chloride; the tincture of which, called tincture of sesquichloride of iron, is extremely valuable as an emmenagogue; it likewise is very beneficial in checking menorrhagia proceeding from relaxation of the uterus. It checks hæmaturia from relaxation of the tissue of the kidneys. In catarrh of the bladder it is very serviceable. In frequently repeated small doses it relaxes spasmodic stricture of the urethra. But the feeling of nausea and sinking which it causes, renders patients averse to its repetition. It acts as a potent astringent when applied externally or to mucous membranes as an injection.

Sulphate of iron can be given in small doses, in pills or otherwise. Its powers are often much heightened by combination with sulphate of quinia. In nervous debility and indigestion this form is valuable. The potassio-tartrate of iron has less unpleasantness of taste than most of the other preparations of iron, and is therefore more acceptable to children, to whom also the vinum ferri is much prescribed. Both these are nearly superseded by the citrate or ammonio-citrate of iron, which can be given in the form of lozenge or syrup. The latter given in warm water or lemonade is relished by most children. Still the potassio-tartrate has many recommendations.

Iodide of iron is a preparation of great value in strumous disorders. The same may be said of the phosphate of iron, a preparation formerly in the London Pharmacopoeia, and now most unjustly excluded from it. In the phosphatic diathesis of feeble subjects, with a tendency to rickets, it is invaluable. The dose for children is a very few grains, cautiously increased. The numerous preparations of iron recently introduced by chemists have not been sufficiently tried to permit them to be spoken of with certainty; but in many cases their utility is obvious. Of these the chief are citrate of iron, potassio-citrate, sodiocitrate, zinco-citrate, magnesio-citrate, ferro-citrate, and citrate of quinine and iron; this last is of great service in tic douloureux.

A better form is the pyro-phosphate, which is soluble in water, warm or cold; the form of this in pseudo-crystalline scales, is a pyro-phosphate of iron and soda. This along with rhubarb is a most efficacious cure for the headaches of most young females.

The saccharated carbonate of iron has many advantages. It may quite supersede the well-known Griffith's mixture. Hydrated protosulphuret of iron is stated to be an antidote to poisoning by corrosive sublimate, but to be of use it must be given within ten minutes after the poison has been taken. White of egg is a better antidote.

Chalybeate waters often furnish the best medium for administering iron; especially when the iron is associated with much free carbonic acid. Where no free carbonic acid is present, and in some instances even where it exists, the water of the springs should be received in and drunk out of warm water. This often prevents the spasm which is apt to occur when very cold water is suddenly taken into the stomach. Besides being reputed an antidote to the poisonous salts of copper, iron is asserted to prove an antidote to other violent poisons.

Hydrate of peroxide of iron, called also hydrated peroxide of iron, is considered a trustworthy antidote against arsenic, if administered promptly, while the arsenic is yet in the stomach, and not absorbed. Prussic acid may be decomposed or combined, so as to be rendered innocuous, by giving promptly, first, solution of carbonate of potass, followed by a very diluted solution of the proto-persulphate of iron; the object being to form a ferro-prussiate of potass in the stomach. (See Lancet,' 5th October, 1844; or 'Pharmaceutical Journal,' vol. iv. p. 373.)

Physiological Effects and Therapeutic Employment of Iron.-Iron exists both in plants and many animals, as the mammiferæ and birds, constituting an essential part of their fluids and solids; but, incorporated" as it is thoroughly with them, it gives rise to none of those phenomena which it occasions when taken into the stomach. Upon the living tissues iron has a tonic influence; and as its preparations greatly promote digestion, they excite the appetite and render more easy the elaboration of the aliment. The vitality of the digestive organs being exalted, they extract from the food more of the nutritious principles, and thereby furnish a greater quantity fit to be assimilated.

