is increased, for a strong heat is required to weld this tough mass into a ball. By continually raising and turning the iron, it will become uniformly heated. When it becomes tenacious, it may be removed to the hammer or squeezer, and reduced to a rectangular prism five or six inches square; and if too long, it may be cut into pieces not exceeding in length fifteen or sixteen inches. These prisms form the blooms of our markets, and are usually sent to the rolling mills to be transformed into bars, or, generally, into sheet. iron or boiler-plates.

h

The cinder in the hearth, unless present in too large quantity, which is seldom the case, may be suffered to remain. When the scraps of iron are removed, and the lining of the hearth secured, and, if necessary, repaired, coal may again be filled in, and the blast turned on.

White iron, and even mottled iron, very seldom boil; but, by proper treatment, arrive as a pasty mass at the bottom of the hearth. This mass should be broken up, and brought, to a greater or less extent, within the range of the blast. But this manipulation requires caution, where we have to deal with white anthracite iron; because this metal commonly works too fast, and, if its propensity is favored, bad iron results. Taking care to prevent the iron from touching the tuyere, we should keep it in a pasty state as long as possible, to afford the impurities an opportunity of combining with the cinder. When the bottom of the hearth is very cold, it is possible that the metal may be gray or fusible, though the part which touches the hearth may be hard and cold. In this case, the iron, whether in mass or in pieces, should be carefully brought above the tuyere, and once more melted down. In the mean time, it is advisable to discontinue the cooling of the bottom plate.

g. The tools required at the blomary fire are very simple. A few implements like crowbars; several pairs of tongs for lifting the bloom from the fire; and a couple of chisels shaped like hatchets, for cutting blooms, are all we require. Of the means employed to reduce the balls to a proper size, we shall speak elsewhere.

h. The results and the expense of this branch of iron manufacture of course vary greatly. One kind of metal will yield ninety or ninety-two per cent. of blooms; while another kind will yield but eighty per cent., or even a less percentage than that. The same difference may be observed in relation to the quantity of fuel required. The number of bushels of charcoal varies from 150 to 250 per ton of blooms. A blomary fire, conducted night and day

for a week, furnishes from four to seven tons of blooms. Wages of workmen from six to seven dollars per ton.

At various places, hot blast is applied with success; but at other places, with but little advantage. In most instances, it is not employed.

In Europe, the varieties of blomary fires, or refineries, are innumerable. These varieties depend, in a greater or less degree, on the nature of the coal and iron used, and upon the habits of the people. Many arrangements produce better iron than that we have described. But the advantages which these possess depend upon circumstances which are not available in the United States. The only ore which does not follow the general rule of the oxides and hydrates is the magnetic ore of the different States. This ore might be made to produce as good iron as the best Swedish. But our furnace owners, in their inconsiderate eagerness to realize every possible advantage, often produce a metal whose quality cannot be at all relied on. Our forge owners, therefore, when they desire a good article, are generally compelled to do the best they can in relation to economy of fuel.

IV. Finery Fire.

We shall now describe a process intermediate between the blast furnace and the forge; that is, the finery or run-out fire. A description of this should have followed that of the blast furnace; but as it is of later origin, and will, besides, be better understood after the explanation of the German finery, we thought it advisable to delay our notice of it. This invention is the result of necessity. The introduction of stone coal, coke, and hot blast occasioned so much bad pig iron, that some means which should remove a portion of the impurities in the metal before its removal to the charcoal forge or to the puddling furnace were eagerly sought. The necessity of an intermediate process will be readily admitted: but a more awkward and unprofitable invention than that we are considering could not have originated from the most unskillful intellect. The apparatus is so worthless as scarcely to deserve notice. In fact, when we see the large amount of iron which is converted into slag; when we see the best charcoal iron wasted by the Western manufacturers, we are justified, we think, in wishing that the apparatus had never been invented. But the invention exists, and there is no immediate prospect of getting rid of it; therefore it is our duty to record its existence, and to exhibit its construction.

