Diameter of the cylinder, 38 inches. Height of ditto, 26 do. Baillet, who has given the above description, proposes a new application of the moving force to this kind of blowing machine; and he observes, that a very important advantage may be derived from these cylinders, since the simple pressure of a column of water may be substituted for the moving power. In fig. 20. the apparatus is so arranged as to shew in what this effect may be produced.

way

The stalk f, of the cylindrical apparatus c, is common to the piston of the small cylinder d, in which it can convey the column of water bc. When the cock h is open, and that at l is shut, the pressure of the column must elevate the stalk f, and the piston of the blowing cylinder. Then the cock h being shut, and that at being open, the water of the cylinder d will flow out, and the stalk fand the piston of the cylinder will descend. These alternate motions can be easily managed by means of levers, or regulators at i, fitted to the stem of the piston, and in the same way as in the steam engine. The openings at h and I may be regulated according to the velocity which is required in the motion of the piston, and the diameter of the cylinder d will be proportioned to the fall of water b, c, and the volume of air which is wanted.

EXPLANATION OF THE FIGURES.

Fig. 16. exhibits a section and elevation of the blowing machine.

a, the wall of the building. b, the opening in the wall for the balance beam.

c, one of the two beams which receive the gudgeons on which the balance beam moves. d, e, the balance beam, f, the weight which acts as a counterpoise; g, the spring of wood.

h, a brace or strap of leather, which is attached to the curved head of the beam.

i, k, l, m, the frame which supports the cylinders. n, the blowing cylinder of cast iron.

0, 0, 0, tubes for conveying air to the furnace.

p, stalk of the piston.

9, a knee or catch attached to the stalk.

r, the horizontal axis of the water wheel.

s, s, arms attached to the axis, with rollers which

raise the knee or catch q, and the piston.

t, t, similar arms and rollers for moving the piston of the second cylinder.

Fig. 17. Section of the piston.

Fig. 18. The piston seen from above.

Fig. 19. View of the under surface of the piston.. Fig. 17. 18. and 19.

p, stalk of the piston.

w, w, lids or valves.

v, v, groove in the circumference of the piston. u, mortise to receive the stalk p.

x, x, straps of iron to support the stalk p. y, y, the band of leather surrounding the piston. Fig. 20. a, a reservoir of water; b, c, a column of

water.

d, a cylinder for water.

e, the blowing cylinder.

f, the stalk common to the pistons of the two cylin ders, d and e.

g, the pipe for conducting the air.

h, l, cocks for receiving and letting out the water. i, i, the regulators, for the purpose of opening and shutting the cocks.

k, a second blowing cylinder.*

Furnace.

*Jour, de

Three

The following is a description by Torelli-Narci, of a Mines. three-blast furnace, which was constructed in the che- blast furmical laboratory of the French school of mines.

"This furnace (says the author) is destined for fusing different mineral substances, in order to ascertain the nature of them; and the experience of six years has shown that it answers the intended purpose. By its means a very intense heat is obtained, and it was employed by C. Clouet for repeating his experiments on the conversion of forged iron into cast steel, which were attended with full success.

:

"Chemists who have seen this furnace seemed desirous of being better acquainted with the construction of it the council even transmitted drawings of it to seve ral persons; and what has hitherto prevented a description of it from being given was a desire to ascertain its power by longer use.

"I long ago conceived the idea of a fusing furnace, in which the wind was distributed in three tuyeres placed in its circumference, and at equal distances from each other; but I had no opportunity of realizing this idea till I became attached to the council of mines.

"Nearly seven years ago a plan was in agitation for constructing in the laboratory of the school a fusing furnace capable of producing a very great degree of heat, in order to operate with facility and speed on larger quantities of mineral, and consequently to obtain more precision in the trials which might be made than had been obtained by the small furnaces before employed for docimastic experiments.

