Gallium Is a Metal That Melts in Your Hand

Most metals treat melting as a serious event that requires a furnace, protective gear and a great deal of patience. Gallium is not most metals. It turns to liquid at about 29.8 degrees Celsius, roughly 85 degrees Fahrenheit, which is comfortably below the temperature of a human being. Cup a solid lump of it in your hand and within a couple of minutes you are holding a small, shimmering silver puddle that rolls around like liquid chrome.

Chemists have been quietly enjoying this for a century. The classic laboratory prank is the disappearing spoon: cast a teaspoon out of gallium, hand it to a guest with a hot cup of tea, and watch their face as the cutlery quietly gives up and sinks. Unlike mercury, gallium is not especially toxic to handle, which is the only reason this joke survived. It is still not a snack, and it will absolutely ruin a nice teaspoon.

Gallium also holds a grudge against aluminium. A single drop soaks into the metal and turns a sturdy aluminium bar into something you can crumble with your fingers, which is why airlines are famously unenthusiastic about it as carry-on luggage.

For all its theatrics, gallium does very grown-up work. It sits inside the blue and white LEDs lighting your street, the tiny fast chargers in your bag, and a great many microchips. Then, when it cools, it freezes solid again and expands slightly on the way, the same faintly rude trick water plays in a full bottle in the freezer.