periods excelled in the manufacture of some particular article; as Damascus for a beautiful sword blade, which has hitherto baffled all attempts at imitation. If this blade is made, as is commonly supposed, by welding together extremely fine wires of iron, steel, and gold, laid alternately on each other, the dexterity required is such as must astonish the most active and experienced workmen of other countries. The peculiar wave, usually called the water, so universally admired, is effected by the application of a weak acid to the polished surface of iron and steel; at Damascus sulphate of alumine is used; but any dilute acid seems to answer the purpose. The cutlery of England is deservedly held in high estimation in every part of the civilized world. The finer articles, as razors, penknives, scissors, and surgical instruments, are made of cast-steel, that is, steel purified and equalized by fusion. Dexterity and nice attention on the part of the workman to a variety of circumstances, as the quality of the steel, nature of the fuel, accuracy in the processes of hardening and tempering, and many other minor considerations, are essential to the production of a good cutting instrument. Wootz, a steel from India, has been most successfully employed. For table-knives, and all cutlery of that description, sheer-steel is generally used; the tang and shoulder of the table-knife and fork are iron, united to the blade by welding.

The principal manufactories in England are at London and Sheffield; the former are chiefly confined to articles of fine cutlery, as razors, penknives, and the like, and the making of surgical instruments belongs almost exclusively to it. This important branch of the trade is there carried to a very high state of perfection. Describing the process of making any one blade, a razor for instance, will suffice for most other articles of cutlery. The workman being furnished with a bar of cast-steel, forges his blade, using a forge similar to that of a smith; the brow of his anvil and his hammer being convex, enable him to give to the blade a degree of concavity which greatly facilitates and accelerates the subsequent work of grinding. The blade is then fashioned more exactly with a file. It is again heated to a cherry-red colour, and instantly quenched in a cold fluid, commonly water. In this stage the blade is extremely hard, and requires to be tempered; a process usually performed by brightening one side, then heating it over a fire free from flame and smoke, until the brightened surface assumes a straw colour. It is again quenched, and is then ready for grinding. As this method of tempering is liable to many objections, a tempering-bath, with thermometer, will be described, the superior advantages of which appear too obvious for comment. But it now remains to grind and polish the blade; and this is so generally understood as hardly to need explanation. The diameter of the stone is chosen according to the degree of concavity required; and in polishing, care is necessary to avoid heating the blade by friction, which would render it useless. In London, the blade is generally the production of one workman, who is accountable for the whole manipulation, and who, if the work is faulty, can transfer no blame to another. At Sheffield, by division of labour, and the local advantages of coal and water to carry on extensive machinery, more dispatch is attained, and the manufacture afforded at a price considerably below that of London. Numerous attempts have been made to preserve from rust that beautiful polish given to the cutlery of England; the most effectual method is to coat the surface with ethereal solutions of gold; or, what is still better, with muriate of platinum. The late Mr Stodart has given his method of preparing and using these solutions in the eleventh volume of Nicholson's Journal. The process is interesting, independently of its utility, as a chemical experiment, proving the almost infinite divisibility of gold.

It is worth mentioning, that the iron procured from meteoric stones is less susceptible of oxidation than any other. This is most probably owing to its being combined with nickel. Perhaps by artificially combining the two metals, we might obtain an alloy valuable for making instruments that, from necessity, are exposed to moisture. Having objected to the common method of hardening and tempering steel, on which process the excellence of the instruments so much depends, we proceed to state some improvements in that art. The method of tempering with a thermometer was practised by Mr Stodart with perfect success. The following experiment is simple, and clearly exhibits and illustrates this manner of tempering. Let a plate of steel finely polished be so laid as to float on the surface of a bath of mercury, or of the fusible alloy of tin, lead, and bismuth; into the bath plunge the bulb of a thermometer, graduated up to $600^\circ$ Fahrenheit; a good argand will heat the bath. No change of colour will be visible on the steel until the mercury has risen to $430^\circ$, and it will then be so faint as only to be perceptible by comparison with a plate that has not been heated. At $450^\circ$ the colour will be a fine pale straw, which, as the heat increases, will become deeper, and successive changes will take place until it be heated up to the boiling point of mercury.

The advantages of this mode of tempering will now appear obvious and conclusive. If, for example, a straw colour indicates the best temper for a penknife, the blade, or ten thousand blades, are suffered to remain in the bath until the thermometer rises to the number corresponding to that colour, when they are instantly removed from further increase of heat, and, consequently, are all of one temper. After the first experiment, it is unnecessary for the bath to be metallic—oil will answer the purpose equally well.

