On Tuesday evening Philip attended an event at City, University of London, for the unveiling of a blue plaque to the inventor and entrepreneur Sir Henry Bessemer. Bessemer lived for some time in a house at Northampton Square in Islington, in a block that was demolished after World War II for the construction of the universityâ€™s current main entrance building. When the main entrance was reconstructed recently, archaeological investigation confirmed that Bessemerâ€™s home had been directly on its site. After the plaque unveiling, Dr. Susan Mossman from the Science Museum delivered a lecture on Bessemerâ€™s life, from which much of the information in this post comes.
Bessemer is best known for his revolutionary process for steel manufacture, by blowing air through molten pig iron in an egg-shaped converter, to oxidise away most of the carbon in the pig iron. This left steel with the correct proportion of carbon to make it a useful metal. The process was covered by several British patents in 1855-6, but especially GB2321/1855 and GB2768/1855. These patents are not online, but you can see digital copies of them if you come to our reading rooms.
Bessemer preferred to licence his patent rather than build an ironworks himself, but many early licensees failed, and the process was considered a flop until he constructed an ironworks in Baxter Road in Saint Pancras, close to where the British Library is now, and began selling steel at far lower prices than anyone else could manage. It turned out that the process as Bessemer first conceived it was not suitable for iron containing high levels of phosphorus impurities, which was true for metal from ore mined in Northern England. One answer was to oxidise away the contaminants, which also destroyed the carbon already in the pig iron, and then add new carbon and manganese. This process was developed by Robert Forester Mushet, whose business failed but whose process Bessemer took over once Mushetâ€™s patent expired. Bessemer was finally, reportedly shamed by Mushetâ€™s daughter, persuaded to give Mushet a pension. The second answer was the Gilchrist-Thomas process, which lined the converter with alkaline stone, causing the acidic phosphorus compounds in the iron to form compounds that precipitated out of the steel and into the slag. With these further refinements Bessemerâ€™s process became licenced worldwide, making Bessemer hugely rich, and did not become completely obsolete until the late twentieth century.
Bessemer had already come up with many other inventions before his steel process, and would continue to do so afterwards. The most lucrative was his first real success, before steel, a method for making bronze powder for metallic paints on an industrial scale, hugely reducing the cost of a product which had previously been made by hand-grinding by craftworkers in Germany. Bessemer kept the process secret for decades, by ensuring that the machines were kept in four sealed rooms with strictly limited access, and that few people other than himself knew more than one of the four stages of the process. This helped him keep a monopoly much longer than the fourteen years he would have had if heâ€™d patented the process. Bessemer was a shrewd businessman who would only continue working in a field as long as it made money. Once competitors had caught up with him he would move on to something else.
Another of Bessemerâ€™s claims to fame was his early investment in â€śParkesineâ€ť, the first commercialised artificial plastic, a form of celluloid. The business was a failure due to initial low quality, but remains historically important. At the time of his death, Bessemer was having what would have been the worldâ€™s second largest telescope constructed at his estate in Denmark Hill, but it was abandoned when he passed away.
Bessemer remains an inspiring figure for modern British inventors, but the story of his steel process also demonstrates some important lessons that dispel some of the romantic ideas of the inventor. Firstly, always be open to taking on the ideas of others instead of believing your own ideas to be perfect and unimprovable. Second, you may well have to start your own business instead of assuming that other people will be falling over themselves to licence your idea. Third, always think about whether an invention will make money, as well as its abstract beauty. And fourth, it helps to have plenty of money to invest before you start!
Patents by Henry Bessemer, in the Business & IP Reading Room at St Pancras.
An earlier blog post by Dr. Mossman on Bessemerâ€™s life.
Bessemer, H and Bessemer, H Jr. Sir Henry Bessemer, FRS: an autobiography. London: Engineering, 1905. Available for order to our Reading Rooms at 10825.k.7 or Wq3/9544.
Bodsworth, C (Ed.). Sir Henry Bessemer: father of the steel industry. London: Institute of Materials, 1998. Available for order to our Reading Rooms at YK.1998.b.6654 or 2247.795000 690.