Salt was hugely important before refrigeration, and one of the ways of getting salt was from the sea or from brine springs. There were a few ways of doing this, which depended on the natural resources available in the area. You could put the saltwater into a large, flat pool and wait on dry air and the sun to do evaporation until there was no water left and you just had the salt, or you could boil saltwater using enormous quantities of fuel to get rid of the water.
But in places where big pools weren't feasible, they did everything in their power to reduce the amount of fuel required for the production of salt, because fuel takes a lot of time and effort to collect and drives up costs.
Enter the graduation tower!
The idea is that you take some source of salty water, pump it up to the top of a wooden tower filled with brushwood (typically blackthorn), then let it trickle down, which greatly increases evaporation by maximizing surface area and exposing the water to the wind along the way. When the saltwater reaches the bottom, it's saltier than it was, and you can send it through again until it's reached the point of saturation. If you do this with ocean water, you can reduce the amount of fuel needed by a factor of ten.
Plus it looks and sounds awesome - these were sometimes called thorn towers.
And at the start of the 20th century, when other forms of salt production had skyrocketed in efficiency, the graduation towers began to be used for healthcare, because as you might imagine, the air next to the graduation tower is very salty, more than it is next to the seaside. From what I can find it seems like the main thing it does is thin mucus, though there are a lot of other health claims.
There are still a few working thorn towers that you can go visit, mostly in Germany or Poland, but they're either historical curiosities keeping a tradition alive, or health and wellness centers, distilling down a brine spring for supposed special properties.
materialist-scumbag
reblogged from [op] — on graduation towers, salt, fuel, and the Bad-prefix town
Yes, all of this is correct and I want to add a thing, which is that the fuel side of the salt industry is genuinely the part of the story that breaks open if you push on it. Salt-making in pre-modern Europe was, for most of the medieval and early modern period, the single largest industrial consumer of firewood on the continent. The salt-makers ate forests. They ate forests at a rate that beat shipbuilding, beat iron smelting, beat glass furnaces, beat domestic heating in any one region you'd care to name. The salt pans of Lüneburg — which produced something like 40,000 tonnes of salt a year at peak in the 16th century — went through fuel at a pace that essentially deforested an enormous radius around the town and then kept going, importing wood from further and further out as the nearby supply collapsed.
The Bad Reichenhall saltworks in Bavaria, which are the oldest continuously operating inland salt works in Europe (first written mention 696 AD, when the Bavarian Duke Theodor II gave the bishop of Salzburg twenty brine pans), spent literal centuries chasing the forest line backwards into the Alps. By the early 19th century they had to commission a guy named Georg von Reichenbach to build a brine PIPELINE — like, a literal pumped pipeline (completed around 1816) going over Alpine elevation changes — to move the brine itself to where the wood still was, which is a kind of insane engineering project to undertake for what is, again, table salt.
(That's the kind of thing that drives the graduation-tower invention. Reichenbach's brine pipeline is from 1816. The graduation towers in Reichenhall are 16th century. The reason you build a graduation tower is exactly the same reason you eventually build a 20km brine pipeline: you've run out of nearby trees and the option of relocating the saltworks is off the table because the brine springs are where the brine springs are, geologically, and they're not moving.)
So when you say "fuel takes a lot of time and effort to collect, drives up costs," what's actually happening on the ground is that the salt industry is in a permanent slow-motion race against its own appetite. Every saltworks of any scale eats through the wood available within economic transport distance, and then it has to either (a) get more efficient, (b) reach further for wood, or (c) die. The graduation tower is option (a). The Reichenbach pipeline is a particularly insane version of (b). And there are SO MANY salt works that went with (c) — abandoned medieval salt towns are a thing, you can find them all over central Europe, places that had a brine spring and a thousand people and a church and then ran out of nearby wood and just… wound down.
A separate but related thing the OP isn't quite getting at: the demand side of pre-refrigeration salt economics is overwhelmingly about one particular preserved-fish trade, which is salted herring from the Baltic and the North Sea. The herring shoals would show up seasonally in massive numbers off Scania (now southern Sweden) and the Baltic coast, you'd haul them in by the millions, you'd salt them in barrels, and then you'd ship the barrels everywhere across northern Europe because they kept basically indefinitely and Catholic Europe needed protein on Fridays and during Lent and there were a LOT of Catholics and a LOT of Fridays.
