Age of Invention: The Dutch Salten Age

Part III of the Salt Series

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It’s difficult to appreciate salt’s historical significance because it’s now so abundant. Societies used to worry about salt supplies — for preparing and preserving food — as a matter of basic survival. Now we use the vast majority of it for making chemicals or chucking on our roads to keep them from getting icy, while many salt-making plants don’t even operate at full capacity. Yet the story of how we came to achieve salt superabundance is a long and complicated one.

In Part I of this series we looked at salt as a kind of general-purpose technology for the improvement of food, as well as a major revenue-raiser for empires — especially when salt-producing coastal areas could dominate salt-less places inland. In Part II we then looked at a couple of places that were all the more interesting for being both coastal and remarkably salt-less: the coast of Bengal and the Baltic Sea. One was to be exploited by the English East India Company, which needlessly propped up a Bengalese salt industry at great human cost. The other, however, was to prove a more contested prize — and ultimately the place that catalysed the emergence of salt superabundance.

It’s worth a brief recap of where we left the Baltic. Whereas the ocean is on average 3.5% salt, along the Baltic coast it’s at just 0.3% or lower, which would require about twelve times as much time and fuel to produce a given quantity of salt. Although there are a few salt springs near the coast, they were nowhere near large enough to supply the whole region. So from the thirteenth century the Baltic’s salt largely came from the inland salt springs at Lüneburg, supplied via the cities of Lübeck and Hamburg downstream. These two cities had a common interest against the kingdom of Denmark, which controlled the straits between the North and Baltic seas, and created a coalition of trading cities that came to be known as the Hanseatic League. The League resoundingly defeated the Danes in the 1360s and 1430s so that their trade in salt — and the fish they preserved with it — could remain free.

But Lüneburg salt — and by extension the League itself — was soon to face competition.

Lüneburg could simply not keep up with the growth of Baltic demand, as the region’s population became larger and wealthier. And so more and more salt had to come from farther afield, from the Bay of Biscay off France’s western coast, as well as from Setúbal in Portugal and from southern Spain.¹ This “bay salt” — originally referring to just the Bay of Bourgneuf, but then extended to the entire Bay of Biscay, and often to all Atlantic solar-evaporated salt — was made by the sun and the wind slowly evaporated the seawater from a series of shallow coastal pools, with the salt forming in coarse, large-grained pieces that were skimmed off the top. Bay salt, however, inevitably ended up mixed with some of the sand and dirt from the bottoms of the pools in which it was held, while the seawater was never filtered, meaning that the salt was often brown, green, grey or black depending on the skill of the person doing the skimming — only the most skilled could create a bay salt that was white. And it often still contained lots of other chemicals found in seawater, like magnesium chloride and sulphate, calcium carbonate and sulphate, potassium chloride and so on, known as bitterns.²

Bay or “black” salt, made with the heat of the sun, was thus of a lower quality than the white salt boiled and refined from inland salt springs or mined as rock. Its dirt discoloured and adulterated food. Its large grains meant it dissolved slowly and unevenly, slowing the rate at which it started to penetrate and preserve the meat and fish — an especially big problem in warmer climates where flesh spoiled quickly. And its bitterns gave it a bitter, gall taste, affecting the texture of the flesh too. Bay salt, thanks to the bitterns, would “draw forth oil and moisture, leading to dryness and hardness”, as well as consuming “the goodness or nutrimental part of the meat, as moisture, gravy, etc.”³ The resulting meat or fish was often left shrunken and tough, while bitterns also slowed the rate at which salt penetrated them too. Bay-salted meat or fish could often end up rotten inside.

But for all these downsides, bay salt required little labour and no fuel. Its main advantage was that it was extremely cheap — as little as half the price of white Lüneburg salt in the Baltic, despite having to be brought from so much farther away.⁴ Its taste and colour made it unsuitable for use in butter, cheese, or on the table, which was largely reserved for the more expensive white salts. But bay salt’s downsides in terms of preserving meat and fish could be partially offset by simply applying it in excessive quantities — every three barrels of herring, for example, required about a barrel of bay salt to be properly preserved.⁵