These beneficial effects are best seen when the medicine is given in small and long-continued doses, or in the greatly diluted state in which iron occurs in the mineral waters or chalybeate springs. On the other hand, chalybeates occasion at times, especially if in large doses, pain of the epigastre, nausea, fœtid eructations, and great anxiety; consequences referable to the immediate impression, a sort of constrictive action, which the preparations of iron make or exercise when they reach the stomach, upon its internal surface, and the nerves which are distributed upon it. The unpleasant effects may generally be avoided by giving it at first in very small doses, gradually increased, or by diluting it with some vegetable substance of little activity.

Iron given in large doses, when it reaches the intestines, produces in some persons obstinate constipation, accompanied with a sense of great heat in the lower belly; in others it occasions colics and frequent alvine dejections; while with a third set of persons none of these effects follow its administration.

During the use of iron the fæces invariably become blackened, which is caused by the tannin of our food acting upon the iron.

In respect to the secondary effects of iron, the amount of these depends upon the quantity absorbed, and the length of time it has been given. That it is absorbed, in most instances, and carried into the circulation, is proved both by the effects of it being felt over the

whole system, and by being distinctly recognisable in the urine on the addition of an infusion of galls. When used for some time, chalybeates increase greatly the power of the heart; the pulse becomes stronger and harder-effects most observable upon persons previously enfeebled by disease. If persisted in, they cause increased arterial action, followed by febrile commotion, sense of heat, and hæmorrhagic discharges from different parts of the body. These phenomena show themselves most speedily in persons of a plethoric habit and sanguine temperament; iron also rouses the absorbent organs when sluggish.

The functions of nutrition and assimilation are greatly heightened by the use of iron; but if it be too long persevered in, diseases of overaction ensue, as inflammations, hæmorrhages, &c. These symptoms indicate the necessity of discontinuing it.

The preparations of iron are unquestionably efficacious in diseases which proceed from a relaxation of the substance of the living tissues, from an inactivity of the reparative or assimilative function, or in case of weakness proceeding from deficient supply of nervous energy.

Hence they are indicated in anæmia, in convalescence from debilitating fevers, and other tedious diseases, as well as after some of the more acute phlegmasiæ, as pneumonia, the cough remaining after which, if not occasioned by any organic change, is sooner removed by preparations of iron or bark than any other means. Chalybeates are likewise given in defective menstruation from debility of the uterus, and sometimes in sterility. In chlorosis iron is almost our sheet-anchor, while it is also very serviceable in some forms of dyspepsia, also in worms, (in which the sulph.-ferri is given in large doses), in passive hæmorrhages, and it is prescribed empirically in many of the cachexia, as scrofula.

Chalybeates are found useful in many nervous diseases, as hysteria: the cough which is often present in these complaints may be effectually removed by preparations of iron. The indurations, too, of the mammæ (apt to be considered of a cancerous nature), and of other glands in hysterical females, are often dispersed by the use of iron. Some of the forms of tic douloureux, not dependent upon organic causes, are often cured by chalybeates. Iron has likewise been prescribed in the intervals of the paroxysms of intermittents, particularly quartans. The sulphate is given in the dose of 3i. in a pint of water,-in which circumstance it can only act beneficially, like cinchona or bitter tonics,-iron being among minerals what bitter herbs are among vegetable remedies.

Chalybeates are contra-indicated in plethora and all inflammatory diseases, as well as active haemorrhages, as also during pregnancy in females of a sanguine temperament.

IRON MANUFACTURE AND TRADE. The art of smelting iron was practised in this country during the time of the Roman occupation. The principal seats of the manufacture appear to have been Sussex and the Forest of Dean, or Arden as it was then called. It is known that iron-works existed in that part of Gloucestershire in 1238; because there occurs among the patent rolls of Henry III. of that date, one entitled 'De Forgeis levandis in foresta de Dean.' Remains of ancient iron-furnaces have been noticed in Lancashire, Staffordshire, and Yorkshire. The art of working in iron and steel was much practised in this island before the Norman conquest. We are told that not only was the army of Harold well supplied with weapons of steel and with defensive armour, but that the horses were covered with steel and iron armour, and that every officer of rank maintained a smith, who constantly attended his master to the

the second and third being the results of an extension of the processes necessary for the production of the first.

