iSi North America Soda Siphon Classic Mesh Sodamaker

Take a sip of any cold, sparkling beverage. Before the flavor, before the refreshment, there is that other sensation. A sharp, electric, and strangely pleasant tingle that dances across your tongue. It’s a feeling so familiar we rarely stop to question it. We assume it’s the simple physics of tiny bubbles popping against our taste buds.

But what if I told you it’s not? What if that iconic fizz is less about bursting bubbles and more about a sophisticated chemical trick playing out inside your mouth, a signal interpreted by the same nerve pathways that detect the sting of mustard and the cool of mint?

The story of that tingle is the story of a chance discovery in a brewery, a 200-year-old law of physics, and a marvel of modern materials science you might have sitting on your kitchen counter. It’s a journey that reveals how even the simplest pleasure is a symphony of science.

Our story begins not in a laboratory, but in a foul-smelling English brewery in 1767. The English polymath Joseph Priestley, living next door, grew fascinated by the vats of fermenting grain. He noticed a strange, heavy gas shimmering above the bubbling mixture—a gas that could extinguish flames and was unbreathable. This was what he called “fixed air,” what we now know as carbon dioxide ($CO_2$).

Driven by pure curiosity, Priestley devised a way to force this gas into water. By suspending a bowl of water over the vat and stirring it, he created the world’s first glass of artificially carbonated water. It had a “peculiar satisfaction,” a pleasant, acidic tang he had only ever encountered in naturally sparkling spring waters. He hadn’t just made a new drink; he had captured a ghost in a bottle. This discovery was initially celebrated not for its refreshment, but for its perceived medicinal properties, hailed as a cure for ailments like scurvy. The quest to bottle these bubbles had begun.

To understand the challenge faced by Priestley’s successors, you have to understand the fundamental rule governing his discovery. It would take another few decades for his countryman, William Henry, to formally codify it, but the principle is simple: to get a gas to dissolve in a liquid, you need to apply pressure. Henry’s Law dictates that the amount of gas a liquid can absorb is directly proportional to the pressure of that gas exerted upon it.

This is where an object like the modern iSi Soda Siphon transforms from a piece of kitchenware into a beautiful, handheld physics demonstrator. The process is Henry’s Law in action. When you insert a small steel charger, you are releasing highly pressurized $CO_2$ gas into the sealed chamber. This immense pressure forces the gas molecules, against their natural tendency to fly apart, to dissolve and hide among the water molecules.

But there’s a crucial second act to this law: temperature. Gases are far more soluble in cold liquids. The molecules in cold water move more sluggishly, leaving more room for the gas to settle in. This is why the instructions, and the wisdom of experienced users, are unequivocal: you must use very cold water. Shaking the siphon, as users are instructed, accelerates the process by increasing the surface area between the gas and the water, allowing equilibrium to be reached faster. The entire ritual—the chill, the charge, the shake—is a precise choreography designed to maximize the amount of caged fizz.

Of course, caging that fizz is only half the battle. You have to keep it caged. Early soda siphons, stunning artifacts of glass and pewter, faced a dangerous problem: they were, in essence, glass bombs. Glass is incredibly strong under compression but notoriously weak under tension. A microscopic scratch on its surface can, under the constant outward force of the pressurized gas, become a catastrophic failure point. This is why vintage siphons are almost always wrapped in a wire mesh—it wasn’t just for decoration; it was shrapnel netting.

This brings us to the subtle genius of the modern siphon’s design. At first glance, the iSi bottle, with its gleaming stainless steel mesh, looks like its fragile ancestor. But the bottle itself isn’t glass. It’s made from Polyethylene naphthalate (PEN), a high-performance, BPA-free polymer.

This is a deliberate and brilliant act of materials science. PEN has a higher tensile strength and, crucially, a much better gas barrier than common plastics like PET (the stuff of disposable water bottles). It can withstand the pressure without shattering, rendering the protective mesh a purely aesthetic homage to its past. The choice of PEN over glass is a classic engineering trade-off: sacrificing the “premium” feel and chemical inertness of glass for the vastly superior safety and durability of a modern polymer. It’s a silent testament to a century of progress in materials science, hiding in plain sight.

So, we have our pressurized, super-carbonated water, safely contained. We press the lever, and the liquid, driven by the pressure, streams into our glass. The pressure is suddenly released, and the dissolved $CO_2$ begins to escape, forming the beautiful cascade of bubbles we see. Now, for the final act. The sip.

Here is where our intuition fails us. We believe the tingle is the feeling of thousands of tiny bubble explosions. It makes for a nice image, but the reality is far more intricate and happens on a chemical, not a physical, level.

Your tongue is covered in enzymes, one of which is called carbonic anhydrase IV. When carbonated water hits your tongue, this enzyme instantly grabs the dissolved $CO_2$ and water molecules and combines them, creating carbonic acid. This acid then triggers specific receptors on your nerve cells—the same nociceptors and touch receptors that are part of the trigeminal nerve system.

This system is responsible for what scientists call chemesthesis: sensations that are not tastes or smells but chemical feelings. It’s the system that registers the burn of capsaicin from a chili pepper, the cool of menthol from mint, and the sharp bite of mustard. The “tingle” of your soda is, in essence, your brain interpreting a mild, localized acidic reaction as a unique tactile sensation. It’s a phantom touch, a trick of chemistry that our brains have learned to find intensely pleasurable.

This is why flat soda tastes so bland and cloyingly sweet. Without the carbonic acid to provide that sharp counterpoint, the underlying flavor is exposed and unbalanced. The fizz isn’t just a texture; it’s a fundamental component of the taste itself.

So the next time you enjoy that effervescent rush, take a moment to appreciate the journey. You’re not just having a drink. You are participating in the legacy of a curious 18th-century observer, leveraging a 19th-century law of physics, trusting in 21st-century materials science, and experiencing a complex neurological event that turns a simple chemical reaction into a delightful sensation. It is the marvel of the everyday, a reminder that within the most familiar things, there are entire worlds of science waiting to be discovered. All you have to do is take a sip.