The Anthracite Iron Industry


Without question, it was the development of the iron industry – employing anthracite coal as fuel – which propelled the United States into a world power for more than a century. The vast iron and steel industry was born; fortunes were made, hundreds of thousands of workers gained employment and the product was used in the building of railroads, ships, skyscrapers and munitions. This evolution – begun in the late 1830s -- was made possible by the development of the Pennsylvania anthracite coal fields and the harnessing of the powers of the Lehigh, Schuylkill and other rivers for transportation and power.


Prior to the development of anthracite as a blast furnace fuel, charcoal was the fuel of choice for furnaces.  Charcoal furnaces could be found everywhere. But charcoal was frangible – large/tall furnaces could not be employed – the charcoal would be crushed by its own weight, then block the passage of air through the furnace. (See Temin, Iron and Steel in the 19th Century – The Hot Blast.)  Coal – “stone coal” – did not suffer from this mechanical deficiency. The ironmasters of the day recognized this. But anthracite coal had a problem that which has been addressed on a previous page – it would not burn in a blast furnace environment.


The first of the large anthracite-fired blast furnaces erected at the Crane Iron Works in Catasauqua, Pa. in 1839 – 40. It was 45 feet tall. A description of the erection is given in Thomas, Samuel, Reminiscences of the Early Anthracite-Iron Industry.  Click here for an enlarged view of the drawing where the details of the drawing can be read.


The history of the events which led to the successful establishment of the technology required to perfect the anthracite-fired blast furnace has been thoroughly documented. In this page, the highlights are given along with links to publications which provide thorough documentation.  The bottom line is that although many, many talented and industrious men contributed to this effort,  the individual that is credited with successfully implementing the processes in a commercially-viable operation was David Thomas, a Welshman, at the Crane Iron Works in Catasauqua, Pa. in July 1840.

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David Thomas, The Father of the American Anthracite-Fired Iron Industry. Thomas’s biographies can be accessed here.


The real key to the use of anthracite was employment of what is known as the “hot blast”. Here, the air that is blown into the base of the furnace is heated to a temperature of at least 300F prior to injection into furnace through pipes known as tuyeres. Credit for the first implementation of this hot-blast process is given to Scotsman James B. Nielson who was seeking to improve the operation of coke-fired furnaces in his native land. Nielson received a patent covering the process in 1828 – a dozen years before the technology was employed by Thomas at the Crane works. Information of Nielson’s success reached George Crane at Yniscedwin, near Swansea in Wales, where he and his ironmaster, David Thomas were experimenting with anthracite. (There were anthracite fields in that area of Wales.)  Thomas visited Neilson, received a license for the process, and succeeded in employing the technology at Yniscedwin in 1837. Word of that success reached the Lehigh Coal and Navigation Co. who dispatched Erskine Hazard to Yniscedwin to negotiate a contract whereby the technology would be brought to America.  The result was that David Thomas agreed to emigrate to America and it was he that had the Crane Iron Works  built in Catasauqua.


How was the hot-blast actually implemented?  In the beginning, Nielson simply employed a modest-sized stove, fired with coal, through which ran metal ducts carrying the blast air. The amount of temperature rise achieved was quite modest, perhaps 200 F, but it was adequate for Nielson’s purpose (his furnaces were fueled by coke.)

Nielson’s early stoves. The tapered pipes are the tuyeres (twyers in England). Source, Turner, Metallurgy of Iron.



Other experimenters recognized that the waste gases from the blast furnace could be used to heat the air, and mounted heat exchangers at the top of the blast furnace stacks. Again, a modest temperature rise was achieved.


Example of a heat exchanger placed on top of a furnace for  preheating air for the blast. Hot gas emerging from the top of the furnace (1) was deflected by the iron plate (7) into the chamber (2) containing cast iron pipes (5) and passed out the stack covered with the damper (3). The blast engine pumped air up the sheet-iron pipe (4), through the iron pipes, where it was heated, and down the cast iron pipe (6) to the tuyere.  Source: Gordon, American Iron.



It is not clear what type of construction that Thomas used either at Yniscedwin or at Catasauqua, but in Reminiscences Samuel Thomas comments that the structures were substantial.  According to Johnson, the blast was heated in four ovens, each having twelve arched tubes of five inches interior diameter, and two inches thickness of cast iron. No indication of the oven size is given. Eventually, (ca. 1850) furnaces built in Pennsylvania and elsewhere employed what were known as Cowper’s Stoves and Whitwell stoves. These were almost the size of the blast furnace itself, were used in pairs with a spare included so that three stoves per furnace was common place. Indeed, the stoves sometimes dominated the scene of the iron works. These stoves were of the regenerative type where the hot waste gas from the furnace heated a lacework of brick inside the tower for a period of time, then the hot gases were routed to the second furnace while the blast air valve was opened and the blast air picked up the heat from the brickwork.  The details of this process have been documented by Turner – an excerpt of his work which covers the evolution of hot-blast furnace design is available here.