Pig-iron. The first process is that of reducing the iron-stone or ore, or, as it is technically called, the mine, into a metallic state by means of fusion. This operation is conducted in a blast-furnace, the form and construction of which will be understood from the following section. The interior of this furnace in the broadest part, which is called the boshes, is usually from 14 to 17 feet in diameter, and this is gradually decreased to about half that diameter at the top. The whole is built of masonry, the lining to the furnace being composed of fire-bricks carefully jointed together with fire-clay the whole furnace is strongly bound together with iron hoops or stays. The furnace is again contracted below the boshes, and into this lower part the melted iron falls as it is formed. The ground-plan of this lower part of the furnace is constructed as shown in the following diagram, where the unshaded

Fig. 2.-Ground Plan of Blast Furnace.

square in the centre represents the hearth, and is about 3 feet square. The three tubes leading to this hearth (two of which are shown in the vertical section), and which are called tuyeres, are used for introducing the blast of air required to give the degree of intenseness to the heat necessary for fusing the ore.

The size and form of the blast furnaces have undergone much change. Slight differences will be observed by comparing the section in fig. 1, with that at col. 241 of the article FURNACE; but the modern alterations have been still more considerable. Half a century ago the furnaces were generally about 40 feet high, 10 or 12 feet across the boshes, and 34 feet diameter of tunnel-head, or cylinder, at the top; and they were blown with only one tuyere each. By degrees the tunnel-head has been enlarged to 10 feet; the tuyeres have been increased from one to three; a new form has been given to the lower part of the interior; and in some instances, such as that of Messrs. Dixon's works at Govan, near Glasgow, the whole furnace is made cylindrical. The largest furnaces are now 60 feet high, and about 40 feet square at the base. Engineers are still divided in opinion concerning the best size of the throat, or contracted part between the body of the furnace and the tunnel-head; but all agree that it should be much longer than those formerly employed. We have now to notice the filling of the furnace with iron-ore, coke, and limestone. The ore must previously have been roasted or calcined

Fig. 3.-Filling Blast Furnace.

in a kiln, in order to drive off the water, sulphur, and arsenic, with which it is more or less combined in its native state: by this process it loses one-sixth part of its weight. One of the recipes for smelting

iron, in use a few years ago, gave the proportion at 15 tons of roasted iron-ore, 22 tons of coke, and about 6 tons of limestone; but these proportions vary according to the quality of the ingredients, and the routine of processes. The ingredients are supplied at equidistant charges, and must be intimately mixed together in the furnace. The limestone must be broken into small pieces; its use is to act as a flux to the ore and promote its fusion. The mode of filling the furnace varies a good deal. In Wales, the blast furnaces are usually built on the slopes of hills, so that the minerals can easily be brought from the mines to the top of the furnace; but where the latter is built on the level of the ground, as in most of the midland districts, the minerals must be raised to the proper level by steam, water, or pneumatic power. Inclined planes have generally been used; but these are in many works being superseded by a direct vertical lift. One of the filling-mouths at the top of a furnace (of which there are sometimes four) is shown in fig. 3. The usual plan is to throw in the ore, coal, and limestone in alternate barrowsful; but Mr. Slate, in 1859, proposed a new method. He makes the furnace-mouth very wide, and places over it a bridge supported by iron girders. A cast-iron pipe descends vertically from the bridge into the furnace, and is continued down beneath the surface of the burning material; the greater portion of the fuel is fed in through this pipe; while the other materials are fed in through the open mouth of the furnace; insomuch that the fuel is always in the middle, and the ore and flux around it. A valve lifts up the cover of the central pipe; and several scuttles or openings are left to admit the other materials. How far the cast-iron pipe will bear the intense heat, is a point not yet satisfactorily determined.