By 1400, Hanseatic merchants were importing bay salt to the Baltic in large and growing quantities, quickly outgrowing the traditional supplies. No other commodity was as necessary or popular: over 70% of the ships arriving to Reval (modern-day Tallinn in Estonia) in the late fifteenth century carried salt, most of it from France. But Hanseatic ships alone proved insufficient to meet the demand. The Danes, Swedes, and even the Hanseatic towns of the eastern Baltic, having so long been under the thumb of Lübeck’s monopoly over salt from Lüneburg, were increasingly happy to accept bay salt brought by ships from the Low Countries — modern-day Belgium and the Netherlands. Indeed, when these interloping Dutch ships were attacked by Lübeck in 1438, most of the rest of the Hanseatic League refused Lübeck’s call to arms. When even the Hanseatic-installed king of Denmark sided with the Dutch as well, Lübeck decided to back down and save face. The 1441 peace treaty allowed the Dutch into the Baltic on equal terms.⁶ Hanseatic hegemony in the Baltic was officially over.

The Dutch, by the 1440s, had thus gained a share of the carrying trade, exchanging Atlantic bay salt for the Baltic’s grain, timber, and various naval stores like hemp for rope and pitch for caulking. But this was just the beginning.

The Dutch Salten Age

Situated on the wet and windy coast of the North Sea, the Dutch had weather that was hardly conducive to making salt. What they did have, however, were plentiful peat fens near the coast, which were frequently flooded by the sea. By digging, drying, and then burning this salt-laden peat, the resulting salty ashes could then be added to water to create a strong brine. This could then be boiled in shallow pans over a peat fire to create a fine, white, high-quality salt. Dutch fen salt, unlike French bay salt, was exceptionally good at preserving fish — especially herring, the staple of both the Baltic and the North Sea.⁷ But digging peat near the sea-shore had to be highly restricted to prevent damage to the dikes that kept a low, flat country being flooded by the sea, while the process of digging, drying and refining was labour-intensive. Fen salt was costly and impossible to scale.

Although digging the salt-laden peat near the coast was risky, however, digging ordinary peat from further inland was not. The supply of this peat, for all intents and purposes, proved inexhaustible. When the surface peat of the lower-lying bogs of Holland and western Utrecht began to be exhausted in the 1530s, the Dutch developed dredging hoops to cut peat from below the water level and haul it up, turning the bogs into lakes that could be drained to create new agricultural land, as well as building canals to the higher-lying bogs of the more northerly regions like Friesland and Groningen. Indeed, from the 1650s the supply of peat still far outstripped the demand for it, which continued well into the eighteenth century. Peat was so cheap and plentiful that many of the drainage and canal-digging projects to get more of it were cancelled, only to be looked into again over a century later.⁸

So with plentiful peat, and having inserted themselves into the Baltic trade, the Dutch from around the 1450s were able to transform some of the French bay salt they were carrying into a much better product. By dissolving the bay salt in some water and then boiling it over a peat fire, they could remove much of the dirt and treat it — usually by adding egg whites or a bit of ox blood — to remove the bitterns as well. The resulting refined salt, called “salt upon salt”, was pure and white, while plentiful peat meant that it produced cheaply and huge quantities, undercutting the price of white Lüneburg salt, allowing Dutch merchants to expand their share of the Baltic trade.⁹ Having in 1441 gained a mere foothold in the trade, by 1500 about 50% of all ships entering the Baltic were Dutch.¹⁰

The Baltic trade was especially carried out by the poor inhabitants of the coastal, northern Dutch provinces of Zeeland, Friesland and Holland. They exchanged salt in the Baltic for vast quantities of rye — grain that they brought to feed the extraordinary urbanisation of nearby Flanders and Brabant, the southern parts of the Low Countries, where cities like Ghent, Bruges and Antwerp became northern Europe’s most important centres of industry and commerce. Baltic grain was also in high demand in France, Spain, Portugal, and eventually even Italy. But this demand for grain soon far exceeded the Baltic’s demand for salt. By the 1550s, although a third of Dutch ships entering the Baltic brought salt, the remaining two thirds brought nothing at all, achieving their needed sailing weight by filling their holds with worthless ballast. The vast majority of Dutch traders had to pay for Baltic grain with cold, hard, silver cash.¹¹

