Monthly Archives: August 2010

Lime is not only the fruit…

Lime Kiln, Aberystwyth

Anyone who has been down to the harbour in Aberystwyth will have spotted the lime kiln that stands out as one of the oldest – and oddest looking – things you can see in the immediate area. As a child I always thought it looked like a giant sandcastle, which seemed to provide a satisfying enough raison d’être for this oddity, given that Aberystwyth is known for its beach and a castle as well. Even the cracks in the brickwork resemble the worrying structural faults that sandcastles tend to develop as a result of overzealous reshaping or gravity-defying planning.

To continue my recent(ish) attempts to look more carefully at things I photograph, not just through the viewfinder, I decided it was time to find out a bit more about this landmark…

In fact it is the last survivor of a number of such kilns in the Trefechan area around the harbour, dating back to the eighteenth century. In those days Aberystwyth was a busy sea port, something that is hard to appreciate today given that the harbour is home to just a few small fishing boats, modest sailing yachts and the like. Back then, limestone was shipped in from places further down the coast, together with culm (a mixture of coal dust and clay), the fuel needed to convert it into (quick)lime.

Burning limestone (calcium carbonate, CaCO3) at temperatures of 800-900°C causes it to break down into carbon dioxide (CO2) and calcium oxide (CaO) in a process that was said to result in blue flames and lots of thick yellow smoke coming out of the kiln. Calcium oxide is a very reactive compound traditionally known as quicklime because of its lively behaviour on contact with water. Adding water produces so-called slaked lime (calcium hydroxide, Ca(OH)2).

Are you still with me? Nowadays I suspect most of us could come up with a good few ideas for how you might use lime of the green, citrus variety (mmmm, caipirinha!), but this other sort of lime has most likely slipped into obscurity for us “younger” generations and/or anyone not interested in the chemical side of it. However, this stuff was hugely important in the heyday of these kilns, and had been for a long, long time before that.

The Romans used lime in mortar and concrete, and for centuries it was also used for making whitewash, a kind of paint that was popular not just because it was cheap and gave a fresh, clean look to the walls of houses but also for its added durability and anti-bacterial properties. In this part of Wales lime was used rather more extensively in agriculture – farmers purchased calcium oxide to slake and spread on their fields to neutralize the acidity of the soil, improve drainage and provide access to nutrients for their crops, the beneficial properties of lime having been noted as early as the sixteenth century. Without this fertilizer arable farming would have been well-nigh impossible, and concentrating on sheep or dairy farming was simply not an option for the subsistence farmers of pre-modern times.

The decline of the lime burning industry in West Wales in the nineteenth century can be mainly attibuted to two factors. Firstly, agriculture had changed almost beyond recognition even within the space of a century, and fertilizers had moved on, too. Those farmers who were still growing cereal crops in this area could choose between potent, if pricy, imported guano (anyone who has experienced the seagull problem in Aberystwyth might wonder why it needed to be imported…*), more readily available and economically produced bone meal, or superphosphate of the sort manufactured in England since 1842.

Secondly, the coming of the railways might have turned Aberystwyth into a tourist resort, but in industrial terms the area became marginalized as the local shipping trade was gradually wound down and inland, more central areas were more economically integrated into the industrial transport network. Even today, when you travel by train to Aberystwyth you can feel as if you are travelling to the end of the world…

* I do know why, but I don’t want to expose myself as a faeces nerd ;)

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