English glass owed its crystal clarity to Hungarian potash. And to get that potash, we burned down roughly a fifth of present-day Hungary. 🔥 In the Bükk hills of northern Hungary there is a valley called Szalajka: a string of trout ponds, pine forests, springs, a waterfall, a little forest railway, and barely a building in sight. You eat grilled trout there and think you couldn't find a more untouched place in the whole country if you tried. Then you walk up the valley and read the information boards. They tell you that in the 1800s the village of Szalajka, right there in the valley, had more inhabitants than nearby Miskolc. So where is it? There are three buildings in the entire valley. Gone. Torn down, carted off, leaving nothing but its name. And the village got that name from the stuff it produced: sal alkali, which the locals couldn't quite pronounce. It became "szalakáli", then Szalajka. Sal alkali is potash, potassium carbonate, and you get it from wood ash. So two hundred years ago this lovely valley sat among smoking kilns, stripped hillsides and mountains of ash. It wasn't a beauty spot. It was a chemical plant. And not just here. In the mid-18th century the price of potash shot up in England and France, because the glass, soap and textile industries couldn't get enough of it. So it shot up here too, and anything made of wood started to burn. In 1756, in just 11 villages of the Bakony hills, 44 kilns were devouring the forest. The law, in theory, only allowed burning trees that had already fallen. But a tree falls over remarkably easily once someone tickles it with an axe. 😏 The village of Szentgál banned ash-burning outright in 1791, fed up with the abuse and the destruction. By 1764 close to two hundred kilns were producing ash and potash, and the peak was still a long way off. Most Hungarian potash went to England, where people believed English glass owed its crystal clarity to it. By the early 19th century, the wood ash for all that potash had cost four million cadastral acres of forest, roughly a fifth of today's Hungary. Later this was politely described as the forests becoming "exhausted". They were cut down and burned. WE BURNED A FIFTH OF THE COUNTRY FOR A WHITE POWDER! When the wood ran out at home, potash-making moved on to Transylvania: the forests of Avas, Szilágyság and Bihar, later the mountains around Brașov and Sibiu. My wife and I go mushroom hunting there every summer, and once a biology professor told me that the huge pine forests we walk through aren't native at all. They were planted. Beech and oak should be standing there. Back then I had no idea who planted all those pines, or why. Two years later I ran into the potash craze, and it clicked: the original forest had been burned down to the last tree in the 18th century and replanted with faster-growing pine. The madness was finally stopped by a French chemist, Nicolas Leblanc, who started making natron from common salt. Natron is potash's sodium relative (sodium instead of potassium), and it makes glass just as well. Overnight, nobody needed wood ash anymore. By then, though, the same fire had swept through most of Europe and North America. And here's the twist. 💡 Egypt never needed any of this, thousands of years earlier, because on the shores of the salt lakes of Wadi el-Natrun, natron simply bloomed out of the ground. You just had to sweep it up. What we burned forests for, its close alkaline relative was lying around there for free, probably until it was mined out to the last gram. It's gone there too now. Now dissolve that natron in wood-ash lye and add burnt lime, and you get an alkaline mix that eats into stone at just 168 °C, about what a kitchen oven can do. I don't think it's a coincidence that the biggest stone monuments rose exactly where natron once lay around for free. The official explanation is different, of course: copper chisels, dolerite balls and a few thousand enthusiastic workers. A people with one of the best stone-etching chemicals in the world lying at their feet, and they chose to keep hammering. They must have really loved the workout. 😏 So next time you're sitting over grilled trout at a waterfall in a Hungarian valley, remember: you're having lunch in the ruins of a chemical plant. Do you know any other place name that comes from potash or ash-burning? Tell me in the comments, because I'm sure Szalajka isn't the only one. If you want the full story, my book is on Amazon: amazon.com/dp/B0DG3JT2N5 @SciHistoryOrg @ceramicreview @MuseumofGlass @XoloElvis @mazzenilsson