Serious chefs have preferred copper mixing bowls for centuries. They are beautiful, of course, but their true beauty is in their superior function. No other container gives you the lush, stable peaks of meringue you can whip up in a copper bowl. Copper is equally handy when mashing potatoes to a fine froth or spinning heavy cream into whipped cream. But its classic bonafides come from copper's reaction with raw eggs basic chemistry with a culinary bonus.