On the Progress, present Amount, and probable future Condition of the Iron Manufacture in Great Britain. By G. R. PORTER, F.R.S. IN obedience to the request of the Council of the British Association, made at its meeting in June 1845 at Cambridge,—a request from that body being equivalent to a command,—I avail myself of the first moment of leisure that has since presented itself, to investigate the condition of the iron manufacture in Great Britain. The incessant claims upon my time, of public duties, which have called in their performance for the most anxious and unremitting labour, throughout all of the present year that has hitherto elapsed, may perhaps be allowed to plead in excuse for the imperfect manner in which I am able to perform my task. I wish, most sincerely, that it had been otherwise, and that it had been possible to devote to its accomplishment an amount of time and a degree of research that might have enabled me to present a work more worthy of the acceptance of this body, and better proportioned to the importance of the subject. It was, doubtless, a conviction of the great and growing influence which the progress of the iron manufacture must exercise upon other important branches of our national industry, that led the Council of our body to desire information concerning it, and all that has since arisen in the course of our legislation has given additional interest to the subject, so that it has become more than ever of consequence to know the actual condition of this great branch of our industry, and of the capabilities which present themselves for its increase. The enormous demand for iron caused by the general and simultaneous construction of railways all over this kingdom, and not here only, but in various parts of Europe and in the United States of America, and also by their promised extension to India, is calculated to produce much of anxious inquiry into the subject, in order to ascertain, in the first place, whether, and in what way, that enormous demand can be met, and then to satisfy ourselves that through the cessation of that demand, which from its nature must be in a chief degree temporary, we may not be exposing to ruinous depreciation establishments for the formation of which vast capitals have been and will be sunk, in which many skilled workmen are trained, who during the continuance of the existing great demand will be receiving high wages, but who when it ceases may, many of them, be thrown out of employment, and who must be so, unless some new and permanent uses can be found for the produce of their industry. The object of the present inquiry does not call for any research into the remote history of the iron manufacture. It will not assist us in the solution of the questions now pressing upon our attention, to ascertain whether, in centuries preceding the Christian æra, when the Phoenicians traded with our ancestors for tin, the Britons did, as some writers have assumed, know and practise the manufacture of iron. Certain it is, that the rise of that manufacture upon any scale deserving of notice as a national object, dates from a time within the memory of persons now living. In 1788 the whole quantity of pig-iron made in England and Wales is said to have amounted to no more than 61,300 tons, of which quantity 48,200 tons were made with coke of pit-coal, and the remaining 13,100 tons were still made with charcoal (see Appendix No. 1). In the same year the production in Scotland did not exceed 7000 tons. In Ireland charcoal-iron was made on a moderate scale during the seventeenth century. Sir William Petty tells us in his 'Political Anatomy of Ireland,' that in 1672 the quantity of iron made there was about 1000 tons, giving employment to about 2000 persons of both sexes. Works established by Sir William Petty in the county of Kerry in 1660, continued to be carried on until the exhaustion of the timber in the neighbourhood brought them to a stand, and in 1788 there does not appear to have been any iron-work in existence in Ireland. About this time the iron-masters in Great Britain began to avail themselves of Mr. Watt's improvements of the steam-engine, and were thus enabled greatly and rapidly to increase the productive power of their works, so that in eight years from 1788 the quantity of British-made iron was nearly doubled. An inquiry made in 1796, consequent upon the proposal of Mr. Pitt, which was afterwards abandoned, to place a tax upon coal at the pit's mouth, showed the make of British iron to be then In England and Wales... 108,993 tons. Ten years later, in 1806, it was proposed to tax the production of iron, and again on that occasion an account was taken of the number of furnaces and the quantity of iron produced, which was found to have been more than doubled in ten years; the production being In England and Wales... 234,966 tons. ..... ...... 