Timing Poached Eggs by Levitation

There’s a professional method for poaching eggs that also makes great amateur entertainment. This is the restaurant technique in which eggs are cracked into boiling water in a tall stockpot, disappear into the depths, and—as if by magic!—bob up to the surface again just when they’re done: a handy way indeed to keep track of many eggs being cooked at once. The trick is the use of vinegar and salt (at about ½ and 1 tablespoon respectively for each quart of cooking water, 8 and 15g per liter) and keeping the water at the boil. The vinegar reacts with bicarbonate in the thin white to form tiny buoyant bubbles of carbon dioxide, which get trapped at the egg surface as its proteins coagulate. The salt increases the density of the cooking liquid just enough that the egg and three minutes’ worth of bubbles will float.