"I proposed my ideas: they were approved by the council of mines; and I was ordered to cause the furnace I am about to describe to be constructed. The principal difference between it and those before used for the same purpose is, that in the present one the wind is introduced through three tuyeres, placed at equal distances from each other in its circumference, whereas in common furnaces it enters only by one.

"This furnace is round, both outside and inside, and constructed of very refractory bricks, secured by iron hoops in such a manner that they cannot be displaced. It rests on a square base of strong mason work, raised to a sufficient height above the ground to render it easy to manage.

"The bellows are four feet in length, and the mean breadth of them is about 20 or 21 inches: they are of wood, and the joints are covered with white leather. The upper part consists of five folds and two balf folds; the inferior, of two folds and two half folds. They are placed eight or nine feet (K) above a wooden box, the joints of which are covered with leather, and into which the wind

nace.

and by these means to prevent the furnace from becom- Furnace. ing deranged.

Furnace. wind as it comes from the bellows is conveyed by a copper pipe, three inches in diameter, adjusted to the upper part of the box. The box itself is supported by two iron bars built into the wall. From the lower part of this box descend, in a vertical direction, three pipes of copper, two inches in diameter, bent at right angles about 45 inches below it, to bring them into a horizontal position, and to convey the wind to the furnace, which is about six feet distant. The extremities of these pipes are fitted into three tuyeres of forged iron, fixed at equal distances around the circumference of the furnace: these three pipes are more or less curved or bent, to convey the wind into the furnace by the three apertures made for that purpose.

"About six inches below the box is adjusted, on each of the three tubes, which descend in a vertical direction, a brass cock about three inches of interior diameter: these cocks serve to intercept entirely the communication between the bellows and the furnace; and by opening them all more or less, or each of them separately, any required quantity of wind may be obtained (L).

"These cocks are well fixed to the tubes, and kept in their place by two clips of iron suited to the diameters of the tubes, and forming a kind of three collars, which by means of four screws embrace and confine them these pieces of iron are themselves made fast to two crutches of iron, which support the box and are fixed to it by screws. The box is kept on the crutches by two straps, which embrace it at each extremity, and are fixed by female screws, which are fitted to screws on the ends of these straps after they have passed through the horizontal part of the two crutches.

To give the proper strength to this furnace, a solid square was constructed of mason-work, about a foot larger on each side than the exterior diameter of the sides of the furnace, which were from 21 to 22 inches from Outside to outside. Bricks were placed on the ground in the middle of this erection for the extent of 18 inches, - in order to form a bottom, and on this base were placed the sides of the furnace constructed in the manner about to be described.

"I caused to be forged two iron hoops six lines in thickness, from 2 to 2 inches in breadth, and about 22 inches of exterior diameter; these two circles were fastened together by three bars of iron, the distance of their exterior edge being kept at about nine inches, the height of the bricks: these bars are pierced with holes towards the end rivetted on the circles, and placed at equal distances on their circumference. One of the extremes of each of these three bars is left of a sufficient length to pass beyond the lower circle about an inch, in order to make them enter into three holes formed in the brick-work which forms the bottom of the furnace,

"This kind of iron frame was filled with bricks similar to those employed for the bottom of the furnace : they were rubbed one on the other to smooth them, and the corners were a little rounded; so that, being placed upright with their broad sides applied to the iron hoops, the narrow side stood inwards. By these means all these bricks were adjusted in such a manner as to touch each other by their broadest faces, and to form the sides of the furnace, the thickness of which was equal to the breadth of the bricks, and its depth to their length. Three apertures were reserved for the tuyeres which terminate the three tubes that convey the wind, by cutting from as many bricks a portion equal to the thickness of a brick.

"These bricks thus adjusted were taken from the iron frame, and then replaced, putting between them a cement to connect them firmly and to fill up the joints. The dust produced by cutting the bricks was reserved for this purpose; and I desired the workmen to mix with it a small quantity of clay diluted in a great deal of water, in order to make a puddle for daubing over the bricks, and in particular to put between them no more than was necessary for filling the joints and the small space left between their faces in consequence of any inequality left in dressing them.

