Henry Bessemer and the Bessemer Process for Cheap Steel

Sir Henry Bessemer (1813-1898) was the English inventor and engineer who developed the Bessemer process, the first inexpensive industrial method for the mass production of steel from molten pig iron. Patented in 1856, the Bessemer process transformed the steel industry, made possible the great expansion of the railway, shipbuilding, and construction industries in the second half of the nineteenth century, and laid the foundation for the Second Industrial Revolution.

The Problem of Cheap Steel

To understand the importance of the Bessemer process, it helps to understand the steel industry of the mid-nineteenth century. Steel, an alloy of iron and carbon that is stronger, harder, and more versatile than either iron or wrought iron, had been known for centuries. But producing steel in large quantities was difficult and expensive. The traditional method, the cementation process, involved heating bars of wrought iron in a sealed furnace with charcoal for several days, and it produced only small quantities of high-quality steel at high cost.

The result was that steel was a relatively scarce and expensive material, used mainly for specialized applications such as cutlery, springs, and tools. The great iron bridges, the iron-framed buildings, the iron ships, and the iron railways of the early nineteenth century had been built with iron rather than steel, because steel was too expensive. The need for a cheaper method of producing steel was clear, and several inventors had tried to develop one.

Bessemer’s Background

Henry Bessemer was born in 1813 in Charlton, Hertfordshire, the son of an artist and inventor. From a young age, he showed a talent for mechanical invention, and he obtained his first patent, for a method of stamping letters on envelopes, at the age of just 17. Over the following decades, he patented a wide range of inventions, including a process for making bronze powder, a sugar-refining machine, and a method of manufacturing gold chains.

Bessemer was not a trained metallurgist, but he was a skilled experimenter with a practical approach to problem solving. He was also an effective businessman, and he made a substantial fortune from his various inventions before turning his attention to steel.

The Invention of the Bessemer Process

The Bessemer process was developed in the 1850s, partly as a result of the Crimean War. The British military had discovered that the cast-iron cannons of the time were prone to bursting, and the government had offered a prize for a better method of producing strong, reliable gun barrels. Bessemer, who had been working on a new type of projectile, became interested in the problem of strong metal.

Through a series of experiments, Bessemer discovered that blowing air through molten pig iron burned off the excess carbon and produced steel rather than wrought iron. The process was rapid, taking only about 20 minutes to convert a charge of molten iron into steel, and it could be carried out in a single vessel, the Bessemer converter.

Bessemer patented the process in 1856, and he announced it at a famous meeting of the British Association for the Advancement of Science. The announcement was met with skepticism by the established metallurgists of the time, but Bessemer pressed on with the development, and within a few years the process was being used in steelworks around the world.

The Initial Difficulties

The early Bessemer converters had a serious problem. The steel they produced was often brittle and unreliable, because the process did not remove the phosphorus that was present in most British iron ores. Phosphorus made the steel brittle, especially at low temperatures, and it limited the usefulness of the Bessemer process for the iron ores of Britain.

The problem was eventually solved by Sidney Gilchrist Thomas and Percy Gilchrist, who in 1878 developed the basic Bessemer process, in which the converter was lined with a basic material (such as dolomite or limestone) rather than an acidic material (such as silica). The basic lining reacted with the phosphorus and removed it from the iron, producing steel that was suitable for a wide range of applications. The basic Bessemer process was particularly important for Britain, which had large deposits of phosphoric iron ores, and it helped to ensure that the British steel industry remained competitive with the steel industries of Germany and the United States.

The Effects of the Bessemer Process

The Bessemer process had several major effects on the steel industry and on the broader economy. It dramatically reduced the cost of producing steel, and it made possible the mass production of steel in quantities that had been unimaginable before. The price of steel fell sharply, and steel was gradually substituted for iron in many applications.

The most important of these applications was the railway. The Bessemer process made it possible to produce steel rails in large quantities, and steel rails gradually replaced the older iron rails on the major railway lines. Steel rails were stronger, more durable, and longer-lasting than iron rails, and they were particularly well suited to the heavy traffic of the main lines.

Steel was also used in shipbuilding. The Bessemer process made it possible to build steel-hulled ships in large quantities, and steel-hulled steamships gradually replaced the older iron-hulled ships and wooden ships. Among the earliest vessels often cited as the first all-steel ships are the small French steamer Ma Robert (1858) and, more securely, the British ironclad HMVS Cerberus (1871); by the 1880s steel-hulled ships were the norm.