Supposing the fire to be lighted and the minerals introduced, the next matter is the important one of the blast. The heat that would be produced in any furnace by merely setting fire to the fuel which is thrown into it would be altogether insufficient for the fusion of the ore, if its intensity were not promoted by the forcing in of a current or blast of air. For this purpose it is necessary to use a strong mechanical force. Water-wheels, where they can be had, are suitable agents; but there are not many places where a sufficiently copious and regular supply of water at all seasons can be commanded, and the success of an iron-work would be destroyed by the failure of the blast in any degree for even a short time. Steam-engines are now, therefore, almost universally preferred. This power is applied to the working of a blowing cylinder, which may be many times the area of the cylinder of the steam-engine. If the blast thus produced were passed immediately from the blowing cylinder through the tuyeres to the furnace, the effect would be intermitting and irregular, ceasing at the end of each stroke of the steam-piston. To remedy this inconvenience the blast is carried into an intermediate chamber of a spherical or cylindrical shape, called a regulator; and as the air is in a state of condensation when admitted, its effort to expand itself again to its natural volume causes the continuous and regular supply to the furnace which is necessary. The air thus forced into the furnace keeps the heat at a high degree of intenseness. Until about thirty years ago, the air thus supplied was uniformly at the temperature of the atmosphere from which it was immediately taken; and the effect was not only to produce a stream of cold air, but also to supply a quantity of moisture which is prejudicial to the smelting process. Atmospheric air always contains moisture in some degree or other, but holds a larger proportion in hot than in cold weather, for a very obvious reason, and this causes the furnaces not to work so well in summer as in winter. By the previous drying and heating of the air these inconveniences are remedied, the consumption of fuel is lessened, and the absence of moisture is said to have a beneficial effect upon the quality of the iron produced. This improvement was the invention of Mr. Neilson, of the Clyde iron-works, and was made the subject of a patent in 1829. The air, before it is forced into the furnace, is heated in cast-iron vessels to 300° Fahr., or more, and is thus more nearly than when at its natural temperature in a condition to support combustion.

The precise value of the hot-blast has been a subject of very animated controversy. That it has contributed greatly to the advance of the manufacture is beyond all question; but some persons appear to carry this estimate to too high a degree. Just before Mr. Neilson introduced his method at the Clyde Works, it was customary in that establishment to use eight tons of coal for making one ton of iron; in the next following year the quantity was reduced to five tons and a quarter, with an addition of eight cwt. for heating the air before using. In 1831, Mr. Dixon, of Calder Works, found that if the temperature of the blast were raised far above 350° Fahr., raw coal might be used instead of coke in the blast furnace-a most important discovery, for it rendered unnecessary the cost of time and money in coking the coal for making certain descriptions of iron. From that time it became usual to raise the blast to 600° Fahr., about sufficient to melt lead or zinc. In 1833, it was asserted that three tons of coal sufficed, including that for heating the air, for smelting one ton of iron; and that the same quantity of air would blow four furnaces as had previously been used for three. The hot-blast has from the first been more favoured in Scotland than in Wales or in Staffordshire; nevertheless it is increasing everywhere in use. Mr. Truran takes exception to some of Mr. Mushet's statements concerning the enormous saving effected by using the hot-blast. He contends that only a part of the economy

passes, in their diameter, their power, their closeness, or the size and shape of their grooves. In some of the establishments, the roughingrolls, or those first used, are of vast size and weight-as much as 64 feet long by 22 inches in diameter, requiring great steam-power to

Fig. 6.-Puddling Rollers.