This is why Lüneburg, an otherwise unremarkable town in Lower Saxony, becomes one of the wealthiest cities in medieval Germany. It sits on a colossal salt deposit. Lübeck, which is the actual port city, controls the trade route. Lüneburg salt goes to Lübeck. Lübeck ships it to Scania. The fishermen salt the herring. The herring goes back through Lübeck and out to Cologne and Bruges and Bergen and Novgorod and everywhere. The whole Hanseatic League is, to a pretty significant degree, a salt-and-fish cartel running on a single chemical transformation: chloride ion plus protein equals food that doesn't rot.
Lüneburg's salt works, the Saline Lüneburg, was the largest industrial operation in medieval Europe by some metrics. Over a thousand years of continuous operation, depending on which century of monastic-era boiling you want to start counting from. The town minted its own coins, kept its own army, negotiated as a peer with kings.
And the buildings in Lüneburg today lean.
They lean because the salt mine ran underneath the town for centuries and the ground gave out. Subsidence. The medieval city center is gorgeous and it is also visibly buckled — gabled facades that slump in the middle, towers that aren't quite vertical, doorways that aren't quite square. The whole town is sitting on a thousand years of hollowed-out salt and gradually settling into the cavity. Which, like, what a perfect physical record of where the wealth came from — the town that the salt built is collapsing into the hole the salt left behind.
The fuel problem is what kills Lüneburg, eventually. Well, the fuel problem and competition from French and Portuguese sea salt, which the Hanseatic League couldn't keep out forever, because solar-evaporated sea salt produced in places like Setúbal didn't need fuel AT ALL, which meant it could be made cheaper than anything you could boil in Lower Saxony no matter how much your graduation towers helped. By the 16th and 17th centuries the Atlantic sea salt is coming in by the shipload and the boiled-brine economies of northern Europe are in slow decline. Not gone — Lüneburg keeps boiling salt until 1980, which is its own incredible story — but no longer dominant.
(The 1980 closure date for Saline Lüneburg, by the way. Eight hundred and some years of continuous industrial salt production at one site, finally shut down inside the lifetimes of people still walking around there. We tend to think of medieval industries as having ended at some clean historical break point and they basically never did — most of them limped along for centuries in increasingly marginal forms until something specific finally killed them in living memory.)
OK so the OP's actual question, which is about the second life of graduation towers as healthcare facilities. This is also where it gets more interesting than "they noticed the air was nice."
The 19th century in Germany is the absolute peak of a particular institutional form, which is the spa town — the Kurbad or Bad — and the political-economic role of the spa town is to take a body of bourgeois and aristocratic visitors with non-specific health complaints (stomach troubles, "nerves," respiratory issues, gout, syphilis they can't talk about) and give them a structured environment with a doctor's supervision, a mineral water source, a set of physical activities, a defined social calendar, and — crucially — a duration of stay measured in WEEKS rather than days. Six weeks at the spa was the normal prescription. You'd go through a full season of treatment.
The German spa towns — and there are dozens of them, the "Bad" prefix means they're officially recognized as one — are basically nineteenth-century wellness corporations operating under royal patent. The Prussian state regulates which springs count, which doctors can practice there, what claims can be made, who can build a hotel, what the bathing schedules look like. It's a real industry. It supports its own architecture (the neoclassical Kurhaus, the colonnaded pump room), its own medical literature, its own social rituals (the daily walk, the brine inhalation, the regulated diet), and its own resort towns that are economically dependent on the annual influx of Berlin civil servants and their wives coming to take the cure.
So when a salt-works town like Bad Reichenhall or Bad Kissingen finds itself with obsolete industrial infrastructure in the 1850s-1890s — when modern salt mining and solar evaporation and rail freight have made the local salt-boiling business uneconomical — what they have on hand is (a) a town with the existing infrastructure for visitors, because saltworks workers needed places to live and eat, (b) a brine source still flowing, (c) a giant wooden structure that produces salty air, and (d) a state apparatus actively LOOKING for new spa towns to certify, because the Prussian and Bavarian and Saxon governments understood that spa tourism was a significant source of regional revenue and tax base.