The furnace thus constructed was then placed on its base, a stratum of the same mortar employed for filling up the joinings of the bricks being first interposed. The extremities of the three iron bars projecting beyond the lower circle were placed in the holes left in the base to receive them. The body of the furnace encircled with iron, both by its weight and the gentle blows given to the iron hoops above the bars which connected them, expelled the excess of the mortar, and caused a part of it to enter and unite with that which filled up the joints of the brick work of the circumference, which rendered it immoveable.

"The bellows is secured as usual by crutches of iron and supporters fixed in the wall and to the floor: the handle is disposed in such a manner, that the rope which makes it act may be pulled by the same person who manages the fire of the furnace, which in certain cases is necessary.

"The tuyeres of forged iron, which receive the ends of the copper tubes, are secured in their proper apertures in the circumference of the furnace by pieces of brick and mortar similar to that employed for filling up the joints; and the ends of the copper pipes introduced into these tuyeres are luted with the same mortar, a little thickened with brick dust.

"The apertures of these tuyeres towards the interior of the furnace is only nine lines in diameter; on which account,

66

Furnace. account, as the volume of air furnished by the bellows cannot pass so quick as it is produced, it becomes condensed in the box placed above the cocks. By these means a very uniform blast is obtained, which can also be regulated by opening more or fewer of the cocks. During more than six years, since this furnace was constructed, it has suffered no derangement: it is not even cracked. It is however worn in the inside by the violence of the heat it has experienced, which has increased its diameter about two inches. The parts round the three tuyeres have also got hollowed, so that it has need of being repaired. It is intended to make it deeper, and to have a kind of moveable muffs or linings made of fire clay, in order that its diameter may be reduced at pleasure it is meant also to construct it in such a manner, as to deposit the rest or support for the crucible, not on the bottom of the furnace, but on bars of forged iron placed at the distance of some inches from that bottom, so as to leave below them a vacuity in which the blast of the bellows may be diffused, and from which it may rise, passing between the bars to traverse the mass of charcoal which surrounds the crucible. The blast will then produce a more uniform fire, and the flame can no longer be directed against the sides of the crucibles; so that the risk of their breaking by sudden inequalities in the heat will be much less.

Plate

This alteration is going to be immediately carried into execution, and the method proposed for doing it is as follows:

"A round frame will be made of forged iron, in which bricks will be placed in the same manner as above described. In the lower part of the furnace an aperture will be reserved for raking out the ashes, which will be closed by means of a door of baked earth carefully luted with clay. Some inches above the bottom of the furnace will be placed a grate of forged iron, and between this grate and the bottom of the furnace the tuyeres will terminate, and the blast be introduced. Muffs or linings of very refractory earth will then be introduced, so as to descend to this grate. There will be two of them, one within the other, and both within the body of the furnace. At the lower part these muffs will be furnished with a rim, projecting outward so as to leave between the body of the furnace and the muffs, a vacuity, which will be luted at the bottom with clay, and which will be filled with pounded glass, or any other substance a bad conductor for heat.

The interior muff, or both of them, may be removed at pleasure to obtain a furnace of greater or less capacity according to the operations to be performed. It is proposed to make the muffs wider at the top than at the bottom.

Explanation of the Figures.

"Fig. 21. Plan of the bellows and of the furnace. cexxvII. AB, the bellows made of wood, the folds of which are fig. 1. also of wood covered with leather on the joints. CD, the handle which serves for moving the bellows. E, a copper tube which conveys the wind of the bellows into the box FG, in which it is condensed. FG, a box of wood serving as a reservoir for the wind condensed by the bellows. HI, KL, MN, three pipes adapt

ed to the box FG, and which convey the wind into Furnace. the inside of the furnace by, three tuyeres, I, L, N. OP, mason work to support the horizontal pipes. Q, the furnace properly so called, the former of which is circular, and which is placed on the square mason work R, S, T, U.