All the processes of refining, puddling, and blooming, like those of smelting, have undergone numerous improvements within the last few years. Refining is always needed for making the best iron; but it is not so much adopted as formerly for the medium kinds. Sometimes, instead of refining and puddling, a process called boiling is adopted; and this practice has of late been greatly extended. Those who 'boil their pigs,' as it is termed, do so under the impression that it obviates some of the waste involved in refining. The boilingfurnace differs in some particulars from the others. Into it is put a portion of hammer-slag, then pig-iron, and then fresh coal. The metal is kept almost in a boiling state for half an hour, the puddler working it about all the time; a cinder or heavy slag falls to the bottom, and the gradually-thickening iron is worked about into balls. As generally conducted, the melting occupies about half an hour, the boiling half an hour, and the balling an hour. All the manufacturers admit that refining and puddling produce the best iron; but they differ in opinion concerning the relative advantages of boiling for the middling and cheaper qualities. Boiling is less in favour in South Wales than in Staffordshire. When the iron has been worked about into balls or blooms, either by refining and puddling, or by boiling, the blooms are, as we have said, shingled, or beaten with a few blows of a heavy hammer; this is admitted to make the best iron; but the makers of inferior kinds prefer to use a machine called a squeezer, because it leaves some of the slag in the metal, and thereby increases the quantity. Mr. Brown, of the Oak Farm Ironworks, has recently introduced a machine for this purpose. Three excentric cams work simultaneously; they are kept rotating in one direction by wheels and pinions, worked by steam power. The convex sides of the cams are grooved and serrated. A bloom of white-hot iron being dropped into the concavity of the upper cam, it is drawn into the centre of motion of the three cams; the convexities approach nearer and nearer, and the serrations squeeze and knead the iron like dough. The slag and impurities are expelled, more or less completely, and fall out of the machine. By the approximation of the cams, the iron is sent out as a sort of cylinder. This may be the best place to notice a plan brought forward by Mr. Maudslay, in 1858, for producing cast-iron possess ing a degree of toughness almost equal to that of the best wrought iron for the steam-engine manufacture. The plan consists in the employment of an entirely novel furnace, which revolves on an axis inclined about 10° from the perpendicular. The rotation is maintained by a system of gearing and toothed wheels, actuated by steam power. The iron being brought into a molten state in the furnace, and being kept constantly stirred, the two movements of rotation and stirring afford great opportunity for the sulphur and other impurities to escape from the mass and to fly off. The iron becomes semi-puddled; it retains a sufficient degree of fluidity to be cast into moulds, which fully puddled iron does not; while it has more fibre and toughness than pig or raw iron. The metal is, in fact, precisely in a medium state between pig-iron and malleable-iron.

Rolled Iron. We shall adopt this as a convenient name for iron in a more advanced state. We have seen that the crude smelted metal constitutes pig-iron; that when this is run into moulds it becomes cast-iron; and that when the pigs have been refined and puddled, or boiled, the result is malleable-iron. This malleable iron is the substance from which are made bars, rails, nail-rods, wire, sheets, &c., all of which we may consider to be varieties of rolled iron, since they all pass between the nearly touching surfaces of ponderous iron-rollers.

When the blooms have been shingled or squeezed, and roughly rolled into bars, in the manner already described, and while yet hot, they are cut into convenient lengths and taken to the balling-furnace, the shape and construction of which resemble the puddling-furnace. In this balling-furnace the bars are piled evenly, so that one bar does not project beyond another. Several of these piles, each of which is composed of five or six bars, are placed at once in the furnace, and when sufficiently heated, so that they will weld together, the piles are taken out separately and are passed again through rollers similar in construction to those described above, but differing from each other in the form of their orifices and grooves, so that either round or flat or square rods and bars may be produced at the pleasure of the

maker.