The standard story you'll see about this is "they noticed the workers were healthier and started inviting visitors." What actually happened: the salt economy died, the town needed a new economy, the spa-town industrial pattern was the obvious one to pivot into, and the graduation tower was the asset that justified the pivot. Same with every Bad-prefix town in Germany. The brine spring became "healing waters." The wooden tower for industrial concentration became an "open-air inhalation chamber." The salt-boiling house became a thermal bath. The salt master's office became a doctor's consulting room. The entire former salt industry got rebadged as health infrastructure within about a generation, because there was a state-backed industry actively seeking exactly that kind of asset and the towns with the assets were happy to oblige.
(This is the same move you see at basically every other obsolete extractive site in 19th century Europe, by the way. The mines became "deep mineral spas." The iron springs became "ferruginous tonic waters." The coal towns with bad ventilation became respiratory wellness destinations. The waste heat from blast furnaces became "warm springs." The 19th century basically inherited the entire pre-industrial extractive infrastructure of central Europe and figured out how to monetize the byproducts as health goods. You can read this charitably as adaptive reuse or cynically as a kind of medical-tourism asset stripping. Both readings are correct.)
The Polish ones at Ciechocinek and Inowrocław are an interesting variant on this because Poland during the 19th century is partitioned and doesn't have a German-style coordinated state spa industry — Ciechocinek's spa development happens under Russian rule, starting in the 1830s, and the graduation tower there gets built on a much larger scale than the German ones precisely because it's being designed FROM THE START as a spa attraction rather than an industrial facility that pivoted. The Ciechocinek towers are like 1,700 meters long, which is on an order beyond any of the German ones, and they're built that way because the brine concentration is a secondary concern; the primary function is to produce a long impressive promenade-able salt-fog environment for the visiting bourgeoisie of Warsaw and Łódź to walk along on doctor's orders.
(Bad Salzuflen in Germany also has a 300m+ tower for similar reasons. The really big towers are post-industrial. The original 16th-17th century graduation towers were smaller and uglier, built as industrial equipment with no thought given to how they looked.)
The mucus thing is real, by the way. Inhaling fine-particle salt mist does thin respiratory mucus, which can provide genuine relief for people with chronic obstructive conditions, asthma, post-viral congestion, and so on. There's a study from the Paracelsus Private Medical University in Salzburg that worked with the Bad Reichenhall clinic showing measurable effects. So the wellness claims aren't ALL bullshit. But the historical structure of the claim is interesting because what got medicalized was a thing that happened to exist because of an entirely different economic process, and the medicalization was driven by the need to find a use for the existing infrastructure, and the population that benefited was very specifically the population that could afford a six-week stay at a Kurbad in the 1880s.
The contemporary version is mostly Polish and German pensioners and people on insurance-subsidized rehabilitation stays. The economic model is national health insurance plus aging-population wellness tourism. The structural pattern hasn't changed since 1880 — find a state-backed reimbursement scheme for non-specific health-adjacent activities, locate it in a town that needs revenue, build the patient flow around the legacy industrial infrastructure of a vanished extractive economy. The asset that was originally a 17th century answer to "how do we boil less wood" became a 19th century answer to "what do we tell the bourgeoisie they need" and then a 21st century answer to "how does a small Saxon town stay solvent."
Same as it ever was.
The thorn trees, incidentally, get replaced every 5-10 years as they get encrusted with mineral deposits — the calcium and magnesium and iron compounds that aren't sodium chloride precipitate onto the wood as the brine concentrates, and the encrustation eventually clogs the airflow and reduces evaporation efficiency. The replaced thorn bundles are full of a hard greyish-white mineral concretion the Germans call "Dornstein" or thornstone, which is one of those gorgeous accidental side products that nobody knew they were making until they were stuck with tons of it. The thornstone has some use as a soil amendment but mostly it just piles up around the saltworks as a kind of geological record of which minerals were in the brine and how dry the summers were when the bundles were last replaced.
If you ever go to Bad Kösen there's a thornstone exhibit. It looks like coral.
#salt #materialist scumbag #amhist #infrastructure #the bad prefix #white gold #hanseatic league #graduation towers #thornstone #lüneburg
