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the temperature at which any given temper will be acquired. The best temper for penknives is attained at the straw color. This appears at 450 degrees; accordingly, the mercury is heated to such temperature, and introducing two or three hundred hard steel blades, they will be effectually and simultaneously tempered without involving the tedious necessity of watching the appearance of the straw color upon each individual blade, as must be done if they were placed on heated iron.
The tempering of steel, therefore, consists in reducing its excessive hardness to a moderate degree, by gentle heating, which also restores its toughness and elasticity.
The various colors that announce its fitness for cutting instruments, and the temperature at which they appear, if it be heated in air, or at which temper is conferred, if it be heated under mercury, are hereby subjoined;
At 430 degs., very faint yellow, for lancets.
At 600 degs., dark blue, or almost black, the softest gradation for hand and pit saws.
Steel, if heated still further, becomes perfectly soft.
The ordinary bar iron of Sweden and England, when converted by cementation into steel, exhibits upon its surface numerous small warty points, but few or no distinct viscular eruptions; whereas the Dannemord and the Ulverstone steel present, all over the surface of the bars, well raised blisters, three eighths of an inch in diameter, horizontally, but somewhat flattened at the top. Iron of an inferior description, when highly converted in the cementing-chest, becomes gray on the outer edges of the fracture; while that of the Dannemord acquires a silver color and lustre on the edges, with crystalline facets within. The highly converted steel is used for tools that require to be made very hard; the slightly converted, for softer and more elastic articles, such as springs and sword blades.
One of the greatest improvements which this valuable modification of iron has ever received is due to the late Mr. Josian M. Heath, who, after many elaborate and costly researches, discovered that, by the introduction of a small portion, one per cent., and even less, of carburet of manganese into the melting pot along with the usual broken bars of blistered steel, a cast steel was obtained after fusion, of a quality very superior to what the bar steel would have yielded without the manganese, and, moreover, possessed of the new and peculiar property of being weldable either to itself or to wrought iron. He also found that a common bar steel, made from an inferior mark or quality of Swedish or Russian iron, would, when so treated, produce an excellent cast steel. One immediate consequence of this discovery has been the reduction of the price of good steel in the Sheffield market by from thiirty to forty per cent., and likewise the manufacture of table-knives of cast steel, with iron tangs welded to them; whereas, till Mr. Heath's invention, table-knives were necessarily made of shear-steel, with unseemly wavy lines in them because cast steel could not be welded to the tangs.
So great is the affinity of iron for carbon, that in certain circumstances, it will absorb it from carburetted hydrogen, or coal gas, and thus become converted into steel. Mr. Mackintosh, of Glasgow, obtained a patent for making steel. His furnace coneists of one cylinder of bricks built concentrically within another. The bars of iron are suspended in the innermost, from the top; a stream of purified coal gas circulates freely around, entering below and creeping slowly above, while the bars are maintained in a state of briglit ignition by a fire burning in the annular space between the cylinders. This steel
go produced is of excellent quality; but the process does not seem to be so economical as the ordinary cementation with charcoal powder.
All the artificial alloys of silver with steel, of which so much has been said, are not fit for any thing, and are never met with in commerce.
MANUFACTURE OF BAR-IRON.
Mr. W. Clay, of Liverpool, has patented some improvements in manufacturing bar-iron; that invention relates to the employment of rolling pressure for the conversion of bar-iron of various sectional figures, as, for example, plain, straight, square bars, or bars of angle iron, or T or channel grooved or trough iron, into taper bars, or bars which, in their cross-section, gradually diminish or increase from one point of their length to another, the object being to impart to bars of iron so made different strengths or powers of resistance at different points, and thereby to adapt rolled metal to various uses, where greater strength or rigidity is required at one point than at another. This invention also relates to the adaptation of rolling pressure to the formation of bars with sudden as well as gradual irregularities of depth or thickness, by which means it is proposed to form projections, protuberances, or indentions on or in the bars at different points, according to the particular purposes for which the iron may be required. Instead of allowing the top roll to rise gradually in its bearings, and thus afford increasing space between the rolling surfaces (as in his patent of Dec. 16, 1818), Mr. Clay adjusts the rolls to the work they have to perform, and keeps them to that position until the operation is completed, his object being to produce a class of work, the irregularity in the section of which is too great to permit of its being manufactured with facility by the rising roll process. For forming a taper on the extremity of bars suitable for railway “points,” he sets the rolls to a distance apart that will correspond with the greatest depth which the formed bar is required to measure, say, for example, three inches; and assuming also, for example, that the extremity of the bar is to be tapered down to, say, one inch in depth, he provides a plate of iron or steel of a taper form, and of a thickness corresponding exactly with the diminution of thickness required in the end of the bar under operation. This plate he takes, in its cold state, and places over the end of the bar of red-hot metal, and then passes the two between the rolls. The taper plate acting as a filling piece, or as an eccentric projection on one of the rolls would act, enables the rolls to put a severer pressure on the bar at the part overlaid by the plate, and thus by simple rolling in an ordinary rolling mill a tapered bar may be produced.