In the production of various kinds of iron from the malleable state,

Fig. 7.-Rolling Bar-iron.

rotate them. Some of the achievements in rolling bars are very remarkable. When the Great Exhibition of 1851 was about to be held, the Rhymney Works in Monmouthshire produced the largest and heaviest rail ever made, being 52 feet long and weighing 1575 lbs. Thereupon, the workmen at the Tredegar Works voluntarily undertook, for the honour of their firm and not for pay, to produce a still larger rail; their specimen was 60 feet long, but a few pounds lighter than that from Rhymney. The rolling of iron into rails, bars, and rods is very similar in its character, seeing that there are grooves in the rollers for all these kinds. In producing sheet-iron, however, this is not the case; the rolls are smooth, and the gradual thinning of the sheet results from bringing the rollers more and more closely into contact. In preparing the sheets for various manufacturing purposes, a machine is sometimes used, one end of which cuts the iron as if it were a piece of pasteboard, while the other pierces it for the reception of rivets.

It is right to mention here, that the rolling of iron was one of the capital inventions of Richard Cort, who, by a series of scandalous actions on the part of a government officer, and laxity in official morality generally, was brought to utter ruin in the attempt to carry out a system which has greatly enriched the iron manufacturers of this country. The whole case is being minutely narrated by Mr. Webster, the barrister, in a series of papers in the Mechanics' Magazine' for 1859 and 1860.

Projected Improvements.-It is impossible to notice here all the novelties introduced or proposed in the iron manufacture within the last few years; but there are three concerning which a few words may be given: namely-the production of iron direct from the ore; the utilisation of slag; and the utilisation of the gases and heated air of the blast-furnace. The process introduced and warmly advocated by Mr. Bessemer will best be noticed in connection with STEEL MANUFACTURE.

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The making of wrought-iron direct from the ore is now attracting much attention in the United States. The iron is in this case not puddled, as it never melts; but having first been deoxidised in a close chamber, it is simply welded together. There are many patented processes at work to this end. In one, Kenton's, the surplus heat from the reducing chamber passes round a series of tubes where the other processes are going on, insomuch that one mass of fuel avails for the whole operation. Another, Davis's, begins by pulverising the ore, mixing it with 20 per cent. of coal, putting the mixture into an airchamber heated by anthracite, and thence passing it to a sort of puddling-furnace heated by the same fuel. A third, Harvey's, employs the gases generated in the furnace to act directly on the ore in deoxidising and desulphurising it, without making the puddling process a distinct one. The object of all these plans seems to be to save fuel and labour; but English manufacturers have not yet seen reason to place much reliance on the methods.

The utilisation of slag is an important matter, if practicable; for there are millions of tons of it lying waste, all of which is known to contain a certain per-centage of iron. Professor Bleekrode, in a communication to the Society of Arts in 1859, drew attention to this matter. Of the vast heaps of slag now existing some are modern, while some are the remains from ancient works. The Swedes make good

iron from the slag of their old charcoal smelt-works, in a furnace suggested by Sefström in 1821. At Liege slag is mixed with the poorer ores, and smelted. The Silesian slag has been utilised since 1855, by mixing it with a certain per-centage of argillaceous schist and limestone. The same thing is done in Austria. The slag of the Dean Forest Works used to be made into a peculiar kind of black bottles at Bristol. Numerous processes have been patented in England within the last few years for rendering the slag useful, generally by mixing it with lime or limestone. Dr. Percy has recently observed: "An immense quantity of iron slag, far richer than many iron ores, is annually thrown away. It may be that the presence of phosphorus in sensible quantity is one of the causes which prevent the re-smelting of this slag with advantage. This fact has not yet sufficiently attracted the attention of those engaged in the manufacture of iron. The discovery of a method of extracting economically good iron from these rich slags would be of great advantage to the country, and could not fail amply to reward its author." Among the seven million tons of slag supposed to be annually produced in this country, many specimens are very beautiful when cast into moulds, looking like marble and serpentine when polished. Hence have arisen certain plans of utilisation, irrespective of the re-smelting for the sake of the metal. But there are drawbacks. If exposed to the air, the slag becomes oxidised and rusted; if not well annealed, it becomes friable; if in every way well prepared, it takes so much labour and fuel to work it that it ceases to be a commercially profitable material.