23,240 tons. Together 258,206 tons. (See App. No. 3.) Of this quantity it was stated that about 95,000 tons were converted into bars and plates, and that the capital engaged in the manufacture amounted to £5,000,000. The proposed tax was so powerfully opposed in the House of Commons, that the bill was carried through the Committee by a majority of only ten, and the measure was abandoned. The next account of this manufacture which has been given, was prepared by Mr. Francis Finch, formerly member for Walsall, and had reference to the year 1823. From that account (see App. No. 4) it appeared that in seventeen years the make of iron in Great Britain had been increased from 258,206 tons to 452,066 tons. Between 1823 and 1830 there were erected ninety-six new furnaces; and in the latter year it was found, on a further examination by Mr. Finch, that the quantity of pig-iron made in Great Britain amounted to 678,417 tons (see App. No. 5). Our confidence in the correctness of the quantities here stated should be confirmed by their having been adopted in his evidence before the Committee on Import Duties in 1840 by Sir John Guest, whose authority upon this subject is conclusive. From this time (1830) a series of improvements has been introduced into the processes of making iron, which has had the effect of improving the quality of the metal and of materially œconomising the cost of its production. One of the most important of these improvements was made the subject of a patent in 1829 by Mr. Neilson of Glasgow, and consisted in the artificial heating of the air previously to its being passed into the furnaces. The effect of this plan in saving fuel has been most remarkable. In 1829, at the Clyde Iron Works, where Mr. Neilson's experiments were made, and in which his patent was first adopted, it required more than 8 tons of coal, when converted into coke, to produce 1 ton of cast iron. This was when the air was forced into the furnace at its natural temperature. By heating the air to 300° Fahrenheit preparatory to its introduction, it became necessary to consume for each ton of iron produced only 5 tons 3 cwt. of coal converted into coke; but in heating the air to the required degree, nearly 8 cwt. of coal was consumed. The saving was thus found to be 21⁄2 tons of coal for each ton of iron. Thus encouraged, further experiments were made. The previous heating of the air was raised to 600° Fahrenheit, and it was then found, not only that a further great œconomy was produced in the fuel, but that coal could be used for smelting in its raw or uncoked condition. It was further discovered that the same blast-machinery, when the air was thus heated, sufficed for a greater number of furnaces, so that the power necessary for three furnaces, when cold air was employed, became ample for four furnaces of equal size when the air was previously heated. The result may be thus stated : In 1829, using coke and cold air, each ton of iron required for its production 8 tons 1 cwt. 1 qr. of coal. In 1830, using coke and heated air, each ton of iron was made with 5 tons 3 cwt. 1 qr. of coal. In 1833, using raw coal and heated air, each ton of iron was made with 2 tons 5 cwt. 1 qr. of coal. The saving in fuel is thus seen to amount to 72 per cent. The effect of the hot-blast upon the quality of the iron produced has been the object of many experiments to determine. As those experiments were in great part undertaken at the instance of the British Association, and as their results have been published from time to time in its Transactions, it cannot be necessary to notice them further here. Mr. Neilson's invention was for a long time greatly decried, and to this day it is the practice with some few of our leading engineers, when drawing specifications for works, to forbid the use of hot-blast iron. Under these circumstances, the introduction of this plan has been by no means universal in the iron-works of England and Wales, although it is otherwise in Scotland, where the increased make of iron, from 37,500 tons in 1830, to nearly 500,000 tons in the past twelve months, may be in great part, if not altogether, ascribed to the economy which Mr. Neilson's plan has occasioned. But for the introduction of that plan, we should in all likelihood not have witnessed the unequalled development exhibited during the past fifteen years in this, which has now become one of the greatest branches of our national industry. Without this discovery our railroad system could not have marched forward with such giant strides, and in all probability the application of iron to the building of ships,—an application from the extension of which, in future years, so many advantages may be made to arise,-might have continued unthought of. In a letter which has reached me while writing, from a most intelligent iron-master in the North of England *, the subject is thus noticed : "Previously to this invention, metal was made