66

Fig. 22. Elevation of the furnace, the pipes which Fig. 22. convey the blast, the cocks, the condensing box, and the bellows. AB, the bellows mounted in their place, and supported by the iron-work necessary for securing it, which is fixed in the wall and to the floor. CD, the handle which serves for moving the bellows. E, the copper pipe which conveys the blast of the bellows to the box FG in which it is condensed. At G is a hole shut by a large cork stopper, which can be opened at pleasure. This box is supported by two crutches of iron f, g, and h, i, built into the wall, and on which it is fixed by two iron stirrups, m.

"Fig. 23. One of the crutches and its stirrup are seen Fig. 23represented sidewise at f, g, l; the extremities, n,o, are built into the wall, and the two ends, p, q, of the iron piece which keeps the box on the horizontal traverse of the crutch, are tapped, and receive screws which make them fast to the crutch f, g. HI, KL, MN, are three pipes which convey the wind into the interior of the furnace. Q, R, S, T, U, mason work on which is placed the furnace Q, and which serves it as a bottom. OP, masonry which serves to support the three pipes that convey the wind to the furnace. XYZ, fig. 22. are the three cocks fixed to the three pipes which proceed from the box to convey the wind to the furnace.

"In fig. 24. the dimensions of which are double those Fig, 1.4 of fig. 22. may be seen the details of one of these cocks.

"At r, s, t, the body of the cock is seen in front; the stopper being taken out shows at r and at t the two holes which receive the tubes that communicate either with the box or with the tuyeres. u Exhibits the body of the cock seen on one side; v the key with its aperture x, and its head y. This key, turned round more or less in its socket, serves to give more or less wind. 1, 2, 3, Iron clips which secure the cocks at the distance they ought to be from each other, and connect them at the same time to the iron crutches which support the air-box.

“Fig. 25. a plan of these two clips. They are bent Fig. 25. at the places marked 1, 2, 3, to embrace the body of the three cocks, and secure them in such a manner that they cannot be deranged when they are opened or shut.

"Fig. 26. and 27. represent the plan and section of Fig. 16: the changes and additions proposed to be made when and 27. the furnace is re-constructed. At I, L, and N, are seen the extremities of the three pipes that enter the forged iron tuyeres, and convey the wind to the interior of the furnace. a, b, and c, indicate the thickness at the upper part of each of the muffs and of the body of the furnace, between which there are two vacuities filled with pounded glass or some other bad conductor of heat. d, the grate on which are deposited the rests of baked earth destined to receive the crucibles. e, the crucible, luted and attached with clay to a rest of baked earth (M).”

Mr

"At

Furnace.

Accounts of

"I shall, at present, confine my remarks to the ope- Furnace. ration performed on iron in Sheffield and its neighbourhood: from whence various communications have Process in been transmitted to me by resident friends, and where Sheffield, I have myself seen the operations repeatedly performed.

Mr Collier, in a paper communicated to the Manchester Philosophical Society, has delivered some important observations on iron and steel, with a more correct account of the process for the manufacture of the latter than has hitherto been given. To this account he has added the description of a furnace for the conversion of iron into steel. As his observations and reasonings are extremely valuable, we shall lay the whole before our readers in his own words.

"After examining (says (Mr Collier) the works of the process different authors who have written on the subject of for making making iron and steel, I am persuaded that the accounts

iron and steel, imperfect,

given by them of the necessary processes and operations are extremely imperfect. Chemists have examined and described the various compound minerals containing iron with great accuracy, but have been less attentive to their reduction. This observation more particularly applies to steel, of the making of which I have not seen any correct account.

"It is singular to observe, how very imperfectly the cementation of iron has been described by men of great eminence in the science of chemistry. Citizen Fourcroy states the length of time necessary for the cementation of iron to be about twelve hours; but it is difficult to discover whether he alludes to cast or to bar steel: for he says, that short bars of iron are to be put into an earthen box with a cement, and closed up. Now steel is made from bars of iron of the usual length and thickness: but cast steel is made according to the process described by Citizen Fourcroy, with this essential difference; the operation is begun upon bar steel and not bar iron.