The third subject, the utilisation of waste heat, was taken up a few years ago by the Ebbw Vale Iron Company of South Wales. After a furnace has performed the work for which it is intended, various gases escape with the smoke, at the upper orifice; and these gases carry with them a large amount of valuable heat. If the heat could be abstracted and usefully applied, without lessening the power of the furnace, an economical benefit would result. The above-named company had eleven blast-furnaces, five engines to produce the blast, and twenty-five boilers to supply the engines with steam. The greater number of these boilers were wholly heated by the waste heat from the blast-furnaces; and various ovens and stoves in the works were heated by similar means. The heated gases were arrested near the top of the furnace, carried out by a horizontal tube, mixed with atmospheric air admitted in thin sheets or layers, and ignited by a small fire. It formed a true gas-light; and this gas-light heated a large flue, which was surrounded by a boiler containing water; and thus was a supply of steam obtained. These operations at Ebbw Vale depended on the combustion of the furnace gases; and the Ystalyfera Works modified the process by mixing the gases more thoroughly with atmospheric air. At the iron-works generally, however, it is considered that there are disadvantages which counterbalance the supposed saving; and neither plan has yet been very extensively acted on.

Iron Trade. The expansion of the iron trade is one of the most remarkable things in the history of our national industry. When charcoal was used for fuel; when there were no steam-engines to force in a blast; when the air employed for the blast was cold; and when there were neither rolling-mills nor shingling-hammers, a large production was impossible. Nor was there such a demand as would make even an approach to that which now exists; for iron bridges, iron ships, iron houses, iron roads, iron pontoons, iron cables, iron articles-from Great Easterns' down to shirt-buttons-are things of the present. It is supposed that in 1740, the produce of iron in Great Britain was about 17,000 tons. In 1750, a bill was brought into parliament, in the interest of iron-purchasers, for the importation of iron from the American colonies. This was opposed by the tanners, on grounds not very easy to guess à priori, but curiously illustrative of the spirit of protection. If, it was argued, colonial iron be admitted, English iron masters would be undersold; if so, some would be ruined and others would leave the trade; if so, many of the furnaces and forges would be put out of blast; if so, less wood would be used for fuel; if so, there would be less oak-bark in the market; and if so, the tanners might suffer from a deficiency of tan-material. Later in the century, however, when improvements and new appliances were numerous, it mattered little whether colonial iron was imported or not; seeing that the home produce would supply all demands. By 1788, the produce reached 68,000 tons; the weekly produce from the blast-furnaces averaged about 20 tons each. By 1796, the produce was 125,000 tons, and the weekly average per furnace 27 tons (taking the celebrated Dowlais works as an exemplar). Approximate estimates made at different times, set down the quantities of pig-iron made at 250,000 tons in 1806, 400,000 tons in 1820, and 690,000 tons in 1827; the average produce per furnace being raised in those same years to about 42, 62, and 70 tons per week, partly by the adoption of larger dimensions in the furnaces themselves, and partly by improved processes.

The introduction of the hot blast by Mr. Neilson in 1829 was shortly followed by a very remarkable extension of the manufacture. The produce of 1836 was about 1,000,000 tons, and the weekly average per furnace about 85 tons. The year 1839 was the first for which any trustworthy statistics were obtained, the estimates for previous years having been little more than guesses. Mr. Mushet, for that year, set down the number of blast-furnaces at 430, of which 377 were at work, producing about 1,250,000 tons in all. Of the furnaces in blast, 135 were in Wales, 188 in England, and 54 in Scotland; Wales had the