with such coal only as was easily destructible before the blast, thereby admitting a greater quantity of air into the furnace. Air is the food of fire. Coals of a stronger or more bituminous character were not serviceable; the current of cold air at the Tuyeres had the effect of caking the coal and choking the admission of air, by which the process of reduction was stopped. But when Mr. Neilson introduced his method the difficulty was conquered. By heating the air up to 600° Fahrenheit, the caking at the Tuyeres no longer took place; the air entered freely into the furnace, and coal hitherto unserviceable was enlisted into the service of mankind, and applied to the great improvement of their condition. "It was pretended that the metal made with hot-blast was not so good; that it was weaker; and for a long time it was tabooed in all contracts; but this delusion is gradually giving way to truth. There was no foundation for such prejudice. It is known that air does not burn until it reaches 3000° *Charles Perkins, Esq. Fahrenheit; the raising of it to 600° before admission to the furnace was nothing, nor did it destroy any of its elementary qualities; it only secured its admission and ensured its regularity of action in the process of reduction. This was an increase of man's power over elementary matter: it is by the additions to and the increase of this power that men will in time accomplish a greater and more powerful condition." The disinclination to adopt an innovation, which as we have seen in this case of the hot-blast, has not been entirely overcome by more than fifteen years' experience of its advantages, has not been confined to that instance, but has been allowed for a much longer period to influence, in another case, the proceedings of our iron-masters. It was as long ago as 1801, that Mr. David Mushet, to whom the world is greatly indebted for his scientific researches and his practical exertions in this important branch of metallurgy, discovered when crossing the river Calder, in the parish of Old Monkland, a description of ironstone, to which the name of black-band, or Mushet-stone, has been given. For many years following this discovery the black-band was used only in the Calder Iron Works, which were established in 1800 by Mr. Mushet, and it was not even there employed alone, but was used in combination with other iron ores of the argillaceous class. It was not until 1825 that it was first used alone by the Monkland Company, whose success in the experiment led gradually to its adoption by other establishments, and to the erection of additional works. Mr. Mushet, in his Papers on Iron and Steel,' p. 128, thus describes the advantages of this kind of ironstone : "Instead of 20, 25 or 30 cwt. of limestone formerly used to make a ton of iron, the black-band now requires only 6, 7 or 8 cwt. to the production of a ton. This arises from the extreme richness of the ore when roasted, and from the small quantity of earthy matter it contains, which renders the operation of smelting the black-band with hot-blast more like the melting of iron than the smelting of an ore. When properly roasted, its richness ranges from 60 to 70 per cent., so that little more than a ton and a half is required to make a ton of pig-iron; and as one ton of coal will smelt one ton of roasted ore, it is evident that when the black-band is used alone, 35 cwt. of raw coal will suffice to the production of one ton of good gray pig-iron." This calculation is strongly corroborated by a statement which was produced by Dr. Watt to the Statistical Section of the Association at Cambridge, from which it appeared, that to make 400,400 tons of iron in the counties of Lanark, Ayr, Stirling and Clackmannan, the quantity of coal consumed was 934,266 tons, or 2 tons 6 cwt. 2 qrs. 18 lbs. for each ton of iron, part of which is the produce of argillaceous ores. The statement of these discoveries appears necessary in order to account for the great and rapid extension given since 1830 to the production of iron in this kingdom, and especially in Scotland. In 1836 every iron-work in Great Britain was visited, and an account taken of its produce, by a highly-gifted gentleman, M. F. Le Play, "Ingénieur en chef," employed in the Ministry of Public Works at Paris, under whose direction are made the yearly reports describing the progress of mining industry in France, of which I have on former occasions availed myself in preparing papers read before this Section of the Association. The result of his inquiries showed that in that year the quantity of iron made reached to 1,000,000 tons, an amount then deemed almost incredible, but which in the years immediately following was greatly exceeded. In his Papers on Iron and Steel,' to which reference has already been had, Mr. Mushet states (p. 421) that the quantity of British iron made in 1839, was 1,248,781 tons (See App. No. 6). |