The huge profits from grain-carrying alone made the trip worthwhile: replacing the ballast with what salt could find a market was thus essentially costless. And as the fishermen of Holland, Friesland and Zeeland were relatively poor, the carrying trade proved a decent earner during the fishing off-seasons, when they would have struggled to find employment. Given the lack of other options, the Dutch could transport goods at a lower cost than that of the Hanseatic ships because the sailors could be paid much lower wages — a cost advantage that was later solidified by developing ways to employ fewer sailors per ship.¹² The relatively warm climate of the Low Countries also meant that they could set out to France while most Hanseatic ports were still ice-bound, getting salt to the Baltic and returning home with grain again all in one season before the ice set back in.¹³ These factors all helped the Dutch to maintain their share of the trade against Hanseatic competition.

But to be able to pay for more than a fraction of Baltic grain, the Dutch needed a way to earn silver from elsewhere. The northern Dutch provinces like Holland, Zeeland and Friesland were to grow well and truly rich not from the mere carrying of grain and salt, but because of what they was able to do with them, creating higher-value exports that earned the silver to buy still more.

The Dutch very quickly carried far more grain than they needed merely to feed themselves, so it soon became abundant and cheap in their own lands. Their farms were able to safely shift to growing higher-value crops, including various dyestuffs for cloths, and especially fodder and pasture for cows. Huge herds walked 350 kilometres or so each year from Holstein, in southern Denmark (now in Germany), to grow fat on the pastures of Friesland.¹⁴ And with plenty of cows and refined white salt, the Dutch diet soon involved plenty of butter and cheese.¹⁵ Foreigners in 1600 referred to the northern Dutch as “butter-mouths” with one English visitor remarking that “butter is the first and last dish at the table, whereof they make all sauces”, adding that Dutch traders travelling between towns “carry with them cheese, and boxes of butter for their food, whereupon in like sort strangers [foreigners] call them ‘butter boxes’, and nothing is more ordinary than for citizens of good account and wealth to sit at their doors … holding in their hands and eating a great lump of bread and butter with a luncheon of cheese.”¹⁶ Salted butter and cheese became important Dutch exports to the south and west too, helping to pay for bay salt and earning some of the silver needed for more Baltic grain.

But above all, the northern Dutch were to build their wealth by adding their salt to fish.

As I mentioned last time, Lübeck’s and Hamburg’s access to salt supplies had given them unique advantages in the herring fishing industries of the North Sea and Baltic. Dutch salt-upon-salt, however, was just about as good as any other refined white salt for preserving fish, while also being much cheaper and more easily scaled. France, Spain and Portugal, with plenty of coast and infinite sunshine, could easily expand the production of bay salt to serve as the basic feedstock, while Dutch peat to fuel its refining was, as we’ve seen, for all intents and purposes inexhaustible. By contrast the traditional sources of the Baltic’s white salt, like the Lüneburg salt springs, were constrained by the supply of wood fuel for boiling the brine. To expand in the same way would have required the creation and maintenance of many more forests up-river into Germany, on land that was already spoken for, and thus expensive to convert. There was simply no contest: thanks to their uniquely expandable supply of white salt, the northern Dutch could catch and preserve far more herring to a high quality.

Which is exactly what they then did. Over the course of the fifteenth century the Dutch were able to expand their herring catch in a way that left other nations in awe.

Traditionally, small fishing boats, each with about six to ten men, would go out into coastal waters, catching as many as they could and then rushing back to shore. A little might be eaten that same day, fresh. Some more might be lightly salted, to make it last a couple of days longer. But for anything more, the herring had to be gutted and drained of its blood to remove the parts most likely to spoil, then packed into barrels of almost a thousand fish apiece among hefty layers of salt. The faster the gutting and packing could be begun and done — a skilled gutter could handle up to 2,000 herring per hour — the fresher and longer-lasting the fish, and the further it could be sent.¹⁷ In the North Sea, the major traditional fishing waters were off Norway and the coast of England. In the Baltic, they were off Scania, the southern tip of Sweden — waters so heaving with herring in August to November most years that the boats reputedly had trouble using their rudders, and were “scarce able with wind and oar to break through them”.¹⁸

