Mark Miodownik demonstrates his mastery of the material sciences by explaining everyday substances with everyday jargon people can grasp even without a doctorate from Oxford or professorship at the University of London. After giving us a tour of the world of solids in his award-winning book Stuff Matters, Miodownik returns to explore a more mysterious, dynamic state of matter.

If you had a microscope powerful enough to zoom in to the molecular structure of kerosene, you would see a tangle of noodles: long chains of carbon atoms with hydrogen atoms branching off each carbon. Judging solely by appearance, kerosene is indistinguishable from water, but water won’t take you from 0-500 miles per hour in a matter of seconds, or from sea level to 30,000 feet in minutes, or from one side of the globe to another in a few hours. At a molecular level, kerosene resembles olive oil more than water. Olive oil is made of long, twisted chains that swirl and branch out, rather than a bowl of noodles. By contrast, water molecules are just a messy jumble of V-shaped compounds bumping into one another.

A Persian alchemist named Rhazes first discovered kerosene over a millennium ago. He probably wasn’t envisioning metal objects flying through the sky propelled by the substance he had just distilled, but he did notice kerosene’s flammability and that the flame burned without leaving any smoke or black residue. At that time, reliable indoor lighting was a struggle around the world, one which probably would not have been lost on him.

In the Middle East where Rhazes lived, people used olive-oil-fueled lamps (think Aladdin’s magic lamp). Olive oil doesn’t burn efficiently or cleanly because it’s relatively viscous as fuels go. But it was a staple in ninth-century Persia. Everyone used it for cooking and it was even the currency in which many people paid taxes to the empire.

For millennia, oil lamps were common in places where oil could be harvested, whereas candles proved the preferred method where animal fats and wax had to be relied on. For millennia people around the world were looking for better alternatives that burned brighter, left less residue, did not pose a huge fire hazard, and were cheap to produce. What the world was looking for without knowing it was kerosene, but the world slept on Rhazes’ discovery in the 800s. People continued using candles and vegetable oils and slaughtering whales for fuel (more than 250,000 in the 1800s alone). It wasn’t until the 1800s that Europe began experimenting with crude oil and distilling it down to the forms we’re familiar with today. Today, we burn up massive amounts of oils like kerosene—about four billion gallons everyday between flights, commutes, and its myriad other uses.

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Alcohol resembles kerosene at a molecular level. The viscosity is similar, and like kerosene, alcohol is flammable. This can make for a delightful flambéed dessert or a  bar engulfed in flames.

What most people don’t realize is that alcohol is toxic, even though words like “blood toxicity levels” and “intoxicated” are commonly invoked. Alcohol is a toxin that mutes our nervous system, blunts out cognitive faculties, and impairs our motor skills. But we consume it anyway and even enjoy the toxin’s effects. We smile more, and become far less inhibited.

Ethanol, the compound that makes alcohol alcohol, is a member of what chemists call the hydroxyl group. Water joins the ranks of the hydroxyl group due to structural similarities, and it is these structural similarities that allow ethanol to dissolve in water. So when you see alcohol percentages on a bottle of bourbon or wine, you are learning the percentage of ethanol that dissolved in the solution. So more ethanol dissolves in bourbon than beer, which is why the former is boozier.

Because ethanol molecules are minuscule, they slip past the stomach lining and are quickly absorbed into the bloodstream via the intestines. A fifth of the ethanol you consume is absorbed directly into your bloodstream via the stomach, which is why you feel the buzz almost instantly. And, of course, less food in the stomach means the ethanol gets past the stomach lining ever faster.

The toxin also inhibits hormone secretion that signals the kidneys to conserve water, which is why drinking extra water mitigates the toxin’s effects the next day.

Saliva is a source of embarrassment when you realize it’s been dribbling down your chin or that you’ve sprayed someone in the process of conveying your point. Body fluids have a way of triggering visceral disgust in us humans and we’ve built social and religious codes about keeping them contained. Even vicious criminals uphold this code of conduct for the most part.

When body fluids are outside our bodies, they disgust us. But they are absolutely essential for our survival and, in the case of saliva, our ability to enjoy food. Saliva allows us to taste food to determine whether it’s edible, nutritious, delicious, or poisonous and full of bacteria as it activates taste receptors on the tongue. The liquid is needed for taste. Saliva also keeps the mouth’s pH neutral—not too acidic or alkaline. When bacteria feast on residual sugar between your teeth, they make the environment more acidic, corroding your enamel and teeth. By flushing away bacteria, the saliva reduces the acidity and saves your teeth and gums. Saliva even contains calcium and other minerals that fortify your pearly whites.

Your salivary glands work hard for you and produce about one quart everyday. Some people, however, suffer from a condition called dry mouth, where the salivary glands don’t produce enough. For most people the idea of saliva donations and transfusions is pretty gross. The alternative is artificial saliva, a gel or spray that you can spritz your mouth with to deliver the nutrients and minerals that saliva naturally carries.