"Mr Nicholson is equally unfortunate in the account given in his Chemical Dictionary. He says, that the usual time required for the cementation of iron is from six to ten hours, and cautions us against continuing the cementation too long; whereas the operation, from the beginning to the end, requires sixteen days at least. In other parts of the operation he is equally defective, confounding the making of bar with that of cast steel, and not fully describing either. In speaking of the uses of steel, or rather of what constitutes its superiority, Mr Nicholson is also deficient. He observes, that its most useful and advantageous property is that of becoming extremely hard when plunged into water.' He has here forgotten every thing respecting the temper and tempering of steel instruments, of which, however, he takes some notice in the same page. Plunging into water' requires a little explanation: for if very hot steel be immersed in cold water without great caution, it will crack, nay, sometimes break to pieces. It is, however, necessary to be done, in order to prevent the steel from growing soft, and returning to the state of malleable iron; for, were it permitted to cool in the open air, the carbone which it holds in combination would be dissipated (N).

"The iron made in that part of Yorkshire is procured from ores found in the neighbourhood, which are of the argillaceous kind, but intermixed with a large proportion of foreign matter. These, however, are frequently combined with richer ores from Cumber. land and other places. The ore is first roasted with cinders for three days in the open air, in order to expel the sulphureous or arsenical parts, and afterwards taken to the furnaces: some of which are constructed so that their internal cavity has the form of two four-sided pyramids joined base to base; but those most commonly used are of a conical form, from 40 to 50 feet high. The furnace is charged at the top with equal parts offor the recoal-cinder and lime-stone. The lime-stone acts as a duction of Alux, at the same time that it supplies a sufficient quan- ore, tity of earthy matter to be converted into scoriæ, which are necessary to defend the reduced matter from calcination, when it comes near the lower part of the furnace. The fire is lighted at the bottom; and the heat is excited by means of two pair of large bellows blowing alternately. The quantity of air generally thrown into the furnace is from a thousand to twelve hundred square feet in a minute. The air passes through a pipe, the diameter of which is from two inches and a quarter, to two and three quarters, wide. The compression of air which is necessary is equal to a column of water four feet and a half high. The ore melts as it passes through the fire and is collected at the bottom, where it is maintained in a liquid state. The slag, which falls down with the fused metal, is let off, by means of an opening in the side of the furnace, at the discretion of

the workmen.

"When a sufficient quantity of regulus, or imperfectly reduced metal, is accumulated at the bottom of the furnace (which usually happens every eight hours), it is let off into moulds; to form it for the purposes intended, such as cannon or pig iron.

"Crude iron is distinguished into white, black, and gray. The white is the least reduced, and more brittle than the other two. The black is that with which a large quantity of fuel has been used; and the gray is that which has been reduced with a sufficient quantity of fuel, of which it contains a part in solution.

"The operation of refining crude iron consists in and for reburning the combustible matter which it holds in so-fining crude lution; at the same time that the remaining iron is iron. more perfectly reduced, and acquires a fibrous texture. For this purpose, the pigs of cast iron are taken to the forge; where they are first put into what is called the refinery which is an open charcoal fire,

Furnace. fire, urged by a pair of bellows, worked by water or a steam engine; but the compression of air, in the refinery, ought to be less than that in the blast furnace. After the metal is melted, it is let out of the fire by the workmen, to discharge the scoriæ; and then returned and subjected to the blast as before. This operation is sometimes repeated two or three times before any appearance of malleability (or what the workmen call coming into nature) takes place; this they know by the metal's first assuming a granular appearance, the particles appearing to repel each other, or at least to have no signs of attraction. Soon afterwards they begin to adhere, the attraction increases very rapidly, and it is with great difficulty that the whole is prevented from running into one mass, which it is desirable to avoid, it being more convenient to stamp small pieces into thin cakes: this is done by putting the iron immediately under the forge hammer, and beating it into pieces about an inch thick, which easily break from the rest during the operation. These small pieces are then collected and piled upon circular stones, which are an inch thick, nine inches in diameter, and about ten inches high. They are afterwards put into a furnace, in which the fire is reverberated upon them until they are in a semi-fluid state. The workmen then take one out of the furnace, and draw it into a bar under the hammer; which being finished, they apply the bar to another of the piles of semi-fluid metal, to which it quickly cements, is taken again to the hammer, the bar first drawn serving as a handle, and drawn down as before. The imperfections in the bars are remedied by putting them into another fire called the chafery, and again subjecting them to the action of the forge hammer.

