we consider the immense number of families of miners, melters, refiners, smiths, and other handicraftsmen, who, in all the civilized parts of the world, look up to this particular branch of manufacture for their maintenance and support; when we consider, that the once obscure and inconsiderable village of Merthyr Tydvil, though wild, barren, and sterile, and too poor to produce even the common necessaries of life, has been peopled in the teeth of every obstacle, and, within the space of seventy years, has, through the manufacture of this metal, become by far the largest and most populous town in Wales; we cannot but rejoice that this metal is one of the staple manufactures of Great Britain.

When this metal has become too much worn to answer longer the purpose for which the smith designed it, it is sold to the dealers in marine stores,' who assort it into three parcels; one called coach-tyre, consisting of the old tyre of coach and other wheels; another bushel iron, being remnants of old hoops, and different pieces of iron of similar nature; and another scrap or nut-iron, consisting of old nails, screws, nuts, and pieces of that description.

These are sold to the manufacturer to be remanufactured. The process of remanufacturing is as follows:

Two pieces of iron, each forming three sides of a square, are fixed to a wooden bench, about 10 or 12 inches apart. In the space between these two pieces are placed two rods of iron, about three-eighths of an inch square, one rod being placed close to each of the pieces. On these rods are laid pieces of old hoop, previously straightened, and cut to the proper lengths of 12 or 14 inches, according to the intended length of the faggot. The ends of the hoop rest upon the bottom of each of the pieces of iron first described, and similar pieces of hoop are ranged upon each side, while the interior is filled with bushel or scrap iron. The top is then covered with hoop, and the whole pressed tightly down, and bound, by bringing the ends of the three-eighths rod together, and screwing them round. This is termed a faggot, being about 12 or 14 inches long, and six inches square.

The faggot is then carried to a furnace not much unlike the puddling furnace, and when sufficiently heated is brought ont, and passed through the rollers, and made into what are called blooms. These blooms are generally about two feet long, by three or four inches wide, and two thick.

The blooms are again exposed to the heat in the furnace, and when at a proper temperature are taken cut and passed through the rollers, either those represented in fig. 351, or

those in fig. 352, accordingly as they are to be made into hoops, or bars. The hoop-rollers are represented in fig. 351; the bar-rollers in fig. 352.

Tables of the average weight of bars, squares, and bolts,

WHEN iron has lost all its carbon, and has become malleable, it can be reimpregnated with carbon, to a certain extent, without materially injuring its malleable properties.

The compound of iron and carbon thus produced is called steel.

To reimpregnate the iron with carbon, it must be put into a close vessel, called a cementing pot, and stratified with powdered charcoal.

The pots are made with a peculiar kind of stone, termed fire-stone, which is found abundantly in the neighbourhood of Sheffield. It possesses the properties of not being liable to crack by the heat, or of entering into fusion. These pots in the interior dimensions are from 10 to 15 feet long, and from 24 to 30 inches square. Each bar of iron is completely covered with powdered charcoal, and the last stratum of it is usually made much thicker than the rest, and kept

close with a mixture of sand and clay, to prevent the charcoal from entering into combustion with the outer air. Two of these pots only are contained in a furnace at a time, and fire is gradually employed till the heat is little short of what would be required to fuse the steel.

A vertical section, and horizontal plan, of the converting furnace is shown in figs. 355 and 356. In both figures the same letters denote the same parts.

CC is the external cone, built in a substantial manner of stone or brickwork. Its height from the ground to its vertex, in order to procure a good draught of air, should not be less than 40 or 50 feet; and to procure a still stronger heat a cylindric chimney of several feet in length is most generally fixed on the top of the cone. The lower part of the cone, which may be made of any dimensions, is built either square or octangular. The sides are carried up until they meet the cone, giving the furnace the appearance of a cone cut to a square or octangular prism at its base, and exhibiting the parabola where every side intersects the cone.