The late Mr Nicolson, who devoted much attention to the subject of steel, used, in hardening delicate articles, a bath of lead; and a metallic bath may, perhaps, frequently be advantageous in hardening as well as in tempering. A very ingenious method of hardening steel work was communicated to Mr Stodart by Dr Wollaston. The steel is inclosed in a tube, surrounded by the well-known fusible alloy of eight parts lead, two tin, and five bismuth. The tube, with its contents, is heated in a furnace to redness, and then plunged into a cooling fluid. It is afterwards thrown into boiling water, by which the alloy is fused, and the steel is left perfectly hardened, and unaltered by twisting, cracking, or in any way changing its shape. Several experiments have been made to ascertain the best cooling fluid, without any very satisfactory result. A large quantity of water cooled down to about $40^\circ$ Fahrenheit seems to answer as well as anything hitherto tried. Mr Stodart quenched a scalpel in snow and muriate of lime, without perceiving any advantage from the extreme cold.

Having mentioned the wootz of India as valuable for fine articles of cutlery, a brief account of it may be acceptable. For the introduction of wootz into this country, we are indebted to the late Sir Joseph Banks, who submitted some of it to the experiments of intelligent workmen in the year 1795. It was soon found to contain valuable properties. From the cake (as the lump is called in the state in which it is imported) a small penknife was made. The forging was attended with considerable difficulty, partly owing to the unmanageable form of the cake, but more especially to the inequality of the mass; the steely principle being deficient in some parts, whilst others were quite overcharged with it. The penknife, however, proved excellent, and fully justified and encouraged further trials. The inequality in the mass was evidently owing to imperfect fusion, which defect will most likely remain until the Indian steel-maker is acquainted with the formation and management of a proper furnace. If he was likewise instructed to pour the fluid metal into a mould instead of allowing it to crystallize in the crucible, and afterwards to form it into bars with a tilt-hammer, it might be imported in the shape of English cast-steel, and probably at a price not greatly exceeding that article. The Indian account of wootz-making is the following. Pieces of forged iron are inclosed in a crucible with wood, and heated together in a furnace; the fire is urged by three or more bellows peculiar to the country; thus the wood is charred, the iron fused, and at the same time converted into steel. The metal is suffered to crystallize in the crucible, and in this state it is imported. This method of steel-making is neat and ingenious. Its chief peculiarity consists in the wood not being previously charred, its apparent defect in the fusion not being complete. When wootz is submitted to a second and more perfect fusion, it improves so much as scarcely to be recognised. This advantageous change is evidently owing to the whole mass being purified and equalized when in a state as this It is now fit for all purposes of fine cutlery, and is in fact infinitely superior to the best cast steel of England. Is this owing to the use of uncharred wood, or is it not rather, as suspected by Mr Stodart, owing to some particular property of the iron ore of India highly favourable to steel-making? The present state of chemical knowledge does not militate against the supposition, that this steel may be alloyed with one or more of the metals of the earth. We know that a very minute quantity of one metal is capable of producing extraordinary effects by combining with another. Sir Humphry Davy's discovery is a fine example of this, namely, that mercury is rendered solid, and has its specific gravity diminished from 13 to 3, by combination with \(\frac{1}{2000}\) of ammonium. Wootz requires from the workman every attention and care in forging. If overheated it is useless. In hardening, it should be quenched at a cherry red colour, and, in tempering, be heated from thirty to forty degrees higher than our best cast steel. Thus if a razor of cast-steel should be removed from the bath at 460°, one of wootz may remain to 500°, and even then it will be the hardest of the two. Notwithstanding its excellence, this steel has hitherto been little used by cutlers.