The above method is now most in use, and is called flourishing; but the iron made by this process is in no respect superior to that which I am going to describe. It is, however, not so expensive, and requires less labour.

"The process for refining crude iron, which was most common previously to the introduction of flourishing, is as follows.

"The pigs of cast iron are put into the refinery, as above, where they remain until they have acquired a consistence resembling paste, which happens in about two hours and a half. The iron is then taken out of the refinery and laid upon a cast iron plate on the floor, and beaten by the workmen with hand hammers to knock off the cinders and other extraneous matters which adhere to the metal. It is afterwards taken to the forge hammer and beaten, first gently, till it has obtained a little tenacity; then the middle part of the piece is drawn into a bar, about half an inch thick, three inches broad, and four feet long; leaving at each end a thick square lump of imperfect iron. In this form it is called ancony. It is now taken to the fire called the chafery, made of common coal; after which the two ends are drawn out into the form of the middle, and the operation is finished.

process.

"There is also a third method of rendering crude Furnace. iron malleable, which, I think, promises to be abundantly more advantageous than either of the two for. An im. mer, as it will dispense both with the refinery and proved chafery and nothing more will be necessary than a reverberating furnace, and a furnace to give the metal a malleable heat, about the middle of the operation. The large forge hammer will also fall into disrepute, but in its place must be substituted metal rollers of different capacities, which, like the forge hammer, must be worked either by a water wheel, or a steam engine.

"It is by the operation of the forge hammer or metal rollers, that the iron is deprived of the remaining portion of impurity, and acquires a fibrous texture.

"The iron made by the three foregoing processes is equally valuable, for by any of them the metal is rendered pure; but after those different operations are finished, it is the opinion of many of the most judicious workers in iron, that laying it in a damp place, for some time, improves its quality; and to this alone, some attribute the superiority of foreign iron, more time elapsing between making and using the metal. To the lat ter part of this opinion I can by no means accede, as it is well known that the Swedish (0) ores contain much less heterogeneous matters than ours, and are generally much richer, as they usually yield about 70 per quintal of pure iron, whereas the average of ours is not more than 30 or 40 (P): add to this, that the Swedish ores are smelted in wood fires, which gives the iron an additional superiority.

"Iron instruments are case-hardened by heating them in a cinder or charcoal fire; but if the first be used, a quantity of old leather, or bones, must be burnt in the fire to supply the metal with carbone. The fire must be urged by a pair of bellows to a sufficient degree of heat; and the whole operation is usually completed in

an hour.

"The process for case-hardening iron, is in fact the same as for converting iron into steel, but not continued so long, as the surface only of the article is to be impregnated with carbone.

"Some attempts have been made to give cast iron, by case-hardening, the texture and ductility of steel, but they have not been very successful. Table and penknife blades have been made of it, and, when ground, have had a pretty good appearance; but the edges are not firm, and they soon lose their polish. Common table knives are frequently made of this metal.

"The cementation of iron converts it into steel:--a substance intermediate between crude and malleable iron.

"The furnaces for making steel are conical build- Furnace for ings; about the middle of which are two troughs of making brick or fire stone, which will hold about four tons of steel iron in the bar. At the bottom is a long grate for fire.

"A layer of charcoal dust is put upon the bottom of Ppa the

(0)

"Steel is commonly made of Swedish iron."