Salt

After reading Paper, I decided to tackle Salt by Mark Kurlansky. Like Paper, Salt is chock full of interesting information with both breadth and depth. Appropriately, the first chapter begins in China, “A Mandate of Salt”. I learned that the earliest written record of salt production dates back to 800 B.C., but the records discuss the production and trade of salt during the Xia dynasty going back a further thousand years. I also learned the history of fermenting fish and soybeans to make what is now the ubiquitous soy sauce (although fish is no longer used in the recipe). Fermentation – it’s all chemistry! And those tasty black gelatinous century eggs? They are soaked in brine and sometimes encased in salted mud and straw

A hero in the Chinese story was the governor of what is now Sichuan province, an engineer named Li Bing. The province had long produced salt, but Li Bing figured out that the brine came from underground, and had the first brine wells drilled (in 252 B.C.) As the Chinese became more skilled at the task, the drill shafts went deeper. (Now I’ll quote two great paragraphs from Kurlansky…)

“But sometimes the people who dug the wells would inexplicably become weak, get sick, lie down and die. Occasionally, a tremendous explosion would kill an entire crew of flames spit out from the bore holes. Gradually, the salt workers and their communities realized that an evil spirit from some underworld was rising up through the holes they were digging… Once a year the governors of the respective provinces would visit these wells and make offerings.”

“By A.D. 100, the well workers, understanding that the disturbances were caused by an invisible substance, found the holes where it came out of the ground, lit them, and stated placing pots close by. They could cook with it. Soon they learned to insulate bamboo tubes with mud and brine and pipe the invisible force to boiling houses. These boiling houses were open sheds where pots of brine cooked until the water evaporated and left salt crystals.”

The passage reminded me about the kobolds of the Saxon miners, but what is particularly neat is that the workers behaved like amateur scientists and engineers. Yes, there may be evil spirits to placate, but one can make use whatever fumes may be coming from the beasts below. They essentially invented the first natural gas piping system, all in the service of salt production! Not only that, the use of bamboo piping spread to irrigation and plumbing systems. The Chinese also discovered gunpowder from mixing salt with other ingredients. And their salt taxes imposed by the government go way back, more than four millennia. The Chinese pictograph character for salt apparently “depicted the state’s control of its manufacture.” The image below is from salt.umd.edu and traces the evolution of the character.

 

As Kurlansky writes: “A substance needed by all humans for good health, even survival, would make a good tax generator. Everyone had to buy it, and so everyone would support the state through salt taxes.” The highs and lows of salt taxes are a prominent part of the book. Kurlansky trots the globe with how governments used and abused salt taxes from the pharaohs of ancient Egypt to Gandhi’s famous march in 1930 defying colonial Britain’s salt laws. He traces the important role of salt in the American Civil War, the American Revolution, and the Spanish wars with the Aztecs and the Incas. Whoever controls the salt, has the power.

History and chemistry is discussed in Chapter 18, “The Odium of Sodium”, titled after a ditty written by a British novelist.

Sir Humphry Davy

Abominated gravy.

He lived in odium

Of having discovered sodium.

In 1807, Davy isolated sodium via electrolysis. In 1810, he isolated chlorine. The former is a soft grey metal that reacts violently with water; the latter a greenish yellow gas that would gain infamy in gaseous trench warfare of the first world war. But when combined, they make sodium chloride, a white crystalline powdery substance, and the most common ingredient in what we now call table salt. The chemist thinks of salts as ionic compounds consisting of an electron donor (the metal) and an electron acceptor (the non-metal). The combinations of different metals and non-metals produces different salts with different properties. Saltpeter, a constituent of gunpowder, is potassium nitrate. Epsom salt is magnesium sulfate. Chalk is calcium carbonate. The combinations are myriad. We owe it to Davy and the many scientists who teased out the chemical theory of salts for our plethora of choices today. (Picture below from an interesting RedOrbit article about scientists studying the compression of table salt.)

Through much of history, the whiteness of salt and having uniform crystals, was highly prized. Dirtier and coarser salts were viewed as “less pure” and less valuable; perhaps related to the rise of industrial mechanization. But the tables have turned. Artisanal salt, irregular in its composition, not dazzling white because of the presence of impurities, has now become the darling of gourmet chefs and their many followers. Dirty salt, it had been called through the ages, and now it commands the higher prices.

What is our new salt today? The substance that everyone needs and can be taxed appropriately by the governments, or perhaps, the corporations of the world. The quest for the Killer App, the holy grail of the twenty-first century, is perhaps simply a short-term substitute for the position long held by salt.