The construction industry was also transformed by the availability of cheap steel. Steel frames replaced iron frames in large buildings, and steel was used in bridges, viaducts, and other structures. The availability of cheap steel made possible the great engineering works of the late nineteenth and early twentieth centuries, from the Forth Bridge in Scotland to the skyscrapers of Chicago and New York.

The Steel Industry and the Second Industrial Revolution

The Bessemer process was one of the foundations of the Second Industrial Revolution. The cheap steel produced by the process was the material that made possible the great steel industries of the late nineteenth and early twentieth centuries, from the Carnegie Steel Company in the United States to the Krupp steelworks in Germany.

The steel industry was also a major customer of the iron ore and coal industries, since the Bessemer converter required large quantities of both. The growth of the steel industry therefore stimulated the growth of the mining industries, and the demand for iron ore and coal helped to drive the development of new mining regions in places like the Mesabi Range in the United States, the Lorraine region of France, and the Ruhr Valley in Germany.

The steel industry was also closely tied to the development of the modern corporation. The great steel companies of the late nineteenth century, including Carnegie, Krupp, and the various combinations that would eventually form United States Steel, were among the first modern industrial corporations, with their complex structures of ownership, management, and finance.

Bessemer’s Later Career

Henry Bessemer continued to invent and to be active in the steel industry for the rest of his life. He developed a number of other important inventions, including a method of producing malleable iron, a process for making gold leaf, and various improvements to optical instruments. He was knighted in 1879 in recognition of his contributions to industry.

Bessemer died in 1898. By that date his process had displaced the cementation and crucible methods for bulk steel, and Bessemer steel rails, plates, and beams were in use across the railway, shipbuilding, and construction industries. The modern steel industry, with its giant blast furnaces, its continuous casting machines, and its computer-controlled rolling mills, is in many ways the descendant of the technology that Bessemer pioneered in the 1850s.

The Legacy of the Bessemer Process

The Bessemer process is often cited as one of the most important inventions of the Industrial Revolution, second only to the steam engine in its impact on the modern world. The availability of cheap steel made possible a wide range of technologies, from the railway and the steamship to the skyscraper and the automobile, and it helped to create the material basis of the modern industrial economy.

Before Bessemer, steel was a relatively scarce and expensive material, used mainly for specialized applications. After Bessemer, steel became a mass-produced commodity, available in vast quantities and at low cost. The transformation of steel from a specialty product to a mass-produced material is closely tied to the broader transformation of industry in the late nineteenth century.

The Continuing Question

The Bessemer process was patented in 1856 and almost immediately failed in practice: the early Bessemer steel was full of phosphorus-driven brittleness, and Bessemer’s own converter could not handle the high-phosphorus ores that made up most of the European supply. The unanswered historical question is who actually fixed the process. The standard answer credits the English metallurgist Robert Mushet, who in 1856-1858 patented the addition of spiegeleisen (a manganese-iron alloy) to the converter. The revisionist answer, developed in Thomas Misa’s A Nation of Steel (1995) and in the work of the iron-and-steel historian Peter Temin, is that Mushet’s patent was narrow and probably not enforceable, and that the practical Bessemer process was the work of the Swedish engineer Göran Fredrik Göransson, who in 1858 built a working converter at Högbo Bruk that handled the high-phosphorus ores that the English plant could not. The answer matters because the Swedish Bessemer process was the basis of the Belgian, German, and American industries, and the English patent pool lost control of the technology in the 1860s. The interesting current question, raised by Misa and by the comparative history of basic oxygen steelmaking, is whether the Bessemer “revolution” was really a revolution at all — or whether, like the spinning jenny and the puddling furnace, the public patent records the breakthrough, but the working technology was the work of a community of metallurgists in the 1860s and 1870s.

Selected Sources

Bessemer, Henry. Sir Henry Bessemer, F.R.S.: An Autobiography. London: Offices of “Engineering,” 1905.
Allen, Robert C. The British Industrial Revolution in Global Perspective. Cambridge: Cambridge University Press, 2009.
Landes, David S. The Unbound Prometheus: Technological Change and Industrial Development in Western Europe from 1750 to the Present. Cambridge: Cambridge University Press, 1969.
Misa, Thomas J. A Nation of Steel: The Making of Modern America, 1865–1925. Baltimore: Johns Hopkins University Press, 1995.