The Soda File

“Which boy can tell me about sodium?”

“Please, sir.” One of the little crawlers in the front row of the class shot his arm up, revealing a neatly-ironed white sleeve. “It’s salt, sir.”

“WRONG!” the teacher roared. He thumped his fist on the desk so hard that a pen jumped. Glaring at stupidity, he told us, “It’s a metal.”

‘Basher’ was the only teacher who terrified us in elementary chemistry classes. The hulk behind the desk was infinitely old with jowls like a Labrador retriever, a few wispy hairs greased back in a pretense of covering his bald pate, and a large fat nose squished like a slug to one side. He only smiled when our public exam results came through, and that gesture betrayed a row of crooked teeth like leaning gravestones.  Less courageous boys who avoided his class wondered how such a teacher could shepherd us to so many top grades. But it was no secret—it was FEAR.

We had nicknames for all our teachers, but ‘Basher’ was the most fitting. He had been a heavyweight boxer whom the headmaster hired out of retirement when there was a shortage of qualified chemistry teachers in our London Borough of Sidcup. Basher was a showman because he learned in ‘the ring.’

That day he used a pair of tongs to lift a silvery metal fragment out of a jar filled with oil. “What’s this Farrington?” The boy looked blank and scared.

“Is it sodium, sir?” That was the class smart alec. In those days, our teachers addressed us by our surnames, and they were always ‘Sir’ to us.

He held it in the flame of a Bunsen where it burned with a bright yellow flame. “That’s Na,” he informed us pointing a stubby finger at the large poster on the wall. Later, we heard it was called the Periodic Table. “Now boys, gather round in a circle.”

We trooped from our desks to watch him drop the flaming metal in a tank of water where it raced and fizzled on the surface until extinguished. Our curiosity grew in leaps and bounds when we learned the bubbles were explosive hydrogen gas.  Basher was playing magician and loved being on stage.

We were not the only schoolboys to enjoy this experiment. A generation earlier, the neurologist and author Oliver Sacks described the same on a London pond in his book, Uncle Tungsten: Memories of a Chemical Boyhood. He wrote: “It took fire instantly and sped around and around on the surface like a demented meteor, with a huge sheet of yellow flame above it.”

Sodium was not the only exciting ‘demonstration’ in chemistry that year. I look back in horror on the day he heated a beaker of benzene on an open bench; I can’t remember its purpose, but loved the sweet odor as it vaporized. Our teacher didn’t tolerate health and safety wimps getting in the way of life experience. The older staff in our boys’ school had grown up facing far greater dangers two decades earlier while serving in the War, and Basher was undoubtedly a commando.

The reason why gratitude to him conquered fear of him was his recipe for making NI3.NH3 from innocent-looking ingredients we could buy in a store. This contact explosive is completely safe while it stays moist, but when dried as a smear it goes off with a loud bang and puff of purple smoke at the slightest touch. It was the perfect revenge for the other class who sneered at us ‘Basherboys.’ Huddling outside all-ears, we waited for class break when they visited the school toilets…

Basher never gave us any practical demonstrations of salt because it was a boring substance. Sodium chloride is an extremely stable union of two highly-reactive ions. It did, however, interest the biology and geography teachers, and no doubt was an ingredient of cookery classes at the girls’ school in those days. Today, there is plenty of talk about common salt, but I hardly ever hear anything about sodium now.

As one of the commonest salts leaching out of the earth’s crust, it is carried down rivers to the oceans where it is concentrated over eons. If life originated in the oceans, seawater bathed the ‘bodies’ of the first creatures before body fluids, and later blood, provided a controlled internal environment. But as oceans became more briny, sea-life had to adapt: bodies become dehydrated when water is withdrawn osmotically from their less concentrated fluids. Our body is only a third as concentrated as seawater. Kidneys and gills in fish or salt glands in seabirds help to expel excess salt from drinking sea water, whereas shellfish and sharks solve the problem differently by conforming to the solute strength around them. Salmon and eels that migrate between the ocean and rivers have extraordinary ways of adapting to salt stress. Even marine fish cannot tolerate much higher concentrations of salt, which is a good preservative for ‘saltfish.’

How did mermaids manage to live in the sea if we can’t? Adrift in a raft, we can only survive for around 10-11 days without fresh water. The temptation for a thirsty survivor to drink seawater is huge, and watching albatrosses sipping it might drive him crazy, but it would hasten delirium and death. Our kidneys can’t produce urine concentrated enough to get rid of excess sodium, so our blood gets more and more briny. In the movie Unbroken, based on a book of the same name by Laura Hillenbrand, “Louie” Zamperini was afloat on a raft for 47 days in the Pacific Ocean. He drank rainwater.

Lot's wife in Book of Genesis
Lot of salt (200g)

A modest amount of sodium chloride in our diet, along with other minerals, is needed to replace natural losses because its ions are essential for cells to function.  We contain about 200g of sodium chloride, not exactly a “pillar of salt” which was what Lot’s wife was reduced to as punishment for turning to look back at Sodom.

Although we need perhaps as little as 0.5g of salt a day, or a quarter teaspoon, we almost always consume much more. The American Heart Association now advises a new lower limit of 2.3g or only 1.5g for people with hypertension, or who by reason of age or genetics are at risk of high blood pressure and stroke.

But how much salt do we eat and how can we control it? We can push the salt cellar away from our plate and buy unsalted peanuts from the grocery store, but how much are we consuming unwittingly in processed foods and restaurant meals? It is a problem like sugar – salt is tasty and hard to avoid. Basher told us that sodium chloride is unreactive, but as a biologist I take that with a grain of salt.

Next Post: Virginia Nature Journal for February