The application of this principle of rolling may be further extended by giving to the contact face of the overlying plate such projections or indentations (whether gradual or sudden) as circumstances inay require, such projections or indentations corresponding to, or rather forming a counterpart of the figure to which the contact surface of the bar is required to be reduced. A plate thus formed, being placed over a heated bar of inetal, and submitted with it to the pressure of a pair of rolls, will leave the counterpart impression of its face upon the heated bar of metal. In like manner, when projections or indentations are required on opposite sides of the bar, as will be the case when rolling the spokes for railway wheels, Mr. Clay proposes to enclose the metal to be rolled (the same having been previously heated) between two suitably shaped pressure plates, and then to submit the pile to the rolling pressure.
In this way it will be obvious that he can reduce to unequal thicknesses not merely flat bars or plates of iron, but also angle iron and metal bars, having a concave or convex surface. The patentee claims the imparting a rolling pressure to the bar-iron, in the manner and for the purpose above set forth.
ON THE FORMATION OF BRASS BY GALVANIC AGENCY. Copper is more electro-negative than zinc, and separates more easily from its solutions than a metal less negative. If then, in order to obtain a deposit
of brass by galvanic means, we employ a solution containing the two component metals, copper and zinc, in the proportions in which they would form brass, there will only be produced by the action of the battery a deposit of real copper; the zinc, more difficult of reduction, remains in solution. What must be done, then, to obtain a simultaneous precipitate of the two metals in the proportions required, is either to retard the precipitation of the copper or to accelerate that of the zinc. This may be accelerated by forming the bath with a great excess of zinc and very little copper.
Dr. Heeren gives the following proportions as having perfectly succeeded: There are to be taken of
Sulphate of copper And then Sulphate of zinc
Cyanide of potassium
8 16 18 35
Each salt is dissolved in its prescribed quantity of water, and the solutions are then mixed; thereupon a precipitate is thrown down, which is either dissolved by agitation alone or by the addition of a little cyanide of potassium ; indeed, it does not much matter if the solution be a little troubled. After the addition of 250 parts of distilled water, it is subjected to the action of two Bunsen elements charged with concentrated nitric acid mixed with one tenth of oil of vitriol. The bath is to be heated to ebullition, and is introduced into a glass with a foot, in which the two electrodes are plunged. The object to be covered is suspended from the positive pole, whilst a plate of brass is attached to the negative pole. The two metallic pieces may be placed very
The deposit is rapidly formed if the bath be very hot; after a few minutes there is produced a layer of brass, the thickness of which augments rapidly.
Deposits of brass have been obtained in this way on copper, xinc, brass, and Britannia metal; these metals are previously well pickled.' Iron may, probably, also be coated in this wsy ; but cast iron is but ill adapted for this operation.-Mittheilungen des Hannov. Gewerbevereins, through Dublin Journal of Industrial Progress.
IMPROVEMENTS IN SMELTING, AND IN APPARATUS TO BE USED THEREIN.
BY WILLIAM TRURAN, of Marazion, Cornwall. In his improved method of smelting, the patentee divides the internal bore of the blast nozzle or nozzles in such a manner that it or they shall deliver a divided jet, or two or more jets of blast, into the interior chamber through the same tuyere; the pressure, tem ure, and general qualities of the blast delivered by the respective jets being either alike or dissimilar, as may be advisable, and of such form and relative proportions as the peculiar circumstances of the furnace and materials may require. The throat and mouth of the interior chamber, through which the decomposed blast escapes into the atmosphere, and of so much of the interior chamber as lies above the boshes, is constructed of a breadth equal to or in excess of the breadth of the chamber at the upper bosh line, and of an area in the plane section equal to or in excess of the area at the upper bosh line.
The form of the jet and the intensity of the blast delivered by the respective divisions of the divided nozzle-pipe may be varied by substituting other nozzles differently divided, and the general dimensions of the nozzle likewise may be adapted to local circumstances; but it is preferred to form the nozzle of two cylindrico-conical cases of different size, the lesser being inside the larger, and maintained in its position eccentrically or concentrically, as may seem best, by suitable connecting pins or pieces--care being taken that such connections do not naterially impede the delivery of the blast. When it is desired that the blast issuing from the circular central orifice shall be of equal
pressure and intensity with that issuing from the annular orifice, the proportion of taper, if any, in both inner and outer cases may be nearly similar.
By means of the improvements herein described, iron ores are smelted with greater economy of fuel, blast, and other materials than heretofore, and iron ores of every description are smelted with raw or uncoked coal, which hitherto has been coked before use in the blast furnace; and iron of fine quality is produced without passing the ore through the preliminary operation of calcination, which has not heretofore been accomplished with the ores known to geologists as the carbonates of the coal formations, and to practical smelters as the clay band and black band iron stones.
SANDERSON'S PROCESS FOR REFINING AND IMPROVING THE MANUFACTURE OF IRON.