Tea is the world’s most popular drink. It’s twice as popular as coffee in the United Kingdom and that ratio gets even more lopsided in many other parts of the world. It’s hard to get a reliable figure, but some estimate 165 million cups of tea are consumed by Britons every day.

Tea options vary widely, but they all trace back to the same plant: Camellia sinensis. The variation in teas comes from the different processes involved in taking the leaves from bush to beverage.

Green teas are processed immediately after harvest, allowing them to keep their green chlorophyll color, rather than turning brown and black as other teas do. By contrast, black teas are made by allowing the leaves to wilt first, which sucks the chlorophyll out, through a process called oxidation.

When making a cup of tea, the water used impacts the flavor more than you might suspect. You don’t want all the minerals extracted from the water (distilled water), but you also don’t want too many minerals to overwhelm the tea’s flavors. For instance, some areas have tap water with high levels of calcium—often called “hard water.” The calcium ions will latch on to the organic molecules in the tea leaves, creating a scummy residue at the top of the glass and detracting from the tea-drinking experience.

The water’s temperature also makes a world of difference in the outcome of the brew. Too low a temperature will give you an unflavorful, under-extracted cup. Too high a temperature will extract more of the astringent tannins and polyphenols that make your face contort and dry out your mouth. Green teas are especially high in these, which is why it’s best to steep at lower temperatures. Caffeine adds its own bitterness to the mix, but if it’s a black tea, you don’t have to worry about the astringent tannins and polyphenols, as these get pulled out through the oxidation process (letting the leaves dry out).

It is easy to botch a cup of tea, but when the factors of tea quality, water quality, water temperature, and brew time come together well, it becomes more than fuel—it becomes an experience.

Terra firma (solid ground) is a misleading term. Our planet is far less solid than you might think—less solid and more liquid. Earth began as a molten sphere billions of years ago, and the outside has been gradually cooling, eventually becoming cool enough for life to emerge. There’s not only liquid on Earth’s surface in the form of oceans, but down towards the center, too. That molten ocean of liquid metal the planet began as remains. It’s a thousand miles thick and it envelops the Earth’s deepest core: a solid sphere of nickel and iron at 9,000 degrees Fahrenheit. Nine thousand degrees is well beyond the melting point for either metal, but the gravitational force throbbing toward the center of the planet changes that iron and nickel into solid metal crystals.

The outer crust with which we are familiar, the one on which forests, mountains, and buildings have grown up, is little more than Earth’s epidermis. The outer layer is comprised of thin tectonic plates only 20-60 miles thick, rock sheets floating around on a far thicker layer of viscous liquid metal called the mantel.

These plates “creep” along the surface of the mantel they rest on, and they often collide into each other. If you live in a place like San Francisco, you understand how fluid that mantel is. San Francisco sits on the fault line between frequently shifting Pacific and North American plates. Usually these shifts create small tremors, but occasionally they birth colossal rumbles that rend overpasses, bridges, and buildings and rack up scores or hundreds of deaths. In an especially violent quake in 1909, over 3,000 people died in San Francisco.  

Mountains are another result of these tectonic collisions. The Himalayas formed when the Indian subcontinent smashed into the Asian mainland. Like the Himalayas, the Rockies, the Alps, and the Andes are all located along fault lines. Mountains are also formed through volcanoes—and in a much more efficient and epic manner. On occasion, their eruptions are shattering enough to alter global weather patterns. In 1883, an active volcano on an Indonesian island erupted with force equal to 13,000 atomic bombs, decimating most of the island, and sending enough ash into the atmosphere to cover the globe, block the sun for years, and bring down the world’s temperatures.

You can count on solids. If you set a mug on the counter, it will stay there until you pick it up again. If you put an ice cube on the table though, it will melt into liquid water and spill into cracks where bacteria can colonize, or onto the floor where it just makes a mess. Liquids are unpredictable, especially if there’s no container to hold them. It’s the liquids in our lives that invite mold in the bathroom, that rot the timbers holding your home together, that put airport security on edge, and cause slips when people miss the caution signs. But it is also liquids that quench our thirst, that course through our veins, that keep us clean and hygienic. Liquid is a source of potential and pandemonium. Much more than solids or gasses, liquids tend to elicit our deepest disgust and delight. What armpit stains and specialty cocktails hold in common is their state of matter.

Even the same liquid in a different context or consistency yields wildly divergent reactions. You might dread a slobbery kiss from an aging relative, but from your lover? Saliva suddenly becomes more tolerable. We walk past hardened chunks of dog poo without any trepidation, but we are careful to give a wide berth when we see a moist, freshly deposited mound. And if you step in it? You can barely stifle the gag reflex. There is something about liquid that can make us uneasy and queasy in a way that other forms of matter simply don’t.

We can only guess what our future relationship with liquids will be like, if we will discover new compounds that revolutionize life as we know it or if the liquids in our life now will continue to be the most influential and consequential for our existence. In any case, our relationship with liquids will continue to be a vital but complicated one.

These insights are just an introduction. If you're ready to dive deeper, pick up a copy of Liquid Rules here. And since we get a commission on every sale, your purchase will help keep this newsletter free.