Fig. 78 represents a vertical section, and Fig. 79 a ground-plan, of a finery. It is erected on a platform of brick, about twenty inches in height, in the middle of which is the hearth or fireplace A. At each of the four corners an iron column is erected, upon

Fig. 78.

Finery, or run-out fire.

which a brick chimney, two feet in width inside, is built. This fire generally works with four tuyeres, that is, two on opposite sides; or with four nozzles, and but two tuyeres, on the same side. When the latter is the case, two currents of blast are conducted into each tuyere, that the whole surface of the melted metal may be exposed to the action of the blast. The sides of the hearth are formed of hollow cast iron plates, through which a current of cold water is constantly running, to prevent their melting. The hearth is generally from three to three and a half feet in length, twenty-four inches in width, and twenty-four or thirty inches in depth. Around the fire are sheet iron doors, fastened to the columns; these are alternately used to prevent the disturbance occasioned by strong draughts of wind. Such fires produce a great deal of dust, heat, and rubbish,

17

and are generally removed from the main buildings. The bottom of the hearth is formed of coarse sand, and often of coke dust. The nozzles a a are from an inch to an inch and a quarter wide. The blast, of which about 400 cubic feet per minute are required, is pro

Fig. 79.

Ground-plan of a finery.

duced in iron cylinders. In a prolongation of the tapping hole b, is the chill mould; this is a heavy, cast iron trough, sufficiently large to receive the contents of the hearth. It is commonly ten feet in length, thirty inches in width, and four inches in depth. A current of water is led around it to keep it cool. Pipes, sufficiently large for throwing a strong current of water upon the hot iron, should be at our disposal at all times.

When the hearth is ready for operation, fire may be placed on it, and coke, or, as in many instances, charcoal thrown on; the blast is then applied, and pig iron, to the amount of five or six hundred pounds, charged at once. If the iron is very gray, a greater dip

of the nozzles and of the tuyere is given; this secures stronger blast upon the metal, which, after being charged, soon comes down. When the iron disappears from the top, another charge is given, and melted down, care being taken that the coke is duly supplied. In this way, twenty pigs, or generally one ton of iron, are melted. Some time is required, where the iron is gray, before the metal can be let out; and when sparks of burning iron appear to be thrown off from the top of the coke, this time is supposed by the workmen to have arrived. After the lapse of about two hours, the time required for one heat, the tapping hole is opened, and the iron runs into the chill mould, or, as it is called by the workmen, the pit. This mould has been previously washed with a thin clay solution, to prevent adhesion of the refined metal to its surface. Cinder also flows off with the iron. As soon as the metal becomes solid, a strong current of cold water is permitted to flow upon it, the reason for which we shall explain in another place. In the mean while, fresh coke and pig iron are charged, and the process continued as before.

a. The quality of the refined iron depends principally upon that of the pig metal; while the quality of the latter depends upon the previous manipulation in the blast furnace. Good soft gray or white iron generally furnishes metal of excellent quality; but white, hard, and brittle pig is very little improved in the finery. There have been cases in which 2300 pounds of pig produced a ton of metal; and we have known instances in which 3000 pounds of coke iron were used to produce the same amount. It is beyond human skill to suggest any method by which a waste of iron, to a greater or less degree, can be prevented.

To what extent this kind of work answers its purpose as a forerunner of the finery forge and puddling furnace, we shall investigate at the close of this chapter. Some years since, Mr. Detmold, of New York, introduced an improvement upon this mode of refining. He constructed a reverberatory furnace, resembling in form the puddling furnace. The pig iron was melted on a large hearth, and the blast thrown upon its surface to whiten it. But there is little merit in either of these refineries.

V. Puddling Furnaces.

The reverberatory or puddling furnace is, unquestionably, of all arrangements, the best adapted to convert cast iron into bar iron. The imperfect results which have hitherto been obtained with respect to the quality of iron, have, as might have been expected,