We have already mentioned a branch of cutlery, which, from its importance to the cause of humanity, claims some further notice. Knives and other edge instruments for surgical operations, made and finished in the very best manner, are indeed invaluable. When fortunately the form and physical properties of the instrument are exactly to the wish of the operator, he is freed from many embarrassments inseparably connected with a bad or an indifferent instrument, consequently the sufferings of the patient are lessened both in intensity and duration. This truly desirable state of excellence is confessedly of difficult attainment. The choicest pieces of steel should be carefully selected (that from India merits a preference), and the skill and undivided attention of the best workman devoted to the whole manipulation of forging, hardening, tempering, grinding, and polishing. By want of ability or diligence during these various processes, the knife may be rendered totally unfit for the purposes for which it was intended. Finishing the edge, technically termed setting, is a work of much delicacy and skill. Very few acquire this art in the highest degree of perfection. The artist must be in a situation undisturbed by noise or conversation, and his attention must be exclusively devoted to the object on which he is engaged. This very nice and delicate process is performed on a hone moistened with fine oil. The best are from Germany. They are imported in large quantities; not many, however, of superior quality can be selected. The very finest of these are still inadequate to give the last finish to the edge. This is performed on a beautiful green stone, found in some parts of the old pavement of London; the only known material capable of giving perfect smoothness to the points of lancets and other delicate instruments. These points, when made and finished in the very best manner, will perforate a thin piece of leather, by which they are usually proved, with such ease and facility, that no more resistance is sensibly felt, or noise made, than would be if the point was dropped into a fluid, as water or oil. Nothing short of this proof of excellence is satisfactory; mediocrity cannot, at least ought not, to be admitted. These observations apply generally to every description of knife used in surgery; but the nature of each particular operation should be considered, in judging of the requisite degree of strength or delicacy of edge. Next in importance to the knives are the saws used in surgery. All of these must be of the best spring temper, which, for the cast-steel blade, is about 570° of Fahrenheit, and for one of Indian steel 600°, or quite the boiling point of mercury. Of another class of instruments, namely, those denominated blunt, it will be sufficient to observe, that what is known by the name of sheer steel is best adapted for the purpose. Case-hardened iron has been most improperly used, this hardening being very superficial. It is, in fact, converting the surface only into steel, by heating it to redness, in a close vessel, in contact with animal coal, such as charred bone, leather, or horn, and quenching it when red hot in a cold fluid. Iron thus treated will take a beautiful polish; but, except for ornamental purposes, it ought never to be employed. Some instruments are necessarily made of gold or silver, as catheters, and other tubes and probes. When for these ductility is required, the metals should be unalloyed; the extra expense will be more than compensated by the convenience of giving to the instruments, in all cases, the desired curve and form. The elastic catheter consists of a tube of wove silk, coated with a fine varnish, pretty generally supposed to be made from caoutchouc, or Indian rubber. This material, doubtless, forms a component in the varnish; alone it will not answer, as, in using, it would soon be partially decomposed; but when digested with the lethargic of lead and linseed oil, it forms a varnish of great beauty, elasticity, and durability, exactly adapted to make the fine surface of the elastic catheter. These valuable instruments were invented and first made at Paris. They are now manufactured in London, and finished in the most exquisite manner.

The handles of instruments, together with all ornamental parts, must in a great measure depend on the taste and choice of the purchaser. It would be well, however, to avoid such materials as are known to produce chemical action when in contact with polished steel. Ivory and mother-of-pearl are objectionable, as is ebony, although much used. The fine walnut-tree, such as the London gunmakers employ, is perhaps of all the woods the best for the purpose. Sandal-wood answers very well, although it by no means deserves all the credit which has been given to it as a preservative of steel from rust. The instrument-maker who wishes to excel will do well to avail himself of every opportunity of witnessing the operative part of surgery; he can then judge how far the instrument is mechanically and physically adapted to its purpose; and, if imperfect, he is better able to make the requisite alteration.

British cutlery has deservedly obtained a high degree of reputation in almost every part of the civilized world; and it is of vast importance to the commercial interests of the country that its character should be preserved and rendered permanent. It must not, however, be concealed, that some danger does exist of this branch of our manufacture suffering from the use of very improper materials, from which considerable quantities are fabricated. Thus a patent was obtained by a Sheffield manufacturer for a process of casting cutlery from a species of pig iron. This iron is, from the superabundance of its carbon, highly susceptible of liquidity, and readily cast into the required form. In this state the cast-iron cutlery is extremely hard, and as brittle as glass; but it is reduced from this hardness by decomposition, being subjected to a strong and long-continued fire in close vessels; and, in contact with iron ore, oxide of iron, or any substance containing oxygen, with which the superabundant carbon combines, when kept at a high temperature, and flies off in the state of carbonic acid gas. In this way, table-knives, forks, razors, scissors, penknives, and other articles are cast, saving all the labour of forging from the bar by the hammer.

This cast-iron cutlery is, when finished, not always, in appearance, distinguishable from that made at the forge; and as it can be afforded at a much lower price, it ought, in common justice, to be specifically marked as cast iron. Cuttack This very fusible iron may be advantageously applied to many purposes. It is hardly necessary to add, that it is altogether unfit for any description of edge instrument.