In part one, I emphasized the impact the Bessemer Process had on steel production capacity. To put it in terms everyone understands, aka money, the Bessemer Process decreased the price of 1 ton of steel from $95 to $11. In 2022 dollars, that's a decrease from $3,044 to $352 a ton.
Before Bessemer's invention, steel was produced with a slow, expensive, undependable process known as the crucible method. English metalworkers would heat wrought iron, typically imported from Sweden, in large stone containers. This process could pump out about 60 pounds of steel in 2 weeks. The Bessemer process produced 5 tons in 20 minutes.
Taming the Flames
That increase in efficiency is comparable to trading in a horse for a formula 1 racer. The speed at which high-quality steel could be produced increased exponentially. If steel was the fuel for the industrial revolution, then the Bessemer Process was the spark that lit the fire.
But the process alone was not enough. The chemical reaction involved in the Bessemer process was incredibly violent and he needed a contraption that could safely harness the reaction from start to finish. Bessemer first tried to find a way to calm the reaction. That failed, and Bessemer concluded extreme heat and ferocious eruptions were all necessary parts of his new process.
Accepting the need for some sort of vessel, Bessemer went to work, slaving away at the drawing board. What he dreamt up is what we know today as the Bessemer Converter.
The Bessemer Converter was a massive, two-story, egg-shaped, brick-lined furnace centered on a tilt mechanism. The bricks protected the metal shell from the insane heat and the tilt mechanism made it easier to load the converter with molten wrought iron and to pour out liquid steel after completion of the process. The converter had holes in the bottom connected to bellows which, as we've discussed, performed the innovative technique of blowing air through the molten iron.
Bessemer patented his process in February 18561. In his patent application, Bessemer explains precisely what is so innovative about his process. It's slightly more nuanced than simply introducing air streams to molten iron. Bessemer wrote:
I do not claim injecting streams of air or steam into molten iron for the purpose of refining iron, that being a process known and used before. I claim the conversion of molten crude iron or re-melted pig iron or finery iron into steel, or malleable iron, without the use of fuel for reheating or continuing to heat the crude molten metal, such conversion being effected by forcing into and among the particles of a mass of molten iron, current of air or gaseous matter containing, or capable of evolving, sufficient oxygen to keep up the combustion of the carbon contained in the iron till the conversion is accomplished.2
It's a bit confusing, but Bessemer is basically claiming to have improved upon a previously existing technique. In the context of Bessemer's life, "refining" referred to any process that removed impurities from iron. What Bessemer's process did differently than previous methods was "introduce a much more powerful blast of air... so that combustion occurs quickly enough to keep the iron molten while both silicon and carbon are completely burned out of the iron."3
Patent Drama
Historians are not aware of Bessemer ever claiming his idea was influenced by other inventors or metallurgists. However, shortly after his patent was published, a few inventors claimed Bessemer totally ripped off their discoveries.
The most notable claim was made by American inventor, William Kelly. The story goes that Kelly made the same discoveries as Bessemer, but several years sooner. When Bessemer's patent was reported by Scientific American, Kelly was incensed. He wrote to the publication with accusations of what could be described as corporate espionage. Kelly claimed that English "puddlers" visited his production facility where they observed his process. Kelly went on to speculate that those puddlers must have shared their observations with Bessemer.4
A New Jersey inventor also claimed to have filed a patent for the same process in 1855, a year before Bessemer did, but that his lawyer was corrupted by Bessemer into incorrectly filing the patent.5
Whether Bessemer wholly invented the process or not is a bit irrelevant. He got the patent and was much more successful at monetizing the process than Kelly or anyone else. Right off the bat, he licensed his process to four ironworkers for a total of 27,000 euros, or 893,000 2022 dollars.
The story isn't as simple as Bessemer working hard then cashing in. History doesn't stop there for 19th century English steel. In fact, the Bessemer Converter was a hit-and-miss methodology for nearly two decades. Production errors haunted forgers and perplexed metallurgists of the era. Several ironworkers licensing the Bessemer Converter had little luck producing the quality of steel the converter was advertised as capable of making on a consistent basis. Millions of pounds--both of money and raw iron--ended up wasted by early versions of the Bessemer Converter. Bessemer was even forced to recall a few licenses he had sold.
Unlikely Hero
Surprisingly, this problem plaguing professional scientists was solved by an amateur metallurgist, Thomas Gilchrist. Born in London in 1850, Gilchrist was not a professional chemist and he was only 28 years old when he discovered why the Bessemer Converter was so finicky.
Gilchrist spent most of his free time and money on experiments and science classes. After getting off his court reporter day job, Gilchrist would attend night classes and constantly fiddle with the Bessemer Converter problem. He eventually cracked the code in 1878.
The issue turned out to be chemical variation between iron ore deposits. Depending on the mine, some iron ore contained phosphorus while other ore contained none. Bessemer developed his converter using iron with no phosphorous and when ironworkers licensing the Bessemer Converter tried using phosphorized iron, the resultant steel was so brittle as to be useless. Gilchrist discovered that the Bessemer Converter could still remove phosphorous from iron if the brick lining is replaced with limestone. With that discovery came the creation of what we know today as the two types of Bessemer Converters: Acidic and Basic.
After years of iteration and countless experiments, the Bessemer Converter eventually became a staple in English steel production. On the year of Sir Henry's death in 1898, the Bessemer converter was used to produce over 84 million Euros worth of steel on an annual basis. That's more than 2.5 billion in today's Euros. Massive amounts of steel left Great Britain's production facilities and went on to help build the modern world.
But across the pond, another great innovator and entrepreneur was hard at work…
Part 3 coming next week
(Science and Civilisation in China: Volume 5, Chemistry and Chemical Technology, Part 11, Page 361, Paragraph 5, Ferrous Metallurgy, n.d.)
(Science and Civilisation in China: Volume 5, Chemistry and Chemical Technology, Part 11, Page 362, paragraph 3, Ferrous Metallurgy, n.d.)
(Science and Civilisation in China: Volume 5, Chemistry and Chemical Technology, Part 11, Page 362, paragraph 4, Ferrous Metallurgy, n.d.)
(Science and Civilisation in China: Volume 5, Chemistry and Chemical Technology, Part 11, Page 363, paragraph 4, Ferrous Metallurgy, n.d.)
(Science and Civilisation in China: Volume 5, Chemistry and Chemical Technology, Part 11, Page 363, paragraph 3, Ferrous Metallurgy, n.d.)