largest yield per furnace, but England the largest total yield. Soon after this period the Scotch manufacturers made such an enormous extension of the trade, that they quite glutted the market. The large profits led to the building of new furnaces; the discovery of blackband in the Airdrie district increased the available store of cheap raw material; the hot-blast effected a saving in the coking of the fuel; and the Scotch banking system led to the advance of capital almost to a reckless extent. Hence the produce of pig-iron in Scotland, which had been only 37,000 tons in 1830, rose to 197,000 tons in 1839, and 276,000 in 1843. It was especially in 1841 that the Scotch makers glutted the market, at a time when the demand was not brisk; Staffordshire and South Wales suffered severely, for they could not manufacture at a profit, at the prices established by the Airdrie masters. The railway mania of 1844-5, however, revived the trade; the companies not only took all the railway-bars available, but called for so enormous a quantity that new furnaces were needed to supply it. In 1845. Scotland alone made 470,000 tons of iron, of which no less than 234,000 were shipped at the Clyde for England and elsewhere; in 1846 these numbers rose to 522,000 and 277,000 tons respectively. Advancing to the year of the Great Exhibition, we find that Scotland produced in 1851 the vast quantity of 803,000 tons; which was increased to 840,000 in 1853. It had by this time been discovered that Scotland could make raw or pig-iron at a cost only a little exceeding 21. per ton; from 1848 to 1853, the market price varied from 21. to 31.; many of the furnaces being thrown out of blast in the season when the market price only reached, or barely reached, the cost of production. Bar-iron fluctuated much more considerably; for it differs more in quality, and has had a larger amount of labour bestowed upon it, than pig or crude iron; it was sometimes as low as 51. per ton, sometimes as high as 107. Mr. Braithwaite Poole gave an estimate of the iron produce of 1852, for the whole kingdom; from which it appears that there were 497 furnaces in blast, 158 out of blast, and nearly 2,700,000 tons of iron produced-of which England produced 1,190,000, Scotland, 775,000, and Wales 716,000. The authority for this estimate was, however, not given; and so far as Scotland is concerned, it falls short of one given by Mr. Scrivenor.

The most trustworthy statistics of the iron trade of Great Britain, and the latest available in date, are probably those of Mr. Truran, published in his volume on the 'Iron Manufacture.' This engineer was manager of Guest's vast establishment at Dowlais, and afterwards of Crawshay's at Hirwain; and consequently had the best means of acquiring a practical knowledge of the whole subject. His figures refer to 1855. He gives the name of every iron-work in Great Britain; the number of blast-furnaces at each; the weekly power of production at each furnace; and the aggregate power of produce in the year. Avoiding all the minute detail, some of the more general results may be given here, dividing the island into districts for facility of comparison:Weekly Average.

Districts.

Total Produce.

No. of No. of Iron Works. Furnaces.

Shropshire

These figures present much which is worthy of notice. The total producing power in 1855 was about 4,400,000 tons, made in 746 blast furnaces at 227 iron works; presenting an average weekly producing power of 113 tons per furnace. The shares of produce were, in round numbers, England 2,080,000; Wales 1,240,000; Scotland 1,080,000. In the South Wales district, the great Dowlais Works alone figure for 18 blast furnaces and a produce of 108,000 tons. The South Staffordshire district had numerous works, but none very large, the highest comprising five furnaces; the weekly yield varied from 80 to 150 tons per furnace. The Scotch works comprised many of large extent, such as the Gartsherrie with 16 furnaces, and the Dundyvan and Monkland with 9 each; the produce was very high, for none of the furnaces figured for less per week than 120 tons, and the average rose to 145. The most surprising advance, between 1839 and 1855, had been made in the Tees district, or Durham and North Yorkshire, owing to the discovery of ironstone in the Cleveland hills. This district had only 5 furnaces, of 50 tons weekly yield each, in 1839; whereas it had 79 furnaces, of 132 tons yield, in 1855. The largest or most powerful furnaces were in Monmouthshire (belonging to the so-called South Wales iron district), where some of them had a yield of more than 200 tons per week.

Mr. Truran was careful to state that the above were the producing powers of all our iron works, if all the furnaces had been in full blast throughout the whole year. But this is never the case; there are always many furnaces out of blast, and many periods of slackened