An illustration of a Cowper’s Stove. The unit on the left is being heated by waste gases; the unit on the right is heating the blast air. Source: Turner,  Metallurgy of Iron


During this time period, when the effectiveness of the hot-blast had been recognized, there were other experiments being conducted in Pennsylvania on firing furnaces with anthracite coal. A complete accounting of these activities is given by Johnson, Notes on the Use of Anthracite in the Manufacture of Iron, 1841. (That account can be accessed here. A concise accounting was given by William Firmstone in an AIME paper in 1874.))   Some of these efforts partially succeeded but none demonstrated the sustained operation that was necessary to attract investors. Why did Thomas succeed where others failed?  The answer seems to be in the thoroughness and attention to detail which Thomas applied in the construction of the Crane Iron Works – not only with respect to the hot blast, but to the construction of the blast furnace itself, the capabilities of the blowing machinery, the raw materials employed, etc. That is the conclusion of W. Ross Yates in his thorough review of the subject in Discovery of the Process for Making Anthracite Iron published in 1974. (That review can be accessed here.)


Software: Microsoft Office

The Crane Iron Works, The Thomas Ironworks in Hockendauqua, Pa. (founded by David Thomas after his contract with George Crane had been fulfilled), and many other anthracite works in the Lehigh Valley and vicinity prospered for many years. Fortunes were made by the owners of these installations.  The decline of the industry began along with the Panic of 1873, as financial conditions deteriorated and competition from other regions of the country where coal and ore were cheaper began to take a hold. Larger and more efficient operations integrated the open-hearth and Bessemer processes for making steel. Eventually, in the 1920s, the only furnaces operating in the Lehigh Valley were those of the Bethlehem Steel Company.


A news article published in 1875 described the industry decline. Click here to view the article.


Our specific focus in this very brief overview of the anthracite iron industry has been on the Crane Iron Works, not only because it marked the initial commercial success of the industry, but because it was at the Crane Ironworks where Hopkin Thomas completed his career begun 50-years previously with his friend David Thomas at the Neath Abbey Ironworks in Wales. In 1853, after his engineering successes in the locomotive-building business and the coal mining business, Hopkin Thomas came to serve as Master Mechanic (Chief Engineer) at the Crane. Those activities are described in the following chapters.


Details of what has been highlighted above appear in many publications. Following is a list of the more useful sources.


Johnson, Walter R., Notes on the Use of Anthracite in the Manufacture of Iron.  This early (1841) account provides data on the use of anthracite in early blat furnaces – at the time industrialists, entrepreneurs, and capitalists were all striving to have the industry succeed as a commercial activity. Johnson was a mining engineer and professor of chemistry, so the account is highly technical.


Yates, Ross R., Discovery of the Process for Making Anthracite Iron.A scholarly review of the early developments in the anthracite iron industry. Yates was a professor at Lehigh University. The article is thorough with references cited for all significant events described.


Bartholomew, Craig L. and Lance E. Metz, The Anthracite Iron Industry of the Lehigh Valley.  Published in 1988, this publication deals with iron production activities in the Lehigh Valley from the early beginnings to the date of publication. It is a complete compendium of the activities conducted by many industrial operations.


Turner, Thomas, The Metallurgy of Iron.  This publication gives a thorough accounting of the development of the hot-blast process up to the late 1800s. Other subjects including steel making are covered in this comprehensive work.


Bining, Arthur Cecil, Pennsylvania Iron Manufacture in the Eighteenth Century. This scholarly work deals with the iron industry during the period before anthracite was developed as a primary fuel.


Gordon, Robert B., American Iron, 1607 – 1900.  Part of a series on the history of technology, this 340 p. book covers developments in the industry throughout the entire country.


Temin, Peter, Iron and Steel in the Nineteenth Century, An Economic Inquiry. A well researched review of the industry published in 1964 – including a section on the hot blast.


Swank, James M.,  History of The Manufacture of Iron in All Ages.   An often-cited classic history published in 1892 covering activities throughout the word. A chapter on the development of anthracite coal as fuel is comprehensive, covering many activities in Pennsylvania, including David Thomas’s contributions.


Williams, Peter N., David Thomas: Iron Man from Wales. A monograph devoted to David Thomas with emphasis on the social conditions existing in Wales at the time of Thomas’ emigration. The final chapter emphasizes the difficulties that Thomas overcame in the building of the Crane Iron Works.


Guide-Book of The Lehigh Valley Railroad, Appendix B. A thorough examination of who should be given credit for the first successful use of anthracite coal in the smelting of iron. Letters written by those involved in the various efforts are the central theme of this examination.




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Rev. February 2010