Inside the conical building is a smaller furnace, called the vault, built of fire-brick or stone, which will withstand the action of the most intense heat. DD, in the section, is the dome of the vault, and EE are its upright sides, the space between which, and the wall of the external building, is filled with sand and rubbish. A B represent the two pots that contain the iron to be converted into steel. The space between them is about one foot in width, and the fire-grate is directly beneath it. The pots are supported by a number of detached courses of fire-brick, as shown at e e, in fig. 355, which leave spaces between them, called flues, to conduct the flame under the pots; in the same manner, the sides of the pots are supported from the vertical walls of the vault, and from each other, by a few detached stones, represented by f, placed so that they may intercept as little as possible of the heat from the contents of the pots. The adjacent sides of the pot are supported from one another by small piers of stonework, which are also perforated to give passage to the flame. The bottoms of the pots are built of a double course of brick-work, about six inches thick; the sides nearest together are built of a single course of stone, about five inches in thickness; and the other parts of the pot are single courses about three inches, the sides not requiring so much strength, because they have less heat and pressure to resist.

The vault has ten flues, or short chimneys, FF, rising from it, two on each side, to carry off the smoke into the great cone, shown in fig. 356, communicating with each side, and two at each end. In the front of the furnace an aperture is made through the external building, and another corresponding in the wall of the vault; these openings form the door, at which a man enters the vault to put in or take out the iron; but when the furnace is lighted, these doors are closed by fire-bricks luted with fire-clay. Each pot has also small openings in its end, through which the ends of two or three of the bars are left projecting in such a manner, that by only removing one loose brick from the external building, the bars can be drawn out without disturbing the process, to examine the progress of the conversion from time to time; these are called the tap-holes; they should be placed in the centre of the pots, that a fair and equable judgment may be formed from their result of the rest of its contents.

a b, in the elevation, is the fire-grate, formed of bars laid over the ashpit I, which must have a free communication with the open air, that it may convey a current of fresh air to supply the combustion. The ash-pit

should also have steps down to it, that the attendant to the furnace may get down to examine by the light, whether the fire upon the whole length of the grate be equally fierce; and if any part appear dull, he uses a long iron hook to thrust up between the bars, and open a passage for the air. The fire-place is open at both ends, and has no doors. The fire-grate is laid nearly on a level with the floor of the warehouse, before the furnace, and the fireman always keeps a heap of coals piled up before the apertures at its ends, so as to close the opening. This forms a very simple and effective door; and when the furnace requires a fresh supply of fuel, a portion of the heap of coals is shoved in by a sort of hoe, and the heap renewed, to stop any air from entering into the furnace, except that which has passed upwards through the ignited fuel, and by that means contributed to the combustion.

The fire-stones composing all those parts of the furnace which are exposed to the action of the heat, are first hewn nearly to size, and finished by grinding two surfaces together, so that they make very perfect and close joints; when laid together, they are cemented with well-tempered fire-clay, mixed up thin with water. The fire-clay which answers best for this purpose, is that brought from Stourbridge, in Staffordshire, and is the same of which the celebrated Stourbridge crucibles are composed; but very good fire-clay for the purpose is procured from Birkin-lane, near Chesterfield. When the furnace has been once burnt, this clay becomes equally hard with the stone, and is less liable to fly or vitrify in an intense heat than any other known cement.

The flame arising from the ignited fuel upon the grate passes upwards between the pots, and strikes the dome of the vault, from whence it is reverberated down upon the pots, and ultimately escapes through the flues or chimneys of the vault. By this means every part of the pot is exposed to the same degree of heat, which is of great importance.

In order to ascertain when the cementation is perfect, one or two of the bars, having their ends, as before described, projecting from the pots, are taken out of the furnace, and examined.

The blisters upon the surface of the steel, caused by the carbonic oxyd,* is, in general, adopted as a criterion to judge if the metal be sufficiently converted; but this is found frequently to be fallacious, and well it may, for the size of the blisters depend more upon the degree of heat to which the bar has been exposed, than to any other cause.

The time usually required for the conversion of iron into steel is about seven days and nights; and a similar number

Carbonic oxyd is the union of the two gases which arise from the small portions of carbon and oxyd of iron, of which the iron was possessed, and which is dissipated by the heat of the furnace during this long process