Construction time again
One of the many advances the new techniques with iron and steel allowed was the construction of different types of bridges and buildings.
Related programme
Mike Fitzpatrick explains how first cast iron and then steel were developed, and the vital part these discoveries played in the industrial revolution.
The Industrial Revolution and the Development of Steel
The Industrial Revolution was characterized by enormous growth in many areas of industry: mining, transport, and construction to name but a few. This growth set up a demand for more raw materials, and in many cases, for new materials with better properties that did not yet exist. As these new materials were developed, by design or by chance, new applications sprang up to make use of them, creating further demands and so on. One of the features of the Industrial Revolution is the plethora of new materials that became available, and the upsurge in manufacturing methods that made use of them. Metals, fibres and even the early precursors of modern plastics were available in unprecedented variety and quantity.
In the 1700s iron was by no means a new material, it had, after all, been around since the Iron Age nearly 3000 years earlier. However, production of iron was restricted to small-scale smelting of iron ores, and the amount that could be produced was limited. Iron was produced by smelting it with charcoal (wood that has been heated in the absence of air to burn off the impurities in the wood and leave it enriched in carbon: this partial burning produces an excellent fuel which is much more effective than wood itself). Britain had depleted huge areas of forest for fuel since the 1500s, and timber supplies for charcoal were not going to be a sustainable long-term solution. Legislation was in place to ban the harvesting of trees for charcoal production.
Charcoal is more than just a heat source for producing iron from its ores. The key step in smelting iron ore to make raw metal is providing a reducing agent as well as heat: a reducing agent is a chemical that reacts with the iron oxides in the ore to release the iron in metallic form. The simplicity of charcoal is that it acts as both the heat source and the reducing agent.
What was needed was a method by which iron could be smelted in serious tonnage quantities. This was going to need a better heat source than charcoal. Woods in Britain were becoming scarce with demands on them for both building timber and charcoal. Coal looked like it might be such a fuel. There was a problem, though: coal tends to have a high concentration of sulphur, which along with other impurities makes iron brittle. So iron produced by smelting with coal was of very poor quality.
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Content last updated: 17/08/2005