But by the 1410s, the fishermen of Holland and Zeeland were, quite literally, taking things further. They ranged far to the north, beyond Scotland to the Shetlands and Orkneys, as well as farther out into the North Sea, where the herring could be found at a much earlier stage in their lifecycle and some 30-50% larger. Here they would put out a huge dragnet, the vleet, combining over forty smaller nets to form a weighted curtain 1.4 kilometres long, hanging from floats to a depth of 19 metres — about the length of a bowling lane.¹⁹ And to achieve all this, the Dutch were sending larger ships (built from salt-bought Baltic and Norwegian timber and naval stores), which carried the salt, barrels, and workers to immediately do all the gutting and packing of the herring while they were still out at sea. These floating factories, the herring busses, served by a fleet of smaller boats shuttling supplies from the coast, freed the Dutch from having to stay close to shore. The development of the herring buss allowed the Dutch to fish on the high seas, going wherever and whenever was best.²⁰

By the 1460s, Dutch-caught North Sea herring had displaced Baltic herring — cured in Scania and carried by the Hanse — from the markets of the Low Countries, including the wealthier southern parts like Brabant and Flanders. And by 1500, the flow of herring into the North Sea was reversed, with the Dutch bringing about half of the herring sold each year in the main Baltic grain hub of Gdansk.²¹ Dutch-caught herring was soon being exported up the river Rhine into western Germany as far as Switzerland, as well as to England. And it especially went to France, Portugal, and Spain. Having bought grain, timber, and naval stores in the Baltic, and bay salt in France and Iberia, the northern Dutch now sold back salted butter, cheese, and especially herrings to all. These higher-value exports were the main way to the silver needed for the Baltic trade, especially from Antwerp — the main exit point into northern Europe for the silver mined in southern Germany. Holland’s port of Amsterdam was to become Europe’s greatest hub for all sort of provisions and raw materials despite the Dutch growing almost none of it themselves.

The Dutch recognised the importance of this “mother trade” in salt, grain and herring, as did their envious neighbours. For the English, Dutch brazenness in fishing right off England’s coast and then selling their own herring back to them was a sore bone of contention and a depressing reminder of wasted opportunity. Already noticed in the 1550s,²² it was still being complained of in the 1700s.²³ As one English mariner lamented in the 1610s, “O slothfull England and careless countrymen, look but on these fellows that we call the plump Hollanders, behold their diligence in fishing, and our own careless negligence.” Despite repeated attempts to compete with it, for over a century the Dutch herring fishery proved unassailable. And it’s telling that the Dutch banned the export of their fishing tackle, drag-nets, and refined white salt. But the greatest and more immediate threat of all came not from their competitors, but from Spain.

Since 1433, almost the whole of the Low Countries had been united under the rule of the duke of Burgundy, who from the 1510s was also the Habsburg archduke of Austria, king of Naples and Sicily, Holy Roman Emperor, and king of Spain, including its vast possessions in the New World. The seventeen provinces of the Low Countries were thus part — indeed, the centre — of the vast Catholic Habsburg empire. The unifying emperor Charles V was born in Ghent, in wealthy Flanders, and both he and his successor to the Spanish empire, Philip II, based their court at Brussels, in nearby Brabant. In the early sixteenth century then, northern Dutch herring busses thrived under the protection of this mighty empire.

Yet when Philip decided to decamp to Spain in 1559, and to crack down on his increasingly Protestant subjects in the Low Countries, in 1566 they rose up in revolt. A vast Spanish army arrived the following year, and at first seemed to have pacified the region. But in the 1570s the rebels began to claw back control. In 1581, although Philip had in the meantime also added the entirety of the Portuguese empire to his domain, the remaining unconquered Dutch provinces formally declared their independence as a united entity, and in 1588 decided to become a republic. The tiny northern Dutch provinces of Holland, Zeeland, Friesland, and four others thus formed the Republic of the Seven United Netherlands — the famous Dutch Republic — having against all the odds fought the greatest empire on earth to a stalemate.