The object of refining iron is to deprive it of the deleterious matter it may contain, and also a portion of its carbon. To effect this, the usual plan is to melt pig-iron upon coke, with the addition of a strong blast, the oxygen of which acting upon the fluid iron, which is mixed with the various alloys, oxidizes them, and during the time necessary to decarbonize the metal a quantity of slag or cinder is formed, containing from 60 to 70 per cent. of iron, thus causing a great waste of metal, varying from 2 to 4 cwts. per ton. Besides this loss, the metal so produced is not uniform in quality, sometimes being too much blown and at other times too little, thus affording no means of obtaining a regular quality of malleable iron. Coke is used as a fuel, which is expensive, and the necessity of using a strong blast increases materially the cost of production. The objects of this process are
1. To reduce the loss of metal, and to use coal as a fuel instead of coke. 2. To effect a uniform decarbonization of pig-iron without the aid of blast. 3. To use
chemical re-agent capable of giving out oxygen during its decomposition, which taking up and uniting with the carbon evolved from the metal produces carbonic oxide gas, whicli acting upon the earthy compounds contained in the pig-iron, precipitates the metal contained in them.
4. To effect a greater facility, and also to produce a greater economy in the cost of manufacturing refined metal, by decarbonizing it, and at the same time clearing away the unreduced or earthy matter with which pig iron necessarily becomes mixed during its descent through the blast-furnace; and, further, to effect an economy (by using a parer metal so obtained) in the manufacture of malleable iron, causing less waste in puddling, and also in the subsequent re-heating required for producing bar, rod, or sheet-iron.
The furnace used is a common reverberatory, having a bed large enough to contain 2 to 3 tons, or even more of fluid metal.
The crude iron may be operated upon either by melting pig-iron upon the bed of this furnace or by drawing it direct from the blast-furnace. When the metal is melted and at rest, the slag must be skimmed from the surface, and a chemical re-agent is then added, capable of disengaging oxygen during its decomposition. Carbonic acid, or carbonic oxide gases, will be produced by the decomposition of this substance, and by the union of the oxygen contained therein with the carbon contained in the fluid iron from which it is eliminated, the gases so produced being unable to re-enter the metal, either pass off in vapor, or act upon the silicates or other earthy compounds which the crude iron may contain, precipitating the metallic part and allowing the earthy matter to flow away as slag, containing comparatively but a very small percentage of iron. Thus, by adding such chemical re-agent, which by its decomposition will evolve elements capable of combining with the carbon contained in the iron, and of producing carbonic oxide gas, which, acting upon the earthy compounds or other deleterious matter contained in the iron, causes such deleterious substances to separate from the iron, obtaining very clean, pure, crys. talline metal, capable of being manufactured into superior malleable iron.
Many hundred tons have already been refined by this process direct from the blast furnace, and also by re-melting the crude iron; in both instances the
result has been uniform—the loss in metal not reaching 100 lbs. per ton upon re-melted iron, or 60 lbs. upon that operated upon in a fluid state from the blast-furnace. The malleable iron is also very materially improved in quality, being entirely freed from red shortness, and when broken cold presenting a clean, tough, elongated fibre. The loss in puddling averages 84 lbs. per ton, taken upon a furnace working 12 days; and a proportionate waste is experienced in the mill furnaces, according to the kind or size of iron required. For producing a variety of castings, it has also been found very useful, giving them greater strength, arising from the discharge of the earthy'matter contained in the pig, and bringing the metallic particles in close contact.-London Jour.
PROGRESS OF THE IRON MANUFAOTURE.
We have before us the “Address of the Western Iron Association," organized May 18, 1856, in Cincinnati, for the purpose of exciting mutual interest, and communicating information among those interested in the iron manufacture. We notice in this some of the more interesting portions of it:
Looking to the magnitude and increase of the production of American iron we have the following results, viz: In 1840, the production of American Pig Iron was
286,903 tons. In 1850, In 1955,
900,000 Increase from 1840 to 1855,
225 per cent. This is sevenfold the increase of American population, yet it is not so rapid as the importation of foreign iron, which in the same period was about 300 per cent. These facts show a most remarkable state of things; that the increased consumption of iron, from new uses, is so very great, that no increase of production, however great, has been able to keep pace with it. This does not prove the inability of the American manufacturer to supply the demand, for his resources are inexhaustible, but does prove that, for many years to come, the demand for iron will be sufficient to secure a ready market and good profits to the American producer. This is a very satisfactory conclusion to all persons engaged in that business, and one which may be relied on. The following aggregate of iron consumed in the United States, at different periods, will prove the general proposition yet more conclusively:
In 1840, total consumption,
1042,929 In 1955,
1310,000 This shows an aggregate consumption equal to an increase of 250 per cent. in 15 years—a ratio altogether beyond the increase of the population, or of any other great interest in the country.
From this general view of the subject, we may turn to a more special examination of the iron business in our own immediate vicinity. The first column in the table shows the increase of the furnaces in Ohio alone; and the second, in the Iron Region around Hanging Rock.
Furnaces around Hanging;Rock. In 1830, In 1810, In 1850, In 1855,
We should have said that about 22 of the furnaces in the Hanging Rock region, or doing business at Portsmouth, are in Kentucky and Western Virginia. For a list of these we are indebted to Mr. Conway, of Portsmouth. That gentleman has also furnished us with the statistics of each furnace, the aggregate of which is as follows, viz:
Furnaces in Ohio.
4 23 45 56