You can’t haul hundreds of passengers from one point to another without really strong rails. Wood, or even cast iron, aren’t going to hold up under that weight. Luckily, there was steel. The only drawback: steel was expensive.
Steel is an alloy of two metals. Usually it’s iron and carbon (coke). As you may imagine, iron and carbon need to get really hot before they become molten and mix together. The process was fuel-intensive—you needed a whole lot of coal to heat up the metal. But in 1855 Henry Bessemer figured out that if he pumped air through molten steel, the bits of carbon burned even hotter—so much hotter that the steel turned out harder using less fuel. The Bessemer process allowed steel to be mass-produced for way less money.
Because Pittsburgh, Pennsylvania is my second home-town (I lived in Sliberty for 20 years, jaggers), I must celebrate William Kelly who developed the same process as Bessemer at almost the same time (1847). A blast of air dramatically heats the molten pig iron because the impurities burn themselves up more quickly. What’s left is harder steel. The cast-off impurities are called slag.
Cheap, quality steel made Great Britain and the United States leaders in the Industrial Age.
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