Faced with a hostile Spain and Portugal, the merchants of the Dutch Republic were often forced to find new markets. In the 1590s, for example, they ventured into the Arctic, selling salt and herring to Russia via the port of Arkhangelsk. And they especially needed to find new sources of solar salt. French bay salt alone often proved insufficient, and so they ventured down to the coast of Africa to the salt pans of the Cape Verde islands, as well as across the Atlantic to the Americas. There, for many years, they exploited the salt lagoon of Punta de Araya on the Venezuelan coast. The Spanish blocked access to it in 1622 by building a large fort, and so the Dutch went looking for new sources in the Caribbean, at Tortuga and Saint Martin, until the Spanish drove them away from both in 1633.²⁴

Yet despite this game of New World whack-a-mole, the Dutch still just about managed to keep their commerce afloat. It was widely acknowledged that whereas the Spanish empire drew vast quantities of gold and silver from the New World, the Dutch seemed to have as great a “gold mine” of their own in the humble salted herrings of the North Sea.²⁵

Peat had given the Dutch a special advantage in the refining of imported bay salt, allowing them to create higher-value exports with which to drive their trade. And it was seeking to prop up these imports that propelled them into new and unfamiliar seas. The “mother trade” formed a solid foundation for the Dutch to rapidly move into still more trades. But in the late seventeenth century, just as the Dutch Republic was coming to the height of its extraordinary commerce, a new competitor emerged to undermine its foundations. Peat, albeit plentiful, was about to contend with coal. More on that next time.

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1. Philippe Dollinger, The German Hansa, trans. D. S. Ault and S. H. Steinberg, The Emergence of International Business, 1200-1800 (Macmillan and Co Ltd, 1970), pp.219-220, 253-4

2. L. Gittins, ‘Salt, Salt Making, and the Rise of Cheshire’, Transactions of the Newcomen Society 75, no. 1 (January 2005), pp.139–59; L. G. M. Bass-Becking, ‘Historical Notes on Salt and Salt-Manufacture’, The Scientific Monthly 32, no. 5 (1931), pp.434–46; A. R. Bridbury, England and the Salt Trade in the Later Middle Ages (Clarendon Press, 1955), pp.46-52. Incidentally, some historians, like Jonathan I. Israel, Dutch Primacy in World Trade, 1585-1740 (Clarendon Press, 1989) p.223, note occasional reports of French bay salt having been worse than the Portuguese or Spanish due to its high magnesium content, “which imparted an unattractive, blackish colour”. This must be based on a misunderstanding, however, as the salts would have been identical other than in terms of the amount of dirt taken up with the salt from the pans. At certain points in the seventeenth century the French workers skimming the salt must simply have been relatively careless compared to those of Iberia.

3. John Collins, Salt and fishery a discourse thereof (1682), pp.17, 54-5, 66-8

4. Bridbury, pp.94-7 for estimates

5. Karl-Gustaf Hildebrand, ‘Salt and Cloth in Swedish Economic History’, Scandinavian Economic History Review 2, no. 2 (1 July 1954), pp.81, 86, 91

6. For this section see: Dollinger, pp.194-5, 201, 236, 254, 300

7. Bridbury, pp.10-13

8. Jan de Vries and Ad van der Woude, The First Modern Economy: Success, Failure, and Perseverance of the Dutch Economy, 1500-1815 (Cambridge University Press, 1997), pp.38-9

9. Bridbury, pp.99-100

10. de Vries and van der Woude, p.353

11. Israel, p.22, p.49

12. de Vries and van der Woude, pp.356-357

13. Israel, p.20

14. Fynes Moryson, An itinerary … containing his ten yeeres travell (1617), p.95

15. de Vries and van der Woude, pp.204-5, 207

16. Moryson, p.97

17. Richard W. Unger, ‘Dutch Herring, Technology, and International Trade in the Seventeenth Century’, The Journal of Economic History 40, no. 2 (1980), p.257

18. Lewes Roberts, The merchants mappe of commerce (1638), part II, p.151

19. Bo Poulsen, Dutch Herring: An Environmental History, c.1600-1860 (Aksant, 2008), p.138

20. Richard W. Unger, ‘The Netherlands Herring Fishery in the Late Middle Ages: The False Legend of Willem Beukels of Biervliet’, Viator 9 (1978), pp.335–56 for a summary.

21. Unger (1980), p.263

22. John Dee, General and rare memorials pertayning to the perfect arte of nauigation annexed to the paradoxal cumpas, in playne: now first published: 24. yeres, after the first inuention thereof (1577), pp.23-4

23. James Puckle, England’s Path to Wealth and Honour, in a Dialogue between an English-man and a Dutch-man (1708)

24. Israel, p.63

25. Puckle, p.4